MUC1-C nuclear localization drives invasiveness of renal cancer cells through a sheddase/gamma secretase dependent pathway

Audrey Bouillez,Nicolas Pottier,Caroline Butruille,Viviane Gnemmi,Sébastien Aubert,Malika Hamdane,François Glowacki,Christelle Cauffiez,Brigitte Hémon,Xavier Leroy,Isabelle Van Seuningen,Nicolas Sergeant,Michaël Perrais,Bélinda Ringot,Kelly Gaudelot

doi:10.18632/oncotarget.1768

Abstract

MUC1 is a membrane-anchored mucin and its cytoplasmic tail (CT) can interact with many signaling pathways and act as a co-transcription factor to activate genes involved in tumor progression and metastasis. MUC1 is overexpressed in renal cell carcinoma with correlation to prognosis and has been implicated in the hypoxic pathway, the main renal carcinogenetic pathway. In this context, we assessed the effects of MUC1 overexpression on renal cancer cells properties. Using shRNA strategy and/or different MUC1 constructs, we found that MUC1-extracellular domain and MUC1-CT are involved in increase of migration, cell viability, resistance to anoikis and in decrease of cell aggregation in cancer cells. Invasiveness depends only on MUC1-CT. Then, by using siRNA strategy and/or pharmacological inhibitors or peptides, we showed that sheddases ADAM10, ADAM17 and gamma-secretase are necessary for MUC1 C-terminal subunit (MUC1-C) nuclear location and in increase of invasion property. Finally, MUC1 overexpression increases ADAM10/17 protein expression suggesting a positive regulatory loop. In conclusion, we report that MUC1 acts in renal cancer progression and MUC1-C nuclear localization drives invasiveness of cancer cells through a sheddase/gamma secretase dependent pathway. MUC1 appears as a therapeutic target by blocking MUC1 cleavage or nuclear translocation by using pharmacological approach and peptide strategies.

Highlights

MUC1 is a large O-glycoprotein type I translated as a single polypeptide that undergoes autocleavage into N-terminal (MUC1-N) and C-terminal (MUC1-C) subunits allowing the formation of a heterodimer through a stable non-covalent association [1]
MUC1 full length (MUC1FL) ACHN cells presented significantly decreased cell-cell aggregation levels compared to EV ACHN cells (39% vs 79%, p
Our team and others have reported that MUC1 (i) is consistently overexpressed in clear renal cell carcinoma (cRCC) with a high expression correlated to worse prognosis [11, 18], (ii) cytoplasmic immunostaining is associated with metastatic status [11] and (iii) is a target gene of Hypoxia Inducible Factor (HIF)-1 transcription factor which is a master key of the hypoxia pathway, the main renal carcinogenetic pathway [11]

Summary

Introduction

MUC1 is a large O-glycoprotein type I translated as a single polypeptide that undergoes autocleavage into N-terminal (MUC1-N) and C-terminal (MUC1-C) subunits allowing the formation of a heterodimer through a stable non-covalent association [1]. MUC1 expression is cell- and tissue-specific and is altered during carcinogenesis. The MUC1-N is an extracellular domain containing extensively O-glycosylated tandem repeat 20 amino acid (AA) sequence and protudes far away from the apical side of the cell (200–500 nm). The MUC1-C includes a 58-AA extracellular domain, a 28AA transmembrane domain and a 72-AA cytoplasmic tail www.impactjournals.com/oncotarget (CT) [1]. MUC1-N may be released from cell-surface by a mechanism dependent on at least two sheddases, TACE/ ADAM17 [2] and MT1-MMP/MMP14 [3]. MUC1-C (i) is a substrate for γ-secretase [4] and several kinases such as Src, GSK3β, PI3K [1], (ii) can interact with tyrosine kinase receptors such as EGFR and (iii) plays a role in signal transduction. MUC1-CT acts as a co-transcription factor to activate genes involved in tumor progression and metastasis [1]

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