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Nakatsuji M, Fujimori K. Adipocyte-conditioned medium induces tamoxifen resistance by activating PI3K/Akt/mTOR pathway in estrogen receptor-positive breast cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119821. [PMID: 39159684 DOI: 10.1016/j.bbamcr.2024.119821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 07/29/2024] [Accepted: 08/14/2024] [Indexed: 08/21/2024]
Abstract
Resistance to endocrine therapy is a major clinical challenge in estrogen receptor (ER)-positive breast cancer. Obesity is associated with the clinical response to ER-positive breast cancers; however, the mechanism underlying obesity-induced resistance to endocrine therapy in ER-positive breast cancers remains unclear. In this study, we investigated the molecular mechanisms underlying obesity-induced resistance to tamoxifen (TAM), an anti-estrogen agent, in the ER-positive breast cancer cell line MCF-7 using differentiated adipocyte-conditioned medium (D-CM). Treatment of the cells with D-CM promoted TAM resistance by reducing TAM-induced apoptosis. The expression levels of the ERα target genes were higher in D-CM-treated cells than those in untreated ones. In contrast, when the cells were cultured in the presence of TAM, the expression levels were decreased, with or without D-CM. Moreover, the expression of the markers for cancer stem-like cells (CSCs) and mammosphere formation was enhanced by co-treating with D-CM and TAM, compared with TAM alone. The phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway was activated in MCF-7 cells by D-CM treatment, even in the presence of TAM. Inhibition of the PI3K/Akt/mTOR pathway decreased the expression levels of the CSC markers, suppressed mammosphere formation, and resensitized to TAM via inducing apoptosis in D-CM-treated cells. These results indicate that the conditioned medium of differentiated adipocytes promoted TAM resistance by inducing the CSC phenotype through activation of the PI3K/Akt/mTOR pathway in ER-positive breast cancer cells. Thus, the PI3K/Akt/mTOR pathway may be a therapeutic target in obese patients with ER-positive breast cancers.
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Affiliation(s)
- Masatoshi Nakatsuji
- Department of Pathobiochemistry, Faculty of Pharmacy, Osaka Medical and Pharmaceutical University, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Ko Fujimori
- Department of Pathobiochemistry, Faculty of Pharmacy, Osaka Medical and Pharmaceutical University, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
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2
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Karzoon A, Yerer MB, Cumaoğlu A. Empagliflozin demonstrates cytotoxicity and synergy with tamoxifen in ER-positive breast cancer cells: anti-proliferative and anti-survival effects. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024:10.1007/s00210-024-03316-z. [PMID: 39066911 DOI: 10.1007/s00210-024-03316-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Accepted: 07/17/2024] [Indexed: 07/30/2024]
Abstract
Accumulating evidence suggests that sodium-glucose cotransporter 2 (SGLT2) inhibitors may be effective at eliminating tumor cells. While empagliflozin exhibits nearly the highest selectivity for SGLT2 over SGLT1, its specific impact alone and in combination with tamoxifen remains largely unexplored in estrogen receptor α-positive (ERα +) breast cancer. This study investigated the anticancer effects of empagliflozin and its potential synergy with tamoxifen in MCF-7 breast cancer cells. The individual and combined cytotoxic effects of empagliflozin and tamoxifen were assessed using the xCELLigence system. The activities of AMP-activated protein kinase α (AMPKα), p38 mitogen-activated protein kinase (p38 MAPKα), p70-S6 kinase 1 (p70S6K1), and protein kinase B (Akt) were assessed using Western blotting. The gene expression levels of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and Forkhead box O3a (FOXO3a) were assessed via qPCR. Our results revealed time- and concentration-dependent cytotoxic effects of empagliflozin and tamoxifen whether administered separately or in combination. While tamoxifen exhibits potency with an IC50 value of 17 μM, approximately ten times greater than that of empagliflozin (IC50 = 177 μM), synergistic effects are observed when the concentrations of the two agents approach their respective IC50 values. Additionally, empagliflozin significantly increases AMPKα activity while concurrently inhibiting Akt, p70S6K1, and p38 MAPKα, and these effects are significantly enhanced when empagliflozin is combined with tamoxifen. Moreover, empagliflozin modulates the gene expression, downregulating PGC-1α while upregulating FOXO3a. Empagliflozin exerts anti-proliferative and anti-survival effects by inhibiting mTOR, Akt, and PGC-1α, and it exhibits synergy with tamoxifen in MCF-7 breast cancer cells.
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Affiliation(s)
- Ahmad Karzoon
- Department of Pharmacology, Faculty of Medicine, Erciyes University, Kayseri, Türkiye.
| | - Mükerrem Betül Yerer
- Drug Application and Research Center (ERFARMA), Department of Pharmacology, Faculty of Pharmacy, Erciyes University, Kayseri, Türkiye
| | - Ahmet Cumaoğlu
- Department of Biochemistry, Faculty of Pharmacy, Erciyes University, Kayseri, Türkiye
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3
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Targeting mTOR to overcome resistance to hormone and CDK4/6 inhibitors in ER-positive breast cancer models. Sci Rep 2023; 13:2710. [PMID: 36792625 PMCID: PMC9932145 DOI: 10.1038/s41598-023-29425-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 02/03/2023] [Indexed: 02/17/2023] Open
Abstract
Resistance to therapy remains a major obstacle in cancer management. Although treatment with hormone and CDK4/6 inhibitors is successful in luminal breast cancer, resistance to these treatments is frequent, highlighting the need for novel therapeutic strategies to delay disease progression and improve patient survival. Here, we assessed the mechanisms of acquired resistance using T47D and MCF-7 tamoxifen- and palbociclib-resistant cell-line variants in culture and as xenografts, and patient-derived cells (PDCs) obtained from sensitive or resistant patient-derived xenografts (PDXs). In these models, we analyzed the effect of specific kinase inhibitors on survival, signaling and cellular aggressiveness. Our results revealed that mTOR inhibition is more effective than PI3K inhibition in overcoming resistance, irrespective of PIK3CA mutation status, by decreasing cell proliferation and tumor growth, as well as reducing cell migration and stemness. Moreover, a combination of mTOR and CDK4/6 inhibitors may prevent pathway reactivation downstream of PI3K, interfering with the survival of resistant cells and consequent tumor escape. In conclusion, we highlight the benefits of incorporating mTOR inhibitors into the current therapy in ER + breast cancer. This alternative therapeutic strategy not only enhances the antitumor response but may also delay the emergence of resistance and tumor recurrence.
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Ilozumba MN, Yao S, Llanos AAM, Omilian AR, Zhang W, Datta S, Hong CC, Davis W, Khoury T, Bandera EV, Higgins M, Ambrosone CB, Cheng TYD. mTOR pathway gene expression in association with race and clinicopathological characteristics in Black and White breast cancer patients. Discov Oncol 2022; 13:34. [PMID: 35608730 PMCID: PMC9130392 DOI: 10.1007/s12672-022-00497-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/13/2022] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Aberrant activation of the mammalian Target of Rapamycin (mTOR) pathway has been linked to obesity and endocrine therapy resistance, factors that may contribute to Black-White disparities in breast cancer outcomes. We evaluated associations of race and clinicopathological characteristics with mRNA expression of key mTOR pathway genes in breast tumors. METHODS Surgical tumor tissue blocks were collected from 367 newly diagnosed breast cancer patients (190 Black and 177 White). Gene expression of AKT1, EIF4EBP1, MTOR, RPS6KB2, and TSC1 were quantified by NanoString nCounter. Differential gene expression was assessed using linear regression on log2-transformed values. Gene expression and DNA methylation data from TCGA were used for validation and investigation of race-related differences. RESULTS Compared to White women, Black women had relative under-expression of AKT1 (log2 fold-change = - 0.31, 95% CI - 0.44, - 0.18) and RPS6KB2 (log2 fold-change = - 0.11, 95% CI - 0.19, - 0.03). Higher vs. lower tumor grade was associated with relative over-expression of EIF4EBP1 and RPS6KB2, but with lower expression of TSC1. Compared to luminal tumors, triple-negative tumors had relative under-expression of TSC1 (log2 fold-change = - 0.42, 95% CI - 0.22, - 0.01). The results were similar in the TCGA breast cancer dataset. Post-hoc analyses identified differential CpG methylation within the AKT1 and RPS6KB2 locus between Black and White women. CONCLUSIONS Over-expression of RPS6KB2 and EIF4EBP1 and under-expression of TSC1 might be indicators of more aggressive breast cancer phenotypes. Differential expression of AKT1 and RPS6KB2 by race warrants further investigation to elucidate their roles in racial disparities of treatment resistance and outcomes between Black and White women with breast cancer.
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Affiliation(s)
| | - Song Yao
- Department of Cancer Prevention and Control, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Adana A M Llanos
- Department of Epidemiology, Mailman School of Public Health and Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, NY, New York, United States
| | - Angela R Omilian
- Department of Cancer Prevention and Control, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Weizhou Zhang
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL, USA
| | - Susmita Datta
- Department of Biostatistics, University of Florida, Gainesville, FL, USA
| | - Chi-Chen Hong
- Department of Cancer Prevention and Control, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Warren Davis
- Department of Cancer Prevention and Control, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Thaer Khoury
- Department of Pathology & Laboratory Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Elisa V Bandera
- Cancer Epidemiology and Health Outcomes, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, United States
| | - Michael Higgins
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Christine B Ambrosone
- Department of Cancer Prevention and Control, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Ting-Yuan David Cheng
- Department of Epidemiology, University of Florida, Gainesville, FL, USA.
