Growth control of mouse mammary epithelial cells by keratin antibody-targeted liposome containing oligonucleotides antisense to epidermal growth factor receptor.

Abstract

NMuMG cells were incubated with 17beta-estradiol (E)+progesterone (P)+epidermal growth factor (EGF), with or without various types of oligomers (21-mers) to the EGF receptor activity domain (amino acid residues 718 to 724). Sense or antisense oligomers were encapsulated in protein A-bearing liposomes. Uncoupled protein A and unencapsulated sense or antisense oligomers were separated from liposomes on a Sepharose 4B column (the encapsulation efficiency of oligomers in liposome-protein A was 0.8%). The addition of various concentrations of EGF to E+P showed an interaction between them during DNA synthesis (P<0.05). Antisense oligomers (1 microM) decreased DNA synthesis induced by E+P+EGF (65.0% inhibition, P<0.05). Sense oligomers also inhibited DNA synthesis induced by E+P+EGF (P<0.05). However, random-sequence oligomers did not inhibit EGF-induced DNA synthesis. We cannot rule out the possibility that sense oligomers match an unknown functional gene mRNA involved in cell growth, which causes their inhibitory effect. Cells were incubated with a keratin monoclonal antibody and then with dilutions of protein A-bound liposomes containing sense or antisense oligomers in the presence of E+P+EGF. Dose dependent inhibition of DNA synthesis was observed. The encapsulated oligomers in protein A-bound liposomes inhibited DNA synthesis at a 100-fold lower concentration than that of unencapsulated oligomers or the oligomer+liposome mixture. The tyrosine kinase activity domain has an important role in EGF regulation of mammary growth. The effect of a cytokeratin-targeted antibody on DNA synthesis in normal mouse mammary epithelial cells was marginal.