Human papilloma virus type 16 E7 genes protect astrocytes against apoptotic and necrotic death induced by hydrogen peroxide

Increased risk of dementia in patients with genital warts: A nationwide cohort study in Taiwan

Genital warts are a common sexually transmitted disease caused by human papillomavirus (HPV) infections. The prevalence of dementia is 4-8% in those aged 65 years or older in Taiwanese community studies, with a high social and economic burden for patients, family caregivers, the community and society. Previous studies have shown that viral infections such as herpes simplex and herpes zoster were associated with dementia. This study aimed to investigate the association between dementia and HPV infections. A population-based cohort study using data from Taiwan's National Health Insurance Research Database was conducted. Fine and Grays's survival analysis was employed to estimate the hazard ratios (HR) and 95% confidence intervals (CI) for the association between genital warts and dementia. From all of the potential participants aged 50 years or more, a total of 16 116 patients were enrolled, including 4029 genital warts-infected patients, with 12 087 sex-, age- and indexed date-matched controls (1:3). The cumulative incidences of dementia were 10.72 per 10³  person-years and 6.43 per 10³  person-years in the genital warts and control group, respectively. There were 475 dementia cases from the genital warts cohort during the follow-up period of 15 years. The adjusted HR for dementia was 1.485 (95% CI, 1.321-1.668; P < 0.001) for genital warts patients after adjusting for all of the covariates. Our study indicates that genital warts infection may increase the risk of dementia.

Protective effect of oxidative stress in HaCaT keratinocytes expressing E7 oncogene

In a previous study, we established a stable cell line which constitutively expresses E7 in HaCaT human keratinocyte cell line and identified various relevant factors including oxygen modulators affected by the E7 oncogene. E7-expressing HaCaT cells (HaCaT/E7) appeared to be more resistant to H2O2-induced cell death. Here, we demonstrate how E7 oncogene would modulate oxidative stress-induced cell death. In addition, we verified the increased expression of catalase in the HaCaT/E7 by Western blot analysis. The results suggest that the E7 oncogene would induce higher resistance to ROS-induced cell injury in the E7-infected cells via the upregulation of catalase. To investigate these paradoxical effects of high concentrations of H2O2 (500 microM-1 mM), we examined their effects on receptor mediated apoptosis, cell death via the mitochondrial pathway and modulation of apoptosis related factors. Our results revealed that HaCaT keratinocytes infected with HPV 16 E7 oncogene modulated expressions of catalase, Bcl-xL, IL-18, Fas, Bad, and cytochrome c as well as NF-kappaB, resulting in the resistance to oxidative stress-induced cell death.

Hydrogen peroxide producing lactobacilli in women with cervical neoplasia

PURPOSE

It is well known that human papillomavirus (HPV) is the main cause of cervical neoplasia, and hydrogen peroxide-producing lactobacilli are the most important microorganisms for maintaining the balance of the vaginal ecosystem. The purpose of our study was to investigate the relationship of hydrogen peroxide-producing lactobacilli, cervical neoplasia and high-risk HPV.

MATERIALS AND METHODS

We enrolled 1138 women with abnormal cervical smears or cervicograms who were referred to the department of Obstetrics and Gynecology at Chonnam National University Medical School. In all of them, 1,138 vaginal swabs were collected for the qualitative assay of hydrogen peroxide producing lactobacilli and 150 cervical swabs were used for the HPV hybrid capture II test without regard to the subjects' pregnancy status. In the non-pregnant women, 880 cervical biopsies and/or loop electrosurgical excision procedures were performed for making the histological diagnosis.

RESULTS

There was no significant difference not only between the distribution of H(2)O(2) producing lactobacilli and the cervical histology, but also between the distribution of H(2)O(2) producing lactobacilli and the positivity for high-risk HPV.

CONCLUSIONS

Both cervical neoplasia and high-risk HPV may not be influenced by the existence of hydrogen peroxide producing lactobacilli in the vagina.

Protein profiling and identification of modulators regulated by human papillomavirus 16 E7 oncogene in HaCaT keratinocytes by proteomics

OBJECTIVES

Viral oncogenes E6 and E7 are selectively retained and expressed in carcinoma cells infected with human papillomavirus type 16 and cooperated with each other in immortalization and transformation of primary keratinocytes. This study was performed to identify proteins to be bound or modulated by high risk HPV E7 oncogene by using a proteomics.

METHODS

HaCaT normal keratinocyte was prepared to establish a stable cell line expressing E7. The E7-affinity column was also prepared to obtain E7-interacting proteins. In order to search the target molecules modulated by E7 expression, we used 2-dimensional electrophoresis and matrix-assisted laser desorption/ionization time of flight (MALDI/TOF) mass spectrometry. Pull down assay was also performed in order to confirm the E7-interacting proteins.

