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Tripathi BK, Anderman MF, Bhargava D, Boccuzzi L, Qian X, Wang D, Durkin ME, Papageorge AG, de Miguel FJ, Politi K, Walters KJ, Doroshow JH, Lowy DR. Inhibition of cytoplasmic EZH2 induces antitumor activity through stabilization of the DLC1 tumor suppressor protein. Nat Commun 2021; 12:6941. [PMID: 34862367 PMCID: PMC8642553 DOI: 10.1038/s41467-021-26993-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 10/25/2021] [Indexed: 12/13/2022] Open
Abstract
mRNA expression of the DLC1 tumor suppressor gene is downregulated in many lung cancers and their derived cell lines, with DLC1 protein levels being low or absent. Although the role of increased EZH2 methyltransferase in cancer is usually attributed to its histone methylation, we unexpectedly observed that post-translational destabilization of DLC1 protein is common and attributable to its methylation by cytoplasmic EZH2, leading to CUL-4A ubiquitin-dependent proteasomal degradation of DLC1. Furthermore, siRNA knockdown of KRAS in several lines increases DLC1 protein, associated with a drastic reduction in cytoplasmic EZH2. Pharmacologic inhibition of EZH2, CUL-4A, or the proteasome can increase the steady-state level of DLC1 protein, whose tumor suppressor activity is further increased by AKT and/or SRC kinase inhibitors, which reverse the direct phosphorylation of DLC1 by these kinases. These rational drug combinations induce potent tumor growth inhibition, with markers of apoptosis and senescence, that is highly dependent on DLC1 protein.
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Affiliation(s)
- Brajendra K Tripathi
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.
| | - Meghan F Anderman
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Disha Bhargava
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Luciarita Boccuzzi
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Dunrui Wang
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Marian E Durkin
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Alex G Papageorge
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | | | - Katerina Politi
- Yale Cancer Center, Yale School of Medicine, New Haven, CT, USA
- Departments of Pathology and Internal Medicine (Section of Medical Oncology), Yale School of Medicine, New Haven, CT, USA
| | - Kylie J Walters
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - James H Doroshow
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Douglas R Lowy
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.
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2
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Al Haddad M, El-Rif R, Hanna S, Jaafar L, Dennaoui R, Abdellatef S, Miskolci V, Cox D, Hodgson L, El-Sibai M. Differential regulation of rho GTPases during lung adenocarcinoma migration and invasion reveals a novel role of the tumor suppressor StarD13 in invadopodia regulation. Cell Commun Signal 2020; 18:144. [PMID: 32900380 PMCID: PMC7487901 DOI: 10.1186/s12964-020-00635-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 08/03/2020] [Indexed: 11/11/2022] Open
Abstract
Background Lung cancer is the second most commonly occurring cancer. The ability to metastasize and spread to distant locations renders the tumor more aggressive. Members of the Rho subfamily of small GTP-binding proteins (GTPases) play a central role in the regulation of the actin cytoskeleton and in cancer cell migration and metastasis. In this study we investigated the role of the RhoA/Cdc42 GAP, StarD13, a previously described tumor suppressor, in malignancy, migration and invasion of the lung cancer cells A549. Methods We knocked down StarD13 expression in A549 lung cancer cells and tested the effect on cell migration and invadopodia formation using time lapse imaging and invasion assays. We also performed rescue experiments to determine the signaling pathways downstream of StarD13 and transfected the cells with FRET biosensors for RhoGTPases to identify the proteins involved in invadopodia formation. Results We observed a decrease in the level of expression of StarD13 in lung tumor tissues compared to normal lung tissues through immunohistochemistry. StarD13 also showed a lower expression in the lung adenocarcinoma cell line A549 compared to normal lung cells, WI38. In addition, the depletion of StarD13 increased cell proliferation and viability in WI38 and A549 cells, suggesting that StarD13 might potentially be a tumor suppressor in lung cancer. The depletion of StarD13, however, inhibited cell motility, conversely demonstrating a positive regulatory role in cell migration. This was potentially due to the constitutive activation of RhoA detected by pull down and FRET assays. Surprisingly, StarD13 suppressed cell invasion by inhibiting Cdc42-mediated invadopodia formation. Indeed, TKS4 staining and invadopodia assay revealed that StarD13 depletion increased Cdc42 activation as well as invadopodia formation and matrix degradation. Normal lung cells depleted of StarD13 also produced invadopodia, otherwise a unique hallmark of invasive cancer cells. Cdc42 knock down mimicked the effects of StarD13, while overexpression of a constitutively active Cdc42 mimicked the effects of its depletion. Finally, immunostaining and FRET analysis revealed the absence of StarD13 in invadopodia as compared to Cdc42, which was activated in invadopodia at the sites of matrix degradation. Conclusion In conclusion, StarD13 plays distinct roles in lung cancer cell migration and invasion through its differential regulation of Rho GTPases. Video abstract.
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Affiliation(s)
- Maria Al Haddad
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box: 13-5053. Chouran, Beirut, 1102 2801, Lebanon
| | - Rayane El-Rif
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box: 13-5053. Chouran, Beirut, 1102 2801, Lebanon
| | - Samer Hanna
- Department of Pediatrics HemeOnc division, Weill Cornell Medicine, Joan & Sanford I. Weill Medical College of Cornell University, New York, USA
| | - Leila Jaafar
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box: 13-5053. Chouran, Beirut, 1102 2801, Lebanon
| | - Rayanne Dennaoui
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box: 13-5053. Chouran, Beirut, 1102 2801, Lebanon
| | - Sandra Abdellatef
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box: 13-5053. Chouran, Beirut, 1102 2801, Lebanon
| | - Veronika Miskolci
- Department of Medical Microbiology and Immunology, University of Wisconsin - Madison, Madison, WI, 53706, USA
| | - Dianne Cox
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, USA.,Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, USA
| | - Louis Hodgson
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, USA.,Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, USA
| | - Mirvat El-Sibai
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box: 13-5053. Chouran, Beirut, 1102 2801, Lebanon.
