Novel transduction of nutrient stress to Notch pathway by RasGRP3 promotes malignant aggressiveness in human esophageal squamous cell carcinoma.

In the process of enlarging of tumors, the dissolving tissue structures and remodeling endothelial cells for restoring gas exchange and nutritional support, further facilitate tumor cell invasion and metastasis. Activation of Ras plays a critical role in the development of esophageal squamous cell carcinoma (ESCC), but the underlying mechanisms remain poorly understood. We therefore investigated whether Ras guanyl-releasing protein 3 (RasGRP3), a Ras activator, could promote metastasis by inducing vascular regeneration and further epithelial-mesenchymal transition under nutrient stress (NS). In the present study, we explored that the accumulation of RasGRP3 regulated vascular endothelial growth factor-A production, co-stimulated Notch pathway with high expression of Notch intracellular domain (NICD) and Hes1. Moreover, ESCC cells under NS increased the expression of vimentin, Snail, Slug and MMP9 proteins; while inhibition of Notch activation by DAPT (a γ-secretase inhibitor) or RasGRP3-targeted RNA interference prevented from the effect. In conclusion, these findings provide a new insight into the upregulation of RasGRP3 involved in Notch pathway activation in the development of ESCC, especially under nutrient deprivation.