Early-onset gastric cancers have a different molecular expression profile than conventional gastric cancers

E-cadherin genetic screening and clinico-pathologic characteristics of early onset gastric cancer

AIM

CDH1 germline alterations occur in about 40% of hereditary diffuse gastric cancer (HDGC) families. CDH1 germline mutations are also documented in few early onset diffuse gastric cancer patients (EODGC) without family history, but the real frequency in this setting in unknown. In these patients, the advanced stage at the time of diagnosis remains a clinical burden due to the poor long term survival.

METHODS

The entire coding region and exon flanking sequences of the CDH1 gene was analysed by direct sequencing in 21 EODGC patients aged ≤50 years. The potential deleterious nature for a new CDH1 missense variant was assessed by cell-cell aggregation and invasion assays. Somatic CDH1 mutation, loss of heterozygosity (LOH) and promoter hypermethylation was explored in the tumour from one CDH1 germline mutation carrier.

RESULTS

Two novel CDH1 germline variants were identified in 21 EODGC cases, c.670C>T and -63C>A. Functional analysis of the c.670C>T missense variant classified this mutation as non-pathogenic. The analysis of CDH1 somatic second hits failed to demonstrate E-cadherin structural and epigenetic alterations in the tumour sample.

CONCLUSION

Data from the present work and a systematic review of the literature revealed that CDH1 germline mutations occurred in 7.2% of EOGC patients invariably with diffuse of mixed histology. From these, proved CDH1 mutation pathogenicity has been assigned only to 2.3% of the cases who were recurrently diagnosed before 35 years old. Germline CDH1 mutation remain the only germline genetic defect described in this type of patients and CDH1 mutation screening should be recommended for patients with these characteristics.

Genetic epidemiological analysis reveals a multi-gene additive model for gastric cancer

A genetic epidemiologic analysis of gastric cancer in the Chinese Han population was conducted for 64 pedigrees (902 individuals) with gastric cancer and controls obtained from the population after a census was carried out in August 2007. The heritability of gastric cancer was performed using the Falconer method and the complex segregation analysis was performed using the Statistical Analysis for Genetic Epidemiology (S.A.G.E.) SEGREG program. The heritability of gastric cancer in first- and second-degree relatives was 54.75% (95% CI, 48.01-61.49%) and 44.97% (95% CI, 33.12-56.82%), respectively. The estimated segregation ratio of gastric cancer was 0.039 (95% CI, 0.017-0.061). The complex segregation analysis showed that the Mendelian inheritance of additive model provided the best fit to the data (AIC = 170.58, P > 0.05). Therefore, polygenetic or multi-factorial additive inheritance is involved in the genetic predisposition for the development of gastric cancer.

Hsa-mir-27a genetic variant contributes to gastric cancer susceptibility through affecting miR-27a and target gene expression

Aberrant microRNA (miRNA) expression is presently proposed to correlate with various human cancers and common single-nucleotide polymorphisms (SNP) at miRNA genes can influence the maturation of miRNAs or miRNA-mediated transcriptional regulation. However, whether miRNAs SNP alter gastric cancer susceptibility is still unclear. Here we investigated the possible role of a common A/G polymorphism (rs895819) within hsa-mir-27a in the development or progression of gastric cancer, and assessed the effect of rs895819 on the expression of miR-27a and its target gene Zinc finger and BTB domain containing 10 (ZBTB10). In the present case-control study, we found that subjects with the variant genotypes (AG + GG) showed a significantly increased risk of gastric cancer relative to AA carriers (adjusted odds ratio = 1.48, 95% confidence interval 1.06-2.05; P = 0.019). The elevated risk was especially evident in older subjects (age >58 years), men, nonsmokers and rural subjects. A significant association of hsa-mir-27a variant genotypes with lymph node metastasis was also observed. Further functional analyses indicated that variant genotypes might be responsible for elevated miR-27a levels and reduced ZBTB10 mRNA. Moreover, an inverse correlation was found between ZBTB10 and miR-27a levels. In conclusion, we were the first to show that a common polymorphism (rs895819) in hsa-mir-27a, by modulating miR-27a and ZBTB10 levels, acted as an important factor of the gastric cancer susceptibility.

