Bettaieb Ahmed, Averill-Bates Diana A
Département des sciences biologiques, TOXEN, Université du Québec à Montréal, CP 8888, Succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada.
Département des sciences biologiques, TOXEN, Université du Québec à Montréal, CP 8888, Succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada.
Biochim Biophys Acta. 2015 Jan;1853(1):52-62. doi: 10.1016/j.bbamcr.2014.09.016. Epub 2014 Sep 26.
Hyperthermia (39-45°C) has emerged as an alternate prospect for cancer therapy in combination with radiation and chemotherapy. Despite promising progress in the clinic, molecular mechanisms involved in hyperthermia-induced cell death are not clear. Hyperthermia causes protein denaturation/aggregation, which results in cell death by apoptosis and/or necrosis. Hyperthermia also induces thermotolerance, which renders cells resistant to subsequent exposure to lethal heat shock. This study investigates the role of both lethal (42-43°C) and mild (40°C) hyperthermia in regulating ER stress and ER stress-induced apoptosis in HeLa cells. The ability of mild thermotolerance induced at 40°C to alleviate either or both of these processes is also determined. Hyperthermia (42-43°C) induced ER stress, revealed by phosphorylation of PERK, eIF2α and IRE1α, cleavage of ATF6 and increased expression of BiP and sXBP1. Real-time PCR revealed that mRNA levels of ATF6, ATF4, BiP, sXBP1 and CHOP increased in cells exposed to hyperthermia. Moreover, hyperthermia caused disruption of calcium homeostasis and activated the calpain-calpastatin proteolytic system and ER resident caspase 4. Pre-exposure to mild hyperthermia (40°C) alleviated the induction of cytotoxicity and ER stress by hyperthermia (42-43°C) and protected cells against ER stress-induced apoptosis. ShRNA-mediated depletion of Hsp72 abrogated protective effects of mild thermotolerance (40°C) against heat-shock induced ER stress and sensitized cells to ER stress-mediated apoptosis. Our findings show that Hsp72 contributes to the protective effects of mild hyperthermia (40°C) against hyperthermia-induced ER stress and apoptosis.
热疗（39 - 45°C）已成为与放疗和化疗联合使用的癌症治疗替代方案。尽管在临床方面取得了令人鼓舞的进展，但热疗诱导细胞死亡所涉及的分子机制尚不清楚。热疗会导致蛋白质变性/聚集，进而通过凋亡和/或坏死导致细胞死亡。热疗还会诱导热耐受性，使细胞对随后的致死性热休克产生抗性。本研究调查了致死性热疗（42 - 43°C）和轻度热疗（40°C）在调节HeLa细胞内质网应激（ER应激）及ER应激诱导的凋亡中的作用。同时还确定了40°C诱导的轻度热耐受性减轻这些过程中一个或两个过程的能力。热疗（42 - 43°C）诱导了ER应激，表现为PERK、eIF2α和IRE1α的磷酸化、ATF6的裂解以及BiP和sXBP1表达的增加。实时PCR显示，暴露于热疗的细胞中ATF6、ATF4、BiP、sXBP1和CHOP的mRNA水平升高。此外，热疗导致钙稳态破坏，并激活了钙蛋白酶 - 钙蛋白酶抑制蛋白水解系统和内质网驻留半胱天冬酶4。预先暴露于轻度热疗（40°C）可减轻热疗（42 - 43°C）诱导的细胞毒性和ER应激，并保护细胞免受ER应激诱导的凋亡。通过短发夹RNA（shRNA）介导的Hsp72缺失消除了轻度热耐受性（40°C）对热休克诱导的ER应激的保护作用，并使细胞对ER应激介导的凋亡敏感。我们的研究结果表明，Hsp72有助于轻度热疗（40°C）对热疗诱导的ER应激和凋亡的保护作用。
