Fatty acid synthase mediates high glucose-induced EGFR activation in oral dysplastic keratinocytes.

Abstract

Recent studies point to the epidermal growth factor receptor (EGFR) as a critical mediator of type 2 diabetes mellitus (T2DM)-induced renal, cardiac, and ocular complications. T2DM is considered a systemic contributing factor in oral carcinogenesis. Similarly, increased EGFR gene copy number and protein expression strongly predict tumor progression. Yet, the impact of hyperglycemia on EGFR activity in oral potentially malignant disorders remains unclear. We recently reported that fatty acid synthase (FASN), a key de novo lipogenic enzyme, mediates EGFR activation in nicotine-treated oral dysplastic keratinocytes. While in non-malignant tissues FASN expression is extremely low, it is frequently upregulated in several cancers, including oral squamous cell carcinoma. The present study was carried out to investigate whether high glucose conditions trigger pro-oncogenic responses in oral dysplastic keratinocytes via FASN-mediated EGFR activation. Cell viability and migration of oral dysplastic keratinocytes were evaluated when exposed to normal (5mM) or high (20mM) glucose conditions in the presence of FASN and EGFR inhibitors. Western blotting was also performed to assess changes in FASN protein expression and EGFR activation. Oral dysplastic keratinocytes exposed to high glucose led to EGFR activation in a FASN-dependent manner. Likewise, high glucose significantly enhanced cell viability and migration in a FASN/EGFR-mediated fashion. Notably, EGFR inhibition by the anti-EGFR monoclonal antibody cetuximab significantly reduced the proliferation of FASN-overexpressing oral dysplastic keratinocytes. These novel findings suggest that FASN may act as a key targetable metabolic regulator of glucose-induced EGFR oncogenic signaling in oral potentially malignant disorders.