• Elucidating the Role of Fatty Acid Synthase in Oral Carcinogenesis and Potential Therapeutics

      Wisniewski, David John; Schneider, Abraham; 0000-0002-7514-7918 (2018)
      The 5-year overall survival rate in oral squamous cell carcinoma (OSCC) has remained relatively unchanged over decades, due to late stage diagnosis and high recurrence rates. This work investigates two potential contributing risk factors associated with OSCC development: nicotine, present in traditional combustible tobacco cigarettes and electronic nicotine delivery systems, and high glucose as associated with Type II diabetes and hyperglycemia. A novel therapeutic, TVB-3166, for OSCC treatment was also studied through in vitro experiments, which may help improve clinical treatments for fully developed, often late-stage OSCC. Through cell viability and growth assays, scratch assays to mimic in vitro migration, and western blotting, we determined that both nicotine and high glucose caused oral dysplastic keratinocytes to exhibit an increase in malignant-like behavior. High expression levels of fatty acid synthase (FASN), a key de novo lipogenic enzyme, have been implicated in OSCC, and this work presents the first evidence that both nicotine and high glucose markedly increase oral dysplastic keratinocyte FASN expression, which drives epidermal growth factor receptor (EGFR) signaling, a key pro-oncogenic signaling pathway commonly associated with oral carcinogenesis. We also demonstrate that TVB-3166, a novel selective FASN inhibitor, induces apoptosis and reduces in vitro OSCC cell migration. Moreover, TVB-3166 inhibits basal EGFR activity and several other oncogenic signaling proteins. This further establishes a potential role for FASN and EGFR not only in the progression of oral epithelial dysplastic pre-malignant lesions, but in fully-developed OSCC tumors. Overall, this work suggests that both nicotine and high glucose play a role in OSCC progression, specifically as it relates to FASN-dependent EGFR activation. Further, the novel drug TVB-3166 should be investigated in future pre-clinical animal models as a potential adjunct to OSCC therapeutics. Through an improved understanding of risk factors for OSCC development, as well as determination of novel therapeutic strategies, this work aims to improve overall patient survival through prevention of OSCC development, as well as discovery of new adjunctive treatments for fully established tumors.
    • Role of Cell Cycle Regulators Enhancer of Zeste Homolog 2 and Cell Division Cycle 25A in Tumorigenesis of the Aerodigestive Tract

      Younis, Rania Hassan M.; Mao, Li, M.D. (2011)
      Oral Squamous Cell Carcinoma (OSCC) and Non Small Cell Lung Cancer (NSCLC) represent the most common aerodigestive tract malignancies and are a major public health burden worldwide. The prognosis of NSCLC patients is dismal with a 5-year survival rate of 16%. Although the 5-year survival rate of patients with OSCC is more than 50%, many of the survivors suffer significant treatment side effects and disfigurement. Therefore, further understanding of the biologic basis of tumorigenic processes of these cancers is critical for development of novel diagnostic and therapeutic strategies. One of the common features of these cancers is the deregulation of cell cycle process during carcinogenesis. The transcriptional repressor Enhancer of Zeste Homolog 2 (EZH2) has been implicated in cell cycle regulation and tumorigenesis. While the cell cycle promoter Cell Division Cycle 25A (CDC25A) has been proposed as a critical cell cycle promoter linked to several malignancies. Here we investigated the role of the epigenetic EZH2 on cell cycle progression and malignant phenotypes in oral premalignancy and NSCLC. We also studied CDC25A expression and modulation of the cell cycle in NSCLC. Our results provide evidence that EZH2 promotes malignancy in Leuk-1 cell line and is a prognostic marker to OSCC onset in patients with oral premalignancy. EZH2 expression directly correlated with expression of cell cycle promoters in NSCLC NCI-H1299 and Leuk-1 cells. We also identified CDC25A-Q110del a stable isoform in NSCLC that confers CDC25A protein stability and promotes its activity. CDC25A-Q110del confers more cellular survival upon DNA damage and correlates with poor overall survival in NSCLC patients. These data unravel a novel role of EZH2 in cell cycle regulation of oral premalignancy and describe a new mode of regulation and expression of CDC25A in NSCLC. Given the potential role of the two molecules in the tumorigenic process, they may also serve as targets for blocking tumor development or progression. The link between EZH2 and CDC25A in cell cycle regulation may warrant additional investigation regarding the cross talk between the two molecules.
    • The Role of miRNAs in Early Detection of Oral Cancer

      Almubarak, Hussain Mohammed; Meiller, Timothy F.; Mao, Li, M.D. (2012)
      MicroRNAs, commonly noted as miRNAs (miRs), are evolutionary conserved small non-coding RNAs that negatively regulate gene expression post-transcriptionally. Recently, miRNAs have been identified as potentially important biomarkers in various cancers including oral squamous cell carcinoma. The hypothesis of this study was that the expression of miRNAs is different in squamous cell carcinoma in African Americans as compared to Caucasians; as well as when compared to Age, Sex, Location, Recurrence, Grade of cancer, Stage of cancer, Neural invasion, Muscular invasion, and HPV 16/18 or HPV 31/33/51 status. Fifty cases of oral squamous cell carcinoma were matched to the Maryland Cancer Registry (MCR) database and were selected for one Caucasian and one African American in matched sets for age, sex and location. To detect potentially significant miRNAs, two different epithelial cell lines were selected to represent the normal epithelium (HaCaT and NOK) and compared to the dysplastic epithelium (Leuk-1) and the oral cancer (SCC-9 and SCC-25). The miRNAs profiling was performed for the cell lines and several dysregulated miRNAs were identified. The microarray data were validated by the real-time PCR. The expression of miR-708, miR-193a-5p, miR-155, miR-584, miR-663, and miR-886-5p suggested their significant potential at the early stages of tumorigenesis. However, miR-30d, miR-34a, miR-34c-3p, miR-138, and miR-486-5p were dysregulated only in cancer cell lines reflecting their potential at the late stages. The prominently dysregulated miR-708 and miR-193a-5p were selected for further analysis. The lentiviral transduction targeting miR-708 and miR-193a-5p was used to reverse their originally detected expression levels. Immunoblotting was performed on Survivin, a miR-708's direct target in Renal Cell Carcinoma, and on previously studied biomarkers including Hexokinase II, Beclin 1, and LC3. The expression patterns of the detected miRNAs were matched with microarrays results of the 50 paraffin-embedded tissue samples. Significant difference was found based on race (miR-34c-3p), sex (miR-193a-5p), location (miR-193a-5p & miR-34a), grade (miR-486-5p), and HPV status (miR-584). The survival analysis showed a significant difference based on age, location, and grade. The bioinformatics analysis supported our findings and showed consistent results with other miRNAs studies in the literature. The high expressions of miR-584 and miR-486-5p deserve further investigation.