Purpose: Osteosarcoma (OS) is the most common type of cancer in children. OS demonstrates aggressive growth with a high risk of early, pulmonary metastasis. Here we investigated expression of malignancy-related factors in six osteosarcoma cell lines (SaOS, MNNG/ HOS, MG63, SW1353, SKES, SJSA), ten biopsies of primary OS and OS derived cells.
Methods: For this project, we are using RT-PCR and immunohistochemistry to detect PARP, ET-1, ETA and ETB receptor. We also, examined the expression of osteocrin by in situ hybridization. Zymography and Northern Blot were use to observe the presence of gela-tinases (MMP-2 and MMP-9) and finally, we showed the presence of ET-1(1–31) by Elisa-immunoassay.
Results: In OS tissues and cells, we observed ET-1, MMP-2, and ETA receptor overexpression, in contrast to under-expression of MMP-9 and ETB receptor. Additionally, in high malignant OS cells, MMP-2, MMP-3, MMP-13 and PARP were overexpressed and TIMP-1, TIMP-2 and TIMP-4 expressed at low levels. Using a new specific immunoassay for ET-1 (1–31) we showed presence of this alternative form of ET-1 in OS-derived cells. We also showed that, in cells exposed to ET-1, the inhibition of NF-kB pathway (NF-kB is an ubiquitous transcription factor playing a central role in differentiation, proliferation and malign transformation) drastically blocked MMP-2 production and activity, and that ET-1 induces NF-kB p65 unit translocation to the nucleus.
Conclusions: Thus, we concluded that expression of malignancy-related factors in parallel to the histological evaluation of these tumors, could be beneficial for malignancy understanding. Tumor cells invasion and aggressiveness of OS cells are the results, in part, of the tumorigenic potential of alternative forms of ET-1 generated by MMPs and enhanced in malignant microenvironment. These factors could be predictive for tumoral progression. Funding: Educational Grant from the Canadian Orthopaedic Foundation. Funding Parties: Canadian Orthopaedic Foundation (Carrol A. Laurin Award) and MENTOR program of CIHR
