Some chemotherapeutic drugs induce NF-κB activation by degrading the IκBα protein in cancer cells which contributes to anticancer drug resistance. We hypothesized that inhibiting IκBα degradation would block NF-κB activation and result in increased tumor cell mortality in response to chemotherapy.

The "superrepressor" form of the NF-κB inhibitor was transferred by an adenoviral vector (Ad-IκBα-SR) to the human lung cancer cell lines (NCI H157 and NCI H460). With a MTT assay, the level of sensitization to cisplatin and paclitaxel were measured. To confirm the mechanism, an EMSA and Annexin V assay were performed.

EMSA showed that IκBα-SR effectively blocked the NF-κB activation induced by cisplatin. Transduction with Ad-IκBα-SR resulted in an increased sensitivity of the lung cancer cell lines to cisplatin and paclitaxel by a factor of 2~3 in terms of IC50. Annexin-V analysis suggests that this increment in chemosensitivity to cisplatin probably occurs through the induction of apoptosis.

The blockade of chemotherapeutics induced NF-κB activation by inducing Ad-IκBα-SR, increased apoptosis and increasing the chemosensitivity of the lung cancer cell lines tested, subsequently. Gene transfer of IκBα-SR appears to be a new therapeutic strategy of chemosensitization in lung cancer.