Perez-Stable Carlos, de Las Pozas Alicia, Reiner Teresita, Gomez Jose, Nagarajan Manojavan, Foster Robert T, Ure Daren R, Wangpaichitr Medhi
Research Service, Bruce W. Carter Veterans Affairs Medical Center, Miami, FL 33125, USA.
South Florida VA Foundation for Research and Education, Miami, FL 33125, USA.
Int J Mol Sci. 2025 Jul 12;26(14):6699. doi: 10.3390/ijms26146699.
Inhibitors of the ubiquitin-proteasome system increase proteotoxic stress and have achieved clinical success for multiple myeloma but not for solid cancers such as hepatocellular carcinoma. Our objective is to identify a combination with proteasome inhibitors that enhances proteotoxic stress and apoptotic cell death in hepatocellular carcinoma but with less toxicity to non-cancer cells. We found that rencofilstat, a pan-cyclophilin inhibitor, combined with ixazomib, a proteasome inhibitor, increased apoptotic cell death in hepatocellular carcinoma but not in umbilical vein or dermal fibroblast non-cancer cells. We then analyzed the effects of rencofilstat + ixazomib on XBP1s and PERK, critical factors in the unfolded protein response used by cells to survive proteotoxic stress. Rencofilstat + ixazomib maintained higher expression of XBP1s and genetic models suggested that XBP1s was a pro-survival protein early and pro-death protein at later times. Simultaneously, decreased PERK expression prevented the block in protein synthesis via phospho-eIF2α and likely further amplified proteotoxic stress. Rencofilstat + ixazomib did not have effects on XBP1s or PERK in non-cancer cells. Further genetic experiments revealed the pro-survival roles for cyclophilin A and B in mediating rencofilstat + ixazomib-induced cell death. In the Hep3B xenograft model, rencofilstat + ixazomib significantly inhibited tumor volumes/weights without general toxicity. We conclude that rencofilstat + ixazomib amplified proteotoxic stress in hepatocellular carcinoma past a threshold pro-survival pathways could not tolerate, whereas non-cancer cells were less affected.
泛素 - 蛋白酶体系统抑制剂会增加蛋白质毒性应激，在多发性骨髓瘤治疗中已取得临床成功，但对肝细胞癌等实体癌无效。我们的目标是找到一种与蛋白酶体抑制剂的组合，能增强肝细胞癌中的蛋白质毒性应激和凋亡性细胞死亡，同时对非癌细胞的毒性较小。我们发现，泛亲环素抑制剂伦考非司他与蛋白酶体抑制剂伊沙佐米联合使用时，可增加肝细胞癌中的凋亡性细胞死亡，但对脐静脉或真皮成纤维细胞等非癌细胞无此作用。然后，我们分析了伦考非司他 + 伊沙佐米对XBP1s和PERK的影响，这两个是细胞用于在蛋白质毒性应激中存活的未折叠蛋白反应的关键因子。伦考非司他 + 伊沙佐米维持了XBP1s的较高表达，基因模型表明XBP1s早期是促生存蛋白，后期是促死亡蛋白。同时，PERK表达降低阻止了通过磷酸化eIF2α导致的蛋白质合成阻滞，可能进一步放大了蛋白质毒性应激。伦考非司他 + 伊沙佐米对非癌细胞中的XBP1s或PERK没有影响。进一步的基因实验揭示了亲环素A和B在介导伦考非司他 + 伊沙佐米诱导的细胞死亡中的促生存作用。在Hep3B异种移植模型中，伦考非司他 + 伊沙佐米显著抑制肿瘤体积/重量，且无全身毒性。我们得出结论，伦考非司他 + 伊沙佐米在肝细胞癌中放大了蛋白质毒性应激，超过了促生存途径无法耐受的阈值，而非癌细胞受影响较小。
