Microarray based gene expression profiling of advanced gall bladder cancer.

Abstract

Gall bladder cancer (GBC) is an aggressive cancer with specific predilection like female gender and specific geographical areas, however the molecular mechanisms and factors contributing to the clinical or biological behavior are not understood. The aim of this study was to perform a comprehensive analysis of differentially expressed genes in advanced GBC and chronic cholecystitis(CC) cases. Microarray was planned on fresh specimens of advanced GBC and CC cases using single color cRNA based microarray technique (8X60K format; Agilent Technologies, USA). Twelve advanced GBC and four CC patients were included in the study. Of the total of 1307differentially expressed genes, 535genes were significantly upregulated, while 772genes were significantly downregulated in advanced GBC vs CC samples. Differentially expressed genes were associated with biological processes (55.03%), cellular components (31.48%), and molecular functions (13.49%) respectively. The important pathways or key processes affected were cell cycle, DNA replication, oxidative stress, gastric cancer pathway. Using in silico analysis tools, three differentially expressed genes i.e. TPX2, Cdc45and MCM4were selected (for their significant role in DNA replication and microtubule function) and were further validated in 20advanced GBC cohort by immunohistochemistry. Significant positive association of Cdc45and MCM4proteins was found in advanced GBC cases (p=0.043), suggesting the probable oncogenic role of Cdc45and MCM4proteins in advanced GBC. Our data demonstrate the potential regulation of Cdc45-MCM4axis in advanced GBC tumors. Additionally, our study also revealed a range of differentially expressed genes (e.g. TPX2, AKURA etc.) between GBC and CC, and further validation of these genes might provide a potential diagnostic or therapeutic target in future.