Imbalance between Actin Isoforms Contributes to Tumour Progression in Taxol-Resistant Triple-Negative Breast Cancer Cells.

The widespread occurrence of breast cancer and its propensity to develop drug resistance highlight the need for a comprehensive understanding of the molecular mechanisms involved. This study investigates the intricate pathways associated with secondary resistance to taxol in triple-negative breast cancer (TNBC) cells, with a particular focus on the changes observed in the cytoplasmic actin isoforms. By studying a taxol-resistant TNBC cell line, we revealed a shift between actin isoforms towards γ-actin predominance, accompanied by increased motility and invasive properties. This was associated with altered tubulin isotype expression and reorganisation of the microtubule system. In addition, we have shown that taxol-resistant TNBC cells underwent epithelial-to-mesenchymal transition (EMT), as evidenced by Twist1-mediated downregulation of E-cadherin expression and increased nuclear translocation of ß-catenin. The RNA profiling analysis revealed that taxol-resistant cells exhibited significantly increased positive regulation of cell migration, hormone response, cell-substrate adhesion, and actin filament-based processes compared with naïve TNBC cells. Notably, taxol-resistant cells exhibited a reduced proliferation rate, which was associated with an increased invasiveness in vitro and in vivo, revealing a complex interplay between proliferative and metastatic potential. This study suggests that prolonged exposure to taxol and acquisition of taxol resistance may lead to pro-metastatic changes in the TNBC cell line.

Comparison of Methods for MicroRNA Isolation from Extracellular Vesicles Obtained from Ascitic Fluids.

Secreted extracellular vesicles (EVs) contain active biomolecules, including miRNAs, composition of which reflects epigenetic changes occurring in cells during pathological processes, in particular, malignant transformation. The accumulated pool of data on the role of EVs in carcinogenesis has stimulated investigations of the EV-derived cancer markers. The most important factor limiting development of this scientific direction is lack of "gold standards" both for methods of EV isolation from biological fluids and for analyzing their molecular content, including composition of miRNAs. Here we first examined efficacy of various methods for small RNA isolation from EVs contained in ascitic fluid for subsequent miRNA analysis. Comparison of different commercial kits showed advantages of the methods based on phenol-chloroform extraction: Total Exosome RNA & Protein Isolation Kit and miRNeasy Serum/Plasma Kit. Analysis of the small RNA transcriptome showed presence of various classes of molecules in the EVs, among which proportion of miRNAs averaged 6% and reaching 10% with the Total Exosome RNA & Protein Isolation Kit. The PureLink miRNA Isolation Kit demonstrated the lowest efficiency. The miRNeasy Advanced Serum/Plasma Kit showed the highest concentration of the small RNA fraction, miRNA proportion of which, however, did not exceed that obtained with the miRNeasy Serum/Plasma Kit and Total Exosome RNA & Protein Isolation Kit. Moreover, RT-PCR analysis of the individual molecules showed lower levels of each of investigated miRNAs (miR-1246, miR-200b-5p, miR-200c-3p, and miR-23a-3p) when using the miRNeasy Advanced Serum/Plasma Kit. In conclusion, Total Exosome RNA & Protein Isolation Kit and miRNeasy Serum/Plasma Kit can be considered as optimal kits in terms of performance based on combination of the studied characteristics, including small RNA concentration, percentage of microRNA according to bioanalyzer and sequencing results, and levels of individual miRNAs detected by RT-PCR.

Detection of Human Papillomavirus Prevalence in Ovarian Cancer by Different Test Systems.

