34 results on '"Chhabra Y"'
Search Results
2. Growth Hormone Stops Excessive Inflammation After Partial Hepatectomy, Allowing Liver Regeneration and Survival Through Induction of H2-Bl/HLA-G
- Author
-
Ishikawa, M, Brooks, AJ, Fernandez-Rojo, MA, Medina, J, Chhabra, Y, Minami, S, Tunny, KA, Parton, RG, Vivian, JP, Rossjohn, J, Chikani, V, Ramm, GA, Ho, KKY, Waters, MJ, Ishikawa, M, Brooks, AJ, Fernandez-Rojo, MA, Medina, J, Chhabra, Y, Minami, S, Tunny, KA, Parton, RG, Vivian, JP, Rossjohn, J, Chikani, V, Ramm, GA, Ho, KKY, and Waters, MJ
- Abstract
BACKGROUND AND AIMS: Growth hormone (GH) is important for liver regeneration after partial hepatectomy (PHx). We investigated this process in C57BL/6 mice that express different forms of the GH receptor (GHR) with deletions in key signaling domains. APPROACH AND RESULTS: PHx was performed on C57BL/6 mice lacking GHR (Ghr-/- ), disabled for all GH-dependent Janus kinase 2 signaling (Box1-/- ), or lacking only GH-dependent signal transducer and activator of transcription 5 (STAT5) signaling (Ghr391-/- ), and wild-type littermates. C57BL/6 Ghr-/- mice showed striking mortality within 48 hours after PHx, whereas Box1-/- or Ghr391-/- mice survived with normal liver regeneration. Ghr-/- mortality was associated with increased apoptosis and elevated natural killer/natural killer T cell and macrophage cell markers. We identified H2-Bl, a key immunotolerance protein, which is up-regulated by PHx through a GH-mediated, Janus kinase 2-independent, SRC family kinase-dependent pathway. GH treatment was confirmed to up-regulate expression of the human homolog of H2-Bl (human leukocyte antigen G [HLA-G]) in primary human hepatocytes and in the serum of GH-deficient patients. We find that injury-associated innate immune attack by natural killer/natural killer T cell and macrophage cells are instrumental in the failure of liver regeneration, and this can be overcome in Ghr-/- mice by adenoviral delivery of H2-Bl or by infusion of HLA-G protein. Further, H2-Bl knockdown in wild-type C57BL/6 mice showed elevated markers of inflammation after PHx, whereas Ghr-/- backcrossed on a strain with high endogenous H2-Bl expression showed a high rate of survival following PHx. CONCLUSIONS: GH induction of H2-Bl expression is crucial for reducing innate immune-mediated apoptosis and promoting survival after PHx in C57BL/6 mice. Treatment with HLA-G may lead to improved clinical outcomes following liver surgery or transplantation.
- Published
- 2020
3. A growth hormone receptor SNP promotes lung cancer by impairment of SOCS2-mediated degradation
- Author
-
Chhabra, Y., Wong, H. Y., Nikolajsen, Louise Fletcher, Steinocher, Helena, Papadopulos, A., Tunny, K. A., Meunier, F. A., Smith, A. G., Kragelund, Birthe Brandt, Brooks, A. J., Waters, M. J., Chhabra, Y., Wong, H. Y., Nikolajsen, Louise Fletcher, Steinocher, Helena, Papadopulos, A., Tunny, K. A., Meunier, F. A., Smith, A. G., Kragelund, Birthe Brandt, Brooks, A. J., and Waters, M. J.
- Abstract
Both humans and mice lacking functional growth hormone (GH) receptors are known to be resistant to cancer. Further, autocrine GH has been reported to act as a cancer promoter. Here we present the first example of a variant of the GH receptor (GHR) associated with cancer promotion, in this case lung cancer. We show that the GHRP495T variant located in the receptor intracellular domain is able to prolong the GH signal in vitro using stably expressing mouse pro-B-cell and human lung cell lines. This is relevant because GH secretion is pulsatile, and extending the signal duration makes it resemble autocrine GH action. Signal duration for the activated GHR is primarily controlled by suppressor of cytokine signalling 2 (SOCS2), the substrate recognition component of the E3 protein ligase responsible for ubiquitinylation and degradation of the GHR. SOCS2 is induced by a GH pulse and we show that SOCS2 binding to the GHR is impaired by a threonine substitution at Pro 495. This results in decreased internalisation and degradation of the receptor evident in TIRF microscopy and by measurement of mature (surface) receptor expression. Mutational analysis showed that the residue at position 495 impairs SOCS2 binding only when a threonine is present, consistent with interference with the adjacent Thr494. The latter is key for SOCS2 binding, together with nearby Tyr487, which must be phosphorylated for SOCS2 binding. We also undertook nuclear magnetic resonance spectroscopy approach for structural comparison of the SOCS2 binding scaffold Ile455-Ser588, and concluded that this single substitution has altered the structure of the SOCS2 binding site. Importantly, we find that lung BEAS-2B cells expressing GHRP495T display increased expression of transcripts associated with tumour proliferation, epithelial-mesenchymal transition and metastases (TWIST1, SNAI2, EGFR, MYC and CCND1) at 2 h after a GH pulse. This is consistent with prolonged GH signalling acting to promote cancer progre
- Published
- 2018
4. A growth hormone receptor SNP promotes lung cancer by impairment of SOCS2-mediated degradation
- Author
-
Chhabra, Y, primary, Wong, H Y, additional, Nikolajsen, L F, additional, Steinocher, H, additional, Papadopulos, A, additional, Tunny, K A, additional, Meunier, F A, additional, Smith, A G, additional, Kragelund, B B, additional, Brooks, A J, additional, and Waters, M J, additional
- Published
- 2017
- Full Text
- View/download PDF
5. Long-term outcome of renal donors in a tertiary care centre in India
- Author
-
Ram, Pranith, primary, Bhowmik, D., additional, Chhabra, Y., additional, Yadav, R.K., additional, Bagchi, S., additional, Mahajan, S., additional, and Agarwal, S.K., additional
- Published
- 2016
- Full Text
- View/download PDF
6. OR5-4: The choice of growth hormone receptor signalling pathway determines longevity
- Author
-
Chhabra, Y., primary, Nelson, C.N., additional, Plescher, M., additional, Brooks, T., additional, and Waters, M.J., additional
- Published
- 2014
- Full Text
- View/download PDF
7. A growth hormone receptor SNP promotes lung cancer by impairment of SOCS2-mediated degradation
- Author
-
Chhabra, Y, Wong, H Y, Nikolajsen, L F, Steinocher, H, Papadopulos, A, Tunny, K A, Meunier, F A, Smith, A G, Kragelund, B B, Brooks, A J, and Waters, M J
- Abstract
Both humans and mice lacking functional growth hormone (GH) receptors are known to be resistant to cancer. Further, autocrine GH has been reported to act as a cancer promoter. Here we present the first example of a variant of the GH receptor (GHR) associated with cancer promotion, in this case lung cancer. We show that the GHRP495T variant located in the receptor intracellular domain is able to prolong the GH signal in vitro using stably expressing mouse pro-B-cell and human lung cell lines. This is relevant because GH secretion is pulsatile, and extending the signal duration makes it resemble autocrine GH action. Signal duration for the activated GHR is primarily controlled by suppressor of cytokine signalling 2 (SOCS2), the substrate recognition component of the E3 protein ligase responsible for ubiquitinylation and degradation of the GHR. SOCS2 is induced by a GH pulse and we show that SOCS2 binding to the GHR is impaired by a threonine substitution at Pro 495. This results in decreased internalisation and degradation of the receptor evident in TIRF microscopy and by measurement of mature (surface) receptor expression. Mutational analysis showed that the residue at position 495 impairs SOCS2 binding only when a threonine is present, consistent with interference with the adjacent Thr494. The latter is key for SOCS2 binding, together with nearby Tyr487, which must be phosphorylated for SOCS2 binding. We also undertook nuclear magnetic resonance spectroscopy approach for structural comparison of the SOCS2 binding scaffold Ile455-Ser588, and concluded that this single substitution has altered the structure of the SOCS2 binding site. Importantly, we find that lung BEAS-2B cells expressing GHRP495T display increased expression of transcripts associated with tumour proliferation, epithelial–mesenchymal transition and metastases (TWIST1, SNAI2, EGFR, MYC and CCND1) at 2 h after a GH pulse. This is consistent with prolonged GH signalling acting to promote cancer progression in lung cancer.
