A common characteristic of ageing is disrupted homeostasis between growth and atrophy of skeletal muscle resulting in loss of muscle mass and function, which is associated with sarcopenia. Sarcopenia is related to impaired balance, increased falls and decline in quality of life of older people. Ageing-related transcriptome and proteome changes in skeletal muscle have been characterised, however the molecular mechanisms underlying sarcopenia are still not fully understood. microRNAs are novel regulators of gene expression known to modulate skeletal muscle development and homeostasis. Expression of numerous microRNAs is disrupted in skeletal muscle with age however, the functional consequences of this are not yet understood. Given that a single microRNA can simultaneously affect multiple signalling pathways, microRNAs are potent modulators of pathophysiological changes occurring during ageing. Here we use microRNA and transcript expression profiling together with microRNA functional assays to show that disrupted microRNA:target interactions play an important role in maintaining muscle homeostasis. We identified miR-181a as a regulator of the sirtuin1 (Sirt1) gene expression in skeletal muscle and show that the expression of miR-181a and its target gene is disrupted in skeletal muscle from old mice. Moreover, we show that miR-181a:Sirt1 interactions regulate myotube size. Our results demonstrate that disrupted microRNA:target interactions are likely related to the pathophysiological changes occurring in skeletal muscle during ageing.Electronic supplementary materialThe online version of this article (doi:10.1007/s10522-016-9638-8) contains supplementary material, which is available to authorized users.

Objective This study investigated mice serum and joint microRNA expression profiles in ageing and osteoarthritis to elucidate the role of microRNAs in the development and progression of disease, and provide biomarkers for ageing and osteoarthritis. Design Whole joints and serum samples were collected from C57BL6/J male mice and subjected to small RNA sequencing. Groups used included; surgically-induced post-traumatic osteoarthritis, (DMM; 24 months-old); sham surgery (24 months-old); old mice (18 months-old); and young mice (8 months-old). Differentially expressed microRNAs between the four groups were identified and validated using real-time quantitative PCR. MicroRNA differential expression data was used for target prediction and pathway analysis. Results In joint tissues, miR-140–5p, miR-205–5p, miR-682, miR-208b-3p, miR-499–5p, miR-455–3p and miR-6238 were differentially expressed between young and old groups; miR-146a-5p, miR-3474, miR-615–3p and miR-151–5p were differentially expressed between DMM and Sham groups; and miR-652–3p, miR-23b-3p, miR-708–5p, miR-5099, miR-23a-3p, miR-214–3p, miR-6238 and miR-148–3p between the old and DMM groups. The number of differentially expressed microRNAs in serum was higher, some in common with joint tissues including miR-140–5p and miR-455–3p between young and old groups; and miR-23b-3p, miR-5099 and miR-6238 between old and DMM groups. We confirmed miR-140–5p, miR-499–5p and miR-455–3p expression to be decreased in old mouse joints compared to young, suggesting their potential use as biomarkers of joint ageing in mice. Conclusions MiR-140–5p, miR-499–5p and miR-455–3p could be used as joint ageing biomarkers in mice. Further research into these specific molecules in human tissues is now warranted to check their potential suitability as human biomarkers of ageing.

Colorectal cancer (CRC) with a mesenchymal gene expression signature has the greatest propensity for distant metastasis and is characterised by the accumulation of cancer‐associated fibroblasts in the stroma. We investigated whether the epithelial to mesenchymal transition status of CRC cells influences fibroblast phenotype, with a focus on the transfer of extracellular vesicles (EVs), as a controlled means of cell–cell communication. Epithelial CRC EVs suppressed TGF‐β‐driven myofibroblast differentiation, whereas mesenchymal CRC EVs did not. This was driven by miR‐200 (miR‐200a/b/c, ‐141), which was enriched in epithelial CRC EVs and transferred to recipient fibroblasts. Ectopic miR‐200 expression or ZEB1 knockdown, in fibroblasts, similarly suppressed myofibroblast differentiation. Supporting these findings, there was a strong negative correlation between miR‐200 and myofibroblastic markers in a cohort of CRC patients in the TCGA dataset. This was replicated in mice, by co‐injecting epithelial or mesenchymal CRC cells with fibroblasts and analysing stromal markers of myofibroblastic phenotype. Fibroblasts from epithelial tumours contained more miR‐200 and expressed less ACTA2 and FN1 than those from mesenchymal tumours. As such, these data provide a new mechanism for the development of fibroblast heterogeneity in CRC, through EV‐mediated transfer of miRNAs, and provide an explanation as to why CRC tumours with greater metastatic potential are CAF rich.

