Molecular characterization of the TMPRSS2-ERG gene fusion in the NCI-H660 prostate cancer cell line – a new perspective for an old model

Kirsten D Mertz, Sunita R Setlur, Saravana Mohan Dhanasekaran, Francesca Demichelis, Sven Perner, Scott Tomlins, Joelle Tchinda, Bharathi Laxman, Robert L Vessella, Rameen Beroukhim, Charles Lee, Arul M Chinnaiyan and Mark A. Rubin

Year 2007, Volume 9, Issue 3

Abstract

Recent studies have established that a significant fraction of prostate cancers harbor a signature gene fusion between the 5Â’ region of the androgen-regulated TMPRSS2 and an ETS family transcription factor, most commonly ERG. Studying the molecular mechanisms and the functional consequences of this important chromosomal rearrangement is currently limited to the VCaP cell line derived from a vertebral bone metastasis of a hormone-refractory prostate tumor. Here we report on the NCI-H660 cell line, derived from a metastatic site of an extrapulmonary small cell carcinoma arising from the prostate. NCI-H660 harbors the TMPRSS2-ERG fusion with a homozygous intronic deletion between TMPRSS2 and ERG. We demonstrate this by quantitative real-time PCR, a two-stage dual-color interphase FISH assay testing for TMPRSS2 and ERG break-aparts and Single Nucleotide Polymorphism oligonucleotide arrays. The deletion is consistent with the common intronic deletion found on chromosome 21q22.2-3 in human prostate cancer samples. For the first time, we demonstrate the physical juxtaposition of TMPRSS2 and ERG on the DNA level by fiber FISH. The androgen receptor negative NCI-H660 cell line expresses ERG in an androgen-independent fashion. This in vitro model system has the potential to provide important pathobiologic insights into TMPRSS2-ERG fusion prostate cancer and should be included in the armamentarium to study prostate cancer biology.

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