Comparative Proteomic Profiling of Human Breast Cell Lines

Abstract

Although epidemiological studies have suggested that the isoflavone genistein found in soy may be protective against breast cancer, its effects on molecular processes involved in cell proliferation have not been clearly elucidated. Using comparative shotgun proteomics, we examined the proteome of non‐cancerous breast MCF10A cells, estrogen receptor‐positive breast cancer T47D cells, and Hras transfected MCF10A cells after treatment with 3, 10, and 30 μM genistein for 18 h. While genistein induced G1‐phase arrest in MCF10A‐Hras and G2/M‐phase arrest in T47D cells, it did not alter the cell cycle distribution in MCF10A cells. The arrest in G1‐phase of MCF10A‐Hras cells coincided with downregulation of the proliferation marker Ki67, epidermal growth factor receptor, various components of the mitogen‐activated protein kinase family of enzymes and low molecular weight phosphotyrosine protein phosphatase (ACP1), The arrest in G2/M‐phase of T47D cells was accompanied by upregulation of caspase‐8 and mSH2, suggesting that genistein may induce a G2/M checkpoint/proapoptotic response involving the mismatch repair system. Taken together, these findings suggest a differential response to genistein in cancerous cells and non‐malignant epithelial cells, and demonstrate the utility of comparative shotgun proteomics for investigating the cancer preventative effects of bioactive components.