Systemic circulating microRNA landscape in Lynch syndrome.

Circulating microRNAs (c-miRs) are small noncoding RNA molecules that migrate throughout the body and regulate gene expression. Global c-miR expression patterns (c-miRnomes) change with sporadic carcinogenesis and have predictive potential in early detection of cancers. However, there are no studies that have assessed whether c-miRnomes display similar potential in carriers of inherited pathogenic mismatch-repair gene variants (path_MMR), known as Lynch syndrome (LS), who are predisposed to highly increased cancer risk. Using high-throughput sequencing and bioinformatic approaches, we conducted an exploratory analysis to characterize systemic c-miRnomes of path_MMR carriers, sporadic rectal cancer patients and non-LS controls. We showed for the first time that cancer-free path_MMR carriers have a systemic c-miRnome of 40 differentially expressed c-miRs that can distinguish them from non-LS controls. The systemic c-miRnome of cancer-free path_MMR carriers also resembles the systemic c-miRnomes of cancer patients with or without path_MMR. Our pathway analysis linked the found differentially expressed c-miRs to carcinogenesis. A total of 508 putative target genes were identified for 32 out of 40 differentially expressed c-miRs, and 238 of them were enriched in cancer-related pathways. The most enriched c-miR-target genes include well-known oncogenes and tumor suppressor genes such as BCL2, AKT3, PIK3CA, KRAS, NRAS, CDKN1A and PIK3R1. Taken together, our findings suggest that LS and sporadic carcinogenesis share common biological pathways and alterations in these pathways can produce a c-miR signature which can track potential oncogenic stress in cancer-free path_MMR carriers. Therefore, c-miRs hold potential in monitoring the LS risk stratification patterns during clinical surveillance or cancer management.

Epidemiological, clinical and molecular characterization of Lynch-like syndrome: A population-based study.

Colorectal carcinomas that are mismatch repair (MMR)-deficient in the absence of MLH1 promoter methylation or germline mutations represent Lynch-like syndrome (LLS). Double somatic events inactivating MMR genes are involved in the etiology of LLS tumors. Our purpose was to define the clinical and broader molecular hallmarks of LLS tumors and the population incidence of LLS, which remain poorly characterized. We investigated 762 consecutive colorectal carcinomas operated in Central Finland in 2000-2010. LLS cases were identified by a stepwise protocol based on MMR protein expression, MLH1 methylation and MMR gene mutation status. LLS tumors were profiled for CpG Island Methylator Phenotype (CIMP) and somatic mutations in 578 cancer-relevant genes. Among 107 MMR-deficient tumors, 81 (76%) were attributable to MLH1 promoter methylation and 9 (8%) to germline mutations (Lynch syndrome, LS), leaving 14 LLS cases (13%) (3 remained unclassified). LLS carcinomas were diagnosed at a mean age of 65 years (vs. 44 years in LS, p < 0.001), had a proximal to distal ratio of 1:1, and all were BRAF V600E-negative. Two somatic events in MMR genes were identifiable in 11 tumors (79%). As novel findings, the tumors contained an average of 31 nonsynonymous somatic mutations/Mb and 13/14 were CIMP-positive. In conclusion, we establish the epidemiological, clinical and molecular characteristics of LLS in a population-based study design. Significantly more frequent CIMP-positivity and lower rates of somatic mutations make a distinction to LS. The absence of BRAF V600E mutation separates LLS colorectal carcinomas from MLH1-methylated colorectal carcinomas with CIMP-positive phenotype.

Detection of a major Lynch Syndrome-causing MLH1 founder variant in a large-scale genotyped cohort.

Some 50% of Finnish Lynch Syndrome (LS) cases are caused by a founder variant in MLH1, in which the entire exon 16 has been lost due to an Alu-mediated recombination event. We piloted detecting the variant in FinnGen, a large genotyped cohort comprising approximately 10% of the current Finnish population, and validated the MLH1 founder variant status of identified individuals residing in the Central Finland Biobank catchment area. A consensus sequence flanking the deletion was identified in whole genome sequences of six LS individuals with the founder variant. Genotype data of 212,196 individuals was queried for regional matches to the consensus sequence. Enrichment of cancer and age at cancer onset was compared between matching and non-matching individuals. Variant status was validated for a subset of the identified individuals using a polymerase chain reaction assay. Allelic matches in a chosen target region was detected in 348 individuals, with 89 having a cancer diagnosis (Bonferroni-adjusted p-value = 1), 20 a familial cancer history (p-adj. < .001), with mean age of onset of cancer being 53.6 years (p-adj. = .002). Eighteen of potential variant carriers had been sampled by the Central Finland Biobank, of which four (22%) were validated as true variant carriers. The workflow we have employed identifies MLH1 exon 16 deletion variant carriers from population-wide SNP genotyping data. An alternative design will be sought to limit false positive findings. Large genotyped cohorts provide a potential resource for identification and prevention of hereditary cancer.

