Silibinin inhibits endometrial carcinoma via blocking pathways of STAT3 activation and SREBP1-mediated lipid accumulation

Aims: To seek new conservative treatments for young women with early-stage endometrial carcinoma (EC) who desire to retain fertility, we investigated the effects and the underlying mechanism of silibinin in EC, which exhibits promising anti-cancer and tumour-suppressing properties in many malignant tumours. Main methods: Through relevant experiments such as MTT assay, cell colony formation assay and subcutaneous xenograft experiment, we showed that silibinin inhibited the proliferation of EC cells and tumours. Silibinin significantly induced cell cycle arrest and promoted apoptosis in vitro. In vivo TUNEL assay confirmed the apoptotic effect caused by silibinin. STAT3 is activated in the development of tumours. Silibinin notably inhibited the expression of STAT3 phosphorylation and regulated the expression of downstream genes involved in cell cycle and apoptosis at protein and mRNA levels in EC cells. Furthermore, silibinin decreased the expression of intranuclear SREBP1, which is a key regulator of lipid metabolism in the nucleus, and reduced the lipid accumulation in EC cells. Downregulation of the expression levels of SREBP1 and its downstream genes associated with lipid metabolism was also observed in silibinin-treated EC cells. Key findings: The results revealed that a novel anticancer drug, silibinin, markedly suppressed cell proliferation, cell cycle progression, apoptosis inhibition and lipid accumulation by blocking STAT3 and SERBP1 signalling pathways in EC cells.