Fig. 6

TGF-β can significantly promote tumorigenesis under hypoxia in vivo, which can be blocked by knockdown of Smad2/3 and HIF-1α. a, Compared with Smad2/3 knockdown or both Smad2/3 and HIF-1α knockdown, HIF-1α knockdown alone can more effectively inhibit TGF-β-driven tumor formation. A549 cells stably expressing GFP were injected subcutaneously into the armpit of the forelimb of nude mice. TGF-β (50 µl, 5 ng/ml) was injected into a parallel subcutaneous tumor group once a week. Actual tumors are shown. b, Statistical analysis of tumor formation in a, n = 6 mice/group. c, Immunohistochemical staining of paraffin sections prepared from subcutaneous tumors of nude mice (scale bars, 50 μm). TGF-β plays opposing roles in regulating PKM2 and p21 expression by enhancing the crosstalk of p-Smad2/3 and HIF-1α. d, Changes in the relative fluorescence intensity of subcutaneous tumors with the indicated treatments in NOD/SCID mice (5 mice in each group, one of them died in the group of TGF-β + HIF-1α mut). e, A549 subcutaneous tumor tissue fluorescence showed that Image-iT™ Green Hypoxia Reagent detected some hypoxic areas. f, Taking the blank control group as a reference, the results showed that the fluorescence intensity of the subcutaneous tumors of nude mice was significantly higher with indicated treatments. HIF-1α mut +TGF-β group had the strongest fluorescence intensity. ****P < 0.0001