Ethanol Decreases Negative Cell-cycle-regulating Proteins in a Head and Neck Squamous Cell Carcinoma Cell Line

Abstract

Epidemiologic studies have provided evidence of an alcohol-associated increased risk of upper aerodigestive tract cancers. Recently we reported ethanol-induced proliferation in a squamous cell carcinoma of the head and neck (SCCHN) cell line, but the underlying mechanisms are unknown. In order to further clarify these findings, major G0/G1-regulating proteins were investigated in the present study. Synchronized cells of a SCCHN line (JP-PA) and a human immortalized keratinocyte line (HaCaT)-used as a control-were cultured with or without 10(-3) M ethanol for up to 96 h. At distinct time intervals the expression of cyclin D1 and the inhibitors p16, p18, p19 and p21 were determined by Western blot analyses. In both lines ethanol had no influence on the protein expression of cyclin D1. In contrast, distinct downregulations of p21, p18 and p19 were detectable at the protein level. The p16 protein was not expressed in the SCCHN line and was unchanged in the control line after the addition of ethanol. In these in vitro experiments the marked downregulation of important cell-cycle inhibitors may accelerate progression from the G1 to the S phase of the cell cycle. The relevance of our findings to in vivo conditions remains speculative, but the observed mechanisms of significantly reduced expression of cell-cycle inhibitor proteins may be involved in the carcinogenesis of head and neck malignancies.

Discrimination of epithelium-like and fibroblast-like phenotypes derived from ethanol-treated immortalised human gingival keratinocytes in epithelial equivalents

“…To elucidate the morphological and molecular changes underlying the multistep process of oral carcinogenesis, but uncoupled from in vivo complexity, several in vitro studies have been conducted by employing cell cultures of ethanol-treated transformed keratinocytes. In recent investigations dealing with the molecular mechanisms of ethanol effects, a marked reduction of important cell cycle inhibitors, such as p16, p18 and p19, has been reported, whereas the expression of cyclin D1, which is important for the G1/S transition, remains unaffected (Hager et al 2001;Kornfehl et al 2002). In terminally transformed keratinocytes derived from OSCC, ethanol has been shown to increase cell proliferation, whereas on the other hand, the keratin profile suggests a reduction in cellular differentiation (Kornfehl et al 1999).…”

Association of p73 G4C14‐to‐A4T14 polymorphism with human papillomavirus type 16 status in squamous cell carcinoma of the head and neck in non‐Hispanic whites

“…Previous studies have shown that ethanol affects cell cycle regulation 48, 49, induces apoptosis 50, and inhibits DNA repair 51. It is thus plausible that an ethanol-mediated cellular response affects p73 activation and expression and that the p73 polymorphism plays a role in this mechanism, resulting in the difference in presence of HPV16.…”

INK4 Family —A promising target for ‘gene-regulating chemoprevention’ and ‘molecular-targeting prevention’ of cancer

“…There is a close association between chronic alcohol consumption and increased risk of cancer of the upper aerodigestive tract. A recent study elucidated that ethanol decreases p18 INK4c and p19 INK4d expression at the protein level in a head and neck squamous cell carcinoma cell line (12) (Fig. 2).…”