Prostatic Neoplasms: Chen X

Chen N, Chen X, Huang R, Zeng H, Gong J, Meng W, Lu Y, Zhao F, Wang L, Zhou Q. · Laboratory of Pathology, Departments of Pathology and Urology, and Laboratory of Stem Cell Research, State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, China 610041. · J Biol Chem. · Pubmed #19211554 No free full text.

Abstract: The transcription factor hypoxia-inducible factor-1alpha (HIF-1alpha) plays pivotal roles in physiology and pathophysiology. Constitutive or hypoxia-induced HIF-1alpha overexpression is observed in many types of cancers including prostate adenocarcinoma, in which it is associated with resistance to apoptosis and therapeutic agents. BCL-xL, a hypoxia-responsive, anti-apoptotic protein of the Bcl-2 family, is also overexpressed in prostate carcinoma and many other cancers. Despite this connection, whether BCL-xL expression is directly regulated by HIF-1alpha is not known. We used prostate cancer PC-3 cell with constitutive high HIF-1alpha level as a model to address this important question. We first generated prostate cancer PC-3 cells in which HIF-1alpha was stably knocked-down (HIF-KD) by using small interference RNA. BCL-xL was dramatically decreased in HIF-KD PC-3 cells, in parallel with sensitization to apoptosis with caspase-3 activation as well as decreased cell proliferation. We then demonstrated that HIF-1alpha directly regulated BCL-xL transcription by binding to a hypoxia-responsive element in the BCL-xL promoter (-865 to -847) by reporter gene assay, chromatin immunoprecipitation, and electrophoretic mobility shift and supershift assays. HIF-1alpha-dependent BCL-xL overexpression may be an important mechanism by which HIF-1alpha protects prostate cancer cells from apoptosis and leads to treatment resistance.

Gao P, Sun X, Chen X, Subjeck J, Wang XY. · Department of Cellular Stress Biology, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA. · Cancer Immunol Immunother. · Pubmed #19142636 No free full text.

Abstract: It is well established that certain stress proteins or molecular chaperones are highly efficient in cross-presenting tumor-derived antigens, resulting in a potent antitumor immune response. In this study we demonstrate that genetic modification of weakly immunogenic murine prostate tumor cells (TRAMP-C2) by stable transfection with a secretable form of endoplasmic reticulum resident chaperone grp170 significantly enhances its immunogenicity in vivo. Generation of systemic antitumor immunity is indicated by the growth suppression of distant parental tumors, which is associated with increased tumor infiltration, elevated effector functions of CD8(+) T-cells. Immunization with inactivated grp170-secreting C2 cells augments a CD8(+) T-cell dependent, tumor-protective effect. Furthermore, infection of C2 tumor cells with a nonreplicating adenoviral vectors encoding secretable grp170 promotes tumor immunogenicity more effectively than plasmid transduction, as shown by the increased production of pro-inflammatory cytokine TNF-alpha by dendritice cells and enhanced therapeutic efficacy in treating pre-established tumors. Given a repertoire of undefined antigens in prostate tumor, manipulation of cellular compartmentalization of immuno-stimulatory chaperone grp170 to elicit systemic tumor immunity may be used to improve treatment outcomes for prostate cancer when combined with other treatment modalities.

Zhao Y, Yan Q, Long X, Chen X, Wang Y. · Key Laboratory for Oral Biomedical Engineering, Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan 430079, P.R. China. · Cell Biochem Funct. · Pubmed #18464297 No free full text.

Abstract: A significant proportion of prostate cancer patients treated with curative intent go on to develop advanced disease. At a fundamental biological level, very little is known about what makes the disease aggressive and metastatic. Observational pathology reports and experimental data suggest that epithelial-mesenchymal transition is involved in prostate cancer invasiveness. Here, we investigated vimentin expression of prostate cancer cells, and explored the potential mechanism of vimentin promoting prostate cancer cells invasion. Vimentin expression was not detected in well differentiated tumors or in moderately differentiated tumors, but the majority of poorly differentiated cancers (5/11 with negative bone scan, 11/14 bone with positive scan) and bone metastases (8/8) had high vimentin expression in tumor cells. Downregulation of vimentin expression in PC-3 cells by transfection with antisense-vimentin led to a significant decrease in tumor cells motility and invasive activity. Furthermore, the expression of E-cadherin was inversely associated with expression of vimentin. Our results suggest that vimentin affects prostate cancer cells motility and invasiveness.

Chen X, Gardner ER, Price DK, Figg WD. · Clinical Pharmacology Program, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD 20892, USA. · J Chromatogr Sci. · Pubmed #18402729 links to  free full text

Abstract: An analytical method is developed and validated for the quantitative determination of finasteride, a potent 5 alpha-reductase inhibitor, in human plasma. Calibration curves are linear in the concentration range of 1 to 100 ng/mL. Sample pretreatment involves a liquid-liquid extraction with ethyl acetate using 0.2 mL aliquots of plasma. Finasteride and the internal standard (beclomethasone) are separated on a Waters Symmetry Shield RP18 column (50 x 2.1 mm, 3.5 microm) and eluted using a gradient mobile phase composed of acetonitrile and 10mM ammonium acetate with 0.1% formic acid. The column eluant is monitored by mass spectrometry with electrospray ionization. A complete validation of the method is performed. For quality control samples at three different concentrations that were analyzed in quintuplicate, on six separate occasions, the accuracy and precision range from 95.2% to 101% and 3.4% to 7.3%, respectively. The developed method is subsequently applied to measure the steady state finasteride concentration of patients who participated in the Prostate Cancer Prevention Trial.

