Background: The diabetes-cancer link may be mediated by inflammation due to infection such as Human Papilloma Virus (HPV). Exendin 4, a Glucagon-like-peptide 1 agonist, has anti-hyperglycemic and anti- inflammatory effect and can attenuate certain cancer growth.
Methods: We used RNA microarray analysis to detect the gene expression after Exendin 4 treatment in the db/db mouse tumor, which was established by inoculation of mouse PV cancer cells (CUP-1). The latter originates from the kidney of baby C57BL/6J mice expressing HPV-16 E7 oncogene. We examined the effect of Exendin 4 on cell proliferation, apoptosis and gene expression along the inflammatory pathway in CUP-1 under different glucose environment. We developed CUP-1 cells with or without target gene overexpression (OE) or downregulation (DR) for inoculation into the db/db mouse. We compared RNA expression of the target gene in cervical cancer specimen from patients with or without diabetes.
Results: RNA expression of proteasome 20s (psma) was decreased after Exendin 4 treatment in the db/db mouse tumor. High glucose environment increased cell proliferation in CUP-1 cells, which was enhanced after OE of psma but attenuated after DR of psma. Exendin 4 suppressed NFκB P65 and IκB activation in CUP-1 cells under high glucose medium. After inoculation of CUP-1 cells with DR and OE of psma, the tumor size was decreased and increased in db/db mice respectively. Exendin 4 decreased the tumor volume in the db/db mice of psma OE group. In human cervical cancer specimen, RNA expression of psma was increased in patients with diabetes versus those without diabetes.
Conclusion: High glucose increased expression of psma, which activated NFκB inflammation pathway and promoted carcinogenesis. Exendin 4 suppressed the NFκB pathway activation and decreased tumor volume with corroborative evidence from human samples, suggesting that the anti-cancer effect of Exendin 4 might be mediated by the psma-NFκB pathway.
D. Mao: None. J.C. Chan: None.