Gene Expression Profiling and Phenotypic Characterization of Circulating Tumor Cells Derived from a Murine Osteosarcoma Model.

Background/objectives: Osteosarcoma is an aggressive bone malignancy with high metastatic potential to the lungs. CTCs, as seeds of metastasis, play an important role in the spread of this cancer, and, therefore, their isolation, culture, and gene expression analysis promises valuable insights into the progression and metastatic cascade of osteosarcoma. The aim of this study was to isolate and culture CTCs from osteosarcoma-bearing mice and compare their migration, radioresistance, and gene expression with their parental cell line.

Methods: CTCs from LM8-inoculated mice were isolated and cultured. The gene expression of the CTC-derived cell lines was then compared to the parental cell line. Furthermore, a Transwell assay, a clonogenic assay after irradiation, and immunohistochemical stainings were used to compare the CTC-derived cell lines with the parental cell line.

Results: The CTC-derived cell lines differed significantly in gene expression from their parental cell line. 361 differentially expressed genes were identified, among which GO and KEGG analysis revealed major differences in the expression of genes related to antigen processing and presentation and extracellular matrix constituents. In addition, the CTC-derived cell lines were observed to have a higher migratory capacity and comparable radioresistance compared to the parental cell line. CD44 expression was found to be conserved in CTC-derived cell lines.

Conclusions: This study provides a comparison between CTC-derived and their parental cell lines in terms of gene expression, migration, and radioresistance. Our findings allow for further research in the field of osteosarcoma CTCs and their generation. Furthermore, the identified DEGs between CTCs and their parental cell line can serve as a reference point for targeted therapies against osteosarcoma CTCs.