Tag Archives: U87 glioma cells

ERN1 modifies the effect of glutamine deprivation on tumor growth related factors expression in U87 glioma cells

O. H. Minchenko, A. P. Kharkova, O. S. Hnatiuk, O. Y. Luzina, I. V. Kryvdiuk, A. Y. Kuznetsova

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com

The expression of a subset of genes encoding important tumor growth related factors in U87 glioma cells with ERN1 (endoplasmic reticulum to nucleus signaling 1) loss of function as well as upon glutamine deprivation was studied. It was shown that glutamine deprivation down-regulated the expression level of ATF6 (activating transcription factor 6), EIF2AK3/PERK (eukaryotic translation initiation factor 2 alpha kinase 3), GLO1 (glyoxalase I), BIRC5 (baculoviral IAP repeat-containing 5), and RAB5C (RAB5C, a member of RAS oncogene family) mRNAs in control glioma cells. At the same time, the expression level of HSPB8 (heat shock 22kDa protein 8) and HSPA5/GRP78 (heat shock protein family A (Hsp70) member 5) mRNAs was resistant to glutamine withdrawal in these glioma cells. It was also shown that inhibition of ERN1, which controled cell proliferation and tumor growth, modified the effect of glutamine deprivation on the expression levels of most studied genes in U87 glioma cells: up-regulated the expression of ATF6 and HSPA5 genes and enhanced sensitivity of EIF2AK3 and BIRC5 genes to glutamine withdrawal. Furthermore, the expression of all studied genes, except EIF2AK3, was down-regulated in ERN1 knockdown glioma cells in the presence of glutamine. It was demonstrated that glutamine deprivation affected the expression of most studied genes in ERN1 depen­dent manner and that these changes possibly contributed to the suppression of glioma growth from cells without ERN1 signaling enzyme function.

Expression of ubiquitin specific peptidase and ATG7 genes in U87 glioma cells upon glutamine deprivation

O. V. Halkin1, D. O. Minchenko1,2, О. O. Riabovol1,
V. V. Telychko1, О. O. Ratushna1, O. H. Minchenko1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bohomolets National Medical University, Kyiv, Ukraine

We have studied the effect of glutamine deprivation on the expression of genes encoding for ubiquitin specific peptidases (USP) and ubiquitin activating enzyme E1-like protein/autophagy related 7 (GSA7/ATG7) in U87 glioma cells in relation to inhibition of inositol requiring enzyme-1 (IRE1). It was shown that exposure of control glioma cells (transfected by empty vector) upon glutamine deprivation led to suppression of USP1 and ATG7 mRNA expression and up-regulated USP25 mRNA. At the same time, glutamine deprivation did not significantly change USP4, USP10, USP14, and USP22 gene expressions in these cells. Inhibition of ІRE1 signaling enzyme function in U87 glioma cells increased effect of glutamine deprivation on the expression of USP1 gene and introduced sensitivity of USP4 and USP14 genes to this condition. Therefore, glutamine deprivation affected the expression level of most studied genes in gene specific manner in relation to the functional activity of IRE1 enzyme, a central mediator of endoplasmic reticulum stress, which controls cell proliferation and tumor growth.

Expression of tumor growth related genes in IRE1 knockdown U87 glioma cells: effect of hypoxia

O. H. Minchenko1, O. Y. Luzina1, O. S. Hnatiuk1,
D. O. Minchenko1,2, I. A. Garmash1, O. O. Ratushna1

1Palladin Institute of Biochemistry,  National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bohomolets National Medical University, Kyiv, Ukraine

We have studied the effect of IRE1 signaling enzyme knockdown as well as hypoxia on the expression of genes encoding the important tumor growth related proteins (BRCA1, DEK, BCL2L1, COL6A1, TPD52, HOMER3, and GNPDA1) in U87 glioma cells. It was shown that the expression level of breast cancer 1 early onset (BRCA1) and tumor protein D52 (TPD52) mRNAs are strongly up-regulated in U87 glioma cells by down-regulation of IRE1 expression in comparison with the control cells. At the same time the expression level of collagen, type VI, alpha 1 (COL6A1), DEK oncogene (DEK), glucosamine-6-phosphate deaminase 1 (GNPDA1) and homer homolog 3 (HOMER3) was significantly down-regulated in glioma cells under these experimental conditions. It was also shown that hypoxia up-regulated the expression level of COL6A1 and TPD52 mRNAs and down-regulated – BRCA1, DEK, and GNPDA1 mRNAs in control glioma cells and that down-regulation of IRE1, which control cell proliferation and tumor growth, modified the effect of hypoxia on the expression of COL6A1, DEK, BCL2L1, HOMER3, and GNPDA1 genes. The present study demonstrated that hypoxia affected the expression of most studied genes in IRE1-dependent manner.

