MiR-590-5p promotes cisplatin resistance via targeting hMSH2 in ovarian cancer.

OBJECTIVE: The mechanisms of ovarian cancer generate chemotherapy resistance are still unclear. This study aimed to explore the role of microRNA (miR)-590-5p in regulating hMSH2 expression and cisplatin resistance in ovarian cancer. METHODS: MiR-590-5p was identified as a regulator of hMSH2 with miRDB database and Target Scan database. Then cisplatin sensitive cell line (SKOV3) and resistant cell line (SKOV3-DDP) of ovarian cancer were cultured for cell functional assay and molecular biology assay. The expression levels of MiR-590-5p and hMSH2 were compared between the two cell lines. Dual luciferase reporter assay was used to verify the targeted regulatory relationship between miR-590-5p and hMSH2. CCK-8 assay and cell apoptosis assay were utilized to assess the role of MiR-590-5p and hMSH2 in cell viability under cisplatin. RESULTS: The expression of hMSH2 was significantly decreased, and miR-590-5p was significantly up-regulated in SKOV3-DDP. Up-regulation of hMSH2 weakened the viability of SKOV3 and SKOV3-DDP cell under cisplatin. Transfection with miR­590-5p mimics reduced the expression of hMSH2 and enhanced the viability of ovarian cancer cells under cisplatin, whereas inhibition of miR­590-5p increased the expression of hMSH2, and decreased ovarian cancer cells' viability under cisplatin. Furthermore, luciferase reporter assay showed that hMSH2 was a direct target of miR-590-5p. CONCLUSION: The present study demonstrates that miR­590-5p promotes cisplatin resistance of ovarian cancer via negatively regulating hMSH2 expression. Inhibition of miR­590-5p decreases ovarian cancer cells' viability under cisplatin. Thus miR­590-5p and hMSH2 may serve as therapeutic targets for cisplatin resistant ovarian cancer.

hMSH2 coordinated with the expression of E2F1 promotes platinum response in epithelial ovarian cancer.

OBJECTIVE: To explore underlying mechanisms that regulate hMSH2 expression and drug susceptibility in epithelial ovarian cancer (EOC). METHODS: Using data from the Cancer Genome Atlas (TCGA) we used bioinformatical analysis to predict transcription factors (TFs) that potentially regulate hMSH2. RT-qPCR, Western blot, and luciferase assays were undertaken using ovarian cancer cell lines to verify the identified TF. Expressions of the TF were modulated using overexpression or knockdown, and the corresponding cellular responses to cisplatin were examined. RESULTS: The TF, E2F1, was found to regulate the hMSH2 gene. The expression level of E2F1 correlated with cisplatin susceptibility in vitro. Kaplan-Meier analysis of 77 patients with EOC showed that low E2F1 expression was associated with worse survival. CONCLUSIONS: To our knowledge, this is the first report of E2F1 regulated MSH2 expression playing a role in drug resistance of platinum-based treatments for patients with EOC. Further work is need to confirm our results.

Hypermethylation of mismatch repair gene hMSH2 associates with platinum-resistant disease in epithelial ovarian cancer.

PURPOSE: One major reason of the high mortality of epithelial ovarian cancer (EOC) is due to platinum-based chemotherapy resistance. Aberrant DNA methylation may be a potential mechanism underlying the development of platinum resistance in EOC. The purpose of this study is to discover potential aberrant DNA methylation that contributes to drug resistance. METHODS: By initially screening of 16 platinum-sensitive/resistant samples from EOC patients with reduced representation bisulfite sequencing (RRBS), the upstream region of the hMSH2 gene was discovered hypermethylated in the platinum-resistant group. The effect of hMSH2 methylation on the cellular response to cisplatin was explored by demethylation and knockdown assays in ovarian cancer cell line A2780. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry was employed to examine the methylation levels of hMSH2 upstream region in additional 40 EOC patient samples. RT-qPCR and IHC assay was used to detect the hMSH2 mRNA and protein expression in extended 150 patients. RESULTS: RRBS assay discovered an upstream region from - 1193 to - 1125 of hMSH2 was significant hypermethylated in resistant EOC patients (P = 1.06 × 10-14). In vitro analysis demonstrated that global demethylation increased cisplatin sensitivity along with a higher expression of the hMSH2 mRNA and protein. Knockdown hMSH2 reduced the cell sensitivity to cisplatin. MALDI-TOF mass spectrometry assay validated the strong association of hypermethylation of hMSH2 upstream region with platinum resistance. Spearman's correlation analysis revealed a significantly negative connection between methylation level of hMSH2 upstream region and its expression. The Kaplan-Meier analyses showed the high methylation of hMSH2 promoter region, and its low expressions are associated with worse survival. In multivariable models, hMSH2 low expression was an independent factor predicting poor outcome (P = 0.03, HR = 1.91, 95%CI = 1.85-2.31). CONCLUSION: The hypermethylation of hMSH2 upstream region is associated with platinum resistant in EOC, and low expression of hMSH2 may be an index for the poor prognosis.