BACKGROUND/AIMS: High-risk human papillomavirus (HPV) infection is associated with different malignancies, but its role in the pathogenesis of ovarian cancer remains inconclusive. Published studies demonstrated a wide variation (0-50%) in HPV prevalence in ovarian cancer. To evaluate the contribution of detection tests to controversial results in different populations, we determined the presence of HPV DNA in Russian ovarian cancer patients using 10 different PCR-based tests. METHODS: Epithelial ovarian adenocarcinomas were tested with 5 general primer sets commonly used for HPV screening of cervical and ovarian cancer and 5 HPV type-specific primers. RESULTS: The use of a single PCR primer set resulted in a wide variation (0-29%) and an underestimation of the incidence of HPV-positive cancers. The combination of MY09/MY11 and GP5+/6+ primers in nested PCR revealed HPV DNA in 53% (18/34) of adenocarcinomas. HPV16 was found in 94% of the HPV-positive cases. In 6/6 positive cases, the active status of HPV16 was demonstrated by RT-PCR detection of E6 and E7 oncogene mRNAs. CONCLUSION: These findings indicate the need to employ multiple PCR-based tests to detect all HPV-positive patients. The identification of viral DNA and oncogene transcripts in cancerous tissues indicate the possible role of HPV in ovarian carcinogenesis in Russia.

Genomic characterization of viral integration sites in HPV-related cancers.

Persistent infection with carcinogenic human papillomaviruses (HPV) causes the majority of anogenital cancers and a subset of head and neck cancers. The HPV genome is frequently found integrated into the host genome of invasive cancers. The mechanisms of how it may promote disease progression are not well understood. Thoroughly characterizing integration events can provide insights into HPV carcinogenesis. Individual studies have reported limited number of integration sites in cell lines and human samples. We performed a systematic review of published integration sites in HPV-related cancers and conducted a pooled analysis to formally test for integration hotspots and genomic features enriched in integration events using data from the Encyclopedia of DNA Elements (ENCODE). Over 1,500 integration sites were reported in the literature, of which 90.8% (N = 1,407) were in human tissues. We found 10 cytobands enriched for integration events, three previously reported ones (3q28, 8q24.21 and 13q22.1) and seven additional ones (2q22.3, 3p14.2, 8q24.22, 14q24.1, 17p11.1, 17q23.1 and 17q23.2). Cervical infections with HPV18 were more likely to have breakpoints in 8q24.21 (p = 7.68 × 10(-4) ) than those with HPV16. Overall, integration sites were more likely to be in gene regions than expected by chance (p = 6.93 × 10(-9) ). They were also significantly closer to CpG regions, fragile sites, transcriptionally active regions and enhancers. Few integration events occurred within 50 Kb of known cervical cancer driver genes. This suggests that HPV integrates in accessible regions of the genome, preferentially genes and enhancers, which may affect the expression of target genes.

p16(INK4a) /Ki-67 co-expression specifically identifies transformed cells in the head and neck region.

p16(INK4a) immunohistochemical overexpression is an overall reliable surrogate marker of human papillomavirus (HPV)-associated head and neck squamous cell carcinomas (HNSCC). However, cases of ambiguous p16(INK4a) overexpression are regularly detected in the head and neck: p16(INK4a) expression can be observed in non-malignant tissue, such as tonsillar crypt epithelium and a proportion of branchial cleft cysts. Additionally, diverse patterns of p16(INK4) expression can complicate interpretation of "p16(INK4a) -positivity". These aspects impede the unrestricted application of p16(INK4a) as a diagnostic marker in the head and neck. We hypothesized that combined detection of p16(INK4a) and the proliferation marker Ki-67 could support clarification of ambiguous p16(INK4a) expression in the head and neck by specifically indicating p16(INK4a) -expressing cells with proliferative activity. p16(INK4a) /Ki-67 co-expression in a combined staining procedure was correlated to distinct p16(INK4a) expression patterns and HPV status (HPV DNA followed by E6*I oncogene mRNA detection) in 147 HNSCC and 50 non-malignant head and neck samples. p16(INK4a) /Ki-67 co-expression only occurred in transformed cells of the head and neck. Co-expression was never detected in non-transformed cells. Combined p16(INK4a) /Ki-67 expression was stringently associated with a diffuse p16(INK4a) expression pattern. All HPV oncogene-expressing HNSCC showed p16(INK4a) /Ki-67 co-expression. We demonstrate that p16(INK4a) /Ki-67 co-expression occurs exclusively in transformed cells of the head and neck. Our findings indicate a substantial impact of combined p16(INK4a) /Ki-67 expression in the assessment of ambiguous p16(INK4a) expression in the head and neck by specifically identifying p16(INK4a) -expressing cells with proliferative activity. This property will be of considerable significance for head and neck histo- and cytopathology.

