Inhibition of pulmonary metastasis in mice by all-trans retinoic acid incorporated in cationic liposomes

Effects of Anionic Liposome Delivery of All-Trans-Retinoic Acid on Neuroblastoma Cell Differentiation

All-trans-retinoic acid (ATRA) has long been known to affect cell growth and differentiation. To improve ATRA's therapeutic efficacy and pharmacodynamics, several delivery systems have been used. In this study, free ATRA and anionic-liposome-encapsulated ATRA were compared for their effects on SK-N-SH human neuroblastoma cell growth and differentiation. Anionic liposomes made of L-α-phosphatidylcholine (PC) and L-α-phosphatidic acid (PA), empty (PC-PA) and loaded with ATRA (PC-PA-ATRA), were characterized by dynamic light scattering (DLS) and electrophoretic mobility measurements, and drug entrapment efficiency (EE%) was measured to evaluate the applicability of the new colloidal formulation. The results of brightfield microscopy and cell growth curves indicated that ATRA, whether free or encapsulated, reduced growth and induced differentiation, resulting in SK-N-SH cells changing from epithelioid to neuronal-like morphologies, and producing a significant increase in neurite growth. To further characterize the neuro-differentiation of SK-N-SH cells, the expression of βIII-Tubulin and synaptophysin and mitochondria localization were analyzed via immunofluorescence. Increased expression of neuronal markers and a peculiar localization of mitochondria in the neuritic extensions were apparent both in ATRA- and PC-PA-ATRA-differentiated cells. As a whole, our results strongly indicate that ATRA treatment, by any means, can induce the differentiation of parent SK-N-SH, and they highlight that its encapsulation in anionic liposomes increases its differentiation ability in terms of the percentage of neurite-bearing cells. Interestingly, our data also suggest an unexpected differentiation capability of anionic liposomes per se. This work highlights the importance of developing and carefully testing novel delivery nanocarriers, which are a necessary first "step" in the development of new therapeutic settings.

Advances in Lung Cancer Treatment Using Nanomedicines

Carcinoma of the lungs is among the most menacing forms of malignancy and has a poor prognosis, with a low overall survival rate due to delayed detection and ineffectiveness of conventional therapy. Therefore, drug delivery strategies that may overcome undesired damage to healthy cells, boost therapeutic efficacy, and act as imaging tools are currently gaining much attention. Advances in material science have resulted in unique nanoscale-based theranostic agents, which provide renewed hope for patients suffering from lung cancer. Nanotechnology has vastly modified and upgraded the existing techniques, focusing primarily on increasing bioavailability and stability of anti-cancer drugs. Nanocarrier-based imaging systems as theranostic tools in the treatment of lung carcinoma have proven to possess considerable benefits, such as early detection and targeted therapeutic delivery for effectively treating lung cancer. Several variants of nano-drug delivery agents have been successfully studied for therapeutic applications, such as liposomes, dendrimers, polymeric nanoparticles, nanoemulsions, carbon nanotubes, gold nanoparticles, magnetic nanoparticles, solid lipid nanoparticles, hydrogels, and micelles. In this Review, we present a comprehensive outline on the various types of overexpressed receptors in lung cancer, as well as the various targeting approaches of nanoparticles.

Recent Advances in Lung Cancer Therapy Based on Nanomaterials: A Review

Lung cancer is one of the commonest cancers with a significant mortality rate for both genders, particularly in men. Lung cancer is recognized as one of the leading causes of death worldwide, which threatens the lives of over 1.6 million people every day. Although cancer is the leading cause of death in industrialized countries, conventional anticancer medications are unlikely to increase patients' life expectancy and quality of life significantly. In recent years, there are significant advances in the development and applications of nanotechnology in cancer treatment. The superiority of nanostructured approaches is that they act more selectively than traditional agents. This progress led to the development of a novel field of cancer treatment known as nanomedicine. Various formulations based on nanocarriers, including lipids, polymers, liposomes, nanoparticles and dendrimers have opened new horizons in lung cancer therapy. The application and expansion of nano-agents lead to an exciting and challenging research era in pharmaceutical science, especially for the delivery of emerging anti-cancer agents. The objective of this review is to discuss the recent advances in three types of nanoparticle formulations for lung cancer treatments modalities, including liposomes, polymeric micelles, and dendrimers for efficient drug delivery. Afterward, we have summarized the promising clinical data on nanomaterials based therapeutic approaches in ongoing clinical studies.

