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Hypoxia is one of powerful inducers of expression of a large group of genes, including genes which control glycolysis, angiogenesis and proliferation supportingcell surviving at low oxygen condition. However, in tumor cells hypoxia was observed at normal oxygen tension condition as a result of its decreased utilization. Moreover, hypoxia is an obligate component of malignant tumor growth and substantially controls glycolysis, angiogenesis and proliferation processes. Data concerning molecular mechanisms of activation of hypoxia inducible transcription factor HIF in cells at hypoxia and in malignant tumors, as well as its role of in the regulation of gene expressions have been analyzed. The mechanisms of interaction of the transcription factor HIF with specific hypoxic regulatory elements in the promoter region of genes activated by hypoxia were examined.

The angiogenesis is an important component of tumor growth and tightly associated with hypoxia. The expression level of genes related to regulation of angiogenesis (BAI2, SPARC, TIMP1, TIMP2, TIMP3, TIMP4, THBS1, THBS2, ADAMTS5 and FGF2) in glioma U87cells and cells with suppressed function of signaling enzyme ERN1, a major mediator of the endoplasmic reticulum stress by qPCR, was studied. We have shown that the expression of genes encoding BAI2, SPARC, TIMP2, TIMP3, THBS1 and THBS2 is strongly increased in glioma cells with ERN1 signaling enzyme loss of function, being more intense for TIMP2, TIMP3 and THBS1 genes. At the same time, the expression of genes encoding TIMP1, TIMP4, ADAMTS5 and FGF2 is significantly decreased with more strong effect for ADAMTS5 and TIMP4 genes. At hypoxia, the expression of most of studied genes in both glioma cell types is affected. Hypoxia induced the expression of TIMP1, TIMP3 and ADAMTS5 genes both in control glioma cells and cells with ERN1 enzyme loss of function. However, the effect of hypoxia towards TIMP2 gene expression was observed only in control glioma cells. At the same time, the expression of genes encoding BAI2, SPARC, THBS1, THBS2, ADAMTS5 and FGF2 is decreased under hypoxia action, but its expression mostly depended on ERN1 signaling enzyme function. The results of this study provide strong evidence that suppression of ERN1 signaling enzyme function, as well as hypoxia, changes the expression of genes related to regulation of angiogenesis in glioma cells. It is possible that changes in the expression of these genes contribute to the suppression of glioma cells’ proliferation by blockade of ERN1 signaling enzyme functioning.

Accumulating evidence raises the hypothesis that dysregulation of different intrinsic mechanisms which control most metabolic processes are involved in the development of obesity, metabolic syndrome and type 2 diabetes mellitus, the most profound public health problems. Angiogenesis is an important component of different proliferative processes, in particular, fat tissue growth. Moreover, dysregulation of molecular components of the angiogenesis system can contributes to the development of diabetic complications. We have studied the expression levels of genes related to regulation of angiogenesis (TIMP1, TIMP2, TIMP3, TIMP4, THBS1, THBS2, THBS3, ADAMTS5, LUM, DCN, IL6 and ZEB1) in subcutaneous adipose tissue of obese individuals as well as obese patients with impaired glucose tolerance (prediabetic) and type 2 diabetes using real-time quantitative PCR. We have shown that the expression level of most of these genes with anti-angiogenic properties significantly increases in subcutaneous adipose tissue of obese individuals versus lean patients, being more intense for TIMP1, TIMP2, THBS2 and LUM genes. Increased expression level of TIMP1, TIMP2, TIMP3, ADAMTS5 as well as THBS1 and THBS2 in adipose tissue was found in obese patients with impaired glucose tolerance. At the same time, expression of genes which encode for TIMP1 and TIMP2 strongly decreased in adipose tissue of obese individuals with type 2 diabetes versus subjects with glucose intolerance. Results of this study provide strong evidence that expression of genes mostly related to suppression of angiogenesis is dysregulated in adipose tissue of obese individuals as well as in obese patients with glucose intolerance and type 2 diabetes. It is possible that these changes in the expression of TIMP and THBS genes in adipose tissue in obesity as well as in obese individuals with impaired glucose tolerance and type 2 diabetes can contribute to fat tissue storage, insulin resistance and the development of diabetic complications.

The main molecular components of circadian clock system are proteins which play a significant role in the control of both metabolism and malignant tumor growth. Endoplasmic reticulum stress as well as hypoxia and ischemia are important factors for tumor neovascularization and growth. We have studied the expression of circadian genes in the glioma cell line U87 under knockdown of endoplasmic reticulum–nuclei-1 (ERN1) sensing and signaling enzyme. It was shown that blockade of ERN1 leads to increase in the expression levels of PER1, PER3 and CLOCK mRNA; but the CRY1, PER2, BMAL1, BMAL2 and DEC2 mRNA levels are decreased. Moreover, the expression levels of most of the studied genes are increased under glucose or glutamine deprivation conditions both in control and ERN1-deficient glioma cells; however knockdown of ERN1 modifies the effect of these ischemic conditions. Hypoxia has different effects on the expression levels of circadian genes and these effects are dependent on ERN1 function. Hypoxia induces the expression of PER1, BMAL1 and DEC2 and decreased – PER3, CLOCK, CRY1 and BMAL2 mRNA in control glioma cells, while in genetically modified cells it induces the expression of BMAL1 mRNA only. Thus, the expression of circadian genes is dependent on ERN1 signaling enzyme function in normal, hypoxic and ischaemic conditions.

Most of physiological and biochemical processes in living organisms have circa­dian character. Disturbance of the regulation of circadian processes leads to developing different pathological processes and cancer, in particular. In this work, we have studied the effect of silver nanoparticles on the expression of very important regulatory genes which control the circadian processes: Per1, Clock and BMal1. We have shown that the level of Per1 expression significantly increased in the liver and lung but decreased in the testes. The level of Clock mRNA expression also increased in liver and lung but decreased in kidney. The Clock mRNA expression in testis and heart was observed at late period of silver nanoparticles action. Thus, the expression of Per1, Clock and BMal1 mRNA significantly changed in tissue specific manner in rats treated with silver nanoparticles. Disturbance of these genes expression can destroy cellular signal pathways and leads to developing pathological processes. The results of our investigation clearly demonstrated that silver nanoparticles have significant effect on the regulatory mechanisms which control cell metabolism via circadian gene expression. Expression of circadian genes can be a sensitive test for the detection of silver nanoparticles action on the organisms.