Prostate Stem Cell Antigen Expression Research Articles

Final results from phase I study of PSCA-targeted chimeric antigen receptor (CAR) T cells in patients with metastatic castration resistant prostate cancer (mCRPC).

5019 Background: Chimeric antigen receptor (CAR)-engineered T cell therapies are being pursued for the treatment of mCRPC. Prostate Stem Cell Antigen (PSCA) is highly expressed on the surface membrane in mCRPC and with limited expression on normal tissues. We are completing a phase I study of PSCA-targeted 4-1BB-co-stimulated CAR T cell therapy in mCRPC. Methods: CAR T cells were manufactured at City of Hope’s cGMP facility. Patients (pts) were required to have disease progression after at least 1 androgen receptor targeted therapy but there was no limit on other prior treatments. The primary objective was to define the dose limiting toxicities (DLT) as well as to describe preliminary bioactivity and activity. CAR T persistence and cytokine levels were evaluated by flow cytometry and Luminex. Circulating tumor cells (CTC) were measured by an unselected assay (Kuhn). Results: 14 pts were treated, median age 69, median baseline PSA 88. 12(86%) had previously been treated with chemotherapy; 9 received two taxanes and 3 docetaxel only. 79% of screened pts had PSCA expression >2+ in >80% of cancer cells. Two of 6 pts encountered DLT (grade 3 cystitis) at 100M + lymphodepletion (LD) chemotherapy. The protocol was amended to reduce the LD dose to 300 mg/m2 cyclophosphamide D1-3. No DLTs occurred in 5 pts treated in the modified LD 100M cohort. Cytokine release syndrome (CRS), best response by RECIST, CAR T cell expansion and persistence are presented by dose level in the table. CAR T expansion was greater with LD than without. PSA declines were seen, as well as radiographic improvement, though RECIST response was limited to stable disease (SD) by concurrent bone metastases. Cytokine peaks were higher in patients with anti-tumor effect noted. CTC decreases in both marrow and peripheral blood were seen, associated with PSA declines. Conclusions: PSCA-CAR T cells have anti-cancer activity in mCRPC with DLT of cystitis. LD was required for greater expansion and activity; lower dose LD improved toxicity without clear negative impact on expansion. Clinical trial information: NCT03873805 . [Table: see text]

Preclinical Characterization of the 177Lu-Labeled Prostate Stem Cell Antigen (PSCA)-Specific Monoclonal Antibody 7F5.

Prostate specific membrane antigen (PSMA) is an excellent target for imaging and treatment of prostate carcinoma (PCa). Unfortunately, not all PCa cells express PSMA. Therefore, alternative theranostic targets are required. The membrane protein prostate stem cell antigen (PSCA) is highly overexpressed in most primary prostate carcinoma (PCa) cells and in metastatic and hormone refractory tumor cells. Moreover, PSCA expression positively correlates with tumor progression. Therefore, it represents a potential alternative theranostic target suitable for imaging and/or radioimmunotherapy. In order to support this working hypothesis, we conjugated our previously described anti-PSCA monoclonal antibody (mAb) 7F5 with the bifunctional chelator CHX-A″-DTPA and subsequently radiolabeled it with the theranostic radionuclide 177Lu. The resulting radiolabeled mAb ([177Lu]Lu-CHX-A″-DTPA-7F5) was characterized both in vitro and in vivo. It showed a high radiochemical purity (>95%) and stability. The labelling did not affect its binding capability. Biodistribution studies showed a high specific tumor uptake compared to most non-targeted tissues in mice bearing PSCA-positive tumors. Accordingly, SPECT/CT images revealed a high tumor-to-background ratios from 16 h to 7 days after administration of [177Lu]Lu-CHX-A″-DTPA-7F5. Consequently, [177Lu]Lu-CHX-A″-DTPA-7F5 represents a promising candidate for imaging and in the future also for radioimmunotherapy.

The PSCA rs2294008 (C/T) Polymorphism Increases the Risk of Gastric and Bladder Cancer: A Meta-Analysis.

