Intracellular pH-Regulating Nanoparticles to Improve Anticancer Drug Efficacy for Cancer Treatment.

Here, we describe an intracellular pH-regulating nanoparticle (IPRN), coencapsulated with chemosensitizers and anticancer agents for effective and safe cancer treatment. IPRN contains a tubulysin derivative (TUB), a hydrophobic anticancer drug, and pantoprazole (PTZ), a hydrophilic proton-pump inhibitor. IPRN with a size of 62 nm has an anionic surface charge and is stable for at least two weeks under storage conditions, though PTZ and TUB encapsulated in IPRN showed different drug release patterns. PTZ was released before TUB, controlling the cancer's intracellular pH, maintaining a pH at which TUB can work well. The encapsulated PTZ increased the pH of endolysosomes and inhibited ion trapping, with TUB ionization, thereby exhibiting increased cytotoxicity compared with free TUB observed in various cancer cell lines, such as human liver adenocarcinoma, human glioblastoma, and human pancreatic carcinoma. IPRN exhibited a 1.9-fold improved tumor growth inhibitory effect in a human liver adenocarcinoma-bearing mouse model, while minimizing the hepatotoxicity of free TUB. Thus, nanomedicines that contain both a chemosensitizer and an anticancer agent, such as IPRN, are expected to be next-generation anticancer agents that reduce the side effects of anticancer drugs and increase the therapeutic effect.