- Division of Cancer Prevention and Control, Department of Internal Medicine, The Ohio State University, Suite 525, 1590 North High Street, Columbus, OH, 43201, USA.
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p70 S6 kinase as a therapeutic target in cancers: More than just an mTOR effector. Cancer Lett 2022; 535:215593. [PMID: 35176419 DOI: 10.1016/j.canlet.2022.215593] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/25/2022] [Accepted: 02/06/2022] [Indexed: 11/23/2022]
Abstract
p70 S6 kinase (p70S6K) is best-known for its regulatory roles in protein synthesis and cell growth by phosphorylating its primary substrate, ribosomal protein S6, upon mitogen stimulation. The enhanced expression/activation of p70S6K has been correlated with poor prognosis in some cancer types, suggesting that it may serve as a biomarker for disease monitoring. p70S6K is a critical downstream effector of the oncogenic PI3K/Akt/mTOR pathway and its activation is tightly regulated by an ordered cascade of Ser/Thr phosphorylation events. Nonetheless, it should be noted that other upstream mechanisms regulating p70S6K at both the post-translational and post-transcriptional levels also exist. Activated p70S6K could promote various aspects of cancer progression such as epithelial-mesenchymal transition, cancer stemness and drug resistance. Importantly, novel evidence showing that p70S6K may also regulate different cellular components in the tumor microenvironment will be discussed. Therapeutic targeting of p70S6K alone or in combination with traditional chemotherapies or other microenvironmental-based drugs such as immunotherapy may represent promising approaches against cancers with aberrant p70S6K signaling. Currently, the only clinically available p70S6K inhibitors are rapamycin analogs (rapalogs) which target mTOR. However, there are emerging p70S6K-selective drugs which are going through active preclinical or clinical trial phases. Moreover, various screening strategies have been used for the discovery of novel p70S6K inhibitors, hence bringing new insights for p70S6K-targeted therapy.
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Kim JY, Park CS, Jang SK, Seol H, Seong MK, Noh WC, Park IC, Kim HA. The Significance of p-AKT1 as a Prognostic Marker and Therapeutic Target in Patients With Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor-2-Positive Early Breast Cancer. J Breast Cancer 2022; 25:387-403. [DOI: 10.4048/jbc.2022.25.e43] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/26/2022] [Accepted: 10/10/2022] [Indexed: 11/05/2022] Open
Affiliation(s)
- Ji Yea Kim
- Division of Fusion Radiology Research, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Chan Sub Park
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Se-Kyeong Jang
- Division of Fusion Radiology Research, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Hyesil Seol
- Department of Pathology, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Min-Ki Seong
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Woo Chul Noh
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - In-Chul Park
- Division of Fusion Radiology Research, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Hyun-Ah Kim
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
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Distinct Roles of mTOR Targets S6K1 and S6K2 in Breast Cancer. Int J Mol Sci 2020; 21:ijms21041199. [PMID: 32054043 PMCID: PMC7072743 DOI: 10.3390/ijms21041199] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 12/12/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is a master regulator of protein translation, metabolism, cell growth and proliferation. It forms two complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2). mTORC1 is frequently deregulated in many cancers, including breast cancer, and is an important target for cancer therapy. The immunosuppressant drug rapamycin and its analogs that inhibit mTOR are currently being evaluated for their potential as anti-cancer agents, albeit with limited efficacy. mTORC1 mediates its function via its downstream targets 40S ribosomal S6 kinases (S6K) and eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). There are two homologs of S6K: S6K1 and S6K2. Most of the earlier studies focused on S6K1 rather than S6K2. Because of their high degree of structural homology, it was generally believed that they behave similarly. Recent studies suggest that while they may share some functions, they may also exhibit distinct or even opposite functions. Both homologs have been implicated in breast cancer, although how they contribute to breast cancer may differ. The purpose of this review article is to compare and contrast the expression, structure, regulation and function of these two S6K homologs in breast cancer.
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8
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Predicting Radiation Resistance in Breast Cancer with Expression Status of Phosphorylated S6K1. Sci Rep 2020; 10:641. [PMID: 31959810 PMCID: PMC6971275 DOI: 10.1038/s41598-020-57496-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/31/2019] [Indexed: 12/14/2022] Open
Abstract
Emerging evidence suggests that the mammalian target of rapamcyin (mTOR) pathway is associated with radio-resistance in cancer treatment. We hypothesised that phosphorylated ribosomal S6 kinase 1 (p-S6K1), a major downstream regulator of the mTOR pathway, may play a role in predicting radio-resistance. Therefore, we evaluated the association of p-S6K1 expression with radio-resistance in breast cancer cell lines and patients. During median follow-up of 33 (range, 0.1-111) months for 1770 primary breast cancer patients who underwent surgery, patients expressing p-S6K1 showed worse 10-year loco-regional recurrence-free survival (LRFS) compared to that of p-S6K1-negative patients after radiotherapy (93.4% vs. 97.7%, p = 0.015). Multivariate analysis revealed p-S6K1 expression as a predictor of radio-resistance (hazard ratio 7.9, 95% confidence interval 1.1-58.5, p = 0.04). In vitro, CD44high/CD24low MCF7 cells with a radioresistant phenotype expressed higher levels of p-S6K1 than control MCF7 cells. Furthermore, the combination of radiation with treatment of everolimus, an mTOR-S6K1 pathway inhibitor, sensitised CD44high/CD24low MCF7 cells to a greater extent than MCF7 cells. This study provides in vivo and in vitro evidence for p-S6K1 expression status as an important marker for predicting the resistance to radiotherapy and as a possible target for radio-sensitization in breast cancer patients.
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Choi J, Park CS, Seong MK, Seol H, Kim JS, Park IC, Noh WC, Kim HA. Predicting the Benefit of Adjuvant Aromatase Inhibitor Therapy in Postmenopausal Breast Cancer Patients with Phosphorylated S6K1 Expression Status. J Breast Cancer 2019; 23:10-19. [PMID: 32140266 PMCID: PMC7043945 DOI: 10.4048/jbc.2020.23.e5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 11/20/2019] [Indexed: 12/11/2022] Open
Abstract
Purpose Phosphorylated ribosomal S6 kinase 1 (pS6K1) is a major downstream regulator of the mammalian target of rapamycin (mTOR) pathway. Recent studies have addressed the role of S6K1 in adipogenesis. pS6K1 may affect the outcome of estrogen depletion therapy in patients with hormone-sensitive breast cancer due to its association with adipogenesis and increased local estrogen levels. This study aimed to investigate the potential of pS6K1 as a predictive marker of adjuvant aromatase inhibitor (AI) therapy outcome in postmenopausal or ovarian function-suppressed patients with hormone-sensitive breast cancer. Methods Medical records were retrospectively reviewed in postmenopausal or ovarian function-suppressed patients with estrogen receptor-positive and node-positive primary breast cancer. pS6K1 expression status was scored on a scale from 0 (negative) to 3+ (positive) based on immunohistochemical analysis. Results A total of 428 patients were eligible. The median follow-up duration was 44 months (range, 1–90). In patients with positive pS6K1 expression, AIs significantly improved disease-free survival (DFS) compared to selective estrogen receptor modulators (SERMs) (5 year-DFS: 83.5% vs. 50.7%, p = 0.016). However, there was no benefit of AIs on DFS in the pS6K1 negative group (5 year-DFS 87.6% vs. 91.4%, p = 0.630). On multivariate analysis, AI therapy remained a significant predictor for DFS in the pS6K1 positive group (hazard ratio, 0.39; 95% confidence interval, 0.16–0.96; p = 0.041). pS6K1 was more effective in predicting the benefit of AI therapy in patients with ages < 50 (p = 0.021) compared to those with ages ≥ 50 (p = 0.188). Conclusion pS6K1 expression may predict AI therapy outcomes and serve as a potential predictive marker for adjuvant endocrine therapy in postmenopausal and ovarian function-suppressed patients with hormone-sensitive breast cancer. AIs may be more effective in patients with pS6K1 positive tumors, while SERM could be considered an alternative option for patients with pS6K1 negative tumors.
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Affiliation(s)
- Jihye Choi
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.,Department of Surgery, National Medical Center, Seoul, Korea
| | - Chan Sub Park
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Min-Ki Seong
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Hyesil Seol
- Department of Pathology, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Jae-Sung Kim
- Division of Basic Radiation Bioscience, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - In-Chul Park
- Division of Basic Radiation Bioscience, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Woo Chul Noh
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Hyun-Ah Kim
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
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Park CS, Choi J, Seong MK, Hong SE, Kim JS, Park IC, Seol H, Noh WC, Kim HA. pS6K1 as an efficacy marker of GnRH agonist with premenopausal breast cancer. Endocr Connect 2019; 8:863-869. [PMID: 31252399 PMCID: PMC6599072 DOI: 10.1530/ec-19-0101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 06/05/2019] [Indexed: 11/10/2022]
Abstract
Estradiol is a key factor for tumorigenesis and prognosis of hormone receptor-positive breast cancer. Adipocytes are one source of estradiol in patients with breast cancer. Recent studies have shown that phosphorylated ribosomal protein S6 kinase-1 plays a critical role in adipogenesis. Therefore, estrogen depletion therapy might have beneficial effects in phosphorylated ribosomal protein S6 kinase-1-positive breast cancer. This study was conducted to evaluate the value of phosphorylated ribosomal protein S6 kinase-1 as a marker for gonadotropin-releasing hormone agonist treatment, a form of estrogen depletion therapy, for premenopausal patients with HR-positive, human epidermal growth factor receptor 2-negative breast cancer. We reviewed the medical records of 296 premenopausal patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative primary invasive breast cancer treated between 2008 and 2015. Phosphorylated ribosomal protein S6 kinase-1 positivity was defined by immunohistochemical staining scores of 1+, 2+ and 3+, whereas a score of 0 was considered negative. Phosphorylated ribosomal protein S6 kinase-1-positive tumors were found in 74.0% of the patients. In the phosphorylated ribosomal protein S6 kinase-1-positive group, disease-free survival of patients treated with a gonadotropin-releasing hormone agonist was significantly longer than that of patients treated without a gonadotropin-releasing hormone agonist (mean 106.7 months vs mean 91.1 months, P = 0.018). Phosphorylated ribosomal protein S6 kinase-1 is a potential biomarker for predicting the efficacy of gonadotropin-releasing hormone agonist therapy in premenopausal patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer.
