APTO-253

APTO-253 (LOR-253) is a small molecule that 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 induction of the Krüppel-like factor 4 (KLF4) tumor suppressor^[1][2]. APTO-253 has antiarthritic activity^[3]. IC50 & Target: c-Myc^[1]; KLF4^[2] In Vitro: APTO-253 (LOR-253) is an inducer of KLF4. 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, with IC₅₀s of 105 ± 2.4 nM and 1387 ± 94 nM, respectively. 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 with IC₅₀s ranging from 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. Futhermore, APTO-253 is a potent stabilizer of Gquadruplex (G4) motifs, and demonstrates the greatest propensity for stabilizing the MYC G4 sequences^[3]. In Vivo: APTO-253 (LOR-253; 15 mg/kg; IV; twice per day for 2 consecutive days per week for 14 days) has antiarthritic activity in a CIA model^[3].