Lu Y, Wang J, Xu Y, Koch AE, Cai Z, Chen X, Galson DL, Taichman RS, Zhang J. · Department of Medicine, Pittsburgh VA Healthcare System, Research and Development, University of Pittsburgh, Pittsburgh, PA 15240, USA. · Mol Cancer Res. · Pubmed #18344492 links to  free full text

Abstract: A variety of tumor cells produce chemokines that promote tumor cell proliferation and chemotaxis. We previously reported that CXCL16 production is increased in aggressive prostate cancer cells compared with the less aggressive tumor cells and benign cells as identified in a cytokine antibody array. The functional contribution of CXCL16 in prostate cancer development has not yet been evaluated. Accordingly, mRNA expression of CXCL16 and its receptor, CXCR6, were determined by real-time reverse transcription-PCR in various cancer cell lines, including prostate cancer and tissues obtained from localized and metastatic prostate cancer. Consistent with our finding on CXCL16 protein production by prostate cancer cells, aggressive prostate cancer C4-2B and PC3 cells, as well as bone and liver metastatic tissues, expressed higher levels of both CXCL16 and CXCR6 mRNA compared with the less aggressive prostate cancer LNCaP cells, nonneoplastic PrEC and RWPE-1 cells, and benign prostate tissues, respectively. Furthermore, CXCR6 and CXCL16 protein expressions were examined in tissue specimens by immunohistochemistry. Immunohistochemical examination of CXCR6 expression showed strong epithelial staining that correlated with Gleason score, whereas CXCL16 staining was not. Finally, we found that both interleukin-1beta and tumor necrosis factor alpha significantly induced CXCL16 production by prostate epithelial cells, thereby indicating that inflammatory cytokines may play a role in the CXCL16 induction. CXCL16 was found to promote prostate cancer cell migration and invasion in vitro. Therefore, we concluded that CXCL16 functions, through CXCR6, as a novel chemotactic factor for prostate cancer cells.

Li H, Chen X, Calhoun-Davis T, Claypool K, Tang DG. · Department of Carcinogenesis, Science Park-Research Division, The University of Texas M.D. Anderson Cancer Center, Smithville, TX 78957, USA. · Cancer Res. · Pubmed #18339862 links to  free full text

Abstract: Primary keratinocytes exhibit three typical clonal morphologies represented by holoclones, meroclones, and paraclones, with holoclones containing self-renewing stem cells, and meroclones and paraclones containing more mature and differentiated cells. Interestingly, long-term-cultured human epithelial cancer cells in clonal cultures also form holoclones, meroclones, and paraclones, and tumor cell holoclones have been hypothesized to harbor stem-like cells or cancer stem cells. However, the key question of whether tumor cell holoclones genuinely contain tumor-initiating cells has not been directly addressed. Here, using PC3 human prostate carcinoma cells as a model, we provide direct experimental evidence that tumor cell holoclones contain stem-like cells that can initiate serially transplantable tumors. Importantly, holoclones derived from either cultured PC3 cells or holoclone-initiated tumors can be serially passaged and regenerate all three types of clones. In contrast, meroclones and paraclones cannot be continuously propagated and fail to initiate tumor development. Phenotypic characterizations reveal high levels of CD44, alpha(2)beta(1) integrin, and beta-catenin expression in holoclones, whereas meroclones and paraclones show markedly reduced expression of these stem cell markers. The present results have important implications in understanding morphologic heterogeneities and tumorigenic hierarchies in human epithelial cancer cells.

Li ZB, Wu Z, Chen K, Ryu EK, Chen X. · Molecular Imaging Program at Stanford, Department of Radiology, Biophysics, and Bio-X Program, Stanford University School of Medicine, Stanford, California 94305-5484, USA. · J Nucl Med. · Pubmed #18287274 links to  free full text

Abstract: Both bombesin (BBN) analogs and cyclic RGD peptides have been suitably radiolabeled for prostate cancer imaging. However, the limited expression of gastrin-releasing peptide receptor (GRPR) and integrin alpha(v)beta(3) as well as unfavorable in vivo kinetics limited further applications of these imaging agents. We hypothesize that a peptide ligand recognizing both GRPR and integrin will be advantageous because of its dual-receptor-targeting ability. METHODS: A BBN-RGD heterodimer was synthesized from bombesin(7-14) and c(RGDyK) through a glutamate linker and then labeled with (18)F via the N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB) prosthetic group. The receptor-binding characteristics and tumor-targeting efficacy of (18)F-FB-BBN-RGD were tested in vitro and in vivo. RESULTS: FB-BBN-RGD had comparable integrin alpha(v)beta(3)-binding affinity with c(RGDyK) and comparable GRPR-binding affinity with BBN(7-14). (18)F-FB-BBN-RGD had significantly higher tumor uptake compared with monomeric RGD and monomeric BBN peptide tracer analogs at all time points examined. The PC-3 tumor uptake of (18)F-FB-BBN-RGD was inhibited only partially in the presence of an excess amount of unlabeled BBN(7-14) or c(RGDyK) but was blocked completely in the presence of both BBN(7-14) and c(RGDyK). Compared with (18)F-FB-BBN and (18)F-FB-RGD, (18)F-FB-BBN-RGD also had improved pharmacokinetics, resulting in a significantly higher imaging quality. CONCLUSION: Dual integrin alpha(v)beta(3) and GRPR recognition showed significantly improved tumor-targeting efficacy and pharmacokinetics compared with (18)F-labeled RGD and BBN analogs. The same heterodimeric ligand design may also be applicable to other receptor system combinations and other imaging modalities.

