自噬溶酶体异常与癌症的恶性进展相关。转录因子EB（TFEB）是自噬-溶酶体机制的主要转录调节因子，其异常活性与自噬-溶酶体功能障碍有关。重楼素II（PPII）是从重楼根茎中分离出来的一种活性甾体皂苷，已被证明具有抗肿瘤活性。在此，我们探讨了PPII在乳腺癌（BC）中的抗肿瘤活性，并进一步阐明了其机制。检测到自噬体通过透射电子显微镜、自噬指示系统和蛋白质印迹。通过流式细胞术、溶酶体组织蛋白酶活性测定和吖啶橙染色评估 PPII 对溶酶体活性的影响。通过蛋白质印迹、基因表达测量、基因改变评估PPII对信号通路的影响。通过药物亲和力响应靶稳定性测定来检查 PPII 和 MOB1 的结合。在 Sprague-Dawley 大鼠中评估了 PPII 的药代动力学参数。PPII 通过诱导自噬体的积累在 BC 中表现出治疗潜力。 PPII 促进 YAP/TFEB 的细胞质滞留，这负责自噬体在 BC 中的积累。 PPII 激活 Hippo 信号传导以促进 YAP 的细胞质保留。 PPII 通过直接结合相互作用加速 MOB1 的乙酰化，从而激活 Hippo 信号传导。总之，这些结果证实 MOB1 的乙酰化通过促进 YAP/TFEB 共激活剂复合物的细胞质保留来介导 PPII 诱导的 BC 中自噬体积累。 PPII 有望成为基于溶酶体生物合成治疗 BC 的候选药物。版权所有 © 2023。由 Elsevier GmbH 出版。

Autophagy‒lysosome abnormalities are associated with the malignant progression of cancer. Transcription factor EB (TFEB) is the master transcriptional regulator of the autophagy‒lysosome machinery, and its abnormal activity is associated with autophagy-lysosome dysfunction. Polyphyllin II (PPII), an active steroidal saponin isolated from the rhizomes of Paris polyphylla, has been demonstrated to have antitumor activity.Here, we explored the antitumor activity of PPII in breast cancer (BC) and further clarified its mechanism.Autophagosome was detected by transmission electron microscopy, an autophagy indicator system, and western blot. The effect of PPII on lysosomal activity was evaluated by flow cytometry, a lysosomal cathepsin activity assay, and acridine orange staining. The effect of PPII on the signaling pathway was evaluated by Western blot, gene expression measurement, gene alterations. The binding of PPII and MOB1 was examined through a drug affinity responsive target stability assay. The pharmacokinetic parameters of PPII were evaluated in Sprague-Dawley rats.PPII exhibits therapeutic potential in BC by inducing the accumulation of autophagosome. PPII promotes the cytoplasmic retention of YAP/TFEB, which is responsible for the accumulation of autophagosome in BC. PPII activates Hippo signaling to promote cytoplasmic retention of YAP. PPII activates Hippo signaling by accelerating acetylation of MOB1 through a direct binding interaction.Taken together, these results confirm that acetylation of MOB1 mediates PPII-induced autophagosome accumulation in BC by promoting cytoplasmic retention of the YAP/TFEB coactivator complex. PPII is expected to be a drug candidate for the treatment of BC based on lysosomal biosynthesis.Copyright © 2023. Published by Elsevier GmbH.