Fusion of breast cancer MCF-7 cells with mesenchymal stem cells rearranges interallelic gene expression and enhances cancer malignancy

Fusion among normal cells is tightly regulated and required for the developmental processes of an organism. Cancer cell fusion appears relatively rare but is associated with generating new hybrid cancer cells with aggressive properties. However, it remains unclear how cancer cells acquire aggressiveness via cell fusion. Here, we report changes in cell proliferative capacity, cell motility, anticancer drug resistance, and gene expression profiles when fusing human MCF-7 breast cancer cells and mesenchymal stem cells (MSCs). The fused cells were established using envelopes of a hemagglutinating virus of Japan, which increased cell proliferation, motility, and drug resistance. Comprehensive gene expression profile analysis revealed that the fused cells expressed higher levels of glycolysis-related genes than their parental cells. In fact, the fused cells relied more on glycolysis for ATP production (Warburg effect). HIF1A, which induces the expression of glycolysis-related genes, was upregulated in fused cells compared to MCF-7 cells. Allele-specific expression analysis of the fused cells indicated that MSC allele-derived HIF1A efficiently induces the expression of glycolysis-related genes in the MCF-7 allele. These findings indicate that the reorganization of gene expression by combining MSCs and MCF-7 alleles resulted in the predominant expression of glycolysis-related genes and increased malignancy in the fused cells.