Head and Neck Pathology

, Volume 13, Issue 4, pp 635–642 | Cite as

Expanded Expression of Toll-Like Receptor 2 in Proliferative Verrucous Leukoplakia

  • Joon Koh
  • Zoya B. KuragoEmail author
Original Paper


Proliferative verrucous leukoplakia (PVL) is a premalignant condition of the oral mucosa with > 70% chance of progression to squamous cell carcinoma (SCC), while lacking the common risks and behavior seen in non-PVL oral squamous carcinogenesis. PVL follows a multi-stage slow, relentless and usually multifocal expansion of surface epithelial thickening that over time takes on a verrucous architecture, eventually leading to verrucous carcinoma and/or dysplasia followed by “conventional” SCC, a process that takes years and is notoriously difficult to manage. As mucosal surfaces and carcinomas arising at these sites, are colonized by microorganisms, host receptors for microbial products have received attention as potential contributors to carcinogenesis. Studies show that microbial pattern recognition toll-like receptor (TLR)2 in various epithelial cells is upregulated in premalignant lesions and in malignant cells and can activate oncogenic pathways. Because of the highly progressive nature of PVL, we examined TLR2 expression in well-characterized PVL samples by immunohistochemistry. We found that, similar to epithelial dysplasia and SCC, PVL keratinocytes throughout the epithelial thickness showed diffuse TLR2 expression even in early stage lesions prior to onset of dysplasia. In contrast, oral mucosal samples in the absence of hyperorothokeratosis or dysplasia, expressed TLR2 primarily in the basal and parabasal layers. Given the high rates of PVL transformation and the previously established pro-cancer role of high TLR2 expression in malignant oral squamous cells, it is important to determine how its’ expression and functions are regulated in the oral squamous epithelium, and what is the specific TLR2 role in carcinogenesis.


Proliferative verrucous leukoplakia PVL Verrucous hyperplasia Toll-like receptor 2 TLR2 Squamous epithelium Squamous cell carcinoma Oral cancer 



Cluster of differentiation 282




Extracellular signal regulated kinase






Hematoxylin and eosin


Human papillomavirus




Mitogen-activated protein kinase


Phosphate buffered saline


Proliferative verrucous leukoplakia


Squamous cell carcinoma


Toll-like receptor



We thank Ms. Regina Hand, histotechnologist at the Dental College of Georgia, for providing sections of archival specimens for the study. This study was supported by Augusta University Pilot Project Grant.

Compliance with Ethical Standards

Conflict of interest

Authors have no conflicts of interest to disclose.


