Intracellular delivery of NF-κB small interfering RNA for modulating therapeutic activities of classical anti-cancer drugs in human cervical cancer cells

Cervical cancer is the second most common cancer and fourth leading cause of cancer-related deaths among women. Advanced stage of the disease is treated with radiation therapy and chemotherapy with poor therapeutic outcome and adverse side effects. NFκB, a well-known transcription factor in the control of immunity and inflammation, has recently emerged as a key regulator of cell survival through induction of antiapoptotic genes. Many human cancers, including cervical carcinoma, constitutively express NF-κB and a blockade in expression of its subunit proteins through targeted knockdown of the gene transcripts with small interfering RNAs (siRNA) could be an attractive approach in order to sensitize the cancer cells towards the widely used anti-cancer drugs. However, the inefficiency of the naked siRNA to cross the plasma membrane and its sensitiveness to nuclease-mediated degradation are the major challenges limiting the siRNA technology in therapeutic intervention. pH-sensitive carbonate apatite has been established as an efficient nano-carrier for intracellular delivery of siRNA, due to its strong electrostatic interaction with the siRNA, the desirable size distribution of the resulting siRNA complex for effective endocytosis and the ability of the endocytosed siRNA to be released from the degradable particles and escape the endosomes, thus leading to the effective knockdown of the target gene of cyclin B1 or ABCB1. Here, we report that carbonate apatite-facilitated delivery of the siRNA targeting NF-κB1 and NF-κB2 gene transcripts in HeLa, a human cervical adenocar- cinoma cell line expressing NF-κB, led to a synergistic effect in enhancement of chemosensitivity to doxorubicin, but apparently not to cisplatin or paclitaxel.