Differential protein expression in MCF7 breast cancer cells transfected with ErbB2, neomycin resistance and luciferase plus yellow fluorescent protein

摘要

Gene transfection is frequently used to explore the molecular and phenotypic consequences of introduced genes. Breast cancer cell lines transfected with genes for growth factor receptors, intracellular signaling molecules or genes that generate luminescent signals are widely used in basic science and preclinical studies. Typically, a target gene of interest is co-transfected with selectable markers that are generally assumed to be innocuous. Perturbations of the cellular genome by transfected sequences may induce subtle and/or unexpected modulations in protein expression, only some of which may be attributable to the target gene of interest. In this study, we show that neomycin resistant MCF7 cells (MCF7 Neo') proliferate twice as rapidly in nude mice as do the untransfected parent cells, but show similar growth rates in vitro. MCF7 transfected with the ErbB2 gene shows minimal alteration in growth rate in vitro, and approximately a threefold increased growth rate in vivo. MCF7 cells that express luciferase and yellow fluorescent protein proliferate slowly in vitro and show essentially no growth in vivo suggesting that overexpression of these tracking proteins adversely affects cellular proliferative capacity. The molecular basis for alterations in proliferative capacity of the transfected sub-lines is poorly understood. We performed two-dimensional gel electrophoresis (2-DE) to compare relative protein expression among the cell lines. Relative to the parental MCF7, transfected cell lines displayed numerous differentially expressed proteins (69 to 149), relative to parental MCF7. Twenty-one of these differentially expressed proteins were identified by mass spectrometry, and included metabolic, structural, and signaling proteins. Possible roles of differentially expressed proteins in altering cellular proliferation are discussed.