MSH2 Research Articles

A novel mouse model recapitulating the MMR-defective SCLC subtype uncovers an actionable sensitivity to immune checkpoint blockade.

Small cell lung cancer (SCLC) has an extremely poor prognosis. Despite high initial response rates to chemotherapy and modest survival improvements with the addition of immune checkpoint inhibitors (ICI), almost all patients experience relapse and fatal outcomes. Recent genomic insights uncovered extensive molecular heterogeneity in addition to the almost uniform loss of RB1 and TRP53. Additionally, defective DNA mismatch repair (MMR) has recently been described in some SCLC cases. Here, we generated a novel SCLC mouse model capturing MMR deficiency and assessed immunotherapy responses. We developed an MMR-deficient genetically engineered mouse model (GEMM) of SCLC by introducing a conditional Msh2 gene, crucial for maintaining MMR integrity, into the standard Rb1fl/fl;Trp53fl/fl (RP) model. Genomic characteristics and preclinical therapy responses were evaluated by focusing on overall survival and whole exome sequencing (WES) analyses. MMR-defective SCLC tumors (Rb1fl/fl;Trp53fl/fl;Msh2fl/fl (RPM)) developed later than tumors in MMR-proficient mice. However, the time from tumor manifestation to death of the affected animals was substantially shortened (median survival 55 days in RP vs. 46.5 days in RPM), indicating increased aggressiveness of MMR-defective tumors. RPM tumors exhibited MMR deficiency, high tumor mutational burden (TMB), and an elevated load of candidate neoantigens, compared to RP lesions (p = 0.0106), suggesting increased immunogenicity. Importantly, the overall survival of RPM animals was significantly improved when exposed to ICI. We propose a novel RPM mouse model as a suitable system to mimic MMR-defective SCLC and tumors with high TMB. We provide in vivo evidence that Msh2 deficiency enhances ICI sensitivity. These findings could contribute to stratifying SCLC patients to immunotherapy, thereby improving treatment outcomes.

Association of multilocus sequence typing, MSH2 gene mutations, and antifungal resistance in Candida glabrata: implications for clinical outcomes in Chinese hospitals

BackgroundCandida glabrata is the second most common cause of invasive candidiasis worldwide. In this study, we determined the clinical characteristics and drug sensitivity of C. glabrata isolates and investigated the associations between MSH2 gene mutations, sequence types (ST), and drug resistance.MethodsA total of 154 C. glabrata isolates were collected from patients being treated in three hospitals in China. The antifungal sensitivity of the strains was assessed using the broth microdilution method. Multilocus sequence typing (MLST) was also performed, followed by MSH2 sequencing. The clinical features and outcomes of C. glabrata infection were analysed for a total of 49 strains, which were collected from patients with invasive Candida infection at Longhua Hospital.ResultsAll 154 isolates were found to be susceptible to amphotericin, 5-fluorocytosine, anidulafungin, caspofungin, and micafungin, whereas 11.7% were fluconazole-resistant, 18.8% were itraconazole non-wild type, and 35.7% were voriconazole non-wild type. ST7 (62.34%) was the most common ST genotype, followed by ST10 (16.88%) and ST15 (7.79%). The total azole resistance rates for all isolates, ST7, ST10, and other STs were 36.4, 42.7, 34.6, and 18.8%, respectively. The ST7 and ST10 isolates were characterised by a higher drug resistance rate than the other minor ST isolates. Moreover, 59.09% of isolates had one or more MSH2 non-synonymous mutations, with V239L being the most commonly detected mutation. The frequency of MSH2 mutations was significantly higher in azole-resistant isolates than in other isolates, whereas P6L or L87P mutations were associated with the highest azole resistance rates of up to 87.5% and 80%, respectively. Our results indicated that ST7 and ST15 are independent predictors of mortality caused by C. glabrata infection and revealed a higher 30-day mortality in patients infected with these strains than in those infected with other ST isolates.ConclusionsOur findings revealed the relationships between MLST, MSH2 gene mutations, and drug resistance in the common pathogenic fungus C. glabrata, and thereby enabled us to identify strains that are associated with higher rates of mortality. These findings will contribute to enhancing our understanding of the pathogenesis of C. glabrata infection.

Germline Variants in DNA Interstrand-Cross Link Repair Genes May Contribute to Increased Susceptibility for Serrated Polyposis Syndrome.

