Calcium ions promote primary renal epithelial cell differentiation into cells with bone-associated phenotypes via transforming growth factor-β1-induced epithelial-mesenchymal transition in idiopathic hypercalciuria patients.
The present study aimed to identify the characteristics and cross‑talk between transforming growth factor β1 (TGF‑β1) and calcium ions in nephrolithiasis patients with idiopathic hypercalciuria (IH) in order to elucidate the potential mechanisms underlying changes in cell phenotype induced by bone‑associated factors and their influence on renal nephrolithiasis formation. Blood samples from a total of 29 nephrolithiasis patients with IH, 29 renal stone patients without IH and 29 healthy age‑matched normal controls were subjected to quantification of peripheral serum TGF‑β1, osteopontin (OPN) and bone morphogenetic protein 2 (BMP2) using ELISA. This was followed by detection of BMP2, OPN and 1,25‑dihydroxyvitamin D3 receptor (VDR) mRNA and protein levels in primary renal epithelial cells (PRECs) of IH and HK‑2 human proximal tubular cell lines (control) using reverse transcription quantitative polymerase chain reaction (RT‑qPCR) and western blot analyses. The mRNA expression levels of BMP2, OPN and VDR in PRECs and HK‑2 were evaluated following stimulation with various concentrations of TGF‑β1 (0.5, 2.0 and 5.0 ng/ml), Ca2+ (0.5, 1.5 and 2.5 mM) or TGF‑β1 and Ca2+ combined using RT‑qPCR, respectively. TGF‑β1, BMP2 and OPN expression levels in patients with IH were all significantly higher than those in the control group. The mRNA and protein expression levels of BMP2 and VDR were significantly higher in PRECs than those in HK‑2 cells. Following incubation with TGF‑β1 and/or Ca2+, the mRNA expression levels of BMP2, OPN and VDR in PRECs increased in a dose‑dependent manner; however, no significant differences were observed in HK‑2 cells with increasing TGF‑β1 dosage. Co‑incubation with TGF‑β1 and Ca2+ in PRECs and HK‑2 cell lines resulted in similar effects and the expression of BMP2, OPN and VDR mRNA increased in a time‑dependent manner. In conclusion, the results of the present study demonstrated that TGF‑β1 regulated the expression of BMP2, OPN and VDR in PRECs, but not in HK‑2 cells. Co‑incubation with TGF‑β1 and Ca2+ significantly increased the expression levels of bone‑associated factors in PRECs and HK‑2 cells, which suggested that this process may be partially responsible for the pathogenesis of calcium stone development, and also associated with bone formation and the TGF‑β1‑induced epithelial to mesenchymal transition.
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Deng
D
He
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Shaogang
S
Wang
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Zhaohui
Z
Jia
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Lei
L
Cui
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Yuchao
Y
Lu
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Henglong
H
Hu
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Baolong
B
Qin
D000328:Adult; D055396:Bone Morphogenetic Protein 2 / Q000097:blood / Q000235:genetics / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D016022:Case-Control Studies; D002460:Cell Line; D054338:Cell Transdifferentiation / Q000187:drug effects; D004847:Epithelial Cells / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D015870:Gene Expression; D006801:Humans; D053565:Hypercalciuria / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D053040:Nephrolithiasis / Q000235:genetics / Q000378:metabolism; D053495:Osteopontin / Q000097:blood / Q000378:metabolism; D010641:Phenotype; D053773:Transforming Growth Factor beta1 / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D055815:Young Adult
D055396:Bone Morphogenetic Protein 2; D053773:Transforming Growth Factor beta1; D053495:Osteopontin; D002118:Calcium