Exosome-delivered miR-769-3p promotes malignant progression of hepatocellular carcinoma via ALKBH5-dependent m6A modification.

BACKGROUND: Hepatocellular carcinoma (HCC) is a highly heterogeneous malignancy, and its intrinsic variability contributes to aggressive progression, recurrence, and therapeutic resistance. Exosomes are key mediators of intercellular communication among tumor cells with different malignant potentials, while N6-methyladenosine (m6A) modification has emerged as a critical epigenetic regulator of tumorigenesis. However, the mechanisms by which exosome-mediated m6A regulation contributes to HCC progression and heterogeneity remain poorly understood. METHODS: Exosomal microRNA (miRNA) profiles from HCC cells with distinct malignant phenotypes were analyzed using microarray analysis, and the clinical relevance of miR-769-3p was evaluated in samples of HCC patients. Gain- and loss-of-function assays were performed to assess its effects on HCC proliferation and metastasis both in vitro and in vivo. AlkB homolog 5 (ALKBH5) was identified as a downstream target of miR-769-3p, and its m6A-dependent regulatory mechanism was investigated using methylated RNA immunoprecipitation sequencing and subsequent validation assays. In addition, a liposome-based drug delivery system targeting miR-769-3p was developed and evaluated for therapeutic efficacy. RESULTS: Exosomal miR-769-3p was significantly enriched in highly malignant HCC cells and was associated with poor clinical outcomes. Functional studies demonstrated that exosomal miR-769-3p promoted HCC proliferation and metastasis by suppressing ALKBH5 expression. Mechanistically, ALKBH5 inhibited the expression of the oncogene G protein subunit alpha z (GNAZ) in an m6A-dependent manner, while ALKBH5-mediated destabilization of GNAZ transcripts required the m6A reader insulin-like growth factor 2 mRNA-binding protein 1. Importantly, in vivo experiments revealed that a liposomal delivery system targeting miR-769-3p markedly suppressed HCC tumor growth and metastatic dissemination. CONCLUSIONS: Exosomal miR-769-3p mediates malignant intercellular communication between HCC subtypes by regulating the ALKBH5/m6A/GNAZ axis. Targeting miR-769-3p using a liposome-based delivery strategy represents a promising therapeutic approach for HCC. These findings provide novel mechanistic insights into HCC progression and identify a potential therapeutic target for HCC treatment.