Downregulation of chromobox protein homolog 7 expression in multiple human cancer tissues / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between chromobox protein homolog 7 (cbx7) expression and the occurrence and development of colorectal carcinoma (CRC), gastric carcinoma (GC) and hepatocarcinoma (HCC) tissues.</p><p><b>METHODS</b>The samples of neoplastic tissues and the corresponding cutting-edge normal tissues from 22 cases of CRC, 20 cases of GC, 30 cases of HCC were surgically collected. Level of cbx7 mRNA was detected with a fluorescent quantitative RT-PCR assay, and the correlationship among expression of cbx7 mRNA, the patients' clinicopathologic features and the surviving time after surgery was analyzed.</p><p><b>RESULTS</b>The relative copy number of cbx7 mRNA in carcinomas and the normal tissues was 0.010 ± 0.015 vs 0.053 ± 0.042 for CRCs, 0.197 ± 0.195 vs 1.891 ± 1.254 for GCs, and 0.008 ± 0.008 vs 0.030 ± 0.021 for HCCs, respectively. Compared with the corresponding normal tissues, cbx7 expression was significantly downregulated in CRCs, GCs, and HCCs (t = -7.351, -5.417 and -6.680, respectively, P < 0.01). The expression of cbx7 mRNA in CRCs had significant differences not only between two age groups (the relative copy number of cbx7 mRNA in age > 55 group was 0.007 ± 0.015, but 0.017 ± 0.012 in age ≤ 55 group, t = -2.586, P = 0.022); but also between vascular embolus-positive and negative groups (the level of cbx7 mRNA in positive and negative group was 0.022 ± 0.021 vs 0.006 ± 0.011, t = -3.175, P = 0.010). The area under the receiver operating characteristics (ROC) curve is 0.769 (P = 0.033). when the Cut-off value of the relative copy number of cbx7 mRNA was 0.002 in CRCs. The values less-than 0.002 were defined as low expression. The CRC patients with low expression of cbx7 had a shorter overall survival time; whose 5 years survival rate was only 30.8% (4/13); while the rate was 77.8% (7/9) in high expression of cbx7 group. The difference had statistical significance (χ(2) = 4.329, P = 0.037). The similar differences could not be found among GC and HCC patients.</p><p><b>CONCLUSION</b>Downregulation of cbx7 expression was very common among multiple carcinomas cases, and the downregulation influenced the prognosis of CRC patients.</p>

Effects of methylation status of CpG islands on results of luciferase reporter assay / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of methylation status of CpG islands of endogenous E-cadherin (CDH1) gene on the promoter activity of corresponding genes in reporter assays.</p><p><b>METHODS</b>The methylation statuses of CpG island of CDH1 in 8 different cell lines were detected by methylation-specific PCR. CDH1 protein was analyzed by Western blotting. Two sets of pGL3 reporter vectors with different genotypes/haplotypes of the CDH1 promoter were constructed [ pGL3-A(-73)/-C(-73) pGL3-H1/-H4] and used to transfect these cell lines. The differences between these promoter reporter vectors were analyzed by t-test.</p><p><b>RESULTS</b>(1) CDH1 CpG island was unmethylated in AGS, MCF7, MKN74, and PC-3 cell lines, expressed in MCF7, MKN74, and PC-3, but not in AGS. Expression of CDH1 was silenced by methylation in HeLa, BGC823, A549, and RKO cell lines. (2) In the four CDH1-unmethylated MCF7, MKN74, PC-3, and AGS cell lines, the promoter activities of pGL3-C(-73), (as 0.78 +/- 0.10, 0.17 +/- 0.01, 0.11 +/- 0.01, 1.19 +/- 0.18) were significantly higher than those of pGL3-A(-73) (as 0.30 +/- 0.08, 0.07 +/- 0.01, 0.07 +/- 0.01, 0.39 +/- 0.04) (t values are -6.298, - 12.349, -8.128, -7.388, and P <. 0.1). However, in the four CDH1-methylated HeLa, BGC823, A549, and RKO cell lines, the promoter activity of pGL3-C(-73) (as 0.09 +/- 0.02, 0.13 +/- 0.02, 0.05 +/- 0.01, 0.01 +/- 0.00) was significantly lower than that of pGL3-A(-73) (as 0.16 +/- 0.01, 0.25 +/- 0.01, 0.11 +/- 0.03, 0.03 +/- 0.00) (t valued at 5.958, 11.189, 3.661, 13.866, and P<0.05). (3) In the unmethylated MKN74 and methylated RKO cell lines, the promoter activities of pGL3-H1/-H4 were obviously and contrarily different (as 1.57 +/- 0.23/0.94 +/- 0.06 and 0.38 +/- 0.02/0.50 +/- 0.04, t values were 4.577 and -4.915, P values were 0.010 and 0.003).</p><p><b>CONCLUSION</b>The methylation status of CpG island of the target gene in the tested cell lines affects the promoter activity in Reporter Assay significantly. The most active one may be the most suppressive one.</p>

