Growth delay of human bladder cancer cells by Prostate Stem Cell Antigen downregulation is associated with activation of immune signaling pathways

Potential association between PSCA rs2976395 functional variant and pancreatic cancer risk

Correlated regions of systemic interindividual variation (CoRSIV) represent a small proportion of the human genome showing DNA methylation patterns that are the same in all human tissues, are different among individuals, and are partially regulated by genetic variants in cis. In this study we aimed at investigating single-nucleotide polymorphisms (SNPs) within CoRSIVs and their involvement with pancreatic ductal adenocarcinoma (PDAC) risk. We analyzed 29,099 CoRSIV-SNPs and 133,615 CoRSIV-mQTLs in 14,394 cases and 247,022 controls of European and Asian descent. We observed that the A allele of the rs2976395 SNP was associated with increased PDAC risk in Europeans (p = 2.81 × 10-5). This SNP lies in the prostate stem cell antigen gene and is in perfect linkage disequilibrium with a variant (rs2294008) that has been reported to be associated with risk of many other cancer types. The A allele is associated with the DNA methylation level of the gene according to the PanCan-meQTL database and with overexpression according to QTLbase. The expression of the gene has been observed to be deregulated in many tumors of the gastrointestinal tract including pancreatic cancer; however, functional studies are needed to elucidate the function relevance of the association.

Significance of PSCA as a novel prognostic marker and therapeutic target for cancer

One of the contributing factors in the diagnosis and treatment of most cancers is the identification of their surface antigens. Cancer tissues or cells have their specific antigens. Some antigens that are present in many cancers elicit different functions. One of these antigens is the prostate stem cell antigen (PSCA) antigen, which was first identified in the prostate. PSCA is a cell surface protein that has different functions in different tissues. It can play an inhibitory role in cell proliferation as well as a tumor-inducing role. PSCA has several genetic variants involved in cancer susceptibility in some tissues, so identifying the characteristics of this antigen and its relationship with clinical features can provide more information on diagnosis and treatment of patients with cancers. Most studies on the PSCA have focused on prostate cancer. While it is also expressed in other cancers, little attention has been paid to its role as a valuable diagnostic, prognostic, and therapeutic tool in other cancers. PSCA has several genetic variants that seem to play a significant role in cancer susceptibility in some tissues, so identifying the characteristics of this antigen and its relationship and variants with clinical features can be beneficial in concomitant cancer therapy and diagnosis, as theranostic tools. In this study, we will review the alteration of the PSCA expression and its polymorphisms and evaluate its clinical and theranostics significance in various cancers.

SNP rs2920280 in PSCA Is Associated with Susceptibility to Gastric Mucosal Atrophy and Is a Promising Biomarker in Japanese Individuals with Helicobacter pylori Infection

Helicobacter pylori infection results in gastric cancer (GC) with gastric mucosal atrophy (GMA). Some single-nucleotide polymorphisms (SNPs) in the prostate stem cell antigen gene (PSCA) are associated with GC and duodenal ulcers. However, the relationship of other identified SNPs in PSCA with these diseases remains unclear. Herein, the association between PSCA SNPs and GMA among 195 Japanese individuals with H. pylori infection was evaluated. The definition of GMA or non-GMA was based on serum pepsinogen levels or endoscopic findings. Five tag PSCA SNPs were analyzed using PCR high-resolution melting curve analysis with nonlabelled probes. The frequencies of alleles and the genotypes of each tag SNP were compared between the GMA and non-GMA groups. Subsequently, a genetic test was performed using associated SNPs as biomarkers to detect patients developing GMA. Two tag PSCA SNPs (rs2920280 and rs2294008) were related to GMA susceptibility. Individuals with the rs2920280 G/G genotype or the rs2294008 T/T genotype in PSCA had 3.5- and 2.1-fold susceptibility to GMA, respectively. In conclusion, SNP rs2920280 is a possible biomarker for detecting individuals developing GMA. PSCA polymorphisms may be useful biomarkers for predicting GMA linked to GC risk and a screening endoscopy strategy to detect GC related to early stage H. pylori associated GMA.

The role of single-nucleotide polymorphisms of the 8q24 chromosome region in patients with concomitant bladder and prostate cancer

OBJECTIVE

To assess whether single-nucleotide polymorphisms (SNPs) of the 8q24 chromosome region are associated with recurrence-free survival (RFS) after radical cystoprostatectomy (RC) in patients with concomitant bladder (BC) and prostate cancer (PC).

MATERIALS AND METHODS

A cohort of thirty-six patients treated with RC and pelvic lymph node dissection and histologically exhibited invasive BC and incidental PC. Using Sanger sequencing, a total of seven SNPs in the androgen-responsive element of the promoter region of the following genes were assessed in tumor-free lymph nodes and correlated with oncological outcomes: PSCA (rs2294008, rs2978974, rs1045531, rs3736001), MYC (rs6983267), FXBO32 (rs7830622), and MIR151A (rs14974929). The median follow-up was 26 months (range: 4-68).

RESULTS

In a dominant model, patients exhibiting rs2978974 as a minor allelic variant of the PSCA gene had worse RFS (32 vs. 75%, p = 0.015). No associations were found for the other SNPs.

CONCLUSIONS

These data suggest that the rs2978974 of the PSCA gene correlates with inferior BC-specific RFS after RC and should be further evaluated in larger studies.

