Proteomic detection of changes in protein synthesis induced by fibroblast growth factor-2 in MCF-7 human breast cancer cells

Fibroblast growth factor-2 (FGF-2) is a potent regulator of breast cancer c ell growth through stimulation of tyrosine kinase receptors and activation of the mitogen-activated protein kinase cascade. In the present study, we h ave investigated changes in protein synthesis induced by FGF-2 stimulation of the prototypic human breast cancer cell line MCF-7. Using high-resolutio n two-dimensional electrophoresis of S-35 amino acid metabolically labeled proteins and computerized analysis of 2D autoradiograms, we found that four proteins were up-regulated within the first 12 h of FGF-S stimulation. Mas s spectrometry analysis (MALDI-TOF and MS-MS) of tryptic fragments and data base searches allowed the identification of these FGF-a-regulated proteins as the heat shock proteins HSP90 and HSP70, the proliferating cell nuclear antigen (PCNA), and the transcriptionaly controlled tumor protein (TCTP). W e then analyzed the distribution of these proteins in various cancerous and normal breast epithelial cells. Interestingly, the four FGF-a-regulated pr oteins were found to be constitutively up-regulated in ras-transfected MCF- 7 cells, indicating their relevance to the up-regulation of cellular prolif eration. Moreover, HSP90 and PCNA were found at higher levels in cancerous cells than in normal cells, The role of HSP90 was further investigated usin g the specific inhibitor geldanamycin. We showed that the functionality of HSP90 is strictly required in order to obtain FGF-S mitogenic stimulation i n MCF-7 cells, indicating the crucial role played by this molecular chapero ne in the control of breast cancer cell growth, Finally, these results show that proteomic analysis is a valuable method for identifying potential mar kers or therapeutic targets related to cancer growth, (C) 2001 Academic Pre ss.