Matrix metalloproteinases and their role in pancreatic cancer: a review of preclinical studies and clinical trials

Chemotherapy Assessment in Advanced Multicellular 3D Models of Pancreatic Cancer: Unravelling the Importance of Spatiotemporal Mimicry of the Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a challenge for global health with very low survival rate and high therapeutic resistance. Hence, advanced preclinical models for treatment screening are of paramount importance. Herein, chemotherapeutic (gemcitabine) assessment on novel (polyurethane) scaffold-based spatially advanced 3D multicellular PDAC models is carried out. Through comprehensive image-based analysis at the protein level, and expression analysis at the mRNA level, the importance of stromal cells is confirmed, primarily activated stellate cells in the chemoresistance of PDAC cells within the models. Furthermore, it is demonstrated that, in addition to the presence of activated stellate cells, the spatial architecture of the scaffolds, i.e., segregation/compartmentalization of the cancer and stromal zones, affect the cellular evolution and is necessary for the development of chemoresistance. These results highlight that, further to multicellularity, mapping the tumor structure/architecture and zonal complexity in 3D cancer models is important for better mimicry of the in vivo therapeutic response.

Nab-Paclitaxel in the Treatment of Gastrointestinal Cancers-Improvements in Clinical Efficacy and Safety

Taxanes (paclitaxel and docetaxel) are one of the most useful classes of anticancer drugs. Taxanes are highly hydrophobic; therefore, these drugs must be dissolved in organic solvents (polysorbate or Cremophor EL), which contribute to their toxicities. To reduce this toxicity and to enhance their efficacy, novel formulations have been developed. Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) is an albumin-stabilized, Cremophor-free, and water-soluble nanoparticle formulation of paclitaxel. Nab-paclitaxel has better solubility and less infusion-associated toxicity compared to solvent-based paclitaxel. Additionally, nab-paclitaxel can be given at higher doses and concentrations compared with solvent-based paclitaxel. Based on its superior clinical efficacy and safety profile, nab-paclitaxel received FDA approval for metastatic breast cancer (2008) and NSCLC (2011). Among gastrointestinal cancers, it is now approved in the USA for treating patients with metastatic adenocarcinoma of the pancreas as first-line therapy in combination with gemcitabine. Furthermore, several clinical trials have suggested the potential efficacy of nab-paclitaxel as a single agent or in combination with other agents for the treatment of metastatic esophageal, gastric, bowel, and biliary tract cancers. Nab-paclitaxel has been demonstrated to have greater overall response rates (ORR) with enhanced progression-free survival (PFS), overall survival (OS) and a superior safety profile with fewer adverse effects in patients with gastrointestinal tract cancers. This review summarizes the advantages associated with nab-paclitaxel-based regimens in terms of improving clinical efficacy and the safety profile in upper gastrointestinal cancer.

Genomic and immunogenomic analysis of three prognostic signature genes in LUAD

BACKGROUND

Searching for immunotherapy-related markers is an important research content to screen for target populations suitable for immunotherapy. Prognosis-related genes in early stage lung cancer may also affect the tumor immune microenvironment, which in turn affects immunotherapy.

RESULTS

We analyzed the differential genes affecting lung cancer patients receiving immunotherapy through the Cancer Treatment Response gene signature DataBase (CTR-DB), and set a threshold to obtain a total of 176 differential genes between response and non-response to immunotherapy. Functional enrichment analysis found that these differential genes were mainly involved in immune regulation-related pathways. The early-stage lung adenocarcinoma (LUAD) prognostic model was constructed through the cancer genome atlas (TCGA) database, and three target genes (MMP12, NFE2, HOXC8) were screened to calculate the risk score of early-stage LUAD. The receiver operating characteristic (ROC) curve indicated that the model had good prognostic value, and the validation set (GSE50081, GSE11969 and GSE42127) from the gene expression omnibus (GEO) analysis indicated that the model had good stability, and the risk score was correlated with immune infiltrations to varying degrees. Multi-type survival analysis and immune infiltration analysis revealed that the transcriptome, methylation and the copy number variation (CNV) levels of the three genes were correlated with patient prognosis and some tumor microenvironment (TME) components. Drug sensitivity analysis found that the three genes may affect some anti-tumor drugs. The mRNA expression of immune checkpoint-related genes showed significant differences between the high and low group of the three genes, and there may be a mutual regulatory network between immune checkpoint-related genes and target genes. Tumor immune dysfunction and exclusion (TIDE) analysis found that three genes were associated with immunotherapy response and maybe the potential predictors to immunotherapy, consistent with the CTR-DB database analysis.

CONCLUSIONS

From the perspective of data mining, this study suggests that MMP12, NFE2, and HOXC8 may be involved in tumor immune regulation and affect immunotherapy. They are expected to become markers of immunotherapy and are worthy of further experimental research.

The Role of ECM Remodeling, EMT, and Adhesion Molecules in Cancerous Neural Invasion: Changing Perspectives

Perineural invasion (PNI) refers to the cancerous invasion of nerves. It provides an alternative route for metastatic invasion and can exist independently in the absence of lymphatic or vascular invasion. It is a prominent characteristic of specific aggressive malignancies where it correlates with poor prognosis. The clinical significance of PNI is widely recognized despite a lack of understanding of the molecular mechanisms underlying its pathogenesis. The interaction between the nerve and the cancer cells is the most pivotal PNI step which is mediated by the activation or inhibition of multiple signaling pathways that include chemokines, interleukins, nerve growth factors, and matrix metalloproteinases, to name a few. The nerve-cancer cell interaction brings about specific changes in the perineural niche, which not only affects the regular nerve functions, but also enhances the migratory, invasive, and adherent properties of the tumor cells. This review aims to elucidate the vital role of adhesion molecules, extracellular matrix, and epithelial-mesenchymal proteins that promote PNI, which may serve as therapeutic targets in the future.

Identification of potential biomarkers for digestive system cancers from serum-derived extracellular vesicle RNA

BACKGROUND

Poor prognosis of digestive system cancers is mainly owing to lack of accurate and timely diagnosis. The exploration of novel tumor biomarkers from extracellular vesicle (EV) might be helpful to clinical diagnosis for digestive system cancers.

METHODS

Several public databases were first used for a preliminary screening of candidate genes. The RNA levels of these candidate genes were then detected in cancer cell lines and the patients serum-derived EVs by PCR Array or digital PCR, respectively.

RESULTS

We found that 4 EV-RNAs, ANLN, ITGA6, KRT18, and MMP9, had a lower level in gastrointestinal cancer patients than in benign gastrointestinal diseases patients and healthy controls, while 3 EV-RNAs, ANLN, ITGA6, and KRT18, had a lower level in pancreatic cancer patients than in benign pancreatic diseases patients or healthy individuals. And EV-RNA of MMP9 had a relatively higher level in advanced pancreatic cancer patients than in early-stage patients. Moreover, ROC analysis demonstrated that the determination of the above EV-RNAs could increase the ability of traditional tumor biomarkers to distinguish benign and malignant diseases.

CONCLUSIONS

The serum-derived EV-RNAs of ANLN, ITGA6, KRT18, and MMP9 could be served as novel, non-invasive biomarkers for digestive system cancers.

