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Han D, Spehar JM, Richardson DS, Leelananda S, Chakravarthy P, Grecco S, Reardon J, Stover DG, Bennett C, Sizemore GM, Li Z, Lindert S, Sizemore ST. The RAL Small G Proteins Are Clinically Relevant Targets in Triple Negative Breast Cancer. Cancers (Basel) 2024; 16:3043. [PMID: 39272901 DOI: 10.3390/cancers16173043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/16/2024] [Accepted: 08/29/2024] [Indexed: 09/15/2024] Open
Abstract
Breast cancer (BC) is the most frequent cancer and second-leading cause of cancer deaths in women in the United States. While RAS mutations are infrequent in BC, triple-negative (TN) and HER2-positive (HER2+) BC both exhibit increased RAS activity. Here, we tested the RAS effectors RALA and RALB, which are overexpressed in BC, as tractable molecular targets in these subtypes. While analysis of the breast cancer patient sample data suggests that the RALs are associated with poor outcome in both TNBC and HER2+ BC, our in vivo and in vitro experimental findings revealed the RALs to be essential in only the TNBC cell lines. While testing the response of the BC cell lines to the RAL inhibitors RBC8 and BQU57, we observed no correlation between drug efficacy and cell line dependency on RAL expression for survival, suggesting that these compounds kill via off-target effects. Finally, we report the discovery of a new small molecule inhibitor, OSURALi, which exhibits strong RAL binding, effectively inhibits RAL activation, and is significantly more toxic to RAL-dependent TNBC cells than RAL-independent HER2+ and normal cell lines. These results support the RALs as viable molecular targets in TNBC and the further investigation of OSURALi as a therapeutic agent.
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Affiliation(s)
- David Han
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Jonathan M Spehar
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Dillon S Richardson
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | | | - Prathik Chakravarthy
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Samantha Grecco
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Jesse Reardon
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Daniel G Stover
- Department of Internal Medicine, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Chad Bennett
- Drug Development Institute, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Gina M Sizemore
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Zaibo Li
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Steven T Sizemore
- Department of Radiation Oncology, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
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Phadke MS, Smalley KS. Targeting NRAS Mutations in Advanced Melanoma. J Clin Oncol 2023; 41:2661-2664. [PMID: 36947724 PMCID: PMC10414701 DOI: 10.1200/jco.23.00205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/14/2023] [Accepted: 02/17/2023] [Indexed: 03/24/2023] Open
Affiliation(s)
- Manali S. Phadke
- Department of Tumor Biology, Moffitt Cancer Center & Research Institute, Tampa, FL
| | - Keiran S.M. Smalley
- Department of Tumor Biology, Moffitt Cancer Center & Research Institute, Tampa, FL
- Department of Cutaneous Oncology, Moffitt Cancer Center & Research Institute, Tampa, FL
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3
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Antitumor Effects of Ral-GTPases Downregulation in Glioblastoma. Int J Mol Sci 2022; 23:ijms23158199. [PMID: 35897776 PMCID: PMC9330696 DOI: 10.3390/ijms23158199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/19/2022] [Accepted: 07/22/2022] [Indexed: 12/20/2022] Open
Abstract
Glioblastoma (GBM) is the most common tumor in the central nervous system in adults. This neoplasia shows a high capacity of growth and spreading to the surrounding brain tissue, hindering its complete surgical resection. Therefore, the finding of new antitumor therapies for GBM treatment is a priority. We have previously described that cyclin D1-CDK4 promotes GBM dissemination through the activation of the small GTPases RalA and RalB. In this paper, we show that RalB GTPase is upregulated in primary GBM cells. We found that the downregulation of Ral GTPases, mainly RalB, prevents the proliferation of primary GBM cells and triggers a senescence-like response. Moreover, downregulation of RalA and RalB reduces the viability of GBM cells growing as tumorspheres, suggesting a possible role of these GTPases in the survival of GBM stem cells. By using mouse subcutaneous xenografts, we have corroborated the role of RalB in GBM growth in vivo. Finally, we have observed that the knockdown of RalB also inhibits cell growth in temozolomide-resistant GBM cells. Overall, our work shows that GBM cells are especially sensitive to Ral-GTPase availability. Therefore, we propose that the inactivation of Ral-GTPases may be a reliable therapeutic approach to prevent GBM progression and recurrence.
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Richardson DS, Spehar JM, Han DT, Chakravarthy PA, Sizemore ST. The RAL Enigma: Distinct Roles of RALA and RALB in Cancer. Cells 2022; 11:cells11101645. [PMID: 35626682 PMCID: PMC9139244 DOI: 10.3390/cells11101645] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 11/16/2022] Open
Abstract
RALA and RALB are highly homologous small G proteins belonging to the RAS superfamily. Like other small GTPases, the RALs are molecular switches that can be toggled between inactive GDP-bound and active GTP-bound states to regulate diverse and critical cellular functions such as vesicle trafficking, filopodia formation, mitochondrial fission, and cytokinesis. The RAL paralogs are activated and inactivated by a shared set of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) and utilize similar sets of downstream effectors. In addition to their important roles in normal cell biology, the RALs are known to be critical mediators of cancer cell survival, invasion, migration, and metastasis. However, despite their substantial similarities, the RALs often display striking functional disparities in cancer. RALA and RALB can have redundant, unique, or even antagonistic functions depending on cancer type. The molecular basis for these discrepancies remains an important unanswered question in the field of cancer biology. In this review we examine the functions of the RAL paralogs in normal cellular physiology and cancer biology with special consideration provided to situations where the roles of RALA and RALB are non-redundant.
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Rio-Vilariño A, del Puerto-Nevado L, García-Foncillas J, Cebrián A. Ras Family of Small GTPases in CRC: New Perspectives for Overcoming Drug Resistance. Cancers (Basel) 2021; 13:3757. [PMID: 34359657 PMCID: PMC8345156 DOI: 10.3390/cancers13153757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 12/11/2022] Open
Abstract
Colorectal cancer remains among the cancers with the highest incidence, prevalence, and mortality worldwide. Although the development of targeted therapies against the EGFR and VEGFR membrane receptors has considerably improved survival in these patients, the appearance of resistance means that their success is still limited. Overactivation of several members of the Ras-GTPase family is one of the main actors in both tumour progression and the lack of response to cytotoxic and targeted therapies. This fact has led many resources to be devoted over the last decades to the development of targeted therapies against these proteins. However, they have not been as successful as expected in their move to the clinic so far. In this review, we will analyse the role of these Ras-GTPases in the emergence and development of colorectal cancer and their relationship with resistance to targeted therapies, as well as the status and new advances in the design of targeted therapies against these proteins and their possible clinical implications.
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Affiliation(s)
| | | | - Jesús García-Foncillas
- Translational Oncology Division, Hospital Universitario Fundación Jimenez Diaz, 28040 Madrid, Spain; (A.R.-V.); (L.d.P.-N.)
| | - Arancha Cebrián
- Translational Oncology Division, Hospital Universitario Fundación Jimenez Diaz, 28040 Madrid, Spain; (A.R.-V.); (L.d.P.-N.)
