Anticancer Drug Gemcitabine Research Articles

Multifunctional polymersomes for cytosolic delivery of gemcitabine and doxorubicin to cancer cells

Although liposomes are widely used as carriers of drugs and imaging agents, they suffer from a lack of stability and the slow release of the encapsulated contents at the targeted site. Polymersomes (vesicles of amphiphilic polymers) are considerably more stable compared to liposomes; however, they also demonstrate a slow release for the encapsulated contents, limiting their efficacy as a drug-delivery tool. As a solution, we prepared and characterized echogenic polymersomes, which are programmed to release the encapsulated drugs rapidly when incubated with cytosolic concentrations of glutathione. These vesicles encapsulated air bubbles inside and efficiently reflected diagnostic-frequency ultrasound. Folate-targeted polymersomes showed an enhanced uptake by breast and pancreatic-cancer cells in a monolayer as well as in three-dimensional spheroid cultures. Polymersomes encapsulated with the anticancer drugs gemcitabine and doxorubicin showed significant cytotoxicity to these cells. With further improvements, these vesicles hold the promise to serve as multifunctional nanocarriers, offering a triggered release as well as diagnostic ultrasound imaging.

Nucleoside-catabolizing Enzymes in Mycoplasma-infected Tumor Cell Cultures Compromise the Cytostatic Activity of the Anticancer Drug Gemcitabine

The intracellular metabolism and cytostatic activity of the anticancer drug gemcitabine (2',2'-difluoro-2'-deoxycytidine; dFdC) was severely compromised in Mycoplasma hyorhinis-infected tumor cell cultures. Pronounced deamination of dFdC to its less cytostatic metabolite 2',2'-difluoro-2'-deoxyuridine was observed, both in cell extracts and spent culture medium (i.e. tumor cell-free but mycoplasma-containing) of mycoplasma-infected tumor cells. This indicates that the decreased antiproliferative activity of dFdC in such cells is attributed to a mycoplasma cytidine deaminase causing rapid drug catabolism. Indeed, the cytostatic activity of gemcitabine could be restored by the co-administration of tetrahydrouridine (a potent cytidine deaminase inhibitor). Additionally, mycoplasma-derived pyrimidine nucleoside phosphorylase (PyNP) activity indirectly potentiated deamination of dFdC: the natural pyrimidine nucleosides uridine, 2'-deoxyuridine and thymidine inhibited mycoplasma-associated dFdC deamination but were efficiently catabolized (removed) by mycoplasma PyNP. The markedly lower anabolism and related cytostatic activity of dFdC in mycoplasma-infected tumor cells was therefore also (partially) restored by a specific TP/PyNP inhibitor (TPI), or by exogenous thymidine. Consequently, no effect on the cytostatic activity of dFdC was observed in tumor cell cultures infected with a PyNP-deficient Mycoplasma pneumoniae strain. Because it has been reported that some commensal mycoplasma species (including M. hyorhinis) preferentially colonize tumor tissue in cancer patients, our findings suggest that the presence of mycoplasmas in the tumor microenvironment could be a limiting factor for the anticancer efficiency of dFdC-based chemotherapy. Accordingly, a significantly decreased antitumor effect of dFdC was observed in mice bearing M. hyorhinis-infected murine mammary FM3A tumors compared with uninfected tumors.

Autophagy is needed for the growth of pancreatic adenocarcinoma and has a cytoprotective effect against anticancer drugs

