Expression and regulation of amphiregulin in G sα-mutated human bone marrow stromal cells of fibrous dysplasia of mandible

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Fibrous dysplasia (FD) is a focal bone lesion composed primarily of immature bone marrow stromal cells along with spicules of immature woven bone. However, cellular differentiation and proliferation in mutant human bone marrow stromal cells (hBMSCs) of FD have not been fully elucidated. Therefore, the aim of this study was to investigate the occurrence of G(s)α mutation at the Arg(201) codon in hBMSCs and human trabecular bone cells (hTBCs, osteoblast-like cells). In addition, we evaluated the gene expression and protein secretion of amphiregulin from hBMSCs and hTBCs and assessed the biologic activity and possible mechanism of amphiregulin in our system. Mutant hBMSCs from FD patients and hTBCs from disease-free bone specimens of the same patient were successfully cultured. We studied the G(s)α mutations at the Arg(201) codon by means of polymerase chain reaction (PCR)-restriction fragment length polymorphism. Gene expression and protein secretion of amphiregulin in hBMSCs and hTBCs was confirmed by reverse-transcription (RT) PCR and Western blotting analysis. The modulation proliferation and possible mechanism of the exogenous addition of amphiregulin and epidermal growth factor receptor tyrosine kinase inhibitor (AG-1478) were assessed by using Wst-1 assays. The G(s)α mutations in clonal adherent mutant hBMSCs and hTBCs were successfully identified. We identified amphiregulin to be highly expressed in hBMSCs compared with hTBCs. The growth of hBMSCs was stimulated by the exogenous addition of amphiregulin and inhibited by AG-1478. The G(s)α-mutant hBMSCs were successfully identified, and amphiregulin may play a significant role in the proliferation of hBMSCs.