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. Author manuscript; available in PMC: 2022 Aug 1.
Published in final edited form as: Mol Cancer Ther. 2021 Dec 14;21(2):347–358. doi: 10.1158/1535-7163.MCT-21-0310

Figure 3. SRI31277 inhibits MDSC proliferation and directly alleviates MM cell resistance to BTZ by inhibiting the TGF-β1 pathway in vitro.

Figure 3.

A, MDSCs derived from the BM of OB-Runx2+/+ mice were cultured in medium mixed with BMS from OB-Runx2+/+ or OB-Runx2−/− mice (no tumor injection) and PBS or SRI31277 (40 nM) for 48 h (n=4, BMS from 8 mice per group). Cells were then stained with trypan blue and counted. B-G, 5TGM1-Luc or MPC-11 MM cells were cultured in medium mixed with BMS from OB-Runx2+/+ or OB-Runx2−/− mice (no tumor cell injection) and PBS, BTZ (2.5 nM), SRI31277 (25 nM), or BTZ+SRI31277 for 24 h. B, Percent viability of 5TGM1-Luc MM cells after treatment, assessed by MTT assay (n=4, BMS from 3 mice per group). C, Percent viability of MPC-11 MM cells after treatment, assessed by MTT assay (n=3, BMS from 3 mice per group). D, Representative Western blots showing the detection of cleaved caspase-3 in 5TGM1-Luc MM cells after treatment (left) and densitometric quantification of cleaved caspase-3 normalized to GAPDH (right). E-G, Representative Western blots showing the detection of total and phosphorylated SMAD2/3 and ERK1/2 in 5TGM1-Luc MM cells after each treatment (E) and densitometric quantification of the p-SMAD2/3 to t-SMAD2/3 ratio (F) and of the p-ERK1/2 to t-ERK1/2 ratio (G) normalized to GAPDH. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.005, ****P < 0.001. ns, not significant; p-SMAD2/3, phosphorylated SMAD2/3; t-SMAD2/3, total SMAD2/3; p-ERK1/2, phosphorylated ERK1/2; t-ERK1/2, total ERK1/2.