Pyrimidine-2,4-dione targets STAT3 signaling pathway to induce cytotoxicity in hepatocellular carcinoma cells

[Display omitted] •14 N-methyluracil analogs were synthesized using ligand-free Suzuki-Miyaura reaction.•MNK8 showed good growth inhibition against hepatocellular carcinoma (HCC) cells.•MNK8 increased SubG1 cell population and induced apoptosis in HCC cells.•MNK8 inhibited STAT3 activation and reduced its DNA binding ability.•MNK8 reduced prosurvival proteins expression & migration/invasion of HCC cells. Signal transducer and activator of transcription 3 (STAT3) is a tumorigenic transcription factor that is persistently activated in various human cancers including hepatocellular carcinoma (HCC). Therefore, STAT3 is considered as a prominent target to counteract the uncontrolled proliferation of cancer cells. In the present report, pyrimidine-2,4-diones (N-methyluracil derivatives) (MNK1-MNK14) were synthesized in an ionic liquid (BMIm PF6) medium employing a ligand-free Suzuki-Miyaura cross-coupling process. Among the 14 derivatives, compound MNK8 showed good cytotoxicity towards both the tested cell lines and did not display a toxic effect against normal hepatocytes (LO2). MNK8 significantly increased the Sub-G1 cell count in both cell lines and the cytotoxic effect of MNK8 was found to be mediated through the suppression of constitutive phosphorylation of STAT3Y705. It also decreased the DNA interaction ability of nuclear STAT3 in HCC cells. MNK8 downregulated the levels of apoptosis-related proteins (such as Bcl-2, cyclin D1, survivin) and increased cleaved caspase-3 inferring the apoptogenic effect of MNK8. It also reduced the CXCL12-triggered cell migration and invasion in in vitro assay systems. Overall, MNK8 has been demonstrated as a new inhibitor of STAT3 signaling cascade in HCC cells.