LukS-PV Induced HOXA9 Degradation in Acute Myeloid Leukemia Cells via Autophagy

Aberrant over-expression of HOXA9 is a prominent feature of AML driven by multiple oncogenes, thus therapeutic degradation of HOXA9 by autophagy may be an effective treatment strategy for AML. PVL is a pore forming cytotoxin secreted by Staphylococcus aureus, and it is composed of two subunits - LukS-PV and LukF-PV. Here, we show that LukS-PV can stimulate the conversion of LC3-I to LC3-II in AML cells in a concentration-dependent manner, and autophagic vacuoles can be found in LukS-PV-treated THP-1 cells. Furthermore, we find that an accumulation of LC3-positive structures in AML cells exposed to LukS-PV, indicating that an increased autophagic flux were formed. Therefore, LukS-PV induced autophagy of AML cells. We also demonstrated that LukS-PV could regulate the expression of HOXA9 at the protein level. HOXA9 molecules were detected in autophagosomes after LukS-PV treatment, indicating that autophagy induction accounted for the degradation of HOXA9.