ASPB10 insulin induction of increased mitogenic responses and phenotypic changes in human breast epithelial cells: Evidence for enhanced interactions with the insulin-like growth factor-I receptor
✍ Scribed by Giovanni Milazzo; Laura Sciacca; Vincenzo Papa; Ira D. Goldfine; Riccardo Vigneri
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 128 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0899-1987
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✦ Synopsis
The human insulin analogue ASPB 10 has been reported to have increased affinity for the insulin receptor and to cause breast cancer in female rats. In the study reported here, we investigated whether ASPB 10 has an increased mitogenic potency and induces a transformed phenotype in cultured human breast cells. In both MCF-10 cells (a non-malignant human breast line) and MCF-7 cells (a human breast cancer cell line), ASPB 10 was approximately twofold more potent than insulin in competing for 125 I-insulin binding but sevenfold to tenfold more potent than insulin in competing for 125 I-insulin-like growth factor (IGF)-I binding. In addition, ASPB 10 was twofold more potent than insulin in stimulating insulin receptor autophosphorylation but significantly more potent in stimulating IGF-I receptor autophosphorylation in both cell lines. Moreover, ASPB 10 was approximately sevenfold more potent than insulin in stimulating the growth of MCF-10 and MCF-7 cells. This increased mitogenic effect of ASPB 10 was significantly inhibited (but not abolished) when cells were cultured in the presence of α-IR3, a monoclonal antibody to the IGF-I receptor. ASPB 10 , but not insulin, caused phenotypic changes (focus formation) in MCF-10 cells. Neither agent caused colony formation in soft agar in MCF-10 cells, but ASPB 10 was more potent than insulin in stimulating colony formation in MCF-7 cells. These observations indicate that in human breast cells, ASPB 10 has enhanced mitogenic effects and induces phenotypic changes as a consequence of its activation of both insulin and IGF-I receptors. Mol.