c-Myc and E2F1 drive PBK/TOPK expression in high-grade malignant lymphomas.

c-Myc has been implicated in a variety of hematologic malignancies including Burkitt's lymphoma. Targeting c-Myc driven growth pathways could be therapeutically useful but might require the identification of critical downstream proteins. Here we show that the serine-threonine kinase PBK/TOPK is frequently overexpressed in high-grade lymphomas and its expression is positively correlated to that of c-Myc and E2F1. Further we demonstrate that c-Myc regulates PBK expression through E2F1. Additionally, inhibition of c-Myc, E2F1 or PBK comparably decreased cell growth and survival. In conclusion, a c-Myc-E2F1-PBK signaling pathway operates in high-grade lymphomas and may provide a useful target for novel antineoplastic therapeutics.