- Published
- 2018
- Full Text
- View/download PDF
8. Aged fibroblast-derived extracellular vesicles promote angiogenesis in melanoma.
- Author
-
Hüser L, Chhabra Y, Gololobova O, Wang V, Liu G, Dixit A, Rocha MR, Harper EI, Fane ME, Marino-Bravante GE, Zabransky DJ, Cai KQ, Utikal J, Slusher BS, Walston J, Lipson EJ, Witwer KW, and Weeraratna AT
- Subjects
- Humans, Tumor Microenvironment, Cell Line, Tumor, Skin Neoplasms pathology, Skin Neoplasms metabolism, Skin Neoplasms genetics, Aging metabolism, Aging pathology, Endothelial Cells metabolism, Endothelial Cells pathology, Animals, Angiogenesis, Extracellular Vesicles metabolism, Melanoma metabolism, Melanoma pathology, Neovascularization, Pathologic metabolism, Neovascularization, Pathologic pathology, Fibroblasts metabolism, Fibroblasts pathology, Tetraspanin 29 metabolism, Tetraspanin 29 genetics
- Abstract
Advancing age is a negative prognostic factor for cutaneous melanoma. However, the role of extracellular vesicles (EVs) within the melanoma tumor microenvironment (TME) has remained unexplored in the context of aging. While the size and morphology of the EVs isolated from young vs. aged fibroblasts remained unaltered, the contents of the protein cargo were changed. Aging reduced the expression of the tetraspanin CD9 in both the dermal fibroblasts and released EVs. CD9 is a crucial regulator of EV cargo sorting. Modulating the CD9 expression in fibroblasts was sufficient to alter its levels in EVs. Mass spectrometry analysis of EVs released by CD9 knockdown (KD) vs. control cells revealed a significant increase in angiopoietin-like protein 2 (ANGPTL2), an angiogenesis promoter. Analysis of primary endothelial cells confirmed increased sprouting under CD9 KD conditions. Together, our data indicate that aged EVs play an important role in promoting a tumor-permissive microenvironment., Competing Interests: Declaration of interests A.T.W. is on the boards of reGAIN Therapeutics and the Melanoma Research Foundation and the scientific advisory committee of the V Foundation. D.J.Z. reports grant funding (paid to Johns Hopkins University) from Roche/Genentech., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
9. Sex-dependent effects in the aged melanoma tumor microenvironment influence invasion and resistance to targeted therapy.
- Author
-
Chhabra Y, Fane ME, Pramod S, Hüser L, Zabransky DJ, Wang V, Dixit A, Zhao R, Kumah E, Brezka ML, Truskowski K, Nandi A, Marino-Bravante GE, Carey AE, Gour N, Maranto DA, Rocha MR, Harper EI, Ruiz J, Lipson EJ, Jaffee EM, Bibee K, Sunshine JC, Ji H, and Weeraratna AT
- Abstract
There is documented sex disparity in cutaneous melanoma incidence and mortality, increasing disproportionately with age and in the male sex. However, the underlying mechanisms remain unclear. While biological sex differences and inherent immune response variability have been assessed in tumor cells, the role of the tumor-surrounding microenvironment, contextually in aging, has been overlooked. Here, we show that skin fibroblasts undergo age-mediated, sex-dependent changes in their proliferation, senescence, ROS levels, and stress response. We find that aged male fibroblasts selectively drive an invasive, therapy-resistant phenotype in melanoma cells and promote metastasis in aged male mice by increasing AXL expression. Intrinsic aging in male fibroblasts mediated by EZH2 decline increases BMP2 secretion, which in turn drives the slower-cycling, highly invasive, and therapy-resistant melanoma cell phenotype, characteristic of the aged male TME. Inhibition of BMP2 activity blocks the emergence of invasive phenotypes and sensitizes melanoma cells to BRAF/MEK inhibition., Competing Interests: Declaration of interests A.T.W. is on the board of reGAIN Therapeutics and the Melanoma Research Foundation. E.M.J. reports other support from Abmeta, personal fees from Genocea, personal fees from Achilles, personal fees from DragonFly, personal fees from Candel Therapeutics, other support from the Parker Institute, grants and other support from Lustgarten, personal fees from Carta, grants and other support from Genentech, grants and other support from AstraZeneca, personal fees from NextCure, and grants and other support from Break Through Cancer outside of the submitted work. D.J.Z. reports grant funding (paid to Johns Hopkins University) from Roche/Genentech. Y.C. and M.E.F. are affiliated with the Cancer Signaling and Microenvironment program, FoxChase Cancer Center, Philadelphia, PA, USA., (Copyright © 2024 Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
10. Age-Related Increases in IGFBP2 Increase Melanoma Cell Invasion and Lipid Synthesis.
- Author
-
Alicea GM, Patel P, Portuallo ME, Fane ME, Wei M, Chhabra Y, Dixit A, Carey AE, Wang V, Rocha MR, Behera R, Speicher DW, Tang HY, Kossenkov AV, Rebecca VW, Wirtz D, and Weeraratna AT
- Subjects
- Humans, Animals, Mice, Cell Line, Tumor, Fibroblasts metabolism, Fibroblasts pathology, Cell Movement, Aged, Middle Aged, Lipids, Lipid Metabolism, Age Factors, Mice, Inbred C57BL, Insulin-Like Growth Factor Binding Protein 2 metabolism, Insulin-Like Growth Factor Binding Protein 2 genetics, Melanoma pathology, Melanoma metabolism, Neoplasm Invasiveness
- Abstract
Aged patients with melanoma (>65 years old) have more aggressive disease relative to young patients (<55 years old) for reasons that are not completely understood. Analysis of the young and aged secretome from human dermal fibroblasts identified >5-fold levels of IGF-binding protein 2 (IGFBP2) in the aged fibroblast secretome. IGFBP2 functionally triggers upregulation of the PI3K-dependent fatty acid biosynthesis program in melanoma cells. Melanoma cells co-cultured with aged dermal fibroblasts have higher levels of lipids relative to those co-cultured with young dermal fibroblasts, which can be lowered by silencing IGFBP2 expression in fibroblasts prior to treating with conditioned media. Conversely, ectopically treating melanoma cells with recombinant IGFBP2 in the presence of conditioned media from young fibroblasts or overexpressing IGFBP2 in melanoma cells promoted lipid synthesis and accumulation in melanoma cells. Treatment of young mice with rIGFBP2 increases tumor growth. Neutralizing IGFBP2 in vitro reduces migration and invasion in melanoma cells, and in vivo studies demonstrate that neutralizing IGFBP2 in syngeneic aged mice reduces tumor growth and metastasis. Our results suggest that aged dermal fibroblasts increase melanoma cell aggressiveness through increased secretion of IGFBP2, stressing the importance of considering age when designing studies and treatment., Significance: The aged microenvironment drives metastasis in melanoma cells. This study reports that IGFBP2 secretion by aged fibroblasts induces lipid accumulation in melanoma cells, driving an increase in tumor invasiveness. Neutralizing IGFBP2 decreases melanoma tumor growth and metastasis., (©2024 The Authors; Published by the American Association for Cancer Research.)
