Combination of intensity modulated radiotherapy followed treatment with p38 MAPK activation inhibitor inhibits the proliferation of MCF-7 breast cancer cells

The present study was aimed to investigate the effect of intensity modulated radiotherapy (IMRT) followed by treatment with inhibitor for p38 MAPK, SB203580 on the rate of proliferation in drug resistant MCF-7 breast cancer cells. Interestingly, the results from immuno histochemistry and western blot assays revealed higher level of distribution of activated p38 MAPK in the drug resistant breast cancer tissues compared to the primary tissues. Treatment of the drug resistant MCF-7 cells with SB203580 led to a significant decrease in the phosphorylation of p38 MAPK. Exposure to IMRT caused a significant decrease in the rate of proliferation in drug resistant MCF-7breast cancer cells (P < 0.05). MCF-7 cells were subjected to IMRT for 45 min followed by treatment with SB203580 for 12 h. The results from MTT assay revealed inhibition in the rate of proliferation of MCF-7 cells more efficiently compared to the IMRT or SB203580 when used separately (P < 0.02). The effect of IMRT and SB203580 on inhibition of MCF-7 cell proliferation showed synergistic relation. Since MAPK signaling pathway plays an important role in the development of drug resistance, therefore, inhibition of p38 MAPK activation by the combination of IMRT followed by treatment with inhibitor for p38 MAPK can be a promising strategy for breast cancer treatment. Thus combination of IMRT exposure and treatment with SB203580 can be used for the inhibition of drug resistant breast cancer.