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Gu S, Ngamcherdtrakul W, Reda M, Hu Z, Gray JW, Yantasee W. Lack of acquired resistance in HER2-positive breast cancer cells after long-term HER2 siRNA nanoparticle treatment. PLoS One 2018; 13:e0198141. [PMID: 29879129 PMCID: PMC5991725 DOI: 10.1371/journal.pone.0198141] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 05/14/2018] [Indexed: 01/09/2023] Open
Abstract
Intrinsic and acquired resistance to current HER2 targeted therapies remains a challenge in clinics. We have developed a therapeutic HER2 siRNA delivered using mesoporous silica nanoparticles modified with polymers and conjugated with HER2 targeting antibodies. Our previous studies have shown that our HER2 siRNA nanoparticles could overcome intrinsic and acquired resistance to trastuzumab and lapatinib in HER2-positive breast cancers. In this study, we investigated the effect of long-term (7 months) treatment using our therapeutic HER2 siRNA. Even after the removal of HER2 siRNA, the long-term treated cells grew much slower (67% increase in doubling time) than cells that have not received any treatment. The treated cells did not undergo epithelial-mesenchymal transition or showed enrichment of tumor initiating cells. Unlike trastuzumab and lapatinib, which induced resistance in BT474 cells after 6 months of treatment, HER2 siRNA did not induce resistance to HER2 siRNA, trastuzumab, or lapatinib. HER2 ablation with HER2 siRNA prevented reactivation of HER2 signaling that was observed in cells resistant to lapatinib. Altogether, our results indicate that a HER2 siRNA based therapeutic provides a more durable inhibition of HER2 signaling in vitro and can potentially be more effective than the existing therapeutic monoclonal antibodies and small molecule inhibitors.
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Affiliation(s)
- Shenda Gu
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Worapol Ngamcherdtrakul
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon, United States of America
- PDX Pharmaceuticals, LLC, Portland, Oregon, United States of America
| | - Moataz Reda
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Zhi Hu
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Joe W. Gray
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Wassana Yantasee
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon, United States of America
- PDX Pharmaceuticals, LLC, Portland, Oregon, United States of America
- * E-mail:
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52
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El Shamieh S, Saleh F, Moussa S, Kattan J, Farhat F. RICTOR gene amplification is correlated with metastasis and therapeutic resistance in triple-negative breast cancer. Pharmacogenomics 2018; 19:757-760. [PMID: 29790419 DOI: 10.2217/pgs-2018-0019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Triple-negative breast cancer (TNBC) is characterized by its aggressive behavior, metastasis and lack of targeted therapies. Herein, we discuss the clinical, histopathological and genetic profile of a woman diagnosed with TNBC. Since the patient had no durable response to chemotherapy, a genetic profiling was carried out. Next-generation sequencing analysis of 592 genes showed a missense mutation, p.E545A in PIK3CA, thus the patient was started on the mTOR inhibitor everolimus, in combination with exemestane, which controlled her pain; however, the disease progressed aggressively. More importantly, next-generation sequencing analysis showed a RICTOR gene amplification (eight copies) suggesting that RICTOR promotes the genesis of TNBC. We conclude that determining regulators of RICTOR and furthermore, their inhibitors might decrease cancer cells proliferation rate in patients with TNBC.