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3
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Wang D, Qian X, Sanchez-Solana B, Tripathi BK, Durkin ME, Lowy DR. Cancer-Associated Point Mutations in the DLC1 Tumor Suppressor and Other Rho-GAPs Occur Frequently and Are Associated with Decreased Function. Cancer Res 2020; 80:3568-3579. [PMID: 32606003 DOI: 10.1158/0008-5472.can-19-3984] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/25/2020] [Accepted: 06/26/2020] [Indexed: 02/06/2023]
Abstract
In advanced cancer, the RHOA GTPase is often active together with reduced expression of genes encoding Rho-specific GTPase-accelerating proteins (Rho-GAP), which negatively regulate RHOA and related GTPases. Here we used the The Cancer Genome Atlas dataset to examine 12 tumor types (including colon, breast, prostate, pancreas, lung adenocarcinoma, and squamous cell carcinoma) for the frequency of codon mutations of 10 Rho-GAP and experimentally tested biochemical and biological consequences for cancer-associated mutants that arose in the DLC1 tumor suppressor gene. DLC1 was the Rho-GAP gene mutated most frequently, with 5%-8% of tumors in five of the tumor types evaluated having DLC1 missense mutations. Furthermore, 20%-26% of the tumors in four of these five tumor types harbored missense mutations in at least one of the 10 Rho-GAPs. Experimental analysis of the DLC1 mutants indicated 7 of 9 mutants whose lesions were located in the Rho-GAP domain were deficient for Rho-GAP activity and for suppressing cell migration and anchorage-independent growth. Analysis of a DLC1 linker region mutant and a START domain mutant showed each was deficient for suppressing migration and growth in agar, but their Rho-GAP activity was similar to that of wild-type DLC1. Compared with the wild-type, the linker region mutant bound 14-3-3 proteins less efficiently, while the START domain mutant displayed reduced binding to Caveolin-1. Thus, mutation of Rho-GAP genes occurs frequently in some cancer types and the majority of cancer-associated DLC1 mutants evaluated were deficient biologically, with various mechanisms contributing to their reduced activity. SIGNIFICANCE: These findings indicate that point mutation of Rho-GAP genes is unexpectedly frequent in several cancer types, with DLC1 mutants exhibiting reduced function by various mechanisms.
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Affiliation(s)
- Dunrui Wang
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, Maryland
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, Maryland
| | - Beatriz Sanchez-Solana
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, Maryland
| | - Brajendra K Tripathi
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, Maryland
| | - Marian E Durkin
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, Maryland
| | - Douglas R Lowy
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, Maryland.
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p190A inactivating mutations cause aberrant RhoA activation and promote malignant transformation via the Hippo-YAP pathway in endometrial cancer. Signal Transduct Target Ther 2020; 5:81. [PMID: 32457342 PMCID: PMC7250911 DOI: 10.1038/s41392-020-0170-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 03/21/2020] [Accepted: 04/15/2020] [Indexed: 12/02/2022] Open
Abstract
The Rho family of GTPases is strictly regulated by a large family of GTPase-activating proteins (GAPs) that stimulate the relatively weak intrinsic GTP-hydrolyzing activity of Rho GTPases. p190A is a potent and widely expressed GAP that acts on RhoA GTPases. p190A is frequently mutated in endometrial cancer, but the contribution of p190A mutations to endometrial tumorigenesis remains unclear. Here we identified that p190A is an upstream regulator of the Hippo-YAP signaling pathway, which is a critical regulator of cell proliferation, apoptosis, and cell fate. p190A knockout in endometrial cancer cells promoted cell proliferation, migration, and epithelial–mesenchymal transition (EMT), which were partially dependent on YAP activation. Wild-type p190A, but not endometrial cancer-associated mutants, suppressed the nuclear localization, transcriptional activity, and malignant transformation function of YAP. Moreover, the nuclear localization of YAP was enhanced in p190A-mutated endometrial cancer. These findings reveal novel molecular mechanisms underlying Hippo-YAP pathway-driven endometrial tumorigenesis and elucidate the potential for therapy targeting the Hippo-YAP pathway in p190A-mutated endometrial cancer.
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5
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Jaafar L, Chamseddine Z, El-Sibai M. StarD13: a potential star target for tumor therapeutics. Hum Cell 2020; 33:437-443. [PMID: 32274657 DOI: 10.1007/s13577-020-00358-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 04/03/2020] [Indexed: 12/19/2022]
Abstract
StarD13 is a tumor suppressor and a GTPase activating protein (GAP) for Rho GTPases. Thus, StarD13 regulates cell survival pathways and induces apoptosis in a p53-dependent and independent manners. In tumors, StarD13 is either downregulated or completely inhibited, depending on the tumor type. As such, and through the dysregulation of Rho GTPases, this affects adhesion dynamics, actin dynamics, and leads to an increase or a decrease in tumor metastasis depending on the tumor grade and type. Being a key regulatory protein, StarD13 is a potential promising candidate for therapeutic approaches. This paper reviews the key characteristics of this protein and its role in tumor malignancies.
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Affiliation(s)
- Leila Jaafar
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Chouran, P.O. Box 13-5053, 1102 2801, Beirut, Lebanon
| | - Zeinab Chamseddine
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Chouran, P.O. Box 13-5053, 1102 2801, Beirut, Lebanon
| | - Mirvat El-Sibai
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Chouran, P.O. Box 13-5053, 1102 2801, Beirut, Lebanon.
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Tripathi BK, Anderman MF, Qian X, Zhou M, Wang D, Papageorge AG, Lowy DR. SRC and ERK cooperatively phosphorylate DLC1 and attenuate its Rho-GAP and tumor suppressor functions. J Cell Biol 2019; 218:3060-3076. [PMID: 31308216 PMCID: PMC6719442 DOI: 10.1083/jcb.201810098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 03/24/2019] [Accepted: 05/02/2019] [Indexed: 12/12/2022] Open
Abstract
DLC1 controls focal adhesion dynamics and other processes that suppress tumorigenesis; therefore, it is unclear why some cancers maintain high levels of DLC1. Tripathi et al. show that phosphorylation of DLC1 by SRC and ERK mitigates DLC1’s tumor suppressor activities but these can be reactivated by kinase inhibition as a potential cancer treatment. SRC and ERK kinases control many cell biological processes that promote tumorigenesis by altering the activity of oncogenic and tumor suppressor proteins. We identify here a physiological interaction between DLC1, a focal adhesion protein and tumor suppressor, with SRC and ERK. The tumor suppressor function of DLC1 is attenuated by phosphorylation of tyrosines Y451 and Y701 by SRC, which down-regulates DLC1’s tensin-binding and Rho-GAP activities. ERK1/2 phosphorylate DLC1 on serine S129, which increases both the binding of SRC to DLC1 and SRC-dependent phosphorylation of DLC1. SRC inhibitors exhibit potent antitumor activity in a DLC1-positive transgenic cancer model and a DLC1-positive tumor xenograft model, due to reactivation of the tumor suppressor activities of DLC1. Combined treatment of DLC1-positive tumors with SRC plus AKT inhibitors has even greater antitumor activity. Together, these findings indicate cooperation between the SRC, ERK1/2, and AKT kinases to reduce DLC1 Rho-GAP and tumor suppressor activities in cancer cells, which can be reactivated by the kinase inhibitors.
