Project description:Human papillomavirus (HPV) integration is a critical step in cervical cancer development, while the oncogenic mechanism in genome-wide transcriptional level is still poorly understood. In this study, we employed integrative analysis on multi-omics data of cervical cancer cell lines. Through HPV integration detection, super enhancer (SE) identification, SE-associated gene expression and extrachromosomal DNA (ecDNA) investigation, we aimed to explore the genome-wide transcriptional influence of HPV integration. We identified 5 high-ranking cellular super enhancers generated by HPV integration (the HPV breakpoint induced cellular super enhancers, BP-cSE), leading to intra-chromosomal and inter-chromosomal regulations of chromosomal genes. The pathway analysis showed the dysregulated chromosomal genes were correlated to cervical cancer associated pathways. Importantly, we demonstrated that BP-cSE existed in the HPV-host ecDNA, explaining above transcription alterations. Our results suggest that HPV integration generates cellular super enhancers and functions as ecDNA to regulate unconstraint transcription, expanding the tumorigenic mechanism of HPV integration and providing insights of developing new diagnostic and therapeutic strategies.
Project description:Genomic instability is a hallmark of human cancers, including the 5% caused by human papillomavirus (HPV). Here we report a striking association between HPV integration and adjacent host genomic structural variation in human cancer cell lines and primary tumors. Whole genome sequencing revealed HPV integrants flanking and bridging extensive host genomic amplifications and rearrangements, including deletions, inversions and chromosomal translocations. We present a model of ³looping² by which HPV integrant-mediated DNA replication and recombination may result in viral-host DNA concatemers, frequently disrupting genes involved in oncogenesis and amplifying HPV oncogenes E6 and E7. Our high-resolution results shed new light on a catastrophic process, distinct from chromothripsis and other mutational processes, by which HPV directly promotes genomic instability.
Project description:Human cancer cell lines are the most frequently used preclinical models in the study of cancer biology and the development of therapeutics. Although anatomically diverse, human papillomavirus (HPV)-driven cancers have a common etiology and similar mutations that overlap with but are distinct from those found in HPV-negative cancers. Building on prior studies that have characterized subsets of head and neck squamous cell carcinoma (HNSCC) and cervical squamous cell carcinoma (CESC) cell lines separately, we performed genomic, viral gene expression, and viral integration analyses on 74 cell lines that include all readily-available HPV-positive (9 HNSCC, 8 CESC) and CESC (8 HPV-positive, 2 HPV-negative) cell lines and 55 HPV-negative HNSCC cell lines. We used over 700 human tumors for comparison. Mutation patterns in the cell lines were similar to those of human tumors. We confirmed HPV viral protein and mRNA expression in the HPV-positive cell lines. We found HPV types in three CESC cell lines that are distinct from those previously reported. We found that cell lines and tumors had similar patterns of viral gene expression; there were few sites of recurrent HPV integration. As seen in tumors, HPV integration did appear to alter host gene expression in cell lines. The HPV-positive cell lines had higher levels of p16 and lower levels of Rb protein expression than did the HPV-negative lines. Although the number of HPV-positive cell lines is limited, our results suggest that these cell lines represent suitable models for studying HNSCC and CESC, both of which are common and lethal.
Project description:HPV integrated site capture (HISC) protocol used to detect HPV16 integration breakpoints in the genomes of W12 cell lines. Biotinylated HPV16-specific RNA baits were used to capture HPV16-human breakpoint junctions in genomic DNA.
Project description:Multiple HPV genotypes infection is frequently detected in HPV+ cervical lesions, however it is not well stablished how is the different viral interaction during the carcinogenic process. Here we carried out a comprehensive study to characterize the multiple HPV genome expression and integration by RNA-Seq analysis in 19 invasive cervical carcinomas with HPV coinfections. Analysis of tumoral DNA by a hybridization kit indicated multi-infection ranging from 2 to 6 different HPV genotypes, without a preferential species coinfection. The expression analysis showed that a single HPV genotype preferentially expressed its genome, might indicating a competition between the infecting virus. Finally, the search for HPV/human chimeric transcripts indicated integration from just one HPV in almost all samples, corroborating the expression findings.
