Reduced expression of PSCA, a member of the LY-6 family of cell surface antigens, in bladder, esophagus, and stomach tumors

Urothelial cell culture

This chapter reviews the use of urothelial cells as a means to enhance tissue regeneration and wound healing in urinary tract system. It addresses the properties of urothelial cells, including their role as a permeability barrier to protect underlying muscle tissue from the caustic effects of urine and as one of the main cell types, along with smooth muscle cells, that are used in urethral or bladder tissue engineering today. This description includes a general overview of various isolation techniques and culture methods that have been developed to improve urinary tract reconstruction in vivo and aid the characterization of growth factor expression in vitro. The chapter then describes various applications using urothelial cells, including production of multilayer urothelial sheets, tissue engineered bladder mucosa, tissue engineered urethra, and tissue engineered bladder. It also outlines the advantages of sandwich and layered coculture of these cells and the effects of epithelial-stromal cell interactions during tissue regeneration or wound healing processes in the urinary tract.

Genetic factors related to gastric cancer susceptibility identified using a genome-wide association study

Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia, where Japan and Korea have the highest incidence in the world. Gastric cancer is classified into intestinal and diffuse types. While the former is almost absolutely caused by Helicobacter pylori infection as the initial insult, the latter seems to include cases in which the role of infection is limited, if any, and a contribution of genetic factors is anticipated. Previously, we performed a genome-wide association study (GWAS) on diffuse-type GC by using single nucleotide polymorphisms (SNP) catalogued for Japanese population (JSNP), and identified a prostate stem cell antigen (PSCA) gene encoding a glycosylphosphatidylinositol-anchored cell surface antigen as a GC susceptibility gene. From the second candidate locus identified using the GWAS, 1q22, we found the Mucin 1 (MUC1) gene encoding a cell membrane-bound mucin protein as another gene related to diffuse-type GC. A two-allele analysis based on risk genotypes of the two genes revealed approximately 95% of Japanese population have at least one of the two risk genotypes, and approximately 56% of the population have both risk genotypes. The two-SNP genotype might offer ample room to further stratify a high GC risk subpopulation in Japan and Asia by adding another genetic and/or non-genetic factor. Recently, a GWAS on the Chinese population disclosed an additional three GC susceptibility loci: 3q13.31, 5p13.1 and 10q23.

The synergistic effect of chemical carcinogens enhances Epstein-Barr virus reactivation and tumor progression of nasopharyngeal carcinoma cells

Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). N-nitroso compounds, phorbols, and butyrates are chemicals found in food and herb samples collected from NPC high-risk areas. These chemicals have been reported to be risk factors contributing to the development of NPC, however, the underlying mechanism is not fully understood. We have demonstrated previously that low dose N-methyl-N’-nitro-N-nitrosoguanidine (MNNG, 0.1 µg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate (SB) in enhancing EBV reactivation and genome instability in NPC cells harboring EBV. Considering that residents in NPC high-risk areas may contact regularly with these chemical carcinogens, it is vital to elucidate the relation between chemicals and EBV and their contributions to the carcinogenesis of NPC. In this study, we constructed a cell culture model to show that genome instability, alterations of cancer hallmark gene expression, and tumorigenicity were increased after recurrent EBV reactivation in NPC cells following combined treatment of TPA/SB and MNNG. NPC cells latently infected with EBV, NA, and the corresponding EBV-negative cell, NPC-TW01, were periodically treated with MNNG, TPA/SB, or TPA/SB combined with MNNG. With chemically-induced recurrent reactivation of EBV, the degree of genome instability was significantly enhanced in NA cells treated with a combination of TPA/SB and MNNG than those treated individually. The Matrigel invasiveness, as well as the tumorigenicity in mouse, was also enhanced in NA cells after recurrent EBV reactivation. Expression profile analysis by microarray indicates that many carcinogenesis-related genes were altered after recurrent EBV reactivation, and several aberrations observed in cell lines correspond to alterations in NPC lesions. These results indicate that cooperation between chemical carcinogens can enhance the reactivation of EBV and, over recurrent reactivations, lead to alteration of cancer hallmark gene expression with resultant enhancement of tumorigenesis in NPC.

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.

Effect of PSCA gene polymorphisms on gastric cancer risk and survival prediction: A meta-analysis

Previous studies have shown that two single-nucleotide polymorphisms (SNPs) in PSCA (rs2976392 and rs2294008) are associated with gastric cancer (GC), but the results are conflicting. Additionally, the prognostic value of PSCA gene polymorphisms for GC patients is unknown. We performed a meta-analysis using 9 eligible case-control studies to investigate the association between PSCA polymorphisms and GC risk, and additionally investigated the prognostic value of PSCA polymorphisms for GC patients with two eligible studies. The association was measured using random-effect or fixed-effect odds ratios (ORs) combined with 95% confidence intervals (CIs) according to the heterogeneity of the studies. We found that rs2294008 (dominant model: OR, 1.44; 95% CI, 1.16-1.79) and rs2976392 (dominant model: OR, 1.41; 95% CI, 0.98-2.04) polymorphisms were associated with increased risk of GC, although the association of rs2976392 was not statistically significant. For rs2294008, the associations were all consistently significant among the different subgroups stratified by ethnicity and tumor location, but not significant in intestinal or diffuse subtypes. For rs2976392, the associations were consistently significant for the intestinal, diffuse and non-cardia subtypes, but not significant for the cardia subtype. Furthermore, two eligible studies reported inverse results of PCSA in predicting the survival of GC patients (HR, 0.75; 95% CI, 0.59-0.96; and HR, 2.12; 95% CI, 1.22-3.69, respectively). In conclusion, PSCA gene polymorphisms are associated with increased risk of GC and are correlated with the prognosis of GC patients. Future studies are required to evaluate the molecular mechanisms of PSCA polymorphisms in GC and validate the prognostic value in a larger number of patients.

The PSCA polymorphisms derived from genome-wide association study are associated with risk of gastric cancer: a meta-analysis

PURPOSE

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol-anchored 123-aa protein related to the cell-proliferation inhibition and/or cell-death induction activity. Many studies had reported the role of PSCA rs2294008 C > T and rs2976392 G > A polymorphisms on gastric cancer risk.

METHODS

To investigate a more precise estimation of the relationships, we performed a meta-analysis on 9 case-control studies included 10,746 cases and 9,158 controls. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to assess the strength of the association.

RESULTS

For PSCA rs2294008 C > T polymorphism, there was a significantly increased risk of gastric cancer in all genetic models (TT/TC vs. CC: OR = 1.61, 95 % CI = 1.35-1.91; TT vs.

TC/CC

OR = 1.33, 95 % CI = 1.24-1.42). Similar results were also observed for PSCA rs2976392 G > A polymorphism (AA/AG vs. GG: OR = 1.69, 95 % CI = 1.24-2.31; AA vs.

AG/GG

OR = 1.36, 95 % CI = 1.24-1.50). In the stratified analysis by ethnicity of rs2294008, an increased gastric cancer risk was found in both Asians (TT vs.

