P53 and Rb tumor suppressor gene alterations in gastric cancer

Prognosis and survival study in patients with gastric adenocarcinoma and its relationship with pRb expression alteration: A retrospective IHC-based study

Background and Objective

Among cancers, gastric cancer has the fifth highest incidence worldwide and is the third most common mortality factor, which may have been due to inadequate knowledge of its molecular pathogenesis. The retinoblastoma gene (RB1), a tumor suppressor gene, may have a role in gastric cancer. This research aims to assess Rb expression as a prognostic marker to obtain more insight regarding gastric cancer.

Methods

This retrospective analytical study was done on 61 patients (45 males and 16 females) with gastric adenocarcinoma admitted from 2010 to 2012 in Shahid Sadoughi and Mortaz hospitals, Yazd, Iran. Demographic data, including age, gender, clinical signs and symptoms, and pathology reports, were retrieved from patients' hospital folders. Then, the altered Retinoblastoma gene expression was evaluated by immunohistochemistry studies. Acquired data were analyzed by SPSS software v.16. p < 0.05 was statistically considered meaningful.

Results

In this study, the ratio of men to women was higher (2.81:1), and the mean age of patients was 62.44 years. About 90.2% of patients died during the study. There was no meaningful relationship between the presence of pRb, the intensity of staining, the percentage of staining with patients' age, gender, tumor grading, and survival rate (p > 0.05). There was only a meaningful relationship between the grade of tumors and survival rate (p = 0.039).

Conclusion

Altered pRB expression is not common in gastric cancer and does not impact the survival and grading of tumors. Poorly differentiated tumors had an ominous outcome with the lowest survival time.

Loss of LLGL1 Expression Correlates with Diffuse Gastric Cancer and Distant Peritoneal Metastases

BACKGROUND

Loss of LLGL1 has been associated with loss of cellular adhesion and dissemination of cells from colorectal cancer and malignant melanoma. Regulation and relevance of LLGL1 were analyzed in gastric cancer patients with lymphatic and distant dissemination. Furthermore, LLGL1 expression was analyzed in relation to the cellular adhesion protein E-cadherin.

METHODS

LLGL1 and E-cadherin transcription levels were evaluated in 56 gastric cancer patients and five gastric cancer cell lines. IHC staining for LLGL1 was performed on 39 gastric cancer specimens. LLGL1 was stably transfected into LLGL1 negative gastric cancer cell line SNU16 (del(17) (p11.2)) for functional in vitro assays and a xenograft bioassay.

RESULTS

Gastric cancer specimens and cell lines displayed LLGL1 and E-cadherin expression levels with variable intensity. In gastric mucosa, LLGL1 exhibited weak cytoplasmic and strong cortical staining. Loss of LLGL1 expression occurred in 65% of gastric cancers and significantly correlated with loss of E-cadherin expression (P=0.00009). Loss of LLGL1 expression was associated with the diffuse type of gastric cancer (P=0.029) with peritoneal carcinomatosis (M1; P=0.006) and with female gender (P=0.017). Stable reexpression of LLGL1 in SNU16 cells significantly increased both plastic surface adhesion and extracellular matrix proteins laminin and fibronectin, but had no impact on in vitro proliferation, apoptosis, or invasion or on in vivo proliferation or differentiation in our xenograft bioassay.

CONCLUSION

LLGL1 is coexpressed with E-cadherin. Loss of expression of either protein is associated with diffuse gastric cancer and peritoneal metastases. LLGL1 does not impact on proliferation or epithelial-mesenchymal transition (EMT) rather increasing cellular adhesion.

NHE1 is upregulated in gastric cancer and regulates gastric cancer cell proliferation, migration and invasion

Na+/H+ exchanger isoform 1 (NHE1) is known to play a key role in regulating intracellular pH and osmotic homeostasis and is involved in the development and progression of several types of cancer. However, the function and specific mechanism of NHE1 in gastric cancer (GC) are not clearly understood. In the present study, we report that NHE1 is overexpressed in tissues and cell lines from GC patients, and knockdown or inhibition of NHE1 suppressed GC cell proliferation via regulation of G1/S and G2/M cell cycle phase transitions, concomitant with a marked decrease in positive cell cycle regulators, including cyclin D1 and cyclin B1. Likewise, NHE1 was required for GC cell migration and invasion through the regulation of epithelial-mesenchymal transition (EMT) proteins, and NHE1 inhibition resulted in an acidic intracellular environment, providing possible mechanisms underlying NHE1-mediated GC progression both in vitro and in vivo. These data highlight the important role of NHE1 in GC progression and suggest that NHE1 may be a useful target for GC therapy.