Analysis of cell cycle-related proteins in gastric intramucosal differentiated-type cancers based on mucin phenotypes: a novel hypothesis of early gastric carcinogenesis based on mucin phenotype

Background

Abnormalities of cell cycle regulators are common features in human cancers, and several of these factors are associated with the early development of gastric cancers. However, recent studies have shown that gastric cancer tumorigenesis was characterized by mucin expression. Thus, expression patterns of cell cycle-related proteins were investigated in the early phase of differentiated-type gastric cancers to ascertain any mechanistic relationships with mucin phenotypes.

Methods

Immunostaining for Cyclins D1, A, E, and p21, p27, p53 and β-catenin was used to examine impairments of the cell cycle in 190 gastric intramucosal differentiated-type cancers. Mucin phenotypes were determined by the expressions of MUC5AC, MUC6, MUC2 and CD10. A Ki-67 positive rate (PR) was also examined.

Results

Overexpressions of p53, cyclin D1 and cyclin A were significantly more frequent in a gastric phenotype than an intestinal phenotype. Cyclin A was overexpressed in a mixed phenotype compared with an intestinal phenotype, while p27 overexpression was more frequent in an intestinal phenotype than in a mixed phenotype. Reduction of p21 was a common feature of the gastric intramucosal differentiated-type cancers examined.

Conclusions

Our results suggest that the levels of some cell cycle regulators appear to be associated with mucin phenotypes of early gastric differentiated-type cancers.

Early-onset gastric cancer: Learning lessons from the young

There is by no means a clear-cut pattern of mutations contributing to gastric cancers, and gastric cancer research can be hampered by the diversity of factors that can induce gastric cancer, such as Helicobacter pylori infection, diet, ageing and other environmental factors. Tumours are unquestionably riddled with genetic changes yet we are faced with an unsolvable puzzle with respect to a temporal relationship. It is postulated that inherited genetic factors may be more important in early-onset gastric cancer (EOGC) than in gastric cancers found in older patients as they have less exposure to environmental carcinogens. EOGC, therefore, could provide a key to unravelling the genetic changes in gastric carcinogenesis. Gastric cancers occurring in young patients provide an ideal background on which to try and uncover the initiating stages of gastric carcinogenesis. This review summarizes the literature regarding EOGC and also presents evidence that these cancers have a unique molecular-genetic phenotype, distinct from conventional gastric cancer.

IkappaBalpha polymorphism at promoter region (rs2233408) influences the susceptibility of gastric cancer in Chinese

Background

Nuclear factor of kappa B inhibitor alpha (IκBα) protein is implicated in regulating a variety of cellular process from inflammation to tumorigenesis. The objective of this study was to investigate the susceptibility of rs2233408 T/C genotype in the promoter region of IκBα to gastric cancer and the association of this polymorphism with clinicopathologic variables in gastric cancer patients.

Methods

A population-based case-control study was conducted between 1999 and 2006 in Guangdong Province, China. A total of 564 gastric cancer patients and 566 healthy controls were enrolled in this study. rs2233408 genotypes in IκBα were analyzed by TaqMan SNP genotyping assay.

Results

Both rs2233408 T homozygote (TT) and T heterozygotes (TC and TT) had significantly reduced gastric cancer risk (TT: OR = 0.250, 95% CI = 0.069-0.909, P = 0.035; TC and TT: OR = 0.721, 95% CI = 0.530-0.981, P = 0.037), compared with rs2233408 C homozygote (CC). rs2233408 T heterozygotes were significantly associated with reduced risk of intestinal-type gastric cancer with ORs of 0.648 (95% CI = 0.459-0.916, P = 0.014), but not with the diffuse or mix type of gastric cancer. The association between rs2233408 T heterozygotes and gastric cancer appeared more apparent in the older patients (age>40) (OR = 0.674, 95% CI = 0.484-0.939, P = 0.02). rs2233408 T heterozygotes was associated with non-cardiac gastric cancer (OR = 0.594, 95% CI = 0.411-0.859, P = 0.006), but not with cardiac gastric cancer. However, rs2233408 polymorphism was not associated with the prognosis of gastric cancer patients.