TC/CC

OR = 1.31, 95 % CI = 1.22-1.42) and Europeans (TT/TC vs. CC: OR = 1.42, 95 % CI = 1.18-1.71). Furthermore, when stratified by clinicopathologic characteristics of tumor location and histology, a higher risk on non-cardia compared with cardia gastric cancer (TT vs.

TC/CC

OR = 1.43, 95 % CI = 1.12-1.83) as same as diffused compared with intestinal gastric cancer (TT vs.

TC/CC

OR = 1.29, 95 % CI = 1.13-1.49) was observed.

CONCLUSION

These findings supported that PSCA rs2294008 C > T and rs2976392 G > A polymorphisms may contribute to the susceptibility to gastric cancer, particular in non-cardia or diffused gastric cancer.

Identification of distinct populations of prostasomes that differentially express prostate stem cell antigen, annexin A1, and GLIPR2 in humans

In addition to sperm cells, seminal fluid contains various small membranous vesicles. These include prostasomes, membrane vesicles secreted by prostate epithelial cells. Prostasomes have been proposed to perform a variety of functions, including modulation of (immune) cell activity within the female reproductive tract and stimulation of sperm motility and capacitation. How prostasomes mediate such diverse functions, however, remains unclear. In many studies, vesicles from the seminal plasma have been categorized collectively as a single population of prostasomes; in fact, they more likely represent a heterogeneous mixture of vesicles produced by different reproductive glands and secretory mechanisms. We here characterized membranous vesicles from seminal fluid obtained from vasectomized men, thereby excluding material from the testes or epididymides. Two distinct populations of vesicles with characteristic sizes (56 ± 13 nm vs. 105 ± 25 nm) but similar equilibrium buoyant density (∼1.15 g/ml) could be separated by using the distinct rates with which they floated into sucrose gradients. Both types of vesicle resembled exosomes in terms of their buoyant density, size, and the presence of the ubiquitous exosome marker CD9. The protein GLIPR2 was found to be specifically enriched in the lumen of the smaller vesicles, while annexin A1 was uniquely associated with the surface of the larger vesicles. Prostate stem-cell antigen (PSCA), a prostate-specific protein, was present on both populations, thereby confirming their origin. PSCA was, however, absent from membrane vesicles in the seminal fluid of some donors, indicating heterogeneity of prostasome characteristics between individuals.

Prostate stem cell antigen polymorphisms and susceptibility to gastric cancer: a systematic review and meta-analysis

BACKGROUND

Many studies have reported that prostate stem cell antigen (PSCA) polymorphisms (rs2294008 and/or 2976392) are significantly associated with gastric cancer (GC) risk, although the published results are inconsistent. We conducted a systematic review and meta-analysis for relevant literatures to quantitatively evaluate the relationship between PSCA polymorphisms and GC susceptibility.

METHODS

Extensive searches were conducted in three databases up to November 1, 2011. ORs and 95% CIs were used to assess the strength of the associations. The data were further stratified by ethnicity, histopathology, subsite, and study design. All of the associations were evaluated with dominant model and recessive model, respectively. Heterogeneity and publication bias were also assessed by Q test, I(2), and funnel plot accordingly.

RESULTS

Nine articles including 11 case-control data sets were included, with 10,746 GC cases and 9,158 controls for rs2294008 and 6,060 cases and 4,824 controls for rs2976392. The results showed that risk allele carriers were significantly associated with GC risk compared with nonrisk allele homozygotes. In stratification analyses, these associations remained significant for majority of subgroups except for Caucasians and noncardia tumor in dominant model, and cardia tumor in both dominant and recessive model. Random model was used when heterogeneity among studies was detected. No publication bias was observed.

CONCLUSIONS

The two loci of PSCA (rs2294008 and rs2976392) were both significantly associated with GC susceptibility and in linkage disequilibrium.

IMPACT

More prospective studies on PSCA polymorphisms at multicenters with sufficient sample size and less heterogeneity will be needed for further validations.

Genetic variations of prostate stem cell antigen (PSCA) contribute to the risk of gastric cancer for Eastern Asians: a meta-analysis based on 16792 individuals

The associations between polymorphisms of prostate stem cell antigen (PSCA-rs2294008C>T and -rs2976392G>A) and gastric cancer (GC) risk for Eastern Asians have been commonly studied, but the results were conflicting. The aim of the present study was to further assess the associations by the method of meta-analysis. The databases of Medline, Embase and CNKI (up to May 25th, 2011) were retrieved to identify eligible case-control studies. Odds ratio (OR) and 95% confidence interval (95%CI) were used to present the strength of the associations. In total, eight case-control studies in seven articles with 16792 individuals (9738 cases of GC and 7054 controls) were included in this meta-analysis. Through quantitative analyses, we found that T allele of rs2294008C>T and A allele of rs2976392G>A were significantly associated with increased GC risk [rs2294008C>T: OR (95%CI)=1.31 (1.22-1.42), P(z-test)<0.001, P(heterogeneity)=0.166 for TT vs. C carriers; rs2976392G>A: OR (95%CI)=1.36(1.24-1.50), P(z-test)=0.015, P(heterogeneity)=0.111 for AA vs. G carriers]. The results of subgroup analyses (according to histopathology, countries and sources of controls) indicated that T allele of rs2294008C>T and A allele rs2976392G>A were associated with increased risk of both intestinal- and diffuse-type GC, and associated with increased risk of GC for Chinese, Japanese, Koreans, PCC and HCC/PHCC. Furthermore, T allele of rs2294008C>T was also associated with increased risk of cardia and non-cardia GC, and associated with increased risk of GC for males and females. Besides those, this meta-analysis also indicated that the interactions between T allele of rs2294008C>T and A allele of rs2976392G>A was associated with increased risk of GC (A-T vs. G-T: OR=1.16, 95%CI=1.06-1.27, P(z-test)=0.001, P(heterogeneity)=0.835). Although modest limitations and potential bias cannot be eliminated, this meta-analysis suggests that PSCA -rs2294008C>T and -rs2976392G>A are potential factors of GC development for Eastern Asians, and future work may incorporate these findings and evaluate these variants as potential markers for screening and early diagnosis of GC.

Prostate stem cell antigen, a presumable organ-dependent tumor suppressor gene, is down-regulated in gallbladder carcinogenesis

Gallbladder cancer (GBC) is relatively rare but has a high mortality rate. One candidate molecule which might be involved in GBC development is prostate stem cell antigen (PSCA), a glycosylphosphatidylinositol-anchored cell surface antigen with a tissue-specific pattern of expression in the epithelium of several organs, such as the prostate, stomach, bladder, and gallbladder. It is up-regulated in a number of cancers including prostate, urinary bladder, and pancreatic cancers, while it is down-regulated in esophageal and gastric cancers, suggesting that PSCA has an oncogenic activity in the former but a tumor suppressor activity in the latter. However, the precise function of PSCA and the regulatory mechanism for its expression in normal and cancer cells are yet to be determined. In this study, immunohistochemical analyses with a specific antibody revealed that PSCA is down-regulated in non-neoplastic gallbladder lesions such as cholesterolosis, cholecystolithiasis, and cholecystitis (9/17; 53%), and also in adenocarcinoma (40/44; 91%), a common neoplasm in gallbladder. Analyses of the DNA methylation status in the GBC cell lines by bisulfite-Pyrosequencing and a reporter assay for the PSCA promoter activity suggested that the down-regulation is explained, at least partly, by DNA methylation. Moreover, colony formation assay revealed that PSCA has cell-proliferation inhibition activity in the GBC cell lines, which was also observed in vivo. These lines of in vivo and in vitro evidence suggest that PSCA is acting as a tumor suppressor in GBC development.

