Phosphocaveolin-1 Enforces Tumor Growth and Chemoresistance in Rhabdomyosarcoma

Fiorella Faggi,Manuela Cominelli,Rosario Donato,Alessandro Fanzani,Francesca Riuzzi,Fabio Penna,Ilaria Perini,Stefania Mitola,Marina Colombi,Eugenio Monti,Maurilio Sampaolesi,Silvia Codenotti,Paola Costelli,Stefano Calza,Stefania Rossi,Guglielmo Sorci,Pietro Luigi Poliani,Raffaella Vescovi,Natasha Kyprianou

doi:10.1371/journal.pone.0084618

Fiorella Faggi, Manuela Cominelli + Show 17 more

Open Access

https://doi.org/10.1371/journal.pone.0084618

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Abstract

Caveolin-1 (Cav-1) can ambiguously behave as either tumor suppressor or oncogene depending on its phosphorylation state and the type of cancer. In this study we show that Cav-1 was phosphorylated on tyrosine 14 (pCav-1) by Src-kinase family members in various human cell lines and primary mouse cultures of rhabdomyosarcoma (RMS), the most frequent soft-tissue sarcoma affecting childhood. Cav-1 overexpression in the human embryonal RD or alveolar RH30 cells yielded increased pCav-1 levels and reinforced the phosphorylation state of either ERK or AKT kinase, respectively, in turn enhancing in vitro cell proliferation, migration, invasiveness and chemoresistance. In contrast, reducing the pCav-1 levels by administration of a Src-kinase inhibitor or through targeted Cav-1 silencing counteracted the malignant in vitro phenotype of RMS cells. Consistent with these results, xenotransplantation of Cav-1 overexpressing RD cells into nude mice resulted in substantial tumor growth in comparison to control cells. Taken together, these data point to pCav-1 as an important and therapeutically valuable target for overcoming the progression and multidrug resistance of RMS.

Highlights

Caveolins (i.e. Cav-1, Cav-2 and Cav-3) are 21–24 kDa membrane-associated proteins that mainly localize in the 50– 100 nm cholesterol-enriched invaginations of the plasma membrane, known as caveolae [1,2,3]
The expression levels of Caveolin family members were analysed by western blot using four human RMS cell lines and two mouse primary tumor cultures established from transgenic Myf6Cre/p532/2 and Myf6Cre/Pax3-Foxo1/p532/2 mice [21,24]
Cav-1 and Cav-2 genes are located in a fragile site that is frequently deleted in human cancers [46], indicating a common role as tumor suppressors

Summary

Introduction

Caveolins (i.e. Cav-1, Cav-2 and Cav-3) are 21–24 kDa membrane-associated proteins that mainly localize in the 50– 100 nm cholesterol-enriched invaginations of the plasma membrane, known as caveolae [1,2,3]. In response to a variety of stimuli such as growth factors, UV irradiation, mechanical and oxidative stress, Cav-1 can be phosphorylated on tyrosine 14 (hereafter referred as to pCav-1) by members of the sarcoma kinases (Src-kinases) [8,9,10], in turn leading to activation of pathways linked to cell death or survival [11]. The current classification includes two major histological variants, known as embryonal (ERMS) and alveolar (ARMS), with the former characterized by a complex genomic aetiogenesis [16,17] and the latter by the prevalent expression of chimeric transcription factors generated by the fusion of the paired box 3 or 7 with forkhead box O1 (Pax3-Foxo or Pax7-Foxo1) as a result of specific chromosomal translocations [29,30]. We provide further evidence that Cav-1 is consistently phosphorylated through a Src-dependent mechanism in various ERMS and ARMS cell lines, playing a pivotal role in tumor growth and chemoresistance

Results

Discussion

Materials and Methods