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Affiliation(s)
- Said El Shamieh
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | - Fatima Saleh
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | - Salim Moussa
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | - Joseph Kattan
- Department of Hematology-Oncology, Saint Joseph Faculty of Medicine, Beirut, Lebanon
| | - Fadi Farhat
- Department of Hematology-Oncology, Saint Joseph Faculty of Medicine, Beirut, Lebanon.,Department of Hematology & Oncology, Hammoud Hospital UMC, Saida, Lebanon
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53
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Morciano G, Marchi S, Morganti C, Sbano L, Bittremieux M, Kerkhofs M, Corricelli M, Danese A, Karkucinska-Wieckowska A, Wieckowski MR, Bultynck G, Giorgi C, Pinton P. Role of Mitochondria-Associated ER Membranes in Calcium Regulation in Cancer-Specific Settings. Neoplasia 2018; 20:510-523. [PMID: 29626751 PMCID: PMC5916088 DOI: 10.1016/j.neo.2018.03.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/25/2018] [Accepted: 03/01/2018] [Indexed: 12/31/2022] Open
Abstract
Mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) are highly specialized subcellular compartments that are shaped by ER subdomains juxtaposed to mitochondria but are biochemically distinct from pure ER and pure mitochondria. MAMs are enriched in enzymes involved in lipid synthesis and transport, channels for calcium transfer, and proteins with oncogenic/oncosuppressive functions that modulate cell signaling pathways involved in physiological and pathophysiological processes. The term "cancer" denotes a group of disorders that result from uncontrolled cell growth driven by a mixture of genetic and environmental components. Alterations in MAMs are thought to account for the onset as well as the progression and metastasis of cancer and have been a focus of investigation in recent years. In this review, we present the current state of the art regarding MAM-resident proteins and their relevance, alterations, and deregulating functions in different types of cancer from a cell biology and clinical perspective.
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Affiliation(s)
- Giampaolo Morciano
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy; Cecilia Hospital, GVM Care & Research, E.S.: Health Science Foundation, Cotignola, Italy
| | - Saverio Marchi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy
| | - Claudia Morganti
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy
| | - Luigi Sbano
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy
| | - Mart Bittremieux
- KU Leuven, Lab. Molecular and Cellular Signaling, Dept. Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O&N 1 Box 802, Herestraat 49, 3000 Leuven, Belgium
| | - Martijn Kerkhofs
- KU Leuven, Lab. Molecular and Cellular Signaling, Dept. Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O&N 1 Box 802, Herestraat 49, 3000 Leuven, Belgium
| | - Mariangela Corricelli
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy
| | - Alberto Danese
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy
| | | | - Mariusz R Wieckowski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Geert Bultynck
- KU Leuven, Lab. Molecular and Cellular Signaling, Dept. Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O&N 1 Box 802, Herestraat 49, 3000 Leuven, Belgium
| | - Carlotta Giorgi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy.
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy; Cecilia Hospital, GVM Care & Research, E.S.: Health Science Foundation, Cotignola, Italy; CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy.
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Jebali A, Dumaz N. The role of RICTOR downstream of receptor tyrosine kinase in cancers. Mol Cancer 2018; 17:39. [PMID: 29455662 PMCID: PMC5817857 DOI: 10.1186/s12943-018-0794-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 02/01/2018] [Indexed: 12/12/2022] Open
Abstract
The importance of the network defined by phosphatidylinositol-3-kinase (PI3K), AKT and mammalian target of rapamycin (mTOR) downstream of Receptor Tyrosine Kinase (RTK) has been known for many years but the central role of RICTOR (rapamycin-insensitive companion of mTOR) in this pathway is only starting to emerge. RICTOR is critical for mTORC2 (the mammalian target of rapamycin complex 2) kinase activity and as such plays a key role downstream of RTK. Alterations of RICTOR have been identified in a number of cancer cell types and its involvement in tumorigenesis has begun to be unraveled recently. Here, we summarize new research into the biology of RICTOR signaling in cancers focusing on tumors with altered RTK. We show that, as a key signaling node and critical effector of RTKs, RICTOR is becoming a valuable therapeutic target in cancer with altered RTK.
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Affiliation(s)
- Ahlem Jebali
- INSERM, U976, Centre de Recherche sur la Peau, Hôpital Saint Louis, F-75010, 1 avenue Claude Vellefaux, 75475 Paris cedex 10, Paris, France.,Univ Paris Diderot, Sorbonne Paris Cité, UMR 976, F-75010, Paris, France
| | - Nicolas Dumaz
- INSERM, U976, Centre de Recherche sur la Peau, Hôpital Saint Louis, F-75010, 1 avenue Claude Vellefaux, 75475 Paris cedex 10, Paris, France. .,Univ Paris Diderot, Sorbonne Paris Cité, UMR 976, F-75010, Paris, France.
