Infectious Agents Associated with Head and Neck Carcinomas

The Role of Oncogenic Viruses in Head and Neck Cancers: Epidemiology, Pathogenesis, and Advancements in Detection Methods

Head and neck cancers (HNCs) constitute a wide range of malignancies originating from the epithelial lining of the upper aerodigestive tract, including the oral cavity, pharynx, larynx, nasal cavity, paranasal sinuses, and salivary glands. Although lymphomas affecting this region are not conventionally classified as HNCs, they may occur in lymph nodes or mucosa-associated lymphoid tissues within the head and neck. Oncogenic viruses play a crucial role in HNC onset. Human papillomavirus (HPV) is extensively studied for its association with oropharyngeal cancers; nevertheless, other oncogenic viruses also contribute to HNC development. This review provides an overview of the epidemiology, pathogenesis, and advancements in detection methods of oncogenic viruses associated with HNCs, recognizing HPV's well-established role while exploring additional viral connections. Notably, Epstein-Barr virus is linked to nasopharyngeal carcinoma and lymphomas. Human herpesvirus 8 is implicated in Kaposi's sarcoma, and Merkel cell polyomavirus is associated with subsets of HNCs. Additionally, hepatitis viruses are examined for their potential association with HNCs. Understanding the viral contributions in the head and neck area is critical for refining therapeutic approaches. This review underlines the interaction between viruses and malignancies in this region, highlighting the necessity for ongoing research to elucidate additional mechanisms and enhance clinical outcomes.

Assessment of Concentration KRT6 Proteins in Tumor and Matching Surgical Margin from Patients with Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinomas (HNSCCs) are one of the most frequently detected cancers in the world; not all mechanisms related to the expression of keratin in this type of cancer are known. The aim of this study was to evaluate type II cytokeratins (KRT): KRT6A, KRT6B, and KRT6C protein concentrations in 54 tumor and margin samples of head and neck squamous cell carcinoma (HNSCC). Moreover, we examined a possible association between protein concentration and the clinical and demographic variables. Protein concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Significantly higher KRT6A protein concentration was found in HNSCC samples compared to surgical margins. An inverse relationship was observed for KRT6B and KRT6C proteins. We showed an association between the KRT6C protein level and clinical parameters T and N in tumor and margin samples. When analyzing the effect of smoking and drinking on KRT6A, KRT6B, and KRT6C levels, we demonstrated a statistically significant difference between regular or occasional tobacco and alcohol habits and patients who do not have any tobacco and alcohol habits in tumor and margin samples. Moreover, we found an association between KRT6B and KRT6C concentration and proliferative index Ki-67 and HPV status in tumor samples. Our results showed that concentrations of KRT6s were different in the tumor and the margin samples and varied in relation to clinical and demographic parameters. We add information to the current knowledge about the role of KRT6s isoforms in HNSCC. We speculate that variations in the studied isoforms of the KRT6 protein could be due to the presence and development of the tumor and its microenvironment. It is important to note that the analyses were performed in tumor and surgical margins and can provide more accurate information on the function in normal and cancer cells and regulation in response to various factors.

Comparative analysis of microbial composition and functional characteristics in dental plaque and saliva of oral cancer patients

BACKGROUND

The oral cavity is home to various ecological niches, each with its own unique microbial composition. Understanding the microbial communities and gene composition in different ecological niches within the oral cavity of oral cancer (OC) patients is crucial for determining how these microbial populations contribute to disease progression.

METHODS

In this study, saliva and dental plaque samples were collected from patients with OC. Metagenomic sequencing was employed to analyze the microbial community classification and functional composition of the different sample groups.

RESULTS

The results of the study revealed significant differences in both the function and classification of microbial communities between saliva and dental plaque samples. The diversity of microbial species in saliva was found to be higher compared to  that in plaque samples. Notably, Actinobacteria were enriched in the dental plaque of OC patients. Furthermore, the study identified several inter-group differential marker species, including Prevotella intermedia, Haemophilus parahaemolyticus, Actinomyces radius, Corynebacterium matruchitii, and Veillonella atypica. Additionally, 1,353 differential genes were annotated into 23 functional pathways. Interestingly, a significant correlation was observed between differentially labeled species and Herpes simplex virus 1 (HSV-1) infection, which may be related to the occurrence and development of cancer.

