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Cytotoxic Efficacy of Photodynamic Therapy in Osteosarcoma Cells In Vitro
Published on: March 18, 2014
Inhibiting DNA-PKCS radiosensitizes human osteosarcoma cells
Tewodros Mamo1, Ann C Mladek2, Kris L Shogren3
1Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55902, USA.
Abstract:
Osteosarcoma survival rate has not improved over the past three decades, and the debilitating side effects of the surgical treatment suggest the need for alternative local control approaches. Radiotherapy is largely ineffective in osteosarcoma, indicating a potential role for radiosensitizers. Blocking DNA repair, particularly by inhibiting the catalytic subunit of DNA-dependent protein kinase (DNA-PKCS), is an attractive option for the radiosensitization of osteosarcoma. In this study, the expression of DNA-PKCS in osteosarcoma tissue specimens and cell lines was examined. Moreover, the small molecule DNA-PKCS inhibitor, KU60648, was investigated as a radiosensitizing strategy for osteosarcoma cells in vitro. DNA-PKCS was consistently expressed in the osteosarcoma tissue specimens and cell lines studied. Additionally, KU60648 effectively sensitized two of those osteosarcoma cell lines (143B cells by 1.5-fold and U2OS cells by 2.5-fold). KU60648 co-treatment also altered cell cycle distribution and enhanced DNA damage. Cell accumulation at the G2/M transition point increased by 55% and 45%, while the percentage of cells with >20 γH2AX foci were enhanced by 59% and 107% for 143B and U2OS cells, respectively. These results indicate that the DNA-PKCS inhibitor, KU60648, is a promising radiosensitizing agent for osteosarcoma.
Insights
The DNA-dependent protein kinase catalytic subunit (DNA-PKCS) inhibitor KU60648 shows promise for radiosensitizing osteosarcoma. This study found that blocking DNA repair with KU60648 enhances radiotherapy effectiveness in osteosarcoma cells.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Osteosarcoma survival rates have stagnated, and current treatments cause significant side effects, necessitating novel therapeutic strategies.
- Radiotherapy is generally ineffective against osteosarcoma, suggesting a need for radiosensitizing agents.
- Inhibiting DNA repair mechanisms, specifically DNA-dependent protein kinase catalytic subunit (DNA-PKCS), is a potential approach for enhancing radiosensitivity.
Purpose of the Study:
- To investigate the expression of DNA-PKCS in osteosarcoma.
- To evaluate the efficacy of the DNA-PKCS inhibitor KU60648 as a radiosensitizing agent for osteosarcoma cells in vitro.
- To assess the impact of KU60648 on cell cycle distribution and DNA damage in osteosarcoma cells.
Main Methods:
- Analysis of DNA-PKCS expression in osteosarcoma tissue specimens and cell lines.
- In vitro treatment of osteosarcoma cell lines (143B and U2OS) with KU60648 and radiation.
- Assessment of cell viability, cell cycle distribution (G2/M phase), and DNA damage marker (γH2AX foci) following treatment.
Main Results:
- DNA-PKCS was consistently expressed in osteosarcoma tissues and cell lines.
- KU60648 significantly sensitized 143B cells (1.5-fold) and U2OS cells (2.5-fold) to radiation.
- Co-treatment with KU60648 led to increased G2/M phase cell accumulation (55% and 45%) and enhanced DNA damage (59% and 107% increase in γH2AX foci).
Conclusions:
- The small molecule DNA-PKCS inhibitor KU60648 demonstrates potential as a radiosensitizing agent for osteosarcoma.
- Targeting DNA repair pathways via DNA-PKCS inhibition offers a promising strategy to improve osteosarcoma treatment outcomes.
- Further investigation into KU60648 as a radiosensitizer for osteosarcoma is warranted.
