In vitro and in vivo anticancer activity of a novel nano-sized formulation based on self-assembling polymers against pancreatic cancer

An overview of polyallylamine applications in gene delivery

A chief objective of gene transportation studies is to manipulate clinically accepted carriers that can be utilized to combat incurable diseases. Despite various strategies, efficiency and application of these vectors have been hindered, owing to different obstacles. Polyallylamine (PAA) is a synthetic water-soluble, weak base cationic polymer with different properties that could be administrated as an ideal candidate for biomedical applications such as gene delivery, drug delivery, or even tissue engineering. However, some intrinsic properties of this polymer limit its application. The two associated problems with the use of PAA in gene delivery are low transfection efficiency (because of low buffering capacity) and cytotoxic effects attributed to intense cationic character. Most of the strategies for structural modification of the PAA structure have focused on introducing hydrophobic groups to the polymeric backbone that target both cytotoxicity and transfection. In this perspective, we concentrate on PAA as a gene delivery vehicle and the existing approaches for modification of this cationic polymer to give insight to researchers for exploitation of PAA as an efficient carrier in biomedical applications.

Thermally reactive N-(2-hydroxypropyl)methacrylamide (HPMA) amphiphiles for drug solubilisation

Thermally active polymers, can respond structurally to temperature changes, making them interesting as potential drug delivery vehicles. Polymers of N-(3-aminopropyl) methacrylamide hydrochloride (APMA) are cationic with primary amine groups in their structure, which have been explored in biomedical applications via post-polymerisation modifications. In this work, we synthesised amphiphilic APMA monomers using hydrophobic pendant groups via conjugation onto their primary amine group. The pendant groups chosen in this study were palmitoyl, dansyl and cholesteryl moieties. The amphiphilic monomers were subsequently copolymerized with N-(2-hydroxypropyl)methacrylamide (HPMA) using varied monomer feed ratios resulting in a thermo-responsive system. The ability of the resultant aggregates in aqueous solution to encapsulate and liberate model drugs (e.g., propofol, griseofulvin and prednisolone) was then determined. Our data showed that the HPMA based formulations were capable of loading the model drug molecules inside their lipophilic core; HPMA-co-(APMA-Dansyl 2%) exhibited the largest drug encapsulation ability. Subsequently, poly(ethylene glycol) (PEG) was incorporated into the intrinsic polymer structure. This resulted in a more rapid drug release profile, whereby 100% of griseofulvin and prednisolone were liberated after only 4 h, which was only 5% and 10% before the PEG inclusion, respectively. Similarly, propofol showed 70% liberation from the polymer aggregate after 24 h, compared with only 30% liberation pre-PEGylation. These studies give an insight into the potential of the HMPA based amphiphiles as thermally responsive cargo carrier/release systems which could be exploited in the delivery of poorly soluble drugs.

Therapeutic resistance of pancreatic cancer: Roadmap to its reversal

Pancreatic cancer is a lethal disease with limited opportunity for resectable surgery as the first choice for cure due to its late diagnosis and early metastasis. The desmoplastic stroma and cellular genetic or epigenetic alterations of pancreatic cancer impose physical and biological barriers to effective therapies, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Here, we review the current therapeutic options for pancreatic cancer, and underlying mechanisms and potential reversal of therapeutic resistance, a hallmark of this deadly disease.

Nanoparticles in Gastrooncology

BACKGROUND

Gastrointestinal malignancies have the greatest incidence and cancer-associated death rates worldwide. Routine therapeutic modalities include surgery, chemotherapy and radiation but they often fail to reach the goal of cancer-free survival.

SUMMARY

In the light of this urgent medical need for the treatment of GI tumors, nanotech-nology-based approaches, i.e. nanomedicine, promise new therapeutic options. Using nanoparticles instead of classically designed drugs, targeting anticancer agents directly to the tumor site may revolutionize both diagnostic and therapeutic tools thereby facilitating the identification and elimination of malignant cells. Importantly, diagnostic insight and therapeutic effects can be achieved simultaneously through the same nanoparticle. Additionally, a nanoparticle may be loaded with more than one agent, thereby further increasing the value and power of the nanotechnology approach in oncologic therapeutic concepts. Although most insight into mechanisms of nanomedicine has been gained from in vitro and preclinical in vivo models, few clinical trials have been conducted, and nanomedicine-based concepts are already part of standard treatment algorithms. However, despite substantial progress it remains a challenge to design nanoparticles that feature all desirable characteristics at the same time.