- Published
- 2024
- Full Text
- View/download PDF
11. Fibroblasts in the Aged Pancreas Drive Pancreatic Cancer Progression.
- Author
-
Zabransky DJ, Chhabra Y, Fane ME, Kartalia E, Leatherman JM, Hüser L, Zimmerman JW, Delitto D, Han S, Armstrong TD, Charmsaz S, Guinn S, Pramod S, Thompson ED, Hughes SJ, O'Connell J, Egan JM, Jaffee EM, and Weeraratna AT
- Subjects
- Animals, Mice, Growth Differentiation Factor 15 genetics, Growth Differentiation Factor 15 therapeutic use, Proto-Oncogene Proteins c-akt, Pancreas pathology, Fibroblasts pathology, Tumor Microenvironment, Cell Line, Tumor, Pancreatic Neoplasms pathology, Cancer-Associated Fibroblasts pathology
- Abstract
Pancreatic cancer is more prevalent in older individuals and often carries a poorer prognosis for them. The relationship between the microenvironment and pancreatic cancer is multifactorial, and age-related changes in nonmalignant cells in the tumor microenvironment may play a key role in promoting cancer aggressiveness. Because fibroblasts have profound impacts on pancreatic cancer progression, we investigated whether age-related changes in pancreatic fibroblasts influence cancer growth and metastasis. Proteomics analysis revealed that aged fibroblasts secrete different factors than young fibroblasts, including increased growth/differentiation factor 15 (GDF-15). Treating young mice with GDF-15 enhanced tumor growth, whereas aged GDF-15 knockout mice showed reduced tumor growth. GDF-15 activated AKT, rendering tumors sensitive to AKT inhibition in an aged but not young microenvironment. These data provide evidence for how aging alters pancreatic fibroblasts and promotes tumor progression, providing potential therapeutic targets and avenues for studying pancreatic cancer while accounting for the effects of aging., Significance: Aged pancreatic fibroblasts secrete GDF-15 and activate AKT signaling to promote pancreatic cancer growth, highlighting the critical role of aging-mediated changes in the pancreatic cancer microenvironment in driving tumor progression. See related commentary by Isaacson et al., p. 1185., (©2024 American Association for Cancer Research.)
- Published
- 2024
- Full Text
- View/download PDF
12. Age-dependent loss of HAPLN1 erodes vascular integrity via indirect upregulation of endothelial ICAM1 in melanoma.
- Author
-
Marino-Bravante GE, Carey AE, Hüser L, Dixit A, Wang V, Kaur A, Liu Y, Ding S, Schnellmann R, Gerecht S, Gu L, Eisinger-Mathason TSK, Chhabra Y, and Weeraratna AT
- Subjects
- Aged, Animals, Humans, Mice, Collagen metabolism, Extracellular Matrix Proteins genetics, Intercellular Adhesion Molecule-1 genetics, Up-Regulation, Melanoma genetics, Skin Neoplasms genetics
- Abstract
Melanoma, the most lethal form of skin cancer, often has worse outcomes in older patients. We previously demonstrated that an age-related decrease in the secreted extracellular matrix (ECM) protein HAPLN1 has a role in slowing melanoma progression. Here we show that HAPLN1 in the dermal ECM is sufficient to maintain the integrity of melanoma-associated blood vessels, as indicated by increased collagen and VE-cadherin expression. Specifically, we show that HAPLN1 in the ECM increases hyaluronic acid and decreases endothelial cell expression of ICAM1. ICAM1 phosphorylates and internalizes VE-cadherin, a critical determinant of vascular integrity, resulting in permeable blood vessels. We found that blocking ICAM1 reduces tumor size and metastasis in older mice. These results suggest that HAPLN1 alters endothelial ICAM1expression in an indirect, matrix-dependent manner. Targeting ICAM1 could be a potential treatment strategy for older patients with melanoma, emphasizing the role of aging in tumorigenesis., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)
- Published
- 2024
- Full Text
- View/download PDF
13. Tyrosine kinases compete for growth hormone receptor binding and regulate receptor mobility and degradation.
- Author
-
Chhabra Y, Seiffert P, Gormal RS, Vullings M, Lee CMM, Wallis TP, Dehkhoda F, Indrakumar S, Jacobsen NL, Lindorff-Larsen K, Durisic N, Waters MJ, Meunier FA, Kragelund BB, and Brooks AJ
- Subjects
- Janus Kinase 2 metabolism, Signal Transduction, Growth Hormone metabolism, Tyrosine metabolism, Phosphorylation, Receptors, Somatotropin metabolism, Human Growth Hormone metabolism
- Abstract
Growth hormone (GH) acts via JAK2 and LYN to regulate growth, metabolism, and neural function. However, the relationship between these tyrosine kinases remains enigmatic. Through an interdisciplinary approach combining cell biology, structural biology, computation, and single-particle tracking on live cells, we find overlapping LYN and JAK2 Box1-Box2-binding regions in GH receptor (GHR). Our data implicate direct competition between JAK2 and LYN for GHR binding and imply divergent signaling profiles. We show that GHR exhibits distinct mobility states within the cell membrane and that activation of LYN by GH mediates GHR immobilization, thereby initiating its nanoclustering in the membrane. Importantly, we observe that LYN mediates cytokine receptor degradation, thereby controlling receptor turnover and activity, and this applies to related cytokine receptors. Our study offers insight into the molecular interactions of LYN with GHR and highlights important functions for LYN in regulating GHR nanoclustering, signaling, and degradation, traits broadly relevant to many cytokine receptors., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
14. Correction: sFRP2 Supersedes VEGF as an Age-related Driver of Angiogenesis in Melanoma, Affecting Response to Anti-VEGF Therapy in Older Patients.
- Author
-
Fane ME, Ecker BL, Kaur A, Marino GE, Alicea GM, Douglass SM, Chhabra Y, Webster MR, Marshall A, Colling R, Espinosa O, Coupe N, Maroo N, Campo L, Middleton MR, Corrie P, Xu X, Karakousis GC, and Weeraratna AT
- Published
- 2023
- Full Text
- View/download PDF
15. Fibroblasts in cancer: Unity in heterogeneity.
- Author
-
Chhabra Y and Weeraratna AT
- Subjects
- Humans, Carcinogenesis, Tumor Microenvironment physiology, Cancer-Associated Fibroblasts metabolism, Neoplasms pathology
- Abstract
Tumor cells do not exist in isolation in vivo, and carcinogenesis depends on the surrounding tumor microenvironment (TME), composed of a myriad of cell types and biophysical and biochemical components. Fibroblasts are integral in maintaining tissue homeostasis. However, even before a tumor develops, pro-tumorigenic fibroblasts in close proximity can provide the fertile 'soil' to the cancer 'seed' and are known as cancer-associated fibroblasts (CAFs). In response to intrinsic and extrinsic stressors, CAFs reorganize the TME enabling metastasis, therapeutic resistance, dormancy and reactivation by secreting cellular and acellular factors. In this review, we summarize the recent discoveries on CAF-mediated cancer progression with a particular focus on fibroblast heterogeneity and plasticity., Competing Interests: Declaration of interests The authors declare no competing interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
