Reversion of pH-induced physiological drug resistance: a novel function of copolymeric nanoparticles

Aims

The extracellular pH of cancer cells is lower than the intracellular pH. Weakly basic anticancer drugs will be protonated extracellularly and display a decreased intracellular concentration. In this study, we show that copolymeric nanoparticles (NPs) are able to overcome this “pH-induced physiological drug resistance” (PIPDR) by delivering drugs to the cancer cells via endocytosis rather than passive diffussion.

Materials and Methods

As a model nanoparticle, Tetradrine (Tet, Pka 7.80) was incorporated into mPEG-PCL. The effectiveness of free Tet and Tet-NPs were compared at different extracellular pHs (pH values 6.8 and 7.4, respectively) by MTT assay, morphological observation and apoptotic analysis in vitro and on a murine model by tumor volume measurement, PET-CT scanning and side effect evaluation in vivo.

Results

The cytotoxicity of free Tet decreased prominently (P<0.05) when the extracellular pH decreased from 7.4 to 6.8. Meanwhile, the cytotoxicity of Tet-NPs was not significantly influenced by reduced pH. In vivo experiment also revealed that Tet-NPs reversed PIPDR more effectively than other existing methods and with much less side effects.

Conclusion

The reversion of PIPDR is a new discovered mechanism of copolymeric NPs. This study emphasized the importance of cancer microenvironmental factors in anticancer drug resistance and revealed the superiority of nanoscale drug carrier from a different aspect.     

In Vitro and In Vivo Antitumor Activity of a Novel pH-Activated Polymeric Drug Delivery System for Doxorubicin

Background

Conventional chemotherapy agent such as doxorubicin (DOX) is of limited clinical use because of its inherently low selectivity, which can lead to systemic toxicity in normal healthy tissue.

Methods

A pH stimuli-sensitive conjugate based on polyethylene glycol (PEG) with covalently attachment doxorubicin via hydrazone bond (PEG-hyd-DOX) was prepared for tumor targeting delivery system. While PEG-DOX conjugates via amid bond (PEG-ami-DOX) was synthesized as control.

Results

The synthetic conjugates were confirmed by proton nuclear magnetic resonance (NMR) spectroscopy, the release profile of DOX from PEG-hyd-DOX was acid-liable for the hydrazone linkage between DOX and PEG, led to different intracellular uptake route; intracellular accumulation of PEG-hyd-DOX was higher than PEG-ami-DOX due to its pH-triggered profile, and thereby more cytotoxicity against MCF-7, MDA-MB-231 (breast cancer models) and HepG2 (hepatocellular carcinoma model) cell lines. Following the in vitro results, we xenografted MDA-MB-231 cell onto SCID mice, PEG-hyd-DOX showed stronger antitumor efficacy than free DOX and was tumor-targeting.

Conclusions

Results from these in vivo experiments were consistent with our in vitro results; suggested this pH-triggered PEG-hyd-DOX conjugate could target DOX to tumor tissues and release free drugs by acidic tumor environment, which would be potent in antitumor drug delivery.     

Upregulation of Gelatinases and Epithelial–Mesenchymal Transition in Small Airway Remodeling Associated with Chronic Exposure to Wood Smoke

Background

Peribronchiolar fibrosis is an important feature of small airway remodeling (SAR) in cigarette smoke-induced COPD. The aim of this study was to investigate the role of gelatinases (MMP9, MMP2) and epithelial-mesenchymal transition (EMT) in SAR related to wood smoke (WS) exposure in a rat model.

Methods

Forty-eight female Sprague-Dawley rats were randomly divided into the WS group, the cigarette smoke (CS) group and the clean air control group. After 4 to 7 months of smoke exposure, lung tissues were examined with morphometric measurements, immunohistochemistry and Western blotting. Serum MMP9 and TIMP1 concentrations were detected by ELISA. In vitro, primary rat tracheal epithelial cells were stimulated with wood smoke condensate for 7 days.