NGS of brush cytology samples improves the detection of high-grade dysplasia and cholangiocarcinoma in patients with primary sclerosing cholangitis: A retrospective and prospective study.

BACKGROUND: Biliary dysplasia, a precursor of cholangiocarcinoma (CCA), is a common complication of primary sclerosing cholangitis. Patients with high-grade dysplasia (HGD) or early CCA who have received oncological treatment are candidates for liver transplantation. The preoperative diagnosis of CCA or HGD is challenging, and the sensitivity of biliary brush cytology (BC) is limited. METHODS: By using next-generation sequencing (NGS), we retrospectively analyzed archived tissue samples (n=62) obtained from explanted liver tissue and CCA samples to identify oncogenic mutations that occur during primary sclerosing cholangitis carcinogenesis. BC samples were prospectively collected from patients with primary sclerosing cholangitis (n=97) referred for endoscopic retrograde cholangiography to measure the diagnostic utility of NGS combined with BC compared with traditional cytology alone. RESULTS: Mutations in KRAS, GNAS, FLT3, RNF43, TP53, ATRX, and SMAD4 were detected in archived CCA or HGD samples. KRAS, GNAS, TP53, CDKN2A, FBXW7, BRAF, and ATM mutations were detected in prospectively collected brush samples from patients with histologically verified CCA or HGD. One patient with low-grade dysplasia in the explanted liver had KRAS and GNAS mutations in brush sample. No mutations were observed in brush samples or archived tissues in liver transplantation cases without biliary neoplasia. While KRAS mutations are common in biliary neoplasms, they were also observed in patients without biliary neoplasia during surveillance. CONCLUSIONS: In summary, NGS of BC samples increased the sensitivity of detecting biliary neoplasia compared with traditional cytology. Performing NGS on BC samples may help diagnose HGD or early CCA, benefiting the timing of liver transplantation.

Urokinase-type plasminogen activator regulates neurodegeneration and neurogenesis but not vascular changes in the mouse hippocampus after status epilepticus.

Expression of urokinase-type plasminogen activator (uPA) is increased after brain injury, suggesting that, like in cancer tissue, uPA plays roles in brain remodeling. Here we injured brain with intrahippocampal kainic acid (KA) injection in adult Wt and uPA-/- mice. At 20 days post-injury, uPA-/- mice had more severe loss of contralateral pyramidal (p<0.05) and hilar neurons (p<0.05) than Wt mice. The number of doublecortin (DCX)-positive newly born neurons was also reduced in uPA-/- mice as compared to Wt (p<0.01). No difference was observed in granule cell dispersion or distribution of DCX-positive neurons in the dentate gyrus. uPA deficiency did not affect the total length of hippocampal blood vessels or vessel density. No differences were observed in the severity of status epilepticus or consequent epilepsy between the genotypes. These data indicate that uPA deficiency can unfavorably modulate both delayed neurodegeneration and neurogenesis but has little effect on post-injury neuronal migration and vascular density. Our results favor the idea that elevated uPA during the post-injury phase is neuroprotective.

Clonal Evolution of MEK/MAPK Pathway Activating Mutations in a Metastatic Colorectal Cancer Case.

BACKGROUND/AIM: The aim of this study was to examine clonal heterogeneity, to test the utility of liquid biopsy in monitoring disease progression and to evaluate the usefulness of ex vivo drug screening in a BRAF L597Q-mutated colorectal cancer (CRC) patient developing metastases during adjuvant therapy. MATERIALS AND METHODS: Next generation sequencing (NGS) and droplet digital PCR (ddPCR) were performed in samples from tumor tissues and liquid biopsies. Live cancer cells from a metastatic lesion were used in ex vivo drug sensitivity assays. RESULTS: We found evidence of continued dependence of MEK/MAPK pathway activation, but different activating mutations in primary tumor and metastases. Liquid biopsy based BRAF L597Q ddPCR testing was a sensitive personalized biomarker predicting the rise of clinically aggressive metastatic disease. Ex vivo drug sensitivity assays with BRAF L597Q mutated cells showed response to MEK/MAPK targeted therapies. CONCLUSION: The rare BRAF L597Q mutation may be associated with aggressive tumor behavior in CRC. Liquid biopsy can be used to capture clinically relevant tumor features.

