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Polypeptide-based nanogels co-encapsulating a synergistic combination of doxorubicin with 17-AAG show potent anti-tumor activity in ErbB2-driven breast cancer models.

ABSTRACT: ErbB2-driven breast cancers constitute 20-25% of the cases diagnosed within the USA. The humanized anti-ErbB2 monoclonal antibody, Trastuzumab (Herceptin™; Genentech), with chemotherapy is the current standard of treatment. Novel agents and strategies continue to be explored, given the challenges posed by Trastuzumab-resistance development in most patients. The HSP90 inhibitor, 17-allylaminodemethoxygeldanamycin (17-AAG), which induces ErbB2 degradation and attenuates downstream oncogenic signaling, is one such agent that showed significant promise in early phase I and II clinical trials. Its low water solubility, potential toxicities and undesirable side effects observed in patients, partly due to the Cremophor-based formulation, have been discouraging factors in the advancement of this promising drug into clinical use. Encapsulation of 17-AAG into polymeric nanoparticle formulations, particularly in synergistic combination with conventional chemotherapeutics, represents an alternative approach to overcome these problems. Herein, we report an efficient co-encapsulation of 17-AAG and doxorubicin, a clinically well-established and effective modality in breast cancer treatment, into biodegradable and biocompatible polypeptide-based nanogels. Dual drug-loaded nanogels displayed potent cytotoxicity in a breast cancer cell panel and exerted selective synergistic anticancer activity against ErbB2-overexpressing breast cancer cell lines. Analysis of ErbB2 degradation confirmed efficient 17-AAG release from nanogels with activity comparable to free 17-AAG. Furthermore, nanogels containing both 17-AAG and doxorubicin exhibited superior antitumor efficacy in vivo in an ErbB2-driven xenograft model compared to the combination of free drugs. These studies demonstrate that polypeptide-based nanogels can serve as novel nanocarriers for encapsulating 17-AAG along with other chemotherapeutics, providing an opportunity to overcome solubility issues and thereby exploit its full potential as an anti-cancer agent.

SUBMITTER: Desale SS

PROVIDER: S-EPMC4430376 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature

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Polypeptide-based nanogels co-encapsulating a synergistic combination of doxorubicin with 17-AAG show potent anti-tumor activity in ErbB2-driven breast cancer models.

Desale Swapnil S SS Raja Srikumar M SM Kim Jong Oh JO Mohapatra Bhopal B Soni Kruti S KS Luan Haitao H Williams Stetson H SH Bielecki Timothy A TA Feng Dan D Storck Matthew M Band Vimla V Cohen Samuel M SM Band Hamid H Bronich Tatiana K TK

Journal of controlled release : official journal of the Controlled Release Society 20150203

ErbB2-driven breast cancers constitute 20-25% of the cases diagnosed within the USA. The humanized anti-ErbB2 monoclonal antibody, Trastuzumab (Herceptin™; Genentech), with chemotherapy is the current standard of treatment. Novel agents and strategies continue to be explored, given the challenges posed by Trastuzumab-resistance development in most patients. The HSP90 inhibitor, 17-allylaminodemethoxygeldanamycin (17-AAG), which induces ErbB2 degradation and attenuates downstream oncogenic signal ...[more]