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55
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Werfel TA, Wang S, Jackson MA, Kavanaugh TE, Joly MM, Lee LH, Hicks DJ, Sanchez V, Ericsson PG, Kilchrist KV, Dimobi SC, Sarett SM, Brantley-Sieders DM, Cook RS, Duvall CL. Selective mTORC2 Inhibitor Therapeutically Blocks Breast Cancer Cell Growth and Survival. Cancer Res 2018; 78:1845-1858. [PMID: 29358172 DOI: 10.1158/0008-5472.can-17-2388] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/11/2017] [Accepted: 01/17/2018] [Indexed: 12/12/2022]
Abstract
Small-molecule inhibitors of the mTORC2 kinase (torkinibs) have shown efficacy in early clinical trials. However, the torkinibs under study also inhibit the other mTOR-containing complex mTORC1. While mTORC1/mTORC2 combined inhibition may be beneficial in cancer cells, recent reports describe compensatory cell survival upon mTORC1 inhibition due to loss of negative feedback on PI3K, increased autophagy, and increased macropinocytosis. Genetic models suggest that selective mTORC2 inhibition would be effective in breast cancers, but the lack of selective small-molecule inhibitors of mTORC2 have precluded testing of this hypothesis to date. Here we report the engineering of a nanoparticle-based RNAi therapeutic that can effectively silence the mTORC2 obligate cofactor Rictor. Nanoparticle-based Rictor ablation in HER2-amplified breast tumors was achieved following intratumoral and intravenous delivery, decreasing Akt phosphorylation and increasing tumor cell killing. Selective mTORC2 inhibition in vivo, combined with the HER2 inhibitor lapatinib, decreased the growth of HER2-amplified breast cancers to a greater extent than either agent alone, suggesting that mTORC2 promotes lapatinib resistance, but is overcome by mTORC2 inhibition. Importantly, selective mTORC2 inhibition was effective in a triple-negative breast cancer (TNBC) model, decreasing Akt phosphorylation and tumor growth, consistent with our findings that RICTOR mRNA correlates with worse outcome in patients with basal-like TNBC. Together, our results offer preclinical validation of a novel RNAi delivery platform for therapeutic gene ablation in breast cancer, and they show that mTORC2-selective targeting is feasible and efficacious in this disease setting.Significance: This study describes a nanomedicine to effectively inhibit the growth regulatory kinase mTORC2 in a preclinical model of breast cancer, targeting an important pathogenic enzyme in that setting that has been undruggable to date. Cancer Res; 78(7); 1845-58. ©2018 AACR.
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Affiliation(s)
- Thomas A Werfel
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Shan Wang
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Meredith A Jackson
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Taylor E Kavanaugh
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Meghan Morrison Joly
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Linus H Lee
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Donna J Hicks
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Violeta Sanchez
- Breast Cancer Research Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Paula Gonzalez Ericsson
- Breast Cancer Research Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Kameron V Kilchrist
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Somtochukwu C Dimobi
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Samantha M Sarett
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Dana M Brantley-Sieders
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.,Breast Cancer Research Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Rebecca S Cook
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee. .,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee.,Breast Cancer Research Program, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Craig L Duvall
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.
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mTOR Cross-Talk in Cancer and Potential for Combination Therapy. Cancers (Basel) 2018; 10:cancers10010023. [PMID: 29351204 PMCID: PMC5789373 DOI: 10.3390/cancers10010023] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/15/2018] [Accepted: 01/16/2018] [Indexed: 12/20/2022] Open
Abstract
The mammalian Target of Rapamycin (mTOR) pathway plays an essential role in sensing and integrating a variety of exogenous cues to regulate cellular growth and metabolism, in both physiological and pathological conditions. mTOR functions through two functionally and structurally distinct multi-component complexes, mTORC1 and mTORC2, which interact with each other and with several elements of other signaling pathways. In the past few years, many new insights into mTOR function and regulation have been gained and extensive genetic and pharmacological studies in mice have enhanced our understanding of how mTOR dysfunction contributes to several diseases, including cancer. Single-agent mTOR targeting, mostly using rapalogs, has so far met limited clinical success; however, due to the extensive cross-talk between mTOR and other pathways, combined approaches are the most promising avenues to improve clinical efficacy of available therapeutics and overcome drug resistance. This review provides a brief and up-to-date narrative on the regulation of mTOR function, the relative contributions of mTORC1 and mTORC2 complexes to cancer development and progression, and prospects for mTOR inhibition as a therapeutic strategy.
