A mouse fibroblast cell model to study human papillomavirus-associated tumorigenesis

Cervical cancer represents the second most common cancer in women worldwide. About 90% of cervical cancer contain high-risk human papillomavirus (HPV) DNA, most often HPV type 16. Animal models and mostly laboratory mice are excellent for carrying out diverse immunological studies. We transfected a fibroblast cell line, 3T3-A31, with human papillomavirus type 16 genome to develop an in vivo/in vitro malignant transformant model. Isolated clones inoculated to immunocompetent mice displayed a tumorigenic phenotype. Small clusters of metastatic cells were found in the liver of animal 45 days after receiving the inoculum. Integrated viral DNA and expression of E7 viral oncogene from the high-risk HPV-16 were demonstrated both in transfectans and tumor-derived cells. The observed high-grade neovascularization was correlated with the upregulation of vascular endothelial growth factor (VEGF) mRNA on HPV-16 transformed fibroblast cells. These observations emphasize the association between papillomavirus expression and progression to malignancy.     

Production of human papillomavirus type 16 virions in a keratinocyte cell line.

Human papillomavirus type 16 (HPV-16) is strongly associated with carcinoma of the cervix, but the complete life cycle of the virus cannot be studied because no experimental system is available in which HPV-16 progeny are produced, and there is currently no source of HPV-16 virus particles. Most cell lines that harbor HPV-16 DNA contain the viral genome as integrated or concatenated DNA in which open reading frames are disrupted or deleted, but a human cervical keratinocyte cell line has been described which maintains HPV-16 DNA in monomeric episomal form (M.A. Stanley, H.M. Brown, M.W. Appleby, and A.C. Minson, Int. J. Cancer 43:672-676, 1989). This cell line was induced to form a stratified differentiating epithelium by grafting onto nude mice. Long-term grafts displayed the histological features of a low-grade cervical dysplasia, and terminally differentiated cells contained amplified levels of HPV-16 DNA, virus capsid antigen, and virus particles. This experimental system appears to permit the completion of the HPV-16 life cycle in virus-containing keratinocytes.     

Suppression of HPV-16 late L1 5′-splice site SD3632 by binding of hnRNP D proteins and hnRNP A2/B1 to upstream AUAGUA RNA motifs

Human papillomavirus type 16 (HPV-16) 5′-splice site SD3632 is used exclusively to produce late L1 mRNAs. We identified a 34-nt splicing inhibitory element located immediately upstream of HPV-16 late 5′-splice site SD3632. Two AUAGUA motifs located in these 34 nt inhibited SD3632. Two nucleotide substitutions in each of the HPV-16 specific AUAGUA motifs alleviated splicing inhibition and induced late L1 mRNA production from episomal forms of the HPV-16 genome in primary human keratinocytes. The AUAGUA motifs bind specifically not only to the heterogeneous nuclear RNP (hnRNP) D family of RNA-binding proteins including hnRNP D/AUF, hnRNP DL and hnRNP AB but also to hnRNP A2/B1. Knock-down of these proteins induced HPV-16 late L1 mRNA expression, and overexpression of hnRNP A2/B1, hnRNP AB, hnRNP DL and the two hnRNP D isoforms hnRNP D37 and hnRNP D40 further suppressed L1 mRNA expression. This inhibition may allow HPV-16 to hide from the immune system and establish long-term persistent infections with enhanced risk at progressing to cancer. There is an inverse correlation between expression of hnRNP D proteins and hnRNP A2/B1 and HPV-16 L1 production in the cervical epithelium, as well as in cervical cancer, supporting the conclusion that hnRNP D proteins and A2/B1 inhibit HPV-16 L1 mRNA production.     

Roles of PI3K/Akt and c-Jun Signaling Pathways in Human Papillomavirus Type 16 Oncoprotein-Induced HIF-1α, VEGF,and IL-8 Expression and In Vitro Angiogenesis in Non-Small Cell Lung Cancer Cells

Background and Objectives

Human papillomavirus (HPV)-16 infection may be related to non-smoking associated lung cancer. Our previous studies have found that HPV-16 oncoproteins promoted angiogenesis via enhancing hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and interleukin-8 (IL-8) expression in non-small cell lung cancer (NSCLC) cells. In this study, we further investigated the roles of PI3K/Akt and c-Jun signaling pathways in it.

