Calcium-sensitive receptor expression differs between primary and secondary hyperparathyroidism

Background: Calcium-sensitive receptor (CASR) plays an important role in the pathogenesis and progression of secondary hyperparathyroidism (SHPT). The purpose of this study is to examine the protein and gene expression characteristics of CASR in SHPT. Methods: Immunohistochemistry and real-time PCR were used to detect and compare the expression of CASR protein and genes in SHPT and primary hyperparathyroidism (PHPT) tissues. Results: CASR protein was down-regulated in SHPT and PHPT compared with normal parathyroid tissues (2.42±0.5 vs. 3.2±0.62, P<0.05; 1.8±0.83 vs. 3.2±0.62, P<0.05). Further, SHPT tissue showed higher expression of both CASR protein (2.42±0.5 vs. 1.8±0.83, P<0.05) and CASR gene (0.29±0.23 vs. 0.01±0.12, P<0.05) than PHPT tissue, respectively. Conclusion: The expression of CASR protein and gene in SHPT is higher than that in PHPT. This feature provides a theoretical basis and further ideas for studying the mechanism of CASR down-regulation.