GZ17-6.02 interacts with carboplatin and etoposide to kill neuroblastoma cells

The biology of GZ17-6.02 alone and more so in combination with either of the standard-of-care agents etoposide or carboplatin killed MYCN overexpressing neuroblastoma (NB) cells is unknown. The methods involved in this study are in-cell immunoblotting, trypan blue exclusion, plasmid and siRNA transfection, assessment of autophagy using a plasmid expressing LC3-GFP-RFP. GZ17-6.02 (602) comprises, by mass, a ratio of curcumin (1.0), harmine (1.3), and isovanillin (7.7). In tumors dosed with 602, the ratio becomes curcumin (1.0), harmine (16), and isovanillin (6.1) (602NR). GZ17-6.02 activated ATM, AMPK, ULK1, ATG13, and PERK and inactivated ERBB1, ERBB2, ERBB3, ERBB4, AKT, mTORC1, mTORC2, SRC, NFκB, YAP, and eIF2α. 602 enhanced autophagosome formation and autophagic flux that was amplified when it was combined with etoposide or carboplatin. Compared with 602, 602NR caused significantly greater autophagosome formation that was also amplified when in combination with chemotherapy and which was reduced ~40% by knockdown of ATM or AMPKα and abolished by knockdown of Beclin1 or ATG5. Knockdown of ATM or AMPKα significantly reduced tumor cell death caused by 602 of 602NR, whereas endoplasmic reticulum stress (eIF2α) and macroautophagy (Beclin1, ATG5) were more effective at maintaining tumor cell survival. Combined knockdown of Beclin1 and the death receptor CD95 almost abolished the antitumor actions of 602 and 602NR. 602, and more so 602NR, kills MYCN NB cells and interacts with standard-of-care chemotherapeutics to cause further killing via autophagy and death receptor signaling.