Antitumor Activity of Polyuridylic Acid in Human Soft Tissue and Bone Sarcomas

Abstract

The immunomodulatory properties of polyuridylic acid (PolyU) make it a promising agent in cancer immunotherapy. However, there is limited information on its direct effects on tumor cells. TLR8 mRNA and protein expression in soft tissue sarcoma (STS) and bone sarcoma (BS) cell lines were determined by PCR and flow cytometry, respectively. Apoptosis and proliferation assays were performed using annexin V staining and BrdU incorporation assays, respectively. A relative cell enumeration was evaluated with WST-1 reagent. Expression levels of apoptotic proteins were evaluated by Western blotting. We demonstrate that PolyU treatment resulted in a significant decrease in STS and BS cell count by inducing apoptosis and inhibition of cell proliferation. All cell lines examined expressed TLR8 and the effect of PolyU was partially mediated through TLR8. Several apoptotic proteins including caspases were activated or increased in STS cells after treatment with PolyU. Administration PolyU resulted in significant growth inhibition of STS without any observable adverse effects in mouse xenograft tumor models. These results elucidate the effect of PolyU in STS and BS cells and demonstrate that PolyU may be a potential therapeutic agent for STS and BS.