A single nucleotide polymorphism in Prostate Stem Cell Antigen is associated with endoscopic grading in Kyoto classification of gastritis

The risk allele of a single nucleotide polymorphism (SNP) rs2294008 in the Prostate stem cell antigen (PSCA) gene is strongly associated with gastric cancer. Although the Kyoto classification score is believed to be an indicator of gastric cancer risk, it lacks supporting genetic evidence. We investigated the effect of this risk allele of PSCA SNP on the Kyoto score. Participants without a history of gastric cancer or Helicobacter pylori (H. pylori) eradication underwent esophagogastroduodenoscopy, H. pylori evaluation, and SNP genotyping. The Kyoto score is the sum of scores obtained from endoscopy-based atrophy, intestinal metaplasia, enlarged folds, nodularity, and diffuse redness. The Kyoto score is novel in the light of scoring for gastritis. A total of 323 patients were enrolled (number of individuals with genotype CC: 52; CT: 140; TT: 131, average age: 50.1 years, male: 50.8%). The patient baseline characteristics including age, sex, body mass index, smoking, drinking, family history of gastric cancer, and H. pylori status had no association with PSCA SNP. The Kyoto score was higher in T (CT or TT genotype; risk allele) carriers than in CC carriers. Atrophy, enlarged folds, and diffuse redness scores were higher in T allele carriers (risk allele) than in CC genotype individuals. In multivariate analysis, the Kyoto score was independently associated with PSCA SNP (OR: 1.30, p = 0.012). Thus, the Kyoto score was associated with a genetic predisposition.

Downregulation of PSCA promotes gastric cancer proliferation and is related to poor prognosis

Background: Dysregulation of prostate stem cell antigen (PSCA) has been implicated in human cancers. Studies have reported that PSCA expression is generally high in prostate cancer, which correlates with a worse survival. PSCA is also highly expressed in bladder, ovarian, and pancreatic cancers. However, PSCA is expressed at low levels in gastric, gallbladder and oesophageal cancers. At present, the clinical significance, expression pattern and biological function of PSCA in gastric cancer (GC) are still unclear.

Methods: Previously, we used cDNA microarray as a screening tool to compare GC tissues with its matched normal gastric mucosa tissues (MNGT), and obtained the differentially expressed genes of the two tissue types. PSCA is one of the genes significantly down-regulated in GC tissues. In this study, we detected the expression of PSCA in GC tissues and MNGT by western-blot experiment and immunohistochemical staining (IHC). Then the relationship between the expression pattern of PSCA and the clinicopathological characteristics and survival in GC was analyzed. In order to further study the function of PSCA in GC, lentivirus was used to construct stable cell lines with knockdown and overexpression of PSCA gene. We used AGS and MKN45 cell lines for plasmid transfection. Colony formation assay, MTS and nude mice xenograft model were performed to investigate the effect of PSCA in GC.

Results: Western-blot and IHC assays demonstrated that the expression of PSCA in GC tissues was significantly lower than that in the MNGT. PSCA expression in GC tissues was high in 252 (57.5%) and low in 186 (42.5%) of 438 patients. PSCA expression for MNGT was high in 273 (62.3%) and low in 165 (37.7%) of 438 patients. PSCA expression was significantly associated with T classification (P=0.024), N classification (P=0.018) and TNM stage (P=0.019) using χ² test. The relationship between PSCA expression level and patient survival was analysed using Kaplan-Meier analysis and the log-rank test. Low levels of PSCA expression were significantly associated with a poorer OS than high expression levels of PSCA (P=0.011). In the COX regression analysis of OS, all 9 variables in the univariate analysis were significantly correlated with OS (P<0.05), while the variables found to be independently correlated with OS in the multivariate analysis were PSCA expression (P=0.036), age (P<0.001), gender (P=0.007), and TNM stage (P<0.001), respectively. Univariate and multivariate analyses showed that PSCA was an independent prognostic factor for OS in GC. In vitro MTS cell proliferation experiment and clonal formation experiment and in vivo nude mouse subcutaneous tumorigenesis experiment all proved that knockdown of PSCA gene can improve the proliferation ability of GC cells, while in vitro experiment proved that overexpression of PSCA can reduce the proliferation ability of GC cells.It was found that knockdown of PSCA gene can improve the proliferation ability of GC cells both in vitro and in vivo, while overexpression of PSCA can reduce the proliferation ability of GC cells in vitro.

Conclusion: Our study showed that the expression of PSCA gene was decreased in GC, which was related to more advanced pathological stages. And the expression level of PSCA in GC was an independent good prognostic factor. PSCA gene had the function of inhibiting GC proliferation.

PSCArs2294008 T polymorphism increases the risk of bladder cancer in Bai, Dai, and Han ethnicity in China and a potential mechanism

The aim of this study is to make a comparative evaluation on association of PSCArs2294008 C/T polymorphism with the risk of bladder cancer in Bai, Dai, and Han people in China. A potential mechanism of the T allele risk was also investigated. T allele increased the occurring risk of bladder cancer in Han (OR 1.34; 95% CI 1.17-1.69), Dai, (OR 1.33; 95% CI 1.12-1.70), and Bai (OR 1.14; 95% CI 1.08-1.57) people. T genotype was also observed to associate with invasive bladder cancer in all the three populations (Bai, OR 1.15, 95% CI 1.07-1.87; Dai, OR 1.17, 95% CI 1.05-2.23; Han, OR 1.22, 95% CI 1.10-2.09). PSCA m-RNA levels in T genotype bladder cancer tissues were significantly lower than those in C genotype. An enhancement of PSCA m-RNA level by over-expressing C or T genotype in bladder cancer cells both decreased the cell proliferation and migration, but not affected cell cycle. The increased cell apoptasis due to the over-expression of the two variants was observed. Those change of cell proliferation, migration, and apoptasis was more remarkable in over-expressed C genotype cells than those in over-expressed T genotype. T genotype was genetically high risk to the occurrence of bladder cancer. The decreased PSCA m-RNA levels were involved in the progress of bladder cancer. T allele takes more responsibility for PSCA m-RNA down-regulation to promote cell proliferation and migration and hinder cell apoptasis, thus leading to a higher risk.