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Affiliation(s)
- Chan Sub Park
- Department of Breast and Thyroid Surgery, Kyungpook National University Chilgok Hospital, Buk-gu, Daegu, Republic of Korea
| | - Jihye Choi
- Department of General Surgery, National Medical Center, Jung-gu, Seoul, Republic of Korea
| | - Min-Ki Seong
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Nowon-gu, Seoul, Republic of Korea
| | - Sung-Eun Hong
- Radiation Medicine Clinical Research Division, Korea Institute of Radiological and Medical Sciences, Nowon-gu, Seoul, Republic of Korea
| | - Jae-Sung Kim
- Radiation Medicine Clinical Research Division, Korea Institute of Radiological and Medical Sciences, Nowon-gu, Seoul, Republic of Korea
| | - In-Chul Park
- Division of Fusion Radiology Research, Korea Institute of Radiological and Medical Sciences, Nowon-gu, Seoul, Republic of Korea
| | - Hyesil Seol
- Department of Pathology, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Nowon-gu, Seoul, Republic of Korea
| | - Woo Chul Noh
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Nowon-gu, Seoul, Republic of Korea
| | - Hyun-Ah Kim
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Nowon-gu, Seoul, Republic of Korea
- Correspondence should be addressed to H-A Kim:
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11
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Zhang S, Hu B, Lv X, Chen S, Liu W, Shao Z. The Prognostic Role of Ribosomal Protein S6 Kinase 1 Pathway in Patients With Solid Tumors: A Meta-Analysis. Front Oncol 2019; 9:390. [PMID: 31139572 PMCID: PMC6527894 DOI: 10.3389/fonc.2019.00390] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 04/26/2019] [Indexed: 12/26/2022] Open
Abstract
Background: Recent studies supported the predictive role of ribosomal protein S6 kinase 1 (S6K1), phosphorylated S6K1 (p-S6K1), and phosphorylated ribosomal protein S6 (p-S6) for the outcome of cancer patients. However, inconsistent results were acquired across different researches. To comprehensively and quantitatively elucidate their prognostic significance in solid malignancies, the current meta-analysis was carried out utilizing the results of clinical studies. Methods: We conducted the literature retrieval by searching PubMed, Web of Science, EMBASE, and Cochrane library to identify eligible publications. Data were collected from included articles to calculate pooled overall survival (OS), disease-free survival (DFS), recurrence-free survival (RFS), and progression-free survival (PFS). Hazard ratios (HRs) with 95% confidence intervals (CIs) served as appropriate parameters to assess prognostic significance. Results: Forty-four original studies were included, of which 7 studies were analyzed for S6K1, 24 for p-S6K1, and 16 for p-S6. The overexpression of p-S6K1 was significantly associated with poorer prognosis of solid tumor patients in OS (HR = 1.706, 95%CI: 1.369–2.125, p < 0.001), DFS (HR = 1.665, 95%CI: 1.002–2.768, p = 0.049). However, prognostic role of p-S6K1 in RFS and PFS was not found. The result also revealed that S6K1 and p-S6 were significantly associated with reduced OS (HR = 1.691, 95%CI: 1.306–2.189, p < 0.001; HR = 2.019, 95%CI: 1.775–2.296, p < 0.001, respectively). Conclusions: The present meta-analysis demonstrated that elevated expression of S6K1, p-S6K1, or p-S6 might indicate worse prognosis of patients with solid tumors, and supported a promising clinical test to predict solid tumor prognosis based on the level of S6K1 pathway.
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Affiliation(s)
- Shuo Zhang
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Binwu Hu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao Lv
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Songfeng Chen
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Weijian Liu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zengwu Shao
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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12
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Kanaizumi H, Higashi C, Tanaka Y, Hamada M, Shinzaki W, Azumi T, Hashimoto Y, Inui H, Houjou T, Komoike Y. PI3K/Akt/mTOR signalling pathway activation in patients with ER-positive, metachronous, contralateral breast cancer treated with hormone therapy. Oncol Lett 2018; 17:1962-1968. [PMID: 30675261 DOI: 10.3892/ol.2018.9759] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/31/2018] [Indexed: 01/12/2023] Open
Abstract
Oestrogen receptor (ER)-positive, metachronous, contralateral breast cancer (MCBC) sometimes develops during or soon after completion of hormone therapy (HT), but it is uncertain whether it is HT-resistant. We examined the association between ER-positive second cancer and activation of the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) pathways, which are associated with HT resistance. We examined the treatment-free interval (time after completion of HT for initial cancer) in 41 patients with ER-positive MCBC with a history of adjuvant HT for initial cancer (HT group), and initial-to-second period duration (time after operation of initial cancer to onset of second cancer) in 17 patients with ER-positive MCBC in whom adjuvant HT was not applied to the initial tumour (control group or no HT group). Phosphorylated S6 (pS6) and phosphorylated MAPK (pMAPK) were used as indicators of PI3K/Akt/mTOR and MAPK pathway activity, respectively. Tumours were classified as showing negative, positive or strongly positive staining, and the correlation between staining and treatment-free interval or initial-to-second period duration was evaluated using the Spearman's rank correlation coefficient (ρ). Treatment-free interval and pS6 staining showed a negative correlation (ρ=-0.5355; P=0.0003) in the HT group. There was no correlation between initial-to-second period duration and pS6 staining in the no HT group (ρ=-0.0814; P=0.756). There was no correlation between pMAPK signalling and the treatment-free interval in the HT group (ρ=-0.1560; P=0.330) or the initial-to-second period duration in the no HT group (ρ=-0.0116; P=0.965). Development of a second ER-positive cancer during or soon after completion of HT for the initial cancer may be associated with activation of the PI3K/Akt/mTOR pathway. Care should be taken during follow-up and when selecting adjuvant therapy for second cancer.
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Affiliation(s)
- Hirofumi Kanaizumi
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Chihiro Higashi
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Yumiko Tanaka
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Mika Hamada
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Wataru Shinzaki
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Tatsuya Azumi
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Yukihiko Hashimoto
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Hiroki Inui
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Toshiya Houjou
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
| | - Yoshifumi Komoike
- Division of Breast and Endocrine Surgery, Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka 589-8511, Japan
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13
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Feng Y, Spezia M, Huang S, Yuan C, Zeng Z, Zhang L, Ji X, Liu W, Huang B, Luo W, Liu B, Lei Y, Du S, Vuppalapati A, Luu HH, Haydon RC, He TC, Ren G. Breast cancer development and progression: Risk factors, cancer stem cells, signaling pathways, genomics, and molecular pathogenesis. Genes Dis 2018; 5:77-106. [PMID: 30258937 PMCID: PMC6147049 DOI: 10.1016/j.gendis.2018.05.001] [Citation(s) in RCA: 579] [Impact Index Per Article: 96.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 05/08/2018] [Indexed: 12/14/2022] Open
Abstract
As the most commonly occurring cancer in women worldwide, breast cancer poses a formidable public health challenge on a global scale. Breast cancer consists of a group of biologically and molecularly heterogeneous diseases originated from the breast. While the risk factors associated with this cancer varies with respect to other cancers, genetic predisposition, most notably mutations in BRCA1 or BRCA2 gene, is an important causative factor for this malignancy. Breast cancers can begin in different areas of the breast, such as the ducts, the lobules, or the tissue in between. Within the large group of diverse breast carcinomas, there are various denoted types of breast cancer based on their invasiveness relative to the primary tumor sites. It is important to distinguish between the various subtypes because they have different prognoses and treatment implications. As there are remarkable parallels between normal development and breast cancer progression at the molecular level, it has been postulated that breast cancer may be derived from mammary cancer stem cells. Normal breast development and mammary stem cells are regulated by several signaling pathways, such as estrogen receptors (ERs), HER2, and Wnt/β-catenin signaling pathways, which control stem cell proliferation, cell death, cell differentiation, and cell motility. Furthermore, emerging evidence indicates that epigenetic regulations and noncoding RNAs may play important roles in breast cancer development and may contribute to the heterogeneity and metastatic aspects of breast cancer, especially for triple-negative breast cancer. This review provides a comprehensive survey of the molecular, cellular and genetic aspects of breast cancer.
