Cell-type specific and ligand specific enhancement of cellular uptake of oligodeoxynucleoside methylphosphonates covalently linked with a neoglycopeptide, YEE(ah-GalNAc)3.

A novel, structurally defined, and homogeneous oligodeoxynucleoside methylphosphonate (oligo-MP) neoglycopeptide conjugate, [YEE(ah-GalNAc)3]-SMCC-AET-pUmpT7, has been synthesized. The linkage between the carbohydrate ligand and the oligo-MP is a metabolically stable thioether. Experiments establish that uptake of this conjugate by human hepatocellular carcinoma (Hep G2) is cell-type specific when compared with its uptake by human fibrosarcoma (HT 1080) and human promyleocytic leukemia (HL-60). Uptake of the conjugate with Hep G2 cells can be totally inhibited by the addition of a 100-fold excess of free YEE(ah-GalNAc)3 in the culture medium indicating the observed cell uptake is ligand specific. The conjugate is rapidly taken in by Hep G2 cells in a linear fashion reaching a saturation plateau of 26 pmol per 10(6) cells after 24 h. Conjugation of oligo-MPs to ligands for hepatic carbohydrate receptors, such as YEE(ah-GalNAc)3, represents an efficient and ligand-specific method for the intracellular delivery of oligo-MPs.