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Luo Y, Wang X, Wang H, Xu Y, Wen Q, Fan S, Zhao R, Jiang S, Yang J, Liu Y, Li X, Xiong W, Ma J, Peng S, Zeng Z, Li X, Phillips JB, Li G, Tan M, Zhou M. High Bak Expression Is Associated with a Favorable Prognosis in Breast Cancer and Sensitizes Breast Cancer Cells to Paclitaxel. PLoS One 2015; 10:e0138955. [PMID: 26406239 PMCID: PMC4583467 DOI: 10.1371/journal.pone.0138955] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 09/05/2015] [Indexed: 01/28/2023] Open
Abstract
Breast cancer has become the leading cause of cancer-related death among women. A large number of patients become resistant to drug chemotherapy. Paclitaxel (Taxol) is an effective chemotherapeutic agent used to treat cancer patients. Taxol has been widely used in human malignancies including breast cancer because it can stabilize microtubules resulting in cell death by causing an arrest during the G2/M phase of the cell cycle. Pro-apoptotic Bcl-2 antagonist killer 1 (Bak) plays an important role in Taxol-induced apoptosis in breast cancer. In our present study, we investigated the expression of the Bak protein and clinicopathological correlations in a large sample of breast cancer tissues by immunohistochemistry. We found that the percentage of high scores of Bak expression in breast cancer was significantly lower than that of the non-cancerous breast control tissue. In addition, lower Bak expression was positively associated with the clinical TNM stage of breast cancer with a significant decrease in overall survival compared with those with higher Bak expression especially in the Luminal and HER2 subtypes. Importantly, higher Bak expression predicted a favorable clinical outcome in the cases treated with Taxol indicated by a higher overall survival than that of patients with lower Bak expression especially in Luminal and HER2 subtypes. Furthermore, these results were confirmed in vitro since overexpression of Bak sensitized breast cancer cells to Taxol by inhibiting proliferation and promoting apoptosis; in contrast, downregulation of Bak through siRNA transfection inhibited Taxol induced-apoptosis. Therefore, our results demonstrate that Bak acts as a sensitive biomarker and favorable prognostic factor for Taxol treatment in breast cancer. The restoration of Bak expression would be therapeutically beneficial for Taxol resistant breast cancer patients.
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Affiliation(s)
- Yanwei Luo
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Xinye Wang
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Heran Wang
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Yang Xu
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Qiuyuan Wen
- The Second Xiang-Ya Hospital, Central South University, Changsha, Hunan, 410011, P. R. China
| | - Songqing Fan
- The Second Xiang-Ya Hospital, Central South University, Changsha, Hunan, 410011, P. R. China
| | - Ran Zhao
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Shihe Jiang
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Jing Yang
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Yukun Liu
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Xiayu Li
- The Third Xiang-Ya Hospital, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Wei Xiong
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Jian Ma
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Shuping Peng
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Zhaoyang Zeng
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Xiaoling Li
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Joshua B. Phillips
- Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, 36604, United States of America
| | - Guiyuan Li
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
| | - Ming Tan
- Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, 36604, United States of America
- * E-mail: (MT); (MZ)
| | - Ming Zhou
- The Affiliated Tumor Hospital of Xiangya Medical School, Cancer Research Institute, Central South University, Changsha, Hunan, 410013, P. R. China
- * E-mail: (MT); (MZ)
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Estrogen regulation of anti-apoptotic Bcl-2 family member Mcl-1 expression in breast cancer cells. PLoS One 2014; 9:e100364. [PMID: 24971890 PMCID: PMC4074091 DOI: 10.1371/journal.pone.0100364] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 05/27/2014] [Indexed: 01/31/2023] Open
Abstract
Estrogen is implicated as an important factor in stimulating breast cancer cell proliferation, and presence of estrogen receptor (ER) is an indication of a good prognosis in breast cancer patients. Mcl-1 is an anti-apoptotic Bcl-2 family member that is often over expressed in breast tumors, correlating with poor survival. In breast cancer, it was been previously shown that epidermal growth factor receptors up-regulate Mcl-1 but the role of estrogen in increasing Mcl-1 expression was unknown. In ERα positive cell lines MCF-7 and ZR-75, estrogen treatment increased Mcl-1 expression at both the protein and mRNA level. In two ERα negative cell lines, SK-BR-3 and MDA-MB-231, estrogen failed to increase in Mcl-1 protein expression. We found that ERα antagonists decreased estrogen mediated Mcl-1 expression at both the protein and mRNA level. Upon knockdown of ERα, Mcl-1 mRNA expression after estrogen treatment was also decreased. We also found that ERα binds to the Mcl-1 promoter at a region upstream of the translation start site containing a half ERE site. Streptavidin-pull down assay showed that both ERα and transcription factor Sp1 bind to this region. These results suggest that estrogen is involved in regulating Mcl-1 expression specifically through a mechanism involving ERα.
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