Liposome nano-formulation with cationic polar lipid DOTAP and cholesterol as a suitable pH-responsive carrier for molecular therapeutic drug (all-trans retinoic acid) delivery to lung cancer cells

The molecular targeted drug ATRA demands a suitable carrier that delivers to the cancer site due to its poor bioavailability and drug resistance. ATRA, being a lipid with carboxylic acid, has been nano‐formulated as a cationic lipo‐ATRA with DOTAP:cholesterol:ATRA (5:4:1) and its pH‐responsive release, intracellular drug accumulation, and anticancer effect on human lung cancer (A549) cell line analysed. The analysis of the physicochemical characteristics of the developed lipo‐ATRA (0.8 µmol) revealed that the size of 231 ± 2.35 d.nm had a zeta potential of 6.4 ± 1.19 and an encapsulation efficiency of 93.7 ± 3.6%. The ATRA release from lipo‐ATRA in vitro was significantly (p ≤ 0.05) higher at acidic pH 6 compared to pH 7.5. The intracellular uptake of ATRA into lipo‐ATRA‐treated A549 cells was seven‐fold higher (0.007 ± 0.001 mg/ml) while only three‐fold uptake was observed in free ATRA treatment (0.003 ± 0.002 mg/ml). The lipo‐ATRA treatment caused a highly significant (p ≤ 0.001) decrease in percent cell viability at 48 h when compared with the free ATRA treatment. Overall, the results proved that the developed lipo‐ATRA has suitable physicochemical properties with enhanced ATRA release at acidic pH, while maintaining stability at physiologic pH and temperature. This resulted in an increased ATRA uptake by lung cancer cells with enhanced treatment efficiency. Hence, it is concluded that DOTAP lipo‐ATRA is a suitable carrier for ATRA delivery to solid cancer cells.

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Current Trends in ATRA Delivery for Cancer Therapy

All-Trans Retinoic Acid (ATRA) is the most active metabolite of vitamin A. It is critically involved in the regulation of multiple processes, such as cell differentiation and apoptosis, by activating specific genomic pathways or by influencing key signaling proteins. Furthermore, mounting evidence highlights the anti-tumor activity of this compound. Notably, oral administration of ATRA is the first choice treatment in Acute Promyelocytic Leukemia (APL) in adults and NeuroBlastoma (NB) in children. Regrettably, the promising results obtained for these diseases have not been translated yet into the clinics for solid tumors. This is mainly due to ATRA-resistance developed by cancer cells and to ineffective delivery and targeting. This up-to-date review deals with recent studies on different ATRA-loaded Drug Delivery Systems (DDSs) development and application on several tumor models. Moreover, patents, pre-clinical, and clinical studies are also reviewed. To sum up, the main aim of this in-depth review is to provide a detailed overview of the several attempts which have been made in the recent years to ameliorate ATRA delivery and targeting in cancer.

All-trans retinoic acid reverses epithelial-mesenchymal transition in paclitaxel-resistant cells by inhibiting nuclear factor kappa B and upregulating gap junctions

Paclitaxel is a widely used chemotherapy drug, but development of resistance leads to treatment failure. Tumor cells that are treated with a sublethal dose of paclitaxel for a long period of time show the epithelial-mesenchymal transition (EMT) phenotype, which leads to metastasis and resistance. All-trans retinoic acid (ATRA) is always used in combination with paclitaxel and can reverse EMT in many types of cancer cells. The ability of ATRA to reverse EMT in chemoresistant cells is still unknown. In the present study, the ability of ATRA to reverse EMT in paclitaxel-resistant cells was investigated. Three colorectal cancer cell lines, HCT116, LoVo and CT26, were treated with sublethal doses of paclitaxel to create resistant cell lines. Western blotting, immunocytochemistry, and "parachute" dye-coupling assays showed that ATRA reverses EMT, inhibits nuclear factor kappa B (NF-κΒ), and upregulates gap junctions in paclitaxel-resistant cells. Scratch wound-healing and Transwell assays showed that ATRA decreases the migration and invasion abilities of paclitaxel-resistant cells. In addition, the CT26 cell line was used in the Balb/c pulmonary metastasis model to show that ATRA reduces metastasis of paclitaxel-resistant cells in vivo. Given these data, ATRA may reverse EMT by inhibiting NF-κΒ and upregulating gap junctions in paclitaxel-resistant cells.

