title: Pseudolaric acid B activates autophagy in MCF-7 human breast cancer cells to prevent cell death.
abstract: Pseudolaric acid B (PAB) has been demonstrated to exert antitumor effects in MCF-7 human breast cancer cells. The present study aimed to investigate the mechanism of resistance to PAB-induced cell death. Following incubation with 4 µM of PAB for 3 days, the majority of MCF-7 cells became senescent, while some retained the same morphology as control cells, as assessed using a senescence detection kit. Additionally, 36 h of treatment with 4 µM of PAB increased the positive staining of autophagy markers, as shown by monodansylcadaverine and acridine orange staining. Western blot analysis indicated that this treatment also increased expression of the autophagy-related proteins Beclin-1 and microtubule-associated protein 1 light chain 3. Furthermore, treatment with PAB and the autophagy inhibitor 3-methyl adenine significantly decreased the ratio of autophagy, as assessed by flow cytometric analysis of monodansylcadaverine staining density (P<0.001), and increased the ratio of cell death, as assessed by MTT analysis (P<0.001). This indicated that autophagy promotes cell survival as a resistance mechanism to PAB treatment. Additionally, the present study demonstrated that PAB treatment did not affect the mitochondrial membrane potential, which may be related to autophagy. Increased Bcl-2 expression may explain why PAB did not affect the mitochondrial membrane potential. A Bcl-2 binding test demonstrated that PAB treatment inhibits the binding of Bcl-2 and Beclin-1, which may free Beclin-1 to participate in autophagy. Therefore, the present study demonstrated that autophagy may be activated by PAB treatment in human breast cancer MCF-7 cells, contributing to resistance to cell death.
authors.affiliation: Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Acupunture, The Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, Jilin 130000, P.R. China.
authors.forename: Chunhai
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Drug Analysis and Analytical Chemistry, Changchun University of Chinese Medicine, Changchun, Jilin 130117, P.R. China.
authors.forename: Tianyang
authors.initials: T
authors.lastname: Xu
authors.affiliation: Department of Biomedical Engineering, College of Pharmacy, Jilin University, Changchun, Jilin 130000, P.R. China.
authors.forename: Minghui
authors.initials: M
authors.lastname: Yan
authors.affiliation: Department of Gastroenterology, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China.
authors.forename: Bianbian
authors.initials: B
authors.lastname: Xue
authors.affiliation: Department of Gastroenterology, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Acupunture, The Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, Jilin 130000, P.R. China.
authors.forename: Chunyu
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Medicinal Chemistry, Changchun University of Chinese Medicine, Changchun, Jilin 130117, P.R. China.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhong
authors.affiliation: Department of Internal Medicine, The First Hospital of Jilin University, Changchun, Jilin 130000, P.R. China.
authors.forename: Zengyan
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Thyroid Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China.
authors.forename: Xianying
authors.initials: X
authors.lastname: Meng
authors.affiliation: Department of Medicinal Chemistry, Changchun University of Chinese Medicine, Changchun, Jilin 130117, P.R. China.
authors.forename: Donghua
authors.initials: D
authors.lastname: Hu
authors.affiliation: Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China; Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Yu
keywords: MCF-7 human breast cancer cells; autophagy; pseudolaric acid B