L-plastin Ser5 phosphorylation is modulated by the PI3K/SGK pathway and promotes breast cancer cell invasiveness

Cell Communication and Signaling

Elisabeth Schaffner-Reckinger¹  Dunja Stojevski¹  Raquel A. C. Machado¹  Alexandre Baron²  Thomas Sauter³  Sébastien De Landtsheer³  Philippe Lucarelli⁴ 

[1] Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, Faculty of Science, Technology and Medicine, University of Luxembourg, CAMPUS Belval, BT1, 7, avenue des Hauts-Fourneaux, 4362, Esch-sur-Alzette, Luxembourg;Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, Faculty of Science, Technology and Medicine, University of Luxembourg, CAMPUS Belval, BT1, 7, avenue des Hauts-Fourneaux, 4362, Esch-sur-Alzette, Luxembourg;Immune Systems Biology Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg;Systems Biology Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg;Systems Biology Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg;Sensile Medical AG, Olten, Switzerland;

关键词: L-plastin;    Actin-bundling;    PI3K pathway;    ERK/MAPK pathway;    SGK;    RSK;    Invasion;    Invadopodia;    Extracellular matrix degradation;    Metastasis;   

DOI  :  10.1186/s12964-021-00710-5

来源: Springer

【 摘 要 】

BackgroundMetastasis is the predominant cause for cancer morbidity and mortality accounting for approximatively 90% of cancer deaths. The actin-bundling protein L-plastin has been proposed as a metastatic marker and phosphorylation on its residue Ser5 is known to increase its actin-bundling activity. We recently showed that activation of the ERK/MAPK signalling pathway leads to L-plastin Ser5 phosphorylation and that the downstream kinases RSK1 and RSK2 are able to directly phosphorylate Ser5. Here we investigate the involvement of the PI3K pathway in L-plastin Ser5 phosphorylation and the functional effect of this phosphorylation event in breast cancer cells.MethodsTo unravel the signal transduction network upstream of L-plastin Ser5 phosphorylation, we performed computational modelling based on immunoblot analysis data, followed by experimental validation through inhibition/overexpression studies and in vitro kinase assays. To assess the functional impact of L-plastin expression/Ser5 phosphorylation in breast cancer cells, we either silenced L-plastin in cell lines initially expressing endogenous L-plastin or neoexpressed L-plastin wild type and phosphovariants in cell lines devoid of endogenous L-plastin. The established cell lines were used for cell biology experiments and confocal microscopy analysis.ResultsOur modelling approach revealed that, in addition to the ERK/MAPK pathway and depending on the cellular context, the PI3K pathway contributes to L-plastin Ser5 phosphorylation through its downstream kinase SGK3. The results of the transwell invasion/migration assays showed that shRNA-mediated knockdown of L-plastin in BT-20 or HCC38 cells significantly reduced cell invasion, whereas stable expression of the phosphomimetic L-plastin Ser5Glu variant led to increased migration and invasion of BT-549 and MDA-MB-231 cells. Finally, confocal image analysis combined with zymography experiments and gelatin degradation assays provided evidence that L-plastin Ser5 phosphorylation promotes L-plastin recruitment to invadopodia, MMP-9 activity and concomitant extracellular matrix degradation.ConclusionAltogether, our results demonstrate that L-plastin Ser5 phosphorylation increases breast cancer cell invasiveness. Being a downstream molecule of both ERK/MAPK and PI3K/SGK pathways, L-plastin is proposed here as a potential target for therapeutic approaches that are aimed at blocking dysregulated signalling outcome of both pathways and, thus, at impairing cancer cell invasion and metastasis formation.9rn5EeEuriEpmsCBgdyXncVideo abstract

【 授权许可】

CC BY