CONCLUSIONS

Significant differences in the microbial and genetic composition of saliva and dental plaque samples were observed in OC patients. Furthermore, pathogenic bacteria associated with oral diseases were predominantly enriched in saliva. The identification of inter-group differential biomarkers and pathways provide insights into the relationship between oral microbiota and the occurrence and development of OC.

Detection of herpes simplex virus in oral tongue squamous cell carcinoma

Introduction: Oral tongue squamous cell carcinoma (OTSCC) is the most common cancer of the oral cavity. Contradictory results have been observed on the involvement of herpes simplex virus 1 (HSV-1) in oral squamous cell carcinomas. Here, we aimed to study the predominance of HSV-1 or HSV-2 in oral HSV infections and to investigate the presence of HSV-1 in OTSCC and its effect on carcinoma cell viability and invasion. Methods: The distribution of HSV types one and two in diagnostic samples taken from suspected oral HSV infections was determined from the Helsinki University Hospital Laboratory database. We then analysed 67 OTSCC samples for HSV-1 infection using immunohistochemical staining. We further tested the effects of HSV-1 using six concentrations (0.00001-1.0 multiplicity of infection [MOI]) on viability and two concentrations (0.001 and 0.1 MOI) on invasion of highly invasive metastatic HSC-3 and less invasive primary SCC-25 OTSCC cell lines using MTT and Myogel-coated Transwell invasion assays. Results: Altogether 321 oropharyngeal samples were diagnosed positive for HSV during the study period. HSV-1 was the predominant (97.8%) HSV type compared with HSV-2 (detected in 2.2% of samples). HSV-1 was also detected in 24% of the OTSCC samples and had no association with patient survival or recurrence. OTSCC cells were viable even after 6 days with low viral load (0.00001, 0.0001, 0.001 MOI) of HSV-1. In both cell lines, 0.001 MOI did not affect cell invasion. However, 0.1 MOI significantly reduced cell invasion in HSC-3 cells. Discussion: HSV-1 infection is predominant compared with HSV-2 in the oral cavity. HSV-1 is detected in OTSCC samples without clinical significance, and OTSCC cell survival or invasion was not affected at low doses of HSV-1.

Altered oral microbiome in Sudanese Toombak smokeless tobacco users carries a newly emerging risk of squamous cell carcinoma development and progression

There are an estimated 6-10 million smokeless tobacco (Toombak) users in Sudan, the majority being males. Toombak is known to be a carcinogenic product that is likely to modify the oral microbiome spatiality into a high-risk potential for the development and progression of oral cancer, but previous studies are lacking in this field. Here, we endeavour for the first time the exploration of the oral microbiome in key mucosal areas of the oral cavity and assess the microbiome variations in premalignant and oral squamous cell carcinoma (OSCC) samples from both users and non-users of Toombak. 16S rRNA sequencing was performed on DNA obtained from pooled saliva, oral mucosa and supragingival plaque from 78 Sudanese users and non-users of Toombak, aged between 20 and 70 years. In 32 of the pooled saliva samples, the mycobiome (fungal) environment was analysed through ITS sequencing. Then, 46 formalin-fixed paraffin-embedded samples of premalignant and OSCC samples were collected, and their associated microbiomes sequenced. The oral Sudanese microbiome was found to be enriched in Streptococcaceae, but Staphylococcaceae were significantly more abundant amongst Toombak users. Genera enriched in the oral cavity of Toombak users included Corynebacterium_1 and Cardiobacterium while in non-users, Prevotella, Lactobacillus and Bifidobacterium were prominent. Aspergillus was the most abundant fungus in the mouths of Toombak users with a marked loss of Candida. The genus Corynebacterium_1 was abundant in the buccal, floor of the mouth and saliva microbiomes as well as in oral cancer samples from Toombak users indicating a possible role for this genus in the early stages of oral cancer development. An oral cancer microbiome that favours poor survival and metastasis in those who use Toombak also emerged that includes the genera Stenotrophomonas and Schlegelella. Those utilising Toombak carry an altered oral microbiome that may be an additional risk factor for this products carcinogenicity to the oral structures. These significant microbiome modulations are a newly emerging key driving factor in oral cancer development and progression in Toombak users while it is also shown that Toombak users carry an oral cancer microbiome that may increase the potential for a poorer prognosis.

