Tumor Suppression Efficacy of Heat Shock Protein 90 Inhibitor 17AAG in a Liposarcoma Mouse Model.

BACKGROUND/AIM: Heat shock protein 90 (HSP90) inhibitors have recently been tested as anticancer drugs in a variety of carcinomas. Yet, there exist only few reports about HSP90 inhibitor and its thepeutic effect on liposarcoma. The therapeutic effects of HSP90 inhibitors have been mainly observed in oncogenic and tumor angiogenic signaling cascades by observing tumor growth.

MATERIALS AND METHODS

We used the the LPS 246 liposarcoma cell line and GS-076 PDC (patient-derived cell lines). On these, we performed cell viability assays and migration assays under treatment with the HSP90 inhibitor, 17AAG. For analyzing angiogenesis factor, we used quantitative polymerase chain reaction (qPCR) after treating cells with the 17AAG inhibitor. Regarding in vivo assay, we made the tumor model in immune-deficient mouse and compared the tumor size of drug-treated group at each time point with controls. For sequestering analysis of angiogenesis factor in vivo, we performed immuno-fluorescence (IF) staining on tumor tissue.

RESULTS

Through cell viability, migration assay and qPCR about angiogenesis factor, we demonstrated the anti-oncogenic and anti-angiogenic effects of an HSP90 inhibitor on a liposarcoma cell line and a patient-derived primary cell model (PDC). Also, the HSP90 inhibitor 17AAG effectively inhibited the activity of protein kinase B (AKT) and blocked extracellular signal-regulated kinase (ERK) activity. Hence, 17AAG effectively disrupted the oncogenic signaling cascade and substantially inhibited tumor growth in vitro. In an LPS 863 cell xenograft mouse model treated with 17AAG, we observed that tumor size was decreasing, as well as down-regulation of the expression levels of vascular endothelial growth factor receptor 2 (VEGFR2), CD31 and signal transducer and activator of transcription-3 (STAT3).

CONCLUSION

17AAG reduced the activity of AKT, ERK, VEGF and STAT3 in oncogenic and angiogenic pathways in liposarcoma PDC models derived from patients' tissues and cancer cell lines.