Genetic polymorphisms in hMSH2 and hMLH1 genes are associated with prognosis in epithelial ovarian cancer patients.

OBJECTIVE: DNA mismatch repair deficiency is not only thought to promote tumorigenesis but is also suggested to be associated with platinum-based chemotherapy treatment. In this study, we investigated the effects of two genetic polymorphisms in the hMSH2 and hMLH1 genes on the risk of epithelial ovarian cancer and the clinical outcome of patients treated with platinum-based chemotherapy. METHODS: A case-control study was performed in 536 epithelial ovarian cancer patients and 532 control women. Genotypes of two polymorphisms were determined by the polymerase chain reaction/ligase detection reaction method. Pearson Chi-square test was used to evaluate genotype distributions and allele frequencies in the patients and controls. Kaplan-Meier survival curves, and univariate and multivariate Cox regression models were used to analyze the effect of polymorphisms on patients' prognoses. RESULTS: The genotype and allele frequencies of the rs2303428 and rs1800734 polymorphisms were not significantly different between the case and control groups. Compared with wild homozygous genotype, the presence of variant alleles (heterozygous and variant homozygous genotypes) did not affect the risk of developing epithelial ovarian cancer. However, survival analysis showed that the rs2303428 polymorphism was related to the prognosis of epithelial ovarian cancer patients. Compared with the TT genotype, patients carrying the C allele had a shorter progression-free survival during the 3- and 5-year follow-up (HR 1.41, 95% CI 1.07 to 1.87 and HR 1.56, 95% CI 1.12 to 2.16, respectively). For the rs1800734 polymorphism, the A allele may significantly increase patients' progression-free survival compared with the GG genotype in the 5-year follow-up (HR 0.66, 95% CI 0.44 to 0.98). CONCLUSION: Our research suggests that genetic polymorphisms in hMSH2 and hMLH1 may indicate the clinical progression of epithelial ovarian cancer patients treated with platinum-based chemotherapy.

Mismatch Repair Protein hMLH1, but not hMSH2, Enhances Estrogen-Induced Apoptosis of Colon Cancer Cells.

BACKGROUND: Epidemiological studies suggest a protective role of estrogen against colon carcinogenesis; this effect appears to be dependent on mismatch repair (MMR) status. However, the underlying mechanism remains unclear. This study investigated the role of MMR proteins in apoptosis of colon cancer cells in the presence or absence of estrogen. METHODS: Two major MMR proteins, human mutL homolog 1 (hMLH1) and mutS homolog 2 (hMSH2), as well as estrogen receptor-ß (ERß), were transiently expressed in either hMLH1-deficient HCT116 cells or hMSH2-deficient LoVo cells. Effects of estradiol on cell viability and apoptosis were assessed. Furthermore, we examined the apoptotic status of epithelial cells in colonic mucosa taken from previous healthy female subjects with menopausal syndrome before and after 6-month hormone replacement therapy (HRT). RESULTS: In hMLH1-deficient HCT116 cells, re-expression of hMLH1 led to a significantly decreased cell viability and increased apoptosis, which were further enhanced by estradiol, including marked increase of activated caspase-3 and caspase-9, as well as Bax and P53. The effect of hMLH1 overexpression in LoVo cells resulted in a similar increase in apoptosis that was greatly stimulated by estradiol. The enhanced apoptosis by hMLH1 and estradiol was further validated by FACS analyses of Annexin V expression. Re-expression of hMSH2 or overexpression of ERß in HCT116 cells also enhanced apoptosis; however, the effects were independent of estradiol. Furthermore, studies on healthy menopausal women before and after 6-month HRT demonstrated a significant HRT-mediated upregulation of the hMLH1 expression, with concomitant elevation of caspase-3 and caspase-9 activation in the colonic mucosa. CONCLUSION: We present the first evidence that hMLH1 and hMSH2 have similar but distinct roles in the apoptosis of colon cancer cells: an increased expression of either one can promote apoptosis, while only the effect of hMLH1 but not hMSH2 is estradiol-dependent. Our data suggest that MMR status should be assessed before hormone replacement therapy or future application of estrogen-based chemoprevention.

