Abstract

Betulinic acid (BA), a naturally occurring lupane-type triterpenoid, possesses a wide range of potential activities against different types of cancer. However, the molecular mechanisms involved in anti-cervical cancer about BA were rarely investigated. Herein, the role of BA in cervical cancer suppression by ROS-mediated endoplasmic reticulum stress (ERS) and autophagy was deeply discussed. The findings revealed that BA activated Keap1/Nrf2 pathway and triggered mitochondria-dependent apoptosis due to ROS production. Furthermore, BA increased the intracellular Ca²⁺ levels, inhibited the expression of Beclin1 and promoted the expression of GRP78, LC3-II, and p62 associated with ERS and autophagy. Besides, BA initiated the formation of autophagosomes and inhibited autophagic flux by the co-administration of BA with 3-methyladenine (3-MA) and chloroquine (CQ), respectively. The in vivo experiment manifested that hydroxychloroquine (HCQ) enhanced the apoptosis induced by BA. For the first time, we demonstrated that BA could initiate early autophagy, inhibit autophagy flux, and induce protective autophagy in HeLa cells. Thus, BA could be a potential chemotherapy drug for cervical cancer, and inhibition of autophagy could enhance the anti-tumor effect of BA. However, the interactions of signaling factors between ERS-mediated and autophagy-mediated apoptosis deserve further attention.

Graphical abstract

中文翻译：

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桦木酸在体外和体内通过ROS依赖性内质网应激和自噬诱导HeLa细胞凋亡

摘要

桦木酸（BA）是一种天然存在的羽扇豆烷型三萜类化合物，具有广泛的抗不同类型癌症的潜在活性。然而，BA抗宫颈癌的分子机制却鲜有研究。在此，深入讨论了 BA 通过 ROS 介导的内质网应激（ERS）和自噬抑制宫颈癌的作用。研究结果表明，BA 激活 Keap1/Nrf2 通路，并由于 ROS 的产生而引发线粒体依赖性细胞凋亡。此外，BA 增加细胞内 Ca ²⁺水平，抑制 Beclin1 的表达，并促进与 ERS ​​和自噬相关的 GRP78、LC3-II 和 p62 的表达。此外，BA分别与3-甲基腺嘌呤（3-MA）和氯喹（CQ）共同给药可启动自噬体的形成并抑制自噬流。体内实验表明羟氯喹(HCQ)增强BA诱导的细胞凋亡。我们首次证明 BA 可以在 HeLa 细胞中启动早期自噬、抑制自噬流并诱导保护性自噬。因此，BA可能是一种潜在的宫颈癌化疗药物，抑制自噬可以增强BA的抗肿瘤作用。然而，ERS介导的细胞凋亡和自噬介导的细胞凋亡之间信号因子的相互作用值得进一步关注。

图形概要