Abstract
The tyrosine kinase Src is frequently activated in advanced human prostate carcinomas and its activation correlates with tyrosine phosphorylation of the RNA-binding protein Sam68. Herein, we have investigated the expression and function of Sam68 in human prostate cancer cells. Analysis of specimens obtained from 20 patients revealed that Sam68 is upregulated at the protein level in 35% of the samples. Real-time polymerase chain reaction confirmed the results at the mRNA level in most patients. Downregulation of Sam68 by RNAi in LNCaP prostate cancer cells delayed cell cycle progression and reduced the proliferation rate. Moreover, depletion of Sam68 sensitized cells to apoptosis induced by DNA-damaging agents. Similarly, stable cell lines expressing a truncated GFP-Sam68GSG protein displayed reduced growth rates and higher sensitivity to cisplatin-induced apoptosis. Microarray analyses revealed that a subset of genes involved in proliferation and apoptosis were altered when Sam68 was knocked down in LNCaP cells. Our results indicate that Sam68 expression supports prostate cancer cells proliferation and survival to cytotoxic agents.
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Abbreviations
- PCa:
-
prostate carcinoma
- STAR:
-
signal transduction and activation of RNA metabolism
- cdk:
-
cyclin dependent kinase
- EDTA:
-
ethilenediaminetetraacetic acid
- DMSO:
-
dimethyl-sulfoxide
- BSA:
-
bovine serum albumin
- SDS:
-
sodium dodecyl sulfate
- BrdU:
-
5-bromo-2-deoxyuridine
- MTS:
-
[3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt]
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Acknowledgements
We wish to thank Professor S Di Stasi for help with patients recruitment, Professor R Geremia for helpful discussion; Dr Andrea Bianchini for microarray data analysis; Drs Ezio Giorda and Rita Carsetti for help with FACS analysis. This work was supported by grants from the Associazione Italiana Ricerca sul Cancro (AIRC) and the Italian Ministry of Education (PRIN 2004) to CS MP Paronetto is supported by a Post-doctoral scholarship from the IRCCS Fondazione Santa Lucia.
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Busà , R., Paronetto, M., Farini, D. et al. The RNA-binding protein Sam68 contributes to proliferation and survival of human prostate cancer cells. Oncogene 26, 4372–4382 (2007). https://doi.org/10.1038/sj.onc.1210224
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DOI: https://doi.org/10.1038/sj.onc.1210224
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