Background and aimAutophagy is a regulated process of degradation and recycling of cellular constituents. The role of autophagy in pancreatic cancer is still not clear. Some studies indicate that in pancreatic cancer autophagy exerts cytoprotective effects, whereas others suggest that autophagy positively contributes to cell death by enhancing cytotoxicity of anticancer drugs. The aim of this study was to investigate the role of autophagy in pancreatic cancer, and to provide insights into new strategies for treatment. Materials and methodsPancreatic cancer cell lines PANC-1 and BxPC-3 were treated with anticancer drugs (5-fluorouracil or gemcitabine) alone and in combination with autophagy inhibitors (chloroquine or wortmannin). Biopsy samples were retrieved from patients from pancreatic normal tissue and adenocarcinoma. Western blot of microtubule-associated protein 1 light chain 3 (LC3)-II was performed to investigate the degree of autophagy and cell proliferation was assessed by a crystal violet assay. ResultsAutophagy was active in PANC-1 cells under basal conditions. Autophagy was significantly induced in pancreatic ductal adenocarcinoma compared to healthy pancreatic tissue in patients. Inhibition of autophagy by chloroquine suppressed the growth of PANC-1 and BxPC-3. Autophagy was markedly increased after treatment with 5-fluorouracil or gemcitabine. Inhibition of autophagy by chloroquine potentiated the inhibition of cell proliferation of PANC-1 and BxPC-3 by 5-fluorouracil and gemcitabine. ConclusionsOur results with pancreatic cancer cell lines and human pancreatic adenocarcinoma suggest that autophagy contributes to pancreatic cancer cell growth. Autophagy has a cytoprotective effect against 5-fluorouracil and gemcitabine in pancreatic cancer cells. Combination therapy of these anticancer drugs and chloroquine should be investigated.

A study of an effective sunitinib–chemotherapeutic combination regimen for bladder cancer treatment using a mouse model

ObjectiveTo determine if tyrosine kinase receptor inhibitor, sunitinib malate, combined with chemotherapeutic drugs may present synergistic enhancement of cytotoxicity to transitional cell carcinoma cells (TCC). MethodsThe mRNA and protein contents of vascular endothelial growth factor-α (VEGFα) in various TCC cell lines were detected individually by quantitative-polymerase chain reaction and Western blot. The inhibitory concentrations of various chemotherapeutic drugs, including gemcitabine, doxorubicin, and cisplatin, and their combination with sunitinib to TCC cancer cells were determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The synergist efficacy was measured using the observed/expected ratio calculation method. Finally, the synergistic effect of sunitinib and selected anticancer drug gemcitabine was elucidated in C3H/MBT-2 animal tumor model with monitoring tumor growth volume and survival rate. ResultsThe mRNA of VEGFα had high expression in high-grade TCC cell lines (T24, TCC 8701, and TCC 8702) when compared with low-grade TCC cell lines (TCC 8301 and TSGH 9201). The expression of VEGFα protein level was closely correlated with the mRNA content in each individual cell line. Sunitinib, combined with gemcitabine, has shown the highest synergistic cytotoxic effect to TCC cells in an MTT assay. In the xenografted tumor model, MBT-2 bearing mice treated by sunitinib and gemcitabine combination had the lower mean tumor volume (265 ± 95 mm3 vs. 2605 ± 320 mm3) and higher survival rate (100% vs. 56%) at 30 days follow-up when compared with control mice. ConclusionCombination of the tyrosine kinase receptor inhibitor sunitinib with gemcitabine chemotherapy synergistically enhances tumor cytotoxicity and may provide a new treatment modality for advanced bladder cancer.

Surface functionalization of SBA-15 nanorods for anticancer drug delivery

SBA-15 nanorods with high surface area (1010m2g−1) were functionalized by post grafting method with three different alkoxysilanes including (3-aminopropyl) triethoxysilane (APTES), 3-[bis(2-hydroxyethyl)amino] propyl triethoxysilane (HAPS) and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane (AEPS). The prepared materials were used as nanocarriers for an anticancer drug (gemcitabine). The obtained samples were characterized by SAXS, elemental analysis, TGA, N2 adsorption/desorption, SEM, TEM, FTIR and UV spectroscopies. The adsorption and release properties of all samples were investigated. It was found that the surface functionalization increases the interaction between the carrier and gemcitabine and results in the loading enhancement of the drug. In addition, the adsorption of gemcitabine on the modified mesoporous matrix depends on the type and the amount of alkoxysilanes groups. The maximum content of the deposited drug in the modified SBA-15 nanorods is close to 22wt.%. The rate of the drug release from the modified samples containing NH2 groups on their surfaces is pH dependent.

