The p53 isoform Δ133p53β promotes cancer stem cell potential.
Bottom Line: Here we report that Δ133p53β, a TP53 splice variant, enhanced cancer cell stemness in MCF-7 breast cancer cells, while its depletion reduced it.Like in MCF-7 cells, SOX2, OCT3/4, and NANOG expression were positively regulated by Δ133p53β in these cells.Our findings show that Δ133p53β supports CSC potential.
Affiliation: Centre National de la Recherche Scientifique, UMR 5237, Centre de Recherche en Biochimie Macromoléculaire, Université Montpellier, 1919 route de Mende, 34293 Montpellier Cedex 5, France.Show MeSH
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Mentions: Topoisomerase II inhibitors (etoposide-VP16 and doxorubicin) are frequently used as adjuvant chemotherapy treatment for several cancer types alone or in combination with other drugs (cisplatin most frequently). Topoisomerase II inhibitors induce double-strand DNA breaks, a genotoxic stress that strongly activates p53 signaling. Upregulation of TAp53 should be beneficial due to its ability to induce cell-cycle arrest, apoptosis, and to negatively regulate cell reprogramming. We thus assessed whether etoposide could affect Δ133p53 expression and CSC potential in breast cancer cell lines. Increasing concentrations of etoposide resulted in TAp53α stabilization in MCF-7. As expected, p21 expression (positively regulated by p53) was increased, whereas C-MYC expression (negatively regulated by p53) was reduced (Figure 4A), as also confirmed by qRT-PCR quantification (Figure 4B). Moreover, qRT-PCR and western blot analysis showed that, upon etoposide treatment, Δ133p53 isoforms (Figures 4C and 4D) as well as OCT3/4, NANOG, and SOX2 (Figure 4E) were strongly upregulated in a dose-dependent manner. This last result is particularly intriguing because TAp53α, which is considered as a negative regulator of pluripotency/reprogramming genes, is stabilized and transcriptionally active.
Affiliation: Centre National de la Recherche Scientifique, UMR 5237, Centre de Recherche en Biochimie Macromoléculaire, Université Montpellier, 1919 route de Mende, 34293 Montpellier Cedex 5, France.