Carcinogenesis Advance Access originally published online on August 19, 2008
Carcinogenesis 2008 29(11):2089-2095; doi:10.1093/carcin/bgn198
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
S-adenosylhomocysteine hydrolase downregulation contributes to tumorigenesis


1 Spanish National Cancer Research Center (CNIO), 3 Melchor Fernández Almagro St, Madrid 28029, Spain
2 Pathology Department, Fundació Institut de Recerca Hospital Vall d'Hebron, Passeig Vall d'Hebron 119-129, Barcelona 08035, Spain
* To whom correspondence should be addressed. Tel: +93 4894169; Fax: +93 4894015; Email: melleona{at}ir.vhebron.net
Correspondence may also be addressed to A.Carnero. Tel: +91 7328000; Fax: +91 2246900; Email: acarnero{at}cnio.es
With the idea to discover novel genes involved in proliferation, we have performed a genome-wide loss-of-function genetic screen to identify additional putative tumor suppressor genes. We have previously identified five genes belonging to different biochemical families. In this report, we focused on the study of one of these genes designated S-adenosylhomocysteine hydrolase (SAHH), which has also been previously identified in an independent short hairpin RNA screening. SAHH inactivation confers resistance to both p53 and p16INK4-induced proliferation arrest. Interestingly, SAHH inactivation inhibits p53 transcriptional activity and impairs DNA damage-induced transcription of p21Cip1. Given that SAHH downregulation modulates senescence in primary cells, we also studied SAHH expression in human tumors at the messenger RNA (mRNA) and protein levels. SAHH mRNA was lost in 50% of tumor tissues from 206 patients with different kinds of tumors in comparison with normal tissue counterparts. Moreover, SAHH protein was also affected in some colon cancers. Such findings may be of relevance to cancer research, suggesting that SAHH might be a largely unexplored tumor suppressor.
Abbreviations: cDNA, complementary DNA; MEFs, mouse embryonic fibroblast; mRNA, messenger RNA; PCR, polymerase chain reaction; RT, reverse transcription; SAHH, S-adenosylhomocysteine hydrolase; shRNA, short hairpin RNA; siRNA, small interpherence RNA
These authors contributed equally to this work. Received March 26, 2008; revised August 12, 2008; accepted August 16, 2008.