At 21-25 nucleotides long, MicroRNAs (miRNA) are non-coding, regulators of gene expression at the posttranscriptional level through degradation and/or inhibition of mRNA translation. miRNAs have been associated with various human diseases, although its precise role in metabolic bone diseases such as osteoporosis is unclear. The aim of this study is to investigate the involvement of miRNA at different stages of human bone development. We investigated miRNA expression in three human osteosarcoma cell lines representing different stages of osteoblast differentiation, MG-63 the least differentiated, TE-85 intermediate and SaOS-2 the most mature. In the other study, we found that SaOS-2 expressed the highest level of sclerostin and alkaline phosphatase followed by TE85 and MG63. This result confirms that SaOS-2 is the most mature while MG63 is the least differentiated. All cell lines were cultured in DMEM +10% FCS. Total RNA was extracted from confluent cell culture. More than 500 miRNAs were differentially expressed, those with the largest difference in expression were hsa-miR-935, hsa-miR-143-3p, hsa-miR-145-5p, hsa-miR-155-5p, hsa-miR-3200-3p, hsa-miR-584-5p, hsa-miR-486-3p, hsa-miR-767-5p and hsa-miR-105-5p. miR-935 was expressed highest in TE85 and lowest in SaOS-2 (P<0.05). Expression of miR-143-3p and miR-155-5p was significantly higher in TE85 and SaOS-2 cells compared to MG63 (P<0.05). However, MG63 showed highest expression of miR-155-5p, miR-3200-3p and miR-584-5p compared with TE85 and SaOs-2 (P<0.05). The most striking observation to emerge from the data comparison was the expression of miR-155-5p in MG63 was 2842-fold greater than SaoS-2 and 1467-fold greater in TE85 than SaOS-2. Meanwhile, miR-486-3p, miR-767-5p and miR-105-5p were highest in SaOS-2 compared with MG63 and TE85 (P<0.05). Our data shows that different stages of osteoblast development are characterised by different sets of highly expressed microRNAs and suggests that miRNAs could be potential biomarkers in bone development and may provide the basis of new therapeutic approaches to prevent bone loss.
Disclosure: The authors declared no competing interests. This work is supported by the Ministry of Education Malaysia and Universiti Putra Malaysia.