Extracellular matrix induces doxorubicin-resistance in human osteosarcoma cells by suppression of p53 function

Osteosarcoma is the most common primary malignant bone tumor in childhood and adolescence. The several chemotherapy-resistant cases of osteosarcoma are at a higher risk of relapse and adverse outcome.

The aim of the current study was to determine the role of extracellular matrix in the resistance developed against chemotherapeutic treatments of human osteosarcoma cells.

A cell line, named OSCORT was established from the biopsy of a 17-year-old male patient with primary osteosarcoma. Cell proliferation, apoptosis and quantification of DNA damage after treatments with doxorubicin were investigated in classical and three-dimensional cell culture systems using an extracellular matrix gel. The experimental results were related to the clinical observations of the case.

The cells cultured in extracellular matrix gel have shown resistance to doxorubicin similar to that seen in the clinical case, as demonstrated by their proliferation, apoptosis and doxorubicin-induced DNA damage characteristics. Among the extracellular matrix components, the heparan sulfate proteoglycan and-to a lesser extent-fibronectin were involved in the doxorubicin resistance. Laminin and nidogen did not decrease the cytoreductive effect of doxorubicin, while collagen IV even increased it. The extracellular matrix gel decreased the protein levels of p53 and abrogated its cell nuclear translocalization. The most frequent known mutations in the p53 gene were not found in OSCORT cells.

The current study provides experimental evidence for an epigenetical, extracellular matrix-induced loss of p53 function, which lead to a potent chemotherapy resistance showing accordance with the clinical experience.