16. Reciprocal Regulation of BRN2 and NOTCH1/2 Signaling Synergistically Drives Melanoma Cell Migration and Invasion.
- Author
-
Fane ME, Chhabra Y, Spoerri L, Simmons JL, Ludwig R, Bonvin E, Goding CR, Sturm RA, Boyle GM, Haass NK, Piper M, and Smith AG
- Subjects
- Cell Line, Tumor, Cell Movement, Gene Expression Regulation, Neoplastic, Humans, Microphthalmia-Associated Transcription Factor genetics, Neoplasm Invasiveness genetics, Homeodomain Proteins genetics, Melanoma pathology, POU Domain Factors genetics, Receptor, Notch1 genetics, Receptor, Notch2 genetics
- Abstract
Phenotypic plasticity drives cancer progression, impacts treatment response, and is a major driver of therapeutic resistance. In melanoma, a regulatory axis between the MITF and BRN2 transcription factors has been reported to promote tumor heterogeneity by mediating switching between proliferative and invasive phenotypes, respectively. Despite strong evidence that subpopulations of cells that exhibit a BRN2
high /MITFlow expression profile switch to a predominantly invasive phenotype, the mechanisms by which this switch is propagated and promotes invasion remain poorly defined. We have found that a reciprocal relationship between BRN2 and NOTCH1/2 signaling exists in melanoma cells in vitro, within patient datasets, and in in vivo primary and metastatic human tumors that bolsters acquisition of invasiveness. Working through the epigenetic modulator EZH2, the BRN2‒NOTCH1/2 axis is potentially a key mechanism by which the invasive phenotype is maintained. Given the emergence of agents targeting both EZH2 and NOTCH, understanding the mechanism through which BRN2 promotes heterogeneity may provide crucial biomarkers to predict treatment response to prevent metastasis., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2022
- Full Text
- View/download PDF
17. Stromal changes in the aged lung induce an emergence from melanoma dormancy.
- Author
-
Fane ME, Chhabra Y, Alicea GM, Maranto DA, Douglass SM, Webster MR, Rebecca VW, Marino GE, Almeida F, Ecker BL, Zabransky DJ, Hüser L, Beer T, Tang HY, Kossenkov A, Herlyn M, Speicher DW, Xu W, Xu X, Jaffee EM, Aguirre-Ghiso JA, and Weeraratna AT
- Subjects
- Aged, Fibroblasts pathology, Humans, Neoplasm Invasiveness pathology, Neoplasm, Residual, Proto-Oncogene Proteins, Receptor Protein-Tyrosine Kinases, Skin pathology, Wnt-5a Protein, c-Mer Tyrosine Kinase, Axl Receptor Tyrosine Kinase, Aging pathology, Lung pathology, Melanoma pathology, Neoplasm Metastasis pathology, Stromal Cells pathology, Tumor Microenvironment
- Abstract
Disseminated cancer cells from primary tumours can seed in distal tissues, but may take several years to form overt metastases, a phenomenon that is termed tumour dormancy. Despite its importance in metastasis and residual disease, few studies have been able to successfully characterize dormancy within melanoma. Here we show that the aged lung microenvironment facilitates a permissive niche for efficient outgrowth of dormant disseminated cancer cells-in contrast to the aged skin, in which age-related changes suppress melanoma growth but drive dissemination. These microenvironmental complexities can be explained by the phenotype switching model, which argues that melanoma cells switch between a proliferative cell state and a slower-cycling, invasive state
1-3 . It was previously shown that dermal fibroblasts promote phenotype switching in melanoma during ageing4-8 . We now identify WNT5A as an activator of dormancy in melanoma disseminated cancer cells within the lung, which initially enables the efficient dissemination and seeding of melanoma cells in metastatic niches. Age-induced reprogramming of lung fibroblasts increases their secretion of the soluble WNT antagonist sFRP1, which inhibits WNT5A in melanoma cells and thereby enables efficient metastatic outgrowth. We also identify the tyrosine kinase receptors AXL and MER as promoting a dormancy-to-reactivation axis within melanoma cells. Overall, we find that age-induced changes in distal metastatic microenvironments promote the efficient reactivation of dormant melanoma cells in the lung., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)- Published
- 2022
- Full Text
- View/download PDF
18. Myeloid-Derived Suppressor Cells Are a Major Source of Wnt5A in the Melanoma Microenvironment and Depend on Wnt5A for Full Suppressive Activity.
- Author
-
Douglass SM, Fane ME, Sanseviero E, Ecker BL, Kugel CH 3rd, Behera R, Kumar V, Tcyganov EN, Yin X, Liu Q, Chhabra Y, Alicea GM, Kuruvilla R, Gabrilovich DI, and Weeraratna AT
- Subjects
- Animals, Antigens, CD metabolism, Arginase metabolism, Cell Line, Tumor, Female, Lung Neoplasms secondary, Lymphocytes, Tumor-Infiltrating metabolism, Male, Melanoma secondary, Mice, Mice, Inbred C57BL, Mice, Transgenic, Myeloid-Derived Suppressor Cells immunology, Neoplasm Invasiveness, Programmed Cell Death 1 Receptor metabolism, T-Lymphocytes, Regulatory metabolism, Transforming Growth Factor beta1 metabolism, Lymphocyte Activation Gene 3 Protein, Melanoma metabolism, Myeloid-Derived Suppressor Cells metabolism, Tumor Microenvironment, Wnt-5a Protein metabolism
- Abstract
Metastatic dissemination remains a significant barrier to successful therapy for melanoma. Wnt5A is a potent driver of invasion in melanoma and is believed to be secreted from the tumor microenvironment (TME). Our data suggest that myeloid-derived suppressor cells (MDSC) in the TME are a major source of Wnt5A and are reliant upon Wnt5A for multiple actions. Knockdown of Wnt5A specifically in the myeloid cells demonstrated a clear decrease in Wnt5A expression within the TME in vivo as well as a decrease in intratumoral MDSC and regulatory T cell (Treg). Wnt5A knockdown also decreased the immunosuppressive nature of MDSC and decreased expression of TGFβ1 and arginase 1. In the presence of Wnt5A-depleted MDSC, tumor-infiltrating lymphocytes expressed decreased PD-1 and LAG3, suggesting a less exhausted phenotype. Myeloid-specific Wnt5A knockdown also led to decreased lung metastasis. Tumor-infiltrating MDSC from control animals showed a strong positive correlation with Treg, which was completely ablated in animals with Wnt5A-negative MDSC. Overall, our data suggest that while MDSC contribute to an immunosuppressive and less immunogenic environment, they exhibit an additional function as the major source of Wnt5A in the TME. SIGNIFICANCE: These findings demonstrate that myeloid cells provide a major source of Wnt5A to facilitate metastatic potential in melanoma cells and rely on Wnt5A for their immunosuppressive function., (©2020 American Association for Cancer Research.)
- Published
- 2021
- Full Text
- View/download PDF
19. Growth Hormone Stops Excessive Inflammation After Partial Hepatectomy, Allowing Liver Regeneration and Survival Through Induction of H2-Bl/HLA-G.
- Author
-
Ishikawa M, Brooks AJ, Fernández-Rojo MA, Medina J, Chhabra Y, Minami S, Tunny KA, Parton RG, Vivian JP, Rossjohn J, Chikani V, Ramm GA, Ho KKY, and Waters MJ
- Subjects
- Animals, Apoptosis immunology, Carrier Proteins genetics, Carrier Proteins metabolism, Cells, Cultured, Coculture Techniques, Gene Knockdown Techniques, H-2 Antigens genetics, HLA-G Antigens genetics, HLA-G Antigens isolation & purification, Hepatectomy, Hepatocytes, Humans, Immunity, Innate, Killer Cells, Natural immunology, Killer Cells, Natural metabolism, Liver surgery, Macrophages immunology, Macrophages metabolism, Mice, Natural Killer T-Cells immunology, Natural Killer T-Cells metabolism, Primary Cell Culture, Recombinant Proteins genetics, Recombinant Proteins immunology, Recombinant Proteins metabolism, Signal Transduction genetics, Signal Transduction immunology, Growth Hormone deficiency, H-2 Antigens metabolism, HLA-G Antigens metabolism, Liver physiology, Liver Regeneration immunology
- Abstract
Background and Aims: Growth hormone (GH) is important for liver regeneration after partial hepatectomy (PHx). We investigated this process in C57BL/6 mice that express different forms of the GH receptor (GHR) with deletions in key signaling domains., Approach and Results: PHx was performed on C57BL/6 mice lacking GHR (Ghr
-/- ), disabled for all GH-dependent Janus kinase 2 signaling (Box1-/- ), or lacking only GH-dependent signal transducer and activator of transcription 5 (STAT5) signaling (Ghr391-/- ), and wild-type littermates. C57BL/6 Ghr-/- mice showed striking mortality within 48 hours after PHx, whereas Box1-/- or Ghr391-/- mice survived with normal liver regeneration. Ghr-/- mortality was associated with increased apoptosis and elevated natural killer/natural killer T cell and macrophage cell markers. We identified H2-Bl, a key immunotolerance protein, which is up-regulated by PHx through a GH-mediated, Janus kinase 2-independent, SRC family kinase-dependent pathway. GH treatment was confirmed to up-regulate expression of the human homolog of H2-Bl (human leukocyte antigen G [HLA-G]) in primary human hepatocytes and in the serum of GH-deficient patients. We find that injury-associated innate immune attack by natural killer/natural killer T cell and macrophage cells are instrumental in the failure of liver regeneration, and this can be overcome in Ghr-/- mice by adenoviral delivery of H2-Bl or by infusion of HLA-G protein. Further, H2-Bl knockdown in wild-type C57BL/6 mice showed elevated markers of inflammation after PHx, whereas Ghr-/- backcrossed on a strain with high endogenous H2-Bl expression showed a high rate of survival following PHx., Conclusions: GH induction of H2-Bl expression is crucial for reducing innate immune-mediated apoptosis and promoting survival after PHx in C57BL/6 mice. Treatment with HLA-G may lead to improved clinical outcomes following liver surgery or transplantation., (© 2020 The Authors. Hepatology published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)- Published
