APTO-253 (LOR-253) inhibits c-Myc expression, stabilizes G-quadruplex DNA, and induces cell cycle arrest and apoptosis in acute myeloid leukemia cells. APTO-253 mediates anticancer activity through the induction of the KLF4 tumor suppressor.

APTO-253 (5 μM) induces KLF4 expression and enhances apoptosis induced by NSC 119875 in both SKOV3 and OVCAR3 cells. APTO-253 (5 μM) also leads to G1 phase arrest and reduces S and G2/M phase cells in SKOV3 and OVCAR3 cells [1]. APTO-253 is cytotoxic to Raji and Raji/253R cell lines (IC50s: 105 nM and 1387 nM). APTO-253 (0.5 μM) also causes DNA damage in Raji cells. BRCA1/2 deficient cells are hypersensitive to APTO-253. ABCG2 overexpressed HEK-293 cells are resistant to APTO-253 and inhibition of ABCG2 reverses resistance to APTO-253 in Raji/253R [2]. APTO-253 suppresses the proliferation of acute myeloid leukemia (AML) cell lines and various forms of lymphoma cell lines (IC50s: 57 nM to 1.75 μM). APTO-253 (500 nM) also causes G0/G1 cell cycle arrest, induces apoptosis, and down-regulates MYC RNA and protein expression in AML lines. APTO-253 (500 nM) leads to DNA damage response pathways in MV4-11 cells. Furthermore, APTO-253 is a potent stabilizer of G-quadruplex (G4) motifs and demonstrates the greatest propensity for stabilizing the MYC G4 sequences.