Autophagy Blockade by Ai Du Qing Formula Promotes Chemosensitivity of Breast Cancer Stem Cells Via GRP78/β-Catenin/ABCG2 Axis

Mianmian Liao; Caiwei Wang; Bowen Yang; Danping Huang; Yifeng Zheng; Shengqi Wang; Xuan Wang; Juping Zhang; Chunbian Tang; Zheng Xu; Yu He; Ruolin Huang; Fengxue Zhang; Zhiyu Wang; Neng Wang

doi:10.3389/fphar.2021.659297

Autophagy Blockade by Ai Du Qing Formula Promotes Chemosensitivity of Breast Cancer Stem Cells Via GRP78/β-Catenin/ABCG2 Axis

Front Pharmacol. 2021 Jun 3:12:659297. doi: 10.3389/fphar.2021.659297. eCollection 2021.

Authors

Mianmian Liao¹, Caiwei Wang¹, Bowen Yang^{1

2

3}, Danping Huang⁴, Yifeng Zheng^{2

3}, Shengqi Wang^{2

3}, Xuan Wang^{2

3}, Juping Zhang^{2

3}, Chunbian Tang⁵, Zheng Xu¹, Yu He^{1

6}, Ruolin Huang^{1

6}, Fengxue Zhang¹, Zhiyu Wang^{2

3}, Neng Wang^{1

6}

Affiliations

¹ The Research Center for Integrative Medicine, School of Basic Medical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China.
² Integrative Research Laboratory of Breast Cancer, The Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China.
³ Guangdong Provincial Key Laboratory of Clinical Research on Traditional Chinese Medicine Syndrome, Guangdong Provincial Academy of Chinese Medical Sciences, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.
⁴ Shenzhen Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China.
⁵ Department of Hepatology, Shenzhen Traditional Chinese Medicine Hospital, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine, Shenzhen, China.
⁶ Department of Medical Biotechnology, School of Basic Medical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China.

Abstract

Accumulating evidence suggests that the root of drug chemoresistance in breast cancer is tightly associated with subpopulations of cancer stem cells (CSCs), whose activation is largely dependent on taxol-promoting autophagy. Our pilot study identified GRP78 as a specific marker for chemoresistance potential of breast CSCs by regulating Wnt/β-catenin signaling. Ai Du Qing (ADQ) is a traditional Chinese medicine formula that has been utilized in the treatment cancer, particularly during the consolidation phase. In the present study, we investigated the regulatory effects and molecular mechanisms of ADQ in promoting autophagy-related breast cancer chemosensitivity. ADQ with taxol decreasing the cell proliferation and colony formation of breast cancer cells, which was accompanied by suppressed breast CSC ratio, limited self-renewal capability, as well as attenuated multi-differentiation. Furthermore, autophagy in ADQ-treated breast CSCs was blocked by taxol via regulation of β-catenin/ABCG2 signaling. We also validated that autophagy suppression and chemosensitizing activity of this formula was GRP78-dependent. In addition, GRP78 overexpression promoted autophagy-inducing chemoresistance in breast cancer cells by stabilizing β-catenin, while ADQ treatment downregulated GRP78, activated the Akt/GSK3β-mediated proteasome degradation of β-catenin via ubiquitination activation, and consequently attenuated the chemoresistance-promoted effect of GRP78. In addition, both mouse breast cancer xenograft and zebrafish xenotransplantation models demonstrated that ADQ inhibited mammary tumor growth, and the breast CSC subpopulation showed obscure adverse effects. Collectively, this study not only reveals the chemosensitizating mechanism of ADQ in breast CSCs, but also highlights the importance of GRP78 in mediating autophagy-promoting drug resistance via β-catenin/ABCG2 signaling.

Keywords: Ai Du Qing formula; GRP78/β-catenin/ABCG2 axis; autophagy; breast cancer chemosensitivity; cancer stem cells.