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Affiliation(s)
- Brajendra K Tripathi
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Meghan F Anderman
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Ming Zhou
- Laboratory of Proteomics and Analytical Technologies, Frederick National Laboratory for Cancer Research, Frederick, MD
| | - Dunrui Wang
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Alex G Papageorge
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Douglas R Lowy
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
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Sánchez-Martín D, Otsuka A, Kabashima K, Ha T, Wang D, Qian X, Lowy DR, Tosato G. Effects of DLC1 Deficiency on Endothelial Cell Contact Growth Inhibition and Angiosarcoma Progression. J Natl Cancer Inst 2019; 110:390-399. [PMID: 29202196 DOI: 10.1093/jnci/djx219] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 09/18/2017] [Indexed: 01/04/2023] Open
Abstract
Background Deleted in Liver Cancer 1 (DLC1) is a tumor suppressor gene frequently deleted in cancer. However, DLC1 is not known to be deleted in angiosarcoma, an aggressive malignancy of endothelial cell derivation. Additionally, the physiologic functions of DLC1 protein in endothelial cells are poorly defined. Methods We investigated the effects of shRNA-induced DLC1 depletion in endothelial cells. Cell growth was measured by 3H thymidine incorporation, IncuCyte imaging, and population doublings; cell death by cell cycle analysis; gene expression by Affimetrix arrays and quantitative polymerase chain reaction; NF-κB activity by reporter assays; and protein levels by immunoblotting and immunofluorescence staining. We tested Tanespimycin/17-AAG and Fasudil treatment in groups of nine to 10 mice bearing ISOS-1 angiosarcoma. All statistical tests were two-sided. Results We discovered that DLC1 is a critical regulator of cell contact inhibition of proliferation in endothelial cells, promoting statistically significant (P < .001) cell death when cells are confluent (mean [SD] % viability: control DLC1 = 15.6 [19.3]; shDLC1 = 73.4 [13.1]). This prosurvival phenotype of DLC1-depleted confluent endothelial cells is attributable to a statistically significant and sustained increase of NF-κB activity (day 5, P = .001; day 8, P = .03) associated with increased tumor necrosis factor alpha-induced protein 3 (TNFAIP3/A20) signaling. Consistently, we found that DLC1 is statistically significantly reduced (P < .001 in 5 of 6) and TNFAIP3/A20 is statistically significantly increased (P < .001 in 2 of 3 and P = 0.02 in 1 of 3) in human angiosarcoma compared with normal adjacent endothelium. Treatment with the NF-κB inhibitor Tanespimycin/17-AAG statistically significantly reduced angiosarcoma tumor growth in mice (treatment tumor weight vs control, 0.50 [0.19] g vs 0.91 [0.21] g, P = .001 experiment 1; 0.66 [0.26] g vs 1.10 [0.31] g, P = .01 experiment 2). Conclusions These results identify DLC1 as a previously unrecognized regulator of endothelial cell contact inhibition of proliferation that is depleted in angiosarcoma and support NF-κB targeting for the treatment of angiosarcoma where DLC1 is lost.
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Affiliation(s)
- David Sánchez-Martín
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Atsushi Otsuka
- Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Kenji Kabashima
- Department of Dermatology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Taekyu Ha
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Dunrui Wang
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Douglas R Lowy
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Giovanna Tosato
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
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8
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Yang Z, Chen H, Shu M, Zhang Y, Xue L, Lin Y. DLC2 operates as a tumor suppressor gene in breast cancer via the RhoGTPase pathway. Oncol Lett 2018; 17:2107-2116. [PMID: 30719106 PMCID: PMC6350186 DOI: 10.3892/ol.2018.9874] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 09/21/2018] [Indexed: 12/21/2022] Open
Abstract
Deleted in liver cancer 2 (DLC2) is a tumor suppressor, associated with various types of cancer. The aim of the present study was to analyze the expression of DLC2 in breast cancer, its clinical significance and its effect on breast cancer cell behavior. The expression of DLC2 was evaluated by immunohistochemistry in 131 cases of breast cancer. Associations among DLC2 expression and clinicopathological features were analyzed, and its effects on proliferation, motility, migration and invasion in DLC2-knockdown breast cancer cell lines were observed. The results indicated that DLC2 was expressed in 42.75% of breast cancer cases (56/131) and in 79.39% of adjacent normal tissues (104/131). Lower expression of DLC2 in breast cancer was associated with tumor differentiation (P<0.001), lymph node metastasis (P<0.001) and poor prognosis (P<0.001). The silencing of the DLC2 gene in human breast cancer cell indicated an increased number of cells entering S phase, and increased abilities of clone formation, cell migration and invasion. Downregulated expression of DLC2 was associated with activated Ras homolog family member A and decreased Rac family small GTPase 1, cell division cycle 42 and Rho-associated protein kinase-2 expression levels, indicating that DLC2 may serve a regulatory function in breast cancer cell proliferation and invasion via the RhoGTPase pathway. The results of the present study suggested that DLC2 serves as a suppressor gene in the development of breast cancer and may be a prognostic marker for patients with breast cancer.
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Affiliation(s)
- Zheng Yang
- Department of Pathology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Hanrui Chen
- Department of Oncology, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China
| | - Man Shu
- Department of Pathology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yunjian Zhang
- Department of Thyroid, Breast Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Ling Xue
- Department of Pathology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yuan Lin
- Department of Pathology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510080, P.R. China
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Activated Rho GTPases in Cancer-The Beginning of a New Paradigm. Int J Mol Sci 2018; 19:ijms19123949. [PMID: 30544828 PMCID: PMC6321241 DOI: 10.3390/ijms19123949] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 11/30/2018] [Accepted: 12/05/2018] [Indexed: 12/26/2022] Open
Abstract
Involvement of Rho GTPases in cancer has been a matter of debate since the identification of the first members of this branch of the Ras superfamily of small GTPases. The Rho GTPases were ascribed important roles in the cell, although these were restricted to regulation of cytoskeletal dynamics, cell morphogenesis, and cell locomotion, with initially no clear indications of direct involvement in cancer progression. This paradigm has been challenged by numerous observations that Rho-regulated pathways are often dysregulated in cancers. More recently, identification of point mutants in the Rho GTPases Rac1, RhoA, and Cdc42 in human tumors has finally given rise to a new paradigm, and we can now state with confidence that Rho GTPases serve as oncogenes in several human cancers. This article provides an exposé of current knowledge of the roles of activated Rho GTPases in cancers.