Emerging Albumin-Binding Anticancer Drugs for Tumor-Targeted Drug Delivery: Current Understandings and Clinical Translation

Albumin has shown remarkable promise as a natural drug carrier by improving pharmacokinetic (PK) profiles of anticancer drugs for tumor-targeted delivery. The exogenous or endogenous albumin enhances the circulatory half-lives of anticancer drugs and passively target the tumors by the enhanced permeability and retention (EPR) effect. Thus, the albumin-based drug delivery leads to a potent antitumor efficacy in various preclinical models, and several candidates have been evaluated clinically. The most successful example is Abraxane, an exogenous human serum albumin (HSA)-bound paclitaxel formulation approved by the FDA and used to treat locally advanced or metastatic tumors. However, additional clinical translation of exogenous albumin formulations has not been approved to date because of their unexpectedly low delivery efficiency, which can increase the risk of systemic toxicity. To overcome these limitations, several prodrugs binding endogenous albumin covalently have been investigated owing to distinct advantages for a safe and more effective drug delivery. In this review, we give account of the different albumin-based drug delivery systems, from laboratory investigations to clinical applications, and their potential challenges, and the outlook for clinical translation is discussed. In addition, recent advances and progress of albumin-binding drugs to move more closely to the clinical settings are outlined.

Ruthenium(ii)-arene complexes as anti-metastatic agents, and related techniques

With the discovery of cisplatin, a vast area of applications of metallodrugs in cancer treatment was opened but due to the side effects caused by the cisplatin complexes, researchers began to look for alternatives with similar anticancer properties but fewer side effects. Ruthenium was found to be a promising candidate, considering its significant anticancer properties and low side effects. Several ruthenium complexes, viz. NAMI-A, KP1019, KP1339, and TLD1433, have entered clinical trials. Some other arene ruthenium complexes such as RM175 and RAPTA-C have also entered clinical trials but very few of them have shown anti-metastatic properties. Herein, we provide information and probable mechanistic pathways for ruthenium(ii)-arene complexes that have been studied, so far, for their anti-metastatic activities. Also, we discuss the techniques and their significance for determining the anti-metastatic effects of the complexes.

Establishment of Pancreatobiliary Cancer Zebrafish Avatars for Chemotherapy Screening

Background: Cancers of the pancreas and biliary tree remain one of the most aggressive oncological malignancies, with most patients relying on systemic chemotherapy. However, effective biomarkers to predict the best therapy option for each patient are still lacking. In this context, an assay able to evaluate individual responses prior to treatment would be of great value for clinical decisions. Here we aimed to develop such a model using zebrafish xenografts to directly challenge pancreatic cancer cells to the available chemotherapies. Methods: Zebrafish xenografts were generated from a Panc-1 cell line to optimize the pancreatic setting. Pancreatic surgical resected samples, without in vitro expansion, were used to establish zebrafish patient-derived xenografts (zAvatars). Upon chemotherapy exposure, zAvatars were analyzed by single-cell confocal microscopy. Results: We show that Panc-1 zebrafish xenografts are able to reveal tumor responses to both FOLFIRINOX and gemcitabine plus nanoparticle albumin-bound (nab)-paclitaxel in just 4 days. Moreover, we established pancreatic and ampullary zAvatars with patient-derived tumors representative of different histological types. Conclusion: Altogether, we provide a short report showing the feasibility of generating and analyzing with single-cell resolution zAvatars from pancreatic and ampullary cancers, with potential use for future preclinical studies and personalized treatment.

Biomarkers in Pancreatic Cancer as Analytic Targets for Nanomediated Imaging and Therapy

As the increase in therapeutic and imaging technologies is swiftly improving survival chances for cancer patients, pancreatic cancer (PC) still has a grim prognosis and a rising incidence. Practically everything distinguishing for this type of malignancy makes it challenging to treat: no approved method for early detection, extended asymptomatic state, limited treatment options, poor chemotherapy response and dense tumor stroma that impedes drug delivery. We provide a narrative review of our main findings in the field of nanoparticle directed treatment for PC, with a focus on biomarker targeted delivery. By reducing drug toxicity, increasing their tumor accumulation, ability to modulate tumor microenvironment and even improve imaging contrast, it seems that nanotechnology may one day give hope for better outcome in pancreatic cancer. Further conjugating nanoparticles with biomarkers that are overexpressed amplifies the benefits mentioned, with potential increase in survival and treatment response.

Synergistic metalloproteinase-based remodeling of matrix by pancreatic tumor and stromal cells

The process by which tumor cells mechanically invade through the surrounding stroma into peripheral tissues is an essential component of metastatic dissemination. Matrix metalloproteinase (MMP)-mediated extracellular matrix (ECM) degradation plays an important role in this invasive process. Defining the contribution and interaction between these MMPs during invasion remains a key interest in the development of targeted anti-metastatic therapies. In this study we have utilized multiple different stromal fibroblasts and tumor cells to define the relative contributions between cancer cells and stromal cells during MMP-dependent matrix remodeling and pancreatic (PDAC) tumor cell invasion. We find that tumor cells co-cultured with the conditioned medium from stromal fibroblasts exhibited a substantial increase in invadopodial-based matrix degradation and transwell invasion. This increase is dependent on pro-MMP2 expressed and secreted by stromal fibroblasts. Further, the pro-MMP2 from the stromal fibroblasts is activated by MT1-MMP expressed on the tumor cells. Depletion of MT1-MMP, the known activator of MMP2, in tumor cells largely blocked matrix remodeling, even in the presence of stromal cell medium. In summary, these findings implicate an important interplay between MT1-MMP from tumor cells and MMP2 from fibroblasts as a key component for ECM remodeling and invasion.

Polyvinyl alcohol increased growth, migration, invasion, and sphere size in the PK-8 pancreatic ductal adenocarcinoma cell line

Polyvinyl alcohol (PVA) is a water-soluble synthetic polymer used in eye drops, embolization particles, and artificial cartilage. It has also been shown to cause expansion of functional multipotent self-renewing hematopoietic stem cells under serum-free conditions. In this study, we examined the effects of PVA on human pancreatic ductal adenocarcinoma (PDAC) cell lines using 2-dimensional (2D) and 3D-cultures with serum-free medium. In the 2D-culture, PVA-treatment induced an aggregated colony-like appearance in PDAC cells. It increased the growth of PK-8 cells in a dose-dependent manner as well as significantly increasing migration and invasion abilities. qRT-PCR showed an increase in α2 integrin and a decrease in matrix metalloprotease levels in PVA-treated PK-8 cells. Through qRT-PCR analysis, β1 integrin expression at the mRNA level was found to be decreased; however, it was unaltered at the protein level when assessed using FACS analysis. PVA further induced mesenchymal to epithelial transition-like alterations, including increased E-cadherin and decreased Vimentin and N-cadherin expression. Four cancer stem cell (CSC) markers were higher in PVA-treated PK-8 cells compared to controls. In 3D-culture, PVA-treated PK-8 cells showed a rod-like appearance with larger sphere size and higher growth ability. qRT-PCR showed that CSC markers did not increase and 2 of 4 drug transporters had decreased in PVA-treated PK-8 cells. These findings suggest that PVA increases the growth, migration, invasion, and sphere size of PK-8 cells, but does not increase the proportion of pancreatic CSCs under 3D-culture conditions with serum-free medium.

Enhancement of Pancreatic Cancer Therapy Efficacy by Type-1 Matrix Metalloproteinase-Functionalized Nanoparticles for the Selective Delivery of Gemcitabine and Erlotinib

Purpose

Pancreatic cancer (PCa) is projected to become the second leading cause of cancer-related deaths by 2030. Gemcitabine (GEM) combined with erlotinib (ERL) have been approved by the FDA for locally advanced, unresectable or metastatic pancreatic cancer therapy since 2005. Type-1 matrix metalloproteinase (MT1-MMP) has been recognized as a critical mediator of several steps in PCa progression including activating TGF-β or releasing latent TGF-β from LTBP-1, resulting in increased collagen production and cleavage collagen.

