Phenotypic changes induced by low concentration of glutamine in pancreatic cancer cells: Effects of a hypomethylating therapy


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Jose Neptuno Rodriguez-Lopez1,Maria Fernanda Montenegro1,Luis Sanchez-del-Campo1,Rebeca Gonzalez-Guerrero1,Juan Cabezas-Herrera2
1University of Murcia,2Instituto Murciano de Investigación Biosanitaria. University Hospital Virgen de la Arrixaca

Abstract

Background

Although cancer is a disease in which genetic abnormalities predominate, molecular studies have shown that epigenetic alterations share a leading role in their development. Pancreatic cancer is one of the leading causes of death in Western countries, mainly due to the lack of effective treatments. It is a poorly vascularized organ, which generates situations of nutrient deprivation as glutamine deficiency.

Method

We have conducted optical microscopy studies to study the morphology and growth of pancreatic cancer cells in different experimental conditions, as well as, electrophoresis, western-blot, and flow cytometry to study the expression of certain genes involved in the transition epithelium-mesenchyme (EMT), cell differentiation and the presence of immunogenic markers.

Results

We observed that a decrease in glutamine levels led the cells to a more mesenchymal phenotype (increasing the expression of proteins such as N-cadherin and vimentin, and decreasing E-cadherin) and to a more dedifferentiated state (increasing the expression of SOX2, CD24 and CD44). The lack of glutamine induces hypermethylation of a series of proteins (histones) that could result in the generation of a highly aggressive phenotype. In this sense, we observed that a hypomethylating treatment avoided the effects generated by the glutamine deprivation. In the presence of this treatment, the pancreatic cancer cells became insensitive to the lowering of glutamine and, in all cases, maintained a more epithelial and differentiated phenotype, thus decreasing the aggressiveness of these cells. It was interesting to note that hypomethylating therapy induced apoptosis in pancreatic tumor cells grown at low glutamine concentration.

Conclusion

Since intratumoral regional variation in the nutritional microenvironment contributes to tumor heterogeneity and therapeutic response, we conclude that this hypomethylating therapy could be of interest to eliminate more aggressive pancreatic tumor cells that grow in an environment of glutamine limitation.