BCL-2 EXPRESSION CORRELATES WITH APOPTOSIS INDUCTION BUT NOT LOSS OF CLONOGENIC SURVIVAL IN SMALL-CELL LUNG-CANCER CELL-LINES TREATED WITH ETOPOSIDE

The influence of bcl-2 oncogene expression on etoposide-induced apopto sis and clonogenic survival was investigated in five small cell lung c ancer (SCLC) cell lines, three of which were bcl-2-expressing and two of which were non-bcl-2-expressing, The bcl-2-expressing lines display ed a lower apoptosis propensity than the non-bcl-2-expressing lines. W hen bcl-2-expressing cells were incubated in cystine/methionine-free ( CMF) medium, etoposide-induced apoptosis was restored to levels compar able to those seen in non-bcl-2-expressing lines. However, the endpoin t of clonogenic survival after drug treatment did not display any cons istent pattern that correlated with bcl-2 status, In addition, treatme nt of the two bcl-2-expressing cell lines with etoposide in CMF medium did not modify their clonogenic survival curves compared to treatment in regular medium. These results are consistent with the idea that bc l-2 expression modulates etoposide-induced apoptosis but not clonogeni c survival. [(C) 1998 Lippincott Williams & Wilkins.].