Targeting intracellular MMPs efficiently inhibits tumor metastasis and angiogenesis

Sensitizing Triple Negative Breast Cancer to Tamoxifen Chemotherapy via a Redox-Responsive Vorinostat-containing Polymeric Prodrug Nanocarrier

There is an urgent and unmet need to develop effective therapies for triple negative breast cancers (TNBCs) which are much more aggressive and have poor prognosis due to lack of receptor targets for Her2-targeted and endocrine therapy. In this study we systematically evaluated the effect of Vorinostat (SAHA, a pan-HDAC inhibitor) in reactivating the expression of functional estrogen receptor α (ERα) and synergizing with tamoxifen (TAM, a selective estrogen-receptor modulator) in antitumor activity. In addition, a SAHA prodrug-based dual functional nanocarrier was developed for codelivery of SAHA and TAM for effective combination therapy.

Methods: A SAHA-containing polymeric nanocarrier, POEG-co-PVDSAHA was developed via reversible addition-fragmentation transfer (RAFT) polymerization with SAHA incorporated into the polymer through a redox-responsive disulfide linkage. The effect of both free SAHA and POEG-co-PVDSAHA on reactivating the expression of functional ERα was investigated in several human and murine TNBC cell lines via examining the mRNA and protein expression of ERα target genes. The cytotoxicity of free SAHA and TAM combination and TAM-loaded POEG-co-PVDSAHA micelles was examined via MTT assay. The in vivo antitumor activity of TAM-loaded POEG-co-PVDSAHA was investigated in a murine breast cancer model (4T1.2).

Results: Both free SAHA and POEG-co-PVDSAHA were effective in inducing the reexpression of functional estrogen receptor α (ERα), which may have helped to sensitize TNBCs to TAM. More importantly, POEG-co-PVDSAHA self-assembled to form small-sized micellar carrier that is effective in formulating and codelivery of TAM. TAM-loaded POEG-co-PVDSAHA micelles exhibited enhanced and synergistic cytotoxicity against TNBC cell lines compared with free SAHA, free TAM and TAM loaded into a pharmacologically inert control carrier (POEG-co-PVMA). In addition, codelivery of TAM via POEG-co-PVDSAHA micelles led to significantly improved antitumor efficacy in 4T1.2 tumor model compared with other groups such as combination of free SAHA and TAM and TAM-loaded POEG-co-PVMA micelles.

Conclusion: Our prodrug-based co-delivery system may provide an effective and simple strategy to re-sensitize TNBCs to TAM-based hormone therapy.

SRV2 promotes mitochondrial fission and Mst1-Drp1 signaling in LPS-induced septic cardiomyopathy

Mitochondrial fission is associated with cardiomyocyte death and myocardial depression, and suppressor of ras val-2 (SRV2) is a newly discovered pro-fission protein. In this study, we examined the mechanisms of SRV2-mediated mitochondrial fission in septic cardiomyopathy. Western blotting, ELISA, and immunofluorescence were used to evaluate mitochondrial function, oxidative balance, energy metabolism and caspase-related death, and siRNA and adenoviruses were used to perform loss- and gain-of-function assays. Our results demonstrated that increased SRV2 expression promotes, while SRV2 knockdown attenuates, cardiomyocyte death in LPS-induced septic cardiomyopathy. Mechanistically, SRV2 activation promoted mitochondrial fission and physiological abnormalities by upregulating oxidative injury, ATP depletion, and caspase-9-related apoptosis. Our results also demonstrated that SRV2 promotes mitochondrial fission via a Mst1-Drp1 axis. SRV2 knockdown decreased Mst1 and Drp1 levels, while Mst1 overexpression abolished the mitochondrial protection and cardiomyocyte survival-promoting effects of SRV2 knockdown. SRV2 is thus a key novel promotor of mitochondrial fission and Mst1-Drp1 axis activity in septic cardiomyopathy.