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Apken LH, Oeckinghaus A. The RAL signaling network: Cancer and beyond. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 361:21-105. [PMID: 34074494 DOI: 10.1016/bs.ircmb.2020.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The RAL proteins RALA and RALB belong to the superfamily of small RAS-like GTPases (guanosine triphosphatases). RAL GTPases function as molecular switches in cells by cycling through GDP- and GTP-bound states, a process which is regulated by several guanine exchange factors (GEFs) and two heterodimeric GTPase activating proteins (GAPs). Since their discovery in the 1980s, RALA and RALB have been established to exert isoform-specific functions in central cellular processes such as exocytosis, endocytosis, actin organization and gene expression. Consequently, it is not surprising that an increasing number of physiological functions are discovered to be controlled by RAL, including neuronal plasticity, immune response, and glucose and lipid homeostasis. The critical importance of RAL GTPases for oncogenic RAS-driven cellular transformation and tumorigenesis still attracts most research interest. Here, RAL proteins are key drivers of cell migration, metastasis, anchorage-independent proliferation, and survival. This chapter provides an overview of normal and pathological functions of RAL GTPases and summarizes the current knowledge on the involvement of RAL in human disease as well as current therapeutic targeting strategies. In particular, molecular mechanisms that specifically control RAL activity and RAL effector usage in different scenarios are outlined, putting a spotlight on the complexity of the RAL GTPase signaling network and the emerging theme of RAS-independent regulation and relevance of RAL.
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Affiliation(s)
- Lisa H Apken
- Institute of Molecular Tumor Biology, Faculty of Medicine, University of Münster, Münster, Germany
| | - Andrea Oeckinghaus
- Institute of Molecular Tumor Biology, Faculty of Medicine, University of Münster, Münster, Germany.
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Leng HJ, Wang YT, He XH, Xia HL, Xu PS, Xiang P, He QQ, Zhan G, Huang W. Design and Efficient Synthesis of RalA Inhibitors Containing the Dihydro-α-carboline Scaffold. ChemMedChem 2020; 16:851-859. [PMID: 33244883 DOI: 10.1002/cmdc.202000722] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/02/2020] [Indexed: 11/07/2022]
Abstract
Ras-related protein RalA is a member of the Ras small GTPases superfamily. Its activation plays an important role in regulating tumor initiation, invasion, migration, and metastasis. In this study, we designed a new type of RalA inhibitor containing a dihydro-α-carboline scaffold. The structurally new dihydro-α-carboline derivatives could be efficiently synthesized in good yields through a newly developed three-component [3+2+1] cyclization reaction. Evaluation of the biological activity showed that some of the dihydro-α-carboline derivatives can inhibit RalA/B and proliferative activities of NSCLC cell lines. The 4-(pyridin-3-yl)-dihydro-α-carboline compound (3 o) was found to be the most potent derivative, with IC50 values of 0.43±0.03, 0.64±0.07, 0.93±0.10, and 1.54±0.15 μM against A549, H1299, H460, and H1975 cells, respectively. Mechanism investigation suggested that 3 o inhibits the RalA/B activation of A549, down-regulates Bcl-2, stimulates cytochrome c and PARP cleavage, and induces cell apoptosis. A molecular docking study revealed that 3 o can form stable hydrogen bonds with residues of RalA. Moreover, amide-π and alkyl-π interactions also contributed to the affinity between 3 o and RalA.
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Affiliation(s)
- Hai-Jun Leng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Hospital of Chengdu University of Traditional Chinese Medicine, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, 611137, Chengdu, China.,Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, 610052, Chengdu, China
| | - Yu-Ting Wang
- State Key Laboratory of Southwestern Chinese Medicine Resources, Hospital of Chengdu University of Traditional Chinese Medicine, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, 611137, Chengdu, China
| | - Xiang-Hong He
- State Key Laboratory of Southwestern Chinese Medicine Resources, Hospital of Chengdu University of Traditional Chinese Medicine, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, 611137, Chengdu, China
| | - Hou-Lin Xia
- State Key Laboratory of Southwestern Chinese Medicine Resources, Hospital of Chengdu University of Traditional Chinese Medicine, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, 611137, Chengdu, China
| | - Peng-Shuai Xu
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, 610052, Chengdu, China
| | - Peng Xiang
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, 610052, Chengdu, China
| | - Qing-Qing He
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, School of Pharmacy, Sichuan Industrial Institute of Antibiotics, Chengdu University, 610052, Chengdu, China
| | - Gu Zhan
- State Key Laboratory of Southwestern Chinese Medicine Resources, Hospital of Chengdu University of Traditional Chinese Medicine, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, 611137, Chengdu, China
| | - Wei Huang
- State Key Laboratory of Southwestern Chinese Medicine Resources, Hospital of Chengdu University of Traditional Chinese Medicine, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, 611137, Chengdu, China
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8
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Brito C, Barral DC, Pojo M. Subversion of Ras Small GTPases in Cutaneous Melanoma Aggressiveness. Front Cell Dev Biol 2020; 8:575223. [PMID: 33072757 PMCID: PMC7538714 DOI: 10.3389/fcell.2020.575223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/28/2020] [Indexed: 12/25/2022] Open
Abstract
The rising incidence and mortality rate associated with the metastatic ability of cutaneous melanoma represent a major public health concern. Cutaneous melanoma is one of the most invasive human cancers, but the molecular mechanisms are poorly understood. Moreover, currently available therapies are not efficient in avoiding melanoma lethality. In this context, new biomarkers of prognosis, metastasis, and response to therapy are necessary to better predict the disease outcome. Additionally, the knowledge about the molecular alterations and dysregulated pathways involved in melanoma metastasis may provide new therapeutic targets. Members of the Ras superfamily of small GTPases regulate various essential cellular activities, from signaling to membrane traffic and cytoskeleton dynamics. Therefore, it is not surprising that they are differentially expressed, and their functions subverted in several types of cancer, including melanoma. Indeed, Ras small GTPases were found to regulate melanoma progression and invasion. Hence, a better understanding of the mechanisms regulated by Ras small GTPases that are involved in melanoma tumorigenesis and progression may provide new therapeutic strategies to block these processes. Here, we review the current knowledge on the role of Ras small GTPases in melanoma aggressiveness and the molecular mechanisms involved. Furthermore, we summarize the known involvement of these proteins in melanoma metastasis and how these players influence the response to therapy.
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Affiliation(s)
- Cheila Brito
- Unidade de Investigação em Patobiologia Molecular (UIPM) do Instituto Português de Oncologia de Lisboa Francisco Gentil E.P.E., Lisbon, Portugal
| | - Duarte C Barral
- CEDOC, Faculdade de Ciências Médicas, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Marta Pojo
- Unidade de Investigação em Patobiologia Molecular (UIPM) do Instituto Português de Oncologia de Lisboa Francisco Gentil E.P.E., Lisbon, Portugal
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9
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Seibold M, Stühmer T, Kremer N, Mottok A, Scholz CJ, Schlosser A, Leich E, Holzgrabe U, Brünnert D, Barrio S, Kortüm KM, Solimando AG, Chatterjee M, Einsele H, Rosenwald A, Bargou RC, Steinbrunn T. RAL GTPases mediate multiple myeloma cell survival and are activated independently of oncogenic RAS. Haematologica 2020; 105:2316-2326. [PMID: 33054056 PMCID: PMC7556628 DOI: 10.3324/haematol.2019.223024] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 10/10/2019] [Indexed: 11/17/2022] Open
Abstract
Oncogenic RAS provides crucial survival signaling for up to half of multiple myeloma cases, but has so far remained a clinically undruggable target. RAL is a member of the RAS superfamily of small GTPases and is considered to be a potential mediator of oncogenic RAS signaling. In primary multiple myeloma, we found RAL to be overexpressed in the vast majority of samples when compared with pre-malignant monoclonal gammopathy of undetermined significance or normal plasma cells. We analyzed the functional effects of RAL abrogation in myeloma cell lines and found that RAL is a critical mediator of survival. RNAi-mediated knockdown of RAL resulted in rapid induction of tumor cell death, an effect which was independent from signaling via mitogen-activated protein kinase, but appears to be partially dependent on Akt activity. Notably, RAL activation was not correlated with the presence of activating RAS mutations and remained unaffected by knockdown of oncogenic RAS. Furthermore, transcriptome analysis yielded distinct RNA expression signatures after knockdown of either RAS or RAL. Combining RAL depletion with clinically relevant anti-myeloma agents led to enhanced rates of cell death. Our data demonstrate that RAL promotes multiple myeloma cell survival independently of oncogenic RAS and, thus, this pathway represents a potential therapeutic target in its own right.
