The calcium-sensing receptor (CaR) is a G protein-coupled, 7 transmembrane-spanning, cell surface receptor (GPCR) that binds calcium ions and allows cells to respond to changes in extracellular calcium concentrations. It plays a central role in systemic mineral metabolism by regulating parathyroid hormone secretion and renal calcium handling. In addition, it is expressed by many other cell types, including mammary epithelial cells (MECs). Expression of the CaR is low in rapidly proliferating MECs during pregnancy, but is greatly upregulated at the start of lactation. This allows the mammary gland to become a calcium-sensing organ that actively participates in the regulation of systemic calcium metabolism during lactation. In normal MECs, activation of the CaR inhibits PTHrP secretion but promotes calcium transport into milk. Therefore, if calcium delivery to the mammary gland falls, MECs transport less calcium and secrete more PTHrP. The increase in circulating PTHrP, in turn, activates bone resorption and liberates calcium from the skeleton for milk production. Thus, during lactation, a calcium-CaR-PTHrP mammary axis mimics the calcium-CaR-PTH parathyroid axis normally responsible for systemic calcium homeostasis. We have observed that malignant transformation alters the relationship between the CaR and PTHrP, such that breast cancer cells stimulate PTHrP production in response to calcium, rather than inhibiting PTHrP production, as they should. Similarly, activation of the CaR inhibits proliferation in normal cells, but stimulates proliferation in breast cancer cells. We hypothesize that these alterations in how the CaR regulates proliferation and PTHrP secretion in malignant versus normal breast cells contribute to the progression of breast tumors and the development of bone metastases. In order to investigate these possibilities, we outline three specific aims.
Aim 1 will examine whether PKC phosphorylation of the CaR alters G-protein usage and cAMP and PTHrP production in response to calcium in malignant versus normal breast cells.
Aim 2 will examine if disruption of the CaR gene will affect the development and progression of mammary tumors in mouse models. It will also determine if tumor CaR expression predicts outcome in a large cohort of patients with breast cancer.
Aim 3 will examine if stimulation of PTHrP production by the CaR contributes to the development of osteolytic bone metastases in vivo.

Public Health Relevance

Breast cancer is the most common neoplasm afflicting women in the US and other developed countries. This disease causes much suffering, is responsible for a large number of premature deaths and costs the US economy a great amount each year. The source of most morbidity and mortality from breast cancer is not the primary tumor itself, but rather metastases. Breast cancer is particularly prone to spread to the skeleton. It is estimated that 80% - 90% of patients with metastatic breast cancer will develop bone lesions. Bone metastases cause intractable pain, pathological fracture, hypercalcemia and spinal cord compression. They also herald mortality, as skeletal lesions cannot be cured at present. Our preliminary data suggest that the calcium sensing receptor (CaR) may contribute to the development of breast cancer and/or its bone metastases by stimulating parathyroid hormone-related protein (PTHrP) production. In contrast, during lactation, the normal breast participates in the regulation of bone metabolism by inhibiting PTHrP production. Our goal in these studies is to determine how malignant transformation alters the regulation of PTHrP production by the CaR and to determine if the CaR contributes to the development of breast cancer and/or its spread to the skeleton in animal models. It is possible that drugs developed to manipulate CaR signaling for bone and parathyroid diseases may also be effective for breast cancer.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Skeletal Biology Development and Disease Study Section (SBDD)
Program Officer
Ogunbiyi, Peter
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Yale University
Internal Medicine/Medicine
Schools of Medicine
New Haven
United States
Zip Code
Jeong, Jaekwang; VanHouten, Joshua N; Kim, Wonnam et al. (2017) The scaffolding protein NHERF1 regulates the stability and activity of the tyrosine kinase HER2. J Biol Chem 292:6555-6568
Kim, Wonnam; Wysolmerski, John J (2016) Calcium-Sensing Receptor in Breast Physiology and Cancer. Front Physiol 7:440
Jeong, Jaekwang; VanHouten, Joshua N; Dann, Pamela et al. (2016) PMCA2 regulates HER2 protein kinase localization and signaling and promotes HER2-mediated breast cancer. Proc Natl Acad Sci U S A 113:E282-90
Kim, Wonnam; Takyar, Farzin M; Swan, Karena et al. (2016) Calcium-Sensing Receptor Promotes Breast Cancer by Stimulating Intracrine Actions of Parathyroid Hormone-Related Protein. Cancer Res 76:5348-60
Ardeshirpour, Laleh; Dumitru, Cristina; Dann, Pamela et al. (2015) OPG Treatment Prevents Bone Loss During Lactation But Does Not Affect Milk Production or Maternal Calcium Metabolism. Endocrinology 156:2762-73
Boras-Granic, Kata; Dann, Pamela; Wysolmerski, John J (2014) Embryonic cells contribute directly to the quiescent stem cell population in the adult mouse mammary gland. Breast Cancer Res 16:487
Boras-Granic, Kata; Dann, Pamela; Vanhouten, Joshua et al. (2014) Deletion of the nuclear localization sequences and C-terminus of PTHrP impairs embryonic mammary development but also inhibits PTHrP production. PLoS One 9:e90418
Wysolmerski, John J (2013) Osteocytes remove and replace perilacunar mineral during reproductive cycles. Bone 54:230-6
Mamillapalli, Ramanaiah; VanHouten, Joshua; Dann, Pamela et al. (2013) Mammary-specific ablation of the calcium-sensing receptor during lactation alters maternal calcium metabolism, milk calcium transport, and neonatal calcium accrual. Endocrinology 154:3031-42
Vanhouten, Joshua N; Wysolmerski, John J (2013) The calcium-sensing receptor in the breast. Best Pract Res Clin Endocrinol Metab 27:403-14

Showing the most recent 10 out of 24 publications