Differential gene expression profiles of DNA repair genes in esophageal cancer cells after X-ray irradiation / 癌症

<p><b>BACKGROUND AND OBJECTIVE</b>Various factors affect the radioresistance of tumor cells, with unknown molecular mechanism(s). Many genes have been found to associate with the radioresistance of tumor cells, however, the precise mechanism of these genes have not been elucidated. This paper was to analyze the differential expressions of DNA repair genes in esophageal carcinoma cells at different time after X-ray irradiation, and to investigate the role of these DNA repair genes in radiation resistance.</p><p><b>METHODS</b>Esophageal cancer parental cells Seg-1 were treated with continuous 2 Gy of fractionated irradiation until the total dose reached 60 Gy to establish the radioresistant cell line Seg-1R. Total RNA was extracted from each cell line at 0, 8, and 24 h after irradiation. Illumine Human-6 V3 microarray was used to identify differentially expressed genes between parental and radioresistant cells. Ten genes involved in DNA repair were obtained and their expressions at different time points after irradiation were analyzed by Gene Ontology analysis.</p><p><b>RESULTS</b>Ten DNA repair associated genes were found to be differentially expressed. Three of these genes, SLK, HMGB1, and PMS1, were not only differentially expressed between parental and radioresistant cell lines, but also expressed differently at different time points after irradiation in the same cell line.</p><p><b>CONCLUSIONS</b>PMS1 may be an important factor involved in the mechanism of radioresistance of esophageal carcinoma cells.</p>

Identification of differentially expressed genes related to radioresistance of human esophageal cancer cells / 癌症

<p><b>BACKGROUND AND OBJECTIVE</b>Radioresistant cells in esophageal cancer is one of the important reasons for the local failure of radiotherapy. In recent years, some researchers used gene chip technology to screen the differentially expressed genes between parental and radioresistant human esophageal cancer cells. But there were some problems in these studies, for example comparing cells at only one time interval, and genetic background not matching. In this study, we selected 3 different pairs of parental and radioresistant human esophageal cancer cells, and compared the gene expression profiles by cDNA microarray at 3 time intervals to identify and analyze the differentially expressed genes between parental and radioresistant human esophageal cancer cells.</p><p><b>METHODS</b>We compared the gene expression profiles between parental cells (TE13, Seg-1, Kyse170) and radioresistant cells (TE13R, Seg-1R, Kyse170R) before, and at 8 h and 24 h after irradiation with a cDNA microarray consisting of 48 000 genes (Human Genome). We identified differentially expressed genes by Pathway and GO analyses, and verified the differentially expressed genes LEF1 and CTNNB1 by RT-PCR.</p><p><b>RESULTS</b>A total of 460, 451, and 397 differentially expressed genes were found before, and at 8 h and 24 h after irradiation. After Pathway and GO analyses, 14 differentially expressed genes, participating in cell growth, apoptosis, cell cycle regulation, gene repair and signal transmission, were selected to further research. LEF1 and CTNNB1 were verified by RT-PCR, and the results were consistent with those of cDNA microarray.</p><p><b>CONCLUSIONS</b>The WNT signal pathway may be an important pathway participating in the formation of radioresistance of esophageal cancer cells. LEF1 and CTNNB1 may be the important genes causing the esophageal cancer cell radioresistance.</p>

Comparison of the major malformation rate of children conceived from cryopreserved embryos and fresh embryos / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cryopreserved embryo transfer has become indispensable in reproductive technology. More and more children are conceived from frozen-thawed embryo transfer (FET). The risk of birth defects associated with frozen-thawed embryo transfer has been evaluated and conflict results are obtained. The aim of this study was to compare the rate of major malformations in children conceived from cryopreserved embryos with that of children from fresh embryos.</p><p><b>METHODS</b>A retrospective analysis was performed on children conceived from frozen-thawed embryos and fresh embryos between January 2005 and December 2008 at the Reproduction Center of the Third Hospital, Peking University. The major malformation rates were compared between two groups for all children, as well as singletons or twins, separately. The frequencies of different subtypes of malformations classified according to different organ system were also compared.</p><p><b>RESULTS</b>Thirty-four of 3125 children from cryopreserved embryos had a major malformation. The malformation rate was 1.09%, which was comparable to that for children after fresh embryos transfer (1.53% (55/3604), OR: 0.71, 95%CI; 0.46-1.09). The malformation rate was also similar when the analysis was limited to children from cryopreserved embryos resulted from in vitro fertilization (IVF) (1.39%) and fresh IVF (1.3%). However, children from cryopreserved embryos resulted from intracytoplasmic sperm injections (ICSI) had much lower malformation rate than from fresh ICSI (0.63% vs.1.83%, OR: 0.34, 95%CI: 0.16-0.75). No difference was found in the incidence of major malformations in singletons from cryo ICSI (0.73%) and fresh ICSI (1.9%), or from cryo IVF (1.49%) and fresh IVF (1.67%). Similar malformation rate was found in multiples from cryo ICSI (0.52%) and fresh ICSI (1.76%), or cryo IVF (1.30%) and fresh IVF (0.90%). The distribution and risk of the subtype of malformations, such as cardiovascular, gastrointestinal, neural tube, urogenital, musculoskeletal and facial abnormalities was not different between the cryo group and fresh group.</p><p><b>CONCLUSIONS</b>The major malformation rate is similar between fetuses/children conceived from cryopreserved embryos and those from fresh embryos. Large prospective and long-term follow-up studies are needed to get exact results concerning the birth defects of the children born after cryopreserved embryos.</p>