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Affiliation(s)
- Marcel Seibold
- Department of Medicine II, University Hospital of Würzburg, Würzburg, Germany
| | - Thorsten Stühmer
- Comprehensive Cancer Center Mainfranken, Chair of Translational Oncology, University Hospital of Würzburg, Würzburg, Germany
| | - Nadine Kremer
- Comprehensive Cancer Center Mainfranken, Chair of Translational Oncology, University Hospital of Würzburg, Würzburg, Germany
| | - Anja Mottok
- Institute of Human Genetics, University of Ulm, Ulm, Germany
| | | | - Andreas Schlosser
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Ellen Leich
- Institute of Pathology, University of Würzburg, Würzburg, Germany
| | - Ulrike Holzgrabe
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Würzburg, Germany
| | - Daniela Brünnert
- Comprehensive Cancer Center Mainfranken, Chair of Translational Oncology, University Hospital of Würzburg, Würzburg, Germany
| | - Santiago Barrio
- Hematology Department, Hospital 12 de Octubre, Complutense University, Madrid, Spain
| | - K. Martin Kortüm
- Department of Medicine II, University Hospital of Würzburg, Würzburg, Germany
| | | | - Manik Chatterjee
- Comprehensive Cancer Center Mainfranken, Chair of Translational Oncology, University Hospital of Würzburg, Würzburg, Germany
| | - Hermann Einsele
- Department of Medicine II, University Hospital of Würzburg, Würzburg, Germany
| | | | - Ralf C. Bargou
- Comprehensive Cancer Center Mainfranken, Chair of Translational Oncology, University Hospital of Würzburg, Würzburg, Germany
| | - Torsten Steinbrunn
- Department of Medicine II, University Hospital of Würzburg, Würzburg, Germany
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10
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Xue D, Cheng P, Jiang J, Ren Y, Wu D, Chen W. Systemic Analysis of the Prognosis-Related RNA Alternative Splicing Signals in Melanoma. Med Sci Monit 2020; 26:e921133. [PMID: 32199022 PMCID: PMC7111138 DOI: 10.12659/msm.921133] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 01/13/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Alternative splicing (AS), the mechanism underlying the occurrence of protein diversity, may result in cancer genesis and development when it becomes out of control, as suggested by a growing number of studies. However, systemically analyze of AS events at the genome-wide level for skin cutaneous melanoma (SKCM) is still in a preliminary phase. This study aimed to systemically analyze the bioinformatics of the AS events at a genome-wide level using The Cancer Genome Atlas (TCGA) SKCM data. MATERIAL AND METHODS The SpliceSeq tool was used to analyze the AS profiles for SKCM clinical specimens from the TCGA database. The association between AS events and overall survival was analyzed by Cox regression analysis. AS event intersections and a gene interaction network were established by UpSet plot. A multivariate survival model was used to establish a feature genes prognosis model. RESULTS A total of 103 SKCM patients with full clinical parameters available were included in this study. We established an AS network that investigated the relationship between AS events and clinical prognosis information. Furthermore, 4 underlying feature genes of SKCM (MCF2L, HARS, TFR2, and RALGPS1) were found in the AS network. We performed function analysis as well as correlation analysis of AS events with gene expression. Using the multivariate survival model, we further confirmed the 4 genes that impacted the classifying SKCM prognosis at the level of AS events as well as gene expression, especially in wild-type SKCM. CONCLUSIONS AS events could be ideal indicators for SKCM prognosis. The key feature gene MCF2L played an important role in wild-type SKCM.
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Affiliation(s)
- Dan Xue
- Department of Plastic Surgery, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Pu Cheng
- Department of Gynecology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Jinxin Jiang
- Department of Surgical Oncology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Yunqing Ren
- Department of Dermatology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Dang Wu
- Department of Radiation Oncology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Wuzhen Chen
- Department of Surgical Oncology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
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11
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Savoia P, Fava P, Casoni F, Cremona O. Targeting the ERK Signaling Pathway in Melanoma. Int J Mol Sci 2019; 20:ijms20061483. [PMID: 30934534 PMCID: PMC6472057 DOI: 10.3390/ijms20061483] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 03/17/2019] [Accepted: 03/19/2019] [Indexed: 12/24/2022] Open
Abstract
The discovery of the role of the RAS/RAF/MEK/ERK pathway in melanomagenesis and its progression have opened a new era in the treatment of this tumor. Vemurafenib was the first specific kinase inhibitor approved for therapy of advanced melanomas harboring BRAF-activating mutations, followed by dabrafenib and encorafenib. However, despite the excellent results of first-generation kinase inhibitors in terms of response rate, the average duration of the response was short, due to the onset of genetic and epigenetic resistance mechanisms. The combination therapy with MEK inhibitors is an excellent strategy to circumvent drug resistance, with the additional advantage of reducing side effects due to the paradoxical reactivation of the MAPK pathway. The recent development of RAS and extracellular signal-related kinases (ERK) inhibitors promises to add new players for the ultimate suppression of this signaling pathway and the control of pathway-related drug resistance. In this review, we analyze the pharmacological, preclinical, and clinical trial data of the various MAPK pathway inhibitors, with a keen interest for their clinical applicability in the management of advanced melanoma.
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Affiliation(s)
- Paola Savoia
- Department of Health Science, University of Eastern Piedmont, via Solaroli 17, 28100 Novara, Italy.
| | - Paolo Fava
- Section of Dermatology, Department of Medical Science, University of Turin, 10124 Turin, Italy.
| | - Filippo Casoni
- San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milano, Italy.
- Università Vita Salute San Raffaele, via Olgettina 58, 20132 Milano, Italy.
| | - Ottavio Cremona
- San Raffaele Scientific Institute, Division of Neuroscience, via Olgettina 58, 20132 Milano, Italy.
- Università Vita Salute San Raffaele, via Olgettina 58, 20132 Milano, Italy.
