Mycoplasma hominis Causes DNA Damage and Cell Death in Primary Human Keratinocytes.

Mycoplasma hominis can be isolated from the human urogenital tract. However, its interaction with the host remains poorly understood. In this study, we aimed to assess the effects of M. hominis infection on primary human keratinocytes (PHKs). Cells were quantified at different phases of the cell cycle. Proteins involved in cell cycle regulation and apoptosis progression were evaluated. The expression of genes encoding proteins that are associated with the DNA damage response and Toll-like receptor pathways was evaluated, and the cytokines involved in inflammatory responses were quantified. A greater number of keratinocytes were observed in the Sub-G0/G1 phase after infection with M. hominis. In the viable keratinocytes, infection resulted in G2/M-phase arrest; GADD45A expression was increased, as was the expression of proteins such as p53, p27, and p21 and others involved in apoptosis regulation and oxidative stress. In infected PHKs, the expression of genes associated with the Toll-like receptor pathways showed a change, and the production of IFN-γ, interleukin (IL) 1ß, IL-18, IL-6, and tumour necrosis factor alpha increased. The infection of PHKs by M. hominis causes cellular damage that can affect the cell cycle by activating the response pathways to cellular damage, oxidative stress, and Toll-like receptors. Overall, this response culminated in the reduction of cell proliferation/viability in vitro.

ATM Pathway Is Essential for HPV-Positive Human Cervical Cancer-Derived Cell Lines Viability and Proliferation.

Infection with some mucosal human papillomavirus (HPV) types is the etiological cause of cervical cancer and of a significant fraction of vaginal, vulvar, anal, penile, and head and neck carcinomas. DNA repair machinery is essential for both HPV replication and tumor cells survival suggesting that cellular DNA repair machinery may play a dual role in HPV biology and pathogenesis. Here, we silenced genes involved in DNA Repair pathways to identify genes that are essential for the survival of HPV-transformed cells. We identified that inhibition of the ATM/CHK2/BRCA1 axis selectively affects the proliferation of cervical cancer-derived cell lines, without altering normal primary human keratinocytes (PHK) growth. Silencing or chemical inhibition of ATM/CHK2 reduced the clonogenic and proliferative capacity of cervical cancer-derived cells. Using PHK transduced with HPV16 oncogenes we observed that the effect of ATM/CHK2 silencing depends on the expression of the oncogene E6 and on its ability to induce p53 degradation. Our results show that inhibition of components of the ATM/CHK2 signaling axis reduces p53-deficient cells proliferation potential, suggesting the existence of a synthetic lethal association between CHK2 and p53. Altogether, we present evidence that synthetic lethality using ATM/CHK2 inhibitors can be exploited to treat cervical cancer and other HPV-associated tumors.

E6/E7 Functional Differences among Two Natural Human Papillomavirus 18 Variants in Human Keratinocytes.

It is suggested that HPV-18 variants from the A lineage have higher oncogenic potential compared to B variants. Some studies show uneven distribution of HPV-18 variants in cervical adenocarcinomas and squamous cell carcinomas. Regarding HPV-18 variants' functions, the few studies reported focus on E6, and none were performed using natural host cells. Here, we immortalized primary human keratinocytes (PHKs) with E6/E7 of HPV-18 A1 and B1 sublineages and functionally characterized these cells. PHK18A1 reached immortalization significantly faster than PHK18B1 and formed a higher number of colonies in monolayer and 3D cultures. Moreover, PHK18A1 showed greater invasion ability and higher resistance to apoptosis induced by actinomycin-D. Nevertheless, no differences were observed regarding morphology, proliferation after immortalization, migration, or epithelial development in raft cultures. Noteworthy, our study highlights qualitative differences among HPV-18 A1 and B1 immortalized PHKs: in contrast to PHK18A1, which formed more compact colonies and spheroids of firmly grouped cells and tended to invade and migrate as clustered cells, morphologically, PHK18B1 colonies and spheroids were looser, and migration and invasion of single cells were observed. Although these observations may be relevant for the association of these variants with cervical cancer of different histological subtypes, further studies are warranted to elucidate the mechanisms behind these findings.

Long-term single-cell passaging of human iPSC fully supports pluripotency and high-efficient trilineage differentiation capacity.

OBJECTIVES: To establish a straightforward single-cell passaging cultivation method that enables high-quality maintenance of human induced pluripotent stem cells without the appearance of karyotypic abnormalities or loss of pluripotency. METHODS: Cells were kept in culture for over 50 passages, following a structured chronogram of passage and monitoring cell growth by population doubling time calculation and cell confluence. Standard procedures for human induced pluripotent stem cells monitoring as embryonic body formation, karyotyping and pluripotency markers expression were evaluated in order to assess the cellular state in long-term culture. Cells that underwent these tests were then subjected to differentiation into keratinocytes, cardiomyocytes and definitive endoderm to evaluate its differentiation capacity. RESULTS: Human induced pluripotent stem cells clones maintained its pluripotent capability as well as chromosomal integrity and were able to generate derivatives from the three germ layers at high passages by embryoid body formation and high-efficient direct differentiation into keratinocytes, cardiomyocytes and definitive endoderm. CONCLUSIONS: Our findings support the routine of human induced pluripotent stem cells single-cell passaging as a reliable procedure even after long-term cultivation, providing healthy human induced pluripotent stem cells to be used in drug discovery, toxicity, and disease modeling as well as for therapeutic approaches.

