Mismatch repair hMSH2, hMLH1, hMSH6 and hPMS2 mRNA expression profiles in precancerous and cancerous urothelium

Dietary methyl donor nutrients, DNA mismatch repair polymorphisms, and risk of colorectal cancer based on microsatellite instability status

PURPOSE

Colorectal cancer (CRC) is a heterogeneous disease caused by complex interplay among the diet, the environment, and genetics involving numerous molecules and pathological pathways. This study aimed to determine whether methyl donor nutrients are associated with CRC and how these associations are altered by DNA mismatch repair (MMR) genes.

METHODS

In total, 626 cases and 838 age- and sex-matched controls were recruited for this case-control study. A validated food frequency questionnaire was used to assess seven methyl donor nutrients (vitamin B₂, niacin, B₆, folate, B₁₂, methionine, and choline). MMR polymorphisms were genotyped using an Illumina MEGA-Expanded Array. For the 626 patients, the microsatellite instability status and immunohistochemical expression of MMR proteins were analyzed. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Among the methyl donor nutrients, B₂, niacin, B₆, folate, and methionine were inversely associated with CRC risk, while a high intake of choline increased CRC. Regarding MMR genes, three hMSH3 polymorphisms (rs32952 A > C, rs41097 A > G, and rs245404 C > G) reduced CRC risk. Regarding gene-diet interactions, a stronger interaction effect was observed in G allele carriers of hMSH3 rs41097 with high niacin intake than in AA carriers with low niacin intake (OR, 95% CI = 0.49, 0.33-0.72, P for interaction = 0.02) in subgroups of patients with distal colon cancer (P for interaction = 0.008) and MMR proficiency with microsatellite stability (P for interaction = 0.021).

CONCLUSIONS

Methyl donor nutrients may affect CRC risk leading to a balance in the MMR machinery.

A Preliminary Study of NER and MMR Pathways Involved in Chemotherapy Response in Bladder Transitional Cell Carcinoma: Impact on progression-free survival

One of the main genotoxic drugs used in bladder cancer chemotherapy is cisplatin. While it is applied in most types of cancers, resistance to cisplatin is wildly common. In order to overcome drug resistance, it is necessary to determine a predictive marker. This study was conducted to provide basic data for selecting and designing a gene profile for further cohort and RCT studies in the future to improve response to treatment in bladder cancer. The expression levels of ERCC1, MLH1, MSH2, and CTR1 mRNA were determined in the tumor tissue using real-time q-PCR. Progression-free survival (PFS) was analyzed in term of the level of genes expression. The results revealed that the level of ERCC1 mRNA expression was higher in the recurrence (R) group compared to the no recurrence (NR) group. Moreover, the PFS time was increased in the patients with an ERCC1 expression level of below 1.57. The level of MLH1 and MSH2 mRNA expression was lower in the R group compared to the NR group; therefore, PFS time was increased in the patients with MLH1 and MSH2 gene expression levels above the cutoff point. While the level of CTR1 mRNA expression was higher in the R group versus the NR group, the PFS time was longer in the patients with CTR1 expression levels of below 1.265 compared to the patients with high levels of CTR1 expression. It can be concluded that the level of ERCC1, MLH1, MSH2, and CTR1 mRNA expression may be associated with PFS time as possible therapeutic targets for decreasing cisplatin resistance.

The Effect of NNK, A Tobacco Smoke Carcinogen, on the miRNA and Mismatch DNA Repair Expression Profiles in Lung and Head and Neck Squamous Cancer Cells

Tobacco smoking is a common risk factor for lung cancer and head and neck cancer. Molecular changes such as deregulation of miRNA expression have been linked to tobacco smoking in both types of cancer. Dysfunction of the Mismatch DNA repair (MMR) mechanism has also been associated with a poor prognosis of these cancers, while a cross-talk between specific miRNAs and MMR genes has been previously proposed. We hypothesized that exposure of lung and head and neck squamous cancer cells (NCI and FaDu, respectively) to tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is capable of altering the expression of MSH2 and MLH1, key MMR components, by promoting specific miRNA deregulation. We found that either a low (1 μM) or high (2 μM) dose of NNK induced significant upregulation of "oncomirs" miR-21 and miR-155 and downregulation of "tumor suppressor" miR-422a, as well as the reduction of MMR protein and mRNA expression, in NCI and FaDu, compared to controls. Inhibition of miR-21 restored the NNK-induced reduced MSH2 phenotype in both NCI and FaDu, indicating that miR-21 might contribute to MSH2 regulation. Finally, NNK exposure increased NCI and FaDu survival, promoting cancer cell progression. We provide novel findings that deregulated miR-21, miR-155, and miR-422a and MMR gene expression patterns may be valuable biomarkers for lung and head and neck squamous cell cancer progression in smokers.

