Cytomorphology and Gene Expression Signatures of Anchorage-independent Aggregations of Oral Cancer Cells.

BACKGROUND/AIM: Cancer cells with high anchorage independence can survive and proliferate in the absence of adhesion to the extracellular matrix. Under anchorage-independent conditions, cancer cells adhere to each other and form aggregates to overcome various stresses. In this study, we investigated the cytomorphology and gene expression signatures of oral cancer cell aggregates. MATERIALS AND METHODS: Two oral cancer-derived cell lines, SAS and HSC-3 cells, were cultured in a low-attachment plate and their cytomorphologies were observed. The transcriptome between attached and detached SAS cells was examined using gene expression microarrays. Subsequently, gene enrichment analysis and Ingenuity Pathway Analysis were performed. Gene expression changes under attached, detached, and re-attached conditions were measured via RT-qPCR. RESULTS: While SAS cells formed multiple round-shaped aggregates, HSC-3 cells, which had lower anchorage independence, did not form aggregates efficiently. Each SAS cell in the aggregate was linked by desmosomes and tight junctions. Comparative transcriptomic analysis revealed 1,698 differentially expressed genes (DEGs) between attached and detached SAS cells. The DEGs were associated with various functions and processes, including cell adhesion. Moreover, under the detached condition, the expression of some epithelial genes (DSC3, DSP, CLDN1 and OCLN) were up-regulated. The changes in both cytomorphology and epithelial gene expression under the detached condition overall returned to their original ones when cells re-attached. CONCLUSION: The results suggest specific cytomorphological and gene expression changes in oral cancer cell aggregates. Our findings provide insights into the mechanisms underlying anchorage-independent oral cancer cell aggregation and reveal previously unknown potential diagnostic and therapeutic molecules.

Teratogenic Effects of Organohalogen Contaminants Extracted from Whale Bacon in a Whole-Rat-Embryo Culture System.

Marine foods can be contaminated with organochlorines and the risk to human beings who consume these foods needs to be evaluated. We examined the teratogenic effects of contaminants extracted from whale bacon on rat embryos using a whole-embryo culture system. Embryonic day 11.5 embryos were cultured for 48 h with organohalogens extracted from whale bacon at low (polychlorinated biphenyls (PCBs): 0.32 ppm, dichlorodiphenyltrichloroethanes (DDTs): 0.16 ppm, chlordanes (CHLs): 0.02 ppm) and high (PCBs: 2.15 ppm, DDTs: 1.99 ppm, CHLs: 0.20 ppm) doses. The levels of organohalogen compounds in cultured embryos were determined. The organochlorine contaminants extracted from whale products were readily transferred to the cultured rat embryos. The number of heartbeats, yolk sac circulation score, and embryonic body circulation score of embryos did not change during the culture period in either exposure group. Cultured embryos treated with the low-dose contaminated medium for 48 h showed abnormalities of the mandible, and craniofacial or forelimb hematomas with an incidence of 50%. All embryos treated with the high-dose medium showed craniofacial abnormalities and cleft lip, and limb abnormalities and hematomas. These results indicate that the organohalogen contaminants in whale bacon may be teratogenic in a dose-dependent manner. Further studies are necessary to determine the dose-effect relationship.

[History and movements of alternatives to animal experiments in Japan].

Experimental animals have been used so very often on science studies from the late 19th centuries. Especially since Wistar rat was produced in the 1890s as an experimental animal, various kinds of experimental animals have been developed and made enormous contribution to human beings. It is not an exaggeration to say that experimental animals have made us alive and rich, so to speak. However, the number of uses of experimental animals has decreased since its peak in 1990s. One of the reasons is the existence of Alternatives to animal experiments. Around 1980, Importance of 3Rs has been increased among its support, and the trend of animal experiments has moved to ones without using animals all over the world. It is because animal experiments cost and take time, but the biggest reason is the concern towards overuse of experimental animals. There is a rooting ethical doubt among many researchers that we can sacrifice other animals to save human lives. Human beings have hunted, and domesticated other animals as means of surviving. But today, we are trying to find a way to live not only for ourselves but for other animals on the whole earth. As a mean of the living, Alternatives to animal experiments have significant meanings and it will get even more important in the future. In this article, I would like to briefly explain the history and movements on Alternatives to animal experiments that took place here in Japan.