Results

The COPD-like pathological alterations in rats exposed chronically to WS were similar to those exposed to CS; the area of collagen deposition was significantly increased in the small airway walls of those exposed to WS or CS for 7 months. The expression of gelatinases in rats induced by WS or CS exposure was markedly increased in whole lung tissue, and immunohistochemistry showed that MMP9, MMP2 and TIMP1 were primarily expressed in the airway epithelium. The serum levels of MMP9 and TIMP1 were significantly higher in rats secondary to WS or CS exposure. Few cells that double immunostained for E-cadherin and vimentin were observed in the airway subepithelium of rats exposed to WS for 7 months (only 3 of these 8 rats). In vitro, the expression of MMP9 and MMP2 proteins was upregulated in primary rat tracheal epithelial cells following exposure to wood smoke condensate for 7 days by Western blotting; positive immunofluorescent staining for vimentin and type I collagen was also observed.

Conclusions

These findings suggest that the upregulation of gelatinases and EMT might play a role in SAR in COPD associated with chronic exposure to wood smoke.     

IL-17A Promotes the Migration and Invasiveness of Cervical Cancer Cells by Coordinately Activating MMPs Expression via the p38/NF-κB Signal Pathway

Objective

IL-17A plays an important role in many inflammatory diseases and cancers. We aimed to examine the effect of IL-17A on the invasion of cervical cancer cells and study its related mechanisms.

Methods

Wound healing and matrigel transwell assays were used to examine the effect of IL-17A on cervical cancer cell migration and invasion by a panel of cervical cancer cell lines. The levels of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) were investigated using western blotting. The activity of p38 and nuclear factor-kappa B (NF-κB) signal pathway was detected too.

Results

Here, we showed that IL-17A could promote the migration and invasion of cervical cancer cells. Further molecular analysis showed that IL-17A could up-regulate the expressions and activities of MMP2 and MMP9, and down-regulate the expressions of TIMP-1 and TIMP-2. Furthermore, IL-17A also activates p38 signal pathway and increased p50 and p65 nuclear expression. In addition, treatment of cervical cancer cells with the pharmacological p38/NF-κB signal pathway inhibitors, SB203580 and PDTC, potently restored the roles of invasion and upregulation of MMPs induced by IL-17A.

Conclusion

IL-17A could promote the migration and invasion of cervical cancer cell via up-regulating MMP2 and MMP9 expression, and down-regulating TIMP-1 and TIMP-2 expression via p38/NF-κB signal pathway. IL-17A may be a potential target to improve the prognosis for patients with cervical cancer.     

Evaluation of Alpha 1-Antitrypsin and the Levels of mRNA Expression of Matrix Metalloproteinase 7, Urokinase Type Plasminogen Activator Receptor and COX-2 for the Diagnosis of Colorectal Cancer

Background

Colorectal cancer (CRC) is the second most common cause of death from cancer in both men and women in the majority of developed countries. Molecular tests of blood could potentially provide this ideal screening tool.

Aim

Our objective was to assess the usefulness of serum markers and mRNA expression levels in the diagnosis of CRC.

Methods

In a prospective study, we measured mRNA expression levels of 13 markers (carbonic anhydrase, guanylyl cyclase C, plasminogen activator inhibitor, matrix metalloproteinase 7 (MMP7), urokinase-type plasminogen activator receptor (uPAR), urokinase-type plasminogen activator, survivin, tetranectin, vascular endothelial growth factor (VEGF), cytokeratin 20, thymidylate synthase, cyclooxygenase 2 (COX-2), and CD44) and three proteins in serum (alpha 1 antitrypsin, carcinoembryonic antigen (CEA) and activated C3 in 42 patients with CRC and 33 with normal colonoscopy results.

Results

Alpha 1-antitrypsin was the serum marker that was most useful for CRC diagnosis (1.79±0.25 in the CRC group vs 1.27±0.25 in the control group, P<0.0005). The area under the ROC curve for alpha 1-antitrypsin was 0.88 (0.79–0.96). The mRNA expression levels of five markers were statistically different between CRC cases and controls: those for which the ROC area was over 75% were MMP7 (0.81) and tetranectin (0.80), COX-2 (0.78), uPAR (0.78) and carbonic anhydrase (0.77). The markers which identified early stage CRC (Stages I and II) were alpha 1-antitrypsin, uPAR, COX-2 and MMP7.

Conclusions

Serum alpha 1-antitrypsin and the levels of mRNA expression of MMP7, COX-2 and uPAR have good diagnostic accuracy for CRC, even in the early stages.     