Chen X, Guan J, Song Y, Chen P, Zheng H, Tang C, Wu Q. · Laboratory of Gene Function, School of Life Science, East China Normal University, Shanghai, People's Republic of China. · J Hum Genet. · Pubmed #18188667 No free full text.

Abstract: Insulin-like growth factor-I modulates cell growth and survival, and is thought to be important in tumor development. A (CA)19 repeat polymorphism in the promoter region of IGF-I gene that may affect transcription activity has been implicated as a risk factor for cancer, but individual studies have been inconclusive or controversial. Therefore, we performed a meta-analysis of 17 studies with IGF-I (CA)19 repeat genotyping on 8,799 patients and 13,901 controls. There were seven studies with prostate cancer (2,307 cases; 2,622 controls), seven studies with breast cancer (3,533 cases; 7,771 controls), and three studies with colorectal cancer (2,959 cases; 3,508 controls). Overall, the random effects odds ratio (OR) for the (CA)19 versus non-(CA)19 allele was 1.03 [95% confidence interval (CI), 0.95-1.11], with some between-study heterogeneity (P < 0.0001). There was no suggestion of an overall effect either in recessive or dominant modeling of (CA)19 allele effects, and the comparison of (CA)19 homozygosity versus non-(CA)19 homozygosity also showed no differential susceptibility to cancer (OR, 0.99; 95% CI, 0.84-1.16). No effect of (CA)19 was seen in subjects of breast cancer (seven comparisons, OR = 1.03; 95% CI, 0.90-1.17, P = 0.005 for heterogeneity), prostate cancer (seven comparisons, OR = 1.08; 95% CI, 0.88-1.27; P = 0.0002 for heterogeneity) and colorectal cancer (three comparisons, OR = 0.96; 95% CI, 0.89-1.03, P = 0.36, no significant between-study heterogeneity). There was also no evidence that the (CA)19 allele associated with the risk of cancer in Caucasians and Asians. The meta-analysis shows that this (CA)19 repeat polymorphism is unlikely to be a major determinant of susceptibility to cancer on a wide population basis. However, a larger single study is required to further evaluate the association IGF-I (CA)19 polymorphisms and the cancer risk in a specific population.

Bhatia B, Multani AS, Patrawala L, Chen X, Calhoun-Davis T, Zhou J, Schroeder L, Schneider-Broussard R, Shen J, Pathak S, Chang S, Tang DG. · Department of Carcinogenesis, University of Texas MD Anderson Cancer Center, Science Park-Research Division, Smithville, TX 78957, USA. · Int J Cancer. · Pubmed #18059027 No free full text.

Abstract: Normal human prostate (NHP) epithelial cells undergo senescence in vitro and in vivo but the potential role of senescent NHP cells in prostate tumorigenesis remain unclear. Here we show that senescent NHP cells enhance the in vivo tumorigenicity of low-tumorigenic LNCaP prostate cancer and low/non-tumorigenic subset of cells (called L cells) isolated from multiple bulk-cultured prostate (and other) cancer cell lines. Subsequent studies suggest cell-cell fusion as a potential mechanism for senescent NHP cell-enhanced tumor development. Using fluorescently tagged tumor cells and/or NHP cells, we find that NHP cells, like fibroblasts, can undergo fusion with unfractionated tumor cells or the L cells. Using 293T-L cells as the model cell system, we verify NHP and 293T-L cell fusion by using differential RT-PCR, karyotyping, and gene expression analyses. Further experiments demonstrate that senescent NHP cells that have lost progenitor markers, accumulated p16INK4a (p16) protein expression, and acquired the AR mRNA expression, appear to be the preferential fusion targets. Strikingly, the tumorigenicity of the NHP/293T-L hybrid cells was inhibited by exogenous p16 as well as hTERT. Chromosomal analyses revealed that hTERT probably inhibited the in vivo tumorigenicity by maintaining genomic stability. These results suggest that senescent NHP cells, like senescent fibroblasts, may promote tumor development and that one of the mechanisms underlying the senescent NHP cell-enhanced tumorigenicity could be through cell fusion.

Sallman DA, Chen X, Zhong B, Gilvary DL, Zhou J, Wei S, Djeu JY. · Immunology Program, H. Lee Moffitt Cancer Center, Department of Interdisciplinary, Oncology, University of South Florida College of Medicine, Tampa, FL, USA. · Mol Cancer Ther. · Pubmed #18025278 links to  free full text

Abstract: One of the major obstacles in curing prostate cancer is the development of drug resistance to docetaxel, which is the gold standard for the treatment of this disease. It is not only imperative to discover the molecular basis of resistance but also to find therapeutic agents that can disrupt the resistant pathways. Based on initial findings that docetaxel-resistant PC3-DR and DU145-DR prostate tumor cell lines express tumor necrosis factor-related apoptosis inducing ligand (TRAIL) receptors, we examined whether TRAIL could be used as an alternative method to kill PC3-DR and DU145-DR cells. However, these tumor cells were found to be TRAIL resistant. Because PC3-DR and DU-145-DR cells were previously shown by us to be clusterin positive, we examined if clusterin could play a role in TRAIL resistance. We found that resveratrol could sensitize docetaxel-resistant tumor cells to TRAIL, and it worked by blocking clusterin expression. In particular, small interfering RNA clusterin expression in the cell lines was sufficient to produce apoptosis by TRAIL. Further analysis indicated that resveratrol functions as an effective tyrosine kinase inhibitor, similar to its analogue, piceatannol, and could inhibit Src and Jak kinases, thus resulting in loss of Stat1 activation. We have shown earlier that Stat1 is essential for gene transcription of clusterin. These results, taken together, show that resveratrol could be a useful new therapeutic agent to combat docetaxel resistance.

