Platinum drug delivery against the detoxification of cytoplasmic thiols is urgently required for achieving efficacy in breast cancer treatment that is over expressed by glutathione (GSH, thiol-oligopeptide). GSH-resistant polymer-cisplatin core-shell nanoparticles were custom designed based on biodegradable carboxylic functional polycaprolactone (PCL)-block-poly(ethylene glycol) diblock copolymers. The core of the nanoparticle was fixed as 100 carboxylic units and the shell part was varied using various molecular weight poly(ethylene glycol) monomethyl ethers (MW of PEGs = 100-5000 g mol(-1)) as initiator in the ring-opening polymerization. The complexation of cisplatin aquo species with the diblocks produced core-shell nanoparticles of 75 nm core with precise size control the particles up to 190 nm. The core-shell nanoparticles were found to be stable in saline solution and PBS and they exhibited enhanced stability with increase in the PEG shell thickness at the periphery. The hydrophobic PCL layer on the periphery of the cisplatin core behaved as a protecting layer against the cytoplasmic thiol residues (GSH and cysteine) and exhibited <5% of drug detoxification. In vitro drug-release studies revealed that the core-shell nanoparticles were ruptured upon exposure to lysosomal enzymes like esterase at the intracellular compartments. Cytotoxicity studies were performed both in normal wild-type mouse embryonic fibroblast cells (Wt-MEFs), and breast cancer (MCF-7) and cervical cancer (HeLa) cell lines. Free cisplatin and polymer drug core-shell nanoparticles showed similar cytotoxicity effects in the HeLa cells. In MCF-7 cells, the free cisplatin drug exhibited 50% cell death whereas complete cell death (100%) was accomplished by the polymer-cisplatin core-shell nanoparticles. Confocal microscopic images confirmed that the core-shell nanoparticles were taken up by the MCF-7 and HeLa cells and they were accumulated both at the cytoplasm as well at peri-nuclear environments. The present investigation lays a new foundation for the polymer-based core-shell nanoparticles approach for overcoming detoxification in platinum drugs for the treatment of GSH over-expressed breast cancer cells.

Cancer cells are known to be glycolytic, driving increased glucose consumption and its conversion to lactate. This process modulates the tumor microenvironment (TME). In the TME, glycolytically activated immune cells often become anergic, leading to an increase in immune checkpoint proteins such as programmed cell death protein-1 (PD-1) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4). Most glycolytic inhibitors not only inhibit glycolysis of cancer but also of immune cells. Therefore, using a nanoparticle-delivered agent to preferentially inhibit glycolysis in tumor cells, and not in immune cells, has the potential to attenuate the expression of checkpoint proteins. Pyruvate dehydrogenase kinase 1 (PDK1) can be an important target to achieve tumor specific glycolysis inhibition. We report TME modulation by a mitochondrion-targeted nanoparticle (NP) containing a prodrug of dichloroacetate (DCA), a PDK1 inhibitor. We demonstrated that the targeted NP alters the TME which results in increased immunological activation against cancer cells, causing a decrease in mean tumor volume. Here, we also show findings that when Mito-DCA, a prodrug of DCA, was combined with anti-PD-1, a checkpoint inhibitor, results from in vivo syngeneic models showed an upregulation in the number of tumor infiltrating lymphocytes. This work provides a platform to bring therapeutic efficacy by selectively inhibiting glycolysis of cancer cells.

We report the first example of carboxylic functionalized poly(caprolactone) (PCL) block copolymer vesicles as a novel dual drug delivery pH responsive vehicle for oral administration under the gastrointestinal (GI) tract. A new carboxylic functionalized caprolactone monomer was custom designed through multistep organic reactions and polymerized under controlled ROP using polyethylene glycol (PEG-2000) to produce amphiphilic diblocks, PEG-b-CPCLx, with x = 25, 50, 75, and 100. These carboxylic PCL block copolymers were self-organized into 100-250 nm vesicular assemblies in water. The size and shape of the vesicular assemblies were confirmed by light scattering, zeta potential, and electron microscopes. These vesicles were capable of loading both hydrophilic molecules (Rhodamine B, Rh-B) and hydrophobic drugs such as ibuprofen (IBU) and camptothecin (CPT) in the core and layer, respectively. These pH-responsive PCL vesicles were stable in strong acidic conditions (pH < 2.0, stomach) and ruptured to release the loaded cargoes under neutral or basic pH (7.0 ≤ pH, similar to that of small intestine). The drug release kinetics under simulated GI tract revealed that the individual drug loaded vesicles followed the combination of diffusion and erosion pathway, whereas the dual drug loaded vesicles predominantly followed the diffusion controlled process. Thus, the custom designed PCL vesicles open up new area of pH stimuli responsive polymer vehicles for delivering multiple drugs in oral drug delivery which are yet to be explored for biomedical applications.

The present investigation reports polymer topology design principle for programming the enzymatic biodegradation and delivery of anticancer drugs at the intracellular compartments of breast and cervical cancers. To accomplish this goal, new classes of biodegradable amphiphilic block and random copolymers based on hydrophilic carboxylic-functionalized polycaprolactone (CPCL) and hydrophobic polycaprolactone (PCL) units were designed via ring-opening polymerization methodology. The interchain interactions and their packing were directly controlled by the topology of the polymers, and the block copolymers were found to be as semicrystalline materials. These amphiphilic block and random polymers were readily dispersible in water, and they self-assembled into <200 nm nanoparticles. These nanoparticles exhibited excellent capability for loading anticancer drug doxorubicin (DOX) in the hydrophobic pocket. In vitro drug release kinetics revealed that the polymer nanoscaffolds were stable under physiological conditions, and they exclusively ruptured in the presence of lysosomal esterase enzyme at the intracellular compartments to deliver DOX. The “burst” and “controlled” release of drugs from the polymer nanocarriers was directly controlled by length and chemical composition of block and random copolymers. In vitro cytotoxicity studies in breast cancer (MCF 7) and cervical cancer (HeLa) cells revealed that the nascent polymer nanoparticle was highly biocompatible and nontoxic to cells whereas their DOX-loaded nanoparticles accomplished >95% cell killing. Confocal microscopy reinstated the cellular uptake of the DOX-loaded polymer scaffold wherein the nanoparticle was highly concentrated at the nucleus and revealed that the drugs were predominantly delivered at the nucleus of the cells for apoptosis. Flow cytometry investigation confirmed the enhanced DOX delivering capability of block and random copolymer nanoparticles compared to free DOX. The newly designed fully biodegradable PCL-based block and random nanocarriers are excellent scaffolds for enzyme-mediated intracellular delivery of DOX, and the proof of concept was established in breast and cervical cancers.