Figure 4.

MBNL1 is a key target of BCL11A that controls the TNBC spliced transcriptome and invasion. A, MBNL1 mRNA expression was assessed by qPCR. B, MBNL1 protein was quantified by western blotting following transfection with BCL11A or nonspecific control siRNA in MDA-MB-231 or MDA-MB-468 cells. Both bands correspond to MBNL1 protein, as determined by using siRNA to MBNL1. C, MBNL1, BCL11A, or both were transiently silenced in MDA-MB-231 cells, and the relative mRNA expression of BCL11A (C) and MBNL1 (D) was evaluated by qPCR. E, fold change in invasion was assessed after BCL11A and MBNL1 silencing in the MDA-MB-231 cells. F, fold change in viable cells 4 days after BCL11A and MBNL1 silencing was determined using the Cyto-X colorimetric assay. G, disease-specific (DSS) survival was determined using the METABRIC data set (39). Samples (all subtypes) were divided into BCL11A high and MBNL1 low (n = 148), BCL11A low + MBNL1 high (n = 345), or intermediate (n = 1478). For panels A–F, significance of differences was calculated using an unpaired t test: *, p < 0.05; ***, p < 0.01; ***, p < 0.001; n.s., not signficant. For panel G, significance of difference between the survival curves was calculated using a log-rank test: green versus red line, p = 0.0002; red versus black line, p = 0.04; green versus black line, p = 0.004.