RESULTS

We identified 28 spots that are modulated by E7 in HaCaT/E7 using 2-dimensional electrophoresis (2-DE) and MALDI/TOF mass spectrometry. Proteomics analyses showed that actin and leukocyte elastase inhibitor were down-regulated, whereas stress-induced phosphoprotein 1, CD2 binding protein 1, catalase, T-complex protein 1, Ku70-binding protein, heat shock 60 kDa protein 1, G1/S-specific cyclin E1 and peroxiredoxin 2 were up-regulated. Western blot revealed that heat shock 60 kDa protein, catalase and peroxiredoxin 2 were also up-regulated. Pull down assay also showed that leukocyte elastase inhibitor (LEI) and Ku70-binding protein were bound to the E7 oncoprotein. By using E7-affinity column and 2-DE/MALDI-TOF, 22 spots were found to interact with E7 recombinant protein. MG11-like proteins, livin inhibitor-of-apoptosis, protein serine kinase c17, CD2 binding protein 1, cyclin E1, TATA box binding protein-associated factor and uridine-cytidine kinase 2 were up-regulated by E7 oncogene and also bound to E7 oncoprotein.

CONCLUSIONS

It is presumed that E7 can influence cell status by modulating the factors related to cell signaling, apoptosis and cell cycle regulation.

E7-expressing HaCaT keratinocyte cells are resistant to oxidative stress-induced cell death via the induction of catalase

Cervical carcinoma is one of the most prevalent cancers in women worldwide, and human papillomavirus (HPV) type 16 is the most common agent linked to human cervical carcinoma. In order to identify various relevant factors affected by the E7 oncogene, we established a stable cell line, which constitutively expressed E7 using the HaCaT human keratinocyte cell line. The increased expression and activity of catalase in the E7-expressing HaCaT cells (HaCaT/E7) were verified via matrix-assisted laser desorption/ionization-time of flight, Western blot, and reverse transcription-polymerase chain reaction analyses. The regulation of catalase by E7 was investigated by the detection of catalase promoter activity. E7 enhanced the activities of both the catalase promoter and nuclear factor-kappaB, one of the major transcription factors regulating the expression of the catalase gene. HaCaT/E7 cells produced lower quantities of intracellular reactive oxygen species (ROS), and appeared to be more resistant to H(2)O(2)-induced cell death. Moreover, in order to test the specific effects of E7 on catalase induction, the HaCaT/E7 cells were transiently transfected with E7 antisense vector, resulting in reductions in both the expression and activity of catalase, and a recovery of intracellular ROS levels, thus resulting in recovered sensitivity to H(2)O(2)-induced cell death. These results suggest that the HPV 16 E7 oncogene induces higher resistance to ROS-induced cell injury in the E7-infected cells, probably via the modulation of several anti-oxidant enzymes, including catalase.

Human keratin 14 driven HPV 16 E6/E7 transgenic mice exhibit hyperkeratinosis

Human papillomavirus type 16 (HPV16) has been known as a major causative factor for the development of uterine cervical carcinomas. To investigate the in vivo activity of HPV16 expressed in squamous epithelia, transgenic mice harboring HPV16 E6/E7 with human keratin 14 (hK14) promoter were generated. Grossly, hK14 driven HPV16 E6/E7 transgenic mice exhibited multiple phenotypes, including wrinkled skin that was apparent prior to the appearance of hair in neonates, thickened ears, and loss of hair in adults. Transgenic mice with phenotype exhibiting severe wrinkled skin and a lack of hair growth died at the age of 3-4 weeks. Histological analysis revealed that in transgenic mice survived beyond the initial 3-4 weeks, HPV16 E6/E7 causes epidermal hyperplasia in multiple transgenic lineages with high incidence of transgene penetration. This epithelial hyperplasia was characterized by an expansion of the proliferating compartment and keratinocytes, and was associated with hyperkeratosis. Such activities were significantly higher in the skin of transgenic mice than that of the normal mice. Thus, these transgenic mice appeared to be useful for the expression of HPV16 E6/E7 gene and subsequent analysis on hyperkeratosis.

Apoptosis induced by generated OH radicals inside cells after irradiation

OH radicals play a major role in radiation-induced DNA and cell membrane damage. These types of damage can also induce death by apoptosis through activation of a pro-apoptosis pathway. We attempted to detect OH radicals inside human promyelocytic leukemia (HL60) cells and estimate the relationship between radiation-induced apoptosis and OH radicals generated inside the cells. Electron spin resonance spectroscopy showed that OH radicals were generated by X-rays within irradiated cell pellets and the relative signal intensities of OH radicals increased with the radiation dose. Agarose gel electrophoresis revealed that the death of HL60 cells by apoptosis was accompanied by internucleosomal DNA fragmentation at 2 h after irradiation with 10-30 Gy. On ultrastructure evaluation by transmission electron microscopy, certain irradiated HL60 cells demonstrated condensed chromatin forms at the nuclear membrane and nuclear fragmentation. The frequency of apoptotic cells with condensation and fragmentation of nuclear chromatin increased with radiation dose in semithin sections. The increase of quantitative DNA fragmentation and percentage of non-living cells also correlated with radiation dose. These results suggest that OH radicals are generated inside cells before apoptosis occurs. The amount of OH radicals generated correlates with apoptotic cell death.