[Increased radiosensitivity of lung cancer cell lines related with the functionally replaced p14ARF gene]

To assess the possibility that whether restored or enforced function of p14ARF could influence the radiosensitivity of lung cancer cells in vitro.

Human lung cancer cell lines with various endogenous backgrounds in INK4a, p53 and Rb genes were used as the recipients of the wild-type p14ARF gene. The expression of p14ARF mRNA and protein was detected with RT-PCR, immunohistochemistry and Western immunoblot after G418 selection. Clones expressing both p14ARF mRNA and protein were identified and selected for further experiments. By comparing with the parental and negative control cells prepared with empty vector, the effects of exogenously transfected p14ARF on cell cycle distribution, cell survival fraction and radiation-induced proportion of apoptosis were analyzed.

The cell cycles of three wild-type p53 cell lines were arrested in G1 phase or G1 and G2-M phases. A significant decline in the proportion of S phase was observed in H460-p14ARF and A549-p14ARF cells, with decreased survival fraction and prolonged G2 delay after irradiation. We also observed in A549-p14ARF cells an increased percentage of apoptosis when radiated.

The exogenously transfected wild-type p14ARF could increase the radiosensitivity of some lung cancer cells. It appears that cell cycle redistribution of cells after acquiring p14ARF may be the main explanation for the enhanced sensitivity. The increased apoptosis proportion of A549-p14ARF cells in response to radiation indicates a fortified p53 function and might partly contribute to the increased sensitization.