Prostate stem-cell antigen gene is associated with diffuse and intestinal gastric cancer in Caucasians: results from the EPIC-EURGAST study

A genome-wide study performed in a Japanese population identified a strong association between SNP rs2294008 (Met1Thr) in the Prostate Stem Cell Antigen gene (PSCA) and diffuse-type gastric cancer (GC). This association was validated in different Asian populations, and, very recently, a study has been published in Caucasians. In this study, we analyzed the association between PSCA variation and GC risk in Caucasians from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Six tagSNPs covering the PSCA gene region were genotyped in 411 incident gastric adenocarcinoma cases and 1530 matched controls from a nested case-control study in the EPIC cohort. Associations were analyzed by unconditional logistic regression, adjusting for age, sex and country. The T allele of rs2294008 in PSCA was found to be a highly significant risk factor for GC (per allele OR = 1.42, 95% CI: 1.23-1.66, p-value = 6.5 × 10(-6) ), particularly of the noncardia-type (per allele OR = 1.47, 95% CI: 1.19-1.81, p-value = 3 × 10(-4) ). At contrast with previous studies, no significant differences were observed between the diffuse (per allele OR = 1.54, 95% CI: 1.20-1.96, p-value = 5 × 10(-4) ) and the intestinal (per allele OR = 1.52, 95% CI: 1.20-1.93, p-value = 5 × 10(-4) ) GC histological subtypes. Although rs12155758 and rs9297976 were also found associated with GC, this association appeared to be due to linkage disequilibrium with rs2294008. Haplotype analysis did not provide additional information. These results confirm the association between variation in the promoter region of PSCA and GC risk in Caucasians and also indicate that the rs2294008 variant is a similar risk factor for both the diffuse and intestinal-types of GC.

Association of a common genetic variant in prostate stem-cell antigen with gastric cancer susceptibility in a Korean population

A recent genome wide association study (GWAS) indentified a significant association between rs2294008 (C > T) polymorphism in prostate stem-cell antigen (PSCA) and increased risk of gastric cancer in Japanese and Korean populations. The aim of this study was to determine whether rs2294008 polymorphism is associated with risk of gastric cancer in a Korean population. We conducted a large-scale case-control study of 3,245 gastric cancer patients and 1,700 controls. The frequencies of the CC, CT, and TT genotypes of rs2294008 polymorphism were 17.8%, 49.9%, and 32.3% in the gastric cancer patients; and 24.4%, 48.1%, and 27.5% in the controls, respectively. We found that the CT and TT genotypes were associated with a significantly increased risk of gastric cancer (OR(CT) = 1.50, 95% confidence intervals, 95% CI: 1.28-1.76; OR(TT) = 1.71, 95% CI: 1.43-2.04), compared with the CC genotype. Further, stratified by tumor location and histological type, the effect of the rs2294008 T allele was larger in cardia (OR(TT) = 2.62, 95% CI = 1.42-4.85) than non-cardia (OR(TT) = 1.67, 95% CI = 1.40-2.00), in diffuse-type (OR(TT) = 2.00, 95% CI: 1.55-2.59) than in intestinal-type (OR(TT) = 1.51, 95% CI: 1.22-1.86). Our study showed that rs2294008 in the PSCA gene was associated with increased risks of gastric cancer in a Korean population, suggests that rs2294008 might play an important role in gastric carcinogenesis.

Genetic susceptibility to bladder cancer risk and outcome

Bladder cancer is an excellent model for studying genetic susceptibility and gene-environment interaction in cancer etiology. The candidate gene approach found NAT2 slow acetylator and GSTM1-null genotypes to be bladder cancer susceptibility loci and also demonstrated interactions between these two genotypes and smoking in modulating bladder cancer risk. Recent genome-wide association studies identified at least eight novel genetic susceptibility loci for bladder cancer. Genetic determinants of clinical outcomes have been inconclusive. The future directions are to identify more genetic susceptibility loci for bladder cancer risk and outcome through a genome-wide association study approach, identify the causal genes and variants, study the biological mechanisms underlying the association between the causal variants and bladder cancer risk, detect gene-environment interactions and incorporate genetic knowledge into clinically applicable risk prediction models to benefit patients and public health.

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.

Genetic variation of PSCA gene is associated with the risk of both diffuse- and intestinal-type gastric cancer in a Chinese population

Prostate stem cell antigen (PSCA), a member of the LY-6/Thy-1 family of glycosylphosphatidylinositol-anchored cell surface proteins, is considered to be involved in the cell-proliferation inhibition and/or cell-death induction activity. Two single nucleotide polymorphisms (SNPs) (rs2976392 and rs2294008) in the PSCA gene were recently identified as the susceptibility loci of gastric cancer, especially in diffuse type. Therefore, this study was to investigate whether these 2 SNPs were associated with the risk of gastric cancer in Chinese population. We genotyped rs2976392 and rs2294008 in PSCA in a case-control study including 1,053 incident gastric cancer patients and 1,100 cancer-free controls in a high-risk Chinese population. We found that variant genotypes of rs2976392 (GA/AA) were associated with a significantly 37% increased risk of gastric cancer (adjusted OR =1.37, 95% CI = 1.15-1.62), compared with variant homozygote GG, and the associations were all consistently significant in both intestinal and diffuse subtypes, and among different subgroups stratified by age, sex, drinking or smoking status. Interestingly, a significant multiplicative interaction between rs2976392 (GA/AA) and alcohol drinking was detected on the development of intestinal-type gastric cancer (p = 0.009). However, rs2294008 variant genotypes (CT/TT) were associated with a nonsignificant increased risk of gastric cancer (adjusted OR = 1.14, 95% CI = 0.96-1.36). A small meta-analysis including 5 case-control studies showed undoubtedly associations between PSCA rs2294008 and rs2976392 and gastric cancer risk (OR = 1.83, 95% CI: 1.29-2.60 and OR = 1.84, 95% CI: 1.33-2.56, respectively). These findings provide further evidence supporting that the genetic variants of PSCA gene may contribute to the gastric carcinogenesis.