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10
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Gökmen-Polar Y, True JD, Vieth E, Gu Y, Gu X, Qi GD, Mosley AL, Badve SS. Quantitative phosphoproteomic analysis identifies novel functional pathways of tumor suppressor DLC1 in estrogen receptor positive breast cancer. PLoS One 2018; 13:e0204658. [PMID: 30278072 PMCID: PMC6168143 DOI: 10.1371/journal.pone.0204658] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 09/12/2018] [Indexed: 11/19/2022] Open
Abstract
Deleted in Liver Cancer-1 (DLC1), a member of the RhoGAP family of proteins, functions as a tumor suppressor in several cancers including breast cancer. However, its clinical relevance is unclear in breast cancer. In this study, expression of DLC1 was correlated with prognosis using publicly available breast cancer gene expression datasets and quantitative Reverse Transcription PCR in cohorts of Estrogen Receptor-positive (ER+) breast cancer. Low expression of DLC1 correlates with poor prognosis in patients with ER+ breast cancer with further decrease in metastatic lesions. The Cancer Genome Atlas (TCGA) data showed that down regulation of DLC1 is not due to methylation or mutations. To seek further insights in understanding the role of DLC1 in ER+ breast cancer, we stably overexpressed DLC1-full-length (DLC1-FL) in T-47D breast cancer cells; this inhibited cell colony formation significantly in vitro compared to its control counterpart. Label-free global proteomic and TiO2 phosphopeptide enrichment assays (ProteomeXchange identifier PXD008220) showed that 205 and 122 phosphopeptides were unique to DLC1-FL cells and T-47D-control cells, respectively, whereas 6,726 were quantified by phosphoproteomics analysis in both conditions. The top three significant clusters of differentially phosphopeptides identified by DAVID pathway analysis represent cell-cell adhesion, mRNA processing and splicing, and transcription regulation. Phosphoproteomics analysis documented an inverse relation between DLC1 expression and several phosphopeptides including epithelial cell transforming sequence 2 (ECT2). Decreased phosphorylation of ECT2 at the residue T359, critical for its active conformational change, was validated by western blot. In addition, the ECT2 T359-containing phosphopeptide was detected in both basal and luminal patient-derived breast cancers breast cancer phosphoproteomics data on the Clinical Proteomic Tumor Analysis Consortium (CPTAC) Assay portal. Together, for the first time, this implicates ECT2 phosphorylation in breast cancer, which has been proposed as a therapeutic target in lung cancer. In conclusion, this data suggests that low expression of DLC1 is associated with poor prognosis. Targeting ECT2 phosphopeptides could provide a promising mechanism for controlling poor prognosis seen in DLC1low ER+ breast cancer.
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Affiliation(s)
- Yesim Gökmen-Polar
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States of America
- * E-mail:
| | - Jason D. True
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States of America
| | - Edyta Vieth
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States of America
| | - Yuan Gu
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States of America
| | - Xiaoping Gu
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States of America
| | - Guihong D. Qi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States of America
| | - Amber L. Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States of America
| | - Sunil S. Badve
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States of America
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States of America
- Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN, United States of America
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Cheng C, Feng S, Jiao J, Huang W, Huang J, Wang L, Jiang W, Jiang C, Dai M, Li Z, Zhang R, Sun J, Shao J. DLC2 inhibits development of glioma through regulating the expression ratio of TAp73α/TAp73β. Am J Cancer Res 2018; 8:1200-1213. [PMID: 30094094 PMCID: PMC6079157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 05/04/2018] [Indexed: 06/08/2023] Open
Abstract
To date, the anti-tumor mechanism of the deleted in liver cancer 2 (DLC2) in gliomas is still unclear. The study shows that TAp73α expression and TAp73α/TAp73β ratio are frequently high in gliomas and that TAp73α and TAp73β have opposite roles in regulating proliferation and apoptosis of glioma cells. Moreover, DLC2 is low-expressed in gliomas, which negatively correlates with TAp73α expression and TAp73α/TAp73β ratio. More importantly, DLC2 inhibits development of glioma by decreasing expression of TAp73α, which changes the expression ratio of TAp73α/TAp73β in glioma cells. Mechanically, DLC2 interacts directly with TAp73α and induces TAp73α ubiquitination and degradation, which is mediated through SAM domain of DLC2 and TAp73α. In detail, DLC2 with SAM domain deletion fails to interact with TAp73α and induce TAp73α ubiquitination and degradation, and SAM deletion decreased tumorigenesis-inhibition effect of DLC2. In conclusion, DLC2 inhibits glioma development by inducing TAp73α degradation and subsequent change of TAp73α/TAp73β expression ratio.
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Affiliation(s)
- Chao Cheng
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Suyin Feng
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Jiantong Jiao
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Weiyi Huang
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Jin Huang
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Long Wang
- Department of Neurosurgery, Peace Hospital of Changzhi Medical CollegeChangzhi 046000, Shanxi, China
| | - Wei Jiang
- Department of Neurosurgery, Changzhou Wujin People’s Hospital of Jiangsu UniversityChangzhou 213100, Jiangsu, China
| | - Chen Jiang
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Minchao Dai
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Zheng Li
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Rui Zhang
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Jun Sun
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
| | - Junfei Shao
- Department of Neurosurgery, Wuxi People’s Hospital of Nanjing Medical UniversityWuxi 214023, Jiangsu, China
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12
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Zhang S, Chang X, Ma J, Chen J, Zhi Y, Li Z, Dai D. Downregulation of STARD8 in gastric cancer and its involvement in gastric cancer progression. Onco Targets Ther 2018; 11:2955-2961. [PMID: 29849465 PMCID: PMC5967373 DOI: 10.2147/ott.s154524] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Objective Rho-GTPases play a pivotal role in a wide variety of signal transduction pathways and are associated with a great number of human carcinomas. STARD8, which is a Rho-GTPase-activating protein, has been proposed as a tumor suppressor gene, but its role in gastric cancer remains elusive. In this study, we investigate the expression of STARD8 in gastric cancer and its association with gastric cancer progression. Materials and methods One normal gastric mucosa cell line for example GES1 and six human gastric cancer cell lines such as AGS, MGC803, MKN45, SGC7901, HGC27 and BGC823 were utilized to analyze STARD8 mRNA and protein levels by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. A total of 70 paired gastric tissues including corresponding nonmalignant gastric tissues and cancer tissues were utilized to analyze the protein expression of STARD8 using immunohistochemistry, and the correlation between STARD8 level and clinicopathological features was also evaluated. Results STARD8 was found to be downregulated in primary gastric cancer cells and tissues compared with the normal gastric mucosa cell line, GES1, and corresponding nonmalignant gastric tissues, while its decreased expression was significantly associated with TNM stage, lymph node metastasis and differentiation (p<0.05). Conclusion There is significantly decreased expression of STARD8 in gastric cancer cells and tissues, and its expression may contribute to gastric tumorigenesis.
