前列腺癌是男性最常见的一种癌症。复发疾病患者最初会对去势素治疗有反应，但肿瘤最终会进展为去势抵抗性前列腺癌。因此，迫切需要针对当前治疗无效的PCa耐药性的新治疗方法。在这里，我们报道心脏苷类化合物neriifolin通过激活内质网应激（ERS）在前列腺癌中增加DNA损伤和凋亡，抑制癌细胞恶性程度。我们发现，心脏苷类化合物neriifolin显著抑制前列腺癌细胞的生长并诱导了细胞凋亡。转录组序列分析表明，neriifolin明显诱导DNA损伤和双链断裂，并验证了DSBs修复基因的表达下降以及增加的磷酸化组蛋白H2AX（γ-H2AX）斑点形成，这是DSBs的定量标志。此外，我们还发现neriifolin也激活了ERS，这表现为ERS相关蛋白如启动子eIF2α、蛋白酶R样内质网激酶（PERK）和C/EBP同源蛋白（CHOP）的上调表达和活化以及CCAAT增强子结合蛋白α（C/EBP-α）的下调，C/EBP-α是与CHOP形成异二聚体的转录因子。此外，neriifolin的治疗显著抑制了肿瘤生长，这些效果可以通过CHOP缺失或C/EBP-α的过表达在裸鼠中逆转。在机械学上，neriifolin通过ERS的CHOP-C/EBP-α信号轴增加DNA损伤和凋亡来抑制肿瘤生长。综上所述，这些结果表明心脏苷类化合物neriifolin可能是前列腺癌治疗中潜在的肿瘤特异性化疗药物。 版权所有©2023 Elsevier Inc.

Prostate cancer (PCa) is one of the most common cancers in men. Patients with recurrent disease initially respond to androgen-deprivation therapy, but the tumor eventually progresses into castration-resistant PCa. Thus, new therapeutic approaches for PCa resistance to current treatments are urgently needed. Here, we report that cardiac glycoside neriifolin suppresses the malignancy of cancer cells via increasing DNA damage and apoptosis through activation of endoplasmic reticulum stress (ERS) in prostate cancers. We found that cardiac glycoside neriifolin markedly inhibited the cell growth and induced apoptosis in prostate cancer cells. Transcriptome sequence analysis revealed that neriifolin significantly induced DNA damage and double strand breaks (DSBs), validated with attenuation expression of genes in DSBs repair and increasing phosphorylated histone H2AX (γ-H2AX) foci formation, a quantitative marker of DSBs. Moreover, we found that neriifolin also activated ERS, evidenced by upregulation and activation of ERS related proteins, including eukaryotic initiation factor 2α (eIF2α), protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) and C/EBP homologous protein (CHOP) as well as downregulation of CCAATenhancerbinding protein alpha (C/EBP-α), a transcriptional factor that forms heterodimers with CHOP. In addition, neriifolin treatment dramatically inhibited the by tumor growth, which were reversed by CHOP loss or overexpression of C/EBP-α in nude mice. Mechanistically, neriifolin suppressed the tumor growth by increasing DNA damage and apoptosis through CHOP-C/EBP-α signaling axis of ERS in prostate cancers. Taken together, these results suggest that cardiac glycoside neriifolin may be a potential tumor-specific chemotherapeutic agent in prostate cancer treatment.Copyright © 2023 Elsevier Inc. All rights reserved.