Inhibition of MicroRNA-21-5p Promotes the Radiation Sensitivity of Non-Small Cell Lung Cancer Through HMSH2.

BACKGROUND: This study aimed to explore the effects of microRNA-21-5p (miR-21-5p) on the radiation sensitivity of non-small cell lung cancer (NSCLC) and the involvement of human MutS homolog 2 (hMSH2) One hundred fourteen NSCLC patients at stage II or III who received surgery and postoperative radiotherapy were enrolled in this study. METHODS: The patients were assigned into radiation-sensitive and -insensitive groups. NSCLC A549 cells were transfected to generate control, Negative control (NC), miR-21-5p inhibitor, miR-21-5p mimic, small interfering hMSH2 (sihMSH2), miR-21-5p inhibitor + sihMSH2 and hMSH2 overexpression groups. Immunohistochemistry was performed to detect the hMSH2 expression in transfected and irradiated cells. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were performed to evaluate A549 miR-21-5p and hMSH2 expression in transfected and irradiated cells. A colony formation assay was adopted for cell survival analysis. The relationship between miR-21-5p and hMSH2 was verified by a luciferase reporter assay. Cell viability was measured by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and apoptosis was assessed by flow cytometry. NSCLC nude mouse models were established, and tumor volumes and tumor weights were recorded. RESULTS: The radiation-sensitive group of patients exhibited lower miR-21-5p but higher hMSH2 expression than the insensitive group. For irradiated A549 cells, lower cell survival, higher apoptosis, increased miR-21-5p expression and decreased hMSH2 expression were observed at 6 and 8 Gy than at 0, 2 and 4 Gy; compared to 6 Gy, cell survival and hMSH2 expression were decreased and apoptosis and miR-21-5p expression were increased at 8 Gy. Additionally, miR-21-5p was found to target hMSH2. Compared with the control group, the cell survival rate was lower and the apoptosis rate higher in the miR-21-5p inhibitor group, whereas the opposite was observed for the miR-21-5p mimic and sihMSH2 groups. For the mouse model, decreased tumor volume and tumor weight and higher hMSH2 expression were found in the miR-21-5p inhibitor, radiation, hMSH2 overexpression, miR-21-5p inhibitor + radiation and hMSH2 overexpression + radiation groups compared with the control group. In addition, tumor volume and tumor weight were decreased and hMSH2 expression increased in the miR-21-5p inhibitor + radiation and hMSH2 overexpression + radiation groups compared with the radiation alone group. CONCLUSION: These findings indicate that inhibition of miR-21 can promote the radiation sensitivity of NSCLC by targeting hMSH2.

Deficiency of hMLH1 and hMSH2 expression is a poor prognostic factor in Early Gastric Cancer (EGC).

Purpose: The aim of the study was to investigate the effect of deficiency of hMLH1 and hMSH2 expression on the prognosis of early gastric cancer (EGC) in Chinese populations. Methods: A total of 160 EGC patients who underwent curative gastrectomy with lymphadenectomy from January 2011 to July 2014 at Xinhua Hospital were evaluated. The expression rates of hMLH1 and hMSH2 were examined using tissues preserved in paraffin blocks by immunohistochemical staining. The clinicopathological characteristics and prognosis of EGC with deficient hMLH1 and hMSH2 were analyzed. Results: On immunohistochemical staining, the loss expression of hMLH1 and hMSH2 were observed in 89 (55.6%) and 45 (28.1%), respectively. The hMLH1 deficiency was associated with the middle third of tumor location (P = 0.041). According to Kaplan-Meier survival analysis and Log-Rank test, the loss expression of hMLH1 and hMSH2 were associated with worse survival than positive hMLH1 (HR = 0.247, 95% CI = 0.078-0.781, P = 0.017) and hMSH2 (HR = 0.174, 95% CI = 0.051-0.601, P = 0.006) in EGC. Conclusion: The main conclusions were as follows: The hMLH1 deficiency was preferred to the middle third of EGC. Lymph node metastasis (LNM) was a prognostic factor of EGC. And the prognosis of EGC patients with deficient mismatch repair (dMMR, mainly including deficient hMLH1 and hMSH2) was obviously worse than proficient mismatch repair (pMMR).