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Affiliation(s)
- Yixiao Feng
- Chongqing Key Laboratory of Molecular Oncology and Epigenetics, Departments of General Surgery, Clinical Laboratory Medicine, Orthopaedic Surgery, Plastic Surgery and Burn, and Otolaryngology, Head and Neck Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Mia Spezia
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Shifeng Huang
- Chongqing Key Laboratory of Molecular Oncology and Epigenetics, Departments of General Surgery, Clinical Laboratory Medicine, Orthopaedic Surgery, Plastic Surgery and Burn, and Otolaryngology, Head and Neck Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Chengfu Yuan
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Department of Biochemistry and Molecular Biology, China Three Gorges University School of Medicine, Yichang 443002, China
| | - Zongyue Zeng
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine and School of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Linghuan Zhang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Stem Cell Biology and Therapy Laboratory, Ministry of Education Key Laboratory of Child Development and Disorders, The Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Xiaojuan Ji
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Stem Cell Biology and Therapy Laboratory, Ministry of Education Key Laboratory of Child Development and Disorders, The Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Wei Liu
- Chongqing Key Laboratory of Molecular Oncology and Epigenetics, Departments of General Surgery, Clinical Laboratory Medicine, Orthopaedic Surgery, Plastic Surgery and Burn, and Otolaryngology, Head and Neck Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Bo Huang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine and School of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, China
- Department of Clinical Laboratory Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Wenping Luo
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Chongqing Key Laboratory for Oral Diseases and Biomedical Sciences, The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing 401147, China
| | - Bo Liu
- Chongqing Key Laboratory of Molecular Oncology and Epigenetics, Departments of General Surgery, Clinical Laboratory Medicine, Orthopaedic Surgery, Plastic Surgery and Burn, and Otolaryngology, Head and Neck Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Yan Lei
- Chongqing Key Laboratory of Molecular Oncology and Epigenetics, Departments of General Surgery, Clinical Laboratory Medicine, Orthopaedic Surgery, Plastic Surgery and Burn, and Otolaryngology, Head and Neck Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Scott Du
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Student Inquiry Research Program, Illinois Mathematics and Science Academy (IMSA), Aurora, IL 60506, USA
| | - Akhila Vuppalapati
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Student Inquiry Research Program, Illinois Mathematics and Science Academy (IMSA), Aurora, IL 60506, USA
| | - Hue H. Luu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Rex C. Haydon
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Tong-Chuan He
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Guosheng Ren
- Chongqing Key Laboratory of Molecular Oncology and Epigenetics, Departments of General Surgery, Clinical Laboratory Medicine, Orthopaedic Surgery, Plastic Surgery and Burn, and Otolaryngology, Head and Neck Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
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14
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Li R, Wang R, Zhai R, Dong Z. Targeted Inhibition of Mammalian Target of Rapamycin (mTOR) Signaling Pathway Inhibits Proliferation and Induces Apoptosis of Laryngeal Carcinoma Cells in vitro. TUMORI JOURNAL 2018; 97:781-6. [DOI: 10.1177/030089161109700616] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Aim and Objective Laryngeal carcinoma is one of the most aggressive cancers of the head and neck region. The survival rate of patients with laryngeal carcinoma is low due to its late metastases and resistance to chemotherapy and radiotherapy. It was reported that mTOR was involved in the growth and apoptosis of various cancer cells. The aim of this study was to detect the effects of mTOR inhibition by mTOR shRNA on the proliferation, apoptosis and invasive ability of Hep-2 human laryngeal carcinoma cells in vitro. Methods and Study Design mTOR shRNA was designed and transfected into Hep-2 human laryngeal carcinoma cells. Untreated cells and cells treated with control vector (non-targeted shRNA) were used as control. The proliferation and apoptosis of Hep-2 cells were detected by MTT and flow cytometry. A transwell assay was used to measure the invasive ability of Hep-2. The inhibition effects on the mTOR signaling pathway by mTOR shRNA were studied using RT-PCR and Western blot. Results Our results showed that the mRNA and protein expression of mTOR and Akt were high in laryngeal carcinoma cells and could be inhibited by mTOR shRNA. At the same time, low expression of PTEN mRNA and protein was observed in Hep-2 cells. The expression increased when the cells were transfected with mTOR shRNA. This showed that mTOR shRNA could inhibit the proliferation and invasive ability of Hep-2 cells. It also could induce the apoptosis of Hep-2 cells in vitro. Conclusions The mTOR signaling pathway plays an important role in the development of laryngeal carcinoma. The mTOR shRNA we designed in this experiment effectively inhibited the mTOR signaling pathway. It inhibited the proliferation and invasive ability of the studied laryngeal carcinoma cells and induced their apoptosis in vitro. mTOR might therefore be a useful target in the therapy of laryngeal carcinoma.
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Affiliation(s)
- Rongrui Li
- Department of Otorhinolaryngology & Head and Neck Surgery, China-Japan Union Hospital of Jilin University, Changchun
- Department of Orthopedic Surgery, the First Affiliated Hospital of JiaMuSi University, Heilongjiang, China
| | - Riguang Wang
- Department of Orthopedic Surgery, the First Affiliated Hospital of JiaMuSi University, Heilongjiang, China
| | - Raosheng Zhai
- Department of Orthopedic Surgery, the First Affiliated Hospital of JiaMuSi University, Heilongjiang, China
| | - Zhen Dong
- Department of Otorhinolaryngology & Head and Neck Surgery, China-Japan Union Hospital of Jilin University, Changchun
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15
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Araki K, Miyoshi Y. Mechanism of resistance to endocrine therapy in breast cancer: the important role of PI3K/Akt/mTOR in estrogen receptor-positive, HER2-negative breast cancer. Breast Cancer 2017; 25:392-401. [PMID: 29086897 DOI: 10.1007/s12282-017-0812-x] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/26/2017] [Indexed: 12/18/2022]
Abstract
Endocrine therapy is a crucial treatment for estrogen receptor-positive (ER+) breast cancer, with proven clinical benefits. However, adaptive mechanisms emerge in the tumor, causing resistance to endocrine therapy. A better understanding of resistance mechanisms is needed to overcome this problem and to develop new, precise treatment strategies. Accumulating genetic and cancer biological studies demonstrate the importance of understanding the PI3K/Akt/mTOR and CDK4/6/RB pathways in ER+ HER2- breast cancer. PIK3CA (which encodes phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit α) is frequently mutated in breast cancer, and 30% of advanced ER+ HER2- breast cancers have an activating PIK3CA mutation. AKT1 mutations (E17K) have been found in 1.4-8% of breast cancer patients. ER+ breast cancer patients preferentially demonstrate gain of CCND1 (cyclin D1; 58% in luminal B vs. 29% in luminal A) and CDK4 (25% in luminal B vs. 14% in luminal A) and loss of CDKN2A (p16) and CDKN2C (p18), which are negatively regulated with the cell cycle and are correlated with the CDK4/6/RB pathway. Abnormalities in PI3K/Akt/mTOR and CDK4/6/RB pathways due to genetic alterations result in deregulated kinase activity and malignant transformation. This review focuses on the recent reports of the essential role of PI3K/Akt/mTOR and CDK4/6/RB pathways in ER+ HER2- breast cancer.
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Affiliation(s)
- Kazuhiro Araki
- Division of Breast and Endocrine, Department of Surgery, Cancer Center, Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo, 663-8501, Japan.
| | - Yasuo Miyoshi
- Division of Breast and Endocrine, Department of Surgery, Cancer Center, Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo, 663-8501, Japan
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16
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Karlsson E, Magić I, Bostner J, Dyrager C, Lysholm F, Hallbeck AL, Stål O, Lundström P. Revealing Different Roles of the mTOR-Targets S6K1 and S6K2 in Breast Cancer by Expression Profiling and Structural Analysis. PLoS One 2015; 10:e0145013. [PMID: 26698305 PMCID: PMC4689523 DOI: 10.1371/journal.pone.0145013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 11/25/2015] [Indexed: 12/21/2022] Open
Abstract
Background The AKT/mTORC1/S6K pathway is frequently overstimulated in breast cancer, constituting a promising therapeutic target. The benefit from mTOR inhibitors varies, likely as a consequence of tumour heterogeneity, and upregulation of several compensatory feed-back mechanisms. The mTORC1 downstream effectors S6K1, S6K2, and 4EBP1 are amplified and overexpressed in breast cancer, associated with a poor outcome and divergent endocrine treatment benefit. S6K1 and S6K2 share high sequence homology, but evidence of partly distinct biological functions is emerging. The aim of this work was to explore possible different roles and treatment target potentials of S6K1 and S6K2 in breast cancer. Materials and methods Whole-genome expression profiles were compared for breast tumours expressing high levels of S6K1, S6K2 or 4EBP1, using public datasets, as well as after in vitro siRNA downregulation of S6K1 and/or S6K2 in ZR751 breast cancer cells. In silico homology modelling of the S6K2 kinase domain was used to evaluate its possible structural divergences to S6K1. Results Genome expression profiles were highly different in S6K1 and S6K2 high tumours, whereas S6K2 and 4EBP1 profiles showed significant overlaps, both correlated to genes involved in cell cycle progression, among these the master regulator E2F1. S6K2 and 4EBP1 were inversely associated with IGF1 levels, and their prognostic value was shown to be restricted to tumours positive for IGFR and/or HER2. In vitro, S6K1 and S6K2 silencing resulted in upregulation of genes in the mTORC1 and mTORC2 complexes. Isoform-specific silencing also showed distinct patterns, e.g. S6K2 downregulation lead to upregulation of several cell cycle associated genes. Structural analyses of the S6K2 kinase domain showed unique structure patterns, deviating from those of S6K1, facilitating the development of isoform-specific inhibitors. Our data support emerging proposals of distinct biological features of S6K1 and S6K2, suggesting their importance as separate oncogenes and clinical markers, where specific targeting in different breast cancer subtypes could facilitate further individualised therapies.