Conclusions

IκBα rs2233408 T heterozygotes were associated with reduced risk of gastric cancer, especially for the development of certain subtypes of gastric cancer in Chinese population.

Analysis of demographic characteristics in 3242 young age gastric cancer patients in Korea

AIM: To evaluate the epidemiologic features of young age gastric cancer (GC).

METHODS: Retrospectively, a total of 3242 patients with GC between 18 and 45 years of age and 3000 sex- and age-matched controls were reviewed. All subjects were stratified into 3 groups based on age (A, 18-30 years; B, 31-40 years; C, 41-45 years). Epidemiologic characteristics and risk factors were investigated with reference to their age and gender.

RESULTS: Compared to controls, more frequent intake of high risk diet (P = 0.00075), history of heavy smoking (P = 0.00087), intake of heavy alcohol (P = 0.00091), lower social economic status (P = 0.00083), body mass index > 30 (P = 0.00097), urban residence (P = 0.00065), and more frequent exposure to harmful occupational environments (P = 0.00072) were observed in all age groups and both genders in young age GC. These relationships were weaker in females compared to males of the same age, and were stronger as the age of patients increased. However, in group C of young age GC patients, environmental factors played important roles in females and males with a similar body weight. In females, older age at first delivery (> 35 years), lack of lactation history, nulliparity, and poor nutritional status during pregnancy were significantly associated with an increased risk of GC (P = 0.00034). In this study, 252 patients (7.8%) had a family history of GC with high odds ratio (OR) (3.22-4.21). In particular, family history was more closely associated with GC in males (OR, 4.21 in male vs 3.46 in female) and more advanced cases (P = 0.00051).

CONCLUSION: Hormonal associated factors were more commonly associated with females whereas environmental factors were more commonly associated with males in young age GC patients.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

Comparison of patients by family history with gastric and non-gastric cancer

AIM: To compare the gastric cancer (GC) patients by their family history with gastric and non-GC.

METHODS: Positive family histories within second-degree relatives and clinicopathological features were obtained for 256 patients.

RESULTS: Of the 256 probands, 112 (76 male, 36 female) were incorporated into familial GC (FGC) group: at least two GC members; 144 (98 male, 46 female) were included in the non-FGC group (relatives only affected with non-GCs). Of 399 tumors in relatives (181 from FGC against 212 from non-FGC), GC was the most frequent, followed by esophageal, hepatocellular, and colorectal cancer. Nasopharyngeal cancer was next to lung cancer but prior to breast and urogenital cancers. Most affected members aggregated within first-degree relatives (FGC: 66 siblings, 48 fathers, 31 mothers, four offspring; non-FGC: 56 fathers, 55 siblings, 43 mothers, and 15 offspring). The ratio of males to females in affected first-degree relatives was usually higher in male probands. Paternal history of GC was a slight risk for GC in males (OR = 1.19, 95% CI: 0.53-2.69), while risk of GC by maternal history of non-GCs was increased in females (OR = 0.46, 95% CI: 0.22-0.97). Diffuse-GC was the major histological type in all subgroups. Difference in tumor sites between the two groups was derived from an excess of upper sites in non-FGC female probands.

CONCLUSION: Distribution of associated non-GCs in a family history of GC may vary with geographic areas. GC may have different genetic and/or environmental etiology in different families, and a certain subtype may be inherited in a female-influenced fashion.

Cadherin-catenin adhesion system and mucin expression: a comparison between young and older patients with gastric carcinoma

BACKGROUND

Young patients are thought to develop gastric carcinomas with a molecular genetic profile that is distinct from that of gastric carcinomas occurring at a later age. The aim of this study was to compare the clinicopathological features and expression patterns of the markers E-cadherin and beta-catenin, and mucins (MUC1, MUC2, MUC5AC, and MUC6) in young and older patients.

