Mechanisms of cell transformation in the Syrian hamster embryo (SHE) cell transformation system

Current Status of Short-Term Tests for Evaluation of Genotoxicity, Mutagenicity, and Carcinogenicity of Environmental Chemicals and NCEs

The advent of the industrial revolution has seen a significant increase in the number of new chemical entities (NCEs) released in the environment. It becomes imperative to check the toxic potential of NCEs to nontarget species before they are released for commercial purposes because some of these may exert genotoxicity, mutagenicity, or carcinogenicity. Exposure to such compounds produces chemical changes in DNA, which are generally repaired by the DNA repair enzymes. However, DNA damage and its fixation may occur in the form of gene mutations, chromosomal damage, and numerical chromosomal changes and recombination. This may affect the incidence of heritable mutations in man and may be transferred to the progeny or lead to the development of cancer. Hence, adequate tests on NCEs have to be undertaken for the risk assessment and hazard prediction. Compounds that are positive in tests that detect such damages have the potential to be human mutagens/carcinogens. Only long-term animal bioassays, involving lifetime studies on animals, were used earlier to classify substances as mutagens/carcinogens. These tests were cumbersome and time consuming and required a lot of facilities and personnel. Short-term tests, therefore, were brought into practice. A "battery" of three to four of these short-term tests has been proposed now by a number of regulatory authorities for the classification of compounds as mutagenic or carcinogenic. This review deals with the current status of these short-term tests.

Three-dimensional cell culture array using magnetic force-based cell patterning for analysis of invasive capacity of BALB/3T3/v-src

A three-dimensional (3D) cell culture system has been fabricated using a magnetic force based cell patterning method, demonstrating a facile approach for the analysis of invasive capacity of BALB/3T3/v-src using an magnetic force and magnetite nanoparticles. The 3D cell patterning was performed using an external magnetic force and a pin holder, which enables the assembly of the magnetically labeled cells on the collagen gel-coated surface as array-like cell patterns, resulting in the development of a 3D in vitro culture model. The cells embedded in type I collagen showed a compacted, spheroid like configuration at each spot, and distinct, accelerated cell growth was observed in cancer model cells compared with the control cells. The developed 3D cell culture array was applied to the susceptibility assay of the GM6001 matrix metalloproteinase (MMP) inhibitor, a collagenase inhibitor; a distinct suppression of cell proliferation was observed, while little change was observed in 2D. The developed 3D cell culture array system is useful to assess the effects of pharmacologic and/or microenvironmental influences on tumor cell invasion.