- 2021
- Full Text
- View/download PDF
20. GHR signalling: Receptor activation and degradation mechanisms.
- Author
-
Chhabra Y, Lee CMM, Müller AF, and Brooks AJ
- Subjects
- Animals, Enzyme Activation, Humans, Models, Biological, Receptors, Somatotropin chemistry, src-Family Kinases metabolism, Proteolysis, Receptors, Somatotropin metabolism, Signal Transduction
- Abstract
Growth hormone (GH) actions via initiating cell signalling through the GH receptor (GHR) are important for many physiological processes, in addition to its well-known role in regulating growth. The activation of JAK-STAT signalling by GH is well characterized, however knowledge on GH activation of SRC family kinases (SFKs) is still limited. In this review we summarise the collective knowledge on the activation, regulation, and downstream signalling of GHR. We highlight studies on GH activation of SFKs and the important outcome of this signalling pathway with a focus on the different degradation mechanisms that can regulate GHR availability since this is an area that warrants further study considering its role in tumour progression., (Copyright © 2020 Elsevier B.V. All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
21. sFRP2 Supersedes VEGF as an Age-related Driver of Angiogenesis in Melanoma, Affecting Response to Anti-VEGF Therapy in Older Patients.
- Author
-
Fane ME, Ecker BL, Kaur A, Marino GE, Alicea GM, Douglass SM, Chhabra Y, Webster MR, Marshall A, Colling R, Espinosa O, Coupe N, Maroo N, Campo L, Middleton MR, Corrie P, Xu X, Karakousis GC, and Weeraratna AT
- Subjects
- Age Factors, Aged, Aged, 80 and over, Animals, Bevacizumab administration & dosage, Cell Line, Tumor, Disease-Free Survival, Gene Expression Regulation, Neoplastic drug effects, Humans, Melanoma drug therapy, Melanoma pathology, Mice, Neovascularization, Pathologic drug therapy, Neovascularization, Pathologic pathology, Tumor Microenvironment drug effects, Melanoma genetics, Membrane Proteins genetics, Neovascularization, Pathologic genetics, Vascular Endothelial Growth Factor A genetics
- Abstract
Purpose: Angiogenesis is thought to be critical for tumor metastasis. However, inhibiting angiogenesis using antibodies such as bevacizumab (Avastin), has had little impact on melanoma patient survival. We have demonstrated that both angiogenesis and metastasis are increased in older individuals, and therefore sought to investigate whether there was an age-related difference in response to bevacizumab, and if so, what the underlying mechanism could be., Experimental Design: We analyzed data from the AVAST-M trial of 1,343 patients with melanoma treated with bevacizumab to determine whether there is an age-dependent response to bevacizumab. We also examined the age-dependent expression of VEGF and its cognate receptors in patients with melanoma, while using syngeneic melanoma animal models to target VEGF in young versus old mice. We also examined the age-related proangiogenic factor secreted frizzled-related protein 2 (sFRP2) and whether it could modulate response to anti-VEGF therapy., Results: We show that older patients respond poorly to bevacizumab, whereas younger patients show improvement in both disease-free survival and overall survival. We find that targeting VEGF does not ablate angiogenesis in an aged mouse model, while sFRP2 promotes angiogenesis in vitro and in young mice. Targeting sFRP2 in aged mice successfully ablates angiogenesis, while the effects of targeting VEGF in young mice can be overcome by increasing sFRP2., Conclusions: VEGF is decreased during aging, thereby reducing response to bevacizumab. Despite the decrease in VEGF, angiogenesis is increased because of an increase in sFRP2 in the aged tumor microenvironment. These results stress the importance of considering age as a factor for designing targeted therapies., (©2020 American Association for Cancer Research.)
- Published
- 2020
- Full Text
- View/download PDF
22. Novel drivers and modifiers of MPL-dependent oncogenic transformation identified by deep mutational scanning.
- Author
-
Bridgford JL, Lee SM, Lee CMM, Guglielmelli P, Rumi E, Pietra D, Wilcox S, Chhabra Y, Rubin AF, Cazzola M, Vannucchi AM, Brooks AJ, Call ME, and Call MJ
- Subjects
- Animals, Cell Line, Exons, Humans, Mice, Models, Molecular, Mutation, Protein Domains, Receptors, Thrombopoietin chemistry, Amino Acid Substitution, Myeloproliferative Disorders genetics, Receptors, Thrombopoietin genetics
- Abstract
The single transmembrane domain (TMD) of the human thrombopoietin receptor (TpoR/myeloproliferative leukemia [MPL] protein), encoded by exon 10 of the MPL gene, is a hotspot for somatic mutations associated with myeloproliferative neoplasms (MPNs). Approximately 6% and 14% of JAK2 V617F- essential thrombocythemia and primary myelofibrosis patients, respectively, have "canonical" MPL exon 10 driver mutations W515L/K/R/A or S505N, which generate constitutively active receptors and consequent loss of Tpo dependence. Other "noncanonical" MPL exon 10 mutations have also been identified in patients, both alone and in combination with canonical mutations, but, in almost all cases, their functional consequences and relevance to disease are unknown. Here, we used a deep mutational scanning approach to evaluate all possible single amino acid substitutions in the human TpoR TMD for their ability to confer cytokine-independent growth in Ba/F3 cells. We identified all currently recognized driver mutations and 7 novel mutations that cause constitutive TpoR activation, and a much larger number of second-site mutations that enhance S505N-driven activation. We found examples of both of these categories in published and previously unpublished MPL exon 10 sequencing data from MPN patients, demonstrating that some, if not all, of the new mutations reported here represent likely drivers or modifiers of myeloproliferative disease., (© 2020 by The American Society of Hematology.)
- Published
- 2020
- Full Text
- View/download PDF
23. Loss of growth hormone-mediated signal transducer and activator of transcription 5 (STAT5) signaling in mice results in insulin sensitivity with obesity.
