AIMS: Recently, we were able to show that the expression of early placenta insulin like growth factor (EPIL) is expressed by highly motile HER-2-positive breast cancer cells in vitro (Brandt et al., Cancer Res. 2002) in Paget cells in vivo and indicates a poor clinical prognosis, irrespectively of other prognostic factors. METHODS: In order to demonstrate the interplay between HER-2 and Epil we established a cellular model for high simultaneous Epil and HER-2 expression. The HER-2-positive breast cancer cell line SKBR3 was modified with an EPIL expression vector. In addition, an assay for the knockdown of EPIL-expression via siRNA was established. Erk1/2 expression was measured via Western Blot. The phenotype of the viable cells was determined by laser scan microscopy. RESULTS: Epil overexpression in SKBR3 cells resulted in fast and frequent protrusion formation of the cells shown by laser scan microscopy. The cells were further characterized by a significantly increased invasiveness, which could be reversed by Epil specific siRNA treatment. Increased invasiveness and morphological changes were associated with a decreased erk1/2 phosphorylation. CONCLUSIONS: These data further supports the assumption that EPIL might provide an autocrine loop in HER-2-positive breast cancer cells that enforce metastasis, conceivably escape from adjuvant therapy and in consequence poor clinical outcome. A tight interaction between HER-2 and EPIL in invasive breast cancer cells is therefore likely. The exact mechanims remain to be elucidated.
AIMS: Recently, we were able to show that the expression of early placenta insulin like growth factor (EPIL) is expressed by highly motile HER-2-positive breast cancer cells in vitro (Brandt et al., Cancer Res. 2002) in Paget cells in vivo and indicates a poor clinical prognosis, irrespectively of other prognostic factors. METHODS: In order to demonstrate the interplay between HER-2 and Epil we established a cellular model for high simultaneous Epil and HER-2 expression. The HER-2-positive breast cancer cell line SKBR3 was modified with an EPIL expression vector. In addition, an assay for the knockdown of EPIL-expression via siRNA was established. Erk1/2 expression was measured via Western Blot. The phenotype of the viable cells was determined by laser scan microscopy. RESULTS:Epil overexpression in SKBR3 cells resulted in fast and frequent protrusion formation of the cells shown by laser scan microscopy. The cells were further characterized by a significantly increased invasiveness, which could be reversed by Epil specific siRNA treatment. Increased invasiveness and morphological changes were associated with a decreased erk1/2 phosphorylation. CONCLUSIONS: These data further supports the assumption that EPIL might provide an autocrine loop in HER-2-positive breast cancer cells that enforce metastasis, conceivably escape from adjuvant therapy and in consequence poor clinical outcome. A tight interaction between HER-2 and EPIL in invasive breast cancer cells is therefore likely. The exact mechanims remain to be elucidated.