Serrated polyposis syndrome (SPS) is characterized by the development of multiple colorectal serrated polyps and increased predisposition to colorectal cancer (CRC). However, the molecular basis of SPS, especially in cases presenting family history of SPS and/or polyps and/or CRC in first-degree relatives (SPS-FHP/CRC), is still poorly understood. In a previous study, we proposed the existence of two molecular entities amongst SPS-FHP/CRC families, proximal/whole-colon and distal SPS-FHP/CRC, according to the preferential location of lesions and somatic events involved in tumor initiation. In the present study, we aimed to investigate these distinct subgroups of SPS patients in a larger cohort at the germline level and to identify the genetic defects underlying an inherited susceptibility for these two entities. Next-generation sequencing was performed using multigene analysis with a custom-designed panel in a Miseq platform in 60 SPS patients (with and without/unknown FHP/CRC). We found germline pathogenic variants in 6/60 patients (ATM, FANCM, MITF, RAD50, RAD51C, and RNF43). We also found variants of unknown significance (VUS), with prediction of probable damaging effect in 23/60 patients (ATM, BLM, BRCA1, FAN1, ERCC2, ERCC3, FANCA, FANCD2, FANCL, MSH2, MSH6, NTHL1, PALB2, PDGFRA, PMS2, PTCH1, RAD51C, RAD51D, RECQL4, TSC2, WRN, and XRCC5 genes). Most variants were detected in gene coding for proteins of the Fanconi Anemia (FA) pathway involved in the DNA Interstrand-Cross Link repair (ICLR). Notably, variants in ICLR genes were significantly more frequent in the proximal/whole-colon than in the distal subgroup [15/44 (34%) vs 1/16 (6%), p = 0.025], as opposed to the non-ICLR genes that were slightly more frequent in the distal group [8/44 (18%) vs. 5/16 (31%), p > 0.05]. Germline defects in the DNA-ICLR genes may contribute to increased serrated colorectal polyps/carcinoma risk in SPS patients, particularly in proximal/whole-colon SPS. The inclusion of DNA-ICLR genes in the genetic diagnosis of SPS patients, mainly in those with proximal/whole-colon lesions, should be considered and validated by other studies. In addition, patients with germline defects in the DNA-ICLR genes may be more sensitive to treatment with platinum-based therapeutics, which can have implications in the clinical management of these patients.

Intronic Variants in the MSH2 (rs2303426 and rs10179950) and PMS2 (rs2286681 and rs62456178) Genes Are Not Associated with Colorectal Cancer in Mexican Patients

Background/Objectives: In the origin and development of colorectal cancer (CRC), a global public health problem, a dysfunction mismatch repair system appears to be a key factor. The objective was to determine the association of intronic variants in the MSH2 and PMS2 genes with CRC in Mexican patients. Methods: Blood samples of 143 CRC patients and 146 reference individuals were genotyped through TaqMan® Genotyping Assays. Genotypic and allelic frequencies were determined by direct counting. To compare genotypic and allelic distributions, the chi-square test was used. For the association analysis, the risks of alleles and genotypes were estimated by odds ratio with 95% confidence intervals. Haplogroups were inferred with a Bayesian algorithm. Linkage disequilibrium was measured using D’ and r2 with Arlequin v3.5.2. The in silico analysis was carried out using the SpliceAI, UCSC, JASPAR and TRRUST platforms. All statistical analyses were performed with SPSS v29.0.2.0. Results: In the CRC group, the mean age was 58.2 ± 14.7 years and 60.8% were men. No variant was associated with CRC or implicated in gene post-replicative processing. Linkage disequilibrium was observed for loci rs2303426 and rs10179950 in MSH2 and for loci rs2286681 and rs62456178 in PMS2. Conclusions: The genotypic and allelic frequencies of the four variants are reported for the first time in Mexican patients with CRC. No association was found between gene variants and risk for CRC but there was a strong linkage disequilibrium between the loci of both MSH2 and PMS2 genes. None of the variants showed a possible repercussion on splicing.

The decrease in Rad51 and DNA ligase IV nuclear protein expression in Msh2 knockdown HC11 cells induced the low CRISPR/Cas9-mediated knock-in efficiency at the β-casein gene locus.