Background: It has been reported that prostate stem cell antigen (PSCA) is overexpressed in certain cancer types and confers poor prognoses. The rs2294008 (C/T) polymorphism of PSCA is considered to be associated with risk for gastric, bladder, and colorectal cancers; however, these studies have produced inconsistent results, so we performed this meta-analysis to verify the association between the PSCA rs2294008 (C/T) polymorphism and cancer risk. Methods: A systematic literature search was performed using PubMed, EMBASE, and the Chinese National Knowledge Infrastructure, through October 20, 2022 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association between the PSCA rs2294008 (C/T) polymorphism and cancer risk. In addition, we explored PSCA mRNA expression in cancers through online databases. Results: In total, 45 articles met our inclusion criteria and were analyzed, including 37,586 cancer cases and 51,197 non-cancer controls. Except in the recessive model, the pooled effect indicated the PSCA rs2294008 T allele was associated with an increased overall cancer risk (T vs. C: OR = 1.120, 95% CI = 1.056-1.188, p < 0.01; TT vs. CC: OR = 1.206, 95% CI = 1.066-1.364, p = 0.03; CT vs. CC: OR = 1.249, 95% CI = 1.151-1.356, p < 0.01; [CT+TT] vs. CC: OR = 1.248, 95% CI = 1.147-1.359, p < 0.01; TT vs. [CT+CC]: OR = 1.051, 95% CI = 0.954-1.156, p = 0.314). In the subgroup analysis, there were significant associations between the rs2294008 T allele and increased risk of bladder and gastric cancer. Two different online tools were used to explore the PSCA mRNA levels in cancer and the corresponding normal adjacent tissues. We found that expression of PSCA was significantly lower in gastric cancer patients. Conclusions: The PSCA rs2294008 T polymorphism is related to increased cancer susceptibility, especially for gastric and bladder cancers. This polymorphism results in a decreased PSCA expression level in gastric cancer.

The Correlation between PSCA Expression and Neuroendocrine Differentiation in Prostate Cancer.

The prostate stem cell antigen (PSCA), as a predominantly prostate-specific marker, is overexpressed in most prostate cancer specimens, is positively correlated with prostate cancer androgen independence, and has the potential to be treated with castration-resistant prostate cancer (CRPC) as a gene therapy target. Using the typical androgen deprivation therapy, most tumors will progress to CRPC, as well as develop into neuroendocrine prostate cancer (NEPC) characterized by the expression of neuroendocrine markers such as enolase 2 (NSE). Our study was aimed at investigating the expressions of PSCA and NSE and the relationship between the two markers, as well as the correlation between the PSCA and NSE expressions and the clinicopathological parameters in prostate cancer specimens from 118 patients by using immunohistochemistry. Our results demonstrated that the PSCA and NSE protein expressions did not correlate with the prostate cancer patients' age or the hormone therapy but showed a significant correlation with the pathological tumor stage of prostate cancer, the Gleason score, and the presence of metastasis. There is a positive association between PSCA and NSE but a negative one between the prostate-specific antigen (PSA) and PSCA or between PSA and NSE. High PSCA and NSE expressions correlated with a poor prognosis in prostate cancer patients. PSCA may play an important role in the progression of neuroendocrine prostate cancer (NEPC).

A PSCA/PGRN-NF-κB-Integrin-α4 Axis Promotes Prostate Cancer Cell Adhesion to Bone Marrow Endothelium and Enhances Metastatic Potential.

Distant metastasis, predominantly to bone, is the leading cause of morbidity and mortality in prostate cancer. However, the mechanisms underlying prostate cancer metastases remain unknown. Prostate cancer cells exhibited discrete adhesion to bone marrow endothelial cells (BMEC), resulting in osteotropic metastasis. Prior data showed an increased metastatic propensity of prostate stem cell antigen (PSCA)-positive prostate cancer cells. The current study sought to characterize the roles of PSCA in the adhesion of prostate cancer cells to BMECs. Cell adhesion was assessed using the adhesion assay and transendothelial migration. The expression and regulation of integrins were evaluated by qRT-PCR, Western blot, promoter-luciferase activity, and chromatin immunoprecipitation (ChIP). Functionally, the potential interacting partners of PSCA in prostate cancer cells were identified by coimmunoprecipitation and mass spectrometry (MS) analysis. The association of PSCA expression with bone metastasis was further analyzed in an in vivo model and prostate cancer patients. We found that overexpression of PSCA enhanced the adhesion capability of prostate cancer cells to BMECs through upregulating integrin-α4 expression, concurrent with transcriptionally activated NF-κB. Growth factor progranulin (PGRN) was identified as a potential interacting partner of PSCA in prostate cancer cells. Functional studies showed that downregulation of PGRN and PSCA with siRNAs in prostate cancer cells significantly suppressed the integrin-α4 expression and the adhesion to BMECs in vitro, respectively, which were restorable by exogenous PGRN. Importantly, PSCA depletion significantly reduced tumors' presence in the bone of a mouse model. Furthermore, PSCA expression is elevated in prostate cancer tissue, and significantly associated with increased Gleason score, advanced stage, bone metastasis, and poor prognosis in prostate cancer patients. We conclude that PSCA/PGRN promoted the adhesion of prostate cancer cells to BMECs through NF-κB/integrin-α4 pathways, to facilitate metastases. IMPLICATIONS: The findings presented here suggest PSCA/PGRN as a potential therapeutic target for prostate cancer metastases, especially for bone metastasis.