Methylation status of HPV16 E2-binding sites classifies subtypes of HPV-associated oropharyngeal cancers.

BACKGROUND: The human papillomavirus (HPV) E2 protein is a transcriptional repressor of the oncogenes E6/E7 and loss of E2 function is considered a key step in carcinogenesis. Integration of HPV into the host genome may disrupt the E2 gene. Furthermore, methylation of CpG dinucleotides in E2-binding sites (E2BSs) in the HPV upstream regulatory region may interfere with transcriptional repression of E6 and E7 by E2. The authors hypothesized that the CpG methylation status of E2BS identifies subtypes of HPV type 16 (HPV16)-associated oropharyngeal squamous cell cancers (OPSCC) in association with E2 gene integrity and viral integration. METHODS: Methylation of 10 CpG dinucleotides within the upstream regulatory region, encompassing E2BSs 1, 2, 3, and 4, was quantitatively analyzed by bisulfite pyrosequencing in 57 HPV16-associated OPSCC cases. E2 status was analyzed by gene amplification and quantitative real-time reverse transcriptase-polymerase chain reaction. Viral integration was determined by integration-specific polymerase chain reaction methods. RESULTS: Three subgroups with differential methylation at E2BS3 and E2BS 4 were identified: 1) complete methylation (>80%) associated with the presence of integrated HPV genomes with an intact E2 gene; 2) intermediate methylation levels (20%-80%) with predominantly episomal HPV genomes with intact E2; and 3) no methylation (<20%) with a disrupted E2 gene. Patients with high methylation levels tended to have a worse 5-year overall survival compared with patients with intermediate methylation (hazard ratio, 3.23; 95% confidence interval, 1.13-9.24 [P = .06]). CONCLUSIONS: Methylation of E2BS3 and E2BS4 in OPSCC is associated with E2 integrity and viral physical status. It might explain deregulated viral oncogene expression in the presence of E2. The prognostic significance of E2BS methylation for patients with HPV-associated OPSCC needs to be analyzed further.

Differential methylation of E2 binding sites in episomal and integrated HPV 16 genomes in preinvasive and invasive cervical lesions.

Enhanced expression of the HPV 16 E6-E7 oncogenes may trigger neoplastic transformation of the squamous epithelial cells at the uterine cervix. The HPV E2 protein is a key transcriptional regulator of the E6-E7 genes. It binds to four E2 binding sites (E2BSs 1-4) in the viral upstream regulatory region (URR). Modification of E2 functions, for example, by methylation of E2BSs is hypothesized to trigger enhanced expression of the viral E6-E7 oncogenes. In the majority of HPV-transformed premalignant lesions and about half of cervical carcinomas HPV genomes persist in an extra-chromosomal, episomal state, whereas they are integrated into host cells chromosomes in the remaining lesions. Here we compared the methylation profile of E2BSs 1-4 of the HPV 16 URR in a series of 18 HPV16-positive premalignant lesions and 33 invasive cervical cancers. CpGs within the E2BSs 1, 3, and 4 were higher methylated in all lesions with only episomal HPV16 genomes compared with lesions displaying single integrated copies. Samples with multiple HPV16 integrated copies displayed high methylation levels for all CpGs suggesting that the majority of multiple copies were silenced by extensive methylation. These data support the hypothesis that differential methylation of the E2BSs 1, 3 and 4 is related to the activation of viral oncogene expression in cervical lesions as long as the viral genome remains in the episomal state. Once the virus becomes integrated into host cell chromosomes these methylation patterns may be substantially altered due to complex epigenetic changes of integrated HPV genomes.

Evaluation of cervical cone biopsies for coexpression of p16INK4a and Ki-67 in epithelial cells.

