Design, Synthesis, and Characterization of a Paclitaxel Formulation Activated by Extracellular MMP9.

The concept of triggered drug release offers a possibility to overcome the toxic side effects of chemotherapeutics in cancer treatment by reducing systemic exposure to the active drug. In the present work, the concept foresees the use of the extracellular enzyme MMP9 as an enzymatic trigger for drug release in the proximity of tumor cells. METHODS: A paclitaxel-hemisuccinate-peptide conjugate as a building block for self-assembling nanoparticles was synthesized using standard conjugation approaches. The building block was purified via preparative HPLC and analyzed by LC-MS. Nanoparticles were formed using the nanoprecipitation method and characterized. For selection of a suitable in vitro model system, common bioanalytical methods were used to determine mRNA expression, enzyme amount, and activity of MMP9. RESULTS: The MMP9-labile prodrug was synthesized and characterized. Nanoparticles were formed out of MMP9-labile conjugate-building blocks. The nanoparticle's diameter averaged at around 120 nm and presented a spherical shape. LN-18 cells, a glioblastoma multiforme derived cell line, were chosen as an in vitro model based on findings in cancer tissue and cell line characterization. The prodrug showed cytotoxicity in LN-18 cells, which was reduced by addition of an MMP9 inhibitor. CONCLUSION: taken together, we confirmed increased MMP9 in several cancer tissues (cervical, esophageal, lung, and brain) compared to healthy tissue and showed the effectiveness of MMP9-labile prodrug in in vitro tests.

PDMS-PMOXA-Nanoparticles Featuring a Cathepsin B-Triggered Release Mechanism.

BACKGROUND: It was our intention to develop cathepsin B-sensitive nanoparticles for tumor-site-directed release. These nanoparticles should be able to release their payload as close to the tumor site with a decrease of off-target effects in mind. Cathepsin B, a lysosomal cysteine protease, is associated with premalignant lesions and invasive stages of cancer. Previous studies have shown cathepsin B in lysosomes and in the extracellular matrix. Therefore, this enzyme qualifies as a trigger for such an approach. METHODS: Poly(dimethylsiloxane)-b-poly(methyloxazoline) (PDMS-PMOXA) nanoparticles loaded with paclitaxel were formed by a thin-film technique and standard coupling reactions were used for surface modifications. Despite the controlled release mechanism, the physical properties of the herein created nanoparticles were described. To characterize potential in vitro model systems, quantitative polymerase chain reaction and common bioanalytical methods were employed. CONCLUSIONS: Stable paclitaxel-loaded nanoparticles with cathepsin B digestible peptide were formed and tested on the ovarian cancer cell line OVCAR-3. These nanoparticles exerted a pharmacological effect on the tumor cells suggesting a release of the payload.

Unravelling the Antiproliferative Activity of 1,2,5-oxadiazole Derivatives.

AIM: To develop several new derivatives aimed to complete the studies concerning the antiproliferative profile of the oxadiazole derivative MD77. MATERIALS AND METHODS: The substitution pattern around the phenyl rings of this compound was analyzed through the synthesis of positional isomers and of analogues bearing different substituents at the para positions (2-12). RESULTS: The results of the antiproliferative activity of these derivatives versus HCT-116 and HeLa cancer cell lines shed light on the effects of the presence, nature and position of such substituents. Notably, derivative 4, a regioisomer of 1 in which the substituents at the para positions of the phenyl rings were inverted, showed the best antiproliferative profile, exhibiting a significant activity also against MCF7 and MDA-MB 468 cancer cell lines. CONCLUSION: Preliminary results showed the ability of compound 4 to reduce the viability of cancer cells by counteracting human recombinant topoisomerase II α relaxation activity.

Synthesis and Characterization of PDMS-PMOXA-Based Polymersomes Sensitive to MMP-9 for Application in Breast Cancer.

Cytotoxic compounds used to treat cancer are often associated with adverse events. The development of formulations activated by tumor-specific triggers would allow a reduction of systemic exposure while maintaining therapeutic concentrations in the tumor. One enzyme with proteolytic activity reported to be involved in tumor progression and assumed to be enhanced in the tumor environment is the matrix metalloproteinase 9 (MMP-9). In our study, we aimed to develop surface-modified PDMS-PMOXA polymersomes able to release their cytotoxic payload upon digestion by MMP-9. To test the applicability of such a system in breast cancer, this tumor entity was assessed for MMP-9 expression, supporting breast cancer as a potential target. The surface-modified polymersomes were synthesized and formulated resulting in paclitaxel-loaded particles of about 320 ± 153.15 nm in size with a surface potential of 0.04 ± 0.007 mV. After the expression and activity of MMP-9 in MCF7 cells were verified, this cell line was used for further analysis. Treatment of MCF7 cells with the polymersomes significantly reduced cell viability, this effect was abolished after addition of MMP-inhibitors, suggesting proteolytic activation. In zebrafish embryos, the polymersomes were observed in the circulation with some enrichment in liver and agglomerates in the caudal veins. Importantly, in zebrafish embryos xenografted with mKate2-expressing MCF7 cells, the amount of tumor cells, quantified by detecting the copies of the heterologously expressed fluorescent protein, significantly decreased after treatment with PDMS-PMOXA-SRL-paclitaxel polymersomes. Taken together, our data suggest that polymersomes modified with an MMP-9 labile peptide and loaded with paclitaxel can be formulated, and that these particles exert pharmacological activity upon enzymatic digestion.