Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent Manner
Parathyroid hormone-related protein (PTHrP) expression in breast cancer is enriched in bone metastases compared to primary tumors. Human MCF7 breast cancer cells “home” to the bones of immune deficient mice following intracardiac inoculation, but do not grow well and stain negatively for Ki67, thus...
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doaj-aa897180e9874f8c95981df67849d3bc2020-11-24T22:28:19ZengFrontiers Media S.A.Frontiers in Endocrinology1664-23922018-05-01910.3389/fendo.2018.00241355938Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent MannerRachelle W. Johnson0Yao Sun1Yao Sun2Patricia W. M. Ho3Audrey S. M. Chan4Jasmine A. Johnson5Nathan J. Pavlos6Natalie A. Sims7Natalie A. Sims8T. John Martin9T. John Martin10Department of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, United StatesBone Biology and Disease Unit, St. Vincent’s Institute of Medical Research, Fitzroy, VIC, AustraliaDepartment of Medicine at St. Vincent’s Hospital, University of Melbourne, Melbourne, VIC, AustraliaBone Biology and Disease Unit, St. Vincent’s Institute of Medical Research, Fitzroy, VIC, AustraliaCellular Orthopaedic Laboratory, School of Biomedical Sciences, The University of Western Australia, Crawley, WA, AustraliaDepartment of Medicine, Division of Clinical Pharmacology, Vanderbilt Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, United StatesCellular Orthopaedic Laboratory, School of Biomedical Sciences, The University of Western Australia, Crawley, WA, AustraliaBone Biology and Disease Unit, St. Vincent’s Institute of Medical Research, Fitzroy, VIC, AustraliaDepartment of Medicine at St. Vincent’s Hospital, University of Melbourne, Melbourne, VIC, AustraliaBone Biology and Disease Unit, St. Vincent’s Institute of Medical Research, Fitzroy, VIC, AustraliaDepartment of Medicine at St. Vincent’s Hospital, University of Melbourne, Melbourne, VIC, AustraliaParathyroid hormone-related protein (PTHrP) expression in breast cancer is enriched in bone metastases compared to primary tumors. Human MCF7 breast cancer cells “home” to the bones of immune deficient mice following intracardiac inoculation, but do not grow well and stain negatively for Ki67, thus serving as a model of breast cancer dormancy in vivo. We have previously shown that PTHrP overexpression in MCF7 cells overcomes this dormant phenotype, causing them to grow as osteolytic deposits, and that PTHrP-overexpressing MCF7 cells showed significantly lower expression of genes associated with dormancy compared to vector controls. Since early work showed a lack of cyclic AMP (cAMP) response to parathyroid hormone (PTH) in MCF7 cells, and cAMP is activated by PTH/PTHrP receptor (PTHR1) signaling, we hypothesized that the effects of PTHrP on dormancy in MCF7 cells occur through non-canonical (i.e., PTHR1/cAMP-independent) signaling. The data presented here demonstrate the lack of cAMP response in MCF7 cells to full length PTHrP(1–141) and PTH(1–34) in a wide range of doses, while maintaining a response to three known activators of adenylyl cyclase: calcitonin, prostaglandin E2 (PGE2), and forskolin. PTHR1 mRNA was detectable in MCF7 cells and was found in eight other human breast and murine mammary carcinoma cell lines. Although PTHrP overexpression in MCF7 cells changed expression levels of many genes, RNAseq analysis revealed that PTHR1 was unaltered, and only 2/32 previous PTHR1/cAMP responsive genes were significantly upregulated. Instead, PTHrP overexpression in MCF7 cells resulted in significant enrichment of the calcium signaling pathway. We conclude that PTHR1 in MCF7 breast cancer cells is not functionally linked to activation of the cAMP pathway. Gene expression responses to PTHrP overexpression must, therefore, result from autocrine or intracrine actions of PTHrP independent of PTHR1, through signals emanating from other domains within the PTHrP molecule.http://journal.frontiersin.org/article/10.3389/fendo.2018.00241/fullparathyroid hormone-related proteincyclic AMPMCF7breast cancercalcium signaling |