Network-Based Method to Investigate the Promoted Cell Apoptosis Mechanisms of Oridonin in OSCC through the RNA-Transcriptome

The morbidity of oral cancer is high in the world. Oridonin is a traditional Chinese medicine that can effectively inhibit oral squamous cell carcinoma (OSCC) growth, but its mechanism remains unclear. Our previous data showed that oridonin inhibited CAL-27 cell proliferation and promoted apoptosis. Herein, we explored the mechanism and target of oridonin in human OSCC through RNA sequencing and integration of multiple bioinformatics analysis strategies. Differences in gene expression can be analyzed with RNA sequencing. Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), gene set enrichment analysis (GSEA), Disease Ontology (DO), and other enrichment analyses were used to evaluate differentially expressed genes (DEGs). Protein–protein interaction (PPI) networks were built via the STRING database. It was found that tumor necrosis factor (TNF) signaling pathway, cytokine–cytokine receptor interaction, and nuclear factor-kappa B (NF-kappaB) signaling pathway were associated with the therapeutic effects of oridonin in OSCC. Three key genes (BIRC3, TNFSF10, and BCL6) were found to associate with cell apoptosis in OSCC cells treated with oridonin. Quantitative PCR assays verified the expression of apoptosis-related DEGs: TNFSF10, BIRC3, AIFM2, BCL6, BCL2L2, and Bax. Western blots were employed for verifying proteins expression associated with DEGs: cleaved caspase 3, Bax, Bcl-w, anti-cIAP2, and anti-TRAIL. In conclusion, our findings reveal the molecular pathways and targets by which oridonin can treat and induce cytotoxic effects in OSCC: by affecting the signaling including TNF, NF-κB, and cytokine-cytokine receptor interaction and by regulating the key gene BIRC3, TNFSF10, and BCL6. It should be noted that further clinical trial validation is very necessary. Combined with current research trends, our existing research may provide innovative research drugs for the treatment of OSCC.

Torque teno virus and cancers: current knowledge

Aim: The aim of this systematic review is to assess the current knowledge about the relationship between Torque teno virus (TTV) and cancer in different settings. Methods: A systematic search was conducted in Medline via PubMed, Embase and Cochrane Library from the inception to the end of January 2023. Results: 34 articles were included in the qualitative synthesis of this review and 2145 patients with solid tumors have been analyzed. The most prevalent cancer types were hepatocellular carcinoma (HCC) and lung cancer. Conclusion: TTV has proven its role as a marker of functional immune competence in the setting of hematopoietic stem cell transplantation (HSCT), but in the oncological field is yet to be defined.

Oral microbiota in patients with oropharyngeal cancer with an emphasis on <i>Candida</i> spp

Introduction. Interactions between the 2 microbiota components – bacteria and fungi – are of interest as diagnostic and prognostic markers in selection of treatment tactics for oncological patients.

Aim. To study microbiota of the oral cavity in patients with primary squamous cell carcinoma of the oropharyngeal area before and after surgical intervention to find biomarkers for rational selection of antifungal drugs.

Materials and methods. At the Surgical Department of Head and Neck Tumors of the N. N. Blokhin National Research Center of Oncology, three-component study was performed: investigations of spectrum of Candida spp. isolates, Candida spp. strains’ resistance to antifungals, and oral washes in primary patients before and after surgery. mALDI-Tof microflex LT (Biotyper, Bruker Daltonics, germany) was used for strain identification; Sensititre Yeast ONE, YO10 (Trek Diagnostic System, united kingdom) plates were used for determination of minimal inhibiting concentrations of anti fungals. values of minimal inhibiting concentrations were evaluated based on the European Committee on Antimicrobial Susceptibility Testing (EuCAST) criteria (version 10.0).

