fig7: Inhibition of P-TEFb impairs EMT and survival of metastatic MDA-MB-231 cells.(A) Treatment of MDA-MB-231 cells with 0.3 μM flavopiridol (Flvp) significantly impairs cell migration as shown by the Transwell assay. The p value (*p<0.05) was determined by the Student's t test. (B) qRT-PCR analysis of Slug expression in MDA-MB-231 cells that have been treated with flavopiridol for 7 hr at the indicated concentrations. (C and D) Clonogenic growth assay. MDA-MB-231 cells were transfected with control vector, Flag-tagged WT LARP7, or Δ2A mutant. The expression of LARP7 and Δ2A was confirmed by Western blotting with anti-Flag. (C). (D) Representative culture areas are shown in the top panel. The number of colonies was quantified and shown in the graph below. The p value (*p<0.05) was determined by the Student's t test.DOI:http://dx.doi.org/10.7554/eLife.02907.012

Mentions: If LARP7 downregulation accelerates malignant progression by increasing expression of EMT genes through elevated P-TEFb activity, we should expect P-TEFb inhibition or re-introduction of LARP7 protein to block EMT and transformation. To test this hypothesis, we first treated the highly invasive and metastatic MDA-MB-231 breast cancer cells with flavopiridol and noted that the treatment significantly inhibited cell migration (Figure 7A). Furthermore, mRNA levels of Slug, a major EMT regulator, were repressed in a dose-dependent manner upon P-TEFb inhibition (Figure 7B). These data suggest that inhibition of P-TEFb can effectively block cell migration in metastatic breast cancer cells.10.7554/eLife.02907.012Figure 7.Inhibition of P-TEFb impairs EMT and survival of metastatic MDA-MB-231 cells.