(P 117) THERAPEUTIC POTENTIAL OF DOXORUBICIN AND DASATINIB COMBINATION IN OSTEOSARCOMA

Objective: Osteosarcoma is a rare, aggressive malignancy and the most common primary bone sarcoma affecting children, adolescents, and young adults. Despite advancements in treatment, survival rates have stagnated, underscoring the need for new therapeutic strategies. Although doxorubicin remains a cornerstone in osteosarcoma treatment, resistance often develops. Enhancing doxorubicin effectiveness against osteosarcoma cells through combination therapy may improve treatment efficacy. This study aimed to identify agents that synergize with doxorubicin in osteosarcoma.

Methods: A kinase inhibitor library was screened using MTT assays in KHOS and 143B osteosarcoma cell lines. Drug interactions were evaluated using the ZIP synergy model, where ZIP < 0 indicates antagonism, 0 ≤ ZIP ≤ 10 is additive, and ZIP > 10 indicates synergy. Src and phosphorylated Src (p-Src) expression and subcellular localization were assessed using Western blotting and immunofluorescence, respectively. Expression of anti-apoptotic proteins and PARP cleavage were also evaluated by Western blot. The functional role of p-Src inhibition in enhancing doxorubicin effectiveness was further evaluated using flow cytometric apoptosis and clonogenic assays.

Results: MTT assays demonstrated that dasatinib exhibited the highest synergy with doxorubicin in both KHOS and 143B cells, with synergy scores of 10.575 and 13.968, respectively (p < 0.05). Immunofluorescence analysis showed that p-Src was predominantly localized in the cytoplasm. Western blot showed that the combination treatment significantly reduced p-Src and anti-apoptotic protein levels, while enhancing PARP cleavage compared to either agent alone. Flow cytometry analysis revealed increased apoptosis in the combination group, while clonogenic assays showed decreased colony-forming ability. These findings indicate dasatinib enhances doxorubicin effectiveness in osteosarcoma cells.

Conclusion: The combination of doxorubicin and dasatinib demonstrates synergistic anti-tumor effects in osteosarcoma. By reducing cell proliferation, downregulating p-Src and anti-apoptotic proteins, and enhancing apoptosis, this combination therapy offers a new and inspiring direction for osteosarcoma treatment. The data strongly support the potential of dasatinib to enhance doxorubicin effectiveness, making it a promising strategy for overcoming drug resistance in osteosarcoma. This inspiring finding motivates further exploration and clinical trials of this combination therapy.