Genistein nanoformulation promotes selective apoptosis in oral squamous cell carcinoma through repression of 3PK-EZH2 signalling pathway.

Overexpression of polycomb protein contributes to epigenetic repression in oral squamous cell carcinoma (OSCC) ensuing in poor prognosis and aggressive phenotype. Several plant-based compounds could help prevent epigenome alteration and cancer progression, but their low bioavailability limits their therapeutic activity. In this study, we have synthesized genistein nanoformulation (GLNPs) and evaluated its epigenetic regulation mechanism for selective apoptosis induction in OSCC. Lactalbumin was used to prepare nanoformulation of Genistein. The mechanism of epigenetic regulation and selective apoptosis by Genistein loaded nanoparticles was studied in OSCC cell line JHU011 and fibroblast cell line L929 using immunofluorescence, Western blotting and ChIP-qPCR assay. We have found that GLNPs treatment selectively induced apoptosis in OSCC compared to the normal fibroblast cells. This selective effect in OSCC is achieved through enhanced reactive oxygen species (ROS) generation followed by Bax mitochondrial translocation and caspase 3 activation. Further, GLNPs induced withdrawal of epigenetic transcription repression through concurrent downregulation of the polycomb group proteins (PcG) Bmi 1 and EZH2 along with their successive targets, UbH2AK119 and H3K27me3, which have immense therapeutic implications in the treatment of OSCC. Last, we have established that GLNPs regulate EZH2expression through proteasomal mediated degradation and 3PK inhibition; 3PK protein was found physically linked with EZH2 protein and its promoter region (-1107 to -1002). This event indicates that 3PK might play some crucial role in EZH2 expression and epigenetic control of OSCC. Moreover, the formulation showed improved biodistribution, aqueous dispersibility and enhanced biocompatibility In-vivo. These results provide evidence that GLNPs may withdraw epigenetic transcriptional repression and selectively induce apoptosis in human oral squamous cell carcinoma.