αβ-Targeted Delivery of Camptothecin-Encapsulated Carbon Nanotube-Cyclic RGD in 2D and 3D Cancer Cell Culture.

Integrin αvβ3 is widely expressed in various types of human cancer lines and plays a key role in angiogenesis for tumor growth and metastasis. Delivery of therapeutics to αvβ3-expressing tumors can thus be a promising approach for treating cancer. For targeted delivery of anticancer therapeutics to αvβ3-expressing tumor cells, cyclic arginylglycylaspartic acid (RGD) peptide was covalently conjugated to the surface of carboxylic acid-functionalized carbon nanotubes (fCNTs), and the topoisomerase I inhibitor camptothecin (CPT) was encapsulated in the fCNTs (CPT@fCNT-RGD). CPT@fCNT-RGD was successfully delivered to αvβ3-expressing A375 cells, and compared with nontargeted CPT@fCNT, it provided 3.78- and 3.02-fold increases in the anticancer effect in 2D and 3D culture. Analysis of apoptosis-related gene expression shows that the expression levels of Bax, cleaved caspase-3, and nuclear factor kappa-light-chain-enhancer of activated B cells were significantly increased in A375 cells incubated with CPT@fCNT-RGD compared with those incubated with CPT@fCNT. These results suggest that cyclic RGD-conjugated CNTs encapsulating an anticancer therapeutic can be a promising platform for treating cancer.