KDM4A-driven SMAD5/TGFβ axis activation as a therapeutic target in cholangiocarcinoma: mechanistic insights and translational implications.

backgroundCholangiocarcinoma is a malignancy with poor prognosis and increasing incidence in recent years. Apart from early surgical resection, other treatments have shown limited efficacy. Lysine-specific demethylase 4A (KDM4A), a histone demethylase, is known to have a promotional effect on a variety of tumours. However, its impact on cholangiocarcinoma remains underexplored.

methodsThe expression differences of KDM4A in cholangiocarcinoma and adjacent tissues were analyzed by database and tissue microarray. The effects of KDM4A on the growth and proliferation ability of cholangiocarcinoma cells were explored through subcutaneous tumor formation experiments in nude mice and cholangiocarcinoma mouse models. The regulatory role of KDM4A on TGFβ pathway was analyzed by real-time quantitative PCR and Western blot experiments. Bioinformatics methods were employed to predict KDM4A binding, which was validated by chromatin immunoprecipitation.

resultsKDM4A was highly expressed in cholangiocarcinoma tissues compared with normal tissues, and KDM4A significantly promoted the proliferation and invasion ability of cholangiocarcinoma. KDM4A positively regulated SMAD5, upregulating its expression and subsequently promoting the expression of TGFβ pathway target genes ID1 and ID2. Knockdown of SMAD5 could reverse the biological effects caused by KDM4A. The expression of SMAD5 was regulated by the histone methylation mark H3K9me3. KDM4A was enriched at the SMAD5 gene promoter region, downregulated H3K9me3 marks, and thus promoted SMAD5 transcription. KDM4A inhibitor can inhibit the proliferation and invasive ability of cholangiocarcinoma through the aforementioned mechanisms. Treatment of cholangiocarcinoma model mice with a KDM4A inhibitor resulted in significantly reduced liver volume and lesion area in the treatment group compared to the control group.

conclusionIn summary, KDM4A promotes the development of cholangiocarcinoma by regulating SMAD5 to activate the TGFβ pathway. The KDM4A inhibitor JIB-04 shows potential in inhibiting cholangiocarcinoma progression, providing a rationale for the epigenetic therapy of cholangiocarcinoma.