A phase I study to evaluate PSCA-targeting chimeric antigen receptor (CAR)-T cells for patients with PSCA+ metastatic castration-resistant prostate cancer (mCRPC).

TPS250 Background: Although treatment options have improved, mCRPC remains highly lethal. Immunotherapy holds potential for durable remissions but not yet in mCRPC. CAR-T cell therapy has yielded cure for patients with refractory hematologic malignancies, and shows promise in solid tumors. Identifying and targeting the optimal antigen will be key to successful translation in solid tumors. Prostate stem cell antigen (PSCA) is highly expressed on prostate cancer cells, especially metastatic foci, and has limited expression on normal tissues. City of Hope has developed a second-generation PSCA CAR-T cell therapy containing an intracellular 4-1BB co-stimulatory domain (PSCA-BBζ) for first-in-human testing in men with mCRPC refractory to standard therapy (NCT03873805). Methods: The toxicity equivalence range (TEQR) design of Blanchard and Longmate will be used to evaluate select doses of PSCA-BBζ cells and determine the maximum tolerated dose (MTD). Doses include Cohort 1 = 100 million (M) CAR-T x 1 alone; Cohort 1b = 100M CAR-T x1 after lymphodepletion; Cohort 2 = 300M after lymphodepletion; Cohort 3 = 600M after lymphodepletion. 12 subjects will be accrued at the MTD. Eligibility: mCRPC treated with either abiraterone, enzalutamide or both; prior chemotherapy and/or radium223 allowed but not mandated. Tumor tissue, primary or metastatic, must stain positive for PSCA by IHC (Abcam 15168) and biopsy is repeated 28 days post infusion. Endpoints: Primary: all toxicities and dose-limiting toxicities defined as grade 3+ toxicity with attribution of possibly related or above, except CRS grade 3 resolved to &lt; grade 2 within 72 hours or grade 3 encephalopathy resolved to baseline within 28 days. Secondary: persistence/expansion of CAR-T, response (soft tissue by RECIST, bone by PCWG3 criteria). Correlative studies include blood (immunophenotyping, cytokines, circulating tumor cell enumeration and PSCA expression), MRI (enhancement/diffusion changes in target lesions) and metastatic core biopsies (PSCA expression and local immune phenotype changes). Progress: 4 subjects have successfully manufactured PSCA-BBζ T cells; 1 completed treatment. Clinical trial information: NCT03873805.

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.

Ligand-inducible, prostate stem cell antigen (PSCA)-directed GoCAR-T cells in advanced solid tumors: Preliminary results from a dose escalation.

