Pulsatilla saponin D (SB365), a natural compound isolated from rhizoma of Pulsatilla chinensis (Bunge) Regel, exhibited anticancer activities in various cancer types. However, the underlying mechanisms are still unknown. This study mainly investigated the regulations and mechanisms of autophagy and apoptosis in HeLa cells and MCF-7 cells by SB365.The entire process of autophagy is known as autophagic flux, including the delivery of cargo to lysosomes, the breakdown of cargo, and releasing of molecules into the cytosol. The results indicated that SB365 could significantly inhibit the proliferation of HeLa cells in a dose- and time-dependent manner. Exposure of cells to SB365 upregulated Bax, downregulated Bcl-2, disrupted the mitochondrial membrane potential, and induced apoptosis in HeLa cells. In addition, SB365 induced the formation of autophagosome by increasing the phosphorylation of AKT and ERK. SB365 increased the levels of LC3II and p62, indicating that SB365 inhibited autophagic flux and could block the recycling of cellular fuels, as evidenced by a deceased ATP generation and activated AMPK in HeLa cells treated with SB365. Inhibitors of autophagic flux, such as chloroquine, were reported to enhance cytotoxic agent-induced cancer cell death. Interestingly, SB365 synergistically enhanced the anticancer activity of chemotherapeutic agents, including camptothecin (CPT), 5-fluorouracil and etoposide against HeLa cells. Furthermore, SB365 synergistically enhanced the anticancer activity of CPT against MCF-7 cells through promoting the induction of autophagy and apoptosis via activation of JNK/Bcl-2 pathway. These data implied that SB365 could be a promising candidate of anticancer agent used alone or in combination.

白頭翁皂苷 D（SB365）是從白頭翁中分離的化合物，在多種腫瘤細胞中表現 出了抗腫瘤能力。然而，其抗腫瘤機制並未完全闡明。本研究以宮頸癌 HeLa 細 胞和乳腺癌 MCF-7 細胞為研究對象，探討 SB365 抑制腫瘤細胞自噬潮和誘導細 胞凋亡及其機制。自噬的整個過程被稱為自噬潮，包括把包裹的自噬體運到溶酶 體後降解，降解的產物釋放到細胞質供細胞利用。結果顯示，SB365 能夠顯著抑 制 HeLa 細胞的增殖，並呈濃度和時間依賴性；SB365 降低細胞線粒體膜電位， 也可以上調凋亡蛋白 Cleaved PARP、Bax，誘導細胞凋亡；SB365 通過啟動 Akt 和 ERK 誘導 HeLa 細胞自噬體的形成；SB365 增加了 p62 和 LC3II 的表達，說 明 SB365 能夠抑制自噬潮；SB365 抑制 ATP 的合成並啟動 AMPK 信號通路為此 推測提供了旁證，說明其可能抑制細胞內能量物質的循环。研究表明，自噬潮抑 制劑，如氯喹，能夠增強細胞毒性藥物殺傷腫瘤細胞。有趣的是，我們的結果表 明，SB365 能協同增強化療藥喜樹堿、5 氟尿嘧啶及依託泊苷對 HeLa 細胞的抗 癌活性。另外，SB365 也能通過啟動 JNK/Bcl-2 信號通路誘導自噬和細胞凋亡， 從而協同增強喜樹堿對 MCF-7 細胞的抗癌活性。這些數據提示，SB365 是一個 有前景的抗腫瘤藥物，可單獨或聯合用藥用於腫瘤治療。 關鍵字：白頭翁皂苷 D；自噬；自噬潮；凋亡； 腫瘤細胞