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57
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Vadla R, Haldar D. Mammalian target of rapamycin complex 2 (mTORC2) controls glycolytic gene expression by regulating Histone H3 Lysine 56 acetylation. Cell Cycle 2018; 17:110-123. [PMID: 29143563 DOI: 10.1080/15384101.2017.1404207] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Metabolic reprogramming is a hallmark of cancer cells, but the mechanisms are not well understood. The mammalian target of rapamycin complex 2 (mTORC2) controls cell growth and proliferation and plays a critical role in metabolic reprogramming in glioma. mTORC2 regulates cellular processes such as cell survival, metabolism, and proliferation by phosphorylation of AGC kinases. Components of mTORC2 are shown to localize to the nucleus, but whether mTORC2 modulates epigenetic modifications to regulate gene expression is not known. Here, we identified histone H3 lysine 56 acetylation (H3K56Ac) is regulated by mTORC2 and show that global H3K56Ac levels were downregulated on mTORC2 knockdown but not on mTORC1 knockdown. mTORC2 promotes H3K56Ac in a tuberous sclerosis complex 1/2 (TSC1/2) mediated signaling pathway. We show that knockdown of sirtuin6 (SIRT6) prevented H3K56 deacetylation in mTORC2 depleted cells. Using glioma model consisting of U87EGFRvIII cells, we established that mTORC2 promotes H3K56Ac in glioma. Finally, we show that mTORC2 regulates the expression of glycolytic genes by regulating H3K56Ac levels at the promoters of these genes in glioma cells and depletion of mTOR leads to increased recruitment of SIRT6 to these promoters. Collectively, these results identify mTORC2 signaling pathway positively promotes H3K56Ac through which it may mediate metabolic reprogramming in glioma.
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Affiliation(s)
- Raghavendra Vadla
- a Centre for DNA Fingerprinting and Diagnostics , Survey Nos. 728, 729, 730 & 734, Opposite Uppal Water Tank, Beside BSNL T E Building, Uppal, Hyderabad 500039 , Ranga Reddy District , India.,b Graduate Studies , Manipal University , Manipal , India
| | - Devyani Haldar
- a Centre for DNA Fingerprinting and Diagnostics , Survey Nos. 728, 729, 730 & 734, Opposite Uppal Water Tank, Beside BSNL T E Building, Uppal, Hyderabad 500039 , Ranga Reddy District , India
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58
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Cao X, Han C, Wen J, Guo X, Zhang K. Nicotine increases apoptosis in HUVECs cultured in high glucose/high fat via Akt ubiquitination and degradation. Clin Exp Pharmacol Physiol 2017; 45:198-204. [PMID: 28963785 DOI: 10.1111/1440-1681.12865] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 09/04/2017] [Accepted: 09/19/2017] [Indexed: 12/12/2022]
Abstract
It is well-documented that nicotine, the main active ingredient in cigarettes, results in endothelial cell injury in numerous diseases. However, whether nicotine plays a crucial role in endothelial cell injury in diabetes and the exact molecular mechanism that mediates this process have not been fully elucidated. The current study aimed to investigate the effects of nicotine on endothelial cell injury in diabetes and the specific molecular mechanism by which it plays a role. Human umbilical vein endothelial cells (HUVECs) were incubated in HG/HF media and treated with nicotine, PYR-41 (a selective ubiquitin E1 inhibitor), Akt-overexpressing adenovirus, or TTC3 and MUL1 shRNA adenovirus. Cell viability was subsequently detected by the CCK8 assay, and apoptosis was examined by caspase-3 cleavage and activity analysis. Compared to the HG/HF incubated group, nicotine incubation significantly decreased cell survival and increased apoptosis. Moreover, nicotine induced Akt degradation via UPS, and Akt overexpression blocked nicotine-induced apoptosis in HUVECs cultured in HG/HF media. Furthermore, the TTC3 and MUL1 shRNA adenovirus dramatically decreased the Akt ubiquitination and apoptosis induced by nicotine. These results indicate that nicotine-induced Akt ubiquitination and degradation occurs through TTC3 and MUL1 and results in a dramatic increase in apoptosis in HUVECs cultured in HG/HF media.