  1. 1.
    International Agency for Research on Cancer: WHO classification of head and neck tumours, 4th ed. 2017;Lyon: IARC.Google Scholar
  2. 2.
    Castellsague X, Alemany L, Quer M, Halec G, Quiros B, Tous S, et al. HPV involvement in head and neck cancers: comprehensive assessment of biomarkers in 3680 patients. J Natl Cancer Inst. 2016;108(6):djv403. Scholar
  3. 3.
    Neville BWDD, Allen CM, Chi AC Oral and maxillofacial pathology, 4th ed. 2016;Amsterdam: Elsevier.Google Scholar
  4. 4.
    Hansen LS, Olson JA, Silverman S. Proliferative verrucous leukoplakia. A long-term study of thirty patients. Oral Surg Oral Med Oral Pathol. 1985;60(3):285–98.CrossRefGoogle Scholar
  5. 5.
    Gillenwater AM, Vigneswaran N, Fatani H, Saintigny P, El-Naggar AK. Proliferative verrucous leukoplakia: recognition and differentiation from conventional leukoplakia and mimics. Head Neck. 2014;36(11):1662–8. Scholar
  6. 6.
    Hooper SJ, Crean SJ, Fardy MJ, Lewis MA, Spratt DA, Wade WG, et al. A molecular analysis of the bacteria present within oral squamous cell carcinoma. J Med Microbiol. 2007;56(Pt 12):1651–9. Scholar
  7. 7.
    Hooper SJ, Wilson MJ, Crean SJ. Exploring the link between microorganisms and oral cancer: a systematic review of the literature. Head Neck. 2009;31(9):1228–39. Scholar
  8. 8.
    Pushalkar S, Ji X, Li Y, Estilo C, Yegnanarayana R, Singh B, et al. Comparison of oral microbiota in tumor and non-tumor tissues of patients with oral squamous cell carcinoma. BMC Microbiol. 2012;12:144. Scholar
  9. 9.
    Pushalkar S, Mane SP, Ji X, Li Y, Evans C, Crasta OR, et al. Microbial diversity in saliva of oral squamous cell carcinoma. FEMS Immunol Med Microbiol. 2011;61(3):269–77. Scholar
  10. 10.
    Schmidt BL, Kuczynski J, Bhattacharya A, Huey B, Corby PM, Queiroz EL, et al. Changes in abundance of oral microbiota associated with oral cancer. PLoS ONE. 2014;9(6):e98741. Scholar
  11. 11.
    Wang H, Funchain P, Bebek G, Altemus J, Zhang H, Niazi F, et al. Microbiomic differences in tumor and paired-normal tissue in head and neck squamous cell carcinomas. Genome Med. 2017;9(1):14. Scholar
  12. 12.
    Joly S, Compton LM, Pujol C, Kurago ZB, Guthmiller JM. Loss of human beta-defensin 1, 2, and 3 expression in oral squamous cell carcinoma. Oral Microbiol Immunol. 2009;24(5):353–60. Scholar
  13. 13.
    De Nardo D. Toll-like receptors: activation, signalling and transcriptional modulation. Cytokine. 2015;74(2):181–9. Scholar
  14. 14.
    Kawai T, Akira S. The role of pattern-recognition receptors in innate immunity: update on toll-like receptors. Nat Immunol. 2010;11(5):373–84. Scholar
  15. 15.
    Kurago ZB, Lam-ubol A, Stetsenko A, De La Mater C, Chen Y, Dawson DV. Lipopolysaccharide-squamous cell carcinoma-monocyte interactions induce cancer-supporting factors leading to rapid STAT3 activation. Head Neck Pathol. 2008;2(1):1–12. Scholar
  16. 16.
    Atretkhany KN, Drutskaya MS, Nedospasov SA, Grivennikov SI, Kuprash DV. Chemokines, cytokines and exosomes help tumors to shape inflammatory microenvironment. Pharmacol Ther. 2016;168:98–112. Scholar
  17. 17.
    Arjunan P, Meghil MM, Pi W, Xu J, Lang L, El-Awady A, et al. Oral pathobiont activates anti-apoptotic pathway, promoting both immune suppression and oncogenic cell proliferation. Sci Rep. 2018;8(1):16607. Scholar
  18. 18.
    Dajon M, Iribarren K, Cremer I. Toll-like receptor stimulation in cancer: a pro- and anti-tumor double-edged sword. Immunobiology. 2017;222(1):89–100. Scholar
  19. 19.