Diffuse overexpression of p16(INK4a) in basal and parabasal cells of cervical epithelium is a hallmark of human papillomavirus-mediated transformation. Focal p16(INK4a) expression is occasionally observed in nondysplastic epithelium. In normal cells, expression of p16(INK4a) triggers cell cycle arrest. However, cells undergoing transformation in intraepithelial lesions actively proliferate. To prove that the different expression patterns of p16(INK4a) , i.e., focal versus diffuse, reflect biologically different entities, we hypothesized that p16(INK4a) -positive cells in epithelia displaying focal p16(INK4a) expression pattern do not coexpress proliferation-associated Ki-67 protein, while p16(INK4a) -positive cells in lesions with diffuse p16(INK4a) expression may do. A total of 138 cervical cone biopsies were stained for the expression of p16(INK4a) and Ki-67 using a primary antibody cocktail. All metaplastic lesions (n = 21) displayed focal staining for p16(INK4a) , and in all of these lesions p16(INK4a) -positive cells were found to be negative for Ki-67 expression. Diffuse expression of p16(INK4a) was observed in 12/21 (57.1%) cervical intraepithelial neoplasia (CIN) 1 lesions, all of them simultaneously showed Ki-67 immunoreactivity in a large proportion of p16(INK4a) -positive cells. Seventeen of 23 (73.9%) CIN2 lesions and all 27 (100%) CIN3/carcinoma in situ (CIS) as well as all 46 (100%) carcinoma cases displayed diffuse and combined expression of p16(INK4a) and Ki-67. Coexpression of Ki-67 and p16(INK4a) in the same cell is entirely restricted to cervical lesions displaying diffuse p16(INK4a) expression, whereas in lesions with focal p16(INK4a) expression, p16(INK4a) -expressing cells are negative for Ki-67. Thus, diffuse expression of p16(INK4a) reflects lesions with proliferation-competent cells, while p16(INK4a) -expressing cells associated with focal expression patterns are cell cycle arrested.

Extracellular Vesicles from Uterine Aspirates Represent a Promising Source for Screening Markers of Gynecologic Cancers.

Extracellular vesicles (EVs), including exosomes, are key factors of intercellular communication, performing both local and distant transfers of bioactive molecules. The increasingly obvious role of EVs in carcinogenesis, similarity of molecular signatures with parental cells, precise selection and high stability of cargo molecules make exosomes a promising source of liquid biopsy markers for cancer diagnosis. The uterine cavity fluid, unlike blood, urine and other body fluids commonly used to study EVs, is of local origin and therefore enriched in EVs secreted by cells of the female reproductive tract. Here, we show that EVs, including those corresponding to exosomes, could be isolated from individual samples of uterine aspirates (UA) obtained from epithelial ovarian cancer (EOC) patients and healthy donors using the ultracentrifugation technique. First, the conducted profiling of small RNAs (small RNA-seq) from UA-derived EVs demonstrated the presence of non-coding RNA molecules belonging to various classes. The analysis of the miRNA content in EVs from UA performed on a pilot sample revealed significant differences in the expression levels of a number of miRNAs in EVs obtained from EOC patients compared to healthy individuals. The results open up prospects for using UA-derived EVs as a source of markers for the diagnostics of gynecological cancers, including EOC.

Isolation and Characterization of Extracellular Vesicles from Gastric Juice.

EVs are involved in local and distant intercellular communication and play a vital role in cancer development. Since EVs have been found in almost all body fluids, there are currently active attempts for their application in liquid diagnostics. Blood is the most commonly used source of EVs for the screening of cancer markers, although the percentage of tumor-derived EVs in the blood is extremely low. In contrast, GJ, as a local biofluid, is expected to be enriched with GC-associated EVs. However, EVs from GJ have never been applied for the screening and are underinvestigated overall. Here we show that EVs can be isolated from GJ by ultracentrifugation. TEM analysis showed high heterogeneity of GJ-derived EVs, including those with exosome-like size and morphology. In addition to morphological diversity, EVs from individual GJ samples differed in the composition of exosomal markers. We also show the presence of stomatin within GJ-derived EVs for the first time. The first conducted comparison of miRNA content in EVs from GC patients and healthy donors performed using a pilot sampling revealed the significant differences in several miRNAs (-135b-3p, -199a-3p, -451a). These results demonstrate the feasibility of the application of GJ-derived EVs for screening for miRNA GC markers.

