Figure 5: Prenylated isoflavonoids are cell permeable kinase inhibitors that act in part through CK2 inhibition.

(A) VIKING output of predicted kinases targeted by isopomiferin.

(B) Cell free CK2a1 kinase activity in presence of pomiferin, isopomiferin or CX-4945. Values represent mean ± S.D. of three technical replicates.

(C) Western blot analysis of PTEN phosphorylation (Thr366) following treatment with either pomiferin or CX-4945 for 24 h.

(D) Western blot analysis of MYCN and two CK2a isoforms following siRNA-mediated knock-down of CK2a1/2 for 48 h in SK-N-Be2 cells.

(E) Cell viability of SK-N-Be2 cells expressing mutant CK2 isoform with impaired binding to inhibitor. Bars represent mean ± S.D. of three biological replicates.

(F) Crystal structure of human apo CK2a1. Cartoon representation of the human CK2a1 protomer for which a-helices, b-strands, and loops are colored in yellow (for Ca carbons), cyan, and light magenta, respectively. The modeled pomiferin (purple for Ca carbons) and side chains (green) of amino acids, which are predicted to interact with pomiferin are shown with stick models.

(G) Ligand interaction diagram of pomiferin in the crystal structure of CK2a1, corresponding to the docking pose shown in (F); arrows indicate hydrogen bonds.

(H) SK-N-Be2 cell viability following treatment with pomiferin, isopomiferin or CX-4945 for 72 h. Bars represent mean ± S.D. of three biological replicates.

(I) MYCN abundance following treatment with pomiferin or CX-4945 for 24 h.

(J) Cellular accumulation of pomiferin or CX-4945 for indicated time points. Values represent mean ± S.D. of three replicate experiments.

(K) Quantification of cellular abundance following treatment with prenylated isoflavonoids and CX-4945. Cell samples treated with 10 µM for 3 h, followed by LC-MS analysis. Values represent mean ± S.D. of three replicate experiments.