A recent report that 93 per cent of invasive cervical cancers worldwide contain human papillomavirus (HPV) may be an underestimate, due to sample inadequacy or integration events affecting the HPV L1 gene, which is the target of the polymerase chain reaction (PCR)-based test which was used. The formerly HPV-negative cases from this study have therefore been reanalyzed for HPV serum antibodies and HPV DNA. Serology for HPV 16 VLPs, E6, and E7 antibodies was performed on 49 of the 66 cases which were HPV-negative and a sample of 48 of the 866 cases which were HPV-positive in the original study. Moreover, 55 of the 66 formerly HPV-negative biopsies were also reanalyzed by a sandwich procedure in which the outer sections in a series of sections are used for histological review, while the inner sections are assayed by three different HPV PCR assays targeting different open reading frames (ORFs). No significant difference was found in serology for HPV 16 proteins between the cases that were originally HPV PCR-negative and -positive. Type-specific E7 PCR for 14 high-risk HPV types detected HPV DNA in 38 (69 per cent) of the 55 originally HPV-negative and amplifiable specimens. The HPV types detected were 16, 18, 31, 33, 39, 45, 52, and 58. Two (4 per cent) additional cases were only HPV DNA-positive by E1 and/or L1 consensus PCR. Histological analysis of the 55 specimens revealed that 21 were qualitatively inadequate. Only two of the 34 adequate samples were HPV-negative on all PCR tests, as against 13 of the 21 that were inadequate ( p< 0.001). Combining the data from this and the previous study and excluding inadequate specimens, the worldwide HPV prevalence in cervical carcinomas is 99.7 per cent. The presence of HPV in virtually all cervical cancers implies the highest worldwide attributable fraction so far reported for a specific cause of any major human cancer. The extreme rarity of HPV-negative cancers reinforces the rationale for HPV testing in addition to, or even instead of, cervical cytology in routine cervical screening.

Human papillomavirus is a necessary cause of invasive cervical cancer worldwide.

The causal role of human papillomavirus infections in cervical cancer has been documented beyond reasonable doubt. The association is present in virtually all cervical cancer cases worldwide. It is the right time for medical societies and public health regulators to consider this evidence and to define its preventive and clinical implications. A comprehensive review of key studies and results is presented.

https://jcp.bmj.com/content/jclinpath/55/4/244.full.pdf

The causal relation between human papillomavirus and cervical cancer

The objectives of this study were to determine whether differences in the size and composition of coarse (2.5-10 micro m), fine (< 2.5 microm), and ultrafine (< 0.1 microm) particulate matter (PM) are related to their uptake in macrophages and epithelial cells and their ability to induce oxidative stress. The premise for this study is the increasing awareness that various PM components induce pulmonary inflammation through the generation of oxidative stress. Coarse, fine, and ultrafine particles (UFPs) were collected by ambient particle concentrators in the Los Angeles basin in California and used to study their chemical composition in parallel with assays for generation of reactive oxygen species (ROS) and ability to induce oxidative stress in macrophages and epithelial cells. UFPs were most potent toward inducing cellular heme oxygenase-1 (HO-1) expression and depleting intracellular glutathione. HO-1 expression, a sensitive marker for oxidative stress, is directly correlated with the high organic carbon and polycyclic aromatic hydrocarbon (PAH) content of UFPs. The dithiothreitol (DTT) assay, a quantitative measure of in vitro ROS formation, was correlated with PAH content and HO-1 expression. UFPs also had the highest ROS activity in the DTT assay. Because the small size of UFPs allows better tissue penetration, we used electron microscopy to study subcellular localization. UFPs and, to a lesser extent, fine particles, localize in mitochondria, where they induce major structural damage. This may contribute to oxidative stress. Our studies demonstrate that the increased biological potency of UFPs is related to the content of redox cycling organic chemicals and their ability to damage mitochondria.

/pdf/ultrafine-particulate-pollutants-induce-oxidative-stress-and-162cjtujkl.pdf

Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage.

The early human papillomavirus type 16 genes that directly participate in the in vitro transformation of primary human keratinocytes have been defined. In the context of the full viral genome, mutations in either the E6 or E7 open reading frame completely abrogated transformation of these cells. Mutations in the E1, E2, and E2-E4 open reading frames, on the other hand, had no effect. Thus, both the full-length E6 and E7 genes were required for the induction of keratinocyte immortalization and resistance to terminal differentiation. The E6 and E7 genes expressed together from the human beta-actin promoter were sufficient for this transformation; mutation of either gene in the context of this recombinant plasmid eliminated the ability to induce stable differentiation-resistant transformants.

https://jvi.asm.org/content/jvi/63/10/4417.full.pdf

The E6 and E7 genes of the human papillomavirus type 16 together are necessary and sufficient for transformation of primary human keratinocytes.

Epidemiology of Genital Human Papillomavirus Infection

Summary Cloned DNA from human papillomavirus (HPV) type 16 was subjected to restriction enzyme analysis. A genome size of 7.8 ± 0.1 kb was determined and restriction maps were prepared. Fragments of HPV 16 DNA were nick-translated and hybridized with fragments of HPV 6b DNA. The two genomes appeared to be colinear. The physical state of HPV 16 DNA in genital tumours was analysed. In each of six benign tumours the viral DNA was detected exclusively as 8 kb circles. In four malignant tumours the viral DNA appeared to be integrated within the host genome but one cervical carcinoma and one case of Bowen's disease also contained oligomeric episomal molecules of viral DNA. One cervical carcinoma (WV 2965), containing only integrated viral DNA, was examined in detail. HPV 16 DNA was integrated as head-to-tail tandem repeats at more than one site. Three virus/cell junction fragments from this tumour were cloned. Two contained lengths of repetitive cellular DNA and one a length of apparently single copy cellular DNA.

The physical state of human papillomavirus type 16 DNA in benign and malignant genital tumours.

In order to evaluate the influence of pregnancy on the presence of human papillomavirus (HPV) in the lower female genital tract, cervical smears of 92 pregnant and 96 non-pregnant women, matched by age, were examined for the presence of HPV-DNA by means of Southern blot hybridization. All patients had negative PAP smears. Twenty-six (28%) of the pregnant women and 12 (12.5%) of the non-pregnant women were positive for HPV. HPV 16 accounted for 42% of all positive pregnant cases and only 25% of the positive non-pregnant cases. Smears of pregnant patients contained more than 10 pg viral DNA in 45% of the cases against 20% in the non-pregnant group. HPV 16 showed the most active replication in both groups. This study demonstrates an increased prevalence of HPV (preferentially of HPV 16) and a higher replication rate of viral DNA during pregnancy.

Marlies Hotz

Papers

The physical state of human papillomavirus type 16 DNA in benign and malignant genital tumours.

Increased prevalence of human papillomaviruses in the lower genital tract of pregnant women