Cisplatin is used to treat a variety of tumors, but dose limiting toxicities or intrinsic and acquired resistance limit its application in many types of cancer including prostate. We report a unique strategy to deliver cisplatin to prostate cancer cells by constructing Pt ( DNA cross-link ͉ metals in medicine ͉ PSMA ͉ controlled release

Most low molecular weight platinum anticancer drugs have short blood circulation times that are reflected in their reduced tumor uptake and intracellular DNA binding. A platinum(IV) complex of the formula c,c,t-[Pt(NH 3 ) 2 Cl 2 (O 2 CCH 2 CH 2 CO 2 H)(O 2 CCH 2 CH 2 CONH-PEG-FA)] (1) containing a folate derivative (FA) at an axial position was prepared and characterized. Folic acid offers a means of targeting human cells that highly overexpress the folate receptor (FR). Compound 1 was attached to the surface of an amine functionalized single walled carbon nanotube (SWNT-PL-PEG-NH 2 ) through multiple amide linkages to use the SWNTs as a "longboat delivery system" for the platinum warhead, carrying it to the tumor cell and releasing cisplatin upon intracellular reduction of Pt(IV) to Pt(II). The ability of SWNT tethered 1 to destroy selectively FR(+) vs FR(−) cells demonstrated its ability to target tumor cells that overexpress the FR on their surface. That the SWNTs deliver the folate-bearing Pt(IV) cargos into FR(+) cancer cells by endocytosis was demonstrated by the localization of fluorophorelabeled SWNTs using fluorescence microscopy. Once inside the cell, cisplatin formed upon reductive release from the longboat oars enters the nucleus and reacts with its target nuclear DNA, as determined by platinum atomic absorption spectroscopy of cell extracts. Formation of the major cisplatin 1,2-intrastrand d(GpG) cross-links on the nuclear DNA was demonstrated by use of a monoclonal antibody specific for this adduct. The SWNT-tethered compound 1 is the first construct in which both targeting and delivery have been incorporated into the same molecule; it is also the first demonstration that intracellular reduction of a Pt(IV) pro-drug leads to the cis-{Pt((NH 3 ) 2 } 1,2-intrastrand d(GpG) crosslink in nuclear DNA.

The genomic revolution has identified therapeutic targets for a plethora of diseases, creating a need to develop robust technologies for combination drug therapy. In the present work, we describe a self-assembled polymeric nanoparticle (NP) platform to target and control precisely the codelivery of drugs with varying physicochemical properties to cancer cells. As proof of concept, we codelivered cisplatin and docetaxel (Dtxl) to prostate cancer cells with synergistic cytotoxicity. A polylactide (PLA) derivative with pendant hydroxyl groups was prepared and conjugated to a platinum(IV) [Pt(IV)] prodrug, c,t,c-½PtðNH 3 Þ 2 ðO 2 CCH 2 CH 2 COOHÞðOHÞCl 2 [PLAPt(IV)]. A blend of PLA-Pt(IV) functionalized polymer and carboxylterminated poly(D,L-lactic-co-glycolic acid)-block-poly(ethylene glycol) copolymer in the presence or absence of Dtxl, was converted, in microfluidic channels, to NPs with a diameter of ∼100 nm. This process resulted in excellent encapsulation efficiency (EE) and high loading of both hydrophilic platinum prodrug and hydrophobic Dtxl with reproducible EEs and loadings. The surface of the NPs was derivatized with the A10 aptamer, which binds to the prostatespecific membrane antigen (PSMA) on prostate cancer cells. These NPs undergo controlled release of both drugs over a period of 48-72 h. Targeted NPs were internalized by the PSMA-expressing LNCaP cells via endocytosis, and formation of cisplatin 1,2-d(GpG) intrastrand cross-links on nuclear DNA was verified. In vitro toxicities demonstrated superiority of the targeted dual-drug combination NPs over NPs with single drug or nontargeted NPs. This work reveals the potential of a single, programmable nanoparticle to blend and deliver a combination of drugs for cancer treatment.chemotherapy | drug delivery | polymer-drug conjugate | targeting | temporal release

Amine-functionalized polyvalent oligonucleotide gold nanoparticles (DNA-Au NP) were derivatized with a cisplatin prodrug, and the resulting DNA-Au NP conjugates were used to internalize multiple platinum centers. A platinum(IV) complex, c,c,t-[Pt(NH3)2Cl2(OH)(O2CCH2CH2CO2H)], was tethered to the surface of DNA-Au NPs through amide linkages. The platinum-tethered gold nanoparticles (Pt-DNA-Au NPs) were taken into several cancer cells. The drop in intracellular pH facilitated reductive release of cisplatin from the prodrug, which then formed 1,2-d(GpG) intrastrand cross-links in the cell nuclei as confirmed by an antibody specific for this adduct. The cytotoxicity of the platinum(IV) complex increases significantly in several cancer cell lines when the complex is attached to the surface of the DNA-Au NPs and in some instances exceeds that of cisplatin.