Epidermal growth factor receptor and epididymis invasion as prognostic biomarkers in clinical stage I testicular germ cell tumours.

BACKGROUND: Inguinal orchiectomy is curative in 70-80% of clinical stage I testicular germ cell tumours (CS I TGCT). The identification of patients who are at low risk of relapse is critical to avoid unnecessary treatment. The aim of this study is to explore EGFR, hMLH-1/hMSH-2 and microsatellite instability (MSI) as potential prognostic factors of recurrence in CS I TGCT. METHODS: Fifty-six CS I TGCT patients who underwent inguinal orchiectomy were included in this study. We analysed the relationship between clinicopathological and molecular factors with survival. Analysis of hMLH1, hMSH2 and EGFR expression was carried out by immunohistochemistry. Methylation status of the hMLH1 promoter was determined by pyrosequencing analysis in selected cases. EGFR exons 19, 20, 21 were analysed by PCR labeled-fragments and MSI status was determined using standard Multiplex MSI assays. RESULTS: Classical pathological factors such as lymphovascular invasion, high percentage of embryonal carcinoma, rete testis invasion or tumour size ≥4 cm showed a significant relationship with a higher risk of relapse. Additionally, it was found that an epididymis invasion proved to be a significant independent poor prognostic factor of recurrence (p = 0.001). hMLH1 or hMSH2 expression showed no significant association with risk of relapse and no MSI was found. EGFR expression was observed in 30.4% of samples and its expression was associated with higher risk of relapse (HR 3.5; 95% CI 1.3-9.8; p = 0.016). None of the cases presented EGFR kinase domain mutations. CONCLUSIONS: Epididymis invasion and EGFR expression, but not hMLH-1/hMSH-2 or MSI, could be potentially useful as new prognostic factors of recurrence for CS I TGCT.

HMSH2 and HMSH6 gene expression profiles in colorectal adenocarcinoma in patients up to 50 years of age.

Lynch syndrome, previously called hereditary non-polyposis colorectal cancer (HNPCC), is a major mortality threat. It is an autosomal dominant disease which is caused by a germline mutation in the DNA mismatch repair (MMR), especially in patients aged up to 50 years. Such mutation more frequently occurs in the hMSH2 gene (38-40%) and less frequently in the hMSH6 gene (14-16%). These mutations, when associated with the patient's lifestyle, may reveal a considerable variability in the disease manifestations, such as the degrees of penetrance and clinical aggressiveness. The aim of this study is to analyze the expression of DNA MMR genes, and correlate this expression with the clinical and anatomopathological findings of the neoplasia in patients aged between 39 and 49 years. A total of 45 patients were included: (48.9%) males and (51.1%) females, and they all underwent resection of a colorectal adenocarcinoma. The tissue microarray technique was used to analyze the relative and absolute expression of hMSH2 and hMSH6. Amsterdam II criteria for the diagnosis of HNPCC were obtained from the data provided by medical records and interviews with patients. hMSH2 and hMSH6 was expressed in all patients, which correlated between each other (RHO=0.669 and p<0.001) but not to age. There is a positive correlation between the expressions of males (RHO=0.673 and p=0.001) and females (RHO=0.006 and p<0.001). It is possible to evaluate the expression of MMR genes in embedded anatomopathological samples. Gene expressions correlated between each other and to the sex of the patients, but no difference in relation to age.

Mismatch repair.

Highly conserved MutS homologs (MSH) and MutL homologs (MLH/PMS) are the fundamental components of mismatch repair (MMR). After decades of debate, it appears clear that the MSH proteins initiate MMR by recognizing a mismatch and forming multiple extremely stable ATP-bound sliding clamps that diffuse without hydrolysis along the adjacent DNA. The function(s) of MLH/PMS proteins is less clear, although they too bind ATP and are targeted to MMR by MSH sliding clamps. Structural analysis combined with recent real-time single molecule and cellular imaging technologies are providing new and detailed insight into the thermal-driven motions that animate the complete MMR mechanism.