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12
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Yu X, Dobrikov M, Keir ST, Gromeier M, Pastan IH, Reisfeld R, Bigner DD, Chandramohan V. Synergistic antitumor effects of 9.2.27-PE38KDEL and ABT-737 in primary and metastatic brain tumors. PLoS One 2019; 14:e0210608. [PMID: 30625226 PMCID: PMC6326518 DOI: 10.1371/journal.pone.0210608] [Citation(s) in RCA: 11] [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: 10/11/2018] [Accepted: 12/30/2018] [Indexed: 12/30/2022] Open
Abstract
Standard treatment, unfortunately, yields a poor prognosis for patients with primary or metastatic cancers in the central nervous system, indicating a necessity for novel therapeutic agents. Immunotoxins (ITs) are a class of promising therapeutic candidates produced by fusing antibody fragments with toxin moieties. In this study, we investigated if inherent resistance to IT cytotoxicity can be overcome by rational combination with pro-apoptotic enhancers. Therefore, we combined ITs (9.2.27-PE38KDEL or Mel-14-PE38KDEL) targeting chondroitin sulfate proteoglycan 4 (CSPG4) with a panel of Bcl-2 family inhibitors (ABT-737, ABT-263, ABT-199 [Venetoclax], A-1155463, and S63845) against patient-derived glioblastoma, melanoma, and breast cancer cells/cell lines. In vitro cytotoxicity assays demonstrated that the addition of the ABT compounds, specifically ABT-737, sensitized the different tumors to IT treatment, and improved the IC50 values of 9.2.27-PE38KDEL up to >1,000-fold. Mechanistic studies using 9.2.27-PE38KDEL and ABT-737 revealed that increased levels of intracellular IT, processed (active) exotoxin, and PARP cleavage correlated with the enhanced sensitivity to the combination treatment. Furthermore, we confirmed the synergistic effect of 9.2.27-PE38KDEL and ABT-737 combination therapy in orthotopic GBM xenograft and cerebral melanoma metastasis models in nude mice. Our study defines strategies for overcoming IT resistance and enhancing specific antitumor cytotoxicity in primary and metastatic brain tumors.
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Affiliation(s)
- Xin Yu
- Department of Pathology, Duke University Medical Center, Durham, NC, United States of America
| | - Mikhail Dobrikov
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, United States of America
| | - Stephen T. Keir
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, United States of America
| | - Matthias Gromeier
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, United States of America
| | - Ira H. Pastan
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Ralph Reisfeld
- Department of Immunology and Microbiology, The Scripps Institute, La Jolla, CA, United States of America
| | - Darell D. Bigner
- Department of Pathology, Duke University Medical Center, Durham, NC, United States of America
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, United States of America
| | - Vidyalakshmi Chandramohan
- Department of Pathology, Duke University Medical Center, Durham, NC, United States of America
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, United States of America
- * E-mail:
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13
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Exploring the interactions of the RAS family in the human protein network and their potential implications in RAS-directed therapies. Oncotarget 2018; 7:75810-75826. [PMID: 27713118 PMCID: PMC5342780 DOI: 10.18632/oncotarget.12416] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/15/2016] [Indexed: 12/14/2022] Open
Abstract
RAS proteins are the founding members of the RAS superfamily of GTPases. They are involved in key signaling pathways regulating essential cellular functions such as cell growth and differentiation. As a result, their deregulation by inactivating mutations often results in aberrant cell proliferation and cancer. With the exception of the relatively well-known KRAS, HRAS and NRAS proteins, little is known about how the interactions of the other RAS human paralogs affect cancer evolution and response to treatment. In this study we performed a comprehensive analysis of the relationship between the phylogeny of RAS proteins and their location in the protein interaction network. This analysis was integrated with the structural analysis of conserved positions in available 3D structures of RAS complexes. Our results show that many RAS proteins with divergent sequences are found close together in the human interactome. We found specific conserved amino acid positions in this group that map to the binding sites of RAS with many of their signaling effectors, suggesting that these pairs could share interacting partners. These results underscore the potential relevance of cross-talking in the RAS signaling network, which should be taken into account when considering the inhibitory activity of drugs targeting specific RAS oncoproteins. This study broadens our understanding of the human RAS signaling network and stresses the importance of considering its potential cross-talk in future therapies.
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14
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Inactivation of RASA1 promotes melanoma tumorigenesis via R-Ras activation. Oncotarget 2018; 7:23885-96. [PMID: 26993606 PMCID: PMC5029671 DOI: 10.18632/oncotarget.8127] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 02/28/2016] [Indexed: 11/25/2022] Open
Abstract
Inactivation of Ras GTPase activating proteins (RasGAPs) can activate Ras, increasing the risk for tumor development. Utilizing a melanoma whole genome sequencing (WGS) data from 13 patients, we identified two novel, clustered somatic missense mutations (Y472H and L481F) in RASA1 (RAS p21 protein activator 1, also called p120RasGAP). We have shown that wild type RASA1, but not identified mutants, suppresses soft agar colony formation and tumor growth of BRAF mutated melanoma cell lines via its RasGAP activity toward R-Ras (related RAS viral (r-ras) oncogene homolog) isoform. Moreover, R-Ras increased and RASA1 suppressed Ral-A activation among Ras downstream effectors. In addition to mutations, loss of RASA1 expression was frequently observed in metastatic melanoma samples on melanoma tissue microarray (TMA) and a low level of RASA1 mRNA expression was associated with decreased overall survival in melanoma patients with BRAF mutations. Thus, these data support that RASA1 is inactivated by mutation or by suppressed expression in melanoma and that RASA1 plays a tumor suppressive role by inhibiting R-Ras, a previously less appreciated member of the Ras small GTPases.
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15
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Yan C, Theodorescu D. RAL GTPases: Biology and Potential as Therapeutic Targets in Cancer. Pharmacol Rev 2017; 70:1-11. [PMID: 29196555 DOI: 10.1124/pr.117.014415] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
More than a hundred proteins comprise the RAS superfamily of small GTPases. This family can be divided into RAS, RHO, RAB, RAN, ARF, and RAD subfamilies, with each shown to play distinct roles in human cells in both health and disease. The RAS subfamily has a well-established role in human cancer with the three genes, HRAS, KRAS, and NRAS being the commonly mutated in tumors. These RAS mutations, most often functionally activating, are especially common in pancreatic, lung, and colorectal cancers. Efforts to inhibit RAS and related GTPases have produced inhibitors targeting the downstream effectors of RAS signaling, including inhibitors of the RAF-mitogen-activated protein kinase/extracellular signal-related kinase (ERK)-ERK kinase pathway and the phosphoinositide-3-kinase-AKT-mTOR kinase pathway. A third effector arm of RAS signaling, mediated by RAL (RAS like) has emerged in recent years as a critical driver of RAS oncogenic signaling and has not been targeted until recently. RAL belongs to the RAS branch of the RAS superfamily and shares a high structural similarity with RAS. In human cells, there are two genes, RALA and RALB, both of which have been shown to play roles in the proliferation, survival, and metastasis of a variety of human cancers, including lung, colon, pancreatic, prostate, skin, and bladder cancers. In this review, we summarize the latest knowledge of RAL in the context of human cancer and the recent advancements in the development of cancer therapeutics targeting RAL small GTPases.
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Affiliation(s)
- Chao Yan
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China (C.Y.); Departments of Surgery (Urology) and Pharmacology, University of Colorado, Aurora, Colorado (D.T.); and University of Colorado Comprehensive Cancer Center, Aurora, Colorado (D.T.)
| | - Dan Theodorescu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China (C.Y.); Departments of Surgery (Urology) and Pharmacology, University of Colorado, Aurora, Colorado (D.T.); and University of Colorado Comprehensive Cancer Center, Aurora, Colorado (D.T.)