283 Background: PSCA, a cell surface protein, is upregulated in many solid tumors and correlates with disease stage. BPX601 is an autologous, T-cell product engineered to contain a PSCA-CD3ζ CAR plus the small molecule rimiducid (Rim)-inducible MyD88/CD40 costimulatory domain. BPX601 is optimized for antigen-directed and independent T cell activation, proliferation and persistence, potentially enhancing efficacy in solid tumors versus traditional CARs. This first-in-human study assesses the safety, biological and clinical activity of BPX601 plus Rim in select PSCA-positive cancers. Methods: NCT02744287 is a two-part, open-label trial. Part 1 is an ongoing 3+3 cell dose escalation to identify the recommended BPX601 cell dose (Day 0) given in combination with a fixed, single Rim dose (0.4 mg/kg; Day 7). Eligibility criteria include previously treated metastatic pancreatic cancer (mPDAC) with measurable disease &amp; positive PSCA expression. Results: Patients received only cyclophosphamide (CTX) for lymphodepletion (LD) within three days before BPX601 infusion. Nine adults have been treated across three cell dose levels (cells/kg): 1.25x106 (cells only), 1.25x106+Rim, 2.5x106+Rim. All had mPDAC with ≥ two prior therapies. Common AEs were fatigue and nausea. No DLTs, related SAEs, neurotoxicity or CRS events were reported. Rapid cell engraftment by Day 4 was observed in all patients. No evidence of LD with CTX was seen. Of six patients that received Rim: two had cell expansion 10- to 20-fold within seven days; two had cell persistence &gt; three weeks; all had elevated serum cytokines (IP-10, TNFα) correlated with cell expansion. Best response after ≥ one scan was 4 SD ≥ eight weeks with two minor responses (not confirmed; one patient had matched CA19-9 decrease) and 2 PD. Disease control without new therapy was 16 and &gt; 11 weeks (ongoing) in one and two patients, respectively. Conclusions: BPX601 with single-dose Rim was well-tolerated and resulted in enhanced T cell expansion and prolonged persistence in some patients despite lack of LD. Evidence of clinical benefit in this heavily pretreated mPDAC population was seen. Part 2 is planned to open soon and will include CTX/fludarabine LD to maximize engraftment as well as gastric and prostate cancers. Clinical trial information: NCT02744287.

Dual-Modality Immuno-PET and Near-Infrared Fluorescence Imaging of Pancreatic Cancer Using an Anti-Prostate Stem Cell Antigen Cys-Diabody.

Pancreatic cancer has a high mortality rate due to late diagnosis and the tendency to invade surrounding tissues and metastasize at an early stage. A molecular imaging agent that enables both presurgery antigen-specific PET (immuno-PET) and intraoperative near-infrared fluorescence (NIRF) guidance might benefit diagnosis of pancreatic cancer, staging, and surgical resection, which remains the only curative treatment. Methods: We developed a dual-labeled probe based on A2 cys-diabody (A2cDb) targeting the cell-surface prostate stem cell antigen (PSCA), which is expressed in most pancreatic cancers. Maleimide-IRDye800CW was site-specifically conjugated to the C-terminal cys-tag (A2cDb-800) without impairing integrity or affinity (half-maximal binding, 4.3 nM). Direct radioiodination with 124I (124I-A2cDb-800) yielded a specific activity of 159 ± 48 MBq/mg with a radiochemical purity exceeding 99% and 65% ± 4.5% immunoreactivity (n = 3). In vivo specificity for PSCA-expressing tumor cells and biodistribution of the dual-modality tracer were evaluated in a prostate cancer xenograft model and compared with single-labeled 124I-A2cDb. Patient-derived pancreatic ductal adenocarcinoma xenografts (PDX-PDACs) were grown subcutaneously in NSG mice and screened for PSCA expression by immuno-PET. Small-animal PET/CT scans of PDX-PDAC-bearing mice were obtained using the dual-modality 124I-A2cDb-800 followed by postmortem NIRF imaging with the skin removed. Tumors and organs were analyzed ex vivo to compare the relative fluorescent signals without obstruction by other organs. Results: Specific uptake in PSCA-positive tumors and low nonspecific background activity resulted in high-contrast immuno-PET images. Concurrent with the PET studies, fluorescent signal was observed in the PSCA-positive tumors of mice injected with the dual-tracer 124I-A2cDb-800, with low background uptake or autofluorescence in the surrounding tissue. Ex vivo biodistribution confirmed comparable tumor uptake of both 124I-A2cDb-800 and 124I-A2cDb. Conclusion: Dual-modality imaging using the anti-PSCA cys-diabody resulted in high-contrast immuno-PET/NIRF images of PDX-PDACs, suggesting that this imaging agent might offer both noninvasive whole-body imaging to localize PSCA-positive pancreatic cancer and fluorescence image-guided identification of tumor margins during surgery.

Prostate stem cell antigen is expressed in normal and malignant human brain tissues.