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Affiliation(s)
- Shuanglong Zhang
- Department of Gastrointestinal Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China.,Cancer Center, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China
| | - Xiaojing Chang
- Department of Gastrointestinal Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China.,Cancer Center, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China.,Department of Radiotherapy, The Second Hospital of Hebei Medical University, Shijiazhuang, People's Republic of China
| | - Jinguo Ma
- Cancer Center, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China.,Hulun Buir People's Hospital, Hulun Buir Medical School in Nationalities University of Inner Mongolia, Hulun Buir, People's Republic of China
| | - Jing Chen
- Department of Gastrointestinal Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China
| | - Yu Zhi
- Cancer Center, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China
| | - Zhenhua Li
- Cancer Center, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China
| | - Dongqiu Dai
- Department of Gastrointestinal Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China.,Cancer Center, The Fourth Affiliated Hospital, China Medical University, Shenyang, People's Republic of China
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13
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Wang D, Qian X, Rajaram M, Durkin ME, Lowy DR. DLC1 is the principal biologically-relevant down-regulated DLC family member in several cancers. Oncotarget 2018; 7:45144-45157. [PMID: 27174913 PMCID: PMC5216712 DOI: 10.18632/oncotarget.9266] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 04/10/2016] [Indexed: 01/12/2023] Open
Abstract
The RHO family of RAS-related GTPases in tumors may be activated by reduced levels of RHO GTPase accelerating proteins (GAPs). One common mechanism is decreased expression of one or more members of the Deleted in Liver Cancer (DLC) family of Rho-GAPs, which comprises three closely related genes (DLC1, DLC2, and DLC3) that are down-regulated in a wide range of malignancies. Here we have studied their comparative biological activity in cultured cells and used publicly available datasets to examine their mRNA expression patterns in normal and cancer tissues, and to explore their relationship to cancer phenotypes and survival outcomes. In The Cancer Genome Atlas (TCGA) database, DLC1 expression predominated in normal lung, breast, and liver, but not in colorectum. Conversely, reduced DLC1 expression predominated in lung squamous cell carcinoma (LSC), lung adenocarcinoma (LAD), breast cancer, and hepatocellular carcinoma (HCC), but not in colorectal cancer. Reduced DLC1 expression was frequently associated with promoter methylation in LSC and LAD, while DLC1 copy number loss was frequent in HCC. DLC1 expression was higher in TCGA LAD patients who remained cancer-free, while low DLC1 had a poorer prognosis than low DLC2 or low DLC3 in a more completely annotated database. The poorest prognosis was associated with low expression of both DLC1 and DLC2 (P < 0.0001). In cultured cells, the three genes induced a similar reduction of Rho-GTP and cell migration. We conclude that DLC1 is the predominant family member expressed in several normal tissues, and its expression is preferentially reduced in common cancers at these sites.
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Affiliation(s)
- Dunrui Wang
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Megha Rajaram
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.,Current address: BioTek Instruments Inc., Winooski, VT 05404, USA
| | - Marian E Durkin
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Douglas R Lowy
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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14
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Tripathi BK, Grant T, Qian X, Zhou M, Mertins P, Wang D, Papageorge AG, Tarasov SG, Hunter KW, Carr SA, Lowy DR. Receptor tyrosine kinase activation of RhoA is mediated by AKT phosphorylation of DLC1. J Cell Biol 2017; 216:4255-4270. [PMID: 29114068 PMCID: PMC5716279 DOI: 10.1083/jcb.201703105] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 07/26/2017] [Accepted: 09/01/2017] [Indexed: 01/04/2023] Open
Abstract
A new common mechanism for increasing RhoA-GTP is identified in Tripathi et al. The increased RhoA-GTP results from signaling mechanisms that phosphorylate and attenuate the DLC1 tumor suppressor, which encodes RhoGAP. The potentially reversible nature of this attenuation may have therapeutic relevance in cancer. We report several receptor tyrosine kinase (RTK) ligands increase RhoA–guanosine triphosphate (GTP) in untransformed and transformed cell lines and determine this phenomenon depends on the RTKs activating the AKT serine/threonine kinase. The increased RhoA-GTP results from AKT phosphorylating three serines (S298, S329, and S567) in the DLC1 tumor suppressor, a Rho GTPase-activating protein (RhoGAP) associated with focal adhesions. Phosphorylation of the serines, located N-terminal to the DLC1 RhoGAP domain, induces strong binding of that N-terminal region to the RhoGAP domain, converting DLC1 from an open, active dimer to a closed, inactive monomer. That binding, which interferes with the interaction of RhoA-GTP with the RhoGAP domain, reduces the hydrolysis of RhoA-GTP, the binding of other DLC1 ligands, and the colocalization of DLC1 with focal adhesions and attenuates tumor suppressor activity. DLC1 is a critical AKT target in DLC1-positive cancer because AKT inhibition has potent antitumor activity in the DLC1-positive transgenic cancer model and in a DLC1-positive cancer cell line but not in an isogenic DLC1-negative cell line.
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Affiliation(s)
- Brajendra K Tripathi
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Tiera Grant
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Ming Zhou
- Laboratory of Proteomics and Analytical Technologies, Frederick National Laboratory for Cancer Research, Frederick, MD
| | | | - Dunrui Wang
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Alex G Papageorge
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Sergey G Tarasov
- Structural Biophysics Laboratory, National Cancer Institute, Frederick, MD
| | - Kent W Hunter
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | | | - Douglas R Lowy
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD
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15
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Takaoka M, Ito S, Miki Y, Nakanishi A. FKBP51 regulates cell motility and invasion via RhoA signaling. Cancer Sci 2017; 108:380-389. [PMID: 28032931 PMCID: PMC5378274 DOI: 10.1111/cas.13153] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 12/13/2016] [Accepted: 12/25/2016] [Indexed: 12/12/2022] Open
Abstract
FK506 binding protein 51 (FKBP51), a member of the immunophilin family, is involved in multiple signaling pathways, tumorigenesis, and chemoresistance. FKBP51 expression correlates with metastatic potential in melanoma and prostate cancer. However, the functions of FKBP51, particularly involving the regulation of cell motility and invasion, are not fully understood. We discovered two novel interacting partner proteins of FKBP51, i.e., deleted in liver cancer 1 (DLC1) and deleted in liver cancer 2 (DLC2), using immunoprecipitation and mass spectrometry. DLC1 and DLC2 are Rho GTPase‐activating proteins that are frequently downregulated in various cancers. Next, we demonstrated that overexpression of FKBP51 enhances cell motility and invasion of U2OS cells via upregulation of RhoA activity and enhanced Rho‐ROCK signaling. Moreover, FKBP51‐depleted cells displayed a cortical distribution of actin filaments and decreased cell motility and invasion. Consistent with this phenotype, FKBP51 depletion caused a downregulation of RhoA activity. Considered together, our results demonstrate that FKBP51 positively controls cell motility by promoting RhoA and ROCK activation; thus, we have revealed a novel role for FKBP51 in cytoskeletal rearrangement and cell migration and invasion.
