Functional differences between metastasic and non-metastasic osteosarcoma cells and different potential in their capacity to induce differentiation

VALENZUELA ALVAREZ, MATIAS; GUTIERREZ, LUCIANA M.; BAYO FINA, JUAN; ALANIZ, LAURA; CALVO JUAN; CHASSEING N. A; KLEINERMAN, EUGENIE S.; CORREA, ALEJANDRO ; GARCIA, MARIANA G.; BOLONTRADE, MARCELA F.

Congreso; Reunión Conjunta de Sociedades de Biociencias, LXIII Reunión Anual SAIC, Sociedad Argentina de Investigación Clínica. SAI. SAFIS; 2018

SAIC, SAI, SAFIS

Osteosarcoma (OS) is the most common bone malignant tumor, affecting mainly children and young adults. Lung metastasis is a therapeutic challenge during osteosarcoma progression (15?30% survival rate with pulmonary metastasis at diagnosis). Niche establishment is critical for metastasis. Through proteomic analysis we demonstrated differential gene expression related to molecular function between metastasic OS (LM7) and non-metastasic (SAOS2) OS cell lines. Molecular differences were reflected in variations in the differentiation capacity in the two OS cell lines that differ in their metastatic ability. Differentiation capacity was evaluated by Alizarin Red staining and absorbance (abs) measurement by spectrophotometry. We demonstrated that SAOS2 had higher differentiation capacity towards osteoblastic lineage than LM7 (0.09042±0.0096 abs vs 0.06937±0.0049 abs, respectively) suggesting that LM7 suffer a loss of differentiation potential in the process of gaining metastasic traits. We use conditioned medium (CM) of OS cells lines to evaluate their capacity to induce differentiation and SAOS2 CM increase the differentiation of metastasic and non-metastasic cells towards osteoblastic lineage (LM7: 0.1111±0.02136 abs vs 0.09189±0.01156 abs, SAOS2 CM and LM7 CM respectively), indicating that the paracrine effect of non-metastasic cells may account for calcification observed in lungs. When CM of OS cells were used in tube formation assay, LM7 induced higher morphogenic rearrangements in microendothelial cell (HMEC-1) monolayers, indicating that even though LM7 had a diminished ability to differentiate and to induce differentiation, they can induce microendothelial cell rearrangements, a step associated to the angiogenic cascade. Further proteomic analysis show an increase in calcium ion binding proteins in the CM of SAOS2 . All these points out not only a change of phenotype in metastasic OS cells, but also to a selective ability to induce differentiation in other cells, losing characteristics of the bone microenvironment but gaining traits that could favour the establishment of a suitable metastatic niche.