Stimulation with Porphyromonas gingivalis enhances malignancy and initiates anoikis resistance in immortalized oral keratinocytes

About a Possible Impact of Endodontic Infections by Fusobacterium nucleatum or Porphyromonas gingivalis on Oral Carcinogenesis: A Literature Overview

Periodontitis is linked to the onset and progression of oral squamous cell carcinoma (OSCC), an epidemiologically frequent and clinically aggressive malignancy. In this context, Fusobacterium (F.) nucleatum and Porphyromonas (P.) gingivalis, two bacteria that cause periodontitis, are found in OSCC tissues as well as in oral premalignant lesions, where they exert pro-tumorigenic activities. Since the two bacteria are present also in endodontic diseases, playing a role in their pathogenesis, here we analyze the literature searching for information on the impact that endodontic infection by P. gingivalis or F. nucleatum could have on cellular and molecular events involved in oral carcinogenesis. Results from the reviewed papers indicate that infection by P. gingivalis and/or F. nucleatum triggers the production of inflammatory cytokines and growth factors in dental pulp cells or periodontal cells, affecting the survival, proliferation, invasion, and differentiation of OSCC cells. In addition, the two bacteria and the cytokines they induce halt the differentiation and stimulate the proliferation and invasion of stem cells populating the dental pulp or the periodontium. Although most of the literature confutes the possibility that bacteria-induced endodontic inflammatory diseases could impact on oral carcinogenesis, the papers we have analyzed and discussed herein recommend further investigations on this topic.

Potential role of epithelial-mesenchymal transition induced by periodontal pathogens in oral cancer

With the increasing incidence of oral cancer in the world, it has become a hotspot to explore the pathogenesis and prevention of oral cancer. It has been proved there is a strong link between periodontal pathogens and oral cancer. However, the specific molecular and cellular pathogenic mechanisms remain to be further elucidated. Emerging evidence suggests that periodontal pathogens-induced epithelial-mesenchymal transition (EMT) is closely related to the progression of oral cancer. Cells undergoing EMT showed increased motility, aggressiveness and stemness, which provide a pro-tumour environment and promote malignant metastasis of oral cancer. Plenty of studies proposed periodontal pathogens promote carcinogenesis via EMT. In the current review, we discussed the association between the development of oral cancer and periodontal pathogens, and summarized various mechanisms of EMT caused by periodontal pathogens, which are supposed to play an important role in oral cancer, to provide targets for future research in the fight against oral cancer.

Occurrence of Human Defensins and S100 Proteins in Head and Neck Basal Cell Carcinoma (BCC) Entities: hBD3 and S100A4 as Potential Biomarkers to Evaluate Successful Surgical Therapy

Background: The goal of this study is the identification of potential marker molecules for characterizing different basal cell carcinoma entities, to help improve clinical decisions for surgical resection therapy. Methods: Three different entities, sclerodermiform, solid and superficial basal cell carcinomas, were subjected to immunohistochemical microscopy and histomorphometric analyses for human α- (DEFA1/3; DEFA4) and β-defensins (hBD1/2/3) and special S100 proteins (S100A4/7/8/9). Thirty specimens of the three entities were evaluated. Analyses were performed by comparing tissue and cellular localization and staining intensities of tumorous with non-tumorous areas. Staining intensities were semiquantitatively examined by using an RGB-based model. Results: Human defensins are present in all three entities of basal cell carcinomas. They all show cytoplasmic immunostaining in cells of the epithelium, stroma and tumor. Notably, human β-defensin3 is accumulated in the cell nuclei of sclerodermiform and superficial basal cell carcinomas. S100A4 and A7 are undetectable in tumor regions. However, S100A4 occurs in cancer-associated stroma cells with nuclear staining in superficial basal cell carcinomas. Conclusion: Two candidates, namely hBD3 and S100A4, might be used as potential clinical tools for evaluating successful surgical resection therapy to avoid aesthetic and functional facial deformation.