Genome-wide germline analyses on cancer susceptibility and GeMDBJ database: Gastric cancer as an example

The power of an SNP-based genome-wide association study (GWAS) was first demonstrated in Japan using the JSNP database and is currently a major strategy adopted around the world for a number of common diseases including cancers. The hypothesis-free strategy can lead us to a novel hypothesis for carcinogenesis and may contribute to identifying a high risk group for research and, in the future, practice of personalized prevention. We performed a GWAS on diffuse-type gastric cancer and identified a significant association with SNPs in the PSCA (prostate stem cell antigen) gene. The association was validated by a Korean gastric case-control analysis. The PSCA protein is expressed predominantly in the stem cell/precursor-rich region of the gastric epithelium, which is considered as the origin of diffuse-type gastric cancer, and showed tumor suppressor-like characteristics. Individuals with a low PSCA promoter activity are susceptible to diffuse-type gastric cancer. By contrast, the polymorphism does not significantly predispose to intestinal-type gastric cancer, congruous to the hypothesis of the two distinct carcinogenesis pathways for the two major types of gastric cancer. In addition to publication on a specific gene, the sharing of GWAS data through a database on the web is expected to accelerate validation and discovery by other investigators. GeMDBJ (Genome Medicine Database of Japan), started in 2005 in Japan, is one of such attempts. Moreover, the advent of "next generation" sequencers may herald a new era in which the poorly explored domains of the genetic architecture of disease susceptibility may be unveiled.

Prostate stem cell antigen: a Jekyll and Hyde molecule?

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein. Although PSCA is thought to be involved in intracellular signaling, much remains unknown about its physiological function and regulatory mechanism in normal and cancer cells. It is up-regulated in several major cancers including prostate, bladder, and pancreatic cancers. The expression of PSCA is positively correlated with advanced clinical stage and metastasis in prostate cancers and is also associated with malignant progression of premalignant prostate lesions. Therefore, PSCA has been proposed as a biomarker of diagnosis and prognosis, as well as a target of therapy for these cancers. In addition, PSCA has also shown clinical potential in immunotherapy as a prostate-specific antigen, which, when presented by dendritic cells, may elicit strong tumor-specific immunity. In contrast, PSCA is down-regulated in esophageal and gastric cancer and may have a tumor-suppressing function in the gastric epithelium. Recent exciting findings that genetic variations of PSCA conferred increased risks of gastric cancer and bladder cancer have opened up a new avenue of research about the pathological function of PSCA. PSCA seems to be a Jekyll and Hyde molecule that plays differential roles, tumor promoting or suppressing, depending on the cellular context.

Two genetic variants in prostate stem cell antigen and gastric cancer susceptibility in a Chinese population

Genetic factors play important roles in pathogenesis of human cancer. A recent genome-wide association study (GWAS) linked two single nucleotide polymorphisms (SNPs) in prostate stem cell antigen (PSCA), rs2294008C>T and rs2976392G>A, to risk of diffuse-type of gastric cancer in Japanese and Korean populations. We hypothesized that these two SNPs are also associated with risk of gastric cancer in Chinese population. We examined genotypes and haplotypes of PSCA, rs2294008C/T and rs2976392G/A in 716 patients with cardia gastric carcinoma (CGC), 1020 patients with noncardia gastric carcinoma (NCGC), and 1020 controls. We found that individuals with at least one copy of the rs2294008T allele (CT or TT genotype) had an elevated risk for developing NCGC compared with those without this allele (OR = 1.35, 95% CI = 1.13-1.61). Individuals with at least one copy of the rs2976392A allele (GA or AA genotype) had nonsignificantly increased risk for NCGC compared with those without this allele (OR = 1.20, 95% CI = 1.01-1.43). Stratification analysis showed that the increased risk associated with the SNPs was restricted in female subjects. Moreover, the rs2294008T and rs2976392A allele carriers were predisposed to developing poorly differentiated and high stage NCGC at diagnosis. However, no such association was detected for CGC. In addition, we observed considerably lower allelic and genotype frequencies of these genetic variants in Chinese population compared with Japanese and Korean populations. These findings are in general consistent with previous GWAS and suggest that PSCA may play a role in the development of NCGC in Chinese population.

Genetic variation in the prostate stem cell antigen gene PSCA confers susceptibility to urinary bladder cancer

We conducted a genome-wide association study on 969 bladder cancer cases and 957 controls from Texas. For fast-track validation, we evaluated 60 SNPs in three additional US populations and validated the top SNP in nine European populations. A missense variant (rs2294008) in the PSCA gene showed consistent association with bladder cancer in US and European populations. Combining all subjects (6,667 cases, 39,590 controls), the overall P-value was 2.14 x 10(-10) and the allelic odds ratio was 1.15 (95% confidence interval 1.10-1.20). rs2294008 alters the start codon and is predicted to cause truncation of nine amino acids from the N-terminal signal sequence of the primary PSCA translation product. In vitro reporter gene assay showed that the variant allele significantly reduced promoter activity. Resequencing of the PSCA genomic region showed that rs2294008 is the only common missense SNP in PSCA. Our data identify rs2294008 as a new bladder cancer susceptibility locus.

Expression of the gastrin-releasing peptide receptor, the prostate stem cell antigen and the prostate-specific membrane antigen in lymph node and bone metastases of prostate cancer

OBJECTIVE

Cell membrane antigens like the gastrin-releasing peptide receptor (GRPR), the prostate stem cell antigen (PSCA), and the prostate-specific membrane antigen (PSMA), expressed in prostate cancer, are attractive targets for new therapeutic and diagnostic applications. Therefore, we investigated in this study whether these antigens are expressed in metastasized prostate cancer.

METHODS

Formalin-fixed, paraffin-embedded specimens of 15 patients with uni- or bilateral lymph node metastases of prostate cancer (totaling 21 cases) and 17 patient-cases of bone metastases were processed for immunohistochemistry with anti-GRPR, anti-PSCA, and anti-PSMA antibodies. A pathologist blinded to clinical and pathological data scored the immunoreactivity for these antibodies on a four-point scale (0 = no staining; 1+ = weak staining; 2+ = moderate staining; 3+ = strong staining) and documented the distribution pattern.

RESULTS

GRPR staining in lymph node metastases was seen in 85.7% of cases (18 of 21 cases), PSCA in 95.2% (20/21), and PSMA in 100% (21/21). GRPR in bone metastases was seen in 52.9% of cases (9/17), PSCA in 94.1% (16/17), and PSMA in 100% (17/17).

CONCLUSION

We have shown for the first time that GRPR is expressed in the vast majority of lymph node metastases and in 52.9% of bone metastases of prostate cancer. PSCA and PSMA are both highly expressed in lymph node and bone metastases. Although PSCA and PSMA are mostly expressed in prostate cancer metastases, GRPR offers an interesting alternative target as it can be targeted relatively easy with peptide-based (radio)pharmaceuticals.