Attenuation of nucleoside and anti-cancer nucleoside analog drug uptake in prostate cancer cells by Cimicifuga racemosa extract BNO-1055

This study aimed to investigate the mechanisms underlying the anti-proliferative effects of the ethanolic Cimicifuga racemosa extract BNO-1055 on prostate cells and evaluate its therapeutic potential. BNO-1055 dose-dependently attenuated cellular uptake and incorporation of thymidine and BrdU and significantly inhibited cell growth after long-time exposure. Similar results were obtained using saponin-enriched sub-fractions of BNO-1055. These inhibitory effects of BNO-1055 could be mimicked using pharmacological inhibitors and isoform-specific siRNAs targeting the equilibrative nucleoside transporters ENT1 and ENT2. Moreover, BNO-1055 attenuated the uptake of clinically relevant nucleoside analogs, e.g. the anti-cancer drugs gemcitabine and fludarabine. Consistent with inhibition of the salvage nucleoside uptake pathway BNO-1055 potentiated the cytotoxicity of the de novo nucleotide synthesis inhibitor 5-FU without significantly altering its uptake. Collectively, these data show for the first time that the anti-proliferative effects of BNO-1055 result from hindered nucleoside uptake due to impaired ENT activity and demonstrate the potential therapeutic use of BNO-1055 for modulation of nucleoside transport.

Molecular analysis of the inhibitory effect of N-acetyl-L-cysteine on the proliferation and invasiveness of pancreatic cancer cells

Preliminary studies have suggested that the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) may be effective in inhibiting the growth of pancreatic cancer cells. In-depth cellular and molecular analyses were carried out to determine NAC's mode of action in inhibiting the growth of a well-characterized pancreatic cancer cell line (AsPC-1). Standardized assays were used to monitor cellular growth, apoptosis, levels of ROS, cellular senescence, migration, and invasiveness. Cell stiffness was measured using atomic force microscopy. Gene expression was monitored by quantitative PCR. NAC significantly inhibits the growth and metastatic potential of AsPC-1 cells by inducing cell-cycle arrest in G1 and subsequent cellular senescence and decreased invasiveness. These anticancer properties are associated with an unexpected increase in the intracellular concentrations of ROS. NAC does not decrease the susceptibility of AsPC-1 cells to the anticancer drugs gemcitabine, mitomycin C, and doxorubicin. NAC-induced changes in gene expression are consistent with the onset of mesenchymal-to-epithelial transition. In conclusion, our findings indicate that NAC induces an integrated series of responses in AsPC-1 cells that make it a highly promising candidate for development as a pancreatic cancer therapeutic.

Abstract 227: Manipulation of hypoxia-NFκB pathway to target breast cancer stem cells.

