Apoptozole

Apoptozole is a small inhibitor targets HSC70 and HSP72, with the K_D values of 210nM and 140nM, respectively ^[1]. Apoptozole promotes the instability of the lysosomal membrane and induces lysosomal membrane permeabilization (LMP) by inhibiting lysosomal HSC70 ^[2]. Apoptozole has been widely used in leukemia cell models to induce cell death^[3].

In vitro, Apoptozole treatment for 72 hours significantly inhibited the viability of HeLa cells, SK-OV-3 cells and U373 cells, with the IC₅₀ values of 5.92±0.47µM, 4.25±0.37µM, and 2.23±0.71µM, respectively^[4]. Apoptozole treatment with 3μM for 72 hours inhibited the replication of Zika virus in Huh7 cells, reduced the production of Zika virus proteins, without toxicity to the cells^[5]. Treatment with 0.5μM Apoptozole for 12h resulted in increased levels of cleaved caspase-1 and increased IL-1β abundance in NLRC4-H443p-transfected HEK293T cells^[6].

In vivo, Apoptozole was injected intraperitoneally at a dose of 4mg/kg every other day for 2 weeks, which significantly inhibited the tumor volume of A549 xenograft tumor mice without affecting the body weight of the mice^[7]. 30 minutes before the cecal ligation and puncture (CLP) procedure in mice, a single dose of 10mg/kg of Apoptozole was intraperitoneally injected, resulting in a significant decrease in the survival rate of mice^[8].

References:
[1]Evans L E, Cheeseman M D, Yahya N, et al. Investigating apoptozole as a chemical probe for HSP70 inhibition[J]. PLoS One, 2015, 10(10): e0140006.
[2] Park S H, Ko W, Park S H, et al. Evaluation of the interaction between Bax and Hsp70 in cells by using a FRET system consisting of a fluorescent amino acid and YFP as a FRET pair[J]. ChemBioChem, 2020, 21(1-2): 59-63.
[3] Park S H, Kim W J, Li H, et al. Anti-leukemia activity of a Hsp70 inhibitor and its hybrid molecules[J]. Scientific reports, 2017, 7(1): 3537.
[4] Park S H, Baek K H, Shin I, et al. Subcellular Hsp70 inhibitors promote cancer cell death via different mechanisms[J]. Cell chemical biology, 2018, 25(10): 1242-1254. e8.
[5] Yang J, Xu Y, Yan Y, et al. Small molecule inhibitor of ATPase activity of HSP70 as a broad-spectrum inhibitor against flavivirus infections[J]. ACS infectious diseases, 2020, 6(5): 832-843.
[6] Raghawan A K, Ramaswamy R, Radha V, et al. HSC70 regulates cold-induced caspase-1 hyperactivation by an autoinflammation-causing mutant of cytoplasmic immune receptor NLRC4[J]. Proceedings of the National Academy of Sciences, 2019, 116(43): 21694-21703.
[7] Ko S K, Kim J, Na D C, et al. A small molecule inhibitor of ATPase activity of HSP70 induces apoptosis and has antitumor activities[J]. Chemistry & biology, 2015, 22(3): 391-403.
[8] Yuan X, Chen Y, Chen G, et al. The heat shock protein 70 plays a protective role in sepsis by maintenance of the endothelial permeability[J]. BioMed Research International, 2020, 2020(1): 2194090.