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Affiliation(s)
- Xiaofang Cao
- Center for Disease Control and Prevention of Baoji City, Baoji City, Shanxi Province, China
| | - Chunling Han
- Baoji Maternal and Child Health Hospital, Baoji City, Shanxi Province, China
| | - Jinsuo Wen
- Center for Disease Control and Prevention of Baoji City, Baoji City, Shanxi Province, China
| | - Xiaokun Guo
- Center for Disease Control and Prevention of Baoji City, Baoji City, Shanxi Province, China
| | - Kejian Zhang
- Center for Disease Control and Prevention of Baoji City, Baoji City, Shanxi Province, China
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59
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Dey N, De P, Leyland-Jones B. PI3K-AKT-mTOR inhibitors in breast cancers: From tumor cell signaling to clinical trials. Pharmacol Ther 2017; 175:91-106. [DOI: 10.1016/j.pharmthera.2017.02.037] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Morrison Joly M, Williams MM, Hicks DJ, Jones B, Sanchez V, Young CD, Sarbassov DD, Muller WJ, Brantley-Sieders D, Cook RS. Two distinct mTORC2-dependent pathways converge on Rac1 to drive breast cancer metastasis. Breast Cancer Res 2017; 19:74. [PMID: 28666462 PMCID: PMC5493112 DOI: 10.1186/s13058-017-0868-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/14/2017] [Indexed: 02/06/2023] Open
Abstract
Background The importance of the mTOR complex 2 (mTORC2) signaling complex in tumor progression is becoming increasingly recognized. HER2-amplified breast cancers use Rictor/mTORC2 signaling to drive tumor formation, tumor cell survival and resistance to human epidermal growth factor receptor 2 (HER2)-targeted therapy. Cell motility, a key step in the metastatic process, can be activated by mTORC2 in luminal and triple negative breast cancer cell lines, but its role in promoting metastases from HER2-amplified breast cancers is not yet clear. Methods Because Rictor is an obligate cofactor of mTORC2, we genetically engineered Rictor ablation or overexpression in mouse and human HER2-amplified breast cancer models for modulation of mTORC2 activity. Signaling through mTORC2-dependent pathways was also manipulated using pharmacological inhibitors of mTOR, Akt, and Rac. Signaling was assessed by western analysis and biochemical pull-down assays specific for Rac-GTP and for active Rac guanine nucleotide exchange factors (GEFs). Metastases were assessed from spontaneous tumors and from intravenously delivered tumor cells. Motility and invasion of cells was assessed using Matrigel-coated transwell assays. Results We found that Rictor ablation potently impaired, while Rictor overexpression increased, metastasis in spontaneous and intravenously seeded models of HER2-overexpressing breast cancers. Additionally, migration and invasion of HER2-amplified human breast cancer cells was diminished in the absence of Rictor, or upon pharmacological mTOR kinase inhibition. Active Rac1 was required for Rictor-dependent invasion and motility, which rescued invasion/motility in Rictor depleted cells. Rictor/mTORC2-dependent dampening of the endogenous Rac1 inhibitor RhoGDI2, a factor that correlated directly with increased overall survival in HER2-amplified breast cancer patients, promoted Rac1 activity and tumor cell invasion/migration. The mTORC2 substrate Akt did not affect RhoGDI2 dampening, but partially increased