Tag Archives: hypoxia
Effect of hypoxia on the expression of genes that encode some IGFBP and CCN proteins in U87 glioma cells depends on IRE1 signaling
O. H. Minchenko1, A. P. Kharkova1, D. O. Minchenko1,2, L. L. Karbovskyi1
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 hypoxic regulation of the expression of different insulin-like growth factor binding protein genes in U87 glioma cells in relation to inhibition of IRE1 (inositol requiring enzyme-1), a central mediator of endoplasmic reticulum stress, which controls cell proliferation and tumor growth. We have demonstrated that hypoxia leads to up-regulation of the expression of IGFBP6, IGFBP7, IGFBP10/CYR61, WISP1, and WISP2 genes and down-regulation – of IGFBP9/NOV gene at the mRNA level in control glioma cells, being more significant changes for IGFBP10/CYR61 and WISP2 genes. At the same time, inhibition of IRE1 modifies the effect of hypoxia on the expression of all studied genes: eliminates sensitivity to hypoxia the expression of IGFBP7 and IGFBP9/NOV genes, suppresses effect of hypoxia on IGFBP6, IGFBP10/CYR61, and WISP2 genes, and slightly enhances hypoxic regulation of WISP1 gene expression in glioma cells. We have also demonstrated that the expression of all studied genes in glioma cells is regulated by IRE1 signaling enzyme upon normoxic condition, because inhibition of IRE1 significantly up-regulates IGFBP7, IGFBP10/CYR61, WISP1, and WISP2 genes and down-regulates IGFBP6 and IGFBP9/NOV genes as compared to control glioma cells. The present study demonstrates that hypoxia, which contributes to tumor growth, affects all studied IGFBP and WISP gene expressions and that inhibition of IRE1 preferentially abolishes or suppresses the hypoxic regulation of these gene expressions and thus possibly contributes to slower glioma growth. Moreover, inhibition of IRE1, which correlates with suppression of cell proliferation and glioma growth, is down-regulated expression of pro-proliferative IGFBP genes, attesting to the fact that endoplasmic reticulum stress is a necessary component of malignant tumor growth.
Endoplasmic reticulum stress, its sensor and signalling systems and the role in regulation of gene expression at malignant tumor growth and hypoxia
O. H. Minchenko, A. P. Kharkova, T. V. Bakalets, I. V. Kryvdiuk
Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com
Hypoxia is one of the inductors of the expression of a large group of genes, which control glycolysis and proliferation processes in low oxygen conditions or as a result of low oxygen consumption. Moreover, hypoxia is one of the factors which induce the endoplasmic reticulum stress which, like hypoxia, is an obligatory component of malignant tumor growth and is connected with cytoplasm and nuclei through three sensor and signalling systems: PERK, ATF6 та ERN1. The suppression of ERN1, the main sensing and signalling enzyme of endoplasmic reticulum stress, leads to a decrease of tumor growth and changes the character of hypoxic regulation of many genes responsible for the control of proliferation and glycolysis. ERN1 sensing and signalling system controls the expression of a large set of genes, which are dependent on endoplasmic reticulum stress as well as hypoxia. Moreover, this signalling pathway is an important factor of malignant tumor growth.
Expression of phosphoribosyl pyrophosphate synthetase genes in U87 glioma cells with ERN1 knockdown: effect of hypoxia and endoplasmic reticulum stress
O. H. Minchenko, I. A. Garmash, O. V. Kovalevska,
D. O. Tsymbal, D. O. Minchenko
Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com
Activation of pentose phosphate pathway is an important factor of enhanced cell proliferation and tumor growth. Phosphoribosyl pyrophosphate synthetase (PRPS) is a key enzyme of this pathway and plays a central role in the synthesis of purines and pyrimidines. Hypoxia as well as ERN1 (from endoplasmic reticulum to nuclei-1) mediated endoplasmic reticulum stress response-signalling pathway is linked to the proliferation because the blockade of ERN1 suppresses tumor growth, including glioma. We studied the expression of different PRPS genes in glioma cells with ERN1 knockdown under hypoxic condition. It was shown that hypoxia decreases the expression of PRPS1 and PRPS2 genes in both types of glioma cells, being more pronounced in cells without ERN1 function, but PRPSAP1 and PRPSAP2 gene expressions are suppressed by hypoxia only in glioma cells with blockade of ERN1. Moreover, the blockade of endoribonuclease activity of ERN1 does not affect the expression of PRPS1 and PRPS2 as well as PPRS-associated protein genes in U87 glioma cells. At the same time, the induction of endoplasmic reticulum stress by tunicamycin in glioma cells with suppressed activity of ERN1 endoribonuclease decreases the expression level of PRPS1 and PRPS2 genes only. Results of this investigation clearly demonstrated that the expression of different genes encoding subunits of PRPS enzyme is affected by hypoxia in U87 glioma cells, but the effect of hypoxia is modified by suppression of endoplasmic reticulum stress signaling enzyme ERN1.
