Effect of Restoration of Retinoblastoma Gene Function on the Radiosensitivity of Cells of Human Tumor Cell Lines

To assess the role of expression of the retinoblastoma (RB) gene on the sensitivity of cells to the cytotoxic effects of ionizing radiation, we transfected a normal RB gene into cells of <tex-math>${\rm RB}^{+}$</tex-math> and <tex-math>${\rm RB}^{-}$</tex-math> osteosarcoma cell lines and an <tex-math>${\rm RB}^{-}$</tex-math> prostate carcinoma line and studied the radiosensitivity of the cells before and after transfection. Four transfected clones were isolated from the two <tex-math>${\rm RB}^{-}$</tex-math> tumor cell lines that expressed the product of the transfected normal RB gene and contained no mutations in the pocket and C-terminal regions by sequencing. A small increase in radiosensitivity was observed in cell lines transfected with the pDOL plasmid vector alone, containing the neo gene and a long terminal repeat (LTR) promoter. However, no significant change in radiosensitivity occurred in transfected cells expressing the normal RB gene compared to controls transfected with an <tex-math>${\rm RB}^{-}$</tex-math> plasmid. Based on this and other information, we conclude that RB gene function is not involved in the response of these human tumor cells to the cytotoxic effects of radiation.