pH sensitive nano layered double hydroxides reduce the hematotoxicity and enhance the anticancer efficacy of etoposide on non-small cell lung cancer.

Etoposide (VP16), used for the treatment of many carcinomas, can cause leukopenia, thrombocytopenia and hair loss. To overcome the side effects and achieve target therapy, layered double hydroxides (LDHs), a pH sensitive layered double hydroxide nanohybrid, was used here as a nano-carrier. The functions of LDHs-VP16 on non-small cell lung cancer (NSCLC) were firstly explored both in vitro and in vivo. In A549 cell line, LDH-VP16 induced apoptosis 2.3-fold as that of plain VP16 by targeting to mitochondrial, stocking cells in G1 phase. The cellular uptake demonstrated the delivery of LDH for VP16 to pass through the membrane and accumulate in mitochondria. As a carrier, LDH greatly decreased the liver toxicity and hematotoxicity of VP16. The detected liver parameters, including glutamic-oxaloacetic transaminase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT), were all turn back to normal range after the delivery of LDH, except ALP. In vivo, LDH-VP16 reduced A549 tumor growth significantly by 60.5%, whereas native VP16 exerted no significant anticancer activity. In LDH-VP16 treated mice, the AUC was increased by 6.26 folds as the native drug, and t1/2 of LDH-VP16 was prolonged from 6.68 to 98.78h. LDH-VP16 showed a targeting effect, which largely increase the concentration in tumor and lung. The phosphorylation antibody array and Western Blot of proteins from xenografts revealed that PI3K-AKT signaling was suppressed in the LDH-VP16 treated tumor, while in VP16 treated mice, ERBB signaling pathway was involved. These results suggested that LDH-VP16 diminishes hematotoxicity, targets NSCLC tumor, performs more effectively than VP16, and different signaling pathway is involved compared to VP16. STATEMENT OF SIGNIFICANCE: This paper explored that nano-sized layered double hydroxide (LDH) could be used as a pH sensitive delivery system to overcome hematotoxicity and enhance the bioavailability and anticancer efficacy of etoposide (VP16) against non small cell lung cancer, which was not reported before, as the best of our knowledge. We found that the liver and hematotoxicity is nearly recovered after the loading of VP16 in pH sensitive LDH, which prongs the half time from 6.68h to 98h, helps target VP16 to tumor and lung, and protects white blood cells by its pH sensitive and nano-size property. LDH-VP16 achieve markedly performance on non-small cell lung cancer by targeting to mitochondria of A549 cells in vitro and effectively inhibiting the PI3K-AKT signaling pathway in vivo. The inhibition ratio of VP16 on A549 tumor growth is increased from less than 20% (no significance compared to control) to 60.5% after the delivery of LDH. This work provides a novel system for the safe and efficient use of etoposide on non-small cell lung cancer and explores the mechanism of the function of nano carrier in cancer therapy both in vitro and in vivo.