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Affiliation(s)
- Miho Takaoka
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Japan
| | - Shun Ito
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Japan
| | - Yoshio Miki
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Japan.,Department of Genetic Diagnosis, The Cancer Institute, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Akira Nakanishi
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Japan
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16
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Sim CK, Kim SY, Brunmeir R, Zhang Q, Li H, Dharmasegaran D, Leong C, Lim YY, Han W, Xu F. Regulation of white and brown adipocyte differentiation by RhoGAP DLC1. PLoS One 2017; 12:e0174761. [PMID: 28358928 PMCID: PMC5373604 DOI: 10.1371/journal.pone.0174761] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 03/15/2017] [Indexed: 12/22/2022] Open
Abstract
Adipose tissues constitute an important component of metabolism, the dysfunction of which can cause obesity and type II diabetes. Here we show that differentiation of white and brown adipocytes requires Deleted in Liver Cancer 1 (DLC1), a Rho GTPase Activating Protein (RhoGAP) previously studied for its function in liver cancer. We identified Dlc1 as a super-enhancer associated gene in both white and brown adipocytes through analyzing the genome-wide binding profiles of PPARγ, the master regulator of adipogenesis. We further observed that Dlc1 expression increases during differentiation, and knockdown of Dlc1 by siRNA in white adipocytes reduces the formation of lipid droplets and the expression of fat marker genes. Moreover, knockdown of Dlc1 in brown adipocytes reduces expression of brown fat-specific genes and diminishes mitochondrial respiration. Dlc1-/- knockout mouse embryonic fibroblasts show a complete inability to differentiate into adipocytes, but this phenotype can be rescued by inhibitors of Rho-associated kinase (ROCK) and filamentous actin (F-actin), suggesting the involvement of Rho pathway in DLC1-regulated adipocyte differentiation. Furthermore, PPARγ binds to the promoter of Dlc1 gene to regulate its expression during both white and brown adipocyte differentiation. These results identify DLC1 as an activator of white and brown adipocyte differentiation, and provide a molecular link between PPARγ and Rho pathways.
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Affiliation(s)
- Choon Kiat Sim
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Sun-Yee Kim
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore
| | - Reinhard Brunmeir
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Qiongyi Zhang
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Hongyu Li
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore
| | - Dharmini Dharmasegaran
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Carol Leong
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Ying Yan Lim
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Weiping Han
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Feng Xu
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- * E-mail:
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17
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Lawson CD, Der CJ. Filling GAPs in our knowledge: ARHGAP11A and RACGAP1 act as oncogenes in basal-like breast cancers. Small GTPases 2016; 9:290-296. [PMID: 27657701 DOI: 10.1080/21541248.2016.1220350] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Like RAS proteins, the aberrant function of RHO family small GTPases has been implicated in driving cancer development and growth. However, unlike the RAS family, where gain-of-function missense mutations are found in ∼25% of all human cancers, missense mutations are relatively rare in RHO proteins. Instead, altered RHO activity in cancer more commonly arises through the aberrant functions of RHO GTPase regulators. In many cancer types, altered expression and/or mutation of RHO-selective guanine nucleotide exchange factors (RHOGEFs) or GTPase-activating proteins (RHOGAPs), which activate or inactivate RHO GTPases, respectively, is observed. For example, deletion or loss of expression of the RHOA GAP DLC1 is well-established to drive cancer growth. Recently, we identified high expression of 2 RHOGAPs, ARHGAP11A and RACGAP1, in the basal-like breast cancer subtype. Unexpectedly, both of these RHOA GAPs exhibited properties of oncoproteins rather than tumor suppressors, in contrast to DLC1. In this commentary, we summarize our findings and speculate that different RHOA GAPs can play distinct roles in cancer depending on their spatial regulation and cancer type context. We also evaluate our results in light of recently-described cancer genome sequencing studies that have identified loss-of-function mutations of RHOA in specific cancer types.
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Affiliation(s)
- Campbell D Lawson
- a Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus , London , UK
| | - Channing J Der
- b Department of Pharmacology and Lineberger Comprehensive Cancer Center , University of North Carolina at Chapel Hill , Chapel Hill , NC , USA
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18
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Yang X, Zhou X, Tone P, Durkin ME, Popescu NC. Cooperative antiproliferative effect of coordinated ectopic expression of DLC1 tumor suppressor protein and silencing of MYC oncogene expression in liver cancer cells: Therapeutic implications. Oncol Lett 2016; 12:1591-1596. [PMID: 27446476 DOI: 10.3892/ol.2016.4781] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 06/03/2016] [Indexed: 12/14/2022] Open
Abstract
Human hepatocellular carcinoma (HCC) is one of the most common types of cancer and has a very poor prognosis; thus, the development of effective therapies for the treatment of advanced HCC is of high clinical priority. In the present study, the anti-oncogenic effect of combined knockdown of c-Myc expression and ectopic restoration of deleted in liver cancer 1 (DLC1) expression was investigated in human liver cancer cells. Expression of c-Myc in human HCC cells was knocked down by stable transfection with a Myc-specific short hairpin (sh) RNA vector. DLC1 expression in Huh7 cells was restored by adenovirus transduction, and the effects of DLC1 expression and c-Myc knockdown on Ras homolog gene family, member A (RhoA) levels, cell proliferation, soft agar colony formation and cell invasion were measured. Downregulation of c-Myc or re-expression of DLC1 led to a marked reduction in RhoA levels, which was associated with decreases in cell proliferation, soft agar colony formation and invasiveness; this inhibitory effect was augmented with a combination of DLC1 transduction and c-Myc suppression. To determine whether liver cell-specific delivery of DLC1 was able to enhance the inhibitory effect of c-Myc knockdown on tumor growth in vivo, DLC1 vector DNA complexed with galactosylated polyethylene glycol-linear polyethyleneimine was administered by tail vein injection to mice bearing subcutaneous xenografts of Huh7 cells transfected with shMyc or control shRNA. A cooperative inhibitory effect of DLC1 expression and c-Myc knockdown on the growth of Huh7-derived tumors was observed, suggesting that targeted liver cell delivery of DLC1 and c-Myc shRNA may serve as a possible gene therapy modality for the treatment of human HCC.
