Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 3 uppsatser.

<p>Human papillomavirus type 16 (HPV-16) is the major causative agent of cervical cancer. The life cycle of this oncogenic DNA tumour virus is strictly associated with the differentiation program of the infected epithelial cells. Expression of the viral capsid genes L1 and L2 can only be detected in the terminally differentiated epithelial cells. The studies here focus on the regulation of HPV-16 late gene expression, which is under tight regulation. </p><p>Our experimental system consisted of almost the full length HPV-16 genome driven by a strong CMV promoter. This plasmid and mutants thereof could be transfected into HeLa cells and RNA levels monitored. Using this system, we identified an hnRNP A1-dependent splicing silencer between positions 178 and 226 of the L1 gene. This silencer inhibited the use of the 3' splice site, located immediately upstream of the L1 AUG. We speculate that this splicing silencer plays an essential role in preventing late gene expression at an early stage of the viral life cycle. We subsequently identified a splicing enhancer located in the first 17 nucleotides of L1 that may be needed to counteract the multiple hnRNP A1 dependent splicing silencers in the L1 coding region. A 55kDa protein specifically bound to this splicing enhancer. We also demonstrated that binding of the cellular factors to the splicing silencer in the L1 coding region had an inhibitory effect on expression from L1 cDNA expression plasmids.</p><p>The HPV-16 genome is divided into the early region and the late region, separated by the early poly(A) signal (pAE). pAE is used preferentially early in infection, thereby efficiently blocking late gene expression. We demonstrated that a 57 nucleotide U-rich region of the early 3’untranslated region (3’eUTR) acted as an enhancing upstream element on the usage of pAE. We demonstrated that this U-rich region specifically interacts with hFip1, CstF-64, hnRNP C1/C2 and PTB, suggesting that these factors were either enhancing or regulating polyadenylation at the HPV-16 pAE. </p><p>In conclusion, two regulatory RNA elements that both act to prevent late gene expression at an early stage in the viral life cycle and in proliferating cells were identified: a splicing silencer in the late region and an upstream u-rich element at the pAE.</p>

Human papillomavirus type 16 (HPV-16) is the major causative agent of cervical cancer. The life cycle of this oncogenic DNA tumour virus is strictly associated with the differentiation program of the infected epithelial cells. Expression of the viral capsid genes L1 and L2 can only be detected in the terminally differentiated epithelial cells. The studies here focus on the regulation of HPV-16 late gene expression, which is under tight regulation. Our experimental system consisted of almost the full length HPV-16 genome driven by a strong CMV promoter. This plasmid and mutants thereof could be transfected into HeLa cells and RNA levels monitored. Using this system, we identified an hnRNP A1-dependent splicing silencer between positions 178 and 226 of the L1 gene. This silencer inhibited the use of the 3' splice site, located immediately upstream of the L1 AUG. We speculate that this splicing silencer plays an essential role in preventing late gene expression at an early stage of the viral life cycle. We subsequently identified a splicing enhancer located in the first 17 nucleotides of L1 that may be needed to counteract the multiple hnRNP A1 dependent splicing silencers in the L1 coding region. A 55kDa protein specifically bound to this splicing enhancer. We also demonstrated that binding of the cellular factors to the splicing silencer in the L1 coding region had an inhibitory effect on expression from L1 cDNA expression plasmids. The HPV-16 genome is divided into the early region and the late region, separated by the early poly(A) signal (pAE). pAE is used preferentially early in infection, thereby efficiently blocking late gene expression. We demonstrated that a 57 nucleotide U-rich region of the early 3’untranslated region (3’eUTR) acted as an enhancing upstream element on the usage of pAE. We demonstrated that this U-rich region specifically interacts with hFip1, CstF-64, hnRNP C1/C2 and PTB, suggesting that these factors were either enhancing or regulating polyadenylation at the HPV-16 pAE. In conclusion, two regulatory RNA elements that both act to prevent late gene expression at an early stage in the viral life cycle and in proliferating cells were identified: a splicing silencer in the late region and an upstream u-rich element at the pAE.

