Fig. 5. C3 expression is upregulated by the IL-4/IL-13-STAT6 signaling pathway.

A Levels of IL-6, IL-13, IL-12, and G-CSF were increased in serum of mice with advanced tumor stages. Serum derived from MMTV-PyMT at different time points were measured via 23 cytokines multiplexed bead immunoassay. n = 4 mice each. B C3 expression in LMSCs was induced by IL-13. LMSCs in culture were treated with IL-6, IL-13, IL-12, or G-CSF (10 ng/ml for 24 hr, respectively), and mRNA and supernatant from the treated LMSCs were examined for C3. Med represents cultured medium. n = 4 (left panel), n = 3 (right panel) individual experiments. C Levels of phosphorylated STAT6 and total STAT6 in LMSCs. Proteins from 5 × 10⁴ A-, PM-, or M-LMSCs grown in 12-well plates for 24 h were collected and detected through immunoblotting. The WB images were representative of two independent experiments. D STAT6 is required for IL-13-induced C3 expression. mRNA and supernatant from cultured WT or Stat6^−/− LMSCs treated with or without IL-13 (10 ng/ml for 24 h) were examined for C3. Med represents cultured medium. n = 4 individual experiments. E IL-4 and IL-13 potently induced C3. C3 mRNA from cultured LMSCs treated with IL-4, IL-13, or IL-4/IL-13 (10 ng/ml for 24 h) was analyzed by qRT-PCR. Med represent cultured medium. n = 3 individual experiments. F Increasing IL-4 expression with advancing tumor development. IL-4 in pulmonary extracts (PEs) derived from MMTV-PyMT mice at different tumor stages were measured by ELISA. n = 4 mice each. G Stat6-deficient LMSCs did not acquire IL-4/IL-13-conferred metastasis-promoting ability. WT or Stat6^−/− LMSCs treated with or without IL-4/IL-13 (20 ng/ml) were co-administered with 4T1 cells into BALB/c mice and lung metastatic nodules were counted on day 14. Med was the cultured medium. n = 8 mice each. All the data are presented as mean values ± SD. ns, not significant; p < 0.05, significant, using a one-way ANOVA with Sidak’s post test. Source data are provided as a Source Data file.