Project description:Cervical cancer is the second most common malignancy in women worldwide, with high risk subtypes of human papillomavirus (HPV) constituting the major etiological agent. However, only a small percentage of women infected by the virus develop disease suggesting that additional host genetic alterations are necessary for disease progression. In this study we examined the genomes of a panel of commonly used model cervical cancer cell lines using a recently developed whole genome tiling path array for CGH analysis. Detailed analysis of genomic profiles enabled the detection of many novel aberrations which may have been missed by conventional cytogenetic methods. In total, 27 minimal regions of recurrent copy number alteration were identified that are potentially involved in tumorigenesis. Interestingly, fine mapping of the 3q gain, which is associated with the progression of precursor lesions to invasive cervical cancer, identified a minimal region of alteration harboring genes distinct from previous candidates. Novel regions of gene amplification, including the co-amplification of both the Birc and MMP gene clusters on 11q22, were also evident. Lastly, characterization of genomic structure at sites of HPV integration identified the copy number gain of host cellular sequences between the viral-host genomic boundaries in both SiHa and SW756, suggesting a direct role for HPV integration in the development of genetic abnormalities that initiate cervical cancer. This work represents the highest resolution look at a cervical cancer genome to date and offers definitive characterization of the alteration status of these cancer genomes. Keywords: array CGH, copy number, cervical cancer, genetic alterations, HPV integration, 3q
Project description:ABSTRACT Two major subgroups of head and neck squamous cell carcinomas (HNSCC) are currently distinguished based on etiology and pattern of genetic alterations; tumors with biologically active human papillomavirus (HPV) and tumors without. It is at present unclear whether additional genetically distinct subgroups exist within HPV-negative HNSCC. Aim of this study is to genetically classify HNSCC without HPV involvement and to correlate the genetically defined classes to tumor and patient characteristics. By means of array comparative genomic hybridization (aCGH) we determined DNA copy number variation in thirty-nine HPV-negative, but further unselected HNSCC. Unsupervised analysis of aCGH data distinguished two genetic groups in HPV-negative HNSCC, one characterized by a low level of chromosomal alterations (N=9), and another by a high level of chromosomal alterations (N=30). Absence of chromosomal aberrations was significantly associated with wild-type TP53, a low level of alcohol consumption, a female gender and a better prognosis. The tumors were negative for microsatellite instability. The discovery of this new class of HNSCC with unique genetic and clinical characteristics has important consequences for future basic and clinical studies.
Project description:Oncogenic human papillomavirus (HPV) genomes are often integrated into host chromosomes in HPV-associated cancers. HPV genomes are integrated either as a single copy, or as tandem repeats of viral DNA interspersed with, or without, host DNA. Integration occurs frequently in common fragile sites susceptible to tandem repeat formation, and the flanking or interspersed host DNA often contains transcriptional enhancer elements. When co-amplified with the viral genome, these enhancers can form super-enhancer-like elements that drive high viral oncogene expression. Here, we compiled highly curated datasets of HPV integration sites in cervical (CESC) and head and neck squamous cell carcinoma (HNSCC) cancers and assessed the number of breakpoints, viral transcriptional activity, and host genome copy number at each insertion site. Tumors frequently contained multiple distinct HPV integration sites, but often only one “driver” site that expressed viral RNA. Since common fragile sites and active enhancer elements are cell-type specific, we mapped these regions in cervical cell lines using FANCD2 and Brd4/H3K27ac ChIP-seq, respectively. Large enhancer clusters, or super-enhancers, were also defined using the Brd4/H3K27ac ChIP-seq dataset. HPV integration breakpoints were enriched at both FANCD2-associated fragile sites, and enhancer-rich regions, and frequently showed adjacent focal DNA amplification in CESC samples. We identified recurrent integration “hotspots” that were enriched for super-enhancers, some of which function as regulatory hubs for cell-identity genes. We propose that during persistent infection, extrachromosomal HPV minichromosomes associate with these transcriptional epicenters, and accidental integration could promote viral oncogene expression and carcinogenesis.