Successful gene editing technology is crucial in molecular biology and related fields. An essential part of an efficient knock-in system is increasing homologous recombination (HR) efficiency in the double-strand break (DSB) repair pathways. Interestingly, HR is closely related to the DNA mismatch repair (MMR) pathway, whereby MMR-related gene Msh2 recognizes a mismatch of nucleotides in recombinant intermediates or gene conversion formed during HR. This study aimed to investigate how the knockdown of Msh2 affects HR-mediated knock-in efficiency at the mouse β-casein locus. Therefore, we investigated the effect of inhibiting Msh2 expression on the expression of the HR-related gene Rad51 and the key enzyme DNA ligase IV involved in non-homologous end joining (NHEJ). The knock-in vector targeting the mouse β-casein gene locus, programmed guide RNA, and Msh2 siRNA expression vector were co-transfected in HC11 cells, or only the Msh2 siRNA expression vector was transfected. Knock-in efficiency was confirmed by polymerase chain reaction (PCR). The mRNA and protein expression of Msh2, HR-related gene Rad51, and NHEJ-related gene DNA ligase IV were evaluated by quantitative reverse transcription PCR (RT-qPCR) and Western blot analysis. The knock-in vector efficiency at the mouse β-casein gene locus significantly decreased upon Msh2 knockdown in HC11 mouse mammary epithelial cells (HC11 cell). Additionally, the knockdown of the DNA MMR-related gene Msh2 protein significantly downregulated the nuclear protein expression of the HR-related Rad51 and NHEJ-related DNA ligase IV genes. The decreased Msh2 protein expression in the nucleus downregulated the Rad51 and ligase IV protein expressions. Consequently, reduced Rad51 expression results in decreased knock-in efficiency.

Association of glutaminase expression with immune-suppressive tumor microenvironment, clinicopathologic features, and clinical outcomes in endometrial cancer

ObjectiveIncreased glutamine metabolism by cancer cells via upregulation of the drug-targetable enzyme glutaminase may contribute to an immune-suppressive tumor microenvironment. Inhibiting glutamine metabolism can not only suppress tumor growth, but...

The guidelines for clinical practice for carriers of germline mutations in the Lynch syndrome predisposition genes MLH1, MSH2, MSH6, PMS2 and large deletions of EPCAM (4.2024).

The guidelines for clinical practice for carriers of pathogenic variants in clinically relevant genes predisposing to Lynch syndrome and colorectal cancer define the steps of primary and secondary prevention that should be provided to the individuals at high risk of developing hereditary cancer in the Czech Republic. The drafting of the guidelines was organized by the Oncogenetics Working Group of the Society for Medical Genetics and Genomics of J. E. Purkyně Czech Medical Society, in cooperation with representatives of oncology, oncogynecology, and gastroenterology. The guidelines are based on the current recommendations of the National Comprehensive Cancer Network (NCCN), European Society of Medical Oncology (ESMO) and take into account the capacity of the Czech healthcare system.

The molecular genetics of adrenal cushing.

Adrenal Cushing represents 20% of cases of endogenous hypercorticism. Unilateral cortisol-producing adenoma (CPA), a benign tumor, and adrenocortical carcinoma (ACC), a malignant tumor, are more frequent than bilateral adrenal nodular diseases (primary bilateral macronodular adrenal hyperplasia (PBMAH) and primary pigmented nodular adrenal disease (PPNAD)).In cortisol-producing adrenal tumors, the signaling pathways mainly altered are the protein kinase A and Wnt/β-catenin pathways. Studying components of these pathways and exploring syndromic and familial cases of these tumors has historically enabled identification of many of the predisposing genes. More recently, pangenomic sequencing revealed alterations in sporadic tumors.In ACC, mainly due to TP53 alterations causing Li-Fraumeni syndrome, germline predisposition is frequent in children, while it is rare in adults. Pathogenic variants in the DNA mismatch repair genes MLH1, MSH2, MSH6, and PMS2, which cause Lynch syndrome or alterations of IGF2 and CDKN1C (11p15 locus) in Beckwith-Wiedemann syndrome, can also cause ACC. Rarely, ACC is described in other hereditary tumor syndromes due to germline pathogenic variants in MEN1 or APC and, in very rare cases, NF1, SDH, PRKAR1A, or BRCA2. Concerning ACC somatic alterations, TP53 and genetic or epigenetic alterations at the 11p15 locus are also frequently described, as well as CTNNB1 and ZNRF3 pathogenic variants.CPAs mainly harbor somatic pathogenic variants in PRKACA and CTNNB1 and, less frequently, PRKAR1A, PRKACB, or GNAS1 pathogenic variants. Isolated PBMAH is due to ARMC5 inactivating pathogenic variants in 20 to 25% of cases and to KDM1A pathogenic variants in food-dependent Cushing. Syndromic PBMAH may be due to germline pathogenic variants in MEN1, APC, or FH, causing type 1 multiple endocrine neoplasia, familial adenomatous polyposis, or hereditary leiomyomatosis-kidney cancer syndrome, respectively. PRKAR1A germline pathogenic variants are the main alteration causing PPNAD (isolated or part of Carney complex).