Garcia FU, Haber MM, Chen X. · Department of Pathology and Laboratory Medicine, Drexel University College of Medicine, Philadelphia, PA 19102, USA. · Prostate. · Pubmed #17879949 No free full text.

Abstract: BACKGROUND: Benign prostatic hyperplasia and prostatic adenocarcinoma exhibit prominent zonal predilections. Basal cells from the transitional zone and from the peripheral zone are postulated to have different underlying biological properties. We studied basal cells in both prostatic zones. METHODS: Tissue microarrays (TMA) were prepared from 65 whole-mounted prostatectomy specimens with prostatic adenocarcinoma. The transitional zone and peripheral zone were sampled from each prostate. TMA sections were stained with a basal cell cocktail (CK 34betaE12 + p63). The immunostaining pattern and the morphology of basal cells were recorded. RESULTS: Triangular-shaped basal cells were highlighted by CK 34betaE12 cytoplasmic and p63 nuclear staining. These basal cells had their long axis oriented perpendicular to the basement membrane and their apex toward the lumen interdigited between secretory luminal cells. This morphology was seen in the majority of peripheral zone benign prostatic glands (92.0%) but only a minority of transitional zone benign prostatic glands (18.0%). Basal cells of the transitional zone showed weak or absent CK 34betaE12 staining in 65.9% of glands while maintaining p63. All glands with high-grade prostatic intraepithelial neoplasia (HGPIN) contained the triangular basal cells. In addition, basal cell clusters were identified in 8.7% of peripheral zone glands and 5.2% of HGPIN glands. CONCLUSIONS: Our results indicate that the basal cell morphology and the basal cell immunophenotype have a zonal variation. The finding of a unique morphology of basal cells and the presence of basal cell clusters in the peripheral zone suggests that the peripheral zone might be the stem/progenitor cell-rich area in the human prostates.

Chen X, Yu H, Shen S, Yin J. · Department of Food Science and Nutrition, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310029, PR China. · J Trace Elem Med Biol. · Pubmed #17499153 No free full text.

Abstract: Green tea has chemo-preventive effects to human carcinoma including prostate cancer. Epigallocatechin gallate (EGCG) is the major active component in green tea. Zn(2+) is indispensable to our health, and plays an important role in the normal function and pathology of the prostate gland, and might be a good marker for diagnosing prostate cancer. Effects of Zn(2+), EGCG and their interactions on the growth of androgen-insensitive prostate cancer cell (PC-3) were investigated in the present paper. The results show that Zn(2+) and EGCG inhibited the growth of PC-3 cells in a time- and dose-dependent manner, but effects of interactions of EGCG with Zn(2+) were extremely dependent on their concentrations and added orders. Inhibitory effects of Zn(2+) were significantly decreased in the presence of EGCG on PC-3 cell growth. Therefore, we hypothesize that complexation of EGCG with Zn(2+) might be responsible for the observed decrease of the bioactivities of Zn(2+) against PC-3 cells.

Ding WX, Ni HM, Gao W, Hou YF, Melan MA, Chen X, Stolz DB, Shao ZM, Yin XM. · Departments of Pathology and Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pennsylvania 15261, USA. · J Biol Chem. · Pubmed #17135238 links to  free full text

Abstract: Autophagy is a cellular response to adverse environment and stress, but its significance in cell survival is not always clear. Here we show that autophagy could be induced in the mammalian cells by chemicals, such as A23187, tunicamycin, thapsigargin, and brefeldin A, that cause endoplasmic reticulum stress. Endoplasmic reticulum stress-induced autophagy is important for clearing polyubiquitinated protein aggregates and for reducing cellular vacuolization in HCT116 colon cancer cells and DU145 prostate cancer cells, thus mitigating endoplasmic reticulum stress and protecting against cell death. In contrast, autophagy induced by the same chemicals does not confer protection in a normal human colon cell line and in the non-transformed murine embryonic fibroblasts but rather contributes to cell death. Thus the impact of autophagy on cell survival during endoplasmic reticulum stress is likely contingent on the status of cells, which could be explored for tumor-specific therapy.

Cai W, Wu Y, Chen K, Cao Q, Tice DA, Chen X. · The Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University School of Medicine, Stanford, CA 94305-5484, USA. · Cancer Res. · Pubmed #17018625 links to  free full text

Abstract: Abegrin (MEDI-522 or Vitaxin), a humanized monoclonal antibody against human integrin alpha(v)beta(3), is in clinical trials for cancer therapy. In vivo imaging using Abegrin-based probes is needed for better treatment monitoring and dose optimization. Here, we conjugated Abegrin with macrocyclic chelating agent 1,4,7,10-tetra-azacylododecane N,N',N'',N'''-tetraacetic (DOTA) at five different DOTA/Abegrin ratios. The conjugates were labeled with (64)Cu (half-life = 12.7 hours) and tested in three human (U87MG, MDA-MB-435, and PC-3) and one mouse (GL-26) tumor models. The in vitro and in vivo effects of these (64)Cu-DOTA-Abegrin conjugates were evaluated. The number of DOTA per Abegrin varied from 1.65 +/- 0.32 to 38.53 +/- 5.71 and the radiolabeling yield varied from 5.20 +/- 3.16% to 88.12 +/- 6.98% (based on 2 mCi (64)Cu per 50 microg DOTA-Abegrin conjugate). No significant difference in radioimmunoreactivity was found among these conjugates (between 59.78 +/- 1.33 % and 71.13 +/- 2.58 %). Micro-positron emission tomography studies revealed that (64)Cu-DOTA-Abegrin (1,000:1) had the highest tumor activity accumulation (49.41 +/- 4.54% injected dose/g at 71-hour postinjection for U87MG tumor). The receptor specificity of (64)Cu-DOTA-Abegrin was confirmed by effective blocking of MDA-MB-435 tumor uptake with coadministration of nonradioactive Abegrin. (64)Cu-DOTA-IgG exhibited background level tumor uptake at all time points examined. Integrin alpha(v)beta(3)-specific tumor imaging using (64)Cu-DOTA-Abegrin may be translated into the clinic to characterize the pharmacokinetics, tumor targeting efficacy, dose optimization, and dose interval of Abegrin and/or Abegrin conjugates. Chemotherapeutics or radiotherapeutics using Abegrin as the delivering vehicle may also be effective in treating integrin alpha(v)beta(3)-positive tumors.