EGFR gene copy number decreases during anti-EGFR antibody therapy in colorectal cancer.

Epidermal growth factor receptor (EGFR) gene copy number (GCN) increase is associated with a favorable anti-EGFR antibody treatment response in RAS wild-type metastatic colorectal cancer. However, there are limited and comparative data regarding the EGFR GCN in primary colorectal cancer tumors and corresponding metastases or the effect of anti-EGFR antibody treatment on EGFR GCN in recurrent disease. In addition, little is known about the potential EGFR GCN changes during anti-EGFR therapy in comparison with other treatment regimens. EGFR GCN was analyzed by EGFR immunohistochemistry-guided silver in situ hybridization in primary and corresponding recurrent local or metastatic tumors from 80 colorectal cancer patients. GCN levels were compared between KRAS wild-type patients having received anti-EGFR therapy and patients having received other forms of treatment after primary surgery. The EGFR GCN decrease between primary and recurrent tumors was more pronounced among the anti-EGFR-treated patients than among patients not treated with anti-EGFR therapy (P = .047). None of the patients experiencing an EGFR GCN increase of at least 1.0 between the primary and recurrent tumors were treated with anti-EGFR antibodies. When including only patients with distant metastases, an EGFR GCN decrease of at least 1.0 was more common among the anti-EGFR-treated patients than among patients not treated with anti-EGFR therapy (P = .028). Our results suggest that anti-EGFR antibody treatment is associated with EGFR GCN decrease between the primary and recurrent colorectal adenocarcinomas, whereas no GCN change is observed among patients receiving other forms of treatment after primary surgery.

BRAF mutation in sporadic colorectal cancer and Lynch syndrome.

The aim of the study was to detect mutations of BRAF oncogene in colorectal cancer and to use this information to identify Lynch syndrome patients. Consecutive cases of primary colorectal cancer (n = 137) were analyzed for MLH1 protein expression using immunohistochemistry (IHC). BRAF V600E mutation was detected by IHC using a specific monoclonal antibody (VE1) and by qPCR. All MLH1 protein-negative cases were subjected to microsatellite instability analysis and MLH1 promoter methylation assay. MLH1 protein expression deficiency and high microsatellite instability (MSI-H) were detected in 18 of the 137 (13.1%) consecutive colorectal cancer specimens. Detection of the BRAF V600E mutation by IHC was 100% sensitive and specific as compared to qPCR, and this mutation was frequently present in the MSI-H group (77.8%; 14/18) and less frequently in the microsatellite-stable group (7.6%; 9/118). All BRAF V600E mutated cases of the MSI-H group presented with a MLH1 promoter methylation (14/14) as detected by methylation-specific multiplex ligation-dependent probe amplification. When BRAF was wild type in the MSI-H group, only one MLH1 promoter methylation was detected (1/4), and of the remaining three cases without MLH1 methylation, two were identified to harbor an MLH1 mutation consistent with Lynch syndrome. Finally, 11 previously confirmed Lynch syndrome cases were analyzed for BRAF V600E mutation, and all of them were wild type. In conclusion, detection of BRAF V600E in colorectal cancer specimens by IHC is sensitive and specific and may help to identify Lynch syndrome patients.

Increased expression and activity of urokinase-type plasminogen activator during epileptogenesis.

Our recent large-scale molecular profiling study revealed a sevenfold upregulation in the expression of urokinase-type plasminogen activator (uPA) during epileptogenesis. uPA is a member of the plasminogen activation system, which is a major contributor to the reorganization of neuronal circuits after trauma. Here, we investigated the expression and activity of uPA in normal and epileptogenic rat hippocampus to test a hypothesis that the expression of uPA is altered in brain areas that undergo epilepsy-related circuitry reorganization. Epileptogenesis was triggered by inducing status epilepticus (SE) with electrical stimulation of the amygdala in rats. Continuous video-electroencephalogram recordings were used to monitor the development of SE and the occurrence of spontaneous seizures. Animals were killed at 1, 4 or 14 days after SE, and brains were processed for immunohistochemistry or protein extraction. Confocal microscopy analysis of double-immunolabelled preparations indicated that SE triggered an increased expression of uPA in hippocampal astrocytes, neurons, white matter and blood vessels. Zymography revealed that the expression of uPA protein is associated with increased levels of enzymatically active uPA during epileptogenesis. uPA expression and enzymatic activity peaked within 1-4 days after SE, that is, before the occurrence of spontaneous seizures, and remained elevated for at least 2 weeks. These data suggest that uPA is involved in the reorganization of neuronal tissue during the epileptogenic process.