Confirmation of damaging effect of MSH2 c.2634+1G>C mutation on splicing, its classification and implications for counseling

Alternative splicing of mRNA in colorectal cancer: new strategies for tumor diagnosis and treatment

Alternative splicing (AS) is an important event that contributes to posttranscriptional gene regulation. This process leads to several mature transcript variants with diverse physiological functions. Indeed, disruption of various aspects of this multistep process, such as cis- or trans- factor alteration, promotes the progression of colorectal cancer. Therefore, targeting some specific processes of AS may be an effective therapeutic strategy for treating cancer. Here, we provide an overview of the AS events related to colorectal cancer based on research done in the past 5 years. We focus on the mechanisms and functions of variant products of AS that are relevant to malignant hallmarks, with an emphasis on variants with clinical significance. In addition, novel strategies for exploiting the therapeutic value of AS events are discussed.

Exploring the real-world effect of the SARS-CoV-2 pandemic on the molecular diagnostics for cancer patients and high-risk individuals

Background: The SARS-CoV-2 pandemic introduced a global distraction effect in cancer patients' care. The aim of this study was to explore the effect of the pandemic on the largest molecular diagnostics center for cancer patients and high-risk individuals in Serbia.Research design and methods: EGFR, KRAS/NRAS, BRAF, and BRCA1/2 mutation testing were performed by qPCR and NGS. NGS was used for panel testing of hereditary breast/ovarian cancer and cancers associated with Lynch syndrome. The analytical output during the state of emergency (SoE) was compared to the period before and after the outbreak using one-way ANOVA. Statistical significance was set at p < 0.05.Results: A 38% reduction in the number of analysis was detected during the SoE. After the SoE, a 19% reduction was noted compared to SoE and 50% compared to the period before the SoE (p = 0.038). Three of the 48 scheduled appointments for pretest genetic counseling were carried out during the SoE, but the number of NGS tests increased by 50%.Conclusions: The SARS-CoV-2 pandemic had a profound negative effect on the diagnostic output of our centralized molecular diagnostics center. The only positive effect was shortening of waiting lists for hereditary cancer patients and high-risk individuals.

A Novel Splice-Site Mutation in MSH2 Is Associated With the Development of Lynch Syndrome

Lynch syndrome (LS) is an inherited autosomal dominant disorder caused by germline mutations of mismatch repair (MMR) genes, including MSH2, MSH6, PMS2, and MLH1. This study aimed to analyze the molecular defects and clinical manifestations of an affected family and propose appropriate individual prevention strategies for all mutation carriers. A novel splicing mutation (c.1661+2 T>G) was identified in the MSH2 gene, which was found to co-segregate among affected family members by Whole exome sequencing (WES). RT-PCR analysis confirmed that c.1661+2 T>G could produce 3 transcripts, including 1 normal transcript and 2 aberrant transcripts. The 2 aberrant transcripts resulted in premature termination at the 6th nucleotide codon of MSH2 exon 11, so that the predicted products of the mutant MSH2 mRNAs were truncated proteins of 505 amino acids (with all of exon 10 deleted) and 528 amino acids (with a deletion of 82-nucleotides in exon 10), resulting in the loss of the interaction domain, the ATP domain and post-translationally modified residues. Quantitative RT-PCR (qRT-PCR) analysis showed that MSH2 mRNA levels in all patients were reduced to only 1/4 of the control levels. Our study reveals that a novel splicing mutation (c.1661+2 T>G) in the MSH2 gene causes LS and reaffirms the importance of genetic testing for LS.

Different responses to anti-programmed cell death protein 1 (PD-1) immunotherapy in a patient with Lynch syndrome and metachronous urothelial and colon cancer: A case report

Lynch syndrome (LS), as a result of the germline mutations in DNA mismatch repair genes, is characterized by the increased risk of endometrium, colon, and urinary tract cancer. Individuals with this disorder may occasionally have multiple primary carcinomas. Regardless of tumor type, pembrolizumab was approved for the treatment of patients with unresectable or metastatic mismatch repair deficient tumors, which may be an optional therapeutic method for patients with LS with multiple primary carcinomas. This case study is of a MSH2-deficient patient with LS with metachronous urothelial and colon cancer, who received pembrolizumab treatment for 8 months. The responses of the two primary sites to immunotherapy differed. Based on the changes of tumor markers and tumor size illustrated by imageological examinations, no response was observed in the sigmoid colon lesion, whereas an immune-associated phenomenon known as pseudoprogression was detected in the ureteral lesion. Immunotherapy was innovatively applied to the patient with multiple primary carcinomas. This case proposes a novel concept in which immunotherapy may potentially control the cancer growth in patients with LS and multiple primary carcinomas. However, further large-scale investigations are required. Furthermore, it raises a challenge to monitor the effectiveness of immunotherapy.