Results. four-year observation of patients at the surgical department of head and neck tumors of the N. N. Blokhin National Research Center of Oncology showed that the most common species of Candida is C. albicans (73.5 % of cases). Candida spp. resistance to antifungals was detected only for fluconazole (9.3 % of cases) and micafungin (8.0 % of cases), mostly among C. albicans strains. In 31.8 % of primary patients, oral washes prior to surgery showed growth of Candida spp. (probably, tissue colonization). After surgical intervention, Candida spp. growth was detected in 36.4 % of cases, only 1 of which was diagnosed as invasive mycosis. In 54.5 % of cases before and in 72.7 % of cases after surgery, gram-negative rods were detected. After surgical intervention, percentage of enterobacteria and non-fermenters significantly increased: 59.1 % versus 27.3 % (p <0.05) and 63.6 % versus 27.3 % (p <0.02), respectively. prior to surgery, non-fermenting gram-negative bacteria were represented only by P. aeruginosa; after surgery, the spectrum of non-fermenting gram-negative bacteria became wider but percentage of P. aeruginosa remained high: 71.4 %. ERG11 gene was identified only in 1 strain: C. albicans. FKS1 gene also was identified only in 1 strain: C. inconspicua. virulence factor genes were detected in 57.1 % of strains.

Conclusion. Surgical intervention is associated with changes in bacterial microbiota but not fugal microbiota. presence of virulence factor genes and resistance genes in Candida spp. strains should be considered a biomarker allowing to differentiate between colonization and candida infection and can be used for rational selection of antifungal drugs in prevention and treatment of invasive candidiasis, especially in the absence of criteria for interpretation of measured minimal inhibiting concentrations of antifungals.

Effects of N7-Alkylguanine Conformation and Metal Cofactors on the Translesion Synthesis by Human DNA Polymerase η

Non-enzymatic alkylation on DNA often generates N7-alkyl-2'-deoxyguanosine (N7alkylG) adducts as major lesions. N7alkylG adducts significantly block replicative DNA polymerases and can be bypassed by translesion synthesis (TLS) polymerases such as polymerase η (polη). To gain insights into the bypass of N7alkylG by TLS polymerases, we conducted kinetic and structural studies of polη catalyzing across N7BnG, a genotoxic lesion generated by the carcinogenic N-nitrosobenzylmethylamine. The presence of templating N7BnG in the polη catalytic site decreased the replication fidelity by ∼9-fold, highlighting the promutagenicity of N7BnG. The catalytic efficiency for dCTP incorporation opposite N7BnG decreased ∼22-fold and ∼7-fold compared to the incorporation opposite undamaged guanine in the presence of Mg²⁺ and Mn²⁺, respectively. A crystal structure of the complexes grown with polη, templating N7BnG, incoming dCTP, and Mg²⁺ ions showed the lack of the incoming nucleotide and metal cofactors in the polη catalytic site. Interestingly, the templating N7BnG adopted a syn conformation, which has not been observed in the published N7alkylG structures. The preferential formation of syn-N7BnG conformation at the templating site may deter the binding of an incoming dCTP, causing the inefficient bypass by polη. In contrast, the use of Mn²⁺ in place of Mg²⁺ in co-crystallization yielded a ternary complex displaying an anti-N7BnG:dCTP base pair and catalytic metal ions, which would be a close mimic of a catalytically competent state. We conclude that certain bulky N7-alkylG lesions can slow TLS polymerase-mediated bypass by adopting a catalytically unfavorable syn conformation in the replicating base pair site.

A review on association of fungi with the development and progression of carcinogenesis in the human body

The role and impact of commensal and pathogenic fungi in different parts of the human body are being increasingly appreciated, unveiling the importance of such microorganisms in human health. A key function is the involvement of the mycobiota in cross-kingdom interactions within the microbiome. Any disturbance in the functionality of the microbiota could alter metabolic reactions, have a negative impact on homeostasis or induce diseases. The association of fungi with cancer development is the focus of this review. Several studies have reported direct or indirect involvement of fungal pathogens and mycobiome dysbiosis in induction of carcinogenesis. Most studies focused on cancers of the gastrointestinal tract. However, researchers are now investigating other organs, such as the skin, where the significant results obtained confirm the involvement of fungal pathogens and administration of antifungal drugs in development of cancer. This review gives an overview of the different organs affected and describes the mechanisms used by these eukaryotes or antifungals to induce oncogenesis.