Liposomes assembled from dimeric retinoic acid phospholipid with improved pharmacokinetic properties

All-trans-retinoic acid (ATRA) exhibits potent cytotoxicities against different cancer cells by binding to retinoic acid receptors (RARs), which is regarded as the first example of targeted therapy in acute promyelocytic leukemia (APL). However, its extensive clinical applications have been limited because of poor aqueous solubility, short half-life time and side effects. In this report, dimeric ATRA phosphorylcholine prodrug (Di-ATRA-PC) was designed and assembled into nanoliposomes to improve its pharmacokinetic properties. Di-ATRA-PC prodrug was synthesized by a facile esterification and characterized by mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). The Di-ATRA-PC assembled liposomes were prepared by thin film hydration method with ATRA loading efficiency up to 73wt%. The liposomes have a uniform particle size (73.1±3.6nm) with negatively charged surface (-20.5±2.5mV) and typical lipid bilayer structure as measured by dynamic light scattering (DLS), transmission electron microscope (TEM) and cryogenic transmission electron microscope (cryo-TEM). In vitro drug release study confirmed that Di-ATRA-PC liposomes could sustainedly release free ATRA in a weakly acidic condition. Furthermore, cellular uptake, MTT and cell apoptosis analysis demonstrated that the liposomes could be successfully internalized into tumor cells to induce apoptosis of MCF-7 and HL-60 cells. More importantly, in vivo pharmacokinetic assay indicated that Di-ATRA-PC liposomes had much longer retention time in comparison with ATRA. In conclusion, Di-ATRA-PC liposomal formulation could be a potential drug delivery system of ATRA with enhanced pharmacokinetic properties.

Anticancer activity of all-trans retinoic acid-loaded liposomes on human thyroid carcinoma cells

All-trans retinoic acid (ATRA) is an anti-tumor compound, exerting different anti-cancer effects on different types of cancer cells. Unfortunately, retinoids are also characterized by certain side effects following systemic administration, such as the burning of skin and general malaise. The highly variable degree of bioavailability of ATRA plus its tendency to induce its own destruction through metabolic degradation following oral treatment necessitate the development of alternative formulations. The aim of this work is to evaluate the physico-chemical properties of unilamellar, ATRA-containing liposomes and to investigate the cytotoxic activity of this potential nanomedicine on human thyroid carcinoma cells. Liposomes made up of DPPC/Chol/DSPE-mPEG2000 (6:3:1 molar ratio), characterized by a mean diameter of ∼200nm, a polydispersity index of 0.1 and a negative surface charge, were used as ATRA-carriers and their antiproliferative efficacy was investigated in comparison with the free drug on three different human thyroid carcinoma cell lines (PTC-1, B-CPAP, and FRO) through MTT-testing. The liposomes protected the ATRA against photodegradation and increased its antiproliferative properties due to the improvement of its cellular uptake. ATRA-loaded liposomes could be a novel formulation useful for the treatment of anaplastic thyroid carcinoma.

Cationic Supramolecular Vesicular Aggregates for Pulmonary Tissue Selective Delivery in Anticancer Therapy

The biopharmaceutical properties of supramolecular vesicular aggregates (SVAs) were characterized with regard to their physicochemical features and compared with cationic liposomes (CLs). Neutral and cationic SVAs were synthesized using two different copolymers of poly(aspartyl hydrazide) by thin-layer evaporation and extrusion techniques. Both copolymers were self-assembled in pre-formulated liposomes and formed neutral and cationic SVAs. Gemcitabine hydrochloride (GEM) was used as an anticancer drug and loaded by a pH gradient remote loading procedure, which significantly increased drug loading inside the SVAs. The resulting average size of the SVAs was 100 nm. The anticancer activity of GEM-loaded neutral and cationic SVAs was tested in human alveolar basal epithelial (A549) and colorectal cancer (CaCo-2) cells. GEM-loaded cationic SVAs increased the anticancer activity in A549 and CaCo-2 cells relative to free drug, neutral SVAs, and CLs. In vivo biodistribution in Wistar rats showed that cationic SVAs accumulate at higher concentrations in lung tissue than neutral SVAs and CLs. Cationic SVAs may therefore serve as an innovative future therapy for pulmonary carcinoma.

