Z Gastroenterol 2010; 48 - P2_41
DOI: 10.1055/s-0029-1246420

Exploring the diversity of ways to overcome TRAIL resistance in HCC: contribution of survival signaling, chemotherapeutical drugs and antiapoptotic BCL-2 proteins

BC Köhler 1, T Urbanik 1, B Vick 2, RJ Boger 1, S Heeger 3, PR Galle 1, M Schuchmann 1, H Schulze-Bergkamen 4
  • 1I. Medizinische Klinik, Mainz
  • 2I. Medizinische Klinik, Universität Mainz, Mainz
  • 3Merck KGaA, Darmstadt
  • 4Nationales Centrum für Tumorerkrankungen, Heidelberg

Aim: In this study we analysed ways to overcome resistance of hepatocellular carcinoma (HCC) cells towards apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). In particular, the effect of treatment with recombinant TRAIL or agonistic TRAIL antibodies in combination with chemotherapeutic drugs, specific kinase inhibitors as well as the commitment of antiapoptotic BCL-2 proteins was investigated.

Methods: Surface expression of TRAIL receptors (TRAIL-R1–4) and expression levels of the antiapoptotic BCL-2 proteins MCL-1 and BCL-xL were analysed by flow cytometry and Western blot, respectively. Knock-down of MCL-1 and BCL-xL were performed by transfecting specific siRNAs. HCC cells were treated with recombinant TRAIL, agonistic TRAIL antibodies, kinase inhibitors and the chemotherapeutic drugs 5-Fluorouracil (5-FU) or doxorubicin (doxo). Apoptosis induction and cell viability were analyzed via flow cytometry and MTT assay.

Results: TRAIL-R1 and -R2 were profoundly expressed on the HCC cell lines Huh7 and Hep-G2. Treatment of Huh7 and Hep-G2 with TRAIL and agonistic antibodies only induced minor apoptosis rates. Apoptosis resistance towards TRAIL could be considerably reduced by adding the chemotherapeutical drugs 5-FU and doxo as well as the kinase inhibitors LY294002 (inhibition of PI3 kinase), AG1478 (EGFR kinase), PD98059 (MEK1), rapamycin (mTOR) and the multi-kinase inhibitor sorafenib. Furthermore, knock-down of MCL-1 and BCL-xL by RNA interference significantly increased TRAIL-induced apoptosis of HCC cells revealing a major role of both antiapoptotic BCL-2 proteins in TRAIL resistance.

Conclusion: Our data indicate that there are at least three promising ways to overcome TRAIL resistance in HCC: 1st) combining TRAIL with chemotherapeutical drugs, 2nd) blockage of survival pathways via specific kinase inhibition and 3rd) targeting of antiapoptotic BCL-2 proteins.

5-FU - BCL-xl - Doxorubicin - EGFR kinase - JNK - MCL-1 - MEK - PI3K - Sorafenib - TRAIL - apoptosis - hepatocellular carcinoma