RBM39 Promotes Base Excision Repair to Facilitate the Progression of HCC by Stabilising OGG1 mRNA.

Targeting base excision repair (BER) has been an attractive strategy in cancer therapeutics. RNA-binding motif protein 39 (RBM39) modulates the alternative splicing of numerous genes involved in cancer occurrence and progression. However, whether and how RBM39 regulates BER in hepatocellular carcinoma (HCC) remain unclear. Here, we found that under oxidative stress, RBM39 degradation or knockdown decreased BER efficiency in HCC cells using a well-designed BER reporter. Further assays showed that RBM39 promoted HCC cell proliferation, migration, and invasion, enhancing cell survival and inhibiting apoptosis. Mechanistically, RBM39 interacted with the mRNA of the essential glycosidase 8-oxoguanine-DNA glycosylase 1 (OGG1), thereby stabilising OGG1 mRNA. This in turn increases OGG1 expression and promotes BER efficiency in HCC. Moreover, data suggested that RBM39 degradation, combined with oxidative damage, could be more effective for HCC treatment than monotherapy, both in vitro and in xenograft mice models. Overall, we demonstrated that RBM39 regulated OGG1 stabilisation and improved BER efficiency, suggesting that combining the RBM39 degradant indisulam with the oxidising agent KBrO₃ could be an emerging strategy for HCC treatment.