Anti-metastatic study of liposome-encapsulated all trans retinoic acid (ATRA) in B16F10 melanoma cells-implanted C57BL/6 mice

B16F10 cells-induced C57BL/6 mice were divided into several groups and the free all trans retinoic acid (ATRA) and liposome-encapsulated ATRA were given for 21 days. The encapsulated ATRA treatment lowered the oxidative stress and lipid profile near to the normal level in the drug-treated mice. Encapsulated ATRA treatment showed substantial decrease in serum cytokines and increase in lifespan when compared with free ATRA treatment. These results imply that the liposome-encapsulated ATRA may help to achieve a higher level of ATRA in comparison with free ATRA treatment and helps to enhance anticancer drug delivery in liposome-encapsulated ATRA treatment.

All-trans-retinoic acid counteract the tumor-stimulating effect of hepatectomy and increases survival of rats bearing liver metastases

BACKGROUND

We previously demonstrated a stimulating effect of hepatectomy on residual tumor cells after resection of liver metastases. The aim of this study was to analyze the effect of all-trans-retinoic acid (ATRA) on the protumor effect of hepatectomy and survival of hepatectomized rats bearing liver metastases. We also explored whether ATRA interfered with the tumor promoting effect of hepatotropic growth factors (GFs).

METHODS

The in vitro effect of ATRA on proliferation of S4MH rhabdomyosarcoma tumor cells was assessed when cultured with laparotomized or hepatectomized rat serum (HRS), or in the presence of GFs (hepatocyte growth factor, insulin growth factor 2, Platelet Derived Growth Factor (PDGF)-BB, and vascular endothelial growth factor). For the in vivo studies, rats were partially hepatectomized on day 10 after metastasis induction, one group being treated with ATRA from day 7 to 14, and a second receiving cyclophosphamide (CY; on days 10 and 14) alone or with ATRA. We determined the size and number of liver and lung metastases. Finally, we analyzed the effect of treatments on rat survival.

RESULTS

Hepatotropic GFs increased cell proliferation in a similar manner to HRS. In vitro, ATRA blocked the protumor effect of both HRS and GFs. In vivo, ATRA reduced the size and number of liver and lung metastases, and significantly increased rat survival. Furthermore, adding ATRA to CY significantly increased survival compared with CY alone.

CONCLUSIONS

In our model, ATRA minimizes the tumor-stimulating effect of hepatectomy, reducing the number and size of liver metastases and improving survival. The results suggest that the ATRA may be useful for blocking the growth-promoting effect of hepatotropic GFs released after liver metastasis resection.

All-trans retinoic acid-incorporated nanoparticles of deoxycholic acid-conjugated dextran for treatment of CT26 colorectal carcinoma cells

PURPOSE

All-trans retinoic acid (RA)-incorporated nanoparticles were prepared using deoxycholic acid-conjugated dextran (DexDA). Anticancer activity of RA-incorporated DexDA nanoparticles were tested in vitro and in vivo.

METHODS

RA-incorporated nanoparticles were prepared by dialysis. Antiproliferative and anti-invasive potential of RA-incorporated nanoparticles were studied using CT26 colorectal carcinoma cells.

RESULTS

RA-incorporated nanoparticles have small particle sizes of around 70-300 nm and spherical shapes. The higher drug-feeding ratio and higher substitution degree of deoxycholic acid in the conjugates resulted in higher drug contents, lower loading efficiency, and larger particle size. RA release rate became slower at higher drug contents and higher substitution degree of deoxycholic acid in the DexDA conjugates. The antiproliferation activity, anti-invasive activity, and matrix metalloproteinase 2 expression of RA-incorporated nanoparticles against CT26 cells in vitro was similar to RA. However, RA-incorporated nanoparticles had superior antimetastatic activity in an animal pulmonary metastatic model of CT26 cells compared to RA itself.

