Cancer Gene Therapy Utilizing NF-κB-regulated Expression of a miRNA Targeting RelA.

BACKGROUND: Cancer continues to threat human health and life because of issues such as drug resistance and low response rates. The transcription factor NF-κB has emerged as a promising target for cancer therapy because of its overactivation in various cancers. However, existing NF-κB inhibitors lack cancer-cell specificity, leading to widespread suppression of essential physiological roles in immune regulation and cell survival, which results in systemic toxicity. METHODS: In contrast to the direct inhibition of NF-κB activity, this study introduces a novel antitumour strategy, DMP-miR533, which leverages NF-κB activity in cancer cells. This strategy employs a previously developed NF-κB-activated promoter, DMP, comprising five κB binding sites functioning as an NF-κB decoy and a minimal promoter, along with an artificial microRNA, miR533, that targets NF-κB RelA. Additionally, we constructed a variant with five copies of DMP-miR533, termed 5 × DMP-miR533. RESULTS: We assessed the antitumour efficacy of DMP-miR533 in cultivated human and mouse cells and observed that both DMP-miR533 and 5 × DMP-miR533 induced significant cancer cell death, but didn’t affect the growth of normal cells. By encapsulating DMP-miR533 in an adeno-associated virus (AAV) vector to generate a recombinant AAV (rAAV), designated rAAV-DMP-miR533, significant inhibition of tumour growth was achieved through intravenous administration of rAAV in murine cancer models: H22 cell-formed hepatocellular carcinoma, WEHI-3 cell-formed leukaemia, and CT-26 cell-formed colon cancer. Notably, DMP-miR533 demonstrated substantial antitumour efficacy in both in vitro cell lines and in vivo mouse models without eliciting any observable side effects or toxicity. CONCLUSION: This study presents a promising and biosafe cancer gene therapy strategy involving regulation of NF-κB activity by a RELA-targeting microRNA, whose expression is controlled by a promoter that can sense the NF-κB activity in cells.