Professor Gary Moran

The genome of the fungal pathogen Candida albicans contains a family of ~14 telomeric TLO genes encoding putative transcription factors. The closely related non-pathogenic species C. dubliniensis contains only two orthologous genes, suggesting that the increased gene number in C. albicans may contribute to the increased virulence of this species. Using a combination of mutant construction, transcript profiling and ChIP-Chip analysis, this study aims to determine the role of these gene in the biology and virulence of Candida species.

Oral squamous cell carcinoma (OSCC) exerts a significant clinical and financial burden worldwide. Recently, there has been increasing interest in the role of the microbiome in OSCC. Among microbial species that have frequently been identified in association with OSCC and demonstrated to promote oral carcinogenesis, both in vitro and in animal models, include the bacterium Fusobacterium nucleatum and the fungus Candida albicans. The two species have been demonstrated to interact via co-aggregation; however, whether such interkingdom interaction can promote oral carcinogenesis has never been explored The current proposal builds on our previous studies investigating the microbiome associated with OSCC and oral leukoplakia in clinical samples, and assessing the effects of oral bacteria against oral epithelial cell lines in vitro. The proposed studies will investigate for the first time the potentially synergistic interaction between C. albicans and F. nucleatum in malignant progression, which we hypothesize is facilitated by their coaggregation. Based on our preliminary data, we also hypothesize that the two species mediate part of their oncogenic properties through upregulation of INHBA, a proposed oncogene acting through the TGF-ß pathway. To address these hypotheses, we propose to assess synergistic effects of C. albicans and F. nucleatum on normal, dysplastic, and neoplastic oral epithelium in vitro (Aim 1), and to study the carcinogenicity of C. albicans and F. nucleatum co-carriage in 4-nitroquinoline-1-oxide-induced OSCC mouse model (Aim 2). Combinations of wild-type, aggregation +ve strains and mutant, aggregation-deficient strains of the two species will be used in the two aims to assess the role of co-aggregation in promoting synergistic carcinogenicity. The involvement of INHBA upregulation in this synergy will be investigated by mechanistic gene knockdown experiments. The project will employ a range of technologies including cellular and biochemical assays, metatranscriptomics, histopathology, immunohistochemistry, flow cytometry, q-PCR, fluorescent in-situ hybridization and 16S sequencing to investigate the effect of treating the cell lines and mice with the test species. This innovative, exploratory study leverages the complementary expertise of the research team to provide a first insight into the potential role of interkingdom microbial interactions in OSCC and shed light on novel mechanisms by which C. albicans and F. nucleatum may contribute to oral carcinogenesis

Oral squamous cell carcinoma (OSCC) accounts for 90% of oral cancers. According to the National Cancer Registry, the rate of OSCC in Ireland is increasing annually by 3.3%. OSCCs can arise de novo or from preneoplasis such as Oral Leukoplakia (OLK). Risks factors for OLK include smoking and alcohol consumption, however the mechanisms by which OLK progresses to OSCC are poorly understood and it is difficult to predict which OLKs will resolve or progress. The degree of dysplasia on biopsy is the best indicator of progression, with severe dysplasia being associated with greater risk relative to mild or moderate dysplasia. Recently, oral bacteria such as Fusobacterium nucleatum have been identified as potential drivers of malignant progression in the GI tract. Our recently published preliminary data examining the microbiome of OLK has shown that OLK lesions are colonised with a greater abundance of Fusobacteria, Campylobacter species and Candida albicans compared to healthy mucosa from the same patient. Our hypothesis is that changes in the composition of the mucosal microbiome are a driver of the malignant transformation of oral leukoplakia (OLK) to oral squamous cell carcinoma (OSCC). Characterisation of these microbiome changes will allow us to identify the organisms associated with severe dysplasia and therefore develop tests to identify the patients at greatest risk of malignant progression. In this study we will carry out a comprehensive comparison of the OLK microbiome compared to the healthy mucosal microbiome by Illumina sequence analysis in a large cohort of patients (n=235) to determine whether colonisation of OLK with certain microorganisms is significantly associated with severe dysplasia. These data will indicate whether routine microbiome profiling could be useful as a tool to predict the risk of malignant progression and whether topical antibiotic therapy is warranted to reduce the risk of OSCC.

The oral micro biome constitutes several hundred species of bacteria and fungi. Their role in oral and systemic health is poorly understood. This study will use 16s and 18s sequencing to identify populations associated with malignant lesions in the oral cavity and marker organisms for diseases of the bowel (colitis and Crohn's)

Our recent studies have highlighted the role of nutrients and the nutrient sensing kinase Tor1 in regulating filamentation and virulence in the fungal pathogen C. dubliniensis. In this study we will examine the role of mutations in the Tor kinase pathway that lead to Tor hyperactivity. It is our hypothesis that Tor hyperactive strains of C. albicans will resemble the less virulent pathogen C. dubliniensis. These data will indicate whether Tor agonists have potential as antifungal agents.