CONCLUSION

RA-incorporated nanoparticles showed similar anticancer activity in vitro and superior antimetastatic activity in vivo in a pulmonary metastatic model of CT26 cells. We suggest that RA-incorporated nanoparticles are promising vehicles for efficient delivery of RA.

Inhibition of metastatic lung cancer in C57BL/6 mice by liposome encapsulated all trans retinoic acid (ATRA)

The purpose of this study was to investigate whether all trans retinoic acid (ATRA) incorporated in liposome composed of distearoylphosphatidylcholine (DSPC/cholesterol) could inhibit the metastatic lung cancer in mice more efficiently than free ATRA. Metastatic lung cancer model was developed by intravenous injection of B16F10 cells and it is also referred as melanoma model. In this present study, C57BL/6 mice were divided into several groups as per experimental design and the free ATRA and liposome encapsulated ATRA were given for 21 days at a dose of 0.60 mg/kg body weight/day after cell line implantation. After 21 days, mice were sacrificed at different time interval for ATRA level analysis in serum and lung tissue by HPLC method and the remaining mice were kept for anticancer study. The ATRA level increased significantly in serum and lung tissue in liposome encapsulated ATRA treated mice. In cancer bearing mice, tumor nodule formation decreased and life span increased after receiving liposome encapsulated ATRA treatment than free ATRA treated mice. This result implies that the liposome encapsulated ATRA has maintained more ATRA concentration in lung tissue and showed more inhibition on the lung tumor nodule formation. The results indicate a possible use of liposome encapsulated ATRA in prevention of lung metastasis.

Hepatic vitamin A preloading reduces colorectal cancer metastatic multiplicity in a mouse xenograft model

Previous research in our laboratory showed that retinol inhibited all-trans retinoic acid (ATRA)-resistant human colon cancer cell invasion via a retinoic acid receptor-independent mechanism in vitro. The objective of the current study was to determine if dietary vitamin A supplementation inhibited metastasis of ATRA-resistant colon cancer cells in a nude mouse xenograft model. Female nude mice (BALB/cAnNCr-nu/nu, n = 14 per group) consumed a control diet (2,400 IU retinyl palmitate/kg diet) or a vitamin A supplemented diet (200,000 IU retinyl palmitate/kg diet) for 1 mo prior to tumor cell injection to preload the liver with vitamin A. HCT-116, ATRA-resistant, human colon cancer cells were intrasplenically injected. Mice continued to consume their respective diets for 5 wk following surgery. Consumption of supplemental vitamin A decreased hepatic metastatic multiplicity to 17% of control. Hepatic and splenic retinol and retinyl ester concentrations were significantly higher in the mice supplemented with vitamin A when compared to mice consuming the control diet. Supplemental vitamin A did not decrease body weight, feed intake, or cause toxicity. Thus, supplemental dietary vitamin A may decrease the overall number of hepatic metastasis resulting from colon cancer.

A clinically relevant bi-cellular murine mammary tumor model as a useful tool for evaluating the effect of retinoic acid signaling on tumor progression

BACKGROUND

The effect of retinoic acid (RA) on breast cancer progression is controversial. Our objective was to obtain information about breast cancer progression, taking advantage of the ER-negative murine mammary adenocarcinoma model LM38 (LM38-LP constituted by luminal (LEP) and myoepithelial-like cells (MEP), LM38-HP mainly composed of spindle-shaped epithelial cells, and LM38-D2 containing only large myoepithelial cells), and to validate the role of the retinoic acid receptors (RARs) in each cell-type compartment.

MATERIALS AND METHODS

We studied the expression and functionality of the RARs in LM38 cell lines. We analyzed cell growth and cell cycle distribution, apoptosis, the activity of proteases, motility properties, and expression of the molecules involved in these pathways. We also evaluated tumor growth and dissemination in vivo under retinoid treatment.

