The histological response to chemotherapy is currently the strongest prognostic factor in osteosarcoma (OS). However, the histological response to chemotherapy can only be assessed after pre-operative chemotherapy. Therefore, there is a need to stratify patients before starting pre-operative chemotherapy into chemo-sensitive and chemo-resistant patients to improve the outcome and to minimize the toxicity of therapy. In the last past few years, genetic biomarkers that predict drug-sensitivity of OS have been under investigation. However, the instructive role of microRNA remains unexplored. In this study, we aimed to identify novel chemo-responsiveness biomarkers using microRNA-microarray analysis.
The differentially expressed miRNA profiles of OS between chemo-sensitive (n = 4) and chemo-resistant (n = 4) were analyzed by microarray. qRT-PCR was further performed to verify the expression of selected miRNAs. We further investigated the functions of these miRNAs using cytotoxicity assay, cell roliferation assay and apoptosis assay with OS cells. Then, expression of candidate miRNAs was analyzed in a total of 20 OS patients as validation study.
The microarray analysis revealed differentially expressed miRNAs between chemo-sensitive and chemo-resistant group, 5 miRNAs were upregulated and 1 was downregulated in chemo-resistant group (FD> 2, P < 0.05). qRT-PCR verified statistically consistent expression of two selected miRNAs with microarray analysis. In vitro analysis revealed that overexpression of these miRNAs was related to increasing drug resistance, up-regulation of cell proliferation, and suppression of apoptosis. Then, Gene expression of 2 candidate genes was analyzed in 20 formalin-fixed, paraffin-embedded OS biopsy samples. Expression of two miRNAs was significantly increased in the non-responder group (P < 0.01). Predictive accuracy was evaluated by ROC curve analysis; AUC was 0.91 and 0.90, respectively.
These data demonstrate that these miRNAs are valuable biomarkers for the prediction of OS chemotherapy. Theyse miRNAs may further be targets for the modulation of drug sensitivity and the development of novel therapeutic strategies.
Clinical trial identification
All authors have declared no conflicts of interest.