Usefulness of Immunohistochemistry for Microsatellite Instability Screening in Gastric Cancer.

BACKGROUND/AIMS: The usefulness of immunohistochemistry to screen for the microsatellite instability (MSI) phenotype in gastric cancer remains unclear. Moreover, the prognostic value of MSI phenotypes in gastric cancer has been debated. METHODS: The clinicopathologic parameters and survival outcomes of 203 MSI-high (MSI-H) and 261 microsatellite-stable (MSS) advanced gastric cancers (AGCs) were compared. Next, we compared the immunohistochemistry results for hMLH1 and hMSH2 with those of a polymerase chain reaction (PCR)-based method. Kaplan-Meier curves and a Cox proportional hazard regression model were used to conduct survival analyses. RESULTS: The MSI-H AGCs were correlated with older age (p<0.001), female gender (p=0.018), distal location (p<0.001), larger size (p=0.016), and intestinal type (p<0.001). Multivariate analysis revealed that the MSI-H phenotype was an independent favorable factor that was related to overall survival in patients with AGC (p<0.001). Compared with the PCR-based analysis, immunohistochemistry exhibited high sensitivity (91.1%) and specificity (98.5%) in the detection of MSI phenotypes. CONCLUSIONS: MSI-H gastric cancers have distinct clinicopathologic features and better prognoses, which suggests the necessity of MSI analysis in gastric cancer. Immunohistochemistry can be a useful and reliable screening method in the assessment of MSI status in gastric cancer.

Expression of human DNA mismatch-repair protein, hMSH2, in patients with oral lichen planus.

hMSH2 is one of the human DNA mismatch repair genes that plays an important role in reducing mutations and maintaining genomic stability. The aim of the present study was to detect the expression and significance of hMSH2 protein in patients with oral lichen planus (OLP). The expression levels of hMSH2 in the OLP group (n=51) and control group with normal oral mucosa (NM; n=40) were detected using an immunohistochemical method and subsequently assessed. The positive rate of hMSH2 expression in the OLP group was 52.94%, while the rate was 80% in the control group, exhibiting a statistically significant difference (χ2=7.1993; P<0.05). However, the expression of hMSH2 in the OLP tissues was not shown to significantly correlate with the patient gender, age and type of OLP (P>0.05). In conclusion, the protein expression levels of hMSH2 in the OLP tissues were significantly reduced as compared with that in the NM tissues, indicating that hMSH2 plays a role in the development of OLP. Therefore, hMSH2 may be used as a biomarker for evaluating the cancer risk of patients with OLP.

Usefulness of Immunohistochemistry for Microsatellite Instability Screening in Gastric Cancer

BACKGROUND/AIMS: The usefulness of immunohistochemistry to screen for the microsatellite instability (MSI) phenotype in gastric cancer remains unclear. Moreover, the prognostic value of MSI phenotypes in gastric cancer has been debated. METHODS: The clinicopathologic parameters and survival outcomes of 203 MSI-high (MSI-H) and 261 microsatellite-stable (MSS) advanced gastric cancers (AGCs) were compared. Next, we compared the immunohistochemistry results for hMLH1 and hMSH2 with those of a polymerase chain reaction (PCR)-based method. Kaplan-Meier curves and a Cox proportional hazard regression model were used to conduct survival analyses. RESULTS: The MSI-H AGCs were correlated with older age (p<0.001), female gender (p=0.018), distal location (p<0.001), larger size (p=0.016), and intestinal type (p<0.001). Multivariate analysis revealed that the MSI-H phenotype was an independent favorable factor that was related to overall survival in patients with AGC (p<0.001). Compared with the PCR-based analysis, immunohistochemistry exhibited high sensitivity (91.1%) and specificity (98.5%) in the detection of MSI phenotypes. CONCLUSIONS: MSI-H gastric cancers have distinct clinicopathologic features and better prognoses, which suggests the necessity of MSI analysis in gastric cancer. Immunohistochemistry can be a useful and reliable screening method in the assessment of MSI status in gastric cancer.

