Microarray determination of Bcl-2 family protein inhibition sensitivity in breast cancer cells

This study tests the hypothesis that reverse transcription polymerase chain reaction (RT-PCR) microarrays can be used to predict the relative sensitivity to induction of apoptosis in breast cancer cells exposed to inhibitors of antiapoptotic Bcl-2 family proteins. Four cell lines, MDA-MB-231 (MDA-231) and MDA-MB-468 (MDA-468), BT-20 and T47-D were screened for relative expression of Bcl-2 family members A1, Mcl-1, Bcl-2, Bcl-xL and Bcl-w mRNA by RT-PCR microarrays and Western analysis. The four cell lines were treated with 1 mmol/L obatoclax (GX15-070) and/or 2 Gy radiation (RT) and monitored for apoptosis after 48 h. Cell lines showing the highest total fold-increase of Bcl-2 family member mRNA, MDA-231 and MDA-468, also showed the highest levels of apoptosis induction (approximately 70% with obatoclax alone and 82% with obatoclax plus RT). Cell lines with little or no increase in Bcl-2 family mRNA (BT-20 and T47-D) showed less apoptosis (30% following treatment with obatoclax and 42% with obatoclax plus RT). RT-PCR arrays can predict the relative apoptosis response of breast cancer cells to the pan Bcl-2 inhibitor obatoclax alone or when combined with radiation.