Myocardial-Infarction-Responsive Smart Hydrogels Targeting Matrix Metalloproteinase for On-Demand Growth Factor Delivery

Although in situ restoration of blood supply to the infarction region and attenuating pre-existing extracellular matrix degradation remain potential therapeutic approaches for myocardial infarction (MI), local delivery of therapeutics has been limited by low accumulation (inefficacy) and unnecessary diffusion (toxicity). Here, a dual functional MI-responsive hydrogel is fabricated for on-demand drug delivery to promote angiogenesis and inhibit cardiac remodeling by targeting upregulated matrix metalloproteinase-2/9 (MMP-2/9) after MI. A glutathione (GSH)-modified collagen hydrogel (collagen-GSH) is prepared by conjugating collagen amine groups with GSH sulfhydryl groups and the recombinant protein GST-TIMP-bFGF (bFGF: basic fibroblast growth factor) by fusing bFGF with glutathione-S-transferase (GST) and MMP-2/9 cleavable peptide PLGLAG (TIMP). Specific binding between GST and GSH significantly improves the amount of GST-TIMP-bFGF loaded in collagen-GSH hydrogel. The TIMP peptide enclosed between GST and bFGF responds to MMPs for on-demand release during MI. Additionally, the TIMP peptide is a competitive substrate of MMPs that inhibits the excessive degradation of cardiac matrix by MMPs after MI. GST-TIMP-bFGF/collagen-GSH hydrogels promote the recovery of MI rats by enhancing vascularization and ameliorating myocardium remodeling. The results suggest that on-demand growth factor delivery by synchronously controlling binding and responsive release to promote angiogenesis and attenuate cardiac remodeling might be promising for the treatment of ischemic heart disease.

Enzyme-induced in vivo assembly of gold nanoparticles for imaging-guided synergistic chemo-photothermal therapy of tumor

This article describes a nanoplatform based on matrix metalloproteinase (MMP)-responsive gold nanoparticles (AuNPs) for tumor-targeted photoacoustic (PA) imaging-guided photothermal therapy and drug delivery. AuNPs were grafted with complementary DNA strands, tethered with doxorubicin and coated with poly(ethylene glycol) via a thermal-labile linker and a MMP-cleavable peptide, respectively. The nanoprobes remained well-isolated in healthy tissues, but formed aggregates rapidly under MMP-abundant conditions. The DNA hybridization-induced assembly of the nanoprobes led to prolonged tumor retention and strong near-infrared (NIR) absorption, which is beneficial to deep-tissue imaging and therapy. Compared with MMP-inert nanoprobes, our platform demonstrated significantly enhanced efficiency in PA imaging and photothermal conversion upon NIR irradiation. Meanwhile, doxorubicin could be released rapidly in response to the localized elevation of temperature, leading to synergistic chemo-photothermal therapy. The unique nanoplatform may find applications in effective disease control by delivering imaging and therapy to tumors with high specificity, safety, and universality.

Nanoencapsulated betulinic acid analogue distinctively improves colorectal carcinoma in vitro and in vivo

Betulinic acid, a plant secondary metabolite, has gained significant attention due to its antiproliferative activity over a range of cancer cells. A promising betulinic acid analogue (2c) with better therapeutic efficacy than parent molecule to colon carcinoma cells has been reported. Despite impressive biological applications, low aqueous solubility and bioavailability create difficulties for its therapeutic applications. To overcome these lacunae and make it as a promising drug candidate we have encapsulated the lead betulinic acid derivative (2c) in a polymeric nanocarrier system (2c-NP) and evaluated its in vitro and in vivo therapeutic efficacy. Apoptosis that induces in vitro antiproliferative activity was significantly increased by 2c-NP compared to free-drug (2c), as assured by MTT assay, Annexin V positivity, JC1 analysis and cell cycle study. The therapeutic potential measured in vitro and in vivo reflects ability of 2c-NP as an effective therapeutic agent for treatment of colon carcinoma and future translation to clinical trials.

