Antitumor effects and preliminary systemic toxicity of ANISpm in vivo and in vitro

Polyamines as a vector to ferry toxic agents have attracted attention, and naphthalimide-polyamine conjugates show potent activity and tumor cell selectivity. The present study was carried out to evaluate the antitumor effects and preliminary systemic toxicity of ANISpm, a novel 3-amino-naphthalimide-spermine conjugate. The polyamine transport system recognition of ANISpm, supported by α-difluoromethylornithine (DFMO)/spermidine (Spd) experiments, is in accordance with its potent cell selectivity between human hepatoma HepG2 cells and normal QSG7701 hepatocyte. The antiproliferative effect is because of ANISpm-induced cell apoptosis, a common characteristic of both naphthalimide and polyamine analogs. Various apoptotic assessment assays have shown that ANISpm can induce apoptosis through the PI3K/Akt signal pathway. The apoptotic signaling cascade involves Akt inactivation, which results in a series of cellular events. The downstream pathway includes Bad dephosphorylation, dissociation of 14-3-3 and Bad, and binding to Bcl-xL, which triggers the disruption of the mitochondrial membrane, release of cytochrome c, and caspases' cascade activation. Furthermore, the Akt/mTOR signal pathway is also involved in ANISpm-mediated cell-cycle arrest. Additive DFMO or Spd, which only enhances or attenuates ANISpm-mediated cell apoptosis, respectively, does not alter the signal pathway. In addition, preliminary toxicology evaluation showed that ANISpm had no obvious system toxicity at a dose of 2.5 mg/kg, which exerted potent antitumor activity in vivo, especially hematotoxicity. Thus, ANISpm merits further investigation as a potential chemotherapeutic agent against hepatocellular carcinoma.