Abstract B022: cDNA microarray analysis of genes associated with reduced annexin A6 expression in invasive breast cancer cells

Abstract

Abstract Recent studies have shown that the calcium-dependent membrane binding protein, annexin A6 (AnxA6) is involved in cell proliferation, membrane dynamics, calcium fluxes across the plasma membranes and cell-cell and cell extracellular matrix interactions and cell motility. Together with our recent observation that AnxA6 is down regulated in breast cancer, this suggests that AnxA6 may influence the expression of a very diverse set of genes. We therefore, investigated changes in gene expression profiles associated with AnxA6 depletion in invasive breast cancer cells. To do this we generated AnxA6 depleted BT-549 cells with varying extents of AnxA6 down regulation. Two of the cell lines designated BT-A6sh2 and BT-A6sh5 as well as pGIPZ transfected control cells were used in the cDNA microarray analysis. Analysis of the microarrays revealed that a total of 558 genes were significantly down-regulated of which 38 were down regulated by at least 2.0-fold and p < 0.05. Meanwhile, 625 genes were significantly up-regulated and 33 were up regulated by at least 2.0-fold and p < 0.05. Interestingly, the greater the extent of AnxA6 depletion the greater the number of genes that were up or down regulated. Among the up regulated genes were RASGRF2, CDH2, JAG1, PCDH10 and PCDH7. Among the down regulated genes were FNDC1, CD24 SLC4A4, CALB2, CSPG4 and ST8SIA6. Interestingly, LGALS3 and CDH3 were among several other genes that were up regulated while EGFR, a predictive marker of basal-like breast cancer, was among the genes that were down regulated following >80% depletion of AnxA6. Validation of some of these genes by quantitative RT-PCR suggests that AnxA6 influences Ras signaling, cadherin-mediated cell-cell interactions, solute transport, cell-extracellular matrix interactions, calcium signaling and more interestingly, cancer stem cell phenotypes. Down-regulation of CD24 and up-regulation of N- and P-cadherin suggest that reduced AnxA6 expression as previously shown in breast cancer tissues also facilitates the transformation of tumor cells into CD24-low mesenchymal stem cell-like phenotypes. These data suggest that reduced AnxA6 expression in invasive breast cancer is accompanied by modulation of a wide range of genes that influence several aspects of breast cancer progression, some of which are potentially useful targets for prognosis and therapeutic intervention. Citation Format: Amos M. Sakwe. cDNA microarray analysis of genes associated with reduced annexin A6 expression in invasive breast cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr B022.