Clinicopathological and molecular genetic insights into EBV-positive inflammatory follicular dendritic cell sarcoma

Epstein-Barr virus (EBV)-positive inflammatory follicular dendritic cell (FDC) sarcoma (EBV + IFDCS) is a rare entity, and its histopathological characteristics have not been fully described. This study aimed to investigate the clinical characteristics, pathological features, and molecular genetic profiles of EBV + IFDCS to improve our understanding of these lesions. A total of 12 EBV + IFDCS specimens were obtained from patients in our pathology diagnostic center. The clinical data, morphology, immunohistochemistry, in situ hybridization, and high-throughput DNA-targeted sequencing data were collected, and follow-up data were analyzed. These data were compared with those of 6 patients with traditional FDCS. The patients with EBV + IFDCS ranged from 21 to 84 years old, with a mean age of 52.3 years and a male-to-female ratio of 1:5. At the last follow-up, all patients were alive, with 2 experiencing recurrence and metastasis. In these cases, four were classified as the classical subtype, four as the angiomatoid/sclerosing subtype, and four as the lymphoma-like subtype, with two cases also exhibiting epithelioid granulomas. All patients exhibited heterogeneous expression of follicular dendritic cell markers (CD21, CD23, CD35, and CXCL13) alongside the fibroblast marker SMA, with significantly higher expressions of IgG4, EBER, and SMA in EBV + IFDCS patients compared to FDCS patients (P < 0.05). Conversely, SSTR2, EGFR, and STAT3 expression were significantly lower in the EBV + IFDCS group (P < 0.05). The average value of EBER was significantly higher in the classical subtype group (P = 0.022). Among the four cases of EBV + IFDCS analyzed for molecular genetic features, one patient exhibited germline mutations in the CDKN1C, PDGFRA, MSH2, FANCG, MLH1, ALK, and RUNX1 genes; three exhibited simultaneous SNP variations in the MTHFR gene; and two exhibited simultaneous SNP variations in the NQO1 gene. We conducted KEGG pathway analysis on the mutant genes, revealing significant enrichment in the cAMP signaling pathway, which plays a crucial role in tumor development. Survival analysis demonstrated that the median PFS rates were not reached (NR) for EBV + IFDCS patients, compared to 5 months (HR = 7.76) for FDCS patients. The 3-year PFS rates were 66.67% and 16.67%, respectively. Compared with the FDCS group, EBV + IFDCS patients had a significantly longer median PFS time (p < 0.05). In conclusion, EBV + IFDCS represents a group of tumors with unique clinical, morphological, immunological, prognostic, and molecular cytogenetic characteristics.

Temozolomide Therapy in Management of Refractory Pituitary Adenomas: A Case Series of 39 Patients

ObjectiveThe management of refractory pituitary adenomas (RPAs) presents significant challenges. This study aimed to evaluate the long-term treatment outcomes of patients with RPA managed with temozolomide (TMZ) and to identify potential biomarkers for predicting TMZ treatment response. MethodsThis retrospective case series included patients with RPA who underwent trans-sphenoidal surgery (TSS) or craniotomy at a comprehensive medical center in China between January 2014 and December 2021. Results39 patients with RPA (median age 42 years; 23 males [59%]) were treated with TMZ for a median of 9 cycles. The median follow-up was 34.4 months. Complete response (CR) was observed in 2 patients, partial response (PR) in 11 patients, stable disease (SD) in 9, progressive disease (PD) in 11, and death in 6 patients. O6-methylguanine DNA methyltransferase levels were significantly lower in patients with CR, PR, or SD compared to those with PD or mortality, with mean values of 24.2% and 58.1, respectively. MutS homologs 6 levels were significantly higher in patients with CR, PR, or SD compared to those with PD or mortality, with mean values of 64.2% and 36.9%, respectively. Patients who received concomitant TMZ and external beam radiotherapy showed a significant tumor size reduction of 178,837 mm3 (P < .001) compared to those treated with TMZ alone. ConclusionsTMZ demonstrates promising efficacy in eliciting tumor responses in patients with PRA. O6-methylguanine DNA methyltransferase and MutS homologs 6 have emerged as potential biomarkers for predicting treatment response. Furthermore, radiation with concurrent TMZ may significantly improve outcomes in patients with RPA.