METHODS

The clinicopathological features and overall survival data of 62 young patients (age <or=40 years) with gastric cancer were retrospectively reviewed from hospital records and compared with the data for 453 older patients (age >40 years). A tissue microarray method and immunohistochemistry were used in order to analyze marker expression in paraffin-embedded tissue blocks obtained from both groups.

RESULTS

The young group presented a higher percentage of diffuse-type tumors in comparison to the older group (P<0.01). The rates of positivity for E-cadherin and beta-catenin membranous expression patterns and mucin (MUC2, MUC5AC and MUC6) positivity were higher in the young group (P<0.01). Although young patients showed a lower frequency of alterations in marker expression and had significantly better survival rates than the older patients, neither age nor the marker expression pattern were found to be independent prognostic factors of survival. Only stage, tumor size, and tumor location persisted as prognostic factors for patients with gastric cancer.

CONCLUSION

Biological markers of cellular adhesion and gastric differentiation were differently expressed in young and older patients. Our findings support the hypothesis that young patients develop carcinomas with a different genetic pathway compared to the pathway of tumors occurring at a later age, and we suggest further investigations to assess the prognostic relevance of the markers to specific subgroups.

Increased cyclooxygenase-2 expression in juvenile polyposis syndrome

BACKGROUND & AIMS

Gastrointestinal juvenile polyps may occur in juvenile polyposis syndrome (JPS) or sporadically. JPS is an autosomal-dominant condition caused by a germline defect in SMAD4 or BMPR1A in 50% to 60% of cases, and is characterized by multiple juvenile polyps, predominantly in the colorectum. JPS has an increased risk of gastrointestinal malignancy but sporadic juvenile polyps do not. Cyclooxygenase-2 (COX-2) expression is increased in gastrointestinal tumorigenesis and familial adenomatous polyposis. Inhibition of COX-2 leads to regression of colorectal adenomas in familial adenomatous polyposis patients and inhibits gastrointestinal tumorigenesis. To investigate the role of COX-2 in juvenile polyps, we compared the expression of COX-2 in juvenile polyps from a well-defined group of juvenile polyposis patients and sporadic juvenile polyps.

METHODS

COX-2 expression was assessed in 24 genetically well-defined JPS patients and 26 patients with sporadic juvenile polyps using tissue microarray analysis. Two additional markers, Hu-antigen R, a stabilizer of messenger RNA, and CCAAT/enhancer-binding protein beta, a transcription factor, both associated with increased COX-2 expression, also were investigated.

RESULTS

Increased COX-2 expression in JPS patients was noted compared with patients with sporadic juvenile polyps (P < .001). Also, JPS patients with a BMPR1A germline defect had higher COX-2 expression than did JPS patients in whom no germline mutation was detected. High COX-2 levels correlated with increased cytoplasmic Hu-antigen R expression in JPS polyps (P = .022), but not in sporadic juvenile polyps.

CONCLUSIONS

Juvenile polyposis and sporadic juvenile polyps show distinctive expression profiles of COX-2 that may have clinical implications.

Expression of COX-2 in stomach carcinogenesis

BACKGROUND

Gastric cancer is a frequent cause of cancer in Brazil. The understanding of gastric carcinogenesis is not completely known but the progress of the molecular biology has provided that the initiation and progression of gastric cancer process is a consequence of a cumulative series of multiple gene alterations.

AIM

The aim of the study is to investigate the relationship among cytoplasmatic COX-1 and COX-2, Bcl-2 and nuclear P53 in chronic gastritis, metaplasia, and intestinal and gastric cancer.

PATIENTS AND METHODS

COX-1, COX-2, P53, and Bcl-2 were evaluated by immunohistochemistry in 34 gastric adenocarcinoma (GA) tissues obtained from gastric resection, 21 tissues of patients with chronic gastritis (CG), and 34 with intestinal metaplasia (IM) obtained from endoscopic biopsies.