Genes involved in differentiation, stem cell renewal, and tumorigenesis are modulated in telomerase-immortalized human urothelial cells

The expression of hTERT, the catalytic subunit of telomerase, immortalizes normal human urothelial cells (NHUC). Expression of a modified hTERT, without the ability to act in telomere maintenance, did not immortalize NHUC, confirming that effects at telomeres are required for urothelial immortalization. Previous studies indicate that inhibition of telomerase has an immediate effect on urothelial carcinoma (UC) cell line viability, before sufficient divisions to account for telomere attrition, implicating non-telomere effects of telomerase in UC. We analyzed the effects of telomerase on gene expression in isogenic mortal and hTERT-transduced NHUC. hTERT expression led to consistent alterations in the expression of genes predicted to be of phenotypic significance in tumorigenesis. A subset of expression changes were detected soon after transduction with hTERT and persisted with continued culture. These genes (NME5, PSCA, TSPYL5, LY75, IGFBP2, IGF2, CEACAM6, XG, NOX5, KAL1, and HPGD) include eight previously identified as polycomb group targets. TERT-NHUC showed overexpression of the polycomb repressor complex (PRC1 and PRC4) components, BMI1 and SIRT1, and down-regulation of multiple PRC targets and genes associated with differentiation. TERT-NHUC at 100 population doublings, but not soon after transduction, showed increased saturation density and an attenuated differentiation response, indicating that these are not acute effects of telomerase expression. Some of the changes in gene expression identified may contribute to tumorigenesis. Expression of NME5 and NDN was down-regulated in UC cell lines and tumors. Our data supports the concept of both telomere-based and non-telomere effects of telomerase and provides further rationale for the use of telomerase inhibitors in UC.

Topology of NGEP, a prostate-specific cell:cell junction protein widely expressed in many cancers of different grade level

New gene expressed in prostate (NGEP) is a prostate-specific polytopic membrane protein found at high concentrations at cell:cell contact regions. To determine if NGEP is a useful target for antibody-based therapy of prostate cancer, we performed an immunohistochemical analysis of 126 human prostate carcinoma samples using polyclonal anti-NGEP sera and found that 91% of the cancers express NGEP protein. To elucidate the topology of NGEP and guide the development of monoclonal antibodies (mAb) reacting with the extracellular regions of NGEP, a hemagglutinin epitope tag was inserted at several positions within the NGEP sequence. The tagged proteins were expressed in 293T cells and locations of the tags were determined by immunofluorescence in intact or permeabilized cells. The results indicate that NGEP contains eight transmembrane domains with both the NH(2) and COOH termini of NGEP located inside the cell. We produced mAb to three regions that are predicted to be intracellular based on the epitope tag data (amino acids 1-352, 441-501, and 868-933), and as predicted, the mAb only detected the protein in permeabilized cells. NGEP is a glycoprotein with predicted glycosylation sites at N809 and N824. When these residues were converted to glutamine, glycosylation was abolished, confirming that the residues are extracellular. Our findings on the expression and the orientation of the NGEP protein serve as an important framework for the development of mAb targeting the extracellular regions of NGEP that could be used for prostate cancer immunotherapy.

Genetic variation in PSCA is associated with susceptibility to diffuse-type gastric cancer

Gastric cancer is classified into intestinal and diffuse types, the latter including a highly malignant form, linitis plastica. A two-stage genome-wide association study (stage 1: 85,576 SNPs on 188 cases and 752 references; stage 2: 2,753 SNPs on 749 cases and 750 controls) in Japan identified a significant association between an intronic SNP (rs2976392) in PSCA (prostate stem cell antigen) and diffuse-type gastric cancer (allele-specific odds ratio (OR) = 1.62, 95% CI = 1.38-1.89, P = 1.11 x 10(-9)). The association was far less significant in intestinal-type gastric cancer. We found that PSCA is expressed in differentiating gastric epithelial cells, has a cell-proliferation inhibition activity in vitro and is frequently silenced in gastric cancer. Substitution of the C allele with the risk allele T at a SNP in the first exon (rs2294008, which has r(2) = 0.995, D' = 0.999 with rs2976392) reduces transcriptional activity of an upstream fragment of the gene. The same risk allele was also significantly associated with diffuse-type gastric cancer in 457 cases and 390 controls in Korea (allele-specific OR = 1.90, 95% CI = 1.56-2.33, P = 8.01 x 10(-11)). The polymorphism of the PSCA gene, which is possibly involved in regulating gastric epithelial-cell proliferation, influences susceptibility to diffuse-type gastric cancer.

Prostate stem cell antigen vaccination induces a long-term protective immune response against prostate cancer in the absence of autoimmunity

Prostate stem cell antigen (PSCA) is an attractive antigen to target using therapeutic vaccines because of its overexpression in prostate cancer, especially in metastatic tissues, and its limited expression in other organs. Our studies offer the first evidence that a PSCA-based vaccine can induce long-term protection against prostate cancer development in prostate cancer-prone transgenic adenocarcinoma mouse prostate (TRAMP) mice. Eight-week-old TRAMP mice displaying prostate intraepithelial neoplasia were vaccinated with a heterologous prime/boost strategy consisting of gene gun-delivered PSCA-cDNA followed by Venezuelan equine encephalitis virus replicons encoding PSCA. Our results show the induction of an immune response against a newly defined PSCA epitope that is mediated primarily by CD8 T cells. The prostates of PSCA-vaccinated mice were infiltrated by CD4-positive, CD8-positive, CD11b-positive, and CD11c-positive cells. Vaccination induced MHC class I expression and cytokine production [IFN-gamma, tumor necrosis factor-alpha, interleukin 2 (IL-2), IL-4, and IL-5] within prostate tumors. This tumor microenvironment correlated with low Gleason scores and weak PSCA staining on tumor cells present in hyperplastic zones and in areas that contained focal and well-differentiated adenocarcinomas. PSCA-vaccinated TRAMP mice had a 90% survival rate at 12 months of age. In contrast, all control mice had succumbed to prostate cancer or had heavy tumor loads. Crucially, this long-term protective immune response was not associated with any measurable induction of autoimmunity. The possibility of inducing long-term protection against prostate cancer by vaccination at the earliest signs of its development has the potential to cause a dramatic paradigm shift in the treatment of this disease.

Deletion of PSCA increases metastasis of TRAMP-induced prostate tumors without altering primary tumor formation

BACKGROUND

Prostate stem cell antigen (PSCA) is expressed in normal epithelium of various tissues, in embryos and adult animals. PSCA expression is upregulated in up to 70% of prostate tumors and metastases, and a subset of bladder and pancreatic cancers. However, its function is unknown. We studied the effect of targeted gene deletion of PSCA on normal organ development and prostate carcinogenesis.

METHODS

PSCA +/+, PSCA +/-, and PSCA -/- mice were bred and aged to 22 months. A cohort of animals was treated with gamma-irradiation at 2 and 6 months of age. PSCA knockout mice were crossed to TRAMP mice and TRAMP+ PSCA +/+, TRAMP+ PSCA +/-, and TRAMP+ PSCA -/- mice and offspring aged to 10 months of age. Tissues were analyzed by RT-PCR, histology, and immunohistochemistry for markers of proliferation, apoptosis, angiogenesis, and tumor progression.