Methods

In the present research, GEM and ERL co-loaded nanoparticles (GEM/ERL NPs) were prepared. A non-substrate MT1-MMP binding peptide was decorated onto the GEM/ERL NPs surface.

Results

M-M GEM/ERL NPs exhibited the highest uptake ability (67.65 ± 2.87%), longest half-life period, largest area under the curve, and the best tumor inhibition efficiency (69.81 ± 4.13%). The body weight, blood urine nitrogen (BUN), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) of the system were steady when tested in mice model.

Conclusion

In conclusion, M-M GEM/ERL NPs protected the drugs in the plasma, improved cellular uptake capacity, exhibited the most remarkable tumor cell inhibition ability, and showed the most efficient tumor growth inhibition capacity in vivo. M-M GEM/ERL NPs could be applied as an efficient and safe system for the synergistic combination chemotherapy of PCa.

α2A-Adrenergic Receptor Inhibits the Progression of Cervical Cancer Through Blocking PI3K/AKT/mTOR Pathway

Objective

The study aimed to investigate the effect of α2A-adrenergic receptor (ADRA2A) on cervical cancer and the potential mechanisms of ADRA2A on phosphatidylinositol 3′-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway in cervical cancer cells.

Methods

In our study, ADRA2A expression was evaluated by analyzing cervical cancer RNA sequencing dataset from the GEPIA. The prognostic values of ADRA2A were evaluated by Kaplan–Meier method using the Cancer Genome Atlas (TCGA) database data. In addition, the expression of ADRA2A in cervical cancer cell lines was detected by qRT-PCR and Western blot. Subsequently, the roles of ADRA2A on cell proliferation, apoptosis, migration, invasion and senescence in HeLa and SiHa cells were evaluated. Moreover, tumorigenesis in nude mice was used to investigate the role of ADRA2A in vivo. We also detected the expression changes of key factors in PI3K/Akt/mTOR pathway after overexpression and silencing of ADRA2A in HeLa and SiHa cells.

Results

ADRA2A expression was significantly downregulated in cervical cancer tissues and cell lines. The high expression of ADRA2A was significantly associated with a better prognosis in cervical cancer patients. ADRA2A overexpression significantly suppressed cell proliferation, migration and invasion, and promoted cell senescence and apoptosis in cervical cancer cells. On the contrary, silencing ADRA2A dramatically facilitated cell proliferation, migration and invasion, and inhibited cell senescence and apoptosis in cervical cancer cells. The expressions of p-PI3K, p-AKT and p-mTOR in cervical cancer cells were notably decreased by ADRA2A overexpression and increased by silencing ADRA2A. In addition, we also confirmed that ADRA2A overexpression could suppress the xenograft tumor growth in vivo.

Conclusion

Our study demonstrated that ADRA2A could suppress cell proliferation, migration and invasion, as well as promote cell senescence and apoptosis through inhibiting PI3K/Akt/mTOR pathway in cervical cancer.

Bioinformatics and Molecular Insights to Anti-Metastasis Activity of Triethylene Glycol Derivatives

The anti-metastatic and anti-angiogenic activities of triethylene glycol derivatives have been reported. In this study, we investigated their molecular mechanism(s) using bioinformatics and experimental tools. By molecular dynamics analysis, we found that (i) triethylene glycol dimethacrylate (TD-10) and tetraethylene glycol dimethacrylate (TD-11) can act as inhibitors of the catalytic domain of matrix metalloproteinases (MMP-2, MMP-7 and MMP-9) by binding to the S1’ pocket of MMP-2 and MMP-9 and the catalytic Zn ion binding site of MMP-7, and that (ii) TD-11 can cause local disruption of the secondary structure of vascular endothelial growth factor A (VEGFA) dimer and exhibit stable interaction at the binding interface of VEGFA receptor R1 complex. Cell-culture-based in vitro experiments showed anti-metastatic phenotypes as seen in migration and invasion assays in cancer cells by both TD-10 and TD-11. Underlying biochemical evidence revealed downregulation of VEGF and MMPs at the protein level; MMP-9 was also downregulated at the transcriptional level. By molecular analyses, we demonstrate that TD-10 and TD-11 target stress chaperone mortalin at the transcription and translational level, yielding decreased expression of vimentin, fibronectin and hnRNP-K, and increase in extracellular matrix (ECM) proteins (collagen IV and E-cadherin) endorsing reversal of epithelial–mesenchymal transition (EMT) signaling.

Recent insights into natural product inhibitors of matrix metalloproteinases

Members of the matrix metalloproteinase (MMP) family have biological functions that are central to human health and disease, and MMP inhibitors have been investigated for the treatment of cardiovascular disease, cancer and neurodegenerative disorders. The outcomes of initial clinical trials with the first generation of MMP inhibitors proved disappointing. However, our growing understanding of the complexities of the MMP function in disease, and an increased understanding of MMP protein architecture and control of activity now provide new opportunities and avenues to develop MMP-focused therapies. Natural products that affect MMP activities have been of strong interest as templates for drug discovery, and for their use as chemical tools to help delineate the roles of MMPs that still remain to be defined. Herein, we highlight the most recent discoveries of structurally diverse natural product inhibitors to these proteases.

Leptin receptor mediates the proliferation and glucose metabolism of pancreatic cancer cells via AKT pathway activation

Pancreatic cancer (PC) is the fourth leading cause of cancer‑related mortality worldwide. Leptin is an adipokine that is significantly increased in obese patients and that functions in various biological processes of cancer, such as tumor growth and metastasis. However, its role in PC cell proliferation and glucose metabolism and the underlying mechanisms remain unclear. In the present study, in vitro leptin treatment significantly promoted cell proliferation and increased glucose uptake and lactate production of human PC and healthy pancreas cells in a dose‑dependent manner, accompanied by increased expression of the glycolytic enzymes hexokinase II and glucose transporter 1. Furthermore, leptin receptor‑specific short hairpin RNAs were used to silence leptin receptor expression in PC cells, which had the opposite effect to leptin stimulation and decreased AKT phosphorylation. In addition, the effects of leptin stimulation were significantly counteracted by the AKT inhibitor LY294002, whereas the effects of leptin silencing were counteracted by AKT activator insulin‑like growth factor 1. The results of the present study suggested that leptin may contribute to cell proliferation and glucose metabolism of human PC cells, which may be through activation of the AKT pathway.