Comprehensive analysis of 130 multicentric intraepithelial female lower genital tract lesions by HPV typing and p16 expression profile.

PURPOSE: HPV associated cervical transformation is characterized by well-defined steps, including persistent HPV infection and deregulated oncogene expression. Recent studies have suggested that a number of lower genital tract lesions are clonally related to cervical lesions. In the current study, HPV infections and oncogene expression were assessed in a large series of patients with multicentric lower genital tract disease to analyze the transformation steps in extracervical disease. METHODS: One hundred and thirty biopsies of 52 women treated for multicentric synchronous or metachronous lower genital tract intraepithelial neoplasias were collected. Up to seven multicentric specimens taken from one patient were studied with a maximum follow up of 20 years. HPV typing and p16(ink4a) immunostaining was performed. RESULTS: HPV DNA was present in 121 of 130 specimens (93%). HPV16 was frequently found in VIN, VaIN and AIN (73, 60 and 77%, respectively), whereas only 37% of CIN were HPV16 positive. Infections with identical HPV types in multicentric lesions were diagnosed in 46% of the HPV positive patients. p16INK4a expression was negative in the nine HPV negative lesions whereas about 90% of the high grade lesions showed diffuse p16 staining. CONCLUSION: Our findings indicate that multicentric lower genital tract disease evolves through different pathways. Some cases were related to a high susceptibility towards HPV infections, while others exhibited features of clonal propagation of transformed cervical cell clones. The clinical management of the latter group is particularly challenging, because malignant cell clones can persist over a long time course.

Epigenetics of Virus-Induced Tumors: Perspectives for Therapeutic Targeting.

About 15-20% of human cancers worldwide have viral etiology. Seven human DNA and RNA viruses are accepted to be oncogenic viruses or oncoviruses and contribute to the development of various cancer types. Human oncoviruses have developed multiple molecular mechanisms to interfere with specific cellular pathways to promote viral replication and viral life cycle maintenance in the host. Despite the diversity of oncogenic viruses, they use similar strategies for cancer development. Viral oncoproteins and viral non-coding RNAs are the key factors that can affect multiple cellular processes on both genetic and epigenetic levels. Epigenetics research allows better understanding of the complex interplay between oncoviruses and the host cells. This review highlights the importance of epigenetic reprogramming for virus-induced carcinogenesis. Recent progress in the development of pharmacological tools for targeting epigenetic mechanisms opens new perspectives for modulation of virus/host interaction and intervention of virus-induced cancer. Several clinical trials have been carried out or are on-going involving epigenetic drugs not only as single therapeutic but also in combination with other targeted agents against various virus-induced cancers.

5-aza-2'-deoxycytidine (DAC) treatment downregulates the HPV E6 and E7 oncogene expression and blocks neoplastic growth of HPV-associated cancer cells.

High-risk human papillomaviruses (hr HPVs) may cause various human cancers and associated premalignant lesions. Transformation of the host cells is triggered by overexpression of the viral oncogenes E6 and E7 that deregulate the cell cycle and induce chromosomal instability. This process is accompanied by hypermethylation of distinct CpG sites resulting in silencing of tumor suppressor genes, inhibition of the viral E2 mediated control of E6 and E7 transcription as well as deregulated expression of host cell microRNAs. Therefore, we hypothesized that treatment with demethylating agents might restore those regulatory mechanisms. Here we show that treatment with 5-aza-2'-deoxycytidine (DAC) strongly decreases the expression of E6 and E7 in a panel of HPV-transformed cervical cancer and head and neck squamous cell carcinoma cell lines. Reduction of E6 and E7 further resulted in increased target protein levels including p53 and p21 reducing the proliferation rates and colony formation abilities of the treated cell lines. Moreover, DAC treatment led to enhanced expression of tumor the suppressive miRNA-375 that targets and degrades E6 and E7 transcripts. Therefore, we suggest that DAC treatment of HPV-associated cancers and respective precursor lesions may constitute a targeted approach to subvert HPV oncogene functions that deserves testing in clinical trials.