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16
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Moghadam AR, Patrad E, Tafsiri E, Peng W, Fangman B, Pluard TJ, Accurso A, Salacz M, Shah K, Ricke B, Bi D, Kimura K, Graves L, Najad MK, Dolatkhah R, Sanaat Z, Yazdi M, Tavakolinia N, Mazani M, Amani M, Ghavami S, Gartell R, Reilly C, Naima Z, Esfandyari T, Farassati F. Ral signaling pathway in health and cancer. Cancer Med 2017; 6:2998-3013. [PMID: 29047224 PMCID: PMC5727330 DOI: 10.1002/cam4.1105] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 04/10/2017] [Accepted: 04/14/2017] [Indexed: 12/12/2022] Open
Abstract
The Ral (Ras-Like) signaling pathway plays an important role in the biology of cells. A plethora of effects is regulated by this signaling pathway and its prooncogenic effectors. Our team has demonstrated the overactivation of the RalA signaling pathway in a number of human malignancies including cancers of the liver, ovary, lung, brain, and malignant peripheral nerve sheath tumors. Additionally, we have shown that the activation of RalA in cancer stem cells is higher in comparison with differentiated cancer cells. In this article, we review the role of Ral signaling in health and disease with a focus on the role of this multifunctional protein in the generation of therapies for cancer. An improved understanding of this pathway can lead to development of a novel class of anticancer therapies that functions on the basis of intervention with RalA or its downstream effectors.
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Affiliation(s)
- Adel Rezaei Moghadam
- Department of Human Anatomy and Cell ScienceUniversity of ManitobaWinnipegCanada
| | - Elham Patrad
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Elham Tafsiri
- Department of Pediatrics, Columbia Presbyterian Medical CenterNew YorkNew York
| | - Warner Peng
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Benjamin Fangman
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Timothy J Pluard
- Saint Luke's HospitalUniversity of Missouri at Kansas CityKansas CityMissouri
| | - Anthony Accurso
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Michael Salacz
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Kushal Shah
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Brandon Ricke
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Danse Bi
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Kyle Kimura
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Leland Graves
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Marzieh Khajoie Najad
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Roya Dolatkhah
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Zohreh Sanaat
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Mina Yazdi
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Naeimeh Tavakolinia
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Mohammad Mazani
- Pasteur Institute of IranTehranIran
- Ardabil University of Medical Sciences, BiochemistryArdabilIran
| | - Mojtaba Amani
- Pasteur Institute of IranTehranIran
- Ardabil University of Medical Sciences, BiochemistryArdabilIran
| | - Saeid Ghavami
- Department of Human Anatomy and Cell ScienceUniversity of ManitobaWinnipegCanada
| | - Robyn Gartell
- Department of Pediatrics, Columbia Presbyterian Medical CenterNew YorkNew York
| | - Colleen Reilly
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Zaid Naima
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Tuba Esfandyari
- Department of Medicine, Molecular Medicine LaboratoryThe University of Kansas Medical SchoolKansas CityKansas
| | - Faris Farassati
- Research Service (151)Kansas City Veteran Affairs Medical Center & Midwest Biomedical Research Foundation4801 E Linwood BlvdKansas CityMissouri64128‐2226
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17
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Synthesis of novel Ral inhibitors: An in vitro and in vivo study. Bioorg Med Chem Lett 2016; 26:5815-5818. [PMID: 27825764 DOI: 10.1016/j.bmcl.2016.10.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 10/08/2016] [Indexed: 11/22/2022]
Abstract
Chemical synthesis was performed to produce a series of 6-amino-1,3-disubstituted-4-phenyl-1,4-dihydro pyrano[2,3-c]pyrazole-5-carbonitrile compounds (14-57) which were characterized by 1H NMR, 13C NMR and LC/MS-MS. These compounds were assessed for their effect on the in vitro anchorage independent growth of human lung cancer cell line H2122 and IC50 values calculated. Two of the more potent compounds, BQU057 40 and BQU082 57 also displayed a dose dependent effect on RalA and RalB activity in H2122 spheroids using the common RalBP1 pull-down assay. Mouse PK and tissue distribution studies on 40 and 57 were performed and demonstrated that parent drug was present in tumor 3.0h post ip (50mg/Kg) dose.
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18
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Kobayashi T. Understanding the biology of urothelial cancer metastasis. Asian J Urol 2016; 3:211-222. [PMID: 29264189 PMCID: PMC5730871 DOI: 10.1016/j.ajur.2016.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 09/02/2016] [Accepted: 09/08/2016] [Indexed: 12/29/2022] Open
Abstract
Management of unresectable urothelial cancer (UC) has been a clinical challenge for decades. While drug resistance is a key issue, precise understanding of biology of UC metastasis is another challenge for the improvement of treatment outcome of UC patients. Introduction of the cell biology concepts including epithelial-mesenchymal transition (EMT) and cancer stemness seems to explain UC metastasis. Molecular genetics based on gene expression profiling, next generation sequencing, and explosion of non-coding RNA world has opened the door to intrinsic molecular subtyping of UC. Next steps include, based on the recently accumulated understanding, the establishment of novel disease models representing UC metastasis in various experimental platforms, particularly in vivo animal systems. Indeed, novel knowledge molecular genetics has not been fully linked to the modeling of UC metastasis. Further understanding of bladder carcinogenesis is needed particularly with regard to cell of origin related to tumor characteristics including driver gene alterations, pathological differentiations, and metastatic ability. Then we will be able to establish better disease models, which will consequently lead us to further understanding of biology and eventually the development of novel therapeutic strategies for UC metastasis.
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19
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Posch C, Vujic I, Monshi B, Sanlorenzo M, Weihsengruber F, Rappersberger K, Ortiz-Urda S. Searching for the Chokehold of NRAS Mutant Melanoma. J Invest Dermatol 2016; 136:1330-1336. [PMID: 27160069 DOI: 10.1016/j.jid.2016.03.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 03/01/2016] [Accepted: 03/08/2016] [Indexed: 12/19/2022]
Abstract
Up to 18% of melanomas harbor mutations in the neuroblastoma rat-sarcoma homolog (NRAS). Yet, decades of research aimed to interfere with oncogenic RAS signaling have been largely disappointing and have not resulted in meaningful clinical outputs. Recent advances in disease modeling, structural biology, and an improved understanding of RAS cycling as well as RAS signaling networks have renewed hope for developing strategies to selectively block hyperactive RAS function. This review discusses direct and indirect blocking of activated RAS with a focus on current and potential future therapeutic approaches for NRAS mutant melanoma.