Identification of potential hub genes associated with the pathogenesis and prognosis of pancreatic duct adenocarcinoma using bioinformatics meta-analysis of multi-platform datasets

Pancreatic duct adenocarcinoma (PDAC) is a highly malignant type of cancer with a low five-year survival rate. Gene alterations are crucial to the molecular pathogenesis of PDAC. Therefore, the present study analyzed gene expression profiles to reveal genes involved in the tumorigenesis of PDAC. A total of eight gene expression profiles (GSE15471, GSE16515, GSE41368, GSE62165, GSE62452, GSE71729, GSE71989 and GSE91035) and a PDAC dataset were acquired from the Gene Expression Omnibus and The Cancer Genome Atlas (TCGA) database, respectively. Differentially expressed genes (DEGs) were screened using functional annotation, Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and protein-protein interaction (PPI) network construction. A Cox proportional hazards model was then constructed and used to analyze the data. A total of 136 DEGs (67 up- and 69 downregulated genes) were identified between PDAC tissues and normal tissues. The ‘extracellular matrix-related’ genes were the most enriched in the GO term analysis. ‘Pancreatic secretion’, ‘phosphoinositide-3-kinase–protein kinase B/Akt (PI3K-Akt) signaling pathway’, ‘protein digestion and absorption’ and ‘ECM-receptor interaction’ were the most enriched categories in KEGG pathway analysis. Following PPI network construction, the 10 most significant genes [albumin, epidermal growth factor, matrix metalloproteinase (MMP) 9, epidermal growth factor receptor, fibronectin 1, MMP1, plasminogen activator inhibitor-1, tissue inhibitor of metalloproteinase 1, plasminogen activator urokinase (PLAU) and PLAU receptor) exhibiting a high degree of connectivity, were identified as the hub genes likely to be associated with the pathogenesis of PDAC. In addition, a prognostic predictive system for PDAC, composed of five genes (laminin subunit γ 2, laminin subunit β 3, serpin family B member 5, amphiregulin and secreted frizzled related protein 4), was constructed. This was validated in the GSE62452 dataset (using 66 PDAC samples with outcome data) and TCGA PDAC dataset (using 146 PDAC samples with outcome data). In conclusion, the present study revealed potential hub genes involved in PDAC progression, providing directive significance for individualized clinical decision-making and molecular-targeting therapy in patients with PDAC.

The Rebirth of Matrix Metalloproteinase Inhibitors: Moving Beyond the Dogma

The pursuit of matrix metalloproteinase (MMP) inhibitors began in earnest over three decades ago. Initial clinical trials were disappointing, resulting in a negative view of MMPs as therapeutic targets. As a better understanding of MMP biology and inhibitor pharmacokinetic properties emerged, it became clear that initial MMP inhibitor clinical trials were held prematurely. Further complicating matters were problematic conclusions drawn from animal model studies. The most recent generation of MMP inhibitors have desirable selectivities and improved pharmacokinetics, resulting in improved toxicity profiles. Application of selective MMP inhibitors led to the conclusion that MMP-2, MMP-9, MMP-13, and MT1-MMP are not involved in musculoskeletal syndrome, a common side effect observed with broad spectrum MMP inhibitors. Specific activities within a single MMP can now be inhibited. Better definition of the roles of MMPs in immunological responses and inflammation will help inform clinic trials, and multiple studies indicate that modulating MMP activity can improve immunotherapy. There is a U.S. Food and Drug Administration (FDA)-approved MMP inhibitor for periodontal disease, and several MMP inhibitors are in clinic trials, targeting a variety of maladies including gastric cancer, diabetic foot ulcers, and multiple sclerosis. It is clearly time to move on from the dogma of viewing MMP inhibition as intractable.

MoS2 Field-Effect Transistor-Amyloid-β1-42 Hybrid Device for Signal Amplified Detection of MMP-9

The detection of circulating protein (CP) is very important for the diagnosis and therapeutics of cancer. Conventional techniques based on a specific antibody-antigen interaction are still lacking because of a shortage of cost effectiveness, complicated sandwich structure and tagging process, and inconsistent detection of CP due to the inherent instability of antibodies. Herein, we demonstrate a hybrid device consisting of two-dimensional (2D) nanoscale molybdenum disulfide (MoS₂) field-effect transistor (FET) with an amyloid-β_1-42 (Aβ_1-42) functionalized surface, which amplifies electric signals of the FET in order to detect matrix metalloproteinase-9 (MMP-9), which is a certain type of CP that degrades Aβ_1-42. With the hybrid device, we detected the concentrations of MMP-9 in the range from 1 pM to 10 nM. Moreover, using tapping-mode atomic force microscopy and Kelvin probe force microscopy, we verified that the signal amplification corresponding to the MMP-9 concentrations was caused by the reduced length and the decreased surface potential of degraded Aβ_1-42 due to MMP-9. The hybrid device studied in this paper can be very useful for monitoring MMP-9 activity, as well as serving as a sensing platform for the electrical signal amplification of 2D MoS₂ FET-biosensors.

Aberrant expression of PDZ-binding kinase/T-LAK cell-originated protein kinase modulates the invasive ability of human pancreatic cancer cells via the stabilization of oncoprotein c-MYC

High frequency of mortality in patients with pancreatic ductal adenocarcinoma (PDAC) is vastly associated with the invasive and metastatic nature of these cancer cells. Little is known about the factors involved in this invasive/metastatic process. The current challenge in the treatment of these patients is the lack of viable options besides gemcitabine. The aim of this study was to evaluate the role of PDZ-binding kinase (PBK)/T-LAK cell-originated protein kinase (TOPK) in invasive PDAC cells and to determine whether PBK/TOPK expression drives invasiveness in PDAC. Using gain-of-function and loss-of-function studies in established and patient-derived xenograft-PDAC cell lines, and examining patient-derived archival tissue samples, we demonstrate for the first time that PBK/TOPK is upregulated in pancreatic cancer and expression levels are closely associated with the invasive property of pancreatic cancer cells. Modulation of PBK/TOPK causally regulates the invasive ability of PDAC cells. We also demonstrate that two key players in metastatic invasion, matrix metalloproteinases-2 (MMP-2) and MMP-9 gelatinase activity and gene promoter activities, are regulated by PBK/TOPK. Moreover, we demonstrate for the first time that PBK/TOPK provides stability of an oncoprotein, c-MYC, which transcriptionally regulates MMP-2 and MMP-9 in these invasive PDAC cells. Our in vitro and in situ data corroborate that PBK/TOPK is closely associated with the invasive nature of PDAC and reveal a novel mechanism by which the metastatic behavior of human pancreatic cancer cells is regulated. These findings provide a rationale for targeting PBK/TOPK for the therapeutic intervention of invasive/metastatic pancreatic cancer in human.

Mechanisms of Action of Novel Drugs Targeting Angiogenesis-Promoting Matrix Metalloproteinases

Angiogenesis is facilitated by the proteolytic activities of members of the matrix metalloproteinase (MMP) family. More specifically, MMP-9 and MT1-MMP directly regulate angiogenesis, while several studies indicate a role for MMP-2 as well. The correlation of MMP activity to tumor angiogenesis has instigated numerous drug development programs. However, broad-based and Zn²⁺-chelating MMP inhibitors have fared poorly in the clinic. Selective MMP inhibition by antibodies, biologicals, and small molecules has utilized unique modes of action, such as (a) binding to protease secondary binding sites (exosites), (b) allosterically blocking the protease active site, or (c) preventing proMMP activation. Clinical trials have been undertaken with several of these inhibitors, while others are in advanced pre-clinical stages. The mechanistically non-traditional MMP inhibitors offer treatment strategies for tumor angiogenesis that avoid the off-target toxicities and lack of specificity that plagued Zn²⁺-chelating inhibitors.

