ABSTRACT
In a previous study, the present research group reported that males had a significantly higher prevalence of human papillomavirus (HPV)16 than females in oral rinse samples. The objective of the present study was to examine the relationship between HPV16 viral load and clinical factors, including remaining teeth, denture use and numbers of oral bacteria. A total of 124 patients (48 males and 76 females; mean age, 61.6 years; age range, 20-97 years) who visited the Department of Oral and Maxillofacial Reconstructive Surgery of Hiroshima University Hospital (Hiroshima, Japan) between November 2016 and August 2017 were analyzed. None of the patients had evidence of oral cancer or pre-malignant lesions, including epithelial dysplasia and leukoplakia. Quantitative polymerase chain reaction (qPCR) analysis was employed to examine the number of HPV16 viral copies. Furthermore, the number of oral bacteria was determined using the dielectrophoretic impedance measurement method. HPV16 was below the limit of detection in qPCR findings for samples obtained from 30 of the 124 subjects, thus the association of HPV16 viral copy number with clinical parameters was examined in the remaining 94 patients. The average number of HPV16 E6 DNA copies was 1.65±3.47 copies/cell (range, 0.07-25.3 copies/cell) and was significantly higher in subjects with a high oral bacteria count [≥106.5 colony forming unit (CFU)/ml] than in those with a low count (<106.5 CFU/ml) (0.79±0.98 vs. 2.06±4.11 copies/cell; P=0.030). The present results indicated that HPV16 viral load may be related to an increased bacterial number in the oral cavity. Further investigations are required to clarify the correlation between oral HPV load and oral hygiene status.
ABSTRACT
We previously found that CD44high/ESAlow head and neck squamous cell carcinoma (HNSCC) cells harboring high dihydropyrimidine dehydrogenase (DPD) expression exhibited potent resistance to 5-fluorouracil (5-FU)-induced apoptosis. In addition, susceptibility of HNSCC cells to 5-FU was compromised in the presence of cyclooxygenase 2 (COX2)-derived prostaglandin E2 (PGE2). In this study, we examined 5-FU-induced apoptosis in sorted cell populations (i.e., CD44high/ESAlow, CD44high/ESAhigh, and CD44low cells from the HNSCC cell line A-253) to clarify the anti-apoptotic effect of PGE2 on CD44high cells. Notably, CD44high/ESAlow cells upregulated PGE2, compared with other populations. To investigate the effect of CD44high/ESAlow cell-derived PGE2 on CD44high/ESAhigh cells, direct and indirect co-culture assays were performed. The percentage of apoptotic cells in a culture of CD44high/ESAhigh cells was significantly reduced when they were directly and indirectly co-cultured with CD44high/ESAlow cells. Furthermore, 5-FU-induced apoptosis of CD44high/ESAhigh cells was significantly increased in the presence of an inhibitor of the PGE2 receptors (EP1/EP2) when CD44high/ESAhigh cells were co-cultured with CD44high/ESAlow cells. These results suggest that CD44high/ESAlow cell-derived PGE2 may contribute to the inhibition of 5-FU-induced apoptosis in CD44high/ESAhigh cells. Additionally, NR4A2 knockdown enhances 5-FU-induced apoptosis in CD44high/ESAhigh cells, suggesting that PGE2 attenuates 5-FU-induced apoptosis in an NR4A2-dependent manner in CD44high/ESAhigh cells. In conclusion, CD44high/ESAlow cells contribute to induction of resistance to 5-FU in CD44high/ESAhigh cells through provision of PGE2. CD44high/ESAlow cell-targeted therapy may be effective in treatment of HNSCC.