Cyclen-based cationic lipids for highly efficient gene delivery towards tumor cells

Background

Gene therapy has tremendous potential for both inherited and acquired diseases. However, delivery problems limited their clinical application, and new gene delivery vehicles with low cytotoxicity and high transfection efficiency are greatly required.

Methods

In this report, we designed and synthesized three amphiphilic molecules (L1–L3) with the structures involving 1, 4, 7, 10-tetraazacyclododecane (cyclen), imidazolium and a hydrophobic dodecyl chain. Their interactions with plasmid DNA were studied via electrophoretic gel retardation assays, fluorescent quenching experiments, dynamic light scattering and transmission electron microscopy. The in vitro gene transfection assay and cytotoxicity assay were conducted in four cell lines.

Results

Results indicated that L1 and L3-formed liposomes could effectively bind to DNA to form well-shaped nanoparticles. Combining with neutral lipid DOPE, L3 was found with high efficiency in gene transfer in three tumor cell lines including A549, HepG2 and H460. The optimized gene transfection efficacy of L3 was nearly 5.5 times more efficient than that of the popular commercially available gene delivery agent Lipofectamine 2000™ in human lung carcinoma cells A549. In addition, since L1 and L3 had nearly no gene transfection performance in normal cells HEK293, these cationic lipids showed tumor cell-targeting property to a certain extent. No significant cytotoxicity was found for the lipoplexes formed by L1–L3, and their cytotoxicities were similar to or slightly lower than the lipoplexes prepared from Lipofectamine 2000™.

Conclusion

Novel cyclen-based cationic lipids for effective in vitro gene transfection were founded, and these studies here may extend the application areas of macrocyclic polyamines, especially for cyclen.     

Targeted Delivery of Doxorubicin-Loaded Poly (ε-caprolactone)-b-Poly (N-vinylpyrrolidone) Micelles Enhances Antitumor Effect in Lymphoma

Background

The present study was motivated by the need to design a safe nano-carrier for the delivery of doxorubicin which could be tolerant to normal cells. PCL₆₃-b-PNVP₉₀ was loaded with doxorubicin (6 mg/ml), and with 49.8% drug loading efficiency; it offers a unique platform providing selective immune responses against lymphoma.

Methods

In this study, we have used micelles of amphiphilic PCL₆₃-b-PNVP₉₀ block copolymer as nano-carrier for controlled release of doxorubicin (DOX). DOX is physically entrapped and stabilized in the hydrophobic cores of the micelles and biological roles of these micelles were evaluated in lymphoma.

Results

DOX loaded PCL₆₃-b-PNVP₉₀ block copolymer micelles (DOX-PCL₆₃-b-PNVP₉₀) shows enhanced growth inhibition and cytotoxicity against human (K-562, JE6.1 and Raji) and mice lymphoma cells (Dalton''s lymphoma, DL). DOX-PCL₆₃-b-PNVP₉₀ demonstrates higher levels of tumoricidal effect against DOX-resistant tumor cells compared to free DOX. DOX-PCL₆₃-b-PNVP₉₀ demonstrated effective drug loading and a pH-responsive drug release character besides exhibiting sustained drug release performance in in-vitro and intracellular drug release experiments.

Conclusion

Unlike free DOX, DOX-PCL₆₃-b-PNVP₉₀ does not show cytotoxicity against normal cells. DOX-PCL₆₃-b-PNVP₉₀ prolonged the survival of tumor (DL) bearing mice by enhancing the apoptosis of the tumor cells in targeted organs like liver and spleen.     

A Novel Magnetic Nanoparticle Drug Carrier for Enhanced Cancer Chemotherapy

Background

Magnetic nanoparticles (NPs) loaded with antitumor drugs in combination with an external magnetic field (EMF)-guided delivery can improve the efficacy of treatment and may decrease serious side effects. The purpose of this study was 1) to investigate application of PEG modified GMNPs (PGMNPs) as a drug carrier of the chemotherapy compound doxorubicin (DOX) in vitro; 2) to evaluate the therapeutic efficiency of DOX-conjugated PGMNPs (DOX-PGMNPs) using an EMF-guided delivery in vivo.