Therapeutic efficacy of anti-MMP9 antibody in combination with nab-paclitaxel-based chemotherapy in pre-clinical models of pancreatic cancer

Matrix metalloproteinase 9 (MMP9) is involved in the proteolysis of extracellular proteins and plays a critical role in pancreatic ductal adenocarcinoma (PDAC) progression, invasion and metastasis. The therapeutic potential of an anti‐MMP9 antibody (αMMP9) was evaluated in combination with nab‐paclitaxel (NPT)‐based standard cytotoxic therapy in pre‐clinical models of PDAC. Tumour progression and survival studies were performed in NOD/SCID mice. The mechanistic evaluation involved RNA‐Seq, Luminex, IHC and Immunoblot analyses of tumour samples. Median animal survival compared to controls was significantly increased after 2‐week therapy with NPT (59%), Gem (29%) and NPT+Gem (76%). Addition of αMMP9 antibody exhibited further extension in survival: NPT+αMMP9 (76%), Gem+αMMP9 (47%) and NPT+Gem+αMMP9 (94%). Six‐week maintenance therapy revealed that median animal survival was significantly increased after NPT+Gem (186%) and further improved by the addition of αMMP9 antibody (218%). Qualitative assessment of mice exhibited that αMMP9 therapy led to a reduction in jaundice, bloody ascites and metastatic burden. Anti‐MMP9 antibody increased the levels of tumour‐associated IL‐28 (1.5‐fold) and decreased stromal markers (collagen I, αSMA) and the EMT marker vimentin. Subcutaneous tumours revealed low but detectable levels of MMP9 in all therapy groups but no difference in MMP9 expression. Anti‐MMP9 antibody monotherapy resulted in more gene expression changes in the mouse stroma compared to the human tumour compartment. These findings suggest that anti‐MMP9 antibody can exert specific stroma‐directed effects that could be exploited in combination with currently used cytotoxics to improve clinical PDAC therapy.

Targeted therapies in pancreatic cancer: Promises and failures

Pancreatic ductal adenocarcinoma (PDAC) is an incidence rate nearly equal to its mortality rate. The poor prognosis of the disease can be explained by the absence of effective biomarkers for screening and early detection, together with the aggressive behavior and resistance to the currently available chemotherapy. The therapeutic failure can also be attributed to the inter-/intratumor genetic heterogeneity and the abundance of tumor stroma that occupies the majority of the tumor mass. Gemcitabine is used in the treatment of PDAC; however, the response rate is less than 12%. A recent phase III trial revealed that the combination of oxaliplatin, irinotecan, fluorouracil, and leucovorin could be an option for the treatment of metastatic PDAC patients with good performance status, although these approaches can result in high toxicity level. Further investigations are required to develop innovative anticancer agents that either improve gemcitabine activity, within novel combinatorial approaches or acts with a better efficacy than gemcitabine. The aim of the current review is to give an overview of preclinical and clinical studies targeting key dysregulated signaling pathways in PDAC.

H19 long non-coding RNA contributes to sphere formation and invasion through regulation of CD24 and integrin expression in pancreatic cancer cells

The long non-coding RNA H19 is highly expressed in several cancers, and the functions of H19 vary among cancer cell types. Recently, we reported that H19 contributes to the metastasis of pancreatic ductal adenocarcinoma (PDAC) cells and that inhibition of H19 reduces metastasis in vivo. However, the molecular mechanisms underlying the metastasis-promoting role of H19 in PDAC cells remain poorly elucidated. In this study, we clarified the mechanisms by which H19 regulates PDAC metastasis, with a focus on cancer stem cells (CSCs), by using H19-overexpressing and knockdown PDAC cells. Whereas the sphere-formation and invasion abilities of PDAC cells depended on H19 expression levels, other CSC characteristics of the cells, including stemness-marker expression and anticancer-drug resistance, were unaffected by H19 levels. Furthermore, metalloproteinase activity, a key mediator of invasion, was also independent of H19 expression. By contrast, H19 promoted cell adhesion through regulation of integrin and CD24 expression. Notably, the increased adhesion of H19-overexpressing cells was blocked by an anti-β1-integrin antibody, and this resulted in the inhibition of sphere formation and invasion. Thus, H19 plays critical roles in the CSC self-renewal and cell adhesion of PDAC that lead to invasion and metastasis. Our findings suggest that H19 represents a novel therapeutic target for the metastasis of pancreatic cancer.

Prognostic significance of plasma matrix metalloprotease-2 in pancreatic cancer patients

Background & objectives:

Pancreatic cancer has a propensity for wide stromal invasion. Matrix metalloprotease-2 (MMP-2) is a protease that degrades the peri-tumoural tissue and helps in tumour dissemination. Thus, this study was aimed to assess any association of plasma MMP-2 levels with clinicopathological parameters and survival of patients with pancreatic cancer.

Methods:

Plasma samples from 127 pancreatic cancer patients were analyzed for MMP-2 levels by ELISA. Survival and other clinicopathological parameters of patients were analyzed for any correlation with plasma MMP-2 levels.

Results:

The mean MMP-2 levels in pancreatic cancer patients were 560.3±222.0 ng/ml which were significantly elevated compared to chronic pancreatitis patients (P<0.001) and healthy individuals (P<0.05). The plasma levels of MMP-2 significantly correlated with tissue expression of this protease (P=0.004). However, MMP-2 levels did not exhibit any association either with clinicopathological parameters or with survival.

Interpretation & conclusions:

Elevated MMP-2 levels were observed in blood of pancreatic cancer patients which correlated with its tissue expression. However, these levels did not associate with survival or any clinicopathological parameters of patients. Further studies need to be done to confirm the prognostic/clinical significance of MMP-2 in cancer patients before and after surgery.

Shattering the castle walls: Anti-stromal therapy for pancreatic cancer

Despite the availability of potent chemotherapy regimens, such as 5-fluorouracil, folinic acid, irinotecan, and oxaliplatin (FOLFIRINOX) and nab-paclitaxel plus gemcitabine, treatment outcomes in metastatic pancreatic cancer (PC) remain unsatisfactory. The presence of an abundant fibrous stroma in PC is considered a crucial factor for its unfavorable condition. Apparently, stroma acts as a physical barrier to restrict intratumoral cytotoxic drug penetration and creates a hypoxic environment that reduces the efficacy of radiotherapy. In addition, stroma plays a vital supportive role in the development and progression of PC, which has prompted researchers to assess the potential benefits of agents targeting several cellular (e.g., stellate cells) and acellular (e.g., hyaluronan) elements of the stroma. This study aims to briefly review the primary structural properties of PC stroma and its interaction with cancer cells and summarize the current status of anti-stromal therapies in the management of metastatic PC.

ERO1L promotes pancreatic cancer cell progression through activating the Wnt/catenin pathway

Pancreatic cancer is a lethal malignancy with an extremely poor prognosis. Although many genes and noncoding RNAs have been found to regulate its progression, more regulators are needed to be understood to resolve its high lethality. Endoplasmic reticulum oxidoreductase 1 alpha (ERO1L) plays crucial roles in the progression of various tumors, but its role in pancreatic cancer progression has not been studied. In this study, we found that ERO1L was significantly upregulated in pancreatic cancer cells and patients; its overexpression significantly promoted pancreatic cancer migration, invasion, and growth, while its knockdown significantly inhibited pancreatic cancer migration, invasion, and growth. Mechanism analysis suggested that ERO1L promoted many tumor-associated signaling pathways, especially the Wnt/catenin pathway; it could activate the Wnt/catenin pathway and upregulate the targets of the Wnt/catenin pathway. We further analyzed the correlation between ERO1L expression and the prognosis of patients, suggesting that patients with high ERO1L expression had short survival time; it is an independent prognosis factor for patients' prognosis. Together, we found that ERO1L was an oncogene for pancreatic cancer.