RESULTS

PSCA knockout animals were viable, fertile and indistinguishable from wild-type littermates. Spontaneous or radiation-induced primary epithelial tumor formation was also similar in wild-type and PSCA knockout mice. We observed an increased frequency of metastasis in TRAMP+ PSCA heterozygous and knockout mice, compared to TRAMP+ wild-type mice. Metastases were largely negative for PSCA and androgen receptor. Cleaved-caspase 3 and CD31 staining was similar in all genotypes. Aurora-A and Aurora-B kinases were detected in the cytoplasm of PSCA heterozygous and knockout tumors, suggesting aberrant kinase function.

CONCLUSION

These data suggest that PSCA may play a role in limiting tumor progression in certain contexts, and deletion of PSCA may promote tumor migration and metastasis.

Utilizing quantitative polymerase chain reaction to evaluate prostate stem cell antigen as a tumor marker in pancreatic cancer

BACKGROUND

Real-time quantitative polymerase chain reaction (qPCR) may prove to be a sensitive technique by which to evaluate potential tumor markers in pancreatic cancer.

METHODS

The prostate stem cell antigen (PSCA) gene was identified as a marker highly expressed in pancreatic adenocarcinoma and not normal pancreas. RNA from pancreatic and nonpancreatic cancer cell lines as well as tissue and blood from pancreatic cancer and control patients was reverse-transcribed and PSCA quantified by qPCR.

RESULTS

Individual operator experience affects the results of qPCR, with significantly different copy numbers at experiment numbers 5, 15, and 40. Five of six pancreatic cell lines had PSCA/actin ratios 10-fold greater than nonpancreatic cancer lines. Mean PSCA expression in pancreatic tumor tissue was significantly higher (P < 0.05, Student's t-test) than in the tissue of benign pancreatic processes. The close correlation of PSCA/actin copy number with number of tumor cells in the blood was demonstrated by regression analysis (r = 0.768, P = 0.0001). PSCA copy number was significantly higher in the blood of patients with metastatic pancreatic cancer than in that of normal patients (P < 0.05, Student's t-test).

CONCLUSIONS

Such trends suggest that PSCA may prove to be a valuable pancreatic cancer tumor marker. More generally, the technique of qPCR is shown to provide a sensitive method of evaluating markers in cancer patients.

Gene expression profiling in R-flurbiprofen-treated prostate cancer: R-Flurbiprofen regulates prostate stem cell antigen through activation of AKT kinase

We have used gene expression profiling to characterize genes regulated by the anti-tumor non-steroidal anti-inflammatory drug (NSAID)-like agent R-flurbiprofen (RFB) in murine TRAMP prostate cancer. Mice with spontaneous, palpable tumors were treated with RFB 25 mg/(kgd) x 7d orally, or vehicle only. RNA was then extracted from tumor tissue and used for microarray analysis with Affymetrix chips. Fifty-eight genes were reproducibly regulated by RFB treatment. One of the most highly up-regulated genes was prostate stem cell antigen (psca). We used TRAMP C1 murine prostate cancer cells to examine potential mechanisms through which RFB could regulate psca. RFB induced dose-dependent expression of PSCA protein, and activity of the psca promoter, in TRAMP C1 cells in culture. Increased psca promoter activity was also seen following treatment of cells with sulindac sulfone, another NSAID-like agent, but not with celecoxib treatment. RFB activation of the psca promoter could be attenuated by co-transfection of dominant-negative akt and h-ras constructs, but not by dominant-negative mek1 plasmids. Immunoblotting revealed that RFB increased expression of phosphorylated AKT at concentrations that stimulated psca promoter activity, and that increased PSCA protein expression. In addition, RFB-dependent up-regulation of PSCA protein expression could be blocked by AKT inhibitors. These data demonstrate that RFB, and possibly other NSAID-like analogs, can increase expression of the psca gene both in vivo and in culture. They further suggest the utility of combining RFB with AKT inhibitors or with monoclonal antibodies targeting PSCA protein, for treatment or prevention of prostate cancer.

The expression of prostate stem cell antigen in human clear cell renal cell carcinoma: a quantitative reverse transcriptase-polymerase chain reaction analysis

OBJECTIVES

To analyse the gene expression level of prostate stem cell antigen (PSCA) in human clear cell renal cell carcinoma (CC-RCC) and its relationship with conventional clinicopathological manifestations, to evaluate its prognostic value for patient outcome, and to determine the effect of PSCA on the progression of CC-RCC.

PATIENTS AND METHODS

We quantified PSCA mRNA level in human RCC cell lines (ACHN, A704, KPK-1, Caki-1, and Caki-2) and in 154 surgical tissue samples (81 from CC-RCC, 73 from normal kidney) using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The findings were analysed in relation to clinicopathological factors. Immunohistochemical expression was examined using confocal laser scanning light-microscopy.

RESULTS

PSCA was overexpressed in all RCC cell lines. PSCA mRNA levels were significantly higher in CC-RCC than in normal kidney tissue samples (P < 0.001), in G2-G3 than in G1 tumours (P = 0.028), and in advanced disease (T3-T4) than in organ-confined (T1-T2) tumours (P = 0.016). There was significantly higher PSCA mRNA expression in patients with M1 than in those with M0 disease (P = 0.029). Patients in whom the lesions had high PSCA expression levels had a significantly worse prognosis than those with low PSCA expression levels (P = 0.044). Using immunohistochemical analysis there was markedly greater PSCA expression in CC-RCC than in normal kidney, and in advanced-disease high-grade tumours than in organ-confined low-grade tumours.

CONCLUSIONS

A significant correlation was detected in the gene expression level of PSCA with histological grade, clinicopathological stage and prognosis in CC-RCC. Our data indicate that PSCA is associated with carcinogenesis and progression of CC-RCC.

Prostate stem cell antigen predicts tumour recurrence in superficial transitional cell carcinoma of the urinary bladder

OBJECTIVES

To evaluate the relationship between prostate stem cell antigen (PSCA) expression level in transitional cell carcinoma (TCC) of the urinary bladder and various clinicopathological features, including stage and grade; and to determine whether PSCA mRNA expression predicts disease recurrence in superficial (not muscle-invasive) TCC of the bladder.

PATIENTS AND METHODS

Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on 97 TCC tissue samples and in 36 samples of normal bladder urothelium; the findings were analysed in relation to clinicopathological factors. Immunohistochemical expression was examined using light and confocal immunofluorescence microscopy to validate the RT-PCR data.

RESULTS

Twenty-seven patients developed disease recurrence, while the remaining 22 had no evidence of recurrence of superficial TCC of the bladder. There was significantly higher PSCA mRNA expression in TCC than in normal urothelium samples (P = 0.008). Superficial (TaT1) tumours had significantly higher PSCA expression than muscle-invasive (> or = pT2) tumours (P < 0.001). There was no significant difference between patients with G1-2 tumours and those with G3 tumours (P = 0.109). Immunohistochemical analysis showed markedly greater PSCA expression in superficial than invasive TCC. Notably, from a multivariate analysis, the expression level of PSCA was an independent predictor of disease recurrence in superficial TCC (P = 0.012).

CONCLUSIONS

These findings suggest that the PSCA expression level measured by real-time RT-PCR could be a valuable prognostic marker for tumour recurrence in superficial TCC of the bladder.