Human Papillomavirus 16 E7 Promotes EGFR/PI3K/AKT1/NRF2 Signaling Pathway Contributing to PIR/NF-κB Activation in Oral Cancer Cells.

A subset of oral carcinomas is etiologically related to high-risk human papillomavirus (HR-HPV) infection, with HPV16 being the most frequent HR-HPV type found in these carcinomas. The oncogenic role of HR-HPV is strongly dependent on the overexpression of E6 and E7 oncoproteins, which, in turn, induce p53 and pRb degradation, respectively. Additionally, it has been suggested that HR-HPV oncoproteins are involved in the regulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inducing cancer progression and metastasis. Previously, we reported that HPV16 E7 oncoprotein promotes Pirin upregulation resulting in increased epithelial-mesenchymal transition (EMT) and cell migration, with Pirin being an oxidative stress sensor and activator of NF-κB. In this study, we demonstrate the mechanism by which HPV16 E7-mediated Pirin overexpression occurs by promoting EGFR/PI3K/AKT1/NRF2 signaling, thus causing PIR/NF-κB activation in oral tumor cells. Our results demonstrate a new mechanism by which E7 contributes to oral cancer progression, proposing PIR as a potential new therapeutic target.

Antiviral activity of curcumin-nanoemulsion associated with photodynamic therapy in vulvar cell lines transducing different variants of HPV-16.

Vulvar intraepithelial neoplasia (VIN) is associated with human papillomavirus (HPV) infection. Curcumin is a natural bioactive compound with antineoplastic properties. The use of nanoparticles containing curcumin could allow a better performance of this compound in therapies. So, VIN biopsies were collected and HPV DNA detection was performed by PCR, positive samples were genotyped by Restriction Fragment Length Polymorphism (RFLP) and HPV-16 variants were determined by sequencing. HPV-16 positive vulva carcinoma cells (A431) were transduced with E-P and E-350G HPV-16 E6 variants. The viability of the transduced cells treated with nanoemulsions was determined by MTT assay. Besides, apoptosis was evaluated by enzymatic activity of Caspase-3/7. The cell viability assay showed that both the empty nanoemulsion (NE-V) and the nanoemulsion of curcumin (NE-CUR) had little effect on cell viability as compared to control cells. Additionally, we observed that cells irradiated in the presence of NE-CUR presented 90% of cell death. The apoptosis assay further revealed a significant increase in the activity of caspases 3 and 7 in A431 cells expressing both HPV-16 E6 variants after treatment with NE-CUR. Finally, we submitted the HPV transduced A431 cells to organotypic cultures and observed that the combination of treatments affected tissue architecture with evident signals of tissue damage. We concluded that nanoemulsions attain good biocompatibility, since no cytotoxicity was observed and NE-CUR associated with photoactivation showed promising results, leading to death only in cells subjected to irradiation. This drug delivery system associated with photodynamic therapy may become promising in the treatment of vulva lesions.

HPV-Mediated Resistance to TNF and TRAIL Is Characterized by Global Alterations in Apoptosis Regulatory Factors, Dysregulation of Death Receptors, and Induction of ROS/RNS.

Persistent infection with high-risk human papilloma virus (HR-HPV) is the main risk factor for the development of invasive cervical cancer although is not sufficient to cause cervical cancer. Several host and environmental factors play a key role in cancer initiation/progression, including cytokines and other immune-response mediators. Here, we characterized the response to the individual and combined action of the pro-inflammatory cytokines tumor necrosis factor (TNF) and TNF-related apoptosis-inducing ligand (TRAIL) on HPV-transformed cells and human keratinocytes ectopically expressing E6 and E7 early proteins from different HPV types. We showed that keratinocytes expressing HPV early proteins exhibited global alterations in the expression of proteins involved in apoptosis regulation/execution, including TNF and TRAIL receptors. Besides, we provided evidence that TNF receptor 1 (TNFR1) was down-regulated and may be retained in the cytoplasm of keratinocytes expressing HPV16 oncoproteins. Finally, fluorescence analysis demonstrated that cytokine treatment induced the production and release of reactive oxygen and nitrogen species (ROS/RNS) in cells expressing HPV oncogenes. Alterations in ROS/RNS production and apoptosis regulatory factors expression in response to inflammatory mediators may favor the accumulation of genetic alterations in HPV-infected cells. Altogether, our results suggested that these events may contribute to lesion progression and cancer onset.