ERN1 knockdown modifies the hypoxic regulation of TP53, MDM2, USP7 and PERP gene expressions in U87 glioma cells
S. V. Danilovskyi1, D. O. Minchenko1,2, О. S. Moliavko1,
O. V. Kovalevska1, L. L. Karbovskyi1, O. H. Minchenko1
1Palladin Institute of Biochemistry National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bogomolets National Medical University, Kyiv, Ukraine
Endoplasmic reticulum stress and hypoxia are necessary components of malignant tumors growth and suppression of ERN1 (from endoplasmic reticulum to nuclei-1) signalling pathway, which is linked to the apoptosis and cell death processes, significantly decreases proliferative processes. Glioma cells with ERN1 knockdown were used in order to investigate the effect of ERN1 blockade on the expression of TP53, MDM2, PERP, and USP7 genes and its hypoxic regulation. We have studied the expression of TP53 (tumor protein 53), MDM2 (TP53 E3 ubiquitin protein ligase homolog), PERP (TP53 apoptosis effector), and USP7 (ubiquitin specific peptidase 7) genes, which are related to cell proliferation and apoptosis, in glioma cells with ERN1 knockdown under hypoxic condition. It was shown that blockade of ERN1 gene function in U87 glioma cells intensified the expression of TP53 and USP7 genes, but decreased the expression of MDM2 and PERP genes. Thus, an enhanced expression of TP53 gene in ERN1 knockdown glioma cells correlates with the decreased level of ubiquitin ligase MDM2 and increased expression level of USP7 which deubiquitinates TP53 and MDM2 and induces TP53-dependent cell growth repression and apoptosis. At the same time, the expression levels of TP53, MDM2, and USP7 genes do not change significantly in glioma cells with suppression of endoribonuclease activity only, but PERP gene expression is strongly increased. Moreover, the expression of TP53 and UPS7 genes is decreased in hypoxic conditions in control glioma cells only; however, MDM2 and PERP gene expressions are increased in both cell types, being more significant in ERN1 knockdown cells. Thus, the expression of genes encoding TP53 and related to TP53 factors depends upon the endoplasmic reticulum stress signaling as well as on hypoxia, and correlates with suppression of glioma growth under ERN1 knockdown.
Effect of hypoxia on the expression of CCN2, PLAU, PLAUR, SLURP1, PLAT and ITGB1 genes in ERN1 knockdown U87 glioma cells
O. H. Minchenko1, A. P. Kharkova1, K. I. Kubaichuk1,
D. O. Minchenko1,2, N. A. Hlushchak1, O. V. Kovalevska1
1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bogomolets National Medical University, Kyiv, Ukraine;
The endoplasmic reticulum stress is an important factor of tumor growth and is induced in cancer cells. We have studied the effect of ERN1 knockdown as well as hypoxia on the expression of genes encoding factors, which control cell proliferation, in U87 glioma cells. It was shown that the complete blockade of ERN1 enzyme function leads to an increase of the PLAT (tissue plasminogen activator), CCN2 (CCN family member 2), and ITGB1 (integrin β-1) as well as to a decrease of PLAU (plasminogen activator, urokinase), PLAUR (plasminogen activator, urokinase receptor), and SLURP1 (secreted LY6/PLAUR domain containing 1) mRNA expressions. Moreover, we have shown that hypoxia does not affect the expression level of ITGB1 mRNA, but increases that of CCN2, PLAUR, SLURP1, and PLAT mRNA and decreases the expression level of only PLAU mRNA in control glioma cells. At the same time, in ERN1 knockdown glioma cells the expression level of PLAU, PLAUR, and SLURP1 mRNA is decreased under hypoxia, but PLAT and ITGB1 mRNA expression levels are increased under these experimental conditions. Thus, results of this study have shown that the expression level of all studied genes is affected by ERN1 knockdown as well as by hypoxia and that the effect of hypoxia mostly depends on ERN1 signaling enzyme function.
Inhibition of ERN1 signaling enzyme affects hypoxic regulation of the expression of E2F8, EPAS1, HOXC6, ATF3, TBX3 and FOXF1 genes in U87 glioma cells
O. H. Minchenko1, D. O. Tsymbal1, D. O. Minchenko1,2,
O. V. Kovalevska1, L. L. Karbovskyi1, A. Bikfalvi3
1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: ominchenko@yahoo.com;
2Bogomolets National Medical University, Kyiv, Ukraine;
3INSERM U1029 Angiogenesis and Cancer Microenvironment Laboratory,
University Bordeaux 1, Talence, France
Hypoxia as well as the endoplasmic reticulum stress are important factors of malignant tumor growth and control of the expression of genes, which regulate numerous metabolic processes and cell proliferation. Furthermore, blockade of ERN1 (endoplasmic reticulum to nucleus 1) suppresses cell proliferation and tumor growth. We studied the effect of hypoxia on the expression of genes encoding the transcription factors such as E2F8 (E2F transcription factor 8), EPAS1 (endothelial PAS domain protein 1), TBX3 (T-box 3), ATF3 (activating transcription factor 3), FOXF1 (forkhead box F1), and HOXC6 (homeobox C6) in U87 glioma cells with and without ERN1 signaling enzyme function. We have established that hypoxia enhances the expression of HOXC6, E2F8, ATF3, and EPAS1 genes but does not change TBX3 and FOXF1 gene expression in glioma cells with ERN1 function. At the same time, the expression level of all studied genes is strongly decreased, except for TBX3 gene, in glioma cells without ERN1 function. Moreover, the inhibition of ERN1 signaling enzyme function significantly modifies the effect of hypoxia on the expression of these transcription factor genes: removes or introduces this regulation as well as changes a direction or magnitude of hypoxic regulation. Present study demonstrates that fine-tuning of the expression of proliferation related genes depends upon hypoxia and ERN1-mediated endoplasmic reticulum stress signaling and correlates with slower proliferation rate of glioma cells without ERN1 function.