Comparative assessment of 24-hr primary skin irritation test and human patch test data with in vitro skin irritation tests according to OECD Test Guideline 439 (for quasi-drugs in Japan).

The Organisation for Economic Co-operation and Development (OECD) Test Guideline (TG) 439 is an in vitro test method of reconstructed human epidermis (RhE), which was developed for hazard identification of irritating chemicals in accordance with a primary skin irritation test using rabbits with 4-hr exposure. A regulation for quasi-drugs in Japan requires data from primary skin irritation tests using rabbits to undergo 24-hr exposure, and this is used as an evidence for 24-hr closed patch tests in humans. In this study with the same chemicals, primary skin irritation test data using rabbits undergoing 24-hr exposure and a 24-hr occlusive human patch test data were analyzed by comparing the results obtained with four test methods adopted in OECD TG 439. The performances of in vitro test methods showed a positive predictive value of 72.7-85.7% to predict the results of 24-hr primary rabbit skin irritation test knowing that its positive predictive value was 57.1% against humans only. The prediction factors of in vitro test methods were higher for the human patch test data with a sensitivity reaching 60 to 80%. Three surfactants gave false negatives in some of the RhE methods evaluated with the human patch test, but in each case, they were correctly classified as positive when evaluated at double concentration. Therefore, the approach of setting the margin to 2 was effective in eliminating false negatives. This suggests that in vitro test methods are useful for assessing skin irritation potential without animal testing for the application of quasi-drugs in Japan.

Thalidomide-induced limb abnormalities in a humanized CYP3A mouse model.

Thalidomide is a teratogen in humans but not in rodents. It causes multiple birth defects including malformations of limbs, ears, and other organs. However, the species-specific mechanism of thalidomide teratogenicity is not completely understood. Reproduction of the human teratogenicity of thalidomide in rodents has previously failed because of the lack of a model reflecting human drug metabolism. In addition, because the maternal metabolic effect cannot be eliminated, the migration of unchanged thalidomide to embryos is suppressed, and the metabolic activation is insufficient to develop teratogenicity. Previously, we generated transchromosomic mice containing a human cytochrome P450 (CYP) 3A cluster in which the endogenous mouse Cyp3a genes were deleted. Here, we determined whether human CYP3A or mouse Cyp3a enzyme expression was related to the species difference in a whole embryo culture system using humanized CYP3A mouse embryos. Thalidomide-treated embryos with the human CYP3A gene cluster showed limb abnormalities, and human CYP3A was expressed in the placenta, suggesting that human CYP3A in the placenta may contribute to the teratogenicity of thalidomide. These data suggest that the humanized CYP3A mouse is a useful model to predict embryonic toxicity in humans.

[Current status and future progress of reproductive/developmental toxicity test].

Currently, the European Centre for the Validation of Alternative Methods in the EU appears to be at the forefront of the development of alternative methods for developmental toxicity test (reproductive/developmental toxicity test). Why is it difficult to develop alternative methods for developmental toxicity test in comparison with other toxicity tests? In developmental toxicity test, chemical substances first enter the bloodstream and then reach the placenta via metabolism in the liver and other organs. After further metabolism in the placenta, chemical substances finally reach the fetus, where they affect fetal development. The difference in the in vivo route of chemical substances is an important reason for the difficulty in the establishment of new methods for developmental toxicologic test in comparison with general toxicity tests. According to the EU, the use of "in silico" techniques for developmental toxicity test may be difficult, and I agree with this. The in silico technique is basically a method for prediction of toxicologic effects from existing data, and cannot predict new effects, because data obtained by developmental toxicologic test are too complex. Three techniques are now being examined to overcome the difficulty in changing the method of developmental toxicologic test: the technique utilizing embryonic stem cells; micromass culture technique; and the whole embryonic culture technique. In this symposium, the current status of developmental toxicity tests and the three techniques being examined in the EU are introduced, and opinions on future progress are presented.