A Multiple Interaction Analysis Reveals ADRB3 as a Potential Candidate for Gallbladder Cancer Predisposition via a Complex Interaction with Other Candidate Gene Variations

Gallbladder cancer is the most common and a highly aggressive biliary tract malignancy with a dismal outcome. The pathogenesis of the disease is multifactorial, comprising the combined effect of multiple genetic variations of mild consequence along with numerous dietary and environmental risk factors. Previously, we demonstrated the association of several candidate gene variations with GBC risk. In this study, we aimed to identify the combination of gene variants and their possible interactions contributing towards genetic susceptibility of GBC. Here, we performed Multifactor-Dimensionality Reduction (MDR) and Classification and Regression Tree Analysis (CRT) to investigate the gene–gene interactions and the combined effect of 14 SNPs in nine genes (DR4 (rs20576, rs6557634); FAS (rs2234767); FASL (rs763110); DCC (rs2229080, rs4078288, rs7504990, rs714); PSCA (rs2294008, rs2978974); ADRA2A (rs1801253); ADRB1 (rs1800544); ADRB3 (rs4994); CYP17 (rs2486758)) involved in various signaling pathways. Genotyping was accomplished by PCR-RFLP or Taqman allelic discrimination assays. SPSS software version 16.0 and MDR software version 2.0 were used for all the statistical analysis. Single locus investigation demonstrated significant association of DR4 (rs20576, rs6557634), DCC (rs714, rs2229080, rs4078288) and ADRB3 (rs4994) polymorphisms with GBC risk. MDR analysis revealed ADRB3 (rs4994) to be crucial candidate in GBC susceptibility that may act either alone (p < 0.0001, CVC = 10/10) or in combination with DCC (rs714 and rs2229080, p < 0.0001, CVC = 9/10). Our CRT results are in agreement with the above findings. Further, in-silico results of studied SNPs advocated their role in splicing, transcriptional and/or protein coding regulation. Overall, our result suggested complex interactions amongst the studied SNPs and ADRB3 rs4994 as candidate influencing GBC susceptibility.

Role of genetic variants of deleted in colorectal carcinoma (DCC) polymorphisms and esophageal and gastric cancers risk in Kashmir Valley and meta-analysis

Genetic alterations in the deleted in colorectal carcinoma (DCC) gene have been a priori reported to associate with metastasis in variety of human cancers. We investigated the association between potentially functional SNPs in DCC and susceptibility to esophageal (EC) and gastric (GC) cancers in Kashmir Valley. We genotyped two SNPs DCC rs714 (A>G) and DCC rs2229080 (C>G) of DCC in 135 EC patients, 108 GC patients, and 195 controls matched by age and sex in Kashmir Valley by polymerase chain reaction-RFLP method. Risk for developing EC and GC was estimated by binary logistic regression by using SPSS. We also performed a meta-analysis on DCC rs714 (A>G) and evaluated the association between the DCC rs714 (A>G) polymorphisms and cancer risk. A significant difference in DCC rs714 (A>G) genotype distribution between EC and GC cases and corresponding control groups was observed (odds ratio (OR) = 1.92; P = 0.03; P-trend = 0.04; false discovery rate (FDR) Pcorr = 0.03: OR = 2.15; P = 0.02; P-trend = 0.01; FDR Pcorr = 0.03). But no such association was observed in DCC rs2229080 (C>G). Further, DCC rs714 (A>G) AA genotype showed significantly increased risk for both gastric squamous cell carcinoma (OR = 5.63; P = 0.02; FDR Pcorr = 0.01) and gastric adenocarcinoma (OR = 2.15; P = 0.02; FDR Pcorr = 0.01). Smoking and salted tea are independently associated with both EC and GC, but gene-environment interaction did not further modulate the risk. Meta-analysis also suggested both independent and overall association of DCC rs714 (A>G) polymorphism with cancer (P = 0.000). In conclusion, genetic variations in DCC rs714 (A>G) modulate risk of EC and GC in high-risk Kashmir population.