Single-nucleotide polymorphisms in PSCA and the risk of breast cancer in a Chinese population

This study explored the associations between common PSCA single-nucleotide polymorphisms (rs2294008, rs2978974, and rs2976392) and breast cancer among 560 breast cancer cases and 583 controls (Chinese Han women). We found rs2294008 was significantly associated with a high risk of breast cancer (homozygote model, odds ratio [OR]: 1.67, 95% confidence interval [CI]: 1.06–2.59; recessive, OR: 1.64, 95% CI: 1.06–2.53). And stratification by menopausal status revealed an association of the minor allele of rs2294008 with breast cancer risk among premenopausal (homozygote model, OR: 2.41, 95% CI: 1.03–5.66; recessive, OR: 2.80, 95 % CI: 1.21–6.47) and postmenopausal women (allele model, OR: 1.29, 95% CI: 1.01–1.65). Rs2978974 influenced the breast cancer risk among postmenopausal women in heterozygote model (OR: 1.47, 95% CI: 1.05–2.07). When stratified by clinicopathologic features, the T allele of rs2294008 was associated with progesterone receptor status (homozygote model, OR: 1.98, 95% CI: 1.08–3.63; recessive, OR: 1.87, 95% CI: 1.04–3.37), and the rs2976392 polymorphism was associated with high lymph node metastasis risk in homozygote model (OR: 2.09, 95%CI: 1.01–4.31). Further haplotype analysis suggested that T_rs2294008 A_rs2976392 G_rs2978974 haplotype enhances breast cancer risk (OR:1.52, 95%CI:1.23-1.89, P<0.001). Therefore, among Chinese Han women, the PSCA rs2294008, rs2978974, and rs2976392 minor alleles are associated with increased breast cancer risk especially in progesterone receptor positive breast cancer patients, with breast cancer risk in postmenopausal women, and with high lymph node metastasis risk, respectively. Moreover, T_rs2294008 A_rs2976392 G_rs2978974 haplotype was associated with significantly increased risk of breast cancer.

Decrease in PSCA expression caused by Helicobacter pylori infection may promote progression to severe gastritis

SNP rs2294008 in Prostate Stem Cell Antigen (PSCA) and decreased PSCA expression are associated with gastric cancer. The objective of this study is to investigate the role of rs2294008 and PSCA expression in the gastritis-gastric cancer carcinogenic pathway. We conducted a case-control association study of H. pylori-infected gastritis and gastric cancer. rs2294008 was associated with the progression to chronic active gastritis (P = 9.4 × 10^–5; odds ratio = 3.88, TT + TC vs CC genotype), but not with H. pylori infection per se nor with the progression from active gastritis to gastric cancer. We also assessed the association of rs2294008 with PSCA mRNA expression in the gastric mucosa at various disease stages and found that rs2294008 was associated with PSCA expression (P = 1.3 × 10^–12). H. pylori infection (P = 5.1 × 10^–8) and eradication therapy (P < 1 × 10^–11) resulted in the reduced and increased PSCA expression, respectively, indicating negative regulation of PSCA expression by H. pylori infection. PSCA expression was decreased in severe gastritis compared with mild gastritis only among T allele carriers. Our findings revealed the regulation of PSCA expression by host genetic variation and bacterial infection might contribute to gastritis progression after H. pylori infection.

PSCA promotes prostate cancer proliferation and cell-cycle progression by up-regulating c-Myc

BACKGROUND

The Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol (GPI)-anchored protein. Increasing evidence has indicated PSCA plays an important role in tumorigenesis. However, its function and the underlying molecular mechanisms in prostate cancer (PCa) are still not fully elucidated. In this study, we aimed to explore the effect of PSCA on cell cycle of PCa cells and its mechanism research.

METHODS

Immunohistochemistry, quantitative reverse transcription-PCR (qRT-PCR) and Western blotting were used to quantify PSCA expression pattern in PCa tissues and cell lines. The association of PSCA expression with the biochemical recurrence (BCR)-free survival and overall survival (OS) of PCa patients were analyzed using Kaplan-Meier method. The roles of PSCA in PCa were confirmed based on both in vitro and in vivo systems.

RESULTS

Immunohistochemistry results showed that PSCA was upregulated in PCa tissue. PSCA overexpression were significantly associated with high Gleason score (GS) (P = 0.028), positive BCR (P = 0.002), and poor OS (P = 0.032) and high c-Myc expression (P = 0.019). PSCA promoted PCa cell cycle progression and tumor growth via increased c-Myc expression. Additional, PI3K/AKT signaling pathways was involved in PSCA-mediated c-Myc expression and cell proliferation.

CONCLUSIONS

PSCA is a novel cell cycle regulator with a key role in mediating c-Myc-induced proliferation. PSCA may be a potential diagnostic marker and therapeutic target for patients with PCa.

Association of high-evidence gastric cancer susceptibility loci and somatic gene expression levels with survival

Eleven high-evidence single-nucleotide polymorphisms (SNPs) at nine loci for gastric cancer (GC) risk were reported, but their associations with survival remain unknown. In this study, we examined associations between SNP and GC survival by anatomic location and histology among 1147 incident cases from the Shanxi Upper Gastrointestinal Genetics Project. We further examined whether SNPs were expression quantitative trait loci in normal and tumor gastric tissues, and whether tumor versus normal somatic mRNA differences in 126 cases were associated with survival. No SNPs were associated with GC survival overall. However, subtype-specific associations were observed for gastric cardia adenocarcinomas at MUC1/TRIM46/1q22 rs2070803 [HRAA versus GA+GG = 2.16; 95% confidence interval (CI) = 1.24-3.78; P = 0.0068] and LTA/TNF/6p21.33 rs1799724 (HRTT+CT versus CC = 1.30; 95% CI = 1.07-1.57; P = 0.0077), and for diffuse-type GC at PSCA/8q24.3 rs2294008 (HRTT versus CT+CC = 1.99; 95% CI = 1.33-2.97; P = 7.8E-04). Rs2294008T was a cis-expression quantitative trait loci for PSCA, upregulating mRNA in normal gastric (β = 0.60; P = 5.7E-21) and GC (β = 0.30; P = 0.0089) tissues. Cases in the highest quartile (the smallest downregulation of tumor PSCA) had shortest survival than cases with the most downregulated PSCA (median survival of 0.47 years in the highest quartile versus 3.73 years in the lowest quartile; hazard ratio = 9.70; 95% CI = 2.46-38.4; P = 0.0012). Less striking effects for mRNA levels were observed for MTX1 at 1q22 in gastric cardia adenocarcinoma and for JRK at 8q24.3 in diffuse GC. Our results suggest three high-evidence GC risk loci have prognostic importance in GC subtypes. Future studies in well-characterized independent populations are warranted to validate our findings and further investigate the clinical utility of these variants in predicting GC prognosis.