KEY MESSAGES

This review seeks to provide substantial insight into the current status of nanomedicine-based approaches employed for diagnostic and/or therapeutic purposes in the field of gastrointestinal cancers by highlighting achievements and pointing out unresolved issues that need to be further addressed by future research attempts.

Tumor-stromal crosstalk in pancreatic cancer and tissue fibrosis

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with high morbidity and mortality worldwide. To date, limited therapeutic achievements targeting cell proliferation and related mechanisms has led researchers to focus on the microenvironment where pancreatic cancers develop. The anomalous proliferation of stromal cells, such as pancreatic stellate cells, and an increased deposition of altered matrix proteins create an environment that facilitates tumor growth, metastasis and drug resistance. Here, we summarize our understanding of recent advances in research about the role of fibrosis in pancreatic cancer progression, with particular emphasize on the involvement of fibrotic machineries such as wound healing, extra cellular matrix degradation, and epithelial-to-mesenchymal transition. The precise influence of these mechanisms on the biological behaviors and growth of cancer cells has great impact on clinical therapy and therefore deserves more attention. We also discuss the role of various stromal components in conferring drug resistance to PDAC which further worsening the pessimistic disease prognosis. A more in depth understanding of cancer-stroma crosstalk within the tumor microenvironment and stroma based clinical and translational therapies may provide new therapeutic strategies for the prevention of pancreatic cancer progression.

Reviewing two decades of nanomedicine implementations in targeted treatment and diagnosis of pancreatic cancer: An emphasis on state of art

Pancreatic cancer is nowadays the most life-threatening cancer type worldwide. The problem of poor diagnosis, anti-neoplastics resistance and biopharmaceutical drawbacks of effective anti-cancer drugs lead to worsen disease state. Nanotechnology-based carrier systems used in both imaging and treatment procedures had solved many of these problems. It is critical to develop advanced detection method to save patients from being too late diagnosed. Targeting the pancreatic cancer cells as well helped in decreasing the side effects associated with normal cells destruction. Drug resistance is another challenge in pancreatic cancer management that can be solved by thorough understanding of the microenvironment associated with the disease to design creative nanocarriers. This is the first article to review multifaceted approaches of nanomedicine in pancreatic cancer detection and management. Additionally, mortality rates in selected Arab and European countries were illustrated herein. An emphasis was given on therapeutic and diagnostic challenges and different nanotechnologies adopted to overcome. The four main approaches encompassed nanomedicine for herbal treatment, nanomedicine of synthetic anti-cancer drugs, metal nanoparticles as a distinct treatment policy and nanotechnology for cancer diagnosis. Future research perspectives have been finally proposed.

A Novel PAA Derivative with Enhanced Drug Efficacy in Pancreatic Cancer Cell Lines

Nanoparticles have been shown to be effective drug carriers in cancer therapy. Pancreatic cancer forms dense tumours which are often resistant to drug molecules. In order to overcome such multidrug resistance, new drug entities, novel delivery systems and combination therapy strategies are being explored. In this paper, we report the design and synthesis of a poly(allylamine)-based amphiphile modified with hydrophobic naphthalimido pendant groups. Bisnaphthalimide compounds have been shown to possess anticancer activity. The potential of this polymer to encapsulate, solubilize and enhance drug (5-fluorouricil and bis-(naphthalimidopropyl)-diaminooctane) cytotoxicity in BxPC-3 cells was evaluated. Our studies showed that the insoluble drugs could be formulated up to 4.3 mg mL-1 and 2.4 mg mL-1 inside the amphiphiles, respectively. Additionally, the novel poly(allylamine)-naphthalimide carrier resulted in an amplification of cytotoxic effect with drug treatment after 24 h, and was capable of reduction of 50% cell population at concentrations as low as 3 μg mL-1.

Stimuli Responsive Polymeric Systems for Cancer Therapy

Nanoscale polymers systems have dominated the revolution of drug delivery advancement. Their potential in the fight against cancer is unrivalled with other technologies. Their functionality increase, targeting ability and stimuli responsive nature have led to a major boom in research focus. This review article concentrates on the use of these smart polymers in cancer therapy. Nanotechnologies have shown potential as drug carriers leading to increased drug efficacy and penetration. Multifunctional smart carriers which can release their payload upon an external or internal trigger such as pH or temperature are proving to be major frontrunners in the development of effective strategies to overcome this disease with minimal patient side effects.