Head and Neck Squamous Cell Carcinoma: Risk Factors, Molecular Alterations, Immunology and Peptide Vaccines

Head and neck squamous cell carcinoma (HNSCC) arises from the epithelial lining of the oral cavity, hypopharynx, oropharynx, and larynx. There are several potential risk factors that cause the generation of HNSCC, including cigarette smoking, alcohol consumption, betel quid chewing, inadequate nutrition, poor oral hygiene, HPV and Epstein–Barr virus, and Candida albicans infections. HNSCC has causative links to both environmental factors and genetic mutations, with the latter playing a more critical role in cancer progression. These molecular changes to epithelial cells include the inactivation of cancer suppressor genes and proto-oncogenes overexpression, resulting in tumour cell proliferation and distant metastasis. HNSCC patients have impaired dendritic cell (DC) and natural killer (NK) cell functions, increased production of higher immune-suppressive molecules, loss of regulatory T cells and co-stimulatory molecules and major histocompatibility complex (MHC) class Ι molecules, lower number of lymphocyte subsets, and a poor response to antigen-presenting cells. At present, the standard treatment modalities for HNSCC patients include surgery, chemotherapy and radiotherapy, and combinatorial therapy. Despite advances in the development of novel treatment modalities over the last few decades, survival rates of HNSCC patients have not increased. To establish effective immunotherapies, a greater understanding of interactions between the immune system and HNSCC is required, and there is a particular need to develop novel therapeutic options. A therapeutic cancer vaccine has been proposed as a promising method to improve outcome by inducing a powerful adaptive immune response that leads to cancer cell elimination. Compared with other vaccines, peptide cancer vaccines are more robust and specific. In the past few years, there have been remarkable achievements in peptide-based vaccines for HNSCC patients. Here, we summarize the latest molecular alterations in HNSCC, explore the immune response to HNSCC, and discuss the latest developments in peptide-based cancer vaccine strategies. This review highlights areas for valuable future research focusing on peptide-based cancer vaccines.

Structural and Kinetic Studies of the Effect of Guanine N7 Alkylation and Metal Cofactors on DNA Replication

A wide variety of endogenous and exogenous alkylating agents attack DNA to preferentially generate N7-alkylguanine (N7-alkylG) adducts. Studies of the effect of N7-alkylG lesions on biological processes have been difficult in part because of complications arising from the chemical lability of the positively charged N7-alkylG, which can readily produce secondary lesions. To assess the effect of bulky N7-alkylG on DNA replication, we prepared chemically stable N7-benzylguanine (N7bnG)-containing DNA and evaluated nucleotide incorporation opposite the lesion by human DNA polymerase β (polβ), a model enzyme for high-fidelity DNA polymerases. Kinetic studies showed that the N7-benzyl-G lesion greatly inhibited dCTP incorporation by polβ. The crystal structure of polβ incorporating dCTP opposite N7bnG showed a Watson-Crick N7bnG:dCTP structure. The polβ-N7bnG:dCTP structure showed an open protein conformation, a relatively disordered dCTP, and a lack of catalytic metal, which explained the inefficient nucleotide incorporation opposite N7bnG. This indicates that polβ is sensitive to major groove adducts in the templating base side and deters nucleotide incorporation opposite bulky N7-alkylG adducts by adopting a catalytically incompetent conformation. Substituting Mg²⁺ for Mn²⁺ induced an open-to-closed conformational change due to the presence of catalytic metal and stably bound dCTP and increased the catalytic efficiency by ∼10-fold, highlighting the effect of binding of the incoming nucleotide and catalytic metal on protein conformation and nucleotidyl transfer reaction. Overall, these results suggest that, although bulky alkyl groups at guanine-N7 may not alter base pairing properties of guanine, the major groove-positioned lesions in the template could impede nucleotidyl transfer by some DNA polymerases.

