Regulation and function of AP-1 in insulinoma cells and pancreatic β-cells

The effect of c-Fos on the prognosis, proliferation, and invasion of oral squamous cell carcinoma

OBJECTIVE

This study aimed to determine the role of c-Fos in growth and invasion of oral squamous cell carcinoma (OSCC).

METHODS

Immunohistochemistry was used to assess c-Fos expression in 94 OSCC tissues and 30 adjacent normal tissues, the correlation between c-Fos expression and clinicopathological characteristics was examined, and Kaplan-Meier and Cox analysis were used to investigate the role of c-Fos in predicting the prognosis of OSCC patients. The effects of c-Fos on the growth and invasion of OSCC were disclosed by overexpression and knockdown of c-Fos. Furthermore, based on bioinformatics prediction, the effect of miR-155-5p on c-Fos expression was examined, and dual-luciferase reporter assay system was used to determine whether miR-155-5p regulated the transcriptional activity of c-Fos in OSCC.

RESULTS

c-Fos was markedly increased in OSCC tissues and cells. c-Fos upregulation indicates a poor prognosis in OSCC patients, and c-Fos promotes cell proliferation, migration, and invasion in OSCC. miR-155-5p could regulate the expression and the transcriptional activity of c-Fos by directly targeting the c-Fos 3'-UTR.

CONCLUSION

This study demonstrated that c-Fos contributed to the progression of OSCC and may act as a potential target for OSCC therapy, and a potential prognostic biomarker of OSCC.

Insulin-Responsive Transcription Factors

The hormone insulin executes its function via binding and activating of the insulin receptor, a receptor tyrosine kinase that is mainly expressed in skeletal muscle, adipocytes, liver, pancreatic β-cells, and in some areas of the central nervous system. Stimulation of the insulin receptor activates intracellular signaling cascades involving the enzymes extracellular signal-regulated protein kinase-1/2 (ERK1/2), phosphatidylinositol 3-kinase, protein kinase B/Akt, and phospholipase Cγ as signal transducers. Insulin receptor stimulation is correlated with multiple physiological and biochemical functions, including glucose transport, glucose homeostasis, food intake, proliferation, glycolysis, and lipogenesis. This review article focuses on the activation of gene transcription as a result of insulin receptor stimulation. Signal transducers such as protein kinases or the GLUT4-induced influx of glucose connect insulin receptor stimulation with transcription. We discuss insulin-responsive transcription factors that respond to insulin receptor activation and generate a transcriptional network executing the metabolic functions of insulin. Importantly, insulin receptor stimulation induces transcription of genes encoding essential enzymes of glycolysis and lipogenesis and inhibits genes encoding essential enzymes of gluconeogenesis. Overall, the activation or inhibition of insulin-responsive transcription factors is an essential aspect of orchestrating a wide range of insulin-induced changes in the biochemistry and physiology of insulin-responsive tissues.