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Affiliation(s)
- Elin Karlsson
- Department of Clinical and Experimental Medicine, and Department of Oncology, Linköping University, SE-58185, Linköping, Sweden
| | - Ivana Magić
- Department of Clinical and Experimental Medicine, and Department of Oncology, Linköping University, SE-58185, Linköping, Sweden
- Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, SE-58183, Linköping, Sweden
| | - Josefine Bostner
- Department of Clinical and Experimental Medicine, and Department of Oncology, Linköping University, SE-58185, Linköping, Sweden
| | - Christine Dyrager
- Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, SE-58183, Linköping, Sweden
| | - Fredrik Lysholm
- Division of Bioinformatics and SeRC (Swedish e-Science Research Centre), Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden
| | - Anna-Lotta Hallbeck
- Department of Clinical and Experimental Medicine, and Department of Oncology, Linköping University, SE-58185, Linköping, Sweden
| | - Olle Stål
- Department of Clinical and Experimental Medicine, and Department of Oncology, Linköping University, SE-58185, Linköping, Sweden
- * E-mail: (OS); (PL)
| | - Patrik Lundström
- Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, SE-58183, Linköping, Sweden
- * E-mail: (OS); (PL)
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17
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Park JA, Jin HO, Lee HN, Kim JH, Park IC, Noh WC, Chang YH, Hong YJ, Kim KC, Lee JK. S6K1 inhibition enhances the apoptotic cell death of breast cancer cells in response to Bcl-2/Bcl-xL inhibition by the downregulation of survivin. Oncol Lett 2015; 10:829-834. [PMID: 26622578 DOI: 10.3892/ol.2015.3369] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 04/27/2015] [Indexed: 02/06/2023] Open
Abstract
Breast cancer cells possess a deregulated apoptotic pathway with increased expression levels of anti-apoptotic B-cell lymphoma-2 (Bcl-2) family proteins and ribosomal S6 kinase 1 (S6K1) protein activity. Therefore, combined interference of anti-apoptotic Bcl-2 family and S6K1 protein expression may be a reasonable therapeutic strategy for the treatment of patients with breast cancer. In the present study, it was identified that the administration of a combination of ABT263 [navitoclax; a Bcl-2/Bcl-extra large (Bcl-xL) inhibitor] and PF4708671 (an S6K1 inhibitor) markedly increased apoptotic cell death in the BT474 breast cancer cells compared with the administration of either agent alone. Furthermore, the downregulation of Bcl-2/Bcl-xL and S6K1 with small interfering RNA induced a significant increase in cell death compared with RNA interference of either agent alone. Notably, combination treatment with ABT263 and PF4708671 decreased the expression level of survivin protein, with this ectopic expression of survivin attenuating cell death. Thus, the present study determined that the combined inhibition of Bcl-2/Bcl-xL and S6K1 may be a good strategy for treating patients with breast cancer.
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Affiliation(s)
- Jin-Ah Park
- KIRAMS Radiation Biobank, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea ; Department of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Republic of Korea
| | - Hyeon-Ok Jin
- KIRAMS Radiation Biobank, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
| | - Ha-Na Lee
- KIRAMS Radiation Biobank, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
| | - Jin-Hee Kim
- KIRAMS Radiation Biobank, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
| | - In-Chul Park
- Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
| | - Woo Chul Noh
- Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
| | - Yoon Hwan Chang
- Department of Laboratory Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
| | - Young Jun Hong
- Department of Laboratory Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
| | - Keun-Chul Kim
- Department of Biological Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Republic of Korea
| | - Jin Kyung Lee
- KIRAMS Radiation Biobank, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea ; Department of Laboratory Medicine, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea
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18
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Bratton MR, Martin EC, Elliott S, Rhodes LV, Collins-Burow BM, McLachlan JA, Wiese TE, Boue SM, Burow ME. Glyceollin, a novel regulator of mTOR/p70S6 in estrogen receptor positive breast cancer. J Steroid Biochem Mol Biol 2015; 150:17-23. [PMID: 25771071 PMCID: PMC4424142 DOI: 10.1016/j.jsbmb.2014.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 12/22/2014] [Accepted: 12/29/2014] [Indexed: 01/07/2023]
Abstract
An estimated 70% of breast cancer tumors utilize estrogen receptor (ER) signaling to maintain tumorigenesis and targeting of the estrogen receptor is a common method of treatment for these tumor types. However, ER-positive (+) breast cancers often acquire drug resistant or altered ER activity in response to anti-estrogens. Here we demonstrate glyceollin, an activated soy compound, has anti-estrogen effects in breast cancers. We demonstrate through estrogen response element luciferase and phosphorylation-ER mutants that the effects of glyceollin arise from mechanisms distinct from conventional endocrine therapies. We show that glyceollin suppresses estrogen response element activity; however, it does not affect ER-alpha (α) phosphorylation levels. Additionally we show that glyceollin suppresses the phosphorylation of proteins known to crosstalk with ER signaling, specifically we demonstrate an inhibition of ribosomal protein S6 kinase, 70 kDa (p70S6) phosphorylation following glyceollin treatment. Our data suggests a mechanism for glyceollin inhibition of ERα through the induced suppression of p70S6 and demonstrates novel mechanisms for ER inhibition.
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Affiliation(s)
- Melyssa R Bratton
- Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, New Orleans, LA, United States
| | - Elizabeth C Martin
- Department of Medicine-Section of Hematology and Medical Oncology, Tulane University, New Orleans, LA, United States
| | - Steven Elliott
- Department of Medicine-Section of Hematology and Medical Oncology, Tulane University, New Orleans, LA, United States
| | - Lyndsay V Rhodes
- Department of Medicine-Section of Hematology and Medical Oncology, Tulane University, New Orleans, LA, United States
| | - Bridgette M Collins-Burow
- Department of Medicine-Section of Hematology and Medical Oncology, Tulane University, New Orleans, LA, United States
| | - John A McLachlan
- Department of Medicine-Section of Hematology and Medical Oncology, Tulane University, New Orleans, LA, United States; Department of Pharmacology, Tulane University, New Orleans, LA, United States; The Center for Bioenvironmental Research, Tulane University, New Orleans, LA, United States
| | - Thomas E Wiese
- Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, New Orleans, LA, United States
| | - Stephen M Boue
- Southern Regional Research Center, U.S. Department of Agriculture, New Orleans, LA, United States
| | - Matthew E Burow
- Department of Medicine-Section of Hematology and Medical Oncology, Tulane University, New Orleans, LA, United States; Department of Pharmacology, Tulane University, New Orleans, LA, United States; The Center for Bioenvironmental Research, Tulane University, New Orleans, LA, United States.
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19
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Bostner J, Karlsson E, Eding CB, Perez-Tenorio G, Franzén H, Konstantinell A, Fornander T, Nordenskjöld B, Stål O. S6 kinase signaling: tamoxifen response and prognostic indication in two breast cancer cohorts. Endocr Relat Cancer 2015; 22:331-43. [PMID: 25972244 DOI: 10.1530/erc-14-0513] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Detection of signals in the mammalian target of rapamycin (mTOR) and the estrogen receptor (ER) pathways may be a future clinical tool for the prediction of adjuvant treatment response in primary breast cancer. Using immunohistological staining, we investigated the value of the mTOR targets p70-S6 kinase (S6K) 1 and 2 as biomarkers for tamoxifen benefit in two independent clinical trials comparing adjuvant tamoxifen with no tamoxifen or 5 years versus 2 years of tamoxifen treatment. In addition, the prognostic value of the S6Ks was evaluated. We found that S6K1 correlated with proliferation, HER2 status, and cytoplasmic AKT activity, whereas high protein expression levels of S6K2 and phosphorylated (p) S6K were more common in ER-positive, and low-proliferative tumors with pAKT-s473 localized to the nucelus. Nuclear accumulation of S6K1 was indicative of a reduced tamoxifen effect (hazard ratio (HR): 1.07, 95% CI: 0.53-2.81, P=0.84), compared with a significant benefit from tamoxifen treatment in patients without tumor S6K1 nuclear accumulation (HR: 0.42, 95% CI: 0.29-0.62, P<0.00001). Also S6K1 and S6K2 activation, indicated by pS6K-t389 expression, was associated with low benefit from tamoxifen (HR: 0.97, 95% CI: 0.50-1.87, P=0.92). In addition, high protein expression of S6K1, independent of localization, predicted worse prognosis in a multivariate analysis, P=0.00041 (cytoplasm), P=0.016 (nucleus). In conclusion, the mTOR-activated kinases S6K1 and S6K2 interfere with proliferation and response to tamoxifen. Monitoring their activity and intracellular localization may provide biomarkers for breast cancer treatment, allowing the identification of a group of patients less likely to benefit from tamoxifen and thus in need of an alternative or additional targeted treatment.