KCNE2, a down-regulated gene identified by in silico analysis, suppressed proliferation of gastric cancer cells

It is important to identify the differentially expressed gene in gastric cancer for elucidating the molecular mechanisms of tumorigenesis of stomach. Here, 38 genes differentially expressed genes between gastric cancer and normal gastric mucosa by in silico approaches. A potassium channel protein KCNE2, identified as a down-regulated gene in gastric cancer, was chosen for further study. We investigated the expression of KCNE2 in gastric cancer tissues and cell lines and examined the effect of KCNE2 on proliferation of gastric cancer. The expression of KCNE2 was markedly down-regulated in gastric cancer tissues and cell lines. Forced overexpression of KCNE2 suppressed the growth of SGC7901 cells and cell cycle progression significantly, which might be related to the down-regulation of Cyclin D1. KCNE2 also inhibited SGC7901 cell growth in soft agar and its tumorigenicity in nude mice. Taken together, our work showed that in silico analysis approaches could be used to identify cancer-related genes effectively. KCNE2, as a novel down-regulated gene in gastric cancer, suppressed cell proliferation and tumorigenesis of stomach.

The immunotherapy of prostate and bladder cancer

The role of the immune system in controlling the growth of tumour cells is highly complex and has been extensively debated. It is well documented that the immune system controls virally induced cancers, and there is evidence for a role of specific immunity in other types of tumours. The greater understanding of the regulation and optimization of adoptive, specific immune responses, and the better characterization of tumour-associated antigens indicate the way for active specific vaccination and cell therapy in urological tumours. Currently, bacille Calmette Guerin immunotherapy is established for localized bladder cancer and many experimental immunotherapies are under evaluation. Here we review some timely aspects of tumour immunology, and describe the current status and development of immunotherapy in prostate and bladder cancer.

Profiling, comparison and validation of gene expression in gastric carcinoma and normal stomach

Gastric carcinoma is the fourth most common cause of cancer death worldwide but its molecular biology is poorly understood. We catalogued the genes expressed in two gastric adenocarcinomas and normal stomach, using serial analysis of gene expression (SAGE), and compared the profiles on-line with other glandular epithelia. Candidates were validated by Northern blotting and immunohistochemistry. A total of 29 480 transcripts, derived from 10 866 genes, were identified. In all, 1% of the genes were differentially expressed (>/=fivefold difference plus P-value </=0.01) between cancers and normal stomach. The most abundant transcripts included ribosomal and mitochondrial proteins, of which most were upregulated in the tumours, as were other widely expressed genes including transcription factors, signalling molecules (serine/threonine protein kinases), thymosin beta 10 and collagenase I. Transcripts abundant in normal stomach were functionally important, including gastrin, immunoglobulin alpha, lysozyme, MUC5, pS2 and pepsinogens, which were among 55 gastric-specific genes. Many transcripts were minimally characterized or new, some cancer-associated genes reflected their intestinal morphology, and some normal gastric genes had previously been considered as pancreatic carcinoma markers. The gastric carcinoma profiles resembled other tumours', supporting the existence of common cancer-associated targets. These data provide a catalogue from which to develop markers for better diagnosis and therapy of gastric carcinoma.

Analysis of gene expression profiles of gastric normal and cancer tissues by SAGE

In an attempt to understand the molecular bases of gastric cancer progression, we have analyzed the differentially expressed genes in gastric cancer by SAGE. Four SAGE cDNA tag libraries were constructed from two sets of gastric cancer and normal tissues and 241,127 tags were obtained. By comparing the tags from cancer and normal tissues, 414 differentially expressed tags, representing 383 genes, were identified in cancer tissues (p </= 0.01). Of the 414 tags, 50 tags were previously unidentified and potentially novel genes. Although each gastric cancer tissue revealed more than 200 differentially expressed genes compared to the respective normal tissue, the number of genes with consistent regulation patterns in both cancer tissues was 51: 12 up-regulated and 39 down-regulated genes. The genes that showed consistent regulation patterns included well-known genes such as Trefoil factor 3, RegIV, gastric intrinsic factor, and lactotransferrin as well as a few novel candidates. Interestingly, the expression of several genes, such as osteoglycin, prostate stem cell antigen, and histone deacetylase 3, was variable in the two normal tissues but similar in the cancer tissues. The expression profiles of these genes in normal tissues, possibly due to genetic background, could greatly affect individual sensitivity to cancer development and/or progression. The genes identified in this study will provide useful target genes for diagnosis and molecular treatment of gastric cancer.

Immunocytochemical analysis of prostate stem cell antigen as adjunct marker for detection of urothelial transitional cell carcinoma in voided urine specimens

PURPOSE

Prostate stem cell antigen (PSCA), a homologue of the Ly-6/Thy-1 family of cell surface antigens, has been shown to be increased in a majority of human transitional cell carcinomas. We tested the possibility of using PSCA as an adjunct marker for urine cytology.

MATERIALS AND METHODS

Immunocytochemical analysis was performed on 44 archived voided urine samples obtained from 3 groups of patients based on initial voided urine cytological results and subsequent followup biopsy findings. Group 1 (14 of 44 patients) had positive findings on cytology and histology, group 2 (16 of 44) had negative cytology but positive histology, and group 3 (14 of 44) had negative findings on cytology and histology. Cytological slides prepared from 10 fresh voided urine samples were also analyzed. Papanicoloau stained archived urine slides were de-stained and re-stained immunocytochemically with a monoclonal antibody against PSCA. Immunofluorescence followed by laser scanning cytometer analysis was also performed on archived slides from 2 representative cases.

RESULTS

Sensitivity and specificity were 46.7% and 100% for cytology alone, respectively, and 80% and 85.7% for PSCA alone, respectively. PSCA immunostaining was positive in 92.8% group 1, 68.8% group 2 and only 14.3% group 3 samples. The difference in positive PSCA findings in groups 2 and 3 were statistically significant at p <0.01 by chi-square test. Whereas some superficial umbrella cells showed slight staining by immunocytochemistry, it was feasible to distinguish the expression levels between tumor and normal superficial umbrella cells quantitatively using immunofluorescence coupled with laser scan cytometry analysis.

CONCLUSIONS

Immunocytochemical analysis of PSCA on archived voided urine samples may provide a simple and quantitative adjunct marker for cytological diagnosis of urothelial carcinoma.

