The proto-oncogene serine/threonine-protein kinases, Pim-1 and Pim-2, are enzymes involved in cytokine signaling and participate in various signal transduction pathways, including cell growth, differentiation, and apoptosis. Their overexpression has been implicated in prostate cancer, some forms of leukemia, and lymphoma. Quercetagetin is a flavonol that inhibits Pim-1 with an IC50 value of 0.34 μM. It is selective for Pim-1, inhibiting Pim-2, PKA, RSK2, and JNK with IC50 values of 3.45, 21.2, 2.82, and 4.6 μM, respectively. Quercetagetin has been shown to inhibit Pim-1 activity in intact RWPE2 prostate cancer cells with an ED50 value of 5.5 μM, which led to significant growth inhibition. It can also inhibit the growth of additional prostate epithelial cell lines at a potency proportionate to their respective level of Pim-1 protein.
