Bcl-2 prevents doxorubicin-induced apoptosis of human liver cancer cells

We have isolated two stable human bcl-2 transfected cell lines, HCC-T-bcl and PLC-bcl, that were derived from the transfection of two human hepatocellular carcinoma cell lines (HCC-T and PLC/PRF/5, respectively) with a plasmid vector containing recombinant bcl-2 (pCAGGS-bcl).) Cell lines transfected with the plasmid alone (pCAGGS-neo) were also established as controls (HCC-T-neo and PLC-neo). HCC-T-neo and PLC-neo were sensitive to doxorubicin-induced apoptosis, as defined by morphological observation. Although HCC-T-neo expressed endogenous Bcl-2, the sensitivity of HCC-T-neo to doxorubicin-induced cytotoxicity was similar to that of PLC-neo, which does not express endogenous Bcl-2. In contrast, both HCC-T-bcl and PLC-bcl were more resistant to doxorubicin-induced cytotoxicity. Although these bcl-2 transfectants were resistant to the drug-induced apoptosis, Bcl-2 overexpression did not affect doxorubicin-induced growth suppression. These results suggest that the overexpression of Bcl-2 renders human HCC cells resistant to doxorubicin-induced cytotoxicity.