Dilshara Matharage Gayani, Jeong Jin-Woo, Prasad Tharanga Jayasooriya Rajapaksha Gedara, Neelaka Molagoda Ilandarage Menu, Lee Seungheon, Park Sang Rul, Choi Yung Hyun, Kim Gi-Young
Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea.
Anti-Aging Research Center, Dongeui University, Busan 47227, Republic of Korea.
Biochem Biophys Res Commun. 2017 Apr 1;485(2):440-445. doi: 10.1016/j.bbrc.2017.02.059. Epub 2017 Feb 13.
Tumor cell metabolism is a promising target for various cancer treatments. Apart from aerobic glycolysis, cancer cell growth is dependent on glutamine (Gln) supply, leading to their survival and differentiation. Therefore, we examined whether treatment with TNF-related apoptosis-inducing ligand (TRAIL) sensitizes MDA-MB-231 cells to apoptosis under Gln deprivation condition (TRAIL/Gln deprivation). Gln deprivation decreased cell proliferation as expected, but did not induce remarkable cell death. TRAIL/Gln deprivation, however, significantly increased growth inhibition and morphological shrinkage of MDA-MB-231 cells compared to those induced by treatment with either Gln deprivation or TRAIL alone. Moreover, TRAIL/Gln deprivation upregulated the apoptotic sub-G phase accompanied with a remarkable decrease of pro-caspase-3, pro-caspase-9, and anti-apoptotic xIAP, and Bcl-2. Increased cleavage of PARP and pro-apoptotic Bid protein expression suggests that TRAIL/Gln deprivation triggers mitochondrion-mediated apoptosis in MDA-MB-231 cells. Additionally, TRAIL/Gln deprivation upregulated the expression of endoplasmic reticulum (ER) stress markers such as ATF4 and phosphorylated eIF2α, thereby enhancing the C/EBP homologous protein (CHOP) protein level. Transient knockdown of CHOP partically reversed TRAIL/Gln deprivation-mediated apoptosis. Accordingly, TRAIL/Gln deprivation enhanced the expression of death receptor 5 (DR5) and transient knockdown of DR5 completely restored TRAIL/Gln deprivation-mediated apoptosis. Taken together, our results suggest that Gln deprivation conditions can be used for the development of new therapies for TRAIL-resistant cancers.
肿瘤细胞代谢是各种癌症治疗的一个有前景的靶点。除了有氧糖酵解外，癌细胞的生长依赖于谷氨酰胺（Gln）的供应，这使其得以存活和分化。因此，我们研究了在谷氨酰胺剥夺条件下（TRAIL/谷氨酰胺剥夺），肿瘤坏死因子相关凋亡诱导配体（TRAIL）处理是否会使MDA-MB-231细胞对凋亡敏感。如预期的那样，谷氨酰胺剥夺降低了细胞增殖，但并未诱导明显的细胞死亡。然而，与单独的谷氨酰胺剥夺或TRAIL处理相比，TRAIL/谷氨酰胺剥夺显著增加了MDA-MB-231细胞的生长抑制和形态萎缩。此外，TRAIL/谷氨酰胺剥夺上调了凋亡亚G期，同时伴有原半胱天冬酶-3、原半胱天冬酶-9以及抗凋亡蛋白XIAP和Bcl-2的显著减少。PARP切割增加和促凋亡蛋白Bid表达增加表明，TRAIL/谷氨酰胺剥夺触发了MDA-MB-231细胞中线粒体介导的凋亡。此外，TRAIL/谷氨酰胺剥夺上调了内质网（ER）应激标志物如ATF4和磷酸化eIF2α的表达，从而提高了C/EBP同源蛋白（CHOP）的蛋白水平。CHOP的瞬时敲低部分逆转了TRAIL/谷氨酰胺剥夺介导的凋亡。因此，TRAIL/谷氨酰胺剥夺增强了死亡受体5（DR5）的表达，而DR5的瞬时敲低完全恢复了TRAIL/谷氨酰胺剥夺介导的凋亡。综上所述，我们的结果表明，谷氨酰胺剥夺条件可用于开发针对TRAIL耐药癌症的新疗法。