Advantages of patient-derived orthotopic mouse models and genetic reporters for developing fluorescence-guided surgery

Fluorescence-guided surgery can enhance the surgeon's ability to achieve a complete oncologic resection. There are a number of tumor-specific probes being developed with many preclinical mouse models to evaluate their efficacy. The current review discusses the different preclinical mouse models in the setting of probe evaluation and highlights the advantages of patient-derived orthotopic xenografts (PDOX) mouse models and genetic reporters to develop fluorescence-guided surgery.

The development of fluorescence guided surgery for pancreatic cancer: from bench to clinic

INTRODUCTION

Surgeons face major challenges in achieving curative R0 resection for pancreatic cancers. When the lesion is localized, they must appropriately visualize the tumor, determine appropriate resection margins, and ensure complete tumor clearance. Real-time surgical navigation using fluorescence-guidance has enhanced the ability of surgeons to see the tumor and has the potential to assist in achieving more oncologically complete resections. When there is metastatic disease, fluorescence enhancement can help detect these lesions and prevent unnecessary and futile surgeries. Areas covered: This article reviews different approaches for delivery of a fluorescence signal, their pre-clinical and clinical developments for fluorescence guided surgery, the advantages/challenges of each, and their potential for advancements in the future. Expert commentary: A variety of molecular imaging techniques are available for delivering tumor-specific fluorescence signals. Significant advancements have been made in the past 10 years due to the large body of literature on targeted therapies and this has translated into rapid developments of tumor-specific probes.

The Role of Resveratrol in Cancer Therapy

Natural product compounds have recently attracted significant attention from the scientific community for their potent effects against inflammation-driven diseases, including cancer. A significant amount of research, including preclinical, clinical, and epidemiological studies, has indicated that dietary consumption of polyphenols, found at high levels in cereals, pulses, vegetables, and fruits, may prevent the evolution of an array of diseases, including cancer. Cancer development is a carefully orchestrated progression where normal cells acquires mutations in their genetic makeup, which cause the cells to continuously grow, colonize, and metastasize to other organs such as the liver, lungs, colon, and brain. Compounds that modulate these oncogenic processes can be considered as potential anti-cancer agents that may ultimately make it to clinical application. Resveratrol, a natural stilbene and a non-flavonoid polyphenol, is a phytoestrogen that possesses anti-oxidant, anti-inflammatory, cardioprotective, and anti-cancer properties. It has been reported that resveratrol can reverse multidrug resistance in cancer cells, and, when used in combination with clinically used drugs, it can sensitize cancer cells to standard chemotherapeutic agents. Several novel analogs of resveratrol have been developed with improved anti-cancer activity, bioavailability, and pharmacokinetic profile. The current focus of this review is resveratrol’s in vivo and in vitro effects in a variety of cancers, and intracellular molecular targets modulated by this polyphenol. This is also accompanied by a comprehensive update of the various clinical trials that have demonstrated it to be a promising therapeutic and chemopreventive agent.

Matrix metalloproteinase collagenolysis in health and disease

The proteolytic processing of collagen (collagenolysis) is critical in development and homeostasis, but also contributes to numerous pathologies. Mammalian interstitial collagenolytic enzymes include members of the matrix metalloproteinase (MMP) family and cathepsin K. While MMPs have long been recognized for their ability to catalyze the hydrolysis of collagen, the roles of individual MMPs in physiological and pathological collagenolysis are less defined. The use of knockout and mutant animal models, which reflect human diseases, has revealed distinct collagenolytic roles for MT1-MMP and MMP-13. A better understanding of temporal and spatial collagen processing, along with the knowledge of the specific MMP involved, will ultimately lead to more effective treatments for cancer, arthritis, cardiovascular conditions, and infectious diseases. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.

Quercetin inhibits epithelial-mesenchymal transition, decreases invasiveness and metastasis, and reverses IL-6 induced epithelial-mesenchymal transition, expression of MMP by inhibiting STAT3 signaling in pancreatic cancer cells

Quercetin, a flavone, is multifaceted, having anti-oxidative, anti-inflammatory, and anticancer properties. In the present study, we explored the effects of quercetin on the epithelial–mesenchymal transition (EMT) and invasion of pancreatic cancer cells and the underlying mechanisms. We noted that quercetin exerted pronounced inhibitory effects in PANC-1 and PATU-8988 cells. Moreover, quercetin inhibited EMT and decreased the secretion of matrix metalloproteinase (MMP). Meanwhile, we determined the activity of STAT3 after quercetin treatment. STAT3 phosphorylation decreased following treatment with quercetin. We also used activating agent of STAT3, IL-6, to induce an increase in cell malignancy and to observe the effects of treatment with quercetin. As expected, the EMT and MMP secretion increased with activation of the STAT3 signaling pathway, and quercetin reversed IL-6-induced EMT, invasion, and migration. Therefore, our results demonstrate that quercetin triggers inhibition of EMT, invasion, and metastasis by blocking the STAT3 signaling pathway, and thus, quercetin merits further investigation.

Synthetic 8-hydroxydeoxyguanosine inhibited metastasis of pancreatic cancer through concerted inhibitions of ERM and Rho-GTPase

8-hydroxydeoxyguanosine (8-OHdG) is generated consequent to oxidative stress, but its paradoxical anti-oxidative, anti-inflammatory, and anti-mutagenic effects via Rho-GTPase inhibition were noted in various models of inflammation and cancer. Metastasis occurs through cell detachment, epithelial-mesenchymal transition (EMT), and cell migration; during these processes, changes in cell morphology are initiated through Rho-GTPase-dependent actin cytoskeleton polymerization. In this study, we explored the anti-metastatic mechanisms of 8-OHdG in Panc-1 pancreatic cancer cells. 8-OHdG inhibits cell migration by inactivating ERM and Rho-GTPase proteins, and inhibiting focal adhesion kinase (FAK) and matrix metalloproteinases (MMPs). At 15min, 8-OHdG significantly inactivated ERM (p < 0.05) and led to a significant retardation of wound healing; siERM and H1152 (ROCK inhibitor) had similar effects (p < 0.05). However, FAK inhibitor 14, DPI (NOX inhibitor), and NAC (antioxidant) significantly delayed wound healing without inhibiting ERM or CD44 (p < 0.05). In the experiments on cell migration, siERM, siCD44, DPI, and 8-OHdG significantly inhibited MMPs. 8-OHdG significantly decreased DCF-DA activation in Panc-1 pancreatic cancer cells and down-regulated NOXs (nox-1, nox-2, and nox-3). Finally, all of these anti-migration actions of 8-OHdG resulted in significant inhibition of EMT, as evidenced by the up-regulation of ZO-1 and claudin-1 and down-regulation of vimentin. We found significant inhibition of lung metastasis of Panc-1 cells by 8-OHdG. In conclusion, exogenous 8-OHdG had potent anti-metastasis effects mediated by either ERM or Rho GTPase inhibition in metastasis-prone pancreatic cancer cells.

The Roles of Matrix Metalloproteinases in Pancreatic Cancer

Matrix metalloproteinases (MMPs) have long been implicated for roles in cancer initiation, tumor growth, and metastasis. However, pancreatic cancer clinical trials using broad-based MMP inhibitors were discouraging. To better evaluate the use of MMP inhibitors in pancreatic cancer, (a) more precise roles of individual MMPs in pancreatic cancer needed to be determined and (b) animal models that more accurately represented human pancreatic cancer needed to be developed. The last decade has seen substantial progress in both areas. MT1-MMP has been recognized as a critical mediator of several steps in pancreatic cancer progression, while MMP-9 appears to be an antitarget when considering pancreatic cancer therapies.