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Affiliation(s)
- Josefine Bostner
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Elin Karlsson
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Cecilia Bivik Eding
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Gizeh Perez-Tenorio
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Hanna Franzén
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Aelita Konstantinell
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Tommy Fornander
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Bo Nordenskjöld
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
| | - Olle Stål
- Department of Clinical and Experimental MedicineDepartment of OncologyDepartment of Clinical and Experimental MedicineDivision of Dermatology, Linköping University, SE-58185 Linköping, SwedenDepartment of OncologyKarolinska University Hospital, Karolinska Institute, SE-17176 Stockholm, Sweden
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Lu Q, Wang J, Yu G, Guo T, Hu C, Ren P. Expression and clinical significance of mammalian target of rapamycin/P70 ribosomal protein S6 kinase signaling pathway in human colorectal carcinoma tissue. Oncol Lett 2015; 10:277-282. [PMID: 26171014 DOI: 10.3892/ol.2015.3228] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Accepted: 02/11/2015] [Indexed: 11/06/2022] Open
Abstract
The activation of mammalian target of rapamycin (mTOR) has been reported in tumor development, but the role of mTOR in colorectal carcinomas remains unclear. The aim of the present study was to investigate the significance of mTOR and its downstream effector 70 kDa ribosomal protein S6 kinase (P70S6K) in human colorectal carcinomas. The phosphorylated (p-)mTOR and p-P70S6K proteins were examined by immunohistochemistry performed on tissue microarray containing tissue samples obtained from colorectal carcinoma (n=111), adenomatous polyps (n=40) and normal colonic mucosa (n=40), with a comparison between the expression of these proteins and the clinicopathological parameters of patients with carcinomas. The positive expression rates of p-mTOR and p-P70S6k were 60.4 and 65.8%, respectively, in colorectal carcinoma tissue, which was significantly increased compared with the tissue from adenomatous polyps (27.5 and 20%, respectively) and normal colonic mucosa (10.0 and 5.0%, respectively) (P<0.05). Overexpression of the p-mTOR and p-P70S6K proteins was significantly associated with the tumor-node-metastasis stage, the occurrence of distal and lymph node metastasis and the degree of differentiation. Aberrant expression of p-mTOR and p-P70S6K may contribute to the pathogenesis, growth, invasion and metastasis of colorectal carcinoma. The phosphorylation of these proteins was considered to be a promising marker to indicate the aggressive behaviors and prognosis of colorectal carcinomas. The overexpression of the mTOR/P70S6K signaling pathway may play an important role in colorectal carcinoma carcinogenesis. The expression of p-mTOR and p-P70S6K was considered as a promising marker to indicate the aggressive behaviors and prognosis of human colorectal carcinomas.
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Affiliation(s)
- Qingjun Lu
- Department of General Surgery, Binzhou Central Hospital, Binzhou Medical College, Binzhou, Shandong, P.R. China
| | - Jieshu Wang
- Department of General Surgery, Binzhou Central Hospital, Binzhou Medical College, Binzhou, Shandong, P.R. China
| | - Gang Yu
- Department of General Surgery, Binzhou Central Hospital, Binzhou Medical College, Binzhou, Shandong, P.R. China
| | - Tianhua Guo
- Department of General Surgery, Binzhou Central Hospital, Binzhou Medical College, Binzhou, Shandong, P.R. China
| | - Chun Hu
- Department of Oncology, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, P.R. China
| | - Peng Ren
- Department of General Surgery, Binzhou Central Hospital, Binzhou Medical College, Binzhou, Shandong, P.R. China
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Citro S, Miccolo C, Meloni L, Chiocca S. PI3K/mTOR mediate mitogen-dependent HDAC1 phosphorylation in breast cancer: a novel regulation of estrogen receptor expression. J Mol Cell Biol 2015; 7:132-42. [PMID: 25801958 DOI: 10.1093/jmcb/mjv021] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/02/2015] [Indexed: 12/20/2022] Open
Abstract
Histone deacetylase 1 (HDAC1) is an important epigenetic controller involved in transcriptional regulation through modification of chromatin structure. Genetic and epigenetic changes and deregulation of signal transduction pathways have been implicated in the development of breast cancer. Downregulation of estrogen receptor α (ERα) expression is one of the mechanisms behind the acquisition of endocrine resistance. Sustained and increased hormone and growth factor receptor signaling in breast cancer cells contribute to resistance to endocrine therapy. Both HDACs and the PI3K/mTOR signaling pathway are becoming promising targets in breast cancer, reversing also acquired hormone resistance. Here we show how mitogens, activating the PI3K/mTOR pathway, trigger the phosphorylation of HDAC1 in breast cancer cells, which is completely dependent on the activity of the p70 S6 kinase (S6K1). Our findings show that S6K1, overexpressed in many breast cancers, controls HDAC1-dependent transcriptional regulation of ERα levels upon mitogenic stimuli, controlling HDAC1 recruitment to the ERα promoter. Furthermore, cell treatment with both mTOR and HDACs inhibitors shows an additive effect in inhibiting breast cancer proliferation. This confirms the novel cross-talk between the HDAC1 and PI3K pathways with clinical implications towards the treatment of this malignant disease.
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Affiliation(s)
- Simona Citro
- Department of Experimental Oncology, European Institute of Oncology, IFOM-IEO Campus, via Adamello 16, 20139 Milan, Italy
| | - Claudia Miccolo
- Department of Experimental Oncology, European Institute of Oncology, IFOM-IEO Campus, via Adamello 16, 20139 Milan, Italy
| | - Laura Meloni
- Department of Experimental Oncology, European Institute of Oncology, IFOM-IEO Campus, via Adamello 16, 20139 Milan, Italy Present address: Department for Molecular Biomedical Research, Technologiepark Zwijnaarde, 927 VIB west, 9052 Ghent, Belgium
| | - Susanna Chiocca
- Department of Experimental Oncology, European Institute of Oncology, IFOM-IEO Campus, via Adamello 16, 20139 Milan, Italy
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Yanai A, Inoue N, Yagi T, Nishimukai A, Miyagawa Y, Murase K, Imamura M, Enomoto Y, Takatsuka Y, Watanabe T, Hirota S, Sasa M, Katagiri T, Miyoshi Y. Activation of mTOR/S6K But Not MAPK Pathways Might Be Associated With High Ki-67, ER(+), and HER2(-) Breast Cancer. Clin Breast Cancer 2014; 15:197-203. [PMID: 25600244 DOI: 10.1016/j.clbc.2014.12.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 12/16/2014] [Indexed: 12/27/2022]
Abstract
UNLABELLED We determined the activation of the phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways in 108 cases of estrogen receptor-positive and human epidermal growth factor receptor 2-negative breast cancer with high and low Ki-67 expression. The expression levels of Ki-67, p53, phosphorylated MAPK (pMAPK), and protein S6 (pS6; downstream molecule of PI3K/Akt/mammalian target of rapamycin/S6 kinase pathway) were determined immunohistochemically. pS6 positivity, but not pMAPK positivity, was significantly associated with the high Ki-67 expression subset. BACKGROUND Evaluation of luminal A and luminal B characteristics of estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is considered important. Although the phosphoinositide 3 kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways are thought to be involved in the luminal B subtype, the details of their contribution to breast cancer remain unclear. MATERIALS AND METHODS We determined the activation of these pathways (phosphorylated MAPK [pMAPK] and protein S6 [pS6; a downstream molecule of PI3K/Akt/mammalian target of rapamycin (mTOR)/S6 kinase (S6K)]) in 108 ER(+), HER2(-) breast cancer cases with high and low Ki-67 expression. The ER, progesterone receptor (PgR), Ki-67, p53 expression levels were also determined immunohistochemically. The cutoff value for Ki-67 was set at 15%. RESULTS A significantly greater percentage of cancer cases with high Ki-67 expression showed pS6 positivity than did those with low Ki-67 expression (53.2% vs. 19.7%; P = .0003). No significant differences were found between the cases with high and low expression levels were detected for p53 (23.4% vs. 11.5%; P = .12) or pMAPK (36.2% vs. 34.4%; P = .85) positivity. Multivariate analysis showed that pS6 positivity (odds ratio 5.16, 95% confidence interval 1.95-13.63; P = .0009), nuclear grade 2 and 3, and low PgR expression (≤ 20%) were independently associated with the high Ki-67 subset. CONCLUSION From our findings, we have concluded that the pS6 expression level is associated with the characteristics of breast cancer with high Ki-67 expression. Because these associations were observed, irrespective of menopausal status, the biologic difference seems to be less affected by estrogen signaling than by activation of S6 protein, especially in terms of proliferation. Our findings have also indicated that targeting the mTOR/S6K pathway might be a useful strategy for the treatment of ER(+)/HER2(-) breast cancer with high Ki-67 expression.
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Affiliation(s)
- Ayako Yanai
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Natsuko Inoue
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Tomoko Yagi
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Arisa Nishimukai
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Yoshimasa Miyagawa
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Keiko Murase
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Michiko Imamura
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Yukie Enomoto
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Yuichi Takatsuka
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Takahiro Watanabe
- Department of Surgical Pathology, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Seiichi Hirota
- Department of Surgical Pathology, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Mitsunori Sasa
- Tokushima Breast Care Clinic, Tokushima, Tokushima, Japan
| | - Toyomasa Katagiri
- Division of Genome Medicine, Institute for Genome Research, University of Tokushima, Tokushima, Tokushima, Japan
| | - Yasuo Miyoshi
- Division of Breast and Endocrine, Department of Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan.
