Inhibition of Cysteine Cathepsin Protease Activity Enhances Chemotherapy Regimens by Decreasing Tumor Growth and Invasiveness in a Mouse Model of Multistage Cancer

Cancer Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Cancer Research (Impact Factor: 9.33). 09/2007; 67(15):7378-85. DOI: 10.1158/0008-5472.CAN-07-0602
Source: PubMed


Increases in protease expression and activity are associated with malignant progression and poor patient prognosis in a number of human cancers. Members of the papain family of cysteine cathepsins are among the protease classes that have been functionally implicated in cancer. Inhibition of the cysteine cathepsin family using a pan-cathepsin inhibitor, JPM-OEt, led to tumor regression in the RIP1-Tag2 (RT2) mouse model of pancreatic islet cell tumorigenesis. The present study was designed to determine whether this cathepsin inhibitor, when used in combination with chemotherapy, would increase antitumor efficacy. RT2 mice were treated in a late-stage regression trial with three different chemotherapy regimens, alone or in combination with the cathepsin inhibitor, JPM-OEt. Cyclophosphamide was administered in either a maximum tolerated dose (MTD) regimen, a "metronomic" continuous low-dose regimen, or a "chemo-switch" regimen consisting of MTD followed by metronomic dosing. Mice were sacrificed at a defined end point and tumor burden was assessed followed by a detailed analysis of cell proliferation, apoptosis, vascularization, and invasiveness in the treated and control lesions. An additional cohort of mice was followed for survival analysis. The cathepsin inhibitor plus the chemo-switch regimen of cyclophosphamide led to the most pronounced reduction in tumor burden and greatest increase in overall survival. Cysteine cathepsin inhibition resulted in a significant decrease in tumor invasiveness, which was further augmented in combination with each of the chemotherapy dosing regimens. These results encourage the development and continuing evaluation of cysteine cathepsin inhibitors as cancer therapeutics.