Abstract Background Although the existence of cancer stem cells (CSCs) is still debatable, it is widely accepted that the cancer cells expressing CSC markers are highly resistant to chemo-radiation therapy. Up to 60% of locally advanced solid tumours exhibit hypoxia. Accumulated evidence demonstrates that hypoxia induces epithelial-to-mesenchymal transition and CSCs phenotypes in cancer cells. The pathways between hypoxia and CSCs are still largely in the dark. NFκB is a transcription factor being involved in chemo-radiation resistance. Activation of NFκB by hypoxia in a wide range of cells in inflammatory conditions has been identified for more than a decade. Recently, emerging evidence demonstrates that NFκB is also a key factor maintaining the stemness in breast CSCs. Therefore NFκB may mediate and be involved in hypoxia-induced CSCs phenotypes. Our previous studies show that disulfiram (DS), an anti-alcoholism drug, reverses chemoresistance of a variety of anticancer drugs in several types of cancer. In this study, we used an in vitro model to investigate the relationship between hypoxia-NFκB pathway and CSC phenotypes in two breast cancer cell lines (T47D and MCF7). The effect of DS on hypoxia-NFκB pathway and the cytotoxicity of conventional anticancer drugs (paclitaxel, gemcitabine and doxorubicin) in CSCs were also observed. RESULTS A huge proportion of hypoxic cells were detected in mammospheres. NFκB activation (AKT phosphorylation, IκBα degradation, p65 nuclear translocation, phosphorylation and NFκB transactivation) was detected in the CSCs. The percentage of breast cancer cells with CSC markers (ALDH+, CD24low/CD44high) is significantly increased in the NFκB p65 transfected cell lines. The transfected cell lines are highly resistant to doxorubicin, paclitaxel and gemcitabine. In contrast, breast CSCs do not show any resistance to DS. The cytotoxicity of DS is copper-dependent and cancer specific with no cytotoxicity in normal cell lines. CI-isobologram analysis demonstrates that DS significantly enhances cytotoxicity of conventional anticancer drugs (doxorubicin: 8 - 11-fold; gemcitabine: 1.2 - 23.5-fold; paclitaxel: 4 - 10-fold). DS simultaneously activates ROS-JNK pathway and blocks p65 nuclear translocation. The effect of DS on stemness of breast cancer cell lines is confirmed by its elimination of ALDH+VE CD24Low/CD44High population in mammospheres. To prolong the half-life of DS in bloodstream, we recently developed a liposome encapsulated DS. The liposomal DS shows very strong anticancer activity in an animal cancer model. CONCLUSIONS Our results demonstrate that hypoxia-NFκB pathway is involved in maintaining the stemness and chemoresistance in breast CSCs. DS is highly cytotoxic to breast CSCs and enhances cytotoxicity of conventional anticancer drugs. This may be caused by simultaneous induction of ROS and inhibition of NFkB pathway. Citation Format: Peng Liu, Sarah Brown, Vinodh Kannappan, Angel L. Armesilla, John L. Darling, Weiguang Wang. Manipulation of hypoxia-NFκB pathway to target breast cancer stem cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 227. doi:10.1158/1538-7445.AM2013-227 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

A fluorescence off–on reporter for real time monitoring of gemcitabine delivery to the cancer cells

We present the design, synthesis, optical properties and in vitro biological assessments of the theranostic prodrug in which a near IR fluorophore is conjugated with a cancer cell-directing biotin unit; further it is linked with the anti-cancer drug gemcitabine via a self-immolative spacer, a disulfide bond. The prodrug is able to monitor drug delivery and cellular imaging.

191 Combining siRNAs Targeting Thymidylate Synthase and Thymidine Kinase 1 or 2 Sensitizes Human Tumor Cells to the Anticancer Drugs 5FUdR, Pemetrexed and Gemcitabine

191 Combining siRNAs Targeting Thymidylate Synthase and Thymidine Kinase 1 or 2 Sensitizes Human Tumor Cells to the Anticancer Drugs 5FUdR, Pemetrexed and Gemcitabine

Role of S100A8/A9 in the cross-talk between cancer cells and stroma-associated cells

s / Pancreatology 12 (2012) 502–597 589 1 Tampere Pancreas Laboratory, Tampere University Hospital, Tampere, Finland Department of Gastroenterology and Alimentary Tract Surgery, Tampere University Hospital, Tampere, Finland Department of Gastroenterological Surgery, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan Objectives: Studies with PANC-1 imply that autophagymay be induced in pancreatic ductal adenocarcinoma (PDA). Investigating the role of autophagy in patients is challenging as the induction of autophagy in pancreatic tissue may be affected by cell death mechanisms taking place after the tissue specimens have been harvested. Eliminating this postharvesting distraction would be crucial when investigating this phenomenon. No such study about autophagy in PDA in patients exists. Our aim was to study, whether autophagy is 1) induced in PDA compared to healthy pancreatic tissue in patients, and 2) correspondent to the autophagic status of PANC-1 cells in vitro. Patients and methods: Pancreatic samples were retrieved in laparotomy from patients undergoing pancreato-duodenectomy. Core-needle biopsies from the center of histologically-confirmed PDA tumors and from healthy pancreas (within the area to be resected) were immediately snapfrozen and proteins were extracted by repeated freeze-thaw cycles. The degree of autophagy was analysed by Western blotting of LC3-II, and compared to the degree of autophagy in PANC-1 cells (in basal conditions and when treated with anticancer drugs (gemcitabine and 5-FU) +/autophagy inhibitor chloroquine). Results: Autophagy was significantly induced in PDA compared to healthy pancreatic tissue in patients. This resembled the autophagic status of PANC-1 cells under basal culture conditions. Conclusions: Autophagy is induced in PDA in patients similarly to PANC-1 cells. In PANC-1 cells chloroquine increases the cytotoxicity of 5FU and gemcitabine by inhibiting autophagy. Thus patients with PDA may benefit from therapy where anticancer drugs are combined with an autophagy inhibitor.