    Beasley NJ, Leek R, Alam M, Turley H, Cox GJ, Gatter K, et al. Hypoxia-inducible factors HIF-1alpha and HIF-2alpha in head and neck cancer: relationship to tumor biology and treatment outcome in surgically resected patients. Cancer Res. 2002;62(9):2493–7.PubMedGoogle Scholar
  20. 20.
    Chefetz I, Alvero AB, Holmberg JC, Lebowitz N, Craveiro V, Yang-Hartwich Y, et al. TLR2 enhances ovarian cancer stem cell self-renewal and promotes tumor repair and recurrence. Cell Cycle. 2013;12(3):511–21. Scholar
  21. 21.
    Kuo IH, Carpenter-Mendini A, Yoshida T, McGirt LY, Ivanov AI, Barnes KC, et al. Activation of epidermal toll-like receptor 2 enhances tight junction function: implications for atopic dermatitis and skin barrier repair. J Invest Dermatol. 2013;133(4):988–98. Scholar
  22. 22.
    Huhta H, Helminen O, Lehenkari PP, Saarnio J, Karttunen TJ, Kauppila JH. Toll-like receptors 1, 2, 4 and 6 in esophageal epithelium, Barrett’s esophagus, dysplasia and adenocarcinoma. Oncotarget. 2016;7(17):23658–67. Scholar
  23. 23.
    Chavarria-Velazquez CO, Torres-Martinez AC, Montano LF, Rendon-Huerta EP. TLR2 activation induced by H. pylori LPS promotes the differential expression of claudin-4, -6, -7 and -9 via either STAT3 and ERK1/2 in AGS cells. Immunobiology. 2018;223(1):38–48. Scholar
  24. 24.
    Palani CD, Ramanathapuram L, Lam-Ubol A, Kurago ZB. Toll-like receptor 2 induces adenosine receptor A2a and promotes human squamous carcinoma cell growth via extracellular signal regulated kinases (1/2). Oncotarget. 2018;9(6):6814–29.CrossRefGoogle Scholar
  25. 25.
    Basler K, Bergmann S, Heisig M, Naegel A, Zorn-Kruppa M, Brandner JM. The role of tight junctions in skin barrier function and dermal absorption. J Control Release. 2016;242:105–18. Scholar
  26. 26.
    Hanson PJ, Moran AP, Butler K. Paracellular permeability is increased by basal lipopolysaccharide in a primary culture of colonic epithelial cells; an effect prevented by an activator of Toll-like receptor-2. Innate Immun. 2011;17(3):269–82. Scholar
  27. 27.
    Kubinak JL, Round JL. Toll-like receptors promote mutually beneficial commensal-host interactions. PLoS Pathog. 2012;8(7):e1002785. Scholar
  28. 28.
    Tye H, Kennedy CL, Najdovska M, McLeod L, McCormack W, Hughes N, et al. STAT3-driven upregulation of TLR2 promotes gastric tumorigenesis independent of tumor inflammation. Cancer Cell. 2012;22(4):466–78. Scholar
  29. 29.
    Stack J, Doyle SL, Connolly DJ, Reinert LS, O’Keeffe KM, McLoughlin RM, et al. TRAM is required for TLR2 endosomal signaling to type I IFN induction. J Immunol. 2014;193(12):6090–102. Scholar
  30. 30.
    Scheeren FA, Kuo AH, van Weele LJ, Cai S, Glykofridis I, Sikandar SS, et al. A cell-intrinsic role for TLR2-MYD88 in intestinal and breast epithelia and oncogenesis. Nat Cell Biol. 2014;16(12):1238–48. Scholar
  31. 31.
    Pimentel-Nunes P, Afonso L, Lopes P, Roncon-Albuquerque R Jr, Goncalves N, Henrique R, et al. Increased expression of toll-like receptors (TLR) 2, 4 and 5 in gastric dysplasia. Pathol Oncol Res. 2011;17(3):677–83. Scholar
  32. 32.
    West AC, Tang K, Tye H, Yu L, Deng N, Najdovska M, et al. Identification of a TLR2-regulated gene signature associated with tumor cell growth in gastric cancer. Oncogene. 2017;36(36):5134–44. Scholar
  33. 33.
    Paarnio K, Vayrynen S, Klintrup K, Ohtonen P, Makinen MJ, Makela J, et al. Divergent expression of bacterial wall sensing Toll-like receptors 2 and 4 in colorectal cancer. World J Gastroenterol. 2017;23(26):4831–8. Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Dental College of GeorgiaAugusta UniversityAugustaUSA
  2. 2.Medical College of Georgia, Georgia Cancer CenterAugusta UniversityAugustaUSA

Personalised recommendations