TLR5 and TLR7 are differentially expressed in human papillomavirus-positive and negative base of tongue squamous cell carcinoma, and TLR7 may have an independent prognostic influence.

BACKGROUND: Human papillomavirus-positive (HPV+) base of tongue squamous cell carcinoma (BOTSCC) has a better outcome than corresponding HPV- cancer. TLR5 and TLR7 expression was previously shown to differ depending on HPV - status and correlate with outcome in oropharyngeal squamous cell carcinoma.

AIMS/OBJECTIVES: For validation, TLR5 and TLR7 were analyzed in a BOTSCC-cohort for correlation with HPV, survival, CD4+ and CD8+ tumor-infiltrating lymphocyte (TIL) counts, the latter being a well-documented prognostic marker.

MATERIALS AND METHODS: BOTSCC biopsies, (49HPV+/28HPV-) were analyzed by immunohistochemistry for TLR5 and TLR7, and correlated with the above parameters.

RESULTS: TLR5 expression was more frequently absent/weak than medium/strong in HPV+ compared to HPV- BOTSCC (p < .001). The opposite was observed for TLR7 (p < .007). TLR5 and TLR7 expression did not correlate to survival in either the HPV- or HPV+ cases, or to CD4+ TILs. TLR5, (but not TLR7) expression was correlated to CD8+ TIL counts (p = .023).

CONCLUSION AND SIGNIFICANCE: Absent/weak TLR5 and medium/strong TLR7 expression was validated as more frequent in HPV+ compared with HPV- BOTSCC. A correlation between CD8+ TIL counts, and TLR5 expression was disclosed, but not with TLR7. Therefore, it could be useful to investigate TLR7 further as a potential independent prognostic marker.