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Wang S, Sun Y, He A, Zheng C, Zheng X. Predictive value of phosphorylated mammalian target of rapamycin for disease-free survival in breast cancer patients receiving neoadjuvant chemotherapy. Oncol Lett 2014; 8:2642-2648. [PMID: 25364442 PMCID: PMC4214504 DOI: 10.3892/ol.2014.2551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 07/25/2014] [Indexed: 11/05/2022] Open
Abstract
The mammalian target of rapamycin (mTOR)/eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) pathway plays a critical role in cell growth, survival and angiogenesis, and has been demonstrated to correlate with human epidermal growth factor receptor 2 (HER2) status. Neoadjuvant chemotherapy (NAC), also known as preoperative therapy, is now well established in the treatment of inoperable locally advanced and inflammatory breast cancer. In vitro study has shown that mTOR inhibitors, together with cytotoxic agents, exhibit tumor cell killing activity. A number of non-randomized studies in HER2-positive trastuzumab-resistant metastatic breast cancer have revealed the antitumor activity of mTOR inhibitors when used together with standard chemotherapy plus trastuzumab. In the present study, the expression levels of phosphorylated (p)-mTOR and p-4E-BP1 were analyzed in breast cancer patients prior to and following NAC, to determine whether p-mTOR and p-4E-BP1 affect the response to NAC and the subsequent survival. Formalin-fixed, paraffin-embedded tissues representing matched pairs of core biopsy (pre-NAC) and surgical specimen (post-NAC) from 83 patients with invasive ductal carcinomas were collected. Immunohistochemistry was performed to evaluate the expression of p-mTOR and p-4E-BP1 using a semi-quantitative scoring system by two pathologists. It was found that the expression of p-mTOR and p-4E-BP1 was downregulated following NAC. The decrease in mTOR expression following NAC was found to positively correlate with HER2 expression and the reduction of tumor sizes. The high expression of p-mTOR and p-4E-BP1 in pre-NAC specimens was associated with poor disease-free survival (DFS). Furthermore, the high expression of p-mTOR in post-NAC specimens was associated with poor DFS, regardless of whether the expression was high or low in the pre-NAC specimens. In conclusion, NAC was found to decrease the expression levels of p-mTOR and p-4E-BP1. The p-mTOR expression post-NAC may potentially serve as a predictor for DFS. However, further study is required to clarify the mechanism and to evaluate the predictive value of the phosphatidylinositol 3-kinase/Akt/mTOR/4E-BP1 pathway in NAC.
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Affiliation(s)
- Shuo Wang
- Department of Breast Surgery, First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yiqun Sun
- Department of Burns, General Hospital of Benxi Iron and Steel Company, Benxi, Liaoning 117000, P.R. China
| | - Anning He
- Lab 1, Cancer Institute, China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Caiwei Zheng
- Department of Biology, Brandeis University, Waltham, MA 02453, USA
| | - Xinyu Zheng
- Department of Breast Surgery, First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P.R. China ; Lab 1, Cancer Institute, China Medical University, Shenyang, Liaoning 110001, P.R. China
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Horii R, Matsuura M, Dan S, Ushijima M, Uehiro N, Ogiya A, Honma N, Ito Y, Iwase T, Yamori T, Akiyama F. Extensive analysis of signaling pathway molecules in breast cancer: association with clinicopathological characteristics. Int J Clin Oncol 2014; 20:490-8. [PMID: 25312293 DOI: 10.1007/s10147-014-0753-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/16/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND The aim of this study was to extensively analyze the signaling pathway molecules in breast cancer and to explore candidate biomarkers for clinicopathological relevance. METHODS We assessed the expression of key factors in cell signaling, namely p-AKT, cyclin D1, P27, p-p70S6 K, p-4EBP1, and p-MAPK/ERK, within 338 invasive breast cancer patients. These factors were immunohistochemically examined in tumor tissues and assessed by staining score. Staining scores were analyzed by a clustering method to devise a new classification based on pathway activity. We investigated the relationships among staining scores, the clustering classification, and patient characteristics. RESULTS The proportion of patients displaying high expression levels were as follows: p-AKT, 75%; cyclin D1, 12%; P27, 53%; p-p70S6 K, 37%; p-4EBP1, 19%; and p-MAPK/ERK, 3%. Patients were classified into two groups on the basis of staining scores. Group 1 (39%) included more positive cases for p-4EBP1, p-MAPK/ERK, and p-p70S6 K and fewer positive cases for P27 and cyclin D1 than Group 2 (61%). The clustering classification was significantly related to subgrouping by hormone receptor and HER2 (P < 0.001), nuclear grade (P < 0.001) and histological subtype (P = 0.034). A strong positive correlation was identified between p-AKT and P27, cyclin D1 and P27, p-p70S6 K and p-4EBP1, p-p70S6 K and p-MAPK/ERK, and between p-4EBP1 and p-MAPK/ERK. Levels of p-p70S6 K were significantly related to recurrence in both univariate (RR = 0.75, P < 0.001) and multivariate (RR = 0.71, P = 0.049) analyses. CONCLUSIONS The present study helps us to understand the characteristics of signaling pathway status in breast cancers. Moreover, p-p70S6 K expression may be of use in predicting clinical outcome.
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Affiliation(s)
- Rie Horii
- Department of Pathology, Cancer Institute, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan,
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Yardley DA. Adverse Event Management of mTOR Inhibitors During Treatment of Hormone Receptor–Positive Advanced Breast Cancer: Considerations for Oncologists. Clin Breast Cancer 2014; 14:297-308. [DOI: 10.1016/j.clbc.2014.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/06/2014] [Accepted: 03/24/2014] [Indexed: 10/25/2022]
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Signaling pathways in breast cancer: therapeutic targeting of the microenvironment. Cell Signal 2014; 26:2843-56. [PMID: 25093804 DOI: 10.1016/j.cellsig.2014.07.034] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 07/28/2014] [Indexed: 02/08/2023]
Abstract
Breast cancer is the most common cancer in women worldwide. Understanding the biology of this malignant disease is a prerequisite for selecting an appropriate treatment. Cell cycle alterations are seen in many cancers, including breast cancer. Newly popular targeted agents in breast cancer include cyclin dependent kinase inhibitors (CDKIs) which are agents inhibiting the function of cyclin dependent kinases (CDKs) and agents targeting proto-oncogenic signaling pathways like Notch, Wnt, and SHH (Sonic hedgehog). CDKIs are categorized as selective and non-selective inhibitors of CDK. CDKIs have been tried as monotherapy and combination therapy. The CDKI Palbocyclib is now a promising therapeutic in breast cancer. This drug recently entered phase III trial for estrogen receptor (ER) positive breast cancer after showing encouraging results in progression free survival in a phase II trials. The tumor microenvironment is now recognized as a significant factor in cancer treatment response. The tumor microenvironment is increasingly considered as a target for combination therapy of breast cancer. Recent findings in the signaling pathways in breast cancer are herein summarized and discussed. Furthermore, the therapeutic targeting of the microenvironment in breast cancer is also considered.
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Phosphorylated p-70S6K predicts tamoxifen resistance in postmenopausal breast cancer patients randomized between adjuvant tamoxifen versus no systemic treatment. Breast Cancer Res 2014; 16:R6. [PMID: 24447434 PMCID: PMC3979131 DOI: 10.1186/bcr3598] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 12/10/2013] [Indexed: 01/15/2023] Open
Abstract
Introduction Activation of the phosphatidylinositol-3-kinase (PI3K) and/or mitogen-activated protein kinase (MAPK) pathways results in anti-estrogen resistance in vitro, but a biomarker with clinical validity to predict intrinsic resistance has not been identified. In metastatic breast cancer patients with previous exposure to endocrine therapy, the addition of a mammalian target of rapamycine (mTOR) inhibitor has been shown to be beneficial. Whether or not patients on adjuvant endocrine treatment might benefit from these drugs is currently unclear. A biomarker that predicts intrinsic resistance could potentially be used as companion diagnostic in this setting. We tested the clinical validity of different downstream-activated proteins in the PI3K and/or MAPK pathways to predict intrinsic tamoxifen resistance in postmenopausal primary breast cancer patients. Methods We recollected primary tumor tissue from patients who participated in a randomized trial of adjuvant tamoxifen (1–3 years) versus observation. After constructing a tissue micro-array, cores from 563 estrogen receptor α positive were immunostained for p-AKT(Thr308), p-AKT(Ser473), p-mTOR, p-p706SK and p-ERK1/2. Cox proportional hazard models for recurrence free interval were used to assess hazard ratios and interactions between these markers and tamoxifen treatment efficacy. Results Interactions were identified between tamoxifen and p-AKT(Thr308), p-mTOR, p-p70S6K and p-ERK1/2. Applying a conservative level of significance, p-p70S6K remained significantly associated with tamoxifen resistance. Patients with p-p70S6K negative tumors derived significant benefit from tamoxifen (HR 0.24, P < 0.0001), while patients whose tumor did express p-p70S6K did not (HR = 1.02, P =0.95), P for interaction 0.004. In systemically untreated breast cancer patients, p-p70S6K was associated with a decreased risk for recurrence. Conclusions Patients whose tumor expresses p-p70S6K, as a marker of downstream PI3K and/or MAPK pathway activation, have a favorable prognosis, but do not benefit from adjuvant tamoxifen. A potential benefit from inhibitors of the PI3K/Akt/mTOR pathway in these patients needs to be further explored.