Expression and clinical significance of hMLH-1 and hMSH-2 in Han and Uygur in Xinjiang area of sporadic colorectal carcinoma / 临床与实验病理学杂志

Purpose To detect the incidence rate, average age and the expression of hMLH-1 and hMSH-2 of sporadic colorectal carci-noma ( SCC) with Han and Uygur patients. Methods The expression of hMLH-1 and hMSH-2 was detected in SCC for 60 cases of Uygur and 196 cases of Han by immunohistochemical method, including 60 Uygur and Han cases normal colorectal mucosa ( NCM) . Results The positive rate of hMLH-1 and hMSH-2 proteins expression in the NCM was 100%. There was a marked difference in the positive rate of hMLH-1 in SCC between Han (93. 4%, 183/196)and Uygur (75%, 45/60) (P0. 05). The average age of Han and Uygur SCC patients were 65. 64 years, 57. 63 years, respectively, and Uygur SCC cases were more likely to be diagnosed at less 40 years old (P<0. 05). The positive rate of hMLH-1 and hMSH-2 expression in the tubular adenoma was 100%. The positive rate of hMLH-1 and hMSH-2 expression in the tubulovillous adenoma in Uygur and Han were 66. 7%( 2/3 ) and 66. 7%( 2/3 ) , and 74. 2%(23/31) and 90. 3%(28/31), respectively, significantly lower than those of tubular adenoma (P<0. 05). The expression of hMLH-1 was positively correlated with that of hMSH-2 in SCC in Han(rs =0. 737, P<0. 05). The expression of hMLH-1 was positive-ly correlated with that of hMSH-2 in SCC in Uygur(rs =0. 383, P<0. 05). There exists marked difference in the positive rate of hM-LH-1 and hMSH-2 among difference age groups (P<0. 05). Conclusion There is a certain loss of hMLH-1 and hMSH-2 expression in SCC in Han and Uygur Chinese, which is related to adenoma and age. The expression of hMLH-1 in SCC tissue among Uygur pa-tients is not resemble to those of Han patients. The average age of Uygur SCC patients is younger than Han, and the positive rate of hMLH-1 is higher. Combined detection of hMLH-1 and hMSH-2 proteins may be used for judging the severity and prognosis of SCC in Xinjiang, which helps improve patients’ treatment program and rationalize their choices.

Targeting miR-21 enhances the sensitivity of human colon cancer HT-29 cells to chemoradiotherapy in vitro.

5-Fluorouracil (5-FU) is a classic chemotherapeutic drug that has been widely used for colorectal cancer treatment, but colorectal cancer cells are often resistant to primary or acquired 5-FU therapy. Several studies have shown that miR-21 is significantly elevated in colorectal cancer. This suggests that this miRNA might play a role in this resistance. In this study, we investigated this possibility and the possible mechanism underlying this role. We showed that forced expression of miR-21 significantly inhibited apoptosis, enhanced cell proliferation, invasion, and colony formation ability, promoted G1/S cell cycle transition and increased the resistance of tumor cells to 5-FU and X radiation in HT-29 colon cancer cells. Furthermore, knockdown of miR-21 reversed these effects on HT-29 cells and increased the sensitivity of HT-29/5-FU to 5-FU chemotherapy. Finally, we showed that miR-21 targeted the human mutS homolog2 (hMSH2), and indirectly regulated the expression of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD). These results demonstrate that miR-21 may play an important role in the 5-FU resistance of colon cancer cells.

Comparative study of mutations in SNP loci of K-RAS, hMLH1 and hMSH2 genes in neoplastic intestinal polyps and colorectal cancer.

