Streptococci–Human Papilloma Virus Interaction With Ethanol Exposure Leads to Keratinocyte Damage

PurposeEthanol, human papilloma virus (HPV), and poor oral hygiene are risk factors that have been attributed to oral carcinogenesis. Streptococci sp and HPV infections are common in the head and neck, often associated with sexual activity. Although HPV is linked to head and neck squamous cell carcinoma, it is unclear whether there is a similar role for Streptococci sp. This cell study examines whether Streptococci sp and HPV-16 with exposure to ethyl alcohol (ETOH) can act as cofactors in the malignant transformation of oral keratinocytes.Materials and MethodsETOH (0.1%-20% vol/vol) was used to investigate Streptococci sp attachment with immortalized E6-expressing HPV/HOK-16B cells, human oral buccal keratinocytes, and foreskin keratinocytes. Streptococci sp (Streptococci mutans [LT11]) and various strains of acetaldehyde (AA) producer and nonproducer Streptococcus salivarius (110-1, 109-2, 101-7, and 107-1) and a lactic acid producer bacterium, Lactobacillus rhamnosus (24-1 and 25-2), were examined for interactions with keratinocytes by use of a green dye (percent of cells with colonies after 24 hours). Carcinogens, AA, malondialdehyde, DNA damage, and proliferation (5′-bromo-2-deoxyuridine) among keratinocytes were also quantified.ResultsAA and malondialdehyde production from permissible Streptococci sp significantly increased with attachment to keratinocytes, whereas L rhamnosus did not significantly attach to keratinocytes. This attachment was associated with enhanced levels of AA adduct formation, proliferation (5′-bromo-2-deoxyuridine incorporation), and enhanced migration through integrin-coated basement membrane by HPV oral keratinocytes, which are characteristics of a malignant phenotype.ConclusionsThese cell studies suggest that oral Streptococci sp and HPV (HPV-16) cooperate to transform oral keratinocytes after low-level ETOH (1%) exposure. These results appear to suggest a significant clinical interaction, but further validation is warranted.