Oropharyngeal Candidiasis in Patients Undergoing Radiotherapy for Head and Neck Cancer: Literature Review

AbstractCandidiasis is closely related to patients undergoing head and neck radiotherapy due to the immunosuppressive state, induced xerostomia, mucositis and difficulties in establishing adequate oral hygiene. Therefore, the aim of this study was to discuss the relationship between candidal infections and the radiotherapy of the head and neck region, based on available scientific literature. In order to identify the studies included or considered in this study, a search strategy was carried out for the following databases: SCOPUS, Web of Science and PubMed. Inclusion criteria were publications that addressed key words: Candida spp. of the oral cavity and head and neck cancer. Therefore, this work exposes the necessity for studies relating candidal infections with radiotherapy treatment of the head and neck region.  However, it is possible suggest that colonization and infection by Candida spp. can be increased by radiotherapy. Additionally, it can be suggested that patients irradiated at the head and neck region should be periodically investigated for the presence of pathogenic yeasts in the oral cavity, followed by greater care with oral hygiene and nutrition.Keywords: Candida Spp. Xerostomia. Oral Health. Publications.ResumoA candidíase está intimamente relacionada com pacientes submetidos a radioterapia de cabeça e pescoço devido ao estado imunossupressor, xerostomia induzida, mucosite e dificuldades no estabelecimento de higiene bucal adequada. Portanto, o objetivo deste estudo foi discutir a relação entre infecções por Candida spp. e a radioterapia da região da cabeça e pescoço, com base na literatura científica disponível. Para identificar os estudos incluídos ou considerados neste estudo, foi realizada uma estratégia de busca para os seguintes bancos de dados: SCOPUS, Web of Science e PubMed. Os critérios de inclusão foram publicações que abordavam as palavras-chave: Candida spp. da cavidade oral e câncer de cabeça e pescoço. Desta forma, este trabalho expõe a necessidade de estudos relacionados às infecções por Candida spp. com tratamento de radioterapia da região da cabeça e pescoço. No entanto, podemos sugerir que a colonização e a infecção por Candida spp. pode ser aumentada por radioterapia. Além disso, pode-se sugerir que os pacientes irradiados na região da cabeça e pescoço devem ser investigados periodicamente quanto à presença de leveduras patogênicas na cavidade bucal, seguido de maiores cuidados com higiene bucal e nutrição.Palavras-chave: Candida Spp. Xerostomia. Saúde Bucal. Publicações.

Prevalence and genotypes of human papillomavirus in saliva and tumor samples of head and neck cancer patients in Hungary

In addition to traditional risk factors such as smoking, alcohol consumption and betel nut use, human papillomavirus (HPV) infection also plays a role in the development of head and neck squamous cell carcinomas (HNSCCs). Although among European countries the highest incidence and mortality rates of head and neck cancer types were recorded in Hungary, data regarding HPV prevalence in HNSCCs is scarce. We collected biopsy and saliva samples from patients diagnosed with HNSCC or oral potentially malignant disorders (OPMDs) and tested them for the presence of HPV using the PCR consensus primer set MY09/11 and the GP5+/6+ primer pair. HPV genotypes were assessed by sequencing of the amplified PCR fragments. Oral mucosa and saliva samples from tumor- and OPMD-free individuals were also analysed. HPV was detected in 11 out of 60 HNSCC samples (18%). All of the HPV positive tumors carried HPV type 16. 5 out of the 57 saliva samples collected from HNSCC patients was HPV positive (8.8%); among them, in addition to HPV16, HPV13 was also detected. Tumors located to the oropharynx had the highest HPV positivity rate with 50% (7 out of 14), which was significantly higher than the HPV prevalence in oral mucosa samples collected from controls (0 out of 20; p > 0.001) or in OPMD biopsies (0 out of 21, p > 0.001). 2 out of 57 control saliva samples (3.5%, subtype HPV13 and 11) and 3 out of 39 saliva samples from OPMD patients (7.7%, subtype HPV18, 81 and 10) were HPV positive. Our data suggested that HPV16 infection may contribute, in concert with cigarette smoking, to the development of a subset of head and neck cancers in Hungary. HPV16 infection per se does not account, however, for the high HNSCC incidence rate recorded in this country.

Pathogenic mechanisms of intracellular bacteria

PURPOSE OF REVIEW

We wished to overview recent data on a subset of epigenetic changes elicited by intracellular bacteria in human cells. Reprogramming the gene expression pattern of various host cells may facilitate bacterial growth, survival, and spread.

