Fig. 5: CDK4- and filamin A-driven increased sensitivity to paclitaxel in TNBC models.

A Left: Immunoblot showing different CDK4 levels between parental MDA-MB-231 and MDA-MB-231 CDK4 cells. Tubulin is shown for housekeeping purposes. Experiment was repeated 3 times with similar results. Middle: colony assay pictures (upper panel) and quantitation or relative plating efficiency chart (lower panel) of parental MDA-MB-231 and MDA-MB-231 CDK4 cells exposed to various concentrations of paclitaxel. In the relative plating efficiency chart, each condition is normalized to the untreated condition for each MDA-MB-231 variant. Data are presented as the mean ± SEM, n ≥ 6 independent experiments; two-sided unpaired t-test. Right: IC50 plots showing the ~2.7-fold variation in paclitaxel sensitivity. Data are presented as the mean ± SEM, n ≥ 3 independent experiments; B Immunoblot showing the upregulation of filamin A in MDA-MB-231 CDK4 cells versus the parental cells; tubulin is shown for housekeeping purposes. Samples derived from the same experiment and blots were processed in parallel. Experiment was repeated 3 times with similar results. C Real-time PCR showed a 2.5-fold increase in filamin A mRNA levels in MDA-MB-231 CDK4 cells. Data are presented as the mean ± SEM, n = 4 independent experiments; two-sided unpaired t-test. D Left: Immunoblot showing filamin A levels in MDA-MB-231 FLNA and MDA-MB-231 WT cells. No changes were observed in CDK4 levels in the former. Vinculin: housekeeping. Samples derived from the same experiment and blots were processed in parallel. Experiment was repeated 3 times with similar results. Right: IC50 charts showing the sensitization to paclitaxel in MDA-MB-231 FLNA cells compared to the parental cells (Mean±SEM, n≥3 independent experiments) together with examples of colony assays. E Left: Transient filamin A knockdown with siRNA in MDA-MB-231 CDK4 cells. Experiment was repeated 3 times with similar results. Right: phenotype recovery: the increased sensitivity to paclitaxel in MDA-MB-231 CDK4 cells is restored back to normal (i.e., similar IC50 to that of MDA-MB-231 WT) when filamin A is downregulated. Data are represented as mean ± SEM, n ≥ 14 independent experiments. Examples of colony assays are shown. Source data are provided as a Source data file.