Abstract 2727: The three-dimensional nuclear organization of telomeres during endometrial carcinoma development

Abstract

Abstract Our study focuses on the nuclear 3D telomere architecture during development of endometrial carcinoma (EC). EC represents one of the most common gynecological malignancies. The diagnosis of definitive precancerous stages in endometrial tissue is challenging for pathologists. Type I EC develops from precursor glandular hyperplasic lesions followed by architectural tissue alterations. Tumor initiation and progression is accompanied by genetic instability. Loss of the tumor suppressor PTEN was shown to be an early marker for the transformation of glandular hyperplasia in type I EC. Alterations of the nuclear 3D telomere architecture are a sign of genomic instability and occur early in carcinoma development. We are using a heterozygous PTEN mouse model (+/-) to investigate changes in the nuclear 3D telomere organizations during EC development. PTEN+/- mice develop endometrial hyperplasia that progresses into atypical hyperplasia (AH), carcinoma in situ and invasive carcinoma, similar to the observed type-I EC development in humans. We hypothesize that changes in the nuclear 3D telomere architecture precede the development of carcinoma and can be detected prior to morphological evidence for EC. Paraformaldehyde fixed and paraffin embedded uterine tissues from age-matched (1, 7 and 10 months) wildtype (wt) and PTEN+/- mice with AH and EC were stained with hematoxylin and eosin (H&E) for morphological analysis. PTEN expression was detected by immunohistochemistry. We performed 3D telomere fluorescence in-situ hybridization (FISH) using a Cy3-labeled peptide nucleic acid telomere (PNA) probe followed by fluorescence microscopy and quantitative image analysis using TeloViewTM. The number of telomeres, telomere length, telomere aggregates and the position of telomeres in individual nuclei were assessed. PTEN+/- mice at 7 months of age showed extensive lesions of AH with stratified glandular epithelium, increased gland to stroma ratio, and nuclear atypia. At 10 months of age, EC lesions are present with multi-layered cribriform and highly anaplastic epithelium. Wt uterine glandular cells expressed strong PTEN immunoreactivity at 7 and 10 months of age, but PTEN protein expression was reduced in hyperplasic lesions of PTEN+/- mice at 7 months of age and in EC lesions at 10 months of age indicating inactivation of the remaining PTEN allele prior to carcinoma development. Compared to age-matched wt controls, hyperplasic lesions already showed a trend towards shorter telomeres. A high number of short telomeres and an increase in telomeric aggregates were detected in EC lesions. An increased a/c ratio, a means of spatial 3D nuclear telomere distribution, in EC lesions is indicative for a higher proliferation rate. Our ongoing investigation of the 3D telomere organization in younger PTEN +/- mice will determine potential telomere alterations in early hyperplasic lesions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2727. doi:10.1158/1538-7445.AM2011-2727