Molecular size-dependent specificity of hyaluronan on functional properties, morphology and matrix composition of mammary cancer cells

High levels of hyaluronan (ΗΑ), a major extracellular matrix (ECM) glycosaminoglycan, have been correlated with poor clinical outcome in several malignancies, including breast cancer. The high and low molecular weight HΑ forms exert diverse biological functions. Depending on their molecular size, ΗΑ forms either promote or attenuate signaling cascades that regulate cancer progression. In order to evaluate the effects of different ΗΑ forms on breast cancer cells' behavior, ΗΑ fragments of defined molecular size were synthesized. Breast cancer cells of different estrogen receptor (ER) status - the low metastatic, ERα-positive MCF-7 epithelial cells and the highly aggressive, ERβ-positive MDA-MB-231 mesenchymal cells - were evaluated following treatment with HA fragments. Scanning electron microscopy revealed that HA fragments critically affect the morphology of breast cancer cells in a molecular-size dependent mode. Moreover, the ΗΑ fragments affect cell functional properties, the expression of major ECM mediators and epithelial-to-mesenchymal transition (ΕΜΤ) markers. Notably, treatment with 200 kDa ΗΑ increased the expression levels of the epithelial marker Ε-cadherin and reduced the expression levels of HA synthase 2 and mesenchymal markers, like fibronectin and snail2/slug. These novel data suggest that the effects of HA in breast cancer cells depend on the molecular size and the ER status. An in-depth understanding on the mechanistic basis of these effects may contribute on the development of novel therapeutic strategies for the pharmacological targeting of aggressive breast cancer.

"Locked" cancer cells are more sensitive to chemotherapy

The treatment of metastatic cancer is a great challenging issue throughout the world. Conventional chemotherapy can kill the cancer cells and, whereas, would exacerbate the metastasis and induce drug resistance. Here, a new combinatorial treatment strategy of metastatic cancer was probed via subsequentially dosing dual nanomedicines, marimastat-loaded thermosensitive liposomes (MATT-LTSLs) and paclitaxel nanocrystals (PTX-Ns), via intravenous and intratumoral injection. First, the metastasis was blocked and cancer cells were locked in the tumor microenvironment (TME) by delivering the matrix metalloproteinase (MMP) inhibitor, MATT, to the tumor with LTSLs, downregulating the MMPs by threefold and reducing the degradation of the extracellular matrix. And then, the "locked" cancer cells were efficiently killed via intratumoral injection of the other cytotoxic nanomedicine, PTX-Ns, along with no metastasis and 100% inhibition of tumor growth. This work highlights the importance of the TME's integrity in the chemotherapy duration. We believe this is a generalized strategy for cancer treatment and has potential guidance for the clinical administration.

Application of nanotechnology to target and exploit tumour associated proteases

Proteases are hydrolytic enzymes fundamental for a variety of physiological processes, but the loss of their regulation leads to aberrant functions that promote onset and progression of many diseases including cancer. Proteases have been implicated in almost every hallmark of cancer and whilst widely investigated for tumour therapy, clinical adoption of protease inhibitors as drugs remains a challenge due to issues such as off-target toxicity and inability to achieve therapeutic doses at the disease site. Now, nanotechnology-based solutions and strategies are emerging to circumvent these issues. In this review, preclinical advances in approaches to enhance the delivery of protease drugs and the exploitation of tumour-derived protease activities to promote targeting of nanomedicine formulations is examined. Whilst this field is still in its infancy, innovations to date suggest that nanomedicine approaches to protease targeting or inhibition may hold much therapeutic and diagnostic potential.

Peritumoral implantation of hydrogel-containing nanoparticles and losartan for enhanced nanoparticle penetration and antitumor effect

Background and purpose

Nanoparticle-loaded hydrogels – localized drug delivery devices containing a combination of therapeutic nanoparticles and implantable hydrogel – have been recipients of increased focus and interest for cancer treatment. However, it is difficult for the released nanoparticles to penetrate deeply into tumors because of the dense collagen network in the tumor extracellular matrix, which greatly limits their antitumor effect. We hypothesized that the implantation of a hydrogel loaded with both nanoparticles and losartan (Los) might enhance penetration because Los has been proven to effectively reduce collagen levels in various tumors. Herein, we developed a nanoparticle/Los-loaded hydrogel system and evaluated the intratumoral distribution and anticancer effect after peritumoral implantation of nanoparticles.

