[p14ARF enhances chemosensitivity to cisplatin in human osteosarcoma U2OS cells through p53 apoptotic pathway]

To explore the effects of tumor suppressor p14ARF on chemosensitivity of human osteosarcoma U2OS cells to cisplatin and elucidate its molecular mechanism.

U2OS cells expressing no p14ARF and U2OS-ARF cells expressing p14ARF stably through stable transfection were treated with cisplatin. Cell viability and IC50 were assayed with methyl thiazolyl tetrazolium (MTT). Apoptosis was examined by fluorescence-activated cell sorting and Hoechst33258 staining. The expressions of p53, Bax, p21, Mdm2 and Fas were detected by Western blot. And colorimetry was used to determine the activities of caspase-3, caspase-8 and caspase-9.

The viability was 84.8% ± 4.4%, 86.9% ± 5.0% and 66.7% ± 4.6% respectively in U2OS, U2OS-vec and U2OS-ARF cells. The values of IC50 were (15.8 ± 0.9) µmol/L, (16.3 ± 0.6) and (8.9 ± 0.8) µmol/L respectively in U2OS, U2OS-vec and U2OS-ARF cells. The levels of viability and IC50 obviously decreased in U2OS-ARF cells in response to cisplatin (P < 0.05). There were higher apoptotic rate and more obvious apoptotic morphological changes in U2OS-ARF cells than U2OS and U2OS-vec cells. The basal levels of p53, Mdm2 and p21 in U2OS-ARF cells were slightly higher than those in U2OS-vec cells. Cisplatin up-regulated p53, Mdm2 and p21 in both cell lines. However, the up-regulation was more pronounced in U2OS-ARF cells. Cisplatin did not change the levels of Bax and Fas in U2OS-vec cells. Bax protein was up-regulated in U2OS-ARF cells while the level of Fas remained constant. p14ARF also enhanced the activities of caspase-9 and caspase-3 in response to cisplatin.

p14ARF enhances the chemosensitivity to cisplatin in human osteosarcoma U2OS cells through p53 apoptotic pathway. And intrinsic mitochondrial apoptosis is involved.