Chaga mushroom extract induces autophagy via the AMPK-mTOR signaling pathway in breast cancer cells. (28th June 2021)

• Record Type: Journal Article
• Authors: Lee, Min-Gu; Kwon, Yun-Suk; Nam, Kyung-Soo; Kim, Seo Yeon; Hwang, In Hyun; Kim, Soyoung; Jang, Hyunsoo
• Is Part Of: Journal of ethnopharmacology. Volume 274(2021)
• Publication Date: 2021-06-28
• Subjects: Chaga mushroom -- Inonotus obliquus -- Inotodiol -- Trametenolic acid -- Autophagy -- mTOR -- AMPK -- Breast cancer; CME Chaga mushroom extract -- IEF Inotodiol enriched fraction -- TEF Trametenolic acid enriched fraction -- ER Estrogen receptor -- PR Progesterone receptor -- Bcl-xL B-cell lymphoma-extra large -- AIF Apoptosis-inducing factor -- LC3 Microtubule-associated protein 1A/1B-light chain 3 -- AMPK Adenosine monophosphate-activated protein kinase -- mTOR Mechanistic target of rapamycin -- S6K1 Ribosomal protein S6 kinase beta-1 -- S6 Ribosomal protein S6 -- GAPDH Glyceraldehyde-3-phosphate dehydrogenase; Ethnopharmacology -- Periodicals; Pharmacognosy -- Periodicals; Herbs -- Periodicals; Herbs -- Periodicals; Pharmacognosy -- Periodicals; Pharmacognosie -- Périodiques; Herbes -- Périodiques; 615.1
• DOI: 10.1016/j.jep.2021.114081
• Languages: English
• ISSNs: 0378-8741

Abstract

Abstract: Ethnopharmacological relevance: 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. Aim of the study: 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. Materials and methods: 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 1 H/ 13 C-NMR and LC-MS. Results: 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. Conclusions: 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. Graphical abstract: Image 1 Highlights: Chaga mushrooms extract (CME) induced autophagy in breast cancer cell lines. CME activated AMPK but inhibited the mTOR signaling pathway. Inotodiol and trametenolic acid were responsible for the cytotoxic effects of CME. Inotodiol and trametenolic acid did not interfere with effects of cytotoxic drugs.