Involvement of the Toll-Like Receptor/Nitric Oxide Signaling Pathway in the Pathogenesis of Cervical Cancer Caused by High-Risk Human Papillomavirus Infection

Abstract

Human papillomavirus (HPV) can activate Toll-like receptor (TLR)/nitric oxide (NO) signaling pathways; however, whether the TLR/NO pathway is involved in cervical cancer caused by high-risk HPV (HR-HPV) remains unclear. In this study, 43 HR-HPV-positive patients with cervical cancer (CC group), 39 HR-HPV-positive patients with a healthy cervix (HR-HPV group), and 33 HR-HPV-negative controls were recruited. NO concentration in cervical canal and expression of inducible NO synthase (iNOS) in cervical tissues were detected. Expressions of key TLR/NO pathway genes (TLR3/4/7/8, NF-κB p65, and iNOS) in cervical epithelial cells were detected by quantitative reverse transcription PCR. Expressions of TLR4, NF-κB p65, and iNOS in CaSki, HeLa, and C33a cells were determined by Western blot. NO concentration in cervical canal of CC group was significantly higher than in other groups (P < 0.05). Positive rates of iNOS in cervical tissues were 72.1%, 28.2%, and 3.1% in the CC group, HR-HPV group, and controls, respectively (P < 0.05). Levels of TLR3, TLR4, TLR7, TLR8, NF-κB p65, and iNOS in cervical epithelial cells were higher in CC group than in other groups (P < 0.05). Both mRNA and protein levels of TLR4, NF-κB p65, and iNOS were higher in HPV-positive HeLa and CaSki cells than in HPV-negative C33a cells (P < 0.05). Together, these results suggest that TLR/NO signaling pathway may be involved in pathogenesis of cervical cancer caused by HR-HPV.

IL‐6 expression promoted by Poly(I:C) in cervical cancer cells regulates cytokine expression and recruitment of macrophages

“…Cervical cancer cells express TLR3 and are therefore one of the target cells of poly(I:C). 14 We examined the cytokine expression profiles of two different HPV-positive cervical cancer cells, HeLa (HPV18+) and Caski (HPV16+), and found that both cervical cancer cells highly expressed IL-6, which is consistent with previous studies. 15 IL-6 is a characteristic cytokine in cervical cancer, which is up-regulated in CIN III and during the tumour stage.…”

“…These results suggest that poly(I:C) is involved in the regulation between tumour cells and tumour-infiltrating macrophages in the local microenvironment of cervical cancer.Cervical cancer cells express TLR3 and are therefore one of the target cells of poly(I:C) 14. However, little is known about whether the topical application of poly(I:C) alters the local microenvironment of the tumour, thereby affecting the functional activity of the locally infiltrating immune cells.…”

The Interplay between Antiviral Signalling and Carcinogenesis in Human Papillomavirus Infections

“…While most studies using cell lines show an inhibition of the NF-κB pathway, in CIN and cervical cancer, HPV seems to induce the expression of inflammatory cytokines, which correlates with cancer progression [124,125]. A recent study has shown an increase of nitric oxide (NO) and inducible NO synthase (iNOS), which was suggested to be mediated by TLR-induced NF-κB signalling, in cervical samples from HR-HPV-infected patients [133]. Since NO is a critical component of the tumour microenvironment and promotes tumour angiogenesis, as well as tumour cell invasion and metastasis, it has been studied as a possible target for cancer therapy [134].…”

Viral Modulation of TLRs and Cytokines and the Related Immunotherapies for HPV-Associated Cancers

“…Therefore, TLRs seem to have dual functions in the tumor microenvironment, to the extent that even cancer cells may express those molecules in order to alter immune response and sustain malignant progression [ 3 , 10 ]. Indeed, recently, TLRs were showed to activate the nitric oxide signalling pathway, supporting cervical carcinogenesis [ 11 ].…”

“…As a consequence, lower levels are generally associated with a poor prognosis and cancer progression [ 8 , 12 , 13 ]. However, these receptors have also been correlated with malignancy [ 3 , 11 , 14 , 15 ]. TLR4 was found to be overexpressed in human cervical cancer line (HeLa) [ 11 , 14 ] as well as in premalignant and malignant specimens [ 16 ].…”