RESULTS

LM38 cell lines expressed most retinoic receptor isotypes that were functional. However, only the bi-cellular LM38-LP cells responded to retinoids by increasing RARβ2 and CRBP1 expression. The growth of LM38 cell sublines was inhibited by retinoids, first by inducing arrest in MEP cells, then apoptosis in LEP cells. Retinoids induced inhibitory effects on motility, invasiveness, and activity of proteolytic enzymes, mainly in the LM38-LP cell line. In in-vivo assays with the LM38-LP cell line, RA treatment impaired both primary tumor growth and lung metastases dissemination.

CONCLUSION

These in-vivo and in-vitro results show that to achieve maximum effects of RA on tumor progression both the LEP and MEP cell compartments have to be present, suggesting that the interaction between the LEP and MEP cells is crucial to full activation of the RARs.

Anti-tumor activity of all-trans retinoic acid-incorporated glycol chitosan nanoparticles against HuCC-T1 human cholangiocarcinoma cells

The aim of this study is to investigate antitumor activity of all-trans retinoic acid (RA)-incorporated glycol chitosan (GC) nanoparticles. RA-incorporated GC nanoparticles were prepared by electrostatic interaction between RA and amine group of GC. RA-incorporated GC nanoparticles have spherical shape and their particle size was 317 ± 34.5 nm. They were simply reconstituted into aqueous solution without changes of intrinsic properties. RA-incorporated GC nanoparticles were evidently inhibited the proliferation of HuCC-T1 cholangiocarcinoma cells at higher than 20 μg/ml of RA concentration while empty GC vegicles did not affect to the viablity of tumor cells. Apoptosis and necrosis analysis of tumor cells with treatment of RA or RA-incorporated GC nanoparticles also supported these results. Invasion test using Matrigel also showed that invasion of tumor cells was significantly inhibited at higher than 20 μg/ml of RA concentration. Wound healing assay also showed that RA-incorporated GC nanoparticles were inhibited migration of tumor cells as similar to RA itself. Our results suggested that RA-incorporated GC nanoparticles is a promising vehicles for RA delivery to HuCC-T1 cholangiocarcinoma cells.

Injectable lipid emulsions-advancements, opportunities and challenges

Injectable lipid emulsions, for decades, have been clinically used as an energy source for hospitalized patients by providing essential fatty acids and vitamins. Recent interest in utilizing lipid emulsions for delivering lipid soluble therapeutic agents, intravenously, has been continuously growing due to the biocompatible nature of the lipid-based delivery systems. Advancements in the area of novel lipids (olive oil and fish oil) have opened a new area for future clinical application of lipid-based injectable delivery systems that may provide a better safety profile over traditionally used long- and medium-chain triglycerides to critically ill patients. Formulation components and process parameters play critical role in the success of lipid injectable emulsions as drug delivery vehicles and hence need to be well integrated in the formulation development strategies. Physico-chemical properties of active therapeutic agents significantly impact pharmacokinetics and tissue disposition following intravenous administration of drug-containing lipid emulsion and hence need special attention while selecting such delivery vehicles. In summary, this review provides a broad overview of recent advancements in the field of novel lipids, opportunities for intravenous drug delivery, and challenges associated with injectable lipid emulsions.

Enhanced growth inhibition of metastatic lung tumors by intravenous injection of ATRA-cationic liposome/IL-12 pDNA complexes in mice