Germline Variants Of The MMR/EPCAM Genes In Russian Patients With Lynch Syndrome

Objective — Lynch syndrome is the most common hereditary cancer syndrome caused by pathogenic variants in the MMR/EPCAM genes. Our goal was to study the germline variants of these genes in the largest sample of patients with Lynch syndrome in Russia. Methods — The study included data on pathogenic and likely pathogenic variants in the MMR/EPCAM genes collected from the local Registry of Hereditary Colorectal Cancer of Ryzhikh National Medical Research Centre for Coloproctology (RNMRCC). We analyzed all available data on 141 probands with Lynch syndrome: 78 men and 63 women aged 21 to 80 years treated at RNMRCC from 2012 through 2023. Results — The numbers of pathogenic and likely pathogenic variants detected in the key genes were as follows MLH1 (69 probands), MSH2 (57), MSH6 (10), EPCAM (3), PMS2 (1), and PMS1 (1). Of the 141 germline variants, 17 (12.1%) were detected for the first time: MLH1 (8 probands) MSH2 (8), and MSH6 (1). Thirteen (9.2%) of the detected variants were associated with large deletions/duplications. The most frequent pathogenic variants in the MLH1 gene were c.1852_1854del (9 probands), c.350C&gt;T (4), and c.1459C&gt;T (3). The most frequent pathogenic variants in the MSH2 gene were c.942+3A&gt;T (9 probands) and c.1288A&gt;T (3). Conclusion — Our results allowed establishing the frequency and spectrum of different types of germline variants in the MMR/EPCAM genes, which helped optimize the algorithm for selecting and diagnosing Russian patients with Lynch syndrome.

Fusobacterium Nucleatum Promotes Microsatellite Instability in Colorectal Carcinoma Through Up-regulation of miRNA-155-5p-Targeted Inhibition of MSH6 via the TLR4/NF-κB Signaling Pathway.

Fusobacterium nucleatum (Fn) is significantly associated with poor prognosis in colorectal carcinoma (CRC), however, mechanisms of Fn in DNA mismatch repair (MMR) and microsatellite instability (MSI) in CRC have not been fully elucidated. Clinical samples are collected to analyze the relationship between Fn abundance and microsatellite stability. Tumor cells are treated with Fn to detect the expression of proteins related to toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (Myd88), mutS homolog 6 (MSH6), and nuclear factor-κB (NF-κB) signaling pathways, respectively. Combined with the prediction results from TargetScan, the regulatory role of microRNA upstream of MSH6 is demonstrated. The effect of this regulatory axis on CRC development is demonstrated using a nude mouse tumor model. Compared with microsatellite stability (MSS)-type CRC patients, MSI-type showed higher Fn abundance. Fn treatment of CRC cells activated TLR4/Myd88/NF-κB signaling pathway, transcriptionally activating miRNA-155-5p expression, thereby negatively regulating MSH6. Fn treatment accelerated the malignant progression of CRC in mice, and this process is inhibited by miRNA-155-5p antagomir. Fn in CRC upregulated miRNA-155-5p by activating TLR4/NF-κB signaling to inhibit MSH6, and this regulatory pathway may affect MSS of cancer cells.

Association between microsatellite instability status, clinicopathological features and mitochondrial DNA amplification in patients with colorectal cancer.

The relationship between BRAF-V600E mutations, mitochondrial DNA amplification and microsatellite instability-high (MSI-H) in colorectal cancer (CRC) has yet to be fully elucidated. The aim of the present study was to assess the association between the MSI status and BRAF-V600E gene mutations/clinicopathological features/mitochondrial DNA amplification in CRC. A non-interventional study analysis was performed using the clinicopathological features of 455 patients with CRC. Immunohistochemistry was used to evaluate four mismatch repair proteins (MutS homolog 2, MutS homolog 6, MutL homolog 1 and postmeiotic segregation increased 2), Ki-67 index, and programmed cell death protein 1 (PD-1) and programmed cell death-ligand 1 (PD-L1) expression. Additionally, PCR coupled with capillary electrophoresis were used to ascertain the MSI status. Moreover, amplification refractory mutation system-PCR was used to detect BRAF-V600E gene mutation and fluorescence in situ hybridization analysis was used to assess mitochondrial DNA. A total of 455 patients were divided into the MSI high (MSI-H) group (n=52) and microsatellite stability (MSS) group (n=403) based on their MSI status. Compared with the results of immunohistochemistry of four mismatch repair proteins, the consistency rate between mismatch repair protein deficiency and MSI was 94.23%. There were significant differences in PD-L1, primary tumor site, clinical stage, degree of differentiation, tumor size, lymph node metastasis and the occurrence of multiple primary tumors between the MSI-H group and MSS group (P<0.05 or P<0.001). However, there were no significant differences for sex, age, PD-1, Ki-67 expression and BRAF-V600E. The 24-60-month survival rate of the patients in the MSI-H group was significantly higher than that of those in the MSS group (P<0.05). Furthermore, the number of mitochondrial DNA was significantly amplified in the MSI-H group. In conclusion, the present study demonstrated that the combined detection of PD-L1 and MSI in patients with CRC can provide more accurate and effective guidance for personalized treatment.