A possible role of IL-1RN gene polymorphism in the outcome of gastrointestinal diseases associated with H. pylori infection

Objective

To verify whether the variable number of tandem repeat (VNTR) polymorphism in the IL-1RN gene that encodes the interleukin (IL)-1 receptor antagonist (IL-1Ra) plays a role in the outcome of gastrointestinal diseases associated with Helicobacter pylori (H. pylori) infection.

Methods

Patients with normal endoscopy (n = 71), inflammation of the upper gastrointestinal tract only (n = 196), gastric ulcer (n = 28), duodenal ulcer (n = 76), and gastric cancer (n = 19) were studied. H. pylori infection was diagnosed by the urease test, histological examination, and polymerase chain reaction. The IL-1 receptor antagonist gene (IL-1RN intron 2 VNTR) was analyzed by polymerase chain reaction. Gastritis was scored according to the updated Sydney system of classification.

Results

H. pylori infection was an independent risk factor for mild (odds ratio [OR] = 5.53 [95% confidence interval [CI] = 2.63–11.64; P < 0.05]), moderate (OR = 83.93 [95% CI = 29.7–237.18; P < 0.05]) and marked (OR = 47.47 [95% CI = 5.39–418.05; P < 0.05]) gastritis. The carriage of IL-1RN*2/*2 had a significant protective effect of H. pylori infection (OR = 0.31 [95% CI = 0.17–0.57; P < 0.05]). H. pylori infection was identified as an independent risk of inflammation, duodenal ulcer, and gastric ulcer. The carriage of IL-1RN*2/*2 was an independent risk factor for gastric cancer (OR = 5.81 [95% CI = 1.06–31.98; P < 0.05]); nonetheless, the carriage of allele 2 (IL-1RN*2/*2 plus IL-1RN*L/*2) had an independent protective effect on duodenal ulcer (OR = 0.45 [95% CI = 0.22–0.91; P < 0.05]).

Conclusions

Allele 2 of the VNTR IL-1RN polymorphism had a protective effect against duodenal ulcer and H. pylori infection; however, it increased the risk of gastric cancer.

DCC (deleted in colorectal carcinoma) gene variants confer increased susceptibility to gallbladder cancer (Ref. No.: Gene-D-12-01446)

BACKGROUND AND AIM

GBC is a lethal and multifaceted disease. Deleted in colorectal carcinoma (DCC) is a well known tumor suppressor gene. Recently a small genome-wide association study (GWAS) identified DCC to be significantly associated with gallbladder cancer (GBC) susceptibility in a Japanese population sample. However, the study sample size was small and lacked independent replication. Therefore, the present study was carried out to replicate the association of two GWAS identified DCC SNPs (A>Grs4078288, C>Trs7504990) and two other SNPs (C>Grs2229080 and A>Grs714) previously associated with various cancers.

METHODOLOGY

The study was accomplished in 406 GBC cases and 260 healthy control samples from North India. Genotyping was carried out by PCR-RFLP and Taqman genotyping assays. Statistical analysis was performed by using SPSS ver16 and functional prediction of these variants was carried out using Bioinformatics tools (FAST-SNP, F-SNP).

RESULT

We did not observe association with GWAS-identified SNPs of DCC but other SNPs showed significant association. In addition, a DCC haplotype Grs2229080-Ars4078288-Crs7504990-Ars714 conferred high risk of GBC in India. The haplotype associated risk was independent of gallstone, sex or tobacco usages which are well-known modifiers of GBC risk. Further analysis suggested DCC A>Grs714 as a major risk conferring SNP in the Indian population.

CONCLUSION

This study re-affirms the role of plausible tumor suppressor DCC variants, in gallbladder carcinogenesis and the risk haplotype may be explored as a useful marker for GBC susceptibility.

Coexpression of receptor-tyrosine-kinases in gastric adenocarcinoma-a rationale for a molecular targeting strategy?

