PTH1R-CaSR Cross Talk: New Treatment Options for Breast Cancer Osteolytic Bone Metastases
Table 2
Comparison of PTH1R and CaSR.
PTH1R
CaSR
GPCR
Class B family
Class C family
Receptor size
Human PTH1R has 593 amino acids
Human CaSR has 1078 amino acids
Expression
Mostly in osteoblast and kidney, also in cartilage, normal breast epithelial cells, and some breast cancer cell lines
Parathyroid glands, kidney, bone, normal breast epithelial cells, and BrCa cells
G protein
Gαs, Gαq, Gαi, and G12/13
Gαi, Gαq, Gαs, and G12/13
Agonist
PTH and PTHrP
Type I: inorganic or organic polycations (Ca2+ and Gd3+), polyamines (spermine and spermidine), and aminoglycoside antibiotics (neomycin) Type II: positive allosteric modulators (calcimimetics)—cinacalcet, NPS R-467, NPS R-568, and AMG 416