Association Between the Protein Expressions of MutS Homologs and Villin and the Clinicopathological Characteristics in 310 Colon Cancer Patients

To examine the relationship between the expressions of mismatch repair proteins, MutS homolog 2 (MSH2) and MutS homolog 6 (MSH6), and villin and the pathological features in patients with colon cancer. A total of 310 cases of colon cancer patients who were treated at our hospital between January 2017 and September 2021 were selected. The diagnosis of colon cancer of all patients was verified by pathological evaluation. Immunohistochemistry was used to determine the protein expressions of MSH2, MSH6, and villin. The correlation between the expressions of MSH2, MSH6, and villin and the clinicopathological parameters in patients with colon cancer was analyzed accordingly. Multivariate logistic regression was used to analyze the correlation between the expressions of MSH2, MSH6, and villin and the clinicopathological parameters of colon cancer. Kaplan-Meier survival curve was used to compare the 2-year survival rates of colon cancer patients with different expression levels of the proteins. Among the 310 patients with colon cancer, the negative expression rates of MSH2, MSH6, and villin proteins in cancer tissues were 8.71% (27/310), 9.35% (29/310), and 46.13% (143/310), respectively. The negative expression rates of the three proteins in tissues adjacent to cancer were 3.23% (10/310), 4.19% (13/310), and 9.68% (30/310), respectively. The negative expression rates of the three proteins in cancer tissues were all higher than those in adjacent tissues (P<0.05). Regression analysis showed that the expression of MSH2 and MSH6 in cancer tissues was correlated with the age, the location of tumor lesions, tumor differentiation degree, and lymph node metastasis in colon cancer patients (P<0.05). The expression of villin in the cancer tissue is correlated with the depth of tumor infiltration, lymph node metastasis, distant metastasis, and clinical staging status in colon cancer patients (P<0.05). The 2-year survival rates of patients with negative expressions of MSH2 and MSH6 were 51.85% and 44.83%, respectively, which were lower than those of patients with positive expression of MSH2 and MSH6 (79.51% and 80.43%, P<0.05). Thirteen patients (4.1%) had negative expression of MSH2, MSH6, and villin (referred to as "triple negative expressions") in the cancer tissues, and their 2-year survival rate was 30.77%, which was lower than that of colon cancer patients who did not meet the criteria for triple negative expressions (79.12% [235/297], P<0.05). The expressions of MSH2, MSH6, and villin are closely correlated with the pathological features of colon cancer patients. Evaluating the expression of the three proteins may assist in the clinical diagnosis, treatment, and prognosis evaluation of colon cancer.

Investigation of the Relationship Between DNA Mismatch Repair Genes and Microsatellite Instability in Solid Tumors

Aim: In this study, we aimed to detect the MSI status and somatic mutations in MMR genes (MSH2, MSH6, MLH1, PMS2) of a total of 55 solid tumors diagnosed with colorectal, endometrium and ovarian cancer by NGS method and to reveal the relationship between them. Material and Method: DNA isolation was performed by taking 10-micron sections from paraffin-embedded tissue samples of 55 patients diagnosed with kolorektal, endometrium ve ovarian solid tümörlerinin and Kapa NGS DNA extraction kit was used for sequence analysis. The purity and concentration of the DNA obtained was measured by Qubit fluoremeter, and NadPrep DNA Universal Library Preparation Kit was used for high quality library preparation. Bioinformatics analyses were performed on the Genomize Seq platform. The MSI value was analysed by Roche Navify Mutation Caller software and percentage MSI values were determined using the MSIsensor2 pipeline for secondary analysis of NGS. Results: All ovarian tumors were in the MSI-Stable category. The average MSI value was 2.01. One sample had an MSI of zero. In addition, no mutations in the MSH2 and MLH1 genes were detected in any of the ovarian tumors. 3 of 4 endometrial tumors were in the MSI-Stable category, and 1 tumor was in the MSI-low (MSI value: 13.2) category. No variants were detected in the MSH2 and PMS2 genes in endometrial tumors. 2 of the 41 colorectal tumors (Case4, Case16) were in the MSI-High category. No variants were detected in the MMR genes in 19 tumors. Conclusion: Although frame-shift and stop-gain mutations were detected in 23 tumors that would cause protein deficiency in MMR genes, MSI-H was not detected, as expected, except for two colorectal tumors. Therefore, the results of our study emphasise the need to define new predictive biomarkers clinically within the framework of algorithms to predict response to immunotherapy and determine prognosis.