IRE1 knockdown modifies hypoxic regulation of cathepsins and LONP1 genes expression in U87 glioma cells

O. H. Minchenko1, О. O. Riabovol1, O. V. Halkin1,
D. O. Minchenko1,2, О. O. Ratushna1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bohomolets National Medical University, Kyiv, Ukraine

We have studied the effect of hypoxia on the expression of genes encoding for LONP1/PRSS15 and cathepsins in U87 glioma cells in relation to inhibition of inositol requiring enzyme-1 (IRE1). It was shown that hypoxia up-regulated the expression of CTSA, CTSB, CTSD, CTSF, CTSK, and LONP1 genes and down-regulated the expression of CTSC, CTSL, CTSO, and CTSS genes in control glioma cells (transfected by empty vector). Inhibition of ІRE1 signaling enzyme function in these glioma cells modified effect of hypoxia on the expression of most studied genes: eliminated the effect of hypoxia on CTSA, and LONP1 genes, introduced reverse changes on CTSD and CTSS genes, reduced – on CTSF and CTSK genes, and enhanced – on CTSB and CTSL genes. Therefore, hypoxia affected the expression level of most studied genes in relation to the functional activity of IRE1 enzyme, a central mediator of endoplasmic reticulum stress, which control cell proliferation and tumor growth.

Inhibition of IRE1 modifies hypoxic regulation of G6PD, GPI, TKT, TALDO1, PGLS and RPIA genes expression in U87 glioma cells

O. H. Minchenko1, I. A. Garmash1, D. O. Minchenko1,2,
A. Y. Kuznetsova1, O. O. Ratushna1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bohomolets National Medical University, Kyiv, Ukraine

We have studied the effect of hypoxia on the expression level of mRNA of the basic enzymes of pentose-phosphate cycle (G6PD, TKT, TALDO1, PGLS and RPIA) and glucose-6-phosphate isomerase (GPI) in U87 glioma cells in relation to inhibition of IRE1 (inositol requiring enzyme 1). It was shown that hypoxia leads to up-regulation of the expression of GPI and PGLS genes and to down-regulation of TALDO1 and RPIA genes in control glioma cells. Changes for GPI gene were more significant than for other genes. At the same time, inhibition of IRE1 modified the effect of hypoxia on the expression of all studied genes. In particular, it increased sensitivity to hypoxia of G6PD and TKT genes expression and suppressed the effect of hypoxia on the expression of GPI and RPIA genes. Additionally, inhibition of IRE1 eliminated hypoxic regulation of PGLS gene and did not change significantly effect of hypoxia on the expression of TALDO1 gene in glioma cells. Present study demonstrated that hypoxia, which often contributes to tumor growth, affects the expression of most studied genes and inhibition of IRE1 modified the hypoxic regulation of pentose-phosphate cycle gene expressions in a gene specific manner and thus possibly contributes to slower glioma growth, but several aspects of this regulation warrant further investigation.

Effect of hypoxia on the expression of nuclear genes encoding mitochondrial proteins in U87 glioma cells

O. H. Minchenko1, О. O. Riabovol1, D. O. Tsymbal1, D. O. Minchenko1,2, О. O. Ratushna1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bohomolets National Medical University, Kyiv, Ukraine

We have studied the effect of hypoxia on the expression of nuclear genes encoding mitochondrial proteins in U87 glioma cells under the inhibition of IRE1 (inositol requiring enzyme-1), which controls cell proliferation and tumor growth as a central mediator of endoplasmic reticulum stress. It was shown that hypoxia down-regulated gene expression of malate dehydrogenase 2 (MDH2), malic enzyme 2 (ME2), mitochondrial aspartate aminotransferase (GOT2), and subunit B of succinate dehydrogenase (SDHB) in control (transfected by empty vector) glioma cells in a gene specific manner. At the same time, the expression level of mitochondrial NADP+-dependent isocitrate dehydrogenase 2 (IDH2) and subunit D of succinate dehydrogenase (SDHD) genes in these cells does not significantly change in hypoxic conditions. It was also shown that the inhibition of ІRE1 signaling enzyme function in U87 glioma cells decreases the effect of hypoxia on the expression of ME2, GOT2, and SDHB genes  and introduces the sensitivity of IDH2 gene to hypoxia. Furthermore, the expression of all studied genes depends on IRE1-mediated endoplasmic reticulum stress signaling in gene specific manner, because ІRE1 knockdown significantly decreases their expression in normoxic conditions, except for IDH2 gene, which expression level is strongly up-regulated. Therefore, changes in the expression level of nuclear genes encoding ME2, MDH2, IDH2, SDHB, SDHD, and GOT2 proteins possibly reflect metabolic reprogramming of mitochondria by hypoxia and IRE1-mediated endoplasmic reticulum stress signaling and correlate with suppression of glioma cell proliferation under inhibition of the IRE1 enzyme function.