MicroRNAs modulate immunological and inflammatory responses in Holstein cattle naturally infected with Mycobacterium avium subsp. paratuberculosis.

MicroRNAs (miRNAs) regulate the post-transcriptional expression of genes by binding to their target mRNAs. In this study, whole miRNA sequencing was used to compare the expression of miRNAs in ileocecal valve (ICV) and peripheral blood (PB) samples of cows with focal or diffuse paratuberculosis (PTB)-associated lesions in gut tissues versus (vs) control cows without lesions. Among the eight miRNAs differentially expressed in the PB samples from cows with diffuse lesions vs controls, three (miR-19a, miR-144, miR32) were also down-regulated in cows with diffuse vs focal lesions. In the ICV samples, we identified a total of 4, 5, and 18 miRNAs differentially expressed in cows with focal lesions vs controls, diffuse lesions vs controls, and diffuse vs focal lesions, respectively. The differential expression of five microRNAs (miR-19a, miR-144, miR-2425-3p, miR-139, miR-101) was confirmed by RT-qPCR. Next, mRNA target prediction was performed for each differentially expressed miRNA. A functional analysis using the predicted gene targets revealed a significant enrichment of the RNA polymerase and MAPK signaling pathways in the comparison of cows with focal vs no lesions and with diffuse vs focal lesions, respectively. The identified miRNAs could be used for the development of novel diagnostic and therapeutical tools for PTB control.

Circulating tumor DNA tracking in patients with pancreatic cancer using next-generation sequencing / Evaluación de DNA circulante tumoral en paciente con Cáncer de páncreas empleando secuenciación de nueva generación

Background: Pancreatic cancer remains one of the most devastating malignancies due to the absence of techniques for early diagnosis and the lack of target therapeutic options for advanced disease. Next Generation Sequencing (NGS) generates high throughput and valuable genetic information when evaluating circulating tumor DNA (ctDNA); however clinical utility of liquid biopsy in pancreatic cancer has not been demonstrated yet. The aim of this study was to evaluate whether results from a Next Generation Sequencing panel on plasma samples from pancreatic cancer patients could have a clinical significance. Methods: From December 2016 to January 2020, plasma samples from 27 patients with pancreatic ductal adenocarcinoma at two different tertiary Spanish Hospitals underwent ctDNA testing using a commercial NGS panel of 65 genes. Clinical data were available for these patients. VarsSome Clinical software was used to analyse NGS data and establish pathogenicity. Results: Evaluable NGS results were obtained in 18 out of the 27 plasma samples. Somatic pathogenic mutations were found mainly in KRAS, BRCA2, FLT3 and HNF1A, genes. Pathogenic mutations were detected in 50% of plasma samples from patient diagnosed at stages III-IV samples. FLT3 mutations were observed in 22.22% of samples which constitute a novel result in the field. Conclusions: Liquid biopsy using NGS is a valuable tool but still not sensitive or specific enough to provide clinical utility in pancreatic cancer patients.(AU)

Introducción: El cáncer de páncreas es uno de los cánceres más devastadores debido a la falta de métodos que permitan un diagnóstico temprano y la ausencia de opciones terapéuticas en enfermedad avanzada. La técnica de secuenciación de nueva generación o Next Generation Sequencing (NGS) proporciona importantes resultados de alto rendimiento de información genética en muestras de DNA circulante tumoral (ctDNA); sin embargo, la utilidad clínica de la biopsia líquida en cáncer de páncreas no ha sido demostrado todavía. El objetivo de este estudio fue evaluar si los resultados de un panel de secuenciación de nueva generación en muestras de plasma de pacientes con cáncer de páncreas podría tener un significado clínico. Métodos: Empleando un panel comercial de NGS con 65 genes se evaluaron 27 muestras de plasma de pacientes con cáncer de páncreas recogidas entre diciembre del 2016 y enero del 2020 en 2 hospitales españoles. En el estudio se disponía de datos clínicos correspondientes a los pacientes. Se empleó el software VarSome Clinical para analizar resultados y establecer patogenicidad de las variantes. Resultados: Se obtuvieron resultados evaluables en 18 de las 27 muestras de plasma. Se encontraron mutaciones patogénicas en los genes KRAS, BRCA2, FLT3 y HNF1A. El 50% de los pacientes diagnosticados en estadios ii-iv presentaron alteraciones patogénicas en plasma. Se observaron mutaciones en FLT3 en el 22,22% de las muestras, lo cual es un resultado novedoso. Conclusiones: La NGS en biopsia líquida es una herramienta valiosa pero todavía no sensible ni específica para proporcionar utilidad clínica en pacientes con cáncer de páncreas.(AU)

Circulating tumor DNA tracking in patients with pancreatic cancer using next-generation sequencing.