PSCA regulates IL-6 expression through p38/NF-κB signaling in prostate cancer

BACKGROUND

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein. We previously reported that PSCA involved in proliferation and invasion of PCa cells, however, the underlying mechanisms are unknown. In this study, we aimed to explore the regulating role of PSCA gene expression in interleukin-6 (IL-6) autocrine of PCa cells.

METHODS

The stable knockdown-PSCA and ectopically overexpressed-PSCA vector were constructed and transfected into human PCa DU145 and PC-3M cells. The effects of PSCA overexpression or knockdown were determined in proliferation, invasion, and metastasis assays. The effect of PSCA on the expression and secretion of IL-6 was evaluated by immunoblotting and ELISA. Subcellular localization and expression pattern of PSCA and IL-6 protein were examined by immunohistochemistry. Its clinical significance was statistically analyzed.

RESULTS

The results showed that stable knockdown of PSCA delayed proliferation, migration, and invasion while overexpressing PSCA enhanced the proliferation, migration, and invasion in vitro and the lung metastasis in vivo of PCa cells. Importantly, the PSCA involved in the IL-6 secretion and positively regulated p38/NF-κB/IL-6 signaling, leading to enhanced PCa cell invasion and metastasis. Both the expression of PSCA and IL-6 were significantly associated with poor biochemical recurrence-free survival of patients with PCa. PSCA protein expression showed a prognostic value in overall survival as indicated by Kaplan-Meier analysis.

CONCLUSIONS

These results indicate that PSCA regulates the expression and secretion of IL-6 in human PCa cells through p38/NF-κB signaling pathways. PSCA may be a potential diagnostic marker and therapeutic target for PSCA-positive PCa.

Exploratory investigation of PSCA-protein expression in primary breast cancer patients reveals a link to HER2/neu overexpression

BACKGROUND

Prostate stem cell antigen (PSCA) has been suggested as biomarker and therapeutic target for prostate cancer. Recent advances showed that PSCA is up-regulated in other cancer entities, such as bladder or pancreatic cancer. However, the clinical relevance of PSCA-expression in breast cancer patients has not yet been established and is therefore addressed by the current study.

METHODS

PSCA-protein expression was assessed in 405 breast cancer patients, using immunohistochemistry (PSCA antibody MB1) and tissue microarrays.

RESULTS

PSCA-expression was detected in 94/405 patients (23%) and correlated with unfavorable histopathological grade (p=0.011) and increased Ki67 proliferation index (p=0.006). We observed a strong positive correlation between PSCA-protein expression and HER2/neu receptor status (p<0.001). PSCA did not provide prognostic information in the analyzed cohort. Interestingly, the distribution of PSCA-expression among triple negative patients was comparable to the total population.

CONCLUSION

We identified a subgroup of PSCA-positive breast cancer patients, which could be amenable for a PSCA-targeted therapy. Moreover, given that we found a strong positive correlation between PSCA- and HER/neu expression, targeting PSCA may provide an alternative therapeutic option in case of trastuzumab resistance.

PSCA rs2294008 polymorphism contributes to the decreased risk for cervical cancer in a Chinese population

Recently, three genome-wide association studies have identified the PSCA (prostate stem cell antigen) rs2294008 polymorphism (C > T) associated with susceptibility to gastric cancer, bladder cancer, and duodenal ulcers, highlighting its critical role in disease pathogenesis. Given PSCA is reported to be overexpressed in cervical cancer and the rs2294008 can influence PSCA transcription, we aimed to determine the role of rs2294008 in susceptibility to cervical cancer. The genotyping was performed in the 1126 cases and 1237 controls. Our results showed the rs2294008 TT genotype significantly associated with a reduced risk of cervical cancer (adjusted OR = 0.55, 95% CI = 0.38-0.79; recessive model). Stratified analyses revealed that the association was restricted to the subgroups of age > 49 years, parity ≤ 1, abortion and early-stage cervical cancer. Immunohistochemistry assay showed the individuals carrying the TT genotype having lower PSCA expression than those with CC/CT genotypes. In summary, the PSCA rs2294008 polymorphism may serve as a biomarker of cervical cancer, particularly of early-stage cervical cancer.

Knockdown of PSCA induces EMT and decreases metastatic potentials of the human prostate cancer DU145 cells

Background

Prostate stem cell antigen (PSCA) expression has been shown to correlate with prostatic carcinogenesis and prostate cancer (PCa) progression. The underlying mechanisms for these processes are currently unknown. Epithelial to mesenchymal transition (EMT) has been associated with the invasiveness and the distant metastasis of PCa. In this study, we investigated the effects of knocking down the PSCA on the cell migration, the invasiveness, and the EMT of the PCa cell line DU145 in vitro and in vivo.

Methods

Four target sequences of the small hairpin RNA for PSCA were designed, and the best effect knockdown sequence shRNA#1 was screened to construct the stable transfected DU145 cell line (DU145 shRNA#1), the scramble sequence was also designed to construct the stable transfected DU145 cell line(DU145 scramble). Cell migration and invasion were studied using Transwell assay. Quantitative RT-PCR, Western blot (WB) were used to quantify PSCA, E-cadherin, β-catenin, Vimentin, Fibronectin expression in DU145, DU145 scramble, DU145 shRNA#1 in vitro and in vivo. RT-PCR, immunofluorescent staining were used to quantify PSCA, E-cadherin, and Vimentin expression in vitro. EMT-related genes Snail, Slug, and Twist, were quantified by quantitative RT-PCR in vitro.