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Affiliation(s)
- Christian Posch
- Department of Dermatology, Mt. Zion Cancer Research Center, University of California San Francisco, San Francisco, California, USA; Department of Dermatology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Dermatology, The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Vienna, Austria.
| | - Igor Vujic
- Department of Dermatology, Mt. Zion Cancer Research Center, University of California San Francisco, San Francisco, California, USA; Department of Dermatology, The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Vienna, Austria
| | - Babak Monshi
- Department of Dermatology, The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Vienna, Austria
| | - Martina Sanlorenzo
- Department of Dermatology, Mt. Zion Cancer Research Center, University of California San Francisco, San Francisco, California, USA; Department of Medical Sciences, Section of Dermatology, University of Turin, Turin, Italy
| | - Felix Weihsengruber
- Department of Dermatology, The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Vienna, Austria
| | - Klemens Rappersberger
- Department of Dermatology, The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Vienna, Austria
| | - Susana Ortiz-Urda
- Department of Dermatology, Mt. Zion Cancer Research Center, University of California San Francisco, San Francisco, California, USA
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20
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Vu HL, Aplin AE. Targeting mutant NRAS signaling pathways in melanoma. Pharmacol Res 2016; 107:111-116. [PMID: 26987942 DOI: 10.1016/j.phrs.2016.03.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 03/10/2016] [Accepted: 03/10/2016] [Indexed: 12/19/2022]
Abstract
Cutaneous melanoma is a devastating form of skin cancer and its incidence is increasing faster than any other preventable cancer in the United States. The mutant NRAS subset of melanoma is more aggressive and associated with poorer outcomes compared to non-NRAS mutant melanoma. The aggressive nature and complex molecular signaling conferred by this transformation has evaded clinically effective treatment options. This review examines the major downstream effectors of NRAS relevant in melanoma and the associated advances made in targeted therapies that focus on these effector pathways. We outline the history of MEK inhibition in mutant NRAS melanoma and recent advances with newer MEK inhibitors. Since MEK inhibitors will likely be optimized when combined with other targeted therapies, we focus on recently identified targets that can be used in combination with MEK inhibitors.
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Affiliation(s)
- Ha Linh Vu
- Department of Cancer Biology and Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States.
| | - Andrew E Aplin
- Department of Cancer Biology and Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States; Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA, United States
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21
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Jenkins RW, Sullivan RJ. NRAS mutant melanoma: an overview for the clinician for melanoma management. Melanoma Manag 2016; 3:47-59. [PMID: 30190872 PMCID: PMC6097550 DOI: 10.2217/mmt.15.40] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/06/2015] [Indexed: 12/19/2022] Open
Abstract
Melanoma is the deadliest form of skin cancer and the incidence continues to rise in the United States and worldwide. Activating mutations in RAS oncogenes are found in roughly a third of all human cancers. Mutations in NRAS occur in approximately a fifth of cutaneous melanomas and are associated with aggressive clinical behavior. Cells harboring oncogenic NRAS mutations exhibit activation of multiple signaling cascades, including PI3K/Akt, MEK-ERK and RAL, which collectively stimulate cancer growth. While strategies to target N-Ras itself have proven ineffective, targeting one or more N-Ras effector pathways has shown promise in preclinical models. Despite promising preclinical data, current therapies for NRAS mutant melanoma remain limited. Immune checkpoint inhibitors and targeted therapies for BRAF mutant melanoma are transforming the treatment of metastatic melanoma, but the ideal treatment for NRAS mutant melanoma remains unknown. Improved understanding of NRAS mutant melanoma and relevant N-Ras effector signaling modules will be essential to develop new treatment strategies.
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Affiliation(s)
| | - Ryan J Sullivan
- Massachusetts General Hospital Cancer Center, Boston, MA, USA
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22
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Shirakawa R, Horiuchi H. Ral GTPases: crucial mediators of exocytosis and tumourigenesis. J Biochem 2015; 157:285-99. [DOI: 10.1093/jb/mvv029] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/07/2015] [Indexed: 11/12/2022] Open
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23
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The RAS-RAL axis in cancer: evidence for mutation-specific selectivity in non-small cell lung cancer. Acta Pharmacol Sin 2015; 36:291-7. [PMID: 25557115 DOI: 10.1038/aps.2014.129] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/30/2014] [Indexed: 12/21/2022] Open
Abstract
Activating RAS mutations are common in human tumors. These mutations are often markers for resistance to therapy and subsequent poor prognosis. So far, targeting the RAF-MEK-ERK and PI3K-AKT signaling pathways downstream of RAS is the only promising approach in the treatment of cancer patients harboring RAS mutations. RAL GTPase, another downstream effector of RAS, is also considered as a therapeutic option for the treatment of RAS-mutant cancers. The RAL GTPase family comprises RALA and RALB, which can have either divergent or similar functions in different tumor models. Recent studies on non-small cell lung cancer (NSCLC) have showed that different RAS mutations selectively activate specific effector pathways. This observation requires broader validation in other tumor tissue types, but if true, will provide a new approach to the treatment of RAS-mutant cancer patients by targeting specific downstream RAS effectors according to the type of RAS mutation. It also suggests that RAL GTPase inhibition will be an important treatment strategy for tumors harboring RAS glycine to cysteine (G12C) or glycien to valine (G12V) mutations, which are commonly found in NSCLC and pancreatic cancer.
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24
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Kashatus DF, Counter CM. Breaking up is hard to do: RalA, mitochondrial fission and cancer. Small GTPases 2014; 2:329-333. [PMID: 22545232 PMCID: PMC3337163 DOI: 10.4161/sgtp.18284] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The small GTPases RalA and RalB are activated downstream of oncogenic Ras. While activation of RalA is critically important for tumor initiation and growth of Ras-driven cancers, the highly similar small GTPase RalB is implicated in cell survival and metastasis. This difference in function between these two related proteins maps to the C-terminus, a 30 amino acid region that regulates subcellular localization and contains several potential phosphorylation sites. Here we discuss our recent evidence that phosphorylation by the mitotic kinase Aurora A promotes RalA relocalization to mitochondrial membranes, where it recruits the effector RalBP1 and the large dynamin-related GTPase Drp1 to promote mitochondrial fission. As upregulation of both RalA and Aurora A have been observed in human tumors, and phosphorylation of RalA at the site targeted by Aurora A promotes tumorigenesis, it is possible that regulation of mitochondrial fission is one mechanism by which RalA promotes cancer.
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Affiliation(s)
- David F Kashatus
- Department of Pharmacology and Cancer Biology; Department of Radiation Oncology; Duke University Medical Center; Durham, NC USA
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25
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Gentry LR, Martin TD, Reiner DJ, Der CJ. Ral small GTPase signaling and oncogenesis: More than just 15minutes of fame. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2976-2988. [PMID: 25219551 DOI: 10.1016/j.bbamcr.2014.09.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/03/2014] [Accepted: 09/04/2014] [Indexed: 01/26/2023]
Abstract
Since their discovery in 1986, Ral (Ras-like) GTPases have emerged as critical regulators of diverse cellular functions. Ral-selective guanine nucleotide exchange factors (RalGEFs) function as downstream effectors of the Ras oncoprotein, and the RalGEF-Ral signaling network comprises the third best characterized effector of Ras-dependent human oncogenesis. Because of this, Ral GTPases as well as their effectors are being explored as possible therapeutic targets in the treatment of RAS mutant cancer. The two Ral isoforms, RalA and RalB, interact with a variety of downstream effectors and have been found to play key and distinct roles in both normal and neoplastic cell physiology including regulation of vesicular trafficking, migration and invasion, tumor formation, metastasis, and gene expression. In this review we provide an overview of Ral biochemistry and biology, and we highlight recent discoveries.
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Affiliation(s)
- Leanna R Gentry
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA
| | | | - David J Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, USA
| | - Channing J Der
- University of North Carolina at Chapel Hill, Department of Pharmacology, Chapel Hill, NC, USA; University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA.
