Heparan Sulfate and Chondroitin Sulfate Glycosaminoglycans Are Targeted by Bleomycin in Cancer Cells

Abstract

Background/Aims: Bleomycin is a clinically used anti-cancer drug that produces DNA breaks once inside of cells. However, bleomycin is a positively charged molecule and cannot get inside of cells by free diffusion. We previously reported that the cell surface negatively charged glycosaminoglycans (GAGs) may be involved in the cellular uptake of bleomycin. We also observed that a class of positively charged small molecules has Golgi localization once inside of the cells. We therefore hypothesized that bleomycin might perturb Golgi-operated GAG biosynthesis. Methods: We used stable isotope labeling coupled with LC/MS analysis of GAG disaccharides simultaneously from bleomycin-treated and non-treated cancer cells. To further understand the cytotoxicity of bleomycin and its relationship to GAGs, we used sodium chlorate to inhibit GAG sulfation and commercially available GAGs to compete for cell surface GAG/bleomycin interactions in seven cell lines including CHO745 defective in both heparan sulfate and chondroitin sulfate biosynthesis. Results: we discovered that heparan sulfate GAG was significantly undersulfated and the quantity and disaccharide compositions of GAGs were changed in bleomycin-treated cells in a concentration- and time-dependent manner. We revealed that bleomycin-induced cytotoxicity was directly related to cell surface GAGs. Conclusion: GAGs were targeted by bleomycin both at cell surface and at Golgi. Thus, GAGs might be the biological relevant molecules that might be related to the bleomycin-induced fibrosis in certain cancer patients, a severe side effect with largely unknown molecular mechanism.

Genistein Enhances or Reduces Glycosaminoglycan Quantity in a Cell Type-Specific Manner

“…For cell growth inhibition assay was performed as described previously [31]. In brief, HCT116, CHOK1, CHO3.…”

Pingyangmycin inhibits glycosaminoglycan sulphation in both cancer cells and tumour tissues

“…Pingyangmycin was discovered in 1969 at Pingyang County of Zhejiang Province of China and subsequently approved for clinical use in 1978 by the Chinese FDA . The anticancer activities of BLMA5 are believed to rely on its abilities to produce single‐ and double‐stranded DNA breaks thus preventing DNA from replications . BLMA5 has largely superseded BLM as an anticancer drug in China since it is a single compound and cheaper to obtain.…”

“…More importantly, BLMA5 is as potent, if not superior, in cancer treatment compared to BLM . However, both BLM and BLMA5 induce lung inflammation that leads to fibrosis and rapid death in certain cancer patients with unknown molecular mechanism …”

“…HS and CS GAGs are synthesized by all animal cells. Because their repeating disaccharides can have diverse sulphation and different repeating disaccharide GlcN‐GlcA/IdoA or GalN‐GlcA/IdoA patterns due to differential expressions of GAG biosynthetic enzymes in different animal cells, the quantity and HS or CS disaccharide compositions are varying not only from cell to cell but also from tissues to tissues . The biological functions of proteoglycans are largely dependent on their GAG chains .…”

“…Therefore, we hypothesized that positively charged BLMA5 may interact with the negatively charged GAGs of proteoglycans on the cell surface for their cellular uptake. Indeed, by treating six different cell lines including a unique Chinese hamster ovary cell mutant defective in cell surface GAG biosynthesis (CHO745) with BLM A2, B2, A5 or combination of any two of them, the cytotoxicity data suggested that GAGs might be involved in the cellular uptake of all BLMs . Since BLM has no optical properties, we have synthesized a series of small molecules with intrinsic fluorescence with or without positive charge, that is isothiouronium‐ or bromo‐modified curcumin‐pyrimidine analogs .…”