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Affiliation(s)
- Xuyu Yang
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089-4262, USA; Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Development, Bethesda, MD 2089-4262, USA
| | - Xiaoling Zhou
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089-4262, USA; Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089-4262, USA
| | - Paul Tone
- Department of Medicine, Richmond University Medical Center, Staten Island, NY 10310, USA
| | - Marian E Durkin
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089-4262, USA; Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4262, USA
| | - Nicholas C Popescu
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089-4262, USA; Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4262, USA
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19
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Lawson CD, Fan C, Mitin N, Baker NM, George SD, Graham DM, Perou CM, Burridge K, Der CJ, Rossman KL. Rho GTPase Transcriptome Analysis Reveals Oncogenic Roles for Rho GTPase-Activating Proteins in Basal-like Breast Cancers. Cancer Res 2016; 76:3826-37. [PMID: 27216196 DOI: 10.1158/0008-5472.can-15-2923] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/18/2016] [Indexed: 02/06/2023]
Abstract
The basal-like breast cancer (BLBC) subtype accounts for a disproportionately high percentage of overall breast cancer mortality. The current therapeutic options for BLBC need improvement; hence, elucidating signaling pathways that drive BLBC growth may identify novel targets for the development of effective therapies. Rho GTPases have previously been implicated in promoting tumor cell proliferation and metastasis. These proteins are inactivated by Rho-selective GTPase-activating proteins (RhoGAP), which have generally been presumed to act as tumor suppressors. Surprisingly, RNA-Seq analysis of the Rho GTPase signaling transcriptome revealed high expression of several RhoGAP genes in BLBC tumors, raising the possibility that these genes may be oncogenic. To evaluate this, we examined the roles of two of these RhoGAPs, ArhGAP11A (also known as MP-GAP) and RacGAP1 (also known as MgcRacGAP), in promoting BLBC. Both proteins were highly expressed in human BLBC cell lines, and knockdown of either gene resulted in significant defects in the proliferation of these cells. Knockdown of ArhGAP11A caused CDKN1B/p27-mediated arrest in the G1 phase of the cell cycle, whereas depletion of RacGAP1 inhibited growth through the combined effects of cytokinesis failure, CDKN1A/p21-mediated RB1 inhibition, and the onset of senescence. Random migration was suppressed or enhanced by the knockdown of ArhGAP11A or RacGAP1, respectively. Cell spreading and levels of GTP-bound RhoA were increased upon depletion of either RhoGAP. We have established that, via the suppression of RhoA, ArhGAP11A and RacGAP1 are both critical drivers of BLBC growth, and propose that RhoGAPs can act as oncogenes in cancer. Cancer Res; 76(13); 3826-37. ©2016 AACR.
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Affiliation(s)
- Campbell D Lawson
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cheng Fan
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Natalia Mitin
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nicole M Baker
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Samuel D George
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - David M Graham
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Charles M Perou
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Keith Burridge
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Channing J Der
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
| | - Kent L Rossman
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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20
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Popescu NC, Goodison S. Deleted in liver cancer-1 (DLC1): an emerging metastasis suppressor gene. Mol Diagn Ther 2015; 18:293-302. [PMID: 24519699 DOI: 10.1007/s40291-014-0086-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
While significant progress continues to be made in the early detection and therapeutic management of primary tumors, the incidence of metastatic disease remains the major cause of mortality. Accordingly, the development of novel effective therapies that can ameliorate dissemination and secondary tumor growth are a clinical priority. The identification of genetic and functional alterations in cancer cells that affect factors implicated in the metastatic process is critical for designing preventive and therapeutic strategies. Evidence implicating the protein deleted in liver cancer-1 (DLC1), a Rho GTPase activator, in metastasis has accumulated to a point where DLC1 may be considered as a metastasis suppressor gene. This review presents evidence supporting an anti-metastatic role for DLC1 in several human cancers and discusses the mechanisms contributing to its inhibitory effects. In addition, promising opportunities for therapeutic interventions based on DLC1 function and downstream pathways involved in the metastatic process are considered.
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Affiliation(s)
- Nicholas C Popescu
- Laboratory of Experimental Carcinogenesis, National Cancer Institute, Building 37, Room 4140, 37 Convent Dr., MSC 4262, Bethesda, MD, 20892-4262, USA,
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21
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The tumour suppressor DLC2 ensures mitotic fidelity by coordinating spindle positioning and cell-cell adhesion. Nat Commun 2014; 5:5826. [PMID: 25518808 PMCID: PMC4284802 DOI: 10.1038/ncomms6826] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 11/07/2014] [Indexed: 02/07/2023] Open
Abstract
Dividing epithelial cells need to coordinate spindle positioning with shape changes to maintain cell–cell adhesion. Microtubule interactions with the cell cortex regulate mitotic spindle positioning within the plane of division. How the spindle crosstalks with the actin cytoskeleton to ensure faithful mitosis and spindle positioning is unclear. Here we demonstrate that the tumour suppressor DLC2, a negative regulator of Cdc42, and the interacting kinesin Kif1B coordinate cell junction maintenance and planar spindle positioning by regulating microtubule growth and crosstalk with the actin cytoskeleton. Loss of DLC2 induces the mislocalization of Kif1B, increased Cdc42 activity and cortical recruitment of the Cdc42 effector mDia3, a microtubule stabilizer and promoter of actin dynamics. Accordingly, DLC2 or Kif1B depletion promotes microtubule stabilization, defective spindle positioning, chromosome misalignment and aneuploidy. The tumour suppressor DLC2 and Kif1B are thus central components of a signalling network that guides spindle positioning, cell–cell adhesion and mitotic fidelity. Epithelial cells must position their mitotic spindle correctly to maintain cell–cell adhesion. Here Vitiello et al. show that the tumour suppressor DLC2 and the mitotic kinesin Kif1b coordinate microtubule–actin interactions upstream of mDia3, guiding spindle positioning and mitotic fidelity.
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22
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Tripathi BK, Qian X, Mertins P, Wang D, Papageorge AG, Carr SA, Lowy DR. CDK5 is a major regulator of the tumor suppressor DLC1. ACTA ACUST UNITED AC 2014; 207:627-42. [PMID: 25452387 PMCID: PMC4259810 DOI: 10.1083/jcb.201405105] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
CDK5 activates the tumor suppressor DLC1 by phosphorylating and diminishing the binding of an autoinhibitory region of DLC1 to its Rho-GAP domain and allows it to localize to focal adhesions. DLC1 is a tumor suppressor protein whose full activity depends on its presence at focal adhesions, its Rho–GTPase activating protein (Rho-GAP) function, and its ability to bind several ligands, including tensin and talin. However, the mechanisms that regulate and coordinate these activities remain poorly understood. Here we identify CDK5, a predominantly cytoplasmic serine/threonine kinase, as an important regulator of DLC1 functions. The CDK5 kinase phosphorylates four serines in DLC1 located N-terminal to the Rho-GAP domain. When not phosphorylated, this N-terminal region functions as an autoinhibitory domain that places DLC1 in a closed, inactive conformation by efficiently binding to the Rho-GAP domain. CDK5 phosphorylation reduces this binding and orchestrates the coordinate activation DLC1, including its localization to focal adhesions, its Rho-GAP activity, and its ability to bind tensin and talin. In cancer, these anti-oncogenic effects of CDK5 can provide selective pressure for the down-regulation of DLC1, which occurs frequently in tumors, and can contribute to the pro-oncogenic activity of CDK5 in lung adenocarcinoma.