Circ_0025373 inhibits carbon black nanoparticles-induced malignant transformation of human bronchial epithelial cells by affecting DNA damage through binding to MSH2

Carbon black nanoparticles (CBNPs) have been demonstrated to induce DNA damage in epithelial cells. However, the potential of the damage to initiate carcinogenesis and the underlying mechanism remain poorly understood. Therefore, we constructed an in vitro model of malignant transformation of human bronchial epithelial cells (16HBE-T) by treating 40 μg/mL CBNPs for 120 passages. We observed tumor-like transformation and sustained DNA damage. Using transcriptome sequencing and RIP-seq, we identified the overexpression of the critical DNA mismatch repair genes MutS homolog 2 (MSH2) and its related circular RNA, circ_0025373, in the 16HBE-T cells. Mechanistically, circ_0025373 was found to inhibit DNA damage by binding to MSH2, thereby modifying its expression and influencing its nuclear and cytoplasmic distribution, which lead to inhibition of CBNP-induced malignant transformation of human bronchial epithelial cells. Our findings provide novel evidence on the carcinogenicity of CBNPs, and offer biological insights into the potential epigenetic regulation and potential therapeutic targets for lung carcinogenesis.

DNA demethylation is involved in nitric oxide-induced flowering in tomato

Flowering is one of the most important phenological periods, as it determines the timing of fruit maturation and seed dispersal. To date, both nitric oxide (NO) and DNA demethylation have been reported to regulate flowering in plants. However, there is no compelling experimental evidence of the relationship between NO and DNA demethylation during plant flowering. In this study, an NO donor and a DNA methylation inhibitor were used to investigate the involvement of DNA demethylation in NO-mediated tomato (Solanum lycopersicum cv. Micro-Tom) flowering. The results showed that the promoting effect of NO on tomato flowering was dose-dependent, with the most positive role observed at 10 μmol L-1 of the NO donor S-nitrosoglutathione (GSNO). Treatment with 50 μmol L-1 of the DNA methylation inhibitor 5-azacitidine (5-AzaC) also significantly promoted tomato flowering. Moreover, GSNO and 5-AzaC increased the peroxidase (POD) and catalase (CAT) activity and cytokinin (CTK) and proline contents, while they decreased the gibberellic acid (GA3) and indole-3-acetic acid (IAA) contents. Co-treatment with GSNO and 5-AzaC accelerated the positive effects of GSNO and 5-AzaC in promoting tomato flowering. Meanwhile, compared with GSNO or 5-AzaC treatment alone, co-treatment with GSNO+5-AzaC significantly increased the global DNA demethylation levels in different tissues in tomato. The results also indicate that DNA demethylation may be involved in NO-induced flowering. The expression of flowering genes was significantly altered by the GSNO+5-AzaC treatment. Among these genes, five flowering induction genes-ARGONAUTE 4 (AGO4A), SlSP3D/SINGLE FLOWER TRUSS (SFT), MutS HOMOLOG 1 (MSH1), ZINC FINGER PROTEIN 2 (ZFP2), and FLOWERING LOCUS D (FLD) were selected as candidate genes for further study. Then, McrBC-PCR analysis showed that the DNA demethylation of the SFT gene in the apex and the FLD gene in the stem might be involved in NO-induced flowering. Therefore, our study shows that NO might promote tomato flowering by mediating the DNA demethylation of flowering induction genes. This study provides direct evidence of a synergistic effect of NO and DNA demethylation in promoting tomato flowering.

Association of Functional Polymorphisms in MSH3 and IL-6 Pathway Genes with Different Types of Microsatellite Instability in Sporadic Colorectal Cancer.

