Bafilomycin A1

Bafilomycin A1 (BafA1) is a specific and reversible inhibitor of vacuolar H⁺-ATPase (V-ATPase) with IC₅₀ values of 4-400 nmol/mg. Bafilomycin A1, a macrolide antibiotic, is also used as an autophagy inhibitor at the late stage. Bafilomycin A1 blocks autophagosome-lysosome fusion and inhibits acidification and protein degradation in lysosomes of cultured cells. Bafilomycin A1 induces apoptosis^[1][2][3]. IC50 & Target:V-ATPase^[1] In Vitro: Bafilomycin A1 is treated to different types of membrane ATPases with the I₅₀ of 400 nmol/mg, 4 nmol/mg and 50 nmol/mg for the vacuolar ATPases of a fungus (N. crassa), a plant (Z. mays), and an animal (bovine abrenal medulla). The I₅₀ values refer as μmol of Bafilomycin A1 per mg of protein giving 50% inhibition of ATPase activity^[1].
Bafilomycin A1 ((-)-Bafilomycin A1) disrupts autophagic flux by inhibiting both V-ATPase-dependent acidification and Ca-P60A/SERCA-dependent autophagosome-lysosome fusion^[2].
Bafilomycin A1 at a low concentration (1 nM) effectively and specifically inhibits and kills pediatric B-cell acute lymphoblastic leukemia cells. It targets both early and late stages of the autophagy pathway, mitochondria and induces caspase-independent apoptosis. Bafilomycin A1 induces the binding of Beclin 1 to Bcl-2, which further inhibits autophagy and promotes apoptotic cell death^[5].
The growth of the BEL-7402 hepatocellular carcinoma and HO-8910 ovarian cancer cell lines are retarded and the metastatic potential is inhibited by Bafilomycin A1. Transmission electron microscopy and assays of capsase-3 and -9 suggest that Bafilomycin A1 induces apoptosis^[6].
Bafilomycin A1 inhibits the growth of a variety of cultured cells dose-dependently, including golden hamster embryo and NIH-3T3 fibroblasts, whether or not they are transformed, and PC12 and HeLa cells. The IC₅₀ of Bafilomycin A1 for inhibition of cell growth ranges from 10 to 50 nM^[7]. In Vivo: Chronic treatment with low-dose Bafilomycin A1 (0.1 mg/kg) slightly inhibits the tumor volume, but the final tumor volume does not differ significantly from the control. However, chronic treatment with high dose Bafilomycin A1 (1 mg/kg) inhibits the tumor growth significantly, compared with controls, after 21 days^[8].
Bafilomycin A1 (0.1 mg/kg or 1 mg/kg; i.p. daily for 3 days) extends the survival of B-cell acute lymphoblastic leukemia (B-ALL) xenograft mice with advanced disease^[9].