Fig. 2: GARP promotes the proliferation of bone sarcoma cell lines through the activation of TGF-β.

A Overexpression of GARP in bone sarcoma cell lines. Representative dot plots of non-transduced (NT) and GARP-overexpressing (GARP⁺⁺) G292 (top panel), SAOS-2 (middle panel), and RD-ES (bottom panels). Corresponding isotype staining is represented by vertical lines in all plots. B GARP-overexpression increases the proliferation of bone sarcoma cell lines. Growth curves of NT, GARP⁺⁺, and EGFP-overexpressing (EGFP⁺⁺) G292, SAOS-2, and RD-ES cells were generated by plotting the cumulative cell numbers vs. time. Data are shown as mean (SD) of three individual experiments. * =P < 0.05. C The fold-increase in cell numbers of EGFP⁺⁺ and GARP⁺⁺ cells in relation to NT cells at the end of each experiment are shown as mean (SD) of three individual experiments. ** =P < 0.01. D GARP⁺⁺ sarcoma cells produce more active TGF-β compared to NT cells. NT and GARP⁺⁺ G292, SAOS-2, and RD-ES cells were co-cultured for 24 h with SBE-HEK293 cells subsequently assayed for luciferase activity. The fold-increase in TGF-β activity of the GARP⁺⁺ cells is relative to the NT for each cell line. Data are represented as mean (SD) of three independent experiments. * =P < 0.05, ** =P < 0.01. E The increased proliferation of GARP⁺⁺ sarcoma cells depends on TGF-β. NT and GARP⁺⁺ G292, SAOS-2, and RD-ES were cultured in the absence or presence of SB431542 or anti-TGF-β1/2/3 Ab (11D1) for 3 days and subsequently counted. Fold-increase in cell number is relative to NT for each cell line. Data are shown as mean (SD) of three independent experiments. * =P < 0.05; ** =P < 0.01.