Genomic Instability Promoted by Overexpression of Mismatch Repair Factors in Yeast: A Model for Understanding Cancer Progression

Mismatch repair (MMR) proteins act in spellchecker roles to excise misincorporation errors that occur during DNA replication. Curiously, large-scale analyses of a variety of cancers showed that increased expression of MMR proteins often correlated with tumor aggressiveness, metastasis, and early recurrence. To better understand these observations, we used The Cancer Genome Atlas and Gene Expression across Normal and Tumor tissue databases to analyze MMR protein expression in cancers. We found that the MMR genes MSH2 and MSH6 are overexpressed more frequently than MSH3, and that MSH2 and MSH6 are often cooverexpressed as a result of copy number amplifications of these genes. These observations encouraged us to test the effects of upregulating MMR protein levels in baker's yeast, where we can sensitively monitor genome instability phenotypes associated with cancer initiation and progression. Msh6 overexpression (two- to fourfold) almost completely disrupted mechanisms that prevent recombination between divergent DNA sequences by interacting with the DNA polymerase processivity clamp PCNA and by sequestering the Sgs1 helicase. Importantly, cooverexpression of Msh2 and Msh6 (∼eightfold) conferred, in a PCNA interaction-dependent manner, several genome instability phenotypes including increased mutation rate, increased sensitivity to the DNA replication inhibitor HU and the DNA-damaging agents MMS and 4-nitroquinoline N-oxide, and elevated loss-of-heterozygosity. Msh2 and Msh6 cooverexpression also altered the cell cycle distribution of exponentially growing cells, resulting in an increased fraction of unbudded cells, consistent with a larger percentage of cells in G1. These novel observations suggested that overexpression of MSH factors affected the integrity of the DNA replication fork, causing genome instability phenotypes that could be important for promoting cancer progression.

Diagnostic difficulties in cases of papillary urothelial neoplasm of low malignant potential, urothelial proliferation of uncertain malignant potential, urothelial dysplasia and urothelial papilloma: A review of current literature

Tumours of the urinary tract are the fifth most frequent type of cancer. The most common types are urothelial tumours, among which, non-invasive urothelial neoplasms represent 45% of all cases. The 2016 WHO classification of urinary tract tumours introduced new classifications of non-invasive lesions. Besides urothelial papilloma (UP) and papillary urothelial neoplasm of low malignant potential (PUNLMP), as described in the former classification, the new classification also includes new entities such as urothelial proliferation of uncertain malignant potential (UPUMP) and urothelial dysplasia (UD). Of the aforementioned, UPUMP is the lesion that most commonly progresses, but solely to non-invasive carcinomas. UD is associated with a high risk of progression to invasive carcinoma. Understanding the biological character, and establishing the correct differential diagnosis in cases of non-invasive, non-cancerous lesions of the urinary bladder, will be of importance in establishing outcome predictions for future patients. A systematic review of the current literature allows us to systematize genetic, morphologic and prognostic factors of such lesions. Moreover, the collected data provide the basis for a proposed diagnostic algorithm which facilitates quick and effective differential diagnoses in cases of non-invasive non-cancerous urinary bladder lesions.

Effect of rTsP53 on the M1/M2 activation of bone-marrow derived macrophage in vitro

We investigated that if rTsP53 could be used to activate bone-marrow derived macrophage (BMDM) into M2 macrophage and stop M1 macrophage activation. After 72 h incubation in blank culture medium, cells with PE-CCR7 (-) and FITC-CD206 (-) was extracted and its mean proportion was 92.30 ± 0.22%. With the stimulation of 20 μg/ml IFN-γ for 72 h, cells with PE-CCR7 (+) was extracted and its mean proportion was 16.24 ± 0.82%. With the stimulation of IL-3/IL-14 (both 10 μg/ml) for 72 h, cells with FICT-CD206 (+) was extracted and its mean proportion was 87.32 ± 4.29%. Co-incubation with different dose of rTsP53 (0.001 μg/ml, 0.01 μg/ml, 0.1 μg/ml, 1 μg/ml, 2 μg/ml, 5 μg/ml, 10 μg/ml, respectively) for 72 h, FITC-CD206 (+) macrophage was extracted. The mean proportion in each group was 1.09 ± 0.22%, 2.13 ± 0.13%, 4.91 ± 0.07%, 5.48 ± 0.29%, 9.81 ± 0.06%, 12.83 ± 0.55%, 17.87 ± 0.02%, respectively. The dose of rTsP53 was significantly positive correlated to the proportion of FITC-CD206 (+) macrophage. Co-incubation with 20 μg/ml IFN-γ and 5 μg/ml rTsP53 for 72 h, cells with PE-CCR7 (+) was extracted and its mean proportion was 10.60 ± 0.19%. Compared to that of mere co-incubation with IFN-γ, there was significant difference between the two groups. ELISA showed that Th1 cytokines' (IFN-γ, IL-6 and TNF-α) level decreased in the culture medium supernatant of BMDM co-incubated with rTsP53. There was negative correlation between the Th1 cytokines' level and the dose of rTsP53. Both Th2 cytokines (IL-4 and IL-13) and regulatory cytokines in the culture medium increased. There was positive correlation between the Th2 cytokines' level and the dose of rTsP53. There was also positive correlation between the regulatory cytokines' level and the dose of rTsP53. Compared to that of BMDM co-incubated with IFN-γ, levels of TNF-α and IL-6 were significant lower than that of BMDM co-incubated with both IFN-γ and rTsP53 (both P < 0.05), while the levels of IL-4 and TGF-β were significant higher (both P < 0.05). There was no significant difference in the levels of IL-13 and IL-10 between the two groups.