Microsatellite instability (MSI) has been recognized as an important factor in colorectal cancer (CRC). It arises due to deficient mismatch repair (MMR), mostly attributed to MLH1 and MSH2 loss of function leading to a global MMR defect affecting mononucleotide and longer microsatellite loci. Recently, microsatellite instability at tetranucleotide loci, independent of the global MMR defect context, has been suggested to represent a distinct entity with possibly different consequences for tumorigenesis. It arises as a result of an isolated MSH3 loss of function due to its translocation from the nucleus to the cytoplasm under the influence of interleukin-6 (IL-6). In this study the influence of MSH3 and IL-6 signaling pathway polymorphisms (MSH3 exon 1, MSH3+3133A/G, IL-6-174G/C, IL-6R+48892A/C, and gp130+148G/C) on the occurrence of different types of microsatellite instability in sporadic CRC was examined by PCR-RFLP and real-time PCR SNP analyses. A significant difference in distribution of gp130+148G/C genotypes (p = 0.037) and alleles (p = 0.031) was observed in CRC patients with the C allele being less common in tumors with di- and tetranucleotide instability (isolated MSH3 loss of function) compared to tumors without microsatellite instability. A functional polymorphism in gp130 might modulate the IL-6 signaling pathway, directing it toward the occurrence of microsatellite instability corresponding to the IL-6-mediated MSH3 loss of function.

Clinical Updates and Surveillance Recommendations for DNA Replication Repair Deficiency Syndromes in Children and Young Adults.

Replication repair deficiency (RRD) is a pan-cancer mechanism characterized by abnormalities in the DNA mismatch repair (MMR) system due to pathogenic variants in the PMS2, MSH6, MSH2, or MLH1 genes, and/or in the polymerase-proofreading genes POLE and POLD1. RRD predisposition syndromes (constitutional MMR deficiency, Lynch, and polymerase proofreading-associated polyposis) share overlapping phenotypic and biological characteristics. Moreover, cancers stemming from germline defects of one mechanism can acquire somatic defects in another, leading to complete RRD. Here we describe the recent advances in the diagnostics, surveillance, and clinical management for children with RRD syndromes. For patients with constitutional MMR deficiency, new data combining clinical insights and cancer genomics have revealed genotype-phenotype associations and helped in the development of novel functional assays, diagnostic guidelines, and surveillance recommendations. Recognition of non-gastrointestinal/genitourinary malignancies, particularly aggressive brain tumors, in select children with Lynch and polymerase proofreading-associated polyposis syndromes harboring an RRD biology have led to new management considerations. Additionally, universal hypermutation and microsatellite instability have allowed immunotherapy to be a paradigm shift in the treatment of RRD cancers independent of their germline etiology. These advances have also stimulated a need for expert recommendations about genetic counseling for these patients and their families. Future collaborative work will focus on newer technologies such as quantitative measurement of circulating tumor DNA and functional genomics to tailor surveillance and clinical care, improving immune surveillance; develop prevention strategies; and deliver these novel discoveries to resource-limited settings to maximize benefits for patients globally.

Prognostic implications of immunohistochemistry in patients with endometrial cancer.

Various histological cell types, high histological grade, extensive myometrial invasion, and the presence of lymphovascular involvement are recognized as risk factors for disease development. Individuals carrying mutations in MutL homolog 1 (MLH1), MutS homolog 2 (MSH2), MutS homolog 6 (MSH6), or postmeiotic segregation increased 2 (PMS2) genes face an increased susceptibility to both endometrial and colorectal malignancies, with a lifetime risk ranging from 40% to 60%. This research aimed to investigate the prevalence of specific immunohistochemical (IHC) markers and microsatellite instability in endometrial carcinomas and explore potential associations with patient characteristics and clinical outcomes. Out of 58 patients with comprehensive follow-up data, a subgroup of 21 cases underwent rigorous IHC evaluation, involving estrogen receptor (ER), progesterone receptor (PR), Ki67, MLH1, MSH2, MSH6, PMS2, and p53 markers. Statistical analysis, employing the χ² (chi-squared) test, was conducted to assess the connection between individual IHC markers and clinical outcomes, with particular emphasis on the influence of radiation, chemotherapy, or brachytherapy treatment, as well as the occurrence of recurrence or mortality. Notably, significant correlations were observed in cases where MSH2 and MSH6 exhibited positive results, indicating their association with the use of chemotherapy and brachytherapy. However, the analysis pertaining to International Federation of Gynecology and Obstetrics (FIGO) stage or tumor grade did not reveal any statistically significant relationships with these parameters.