Figure 4: MRTF-SRF signalling mediates TGFβ increased in BTIC self-renewal.
From: TGFβ induces the formation of tumour-initiating cells in claudinlow breast cancer
(a) Regulatory network analysis used to infer differential activity of position weight matrices (PWMs) between two conditions (TGFβ versus SB) in a given cell line (c). The regularized t-statistics of differential expression of ~15,000 genes between the two conditions (t) is regressed against the binding profiles, (b), of ~555 PWMs (f=1,....,555, coded as 1 s-bound and 0 s-unbound) to infer differential activity of PWMs. Differential activity estimates are provided by the regression coefficients (A). (b) Bar chart shows log2 fold change of MS-ICs in M1 cultures of untreated (−) and TGFβ-treated (Tβ) HCC1954 (b) and MDA-MB-231 (c) transfected with siRNAs to knockdown Fos, CTGF, Cyr61 and SRF as indicated, compared with scramble siRNA (sc)-untreated M1 cultures. Data represents the mean ±s.d. of three independent experiments. *TGFβ-treated scramble siRNA (sc) versus TGFβ-treated siRNA (Fos, CTGF, Cyr61 and SRF), P<0.05 (Student's t-test). (d) Bar chart shows log2 fold change of MS-ICs in TGFβ-treated MDA-MB-231 M1 cultures in the presence of 25 μM Y-27632 compared with M1-untreated cultures (−). Error bars represent ±s.d. of three independent experiments. (e) LDA assay using different doses of single cells derived from MDA-MB-231 M1 mammospheres cells left untreated or treated with TGFβ (2.5 ng ml−1) in the absence (−) or presence of Y-27632 for 7 days. Bars represent fold change in total number of BTICs in M1 cultures as compared with M1 untreated cultures. (f) Bar chart shows log2 fold change of MS-ICs in TGFβ-treated MDA-MB-231 M1 cultures in the absence (−) or presence of 0.5 μM latrunculin B (LB) or of 0.4 μM latrunculin A (LA) compared with untreated cells. Error bars represent ±s.d. of at least three independent experiments.
