DataSheet1_PPM-18, an Analog of Vitamin K, Induces Autophagy and Apoptosis in Bladder Cancer Cells Through ROS and AMPK Signaling Pathways.docx

PPM-18, identified as a novel analog of vitamin K, has been reported to play a critical role in the suppression of seizures. However, the concerns that whether PPM-18, like vitamin K, exerts anticancer activity remain to be further investigated. Here, we found that PPM-18 remarkably suppressed the proliferation and induced apoptosis in bladder cancer cells. Furthermore, a significant autophagic effect of PPM-18 on bladder cancer cells was also demonstrated, which profoundly promoted apoptotic cell death. Mechanistically, PPM-18 activated AMP-activated protein kinase (AMPK), whereas it repressed PI3K/AKT and mTORC1 pathways in bladder cancer cells. Inhibition of AMPK markedly relieved PPM-18–induced autophagy and apoptosis, indicating that PPM-18 is able to induce autophagy and apoptosis in bladder cancer cells via AMPK activation. Moreover, reactive oxygen species (ROS) were notably accumulated in PPM-18–treated bladder cancer cells, and treatment with ROS scavengers not only eliminated ROS production but also abrogated AMPK activation, which eventually rescued bladder cancer cells from PPM-18–triggered autophagy and apoptotic cell death. In bladder cancer xenografts, the anticancer activities of PPM-18, including suppressing the growth of tumors and inducing autophagy and apoptosis in tumor cells, were also established. Collectively, this study was the first to demonstrate the anticancer effect of PPM-18 on bladder cancer cells in vitro and in vivo through eliciting autophagy and apoptosis via ROS and AMPK pathways, which might provide new insights into the potential utilization of PPM-18 for future bladder cancer treatment.

PPM-18作为一种新型维生素K类似物，此前已有研究报道其在癫痫发作抑制中发挥关键作用。然而，PPM-18是否如维生素K一般具备抗癌活性，这一问题仍有待进一步探究。本研究发现，PPM-18可显著抑制膀胱癌细胞的增殖并诱导其凋亡。此外，本研究还证实PPM-18对膀胱癌细胞具有显著的自噬诱导效应，该效应可进一步促进细胞凋亡的发生。机制层面，PPM-18可激活腺苷酸活化蛋白激酶（AMP-activated protein kinase, AMPK），同时抑制膀胱癌细胞内的磷脂酰肌醇3-激酶/蛋白激酶B（PI3K/AKT）及雷帕霉素靶蛋白复合物1（mTORC1）信号通路。抑制AMPK可显著缓解PPM-18诱导的自噬与凋亡，这表明PPM-18可通过激活AMPK通路诱导膀胱癌细胞发生自噬与凋亡。此外，经PPM-18处理的膀胱癌细胞中活性氧（reactive oxygen species, ROS）显著蓄积；使用ROS清除剂不仅可消除ROS的产生，还能阻断AMPK的激活，最终使膀胱癌细胞免于PPM-18引发的自噬与凋亡性死亡。在膀胱癌细胞异种移植瘤模型中，PPM-18的抗癌活性同样得到验证，具体表现为抑制肿瘤生长以及诱导肿瘤细胞发生自噬与凋亡。综上，本研究首次证实PPM-18可通过激活ROS及AMPK通路诱导膀胱癌细胞发生自噬与凋亡，从而在体内外发挥抗癌作用，该发现可为PPM-18未来应用于膀胱癌治疗提供全新的理论参考与研究思路。