- Author
-
Chhabra Y, Nelson CN, Plescher M, Barclay JL, Smith AG, Andrikopoulos S, Mangiafico S, Waxman DJ, Brooks AJ, and Waters MJ
- Subjects
- Animals, Glucose genetics, Glucose metabolism, Glycogen genetics, Glycogen metabolism, Insulin Receptor Substrate Proteins genetics, Insulin Receptor Substrate Proteins metabolism, Intracellular Signaling Peptides and Proteins genetics, Intracellular Signaling Peptides and Proteins metabolism, Male, Mice, Mice, Knockout, Phosphoenolpyruvate Carboxykinase (GTP) genetics, Phosphoenolpyruvate Carboxykinase (GTP) metabolism, Receptor, Insulin genetics, Receptor, Insulin metabolism, STAT5 Transcription Factor metabolism, Carrier Proteins genetics, Carrier Proteins metabolism, Fatty Liver genetics, Fatty Liver metabolism, Fatty Liver pathology, Insulin Resistance genetics, Liver metabolism, Liver pathology, Obesity genetics, Obesity metabolism, Obesity pathology, STAT5 Transcription Factor deficiency, Signal Transduction genetics
- Abstract
Growth hormone (GH) has an important function as an insulin antagonist with elevated insulin sensitivity evident in humans and mice lacking a functional GH receptor (GHR). We sought the molecular basis for this sensitivity by utilizing a panel of mice possessing specific deletions of GHR signaling pathways. Metabolic clamps and glucose homeostasis tests were undertaken in these obese adult C57BL/6 male mice, which indicated impaired hepatic gluconeogenesis. Insulin sensitivity and glucose disappearance rate were enhanced in muscle and adipose of mice lacking the ability to activate the signal transducer and activator of transcription (STAT)5 via the GHR ( Ghr -391
-/- ) as for GHR-null ( GHR-/- ) mice. These changes were associated with a striking inhibition of hepatic glucose output associated with altered glycogen metabolism and elevated hepatic glycogen content during unfed state. The enhanced hepatic insulin sensitivity was associated with increased insulin receptor β and insulin receptor substrate 1 activation along with activated downstream protein kinase B signaling cascades. Although phosphoenolpyruvate carboxykinase ( Pck )- 1 expression was unchanged, its inhibitory acetylation was elevated because of decreased sirtuin-2 expression, thereby promoting loss of PCK1. Loss of STAT5 signaling to defined chromatin immunoprecipitation targets would further increase lipogenesis, supporting hepatosteatosis while lowering glucose output. Finally, up-regulation of IL-15 expression in muscle, with increased secretion of adiponectin and fibroblast growth factor 1 from adipose tissue, is expected to promote insulin sensitivity.-Chhabra, Y., Nelson, C. N., Plescher, M., Barclay, J. L., Smith, A. G., Andrikopoulos, S., Mangiafico, S., Waxman, D. J., Brooks, A. J., Waters, M. J. Loss of growth hormone-mediated signal transducer and activator of transcription 5 (STAT5) signaling in mice results in insulin sensitivity with obesity.- Published
- 2019
- Full Text
- View/download PDF
24. BRN2, a POUerful driver of melanoma phenotype switching and metastasis.
- Author
-
Fane ME, Chhabra Y, Smith AG, and Sturm RA
- Subjects
- Animals, Humans, Models, Biological, Neoplasm Invasiveness, Neoplasm Metastasis, Phenotype, Melanoma pathology, POU Domain Factors metabolism
- Abstract
The POU domain family of transcription factors play a central role in embryogenesis and are highly expressed in neural crest cells and the developing brain. BRN2 is a class III POU domain protein that is a key mediator of neuroendocrine and melanocytic development and differentiation. While BRN2 is a central regulator in numerous developmental programs, it has also emerged as a major player in the biology of tumourigenesis. In melanoma, BRN2 has been implicated as one of the master regulators of the acquisition of invasive behaviour within the phenotype switching model of progression. As a mediator of melanoma cell phenotype switching, it coordinates the transition to a dedifferentiated, slow cycling and highly motile cell type. Its inverse expression relationship with MITF is believed to mediate tumour progression and metastasis within this model. Recent evidence has now outlined a potential epigenetic switching mechanism in melanoma cells driven by BRN2 expression that induces melanoma cell invasion. We summarize the role of BRN2 in tumour cell dissemination and metastasis in melanoma, while also examining it as a potential metastatic regulator in other tumour models., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)
- Published
- 2019
- Full Text
- View/download PDF
25. Growth hormone activated STAT5 is required for induction of beige fat in vivo.
- Author
-
Nelson CN, List EO, Ieremia M, Constantin L, Chhabra Y, Kopchick JJ, and Waters MJ
- Subjects
- Adipose Tissue, Beige metabolism, Adipose Tissue, White metabolism, Animals, Cattle, Fibroblast Growth Factors metabolism, Growth Hormone genetics, Mice, Mice, Knockout, Receptors, Adrenergic metabolism, STAT5 Transcription Factor genetics, Signal Transduction, Adipose Tissue, Beige cytology, Adipose Tissue, White cytology, Carrier Proteins physiology, Growth Hormone metabolism, STAT5 Transcription Factor metabolism
- Abstract
Objective: The anti-obesity actions of growth hormone (GH) led us to investigate if GH signaling is able to regulate beige/brite fat development of white adipose tissue (WAT)., Methods: We studied WAT in GHR-391 mice engineered to be unable to activate STAT5 in response to GH, in mice with adipose specific deletion of GHR, in GHR-/- mice and in bGH transgenic mice. QPCR, immunoblots and immunohistochemistry were used to characterize WAT. The in vivo effects of β-3 adrenergic activation with CL-316,243 and that of FGF21 infusion were also studied., Results: GHR-391 mice had lower surface temperature than WT, with deficiency in β-oxidation and beiging transcripts including Ucp1. Oxidative phosphorylation complex subunit proteins were decreased dramatically in GHR-391 inguinal white adipose tissue (iWAT), but increased in bGH iWAT, as were proteins for beige/brown markers. In accord with its lack of β-3 adrenergic receptors, iWAT of GHR-391 mice did not beige in response to administration of the β-3 specific agonist CL-316,243 in contrast to WT mice. GHR-391 mice are deficient in FGF21, but unlike WT, infusion of the purified protein was without effect on extent of beiging. Finally, fat-specific deletion of the GHR replicated the loss of beiging associated transcripts., Conclusion: In addition to promoting lipolysis, our study suggests that GH is able to promote formation of beige adipose tissue through activation of STAT5 and induction of Adrb3. This sensitizes WAT to adrenergic input, and may contribute to the anti-obesity actions of GH., (Copyright © 2018 Elsevier Ltd. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
26. Dengue fever in renal allograft recipients: Clinical course and outcome.
- Author
-
Subbiah A, Bagchi S, Bhowmik D, Mahajan S, Yadav RK, Chhabra Y, and Agarwal S
- Subjects
- Adult, Dengue diagnosis, Dengue etiology, Dengue virology, Disease Outbreaks, Humans, Immunosuppression Therapy, Kidney pathology, Kidney virology, Leukopenia, Male, Retrospective Studies, Severe Dengue etiology, Severe Dengue virology, Young Adult, Dengue epidemiology, Kidney Transplantation adverse effects, Severe Dengue epidemiology, Transplant Recipients statistics & numerical data, Transplantation, Homologous adverse effects
- Abstract
Background: There are annual outbreaks of dengue infection in tropical and subtropical countries. This retrospective study aimed to assess the clinical manifestation of dengue and outcome in renal transplant recipients., Methods: Renal transplant recipients diagnosed with dengue in the nephrology department during the outbreak from August 2015 to December 2015 were included in the study., Results: Twenty patients developed dengue presenting during the outbreak. Mean age was 31.9 ± 8.8 years and all were males. Two patients had severe dengue (dengue hemorrhagic fever, dengue shock syndrome). Clinical presentation included febrile illness (95%), myalgia (65%), headache (30%), retro-orbital pain (10%), and mucocutaneous bleeding manifestations (10%). Three (15%) had third space fluid accumulation and 2 (10%) had hypotension. Ninety percent patients had thrombocytopenia, with 4 requiring platelet transfusion. Leucopenia (WBC < 4000/mm
3 ) developed in 50% patients. About 60% had transient transaminitis. One patient with severed dengue expired and 1 recovered with IV immunoglobulin therapy. About 40% patients had rise in serum creatinine, with complete recovery in all patients., Conclusion: Clinical manifestations of dengue infection in renal transplant recipients were similar to that in general population. However, leucopenia necessitating temporary withdrawal of immunosuppression was common. Renal dysfunction was frequent but completely reversible., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)- Published
- 2018
- Full Text
- View/download PDF
27. Genetic variation in IRF4 expression modulates growth characteristics, tyrosinase expression and interferon-gamma response in melanocytic cells.