A blockade of PD-L1 produced antitumor and antimetastatic effects in an orthotopic mouse pancreatic cancer model via the PI3K/Akt/mTOR signaling pathway

BACKGROUND

Pancreatic cancer is one of the most aggressive and intractable malignant tumors, and most deaths from pancreatic cancer are related to metastases. It has been demonstrated in vitro that overexpression of programmed death-ligand 1 (PD-L1) correlates with a lack of phosphatase and tensin homologue (PTEN) expression in pancreatic cancer tissue. This loss of PTEN expression may aberrantly activate the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway, and thereby promote tumor cell survival, proliferation, and disease progression. In this study, we investigated the potential therapeutic effect of blockading PD-L1 expression on the progression of pancreatic cancer and its spontaneous liver metastases in vivo by inhibiting the PI3K/Akt/mTOR signaling pathway.

METHODS

We investigated the effect of blockading PD-L1 in an orthotopic pancreatic cancer mouse model. The pancreatic tumor weights and inhibition ratios were determined after treatment with antimouse PD-L1 antibody for 5 weeks. We used immunohistochemistry methods to investigate PD-L1 expression in pancreatic cancer tissue and spontaneous liver metastasis tissue. The levels of mRNA and protein expression for various components involved in the PI3K/Akt/mTOR signaling pathway as well as for matrix metalloproteinases-2 and -9 (MMP2 and MMP9) were measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot methods, respectively.

RESULTS

Blockading PD-L1 significantly inhibited tumor growth and decreased the levels of PD-L1 expression in tumor tissue. Furthermore, the levels of PTEN mRNA and protein expression were elevated, while the levels of phospho-Akt (p-Akt) and phospho-mTOR (p-mTOR) protein were decreased in pancreatic cancer and liver metastasis tissues after establishing a PD-L1 blockade. In addition, a PD-L1 blockade decreased the levels of MMP2 and MMP9 mRNA and protein expression in tumor tissues.

CONCLUSION

Our results suggest that a blockade of PD-L1 may inhibit the growth and metastasis of pancreatic cancer by modulating the PI3K/Akt/mTOR pathway.

Dysregulation of signaling pathways associated with innate antibacterial immunity in patients with pancreatic cancer

Disorders of innate antibacterial response are of fundamental importance in the development of gastrointestinal cancers, including pancreatic cancer. Multi-regulatory properties of the Toll-like receptors (TLRs) (e.g., regulation of proliferation, the activity of NF-κB, gene transcription of apoptosis proteins, regulation of angiogenesis, HIF-1α protein expression) are used in experimental studies to better understand the pathogenesis of pancreatic cancer, for early diagnosis, and for more effective therapeutic intervention. There are known numerous examples of TLR agonists (e.g., TLR2/5 ligands, TLR6, TLR9) of antitumor effect. The direction of these studies is promising, but a small number of them does not allow for an accurate assessment of the impact of TLR expression disorders, proteins of these signaling pathways, or attempts to block or stimulate them, on the results of treatment of pancreatic cancer patients. It is known, however, that the expression disorders of proteins of innate antibacterial response signaling pathways occur not only in tumor tissue but also in peripheral blood leukocytes of pancreatic cancer patients (e.g., increased expression of TLR4, NOD1, TRAF6), which is one of the most important factors facilitating further tumor development. This review mainly focuses on the genetic aspects of signaling pathway disorders associated with innate antibacterial response in the pathogenesis and diagnosis of pancreatic cancer.

Anti-metastatic potential of resveratrol and its metabolites by the inhibition of epithelial-mesenchymal transition, migration, and invasion of malignant cancer cells

BACKGROUND

Increased epithelial-mesenchymal transition (EMT) and cell migration and invasion abilities of cancer cells play important roles in the metastatic process of cancer. Resveratrol is a stilbenoid, a type of natural polyphenol found in the skin of grapes, berries, and peanuts. A number of experiments have examined resveratrol's ability to target diverse pathways associated with carcinogenesis and cancer progression.

PURPOSE

This article aims to present updated overview of the knowledge that resveratrol and its metabolites or analogs have the potential to inhibit metastasis of cancer via affecting many signaling pathways related with EMT, cancer migration, and invasion in diverse organs of the body.

CHAPTERS

This article starts with a short introduction describing diverse beneficial effects of resveratrol including cancer prevention and the aim of the present study. To address the effects of resveratrol on cancer metastasis, mechanisms of EMT, migration, invasion, and their relevance with cancer metastasis, anti-metastatic effects of resveratrol through EMT-related signaling pathways and inhibitory effects of resveratrol on migration and invasion are highlighted. In addition, anti-metastatic potential of resveratrol metabolites and analogs is addressed.

CONCLUSION

Resveratrol was demonstrated to turn back the EMT process induced by diverse signaling pathways in several cellular and animal cancer models. In addition, resveratrol can exert chemopreventive efficacies on migration and invasion of cancer cells by inhibiting the related pathways and target molecules. Although these findings display the anti-metastatic potential of resveratrol, more patient-oriented clinical studies demonstrating the marked efficacies of resveratrol in humans are still needed.

Matrix metalloproteinase-9 (MMP-9) as an activator of nanosystems for targeted drug delivery in pancreatic cancer

Specific cancer cell targeting is a pre-requisite for efficient drug delivery as well as for high-resolution imaging and still represents a major technical challenge. Tumor-associated enzyme-assisted targeting is a new concept that takes advantage of the presence of a specific activity in the tumor entity. MMP-9 is a protease found to be upregulated in virtually all malignant tumors. Consequently, we hypothesized that its presence can provide a de-shielding activity for targeted delivery of drugs by nanoparticles (NPs) in pancreatic cancer. Here, we describe synthesis and characterization of an optimized MMP-9-cleavable linker mediating specific removal of a PEG shield from a PLGA-b-PEG-based polymeric nanocarrier (Magh@PNPs-PEG-RegaCP-PEG) leading to specific uptake of the smaller PNPs with their cargo into cells. The specific MMP-9-cleavable linker was designed based on the degradation efficiency of peptides derived from the collagen type II sequence. MMP-9-dependent uptake of the Magh@PNPs-PEG-RegaCP-PEG was demonstrated in pancreatic cancer cells in vitro. Accumulation of the Magh@PNPs-PEG-RegaCP-PEG in pancreatic tissues in the clinically relevant KPC mouse model of pancreatic cancer, as a proof-of-concept, was tumor-specific and MMP-9-dependent, indicating that MMP-9 has a strong potential as a specific mediator of PNP de-shielding for tumor-specific uptake. Pre-treatment of mice with Magh@PNPs-PEG-RegaCP-PEG led to reduction of liver metastasis and drastically decreased average colony size. In conclusion, the increased tumor-specific presence and activity of MMP-9 can be exploited to deliver an MMP-9-activatable NP to pancreatic tumors specifically, effectively, and safely.