BACKGROUND: Pancreatic cancer remains one of the most devastating malignancies due to the absence of techniques for early diagnosis and the lack of target therapeutic options for advanced disease. Next Generation Sequencing (NGS) generates high throughput and valuable genetic information when evaluating circulating tumor DNA (ctDNA); however clinical utility of liquid biopsy in pancreatic cancer has not been demonstrated yet. The aim of this study was to evaluate whether results from a Next Generation Sequencing panel on plasma samples from pancreatic cancer patients could have a clinical significance. METHODS: From December 2016 to January 2020, plasma samples from 27 patients with pancreatic ductal adenocarcinoma at two different tertiary Spanish Hospitals underwent ctDNA testing using a commercial NGS panel of 65 genes. Clinical data were available for these patients. VarsSome Clinical software was used to analyse NGS data and establish pathogenicity. RESULTS: Evaluable NGS results were obtained in 18 out of the 27 plasma samples. Somatic pathogenic mutations were found mainly in KRAS, BRCA2, FLT3 and HNF1A, genes. Pathogenic mutations were detected in 50% of plasma samples from patient diagnosed at stages III-IV samples. FLT3 mutations were observed in 22.22% of samples which constitute a novel result in the field. CONCLUSIONS: Liquid biopsy using NGS is a valuable tool but still not sensitive or specific enough to provide clinical utility in pancreatic cancer patients.

RNA-Seq analysis of ileocecal valve and peripheral blood from Holstein cattle infected with Mycobacterium avium subsp. paratuberculosis revealed dysregulation of the CXCL8/IL8 signaling pathway.

Paratuberculosis is chronic granulomatous enteritis of ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). Whole RNA-sequencing (RNA-Seq) is a promising source of novel biomarkers for early MAP infection and disease progression in cattle. Since the blood transcriptome is widely used as a source of biomarkers, we analyzed whether it recapitulates, at least in part, the transcriptome of the ileocecal valve (ICV), the primary site of MAP colonization. Total RNA was prepared from peripheral blood (PB) and ICV samples, and RNA-Seq was used to compare gene expression between animals with focal or diffuse histopathological lesions in gut tissues versus control animals with no detectable signs of infection. Our results demonstrated both shared, and PB and ICV-specific gene expression in response to a natural MAP infection. As expected, the number of differentially expressed (DE) genes was larger in the ICV than in the PB samples. Among the DE genes in the PB and ICV samples, there were some common genes irrespective of the type of lesion including the C-X-C motif chemokine ligand 8 (CXCL8/IL8), apolipoprotein L (APOLD1), and the interferon inducible protein 27 (IFI27). The biological processes (BP) enriched in the PB gene expression profiles from the cows with diffuse lesions included the killing of cells of other organism, defense response, immune response and the regulation of neutrophil chemotaxis. Two of these BP, the defense and immune response, were also enriched in the ICV from the cows with diffuse lesions. Metabolic analysis of the DE genes revealed that the N-glycan biosynthesis, bile secretion, one-carbon pool by folate and purine metabolism were significantly enriched in the ICV from the cows with focal lesions. In the ICV from cows with diffuse lesions; the valine, leucine and isoleucine degradation route, purine metabolism, vitamin digestion and absorption and the cholesterol routes were enriched. Some of the identified DE genes, BP and metabolic pathways will be studied further to develop novel diagnostic tools, vaccines and immunotherapeutics.

Promoter influences transcription elongation: TATA-box element mediates the assembly of processive transcription complexes responsive to cyclin-dependent kinase 9.

Pausing of RNA polymerase II (RNAPII) during transcript elongation is an important mechanism for regulating gene expression at many genes. In this study we investigated the mechanism of regulated elongation of c-myc and human immunodeficiency virus-1 (HIV-1) using an in vitro elongation assay that reproduces the conditional block to elongation. We found that HIV-1 Tat can activate the RNAPII transcription complexes paused on c-myc by enhancing their elongation efficiency. We determined that cyclin-dependent kinase 9 (CDK9), the kinase subunit of positive transcription elongation factor b (P-TEFb) complex, regulates transcriptional elongation of c-myc and is present in transcription pre-initiation complexes formed on the c-myc promoter, which emphasizes a common mechanism of elongation control between HIV-1 and c-myc genes. We also investigated the roles of upstream elements of the HIV-1 and c-myc promoters in CDK9-activated transcriptional elongation. We found that the TATA-box element mediates the assembly of processive transcription complexes responsive to CDK9 and that specific combinations of upstream activation binding sites contribute to the recruitment of these complexes. We propose a common mechanism for elongation control at the c-myc and HIV-1 genes with an essential role for the TATA-box and specific modulatory contribution of upstream regulatory sequences, derived from the unique structure of the promoters, to form a composite surface for efficient recruitment of elongation-competent transcription complexes.