Oral cancer is one of the most common cancers that affect public health with 500,000 new cases diagnosed yearly worldwide. The behavior of oral cancer might be affected by bacterial pathogens present in the oral cavity. The association between periodontitis, a chronic infection that affect the periodontium, and oral cancer have been reported in many studies. However, the effect of interaction between periodontal bacteria and oral cancer cells on cancer progression and aggressiveness is not well studied. Therefore, we aim to investigate the effect of four major periodontal bacteria on cancer cell pathology and treatment response. Three oral cancer cell lines OQ01, BHY and HN were used. Periodontal infection was represented by four periodontal bacteria Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Fusobacterium nucleatum. These bacteria were used to infect the oral cancer cells as polybacterial infection. Further analysis was done on OQ01 with monobacterial infection. The level of different cytokines (IL8 and TGF-β) were quantified in the culture supernatants after 6 and 24 h using ELISA. After RNA isolation from cell lysate, the relative changes in expression of six different oncogenes (MMP1, MMP9, MYC, JAk1, ZEB1, and STAT3) were measured using RT-PCR. To further investigate the role of F. nucleatum in inducing autophagy, three strains of F. nucleatum (Vincinti, Polymorphum and Periodontium) were used and the levels of autophagy markers (ATG7, ATG12 and ULK1) were measured after 6 and 24 hours. The effect of F. nucleatum on cancer cell invasion was was done starting from 4 h after infection. Statistical analysis was done using two-tailed Student's t-test OQ01 alone showed significantly enhance IL-8 secretion after polyinfection (P= 0.0003); however, enhanced TFG-β secretion was detected in all cell lines tested (P= 0.004). Polybacterial infection of oral cancer cell lines also upregulated MMP1 and MMP9 (P= 0.002) (known to enhance cancer cell invasiveness), ZEB1 (known to induce epithelial mesenchymal transition in cancer cells), and MYC, JAK1 and STAT3 (oncogenes involved in cell survival). Further analysis using OQ01 cells in monobacterial infection showed that F. nucleatum alone had the same or greater effect as polybacterial infection (P= 0.001). These results showed that F. nucleatum was the main periodontal bacteria responsible for inducing invasive phenotype in these oral cancer cells. In addition, F. nucleatum was able to enhance cancer cell invasion in vitro. Furthermore, F. nucleatum appear to upregulate autophagy markers in vitro which can lead to enhanced cancer cell survival and chemoresistance. This study demonstrated that the interaction between oral cancer cells and periodontal bacteria might be both cancer cell- and bacteria-specific. Our study can be highly useful in examining how modulating oral cancer environment can improve treatment outcome.
Citation Format: Amani Harrandah, Sasanka S. Chukkapalli, Ann Progulske-Fox, William Dunn, Kesavalu Lakshmyya, Edward K. Chan. F. nucleatum induces invasive phenotypes in oral cancer cells in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5139.