Abstract
X-chromosome-linked inhibitor of apoptosis protein (XIAP) is known to be an inhibitory factor against caspase-3. We examined radiation sensitivity of human cancer cells is enhanced by small interference RNA (siRNA) targeted for XIAP (XIAP-siRNA) through increase of caspase-3 activity. We used a human cultured non-small cell lung cancer cell line (H1299) lacking a tumor suppression gene of p53 gene. We prepared wild-type p53 cells (H1299/wtp53) and mutated p53 cells (H1299/mp53) having identical genetic background except for p53 gene. When 21-mer XIAP-siRNA was transfected into these cells with liposome, we observed the suppression of the constitutive expression of XIAP protein. Radiation sensitivities of wtp53 and mp53 cells were enhanced by XIAP-siRNA. In accordance with this, radiation-induced activation of caspase-3 was enhanced by XIAP-siRNA. These results suggest that XIAP-siRNA is a possible candidate for radiation sensitizer in radio-cancer therapy.