Methods

Human NSCLC cell lines, A549 and NCI-H460, were stably transfected with pEGFP-16 E6 or E7 plasmids. Western blotting was performed to analyze the expression of HIF-1α, p-Akt, p-P70S6K, p-P85S6K, p-mTOR, p-JNK, and p-c-Jun proteins. VEGF and IL-8 protein secretion and mRNA levels were determined by ELISA and Real-time PCR, respectively. The in vitro angiogenesis was observed by human umbilical vein endothelial cells (HUVECs) tube formation assay. Co-immunoprecipitation was performed to analyze the interaction between c-Jun and HIF-1α.

Results

HPV-16 E6 and E7 oncoproteins promoted the activation of Akt, P70S6K, P85S6K, mTOR, JNK, and c-Jun. {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, a PI3K inhibitor, inhibited HPV-16 oncoprotein-induced activation of Akt, P70S6K, and P85S6K, expression of HIF-1α, VEGF, and IL-8, and in vitro angiogenesis. c-Jun knockdown by specific siRNA abolished HPV-16 oncoprotein-induced HIF-1α, VEGF, and IL-8 expression and in vitro angiogenesis. Additionally, HPV-16 oncoproteins promoted HIF-1α protein stability via blocking proteasome degradation pathway, but c-Jun knockdown abrogated this effect. Furthermore, HPV-16 oncoproteins increased the quantity of c-Jun binding to HIF-1α.

Conclusions

PI3K/Akt signaling pathway and c-Jun are involved in HPV-16 oncoprotein-induced HIF-1α, VEGF, and IL-8 expression and in vitro angiogenesis. Moreover, HPV-16 oncoproteins promoted HIF-1α protein stability possibly through enhancing the interaction between c-Jun and HIF-1α, thus making a contribution to angiogenesis in NSCLC cells.     

The ratio of VEGF/PEDF expression in bone marrow mesenchymal stem cells regulates neovascularization

Angiogenesis, or neovascularization, is a finely balanced process controlled by pro- and anti-angiogenic factors. Vascular endothelial growth factor (VEGF) is a major pro-angiogenic factor, whereas pigment epithelial-derived factor (PEDF) is the most potent natural angiogenesis inhibitor. In this study, the regulatory role of bone marrow stromal cells (BMSCs) during angiogenesis was assessed by the endothelial differentiation potential, VEGF/PEDF production and responses to pro-angiogenic and hypoxic conditions. The in vivo regulation of blood vessel formation by BMSCs was also explored in a SCID mouse model. Results showed that PEDF was expressed more prominently in BMSCs compared to VEGF. This contrasted with human umbilical vein endothelial cells (HUVECs) where the expression of VEGF was higher than that of PEDF. The ratio of VEGF/PEDF gene expression in BMSCs increased when VEGF concentration reached 40ng/ml in the culture medium, but decreased at 80ng/ml. Under CoCl(2)-induced hypoxic conditions, the VEGF/PEDF ratio of BMSCs increased significantly in both normal and angiogenic culture media. There was no expression of endothelial cell markers in BMSCs cultured in either pro-angiogenic or hypoxia culture conditions when compared with HUVECs. The in vivo study showed that VEGF/PEDF expression closely correlated with the degree of neovascularization, and that hypoxia significantly induced pro-angiogenic activity in BMSCs. These results indicate that, rather than being progenitors of endothelial cells, BMSCs play an important role in regulating the neovascularization process, and that the ratio of VEGF and PEDF may, in effect, be an indicator of the pro- or anti-angiogenic activities of BMSCs.     

