You are here:
Development of Normal Human Colonocyte Cultures to Identify the Carcinogenic Potential of Priorty Disinfection By-products
Citation:
JONES, C. AND A. B. DEANGELO. Development of Normal Human Colonocyte Cultures to Identify the Carcinogenic Potential of Priorty Disinfection By-products. Presented at 24th International Conference on Soils, Sediments and Water, October 20-23, 2008, University of Massachusetts, Amherst, MA, Amherst, MA, October 20 - 23, 2008.
Impact/Purpose:
24th International Conference on Soils, Sediments and Water, October 20-23, 2008, University of Massachusetts, Amherst, MA
Description:
Epidemiological studies have linked the consumption of disinfected surface waters to an increased risk of colorectal cancer. Of the approximately >600 disinfection byproducts (DBPs) identified, the US EPA regulates 11 DBPs for an increased risk of cancer. An in-depth mechanism-based structure activity analysis undertaken to rank the carcinogenic potential of the >600 DBPs, identified 50 unregulated DBPs with the highest potential for carcinogenicity. We set out to develop a in vitro/in vivo model system to test the potential of unregulated DBPs to transform normal human colon cells to a malignant state. Two DBPs identified as rodent carcinogens, bromochloroacetic and dichloroacetic acid, two priority DBPs, dibromonitromethane and tribromonitromethane, and the colon carcinogen, azoxymethane, were tested. Human colon mucosal cells (NCM460) were exposed to 1E-06 M (≥ 90% viability) of each test chemical for 10 days. Following chemical removal, the cells (monolayer) were maintained in the growth medium for 14-21 days. Cells growing in suspension (S fraction) were transferred to new flasks and grown for another 14-21 days. The process was repeated with suspended cells to generate an S1 fraction. These steps were necessary to deplete stem cells which have the capacity to grow in soft agar (Transformation Assay). The S1 fraction cells were grown in soft agar for 21-28 days. All of the treated S1 fractions formed colonies in the soft agar; S1 fractions from untreated cells did not form colonies. Colonies from each treatment were selected and propagated to provide cells to place into immunoincompetent mice (Tumor Formation Assay). Gene expression and immunohistochemical staining of the treated cells demonstrated activation of the WNT signaling pathway and Adherens Junction, activations important in the development of colon cancer. The characterization and validation of this model continues. (This is an abstract of a proposed presentation and does not necessarily reflect the opinion of the USEPA)