Department of Pharmacology, College of Medicine, Dongguk University, 123 Dongdae-ro, Gyeongju, Gyeongsangbuk-do, 38066, Republic of Korea.
Department of Pharmacy, Woosuk University, 443 Samnye-ro, Wanju, Jeollabuk-do, 55338, Republic of Korea.
J Ethnopharmacol. 2021 Jun 28;274:114081. doi: 10.1016/j.jep.2021.114081. Epub 2021 Mar 30.
Chaga mushrooms (Inonotus obliquus) are commonly used in traditional treatments in Eastern Europe and Asia due to their diverse pharmacological effects, including anti-tumor and immunologic effects. Thus, many cancer patients take Chaga mushrooms as a complementary medicine, even during chemotherapy or radiotherapy. However, few studies have investigated the effects or molecular targets of Chaga mushrooms in breast cancer.
Herein, we examined the anticancer effects of Chaga mushrooms in different types of breast cancer cell lines, and explored the underlying molecular mechanism to better understand their effects and benefits.
Chaga mushroom extract (CME) was prepared by extracting Chaga mushrooms with 70% ethanol. The cytotoxic effects of CME were assessed by MTT assay and protein expressions were evaluated by western blotting. To evaluate in vivo anti-tumor effects of CME, CME (2 g/kg) was orally administered to 4T1 tumor-bearing BALB/c mice every other day over 30 days (15 administrations), and tumor sizes were measured. Silica gel column chromatography was used to fractionate CME, and major constituents responsible for cytotoxic effects of CME were identified by H/C-NMR and LC-MS.
CME inhibited the proliferation of 4T1 mouse breast cancer cells in a dose and time-dependent manner. The expression of LC3 and phosphorylation of AMPK were increased by CME, while the phosphorylation of mTOR, S6, and S6K1 were suppressed, suggesting that CME induced autophagy by activating AMPK and inhibiting mTOR signaling pathways. Consistent with its observed cytotoxic effect in vitro, CME effectively suppressed tumor growth in 4T1 tumor-bearing BALB/c mice. In addition, inotodiol and trametenolic acid were identified as the major constituents responsible for the cytotoxic effects of CME on breast cancer cells. Moreover, inotodiol and trametenolic acid-enriched fractions both exhibited cytotoxic effects regardless of breast cancer cell subtypes and did not interfere with the cytotoxic effects of conventional drugs.
Taken together, Chaga mushroom extract induced autophagy by activating AMPK and inhibiting the mTOR signaling pathway. Our data suggest Chaga mushrooms may be a beneficial complementary medicine for breast cancer patients.
桦褐孔菌（Inonotus obliquus）由于其多种药理作用，包括抗肿瘤和免疫作用，在东欧和亚洲的传统治疗中被广泛应用。因此，许多癌症患者将桦褐孔菌作为一种辅助药物，甚至在化疗或放疗期间也会服用。然而，很少有研究调查桦褐孔菌在乳腺癌中的作用或分子靶点。
本文研究了桦褐孔菌在不同类型乳腺癌细胞系中的抗癌作用，并探讨了其潜在的分子机制，以更好地理解其作用和益处。
用 70%乙醇提取桦褐孔菌制备桦褐孔菌提取物（CME）。通过 MTT 测定法评估 CME 的细胞毒性作用，通过蛋白质印迹法评估蛋白表达。为了评估 CME 的体内抗肿瘤作用，每隔一天给 4T1 荷瘤 BALB/c 小鼠口服 CME（2 g/kg），连续 30 天（15 次给药），测量肿瘤大小。用硅胶柱层析法对 CME 进行分级，通过 H/C-NMR 和 LC-MS 鉴定负责 CME 细胞毒性作用的主要成分。
CME 呈剂量和时间依赖性抑制 4T1 小鼠乳腺癌细胞的增殖。CME 增加了 LC3 的表达和 AMPK 的磷酸化，同时抑制了 mTOR、S6 和 S6K1 的磷酸化，表明 CME 通过激活 AMPK 并抑制 mTOR 信号通路诱导自噬。与体外观察到的细胞毒性作用一致，CME 有效抑制了 4T1 荷瘤 BALB/c 小鼠的肿瘤生长。此外，鉴定出桦褐孔菌中的桦褐孔菌素和三萜酸是 CME 对乳腺癌细胞产生细胞毒性作用的主要成分。此外，桦褐孔菌素和三萜酸富集馏分均表现出细胞毒性作用，而与乳腺癌细胞亚型无关，并且不干扰常规药物的细胞毒性作用。
总之，桦褐孔菌提取物通过激活 AMPK 并抑制 mTOR 信号通路诱导自噬。我们的数据表明，桦褐孔菌可能是乳腺癌患者有益的辅助药物。
