Comparison of threein vitroassays for carcinogen‐induced DNA damage

Abstract

DNA damage induced by five ultimate carcinogens and five procarcinogens was evaluated by three methods: (1) DNA strand breaks in Crandall feline kidney (CRFK) cells measured by alkaline sucrose gradient centrifugation; (2) unscheduled DNA synthesis (UDS) in CRFK, Syrian hamster embryo (SHE), and rat hepatocyte cultures measured by liquid scintillation counting; and (3) UDS in CRFK, SHE, and rat hepatocyte cultures measured by autoradiography. DNA strand breaks were observed with three procarcinogens and four ultimate carcinogens. Only two procarcinogens and two ultimate carcinogens could be identified by liquid scintillation counting. A positive autoradiographic response for UDS was observed in CRFK cells with four of five ultimate carcinogens and one procarcinogen. SHE cells showed a positive autoradiographic response for UDS with all ultimate carcinogens and three procarcinogens. The autoradiographic system with primary rat hepatocyte cultures was the only one in which a positive response for DNA damage was elicited for all 10 carcinogens.

Chemically‐induced unscheduled DNA synthesis in primary rat hepatocyte cultures: A comparison with bacterial mutagenicity using 218 compounds

“…Consequently, low levels of DNA repair may not be detected by autoradiography. Although liquid scintillation counting has been suggested as an alternate, more sensitive method for measuring DNA repair [21,45], the use of autoradiography has been found to be a superior means of identifying and quantifying UDS [21,25,39].…”

“…Although several laboratories [6,19,25,39,42,43,45] have shown the WC-DNA repair test to be selective against noncarcinogens and responsive to both procarcinogens and ultimate carcinogens, the number and variety of compounds tested in this assay remain somewhat limited. In order t o further identify the strengths and limitations of the HPC-DNA repair test, we have conducted this test using a relatively large number of compounds representing a wide variety of chemical classes.…”

Systematic Carcinogen Testing Through the Decision Point Approach

“…Both of these complications are overcome in the hepatocyte primary culture/DNA repair assay of Williams (73) which uses freshly isolated nondividing liver cells that can metabolize carcinogens and respond with DNA repair synthesis measured autoradio graphically. This assay has demonstrated substantial sensitivity and reliabil ity with activation-dependent procarcinogens (73,74). It also offers the advantages of expanded metabolic capability and biologic significance of the end point.…”

A computational method for the identification of new candidate carcinogenic and non-carcinogenic chemicals

“…Carcinogens can be further classified into procarcinogens and ultimate carcinogens based on whether the substance itself or its metabolite(s) is (are) carcinogenic to the human body. 9 Currently, many chemical compounds, such as radioactive compounds, 10 asbestos, 11 dioxin, 12 arsenic, 13 ethidium bromide, 14 formaldehyde 15 and benzopyrene, which is present in tobacco smoke, 16 have been reported to induce cancer, either directly or indirectly. Several databases have been established to better record and classify these potential carcinogens, and these include the IARC (International Agency for Research on Cancer, http://www.iarc.fr) database 17,18 and CPDB (Carcinogenic Potency Database).…”