Elevated TLR5 expression in vivo and loss of NF-κΒ activation via TLR5 in vitro detected in HPV-negative oropharyngeal squamous cell carcinoma

• Published in: Experimental and molecular pathology 2020-06, Vol.114, p.104435-104435, Article 104435
• Main Authors: Kylmä, Anna Kaisa, Tolvanen, Tuomas Aleksi, Carpén, Timo, Haglund, Caj, Mäkitie, Antti, Mattila, Petri S., Grenman, Reidar, Jouhi, Lauri, Sorsa, Timo, Lehtonen, Sanna, Hagström, Jaana
• Format: Article
• Language: English
• Subjects: Human papillomavirus; Nuclear factor-κΒ; Oropharyngeal squamous cell carcinoma; Toll-like receptor
• ISSN: 0014-4800; 1096-0945
• DOI: 10.1016/j.yexmp.2020.104435

In oropharyngeal squamous cell carcinoma (OPSCC), the expression pattern of toll-like receptors (TLRs), in comparison between human papillomavirus (HPV)-positive and -negative tumors differs. TLRs control innate immune responses by activating, among others, the nuclear factor-κΒ (NF-κΒ) signaling pathway. Elevated NF-κΒ activity is detectable in several cancers and regulates cancer development and progression. We studied TLR5 expression in 143 unselected consecutive OPSCC tumors, and its relation to HPV-DNA and p16 status, clinicopathological parameters, and patient outcome, and studied TLR5 stimulation and consecutive NF-κB cascade activation in vitro in two human OPSCC cell lines and immortalized human keratinocytes (HaCat). Clinicopathological data came from hospital registries, and TLR5 immunoexpression was evaluated by immunohistochemistry. Flagellin served to stimulate TLR5 in cultured cells, followed by analysis of the activity of the NF-κB signaling cascade with In-Cell Western for IκΒ and p-IκΒ. High TLR5 expression was associated with poor disease-specific survival in HPV-positive OPSCC, which typically shows low TLR5 immunoexpression. High TLR5 immunoexpression was more common in HPV-negative OPSCC, known for its less-favorable prognosis. In vitro, we detected NF-κΒ cascade activation in the HPV-positive OPSCC cell line and in HaCat cells, but not in the HPV-negative OPSCC cell line. Our results suggest that elevated TLR5 immunoexpression may be related to reduced NF-κΒ activity in HPV-negative OPSCC. The possible prognosis-worsening mechanisms among these high-risk OPSCC patients however, require further evaluation. •High TLR5 expression was associated with poor DSS in HPV-positive OPSCC, typically showing low TLR5 immunoexpression.•High TLR5 immunoexpression was more common in HPV-negative OPSCC, known for its less-favorable prognosis.•In vitro stimulation of TLR5 with flagellin activated the NF-kB cascade in HPV-positive OPSCC cells and in HaCat cells.•No activation of the NF-kB cascade by TLR5 stimulation in HPV-negative OPSCC cells occurred.•Elevated TLR5 immunoexpression may be related to reduced NF-kB activity in HPV-negative OPSCC.