Promoter methylation profile in preneoplastic and neoplastic gallbladder lesions

Abstract

Gallbladder carcinoma (GBC) is a highly malignant neoplasm and represents the leading cause of cancer death in Chilean women. In order to determine the potential role of promoter methylation in gallbladder carcinogenesis, we investigated the frequency of this epigenetic mechanism by methylation-specific polymerase chain reaction (MSP) in 35 chronic cholecystitis (CC, separated according to the presence or absence of metaplasia), 19 early cancers (mucosa or muscularis propia invasion) and 48 advanced carcinomas with invasion of the gallbladder subserosa (25 cases) and serosa (23 cases). We examined 14 genes and observed an increase of multigenic methylation during tumoral progression which was not significantly associated with the patient's age. Four genes (DAPK1, DLC1, TIMP3, and RARbeta2) displayed a progressive increase in their methylation status from CC without metaplasia to advanced carcinoma invading the serosa layer (P <or= 0.05). The survival analysis indicated that a methylated condition of DLC1 gene is significantly associated with poor prognosis (P = 0.04), whereas a methylated state of MGMT gene correlated with better patient survival (P = 0.006). Our findings indicate that aberrant hypermethylation of promoter regions is an early, progressive and cumulative event in gallbladder carcinogenesis. Furthermore, the methylation levels seems to accumulate in the progression of CC without metaplasia to CC with metaplasia, a fact that could provide new evidence to consider this morphological adaptation of GB mucosa as a premalignant lesion. Finally, the methylation status of some individual genes could be useful biomarkers with potential clinical application in diagnosis or prognosis of GBC if they are validated in a greater number of clinical samples.

Epigenetic Changes in Carcinogenesis of Gallbladder

“…Yet another study from Chile [62], investigated methylation profile of 14 genes in 35 chronic cholecystitis (separated according to the presence or absence of metaplasia), 19 early GBC (mucosa or muscularis propia invasion) and 48 advanced GBC with invasion of the gallbladder subserosa (25 cases) and serosa (23 cases). A progressive significant (p < or = 0.05) increase in their methylation status from chronic cholecystitis without metaplasia to advanced GBC was seen in four genes (DAPK1, DLC1, TIMP3, and RARbeta2).…”

“…Furthermore, the methylation levels seems to accumulate in the progression of chronic cholecystitis without metaplasia to chronic cholecystitis with metaplasia, a fact that could provide new evidence to consider this morphological adaptation of gallbladder mucosa as a premalignant lesion. Finally, the methylation status of some individual genes could be useful biomarkers with potential clinical application in diagnosis or prognosis of GBC if they are validated in a greater number of clinical samples [62].…”

Histone deacetylase inhibitor (SAHA) and repression of EZH2 synergistically inhibit proliferation of gallbladder carcinoma

“…INK4a and E-cadherin in gallbladder carcinoma, (22,23) however, there have been few studies addressing alteration of epigenetic chromatin modification by PcG and HDACs in gallbladder carcinoma. (24,25) In this study using human gallbladders and cultures of gallbladder epithelial cells and the gallbladder carcinoma cell line, we assessed the expression pattern of EZH2 and class I HDACs (HDAC 1 and 2).…”

“…HDAC inhibitors induce different phenotypes in various transformed cells, including growth arrest, activation of extrinsic and ⁄ or intrinsic apoptotic pathways, autophagic cell death, mitotic cell death, and senescence. (19) In comparison, normal cells are relatively more resistant to HDAC inhibitorinduced cell death; (20,21) however, the mechanism underlying this difference is not well understood.Among HDAC inhibitors, SAHA is one of the most advanced in clinical fields as an anticancer agent, which interacts directly with the catalytic site of HDAC-like protein and inhibits its enzymatic activity.(18) SAHA inhibits all 11 members of the class I and II HDAC family, and causes specific modifications in the pattern of acetylation and methylation of lysines in histones H3 and H4 associated with the proximal promoter of the p21 gene.(18) Although considerable progress has been made in elucidating the role of HDACs and the effects of HDAC inhibitors, these areas are still in the early stages of discovery.Several previous studies reported abnormal promoter methylation of important genes including p16INK4a and E-cadherin in gallbladder carcinoma, (22,23) however, there have been few …”

Using epigenomic studies in monozygotic twins to improve our understanding of cancer

“…These changes in the transcriptome include processes such as activation of oncogenes and deactivation of tumor suppressor genes [2]. Epigenetic changes, such as DNA methylation, can be seen in early neoplastic and even in precancerous tissues [35,36]. For example, a key early tumor adaptation to frequently encountered hypoxic conditions is accompanied by epigenomic changes [37,38].…”