Results

The constructed stable knockdown of the PSCA in the DU145 cell had a silencing effect up to 90.5 %. DU145 shRNA#1 became scattered from the tightly packed colonies. It was associated with decreased cell migration and invasion. There was also an increased Vimentin and Fibronectin expression, an inhibited E-cadherin and β-catenin expression at both the mRNA and the protein levels when compared to the DU145 and the DU145 scramble in vitro and vivo. Furthermore, with the exception of the Snail, the expression of EMT-related Slug and Twist genes were upregulated.

Conclusions

Our data indicated that knockdown of PSCA induced EMT and reduced metastatic potentials of the DU145 cells, suggesting that PSCA played an important role in prostatic carcinogenesis and progression.

RNA interference targeting PSCA suppresses primary tumor growth and metastasis formation of human prostate cancer xenografts in SCID mice

BACKGROUND AND OBJECTIVES

Prostate stem cell antigen (PSCA) is a cell surface, glycosylphosphatidylinositol (GPI)-anchored glycoprotein. Its overexpression has been detected in both local and metastatic prostate cancer (PCa), making it a potential therapeutic target. We previously reported that silencing PSCA by small interfering RNA targeting human PSCA (siRNA-PSCA) inhibited biological activity of PSCA-positive PCa cells leading to reduced proliferation, motility and invasion in vitro. In this study, we extended this in vitro findings to in vivo settings in order to investigate the effects of this specific siRNA on the tumor growth and metastasis development of PCa in vivo.

MATERIALS AND METHODS

The siRNA-PSCA and ectopically overexpressed-PSCA vector were constructed and transfected into human PCa PC-3M and LNCaP cells, respectively, and were subcutaneously inoculated into the male SCID mice. Tumor growth was measured with a caliper, and formation of metastasis in mice bearing xenograft tumors was studied by magnetic resonance imaging (MRI) and autopsy analysis. Western blot and immunohistochemistry were used to assess the expression levels of PSCA protein in tumor tissues from xenograft and distant metastases.

RESULTS

Consistent with our previous in vitro findings, the subcutaneous xenografts of PC-3M-siPSCA exhibited the almost completely inhibited expression of PSCA protein in their tumors tissues (P < 0.001 and P < 0.001, respectively), and consequently had a significant reduction in tumor growth volumes (P < 0.05 for all), and metastasis onset and sites (P < 0.001 for all) compared to those of PC-3M and PC-3M-siScrm. Conversely, LNCaP-PSCA showed significantly enhanced primary tumor growth and metastasis formation of xenografts compared to LNCaP-vehicle and LNCaP cells (P < 0.001 for all). Moreover, the up-regulated expression of PSCA protein was detected in the distant metastases of xenograft tumors from all groups.

CONCLUSIONS

Taken together, these observations suggest that PSCA has a promoting role in the growth and metastasis of PCa and siRNA-PSCA may be a potential therapeutic strategy for PSCA-positive PCa.

Prostate stem cell antigen variation rs2294008 associated with the risk of bladder cancer

Several studies reported Prostate stem cell antigen (PSCA) rs2294008 was susceptibly associated with bladder cancer (BC) risk. However, the results were not entirely consistent. The aim of this study was to investigate the association between rs2294008 and BC risk. Comprehensive meta-analysis was preformed to provide a more precise assessment of the association between rs2294008 and BC risk. Twenty five studies involving 14,244 BC patients and 53,963 controls were included in our meta-analysis. The crude odds ratios (ORs) and the 95% confidence intervals (95% CIs) were used to evaluate the strength of the association. Pooled results indicated that the PSCA variant rs2294008-T was significantly connected with an increased risk of BC (OR = 1.15, 95% CI = 1.12-1.18, P(z) < 0.0001). Moreover, stratified analyses showed that rs2294008 significantly increased BC risk in European (OR = 1.10, 95% CI = 1.05-1.15, P(z) < 0.0001), North American (OR = 1.18, 95% CI = 1.12-1.24, P(z) < 0.0001), and Asian (OR = 1.17, 95% CI = 1.13-1.22, P(z) < 0.0001). In conclusion, our meta-analysis demonstrated that the PSCA rs2294008 is a risk factor for BC in European, Asian and North American. Further large case-control studies are needed to assess the relationship in other populations. Biologically functional studies are needed to verify the molecular mechanisms in the pathogenesis of BC.

Association between PSCA mRNA expression levels and rs2294008 polymorphism in transitional cell cancer of the bladder

Prostate stem cell antigen (PSCA) was originally identified as a gene that is overexpressed in prostate cancer, and correlates with prostate cancer progression and prognosis. Recently, a significant association has been identified between the PSCA rs2294008 (C>T) polymorphism and the risk of developing bladder cancer. Therefore, the present study investigated the different expression levels of PSCA mRNA in transitional cell carcinoma (TCC) of the bladder and normal bladder tissue. Furthermore, the association between PSCA mRNA expression levels in TCC and different rs2294008 (C>T) genotypes and various clinicopathological features, including tumor stage and grade, were evaluated. Reverse transcription-quantitative polymerase chain reaction was performed on 80 TCC samples and 38 samples of normal bladder urothelium from TCC patients who underwent transurethral resection of bladder tumor or radical cystectomy at the Beijing Friendship Hospital (Beijing, China) between September 2010 and May 2011. Genomic DNA was extracted from tumor tissue and sequenced to determine the rs2294008 (C>T) genotype. PSCA mRNA expression was detected in all samples (100%); however, tumor samples exhibited significantly higher PSCA expression levels compared with the normal urothelium samples (P=0.038). PSCA mRNA expression was positively correlated with the histological grade of the tumor (G1-2 vs. G3; P=0.001); however, no significant difference was detected between patients with superficial (Ta or T1) and muscle-invasive (≥pT2) tumors (P=0.250). Thus, PSCA mRNA expression levels were associated with TCC and tumor histological grade, but not the tumor stage. Additionally, PSCA mRNA expression levels were significantly higher in T allele carriers compared with CC homozygous patients (P=0.001), indicating that the presence of the T allele may increase PSCA mRNA expression. Therefore, rs2294008 (C>T) may be associated with the biological properties of TCC and, thus, future research should focus on the physiological function of PSCA and the mechanism of rs2294008.