Rac1 activity through the Rac-GEF Tiam1, thus partially rescuing cell invasion/motility. The mTORC2 effector protein kinase C (PKC)α did rescue Rictor-mediated RhoGDI2 downregulation, partially rescuing Rac-guanosine triphosphate (GTP) and migration/motility. Conclusion These findings suggest that mTORC2 uses two coordinated pathways to activate cell invasion/motility, both of which converge on Rac1. Akt signaling activates Rac1 through the Rac-GEF Tiam1, while PKC signaling dampens expression of the endogenous Rac1 inhibitor, RhoGDI2. Electronic supplementary material The online version of this article (doi:10.1186/s13058-017-0868-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Meghan Morrison Joly
- Department of Cancer Biology, Vanderbilt University School of Medicine, 2220 Pierce Avenue, Rm 749 Preston Research Building, Nashville, TN, 37232, USA
| | - Michelle M Williams
- Department of Cancer Biology, Vanderbilt University School of Medicine, 2220 Pierce Avenue, Rm 749 Preston Research Building, Nashville, TN, 37232, USA
| | - Donna J Hicks
- Department of Cancer Biology, Vanderbilt University School of Medicine, 2220 Pierce Avenue, Rm 749 Preston Research Building, Nashville, TN, 37232, USA
| | - Bayley Jones
- Department of Cancer Biology, Vanderbilt University School of Medicine, 2220 Pierce Avenue, Rm 749 Preston Research Building, Nashville, TN, 37232, USA
| | - Violeta Sanchez
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Christian D Young
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Dos D Sarbassov
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - William J Muller
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Dana Brantley-Sieders
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Rebecca S Cook
- Department of Cancer Biology, Vanderbilt University School of Medicine, 2220 Pierce Avenue, Rm 749 Preston Research Building, Nashville, TN, 37232, USA.
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61
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Kim LC, Cook RS, Chen J. mTORC1 and mTORC2 in cancer and the tumor microenvironment. Oncogene 2017; 36:2191-2201. [PMID: 27748764 PMCID: PMC5393956 DOI: 10.1038/onc.2016.363] [Citation(s) in RCA: 288] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/04/2016] [Accepted: 08/15/2016] [Indexed: 02/06/2023]
Abstract
The mammalian target of rapamycin (mTOR) is a crucial signaling node that integrates environmental cues to regulate cell survival, proliferation and metabolism, and is often deregulated in human cancer. mTOR kinase acts in two functionally distinct complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), whose activities and substrate specificities are regulated by complex co-factors. Deregulation of this centralized signaling pathway has been associated with a variety of human diseases including diabetes, neurodegeneration and cancer. Although mTORC1 signaling has been extensively studied in cancer, recent discoveries indicate a subset of human cancers harboring amplifications in mTORC2-specific genes as the only actionable genomic alterations, suggesting a distinct role for mTORC2 in cancer as well. This review will summarize recent advances in dissecting the relative contributions of mTORC1 versus mTORC2 in cancer, their role in tumor-associated blood vessels and tumor immunity, and provide an update on mTOR inhibitors.
