C/EBPα induces highly efficient macrophage transdifferentiation of B lymphoma and leukemia cell lines and impairs their tumorigenicity.

Earlier work demonstrated that the transcription factor C/EBPα can convert immature and mature murine B lineage cells into functional macrophages. Testing >20 human lymphoma and leukemia B cell lines, we found that most can be transdifferentiated at least partially into macrophage-like cells, provided that C/EBPα is expressed at sufficiently high levels. A tamoxifen-inducible subclone of the Seraphina Burkitt lymphoma line, expressing C/EBPαER, could be efficiently converted into phagocytic and quiescent cells with a transcriptome resembling normal macrophages. The converted cells retained their phenotype even when C/EBPα was inactivated, a hallmark of cell reprogramming. Interestingly, C/EBPα induction also impaired the cells' tumorigenicity. Likewise, C/EBPα efficiently converted a lymphoblastic leukemia B cell line into macrophage-like cells, again dramatically impairing their tumorigenicity. Our experiments show that human cancer cells can be induced by C/EBPα to transdifferentiate into seemingly normal cells at high frequencies and provide a proof of principle for a potential new therapeutic strategy for treating B cell malignancies.