EGF-related peptides are involved in the proliferation and survival of MDA-MB-468 human breast carcinoma cells

A majority of human breast carcinomas co-express the epidermal growth factor (EGF)-like peptides CRIPTO (CR), amphiregulin (AR) and transforming growth factor α (TGF-α). MDA-MB-468 breast carcinoma cells express CR, AR and TGFα, while SK-BR-3 cells express CR and TGF-α. Anti-sense phosphorothioate oligodeoxynucleotides (AS S-oligos) directed against either CR or TGF-α inhibit the proliferation of both cell lines. A 40-50% growth inhibition was observed at a 2-μM concentration of each AS S-oligo. Treatment with the AR AS S-oligo also resulted in a significant inhibition of MDA-MB-468 anchorage dependent growth (ADG). No significant growth inhibition was observed when MDA-MB-468 or SK-BR-3 cells were treated with a mis-sense S-oligo. The AS S-oligos inhibited the expression of AR, CR or TGF-α proteins and mRNAs, as assessed by immuno-cytochemistry and semi-quantitative RT-PCR. An additive growth-inhibitory effect was observed when MDA-MB-468 cells were treated with a combination of EGF-related AS S-oligos. Indeed, treatment of MDA-MB-468 cells with a combination of AR, CR and TGF-α AS S- oligos resulted in about 70% growth inhibition at a concentration of 0.7 μM each. Finally, treatment of MDA-MB-468 cells with a combination either of the 3 AS S-oligos or of an EGF receptor-blocking antibody (MAb 225) and either CR, AR or TGFα AS S-oligos resulted in a significant increase in DNA fragmentation. Our data suggest that the EGF-related peptides are involved in the proliferation and survival of breast carcinoma cells.