Interleukin 12 (IL-12) is a proinflammatory cytokine with antitumor activity. All-trans-retinoic acid (ATRA) exerts antitumor effects by regulating a variety of gene expressions, including tumor necrosis factor receptor 1 (TNFR1), increases the number of TNFR1 and potentiates TNF-alpha-induced apoptosis in cancer cells. In this study, ATRA-incorporated cationic liposome (ATRA-cationic liposome)/IL-12 plasmid DNA (pDNA) complexes were prepared to improve therapeutic efficacy of cationic liposome/IL-12 pDNA complexes in a mouse model of metastatic lung tumor after intravenous injection. IL-12 production in lungs by ATRA-cationic liposome/IL-12 pDNA complexes was comparable with that by cationic liposome/IL-12 pDNA complexes. The number of metastatic tumor cells (colon26/Luc) was quantitatively evaluated by measuring luciferase activity. ATRA-cationic liposome/IL-12 pDNA complexes reduced the number of colon26/Luc cells and tumor nodules in lungs. ATRA-cationic liposome/IL-12 pDNA complexes significantly prolonged the survival time of mice, whereas cationic liposome/IL-12 pDNA only slightly prolonged it. ATRA-cationic liposome/IL-12 pDNA complexes increased the TNFR1 mRNA upregulation and the number of apoptotic cells in the lung. Moreover, reduced serum alanine transaminase (ALT) and aspartate transaminase (AST) activities were observed in mice treated with ATRA-cationic liposome/IL-12 pDNA complexes. These results suggest that intravenous injection of ATRA-cationic liposome/IL-12 pDNA complexes is an effective method for the treatment of lung metastasis in mice.

Therapeutic effects of all trans-retinoic acid combined with transarterial chemoembolization on Walker-256 hepatoma in rats

In order to investigate the inhibitory effects of all trans-retinoic acid (ATRA) on differentiation and apoptosis of Walker-256 hepatocellular carcinoma cells and the therapeutic effects of ATRA combined with transarterial chemoembolization (TACE) on rat Walker-256 transplanted hepatocarcinoma, Walker-256 hepatocarcinoma cell lines were treated with ATRA at different concentrations. After culture for 48 h, the inhibitory rate of cell proliferation was determined by MTT assay; the changes of Fas and Bcl-2 mRNA expression were determined by RT-PCR, and the expression levels of Caspase3 and Caspase8 proteins were detected by Western blot. Twenty-seven Wistar rat models of hepatocarcinoma were set up successfully by implanting Walker-256 cell lines. The tumor volume at the 11th day after implantation (V(preoperation)) was measured by magnetic resonance imaging (MRI). The 27 rats were randomly and equally divided into three groups, and the therapy scheme was performed as follows: group A (ATRA 0.1 mg+mitomycin 0.05 mL+lipiodol 0.05 mL+gelfoam powder 0.025 mg); group B (mitomycin 0.05 mg+lipiodol 0.05 ml+gelfoam 0.025 mg; group C (0.9% NaCl 0.2 mL). After another 11 days, MRI was performed once again to measure the tumor volume (V(postoperation)). The expression of factor and Ki VIII -67 in the tumor tissues was detected by immunohistochemistry. The results showed that ATRA could suppress proliferation of Walker-256 cell lines. After treatment of Walker-256 cell lines with ATRA, the expression of Fas mRNA was significantly up-regulated and the Bcl-2 mRNA was significantly down-regulated by ATRA at the concentration of 10 mumol/L as compared with the control group (P<0.05). After treatment with 10 mumol/L ATRA for 48 h, the Caspase3 and Caspase8 were significantly activated as compared with the control group (P<0.05). Significant difference existed in growth rate among the three groups (P<0.01) and between either two groups (P<0.05). The expression rate of factor VIII and Ki-67 was gradually increased from group A, group B to group C. The study suggests that ATRA could inhibit the proliferation of Walker-256 cells and the effectiveness of the combined therapy (ATRA+TACE) for treating transplanted hepatoma of rats is superior to that of TACE alone.

Retinoids: new use by innovative drug-delivery systems

BACKGROUND

Retinoids represent an old class of bioactives used in the treatment of different skin pathologies (such as acne and psoriasis) and in the treatment of many tumors. Unfortunately, they present several side effects, i.e., burning of skin and general malaise after systemic administration and they are very unstable after exposition to light.

METHODS

One of the most promising new approaches for reducing the side effects of retinoids while improving their pharmacological effect is the use of drug-delivery devices. This review explains the current status of retinoid drug transport, which has been developing over the last few years, explaining the modification of their biopharmaceutical properties in detail after encapsulation/inclusion in vesicular and polymeric systems.

RESULTS/CONCLUSION

Different colloidal and micellar systems containing retinoid drugs have been realized furnishing important potential advancements in traditional therapy.