Methods

First, DOX-PGMNPs were synthesized and the cytotoxicity of DOX-PGMNPs was assessed in vitro. Second, upon intravenous administration of DOX-PMGPNs to H22 hepatoma cell tumor-bearing mice, the DOX biodistribution in different organs (tissues) was measured. The antitumor activity was evaluated using different treatment strategies such as DOX-PMGPNs or DOX-PMGPNs with an EMF-guided delivery (DOX-PGMNPs-M).

Results

The relative tumor volumes in DOX-PGMNPs-M, DOX-PGMNPs, and DOX groups were 5.46±1.48, 9.22±1.51, and 14.8±1.64, respectively (each p<0.05), following treatment for 33 days. The life span of tumor-bearing mice treated with DOX-PGMNPs-M, DOX-PGMNPs, and DOX were 74.8±9.95, 66.1±13.5, and 31.3±3.31 days, respectively (each p<0.05).

Conclusion

This simple and adaptive nanoparticle design may accommodate chemotherapy for drug delivery optimization and in vivo drug-target definition in system biology profiling, increasing the margin of safety in treatment of cancers in the near future.     

Flt-1 in colorectal cancer cells is required for the tumor invasive effect of placental growth factor through a p38-MMP9 pathway

Background

Placenta growth factor (PlGF), a dimeric glycoprotein with 53% homology to VEGF, binds to VEGF receptor-1 (Flt-1), but not to VEGF receptor-2 (Flk-1), and may function by modulating VEGF activity. We previously have showed that PlGF displays prognostic value in colorectal cancer (CRC) but the mechanism remains elucidated.

Results

Overexpression of PlGF increased the invasive/migration ability and decreased apoptosis in CRC cells showing Flt-1 expression. Increased migration was associated with increasing MMP9 via p38 MAPK activation. Tumors grew faster, larger; with higher vascularity from PlGF over-expression cells in xenograft assay. In two independent human CRC tissue cohorts, PlGF, MMP9, and Flt-1 expressions were higher in the advanced than the localized disease group. PlGF expression correlated with MMP9, and Flt-1 expression. CRC patients with high PlGF and high Flt-1 expression in tissue had poor prognosis.

Conclusion

PlGF/Flt-1 signaling plays an important role in CRC progression, blocking PlGF/Flt-1 signaling maybe an alternative therapy for CRC.     

Finasteride Inhibits Human Prostate Cancer Cell Invasion through MMP2 and MMP9 Downregulation

Introduction

The use of the 5-alpha reductase inhibitors (5-ARIs) finasteride and dutasteride for prostate cancer prevention is still under debate. The FDA recently concluded that the increased prevalence of high-grade tumors among 5-ARI-treated patients must not be neglected, and they decided to disallow the use of 5-ARIs for prostate cancer prevention. This study was conducted to verify the effects of finasteride on prostate cell migration and invasion and the related enzymes/proteins in normal human and tumoral prostatic cell lines.

Materials and Methods

RWPE-1, LNCaP, PC3 and DU145 cells were cultivated to 60% confluence and exposed for different periods to either 10 µM or 50 µM finasteride that was diluted in culture medium. The conditioned media were collected and concentrated, and MMP2 and MMP9 activities and TIMP-1 and TIMP-2 protein expression were determined. Cell viability, migration and invasion were analyzed, and the remaining cell extracts were submitted to androgen receptor (AR) detection by western blotting techniques. Experiments were carried out in triplicate.

Results

Cell viability was not significantly affected by finasteride exposure. Finasteride significantly downregulated MMP2 and MMP9 activities in RWPE-1 and PC3 cells and MMP2 in DU145 cells. TIMP-2 expression in RWPE-1 cells was upregulated after exposure. The cell invasion of all four tested cell lines was inhibited by exposure to 50 µM of finasteride, and migration inhibition only occurred for RWPE-1 and LNCaP cells. AR was expressed by LNCaP, RWPE-1 and PC3 cells.

Conclusions

Although the debate on the higher incidence of high-grade prostate cancer among 5-ARI-treated patients remains, our findings indicate that finasteride may attenuate tumor aggressiveness and invasion, which could vary depending on the androgen responsiveness of a patient’s prostate cells.     