Blood flow responses to mild-intensity exercise in ectopic vs. orthotopic prostate tumors; dependence upon host tissue hemodynamics and vascular reactivity

Given the critical role of tumor O2 delivery in patient prognosis and the rise in preclinical exercise oncology studies, we investigated tumor and host tissue blood flow at rest and during exercise as well as vascular reactivity using a rat prostate cancer model grown in two transplantation sites. In male COP/CrCrl rats, blood flow (via radiolabeled microspheres) to prostate tumors [R3327-MatLyLu cells injected in the left flank (ectopic) or ventral prostate (orthotopic)] and host tissue was measured at rest and during a bout of mild-intensity exercise. α-Adrenergic vasoconstriction to norepinephrine (NE: 10(-9) to 10(-4) M) was determined in arterioles perforating the tumors and host tissue. To determine host tissue exercise hyperemia in healthy tissue, a sham-operated group was included. Blood flow was lower at rest and during exercise in ectopic tumors and host tissue (subcutaneous adipose) vs. the orthotopic tumor and host tissue (prostate). During exercise, blood flow to the ectopic tumor significantly decreased by 25 ± 5% (SE), whereas flow to the orthotopic tumor increased by 181 ± 30%. Maximal vasoconstriction to NE was not different between arterioles from either tumor location. However, there was a significantly higher peak vasoconstriction to NE in subcutaneous adipose arterioles (92 ± 7%) vs. prostate arterioles (55 ± 7%). Establishment of the tumor did not alter host tissue blood flow from either location at rest or during exercise. These data demonstrate that blood flow in tumors is dependent on host tissue hemodynamics and that the location of the tumor may critically affect how exercise impacts the tumor microenvironment and treatment outcomes.

Biomarkers and Targeted Therapy in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) constitutes 90% of pancreatic cancers. PDAC is a complex and devastating disease with only 1%-3% survival rate in five years after the second stage. Treatment of PDAC is complicated due to the tumor microenvironment, changing cell behaviors to the mesenchymal type, altered drug delivery, and drug resistance. Considering that pancreatic cancer shows early invasion and metastasis, critical research is needed to explore different aspects of the disease, such as elaboration of biomarkers, specific signaling pathways, and gene aberration. In this review, we highlight the biomarkers, the fundamental signaling pathways, and their importance in targeted drug delivery for pancreatic cancers.

Assessment of Matrix Metalloproteinases by Gelatin Zymography

Matrix metalloproteinases are endopeptidases responsible for remodeling of the extracellular matrix and have been identified as critical contributors to breast cancer progression. Gelatin zymography is a valuable tool which allows the analysis of MMP expression. In this approach, enzymes are resolved electrophoretically on a sodium dodecyl sulfate-polyacrylamide gel copolymerized with the substrate for the MMP of interest. Post electrophoresis, the enzymes are refolded in order for proteolysis of the incorporated substrate to occur. This assay yields valuable information about MMP isoforms or changes in activation and can be used to analyze the role of MMPs in normal versus pathological conditions.

Hinokitiol Exerts Anticancer Activity through Downregulation of MMPs 9/2 and Enhancement of Catalase and SOD Enzymes: In Vivo Augmentation of Lung Histoarchitecture

Melanoma is extremely resistant to chemotherapy and the death rate is increasing hastily worldwide. Extracellular matrix promotes the migration and invasion of tumor cells through the production of matrix metalloproteinase (MMP)-2 and -9. Evidence has shown that natural dietary antioxidants are capable of inhibiting cancer cell growth. Our recent studies showed that hinokitiol, a natural bioactive compound, inhibited vascular smooth muscle cell proliferation and platelets aggregation. The present study is to investigate the anticancer efficacy of hinokitiol against B16-F10 melanoma cells via modulating tumor invasion factors MMPs, antioxidant enzymes in vitro. An in vivo mice model of histological investigation was performed to study the patterns of elastic and collagen fibers. Hinokitiol inhibited the expression and activity of MMPs-2 and -9 in B16-F10 melanoma cells, as measured by western blotting and gelatin zymography, respectively. An observed increase in protein expression of MMPs 2/9 in melanoma cells was significantly inhibited by hinokitiol. Notably, hinokitiol (1–5 μM) increased the activities of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) from the reduction in melanoma cells. Also, hinokitiol (2–10 µM) concentration dependently reduced in vitro Fenton reaction induced hydroxyl radical (OH·) formation. An in vivo study showed that hinokitiol treatment increased elastic fibers (EF), collagens dispersion, and improved alveolar alterations in the lungs of B16/F10 injected mice. Overall, our findings propose that hinokitiol may be a potent anticancer candidate through down regulation of MMPs 9/2, reduction of OH· production and enhancement of antioxidant enzymes SOD and CAT.

Neural Regulation of Pancreatic Cancer: A Novel Target for Intervention

The tumor microenvironment is known to play a pivotal role in driving cancer progression and governing response to therapy. This is of significance in pancreatic cancer where the unique pancreatic tumor microenvironment, characterized by its pronounced desmoplasia and fibrosis, drives early stages of tumor progression and dissemination, and contributes to its associated low survival rates. Several molecular factors that regulate interactions between pancreatic tumors and their surrounding stroma are beginning to be identified. Yet broader physiological factors that influence these interactions remain unclear. Here, we discuss a series of preclinical and mechanistic studies that highlight the important role chronic stress plays as a physiological regulator of neural-tumor interactions in driving the progression of pancreatic cancer. These studies propose several approaches to target stress signaling via the β-adrenergic signaling pathway in order to slow pancreatic tumor growth and metastasis. They also provide evidence to support the use of β-blockers as a novel therapeutic intervention to complement current clinical strategies to improve cancer outcome in patients with pancreatic cancer.

Association of matrix metalloproteinase (MMP)-2 and -9 expression with extra-gastrointestinal stromal tumor metastasis

Matrix metalloproteinase (MMP)-2 and MMP-9 are important proteases involved in invasion and metastasis of various tumors. Extra-gastrointestinal stromal tumors (EGISTs) are rare neoplasms. This study was performed to assess MMP-2 and MMP-9 expression in EGIST tissue samples for association with clinicopathological data from the patients. Twenty-one surgical EGIST tissue specimens were collected for analysis of MMP-2 and MMP- 9 expression using immunohistochemistry. MMP-2 and MMP-9 proteins were expressed in all of the epithelial cell types of EGISTs, whereas they were only expressed in 75% of the spindle cell type, although there was no statistically significant difference (p>0.05). Expression of MMP-2 and MMP-9 proteins was associated with tumor size, mitotic rate, tumor necrosis, and distant metastasis (p<0.05). MMP-2 expression was linked with MMP-9 levels (p<0.05). However, there was no correlation between MMP-9 expression and age, sex, primary site, or cell morphology in any of these 21 EGIST patients (p>0.05). Moreover, expression of MMP-2 and MMP-9 proteins increased with the degree of EGIST risk. This study provided evidence of an association of MMP-2 and MMP-9 expression with advanced EGIST behavior.

Targeting Matrix Metalloproteinases in Cancer: Bringing New Life to Old Ideas

Since the identification of matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases, as being a driving factor for cancer progression and patient prognosis, MMPs have been studied extensively. Although early programs targeting MMPs were largely unsuccessful in clinical trials, they remain a viable and highly desirable therapeutic target based on preclinical studies and their role in disease progression. As information regarding the structure and function of these proteinases is compiled and biotechnology evolves, tools to develop better inhibitors is within our grasp. Improved methods for high throughput screening and in silico drug design programs have identified compounds which are highly potent, have high binding affinities, and exhibit favorable pharmacokinetic profiles. More recently, advances in drug delivery methods or compounds which bind outside the active site have brought new light to the field. In this review, we highlight the role of MMPs in cancer, clinical trials for MMP inhibitors, and novel approaches to targeting MMPs in cancer.