RESULTS

COX-1 and COX-2 were expressed in more than 85% of the tissues. A correlation between COX-1 and COX-2 were observed (r = 0.66). P53 was positive in 29% CG, 20% of IM and in 59 % of GA. Bcl-2 was negative in all the CG, in 88% of IM, and in 85% of GA. P53 staining was expressed more frequently in gastric cancer when compared to CG (p = 0.05) or IM (p = 0.003). The expression of Bcl-2 was also higher in gastric cancer (p = 0.002) and in intestinal metaplasia (p = 0.04) when compared to CG. There were no difference between metaplasia and chronic gastritis for P53 or Bcl-2. The immunoreactivity of COX-2 in gastric cancer was higher in the intestinal type (58%) than in diffuse type. A higher expression of COX-2 was found in advanced gastric cancer (p = 0.019). P53 was also more frequent in node positive cancer (p = 0.04).

CONCLUSION

COX-2 is probably involved in gastric carcinogenesis, being an early alteration in cancer. Although we observed in this study a correlation between COX-2 and depth of cancer, this association as a prognostic marker is not well defined. P53 and Bcl-2 was expressed mainly in gastric cancer, being probably a latest alteration in gastric development.

MYC and gastric adenocarcinoma carcinogenesis

MYC is an oncogene involved in cell cycle regulation, cell growth arrest, cell adhesion, metabolism, ribosome biogenesis, protein synthesis, and mitochondrial function. It has been described as a key element of several carcinogenesis processes in humans. Many studies have shown an association between MYC deregulation and gastric cancer. MYC deregulation is also seen in gastric preneoplastic lesions and thus it may have a role in early gastric carcinogenesis. Several studies have suggested that amplification is the main mechanism of MYC deregulation in gastric cancer. In the present review, we focus on the deregulation of the MYC oncogene in gastric adenocarcinoma carcinogenesis, including its association with Helicobacter pylori (H pylori) and clinical applications.

Bile acid induces expression of COX-2 through the homeodomain transcription factor CDX1 and orphan nuclear receptor SHP in human gastric cancer cells

The caudal-related homeobox gene, CDX1, encodes for an intestinal-specific transcription factor and is involved in the induction of intestinal metaplasia (IM) of the stomach in gastric cancer. Gastric IM induced by bile reflux is a precancerous gastric adenocarcinomal lesion and has been associated with the induction of cyclooxygenase-2 (COX-2). In this study, we demonstrate the molecular mechanisms underlying the transcriptional regulation of COX-2 by bile acid in gastric cells. We noted that the ectopic expression of CDX1 enhanced COX-2 gene expression and that bile acid was associated with the induction of CDX1 expression. Furthermore, the induction of CDX1 by bile acid was mediated by the orphan nuclear receptor, small heterodimer partner (SHP). Finally, it was verified that the expression of COX-2, CDX1, SHP and CCAAT element-binding protein beta messenger RNA in human IM lesions were significantly higher than in lesions associated with gastritis. Collectively, these results reveal that bile acid induces an increase in the gene expression of COX-2 via the sequential transcriptional induction of SHP and CDX1 in precancerous lesions of human gastric cancer.

The COX-2 promoter polymorphism -765 G>C is associated with early-onset, conventional and stump gastric cancers

COX-2 overexpression is known to be an important mechanism in gastric carcinogenesis. Previously we have found that early-onset gastric cancer has a unique COX-2 low-expressing phenotype that differs significantly from that of the frequent overexpression seen in conventional gastric cancers. To investigate whether the COX-2 -765 G>C promoter polymorphism (known to lead to a reduction of COX-2 promoter activity in the colon) may explain this difference in expression, we carried out single-nucleotide polymorphism (SNP) analysis of 241 gastric cancers, including early-onset gastric cancer, conventional gastric cancers and gastric stump cancers, as well as in 100 control patients, using real-time PCR and sequence analysis, and correlated these findings with COX-2 expression using immunohistochemistry. We found that the C allele was present in 30% of early-onset gastric cancers, 24% of conventional gastric cancer, 23% of stump cancers, in contrast to 41% in the control group. There was a statistically significant difference in the presence of the C allele in patients with gastric cancer compared with the control group (P=0.007), with the C allele being associated with protection against gastric cancer. However, there was no significant difference between the early-onset, conventional and stump gastric cancer groups. Interestingly, there was no correlation between the presence of the C allele and a difference in COX-2 expression. In summary, we show that the COX-2 -765 G allele promoter polymorphism is significantly associated with gastric cancer when compared with the normal control group, but does not appear to be related directly to COX-2 expression pattern in gastric cancer. Although early-onset gastric cancers appear to have a unique COX-2 expression pattern when compared with conventional gastric cancer, the exact mechanism by which this occurs is yet to be elucidated.

