ABSTRACT: Gene expression data from AML cell lines, MOLM-14, U937, THP-1 and HL-60, that were infected with a scrambled control hairpin (shControl), two shRNAs directed against GSK-3B (shGSK3B_1 and shGSK3B_2), or two shRNAs directed against GSK-3A (shGSK3A_5 and shGSK3A_6). Acute myeloid leukemia (AML) is the most common form of acute leukemia in adults. Long-term survival of patients with AML has changed little over the past decade, necessitating the identification and validation of new AML targets. Integration of genomic approaches with small-molecule and genetic-based high-throughput screening holds the promise of improved discovery of candidate targets for cancer therapy. Here, we identified a role for glycogen synthase kinase 3A (GSK-3A) in AML by performing two independent small-molecule library screens and an shRNA screen for perturbations that induced a differentiation expression signature in AML cells. GSK-3 is a serine-threonine kinase involved in diverse cellular processes including differentiation, signal transduction, cell cycle regulation, and proliferation. We demonstrated that specific loss of GSK-3A induced differentiation in AML by multiple measurements, including induction of gene expression signatures, morphological changes, and cell surface markers consistent with myeloid maturation. GSK-3AM-bM-^@M-^Sspecific suppression also led to impaired growth and proliferation in vitro, induction of apoptosis, loss of colony formation in methylcellulose, and anti-AML activity in vivo. Although the role of GSK-3B has been well studied in cancer development, these studies support a role for GSK-3A in AML. The AML cell lines, MOLM-14, U937, THP-1 and HL-60, were infected with a scrambled control hairpin (shControl), two shRNAs directed against GSK-3B (shGSK3B_1 and shGSK3B_2), and two shRNAs directed against GSK-3A (shGSK3A_5 and shGSK3A_6).