RECENT FINDINGS

DNA-(cytosine C5)-methyltransferases of Mycoplasma hyorhinis targeting cytosine-phosphate-guanine (CpG) dinucleotides and a Mycobacterium tuberculosis methyltransferase targeting non-CpG sites methylated the host cell DNA and altered the pattern of gene expression. Gene silencing by CpG methylation and histone deacetylation, mediated by cellular enzymes, also occurred in M. tuberculosis-infected macrophages. M. tuberculosis elicited cell type-specific epigenetic changes: it caused increased DNA methylation in macrophages, but induced demethylation, deposition of euchromatic histone marks and activation of immune-related genes in dendritic cells. A secreted transposase of Acinetobacter baumannii silenced a cellular gene, whereas Mycobacterium leprae altered the epigenotype, phenotype, and fate of infected Schwann cells. The 'keystone pathogen' oral bacterium Porphyromonas gingivalis induced local DNA methylation and increased the level of histone acetylation in host cells. These epigenetic changes at the biofilm-gingiva interface may contribute to the development of periodontitis.

SUMMARY

Epigenetic regulators produced by intracellular bacteria alter the epigenotype and gene expression pattern of host cells and play an important role in pathogenesis.

Host-Microbiome Interaction and Cancer: Potential Application in Precision Medicine

It has been experimentally shown that host-microbial interaction plays a major role in shaping the wellness or disease of the human body. Microorganisms coexisting in human tissues provide a variety of benefits that contribute to proper functional activity in the host through the modulation of fundamental processes such as signal transduction, immunity and metabolism. The unbalance of this microbial profile, or dysbiosis, has been correlated with the genesis and evolution of complex diseases such as cancer. Although this latter disease has been thoroughly studied using different high-throughput (HT) technologies, its heterogeneous nature makes its understanding and proper treatment in patients a remaining challenge in clinical settings. Notably, given the outstanding role of host-microbiome interactions, the ecological interactions with microorganisms have become a new significant aspect in the systems that can contribute to the diagnosis and potential treatment of solid cancers. As a part of expanding precision medicine in the area of cancer research, efforts aimed at effective treatments for various kinds of cancer based on the knowledge of genetics, biology of the disease and host-microbiome interactions might improve the prediction of disease risk and implement potential microbiota-directed therapeutics. In this review, we present the state of the art of sequencing and metabolome technologies, computational methods and schemes in systems biology that have addressed recent breakthroughs of uncovering relationships or associations between microorganisms and cancer. Together, microbiome studies extend the horizon of new personalized treatments against cancer from the perspective of precision medicine through a synergistic strategy integrating clinical knowledge, HT data, bioinformatics, and systems biology.

Expression of Epstein-Barr virus among oral potentially malignant disorders and oral squamous cell carcinomas in the South Indian tobacco-chewing population

BACKGROUND

Oral cancer is the sixth most common malignancy in the world. Viruses are the causative agents of approximately 10-15% of all cancers worldwide (Cancers, 6, 2014 and 2155). The tumorigenic roles of Epstein-Barr virus in oral cancer are unclear. Literature search results are conflicting and dependent on various factors such as geographical/regional variations, sociocultural lifestyles, dietary habits, chewing/smoking tobacco habit. This study is the first original observation about frequency of Epstein-Barr virus among South Indian tobacco-chewing patients to elucidate its involvement in oral carcinogenesis and to know whether this can be a valuable diagnostic and prognostic indicator.

MATERIALS AND METHODS

A total number of 75 tobacco chewer subjects aged between 23 and 76 years with histopathologically confirmed oral potentially malignant disorders (25), oral squamous cell carcinoma (25), and age-matched healthy controls (25) formed the study group. Immunohistochemical expression of Epstein-Barr virus latent membrane protein 1 was assessed among cases and healthy controls.

RESULTS

Out of the total 75 subjects, six subjects (8%) were positive for Epstein-Barr virus antigen and 69 subjects (92%) negative. The antigen positivity was observed among two cases of moderately differentiated oral squamous cell carcinoma, two cases of leukoplakia, and two healthy controls.

CONCLUSION

No significant association between Epstein-Barr virus positivity was observed among oral potentially malignant disorders and oral squamous cell carcinoma among South Indian tobacco-chewing patients. This can be partially explained by the methodology employed, by the patient population analyzed and different habits in various geographical regions.