Combination Therapy of VEGF-Trap and Gemcitabine Results in Improved Anti-Tumor Efficacy in a Mouse Lung Cancer Model

Background

Angiogenesis is essential for the growth and metastasis of cancer. Although anti-angiogenic agents, particularly vascular endothelial growth factor (VEGF) inhibitors, have exhibited single-agent activity, there is considerable interest in combining these novel drugs with conventional chemotherapy reagents to achieve an optimal clinical efficacy. The objective of this study was to evaluate the benefits of the combination therapy of vascular endothelial growth factor trap (VEGF-Trap) with gemcitabine in a lung tumor model.

Methods

A luciferase-expressing Lewis lung carcinoma (LLC) model was established in C57BL/6J mice and tumor-bearing mice were randomized into control, VEGF-Trap, gemcitabine and VEGF-Trap/gemcitabine combination groups. Tumor growth and animal survival were monitored. Tumor microvessel density and cell proliferation were evaluated by CD31 and Ki-67 immunohistochemical analysis. TUNEL assay was performed to detect apoptotic cells. The protein levels of Cyclin D1, Pro-Caspase-3, Bcl-2, MMP2 and MMP9 in tumor extracts were examined by western blot.

Results

VEGF-Trap in combination with gemcitabine showed significantly enhanced inhibition of tumor growth and prolonged mouse survival compared to the VEGF-Trap or gemcitabine monotherapy. The VEGF-Trap/gemcitabine combination therapy not only potently inhibited tumor angiogenesis and cell proliferation, but also increased cellular apoptosis within tumor tissues. In addition, the combination treatment markedly down-regulated the expression of proliferation, anti-apoptosis and invasion related proteins.

Conclusion

Combination therapy using VEGF-Trap and gemcitabine resulted in improved anti-tumor efficacy in a lung cancer model and VEGF-Trap/gemcitabine combination might represent a promising strategy in the treatment of human lung cancer.     

Planning and monitoring of patients for electrical cardioversion for atrial fibrillation

Objectives

This study evaluated the waiting list for elective electrical cardioversion (ECV) for persistent atrial fibrillation (AF), focusing on when and why procedures were postponed. We compared the effects of management of the waiting list conducted by physicians versus management by nurse practitioners (NPs) and we evaluated the safety of our anticoagulating policy by means of bleeding or thromboembolic complications during and after ECV.

Background

Not all patients selected for ECV receive their treatment at the first planned instance due to a variety of reasons. These reasons are still undocumented.

Methods

We evaluated 250 consecutive patients with persistent AF admitted to our clinic for elective ECV.

Results

Within 5 to 6 weeks, 186 of 242 patients (77%) received ECV. The main reason for postponing an ECV was an inadequate international normalised ratio (INR); other reasons included spontaneous sinus rhythm and switch to rate control. A total of 23 of the 147 patients (16%) managed by the research physician were postponed due to an inadequate INR at admission versus 4 out of 98 patients (4%) managed by NPs (p = 0.005)

Conclusion

An inadequate INR is the main reason for postponing an ECV. Management of ECV by NPs is safe and leads to less postponing on admission.     

Neuroprotective effect of transplanted human embryonic stem cell-derived neural precursors in an animal model of multiple sclerosis

Background

Multiple sclerosis (MS) is an immune mediated demyelinating disease of the central nervous system (CNS). A potential new therapeutic approach for MS is cell transplantation which may promote remyelination and suppress the inflammatory process.

Methods

We transplanted human embryonic stem cells (hESC)-derived early multipotent neural precursors (NPs) into the brain ventricles of mice induced with experimental autoimmune encephalomyelitis (EAE), the animal model of MS. We studied the effect of the transplanted NPs on the functional and pathological manifestations of the disease.

Results

Transplanted hESC-derived NPs significantly reduced the clinical signs of EAE. Histological examination showed migration of the transplanted NPs to the host white matter, however, differentiation to mature oligodendrocytes and remyelination were negligible. Time course analysis of the evolution and progression of CNS inflammation and tissue injury showed an attenuation of the inflammatory process in transplanted animals, which was correlated with the reduction of both axonal damage and demyelination. Co-culture experiments showed that hESC-derived NPs inhibited the activation and proliferation of lymph node–derived T cells in response to nonspecific polyclonal stimuli.