Molecular dynamics properties of varying amounts of the anticancer drug gemcitabine inside an open-ended single-walled carbon nanotube

To investigate the loading of multiple drugs inside single-walled carbon nanotubes (SWCNTs), molecular dynamics simulations were applied to the gemcitabine–SWCNT system with from one to six drug molecules being confined inside the SWCNT cavity. At low drug concentrations (1–4 gemcitabines inside each SWCNT), the π–π stacking of two cytosine rings of adjacent gemcitabine molecules caused them to orientate towards each other and move together inside the SWCNT. In contrast, at high drug concentrations (encapsulated gemcitabines ⩾5), the close contact of gemcitabines promoted electrostatic interactions through hydrogen bonding rather than the π–π stacking interaction from their cytosine rings.

Constitutive Expression of MAP Kinase Phosphatase-1 Confers Multi-drug Resistance in Human Glioblastoma Cells

PurposeCurrent treatment of glioblastoma after surgery consists of a combination of fractionated radiotherapy and temozolomide. However, it is difficult to completely remove glioblastoma because it has uncertain boundaries with surrounding tissues. Moreover, combination therapy is not always successful because glioblastoma has diverse resistances. To overcome these limitations, we examined the combined effects of chemotherapy and knockdown of mitogen-activated protein kinase phosphatase-1 (MKP-1).Materials and MethodsWe used ten different anti-cancer drugs (cisplatin, cyclophosphoamide, doxorubicin, epirubicin, etoposide, 5-fluorouracil, gemcitabine, irinotecan, mitomycin C, and vincristine) to treat glioblastoma multiforme (GBM) cells. Knockdown of MKP-1 was performed using siRNA and lipofectamine. The basal level of MKP-1 in GBM was analyzed based on cDNA microarray data obtained from the Gene Expression Omnibus (GEO) databases.ResultsAnti-cancer drug-induced cell death was significantly enhanced by knockdown of MKP-1, and this effect was most prominent in cells treated with irinotecan and etoposide. Treatment with these two drugs led to significantly increased phosphorylation of c-Jun N-terminal kinase (JNK) in a time-dependent manner, while pharmacological inhibition of JNK partially inhibited drug-induced cell death. Knockdown of MKP-1 also enhanced drug-induced phosphorylation of JNK.ConclusionIncreased MKP-1 expression levels could be the cause of the high resistance to conventional chemotherapeutics in human GBM. Therefore, MKP-1 is an attractive target for overcoming drug resistance in this highly refractory malignancy.

Role of mitochondrial uncoupling protein 2 in cancer cell resistance to gemcitabine

