INVASIVE PHENOTYPE OF MCF10A CELLS OVEREXPRESSING C-HA-RAS AND C-ERBB-2 ONCOGENES

Infection with erbB-2 (E) of Ha-ras (H) oncogene-transfected cells has been previously shown to cooperatively induce anchor-age-independent growth of the MCF10A human mammary epithelial cell line in vitro, but not to induce nude mouse tumorigenicity. Here we show that oncogene-tr ansformed MCF10A are able to halt in the lungs of nude mice, a sign of organ colonization potential. We have therefore studied the transform ants for in vitro migratory and invasive properties known to correlate with the metastatic potential of human mammary carcinoma cells in nud e mice. MCF10A transfected with Ha-ras, infected with a recombinant re troviral vector containing the human c-erbB-2 proto oncogene (MCF10A-H E cells), show a higher invasive index than either the single transfec tant (MCF10A-H) or MCF10A-erbB-2 (MCF10A-E) cells in the Boyden chambe r chemotaxis and chemoinvasion assays. The MCF10A-HE cells also adopte d an invasive stellate growth pattern when plated or embedded in Matri gel, in contrast to the spherical colonies formed by the single transf ormants MCF10A-H, MCF10A-E, and the parental cells. Dot-blot analysis of gelatinase A and TIMP-2 mRNA levels revealed increasing gelatinase A mRNA levels (HE > E > H > MCF10A) and reduced TIMP-2 expression in b oth single and double transformants. Furthermore, MCF10A-HE cells show more MMP-2 activity than parental MCF10A cells or the single transfor mants. CD44 analysis revealed differential isoform banding for the MCF 10A-HE cells compared to parental cells, MCF10A-H and MCF10A-E, accomp anied by increased binding of hyaluronan by the double transformants. Our results indicate that erbB-2 and Ha-res co-expression can induce a more aggressive phenotype in vitro, representative of the malignancy of mammary carcinomas. (C) 1995 Wiley-Liss, Inc.