Electrostatic immobilization of DNA polyplexes on small intestinal submucosa for tissue substrate-mediated transfection

Naturally occurring extracellular matrices (ECMs) such as small intestinal submucosa (SIS) have received significant attention for their therapeutic applications in tissue repair and regeneration. However, there have been no reports exploring the electrostatic properties of naturally occurring ECMs as a means to control transgene delivery. In the present study, we electrostatically adsorbed DNA polyplexes onto SIS for transfection upon cellular adhesion. To associate polyplexes with SIS, we first used a streaming potential method to characterize the surface charge of SIS and obtained a negative zeta potential at neutral pH, which can be attributed to the abundant glycosaminoglycan (GAG) content in SIS. We next prepared cationic polyethylenimine (PEI)/DNA polyplexes to associate with the negatively charged SIS for conjugation. Using the Cy(TM)3 dye-labeled control DNA as the reporter, we visualized the adsorption of PEI/DNA polyplexes at the SIS surface. Using luciferase, green fluorescent protein and beta-galactosidase as reporter proteins, we showed that the adsorbed PEI/DNA polyplexes were active and capable of carrying out transfection upon cellular adhesion, indicating that the electrostatic binding of polyplexes with SIS was reversible. In addition, the SIS-mediated transfection was contact-dependent: separation of SIS from the target cells via a 0.5 mm porous polyester membrane significantly reduced the efficiency of transfection in comparison to a direct seeding of cells onto SIS. We conclude that electrostatic immobilization of PEI/DNA polyplexes on SIS is capable of initiating efficient transgene delivery, which can be a useful tool in developing localized gene transfer.

Anti-tumor Effect of All-Trans Retinoic Acid Loaded Polymeric Micelles in Solid Tumor Bearing Mice

PURPOSE

All-trans retinoic acid (ATRA) polymeric micelles were developed for parenteral administration. The distribution characteristics and antitumor activities of ATRA polymeric micelles were evaluated after intravenous administration to mice bearing CT26 solid tumors.

METHODS

ATRA incorporated in poly(ethylene glycol)-poly(benzyl aspartate) block copolymer was prepared by the evaporation method. The levels of [3H]ATRA in blood and tissue including tumor were determined by measuring the radioactivity after injection into mice. The tumor volume and the survival of the mice were determined to assess the anticancer activity.

RESULTS

The delivery of ATRA by polymeric micelles prolonged the blood circulation and enhanced the accumulation of ATRA in the tumor tissue compared with the administration of free ATRA. Tumor growth was significantly delayed and the survival time of mice was prolonged following the treatment by ATRA polymeric micelles demonstrating the improved anticancer activity of ATRA.

CONCLUSION

Polymeric micelles are a promising and effective carrier of ATRA in order to enhance tumor delivery and they have a promising potential application in the treatment of solid tumors.

Lung-targeting delivery of dexamethasone acetate loaded solid lipid nanoparticles

The objective of the present study was to develop a novel solid lipid nanoparticle (SLN) for the lung-targeting delivery of dexamethasone acetate (DXM) by intravenous administration. DXM loaded SLN colloidal suspensions were prepared by the high pressure homogenization method. The mean particle size, drug loading capacity and drug entrapment efficiency (EE%) of SLNs were investigated. In vitro drug release was also determined. The biodistribution and lung-targeting efficiency of DXM-SLNs and DXM-solutions (DXM-sol) in mice after intravenous administration were studied using reversed-phase high-performance liquid chromatography (HPLC). The results (expressed as mean +/- SD) showed that the DXM-SLNs had an average diameter of 552 +/- 6.5 nm with a drug loading capacity of 8.79 +/- 0.04% and an entrapment efficiency of 92.1 +/- 0.41%. The in vitro drug release profile showed that the initial burst release of DXM from DXM-SLNs was about 68% during the first 2 h, and then the remaining drug was released gradually over the following 48 hours. The biodistribution of DXM-SLNs in mice was significantly different from that of DXM-sol. The concentration of DXM in the lung reached a maximum level at 0.5 h post DXM-SLNs injection. A 17.8-fold larger area under the curve of DXM-SLNs was achieved compared to that of DXM-sol. These results indicate that SLN may be promising lung-targeting drug carrier for lipophilic drugs such as DXM.