Characteristics of benzo[a]pyrene and A-ring reduced 7,12-dimethyl benz[a]anthracene induced neoplastic transformation of human cells in vitro

Reproductive hazards of fire fighting. II. Chemical hazards

Studies of the health of fire fighters have historically focused on non-malignant respiratory disease and cancer. More recently, concerns have surfaced about reproductive health effects in many areas of the workforce, including fire fighting. These concerns prompted this review of chemical exposures that may contribute to adverse reproductive health outcomes in male as well as female fire fighters. A review of the industrial hygiene literature was undertaken to identify agents commonly found in fire smoke. These agents were then examined for evidence of reproductive toxicity or mutagenicity/carcinogenicity. This profile of chemical agents and their reproductive toxicities permits a qualitative determination that fire fighters are exposed to potential reproductive toxicants as a part of their normal fire fighting duties. Considerations for mitigating these risks are also discussed.

Cytotoxicity, anchorage-independent growth, and DNA adduct formation in human neonatal fibroblasts by 1,2,3,4-tetrahydro-7,12-dimethylbenz(a)-anthracene (TH-DMBA), its six aryl fluoro regioisomers, and an exo methylene tautomer

1,2,3,4-Tetrahydro-7,12-dimethylbenz(a)anthracene (TH-DMBA), its six possible fluorosubstituted regioisomers, and the C-7 exo methylene tautomer of the 11F derivative have been investigated for their cytotoxicity and for their ability to induce anchorage-independent growth and to form adducts in human neonatal foreskin fibroblasts. All compounds tested exhibited a low level of cytotoxicity, determined as percent cloning efficiency, up to a final concentration of 30 micrograms/ml. Except for 5F-TH-DMBA and the C-7 exo methylene tautomer, all compounds induced anchorage-independent growth of neonatal foreskin fibroblasts in soft agar at all concentrations tested (1, 3, 10 and 30 micrograms/ml). The C-7 exo methylene tautomer induced anchorage-independent growth only at a concentration of 10 micrograms/ml. Among the compounds tested the 6F derivative was the most effective compound at 1 microgram/ml. The D-ring fluoro isomers induced anchorage-independent growth at a frequency comparable to TH-DMBA itself, with the 11F derivative being the least effective of the four D-ring regioisomers. All compounds except 5F-TH-DMBA formed detectable adducts with cellular DNA as determined by 32P postlabeling procedures, when the cells were treated at 1 microgram/ml. Two adducts were detected in cells treated with TH-DMBA and four adducts were detected in DNA obtained from cells treated with 6F-TH-DMBA. The level of bonding for the D-ring fluoro isomers was quantitatively less and sometimes qualitatively different than that for TH-DMBA. For the D-ring compounds, the ability to induce anchorage-independent growth frequency correlated with the total quantity of adduct formed. The C-7 exo methylene tautomer formed a single adduct and the level of bonding was less than one adduct per 10(9) nucleotides. Analysis of these results led to the proposal that the planar anthracene ring structure (rings B, C, and D) of TH-DMBA and possibly oxidative metabolism at benzylic carbon 4 of the A-ring are important to DNA bonding and initiation of induction of anchorage-independent growth.

Conditions for transformation of human fibroblast cells: an overview

Low passage (low population doubling) human diploid fibroblasts respond to carcinogen and mutagen treatment, with higher passage level human cells remaining refractory to the insult. A cell cycle dependency for an optimize response to the carcinogen of competent responsive low passage cells is associated with early S phase. The process of fixation of the damage in dividing young cells could be more efficient due to intrinsic sensitivity of young cells towards carcinogens. However, specific DNA-carcinogen adduct analysis does not reveal any qualitative or quantitative difference. These low passage carcinogen initiated human cells progress towards the expression of a malignant phenotype. There is little evidence to suggest that these abnormal phenotypes exhibit an infinite lifespan using the selection pressures for isolation of the transformed phenotypes. However, the lifespan of these treated cells is extended beyond those of the untreated cells. In conclusion, criteria can be established to measure the expression of progression of these carcinogen initiated cells towards a malignant phenotype.

Neoplastic transformation of human diploid fibroblasts (KMST-6) by treatment with 60Co gamma rays

Normal fibroblasts (KMS-6) derived from a human embryo were transformed in culture into neoplastic cells (KMST-6) by repeated treatment with 60Co gamma ray irradiation. Repeated treatment was necessary to obtain transformation. Control normal cells exhibited normal karyotype (46, XX) and stopped dividing due to cellular ageing at the 40th passage. The transformed cells are presently growing indefinitely (140th passage) and exhibit prominent karyologic aberrations, both numerical and structural. These 2 characteristics, indefinite growth and abnormal karyotype, are thought to be the most important parameters for neoplastic transformation of human fibroblasts. Other indispensable parameters are the presence of active mitotic figures on confluent cell sheets and colony-type morphology. Transformed cells grow into colonies with relatively smooth edges, while normal fibroblasts form colonies with jagged edges, due to the protrusion of growing fibroblasts. Other parameters, such as elevated plating efficiency, enhanced colony formation in soft agar, low serum requirement for growth, high saturation density, and acquisition of transplantability, are not reliable in the early stages of transformation. These parameters probably appear at rather later stages of transformation following several cell divisions. Among other characteristics, the transformed KMST-6 cells exhibit a B-type isozyme pattern of glucose-6-phosphate dehydrogenase, lactate-dehydrogenase isozyme pattern of human origin, no evidence of viral infection and no production of C-type virus particles.

Differential growth response of normal human diploid fibroblasts and in vitro transformed human fibroblasts in serum-free defined culture medium

Two neoplastic human cell lines, WI-38 CT-1 and SUSM-1, which were transformed in vitro with gamma rays and 4-nitroquinoline 1-oxide, respectively, grew continuously in a serum-free defined medium. The defined medium used was a 1:1 mixture by volume of Dulbecco's modified Eagle's medium and Ham's F12 (DF) supplemented with 0.1% bovine serum albumin fraction V, 10 micrograms/ml of transferrin, 1 microgram/ml of insulin, and 5 micrograms/ml of oleic acid. In the case of SUSM-1, 100 micrograms/ml of fetuin were added to cultures when the cells were subcultured. Under these conditions the growth rates of the two transformed human cell lines were almost the same as those in a DF medium containing 10% fetal bovine serum (FBS). In addition, the defined medium permitted the cells to grow indefinitely without a lag period when they were transferred from serum-containing medium into this defined medium, indicating that no selection or adaptation of the cells had occurred. Interestingly, these cell lines did not require for their growth any polypeptide growth factors such as epidermal, platelet-derived or fibroblast growth factors. On the other hand, the control WI-38 cells stopped growing in the defined medium after about 2 divisions. Another control normal cell strain of fibroblasts derived from a human embryo showed a decreased growth rate in the defined medium as compared with that in the DF medium with 10% FBS. These results suggest that the defined medium described here is useful for the selective growth of human cells transformed in vitro after treatment with carcinogens from an untransformed cell population. In addition, the defined medium for transformed human cells should contribute to studies on their growth mechanisms.