Expression of IGFBP1, IGFBP2 and IGF2BP3 genes in U87 glioma cells with suppressed ERN1 signaling enzyme function in glutamine and glucose deprivation conditions

Insulin-like growth factor binding proteins play an important role in the regulation of cell proliferation and malignant tumor growth. It was shown that blockade of both enzymatic functions of sensor and signaling enzyme ERN1 (from endoplasmic reticulum to nuclei-1), the major component of endoplasmic reticulum stress signaling, decreases the expression level of IGFBP1, IGFBP2 and IGF2BP3 genes in U87 glioma cell. The decreased level of these gene expressions in glioma cells with ERN1 signaling enzyme loss of function correlates with suppression of cell proliferation. It was shown that glutamine deprivation condition leads to enhance the expression of IGFBP1 gene, but did not change significantly the expression of IGFBP2 and IGF2BP3 genes in both types of glioma cells. Moreover, this effect of glutamine deprivation did not depend from suppression of ERN1 enzyme function. At the same time, the expression of IGFBP2 and IGF2BP3 genes is decreased in glucose deprivation condition in both types of glioma cells and blockade of ERN1 signaling enzyme enhanced this effect. Thus, results of this investigation demonstrated that the expression of IGFBP1, IGFBP2 and IGF2BP3 genes in U87 glioma cells is dependent from signaling enzyme ERN1 and is changed in glutamine and glucose deprivation conditions, but only effect of glucose deprivation was depended of ERN1 signaling enzyme function. Moreover, the decreasing of IGFBP1, IGFBP2 and IGF2BP3 gene expressions in glioma cells with blockade of both enzymatic activities of ERN1 is possibly related to suppression of these cells proliferation.