Methods

Fluorescent polystyrene nanoparticles (FPNPs, size ~100 nm) and Los were simultaneously encapsulated in a polyethylene glycol (PEG) hydrogel to form the FPNP/Los-loaded hydrogel. After peritumoral implantation in 4T1 tumor-bearing mice for 2 weeks, intratumoral distributions of FPNPs and collagen level were determined. Based on the results, liposomal doxorubicin (Doxil, ~100 nm) was subsequently substituted for FPNPs in the hydrogel. The cellular uptake and cytotoxicity of the Doxil/Los-loaded hydrogel were studied, and the in vivo antitumor efficacy after peritumoral implantation was evaluated.

Results

Compared with a standard FPNP-loaded hydrogel, the FPNP/Los-loaded hydrogel resulted in enhanced penetration and reduced collagen levels after implantation. Thereafter, the potential of a Doxil/Los-loaded hydrogel for cancer treatment was studied. Doxorubicin was released from the hydrogel and induced effective cytotoxicity against 4T1 cells. The Doxil/Los-loaded hydrogel showed synergistic antitumor effects in 4T1 tumor-bearing mice and was more effective at tumor inhibition than the Doxil-loaded hydrogel.

Conclusion

This study provides a proof of principle that the implantation of nanoparticles/Los-loaded hydrogel can increase the intratumoral distribution and antitumor efficacy of nanoparticles, owing to collagen depletion by Los. Future studies may build on this strategy for enhanced tumor penetration of nanoparticles.

A drug-delivering-drug strategy for combined treatment of metastatic breast cancer

Treatment of metastatic cancer continues to be a huge challenge worldwide. Notably, drug nanocrystals (Ns) in nanosuspensions clearly belong to a type of nanoparticle. Therefore, a question arose as to whether these drug particles can also be applied as carriers for drug delivery. Here, we design a novel paclitaxel (PTX) nanocrystal stabilized with complexes of matrix metalloproteinase (MMP)-sensitive β-casein/marimastat (MATT) for co-delivering MATT and PTX and combined therapy of metastatic breast cancer. The prepared Ns (200 nm) with a drug-loading of >50% were potent in treatment of metastatic cancer, which markedly inhibited MMP expression and activity and greatly blocked the lung metastasis and angiogenesis. In conclusion, employing protein-drug complexes as stabilizers, Ns with dual payloads are developed and are a promising strategy for co-delivery. Furthermore, the developed Ns can target the tumor microenvironment and cancer cells and, as a result, enable efficient treatment for breast metastatic cancer.

Downregulations of AKT/mTOR Signaling Pathway for Salmonella-Mediated Suppression of Matrix Metalloproteinases-9 Expression in Mouse Tumor Models

The roles of Matrix MetalloProteinases (MMPs), such as MMP-9, in tumor metastasis are well studied, and this in turns stimulates the development of MMP inhibitors as antitumor agents. Previously, Salmonella accumulation was observed in the metastatic nodules of the lungs after systemic administration. Salmonella significantly enhanced the survival of the pulmonary metastatic tumor-bearing mice. Based on our previous observation, we hypothesized that Salmonella could affect metastasis-related protein expression. The treatment of Salmonella clearly reduced the expression of MMP-9. Meanwhile, the MMP-9 related signaling pathways, including Phosph-Protein Kinase B (P-AKT) and Phosph-mammalian Targets Of Rapamycin (P-mTOR) were decreased after a Salmonella treatment. The Salmonella inhibited tumor cell migration by wound-healing and Transwell assay. The anti-metastatic effects of Salmonella were evaluated in mice bearing experimental metastasis tumor models. Consequently, Salmonella inhibited the expression of MMP-9 by reducing the AKT/mTOR pathway and metastatic nodules in vivo.