The suppression of drug-induced apoptosis by activation of v-ABL protein tyrosine kinase.

Cells with a temperature-sensitive mutant of the v-abl oncoprotein (IC.DP) were treated with the anticancer drugs melphalan or hydroxyurea. At the restrictive temperature for v-ABL protein tyrosine kinase activity, drug-treated IC.DP cells died by apoptosis. In contrast, apoptotic cell death induced by either drug was suppressed when v-ABL was active. However, melphalan-induced accumulation of cells in the S and G2-M phases of the cell cycle was unaffected by v-ABL activation. Moreover, the continuous presence of v-ABL activity was necessary to suppress apoptosis. This suggested that melphalan had interacted with DNA and that v-ABL activity prevented the coupling of drug-induced damage to the apoptotic pathway. IC.DP cells exhibited similar levels and subcellular localization of the BCL-2 protein irrespective of v-ABL activation status, thus v-ABL-mediated cell survival appeared to be independent of BCL-2.