The Microbiome in Pancreatic Cancer-Implications for Diagnosis and Precision Bacteriophage Therapy for This Low Survival Disease

While the mortality rates for many cancers have decreased due to improved detection and treatments, that of pancreatic cancer remains stubbornly high. The microbiome is an important factor in the progression of many cancers. Greater understanding of the microbiome in pancreatic cancer patients, as well as its manipulation, may assist in diagnosis and treatment of this disease. In this report we reviewed studies that compared microbiome changes in pancreatic cancer patients and non-cancer patients. We then identified which bacterial genera were most increased in relative abundance across the oral, pancreatic, duodenal, and faecal tissue microbiomes. In light of these findings, we discuss the potential for utilising these bacteria as diagnostic biomarkers, as well as their potential control using precision targeting with bacteriophages, in instances where a causal oncogenic link is made.

Oral Microbiota-Driven Cell Migration in Carcinogenesis and Metastasis

The oral cavity harbors approximately 1,000 microbial species, and both pathogenic and commensal strains are involved in the development of carcinogenesis by stimulating chronic inflammation, affecting cell proliferation, and inhibiting cell apoptosis. Moreover, some substances produced by oral bacteria can also act in a carcinogenic manner. The link between oral microbiota and chronic inflammation as well as cell proliferation has been well established. Recently, increasing evidence has indicated the association of the oral microbiota with cell migration, which is crucial in regulating devastating diseases such as cancer. For instance, increased cell migration induced the spread of highly malignant cancer cells. Due to advanced technologies, the mechanistic understanding of cell migration in carcinogenesis and cancer metastasis is undergoing rapid progress. Thus, this review addressed the complexities of cell migration in carcinogenesis and cancer metastasis. We also integrate recent findings on the molecular mechanisms by which the oral microbiota regulates cell migration, with emphasis on the effect of the oral microbiota on adhesion, polarization, and guidance. Finally, we also highlight critical techniques, such as intravital microscopy and superresolution microscopy, for studies in this field.

Role of Porphyromonas gingivalis in oral and orodigestive squamous cell carcinoma

Oral and esophageal squamous cell carcinomas harbor a diverse microbiome that differs compositionally from precancerous and healthy tissues. Though causality is yet to be definitively established, emerging trends implicate periodontal pathogens such as Porphyromonas gingivalis as associated with the cancerous state. Moreover, infection with P. gingivalis correlates with a poor prognosis, and P. gingivalis is oncopathogenic in animal models. Mechanistically, properties of P. gingivalis that have been established in vitro and could promote tumor development include induction of a dysbiotic inflammatory microenvironment, inhibition of apoptosis, increased cell proliferation, enhanced angiogenesis, activation of epithelial-to-mesenchymal transition, and production of carcinogenic metabolites. The microbial community context is also relevant to oncopathogenicity, and consortia of P. gingivalis and Fusobacterium nucleatum are synergistically pathogenic in oral cancer models in vivo. In contrast, oral streptococci, such as Streptococcus gordonii, can antagonize protumorigenic epithelial cell phenotypes induced by P. gingivalis, indicating functionally specialized roles for bacteria in oncogenic communities. Consistent with the notion of the bacterial community constituting the etiologic unit, metatranscriptomic data indicate that functional, rather than compositional, properties of the tumor-associated communities have more relevance to cancer development. A consistent association of P. gingivalis with oral and orodigestive carcinoma could have diagnostic potential for early detection of these conditions that have a high incidence and low survival rates.

Salivary Porphyromonas gingivalis predicts outcome in oral squamous cell carcinomas: a cohort study

Background

Studies suggest Porphyromonas gingivalis (Pg) increased the incidence of oral squamous cell carcinoma (OSCC). However, fimA genotypes distribution of Pg, the origination of Pg in tissue, and its prognostic value are inconclusive. We aimed to investigate the frequency of fimA genotypes in OSCC patients, study the association between Pg and OSCC, and explore the prognostic value of Pg.

Methods

The abundance of Pg in saliva from the OSCC group and the OSCC-free group was analysed by qPCR. The presence of Pg was explored in OSCC tissue and para-cancerous tissue by in situ hybridization. The frequency of fimA genotypes in saliva and OSCC tissue was determined by PCR, then PCR products were sequenced and compared. Clinical data were extracted, and patients followed up for a median period of 23 months. Clinicopathological variables were compared with the abundance of Pg using Pearson Chi-square test or Fisher’s exact test. The disease-free survival (DFS) rate was calculated by Kaplan–Meier method with log-rank tests.