AIM: To define the (co-)expression pattern of target receptor-tyrosine-kinases (RTK) in human gastric adenocarcinoma.

METHODS: The (co-)expression pattern of VEGFR1-3, PDGFRα/β and EGFR1 was analyzed by RT-PCR in 51 human gastric adenocarcinomas. In addition, IHC staining was applied for confirmation of expression and analysis of RTK localisation.

RESULTS: The majority of samples revealed a VEGFR1 (98%), VEGFR2 (80%), VEGFR3 (67%), PDGFRα (82%) and PDGFRβ (82%) expression, whereas only 62% exhibited an EGFR1 expression. 78% of cancers expressed at least four out of six RTKs. While VEGFR1-3 and PDGFRα revealed a predominantly cytoplasmatic staining in tumor cells, accompanied by an additional nuclear staining for VEGFR3, EGFR1 was almost exclusively detected on the membrane of tumor cells. PDGFRβ was restricted to stromal pericytes, which also depicted a PDGFRα expression.

CONCLUSION: Our results reveal a high rate of receptor-tyrosine-kinases coexpression in gastric adenocarcinoma and might therefore encourage an application of multiple-target RTK-inhibitors within a combination therapy.

No correlation of babA2 with vacA and cagA genotypes of Helicobacter pylori and grading of gastritis from peptic ulcer disease patients in Brazil

BACKGROUND

The babA2 gene, which encodes a blood-group antigen-binding adhesin that mediates attachment of Helicobacter pylori to human Lewis(b) antigens on gastric epithelial cells, has been associated with a higher risk of peptic ulcer and gastric cancer. The purpose of this study was to ascertain the frequency of babA2 genotype in H. pylori strains of patients with peptic ulcer and to correlate with other virulence factors.

MATERIALS AND METHODS

vacA, cagA, and babA2 genotypes of H. pylori were determined by using polymerase chain reaction (PCR). DNA was extracted from positive urease test gastric samples of 150 patients with peptic ulcer. Antrum and corpus biopsies were taken for histologic examination according to the updated Sydney system classification.

RESULTS

babA2 genotype was present in 104 (69.3%) and cagA in 113 (75.3%) gastric samples. No significant correlation was observed between babA2 and vacAs1 genotype or between babA2 and cagA status. The correlation of vacAs1 genotype with positive cagA was statistically significant ( p < .001). The babA2-positive strain was more frequently found from the gastric samples of men, than of women (p = .01). Strains harboring cagA, vacAs1, and babA2 genotypes had no association to the grading of gastritis, presence of glandular atrophy, or intestinal metaplasia. The simultaneous presence of cagA, vacAs1, and babA2 was found in 32.6% of the H. pylori strains.

CONCLUSIONS

babA2 genotype is frequently found in H. pylori strains from peptic ulcer disease in Brazil, although it has no significant correlation to the worsening of the gastritis and to other virulence markers such as vacAs1 and cagA.

Heterozygosity loss of fragile histidine triad gene in gastric cancer and precancerous lesions

AIM: To detect the loss of heterozygosity (LOH) of fragile histidine triad (FHIT) gene in gastric cancer and precancerous lesions (dysplasia and intestinal metaplasia), and to analyze its role in the carcinogenesis of gastric cancer.

METHODS: The LOH at microsatellites loci D3S1234 and D3S1300 of FHIT gene were measured in samples of gastric cancer (n = 42), dysplasia (n = 44), intestinal metaplasia (n = 51) and their corresponding normal tissues by (polymerase chain reaction) PCR.

RESULTS: The rates of LOH at D3S1234 locus were 32.4%(11/34), 28.6%(10/35) and 10%(4/40) in gastric cancer, dysplasia and intestinal metaplasia respectively, and the ones at D3S1300 locus were 33.3%(12/36) , 32.4%(11/34) and 7.7% (3/39) respectively. The LOH rates at D3S1234 and D3S1300 loci in gastric cancer and atypical hyperplasia were higher than that of intestinal metaplasia (P<0.05, P<0.01 for D3S1234 and D3S1300 respectively). No significant difference of LOH rate was found between gastric cancer and dysplasia.

CONCLUSION: The loss of heterozygosity of FHIT gene may be an early event in the tumorigenesis of gastric cancer.