Objective To investigate the association between genetic polymorphisms of cytochrome P450 MSP1 gene and the glutathione s-transferase GSTM1 gene in female workers exposed to aromatic solvents and spontaneous abortion. Methods A retrospective epidemiological investigation was carried out among 276 female workers including 58 female workers with history of spontaneous abortion and 218 female workers without spontaneous abortion selected in Yanshan of Beijing by the trained investigators using the unified questionnaire. Results The spontaneous abortion of female workers was significantly associated with GSTM1 (absent) (OR=2.07, 95% CI: 1.15-3.71), but not MSP1 (present) and exposure to aromatic solvent. After adust-ment for major confounders including education, age, shift work, body mass index, passive smoking and occupational stress, the multiple logistic regression analysis showed that GSTM1 gene (absent) significantly increased the risk of spontaneous abortion of female workers (OR=2.15, 95% CI: 1.17-3.98). Before and after adjustment for major confounders including education, age, shift work, body mass index, passive smoking and occupational stess, the multiple regression analysis showed that GSTM1 (absent) combined with MSP1 (heterozygous variant type / homozygous variant type) significantly increased the risk of spontaneous abortion (OR=2.98, 95% CI:l. 17-7.59), using the group with GSTM1 (present) and MSP1 (homozygous wild type) as reference group. Conclusion Our data suggested a genetic influence on spontaneous abortion in this population, GSTM1 (absent) was significantly associaled with spontaneous abortion, also provide evidence of additional joint action of gene MSP1 (heterozygous variant type and homozygous variant type) and GSTM1 (absent) to spontaneous abortion.

BACKGROUNDStudies have shown that the drug resistance of gastric cancer cells can be modulated by abnormal expression of microRNAs (miRNAs). We investigated the role of miR-503 in the development of cisplatin resistance in human gastric cancer cell lines.

METHODSMiR-503 expression was measured by quantitative real-time PCR. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) and clonogenic assays were used to examine changes in cell viability and the drug resistance phenotype of cancer cells associated with upregulation or downregulation of the miRNA. A dual-luciferase activity assay was used to verify target genes of miR-503. Immunohistochemistry, Western blotting analysis, and a flow cytometric apoptosis assay were used to elucidate the mechanism by which miR-503 modulates drug resistance in cancer cells.

RESULTSMiR-503 was significantly downregulated in gastric cancer tissues and several gastric cancer cell lines. Additionally, downregulation of miR-503 in the cisplatin (DDP)-resistant gastric cancer cell line SGC7901/DDP was concurrent with the upregulation of insulin-like growth factor-1 receptor (IGF1R) and B-cell lymphoma 2 (BCL2) expression compared with the parental SGC7901 cell line. An in vitro drug sensitivity assay showed that overexpression of miR-503 sensitized SGC7901/DDP cells to cisplatin. The luciferase activity of reporters driven by IGF1R and BCL2 3'-untranslated regions in SGC7901/DDP cells suggested that IGF1R and BCL2 were both direct target genes of miR-503. Enforced miR-503 expression in SGC7901/DDP cells reduced expression of the target proteins, inhibited proliferation, and sensitized the cells to DDP-induced apoptosis.

CONCLUSIONOur findings suggest that hsa-miR-503 modulates cisplatin resistance of human gastric cancer cells at least in part by targeting IGF1R and BCL2.

Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cisplatin ; pharmacology ; Humans ; Immunohistochemistry ; MicroRNAs ; genetics ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; Real-Time Polymerase Chain Reaction ; Stomach Neoplasms ; genetics