Purpose: The major risk factor for osteoarthritis (OA) is old age. However, the relationship between aging and OA is incompletely understood. Among the joint changes associated with old age are chondrocyte senescence, the decline in matrix production and an altered response to trauma. However, a systemic component of premature aging has also been suggested by the increased presence of old-age comorbidities in the OA patients and by a biomarker of cellular age, telomere length. Telomere shortening has been observed in OA chondrocytes, but also in a study of blood cells from hand OA patients (Zhai et al. Ann Rheum Dis 2006). The reproducibility and implications of these changes in blood cells are still unclear. The recent discovery of a new biomarker of cellular age provides a new opportunity to address these questions. This biomarker is made of changes in DNA methylation at specific sites in the genome. It correlates with chronological age in healthy controls more accurately than telomere length. Therefore, we have analyzed this biomarker at the blood, cartilage and bone levels to distinguish between joint specific and systemic evidence of accelerated aging. Methods: Three collections of samples were investigated. The first included 890 blood samples stratified as 273 from severe hip OA patients, 229 from severe knee OA patients, 206 from hand OA patients and 182 from controls without OA symptoms and without OA in hip radiographs. The second collection included tibial plateau cartilage samples from 18 cadavers with no macroscopic signs of OA and from 23 knee OA patients undergoing joint replacement surgery. The third collection included femoral head bone samples from 34 osteoporosis fracture (OP) patients, 11 healthy control cadavers without signs of OA and 33 hip OA patients at the time of total joint replacement. Methylation age was determined by analyzing CpG methylation at specific sites. For the blood samples, we analyzed a panel of eight sites derived from Weidner et al. (Genome Biol. 2014) and analyzed with methylation-sensitive single-nucleotide primer extension. For the cartilage and bone samples, we used a panel of 353 age-related CpG sites described by Horvath in (Genome Biol. 2013) as multi-tissue age predictor. Methylation data for these analyses were obtained with the Illumina Methylation array. Statistical analysis included comparison of methylation age between OA patients and controls with ANCOVA (age and sex as covariates), or with t-test comparing model-adjusted ages. Results: The blood 8 CpG panel produced methylation age that showed a median absolute deviation of 5.07 years and r 2 ¼ 0.68 (p < 10 À16 ) in relation with chronological age in the published set of 390 healthy controls (ages 20 to 80 years) from Weidner et al. These estimates were better than the obtained with the previously proposed panels with 3 CpG or 5 CpG for blood. When the 8 CpG panel was applied to our 182 controls without OA, methylation age showed an absolute median deviation of 6.7 years and r 2 ¼ 0.52 (p < 10 À16 ) in r...

Cancer-associated fibroblasts are critical to tumor progression. There exists a dynamic crosstalk between cancer and stromal compartments, which maintains a permissive tumor microenvironment. Extracellular vesicles (EVs) play a significant role in this intercellular communication. Colorectal cancer (CRC) cells can be categorized according to epithelial-mesenchymal transition (EMT) status, and therefore metastatic capacity. We aimed to investigate the effect of EMT on EV-mediated cancer-fibroblast signaling. CRC cell lines (DLD-1, HCT116, SW620 and SW480) were characterized by western blotting to determine EMT status. EVs were isolated from conditioned media by serial centrifugation and validated by transmission electron microscopy, western blotting and nanoparticle tracking analysis. Fluorescently labeled EVs and cells were detected and evaluated by flow cytometry and fluorescence microscopy. Increasing concentrations of EVs from CRC cells were co-cultured with fibroblasts for 24h. Activation/inhibition of signaling pathways was examined by western blotting. EV microRNA (miRNA) profiles were obtained, validated by qPCR and submitted for target and pathway analysis. DLD-1, HCT116 and SW620 cells express E-cadherin and are considered epithelial, whereas SW480 lacks E-cadherin, expresses ZEB-1, and is considered mesenchymal. EVs were spherical, enriched in ALIX, TSG101, CD63 and had a mean diameter of 90nm. EVs from CRC cells were shown to transfer directly to primary ex vivo patient-derived fibroblasts and fibroblast cell lines. Transfer of EVs from epithelial CRC cells abrogated ERK activity in fibroblasts, even at the lowest concentration, and was associated with reduced fibroblast proliferation, whereas EVs from mesenchymal cells had no effect. MiRNA profiling of EVs from epithelial and mesenchymal CRC cells showed a 10-fold upregulation of miR-143-3p in epithelial compared to mesenchymal EVs. MiRNA target analysis and experimental validation show that miR-143-3p directly targets KRAS and HRAS, providing a potential miRNA-orchestrated mechanism of action for the downregulation of fibroblast ERK activity in the tumor microenvironment. Importantly, CRC cellular ERK activity is not reflected in fibroblasts treated with CRC EVs, suggesting that EVs do not directly transmit ERK protein or mRNA. However, miRNAs are the most stable EV cargo, and we show that epithelial but not mesenchymal CRC EVs contain upregulated miRNAs, which target critical components of the ERK pathway. Downregulation of ERK activity has been shown to induce fibroblast senescence, a phenotype linked to cancer progression. We hypothesize that differential regulation occurs because epithelial CRC cells are juxtaposed with fibroblasts in the tumor core, where senescent cancer associated fibroblasts are frequently observed, whereas mesenchymal CRC cells are at the invasive front or in the circulation. Citation Format: Rahul Bhome, Louise M. House, Tilman Sanchez-Elsner, Stephen M. Thirdborough, Emre Sayan, Alex H. Mirnezami. Metastatic and non-metastatic colorectal cancer cells differentially regulate fibroblast cell cycle via extracellular vesicles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2982. doi:10.1158/1538-7445.AM2017-2982