High prevalence of oncogenic HPV-16 in cervical smears of asymptomatic women of eastern Uttar Pradesh,India: A population-based study

In developing countries like India, occurrence of Human papillomavirus (HPV) in cervical cancer as well as in the asymptomatic population was observed to be very high. Studies on HPV prevalence have been conducted in different parts of the country but no data were available from the eastern region of Uttar Pradesh (UP). The present study aimed to determine the status of HPV prevalence and its association with different socio-demographic factors in this population. Prevalence of HPV was investigated in a total of 2424 cervical scrape samples of asymptomatic women. Primer sets from L1 consensus region of viral genome were used to detect the presence of HPV, and the positive samples were genotyped by sequencing. Univariate binary logistic regression analysis was used to evaluate association of socio-demographic factors with HPV. 9.9% of the clinically asymptomatic women were found to be infected with HPV comprising 26 different genotypes. Among HPV-positive women, 80.8% showed single infection, while 15.4% harboured multiple infections. HPV-16 (63.7%) was the most prevalent, followed by HPV-31 (6.7%), HPV-6 (5.4%), HPV-81 (4.6%) and HPV-33 (4.2%). Significant association of HPV with non-vegetarian diet (P < 0.05) and rural residential areas (P < 0.01) were observed. High prevalence of HPV-16 in asymptomatic women of this population, a frequency comparable to invasive cervical cancers, highlights an urgent need for a therapeutic HPV vaccine covering HPV-16 and other high-risk types to provide protection against the disease.     

Quantitation and mapping of integrated human papillomavirus on human metaphase chromosomes using a fluorescence microscope imaging system.

Integrated human papillomavirus type 16 (HPV-16) DNA was directly visualized on metaphase chromosomes in the two human cervical carcinoma cell lines SiHa and CaSki by fluorescence in situ hybridization with a biotinylated DNA probe (7.9 kb). The fluorescence intensities of hybridization signals from single copies and dispersed clusters of integrated HPV-16 DNA were quantified using a microscope equipped with a cooled-CCD camera that was interfaced to an image processor and host computer. Hybridization signals were localized on chromosomes using separate, registered images of 4',6-diamidino-2-phenylindole (DAPI) or propidium iodide stained metaphase chromosome spreads. In both SiHa and CaSki spreads, a single fluorescein signal was observed on one or both chromatids of chromosome 13, which was identified by simultaneous hybridization with a biotinylated centromere probe specific for chromosomes 13 and 21. Ratios of the distance from 13pter to the HPV-16 signals to the entire chromosome length were approximately 0.63 +/- 0.05 in both SiHa and CaSki cells, indicating the possibility of a common integration domain on chromosome 13. In SiHa cells, no additional signals were observed on other chromosomes. This observation, taken together with literature reports that SiHa cells contain 1 to 2 copies of the HPV-16 genome in this region of chromosome 13, suggests that each fluorescein signal on chromosome 13 represents one equivalent of the HPV-16 genome. The total integrated fluorescence intensity in isolated CaSki metaphase chromosome spreads was approximately two orders of magnitude greater than that of a single copy of HPV-16 DNA in SiHa cells, indicating an increase in HPV-16 copy number.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human Papillomavirus-16 E7 Interacts with Glutathione S-Transferase P1 and Enhances Its Role in Cell Survival

Background

Human Papillomavirus (HPV)-16 is a paradigm for “high-risk” HPVs, the causative agents of virtually all cervical carcinomas. HPV E6 and E7 viral genes are usually expressed in these tumors, suggesting key roles for their gene products, the E6 and E7 oncoproteins, in inducing malignant transformation.

Methodology/Principal Findings

By protein-protein interaction analysis, using mass spectrometry, we identified glutathione S-transferase P1-1 (GSTP1) as a novel cellular partner of the HPV-16 E7 oncoprotein. Following mapping of the region in the HPV-16 E7 sequence that is involved in the interaction, we generated a three-dimensional molecular model of the complex between HPV-16 E7 and GSTP1, and used this to engineer a mutant molecule of HPV-16 E7 with strongly reduced affinity for GSTP1.When expressed in HaCaT human keratinocytes, HPV-16 E7 modified the equilibrium between the oxidized and reduced forms of GSTP1, thereby inhibiting JNK phosphorylation and its ability to induce apoptosis. Using GSTP1-deficient MCF-7 cancer cells and siRNA interference targeting GSTP1 in HaCaT keratinocytes expressing either wild-type or mutant HPV-16 E7, we uncovered a pivotal role for GSTP1 in the pro-survival program elicited by its binding with HPV-16 E7.