Increase of saliva nitrate and nitrite level in patients with oral candidiasis / 中华预防医学杂志

<p><b>OBJECTIVE</b>To observe the alterations of saliva nitrate and nitrite level in patients with oral candidiasis.</p><p><b>METHODS</b>Parotid saliva and whole saliva were collected from 33 patients and 34 healthy volunteers. Concentrations of nitrate and nitrite in saliva were determined by high-performance liquid chromatography. Follow-up observation was performed on 10 patients after treatment. The data were statistically analyzed with independent-samples t test or paired-samples t test at alpha = 0.05.</p><p><b>RESULTS</b>There was significant increase of the concentrations and secretion rate of parotid saliva nitrate in patient group as compared with controls: (49.70 +/- 0.50) vs (21.51 +/- 0.60) mg/L (t = 2.692, P = 0.009) and (27.71 +/- 0.50) vs (12.55 +/- 0.60) microg/min (t = 2.554, P = 0.013), respectively. Significantly increased concentrations and secretion rate of nitrate and nitrite [nitrate: (6.46 +/- 0.94) vs (1.11 +/- 0.70) mg/L (t = 3.792, P = 0.000); nitrite: (8.48 +/- 0.58) vs (3.39 +/- 0.53) mg/L (t = 2.888, P = 0.005); nitrate secretion rate: (10.57 +/- 0.91) vs (2.10 +/- 0.74) microg/min (t = 3.464, P= 0.001); nitrite secretion rate: (13.91 +/- 0.55) vs (6.42 +/- 0.58) microg/min (t = 2.397, P = 0.020)] were revealed in whole saliva of patients group. Significantly decreased nitrate and nitrite levels were also observed in patients after treatment, especially the changes of parotid saliva nitrate secretion rate [(37.50 +/- 0.50) vs (14.34 +/- 0.64) microg/min (t = 3.142, P = 0.012)], whole saliva nitrate [(14.29 +/- 1.01) vs (2.59 +/- 1.03) mg/L (t = 3.475, P = 0.007)] and whole saliva nitrate secretion rate [(25.97 +/- 0.93) vs (4.12 +/- 1.00) microg/min (t = 3.922, P = 0.003)].</p><p><b>CONCLUSION</b>The present study revealed the significant increase of salivary nitrate and nitrite level in patients with oral candidiasis is considered to be associated with the host defense reaction.</p>