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Affiliation(s)
- Laura C. Kim
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232
| | - Rebecca S. Cook
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232
- Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, TN 37232
| | - Jin Chen
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232
- Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, TN 37232
- Department of Cell & Developmental Biology, Vanderbilt University, Nashville, TN 37232
- Veterans Affairs Medical Center, Tennessee Valley Healthcare System, Nashville, TN 37212
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62
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Liao P, Wang W, Li Y, Wang R, Jin J, Pang W, Chen Y, Shen M, Wang X, Jiang D, Pang J, Liu M, Lin X, Feng XH, Wang P, Ge X. Palmitoylated SCP1 is targeted to the plasma membrane and negatively regulates angiogenesis. eLife 2017; 6:e22058. [PMID: 28440748 PMCID: PMC5404917 DOI: 10.7554/elife.22058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 03/25/2017] [Indexed: 12/12/2022] Open
Abstract
SCP1 as a nuclear transcriptional regulator acts globally to silence neuronal genes and to affect the dephosphorylation of RNA Pol ll. However, we report the first finding and description of SCP1 as a plasma membrane-localized protein in various cancer cells using EGFP- or other epitope-fused SCP1. Membrane-located SCP1 dephosphorylates AKT at serine 473, leading to the abolishment of serine 473 phosphorylation that results in suppressed angiogenesis and a decreased risk of tumorigenesis. Consistently, we observed increased AKT phosphorylation and angiogenesis followed by enhanced tumorigenesis in Ctdsp1 (which encodes SCP1) gene - knockout mice. Importantly, we discovered that the membrane localization of SCP1 is crucial for impeding angiogenesis and tumor growth, and this localization depends on palmitoylation of a conserved cysteine motif within its NH2 terminus. Thus, our study discovers a novel mechanism underlying SCP1 shuttling between the plasma membrane and nucleus, which constitutes a unique pathway in transducing AKT signaling that is closely linked to angiogenesis and tumorigenesis.
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Affiliation(s)
- Peng Liao
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Weichao Wang
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Yu Li
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Rui Wang
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Jiali Jin
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Weijuan Pang
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Yunfei Chen
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Mingyue Shen
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Xinbo Wang
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Dongyang Jiang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jinjiang Pang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
| | - Mingyao Liu
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Xia Lin
- Department of Surgery, Baylor College of Medicine, Houston, United States
| | - Xin-Hua Feng
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Zhejiang, China
| | - Ping Wang
- Department of Central Laboratory, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
- School of Life Science and Technology, Tongji University, Shanghai, China
| | - Xin Ge
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
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Regulation of PI3K effector signalling in cancer by the phosphoinositide phosphatases. Biosci Rep 2017; 37:BSR20160432. [PMID: 28082369 PMCID: PMC5301276 DOI: 10.1042/bsr20160432] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 12/24/2022] Open
Abstract
Class I phosphoinositide 3-kinase (PI3K) generates phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) at the plasma membrane in response to growth factors, activating a signalling cascade that regulates many cellular functions including cell growth, proliferation, survival, migration and metabolism. The PI3K pathway is commonly dysregulated in human cancer, and drives tumorigenesis by promoting aberrant cell growth and transformation. PtdIns(3,4,5)P3 facilitates the activation of many pleckstrin homology (PH) domain-containing proteins including the serine/threonine kinase AKT. There are three AKT isoforms that are frequently hyperactivated in cancer through mutation, amplification or dysregulation of upstream regulatory proteins. AKT isoforms have converging and opposing functions in tumorigenesis. PtdIns(3,4,5)P3 signalling is degraded and terminated by phosphoinositide phosphatases such as phosphatase and tensin homologue (PTEN), proline-rich inositol polyphosphate 5-phosphatase (PIPP) (INPP5J) and inositol polyphosphate 4-phosphatase type II (INPP4B). PtdIns(3,4,5)P3 is rapidly hydrolysed by PIPP to generate phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P2), which is further hydrolysed by INPP4B to form phosphatidylinositol 3-phosphate (PtdIns3P). PtdIns(3,4)P2 and PtdIns3P are also important signalling molecules; PtdIns(3,4)P2 together with PtdIns(3,4,5)P3 are required for maximal AKT activation and PtdIns3P activates PI3K-dependent serum and glucocorticoid-regulated kinase (SGK3) signalling. Loss of Pten, Pipp or Inpp4b expression or function promotes tumour growth in murine cancer models through enhanced AKT isoform-specific signalling. INPP4B inhibits PtdIns(3,4)P2-mediated AKT activation in breast and prostate cancer; however, INPP4B expression is increased in acute myeloid leukaemia (AML), melanoma and colon cancer where it paradoxically promotes cell proliferation, transformation and/or drug resistance. This review will discuss how PTEN, PIPP and INPP4B distinctly regulate PtdIns(3,4,5)P3 signalling downstream of PI3K and how dysregulation of these phosphatases affects cancer outcomes.
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