Man YG, Zhao C, Chen X. · Department of Gynecologic and Breast Pathology, Armed Forces Institute of Pathology and American Registry of Pathology, Washington DC 20306-6000, USA. · Pathol Res Pract. · Pubmed #16842934 No free full text.

Abstract: Immunohistochemical staining for cytokeratin (CK) 34ssE12 has been routinely used to elucidate prostate basal cells for differentiation between non-invasive and invasive lesions. Our previous studies, however, revealed that some morphologically distinct basal cells observed on H&E-stained sections completely lacked CK34ssE12 expression. Our current study attempted to assess whether these basal cells would also lack the expression of other phenotypic markers, and whether basal cell alterations would affect the proliferation status of the associated tumor cells. Consecutive sections from prostate tumors with large basal cell clusters that were morphologically distinct in H&E sections but were completely negative for CK 34ssE12 were morphologically and immunohistochemically assessed with a panel of basal cell phenotypic and other markers. In addition to CK 34ssE12, these basal cells also completely lacked the expression of other phenotypic markers, including CK5, CK14, p63, and maspin, in contrast to adjacent basal cells, which were strongly positive for these markers. Tumors surrounded by basal cell layers that lack the expression of basal cell phenotypic markers showed a significantly higher rate of cell proliferation and mast cell infiltration than their counterparts. These findings suggest that basal cells might be targets of a variety of pathological alterations, which could significantly impact biological presentations of associated tumor cells.

Hu X, Chen X, Ping H, Chen Z, Zeng F, Lu G. · Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China. · J Huazhong Univ Sci Technolog Med Sci. · Pubmed #16696322 No free full text.

Abstract: To study the expression and significance of the serine protease Omi/HtrA2 in prostate cancer and benign prostatic hyperplasia. The expression of Omi/HtrA2 was assayed by means of immunohistochemical technique in 41 prostate cancer (Cap), 20 benign prostatic hyperplasia (BPH) and 10 normal prostate (NP) specimens. Omi/HtrA2 expression was positive in 30 (73.17%) prostate cancer specimens, and the positive rate of Omi/HtrA2 was lower in well differentiated than in poorly and moderately differentiated groups (P < 0.05). By contrast, the cells in normal prostate and benign prostatic hyperplasia groups showed no or weak expression of Omi/HtrA2. Prostate cancer cells in vivo may need Omi/HtrA2 expression for apoptosis, and that Omi/HtrA2 expression might be involved in prostate cancer development.

Yang YS, Zhang X, Xiong Z, Chen X. · Department of Radiology and Bio-X Program, The Molecular Imaging Program at Stanford (MIPS), Stanford University School of Medicine, Stanford, CA 94305-5484, USA. · Nucl Med Biol. · Pubmed #16631086 No free full text.

Abstract: Bombesin (BBN), an analog of human gastrin-releasing peptide (GRP), binds to the GRP receptor (GRPR) with high affinity and specificity. Overexpression of GRPR has been discovered in mostly androgen-independent human prostate tissues and, thus, provides a potential target for prostate cancer diagnosis and therapy. We have previously demonstrated the feasibility of the positron emission tomography (PET) imaging using 64Cu-1,4,7,10-tetraazadodecane-N,N',N'',N'''-tetraacetic acid (DOTA)-[Lys3]BBN to detect GRPR-positive prostate cancer. In this study, we compared the receptor affinity, metabolic stability, tumor-targeting efficacy, and pharmacokinetics of a truncated BBN analog 64Cu-DOTA-Aca-BBN(7-14) with 64Cu-DOTA-[Lys3]BBN. Binding of each DOTA conjugate to GRPR on PC-3 and 22Rv1 prostate cancer cells was evaluated with competitive binding assay using 125I-[Tyr4]BBN as radioligand. In vivo pharmacokinetics was determined on male nude mice subcutaneously implanted with PC-3 cells. Dynamic microPET imaging was performed to evaluate the systemic distribution of the tracers. Metabolic stability of the tracers in blood, urine, tumor, liver and kidney was studied using high-performance liquid chromatography. The results showed that 125I-[Tyr4]BBN has a K(d) of 14.8+/-0.4 nM against PC-3 cells, and the receptor concentration on PC-3 cell surface is approximately 2.7+/-0.1 x 10(6) receptors per cell. The 50% inhibitory concentration value for DOTA-Aca-BBN(7-14) is 18.4 +/- 0.2 nM, and that for DOTA-[Lys3]BBN is 2.2 +/- 0.5 nM. DOTA-[Lys3]BBN shows a better tumor contrast and absolute tumor activity accumulation compared to DOTA-Aca-BBN(7-14). Studies on metabolic stability for both tracers on organ homogenates showed that 64Cu-DOTA-[Lys3]BBN is relatively stable. This study demonstrated that both tracers are suitable for targeted PET imaging to detect the expression of GRPR in prostate cancer, while 64Cu-DOTA-[Lys3]BBN may have a better potential for clinical translation.

