Chromosomally Unstable Gastric Cancers Overexpressing Claudin-6 Disclose Cross-Talk between HNF1A and HNF4A, and Upregulated Cholesterol Metabolism.

(1) Abnormally increased expression of claudin-6 in gastric cancer is considered a prognostic marker of the chromosomal unstable molecular subtype. However, a detailed molecular profile analysis of differentially expressed genes and affected pathways associated with claudin-6 increased (Cldn6high) expression has not been assessed. (2) The TCGA Stomach Adenocarcinoma Pan-Cancer Atlas Data was evaluated using Cytoscape's Gene Mania, MCODE, and Cytohubba bioinformatic software. (3) 96.88% of Cldn6high gastric cancer tumors belonging to the chromosomal unstable molecular subtype are associated with a worse prognosis. Cldn6expression coincided with higher mutations in TP53, MIEN1, STARD3, PGAP3, and CCNE1 genes compared to Cldn6low expression. In Cldn6high cancers, 1316 genes were highly expressed. Cholesterol metabolism was the most affected pathway as APOA1, APOA2, APOH, APOC2, APOC3, APOB-100, LDL receptor-related protein 1/2, Sterol O-acyltransferase, STARD3, MAGEA-2, -3, -4, -6, -9B, and -12 genes were overexpressed in Cldn6high gastric cancers; interestingly, APOA2 and MAGEA9b were identified as top hub genes. Functional enrichment of DEGs linked HNF-4α and HNF-1α genes as highly expressed in Cldn6high gastric cancer. (4) Our results suggest that APOA2 and MAGEA9b could be considered as prognostic markers for Cldn6high gastric cancers.

Claudin-6 increases SNAI1, NANOG and SOX2 gene expression in human gastric adenocarcinoma AGS cells.

BACKGROUND: Gastric cancer is a heterogeneous disease associated to deregulated gastric epithelia tight junction barrier function and di novo expression of claudin-6; these changes are associated with epithelial-mesenchymal transition, enhanced invasiveness, metastatic progression, resistance to chemotherapy, and poor prognosis. Gastric cancer stem cells represent a rare population of cells within the tumor implicated in tumor growth and higher tumorigenic capacity. The possible relation between claudin-6 expression and the expression of some markers associated to epithelial mesenchymal transition and cancer stem cells in gastric cancer cells have never been explored. METHODS AND RESULTS: CD44, CD24, Twist, Villin, DCLK1, claudin-6, NANOG, E-Cadherin, SOX2, and SNAI1 expression was evaluated by immunofluorescence and cytofluorometry in wild type and Claudin-6 transfected AGS cells. Cell migration assays were also performed. Differentially expressed genes and biological processes analysis was performed to determine gene preponderance. The results showed that claudin-6 overexpression enriched the CD44 + /CD24- subpopulation with an overall increase in the expression and the number of CD44 + cells. A significant increase in NANOG, SOX2 and SNAI1 expression and enhanced cell migration was observed in claudin-6 transfected cells. Transcriptome analysis revealed 271 genes involved in enhanced biological processes with only 31 with a significantly p value; thirteen of those genes are closely associated to epithelial mesenchymal transition processes and folding and unfolding processes of proteins in the endoplasmic reticulum. CONCLUSIONS: The pro-tumorigenic effect of claudin-6 in gastric cancer could be associated to dedifferentiation of epithelial cells and an increase in di novo cancer stem cell genesis.

¿Qué son los inflamosomas? El NLRP3 como por ejemplo / What are inflammasomes? The NLRP3 as an example

Resumen Una de las prácticas médicas más concurridas en la actualidad es el uso indiscriminado de medicamentos con actividad inhibidora de la inflamación. Sin embargo la inflamación es un proceso de reparación biológica fuertemente controlado por complejos intracelulares, conocidos como inflamosomas, que actúan como sensores y mediadores de la misma. Los inflamosomas forman parte de la familia de receptores tipo NOD que está formada de 3 subfamilias: NOD (nucleotide-binding oligomerization domain), NLRC (NOD-like receptor CARD domain containing) y NLRP (NOD-like receptor Pyrin domain containing), que es la que se relaciona con la formación de inflamosomas. Existen 14 diferentes tipos de NLRP. Los miembros de la familia NLRP responden a señales exógenas mediadas por PAMPs (pathogen-associated molecular patterns) o a señales endógenas mediadas por DAMPs (damage-associated molecular patterns, [también conocidas como alarminas]). Los componentes de los inflamosomas tipo NLRP, una vez activado, se ensamblan de acuerdo a un patrón determinado y forman un complejo que activa a la caspasa-1 que activa a los precursores de IL-1b, IL-18 e IL-33, favoreciendo la secreción de estas citosinas hacia el espacio extracelular. La IL-1 y la IL-18 son miembros de la misma familia y se les reconoce como reguladores de la respuesta inmune innata y adaptativa, la IL-33 también es miembro de la familia de IL-1 y se le considera una alarmina. A manera de ejemplo, en el presente manuscrito describimos la estructura y formación del inflamosoma NLRP3 y mencionamos algunas de las enfermedades en las que se activa, enfatizando de manera muy particular su participación en la enfermedad de Alzheimer.

Abstract One highly common medical malpractice is the undiscriminatory use of inflammation inhibiting drugs. Inflammation is a biological repair process vastly controlled by intracellular complexes known as the inflammasome that act as sensors and mediators of the inflammation process. Inflammasomes are members of the NOD innate immune system family of receptors that consist of 3 closely related subfamilies: nucleotide-binding oligomerization domain (NOD), NOD-like receptor CARD domain containing (NLRC), and NOD-like receptor Pyrin domain containing (NLRP); the latter is the most directly related to the inflammasome. There are 14 different NLRPs all of which are activated by exogenous signals through pathogen-associated molecular patterns (PAMPs) or by endogenous signals via damage-associated molecular patterns, also known as alarmins, are endogenous molecules constitutively available and released upon tissue damage (DAMPs). Once activated, the components of the NLRP inflammasome begin an assembling process that follows a pre-established pattern so a caspase-1 activating complex is formed. This complex activates IL-1b, IL-18 and IL-33 precursors thus favoring the secretion of this cytokines to the extracellular milieu. IL-1 and IL-18 are members of the same cytokine family and their main function is to regulate the innate and adaptive immune response whereas IL-33, also a member of the IL-1 family of cytokines, is considered an alarmin. We emphasize the structure and formation of NLRP3, implicated on a host of inflammatory disorders, with special attention to its participation in Alzheimer´s diseases.

Claudin-6, 7, or 9 overexpression in the human gastric adenocarcinoma cell line AGS increases its invasiveness, migration, and proliferation rate.

Altered claudin expression is related to metastatic potential, poor prognosis, or tumor recurrence. We analyzed if the overexpression of claudin-6, claudin-7, or claudin-9 in AGS cells altered cell motility, invasiveness, or proliferation rate. Claudin-7, claudin-9, and claudin-6 enhanced their invasive potential by 3.4-fold, 1.6-fold, and 2.0-fold, respectively. Claudin-6 and claudin-9 enhanced cell migration, while the proliferation rate of claudin-6-, claudin-7-, and claudin-9-transfected cells increased by 12.7%, 9.0%, and 13.3%, respectively. Claudin-7 and claudin-9 overexpression increased claudin-1 and zonula occludens-1 levels. In summary, individual increased expression of claudin-6, claudin-7, or claudin-9 is sufficient to enhance tumorigenic properties of a gastric adenocarcinoma cell line.