Biosafety Research Institute, College of Veterinary Medicine, Jeonbuk National University, Iksan, Jeonbuk 54596, Republic of Korea.
Oncol Rep. 2021 Jul;46(1). doi: 10.3892/or.2021.8095. Epub 2021 Jun 3.
Tumor necrosis factor‑related apoptosis‑inducing ligand (TRAIL) is a cytokine with the potential to induce cancer cell‑specific apoptosis with minimal toxicity to normal cells. Therefore, the resistance of certain cancer cells to TRAIL is a major concern and agents that can either enhance TRAIL capabilities or overcome TRAIL resistance are necessary for the development of cancer treatments. The present study investigated whether the antidepressant drug amitriptyline could sensitize TRAIL‑resistant A549 lung cancer cells and enhance TRAIL‑induced apoptosis. Antidepressants are usually prescribed to cancer patients to relieve emotional distress, such as depression or dysthymia. The present study revealed for the first time, to the best of our knowledge, that amitriptyline increased death receptor (DR) 4 and 5 expression, a requirement for TRAIL‑induced cell death. Genetic inhibitors of DR4 and DR5 significantly reduced amitriptyline‑enhanced TRAIL‑mediated apoptosis. Additionally, the present study explored whether blocking autophagy increased DR4 and DR5 expression. Blocking autophagy flux with the final stage autophagy inhibitor chloroquine (CQ) also upregulated DR4 and DR5 expression. TRAIL in combination with amitriptyline or CQ significantly increased the expression of apoptosis‑indicator proteins cleaved caspase‑8 and caspase‑3. The expression levels of LC3‑II and p62 were significantly higher in amitriptyline‑treated cells, which confirmed that amitriptyline blocks autophagy by inhibiting the fusion of autophagosomes with lysosomes. Overall, the present results contributed to understanding the mechanism responsible for the synergistic anticancer effect of amitriptyline and TRAIL and also presented a novel mechanism involved in DR4 and DR5 upregulation.
肿瘤坏死因子相关凋亡诱导配体（TRAIL）是一种细胞因子，具有诱导癌细胞特异性凋亡的潜力，而对正常细胞的毒性最小。因此，某些癌细胞对 TRAIL 的抵抗是一个主要问题，需要能够增强 TRAIL 能力或克服 TRAIL 抵抗的药物来开发癌症治疗方法。本研究探讨了抗抑郁药阿米替林是否可以使 TRAIL 耐药的 A549 肺癌细胞敏感并增强 TRAIL 诱导的细胞凋亡。抗抑郁药通常开给癌症患者以缓解情绪困扰，如抑郁或心境恶劣。本研究首次揭示，据我们所知，阿米替林增加了死亡受体（DR）4 和 5 的表达，这是 TRAIL 诱导细胞死亡的要求。DR4 和 DR5 的基因抑制剂显著降低了阿米替林增强的 TRAIL 介导的细胞凋亡。此外，本研究还探讨了阻断自噬是否会增加 DR4 和 DR5 的表达。用终末自噬抑制剂氯喹（CQ）阻断自噬流也上调了 DR4 和 DR5 的表达。TRAIL 联合阿米替林或 CQ 显著增加了凋亡标志物蛋白 cleaved caspase-8 和 caspase-3 的表达。阿米替林处理的细胞中 LC3-II 和 p62 的表达水平显著升高，这证实了阿米替林通过抑制自噬体与溶酶体的融合来阻断自噬。总的来说，本研究结果有助于理解阿米替林和 TRAIL 协同抗癌作用的机制，并提出了一种涉及 DR4 和 DR5 上调的新机制。
