P-Glycoprotein Antibody Functionalized Carbon Nanotube Overcomes the Multidrug Resistance of Human Leukemia Cells

Multidrug resistance (MDR), which is related to cancer chemotherapy, tumor stem cells, and tumor metastasis, is a huge obstacle for the effective cancer therapy. One of the underlying mechanisms of MDR is the increased efflux of anticancer drugs by overexpressed P-glycoprotein (P-gp) of multidrug resistant cells. In this work, the antibody of P-gp (anti-P-gp) functionalized water-soluble single-walled carbon nanotubes (Ap-SWNTs) loaded with doxorubicin (Dox), Dox/Ap-SWNTs, were synthesized for challenging the MDR of K562 human leukemia cells. The resulting Ap-SWNTs could not only specifically recognize the multidrug resistant human leukemia cells (K562R), but also demonstrate the effective loading and controllable release performance for Dox toward the target K562R cells by exposing to near-infrared radiation (NIR). The recognition capability of Ap-SWNTs toward the K562R cells was confirmed by flow cytometry (FCM) and confocal laser scanning microscopy (CLSM). The binding affinity of Ap-SWNTs toward drug-resistant K562R cells was ca. 23-fold higher than that toward drug-sensitive K562S cells. Additionally, CLSM indicated that Ap-SWNTs could specifically localize on the cell membrane of K562R cells and the fluorescence of Dox in K562R cells could be significantly enhanced after the employment of Ap-SWNTs as carrier. Moreover, the composite of Dox and Ap-SWNTs (Dox/Ap-SWNTs) expressed 2.4-fold higher cytotoxicity and showed the significant cell proliferation suppression toward K562R leukemia cells (p < 0.05) as compared with free Dox which is popularly employed in clinic trials. These results suggest that the Ap-SWNTs are the promising drug delivery vehicle for overcoming the MDR induced by the overexpression of P-gp on cell membrane. Ap-SWNTs loaded with drug molecules could be used to suppress the proliferation of multidrug resistant cells, destroy the tumor stem cells, and inhibit the metastasis of tumor