AIM: To clarify the molecular mechanism involved in pathogenesis of colorectal cancer as well as clinical significance of genetic analysis of histological samples. METHODS: A total of 480 blood and tissue specimens were collected in our hospital from January 2011 to October 2012. In the observation group, there were 120 blood specimens and 120 intestinal tract tissue specimens collected from patients with neoplastic intestinal polyps. In the control group I there were 80 blood specimens and 80 intestinal tract tissue specimens collected from patients with colorectal cancer. In the control group II there were 40 blood specimens and 40 intestinal tract tissue specimens collected from healthy individuals. The gene segments were amplified using PCR and DNA gel electrophoresis along with DNA sequence analysis were employed for the detection of the following single nucleotide polymorphisms (SNPs): K-RAS codons 12 and 13; hMLH1 (human mutS homolog 1) gene missense mutation at Va1384Asp; hMSH2 (human mutS homolog 2) gene missense mutation at 2783C/A. RESULTS: The mutation rate of the SNP at Va1384Asp locus of the hMLH1 gene from blood and tissue specimens in the observation group showed no statistical difference from those in the control group I. The mutation rates of SNPs in codons 12 and 13 of K-RAS and at 2783C/A locus of the hMSH2 gene were significantly lower in the observation group than in the control group I (χ(2) = 15.476, 29.670, 10.811, 16.618, 33.538, 7.898, P < 0.05). The mutation rate of SNP at Va1384Asp locus of the hMLH1 gene was significantly higher in the observation group when compared to the control group II (χ(2) = 10.486, 4.876, P < 0.05). The mutation rates of SNPs in codons 12 and 13 of K-RAS and at 2783C/A locus of the hMSH2 gene did not show any statistical difference from those in the control group II. CONCLUSION: There may be important clinical significance and relevance between neoplastic intestinal polyps and colorectal cancer in terms of the mechanisms involved in the pathogenesis.

The study on the relationship between methylation of MGMT, hMSH2 gene promoters and protein ex-pression in glioma patients / 实用肿瘤学杂志

Objective To investigate the relevance between protein expression and methylation of MG-MT and hMSH2 in glioma patimts.Methods Immunohistochemical and methylation specific PCR were adopted respectively to test on 275 cases of glioma patients for the protein expression and methylation situation of MGMT and hMSH2.Results The negative protein expression rate of MGMT and hMSH 2 in the tissue of brain golima were 47.2% and 62.5% respectively;the occurrence of methylation in gene promoter region were accordingly 41.8% and 22.4%.Statistical analysis revealed that MGMT promoter methylation in peripheral blood gene groups was related with the protein negative expression of tumor tissue (P0.05).Conclusion The meth-ylation of MGMT is a common molecular situation in the generation of brain glioma ,which may be connected with that of tumor.However,hMSH2 promoter methylation might not the main reason for inactivation of hMSH 2 pro-tein,there may be other important factors affecting its expression .

Expression of hMLH1 and hMSH2 in suspected hereditary non-polyposis colorectal cancer / 实用医学杂志

Objective To analyse the suspected hereditary non-polyposis colorectal cancer (HNPCC) in mismatch repair protein (MMR) expression of hMLH1 and hMSH2. Methods Immunohistochemical staining method was used for the detection of hMLH1 and hMSH2 protein expression in 193 cases suspected HNPCC patients, the deletion of MMR proteins was identified as highly suspected HNPCC cases. Results Of the 193 patients with suspected HNPCC hMLH1/hMSH2 abnormal expression rate was 29.02%; ≤30 years old was 40%, 31 ~ 40 years old was 28.05%, 41 ~ 50 years old was 28.71%,3 suspected HNPCC showed the deletion of hMLH1/hMSH2 protein expression at the same time ,; In the right colon , the left half colon and rectal anomaly detection rates were 40.74%, 32.65%and 18.89%; hMLH1/hMSH2 deletion was 46.15%with family history. Conclusions The deletion of MMR protein is closely related to age,site and family history in suspected HNPCC, and the deletion of hMLH1 is an important factor to induce early-set colorectal cancer. The deletion of hMLH1/hMSH2 at the same time indicates that hMLH1/hMSH2 genes may play important role in the incidence of HNPCC.

Mismatch DNA repair mRNA expression profiles in oral melanin pigmentation lesion and hamartomatous polyp of a child with Peutz-Jeghers syndrome.

Mismatch DNA repair (MMR) mRNA expression analysis was performed on a biopsy of oral mucosa melanin pigmentation lesion, a hamartomatous polyp and peripheral blood derived from a 12-year-old child with Peutz-Jeghers Syndrome (PJS). We present a deficient MMR system, in a PJS patient, which demonstrated low mRNA levels of hMSH6 and hPMS2 and an increasing MMR deficiency from the non-dysplastic lesion to hamartomatous polyp of PJS with a high risk of cancer.

Expression of mismatch repair genes hMLH1 and hMSH2 and their significance in patients with colorectal carcinoma / 中国肿瘤临床

10.3969/j.issn.1000-8179.2013.12.007