Human papilloma virus 16 E7 oncogene does not cooperate with RET/PTC 3 oncogene in the neoplastic transformation of thyroid cells in transgenic mice

ETS family transcription factors collaborate with alternative signaling pathways to induce carcinoma from adult murine prostate cells

Chromosomal rearrangements involving erythroblast transformation specific (ETS) family transcription factors were recently defined as the most common genetic alterations in human prostate cancer. Despite their prevalence, it is unclear what quantitative role they play in either initiation or progression of the disease. Using a lentiviral transduction and dissociated cell prostate regeneration approach, we find that acutely increased expression of ETS proteins in adult murine prostate epithelial cells is sufficient to induce the formation of epithelial hyperplasia and focal prostatic intraepithelial neoplasia (PIN) lesions, but not progression to carcinoma. However, combined expression of ERG with additional genetic alternations associated with human prostate cancer can lead to aggressive disease. Although ERG overexpression does not cooperate with loss of the tumor suppressor p53, it does collaborate with alterations in PI3K signaling, such as Pten knockdown or AKT up-regulation, to produce a well-differentiated adenocarcinoma. Most striking is our finding that overexpression of androgen receptor (AR) does not give rise to any hyperplastic lesions, but when combined with high levels of ERG, it promotes the development of a more poorly differentiated, invasive adenocarcinoma. These findings suggest that in human prostate cancer, the most potent function of ETS gene fusions may be to synergize with alternative genetic events and provide different pathways for carcinoma production and invasive behavior. Our results provide direct evidence for selective cooperating events in ERG-induced prostate tumorigenesis and offer a rational basis for combined therapeutic interventions against multiple oncogenic pathways in prostate cancer.

Human thyroid tumours, the puzzling lessons from E7 and RET/PTC3 transgenic mice

Human rearranged RET/PTC3 (papillary thyroid carcinoma) proto-oncogene and high-risk human papillomavirus (HPV) type 16 E7 oncogene induces in the mouse a neoplastic transformation of thyroid follicular cells. We present a detailed immuno-histological study (170 mouse thyroids: RET/PTC3, E7, wild type, 2- to 10-month-old) with cell cycle proliferation and signalling pathway indicators. The characteristics of both models are different. There is an 'oncogene dependent' cellular signature, maintained at all studied ages in the E7 model, less in the RET/PTC3 model. During tumour development a large heterogeneity occurred in the Tg-RET/PTC3 model within a same tumour or within a same thyroid lobe. The Tg-E7 model was less heterogeneous, with a dominant goitrous pattern. The solid tumour already described in the RET/PTC3 models associated with cribriform patterns, suggested 'PTC spindle cell changes' as in humans PTC rather than the equivalent of the solid human PTC. Proliferation and apoptosis in the two thyroid models are related to the causal oncogene rather than reflect a general tumorigenic process. The thyroids of RET/PTC3 mice appeared as a partial and transient model of human PTCs, whereas the Tg-E7 mice do not belong to the usual PTC type.