Research Papers:

ABSTRACT

Pingyangmycin is a clinically used anticancer drug and induces lung fibrosis in certain cancer patients. Glycosaminoglycans, the key components of fibrotic tissues, are synthesized by all animal cells. We previously reported that the cell surface glycosaminoglycans may be involved in the cellular uptake of the positively charged pingyangmycin. We also observed that positively charged small molecules with intrinsic fluorescence have Golgi localization once inside of the cells. We therefore hypothesized that pingyangmycin might perturb Golgi-operated glycosaminoglycan biosynthesis. Indeed, the non-sulfated disaccharides were strongly increased and mono- and di-sulfated disaccharides of heparan sulfate were sharply decreased following pingyangmycin treatment in cultured HCT116 and A549 cells detected by stable isotope labeling coupled with LC/MS analysis. The effect of pingyangmycin was similar at high and lower concentrations and at different exposure times, suggesting a strong causal effect of pingyangmycin. Moreover, the cytotoxicity of pingyangmycin was decreased in the presence of soluble GAGs, in the GAG-deficient cell line CHO745, and in the presence of chlorate that prevent the sulfation of glycosaminoglycans, indicating that glycosaminoglycans mediated pingyangmycin internalization and toxicity. A flow cytometry-based cell surface fibroblast growth factors/fibroblast growth factor receptor/glycosaminoglycan binding assay also showed that pingyangmycin changed cell surface glycosaminoglycan structures in cultured cancer cells. Furthermore, pingyangmycin reduced both chondroitin sulfate and heparan sulfate sulfation in lung tumors in a Lewis lung carcinoma-injected C57BL/6 mouse model. Thus, the glycosaminoglycans might be the biological relevant targets responsible for the anti-cancer as well as the unexplainable side effects of pingyangmycin in cancer patients.