Conclusions

The therapeutic effect of transplantation was not related to graft or host remyelination but was mediated by an immunosuppressive neuroprotective mechanism. The attenuation of EAE by hESC-derived NPs, demonstrated here, may serve as the first step towards further developments of hESC for cell therapy in MS.     

Plant Extract Synthesized PLA Nanoparticles for Controlled and Sustained Release of Quercetin: A Green Approach

Background

Green synthesis of metallic nanoparticles (NPs) has been extensively carried out by using plant extracts (PEs) which have property of stabilizers/ emulsifiers. To our knowledge, there is no comprehensive study on applying a green approach using PEs for fabrication of biodegradable PLA NPs. Conventional methods rely on molecules like polyvinyl alcohol, polyethylene glycol, D-alpha-tocopheryl poly(ethylene glycol 1000) succinate as stabilizers/emulsifiers for the synthesis of such biodegradable NPs which are known to be toxic. So, there is urgent need to look for stabilizers which are biogenic and non-toxic. The present study investigated use of PEs as stabilizers/emulsifiers for the fabrication of stable PLA NPs. Synthesized PLA NPs through this green process were explored for controlled release of the well known antioxidant molecule quercetin.

Methodology/Principal Findings

Stable PLA NPs were synthesized using leaf extracts of medicinally important plants like Syzygium cumini (1), Bauhinia variegata (2), Cedrus deodara (3), Lonicera japonica (4) and Eleaocarpus sphaericus (5). Small and uniformly distributed NPs in the size range 70±30 nm to 143±36 nm were formed with these PEs. To explore such NPs for drugs/ small molecules delivery, we have successfully encapsulated quercetin a lipophilic molecule on a most uniformly distributed PLA-4 NPs synthesized using Lonicera japonica leaf extract. Quercetin loaded PLA-4 NPs were observed for slow and sustained release of quercetin molecule.

Conclusions

This green approach based on PEs mediated synthesis of stable PLA NPs pave the way for encapsulating drug/small molecules, nutraceuticals and other bioactive ingredients for safer cellular uptake, biodistribution and targeted delivery. Hence, such PEs synthesized PLA NPs would be useful to enhance the therapeutic efficacy of encapsulated small molecules/drugs. Furthermore, different types of plants can be explored for the synthesis of PLA as well as other polymeric NPs of smaller size.     

Epigenetically induced changes in nuclear textural patterns and gelatinase expression in human fibrosarcoma cells

Objective

Chromatin texture patterns of tumour cell nuclei can serve as cancer biomarkers, either to define diagnostic classifications or to obtain relevant prognostic information, in a large number of human tumours. Epigenetic mechanisms, mainly DNA methylation and histone post‐translational modification, have been shown to influence chromatin packing states, and therefore nuclear texture. The aim of this study was to analyse effects of these two mechanisms on chromatin texture, and also on correlation with gelatinase expression, in human fibrosarcoma tumour cells.

Materials and methods

We investigated effects of DNA hypomethylating agent 5‐aza‐2′‐deoxycytidine (5‐azadC) and histone deacetylase inhibitor trichostatin A (TSA) on nuclear textural characteristics of human HT1080 fibrosarcoma cells, evaluated by image cytometry, and expression of gelatinases MMP‐2 and MMP‐9, two metalloproteinases implicated in cancer progression and metastasis.

Results

5‐azadC induced significant variation in chromatin higher order organization, particularly chromatin decondensation, associated with reduction in global DNA methylation, concomitantly with increase in MMP‐9, and to a lesser extent, MMP‐2 expression. TSA alone did not have any effect on HT1080 cells, but exhibited differential activity when added to cells treated with 5‐azadC. When treated with both drugs, nuclei had higher texture abnormalities. In this setting, reduction in MMP‐9 expression was observed, whereas MMP‐2 expression remained unaffected.

Conclusions

These data show that hypomethylating drug 5‐azadC and histone deacetylase inhibitor TSA were able to induce modulation of higher order chromatin organization and gelatinase expression in human HT1080 fibrosarcoma cells.

     

Association between polymorphisms in the promoter regions of matrix metalloproteinases (MMPs) and risk of cancer metastasis: a meta-analysis

Background

A variety of studies have evaluated the associations between polymorphisms in the promoter regions of Matrix metalloproteinases (MMPs) and cancer metastasis. However, the results remain inconclusive. To better understand the roles of MMP polymorphisms in metastasis, we conducted a comprehensive meta-analysis.