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein and exhibits an organ-dependent expression pattern in cancer. PSCA is upregulated in prostate cancer and downregulated in gastric cancer. PSCA is expressed in a variety of human organs. Although certain studies previously demonstrated its expression in the mammalian and avian brain, its expression in the human brain has not been thoroughly elucidated. Additionally, it was previously reported that PSCA is weakly expressed in the astrocytes of the normal human brain but aberrantly expressed in glioma, suggesting that PSCA is a promising target of glioma therapy and prostate cancer therapy. The current study identified PSCA expression in the neural and choroid plexus cells of the normal human brain by immunohistochemistry. In brain tumors, PSCA was expressed in medulloblastoma and glioma, and its expression was also observed in papilloma and papillary carcinoma of the choroid plexus, ependymoma and meningioma. The results suggest that PSCA may have a tumor-promoting function in brain tumors and is a potential target for their therapy. However, its expression in normal neuronal and choroid plexus cells implies that a PSCA-targeted therapy may lead to certain adverse phenomena.

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

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. 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. 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. 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.

Expression of prostate stem cell antigen is downregulated during flavonoid-induced cytotoxicity in prostate cancer cells.

Prostate stem cell antigen (PSCA) is expressed in the majority of prostate cancer cases and may be a potential therapeutic target in the treatment of prostate cancer. The present study evaluated the cytotoxicity of three flavonoids (genistein, luteolin and quercetin) towards DU145 prostate cancer cells, and investigated the effect of these flavonoids on PSCA expression. The results demonstrated that genistein, luteolin and quercetin inhibited the growth of DU145 cells in a dose-dependent manner (P<0.05) and induced morphological changes characteristic of apoptosis in DU145 cells. Flow cytometry analysis also indicated that the flavonoids induced S phase cycle arrest in DU145 cells. Notably, it was observed that expression of PSCA was inhibited at the mRNA (P<0.05) and protein levels in DU145 cells following flavonoid treatment compared with the control. These results suggest that flavonoids may be potential therapeutic agents in the treatment and prevention of prostate cancer.

Prostate Stem Cell Antigen Expression in Radical Prostatectomy Specimens Predicts Early Biochemical Recurrence in Patients with High Risk Prostate Cancer Receiving Neoadjuvant Hormonal Therapy.

We aimed to identify tissue biomarkers that predict early biochemical recurrence (BCR) in patients with high-risk prostate cancer (PC), toward the goal of increasing the benefits of neoadjuvant hormonal therapy (NHT). In 2005–2012, prostatectomy specimens were collected from 134 PC patients who had received NHT and radical prostatectomy. The expression of 13 tissue biomarkers was assessed in the specimens via immunohistochemistry. Time to BCR and factors predictive of BCR were determined by using the Cox proportional hazards model. During the follow-up period (median, 57.5 months), 67 (50.0%) patients experienced BCR. Four (3.0%) patients were tumor-free in the final pathology assessment, and 101 (75.4%) had negative resection margins. Prostate stem cell antigen (PSCA) was the only significant prognostic tissue biomarker of BCR [hazard ratio (HR), 2.58; 95% confidence interval (CI), 1.06–6.27; p = 0.037] in a multivariable analysis adjusted by the clinicopathological variables that also significantly predicted BCR; these were seminal vesicle invasion (HR, 2.39; 95% CI, 1.32–4.34), initial prostate serum antigen level (HR 1.01; 95% CI, 1.001–1.020), prostate size (HR, 0.93; 95% CI, 0.90–0.97), and the Gleason score of preoperative biopsies (HR, 1.34; 95% CI, 1.01–1.79). We suggest that PSCA is a useful tissue marker for predicting BCR in patients with high risk PC receiving NHT and radical prostatectomy.

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

BackgroundProstate 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.MethodsFour 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.ResultsThe 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.ConclusionsOur 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.

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.

Increase in prostate stem cell antigen expression in prostatic hyperplasia induced by testosterone and 17β-estradiol in C57BL mice

Estradiol (E2) is known to act synergistically with testosterone (T) for the development of prostatic hyperplasia in rats and dogs, but murine prostate is less responsive to hormonal stimulation. However, a recent study revealed that the combined administration of E2 and T induced prostatic hyperplasia with bladder outlet obstruction in C57BL mice. To understand the mechanisms underlying the hormonal induction of prostatic hyperplasia, the expression of growth factors and their receptors, androgen receptor, estrogen receptor (ER), and prostatic secretory proteins was investigated. Ten-week-old male C57BL mice were treated with T (30mg) or T+E2 (0.5mg) for 10 weeks, and prostatic lobes were dissected and subjected to quantitative RT-PCR and immunoblotting analysis. T administration appeared to induce glandular prostatic growth, while with T+E2 administration this growth was greater and accompanied by extreme bladder enlargement. The expression of prostate stem cell antigen (PSCA) mRNA and protein was increased in prostate tissue in the T group. The combined administration of E2 with T prominently enhanced PSCA expression, along with increased insulin growth factor 1 mRNA levels and decreased estrogen receptor β mRNA expression. The synergistic effect of E2 on the expression of PSCA suggests that this protein may play an important role in the hormone-induced development of prostatic hyperplasia.