Detection of point mutation in an in vitro-selected amoxicillin-resistant strain of Helicobacter pylori / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between point mutation of penicillin-binding protein gene (pbp) and amoxicillin resistance (AMOgamma) of Helicobacter pylori (H. pylori) as well as to compare the protein profiles under proteomic technology to get the candidate resistance-related proteins.</p><p><b>METHODS</b>(1) AMOgamma strains were selected from the sensitive H. pylori strain 26695 by serial passage technique in vitro. (2) Point mutations of five putative resistance genes (HP0597, HP1565, HP1542, HP1556, and HP0160) were analyzed by denaturing high-performance liquid chromatography (DHPLC) and DNA sequencing. (3) Proteins samples were separated by two-dimensional electrophoresis (2-DE). Protein profiles were compared between the AMOgamma strain obtained in vitro and its sensitive parent strain 26695. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was performed to identify the proteins of interest. The proteins were searched by software MASCOT and identified by peptide fingerprint map using the program MS-FIT of Protein Prospect.</p><p><b>RESULTS</b>(1) An AMOgamma strain (MIC 8 microg/ml) was obtained. Complete loss of the resistant phenotype was observed after cultivation in the absence of AMO or storage at - 80 degrees C. (2) DHPLC and Sequencing result showed no point mutations in five pbp genes in the AMOgamma strain when compared with the corresponding PCR products from its parent strain 26695. (3) Protein profiling showed that eleven protein spots were differently expressed between 26695 and the AMOgamma strain. Of these protein spots in the AMOgamma strain, two new spots (Spot 1 and Spot 2) were observed with one (Spot 3) was up-regulated three-fold and the remained ones (Spot 4-11) were down-regulated.</p><p><b>CONCLUSION</b>AMO resistance of H. pylori might be resulted from, unstable phenotype change rather than point mutations of pbp genes. These differentially regulated proteins in AMOgamma strain might play a role in development of resistance to AMO in H. pylori.</p>

Aberrant methylation of APC and Bikunin CpG islands in sporadic breast carcinomas / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate relationship between methylation status of the APC and Bikunin CpG islands and clinicopathological characteristics of breast carcinomas.</p><p><b>METHODS</b>The methylation status of APC and Bikunin CpG islands in 152 sporadic breast carcinoma samples were analyzed by methylation specific PCR.</p><p><b>RESULTS</b>40.8% of breast carcinomas examined showed methylated signals for the APC. The methylation frequency of APC was significantly correlated to the tumor size (chi(2) = 4.041; P = 0.044), but not to patients' age, pathologic type of tumor, clinical stage, histological grade, lymph node metastasis and the status of estrogen or progestogen receptor. In addition, 24.6% of carcinoma samples examined revealed strong methylated signals for Bikunin. No significant correlation was found between the aberrant methylation of Bikunin and the clinicopathological characteristics of sporadic breast carcinomas.</p><p><b>CONCLUSION</b>The aberrant methylations of APC and Bikunin are frequent events during breast carcinogenesis. APC methylation might play a role in the progression of breast cancer.</p>

Quantification of methylation of SNCG CpG islands in human tissue samples by the combined COBRA-DHPLC assay / 中华预防医学杂志

<p><b>OBJECTIVE</b>To setup a quantitative assay for detection of methylation of SNCG CpG island in human tissue samples.</p><p><b>METHODS</b>Methylation status of the 16 tested CpG sites within the CpG island was analyzed by bisulfite-clone-sequencing for 2 gastric carcinoma cell lines, 2 normal gastric mucosa samples, and 2 pairs of primary gastric carcinomas and their corresponding non-neoplastic tissues, respectively.</p><p><b>RESULTS</b>The methylation of -88 and other four CpG sites was well correlated with the methylation of the overall CpG island. Thus, a combined bisulfite-restriction assay (COBRA) was developed based on the enzyme AciI, which digested the only one GCGG sequence in the PCR products of the methylated CpG island, but not the GTGG in the demethylated one. The digested fragments (144 bp and 85 bp) and undigested fragment (229 bp) could be completely separated by denaturing high performance liquid chromatography (DHPLC). According to the peak areas of these fragments, the proportion of the methylated copies of the SNCG CpG island was calculated easily. The result of the COBRA-DHPLC assay was reproducible and consistent with that of clone-sequencing.</p><p><b>CONCLUSION</b>A COBRA-DHPLC assay is setup successfully for quantification of methylation of the SNCG CpG island.</p>

Methylation specific binding activity of zinc finger protein Kaiso / 中华预防医学杂志

<p><b>OBJECTIVE</b>To compare binding activity of different zinc finger domain of human Kaiso with methylated CpG.</p><p><b>METHODS</b>pGEX constructs with different human Kaiso domain were generated and then corresponding fusion proteins were induced and purified. Electrophoretic mobility shift assays were applied to evaluate the binding activity of fusion proteins with methylated CpG.</p><p><b>RESULTS</b>The purified GST-KaisoZF fusion protein (without the POZ protein binding domain) could bind with methylated CpG probe specifically, but not for three or two zinc fingers without flanking domains.</p><p><b>CONCLUSION</b>Human zinc finger protein Kaiso could bind with methylated CpG specifically, only in the assistance of the neighboring flank sequence of the zinc finger domain.</p>