Methods

Electronic databases were searched (from January 2000 to June 2011) for any MMP genetic association studies in metastasis. Overall and subgroup analyses were performed. Odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the associations between MMP polymorphisms and metastasis. Statistical analysis was performed with Review Manager 5.0 and STATA11.0.

Results

Thirty-three studies addressing five MMP polymorphisms were analyzed among 10,516 cancer cases (4,059 metastasis-positive cases and 6,457 metastasis-negative cases). For MMP1 (−1607)1G/2G, genotype 2G/2G increased the overall risk of metastasis under the recessive model (OR = 1.44, 95% CI = 1.05–1.98). In subgroup analysis based on cancer type, associations were found in head/neck and breast cancer under the recessive model, and also in breast cancer under the dominant model. For MMP3 (−1171) 5A/6A, the polymorphism decreased the overall risk of metastasis under two genetic models (recessive: OR = 0.80, 95%CI = 0.64–0.99, dominant: OR = 0.72, 95%CI = 0.56–0.93). The polymorphisms of MMP7 (−181) A/G and MMP9 (−1562) C/T increased metastatic risk. However, no association was observed between MMP2 (−1306) C/T and metastasis.

Conclusions

Our investigations demonstrate that polymorphisms in the promoter regions of MMP1, 3, 7 and 9 might be associated with metastasis in some cancers. Further studies with large sample size for MMP2 should be conducted.     

Advances and future of Radiation Oncology

Aim

Review of recent advances and vision for future developments in clinical practice of Radiation Oncology.

Background

There have been substantial research and technological developments in Radiation Oncology over the past 40 years.

Materials and methods

The relevant literature was reviewed and the authors offer their perspective on future opportunities for advancement in Radiation Oncology.

Conclusions

Significant innovative technological developments have been introduced in the practice of Radiation Oncology, with more precise target delineation and tracking and three dimensional treatment planning, optimal delivery of radiation therapy to the target and lower doses to surrounding Organs at Risk. This dose optimization and adaptive therapy have enhanced the role of Radiation Therapy to more effectively treat patients with cancer. Further creativity and refinements will continue to advance the field into new applications of ionizing radiations in cancer therapy.     

Development of a Novel PET Tracer [18F]AlF-NOTA-C6 Targeting MMP2 for Tumor Imaging

Background and Objective

The overexpression of gelatinases, that is, matrix metalloproteinase MMP2 and MMP9, has been associated with tumor progression, invasion, and metastasis. To image MMP2 in tumors, we developed a novel ligand termed [¹⁸F]AlF-NOTA-C6, with consideration that: c(KAHWGFTLD)NH₂ (herein, C6) is a selective gelatinase inhibitor; Cy5.5-C6 has been visualized in many in vivo tumor models; positron emission tomography (PET) has a higher detection sensitivity and a wider field of view than optical imaging; fluorine-18 (¹⁸F) is the optimal PET radioisotope, and the creation of a [¹⁸F]AlF-peptide complex is a simple procedure.

Methods

C6 was conjugated to the bifunctional chelator NOTA (1, 4, 7-triazacyclononanetriacetic acid) for radiolabeling [¹⁸F]AlF conjugation. The MMP2-binding characteristics and tumor-targeting efficacy of [¹⁸F]AlF-NOTA-C6 were tested in vitro and in vivo.

Results

The non-decay corrected yield of [¹⁸F]AlF-NOTA-C6 was 46.2–64.2%, and the radiochemical purity exceeded 95%. [¹⁸F]AlF-NOTA-C6 was favorably retained in SKOV3 and PC3 cells, determined by cell uptake. Using NOTA-C6 as a competitive ligand, the uptake of [¹⁸F]AlF-NOTA-C6 in SKOV3 cells decreased in a dose-dependent manner. In biodistribution and PET imaging studies, higher radioactivity concentrations were observed in tumors. Pre-injection of C6 caused a marked reduction in tumor tissue uptake. Immunohistochemistry showed MMP2 in tumor tissues.

Conclusions

[¹⁸F]AlF-NOTA-C6 was easy to synthesize and has substantial potential as an imaging agent that targets MMP2 in tumors.