Chen X, Zhao J, Salim S, Garcia FU. · Department of Pathology and Laboratory Medicine, Drexel University College of Medicine, Philadelphia, PA 19102, USA. · Hum Pathol. · Pubmed #16613330 No free full text.

Abstract: Intraprostatic spermatozoa (IS) have been demonstrated in only 2 articles in the literature reporting on postmortem prostates. Intraprostatic spermatozoa have not been previously described in radical prostatectomies. This is the first study that describes the presence of IS in radical prostatectomies with prostatic carcinoma (PC) and its association with atrophy. We examined whole mount sagittal sections from 69 consecutive radical prostatectomy cases for PC. A central section including the seminal vesicle ejaculatory duct urethra complex (SVEDU) from each case was stained with Berg's stain to identify spermatozoa and their location. The extent and the type of atrophy were assessed on the entire prostate by using a grid method. Eighteen cases (26.1%) revealed spermatozoa both in the SVEDU and in the prostate (IS) (group 1). Twenty-two cases (31.9%) showed spermatozoa exclusively in the SVEDU but not in the prostate (group 2). The remaining 29 cases (42.0%) had no spermatozoa in either site. Location of IS was 72.2% peripheral zone, 22.2% central zone, and 5.6% transitional zone. Intraprostatic spermatozoa were frequently seen accompanied by inflammatory infiltrate in the periglandular stroma. The extent of atrophy was greater in group 1 than in group 2 (25.7% versus 15.3%; P = .006). Postatrophic hyperplasia was seen more frequently in group 1 than in group 2 (72.2% versus 40.9%; P = .025). In conclusion, the frequency of IS is 26.1% when including all prostates and 45.0% when including prostates with evidence of residual ejaculate (spermatozoa in the SVEDU), more than previously reported. Intraprostatic spermatozoa are predominantly located in the peripheral zone similar to atrophy and PC. Prostates with IS have larger atrophic areas and increased frequency of postatrophic hyperplasia. The role of IS in the pathogenesis of prostate inflammation and atrophy should be investigated.

Zhang X, Cai W, Cao F, Schreibmann E, Wu Y, Wu JC, Xing L, Chen X. · Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University School of Medicine, Stanford, California 94305-5484, USA. · J Nucl Med. · Pubmed #16513619 links to  free full text

Abstract: The gastrin-releasing peptide receptor (GRPR) is found to be overexpressed in a variety of human tumors. The aim of this study was to develop 18F-labeled bombesin analogs for PET of GRPR expression in prostate cancer xenograft models. METHODS: [Lys3]Bombesin ([Lys3]BBN) and aminocaproic acid-bombesin(7-14) (Aca-BBN(7-14)) were labeled with 18F by coupling the Lys3 amino group and Aca amino group, respectively, with N-succinimidyl-4-18F-fluorobenzoate (18F-SFB) under slightly basic condition (pH 8.5). Receptor-binding affinity of FB-[Lys3]BBN and FB-Aca-BBN(7-14) was tested in PC-3 human prostate carcinoma cells. Internalization and efflux of both radiotracers were also evaluated. Tumor-targeting efficacy and in vivo kinetics of both radiotracers were examined in male athymic nude mice bearing subcutaneous PC-3 tumors by means of biodistribution and dynamic microPET imaging studies. 18F-FB-[Lys3]BBN was also tested for orthotopic PC-3 tumor delineation. Metabolic stability of 18F-FB-[Lys3]BBN was determined in mouse blood, urine, liver, kidney, and tumor homogenates at 1 h after injection. RESULTS: The typical decay-corrected radiochemical yield was about 30%-40% for both tracers, with a total reaction time of 150 +/- 20 min starting from 18F-. 18F-FB-[Lys3]BBN had moderate stability in the blood and PC-3 tumor, whereas it was degraded rapidly in the liver, kidneys, and urine. Both radiotracers exhibited rapid blood clearance. 18F-FB-[Lys3]BBN had predominant renal excretion. 18F-FB-Aca-BBN(7-14) exhibited both hepatobiliary and renal clearance. Dynamic microPET imaging studies revealed that the PC-3 tumor uptake of 18F-FB-[Lys3]BBN in PC-3 tumor was much higher than that of 18F-FB-Aca-BBN(7-14) at all time points examined (P < 0.01). The receptor specificity of 18F-FB-[Lys3]BBN in vivo was demonstrated by effective blocking of tumor uptake in the presence of [Tyr4]BBN. No obvious blockade was found in PC-3 tumor when 18F-FB-Aca-BBN(7-14) was used as radiotracer under the same condition. 18F-FB-[Lys3]BBN was also able to visualize orthotopic PC-3 tumor at early time points after tracer administration, at which time minimal urinary bladder activity was present to interfere with the receptor-mediated tumor uptake. CONCLUSION: This study demonstrates that 18F-FB-[Lys3]BBN and PET are suitable for detecting GRPR-positive prostate cancer in vivo.

