biostudies-literatureVanCleave ANCI NIH HHSNIGMS NIH HHS2597-2610https://www.ebi.ac.uk/biostudies/studies/S-EPMC7343631biostudies-literatureUnknown11(27)Outcomes have not improved for metastatic osteosarcoma for several decades. In part, this failure to develop better therapies stems from a lack of understanding of osteosarcoma biology, given the rarity of the disease and the high genetic heterogeneity at the time of diagnosis. We report here the successful establishment of a new human osteosarcoma cell line, COS-33, from a patient-derived xenograft and demonstrate retention of the biological features of the original tumor. We found high mTOR signaling activity in the cultured cells, which were sensitive to a small molecule inhibitor, rapamycin, a suppressor of the mTOR pathway. Suppressed mTOR signaling after treatment with rapamycin was confirmed by decreased phosphorylation of the S6 ribosomal protein. Increasing concentrations of rapamOncotargetDevelopment and characterization of the novel human osteosarcoma cell line COS-33 with sustained activation of the mTOR pathway.PMC7343631P30 CA042014P20 GM103548P20 GM103620Ross ARao PTao JTorres HFang FZheng SLi QEvans CFuglsby KRodezno TLeiferman PPalmer MAfeworki YHoughton PVanCleave AfalseDevelopment and characterization of the novel human osteosarcoma cell line COS-33 with sustained activation of the mTOR pathway.Outcomes have not improved for metastatic osteosarcoma for several decades. In part, this failure to develop better therapies stems from a lack of understanding of osteosarcoma biology, given the rarity of the disease and the high genetic heterogeneity at the time of diagnosis. We report here the successful establishment of a new human osteosarcoma cell line, COS-33, from a patient-derived xenograft and demonstrate retention of the biological features of the original tumor. We found high mTOR signaling activity in the cultured cells, which were sensitive to a small molecule inhibitor, rapamycin, a suppressor of the mTOR pathway. Suppressed mTOR signaling after treatment with rapamycin was confirmed by decreased phosphorylation of the S6 ribosomal protein. Increasing concentrations of rapam2020-01-01T00:00:00Z2020 Jul2026-04-29T08:44:37.014Z2021-02-19T22:03:42ZS-EPMC73436313267616210.18632/oncotarget.27611