Combined in vitro anti-tumoral action of tamoxifen and retinoic acid derivatives in hepatoma cells.
Chemotherapy does not have a prominent role in the treatment of hepatoma. However, an acyclic retinoid prevented tumor recurrence post-hepatectomy, and tamoxifen (TAM) induced apoptosis in tumor cells. Combination therapy of these agents on proliferation and apoptosis of hepatoma cells has not been explored. HepG2, Hep1B, Hepa1-6 and MH1C1 hepatoma cells were incubated with TAM, 9-cis- and all-trans retinoic acid (CRA, ATRA, respectively) alone or in combination. Proliferation rate was assessed and apoptosis was analyzed by flow cytometry, immunostaining, caspase activity assays and the expression of apoptosis- and/or cell cycle-related molecules. CRA and TAM, but not ATRA monotherapy were moderately effective. Apoptosis was accompanied by upregulation of caspase 3 and 8 activity, and increased p27, bax, caspase 3 expression, while the levels of p21cip/waf and bcl-2 were unchanged or decreased. Combination therapy enhanced apoptosis from a maximum of 60% after monotherapy to more than 90% after 96 h in all cell types. Pro-apoptotic effects were paralleled by inhibition of proliferation. Combination of TAM and CRA, but not ATRA, have an additive to synergistic anti-proliferative and pro-apoptotic effect on HCC cells. This justifies trials for HCC using combinations of these biological response modifiers.
Herold
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C
Department of Medicine I, D-91054 Erlangen, Germany. christoph.herold@med1.imed.uni-erlangen.de
Ganslmayer
M
M
Ocker
M
M
Hermann
M
M
Hahn
E G
EG
Schuppan
D
D
D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000378:metabolism; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004273:DNA, Neoplasm / Q000032:analysis; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D009363:Neoplasm Proteins / Q000378:metabolism; D051381:Rats; D013629:Tamoxifen / Q000008:administration & dosage*; D014212:Tretinoin / Q000008:administration & dosage*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D013629:Tamoxifen; D014212:Tretinoin