Zhang X, Xiong Z, Wu Y, Cai W, Tseng JR, Gambhir SS, Chen X. · Molecular Imaging Program at Stanford, MIPS, and Bio-X Program, Department of Radiology, Stanford University, California 94305-5484, USA. · J Nucl Med. · Pubmed #16391195 links to  free full text

Abstract: The development of noninvasive methods to visualize and quantify integrin alpha(v)beta(3) expression in vivo appears to be crucial for the success of antiangiogenic therapy based on integrin antagonism. Precise documentation of integrin receptor levels will allow appropriate selection of patients who will most likely benefit from an antiintegrin treatment regimen. Imaging can also be used to provide an optimal dosage and time course for treatment based on receptor occupancy studies. In addition, imaging integrin expression will be important to evaluate antiintegrin treatment efficacy and to develop new therapeutic drugs with favorable tumor targeting and in vivo kinetics. We labeled the dimeric RGD peptide E[c(RGDyK)](2) with (18)F and evaluated its tumor-targeting efficacy and pharmacokinetics of (18)F-FB-E[c(RGDyK)](2) ((18)F-FRGD2). METHODS: E[c(RGDyK)](2) was labeled with (18)F by conjugation coupling with N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB) under a slightly basic condition. The in vivo metabolic stability of (18)F-FRGD2 was determined. The diagnostic value after injection of (18)F-FRGD2 was evaluated in various xenograft models by dynamic microPET followed by ex vivo quantification of tumor integrin level. RESULTS: Starting with (18)F(-) Kryptofix 2.2.2./K(2)CO(3) solution, the total reaction time for (18)F-FRGD2, including final high-performance liquid chromatography purification, is about 200 +/- 20 min. Typical decay-corrected radiochemical yield is 23% +/- 2% (n = 20). (18)F-FRGD2 is metabolically stable. The binding potential extrapolated from graphical analysis of PET data and Logan plot correlates well with the receptor density measured by sodium dodecyl sulfate polyacrylamide electrophoresis and autoradiography in various xenograft models. The tumor-to-background ratio at 1 h after injection of (18)F-FRGD2 also gives a good linear relationship with the tumor tissue integrin level. CONCLUSION: The dimeric RGD peptide tracer (18)F-FRGD2, with high integrin specificity and favorable excretion profile, may be translated into the clinic for imaging integrin alpha(v)beta(3) expression. The binding potential calculated from simplified tracer kinetic modeling such as the Logan plot appears to be an excellent indicator of tumor integrin density.

Hao P, Chen X, Geng H, Gu L, Chen J, Lu G. · Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China. · J Huazhong Univ Sci Technolog Med Sci. · Pubmed #15791851 No free full text.

Abstract: To study the expression of hypoxia inducible factor-1alpha (HIF-1alpha) protein in prostate cancer (Pca) and its biological significance, the expression of HIF-1alpha was assayed by means of immunohistochemical technique in 42 prostate cancer, 12 prostatic intraepithelial neoplasm (PIN) and 9 normal prostate tissue (NP) specimens. Western blot was used to examine the expression of HIF-1alpha in prostate cancer cell line (PC-3M) induced by different oxygen tension. HIF-1alpha expression was positive in 33 Pca and 9 PIN specimens, and the positive rate of HIF-1alpha was higher in distant metastasis patients than in patients without metastasis of prostate cancer (P<0.05), while there was no expression of HIF-1alpha in NP. The level of HIF-1alpha in PC-3M significantly increased with the decrease of oxygen tension (P<0.01). Overexpression of HIF-1alpha is the preliminary event of the formation of Pca, which may induce carcinoma into malignant phenotype. Thus it may serve as an early diagnosis marker and the novel target for Pca treatment.

Shankar S, Chen X, Srivastava RK. · Department of Pharmaceutical Sciences, University of Maryland, 20 N Pine Street, Baltimore, MD 2120-1180, USA. · Prostate. · Pubmed #15389801 No free full text.

Abstract: BACKGROUND: Tumor necrosis factor related apoptosis-inducing ligand/Apo2 ligand (TRAIL/Apo-2L) is a novel anticancer agent, capable of inducing apoptosis preferentially in tumor and transformed cells. TRAIL-R1/death receptor (DR)4 and TRAIL-R2/DR5 are members of the tumor necrosis factor (TNF) receptor family, and can be activated by the TRAIL. We examined the clinical potential of chemotherapeutic drugs and TRAIL for the treatment of prostate cancer. METHODS: Prostate and bladder cancer cells were exposed to chemotherapeutic drugs (paclitaxel, vincristine, vinblastine, etoposide, doxorubicin, and camptothecin) and TRAIL. Cell viability was measured by sodium 3'[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis (4-methoxy-6-nitro) assay; expressions of death receptors and Bcl-2 family members were measured by Western blotting, ELISA and ribonuclease protection assay. PC-3 tumor cells xenografted athymic nude mice were exposed to chemotherapeutic drugs and TRAIL, either alone or in combination, to measure tumor growth and survival of mice. Apoptosis was measured by annexin V-FITC/propidium iodide staining, and terminal deoxynucleotidyltransferase-mediated nick end labeling assay. Caspase-3 activity was measured by the Western blotting and immunohistochemistry. RESULTS: TRAIL induced apoptosis with varying sensitivity. Chemotherapeutic drugs (paclitaxel, vincristine, vinblastine, etoposide, doxorubicin, and camptothecin) significantly augmented TRAIL-induced apoptosis in cancer cells through up-regulation of DR4, DR5, Bax, and Bak, and induction of caspase activation. Mitochondrial pathway enhanced the synergistic interactions between drugs and TRAIL. The sequential treatment of mice with chemotherapeutic drugs followed by TRAIL induced caspase-3 activity, and apoptosis, inhibited angiogenesis, completely eradicated the established tumors, and enhanced survival of mice. CONCLUSIONS: Chemotherapeutic drugs can be used to enhance the therapeutic potential of TRAIL in prostate cancer.