Cancer cells exhibit an endogenous constitutive oxidative stress higher than that of normal cells, which renders tumours vulnerable to further reactive oxygen species (ROS) production. Mitochondrial uncoupling protein 2 (UCP2) can mitigate oxidative stress by increasing the influx of protons into the mitochondrial matrix and reducing electron leakage and mitochondrial superoxide generation. Here, we demonstrate that chemical uncouplers or UCP2 over-expression strongly decrease mitochondrial superoxide induction by the anticancer drug gemcitabine (GEM) and protect cancer cells from GEM-induced apoptosis. Moreover, we show that GEM IC50 values well correlate with the endogenous level of UCP2 mRNA, suggesting a critical role for mitochondrial uncoupling in GEM resistance. Interestingly, GEM treatment stimulates UCP2 mRNA expression suggesting that mitochondrial uncoupling could have a role also in the acquired resistance to GEM. Conversely, UCP2 inhibition by genipin or UCP2 mRNA silencing strongly enhances GEM-induced mitochondrial superoxide generation and apoptosis, synergistically inhibiting cancer cell proliferation. These events are significantly reduced by the addition of the radical scavenger N-acetyl-l-cysteine or MnSOD over-expression, demonstrating a critical role of the oxidative stress. Normal primary fibroblasts are much less sensitive to GEM/genipin combination. Our results demonstrate for the first time that UCP2 has a role in cancer cell resistance to GEM supporting the development of an anti-cancer therapy based on UCP2 inhibition associated to GEM treatment.

Basic Investigation for Classification of Anticancer Drugs by Pharmacological Effects

The most effective drugs based on the type of cancer are chosen for chemotherapy. Tumor cells can be targeted at the DNA, RNA or protein level, and most of the classical anticancer drugs interact with tumor DNA in a time-dependent manner or a concentration-dependent manner. However, it has been unclear to date whether a combination therapy is carried out by using exact classification. Thus it is necessary to reclassify a great number of anticancer drugs. We propose a new classification system based on pharmacological effects of anticancer drugs. Classification of four anticancer drugs (cisplatin, carboplatin, paclitaxel and gemcitabine) was performed by the 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The four anticancer drugs were grouped by IC50 values (inhibitory concentration, 50%) in a time-dependent manner and a concentration-dependent manner. The present approach may be combined to enhance the chemosensitivity, improve the dose of cytotoxic drugs and evaluate the effects of novel anticancer drugs.

Application of microwave‐assisted click chemistry in the preparation of functionalized copolymers for drug conjugation

AbstractThe aim of this study is to develop azido‐carrying biodegradable polymers and their postfunctionalization with alkynyl compounds via click chemistry and to investigate their potential use in drug delivery. Azido polymers were prepared by ring‐opening polymerization of cyclic carbonate monomer, 2,2‐bis(azidomethyl)trimethylene carbonate (ATC) with lactide using stannous octoate as catalyst. Several alkynyl compounds were selected to investigate the feasibility and reaction condition of click chemistry. With microwave‐assisting, the reaction time of click chemistry was shortened to 5 min. By using poly(ethylene glycol) (PEG) as macroinitiator, amphiphilic block copolymer mPEG‐b‐P(LA‐co‐ATC) was obtained and it could self‐assemble into micelles by solvent replacement method. The pendant groups were used for conjugating anticancer drugs gemcitabine and paclitaxel and fluorescent dye Rhodamine B. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide was used to assay the cytotoxicity of the conjugate micelles against SKOV‐3 and HeLa cell lines. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Analytical detection and method development of anticancer drug Gemcitabine HCl using gold nanoparticles

A simple, rapid, cost effective and extractive UV spectrophotometric method was developed for the determination of Gemcitabine HCl (GMCT) in bulk drug and pharmaceutical formulation. It was based on UV spectrophotometric measurements in which the drug reacts with gold nanoparticles (AuNP) and changes the original colour of AuNP and forms a dark blue coloured solution which exhibits absorption maximum at 688nm. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 3.95×10−5lmol−1cm−1 and 0.060μgcm−2 respectively. Beer's law was obeyed in the concentration range of 2.0–40μgml−1. This method was tested and validated for various parameters according to ICH guidelines. The proposed method was successfully applied for the determination of GMCT in pharmaceutical formulation (parental formulation). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%). As it is simple, cheap and less time consuming, it can be suitably applied for the estimation of GMCT in dosage forms.

