Bcl-2 is overexpressed and alters the threshold for apoptosis in a cholangiocarcinoma cell line

Hepatology. 1997 Oct;26(4):884-90. doi: 10.1002/hep.510260413.


Cholangiocarcinoma is a malignant neoplasm originating from cholangiocytes. The mechanisms responsible for oncogenesis of cholangiocytes are unknown. Resistance to apoptosis, especially by altered expression of B-cell lymphoma/leukemia 2 (Bcl-2) family members, has been implicated as a mechanism contributing to malignant transformation. Thus, our aim was to test the hypothesis that altered expression of Bcl-2 family members by cholangiocarcinoma cells renders them resistant to apoptosis. We compared the apoptotic threshold and expression of the Bcl-2 protein family members, Bcl-2, Bcl-XL, and Bax, in two human cell lines: 1) nonmalignant human cholangiocytes immortalized by transfection with the simian virus 40 (SV 40) large T antigen; and 2) a malignant human cholangiocarcinoma cell line. Apoptosis was induced pharmacologically using beauvericin. Bcl-2, Bcl-x long, and Bax protein expression were evaluated by immunoblot analysis, and Bcl-2 expression was modulated using antisense technology. The cholangiocyte and malignant/nonmaligant phenotype of both cell lines was verified using both in vitro and in vivo approaches. Beauvericin induced apoptosis of nonmalignant cholangiocytes in a concentration- (0 to 25 micromol/L) and time- (0 to 6 hours) dependent manner. In contrast, malignant cholangiocytes were resistant to apoptosis. Although expression of Bcl-x long and Bax protein were similiar in the two cell lines, Bcl-2 protein expression was 15-fold greater in malignant than in nonmalignant cholangiocytes. An 18 mer bcl-2 antisense oligonucleotide reduced expression of Bcl-2 protein by 50% and increased the rate of beauvericin-induced apoptosis more than threefold in the malignant cells. Our results support the hypothesis that resistance to apoptosis by overexpression of Bcl-2 may be a feature of cholangiocarcinoma.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Apoptosis*
  • Bile Duct Neoplasms / chemistry
  • Bile Duct Neoplasms / pathology*
  • Bile Ducts, Intrahepatic*
  • Cholangiocarcinoma / chemistry
  • Cholangiocarcinoma / pathology*
  • Depsipeptides*
  • Humans
  • Oligonucleotides, Antisense / pharmacology
  • Peptides*
  • Proto-Oncogene Proteins c-bcl-2 / analysis*
  • Tumor Cells, Cultured


  • Anti-Bacterial Agents
  • Depsipeptides
  • Oligonucleotides, Antisense
  • Peptides
  • Proto-Oncogene Proteins c-bcl-2
  • beauvericin