Filamin-A, also called
actin binding protein 280 (ABP-280), cross-links the actin filaments into dynamic orthogonal network to serve as scaffolds in multiple signaling pathways. It has been reported that
filamin-A interacts with DNA damage response
proteins BRCA1 and BRCA2. Defects of
filamin-A impair the repair of
DNA double strand breaks (DSBs), resulting in sensitization of cells to ionizing radiation. In this study, we sought to test the hypothesis that
filamin-A can be used as a target for
cancer chemotherapy and as a
biomarker to predict
cancer response to therapeutic DNA damage. We found that reduction of
filamin-A sensitizes
cancer cells to
chemotherapy reagents bleomycin and
cisplatin, delays the repair of not only DSBs but also single strand breaks (SSBs) and interstrand crosslinks (ICLs), and increases
chromosome breaks after the
drug treatment. By treating a panel of human
melanoma cell lines with variable
filamin-A expression, we observed a correlation between expression level of
filamin-A protein and
drug IC(50). We further inhibited the expression of
filamin-A in
melanoma cells, and found that this confers an increased sensitivity to
bleomycin and
cisplatin treatment in a mouse xenograft
tumor model. These results suggest that
filamin-A plays a role in repair of a variety of DNA damage, that lack of
filamin-A is a prognostic marker for a better outcome after DNA damage based treatment, and
filamin-A can be inhibited to sensitize
filamin-A positive
cancer cells to therapeutic DNA damage. Thus
filamin-A can be used as a
biomarker and a target for DNA damage based
cancer therapy.