Dual Acting Polymeric Nano-Aggregates for Liver Cancer Therapy

Liver cancer treatments are often hindered by poor drug physicochemical properties, hence there is a need for improvement in order to increase patient survival and outlook. Combination therapies have been studied in order to evaluate whether increased overall efficacy can be achieved. This study reports the combined treatment of liver cancer cells with a combination treatment of chemotherapeutic agent paclitaxel and pro-apoptotic protein cytochrome C. In order to administer both agents in a single formulation, a poly(allylamine)-based amphiphile has been fabricated with the incorporation of a hybrid iron oxide-gold nanoparticle into its structure. Here, the insoluble paclitaxel becomes incorporated into the hydrophobic core of the self-assemblies formed in an aqueous environment (256 nm), while the cytochrome C attaches irreversibly onto the hybrid nanoparticle surface via gold-thiol dative covalent binding. The self-assemblies were capable of solubilising up to 0.698 mg/mL of paclitaxel (700-fold improvement) with 0.012 mg/mL of cytochrome C also attached onto the hybrid iron oxide-gold nanoparticles (HNPs) within the hydrophobic core. The formulation was tested on a panel of liver cancer cells and cytotoxicity was measured. The findings suggested that indeed a significant improvement in combined therapy (33-fold) was observed when compared with free drug, which was double the enhancement observed after polymer encapsulation without the cytochrome C in hepatocellular carcinoma (Huh-7D12) cells. Most excitingly, the polymeric nanoparticles did result in improved cellular toxicity in human endothelian liver cancer (SK-hep1) cells, which proved completely resistant to the free drug.

Investigation into Improving the Aqueous Solubility of the Thieno[2,3-b]pyridine Anti-Proliferative Agents

It is now established that the thieno[2,3-b]pyridines are a potent class of antiproliferatives. One of the main issues encountered for their clinical application is their low water solubility. In order to improve this, two strategies were pursued. First, a morpholine moiety was tethered to the molecular scaffold by substituting the sulphur atom with nitrogen, resulting in a 1H-pyrrolo[2,3-b]pyridine core structure. The water solubility was increased by three orders of magnitude, from 1.2 µg/mL (1-thieno[2,3-b]pyridine) to 1.3 mg/mL (3-pyrrolo[2,3-b]pyridine), however, it was only marginally active against cancer cells. The second strategy involved loading a very potent thieno[2,3-b]pyridine derivative (2) into a cholesteryl-poly(allylamine) polymer matrix for water solubilisation. Suppression of human pancreatic adenocarcinoma (BxPC-3) viability was observed to an IC₅₀ value of 0.5 μg/mL (1.30 μM) in conjunction with the polymer, which is a five-fold (×5) increase in potency as compared to the free drug alone, demonstrating the utility of this formulation approach.

Nanotechnologies in Pancreatic Cancer Therapy

Pancreatic cancer has been classified as a cancer of unmet need. After diagnosis the patient prognosis is dismal with few surviving over 5 years. Treatment regimes are highly patient variable and often the patients are too sick to undergo surgical resection or chemotherapy. These chemotherapies are not effective often because patients are diagnosed at late stages and tumour metastasis has occurred. Nanotechnology can be used in order to formulate potent anticancer agents to improve their physicochemical properties such as poor aqueous solubility or prolong circulation times after administration resulting in improved efficacy. Studies have reported the use of nanotechnologies to improve the efficacy of gemcitabine (the current first line treatment) as well as investigating the potential of using other drug molecules which have previously shown promise but were unable to be utilised due to the inability to administer through appropriate routes-often related to solubility. Of the nanotechnologies reported, many can offer site specific targeting to the site of action as well as a plethora of other multifunctional properties such as image guidance and controlled release. This review focuses on the use of the major nanotechnologies both under pre-clinical development and those which have recently been approved for use in pancreatic cancer therapy.