PMID: 25660204

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Project description:The limited clinical efficacy of monotherapies in the clinic has urged the development of novel combination platforms. Taking advantage of light-triggered photodynamic treatment combined together with the controlled release of nanomedicine, it has been possible to treat cancer without eliciting any adverse effects. However, the challenges imposed by limited drug loading capacity and complex synthesis process of organic nanoparticles (NPs) have seriously impeded advances in chemo-photodynamic combination therapy. In this experiment, we utilize our previously synthesized porphyrin-grafted lipid (PGL) NPs to load highly effective chemotherapeutic drug, doxorubicin (DOX) for synergistic chemo-photodynamic therapy. Methods: A relatively simple and inexpensive rapid injection method was used to prepare porphyrin-grafted lipid (PGL) NPs. The self-assembled PGL NPs were used further to encapsulate DOX via a pH-gradient loading protocol. The self-assembled liposome-like PGL NPs having a hydrophilic core were optimized to load DOX at an encapsulation efficiency (EE) of ~99%. The resultant PGL-DOX NPs were intact, highly stable and importantly these NPs successfully escaped from the endo-lysosomal compartment after laser irradiation to release DOX in the cytosol. The therapeutic efficacy of the aforementioned formulation was validated both in vitro and in vivo. Results: PGL-DOX NPs demonstrated excellent cellular uptake, chemo-photodynamic response, and fluorescence imaging ability in different cell lines. Under laser irradiation, cells treated with a low molar concentration of PGL-DOX NPs reduced cell viability significantly. Moreover, in vivo experiments conducted in a xenograft mouse model further demonstrated the excellent tumor accumulation capability of PGL-DOX NPs driven by the enhanced permeability and retention (EPR) effect. Through fluorescence imaging, the biodistribution of PGL-DOX NPs in tumor and major organs was also easily monitored in real time in vivo. The inherent ability of porphyrin to generate ROS under laser irradiation combined with the cytotoxic effect of the anticancer drug DOX significantly suppressed tumor growth in vivo. Conclusion: In summary, the PGL-DOX NPs combined chemo-photodynamic nanoplatform may serve as a potential candidate for cancer theranostics.

Project description:Heat shock protein 90 (HSP90) is a molecular chaperone which stabilizes client proteins with important roles in tumor growth. 17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of HSP90 ATPase activity, occupies the ATP binding site of HSP90 causing a conformational change which destabilizes client proteins and directs them towards proteosomal degradation. Malignant melanomas have active RAF-MEK-ERK signaling which can occur either through an activating mutation in BRAF (BRAFV600E) or through activation of signal transduction upstream of BRAF. Prior work showed that 17-AAG inhibits cell growth in BRAFV600E and BRAF wildtype (BRAFWT) melanomas, although there were conflicting reports about the dependence of BRAFV600E and BRAFWT upon HSP90 activity for stability. Here, we demonstrate that BRAFWT and CRAF are bound by HSP90 in BRAFWT, NRAS mutant melanoma cells. HSP90 inhibition by 17-AAG inhibits ERK signaling and cell growth by destabilizing CRAF but not BRAFWT in the majority of NRAS mutant melanoma cells. The highly-selective BRAFV600E inhibitor, PLX4032 (vemurafenib), inhibits ERK signaling and cell growth in mutant BRAF melanoma cells, but paradoxically enhances signaling in cells with wild-type BRAF. In our study, we examined whether 17-AAG could inhibit PLX4032-enhanced ERK signaling in BRAFWT melanoma cells. As expected, PLX4032 alone enhanced ERK signaling in the BRAFWT melanoma cell lines Mel-Juso, SK-Mel-2, and SK-Mel-30, and inhibited signaling and cell growth in BRAFV600E A375 cells. However, HSP90 inhibition by 17-AAG inhibited PLX4032-enhanced ERK signaling and inhibited cell growth by destabilizing CRAF. Surprisingly, 17-AAG also stimulated melanin production in SK-Mel-30 cells and enhanced TYRP1 and DCT expression without stimulating TYR production in all three BRAFWT cell lines studied as well as in B16F10 mouse melanoma cells. In vivo, the combination of 17-AAG and cellular immunotherapy directed against Tyrp1 enhanced the inhibition of tumor growth compared to either therapy alone. Our studies support a role for 17-AAG and HSP90 inhibition in enhancing cellular immunotherapy for melanoma.

Dataset Information

Polypeptide-based nanogels co-encapsulating a synergistic combination of doxorubicin with 17-AAG show potent anti-tumor activity in ErbB2-driven breast cancer models.

Publications

Polypeptide-based nanogels co-encapsulating a synergistic combination of doxorubicin with 17-AAG show potent anti-tumor activity in ErbB2-driven breast cancer models.

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