Potential Anti-Metastatic Role of the Novel miR-CT3 in Tumor Angiogenesis and Osteosarcoma Invasion.

Lavinia Raimondi,Viviana Costa,Riccardo Alessandro,Nicola Cuscino,Milena Fini,Alessia Gallo,Pier Giulio Conaldi,Gianluca Giavaresi,Valeria Carina,Matteo Bulati,Angela De Luca,Daniele Bellavia

doi:10.3390/ijms23020705

Abstract

Osteosarcoma (OS) is the most common primary bone tumor mainly occurring in young adults and derived from primitive bone-forming mesenchyme. OS develops in an intricate tumor microenvironment (TME) where cellular function regulated by microRNAs (miRNAs) may affect communication between OS cells and the surrounding TME. Therefore, miRNAs are considered potential therapeutic targets in cancer and one of the goals of research is to accurately define a specific signature of a miRNAs, which could reflect the phenotype of a particular tumor, such as OS. Through NGS approach, we previously found a specific molecular profile of miRNAs in OS and discovered 8 novel miRNAs. Among these, we deepen our knowledge on the fifth candidate renamed now miR-CT3. MiR-CT3 expression was low in OS cells when compared with human primary osteoblasts and healthy bone. Through TargetScan, VEGF-A was predicted as a potential biological target of miR-CT3 and luciferase assay confirmed it. We showed that enforced expression of miR-CT3 in two OS cell lines, SAOS-2 and MG-63, reduced expression of VEGF-A mRNA and protein, inhibiting tumor angiogenesis. Enforced expression of miR-CT3 also reduced OS cell migration and invasion as confirmed by soft agar colony formation assay. Interestingly, we found that miR-CT3 behaves inducing the activation of p38 MAP kinase pathway and modulating the epithelial-mesenchymal transition (EMT) proteins, in particular reducing Vimentin expression. Overall, our study highlights the novel role of miR-CT3 in regulating tumor angiogenesis and progression in OS cells, linking also to the modulation of EMT proteins.

Highlights

IntroductionOsteosarcoma (OS) is a primary malignant tumor of bone tissue, whose incidence shows a bimodal age distribution, affecting children and adolescents (with an initial peak at 12–14 years of age) and adults (over 60th) [1]
Osteosarcoma (OS) is a primary malignant tumor of bone tissue, whose incidence shows a bimodal age distribution, affecting children and adolescents and adults [1]
MiR-CT3 expression was evaluated in two OS cell lines (SAOS-2 and MG-63), human primary osteoblasts and healthy bone tissue; low levels of miR-CT3 were detected in OS cells when compared with both hOBs and healthy bone tissue (Figure 1B,C)

Summary

Introduction

Osteosarcoma (OS) is a primary malignant tumor of bone tissue, whose incidence shows a bimodal age distribution, affecting children and adolescents (with an initial peak at 12–14 years of age) and adults (over 60th) [1]. The five-year survival rate for patients diagnosed with non-metastatic OS has increased to 70–80% through wide resection surgery combined with multi-drug adjuvant chemotherapy [2]. More than 60% patients developed metastasis during treatment with 39% presenting lung metastasis [3]. The 5-year survival rate of patients who develop chemo-resistance decreased to less than 20%, supporting in turn a rapid growth of metastatic lesions [4]. The improvement in OS treatment (surgery and chemotherapy) and the advances in understanding the molecular mechanisms underlying OS pathogenesis have altogether increased the long-term survival rate. A further issue of great importance regards micro-metastasis, which is estimated to be present in over half a percentage of patients without lung metastasis at initial examination [9,10]. Despite recent advances, discovery of novel biomarkers for OS diagnosis, prediction of response to therapy and disease progression is still necessary [11]

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Conclusion