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Abstract

It has been shown that several polychlorinated biphenyls are effective promoters of hepatocarcinogenesis in both mice and rats. In particular PCBs congeners with one or more chloro substituents in the ortho position showed no genotoxicity in a wide variety of short-term tests and may act by their inhibitory effect on intercellular communication. However, one mechanism in tumour promotion may involve the ability to cause cytotoxicity and necrosis. The cytotoxicity of 2,3,4,2',4',5', esachlorinated biphenyl was tested on two different murine cell lines, 3T3-L1, which undergoes adipose-like conversion at confluency and Balb/c 3T3 A31-1-1-1 which exhibits high chemically induced frequency of transformation, at different times of exposure and colorimetric assays. Results demonstrated that: (i) the colorimetric assays are correlated and at 24 hours showed the same toxicity of PCBesa on both cell lines, at 72 h a significant major sensitivity of A31-1-1 line and at seven days of exposure a recovery of the resistence of this line; (ii) the clonal efficiency test confirmed the mitogenic activity of PCBesa on 3T3-L1 cell line at the dose of 25 microgram/ml; (iii) a significant frequence of transformation of A31-1-1 cells treated with PCBesa 0.5 microgram/ml (non-cytotoxic dose). The presence of a significant number of foci type III in treated cells' plates confirmed the role of this compound in tumour promotion and the importance of epigenetic mechanisms in multistage carcinogenesis.

Additional information

Authors: GRIBALDO L, JRC Ispra (IT);MILANI R, JRC Ispra (IT);COLLOTTA A, JRC Ispra (IT);CATALANI P, JRC Ispra (IT);BALLS M, JRC Ispra (IT)
Bibliographic Reference: Paper presented: 41st International Congress of the ETCS, Verona (IT), October 9-12, 1994
Availability: Available from (1) as Paper EN 38710 ORA
Record Number: 199511073 / Last updated on: 1995-08-18
Category: PUBLICATION
Original language: en
Available languages: en