- Author
-
Chhabra Y, Yong HXL, Fane ME, Soogrim A, Lim W, Mahiuddin DN, Kim RSQ, Ashcroft M, Beatson SA, Ainger SA, Smit DJ, Jagirdar K, Walker GJ, Sturm RA, and Smith AG
- Subjects
- Antiviral Agents pharmacology, Cell Proliferation, Cell Survival, Cells, Cultured, Gene Expression Regulation, Genetic Predisposition to Disease, Genotype, Humans, Melanocytes drug effects, Melanocytes metabolism, Melanoma drug therapy, Melanoma genetics, Melanoma metabolism, Ultraviolet Rays, Interferon Regulatory Factors genetics, Interferon Regulatory Factors metabolism, Interferon-gamma pharmacology, Melanocytes pathology, Melanoma pathology, Monophenol Monooxygenase metabolism, Polymorphism, Single Nucleotide
- Abstract
A SNP within intron4 of the interferon regulatory factor4 (IRF4) gene, rs12203592*C/T, has been independently associated with pigmentation and age-specific effects on naevus count in European-derived populations. We have characterized the cis-regulatory activity of this intronic region and using human foreskin-derived melanoblast strains, we have explored the correlation between IRF4 rs12203592 homozygous C/C and T/T genotypes with TYR enzyme activity, supporting its association with pigmentation traits. Further, higher IRF4 protein levels directed by the rs12203592*C allele were associated with increased basal proliferation but decreased cell viability following UVR, an etiological factor in melanoma development. Since UVR, and accompanying IFNγ-mediated inflammatory response, is associated with melanomagenesis, we evaluated its effects in the context of IRF4 status. Manipulation of IRF4 levels followed by IFNγ treatment revealed a subset of chemokines and immuno-evasive molecules that are sensitive to IRF4 expression level and genotype including CTLA4 and PD-L1., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)
- Published
- 2018
- Full Text
- View/download PDF
28. NR4A2 Promotes DNA Double-strand Break Repair Upon Exposure to UVR.
- Author
-
Yin K, Chhabra Y, Tropée R, Lim YC, Fane M, Dray E, Sturm RA, and Smith AG
- Subjects
- Cell Death radiation effects, Cell Line, Tumor, DNA, Neoplasm genetics, Humans, Melanocytes metabolism, Melanocytes radiation effects, Melanoma metabolism, Melanoma pathology, Melanoma radiotherapy, Nuclear Receptor Subfamily 4, Group A, Member 2 biosynthesis, Nuclear Receptor Subfamily 4, Group A, Member 2 metabolism, RNA, Messenger genetics, RNA, Messenger metabolism, Signal Transduction, Transfection, Ultraviolet Rays, DNA Breaks, Double-Stranded, DNA Repair, DNA, Neoplasm radiation effects, Melanoma genetics, Nuclear Receptor Subfamily 4, Group A, Member 2 genetics
- Abstract
Exposure of melanocytes to ultraviolet radiation (UVR) induces the formation of UV lesions that can produce deleterious effects in genomic DNA. Encounters of replication forks with unrepaired UV lesions can lead to several complex phenomena, such as the formation of DNA double-strand breaks (DSBs). The NR4A family of nuclear receptors are transcription factors that have been associated with mediating DNA repair functions downstream of the MC1R signaling pathway in melanocytes. In particular, emerging evidence shows that upon DNA damage, the NR4A2 receptor can translocate to sites of UV lesion by mechanisms requiring post-translational modifications within the N-terminal domain and at a serine residue in the DNA-binding domain at position 337. Following this, NR4A2 aids in DNA repair by facilitating chromatin relaxation, allowing accessibility for DNA repair machinery. Using A2058 and HT144 melanoma cells engineered to stably express wild-type or mutant forms of the NR4A2 proteins, we reveal that the expression of functional NR4A2 is associated with elevated cytoprotection against UVR. Conversely, knockdown of NR4A2 expression by siRNA results in a significant loss of cell viability after UV insult. By analyzing the kinetics of the ensuing 53BP1 and RAD51 foci following UV irradiation, we also reveal that the expression of mutant NR4A2 isoforms, lacking the ability to translocate, transactivate, or undergo phosphorylation, display compromised repair capacity. Implications: These data expand the understanding of the mechanism by which the NR4A2 nuclear receptor can facilitate DNA DSB repair. Mol Cancer Res; 15(9); 1184-96. ©2017 AACR ., (©2017 American Association for Cancer Research.)
- Published
- 2017
- Full Text
- View/download PDF
29. NFIB Mediates BRN2 Driven Melanoma Cell Migration and Invasion Through Regulation of EZH2 and MITF.
- Author
-
Fane ME, Chhabra Y, Hollingsworth DEJ, Simmons JL, Spoerri L, Oh TG, Chauhan J, Chin T, Harris L, Harvey TJ, Muscat GEO, Goding CR, Sturm RA, Haass NK, Boyle GM, Piper M, and Smith AG
- Subjects
- Animals, Blotting, Western, Cell Line, Tumor, Enhancer of Zeste Homolog 2 Protein metabolism, Gene Expression Regulation, Neoplastic, Homeodomain Proteins metabolism, Humans, Male, Melanoma metabolism, Melanoma pathology, Mice, Inbred BALB C, Mice, Knockout, Microphthalmia-Associated Transcription Factor metabolism, Microscopy, Fluorescence, NFI Transcription Factors metabolism, Neoplasm Invasiveness, POU Domain Factors metabolism, Protein Binding, Reverse Transcriptase Polymerase Chain Reaction, Transplantation, Heterologous, Cell Movement genetics, Enhancer of Zeste Homolog 2 Protein genetics, Homeodomain Proteins genetics, Melanoma genetics, Microphthalmia-Associated Transcription Factor genetics, NFI Transcription Factors genetics, POU Domain Factors genetics
- Abstract
While invasion and metastasis of tumour cells are the principle factor responsible for cancer related deaths, the mechanisms governing the process remain poorly defined. Moreover, phenotypic divergence of sub-populations of tumour cells is known to underpin alternative behaviors linked to tumour progression such as proliferation, survival and invasion. In the context of melanoma, heterogeneity between two transcription factors, BRN2 and MITF, has been associated with phenotypic switching between predominantly invasive and proliferative behaviors respectively. Epigenetic changes, in response to external cues, have been proposed to underpin this process, however the mechanism by which the phenotypic switch occurs is unclear. Here we report the identification of the NFIB transcription factor as a novel downstream effector of BRN2 function in melanoma cells linked to the migratory and invasive characteristics of these cells. Furthermore, the function of NFIB appears to drive an invasive phenotype through an epigenetic mechanism achieved via the upregulation of the polycomb group protein EZH2. A notable target of NFIB mediated up-regulation of EZH2 is decreased MITF expression, which further promotes a less proliferative, more invasive phenotype. Together our data reveal that NFIB has the ability to promote dynamic changes in the chromatin state of melanoma cells to facilitate migration, invasion and metastasis., (Copyright © 2017. Published by Elsevier B.V.)