Human polyomaviruses and cancer: an overview.

The name of the family Polyomaviridae, derives from the early observation that cells infected with murine polyomavirus induced multiple (poly) tumors (omas) in immunocompromised mice. Subsequent studies showed that many members of this family exhibit the capacity of mediating cell transformation and tumorigenesis in different experimental models. The transformation process mediated by these viruses is driven by viral pleiotropic regulatory proteins called T (tumor) antigens. Similar to other viral oncoproteins T antigens target cellular regulatory factors to favor cell proliferation, immune evasion and downregulation of apoptosis. The first two human polyomaviruses were isolated over 45 years ago. However, recent advances in the DNA sequencing technologies led to the rapid identification of additional twelve new polyomaviruses in different human samples. Many of these viruses establish chronic infections and have been associated with conditions in immunosuppressed individuals, particularly in organ transplant recipients. This has been associated to viral reactivation due to the immunosuppressant therapy applied to these patients. Four polyomaviruses namely, Merkel cell polyomavirus (MCPyV), Trichodysplasia spinulosa polyomavirus (TSPyV), John Cunningham Polyomavirus (JCPyV) and BK polyomavirus (BKPyV) have been associated with the development of specific malignant tumors. However, present evidence only supports the role of MCPyV as a carcinogen to humans. In the present review we present a summarized discussion on the current knowledge concerning the role of MCPyV, TSPyV, JCPyV and BKPyV in human cancers.

Human polyomaviruses and cancer: an overview

The name of the family Polyomaviridae, derives from the early observation that cells infected with murine polyomavirus induced multiple (poly) tumors (omas) in immunocompromised mice. Subsequent studies showed that many members of this family exhibit the capacity of mediating cell transformation and tumorigenesis in different experimental models. The transformation process mediated by these viruses is driven by viral pleiotropic regulatory proteins called T (tumor) antigens. Similar to other viral oncoproteins T antigens target cellular regulatory factors to favor cell proliferation, immune evasion and downregulation of apoptosis. The first two human polyomaviruses were isolated over 45 years ago. However, recent advances in the DNA sequencing technologies led to the rapid identification of additional twelve new polyomaviruses in different human samples. Many of these viruses establish chronic infections and have been associated with conditions in immunosuppressed individuals, particularly in organ transplant recipients. This has been associated to viral reactivation due to the immunosuppressant therapy applied to these patients. Four polyomaviruses namely, Merkel cell polyomavirus (MCPyV), Trichodysplasia spinulosa polyomavirus (TSPyV), John Cunningham Polyomavirus (JCPyV) and BK polyomavirus (BKPyV) have been associated with the development of specific malignant tumors. However, present evidence only supports the role of MCPyV as a carcinogen to humans. In the present review we present a summarized discussion on the current knowledge concerning the role of MCPyV, TSPyV, JCPyV and BKPyV in human cancers.

Co-infection of sexually transmitted pathogens and Human Papillomavirus in cervical samples of women of Brazil.

BACKGROUND: Some sexually transmitted infectious agents, such as Chlamydia trachomatis and Herpes simplex, cause local inflammation, and could contribute to Human Papillomavirus (HPV) and cervical lesion progression. Thus, the aim of this study was to determine any association between the presence of microorganisms of gynecological importance, sexual behavior, clinical and demographical variables to the development and progress of cervical lesions. METHODS: One hundred and thirty-two women between 14 and 78 years and living at Vitória da Conquista, Bahia, Brazil, were included (62 individuals with cervical lesions and 70 without lesions). They answered a questionnaire to provide data for a socioeconomic and sexual activity profile. Samples of cervical swabs were collected and analyzed by PCR to detect genital microorganisms and HPV. Quantitative PCR was used to detect and quantify Ureaplasma urealyticum and Ureaplasma parvum. Univariate and multiple logistic regression were performed to measure the association with the cervical lesions, and an odds ratio (OR) with 95% confidence intervals (95%CI) were calculated. The Mann-Whitney U test was also used to compare the microorganism load in the case and control groups. The significance level was 5% in all hypotheses tested. RESULTS: Cervical lesions were associated with: women in a stable sexual relationship (OR = 14.21, 95%CI = 3.67-55.018), positive PCR for HPV (OR = 16.81, 95%CI = 4.19-67.42), Trichomonas vaginalis (OR = 8.566, 95%CI = 2.04-35.94) and Gardnerella vaginalis (OR = 6.13, 95%CI = 1.53-24.61), adjusted by age and qPCR for U. parvum. U. parvum load showed a statistical difference between the case and control groups (p-value = 0.002). CONCLUSION: Variables such as stable relationship, HPV, T. vaginalis, G. vaginalis were associated with cervical lesions in epidemiological studies. U. parvum load was higher in woman with cervical lesions compared with women without lesions. Additional studies are needed to better understand the role of these factors in cervical lesion development.