RESUMO
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 ß-1) as well as to a decrease ofPLAU (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.
Assuntos
Proliferação de Células/genética , Estresse do Retículo Endoplasmático/genética , Endorribonucleases/genética , Regulação da Expressão Gênica , Proteínas Serina-Treonina Quinases/genética , RNA Mensageiro/genética , Hipóxia Celular/genética , Linhagem Celular Tumoral , Técnicas de Silenciamento de Genes , Humanos , Microscopia de Contraste de FaseRESUMO
The endoplasmic reticulum is a dynamic intracellular organelle with exquisite sensitivity to alterations in homeostasis, and provides stringent quality control systems to ensure that the only correctly folded proteins transit to the Golgi and unfolded or misfolded proteins are retained and ultimately degraded. The endoplasmic reticulum stress represents the unfolded protein response to cope with the accumulation of unfolded or misfolded proteins and is required to maintain the functional integrity of the endoplasmic reticulum. The endoplasmic reticulum stress is a fundamental phenomenon which provides a secure protection of the cells from different factors. This stress provides a wide spectrum of physiological roles in diverse developmental and metabolic processes, especially for professional secretory cells with high-level secretory protein synthesis, such as pancreatic beta cells, hepatocytes and osteoblasts and is required throughout the entire life. The endoplasmic reticulum stress and hypoxia are the obligate components of malignant tumor growth, are interconnected and activate angiogenesis via growth and metabolism control. The endoplasmic reticulum stress is mediated by three by three sensor and signaling pathways (PERK, ATF6 and ERN1), besides that blockade one (ERN1) leads to a decrease of tumor growth through suppression of angiogenesis and proliferation. The data concerning the interaction of signaling enzyme ERN1 and pro- and anti-angiogenic gene expressions is analyzed.