Association of a common genetic variant in prostate stem cell antigen with cancer risk

INTRODUCTION

Polymorphisms in the prostate stem cell antigen (PSCA) gene have been hypothesized to increase the genetic susceptibility to cancers. The common sequence variation in PSCA rs2294008 (C>T) has been implicated in cancer risk. However, results of the relevant published studies were somewhat underpowered and controversial in general.

MATERIAL AND METHODS

To evaluate the role of PSCA rs2294008 (C>T) genotype in global cancer, we performed a pooled analysis of all the available published studies involving 22,817 cancer patients and 27,753 control subjects.

RESULTS

The results showed evidence that PSCA rs2294008 (C>T) was associated with increased total cancer risk in the overall comparisons. Stratified analysis by cancer type indicated that PSCA rs2294008 T is associated with increased risk of gastric cancer (OR = 1.24, 95% CI = 1.09-1.42, p heterogeneity < 0.001, I (2) = 88.0%) and bladder cancer (OR = 1.07, 95% CI = 1.04-1.11, p heterogeneity = 0.108, I (2) = 55.0%) by allelic contrast. Furthermore, in stratified analysis by histological types of gastric cancer, this PSCA variant showed significant associations with diffuse type (OR = 1.81, 95% CI = 1.16-2.81, p heterogeneity < 0.001, I (2) = 88.9%) but not intestinal type (OR = 1.29, 95% CI = 0.95-1.74, p heterogeneity < 0.001, I (2) = 85.2%) in a dominant genetic model. Similar results were found in Asian and European descendents and population-based studies.

CONCLUSIONS

In all, our meta-analysis suggests that PSCA rs2294008 (C>T) may play allele-specific roles in cancer development. Further prospective studies with larger numbers of participants worldwide should be performed in different kinds of cancer and other descendents in more detail.

Targeted therapies in urothelial carcinoma

PURPOSE OF REVIEW

Greater understanding of the biology and genetics of urothelial carcinoma is helping to identify and define the role of molecules and pathways appropriate for novel-targeted therapies. Here, we review the targeted therapies that have been reported or are in ongoing urothelial carcinoma clinical trials, and highlight molecular targets characterized in preclinical and clinical studies.

RECENT FINDINGS

Trials in nonmuscle-invasive bladder cancer are evaluating the role of immunotherapy and agents targeting vascular endothelial growth factor (VEGF) or fibroblast growth factor receptor-3. In muscle-invasive bladder cancer, neoadjuvant studies have focused on combining VEGF agents with chemotherapy; adjuvant studies are testing vaccines and agents targeting the human epidermal growth factor receptor 2, p53, and Hsp27. In the first-line treatment of metastatic urothelial carcinoma, tubulin, cytotoxic T-lymphocyte antigen 4, Hsp27, and p53 are novel targets in clinical trials. The majority of targeted agents studied in urothelial carcinoma are in the second-line setting; new targets include CD105, polo-like kinase-1, phosphatidylinositide 3-kinases (PI3K), transforming growth factor β receptor/activin receptor-like kinase β, estrogen receptor, and the hepatocyte growth factor receptor (HGFR or MET).

SUMMARY

Development of targeted therapies for urothelial carcinoma is still in early stages, consequently there have been no major therapeutic advances to date. However, greater understanding of urothelial carcinoma and solid tumor biology has resulted in a proliferation of clinical trials that could lead to significant advances in treatment strategies.

Genetic variants at 8q24 are associated with risk of esophageal squamous cell carcinoma in a Chinese population

Esophageal cancer and gastric cancer have shared risk factors and inherited susceptibility. Recent genome-wide association studies have identified multiple genetic loci associated with gastric cancer risk, which may also involve in the development of esophageal cancer. Herein, we evaluated the relationship of gastric cancer risk-related variants at 1q22, 3q13.3, 5p13.1, and 8q24 with the risk of esophageal squamous cell carcinoma (ESCC) in a Chinese population with a case–control study (2139 cases and 2273 controls). We found that the T allele of rs2294008, an intronic variant of the PSCA gene at 8q24 that was previously associated with an increased risk of gastric cancer, was inversely associated with a decreased risk of ESCC (odds ratio = 0.90; 95% confidence interval, 0.81–0.99; P = 0.034). Of interest, the association of rs2294008 with ESCC was consistent with that observed in esophageal adenocarcinoma and ESCC in Caucasian populations. However, no significant associations were observed for the other three variants at 1q22 (rs4072037), 3q13.31 (rs9841504), and 5p13.1 (rs13361707). Our findings suggest that the susceptibility locus of PSCA at 8q24 may be a double-edged sword, as modulator between the carcinogenesis processes of stomach and esophagus.

Prostate stem cell antigen and cancer risk, mechanisms and therapeutic implications

Prostate stem cell antigen (PSCA) was originally identified as a tumor antigen in prostate cancer. Recent studies indicated that PSCA was correlated with many cancer types. In this review, we will consider the origin of PSCA, discuss the expression of PSCA in normal and cancer tissue, describe PSCA polymorphisms and cancer risk, summarize potential mechanisms for PSCA involvement in cancer; and look into the therapeutic implications of PSCA. PSCA is upregulated in prostate cancer, pancreatic cancer and bladder cancer, as well as a number of others, making it an ideal clinical target for both diagnosis and therapy. Future studies will be required to explore its mechanisms on various cancer types, and to confirm its clinical utility for diagnosis and immunotherapy strategies. The study of PSCA regulation and expression may also provide information on normal prostate development and prostate carcinogenesis.