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26
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Yan C, Liu D, Li L, Wempe MF, Guin S, Khanna M, Meier J, Hoffman B, Owens C, Wysoczynski CL, Nitz MD, Knabe WE, Ahmed M, Brautigan DL, Paschal BM, Schwartz MA, Jones DNM, Ross D, Meroueh SO, Theodorescu D. Discovery and characterization of small molecules that target the GTPase Ral. Nature 2014; 515:443-7. [PMID: 25219851 DOI: 10.1038/nature13713] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 07/24/2014] [Indexed: 12/22/2022]
Abstract
The Ras-like GTPases RalA and RalB are important drivers of tumour growth and metastasis. Chemicals that block Ral function would be valuable as research tools and for cancer therapeutics. Here we used protein structure analysis and virtual screening to identify drug-like molecules that bind to a site on the GDP-bound form of Ral. The compounds RBC6, RBC8 and RBC10 inhibited the binding of Ral to its effector RALBP1, as well as inhibiting Ral-mediated cell spreading of murine embryonic fibroblasts and anchorage-independent growth of human cancer cell lines. The binding of the RBC8 derivative BQU57 to RalB was confirmed by isothermal titration calorimetry, surface plasmon resonance and (1)H-(15)N transverse relaxation-optimized spectroscopy (TROSY) NMR spectroscopy. RBC8 and BQU57 show selectivity for Ral relative to the GTPases Ras and RhoA and inhibit tumour xenograft growth to a similar extent to the depletion of Ral using RNA interference. Our results show the utility of structure-based discovery for the development of therapeutics for Ral-dependent cancers.
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Affiliation(s)
- Chao Yan
- Department of Surgery, University of Colorado, Aurora, Colorado 80045, USA
| | - Degang Liu
- Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Liwei Li
- Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Michael F Wempe
- Department of Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045, USA
| | - Sunny Guin
- Department of Surgery, University of Colorado, Aurora, Colorado 80045, USA
| | - May Khanna
- Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Jeremy Meier
- Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Brenton Hoffman
- Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Charles Owens
- Department of Surgery, University of Colorado, Aurora, Colorado 80045, USA
| | | | - Matthew D Nitz
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - William E Knabe
- Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Mansoor Ahmed
- 1] Department of Cardiology, Yale University, New Haven, Connecticut 06511, USA [2] Department of Cell Biology, Yale University, New Haven, Connecticut 06511, USA
| | - David L Brautigan
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Bryce M Paschal
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Martin A Schwartz
- 1] Department of Cardiology, Yale University, New Haven, Connecticut 06511, USA [2] Department of Cell Biology, Yale University, New Haven, Connecticut 06511, USA
| | - David N M Jones
- Department of Pharmacology, University of Colorado, Aurora, Colorado 80045, USA
| | - David Ross
- Department of Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045, USA
| | - Samy O Meroueh
- 1] Department of Biochemistry, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA [2] Department of Chemistry and Chemical Biology, Indiana University - Purdue University, Indianapolis, Indiana 46202, USA
| | - Dan Theodorescu
- 1] Department of Surgery, University of Colorado, Aurora, Colorado 80045, USA [2] Department of Pharmacology, University of Colorado, Aurora, Colorado 80045, USA [3] University of Colorado Comprehensive Cancer Center, Aurora, Colorado 80045, USA
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27
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Vu HL, Aplin AE. Targeting TBK1 inhibits migration and resistance to MEK inhibitors in mutant NRAS melanoma. Mol Cancer Res 2014; 12:1509-19. [PMID: 24962318 DOI: 10.1158/1541-7786.mcr-14-0204] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
UNLABELLED Melanoma is a devastating form of skin cancer with limited therapeutic options. Fifteen to 20% of patients with melanoma have an activating mutation in the GTPase, NRAS. The major downstream effectors of RAS are RAFs (ARAF, BRAF, and CRAF), phosphoinositide 3-kinase (PI3K), and the Ral guanine exchange factors (RalGEF). TANK-binding kinase 1 (TBK1) is an atypical IκB kinase family member that acts downstream of RalGEFs. Whereas many studies have analyzed RAF and PI3K signaling in mutant NRAS melanoma, the role of RalGEF/Ral is understudied and TBK1 has not been examined. To address this, TBK1 was modulated with knockdown approaches and targeted therapies to determine the role of TBK1 in motility, apoptosis, and signaling. In melanoma, NRAS overexpression increased TBK1 phosphorylation. TBK1 depletion inhibited migration and invasion, whereas its constitutive overexpression led to an increase in invasion. In three-dimensional systems that mimic the dermal microenvironment, TBK1 depletion or inhibition cooperated with MEK inhibitors to promote apoptosis, particularly in the context of MEK-insensitive mutant NRAS. This effect was absent in melanoma cells that are wild-type for NRAS. These results suggest the utility of TBK1 inhibitors as part of a treatment regimen for patients with mutant NRAS melanoma, for whom there are no current effective therapies. IMPLICATIONS TBK1 promotes the malignant properties of NRAS-mutant melanoma and its targeting, in combination with MEK, promotes apoptosis, thus providing a potential novel targeted therapeutic option.
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Affiliation(s)
- Ha Linh Vu
- Department of Cancer Biology and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Andrew E Aplin
- Department of Cancer Biology and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania. Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, Pennsylvania.
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Brady DC, Crowe MS, Turski ML, Hobbs GA, Yao X, Chaikuad A, Knapp S, Xiao K, Campbell SL, Thiele DJ, Counter CM. Copper is required for oncogenic BRAF signalling and tumorigenesis. Nature 2014; 509:492-6. [PMID: 24717435 PMCID: PMC4138975 DOI: 10.1038/nature13180] [Citation(s) in RCA: 388] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 02/24/2014] [Indexed: 01/04/2023]
Abstract
The BRAF kinase is mutated, typically Val 600→Glu (V600E), to induce an active oncogenic state in a large fraction of melanomas, thyroid cancers, hairy cell leukaemias and, to a smaller extent, a wide spectrum of other cancers. BRAF(V600E) phosphorylates and activates the MEK1 and MEK2 kinases, which in turn phosphorylate and activate the ERK1 and ERK2 kinases, stimulating the mitogen-activated protein kinase (MAPK) pathway to promote cancer. Targeting MEK1/2 is proving to be an important therapeutic strategy, given that a MEK1/2 inhibitor provides a survival advantage in metastatic melanoma, an effect that is increased when administered together with a BRAF(V600E) inhibitor. We previously found that copper (Cu) influx enhances MEK1 phosphorylation of ERK1/2 through a Cu-MEK1 interaction. Here we show decreasing the levels of CTR1 (Cu transporter 1), or mutations in MEK1 that disrupt Cu binding, decreased BRAF(V600E)-driven signalling and tumorigenesis in mice and human cell settings. Conversely, a MEK1-MEK5 chimaera that phosphorylated ERK1/2 independently of Cu or an active ERK2 restored the tumour growth of murine cells lacking Ctr1. Cu chelators used in the treatment of Wilson disease decreased tumour growth of human or murine cells transformed by BRAF(V600E) or engineered to be resistant to BRAF inhibition. Taken together, these results suggest that Cu-chelation therapy could be repurposed to treat cancers containing the BRAF(V600E) mutation.
