Clinical Significance of Frequently Down-Regulated Phosphatidylethanolamine-Binding Protein-1 in Gallbladder Cancer.

BACKGROUND: Promoter hypermethylation of tumor suppressor genes has been demonstrated to be one of the major mechanisms of their epigenetic regulation in various reports. We have studied the promoter methylation status of PEBP1 and evaluated its correlation with gallbladder carcinogenesis. AIMS: PEBP1, an endogenous inhibitor of Raf/MEK/ERK signaling pathway, is a tumor suppressor gene. We aimed to study the expression profile of PEBP1 and understand the mechanism and significance of its deregulation in gallbladder cancer. METHODS: PEBP1 expression analysis and its promoter methylation status were investigated in 77 gallbladder carcinoma (GBC) and tissue biopsies from 28 patients of gallstone disease by RT-PCR and MS-PCR, respectively. RESULTS: Our results of the mRNA expression profiling demonstrate that PEBP1 is down-regulated in 62.3% (48/77), while 31.2% (24/77) of the gallbladder cancer biopsies show no significant change and 6.5% (5/77) show up-regulated expression compared to tissue samples of gallstone diseases. In GBC, 48.1% (N = 37) GBC biopsy samples exhibited significantly heterozygous promoter hypermethylation compared to tissue samples from gallstone diseases which show promoter hypermethylation in 3 (10.7%) samples only. In gallbladder cancer, the PEBP1 methylation is significantly associated with lymph node metastasis and shorter period of survival. CONCLUSION: PEBP1 is frequently down-regulated and hypermethylated in gallbladder cancer and its promoter hypermethylation is a frequent and early inactivating mechanism in GBC.

Frequent promoter hypermethylation and down regulation of BNIP3: An early event during gallbladder cancer progression.

BACKGROUND: Epigenetic alterations have been reported as one of the risk factors of gallbladder cancer. Promoter hypermethylation is associated with high incidence and poor prognosis of GBC. Bcl-2/adenovirus E1B 19 kDa interacting protein 3 is a pro-apoptotic protein member of Bcl-2 family. AIMS: Present study was aimed to investigate expression profile and promoter methylation status of BNIP3 in GBC and its correlation with clinico-pathological parameters. METHODS: The expression analysis and methylation status of BNIP3 was performed by semi-quantitative reverse transcription polymerase chain reaction and Methylation-specific polymerase chain reaction respectively in 84 GBC patients and 29 gallstone tissues (used as normal controls). RESULTS: We demonstrate down regulation of BNIP3 in 56% of the GBC samples. BNIP3 promoter is also frequently hypermethylated (69%) in GBC samples. Interestingly, we found that 69% (40/58) of the BNIP3 promoter hypermethylated samples had also reduced expression of BNIP3. Our data demonstrate significant correlation of the mRNA expression and promoter hypermethylation with late stage and nodal metastasis. Hypermethylation of BNIP3 promoter is associated with low overall survival period. CONCLUSION: Our results suggest that promoter hypermethylation is an early event and can be a frequent mechanism for downregulation of BNIP3 in GBC.

Frequent Downregulation and Promoter Hypermethylation of DLC1: Relationship with Clinical Outcome in Gallbladder Cancer.

INTRODUCTION: Down regulation of DLC1 is associated with poor prognosis in many cancers, however, its role in gallbladder cancer (GBC) is still unclear. In present study, we investigated the expression profile and promoter methylation status of DLC1. METHODS: Expression profiles of DLC1 in 55 GBC and their paired adjacent control samples were analyzed through real time RT-PCR and immunohistochemistry. The mRNA data was correlated with clinico-pathological parameters. Promoter hypermethylation was analyzed through MSP. RESULTS: DLC1 shows downregulation in 76.4%, upregulation in 10.9% whereas no change in 12.7% of GBC samples. Its underexpression shows significant correlation with tumor grade and nodal spread. IHC shows cytoplasmic expression of DLC1 in normal as well as tumor samples. IHC result was concordant to mRNA result. Samples having downregulated DLC1 expression show heterozygous methylation in 83.3% of samples and homozygous methylation in 9.5% of samples whereas 7% of samples have no methylation. Kaplan-Meier analysis shows patient with decreased mRNA of DLC1 have significant low mean survival compared to patients with higher mRNA expression of DLC1. CONCLUSION: Our findings suggested that dysregulated expression of DLC1 and its hypermethylation may be one of the events playing roles in tumorigenesis of GBC and may serve as a potential target for development of future GBC gene therapy.