Laboratory Medicine Center, Department of Clinical Laboratory, Zhejiang Provincial People's Hospital(Affiliated People's Hospital), Hangzhou Medical College, Hangzhou, Zhejiang, China; Department of Central Laboratory, Affiliated Hangzhou First People's Hospital, School of Medicine, Westlake University, Hangzhou, Zhejiang, China.
Department of Central Laboratory, Affiliated Hangzhou First People's Hospital, School of Medicine, Westlake University, Hangzhou, Zhejiang, China.
Redox Biol. 2024 Feb;69:103007. doi: 10.1016/j.redox.2023.103007. Epub 2023 Dec 19.
Hepatocellular carcinoma (HCC) is one of the most prevalent malignant tumors and the fourth leading cause of cancer-related death globally, which is characterized by complicated pathophysiology, high recurrence rate, and poor prognosis. Our previous study has demonstrated that disulfiram (DSF)/Cu could be repurposed for the treatment of HCC by inducing ferroptosis. However, the effectiveness of DSF/Cu may be compromised by compensatory mechanisms that weaken its sensitivity. The mechanisms underlying these compensatory responses are currently unknown. Herein, we found DSF/Cu induces endoplasmic reticulum stress with disrupted ER structures, increased Ca level and activated expression of ATF4. Further studies verified that DSF/Cu induces both ferroptosis and cuproptosis, accompanied by the depletion of GSH, elevation of lipid peroxides, and compensatory increase of xCT. Comparing ferroptosis and cuproptosis, it is interesting to note that GSH acts at the crossing point of the regulation network and therefore, we hypothesized that compensatory elevation of xCT may be a key aspect of the therapeutic target. Mechanically, knockdown of ATF4 facilitated the DSF/Cu-induced cell death and exacerbated the generation of lipid peroxides under the challenge of DSF/Cu. However, ATF4 knockdown was unable to block the compensatory elevation of xCT and the GSH reduction. Notably, we found that DSF/Cu induced the accumulation of ubiquitinated proteins, promoted the half-life of xCT protein, and dramatically dampened the ubiquitination-proteasome mediated degradation of xCT. Moreover, both pharmacologically and genetically suppressing xCT exacerbated DSF/Cu-induced cell death. In conclusion, the current work provides an in-depth study of the mechanism of DSF/Cu-induced cell death and describes a framework for the further understanding of the crosstalk between ferroptosis and cuproptosis. Inhibiting the compensatory increase of xCT renders HCC cells more susceptible to DSF/Cu, which may provide a promising synergistic strategy to sensitize tumor therapy and overcome drug resistance, as it activates different programmed cell death.
肝细胞癌（HCC）是最常见的恶性肿瘤之一，也是全球癌症相关死亡的第四大主要原因，其特点是病理生理学复杂、复发率高、预后差。我们之前的研究表明，双硫仑（DSF）/铜可以通过诱导铁死亡被重新用于治疗 HCC。然而，DSF/Cu 的有效性可能会因削弱其敏感性的代偿机制而受到影响。这些代偿反应的机制目前尚不清楚。在此，我们发现 DSF/Cu 诱导内质网应激，导致内质网结构破坏、Ca 水平升高和 ATF4 激活表达。进一步的研究证实，DSF/Cu 诱导铁死亡和铜死亡，同时伴随着 GSH 的耗竭、脂质过氧化物的增加以及 xCT 的代偿性增加。比较铁死亡和铜死亡，有趣的是，GSH 作用于调控网络的交汇点，因此，我们假设 xCT 的代偿性增加可能是治疗靶点的一个关键方面。从机制上讲，敲低 ATF4 促进了 DSF/Cu 诱导的细胞死亡，并在 DSF/Cu 的挑战下加剧了脂质过氧化物的产生。然而，ATF4 的敲低不能阻断 xCT 的代偿性增加和 GSH 的减少。值得注意的是，我们发现 DSF/Cu 诱导了泛素化蛋白的积累，促进了 xCT 蛋白的半衰期，并显著抑制了 xCT 的泛素化蛋白酶体介导的降解。此外，无论是药理学还是遗传学上抑制 xCT 都加剧了 DSF/Cu 诱导的细胞死亡。总之，本研究深入探讨了 DSF/Cu 诱导细胞死亡的机制，并描述了一个框架，以进一步理解铁死亡和铜死亡之间的串扰。抑制 xCT 的代偿性增加使 HCC 细胞对 DSF/Cu 更为敏感，这可能为增强肿瘤治疗敏感性和克服耐药性提供一种有前途的协同策略，因为它激活了不同的程序性细胞死亡。
