Effect of miR-34b overexpression on the radiosensitivity of non-small cell lung cancer cell lines.

Background: The miR-34 family, under-expressed in-non small cell lung cancers (NSCLCs), are effectors of p53 activation upon irradiation of cells. We evaluated whether the miR-34b overexpression modulates the NSCLCs response to radiation.

Materials And Methods: NSCLC cell lines A549 with V-KI-RAS2 Kirsten Rat Sarcoma viral oncogene (KRAS) codon 12 mutation and with wild type p53, and H1299, not expressing p53, were irradiated after transfection with pre-miR-34b. Cell survival was assessed by clonogenic survival assays. The apoptosis and the cell cycle were evaluated by flow cytometry.

Results: In the A549 cell line, overexpression of miR-34b significantly reduced cell survival at lower than 4 Gy radiation doses. There was a significant reduction in B-cell CLL/lymphoma 2 (BCL2) expression but no significant differences were observed in the apoptotic cell population or the cycle profile. No significant effect was recorded in the H1299 irradiated cells.

Conclusion: In the p53 wild type, KRAS mutated NSCLC cells, the overexpression of miR-34b increases radiosensitivity at low doses of radiation.