A Conjugate of Gemcitabine With Bisphosphonate (Gem/BP) Shows Potential as a Targeted Bone-Specific Therapeutic Agent in an Animal Model of Human Breast Cancer Bone Metastases

Bone metastases in advanced breast cancer patients remains a significant treatment challenge. Bisphosphonates are now a routine first line treatment for prevention and treatment of skeletal damage caused by malignancies and, moreover, have shown an ability to transport therapeutic drugs to the bone. Here, we describe the effect of a conjugate between the potent anticancer drug gemcitabine and a bisphosphonate molecule (Gem/BP) in an animal model of breast cancer metastases. We have previously demonstrated the targeting of this compound to bone in normal mice using an analog labeled with the radionuclide 99mTc. Using a bone metastasis model in nude mice produced by intracardiac injection of the human breast cancer cell line MDA-MB-231BO, we examined the effect of Gem/BP and gemcitabine in reducing the frequency and severity of osteolytic bone lesions. High-resolution radiographs and microPET images showed that Gem/ BP reduced the number and size of bone metastases relative to the gemcitabine-treated and the untreated control groups. Histological examination of the humeri and femurs of the control and gemcitabine groups revealed large metastatic cancer lesions in the outer and inner cortices and the medullary cavities. In contrast, Gem/BP-treated mice showed occasional small wedge-shaped metastases under the periosteum of the outer cortex and very occasionally in the medulla. These findings suggest that Gem/BP should be further evaluated for use in the treatment of bone metastases in breast cancer.

Gemcitabine-loaded chitosan microspheres. Characterization and biological in vitro evaluation

This study investigates the potential of chitosan microspheres as delivery systems for the anticancer drug gemcitabine. The microspheres were obtained by spray-drying chitosan-gemcitabine solutions containing different amounts of the polyanion dextran sulphate. Morphological characterization by SEM and FIB analyses showed the presence of porous spherical particles having sizes ranging from about 1 to 5 μm. Dextran sulphate improves the technological parameters of the systems by producing very high encapsulation efficiency (about 96%, w/w) and by influencing the in vitro release of gemcitabine. The immediate drug release observed in the system prepared without dextrane sulphate (complete drug release within 30 min) was somewhat reduced by the polyanion (immediate release of 70% (w/w) of the encapsulated drug within 30 min, and subsequent continued release of the remaining 30% of the drug for over 4 days). The anti-tumoral efficacy of the various formulations was tested in vitro on human lung cancer cells (A549) comparing the effects with those of the free drug or drug/dextran sulfate complex. The carriers improved the cytotoxic activity of the drug, particularly the formulation containing the lowest amount of dextran sulphate after 72 h incubation.

Targeting apoptosis pathways in pancreatic cancer

Pancreatic cancer – here in particular pancreatic ductal adenocarcinoma (PDAC) – is still a highly therapy refractory disease. Amongst the mechanisms by which PDAC cells could escape any non-surgical therapy, anti-apoptotic protection seems to be the most relevant one. PDAC cells have acquired resistance to apoptotic stimuli such as death ligands (FasL, TRAIL) or anti-cancer drugs (gemcitabine) by a great number of molecular alterations either disrupting an apoptosis inducing signal or counteracting the execution of apoptosis. Thus, PDAC cells exhibit alterations in the EGFR/MAPK/Ras/raf1-, PI3K/Akt-, TRAIL/TRAF2-, or IKK/NF-κB pathway accompanied by deregulations in the expression of apoptosis regulators such as cIAP, Bcl2, XIAP or survivin. Along with protection against apoptosis, PDAC cells also overexpress histone deacetylases (HDACs) giving rise to epigenetic patterns of chemoresistance and to acetylation of other regulatory proteins, as well. With respect to the multitude of anti-apoptotic pathways, a great number of molecular targets might be of high potential in novel therapy strategies. Thus, natural compounds as well as novel synthetic drugs are considered to be used in single or combined therapy of PDAC. A number of proteasome and HDAC inhibitors or selective inhibitors of IKK, EGFR, Akt and mTOR have been widely explored in preclinical settings and clinical studies. Even though these early studies encouraged an application in a clinical setting, most of the trials have been rather disappointing yet. Thus, new molecular targets and novel concepts of combination therapies need to get access into clinical trials – either in neoadjuvant/adjuvant or in palliative treatments.