TAK1 signaling regulates p53 through a mechanism involving ribosomal stress

Justin Zonneville,Mikhail Nikiforov,Andrei V Bakin,Vincent Wong,Michelle Limoge

doi:10.1038/s41598-020-59340-5

Abstract

Triple-negative breast cancer (TNBC) is among the most aggressive forms of breast cancer with limited therapeutic options. TAK1 is implicated in aggressive behavior of TNBC, while means are not fully understood. Here, we report that pharmacological blockade of TAK1 signaling hampered ribosome biogenesis (RBG) by reducing expression of RBG regulators such as RRS1, while not changing expression of ribosomal core proteins. Notably, TAK1 blockade upregulated expression of p53 target genes in cell lines carrying wild type (wt) TP53 but not in p53-mutant cells, suggesting involvement of ribosomal stress in the response. Accordingly, p53 activation by blockade of TAK1 was prevented by depletion of ribosomal protein RPL11. Further, siRNA-mediated depletion of TAK1 or RELA resulted in RPL11-dependent activation of p53 signaling. Knockdown of RRS1 was sufficient to disrupt nucleolar structures and resulted in activation of p53. TCGA data showed that TNBCs express high levels of RBG regulators, and elevated RRS1 levels correlate with unfavorable prognosis. Cytotoxicity data showed that TNBC cell lines are more sensitive to TAK1 inhibitor compared to luminal and HER2+ cell lines. These results show that TAK1 regulates p53 activation by controlling RBG factors, and the TAK1-ribosome axis is a potential therapeutic target in TNBC.

Highlights

Triple-negative breast cancer (TNBC) is among the most aggressive forms of breast cancer with limited therapeutic options
We found that TGF-beta-activated kinase-1 (TAK1)-i effectively blocked TNF-induced activation of NFκB signaling measured by phosphorylation of RELA and protein levels of a negative regulator IκB-alpha www.nature.com/scientificreports (Fig. 1A)
Known p53 target genes[34] constituted roughly 25% of genes commonly induced by TAK1 inhibitors (TAK1-i) in MCF7 and MCF10A cell lines carrying p53-wt, whereas these genes were not regulated by TAK1-i in MDA-MB-231 carrying mutant p53R280K (Fig. 1C; Supplementary Table 1)

Summary

Introduction

Triple-negative breast cancer (TNBC) is among the most aggressive forms of breast cancer with limited therapeutic options. Cytotoxicity data showed that TNBC cell lines are more sensitive to TAK1 inhibitor compared to luminal and HER2+ cell lines. These results show that TAK1 regulates p53 activation by controlling RBG factors, and the TAK1ribosome axis is a potential therapeutic target in TNBC. Recent studies, including from our group, have implicated TGF-beta-activated kinase-1 (TAK1) in cancer progression and metastasis of breast, lung and colon cancers[6,7,8,9,10,11,12]. TAK1 activation involves E3-ubiquitin ligases cIAP1 and cIAP2 (cellular inhibitors of apoptosis, cIAPs), which mediate addition of K(lysine)-63-linked ubiquitin chains to RIP kinase and other signaling proteins[16]. Expression profiles were measured using microarrays and two independent preparations of total RNA from cells treated with TAK1-i for 6 hours. (C) TAK1-i increases expression of p53 target genes in MCF7 and MCF10A cell lines carrying p53 wt but not in p53-

Methods

Results

Conclusion