Department of Immunology, School of Medicine, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, Korea.
Department of Biochemistry, School of Medicine, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, Korea.
Molecules. 2018 Oct 24;23(11):2755. doi: 10.3390/molecules23112755.
We previously reported that PP242 (dual inhibitor of mTORC1/2) plus curcumin induced apoptotic cell death through lysosomal membrane permeabilization (LMP)-mediated autophagy. However, the relationship between ER stress and apoptotic cell death by combined PP242 and curcumin treatment remains unknown. In the present study, we found that combined PP242 and curcumin treatment induced cytosolic Ca release and ER stress. Interestingly, pretreatment with the chemical chaperones (TUDCA and 4-PBA) and knockdown of CHOP and ATF4 by siRNA did not abolish combined treatment-induced apoptosis in renal carcinoma cells. These results suggest that combined treatment with mTORC1/2 inhibitor and curcumin induces ER stress which is not essential for apoptotic cell death. Furthermore, overexpression of HSP70 significantly inhibited PP242 plus curcumin-induced LMP and apoptosis, but the protective effect was abolished by K77R mutation of acetylation site of HSP70. Taken together, our results reveal that regulation of HSP70 through K77 acetylation plays role in combined PP242 and curcumin treatment-induced apoptosis.
我们之前报道过，PP242（mTORC1/2 的双重抑制剂）联合姜黄素通过溶酶体膜通透性（LMP）介导的自噬诱导细胞凋亡。然而，联合使用 PP242 和姜黄素治疗时 ER 应激与细胞凋亡之间的关系尚不清楚。在本研究中，我们发现联合使用 PP242 和姜黄素处理会诱导细胞质 Ca 释放和 ER 应激。有趣的是，用化学伴侣（TUDCA 和 4-PBA）预处理和 siRNA 敲低 CHOP 和 ATF4 并不能消除联合处理诱导的肾癌细胞凋亡。这些结果表明，mTORC1/2 抑制剂和姜黄素的联合治疗会诱导 ER 应激，但这对于细胞凋亡不是必需的。此外，HSP70 的过表达显著抑制了 PP242 联合姜黄素诱导的 LMP 和凋亡，但 HSP70 乙酰化位点 K77R 突变消除了这种保护作用。总之，我们的结果表明，通过 K77 乙酰化调节 HSP70 在 PP242 联合姜黄素治疗诱导的凋亡中发挥作用。