Are trefoil factors oncogenic?

Trefoil factors (TFFs), in particular TFF1, are classical estrogen-regulated genes and have served as markers of estrogen gene regulation by various environmental estrogens. TFFs are also regulated by several other factors including growth hormone (hGH), insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF) and various oncogenic stimuli. TFFs are secreted proteins present in serum and possess the potential to act as growth factors promoting cell survival, anchorage-independent growth and motility. Recent compelling evidence has emerged from experimental and clinical studies to indicate a pivotal role of TFFs in oncogenic transformation, growth and metastatic extension of common human solid tumours. This review will summarize the current evidence for the involvement of TFFs in human cancer.

Association of endothelin-converting enzyme-1b C-338A polymorphism with gastric cancer risk: a case-control study

To investigate the association between endothelin-converting enzyme-1b (ECE-1b) C-338A polymorphism and gastric cancer risk, we conducted a hospital-based case-control study of 256 gastric cancer cases and 256 controls matched on age and gender. The genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism. We found that the genotype frequencies were significantly different (P=0.005) between cases and controls. Compared with the wild genotype CC, the variant genotypes (CA+AA) were associated with a 64% increased risk of gastric cancer [adjusted odds ratio (OR)=1.64, 95% confidence interval (CI) 1.15-2.33]. Further stratification analyses indicated that the increased risk was especially noteworthy in older subjects (age 58) (adjusted OR=1.91, 95% CI 1.18-3.09), women (adjusted OR=2.30, 95% CI 1.11-4.79) and non-smokers (adjusted OR=1.79, 95% CI 1.19-2.67). Our results suggest that the ECE-1b C-338A polymorphism may be associated with increased risk of gastric cancer.

Increased expression of CCAAT/enhancer-binding protein beta in proliferative inflammatory atrophy of the prostate: relation with the expression of COX-2, the androgen receptor, and presence of focal chronic inflammation

BACKGROUND

Proliferative inflammatory atrophy (PIA) in the prostate has been proposed to be a precursor to prostate cancer. CCAAT/enhancer-binding protein beta (C/EBPbeta) is an important transcription factor involved in cellular proliferation and differentiation. Activation of C/EBPbeta plays a crucial role during the initial stage of cyclo-oxygenase 2 (COX-2) induction by proinflammatory mediators. Overexpression of C/EBPbeta has been reported in several human tumors. Nevertheless, the C/EBPbeta expression and functions in human prostate tissue are basically unknown.

METHODS

C/EBPbeta immunohistochemical staining was performed on 45 benign prostate hyperplasia (BPH) samples. The expression of C/EBPbeta in PIA lesions and normal-appearing acini was analyzed. In addition, by using double-IHC staining, C/EBPbeta expression and the association with chronic inflammatory cell density, co-expression of COX-2 and androgen receptor (AR) were also investigated.

RESULTS

C/EBPbeta was occasionally observed in normal-appearing prostate acini (4.9% +/- 6.7%, Mean +/- SD) but was clearly overexpressed in PIA lesions (81.8% +/- 16.4%) (P < 0.0001). Atrophic glands with T-lymphocyte and macrophage inflammation expressed higher level of C/EBPbeta. Furthermore, C/EBPbeta correlated significantly with COX-2 expression. Downregulation of the AR was common in PIA and was also related to the C/EBPbeta overexpression.

CONCLUSIONS

The data demonstrated that chronic inflammation appeared to play roles in the induction of C/EBPbeta expression in prostate epithelium, which was in turn associated with increased COX-2 expression and AR downregulation. In combining with other molecular alteration in the epithelium of PIA, it is suggested that these cells might be a kind of intermediate cells and involved in the pathogenesis of prostate cancer.