Chen X, Park R, Hou Y, Tohme M, Shahinian AH, Bading JR, Conti PS. · PET Imaging Science Center, University of Southern California Keck School of Medicine, Los Angeles 90033, USA. · J Nucl Med. · Pubmed #15299066 links to  free full text

Abstract: Overexpression of gastrin-releasing peptide (GRP) receptor (GRPR) in both androgen-dependent (AD) and androgen-independent (AI) human neoplastic prostate tissues provides an attractive target for prostate cancer imaging and therapy. The goal of this study was to develop (64)Cu-radiolabeled GRP analogs for PET imaging of GRPR expression in prostate cancer xenografted mice. METHODS: [Lys(3)]bombesin ([Lys(3)]BBN) was conjugated with 1,4,7,10-tetraazadodecane-N,N',N",N"'-tetraacetic acid (DOTA) and labeled with the positron-emitting isotope (64)Cu (half-life = 12.8 h, 19% beta(+)). Receptor binding of DOTA-[Lys(3)]BBN and internalization of (64)Cu-DOTA-[Lys(3)]BBN by PC-3 prostate cancer cells were measured. Tissue biodistribution, microPET, and whole-body autoradiographic imaging of the radiotracer were also investigated in PC-3 (AI)/CRW22 (AD) prostate cancer tumor models. RESULTS: A competitive receptor- binding assay using (125)I-[Tyr(4)]BBN against PC-3 cells yielded a 50% inhibitory concentration value of 2.2 +/- 0.5 nmol/L for DOTA-[Lys(3)]BBN. Incubation of cells with the (64)Cu-labeled radiotracer showed temperature- and time-dependent internalization. At 37 degrees C, >60% of the tracer was internalized within the first 15 min and uptake remained constant for 2 h. Radiotracer uptake was higher in AI PC-3 tumor (5.62 +/- 0.08 %ID/g at 30 min after injection, where %ID/g is the percentage of injected dose per gram) than in AD CWR22 tumor (1.75 +/- 0.05 %ID/g at 30 min after injection). Significant accumulation of the activity in GRPR-positive pancreas was also observed (10.4 +/- 0.15 %ID/g at 30 min after injection). Coinjection of a blocking dose of [Lys(3)]BBN inhibited the activity accumulation in PC-3 tumor and pancreas but not in CWR22 tumor. microPET and autoradiographic imaging of (64)Cu-DOTA-[Lys(3)]BBN in athymic nude mice bearing subcutaneous PC-3 and CWR22 tumors showed strong tumor-to-background contrast. CONCLUSION: This study demonstrates that PET imaging of (64)Cu-DOTA-[Lys(3)]BBN is able to detect GRPR-positive prostate cancer.

Xu T, Chen X, Wang XF, Hou SK, Zhu JC, Zhang XD, Huang XB. · Department of Urology, Peking University People Hospital, Beijing 100044, China. · Beijing Da Xue Xue Bao. · Pubmed #15100735 No free full text.

Abstract: OBJECTIVE: To study the prostate specific antigen (PSA), prostate-specific membrane antigen (PSMA) and human glandular kallikrein (hK2) mRNA in peripheral blood samples of prostate cancer (PC) patients with bone metastasis by nested reverse transcriptase polymerase chain reaction (RT-PCR) based assay, and to discuss their clinical implications. METHODS: Samples of peripheral blood were analyzed by nested RT-PCR to identify PSA, PSMA and hK2 mRNA expression. RESULTS: RT-PCR assay was applied to identify the PSA, PSMA and hK2 mRNA expressing LNCaP cells, which were diluted by lymphocytes to 10(-6), 10(-6) and 10(-7) separately. Positive rates of the three markers in newly diagnosed PC patients with bone metastasis were 59.45%, 51.35% and 59.46% respectively, and 32.43% cases showed three positives. In PC patients who had developed bone metastasis after endocrine therapy, the positive rates were 57.14%, 85.71% and 83.33% respectively, and 52.48% cases showed three positives. All samples were negative in regional PC patients and healthy individuals, and all samples were positive for beta actin mRNA, the internal control. CONCLUSION: Nested RT-PCR based assay for PSA, PSMA or hK2 mRNA helps to detect prostate cancer cells in the circulation system, thus providing evidence for occult metastasis. PSMA and hK2 were advisable markers to monitor disease progression after androgen blockage. Combined assays of PSMA and hK2 are suitable for patients who underwent endocrine therapy, and combined assays of the three markers have enhanced sensitivity.

Bemis L, Chan DA, Finkielstein CV, Qi L, Sutphin PD, Chen X, Stenmark K, Giaccia AJ, Zundel W. · Departments of Medicine and Biochemistry, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA. · Genes Dev. · Pubmed #15082527 links to  free full text

Abstract: Mammalian oxygen homeostasis is dependent on the HIF family of transcription factors. The CSN subunit, CSN5, binds both the CODD of HIF-1 alpha and the pVHL tumor suppressor. High CSN5 expression generates a pVHL-independent form of CSN5 that stabilizes HIF-1 alpha aerobically by inhibiting HIF-1 alpha prolyl-564 hydroxylation. Aerobic CSN5 association with HIF-1 alpha occurs independently of the CSN holocomplex, leading to HIF-1 alpha stabilization independent of Cullin 2 deneddylation. CSN5 weakly associates with HIF-1 alpha under hypoxia, but is required for optimal hypoxia-mediated HIF-1 alpha stabilization. These results indicate that CSN5 regulates aerobic as well as hypoxic HIF-1 alpha stability by different mechanisms during oncogenesis.