An in vitro co-culture model of esophageal cells identifies ascorbic acid as a modulator of cell competition.
BACKGROUND
The evolutionary dynamics between interacting heterogeneous cell types are fundamental properties of neoplastic progression but can be difficult to measure and quantify. Cancers are heterogeneous mixtures of mutant clones but the direct effect of interactions between these clones is rarely documented. The implicit goal of most preventive interventions is to bias competition in favor of normal cells over neoplastic cells. However, this is rarely explicitly tested. Here we have developed a cell culture competition model to allow for direct observation of the effect of chemopreventive or therapeutic agents on two interacting cell types. We have examined competition between normal and Barrett's esophagus cell lines, in the hopes of identifying a system that could screen for potential chemopreventive agents.


METHODS
One fluorescently-labeled normal squamous esophageal cell line (EPC2-hTERT) was grown in competition with one of four Barrett's esophagus cell lines (CP-A, CP-B, CP-C, CP-D) under varying conditions and the outcome of competition measured over 14 days by flow cytometry.


RESULTS
We demonstrate that ascorbic acid (vitamin C) can help squamous cells outcompete Barrett's cells in this system. We are also able to show that ascorbic acid's boost to the relative fitness of squamous cells was increased in most cases by mimicking the pH conditions of gastrointestinal reflux in the lower esophagus.


CONCLUSIONS
This model is able to integrate differential fitness effects on various cell types, allowing us to simultaneously capture effects on interacting cell types without having to perform separate experiments. This model system may be used to screen for new classes of cancer prevention agents designed to modulate the competition between normal and neoplastic cells.
The Wistar Institute, 3601 Spruce St., Philadelphia, PA 19104, USA. lmf.merlo@gmail.com
Lauren M F
LM
Merlo
Rachelle E
RE
Kosoff
Kristin L
KL
Gardiner
Carlo C
CC
Maley
D017209:Apoptosis / Q000187:drug effects; D001205:Ascorbic Acid / Q000494:pharmacology*; D001471:Barrett Esophagus / Q000378:metabolism*; D002461:Cell Line, Transformed; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism*; D004947:Esophagus / Q000378:metabolism*; D006801:Humans
D004815:Epidermal Growth Factor; D001205:Ascorbic Acid