Characterization and function of human Ly-6/uPAR molecules

Human Ly-6/uPAR molecules are a superfamily composed of two subfamilies; one is the membrane bound proteins with a GPI-anchor and the other are secreted proteins without the GPI-anchor. Ly-6/uPAR molecules have remarkable amino acid homology through a distinctive 8-10 cysteine-rich domain that is associated predominantly with O-linked glycans. These molecules are encoded by multiple tightly linked genes located on Chr. 8q23, and have a conserved genomic organization. Ly-6/uPAR molecules have an interesting expression pattern during hematopoiesis and on specific tumors indicating that Ly-6/uPAR molecules are associated with development of the immune system and carcinogenesis. Thus, Ly-6/uPAR molecules are useful antigens for diagnostic and therapeutic targets. This review summarizes our understanding of human Ly-6/ uPAR molecules with regard to molecular structure as well as what is known about their function in normal and malignant tissues and suggest Ly-6/uPAR molecules as target antigens for cancer immunotherapy.

TCTP is an androgen-regulated gene implicated in prostate cancer

TCTP has been implicated in a plethora of important cellular processes related to cell growth, cell cycle progression, malignant transformation and inhibition of apoptosis. In addition to these intracellular functions, TCTP has extracellular functions and plays an important role in immune cells. TCTP expression was previously shown to be deregulated in prostate cancer, but its function in prostate cancer cells is largely unknown. Here we show that TCTP expression is regulated by androgens in LNCaP prostate cancer cells in vitro as well as human prostate cancer xenografts in vivo. Knockdown of TCTP reduced colony formation and increased apoptosis in LNCaP cells, implicating it as an important factor for prostate cancer cell growth. Global gene expression profiling in TCTP knockdown LNCaP cells showed that several interferon regulated genes are regulated by TCTP, suggesting that it may have a role in regulating immune function in prostate cancer. In addition, recombinant TCTP treatment increased colony formation in LNCaP cells suggesting that secreted TCTP may function as a proliferative factor in prostate cancer. These results suggest that TCTP may have a role in prostate cancer development.

Impact of PSCA variation on gastric ulcer susceptibility

Peptic ulcer is one of the most common gastrointestinal disorders with complex etiology. Recently we conducted the genome wide association study for duodenal ulcer and identified disease susceptibility variations at two genetic loci corresponding to the Prostate stem cell antigen (PSCA) gene and the ABO blood group (ABO) gene. Here we investigated the association of these variations with gastric ulcer in two Japanese case-control sample sets, a total of 4,291 gastric ulcer cases and 22,665 controls. As a result, a C-allele of rs2294008 at PSCA increased the risk of gastric ulcer with odds ratio (OR) of 1.13 (P value of 5.85×10(-7)) in an additive model. On the other hand, SNP rs505922 on ABO exhibited inconsistent result between two cohorts. Our finding implies presence of the common genetic variant in the pathogenesis of gastric and duodenal ulcers.

Genetic variant as a selection marker for anti-prostate stem cell antigen immunotherapy of bladder cancer

A monoclonal antibody against prostate stem cell antigen (PSCA) has emerged as a novel cancer therapy currently being tested in clinical trials for prostate and pancreatic cancers, but this treatment is likely to be efficient only in patients with PSCA-expressing tumors. The present study demonstrates that a genetic variant (rs2294008) discovered by bladder cancer genome-wide association studies is a strong predictor of PSCA protein expression in bladder tumors, as measured by two-sided multivariable linear regression (P = 6.46×10⁻¹¹; n = 278). The association pattern is similar in non-muscle-invasive tumors, stages Ta (P = 3.10×10⁻⁵; n = 173) and T1 (P = 2.64×10⁻⁵; n = 60), and muscle-invasive tumors, stages T2 (P =.01; n = 23) and T3/4 (P =.03; n = 22). The study suggests that anti-PSCA immunotherapy might be beneficial for bladder cancer patients with high tumor PSCA expression, which is statistically significantly associated with the presence of CT and TT genotypes of a common genetic variant, rs2294008. Future clinical studies will be needed to validate PSCA as a therapeutic target for bladder cancer.

Dendritic cell-directed vaccination with a lentivector encoding PSCA for prostate cancer in mice

Many studies have demonstrated that prostate stem cell antigen (PSCA) is an attractive target for immunotherapy based on its overexpression in prostate tumor tissue, especially in some metastatic tissues. In this study, we evaluated dendritic cell (DC)-directed lentiviral vector (DCLV) encoding murine PSCA (DCLV-PSCA) as a novel tumor vaccine for prostate cancer in mouse models. We showed that DCLV-PSCA could preferentially deliver the PSCA antigen gene to DC-SIGN-expressing 293T cells and bone marrow-derived DCs (BMDCs). Direct immunization with the DCLV-PSCA in male C57BL/6 mice elicited robust PSCA-responsive CD8⁺ and CD4⁺ T cells in vivo. In a transgenic adenocarcinoma mouse prostate cell line (TRAMP-C1) synergetic tumor model, we further demonstrated that DCLV-PSCA-vaccinated mice could be protected from lethal tumor challenge in a prophylactic model, whereas slower tumor growth was observed in a therapeutic model. This DCLV-PSCA vaccine also showed efficacy in inhibiting tumor metastases using a PSCA-expressing B16-F10 model. Taken together, these data suggest that DCLV is a potent vaccine carrier for PSCA in delivering anti-prostate cancer immunity.

Lack of association between the rs2294008 polymorphism in the prostate stem cell antigen gene and colorectal neoplasia: a case-control and immunohistochemical study

Background

Prostate stem cell antigen (PSCA) has been implicated in the pathogenesis of several solid tumours, either due to changes in protein expression, or through association with the rs2294008 polymorphism in the PSCA gene. To our knowledge, the role of PSCA in the development of colorectal neoplasia has not been explored. We performed a genotyping study to assess for associations between the rs2294008 polymorphism and risk of adenomatous polyps and colorectal cancer. DNA samples were available from 388 individuals with colorectal neoplasia and 496 controls, all of whom had undergone screening colonoscopy. In addition, we performed immunohistochemical staining for PSCA in colonic tissue representing all stages of the adenoma-carcinoma sequence.

