Hyperglycemia of Tumor Microenvironment Modulates Stage-Dependent Tumor Progression and Multidrug Resistance: Implication of Cell Survival Regulatory Molecules and Altered Glucose Transport

Using a murine tumor model, we demonstrate that tumor cells display a tumor stage-dependent differential glucose utilization associated with an altered GLUT-1 expression. Hyperglycemic tumor microenvironment modulates the tumorigenic ability, survival, apoptosis, and glucose utilization of tumor cells in late tumor-bearing stage accompanied by an altered tumor acidosis and expression of cell survival regulatory molecules: HIF-1, p53, Bcl2, caspase-activated DNase, IL-4, IL-6, IL-10, IFN-, TGF-, and VEGF. Glucose-exposed tumor cells of late tumor-bearing stage also show a declined susceptibility to the cytotoxic action of chemotherapeutic drugs: cisplatin and methotrexate, accompanied by an increased expression of MDR-1 gene. Taken together the results show that hyperglycemic tumor microenvironment differentially alters tumor growth depending on the stage of tumor progression. (c) 2012 Wiley Periodicals, Inc.