Results

Comparing the OSCC-free group, 95 patients with OSCC showed a high abundance of Pg in saliva (P = 0.033), and OSCC tissue showed strong in situ expression of Pg compared with paired normal tissue. Patients with OSCC showed a dominant distribution of Pg with genotype I + Ib (21.1%), II (31.6%), and IV (21.1%). FimA genotypes detected in saliva were in accordance with those in OSCC tissue, there was, moreover, a significant similarity in amplified Pg fragments. Of the 94 responsive OSCC patients, the recurrence rate was 26.6% (25/94). Overabundance of Pg in saliva showed advanced pathologic staging (P = 0.008), longer disease-free time (P = 0.029) and lower recurrence rate (P = 0.033). The overabundance of Pg in saliva was associated with improved disease-free survival (P = 0.049).

Conclusions

This study indicated that Pg might involve in the pathogenesis of OSCC, Pg carrying fimA I, Ib, II, and IV were prevalent genotypes in patients with OSCC, the provenance of Pg in OSCC tissue might be from the salivary microbial reservoir, and the abundance of Pg in saliva might consider as a favorable potential prognostic indicator in OSCC.

Expression profile of macrophage migration inhibitory factor in periodontitis

OBJECTIVE

Macrophage migration inhibitory factor (MIF) is a pivotal mediator of host innate immunity and influences the development of several inflammatory diseases. The role of MIF in periodontitis is unclear.

METHODS

Eighteen periodontally healthy volunteers and 18 patients with stage III or IV periodontitis were enrolled. Blood samples and gingival tissues were collected from all individuals. The serum concentrations of MIF and MCP-1 were measured by ELISA. The protein and mRNA levels of MIF and MCP-1 in gingival tissue were evaluated by immunohistochemical staining and quantitative PCR. The levels of secreted MIF and MCP-1, as well as their mRNA levels, were determined by ELISA and quantitative PCR in oral epithelial cells infected with Porphyromonas gingivalis.

RESULTS

After adjusting for age, the level of MCP-1 was significantly higher in the serum and gingival tissue of periodontitis patients, as well as in infected epithelial cells. The serum concentration of MIF was increased in periodontitis patients (15.25 ± 2.16 ng/mL, P < 0.05) compared to healthy controls (10.43 ± 1.02 ng/mL). Increased MIF immunoreactivity was found in gingival epithelial tissue but not in the gingival connective tissue of periodontitis patients. The secretion of MIF was 3.82-fold higher in the supernatant of infected cells than in the supernatant of control (P < 0.01). No increase in the MIF mRNA level was found in either gingival tissue or epithelial cells.

CONCLUSIONS

Based on our limited evidence, we showed the level of MIF was related to periodontal conditions. P. gingivalis may contribute to the development and progression of periodontitis through MIF.

Effects of Oral Commensal Streptococci on Porphyromonas gingivalis Invasion into Oral Epithelial Cells

The objective of this study was to determine if the interaction between common oral commensal bacteria and oral epithelial cells would provide protective effects against the invasion of periodontopathogen Porphyromonas gingivalis. Oral epithelial OKF6/Tert cells were used in co-cultures with Streptococcus gordonii, Streptococcus oralis, Streptococcus mitis, and Streptococcus intermedius. The viability of OKF6/Tert cells following a bacterial challenge was evaluated by trypan blue exclusion. The adherence of commensal species was determined by CFU counts. P. gingivalis invasion in OKF6/Tert cells was assessed before and after exposure to commensal species according to CFU counts. Viability assays show that only S. gordonii and S. intermedius display low toxicity toward OKF6/Tert cells. Both commensals adhere to OKF6/Tert cells at an average ratio of 1 CFU to 10 cells. P. gingivalis invasion into host cells is significantly reduced by 25% or 60% after exposure to S. gordonii or S. intermedius, respectively. The results suggest that these commensal species bind to host cells and diminish P. gingivalis invasion. This is important in the context of periodontal disease since P. gingivalis primarily acts on the host by invading it. Therefore, efforts to decrease invasion will eventually lead to future therapies harnessing the mechanisms employed by oral commensal bacteria.