Systematic review of genomic integration sites of human papillomavirus genomes in epithelial dysplasia and invasive cancer of the female lower genital tract.

Cancers of the anogenital tract as well as some head and neck cancers are caused by persistent infections with high-risk type human papillomaviruses (HPVs). Two viral oncogenes, E6 and E7, induce severe chromosomal instability associated with centrosome aberrations, anaphase bridges, chromosome lagging, and breaking. This occurs early in preneoplastic lesions, when the viral genome still persists in an episomal state. In most invasive cancers and also in a few high-grade dysplastic lesions, however, integration of high-risk HPV genomes into the host genome is observed. Integration seems to be a direct consequence of chromosomal instability and an important molecular event in the progression of preneoplastic lesions. Disruption or deregulation of defined critical cellular gene functions by insertional mutagenesis by integrated HPV genome fragments has been hypothesized as one major promoting factor in the pathogenesis of HPV-associated cancers. This hypothesis was based on the detection of HPV integration events in the area of tumor-relevant genes in few cases. Here, we reviewed >190 reported integration loci with respect to changes in the viral structure and the targeted genomic locus. This analysis confirms that HPV integration sites are randomly distributed over the whole genome with a clear predilection for genomic fragile sites. No evidence for targeted disruption or functional alteration of critical cellular genes by the integrated viral sequences could be found.

Human papillomavirus types 16 E1 mRNA is transcribed from P14 early promoter in cervical neoplasms.

High-risk human papillomavirus (HR-HPV) persistent infection is responsible for the development of the majority of cervical cancers. The therapy against HPV-associated cancer requires knowledge of the viral gene expression mechanisms. In this study, the polyadenylated polycistronic transcripts containing full-size E1ORF and produced from the early P14 promoter were detected for the first time in cervical tumors with episomal forms of the HPV16 genome. P14-initiated mRNAs were revealed also in precancerous lesions. The amount of P14-initiated transcripts was significantly less compared to transcripts initiated from the major P97 HPV16 promoter in cervical intraepithelial neoplasms and squamous cell carcinomas. The ratios of P97/P14-transcripts determined by qRT-PCR were unique for each clinical sample and varied in quite wide ranges independent of disease progression stages or tumor grade. These data suggest that the levels of P14- and P97-transcripts are regulated independently from each other in cervical neoplasms.

Characterization of viral-cellular fusion transcripts in a large series of HPV16 and 18 positive anogenital lesions.

Persistent high risk type human papillomavirus (HR-HPVs) infections induce dysplasia or cancer of the anogenital tract, most notably of the uterine cervix. The viral genome usually persists and replicates as an episomal molecule in early dysplasia, whereas in advanced dysplasia or cervical cancer HPV genomes are frequently integrated into the chromosomal DNA of the host cell. Previous studies suggested that modification of critical cellular sequences by integration of HPV genomes might significantly contribute to the neoplastic transformation of anogenital epithelia (insertional mutagenesis). This prompted us to characterize the integration loci of high risk HPV genomes in a large set of genital lesions. We amplified E6/E7 oncogene transcripts derived from integrated HPV16 and HPV18 genomes and characterized in detail the co-transcribed cellular sequences of 64 primary genital lesions and five cervical cancer cell lines. Database analyses of the cellular parts of these fusion transcripts revealed 51 different integration loci, including 26 transcribed genes (14 known genes, 12 EST sequences with unknown gene function). Seventeen sequences showed similarity to repetitive elements, and 26 sequences did not show any database match other than genomic sequence. Chromosomal integration loci were distributed over almost all human chromosomes. Although we found HPV sequences integrated into cancer related genes and close to fragile sites, no preferential site or integration motif could be identified. These data demonstrate that target directed insertional mutagenesis might occur in few HPV-induced anogenital lesions, however, it is rather the exception than the rule.

A comprehensive analysis of HPV integration loci in anogenital lesions combining transcript and genome-based amplification techniques.