Diels Alder-mediated release of gemcitabine from hybrid nanoparticles for enhanced pancreatic cancer therapy

Hybrid nanoparticles (HNPs) have shown huge potential as drug delivery vehicles for pancreatic cancer. Currently, the first line treatment, gemcitabine, is only effective in 23.8% of patients. To improve this, a thermally activated system was developed by introducing a linker between HNPs and gemcitabine. Whereby, heat generation resulting from laser irradiation of the HNPs promoted linker breakdown resulting in prodrug liberation. In vitro evaluation in pancreatic adenocarcinoma cells, showed the prodrug was 4.3 times less cytotoxic than gemcitabine, but exhibited 11-fold improvement in cellular uptake. Heat activation of the formulation led to a 56% rise in cytotoxicity causing it to outperform gemcitabine by 26%. In vivo the formulation outperformed free gemcitabine with a 62% reduction in tumor weight in pancreatic xenografts. This HNP formulation is the first of its kind and has displayed superior anti-cancer activity as compared to the current first line drug gemcitabine after heat mediated controlled release.

Thermally triggered theranostics for pancreatic cancer therapy

Hybrid iron oxide-gold nanoparticles (HNPs) show the ability to bind drugs onto their surface with a triggered release at elevated temperatures. The iron oxide core allows for diagnostic imaging whilst heating of the gold shell upon laser irradiation reverses drug binding. This study exploits the reversible binding of novel polyamine based drugs in order to provide a specific and effective method for pancreatic cancer treatment. Here we used a novel bisnaphthalamido (BNIP) based drug series. Our hybrid nanoparticles (50 nm) showed the ability to load drugs onto their surface (3 : 1 : 0.25, drug : Fe : Au). By exploiting the surface-to-drug electrostatic interaction of a range of BNIP agents, heat triggered drug release was achieved. A 12-fold reduction in IC₅₀ after 24 h in vitro and a 5-fold reduction of tumour retardation in vivo compared with free drug in pancreatic models after treatment were achieved with the HNP-formulation and laser irradiation. This heat activated system could provide a key platform for future therapeutic strategies.

Development and validation of HPLC method with fluorometric detection for quantification of bisnaphthalimidopropyldiaminooctane in animal tissues following administration in polymeric nanoparticles

A simple, sensitive and specific high-performance liquid chromatography method for the quantification of bisnaphthalimidopropyldiaminooctane (BNIPDaoct), a potent anti-Leishmania compound, incorporated into poly(d,l-lactide-co-glycolic acid) (PLGA) nanoparticles was developed and validated toward bioanalysis application. Biological tissue extracts were injected into a reversed-phase monolithic column coupled to a fluorimetric detector (λexc=234nm, λem=394nm), using isocratic elution with aqueous buffer (acetic acid/acetate 0.10M, pH 4.5, 0.010M octanesulfonic acid) and acetonitrile, 60:40 (v/v) at a flow rate of 1.5mLmin(-1). The run time was 6min, with a BNIPDaoct retention time of 3.3min. Calibration curves were linear for BNIPDaoct concentrations ranging from 0.002 to 0.100μM. Matrix effects were observed and calibration curves were performed using the different organ (spleen, liver, kidney, heart and lung) extracts. The method was found to be specific, accurate (97.3-106.8% of nominal values) and precise for intra-day (RSD<1.9%) and inter-day assays (RSD<7.2%) in all matrices. Stability studies showed that BNIPDaoct was stable in all matrices after standing for 24h at room temperature (20°C) or in the autosampler, and after three freeze-thaw cycles. Mean recoveries of BNIPDaoct spiked in mice organs were >88.4%. The LOD and LOQ for biological matrices were ≤0.8 and ≤1.8nM, respectively, corresponding to values ≤4 and ≤9nmolg(-1) in mice organs. The method developed was successfully applied to biodistribution assessment following intravenous administration of BNIPDaoct in solution or incorporated in PLGA nanoparticles.

A review on comb-shaped amphiphilic polymers for hydrophobic drug solubilization

Comb-shaped amphiphilic polymers are rapidly emerging as an alternative approach to amphiphilic block copolymers for hydrophobic drug solubilization. These polymers consist of a homopolymer or copolymer backbone to which hydrophobic and hydrophilic pendant groups can be grafted resulting in a comb-like architecture. The hydrophobic pendants may consist of homopolymers, copolymers and other low-molecular weight hydrophobic structures. In this review, we focus on hydrophobically modified preformed homopolymers. Comb-shaped amphiphilic polymers possess reduced critical aggregation concentration values compared with traditional surfactant micelles indicating increased stability with decreased disruption experienced on dilution. They have been fabricated with diverse architectures and multifunctional properties such as site-specific targeting and external stimuli-responsive nature. The application of comb-shaped amphiphilic polymers is expanding; here we report on the progress achieved so far in hydrophobic drug solubilization for both intravenous and oral delivery.

