Two histologically colorectal carcinomas subsets from the serrated pathway show different methylome signatures and diagnostic biomarkers.

BACKGROUND: Altered methylation patterns are driving forces in colorectal carcinogenesis. The serrated adenocarcinoma (SAC) and sporadic colorectal carcinoma showing histological and molecular features of microsatellite instability (hmMSI-H) are two endpoints of the so-called serrated pathological route sharing some characteristics but displaying a totally different immune response and clinical outcome. However, there are no studies comparing the methylome of these two subtypes of colorectal carcinomas. The methylation status of 450,000 CpG sites using the Infinium Human Methylation 450 BeadChip array was investigated in 48 colorectal specimens, including 39 SACs and 9 matched hmMSI-H. RESULTS: Microarray data comparing SAC and hmMSI-H showed an enrichment in functions related to morphogenesis, neurogenesis, cytoskeleton, metabolism, vesicle transport and immune response and also significant differential methylation of 1540 genes, including CD14 and HLA-DOA which were more methylated in hmMSI-H than in SAC and subsequently validated at the CpG, mRNA and protein level using pyrosequencing, quantitative polymerase chain reaction (qPCR) and immunohistochemistry. CONCLUSIONS: These results demonstrate particular epigenetic regulation patterns in SAC which may help to define key molecules responsible for the characteristic weak immune response of SAC and identify potential targets for treating SAC, which lacks molecular targeted therapy.

Comparison of allelic discrimination by dHPLC, HRM, and TaqMan in the detection of BRAF mutation V600E.

The V600E mutation in the BRAF oncogene is associated with colorectal carcinomas, with mismatch-repair deficiency and, recently, with nonresponse to epidermal growth factor receptor inhibitor therapy. The use of reliable techniques for its detection is important. The aim of our study was to compare the performance characteristics in V600E detection of denaturing high-performance liquid chromatography (dHPLC) and high-resolution melting (HRM) with TaqMan allelic discrimination as well as direct-sequencing methods in a series of 195 colorectal paraffin-embedded specimens up to the age of 15 years. The effectiveness for obtaining results on mutation status was best using TaqMan (96.9%), followed by dHPLC (93.3%), HRM (88.7%), and sequencing (88.2%). In general, TaqMan was best for analyzing older tissues, whereas sequencing was the least efficient. Heterozygotic V600E was detected in 11.6%, 9.9%, 11.6%, and 9.9% of tissues using TaqMan, dHPLC, HRM, and sequencing, respectively. Result concordances between dHPLC and TaqMan or sequencing were excellent (κ = 0.9411 and κ = 0.8988, respectively); for HRM, the concordances were good (κ = 0.7973 and κ = 0.7488, respectively). By using DNA dilutions from tumor tissue, a minimum of 10% of V600E harboring cancer content was required for the analysis by dHPLC and HRM. dHPLC could detect four non-V600E mutations, whereas HRM detected one. Our results indicate that dHPLC and HRM are techniques that can be reliably used for the detection of the BRAFV600E mutation in archival paraffin-embedded tissues.

Differential actions of eplerenone and spironolactone on the protective effect of testosterone against cardiomyocyte apoptosis in vitro.

INTRODUCTION AND OBJECTIVES: Testosterone deficiency is associated with a poor prognosis in patients with heart failure. It is not clear whether testosterone reduces cardiomyocyte apoptosis or whether the effect of spironolactone, an aldosterone receptor blocker with progestogenic and anti-androgen activity, differs from that of the selective aldosterone blocker eplerenone. METHODS: Apoptosis induced by hyperosmotic stress in the embryonic rat heart cell line H9c2 was monitored by measuring cell viability, DNA fragmentation and caspase-3, -8 and -9 activation. The effect of testosterone was investigated in the presence or absence of spironolactone and eplerenone. RESULTS: Exposure to sorbitol (0.6 M, 3 h) decreased cell viability and increased DNA fragmentation and caspase-3, -8 and -9 activation. These effects were all significantly reduced by testosterone, 100 nM (P< .01). Pretreatment with spironolactone, 10 .M, blocked the effects of testosterone, decreased cell viability (P< .01) and increased caspase activation (P< .01). In contrast, eplerenone, 10 .M, increased cell viability (P< .001) without altering the effect on caspase activation. These actions were not modified by the androgen receptor blocker flutamide. They were mediated by SAPK/JNK and ERK1/2 signaling pathways (P< .01). CONCLUSIONS: Testosterone appears to have a protective effect against cardiomyocyte apoptosis which is antagonized by spironolactone but not by eplerenone. These effects await confirmation in in vivo models, but their presence could have clinical and therapeutic implications.

