An in vitro skin sensitization test based on THP-1 cell line / 中国比较医学杂志

Objective To establish an in vitro skin sensitization test,human cell line activation test (h-CLAT),based on THP-1 cell line (a human acute monocytic leukemia cell line),and to assess the sensitizing potency of plant raw materials of chemical and cosmetic products by this in vitro skin sensitization test.Method THP-1 cells were cultured in vitro and exposed to 11 reference skin sensitization chemicals and 9 samples,by monitoring the cell viability,cell surface marker CD54 /CD86 and relative fluorescence intensity of cells surface after the cells was exposures to the substances,and to discover whether there is a positive reaction.At the same time,Buehler test was used to validate the results of samples tested by h-CLAT.Results 11 reference chemicals were distinguished correctly by h-CLAT.Among the 9 samples tested,7 samples were recognized as negative sensitizer and 2 plant extracted substances were identified as suspicious skin sensitizer.The qualitative classification of the 9 samples by h-CLAT test was consistent with the results obtained by animal test.Conclusions The h-CLAT-in vitro test can be used to replace some animal tests for the prediction of soluble skin sensitizing substances.

Preliminary study for integrating DPRA with h-CLAT to predict skin sensitizers / 中国实验动物学报

Objective To establish a detection method integrating DPRA ( direct peptide reactivity assay) with h?CLAT ( human cell line activation test) to screen the skin sensitization potency of chemicals and plant extracts. Methods 12 chemicals and 7 plant extracts were chosen as the test substances. Firstly, the test substances were incubated together with two different peptides ( cysteine and lysine) respectively for reaction for 24 h. The peptide consumptions were analyzed by HPLC. Simultaneously, THP?1 cells were cultured in vitro and then exposed to different concentrations of test sub?stances for 24 h to examine the cell viability, cell surface markers CD54 and CD86 were assessed by flow cytometry. The predicting results were compared further between DPRA and h?CLAT. Results 12 chemicals were distinguished correctly by DPRA classified as 2 non?sensitizers and 10 sensitizers. The results of DPRA were in accordance with h?CLAT. Predic?ting the sensitization potency of plant extracts by DPRA showed that 6 plant extracts were determined as suspected sensiti?zers except for green tea extract. But using the method of h?CLAT, 4 plant extracts were examined as suspected sensitizers except for green tea extract, herba portulacae extract and ginseng fruit extract. The coherence of DPRA and h?CLAT was 0?57. Conclusion This detection method integrating DPRA with h?CLAT can predict single compound accurately. As for complex compound, it can achieve preliminary prediction and need other integrating methods to make a further identifica?tion.

Stability of XIST repression in relation to genomic imprinting following global genome demethylation in a human cell line

DNA methylation is essential in X chromosome inactivation and genomic imprinting, maintaining repression of XIST in the active X chromosome and monoallelic repression of imprinted genes. Disruption of the DNA methyltransferase genes DNMT1 and DNMT3B in the HCT116 cell line (DKO cells) leads to global DNA hypomethylation and biallelic expression of the imprinted gene IGF2 but does not lead to reactivation of XIST expression, suggesting that XIST repression is due to a more stable epigenetic mark than imprinting. To test this hypothesis, we induced acute hypomethylation in HCT116 cells by 5-aza-2′-deoxycytidine (5-aza-CdR) treatment (HCT116-5-aza-CdR) and compared that to DKO cells, evaluating DNA methylation by microarray and monitoring the expression of XIST and imprinted genes IGF2, H19, and PEG10. Whereas imprinted genes showed biallelic expression in HCT116-5-aza-CdR and DKO cells, the XIST locus was hypomethylated and weakly expressed only under acute hypomethylation conditions, indicating the importance of XIST repression in the active X to cell survival. Given that DNMT3A is the only active DNMT in DKO cells, it may be responsible for ensuring the repression of XIST in those cells. Taken together, our data suggest that XIST repression is more tightly controlled than genomic imprinting and, at least in part, is due to DNMT3A.

Transcriptional activity of the 5'-flanking region of the thyroid transcription factor-1 gene in human thyroid cell lines

Thyroid transcription factor-1 (TTF-1, NKX2-1) is a homeodomain-containing transcriptional factor that binds to and activates the promoters of thyroid and lung-specific genes, such as thyroglobulin, thyroid peroxidase, and thyroid stimulating hormone receptor. TTF-1 is known to play a key role in the development of the thyroid. However, the precise mechanism of TTF-1 gene transcription in human thyroid cells has not been studied. The expression of transcriptional activity in various lengths of the 5'-flanking region of the human TTF -1 gene was studied in TTF-1 positive and negative human thyroid cell lines. Increased transcriptional activity was observed in thyroid cell lines containing plasmids that coded for a sequence proximal to the transcription start site of exon 1 of the TTF-1 gene. However, we did not observe any difference in promoter activity in the region up to -2.6 kb from the proximal transcription start site of the TTF-1 gene between TTF-1 positive and negative cells. These results suggest that the proximal 5'-flanking region of the human TTF -1 gene does not contain sufficient cis-active regulatory information to direct gene expression in thyroid cells,and that other cis-or trans-acting factors participate in the thyroid specific gene expression of TTF-1.

No Evidence of the Productive Replication of Porcine Endogenous Retrovirus (PERV) from SNU Miniature Pigs in Human Cell Line / 감염과화학요법

BACKGROUND: The presence of porcine endogenous retrovirus (PERV) has been considered as one of the main hurdles to transplant pig's organs or tissues to human beings. There has been no report that PERV infection is associated with human diseases. Because pigs have their own characteristics of PERV according to pig strain, it is necessary to analyze the infectivity of PERV from SNU miniature pig to human cells for future utilization as a transplantation donor. MATERIALS AND METHODS: Human cell lines were infected with culture supernatant from porcine cell line or immunomodulator-stimulated peripheral blood mononuclear cells (PBMC) of SNU miniature pigs. They were also co-cultured with PBMC or islet cells of SNU miniature pigs. The presence of PERV genes and general pig marker gene in cells was determined by nested PCR with primer set for PERV pol and pig mitochondrial cytochrome oxidase II (COII), respectively. RESULTS: Infection test with the culture supernatant from PBMC of SNU miniature pigs showed that PERV pol but not COII was detected only in a few cases, but there was no uniform infection pattern in scope of stimulators and cell types. PERV pol was not demonstrated in co-cultures of human cell line with PBMC or islet cells from SNU miniature pigs after 80 days of co-cultures. CONCLUSIONS: In vitro infectivity test suggests that PERV from SNU miniature pig might not replicate productively in human cell lines although it could infect human cells and integrate into chromosome.

THE ESTABLISHMENT OF HGPRT MUTANT FROM HUMAN STOMACH GLANDULAR CARCINOMA (BGC 823) / 解剖学报

The wild type cells of human stomach glandular carcinoma, cell line BGC 823, were treated firstly by a chemical carcinogen (MNNG) for the induction of mutagenesis, then the cells were selected in medium with gradually increasing amount of 8-AG (8-azaguanine) from 1-20?g/ml. It was found that the mutant cells could grow vigorously in the medium containing 20?g/ml of 8-AG but not in HAT medium. The HGPRT assay showed an obvious quantitative difference between the wild type and HGPRT mutant cells of BGC 823.