Conclusions/Significance

This study provides further evidence of the transforming abilities of this oncoprotein, setting the groundwork for devising unique molecular tools that can both interfere with the interaction between HPV-16 E7 and GSTP1 and minimize the survival of HPV-16 E7-expressing cancer cells.     

TSHR蛋白在宫颈癌的表达及其与HPV-16感染的关系

目的研究促甲状腺激素受体（TSHR）在子宫颈癌组织的表达及其与乳头瘤病毒（HPV－16）的关系。方法应用免疫组织化学链霉菌抗生物素过氧化物酶（SP）法检测79例子宫颈癌和30例子宫颈炎组织HPV－16与TSHR蛋白表达。79例癌症患者中病理分级〈Ⅱ级33例,≥Ⅱ级46例;病理分期〈Ⅱ期56例,≥Ⅱ期23例;无淋巴结转移66例,有淋巴结转移13例;肿瘤大小〈3cm44例,肿瘤大小≥3cm35例。结果HPV－16在子宫颈癌表达率55．70％明显高于宫颈炎5％（P〈0．05）,TSHR在子宫颈癌表达率68．35％明显高于宫颈炎26．67％（P〈0．05）。HPV－16表达与肿瘤的大小、肿瘤分级、分期、淋巴结转移不相关。TSHR表达与肿瘤的大小呈正相关,P〈0．05,与肿瘤分级、分期及淋巴结转移不相关。HPV－16与TSHR在宫颈癌表达呈正相关。结论HPV感染对宫颈癌病变起到强烈的预警作用。TSHR不仅在甲状腺滤泡上皮细胞表达,在子宫颈癌细胞也表达,TSHR过表达能促进宫颈细胞的异常增殖,其异常功能可能是恶性肿瘤特定的临床表型。HPV与TSHR在子宫颈癌变过程中起协同作用。     

Human Tumor Cells Induce Angiogenesis through Positive Feedback between CD147 and Insulin-Like Growth Factor-I

Tumor angiogenesis is a complex process based upon a sequence of interactions between tumor cells and endothelial cells. Previous studies have shown that CD147 was correlated with tumor angiogenesis through increasing tumor cell secretion of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs). In this study, we made a three-dimensional (3D) tumor angiogenesis model using a co-culture system of human hepatocellular carcinoma cells SMMC-7721 and humanumbilical vein endothelial cells (HUVECs) in vitro. We found that CD147-expressing cancer cells could promote HUVECs to form net-like structures resembling the neo-vasculature, whereas the ability of proliferation, migration and tube formation of HUVECs was significantly decreased in tumor conditioned medium (TCM) of SMMC-7721 cells transfected with specific CD147-siRNA. Furthermore, by assaying the change of pro-angiogenic factors in TCM, we found that the inhibition of CD147 expression led to significant decrease of VEGF and insulin-like growth factor-I (IGF-I) secretion. Interestingly, we also found that IGF-I up-regulated the expression of CD147 in both tumor cells and HUVECs. These findings suggest that there is a positive feedback between CD147 and IGF-I at the tumor-endothelial interface and CD147 initiates the formation of an angiogenesis niche.     

Human papillomavirus type 16 DNA cooperates with activated ras in transforming primary cells.

The close association of human papillomavirus type 16 DNA with a majority of cervical carcinomas implies some role for the virus in this type of cancer. To define the transforming properties of HPV-16 DNA in vitro we have now performed transfection experiments on baby rat kidney cells using HPV-16 DNA in conjunction with an activated ras gene. We have demonstrated that a 6.6-kb DNA fragment, containing the early genes of HPV-16 under the control of Moloney murine leukaemia virus long terminal repeats (MoMuLV-LTRs), cooperates with EJ-ras in transforming these cells. Both DNAs are required and neither alone is effective. The cooperating activity appears to reside in a protein or proteins derived from the E6/E7 region of the HPV-16 genome.     

Presence of human papillomavirus genome in human tumor cell lines and cultured cells.

