RPS15A Mediates PI3K/AKT Signaling-Induced Parathyroid Cell Proliferation in Rats with Secondary Hyperparathyroidism.

Objective: Ribosomal protein S15A (RPS15A) has been identified as a new oncogene in several tumors, but its functional role in secondary hyperparathyroidism (SHPT) characterized by increased serum parathyroid hormone (PTH) level and parathyroid cell proliferation remains unclear.

Methods: A rat model of SHPT was successfully established with a high-phosphorus diet plus 5/6 nephrectomy. ELISA assay was used to determine PTH, calcium and phosphorus and ALP activity. Cell proliferation was analyzed by Cell counting Kit-8 (CCK-8) assay. Flow cytometry assay was utilized to determine cell cycle distribution and apoptosis in parathyroid cells. LY294002, an inhibitor of PI3K/AKT signaling, was used to elucidate the relationship between RPS15A and PI3K/AKT signaling. Immunohistochemical (IHC) staining, quantitative real time PCR and western blot analysis were applied to determine related molecular levels.

Results: Our data showed an upregulation of RPS15A and activated PI3K/AKT signaling pathway in the parathyroid gland tissues of SHPT rats, accompanied with increased PTH, calcium and phosphorus levels. Knockdown of RPS15A decreased parathyroid cell proliferation, induced cell cycle arrest and apoptosis. Treatment with LY294002 reversed the effects of pcDNA3.1-RPSH15A in parathyroid cells.

Conclusions: Our study demonstrated RPS15A-mediated PI3K/AKT pathway as a novel molecular mechanism in the pathogenesis of SHPT, which may provide a new drug target in the future.