Human megakaryocytic tumor cell lines CHRF-288-11 and HEL (human
erythroleukemia) were incubated with antisense phosphodiester (PDE) and phosphorothioate (PS)
oligodeoxynucleotides directed against the first six
codons of the human
serglycin proteoglycan gene. As controls, PDE scrambled 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
proteoglycans. Treatment with all the PS-ODNs resulted in loss of the 31 kD
serglycin core
protein in the medium, but not the cell-associated
proteoglycans, and concomitant appearance of a heavily labeled core
protein band at the
dye front. This band appears to arise from truncation of the core
protein, which leaves the
glycosaminoglycan attachment region 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 treatment of megakaryocytic
tumor cells with PS-ODNs appeared to cause a selective degradation of the
serglycin core
protein in a sequence-independent manner. Degradation most likely occurred intracellularly, because 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 not prevent the degradation.