Analysis of demethylation-related HPV16 reactivation by DHPLC-primer extension assay / 中华预防医学杂志

<p><b>OBJECTIVE</b>To establish a sensitive assay to detect methylation status of the critical 7862nt CpG site related to transcription of HPV16 E6 and E7 genes.</p><p><b>METHODS</b>Genomic DNA of two HPV16-infected cell line SiHa and CaSki was extracted and modified by sodium bisulfite to convert the unmethylated Cs to Us (Ts in PCR products). The target sequence of HPV16 including the 7862nt CpG site was pre-amplified by PCR. Then, the methylation status of the 7862nt site was differentiated in a primer extension reaction with an HPV16-specific primer, and separated by DHPLC at 80 degrees C.</p><p><b>RESULTS</b>The primers without extension and with extension, whether matched to CpG or TpG, could be separated by DHPLC completely. The peak for ddTTP-extension products corresponding to the demethylated CpG site was observed at retention time 6.7 min in both cell lines. However, the peak for ddCTP-extension products representing the methylated CpG site could be detected at retention time 6.3 min in CaSki cell line only, which integrated with 499 methylated and one demethylated HPV16 copies.</p><p><b>CONCLUSION</b>The established DHPLC-primer extension assay can be used to detect methylated and demethylated HPV16 copies simultaneously with a sensitivity up to 1/500 (0.2%).</p>

Effect of selenium-enriched garlic on chronic gastritis of the glandular stomach of Mongolian gerbils induced by H. pylori / 中华预防医学杂志

<p><b>OBJECTIVE</b>To detect the therapeutic effect of selenium-enriched garlic (SeG) on chronic gastritis.</p><p><b>METHODS</b>Chronic gastritis was induced of the glandular stomach of male Mongolian Gerbils via gastric instillation of H. pylori TN2 strain once every 4 days for 5 consecutive times followed by random classification into six groups. Fresh SeG suspension was administrated daily at dosages of 4.70, 1.5, 0.47, 0.15 g.kg(-1).d(-1) for four weeks. The gerbils in the positive control group were treated with omeprazole, clarithromycin, and amoxicillin for one week. The gerbils were killed for pathological examination four weeks after SeG-treatment.</p><p><b>RESULTS</b>Chronic gastritis (CAG), low-grade dysplasia or gastric intraepithelial neoplasia (DYS/GIN) were observed among 77% and 38.5% of the 13 H. pylori-treated animals in the negative control group, respectively; whereas 40% and 26.7% in the positive control group (n = 15), respectively. The incidences of CAG and DYS/GIN in the SeG groups (n = 21 - 27) were reduced dose-dependently, 16.7% - 38.7% and 11.1% - 14.3% for CAG and DYS/GIN, respectively.</p><p><b>CONCLUSION</b>SeG administration inhibits the development and progression of CAG induced by H. pylori remarkably.</p>

Establishment of restriction landmark genome scanning for detection of genomic DNA methylation of tissues / 中华检验医学杂志

50 000 bp)was extracted from frozen gastric cancer tissue and their corresponding normal samples and used for RLGS assay.The genome DNA was digested by methylation-sensitive restriction enzyme Not Ⅰ, and labeled by radioisotope ~(32)p,then separated by two-dimensional electrophoresis and autoradiography. Experimental conditions for each step were optimized step by step.DNA fragment sequences for the dots on scanning profile were identified according to the human RLGS database.Results RLGS assay was set up and used to get the RLGS profiles of the representative tested samples successfully.These profiles can display more than 1 200 available dots averagely,the profiles of high quality DNA sample can display more than 1 800 dots which is the average level at an excellent RLGS lab,discrepant dots which had weaken or enhanced signals and their sequence information were obtained.The result can be reproduced.Conclusion The RLGS assay is established,stabilized for detection of DNA methylation of tissue samples.