A series of 47 human carcinoma cell lines and their cultured cells were examined for human papillomavirus (HPV) genomes with the use of an HPV detection kit (DNA-RNA hybridization, mixed HPV DNA probe of types 6, 11, 16, 18, 31, 33 and 35). Four of 8 cases of mild dysplasia, 3 of 9 cases of severe dysplasia, 3 of 7 cases of carcinoma in situ, 3 of 15 cases of uterine carcinoma and 5 of 6 cases of condyloma acuminatum were shown to contain the HPV DNA genome in primary cultured cells, while HPV was not detected in the third-passage cells except for the three cases of large cell, nonkeratinizing squamous cell carcinoma. HPV was also not detected in such normal tissues as uterine cervical squamous epithelium, uterine cervical columnar epithelium and endometrium. The presence of HPV DNA genomes was detected consistently in the passages of three lines (SKG-II, HKMUS and HKTUS; large cell nonkeratinizing squamous cell carcinomas of the uterine cervix) with the use of the Southern Blot method (DNA-DNA hybridization, mixed HPV probe of types 6, 11, 16 and 18). HPV type 16 DNA was detected in HKTUS, and HPV type 18 DNA was found in SKG-II and HKMUS. The other 44 cell lines, including ovarian carcinoma, endometrial carcinoma, sarcoma, gastric cancer, pancreatic cancer and rectal cancer, were negative for the HPV-6, HPV-11, HPV-16, HPV-18, HPV-31, HPV-33 and HPV-35 genomes under stringent hybridization conditions.     

宫颈癌中p53表达和病毒感染的研究

应用PCR对121例宫颈脱落细胞和组织分别检测HPV-16／18和HSV-2DNA。同时应用免疫组化S-P法检测76例宫颈组织中P53过度表达。结果发现,宫颈癌组织中HPV-16／18和HSV-2阳性率分别为61．3％和32．3％,慢性宫颈炎组HPV-16／18和HSV-2阳性率分别为22．5％和20．0％,与正常宫颈组比较均有显著性差异。宫颈癌中HPV-16／18和HSV-2混合感染率为16．1％。p53过度表达率在慢性宫颈炎、宫颈上皮内瘤变(CIN)、宫颈癌组织中呈梯度递增。另外,宫颈癌组织中P53过度表达与HPV-16／18、HSV-2的感染无相关性。提示：宫颈癌的发生与HPV-16／18关系密切,HSV-2可能与HPV-16／18协同作用导致宫颈癌的发生。宫颈组织中p53过度表达率与宫颈癌的进程有关,这在宫颈癌的防治方面有一定的临床意义。     

Tobacco Smoke Activates Human Papillomavirus 16 p97 Promoter and Cooperates with High-Risk E6/E7 for Oxidative DNA Damage in Lung Cells

We have previously shown a functional interaction between human papillomavirus type 16 (HPV-16) E6 and E7 oncoproteins and cigarette smoke condensate (CSC) in lung cells suggesting cooperation during carcinogenesis. The molecular mechanisms of such interaction, however, remain to be elucidated. Here we first present evidence showing that cigarette smoke condensate (CSC) has the ability to activate the HPV-16 p97 promoter by acting on the long control region (LCR) in lung epithelial cells. Interestingly, we observed that CSC-induced p97 promoter activation occurs in a dose-dependent manner in both tumor A-549 (lung adenocarcinoma), H-2170 (bronchial carcinoma), SiHa or Hela (cervical carcinoma) cells but not in non-tumor BEAS-2B (bronchial) or NL-20 (alveolar) lung cells unless they ectopically expressed the HPV-16 E6 and E7 oncogenes. In addition, we also observed a significant increase of primary DNA damage in tumor and non-tumor CSC-treated lung cells expressing HPV-16 E6 and E7 oncogenes suggesting a cooperative effect in this process, even though the contribution of E7 was significantly higher. Taken together, our results strongly suggest that tobacco smoke is able to induce the activation of the HPV-16 p97 promoter in cooperation with HPV-16 E6 and E7 oncogenes that, in turn, sensitize lung cells to tobacco smoke-induced DNA damage.