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.

DNA repair genes and prognosis in sporadic forms of urothelial carcinoma of the upper urinary tract

INTRODUCTION

Lynch syndrome or hereditary nonpolyposis colorectal cancer is caused by mutations in DNA repair genes, known as mismatch repair (MMR) genes, and is associated with microsatellite instability. Urothelial carcinoma of the renal pelvis is also associated with this syndrome. These genetic abnormalities have been described in sporadic forms of upper tract urothelial carcinoma (UTUC).

MATERIAL AND METHOD

This was a descriptive study and survival analysis of a series of 80 patients with sporadic UTUC with no metastases at diagnosis (N0/Nx M0) treated exclusively with nephroureterectomy. We evaluated the expression of MMR genes (hMLH1, hPMS2, hMSH2 and hMSH6) in sections performed with tissue microarray (TMA) and their association with clinical-pathological parameters. We analyzed the prognostic value of the loss of expression of these genes in UTUC.

RESULTS

We detected no loss of MSH2 or of MSH6, but there was a loss of MLH1 in 11 cases (13.8%) and of PMS2 in 21 cases (26.3%). The expression of hMLH1 and hPMS2 were strongly associated (P<.0001), and this phenotype expression entails significant clinical implications. The loss of MLH1 was associated with a low grade (P=.02). Loss of PMS2 was associated with a lower stage (P=.05), a pushing pattern with no invasive edges (P=.008) and less angiogenesis (P=.008). The inactivation of hPMS2 or hMLH1 is an independent protective factor (HR, 0.309) and, along with the histologic grade (HR, 5.561), defines the patients' prognosis.

CONCLUSION

In our experience, the inactivation of hPMS2 or hMLH1 is an independent marker of good prognosis and occurs in a quarter of sporadic UTUC cases. The immunohistochemical study of these patients can be used to assess the screening of hidden forms of Lynch syndrome.

Molecular characteristics of mismatch repair genes in sporadic colorectal tumors in Czech patients

BACKGROUND

Mismatch repair (MMR) genes are known to be frequently altered in colorectal cancer (CRC). Both genetics and epigenetics modifications seems to be relevant in this phenomenon, however it is still not clear how these two aspects are interconnected. The present study aimed at characterizing of epigenetic and gene expression profiles of MMR genes in sporadic CRC patients from the Czech Republic, a country with one of the highest incidences of this cancer all over Europe.

METHODS

Expression levels and CpG promoter methylation status of all MMR genes were evaluated in DNA from tumor and adjacent mucosal samples of 53 incident CRC patients.

RESULTS

We have found significantly increased transcription levels in EXO1 gene in tumor tissues (P = 0.05) and significant over-expression of MSH3 gene in colon tumors when compared to adjacent mucosal tissues (P = 0.02). Interestingly, almost all MMR genes were differently expressed when localization of tumors was compared. In particular, colon tumors showed an up-regulation of EXO1, MSH2, MSH3, MSH6, and PMS2 genes in comparison to rectal tumors (P = 0.02). Expression levels of all MMR genes positively correlated between each other. The promoter methylation of MLH1 gene was observed in 9% of CRC tissues only.

CONCLUSIONS

In our study, we have observed different pattern of MMR genes expression according to tumor localization. However, a lack of association between methylation in MMR genes and their corresponding expressions was noticed in this study, the relationship between these two aspects is worthy to be analyzed in larger population studies and in pre-malignant stages.

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.