Orientadores: Luiz Carlos Zeferino, Silvia Helena Rabelo dos Santos / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-21T17:52:24Z (GMT). No. of bitstreams: 1 D'Ottaviano_MariaGabrielaLoffredo_D.pdf: 1516066 bytes, checksum: 6d0ec9bd4a1234053c224b579db92914 (MD5) Previous issue date: 2012 / Resumo: A infecção pelo HPV é considerada fator etiológico da neoplasia do colo do útero e a integração do HPV DNA ao DNA da célula hospedeira são apontados como passo importante na carcinogênese do epitélio. O melhor conhecimento da infecção do vário tipo de HPV e o status físico do HPV 16 nas NIC 2 pode colaborar na identificação das lesões que teriam maior risco de progredir para NIC 3 e, portanto, deveriam ser consideradas como lesões precursoras do câncer do colo uterino. O objetivo desta série de casos foi descrever a presença dos diferentes tipos de HPV e a integração do HPV DNA 16 em mulheres com diagnóstico histológico de NIC 2 acompanhadas por 12 meses. Trinta e sete mulheres com citologia inicial, resultado de lesão de baixo grau e atípicas de células escamosas de significado indeterminado e NIC 2, confirmado por biópsia, foram seguidas por 12 meses com citologia, colposcopia, tipagem de HPV e determinação do status físico do HPV DNA 16 a cada três meses. A evolução clínica da NIC 2 foi classificada como regressão em 49% (18\37) dos casos, persistência em 22% (8\37) e progressão em 29% (11\37). A infecção por múltiplos tipos de HPV foi observada em 41% (15\37) dos casos na admissão e durante o seguimento 54% (20\37) dos casos apresentaram infecção por novos tipos de HPV. O HPV 16 foi considerado como possível causa em 67% (10\15) dos casos que persistiram ou progrediram e em 10% (1\10) dos que regrediram (p=0,01). Entre as 20 mulheres que apresentaram HPV 16 na admissão, a forma integrada foi detectada em 25% dos casos e a forma episomal em 75% dos casos. Não foram observados casos de progressão para NIC 3 sem integração do HPV DNA 16 em algum momento do seguimento. Entretanto, foram observados casos de integração do HPV DNA 16 e regressão da NIC 2. Concluindo, a infecção por múltiplos tipos de HPV é frequente nas mulheres com diagnóstico histológico de NIC 2, assim como a infecção por outros tipos de HPV durante o seguimento de 12 meses. As NIC 2 associadas à detecção do HPV 16 persistem ou progridem com maior frequência. As NIC 2 que progrediram para NIC 3 apresentaram o HPV DNA 16 na forma integrada na admissão ou em algum momento do seguimento / Abstract: Human papillomavirus (HPV) persistent infection is considered a necessary cause for the development of cervical cancer and HPV DNA integration considered an important step in the progression of persistent high risk HPV infection to invasive cancer.The knowledge of HPV infection and the HPV DNA 16 physical status in women with cervical intraepithelial neoplasia grade 2 (CIN 2) can better characterize the biological behavior of the lesion. This case series aimed to describe the HPV types and HPV DNA 16 physical status in women with CIN 2 biopsy proven followed for 12 months and clinical outcome. Thirty seven women with CIN 2 biopsy proven, cervical referral smear showing low-grade squamous intraepithelial lesions or atypical squamous cells of undetermined significance and with HPV type, were followed up 12 months with cervical smear, colposcopy, HPV type and HVP DNA 16 every three months. At the end of twelve months follow-up, the CIN 2 regression rate was 49% (18/37), persistence as CIN1 or CIN 2 was 22% (8/37), and progression to CIN 3 was 29% (11/37). Multiple HPV types were observed at admission in 41% (15/37) of cases. During follow-up, 54% (20/37) of the women showed one or more new HPV type detected. HPV 16 was considered possibly causal type in 67% (10/15) of the cases that persisted or progressed and in 10% (1/10) that regressed (p=0.01). Among the twenty women with HPV DNA 16, at admission, 25% showed integrated HPV DNA 16 and 75% episomal form. There were no cases of CIN 2 progression to CIN 3 without HPV DNA 16 integration, but there were cases of HPV DNA 16 integration and CIN 2 regression. Concluding, multiple HPV infections were frequently detected among women with CIN 2 at admission and during the follow up. The CIN 2 associated with HPV 16 was more likely to persist or to progress to CIN 3. The HPV DNA 16 integration is associated with CIN 2 persistence and progression to CIN 3 / Doutorado / Oncologia Ginecológica e Mamária / Doutora em Ciências da Saúde

Cervical cancer is the second most common cancer in women worldwide. The principal cause of cervical cancer is infection with human papillomavirus (HPV). HPV-16 is a high-risk virus and it is responsible for a high portion of all HPV-caused cancers. The HPV-16 genome consists of early and late genes. The virus initially infects basal cells of the cervix epithelium and in these cells early genes are expressed, whilst late genes, L1 and L2, are only expressed in the upper cell layers of the epithelium. Proteins encoded by the late genes are highly immunogenic, thus it is speculated that expression of the late genes earlier in the virus life cycle could lead to clearance of the virus due to interference of the immune system.     The aim of this study was to treat reporter cell lines with three different small molecule drugs to see if they had the ability to induce HPV-16 late gene expression. The reporter cell lines used in this study had been previously created by transfecting HeLa-cells with plasmids representing the HPV-16 genome. In these plasmids, L1 is replaced with a CAT reporter gene that encodes the CAT protein, which can be easily quantified using a sandwich ELISA.     Upon treating the reporter cell lines with TPA, a significant induction of late gene expression was detected. Furthermore, treatment with valproic acid showed some induction of late gene expression. In conclusion, TPA and valproic acid was deemed to have potential to act as a candidate drugs for treatment of HPV infections.