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Affiliation(s)
- Brajendra K Tripathi
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda 20892, MD
| | - Xiaolan Qian
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda 20892, MD
| | | | - Dunrui Wang
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda 20892, MD
| | - Alex G Papageorge
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda 20892, MD
| | - Steven A Carr
- The Broad Institute of MIT and Harvard, Cambridge 02142, MA
| | - Douglas R Lowy
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda 20892, MD
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23
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Jaiswal M, Dvorsky R, Amin E, Risse SL, Fansa EK, Zhang SC, Taha MS, Gauhar AR, Nakhaei-Rad S, Kordes C, Koessmeier KT, Cirstea IC, Olayioye MA, Häussinger D, Ahmadian MR. Functional cross-talk between ras and rho pathways: a Ras-specific GTPase-activating protein (p120RasGAP) competitively inhibits the RhoGAP activity of deleted in liver cancer (DLC) tumor suppressor by masking the catalytic arginine finger. J Biol Chem 2014; 289:6839-6849. [PMID: 24443565 DOI: 10.1074/jbc.m113.527655] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The three deleted in liver cancer genes (DLC1-3) encode Rho-specific GTPase-activating proteins (RhoGAPs). Their expression is frequently silenced in a variety of cancers. The RhoGAP activity, which is required for full DLC-dependent tumor suppressor activity, can be inhibited by the Src homology 3 (SH3) domain of a Ras-specific GAP (p120RasGAP). Here, we comprehensively investigated the molecular mechanism underlying cross-talk between two distinct regulators of small GTP-binding proteins using structural and biochemical methods. We demonstrate that only the SH3 domain of p120 selectively inhibits the RhoGAP activity of all three DLC isoforms as compared with a large set of other representative SH3 or RhoGAP proteins. Structural and mutational analyses provide new insights into a putative interaction mode of the p120 SH3 domain with the DLC1 RhoGAP domain that is atypical and does not follow the classical PXXP-directed interaction. Hence, p120 associates with the DLC1 RhoGAP domain by targeting the catalytic arginine finger and thus by competitively and very potently inhibiting RhoGAP activity. The novel findings of this study shed light on the molecular mechanisms underlying the DLC inhibitory effects of p120 and suggest a functional cross-talk between Ras and Rho proteins at the level of regulatory proteins.
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Affiliation(s)
- Mamta Jaiswal
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Radovan Dvorsky
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Ehsan Amin
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Sarah L Risse
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Eyad K Fansa
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Si-Cai Zhang
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Mohamed S Taha
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Aziz R Gauhar
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Saeideh Nakhaei-Rad
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Claus Kordes
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf
| | - Katja T Koessmeier
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf
| | - Ion C Cirstea
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf; Leibniz Institute for Age Research, 07745 Jena
| | - Monilola A Olayioye
- Institute of Cell Biology and Immunology, University of Stuttgart, 70569 Stuttgart, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf
| | - Mohammad R Ahmadian
- Institute of Biochemistry and Molecular Biology II, Heinrich Heine University, 40225 Düsseldorf.
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24
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Khalil BD, Hanna S, Saykali BA, El-Sitt S, Nasrallah A, Marston D, El-Sabban M, Hahn KM, Symons M, El-Sibai M. The regulation of RhoA at focal adhesions by StarD13 is important for astrocytoma cell motility. Exp Cell Res 2013; 321:109-22. [PMID: 24333506 DOI: 10.1016/j.yexcr.2013.11.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 11/27/2013] [Accepted: 11/29/2013] [Indexed: 10/25/2022]
Abstract
Malignant astrocytomas are highly invasive into adjacent and distant regions of the normal brain. Rho GTPases are small monomeric G proteins that play important roles in cytoskeleton rearrangement, cell motility, and tumor invasion. In the present study, we show that the knock down of StarD13, a GTPase activating protein (GAP) for RhoA and Cdc42, inhibits astrocytoma cell migration through modulating focal adhesion dynamics and cell adhesion. This effect is mediated by the resulting constitutive activation of RhoA and the subsequent indirect inhibition of Rac. Using Total Internal Reflection Fluorescence (TIRF)-based Förster Resonance Energy Transfer (FRET), we show that RhoA activity localizes with focal adhesions at the basal surface of astrocytoma cells. Moreover, the knock down of StarD13 inhibits the cycling of RhoA activation at the rear edge of cells, which makes them defective in retracting their tail. This study highlights the importance of the regulation of RhoA activity in focal adhesions of astrocytoma cells and establishes StarD13 as a GAP playing a major role in this process.
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Affiliation(s)
- Bassem D Khalil
- Department of Natural Sciences, The Lebanese American University, P.O. Box: 13-5053, Chouran, Beirut 1102 2801, Lebanon
| | - Samer Hanna
- Department of Natural Sciences, The Lebanese American University, P.O. Box: 13-5053, Chouran, Beirut 1102 2801, Lebanon
| | - Bechara A Saykali
- Department of Natural Sciences, The Lebanese American University, P.O. Box: 13-5053, Chouran, Beirut 1102 2801, Lebanon
| | - Sally El-Sitt
- Department of Natural Sciences, The Lebanese American University, P.O. Box: 13-5053, Chouran, Beirut 1102 2801, Lebanon
| | - Anita Nasrallah
- Department of Natural Sciences, The Lebanese American University, P.O. Box: 13-5053, Chouran, Beirut 1102 2801, Lebanon
| | - Daniel Marston
- Department of Pharmacology, University of North Carolina School of Medicine, CB7365, Chapel Hill, NC27599, USA
| | - Marwan El-Sabban
- Department of Human Morphology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Klaus M Hahn
- Department of Pharmacology, University of North Carolina School of Medicine, CB7365, Chapel Hill, NC27599, USA
| | - Marc Symons
- Center for Oncology and Cell Biology, The Feinstein Institute for Medical Research at North Shore-LIJ, North Shore University Hospital, Manhasset, NY 11030, USA
| | - Mirvat El-Sibai
- Department of Natural Sciences, The Lebanese American University, P.O. Box: 13-5053, Chouran, Beirut 1102 2801, Lebanon.
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25
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CRL4A-FBXW5-mediated degradation of DLC1 Rho GTPase-activating protein tumor suppressor promotes non-small cell lung cancer cell growth. Proc Natl Acad Sci U S A 2013; 110:16868-73. [PMID: 24082123 DOI: 10.1073/pnas.1306358110] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
DLC1 encodes a RhoA GTPase-activating protein and tumor suppressor lost in cancer by genomic deletion or epigenetic silencing and loss of DLC1 gene transcription. We unexpectedly identified non-small cell lung cancer (NSCLC) cell lines and tumor tissue that expressed DLC1 mRNA yet lacked DLC1 protein expression. We determined that DLC1 was ubiquitinated and degraded by cullin 4A-RING ubiquitin ligase (CRL4A) complex interaction with DDB1 and the FBXW5 substrate receptor. siRNA-mediated suppression of cullin 4A, DDB1, or FBXW5 expression restored DLC1 protein expression in NSCLC cell lines. FBXW5 suppression-induced DLC1 reexpression was associated with a reduction in the levels of activated RhoA-GTP and in RhoA effector signaling. Finally, FBXW5 suppression caused a DLC1-dependent decrease in NSCLC anchorage-dependent and -independent proliferation. In summary, we identify a posttranslational mechanism for loss of DLC1 and a linkage between CRL4A-FBXW5-associated oncogenesis and regulation of RhoA signaling.
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