HDAC gene expression in pancreatic tumor cell lines following treatment with the HDAC inhibitors panobinostat (LBH589) and trichostatine (TSA)

BACKGROUND

In this study, the effect of LBH589 and trichostatin (TSA), a standard histone deacetylase inhibitor (HDACi) toward the growth of pancreatic cancer cell lines was studied. Thus, we examined for the first time, the HDAC family gene expression levels before and after drug treatment.

METHODS

Several human pancreatic cancer cell lines (Panc-1, BxPC-3, SOJ-6) and a normal human pancreatic duct immortalized epithelial cell line (HPDE/E6E7) were used as target cells. The cell growth was measured by MTT assay, cell cycle alteration, membrane phosphatidylserine exposure, DNA fragmentation, mitochondrial membrane potential loss, RT-PCR and Western blots were done using standard methods. The effect of drugs on tumor growth in vivo was studied using subcutaneous xenograft model.

RESULTS

Except in the case of certain HDAC gene/tumor cell line couples: (SIRT1/HPDE-SOJ6/TSA- or LBH589-treated cells; LBH589-treated Panc-1 Cells; HDAC2/BxPC-3/LBH589-treated cells or TSA-treated SOJ-6-1 cells), there were no major significant changes of HDACs genes transcription in cells upon drug treatment. However, significant variation in HDACs and SIRTs protein expression levels could be seen among individual cell samples. The in vivo results showed that LBH589 formulation exhibited similar tumor reduction efficacy as the commercial drug gemcitabine.

CONCLUSION

Our data demonstrate that LBH589 induced the death of pancreatic tumor cell by apoptosis. In line with its in vitro activity, LBH589 achieved a significant reduction in tumor growth in BxPC-3 pancreatic tumor cell line subcutaneous xenograft mouse model. Furthermore, exploring the impact of LBH589 on HDACs encoding genes expression revealed for the first time that some of them, depending on the cell line considered, seem to be regulated during translation.

The influence of bisnaphthalimidopropyl polyamines on DNA instability and repair in Caco-2 colon epithelial cells

Bisnaphthalimido compounds bis-intercalate to DNA via the major groove and are potentially potent cancer therapeutics. Previously, we incorporated natural polyamines as linkers connecting the two naphthalimido ring moieties to create a series of soluble bisnaphthalimidopropyl polyamines (BNIPPs). Here, extending earlier work on bisnaphthalimidopropylspermidine (BNIPSpd)-induced apoptosis in colon adenocarcinoma Caco-2 cells, we compare the cytotoxicity and genotoxicity of BNIPSpd relative to the spermine and oxaspermine derivatives, bisnaphthalimidopropylspermine (BNIPSpm) and bisnaphthalimidopropyloxaspermine (BNIPOSpm). The order of cytotoxicity after 24 h was BNIPSpd (IC(50) = 0.47 μM) > BNIPSpm (IC(50) = 10.04 μM) > BNIPOSpm (IC(50) >50 μM). After a 72-h BNIPOSpm exposure, an IC(50) = 10.25 μM was achieved. With 4-h exposure to BNIPSpd or BNIPSpm or 12-h exposure to BNIPOSpm, concentrations ≥1 μM induced a significant dose-dependent increase in DNA damage as measured by alkaline single-cell gel electrophoresis. The longer incubation times required for BNIPOSpm to induce DNA strand breaks reflect a slower rate of BNIPOSpm cellular distribution as monitored via BNIPP fluorescence within the cells. Moreover, exposure to a non-genotoxic concentration of BNIPSpd, BNIPSpm (0.1 μM for 4 h) or BNIPOSpm (0.1 μM for 12 h) induced a significant decrease in repair of oxidative DNA damage induced by hydrogen peroxide. In conclusion, BNIPP exposure in Caco-2 cells is associated with significant induction of DNA damage and inhibition of DNA repair at non-genotoxic concentrations. The latter is a novel consequence of BNIPP-cell interactions which adds to the spectrum of therapeutically relevant activities that may be exploited for the design and development of naphthalimide-based therapeutics.