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Leal P, Garcia P, Sandoval A, Buchegger K, Weber H, Tapia O, Roa JC. AKT/mTOR substrate P70S6K is frequently phosphorylated in gallbladder cancer tissue and cell lines. Onco Targets Ther 2013; 6:1373-84. [PMID: 24124380 PMCID: PMC3794848 DOI: 10.2147/ott.s46897] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background Gallbladder carcinoma is a highly malignant tumor and a public health problem in some parts of the world. It is characterized by a poor prognosis and its resistance to radio and chemotherapy. There is an urgent need to develop novel therapeutic alternatives for the treatment of gallbladder carcinoma. The mammalian target of the rapamycin (mTOR) signaling pathway is activated in about 50% of human malignancies, and its role in gallbladder carcinoma has previously been suggested. In the present study, we investigated the phosphorylation status of the mTOR substrate p70S6K in preneoplastic and neoplastic gallbladder tissues and evaluated the effect of three mTOR inhibitors on cell growth and migration in gallbladder carcinoma cell lines. Methods Immunohistochemical staining of phospho-p70S6K was analyzed in 181 gallbladder carcinoma cases, classified according to lesion type as dysplasia, early carcinoma, or advanced carcinoma. Protein expression of AKT/mTOR members was also evaluated in eight gallbladder carcinoma cell lines by Western blot analysis. We selected two gallbladder carcinoma cell lines (G415 and TGBC-2TKB) to evaluate the effect of rapamycin, RAD001, and AZD8055 on cell viability, cell migration, and protein expression. Results Our results showed that phospho-p70S6K is highly expressed in dysplasia (66.7%, 12/18), early cancer (84.6%, 22/26), and advanced cancer (88.3%, 121/137). No statistical correlation was observed between phospho-p70S6K status and any clinical or pathological features, including age, gender, ethnicity, wall infiltration level, or histological differentiation (P < 0.05). In vitro treatment with rapamycin, RAD001, and AZD8055 reduced cell growth, cell migration, and phospho-p70S6K expression significantly in G-415 and TGBC-2TKB cancer cells (P < 0.001). Conclusion Our findings confirm the upregulation of this signaling pathway in gallbladder carcinoma and provide a rationale for the potential use of mTOR inhibitors as a therapeutic strategy for human gallbladder carcinoma.
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Affiliation(s)
- Pamela Leal
- Department of Pathology, Universidad de La Frontera, Center of Genetical and Immunological Studies-Scientific and Technological Bioresource Nucleus, Temuco, Santiago, Chile
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Hong SE, Kim EK, Jin HO, Kim HA, Lee JK, Koh JS, Seol H, Kim JI, Park IC, Noh WC. S6K1 inhibition enhances tamoxifen-induced cell death in MCF-7 cells through translational inhibition of Mcl-1 and survivin. Cell Biol Toxicol 2013; 29:273-82. [PMID: 23942996 DOI: 10.1007/s10565-013-9253-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 07/30/2013] [Indexed: 10/26/2022]
Abstract
S6 kinase 1 (S6K1) was suggested to be a marker for endocrine therapy resistance in breast cancer. We examined whether tamoxifen's effect can be modulated by S6K1 inhibition. S6K1 inhibition by PF4708671, a selective inhibitor of S6K1, acts synergistically with tamoxifen in S6K1-high MCF-7 cells. Similarly, the knockdown of S6K1 with small interfering RNA (siRNA) significantly sensitized MCF-7 cells to tamoxifen. Inhibition of S6K1 by PF4708671 led to a marked decrease in the expression levels of the anti-apoptotic proteins Mcl-1 and survivin, which was not related to mRNA levels. In addition, suppression of Mcl-1 or survivin, using specific siRNA, further enhanced cell sensitivity to tamoxifen. These results showed that inhibition of S6K1 acts synergistically with tamoxifen, via translational modulation of Mcl-1 and survivin. Based on these findings, we propose that targeting S6K1 may be an effective strategy to overcome tamoxifen resistance in breast cancer.
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Affiliation(s)
- Sung-Eun Hong
- Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, 215-4 Gongneung-dong, Nowon-gu, Seoul, 139-706, Republic of Korea.
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Martin LA, André F, Campone M, Bachelot T, Jerusalem G. mTOR inhibitors in advanced breast cancer: ready for prime time? Cancer Treat Rev 2013; 39:742-52. [PMID: 23557794 DOI: 10.1016/j.ctrv.2013.02.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 02/15/2013] [Accepted: 02/19/2013] [Indexed: 12/17/2022]
Abstract
Current therapeutic approaches for advanced breast cancer frequently target receptors mediating cell survival and proliferation, such as the estrogen receptor and/or progesterone receptor and human epidermal growth factor receptor-2. Although these approaches are effective for many patients, treatment resistance is common. Therefore, new treatment approaches are needed for patients with advanced breast cancer. Mammalian target of rapamycin is a highly conserved serine-threonine kinase that acts as a major signaling hub that integrates and synergizes with cellular proliferation, survival, and/or motility signals mediated by estrogen receptor, human epidermal growth factor receptor-2, and other receptor tyrosine kinases. Dysregulation of mammalian target of rapamycin signaling occurs in various tumor types, including breast cancer, and has been associated with cancer pathogenesis, disease progression, and treatment resistance. Recent clinical trials show that combined inhibition of mammalian target of rapamycin and estrogen receptor represents an effective strategy for treating hormone receptor-positive advanced breast cancer progressing on nonsteroidal aromatase inhibitor therapy, and data from ongoing trials combining mammalian target of rapamycin inhibition with human epidermal growth factor receptor-2-targeted therapy are awaited. This review focuses on the molecular rationale underlying strategies to enhance sensitivity to treatment in hormone receptor-positive and human epidermal growth factor receptor-2-positive advanced breast cancer, the clinical efficacy of such approaches, and future perspectives.
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Affiliation(s)
- Lesley-Ann Martin
- Breakthrough Breast Cancer Centre, Institute of Cancer Research, London, United Kingdom.
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Inhibition of S6K1 enhances glucose deprivation-induced cell death via downregulation of anti-apoptotic proteins in MCF-7 breast cancer cells. Biochem Biophys Res Commun 2013; 432:123-8. [DOI: 10.1016/j.bbrc.2013.01.074] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 01/19/2013] [Indexed: 02/04/2023]
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LoRusso PM. Mammalian target of rapamycin as a rational therapeutic target for breast cancer treatment. Oncology 2012; 84:43-56. [PMID: 23128843 DOI: 10.1159/000343063] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 08/27/2012] [Indexed: 12/16/2022]
Abstract
Therapies directed at endocrine receptors and human epidermal growth factor receptor 2 are important treatment options for patients with breast cancer; however, drug resistance and subsequent disease progression in patients with advanced disease is inevitable. The mammalian target of rapamycin (mTOR) is a key regulator of cell growth and proliferation implicated in the cellular processes that lead to the uncontrolled growth of cancer cells. Hence, overactivation of the mTOR pathway may also represent a key process in the development of resistance to these therapies, and interrupting this signaling cascade may alleviate resistance and help restore drug sensitivity. A number of agents that target the mTOR pathway have shown potent antitumorigenic effects in vitro, and several agents have also shown promise in treating patients with breast cancer. Everolimus and temsirolimus are the most clinically advanced agents in this class, with recent data from the BOLERO-2 study indicating significant benefit associated with everolimus when added to endocrine therapy in patients with endocrine therapy-resistant disease. In this review, we consider the translation of mTOR inhibitors from laboratory studies to large clinical trials, driven by a rational understanding of the role of mTOR in the processes that underlie breast cancer tumorigenesis.
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Abstract
The 40S ribosomal S6 kinase 1 (S6K1) is a conserved serine/threonine protein kinase that belongs to the AGC family of protein kinases, which also includes Akt and many others. S6K1 is the principal kinase effector downstream of the mammalian target of rapamycin complex 1 (mTORC1). S6K1 is sensitive to a wide range of signaling inputs, including growth factors, amino acids, energy levels and hypoxia. S6K1 relays these signals to regulate a growing list of substrates and interacting proteins in control of oncogenic processes, such as cell growth and proliferation, cell survival and apoptosis and cell migration and invasion. Several lines of evidence suggest an important role for S6K1 in estrogen receptor (ER)-positive breast cancer. S6K1 directly phosphorylates and activates ERα. Furthermore, S6K1 expression is estrogenically regulated. Therefore, hyperactivation of mTORC1/S6K1 signaling may be closely related to ER-positive status in breast cancer and may be utilized as a marker for prognosis and a therapeutic target.
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Affiliation(s)
- Marina K Holz
- Department of Biology, Stern College for Women of Yeshiva University, New York, NY, USA.
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Beelen K, Zwart W, Linn SC. Can predictive biomarkers in breast cancer guide adjuvant endocrine therapy? Nat Rev Clin Oncol 2012; 9:529-41. [PMID: 22825374 DOI: 10.1038/nrclinonc.2012.121] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Personalized medicine for oestrogen receptor-α (ERα)-positive breast cancer requires predictive biomarkers for broad endocrine resistance as well as biomarkers capable of predicting resistance to a specific agent. In addition, biomarkers could be used to select patients that might benefit from the addition of treatments that do not target ERα. However, biomarker identification studies seem to be far from consistent and identified biomarkers seldom face an introduction into clinical practice. Importantly, most of the studies that seek to identify biomarkers have been performed using material from consecutive series of patients treated with tamoxifen (the most commonly prescribed ERα antagonist). Consequently, the predictive value of any biomarker identified is confounded by its prognostic value. Another important issue is the lack of differentiation between premenopausal and postmenopausal patients with breast cancer. The hormonal environment of a tumour in patients who are premenopausal is intrinsically distinct from those arising in postmenopausal women. Biomarkers of different biological mechanisms might enable the prediction of either broad endocrine resistance or resistance to a specific agent in each of these patient subtypes. Ultimately, improvements to study design are needed to establish the clinical validity of the most promising biomarkers to predict benefit from endocrine therapy.
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Affiliation(s)
- Karin Beelen
- Department of Molecular Pathology, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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