The PTEN gene in locally progressive prostate cancer is preferentially inactivated by bi-allelic gene deletion

• Published in: The Journal of pathology 2006-04, Vol.208 (5), p.699-707
• Main Authors: Verhagen, PCMS, van Duijn, PW, Hermans, KGL, Looijenga, LHJ, van Gurp, RJHLM, Stoop, H, van der Kwast, TH, Trapman, J
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Chromosomes, Human, Pair 10 - genetics; Disease Progression; DNA, Neoplasm - genetics; Gene Deletion; Gene Silencing; Humans; In Situ Hybridization, Fluorescence; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Nephrology. Urinary tract diseases; Nucleic Acid Hybridization - methods; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Polymerase Chain Reaction - methods; Polymorphism, Single-Stranded Conformational; prostate neoplasm; Prostatic Neoplasms - genetics; Prostatic Neoplasms - metabolism; PTEN; PTEN Phosphohydrolase - genetics; PTEN Phosphohydrolase - metabolism; Tumors of the urinary system; tumour suppressor gene; Urinary tract. Prostate gland
• ISSN: 0022-3417; 1096-9896
• DOI: 10.1002/path.1929

PTEN is frequently inactivated during the development of many cancers, including prostate cancer, and both bi‐allelic and mono‐allelic PTEN inactivation may contribute to tumorigenesis. PTEN mutations in clinical cancer specimens can easily be recorded but mono‐ or bi‐allelic gene deletions are often difficult to assess. We performed a comprehensive study to detect PTEN inactivation in 40 locally progressive clinical prostate cancer specimens obtained by transurethral resection of the prostate, utilizing a variety of complementary technical approaches. The methods to detect PTEN deletion included allelotype analysis, dual‐colour FISH and array‐based CGH. We also applied a novel semi‐quantitative approach, assessing the PTEN‐WT (wild‐type): PTEN‐Ψ (pseudogene) ratio (WPR). Structural analysis of PTEN was performed by single‐strand conformational polymorphism (PCR‐SSCP) and sequencing. PTEN protein expression was assessed by immunohistochemistry. Our data predict complete PTEN inactivation in 12 samples (30%), nine of these by bi‐allelic deletion. Loss of one PTEN copy was also detected by several methodologies but the number could not be accurately assessed. Immunohistochemistry indicated the absence of PTEN protein in 15 samples, and heterogeneous expression of the protein in eight tumours. Taken together, these data show that bi‐allelic deletion is a major mechanism of PTEN inactivation in locally progressive prostate cancer. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.