Establishment and characterization of novel patient-derived extraskeletal osteosarcoma cell line NCC-ESOS1-C1

Extraskeletal osteosarcoma (ESOS) is a rare mesenchymal malignancy producing osteoid and bone in soft tissue without skeletal attachment. ESOS exhibits chemoresistance and poor prognosis, and is distinct from osseous osteosarcoma. The biological characteristics of ESOS are not fully understood, and patient-derived cell lines of ESOS are not available from public cell banks. Here, we established a novel cell line of ESOS and characterized its genetic and biological characteristics as well as examined its response to anti-cancer reagents. The cell line was established using tumor tissue from a 58-year-old female patient with ESOS, and named as NCC-ESOS1-C1. Phenotypes relevant to malignancy such as proliferation and invasion were examined in vitro, and genetic features were evaluated using the NCC Oncopanel assay. The response to inhibitors was monitored by screening of an anti-cancer reagent library. The cells constantly proliferated, showing spheroid formation and invasion capabilities. The NCC Oncopanel revealed the presence of actionable mutations in PIK3CA. Library screening revealed the presence of anti-cancer reagents with significant anti-proliferative effects on NCC-ESOS1-C1 at a low concentration. In conclusion, we established and characterized a novel ESOS cell line, NCC-ESOS1-C1. This cell line will be a useful resource for basic research and preclinical studies.