Scientific paper
Leptin stimulates esophageal adenocarcinoma growth by nonapoptotic mechanisms

https://doi.org/10.1016/j.amjsurg.2003.07.017Get rights and content

Abstract

Background

Leptin is a hormone primarily produced by adipocytes and serum leptin is elevated in obese persons. One risk factor associated with adenocarcinoma of the esophagus is obesity. We hypothesized that leptin would have stimulatory effects on esophageal adenocarcinoma and alter apoptosis in vitro.

Methods

Barrett's esophageal adenocarcinoma cells (BIC-1 and SEG-1) were cultured with human recombinant leptin (80 ng/mL) for 24 hours. Cell growth was determined by MTT assay. Apoptosis and necrosis was measured after 16 hours of treatment with leptin using a Cell Death Kit.

Results

Exogenous leptin stimulated cell proliferation in both cell lines. No changes in apoptosis or necrosis resulted between control and leptin-treated groups.

Conclusions

We have shown that leptin increases the proliferation of human esophageal adenocarcinoma, but does not alter cell apoptosis or necrosis. The data suggest that leptin stimulates esophageal adenocarcinoma growth by nonapoptotic mechanisms. Leptin antagonism may have potential efficacy in esophageal cancer therapy.

Section snippets

Cell culture and reagents

Human esophageal adenocarcinoma cells (BIC-1 and SEG-1) were derived from Barrett's-associated adenocarcinomas of the distal esophagus [13] and generously provided as a gift by David G. Beer (University of Michigan, Ann Arbor, Michigan). Cells were maintained as monolayers in DMEM media with L-glutamine (Gibco Invitrogen, Carlsbad, California), supplemented with 10% FBS (Biowhittaker, Walkersville, Maryland) and streptomycin (100 μg/mL), and maintained in humidified air at 5% CO2 in a 37°C

The MTT assay

The MTT colorimetric assay was performed to detect tumor cell viability after incubation. The MTT, a tetrazolium dye (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; thiazolyl blue [Sigma, St. Louis, Missouri]) was added to the each well as described previously [14]. Plates were incubated in the presence of MTT dye for 4 hours. Mitochondrial dehydrogenase activity reduced the yellow MTT dye to a purple formazan, which was then solubilized with acidified isopropanol and absorbance

Effect of leptin on cell proliferation

The effects of leptin on esophageal adenocarcinoma tumor cell growth were assessed. Tumor cells were treated with vehicle or human recombinant leptin in concentrations ranging from 0, 40, and 80 ng/mL, and the effects on cell growth were determined after 24 hours of treatment. Exogenous leptin stimulated cell proliferation in both cell lines as shown in Table 1. Administration of leptin at the 40 ng/mL concentration showed no significant change in proliferation for either cell type after 24

Comments

Adenocarcinomas of the esophagus have gained considerable interest recently owing to a rapid increase in reported cases [10]. Devesa et al [11] evaluated incidence trends in the United States and noted a 350% increase in the incidence of esophageal adenocarcinoma between 1976 and 1994. Others have estimated an average annual increase in incidence of 20.6% for the United States, with even higher incidence rates noted for Great Britain, Australia, and the Netherlands [15]. One risk factor that

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