title: Hypermethylation of the 5' CpG island of the gene encoding the serine protease Testisin promotes its loss in testicular tumorigenesis.
abstract: The Testisin gene (PRSS21) encodes a glycosylphosphatidylinositol (GPI)-linked serine protease that exhibits testis tissue-specific expression. Loss of Testisin has been implicated in testicular tumorigenesis, but its role in testis biology and tumorigenesis is not known. Here we have investigated the role of CpG methylation in Testisin gene inactivation and tested the hypothesis that Testisin may act as a tumour suppressor for testicular tumorigenesis. Using sequence analysis of bisulphite-treated genomic DNA, we find a strong relationship between hypermethylation of a 385 bp 5' CpG rich island of the Testisin gene, and silencing of the Testisin gene in a range of human tumour cell lines and in 100% (eight/eight) of testicular germ cell tumours. We show that treatment of Testisin-negative cell lines with demethylating agents and/or a histone deacetylase inhibitor results in reactivation of Testisin gene expression, implicating hypermethylation in Testisin gene silencing. Stable expression of Testisin in the Testisin-negative Tera-2 testicular cancer line suppressed tumorigenicity as revealed by inhibition of both anchorage-dependent cell growth and tumour formation in an SCID mouse model of testicular tumorigenesis. Together, these data show that loss of Testisin is caused, at least in part, by DNA hypermethylation and histone deacetylation, and suggest a tumour suppressor role for Testisin in testicular tumorigenesis.
authors.affiliation: Leukaemia Foundation and Cellular Oncology Laboratories, Queensland Institute of Medical Research, Queensland, Australia.
authors.forename: K J
authors.initials: KJ
authors.lastname: Manton
authors.forename: M L
authors.initials: ML
authors.lastname: Douglas
authors.forename: S
authors.initials: S
authors.lastname: Netzel-Arnett
authors.forename: D R
authors.initials: DR
authors.lastname: Fitzpatrick
authors.forename: D L
authors.initials: DL
authors.lastname: Nicol
authors.forename: A W
authors.initials: AW
authors.lastname: Boyd
authors.forename: J A
authors.initials: JA
authors.lastname: Clements
authors.forename: T M
authors.initials: TM
authors.lastname: Antalis
mesh_terms: D000328:Adult; D000818:Animals; D045744:Cell Line, Tumor; D018899:CpG Islands; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000378:metabolism*; D058851:GPI-Linked Proteins; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D016513:Mice, SCID; D009919:Orchiectomy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000235:genetics* / Q000378:metabolism*; D013736:Testicular Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000601:surgery; D014183:Transplantation, Heterologous
chemical_list: D004273:DNA, Neoplasm; D058851:GPI-Linked Proteins; D056572:Histone Deacetylase Inhibitors; D008565:Membrane Proteins; C120203:PRSS21 protein, human; D012697:Serine Endopeptidases