Enzyme-responsive multistage vector for drug delivery to tumor tissue

Various nanodelivery systems have been designed to release therapeutic agents upon contact with specific enzymes. However, enzyme-triggered release typically takes place in the tissue interstitium, thereby resulting in the extracellular delivery of drugs. Here, we have designed an enzyme-stimulated multistage vector (ESMSV), which enables stimulus-triggered release of drug-encapsulated nanoparticles from a microparticle. Specifically, polymeric nanoparticles with a surface matrix metalloproteinase-2 (MMP2) peptide substrate were conjugated to the surface of porous silicon microparticles. In the presence of MMP2, the polymeric nanoparticles were released into the tumor interstitium. This platform can be used to attain triggered drug release, while simultaneously facilitating the cellular internalization of drugs. The results indicate that nanoparticle release was MMP2-specific and resulted in improved intracellular uptake of hydrophobic agents in the presence of MMP2. Furthermore, in a mouse model of melanoma lung metastasis, systemic delivery of ESMSVs caused a substantial increase in intracellular accumulation of agents in cancer cells in comparison to delivery with non-stimulus-responsive particles.

A pyruvate decarboxylase-mediated therapeutic strategy for mimicking yeast metabolism in cancer cells

Cancer cells have high rates of glycolysis and lactic acid fermentation in order to fuel accelerated rates of cell division (Warburg effect). Here, we present a strategy for merging cancer and yeast metabolism to remove pyruvate, a key intermediate of cancer cell metabolism, and produce the toxic compound acetaldehyde. This approach was achieved by administering the yeast enzyme pyruvate decarboxylase to triple negative breast cancer cells. To overcome the challenges of protein delivery, a nanoparticle-based system consisting of cationic lipids and porous silicon were employed to obtain efficient intracellular uptake. The results demonstrate that the enzyme therapy decreases cancer cell viability through production of acetaldehyde and reduction of lactic acid fermentation.

Multistage vector delivery of sulindac and silymarin for prevention of colon cancer

Familial adenomatous polyposis (FAP) is an inherited condition secondary to germline mutations in the APC gene, thus resulting in the formation of hundreds of colonic adenomas that eventually progress into colon cancer. Surgical removal of the colon remains the only treatment option to avoid malignancy, as long-term exposure to chemopreventive agents such as sulindac (a non-steroidal anti-inflammatory drug) and silymarin (phytoestrogen) is not feasible. Here, we have developed a multistage silicon-based drug delivery platform for sulindac and silymarin that preferentially interacts with colon cancer cells as opposed to normal intestinal mucosa. Preferential binding and internalization of these drugs into colon cancer cells was obtained using a targeting strategy against the protein meprin A, which we demonstrate is overexpressed in human colon cancer cells and in the small intestine of Apc(Min/+) mice. We propose that this delivery system could potentially be used to reduce drug-induced side effects in FAP patients, thus enabling long-term prevention of adenoma formation.