Pentoxifylline increased apoptotic effects of tamoxifen on human breast cancer cells in vitro

Aims: Several anticancer drugs are being currently used in the treatment of breast cancer; however, there is a need to develop newer therapeutic regimens that owing to higher cytotoxicity and lower resistance. This study was aimed to investigate the effect of pentoxifylline (PTX) in combination tamoxifen (TAM) on viability and apoptosis of breast cancer cell lines in vitro. Methods: Two human breast cancer cell lines (MCF-7 and MDA-MB-231) were treated with TAM (2 μM) and different doses of PTX (2, 4, 8, or 16 mM) in combination or alone for 24 or 48 h. Cell viability was evaluated by MTT assay, and effect of these drugs on apoptosis was tested by acridine orange/ethidium bromide staining. Results: In 48 h treatment, cell viability of both MCF-7 and MDA-MB-231 cells was reduced in all treated groups (P < 0.05). In both cell lines, apoptotic index was significantly increased in combined treatment of 2 μM TAM and 16 mM PTX in comparison with each drug alone (P < 0.001). Conclusion: PTX induced synergistic effect with TAM on cell growth inhibition of breast cancer cells and could be a candidate drug for breast cancer treatment.