Persistent infections with high-risk human papillomaviruses (HPVs) induce dysplastic lesions of the lower genital tract. Some of these lesions eventually progress to invasive cancers, particularly of the uterine cervix. In many advanced preneoplastic cervical lesions and most derived carcinomas, HPV genomes are found to be integrated into the host cell chromosomes. Although HPV integration seems to play an important role in the progression of cervical dysplasia, the underlying mechanisms are still unclear. To investigate the pathogenic role of genomic integration of HPV genomes in greater detail, we analysed integration sites of HPV16 and 18 genomes in 21 anogenital precancerous and cancerous lesions using a ligation-mediated chain reaction (DIPS) and the recently described amplification of papilloma virus oncogene transcripts (APOT) assay. On the genomic level, only singular integration events were observed in individual neoplastic cell clones. At many integration sites, a short overlap between HPV and genomic sequences was observed, suggesting that the integration of HPV genomes is mediated by nonhomologous sequence-specific recombination. APOT analysis revealed that the majority of integrated HPV genomes was actively transcribed. These data suggest that in the progression of cervical preneoplasia to invasive carcinomas, integration of viral genomes occurs only at single or few chromosomal loci in a given cell clone. Disruption of cellular genes might support malignant transformation in rare cases; however, it is not a pathogenic prerequisite. The main function of HPV integration seems to be the stabilization of oncogene transcription.

DNA aneuploidy and integration of human papillomavirus type 16 e6/e7 oncogenes in intraepithelial neoplasia and invasive squamous cell carcinoma of the cervix uteri.

PURPOSE: Increasingly deregulated expression of the E6-E7 oncogenes of high-risk human papillomaviruses (HR-HPVs) has been identified as the major transforming factor in the pathogenesis of cervical dysplasia and derived cancers. The expression of these genes in epithelial stem cells first results in chromosomal instability and induces chromosomal aneuploidy. It is speculated that this subsequently favors integration of HR-HPV genomes into cellular chromosomes. This in turn leads to expression of viral cellular fusion transcripts and further enhanced expression of the E6-E7 oncoproteins. Chromosomal instability and aneuploidization thus seems to precede and favor integration of HR-HPV genomes. EXPERIMENTAL DESIGN: To prove this sequential concept, we analyzed here the sequence of events of DNA aneuploidization and integration in a series of HPV-16-positive cervical dysplastic lesions and carcinomas. Eighty-five punch biopsies of HPV-16-positive cervical lesions (20 CIN1/2, 50 CIN3, and 15 CxCa) were analyzed for DNA ploidy by DNA flow cytometry and for integration of HPV E6/E7 oncogenes using the amplification of papillomavirus oncogene transcripts assay, a reverse transcription-PCR method to detect integrate-derived human papillomavirus oncogene transcripts. RESULTS: DNA aneuploidy and viral genome integration were both associated with increasing dysplasia (P < 0.001, chi(2) test for trend). In addition, DNA aneuploidy was associated with increased viral integration (P < 0.01, Fisher's exact test). Nineteen of 20 (95%) lesions with integrated viral genomes had aneuploid cell lines; however, only 19 of 32 (59%) lesions with aneuploid cell lines had integrated viral genomes. CONCLUSIONS: These data support the hypothesis that aneuploidization precedes integration of HR-HPV genomes in the progression of cervical dysplasia. Accordingly, deregulated viral oncogene expression appears to result first in chromosomal instability and aneuploidization and is subsequently followed by integration of HR-HPV genomes in the affected cell clones.

Analysis of p16INK4a and integrated HPV genomes as progression markers.

Most cervical cancers are preventable when the precursor lesions are detected in time. Human papilloma viruses (HPVs) are the main risk factors for cervical cancer development, but there is a high percentage of healthy women infected with HPV that never develop a lesion. Only a small percentage of low-grade dysplasias finally grow out to invasive cancer. Several biomarkers can be used to identify lesions at risk for malignant progression. Overexpression of p16INK4a is induced by the viral oncoprotein E7 and distinguishes dysplastic lesions from benign changes. Integration of human papillomavirus DNA into the host genome is mainly found in high-grade dysplastic lesions and invasive cancers, and points to an increased progression potential.