- Published
- 2017
- Full Text
- View/download PDF
30. CRIM1 is necessary for coronary vascular endothelial cell development and homeostasis.
- Author
-
Iyer S, Chhabra Y, Harvey TJ, Wang R, Chiu HS, Smith AG, Thomas WG, Pennisi DJ, and Piper M
- Subjects
- Animals, Bone Morphogenetic Proteins metabolism, Cell Survival genetics, Human Umbilical Vein Endothelial Cells, Humans, Mice, Mice, Knockout, Mutation, Signal Transduction, Bone Morphogenetic Protein Receptors genetics, Bone Morphogenetic Protein Receptors metabolism, Coronary Vessels cytology, Endothelial Cells metabolism, Homeostasis
- Abstract
Endothelial cells form a critical component of the coronary vasculature, yet the factors regulating their development remain poorly defined. Here we reveal a novel role for the transmembrane protein CRIM1 in mediating cardiac endothelial cell development. In the absence of Crim1 in vivo, the coronary vasculature is malformed, the number of endothelial cells reduced, and the canonical BMP pathway dysregulated. Moreover, we reveal that CRIM1 can bind IGFs, and regulate IGF signalling within endothelial cells. Finally, loss of CRIM1 from human cardiac endothelial cells results in misregulation of endothelial genes, predicted by pathway analysis to be involved in an increased inflammatory response and cytolysis, reminiscent of endothelial cell dysfunction in cardiovascular disease pathogenesis. Collectively, these findings implicate CRIM1 in endothelial cell development and homeostasis in the coronary vasculature.
- Published
- 2017
- Full Text
- View/download PDF
31. A new mechanism for growth hormone receptor activation of JAK2, and implications for related cytokine receptors.
- Author
-
Waters MJ, Brooks AJ, and Chhabra Y
- Abstract
The growth hormone receptor was the first cytokine receptor to be cloned and crystallized, and provides a valuable exemplar for activation of its cognate kinase, JAK2. We review progress in understanding its activation mechanism, in particular the molecular movements made by this constitutively dimerized receptor in response to ligand binding, and how these lead to a separation of JAK-binding Box1 motifs. Such a separation leads to removal of the pseudokinase inhibitory domain from the kinase domain of a partner JAK2 bound to the receptor, and vice versa, leading to apposition of the kinase domains and transactivation. This may be a general mechanism for class I cytokine receptor action.
- Published
- 2014
- Full Text
- View/download PDF
32. Mechanism of activation of protein kinase JAK2 by the growth hormone receptor.
- Author
-
Brooks AJ, Dai W, O'Mara ML, Abankwa D, Chhabra Y, Pelekanos RA, Gardon O, Tunny KA, Blucher KM, Morton CJ, Parker MW, Sierecki E, Gambin Y, Gomez GA, Alexandrov K, Wilson IA, Doxastakis M, Mark AE, and Waters MJ
- Subjects
- Amino Acid Motifs, Amino Acid Sequence, Cysteine chemistry, Enzyme Activation, HEK293 Cells, Humans, Janus Kinase 2 antagonists & inhibitors, Janus Kinase 2 chemistry, Models, Molecular, Molecular Sequence Data, Mutation, Protein Multimerization, Protein Structure, Secondary, Protein Structure, Tertiary, Receptors, Somatotropin chemistry, Receptors, Somatotropin genetics, Janus Kinase 2 metabolism, Receptors, Somatotropin metabolism
- Abstract
Signaling from JAK (Janus kinase) protein kinases to STAT (signal transducers and activators of transcription) transcription factors is key to many aspects of biology and medicine, yet the mechanism by which cytokine receptors initiate signaling is enigmatic. We present a complete mechanistic model for activation of receptor-bound JAK2, based on an archetypal cytokine receptor, the growth hormone receptor. For this, we used fluorescence resonance energy transfer to monitor positioning of the JAK2 binding motif in the receptor dimer, substitution of the receptor extracellular domains with Jun zippers to control the position of its transmembrane (TM) helices, atomistic modeling of TM helix movements, and docking of the crystal structures of the JAK2 kinase and its inhibitory pseudokinase domain with an opposing kinase-pseudokinase domain pair. Activation of the receptor dimer induced a separation of its JAK2 binding motifs, driven by a ligand-induced transition from a parallel TM helix pair to a left-handed crossover arrangement. This separation leads to removal of the pseudokinase domain from the kinase domain of the partner JAK2 and pairing of the two kinase domains, facilitating trans-activation. This model may well generalize to other class I cytokine receptors., (Copyright © 2014, American Association for the Advancement of Science.)
- Published
- 2014
- Full Text
- View/download PDF
33. Differential response to sustained stimulation by hCG & LH on goat ovarian granulosa cells.
- Author
-
Gupta C, Chapekar T, Chhabra Y, Singh P, Sinha S, and Luthra K
- Subjects
- Animals, Cell Culture Techniques, Cell Proliferation drug effects, Cyclic AMP metabolism, Cyclic AMP-Dependent Protein Kinases metabolism, Female, Goats, Granulosa Cells enzymology, Granulosa Cells metabolism, Mitogen-Activated Protein Kinase 3 metabolism, Primary Cell Culture, Protein Kinase C metabolism, Signal Transduction drug effects, Chorionic Gonadotropin pharmacology, Granulosa Cells drug effects, Luteinizing Hormone pharmacology
- Abstract
Background & Objectives: Chapekar established a model of ovarian tumourigenesis in mice by splenic transplantation of ovaries, resulting in sustained luteinizing hormone (LH) levels because of absence of feedback inhibition. There is increasing evidence of the differential response to LH or hCG under various experimental conditions. The effect of sustained hormonal stimulation in long term cultures is sparsely investigated. The study is aimed to determine the role of hCG and LH stress on caprine ovarian granulosa cells and their downstream signaling in short and long term cultures., Methods: To study the response of hCG and LH stress and downstream signaling, short term cultures were set up by exposing goat ovarian granulosa cells in primary cultures to hCG and LH stress (levels beyond their physiological doses) for 5 days (P0). Cells were sub-cultured at sixth day and subjected to prolonged LH/ hCG stress for two weeks in passage 1(P1) (long term cultures). Downstream cell signaling molecules were assessed. Intracellular cAMP was estimated by ELISA. For PKA and PKC, activity assays were performed. pERK protein expressions in short term cultures were assessed by Western blot and flowcytometry; in long term cultures, pERK expression was analyzed by flowcytometry., Results: Differential effects on cell proliferation were observed in long term cultures, where the untreated and hCG exposed cells showed markedly reduced cell proliferation after second week of exposure while LH treated cells continued to proliferate. Different levels of cAMP, PKA, PKC and phosphorylated ERK1/2 were observed on short term and long term LH stimulation. On sustained hormonal stimulation, cAMP levels were significantly (P<0.05) higher in hCG treated cultures as compared to controls and LH treated cultures. LH led to maximal elevation of ERK in long term cultures., Interpretation & Conclusions: As pERK1/2 promotes cellular proliferation, activation of ERK1/2 in LH treated cultures may be responsible for sustained growth. Prolonged LH treatment promoted growth and proliferation in caprine ovarian granulosa cells whereas prolonged exposure to hCG led to elevated levels of cAMP and decreased the rate of proliferation. Defining the signals and second messengers that act as survival or apoptotic mediators may help in elucidation of the mechanisms controlling proliferation or programmed cell death in granulosa cells.
- Published
- 2012
34. Role of the growth hormone-IGF-1 axis in cancer.
- Author
-
Chhabra Y, Waters MJ, and Brooks AJ
- Abstract
A substantial body of evidence supports a role for the growth hormone (GH)-IGF-1 axis in cancer incidence and progression. This includes epidemiological evidence relating elevated plasma IGF-1 to cancer incidence as well as a lack of cancers in GH/IGF-1 deficiency. Rodent models lacking GH or its receptor are strikingly resistant to the induction of a wide range of cancers, and treatment with the GH antagonist pegvisomant slows tumor progression. While GH receptor expression is elevated in many cancers, autocrine GH is present in several types, and overexpression of autocrine GH can induce cell transformation. While the mechanism of autocrine action is not clear, it does involve both STAT5 and STAT3 activation, and probably nuclear translocation of the GH receptor. Development of a more potent GH receptor antagonist or secretion inhibitor is warranted for cancer therapy.
- Published
- 2011
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.