PHOSPHOROTHIOATE OLIGONUCLEOTIDES CAUSE DEGRADATION OF SECRETORY BUT NOT INTRACELLULAR SERGLYCIN PROTEOGLYCAN CORE PROTEIN IN A SEQUENCE-INDEPENDENT MANNER IN HUMAN MEGAKARYOCYTIC TUMOR-CELLS

Human megakaryocytic tumor cell lines CHRF-288-11 and HEL (human eryth roleukemia) were incubated with antisense phosphodiester (PDE) and pho sphorothioate (PS) oligodeoxynucleotides directed against the first si x codons of the human serglycin proteoglycan gene. As controls, PDE sc rambled and PS sense and scrambled sequences and a probe antisense to a 3' portion of the coding sequence were used, Treatment with PDE-ODNs did not alter the core protein content of cell or culture medium prot eoglycans. Treatment with all the PS-ODNs resulted in loss of the 31 k D serglycin core protein in the medium, but not the cell-associated pr oteoglycans, and concomitant appearance of a heavily labeled core prot ein band at the dye front, This band appears to arise from truncation of the core protein, which leaves the glycosaminoglycan attachment reg ion intact. The higher molecular weight core proteins, which appear to be derived from a betaglycan-like proteoglycan, were not affected by the PDE or PS-ODN treatment, The same effect was seen with or without electroporation, which was used to enhance uptake of the ODNs, Thus tr eatment of megakaryocytic tumor cells with PS-ODNs appeared to cause a selective degradation of the serglycin core protein in a sequence-ind ependent manner, Degradation most likely occurred intracellularly, bec ause culture supernatants did not degrade exogenously added serglycin proteoglycan, and the presence of superoxide dismutase and catalase in the culture medium during exposure of the cells to the PS-ODNs did no t prevent the degradation.