Characterization of the human Ly-6 antigens, the newly annotated member Ly-6K included, as molecular markers for head-and-neck squamous cell carcinoma

The E48 antigen is a successfully explored molecular marker for the diagnosis and therapy of HNSCC. The applicability of E48 as an HNSCC-associated antigen, however, is restricted due to its heterogeneous expression in 30% of tumors; and identification of additional target antigens is therefore desired. E48 belongs to the Ly-6 antigen family, comprising a group of highly homologous, low m.w., GPI-anchored surface proteins, of which some show tissue-restricted expression patterns. To identify novel human HNSCC-associated Ly-6 members with squamous cell-associated expression patterns, we performed comprehensive gene-screening consisting of BLAST searches within GenBank databases, followed by expression analysis. Using this approach, the Ly-6K gene could be annotated as a novel member of the human Ly-6 family. Expression of the human Ly-6 genes E48, Ly-6K, PSCA, GML, RIG-E, G6C and Ly-6H was prescreened by qualitative RT-PCR and subsequently analyzed by quantitative RT-PCR in normal keratinocytes, HNSCC cell lines, normal mucosa, HNSCC tumors as well as normal peripheral blood and bone marrow cells. PSCA was highly expressed in normal mucosa, but 100-fold decreased expression was seen in HNSCC. For Ly-6H, GML and G6C, no or very low expression was observed in keratinocytes and HNSCC. Expression of RIG-E was high in normal and malignant squamous cells and in peripheral blood and bone marrow cells, thus limiting its applicability as an HNSCC-associated marker. In contrast, besides the E48 gene, the Ly-6K gene also appeared to be selectively expressed in HNSCC and normal squamous cells. Moreover, expression of Ly-6K was shown in HNSCC cell lines, in which no E48 expression could be detected. These data justify further evaluation of Ly-6K as potential target antigen for the diagnosis and therapy of HNSCC.

Gene expression profiling of human diseases by serial analysis of gene expression

Until recently, the approach to understanding the molecular basis of complex syndromes such as cancer, coronary artery disease, and diabetes was to study the behavior of individual genes. However, it is generally recognized that expression of a number of genes is coordinated both spatially and temporally and that this coordination changes during the development and progression of diseases. Newly developed functional genomic approaches, such as serial analysis of gene expression (SAGE) and DNA microarrays have enabled researchers to determine the expression pattern of thousands of genes simultaneously. One attractive feature of SAGE compared to microarrays is its ability to quantify gene expression without prior sequence information or information about genes that are thought to be expressed. SAGE has been successfully applied to the gene expression profiling of a number of human diseases. In this review, we will first discuss SAGE technique and contrast it to microarray. We will then highlight new biological insights that have emerged from its application to the study of human diseases.

Mapping and gene expression profile of the minimally overrepresented 8q24 region in prostate cancer

We have recently reported that overrepresentation of 8q24 (c-myc) is associated with clinical progression in prostate cancer. In this study, we map the boundaries of the overrepresented region within 8q23-q24 using interphase fluorescent in situ hybridization analysis of paraffin-embedded prostate cancer specimens. One hundred primary prostate cancers and three prostate cancer cell lines were evaluated, and the minimally overrepresented region could be narrowed to the approximately 8.2-Mb region between D8S514 and H47317. This region includes c-myc and is wholly within 8q24. Eukaryotic translation initiation factor 3 subunit 3 does not seem to be overrepresented independent of c-myc in prostate cancer. The cell lines PC3 and DU145 have and do not have 8q24 overrepresentation, respectively. We then selected 39 expressed sequence tags (ESTs) within and surrounding the minimally overrepresented region and performed expression analysis using Northern blot hybridization. Five ESTs/genes including c-myc were overexpressed in both the PC3 cell line and DU145, but the PC3 to DU145 expression ratios were <2. Seven ESTs were overexpressed twofold or more in PC3 compared to DU145. This group included hyaluronan synthase 2, nephroblastoma-overexpressed gene, eukaryotic translation initiation factor 3 subunit 3, and an EST (R69368) encoding a hypothetical protein (BM009). These seven genes as well as c-myc are candidate target genes within the overrepresented 8q24 region and their overexpression may be associated with prostate cancer progression.

PSCA expression is regulated by phorbol ester and cell adhesion in the bladder carcinoma cell line RT112

The expression of the surface protein prostate stem cell antigen (PSCA) in prostate carcinoma increases in parallel with the progression of the tumor. In contrast, we have recently shown that PSCA expression is reduced or undetectable in other types of undifferentiated tumors. To elucidate the cellular mechanisms that underlie this complex pattern of expression, we studied regulatory parameters for PSCA expression in the bladder carcinoma cell line RT112 by Northern analysis. PSCA gene expression was stimulated by a culture dish surface that caused aggregation of cells, suggesting that its expression is regulated by mechanisms related to the adhesion of epithelial cells. Phorbol ester markedly stimulated PSCA gene expression in a cycloheximide- and actinomycin-inhibitable manner after a lag phase of 10 h, indicating that transcription of the PSCA gene is regulated by protein kinase C and a newly synthesized protein. In contrast, epidermal growth factor, platelet-derived growth factor (PDGF)-BB, tumor necrosis factor-alpha, interferon-gamma or a slightly lowered pH failed to increase PSCA mRNA levels. Consistent with the variable expression of PSCA in different tumors, our analysis in RT112 cells shows that its expression is controlled by a strongly inducible promoter that is specifically regulated by extracellular signals.

Gene discovery using the serial analysis of gene expression technique: implications for cancer research

Cancer is a genetic disease. As such, our understanding of the pathobiology of tumors derives from analyses of the genes whose mutations are responsible for those tumors. The cancer phenotype, however, likely reflects the changes in the expression patterns of hundreds or even thousands of genes that occur as a consequence of the primary mutation of an oncogene or a tumor suppressor gene. Recently developed functional genomic approaches, such as DNA microarrays and serial analysis of gene expression (SAGE), have enabled researchers to determine the expression level of every gene in a given cell population, which represents that cell population's entire transcriptome. The most attractive feature of SAGE is its ability to evaluate the expression pattern of thousands of genes in a quantitative manner without prior sequence information. This feature has been exploited in three extremely powerful applications of the technology: the definition of transcriptomes, the analysis of differences between the gene expression patterns of cancer cells and their normal counterparts, and the identification of downstream targets of oncogenes and tumor suppressor genes. Comprehensive analyses of gene expression not only will further understanding of growth regulatory pathways and the processes of tumorigenesis but also may identify new diagnostic and prognostic markers as well as potential targets for therapeutic intervention.

Selective expression of murine prostate stem cell antigen in fetal and adult tissues and the transgenic adenocarcinoma of the mouse prostate model of prostate carcinogenesis

Prostate stem cell antigen (PSCA) is a GPI-anchored membrane protein whose expression is reportedly up-regulated in a majority of human prostate cancers, including advanced stages and metastases. In this study, we investigate the expression pattern of the murine orthologue of PSCA by in situ hybridization in fetal and adult mouse tissues. Murine PSCA is expressed during fetal development in the urogenital sinus, skin, and gastrointestinal tract. The expression in these tissues is restricted to the most superficial cell layer. In the adult mouse, expression is highest in the mucosal lining of the urinary tract. In the normal adult prostate, expression of PSCA is detected exclusively in the secretory epithelium. Examination of PSCA during carcinogenesis of the murine prostate in the transgenic adenocarcinoma of the mouse prostate model showed a markedly increased expression in areas of neoplasia. The transgenic adenocarcinoma of the mouse prostate model may represent a valuable model for the study of PSCA as a potential target for immunotherapy of prostate cancer, despite potential differences in the pattern of expression between mice and humans.