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Affiliation(s)
- Donita C Brady
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Matthew S Crowe
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Michelle L Turski
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - G Aaron Hobbs
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Xiaojie Yao
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Apirat Chaikuad
- Nuffield Department of Clinical Medicine, Target Discovery Institute and Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Stefan Knapp
- Nuffield Department of Clinical Medicine, Target Discovery Institute and Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Kunhong Xiao
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Dennis J Thiele
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Christopher M Counter
- 1] Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA [2] Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Abstract
Recognition that Ral guanine nucleotide exchange factors (RalGEFs) are direct Ras effectors and that Ral G-protein activation is a direct consequence of Ras activation has spurred focused efforts to establish the contribution of RalGEF/Ral signaling to oncogenic transformation. Here, we provide a broad-strokes overview of the mechanistic organization of the RalGEF/Ral signaling network, evaluate the evidence for participation of this network in tumorigenic regulatory milieus, consider targeting strategies, and discuss the challenges to and opportunities for clinical development of these targeting strategies.
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Affiliation(s)
- Jonathan M Cooper
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Brian O Bodemann
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Michael A White
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas, USA.
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30
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Ral GTPases in tumorigenesis: emerging from the shadows. Exp Cell Res 2013; 319:2337-42. [PMID: 23830877 DOI: 10.1016/j.yexcr.2013.06.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 06/18/2013] [Accepted: 06/26/2013] [Indexed: 01/03/2023]
Abstract
Oncogenic Ras proteins rely on a series of key effector pathways to drive the physiological changes that lead to tumorigenic growth. Of these effector pathways, the RalGEF pathway, which activates the two Ras-related GTPases RalA and RalB, remains the most poorly understood. This review will focus on key developments in our understanding of Ral biology, and will speculate on how aberrant activation of the multiple diverse Ral effector proteins might collectively contribute to oncogenic transformation and other aspects of tumor progression.
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Martin TD, Der CJ. Differential involvement of RalA and RalB in colorectal cancer. Small GTPases 2013; 3:126-30. [PMID: 22790202 PMCID: PMC3408977 DOI: 10.4161/sgtp.19571] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mutationally activated K-Ras can utilize a multitude of downstream effector proteins to promote oncogenesis. While the Raf and phosphoinositol 3-kinase effector pathways are the best-studied and validated, recent studies have established the critical importance of Ral guanine nucleotide exchange factor (RalGEF) activation of the RalA and RalB small GTPases in cancer biology. Due to recent evidence that the RalGEF-Ral pathway is necessary for the tumorigenic and metastatic potential of KRAS mutant pancreatic ductal adenocarcinoma (PDAC) tumor cells, we investigated whether or not Ral signaling was necessary for KRAS mutant colorectal cancer (CRC) tumor cell growth. As in PDAC, we found upregulated RalA and RalB activation in CRC tumor cell lines and tumors. Surprisingly we found antagonistic roles for RalA and RalB in the regulation of CRC tumor cell anchorage-independent growth. This observation contrasts with PDAC, where RalA but not RalB is necessary for PDAC tumor cell anchorage-independent growth. Our results emphasize cancer cell type differences in Ral function and hence the need for distinct Ral targeted therapeutic approaches in the treatment of CRC vs. PDAC.
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Affiliation(s)
- Timothy D Martin
- Deparment of Pharmacology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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32
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Targeted therapy for melanoma: rational combinatorial approaches. Oncogene 2013; 33:1-9. [PMID: 23416974 DOI: 10.1038/onc.2013.34] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/19/2012] [Indexed: 12/23/2022]
Abstract
The treatment of melanoma, the most aggressive form of skin cancer, is being revolutionized by the development of personalized targeted therapy approaches. Mutant-selective BRAF inhibitors and MEK inhibitors have demonstrated impressive clinical results in molecularly selected patients. However, emerging understanding of the molecular heterogeneity of this disease and the identification of multiple mechanisms of resistance to targeted therapies strongly support the rationale for combinatorial approaches. In this review, we will discuss the preclinical and clinical studies that are testing leading hypotheses and emerging combinatorial strategies for the future.
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NRAS mutant melanoma: biological behavior and future strategies for therapeutic management. Oncogene 2012; 32:3009-18. [PMID: 23069660 DOI: 10.1038/onc.2012.453] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The recent years have seen a significant shift in the expectations for the therapeutic management of disseminated melanoma. The clinical success of BRAF targeted therapy suggests that long-term disease control may one day be a reality for genetically defined subgroups of melanoma patients. Despite this progress, few advances have been made in developing targeted therapeutic strategies for the 50% of patients whose melanomas are BRAF wild-type. The most well-characterized subgroup of BRAF wild-type tumors is the 15-20% of all melanomas that harbor activating NRAS (Neuroblastoma Rat Sarcoma Virus) mutations. Emerging preclinical and clinical evidence suggests that NRAS mutant melanomas have patterns of signal transduction and biological behavior that is distinct from BRAF mutant melanomas. This overview will discuss the unique clinical and prognostic behavior of NRAS mutant melanoma and will summarize the emerging data on how NRAS-driven signaling networks can be translated into novel therapeutic strategies.
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34
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Abstract
Ras genes are frequently activated in cancer. Attempts to develop drugs that target mutant Ras proteins have, so far, been unsuccessful. Tumors bearing these mutations, therefore, remain among the most difficult to treat. Most efforts to block activated Ras have focused on pathways downstream. Drugs that inhibit Raf kinase have shown clinical benefit in the treatment of malignant melanoma. However, these drugs have failed to show clinical benefit in Ras mutant tumors. It remains unclear to what extent Ras depends on Raf kinase for transforming activity, even though Raf proteins bind directly to Ras and are certainly major effectors of Ras action in normal cells and in development. Furthermore, Raf kinase inhibitors can lead to paradoxical activation of the MAPK pathway. MEK inhibitors block the Ras-MAPK pathway, but often activate the PI3'-kinase, and have shown little clinical benefit as single agents. This activation is mediated by EGF-R and other receptor tyrosine kinases through relief of a negative feedback loop from ERK. Drug combinations that target multiple points within the Ras signaling network are likely to be necessary to achieve substantial clinical benefit. Other effectors may also contribute to Ras signaling and provide a source of targets. In addition, unbiased screens for genes necessary for Ras transformation have revealed new potential targets and have added to our understanding of Ras cancer biology.
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Affiliation(s)
- Stephan Gysin
- UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
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Neel NF, Martin TD, Stratford JK, Zand TP, Reiner DJ, Der CJ. The RalGEF-Ral Effector Signaling Network: The Road Less Traveled for Anti-Ras Drug Discovery. Genes Cancer 2011; 2:275-87. [PMID: 21779498 PMCID: PMC3128631 DOI: 10.1177/1947601911407329] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The high frequency of RAS mutations in human cancers (33%) has stimulated intense interest in the development of anti-Ras inhibitors for cancer therapy. Currently, the major focus of these efforts is centered on inhibitors of components involved in Ras downstream effector signaling. In particular, more than 40 inhibitors of the Raf-MEK-ERK mitogen-activated protein kinase cascade and phosphoinositide 3-kinase-AKT-mTOR effector signaling networks are currently under clinical evaluation. However, these efforts are complicated by the fact that Ras can utilize at least 9 additional functionally distinct effectors, with at least 3 additional effectors with validated roles in Ras-mediated oncogenesis. Of these, the guanine nucleotide exchange factors of the Ras-like (Ral) small GTPases (RalGEFs) have emerged as important effectors of mutant Ras in pancreatic, colon, and other cancers. In this review, we summarize the evidence for the importance of this effector pathway in cancer and discuss possible directions for therapeutic inhibition of aberrant Ral activation and signaling.
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Affiliation(s)
- Nicole F Neel
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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