C/EBPbeta is over-expressed in gastric carcinogenesis and is associated with COX-2 expression

The CCAAT/enhancer-binding protein beta (C/EBPbeta) transcription factor has been associated with several cancer models. In this study, the expression of C/EBPbeta was analysed in a series of 90 gastric carcinomas (GCs). We also assessed the effect of C/EBPbeta on COX-2 expression. In normal gastric mucosa, C/EBPbeta expression was restricted to cells in the proliferative zone. In intestinal metaplasia, dysplasia, and GC of the intestinal and atypical subtypes, C/EBPbeta was over-expressed (p < 0.0001, for the association with histological type). C/EBPbeta and Ki67, a marker of cell proliferation, were also co-expressed in primary GC. We also observed an overlap between C/EBPbeta and COX-2 expression in GC. Using GC cell lines we show that C/EBPbeta can regulate the expression of endogenous COX-2 and transactivate the promoter of the COX-2 gene, depending on its methylation status. These results suggest that C/EBPbeta may be a marker of neoplastic transformation and also play an active role in gastric tumourigenesis by regulating COX-2 expression.

A novel region of amplification at 11p12-13 in gastric cancer, revealed by representational difference analysis, is associated with overexpression of CD44v6, especially in early-onset gastric carcinomas

Diffuse-type gastric carcinomas (GCs) are often difficult to characterize because of contamination of tumor samples by surrounding normal tissue. As such, information regarding chromosomal aberrations in this subtype of GCs is limited. In this study, we used representational difference analysis to pinpoint genomic amplifications occurring in diffuse-type GCs. We found nine differential products from two novel regions of amplification in two tumors: one product mapped to 19p13.1 and eight mapped to a 1.8-Mb region in chromosomal segment 11p12-13. These amplifications were confirmed using Southern blot analysis and occurred in 3/16 and 6/15 diffuse-type GCs, respectively. CD44, a well characterized cellular adhesion molecule involved in several human malignancies, is encoded by a gene located within 200 kb of the 11p12-13 amplification fragments. We confirmed that overexpression of isoform CD44v6 was correlated with amplification at 11p12-13 in 11/12 diffuse-type GCs. Since diffuse-type GCs occur more frequently in early-onset gastric carcinomas (EOGCs, presented at 45 years of age or younger) than in "conventional" GCs, and the tumors carrying the original amplifications were EOGCs, we investigated overexpression of CD44v6 in 107 EOGCs and 88 conventional GCs using tissue microarrays. We found frequent CD44v6 overexpression in both tumor groups (76% and 57% respectively) and, interestingly, significantly more cases with overexpression of CD44v6 in EOGCs than in conventional GCs (P = 0.005), irrespective of histology. These findings provide further evidence for both the relevance of CD44 in GC and for distinct molecular characteristics of EOGCs when compared with those of GCs occurring at a later age.

Promoter hypermethylation and silencing of CHFR mitotic stress checkpoint gene in human gastric cancers

CHFR is a recently identified mitotic stress check-point gene. CHFR is ubiquitously expressed in normal human tissues, whereas loss of CHFR expression has been observed in human tumors. Silencing of CHFR has been associated with aberrant promoter methylation and histone deacetylation in several cancer types. In this study, we investigated epigenetic CHFR inactivation in human gastric cancers by examining CHFR expression and methylation status in gastric cancer cell lines with RT-PCR analysis, bisulfite PCR and sequencing. A series of primary gastric tumors were also analyzed for CHFR methylation. Eight of 12 (66.7%) gastric cancer cell lines and 19/43 (44.2%) primary gastric tumors showed CHFR methylation. In addition, CpG methylation status correlated well with CHFR expression in the human gastric cancer cell lines, in which treatment with 5-aza-dC resulted in de novo or enhanced expression of CHFR. Combination treatment of 5-aza-dC with trichostatin A showed a synergistic effect on CHFR expression in some cases. Our results indicate that aberrant promoter methylation of the CHFR gene was observed in a significant proportion of human gastric cancers and was responsible for the inactivation of the CHFR gene in gastric cancers.