Down-regulation of prostate stem cell antigen (PSCA) by Slug promotes metastasis in nasopharyngeal carcinoma.

Distant metastasis and local recurrence are still the major causes for failure of treatment in patients with nasopharyngeal carcinoma (NPC), making it urgent to further elicit the molecular mechanisms of NPC metastasis. Using a gene microarray including transcription factors and known markers for cancer stem cells, prostate stem cell antigen (PSCA) was found to be significantly down-regulated in metastatic NPC in lymph node, compared to its primary tumour, and in NPC cell lines with high metastatic ability compared to those with low metastatic ability. NPC patients with low PSCA expression had a consistently poor metastasis-free survival (p = 0.003). Knockdown and overexpression of PSCA respectively enhanced and impaired the migration and invasion in vitro and the lung metastasis in vivo of NPC cells. Mechanistically, the enhancement of NPC metastasis by knocking down PSCA probably involved epithelial-mesenchymal transition (EMT), by up-regulating N-cadherin and ZEB1/2 and by activating RhoA. The down-regulation of PSCA in NPC cells resulted directly from the binding of Slug to the PSCA promoter. PSCA may be a potential diagnostic marker and therapeutic target for patients with NPC.

Rs2294008T, a risk allele for gastric and gallbladder cancers, suppresses the PSCA promoter by recruiting the transcription factor YY1.

Previous genomewide association studies identified prostate stem cell antigen (PSCA) as a gastric cancer (GC) susceptibility gene and showed an association between GC and the T allele of the single nucleotide polymorphism rs2294008 (C/T) in this gene. The protein product of this gene inhibits cell growth, and the T allele significantly suppresses the transcriptional activity of the -3.2kb PSCA upstream region. However, the mechanism remains unknown. In this study, we conducted reporter assays using the PSCA upstream region containing the C allele and identified the region from -200 to +38bp of the transcription initiation site of the gene as a critical region of the -3.2kb PSCA upstream region. We found that introducing the T allele at rs2294008 generated a consensus binding sequence for the Polycomb group transcription factor Yin Yang 1 (YY1) and that disruption of the consensus sequence restored the transcriptional activity to the -3.2kb PSCA upstream region. These findings imply that the T allele significantly suppresses PSCA expression in vivo by recruiting YY1 to its promoter, which eventually predisposes gastric epithelial cells to GC development.

Prostate stem cell antigen (PSCA) mRNA expression in peripheral blood in patients with benign prostatic hyperplasia and/or prostate cancer.

The aim of this study was to determine whether detection of prostate stem cell antigen (PSCA) expression in BPH might be associated with the subsequent presence of Prostate cancer (PCa) and also to determine whether detection of PSCA expression has potential for prognosis in PCa. This study was comprised of 112 PCa patients, 111 BPH patients and 120 control subjects. We employed reverse-transcriptase polymerase chain reaction (RT-PCR) to detect PSCA mRNA-bearing cells in peripheral blood. PSCA mRNA was detected in the peripheral blood of 71.4% PCa patients and in 13.5% of patients with BPH by RT-PCR. PSCA was positive in 80% of high-grade diseases compared with 20% of low-grade diseases (P = 0.01). Whereas only 38.8% of prostate-confined diseases were PSCA positive, 61.2% of extraprostatic diseases were PSCA positive (P < 0.001). Patients with a lymphovascular invasion of tumor emboli tended to be PSCA positive (P = 0.02). BPH patients with RT-PCR PSCA positive were significantly more likely to develop prostate cancer (OR = 16, 95% CI = 8.1-31.6, P < 0.001). In conclusion, RT-PCR PSCA positivity is significantly associated with the Gleason score, LV tumor emboli and whether or not the tumor was organ confined. In this study, RT-PCR PSCA detection may be a promising tumor marker of diagnostic and metastasis detection for patients with prostate cancer. Also, it may be an important test for predicting BPH patients who are at high risk of subsequent cancer development.