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    • "The first study on the use of the broad-spectrum small molecule cysteine cathepsin inhibitor, JPM-OEt, in the Rip1-Tag2 pancreatic islet cells cancer mouse model demonstrated significant anti-tumor efficacy in three distinctive trial designs: prevention, intervention, and regression (Joyce et al., 2004), that target different stages in tumorigenesis (Bergers et al., 1999). Furthermore, combination of cathepsin inhibition with two distinct regimens of chemotherapy administration (MTD or chemo-switch) was shown to lead to a more pronounced tumor regression, decreased tumor invasiveness, and increased survival in the Rip1-Tag2 model (Bell-McGuinn et al., 2007). However, there might be some limitations for the use of small synthetic probes in the clinic, primarily because of their pharmacokinetic properties, such as relatively short circulation half-life and poor bioavailability, due to the rapid conversion of the injected cell permeable ethyl esters, e.g., JPM-OEt, to its corresponding acid in the serum (Sadaghiani et al., 2007). "
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    ABSTRACT: Lysosomal cysteine cathepsins belong to a family of 11 human proteolytic enzymes. Some of them correlate with progression in a variety of cancers and therefore are considered as potential therapeutic targets. Until recently, the contribution of individual cathepsins to tumorigenesis and tumor progression remained unknown. By crossing various types of mouse cancer models with mice where specific cathepsins have been ablated, we contributed to this gap of knowledge and will summarize the results in this report. The employed models are the Rip1-Tag2 model for pancreatic neuroendocrine tumors, the K14-HPV16 model for squamous skin and cervical cancers, and the MMTV-PyMT model for metastasizing breast cancer, the KPC model for pancreatic ductal adenocarcinoma, and the APCmin mice developing early stages of intestinal neoplasia. All models harbor mutations in relevant tumor suppressors and/or cell-type specific expression of potent oncogenes, which initiate de novo carcinogenesis in the targeted tissues. In all these models deletion of cathepsin B led to suppression of the aggressiveness of the respective cancer phenotype. Cathepsin B may network with other proteases as it was shown for cathepsin X/Z. In contrast, deletion of cathepsin L was beneficial in the RiP1-Tag2 model, but enhanced tumorigenesis in the APCmin, and the K14-HPV16 mice. A logical consequence of these results would be to further pursue selective inhibition of cathepsin B. Moreover, it became clear that cathepsins B and S derived from cells of the tumor microenvironment support cancer growth. Strikingly, delivery of broad spectrum cysteine cathepsin inhibitors in the tumor microenvironment disrupts the permissive ecosystem of the cancer and results in impaired growth or even in regression of the tumor. In addition, combination of cysteine cathepsin inhibition and standard chemotherapy improves the therapeutic response of the latter.
    Frontiers in Pharmacology 07/2012; 3:133. DOI:10.3389/fphar.2012.00133 · 3.80 Impact Factor
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    • "Cathepsins are potent degradative enzymes whose normal restricted proteolytic activity is altered by neoplastic cells resulting in secretion into the tumour microenvironment and cleavage of ECM component proteins (Obermajer et al, 2008). This ECM remodelling in turn facilitates tumour growth, angiogenesis, invasion and metastasis (Joyce et al, 2004; Gocheva et al, 2006; Bell-McGuinn et al, 2007). Cathepsins have been shown to be upregulated and aberrantly expressed and linked with prognosis in several cancers (Foekens et al, 1998; Mohamed and Sloane, 2006). "
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    ABSTRACT: The aim of this pilot retrospective study was to investigate the immunohistochemical expression of Cathepsin S (CatS) in three cohorts of colorectal cancer (CRC) patients (n=560). Prevalence and association with histopathological variables were assessed across all cohorts. Association with clinical outcomes was investigated in the Northern Ireland Adjuvant Chemotherapy Trial cohort (n=211), where stage II/III CRC patients were randomised between surgery-alone or surgery with adjuvant fluorouracil/folinic acid (FU/FA) treatment. Greater than 95% of tumours had detectable CatS expression with significantly increased staining in tumours compared with matched normal colon (P>0.001). Increasing CatS was associated with reduced recurrence-free survival (RFS; P=0.03) among patients treated with surgery alone. Adjuvant FU/FA significantly improved RFS (hazard ratio (HR), 0.33; 95% CI, 0.12-0.89) and overall survival (OS; HR, 0.25; 95% CI, 0.08-0.81) among 36 patients with high CatS. Treatment did not benefit the 66 patients with low CatS, with a RFS HR of 1.34 (95% CI, 0.60-3.19) and OS HR of 1.33 (95% CI, 0.56-3.15). Interaction between CatS and treatment status was significant for RFS (P=0.02) and OS (P=0.04) in a multivariate model adjusted for known prognostic markers. These results signify that CatS may be an important prognostic biomarker and predictive of response to adjuvant FU/FA in CRC.
    British Journal of Cancer 11/2011; 105(10):1487-94. DOI:10.1038/bjc.2011.408 · 4.84 Impact Factor
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    • "Further potential combination treatment strategies using Fsn0503 may be considered in the light of these results. Previously, the application of a broad spectrum experimental cathepsin probe, JPM-OEt, has been used with chemotherapy to further enhance efficacy of treatment [26]. Therefore the combination of a clinically applicable inhibitor such as Fsn0503 and chemotherapies may produce similar synergistic effects to the drug combinations that have been used here, particularly in inhibiting the spread of invasive and malignant tumours. "
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    ABSTRACT: Angiogenesis is a key hallmark of tumourigenesis and its inhibition is a proven strategy for the development of novel anti-cancer therapeutics. An important aspect of early angiogenesis is the co-ordinated migration and invasion of endothelial cells through the hypoxic tumour tissue. Cathepsin S has been shown to play an important role in angiogenesis as has vascular endothelial growth factor (VEGF). We sought to assess the anti-angiogenic effect of Fsn0503, a novel cathepsin S inhibitory antibody, when combined with anti-VEGF on vascular development. Cathepsin S expression and secretion from endothelial cells was characterised using RT-PCR and western blotting. We further show that cathepsin S promotes pericellular hydrolysis of extracellular matrix components in the tumour microenvironment and facilitates endothelial invasion. The cathepsin S inhibitory antibody, Fsn0503, blocks extracellular proteolysis, inhibiting endothelial invasion and tube formation in cell-based assays. The anti-angiogenic effects of Fsn0503 were also shown in vivo where it significantly retarded the development of vasculature in human xenograft models. Furthermore, when Fsn0503 was combined with an anti-VEGF antibody, a synergistic inhibition of microvascular development was observed. Taken together, this data demonstrates that the antibody-mediated targeting of cathepsin S represents a novel method of inhibiting angiogenesis. Furthermore, when used in combination with anti-VEGF therapies, Fsn0503 has the potential to significantly enhance current treatments of tumour neovascularisation and may also be of use in the treatment of other conditions associated with inappropriate angiogenesis.
    PLoS ONE 09/2010; 5(9). DOI:10.1371/journal.pone.0012543 · 3.23 Impact Factor
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