Histone deacetylase inhibitors (HDACi) were recently identified as having significant clinical potential in reversing β-cell functional inhibition caused by inflammation, a shared precursor of Type 1 and Type 2 diabetes. However, HDACi are highly complex and little is known of their direct effect on important cell secretion pathways for blood glucose regulation. The aims of the present study were to investigate the effect of HDACi on insulin secretion from β-cells, GLP-1 secretion from L-cells, and recombinant insulin secretion from engineered L-cells. The β-cell line βTC-tet, L-cell line GLUTag, or recombinant insulin-secreting L-cell lines were exposed to Trichostatin A for 24. h. Effects on insulin or GLP-1 mRNA, intracellular protein content, processing efficiency, and secretion were measured by real-time PCR, ELISA, and radioimmunoassay. HDACi increased secretion per viable cell in a dose-dependent manner for all cell types. Effects on mRNA levels were variable, but enhanced intracellular polypeptide content and secretion were comparable among cell types. Enhanced recombinant insulin secretion was sustained for seven days in alginate microencapsulated L-cells. HDACi enhances β- and L-cell secretion fluxes in a way that could significantly improve blood glucose regulation in diabetes patients and holds potential as a novel method for enhancing insulin-secreting non-β or β-cell grafts.
In this study, we investigated the effects of the natural antioxidant curcumin on the HPV16-positive oral carcinoma cell line 93VU147T and demonstrated that curcumin is not only a potent inhibitor for the activity of host nuclear transcription factors AP-1 and NF-kB but it also selectively suppresses transcription of the HPV16/E6 oncogene during the carcinogenic process in oral cancer cells. This study suggests a therapeutic potential of curcumin for high-risk human papilloma virus (HPV)-infected oral cancers.