In the development of the skeleton, the long bones are arising from the process of endochondral ossification (EO) in which cartilage is replaced by bone. This complex process is regulated by various factors including genetic, epigenetic, and environmental elements. It is recognized that DNA methylation, higher-order chromatin structure, and post-translational modifications of histones regulate the EO. With emerging understanding, non-coding RNAs (ncRNAs) have been identified as another mode of EO regulation, which is consist of microRNAs (miRNAs or miRs) and long non-coding RNAs (lncRNAs). There is expanding experimental evidence to unlock the role of ncRNAs in the differentiation of cartilage cells, as well as the pathogenesis of several skeletal disorders including osteoarthritis. Cutting-edge technologies such as epigenome-wide association studies have been employed to reveal disease-specific patterns regarding ncRNAs. This opens a new avenue of our understanding of skeletal cell biology, and may also identify potential epigenetic-based biomarkers. In this review, we provide an updated overview of recent advances in the role of ncRNAs especially focus on miRNA and lncRNA in the development of bone from cartilage, as well as their roles in skeletal pathophysiology.

Background: Breast cancer (BC) is the most common malignancy among females with dismal quality of life in patients. It has been proven that epigenetic factors, especially microRNAs, are involved in breast carcinogenesis and progression. This study aimed to assess the expression and clinical performances of a five‐microRNA signature (miR‐127‐3p, miR‐133a‐3p, miR‐155‐5p, miR‐199b‐5p, and miR‐342‐5p) in breast cancer and adjacent normal tissues to identify a potential biomarker for BC and investigate the relationship between their expression and clinicopathological features of BC patients as well. Methods: In this case‐control investigation, we recruited 50 pairs of tumor and matched non‐tumor surgical specimens from patients diagnosed with BC. Expression levels of miR‐127‐3p, miR‐133a‐3p, miR‐155‐5p, miR‐199b‐5p, and miR‐342‐5p were measured in BC and adjacent normal tissues by RT‐qPCR. Results: We found that miR‐127‐3p, miR‐133a‐3p, miR‐199b‐5p, and miR‐342‐5p were significantly down‐regulated, while miR‐155‐5p was significantly up‐regulated in BC tumor tissues compared with the corresponding adjacent normal tissues. The decreased expression of miR‐127‐3p, miR‐133a‐3p, miR‐342‐5p, and up‐regulation of miR‐155‐5p showed a significant correlation with disease stage. We also found a significant down‐regulation of miR‐127‐3p, miR‐199b‐5p, and miR‐342‐5p compared in HER‐2‐negative patients. Our results indicated that miR‐155‐5p had a higher expression level in HER‐2‐positive patients. Receiver operating characteristic (ROC) curve analysis demonstrated that all these five microRNAs can serve as potential biomarkers to distinguish between tumor and non‐tumor breast tissue samples. Conclusions: The present findings suggested that dysregulation of this five‐miRNA signature might be considered as a promising and functional biomarker for BC diagnosis.