Efecto diferencial de espironolactona frente a eplerenona sobre el papel protector in vitro de testosterona en la apoptosis de cardiocitos / Differential actions of eplerenone and spironolactone on the protective effect of testosterone against cardiomyocyte apoptosis in vitro

Introducción y objetivos. La deficiencia de testosterona se asocia a un peor pronóstico en pacientes con insuficiencia cardiaca. Se desconoce si la testosterona disminuye la apoptosis de cardiomiocitos y si la espironolactona, bloqueador del receptor de aldosterona con actividad progestogénica y antiandrogénica, tiene un efecto diferencial respecto al bloqueo selectivo con eplerenona. Métodos. En la línea de cardiomioblastos de rata H9c2, se cuantificó la apoptosis inducida por estrés hiperosmótico mediante análisis de viabilidad celular, fragmentación del ADN y activación de caspasa 3, 8 y 9. Se estudiaron los efectos de testosterona, en presencia o ausencia de espironolactona y eplerenona. Resultados. La exposición al sorbitol (0,6 M, 3 h) disminuyó la viabilidad celular e incrementó la fragmentación del ADN y la activación de caspasa 3, 8 y 9. Estos efectos fueron disminuidos significativamente por la testosterona (100 nM) (p < 0,01). El pretratamiento con espironolactona (10 μM) bloqueó los efectos de la testosterona, disminuyó la viabilidad celular (p < 0,01) e incrementó la activación de caspasas (p < 0,01); por el contrario, la eplerenona (10 μM) incrementó la viabilidad (p < 0,001) sin alterar el efecto en las caspasas. Estas acciones no se modificaron por el bloqueo del receptor de andrógenos con flutamida y fueron mediadas por las rutas de señalización SAPK/JNK y ERK1/2 (p < 0,01). Conclusiones. La testosterona parece tener un efecto protector contra la apoptosis de células cardiacas, que la espironolactona contrarresta, pero no la eplerenona. Estos hallazgos precisan confirmación en modelos in vivo, pero de estar presentes podrían tener implicaciones clínicas y terapéuticas (AU)

Introduction and objectives. Testosterone deficiency is associated with a poor prognosis in patients with heart failure. It is not clear whether testosterone reduces cardiomyocyte apoptosis or whether the effect of spironolactone, an aldosterone receptor blocker with progestogenic and anti-androgen activity, differs from that of the selective aldosterone blocker eplerenone. Methods. Apoptosis induced by hyperosmotic stress in the embryonic rat heart cell line H9c2 was monitored by measuring cell viability, DNA fragmentation and caspase-3, -8 and -9 activation. The effect of testosterone was investigated in the presence or absence of spironolactone and eplerenone. Results. Exposure to sorbitol (0.6 M, 3 h) decreased cell viability and increased DNA fragmentation and caspase-3, -8 and -9 activation. These effects were all significantly reduced by testosterone, 100 nM (P < .01). Pretreatment with spironolactone, 10 μM, blocked the effects of testosterone, decreased cell viability (P < .01) and increased caspase activation (P < .01). In contrast, eplerenone, 10 μM, increased cell viability (P < .001) without altering the effect on caspase activation. These actions were not modified by the androgen receptor blocker flutamide. They were mediated by SAPK/JNK and ERK1/2 signaling pathways (P < .01). Conclusions. Testosterone appears to have a protective effect against cardiomyocyte apoptosis which is antagonized by spironolactone but not by eplerenone. These effects await confirmation in in vivo models, but their presence could have clinical and therapeutic implications (AU)

Mechanism of dimerization of the human melanocortin 1 receptor.

The melanocortin 1 receptor (MC1R) is a dimeric G protein-coupled receptor expressed in melanocytes, where it regulates the amount and type of melanins produced and determines the tanning response to ultraviolet radiation. We have studied the mechanisms of MC1R dimerization. Normal dimerization of a deleted mutant lacking the seventh transmembrane fragment and the C-terminal cytosolic extension excluded coiled-coil interactions as the basis of dimerization. Conversely, the electrophoretic pattern of wild type receptor and several Cys-->Ala mutants showed that four disulfide bonds are established between the monomers. Disruption of any of these bonds abolished MC1R function, but only the one involving Cys35 was essential for traffic to the plasma membrane. A quadruple Cys35-267-273-275Ala mutant migrating as a monomer in SDS-PAGE in the absence of reducing agents was able to dimerize with WT, suggesting that in addition to disulfide bond formation, dimerization involves non-covalent interactions, likely of domain swap type.