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DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Rachelle W. Johnson Yao Sun Yao Sun Patricia W. M. Ho Audrey S. M. Chan Jasmine A. Johnson Nathan J. Pavlos Natalie A. Sims Natalie A. Sims T. John Martin T. John Martin |
spellingShingle |
Rachelle W. Johnson Yao Sun Yao Sun Patricia W. M. Ho Audrey S. M. Chan Jasmine A. Johnson Nathan J. Pavlos Natalie A. Sims Natalie A. Sims T. John Martin T. John Martin Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent Manner Frontiers in Endocrinology parathyroid hormone-related protein cyclic AMP MCF7 breast cancer calcium signaling |
author_facet |
Rachelle W. Johnson Yao Sun Yao Sun Patricia W. M. Ho Audrey S. M. Chan Jasmine A. Johnson Nathan J. Pavlos Natalie A. Sims Natalie A. Sims T. John Martin T. John Martin |
author_sort |
Rachelle W. Johnson |
title |
Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent Manner |
title_short |
Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent Manner |
title_full |
Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent Manner |
title_fullStr |
Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent Manner |
title_full_unstemmed |
Parathyroid Hormone-Related Protein Negatively Regulates Tumor Cell Dormancy Genes in a PTHR1/Cyclic AMP-Independent Manner |
title_sort |
parathyroid hormone-related protein negatively regulates tumor cell dormancy genes in a pthr1/cyclic amp-independent manner |
publisher |
Frontiers Media S.A. |
series |
Frontiers in Endocrinology |
issn |
1664-2392 |
publishDate |
2018-05-01 |
description |
Parathyroid hormone-related protein (PTHrP) expression in breast cancer is enriched in bone metastases compared to primary tumors. Human MCF7 breast cancer cells “home” to the bones of immune deficient mice following intracardiac inoculation, but do not grow well and stain negatively for Ki67, thus serving as a model of breast cancer dormancy in vivo. We have previously shown that PTHrP overexpression in MCF7 cells overcomes this dormant phenotype, causing them to grow as osteolytic deposits, and that PTHrP-overexpressing MCF7 cells showed significantly lower expression of genes associated with dormancy compared to vector controls. Since early work showed a lack of cyclic AMP (cAMP) response to parathyroid hormone (PTH) in MCF7 cells, and cAMP is activated by PTH/PTHrP receptor (PTHR1) signaling, we hypothesized that the effects of PTHrP on dormancy in MCF7 cells occur through non-canonical (i.e., PTHR1/cAMP-independent) signaling. The data presented here demonstrate the lack of cAMP response in MCF7 cells to full length PTHrP(1–141) and PTH(1–34) in a wide range of doses, while maintaining a response to three known activators of adenylyl cyclase: calcitonin, prostaglandin E2 (PGE2), and forskolin. PTHR1 mRNA was detectable in MCF7 cells and was found in eight other human breast and murine mammary carcinoma cell lines. Although PTHrP overexpression in MCF7 cells changed expression levels of many genes, RNAseq analysis revealed that PTHR1 was unaltered, and only 2/32 previous PTHR1/cAMP responsive genes were significantly upregulated. Instead, PTHrP overexpression in MCF7 cells resulted in significant enrichment of the calcium signaling pathway. We conclude that PTHR1 in MCF7 breast cancer cells is not functionally linked to activation of the cAMP pathway. Gene expression responses to PTHrP overexpression must, therefore, result from autocrine or intracrine actions of PTHrP independent of PTHR1, through signals emanating from other domains within the PTHrP molecule. |
topic |
parathyroid hormone-related protein cyclic AMP MCF7 breast cancer calcium signaling |
url |
http://journal.frontiersin.org/article/10.3389/fendo.2018.00241/full |
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