Results

No genotypic associations were found between the rs2294008 polymorphism and the risk of colorectal adenomata or cancer. Immunohistochemical staining did not reveal any alteration in PSCA expression accompanying the adenoma-carcinoma sequence.

Conclusion

From these data it seems unlikely that PSCA has a role in the initiation or progression of colorectal neoplasia.

A genome-wide association study identifies two susceptibility loci for duodenal ulcer in the Japanese population

Through a genome-wide association analysis with a total of 7,035 individuals with duodenal ulcer and 25,323 controls from Japan, we identified two susceptibility loci at the PSCA gene (encoding prostate stem cell antigen) at 8q24 and at the ABO blood group locus at 9q34. The C allele of rs2294008 at PSCA was associated with increased risk of duodenal ulcer (odds ratio (OR) = 1.84; P = 3.92 × 10(-33)) in a recessive model but was associated with decreased risk of gastric cancer (OR = 0.79; P = 6.79 × 10(-12)), as reported previously. The T allele of rs2294008 encodes a translation initiation codon upstream of the reported site and changes protein localization from the cytoplasm to the cell surface. rs505922 at ABO was also associated with duodenal ulcer in a recessive model (OR = 1.32; P = 1.15 × 10(-10)). Our findings demonstrate a role for genetic variants in the pathogenesis of duodenal ulcer.

Small interference RNA-mediated silencing of prostate stem cell antigen attenuates growth, reduces migration and invasion of human prostate cancer PC-3M cells

OBJECTIVES

Prostate stem cell antigen (PSCA), a glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein, is highly expressed in both local and metastatic prostate cancer (CaP). Elevated PSCA expression has been shown to correlate with malignant phenotype and clinical progression. The purpose of the current study is to investigate the therapeutic potential of small interference RNA (siRNA) targeting PSCA on human CaP cells.

MATERIALS AND METHODS

A set of two siRNAs directed different regions of human PSCA (siRNA-PSCA) were designed and transfected into a human CaP PC-3M cell line. The silencing effect was screened by RT-PCR and Western blotting. The biological effects of siRNA-PSCA on PC-3M cells were investigated by examining the cell proliferation through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell cycle distribution through flow cytometry, and migration and invasion potencies through transwell invasion assay upon the PSCA silencing.

RESULTS

PC-3M cells had positive PSCA expression on immunocytochemical assay. PSCA expression was depleted at 48 hours after transfection with siRNA-PSCA. Silencing of PSCA significantly suppressed cell proliferation. Cell cycle assay showed that the anti-proliferation effect of siRNA-PSCA was mediated by arresting cells in the G0/G1 phase rather than apoptosis. Furthermore, PSCA knockdown resulted in a marked decrease of cell migration and invasion capabilities in PC-3M cells.

CONCLUSIONS

The present study provides the first evidence that silencing PSCA using siRNA can inhibit the proliferation and invasiveness properties of human CaP cells, which may provide a promising therapeutic strategy for CaP and open a novel avenue toward the investigation of the role of PSCA overexpression in cancers.

DNA-methylation profiling distinguishes malignant melanomas from benign nevi

DNA methylation, an epigenetic alteration typically occurring early in cancer development, could aid in the molecular diagnosis of melanoma. We determined technical feasibility for high-throughput DNA-methylation array-based profiling using formalin-fixed paraffin-embedded tissues for selection of candidate DNA-methylation differences between melanomas and nevi. Promoter methylation was evaluated in 27 common benign nevi and 22 primary invasive melanomas using a 1505 CpG site microarray. Unsupervised hierarchical clustering distinguished melanomas from nevi; 26 CpG sites in 22 genes were identified with significantly different methylation levels between melanomas and nevi after adjustment for age, sex, and multiple comparisons and with β-value differences of ≥0.2. Prediction analysis for microarrays identified 12 CpG loci that were highly predictive of melanoma, with area under the receiver operating characteristic curves of >0.95. Of our panel of 22 genes, 14 were statistically significant in an independent sample set of 29 nevi (including dysplastic nevi) and 25 primary invasive melanomas after adjustment for age, sex, and multiple comparisons. This first report of a DNA-methylation signature discriminating melanomas from nevi indicates that DNA methylation appears promising as an additional tool for enhancing melanoma diagnosis.

Genetic variation in the prostate stem cell antigen gene and upper gastrointestinal cancer in white individuals

BACKGROUND & AIMS

An association between gastric cancer and the rs2294008 (C>T) polymorphism in the prostate stem cell antigen (PSCA) gene has been reported for several Asian populations. We set out to determine whether such an association exists in white individuals.

METHODS

We genotyped 166 relatives of gastric cancer patients, including 43 Helicobacter pylori-infected subjects with hypochlorhydria and gastric atrophy, 65 infected subjects without these abnormalities, 58 H pylori-negative relatives, and 100 population controls. Additionally, a population-based study of chronic atrophic gastritis provided 533 cases and 1054 controls. We then genotyped 2 population-based, case-control studies of upper gastrointestinal cancer: the first included 312 gastric cancer cases and 383 controls; the second included 309 gastric cancer cases, 159 esophageal cancer cases, and 211 controls. Odds ratios were computed from logistic models and adjusted for confounding variables.

RESULTS

Carriage of the risk allele (T) of rs2294008 in PSCA was associated with chronic atrophic gastritis (adjusted odds ratio [OR], 1.5; 95% confidence interval [CI]: 1.1-1.9) and noncardia gastric cancer (OR, 1.9; 95% CI: 1.3-2.8). The association was strongest for the diffuse histologic type (OR, 3.2; 95% CI: 1.2-10.7). An inverse association was observed between carriage of the risk allele and gastric cardia cancer (OR, 0.5; 95% CI: 0.3-0.9), esophageal adenocarcinoma (OR, 0.5; 95% CI: 0.3-0.9), and esophageal squamous cell carcinoma (OR, 0.4; 95% CI: 0.2-0.9).

CONCLUSIONS

The rs2294008 polymorphism in PSCA increases the risk of noncardia gastric cancer and its precursors in white individuals but protects against proximal cancers.