Ethanol upregulates the expression of p21WAF1/CIP1 and prolongs G1 transition via a p53-independent pathway in human epithelial cells

Abstract

The control of cell cycle progression is necessary for accuracy in the replication of DNA and the distribution of genetic information to daughter cells. Disturbances in progression of the cell cycle may result in the loss of genomic integrity, a`hallmark' of cancer cells. Extensive consumption of alcoholic beverages is a risk factor associated with the development of various human epidermoid cancer including oral and pharyngeal squamous cell carcinomas. However, e ects of ethanol on cell cycle progression and on the expression of genes associated with the cell cycle have not been studied. We report here that exposure of human epithelial cells to ethanol, at concentrations (100 ± 200 mM) that do not cause cell death, (a) does not a ect or only reduces slightly the cellular level of p53 protein, (b) upregulates the transcription of the WAF1/CIP1 gene, (c) inhibits the Cdk2 activity, and (d) reduces the rate of cellular proliferation by inducing a delay in G 1 phase transition. The results also indicate that, at these non-cytotoxic concentrations, ethanol exhibits its e ects through a p53-independent mechanism.

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

“…Our data are quite contrary to a number of studies that reported that ethanol inhibits cell-cycle progression (4,5), induces apoptosis (3), inhibits DNA repair mechanisms (24) or induces the c-jun proto-oncogene (25). The experimental settings in our in vitro model were quiet different.…”

“…Cells were grown in the corresponding medium with or without the addition of 10 ¼ 3 M ethanol and 10:30 mmol:l acetaldehyde (which were routinely changed after 48 h), in accordance with recent studies (20,21). In order to avoid evaporation of ethanol:acetaldehyde, the culture dishes were tightly wrapped with Para lm ''M'' (American National Can, Greenwich, CT) immediately after the addition of ethanol (5). Unchanged ethanol concentration was determined after 48 h using gas chromatography (Chrompack) with silica fused carbowax capillary columns.…”

“…The staining procedure and measurements were performed according to standard protocols described elsewhere (5). Brie y, at indicated time intervals (Fig.…”

“…A correct interpretation of these studies with relevance to upper aerodigestive tract malignancies, which have a quite different tumorigenesis and biological behaviour than other epithelial and:or epidermal neoplasms, is dif cult (6 -8) because most in vitro studies were not performed with mucosa-derived keratinocytes [e.g. murine thymocytes (3), human lymphocytes (2,4) or colon carcinoma cells (5)]. …”

Inhibitors of Protein Geranylgeranyltransferase I and Rab Geranylgeranyltransferase Identified from a Library of Allenoate-derived Compounds

“…Transcriptional Reporter Assays-For the p21 CIP1/WAF1 promoter-luciferase assay, NIH3T3 cells were transfected with p21 CIP1/WAF1 promoter-luciferase or vector plasmids (both plasmids were provided by Dr. Genhong Cheng) (33). Cells were treated with GGTI compounds.…”