Previous studies on human papillomavirus (HPV) type 16 protein functions have established the oncogenic nature of three viral proteins: E5, E6 and E7. Here we have studied the functions of these proteins by functional deletion of the individual E5, E6 or E7, or both E6 and E7 oncogenes in the context of the whole viral genome. These mutants, or the intact wild-type genome, were expressed from the natural viral promoters along with differentiation of epithelial HaCaT cells in three-dimensional collagen raft cultures. High episomal viral copy numbers were obtained using a transfection-based loxp-HPV16-eGFP-N1 vector system. All epithelial equivalents carrying the different HPV type 16 genomes showed pronounced hyperplastic and dysplastic morphology. Particularly the E7 oncogene, with contribution of E6, was shown to enhance cell proliferation. Specifically, the crucial role of E7 in HPV-associated hyperproliferation was clearly manifested. Based on morphological characteristics, immunohistochemical staining for differentiation and proliferation markers, and low expression of E1^E4, we propose that our raft culture models produce cervical intraepithelial neoplasia (CIN)1 and CIN2-like tissue. Our experimental setting provides an alternative tool to study concerted functions of HPV proteins in the development of epithelial dysplasia.
Abstract. Astrocytomas are intracranial malignancies for which invasive growth and high motility of tumour cells preclude total resection; the tumours usually recur in a more aggressive and, eventually, lethal form. Clinical outcome is highly variable and the accuracy of morphology-based prognostic statements is limited. In order to identify novel molecular markers for prognosis we obtained expression profiles of: i) tumours associated with particularly long recurrence-free intervals, ii) tumours which led to rapid patient death, and iii) tumour-free control brain. Unsupervised data analysis completely separated the three sample entities indicating a strong impact of the selection criteria on general gene expression. Consequently, significant numbers of specifically expressed genes could be identified for each entity. An extended set of tumours was then investigated by RT-PCR targeting 12 selected genes. Data from these experiments were summarised into a sample-specific index which assigns tumours to high-and low-risk groups as successfully as does morphology-based grading. Moreover, this index directly correlates with definite survival suggesting that integrated gene expression data allow individualised prognostic statements. We also analysed localisation of selected marker transcripts by in situ hybridization. Our finding of cell-specificity for some of these outcome-determining genes relates global expression data to the presence of morphological correlates of tumour behaviour and, thus, provides a link between morphology-based and molecular pathology. Our identification of expression signatures that are associated individually with clinical outcome confirms the prognostic relevance of gene expression data and, thus, represents a step towards eventually implementing molecular diagnosis into clinical practice in neuro-oncology.
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