A mechanistic study on reduced toxicity of irontecan by coadministered thalidomide, a tumor necrosis factor-a inhibitor

Dose-limiting diarrhea and myelosuppression compromise the success of irinotecan (7-ethyl-10-[4-[1-piperidino]-1-piperidino] carbonyloxycamptothecin) (CPT-11)-based chemotherapy. A recent pilot study indicates that thalidomide attenuates the toxicity of CPT-11 in cancer patients. This study aimed to investigate whether coadministered thalidomide modulated the toxicities of CPT-11 and the underlying mechanisms using several in vivo and in vitro models. Diarrhea, intestinal lesions, cytokine expression, and intestinal epithelial apoptosis were
monitored. Coadministered thalidomide (100 mg/kg i.p. for 8 days) significantly attenuated body weight loss, myelosuppression, diarrhea, and intestinal histological lesions caused by CPT-11 (60 mg/kg i.v. for 4 days). This was accompanied by inhibition of tumor necrosis factor-, interleukins 1 and 6 and interferon-, and intestinal epithelial apoptosis. Coadministered
thalidomide also significantly increased the systemic exposure of CPT-11 but decreased that of SN-38 (7-ethyl-10-hydroxycampothecin). It significantly reduced the biliary excretion and cecal exposure of CPT-11, SN-38, and SN-38 glucuronide. Thalidomide hydrolytic products inhibited hydrolysis of CPT-11 in rat liver microsomes but not in primary rat hepatocytes. In addition, thalidomide and its major hydrolytic products, such as phthaloyl glutamic acid (PGA), increased the intracellular accumulation of CPT-11 and SN-38 in primary rat hepatocytes. They also significantly decreased the transport of CPT-11 and SN-38 in Caco-2 and parental MDCKII cells. Thalidomide and PGA also significantly inhibited P-glycoprotein (PgP/MDR1), multidrug resistance-associated protein (MRP1)- and MRP2-mediated CPT-11 and SN-38 transport in MDCKII cells. These results provide insights into the pharmacodynamic and  pharmacokinetic mechanisms for the protective effects of thalidomide against CPT-11-induced intestinal toxicity.

Development of microfluidic-based analytical methodology for studying the effects of chemotherapy agents on cancer tissue

Whilst a multitude of techniques have been employed to study the biology of tumour tissue and its response to chemotherapeutic reagents, most current methodologies do not capture the sophistication of the in vivo environment. Microfluidics however offers the ability to maintain and interrogate primary tissue samples in an environment with biomimetic flow characteristics. In this study head and neck squamous cell carcinoma (HNSCC) tumour biopsies have been used to investigate the performance of a microfluidic device for generating clinically-useful information. The response of fresh and cryogenically-frozen primary HNSCC or metastatic lymph node samples to chemotherapy drugs (cisplatin, 5-flurouracil or docetaxel), alone and in combination, were monitored for both proliferation (water-soluble tetrazolium salt metabolism) and cell death biomarker release (lactate dehydrogenase, LDH) “off-chip”. The frozen tissue showed no significant difference in terms of either proliferation or LDH release in comparison with the matched fresh samples. Administration of all drugs caused cell death, in a dose-response manner, with the combination showing the greatest amount of cytotoxicity particularly at days 8 and 9; correlating well with published clinical data. The system described here offers an innovative method for studying the tumour microenvironment in vitro and, through incorporation of relevant analytical modules, provides the basis of a pre-clinical device that can be used to define personalised treatment regimens.

Substrates and inhibitors of human multidrug resistance associated proteins and the implications in drug development

Human contains 49 ATP-binding cassette (ABC) transporter genes and the multidrug resistance associated proteins (MRP1/ABCC1, MRP2/ABCC2, MRP3/ABCC3, MRP4/ABCC4, MRP5/ABCC5, MRP6/ABCC6, MRP7/ABCC10, MRP8/ABCC11 and MRP9/ABCC12) belong to the ABCC family which contains 13 members. ABCC7 is cystic fibrosis transmembrane conductance regulator; ABCC8 and ABCC9 are the sulfonylurea receptors which constitute the ATP-sensing subunits of a complex potassium channel. MRP10/ABCC13 is clearly a pseudo-gene which encodes a truncated protein that is highly expressed in fetal human liver with the highest similarity to MRP2/ABCC2 but without transporting activity. These transporters are localized to the apical and/or basolateral membrane of the hepatocytes, enterocytes, renal proximal tubule cells and endothelial cells of the blood-brain barrier. MRP/ABCC members transport a structurally diverse array of important endogenous substances and xenobiotics and their metabolites (in particular conjugates) with different substrate specificity and transport kinetics. The human MRP/ABCC transporters except MRP9/ABCC12 are all able to transport organic anions, such as drugs conjugated to glutathione, sulphate or glucuronate. In addition, selected MRP/ABCC members may transport a variety of endogenous compounds, such as leukotriene C(4) (LTC(4) by MRP1/ABCC1), bilirubin glucuronides (MRP2/ABCC2, and MRP3/ABCC3), prostaglandins E1 and E2 (MRP4/ABCC4), cGMP (MRP4/ABCC4, MRP5/ABCC5, and MRP8/ABCC11), and several glucuronosyl-, or sulfatidyl steroids. In vitro, the MRP/ABCC transporters can collectively confer resistance to natural product anticancer drugs and their conjugated metabolites, platinum compounds, folate antimetabolites, nucleoside and nucleotide analogs, arsenical and antimonial oxyanions, peptide-based agents, and in concert with alterations in phase II conjugating or biosynthetic enzymes, classical alkylating agents, alkylating agents. Several MRP/ABCC members (MRPs 1-3) are associated with tumor resistance which is often caused by an increased efflux and decreased intracellular accumulation of natural product anticancer drugs and other anticancer agents. Drug targeting of these transporters to overcome MRP/ABCC-mediated multidrug resistance may play a role in cancer chemotherapy. Most MRP/ABCC transporters are subject to inhibition by a variety of compounds. Based on currently available preclinical and limited clinical data, it can be expected that modulation of MRP members may represent a useful approach in the management of anticancer and antimicrobial drug resistance and possibly of inflammatory diseases and other diseases. A better understanding of their substrates and inhibitors has important implications in development of drugs for treatment of cancer and inflammation.

Microbial-based therapy of cancer: a new twist to age old practice

The use of bacteria in the regression of tumors has long been known. Various approaches for using bacteria in cancer therapy include the use of bacteria as sensitizing agents for chemotherapy, as delivery agents for cancer drugs and as agents for gene therapy. The tumor regression stimulated by infecting microorganisms has been attributed to activation of the immune system of the host. However, recent studies indicate that when tumor-harboring mice with defective immune systems are infected with certain microorganisms, the regression of the tumor is still observed, suggesting that there are other host factors contributing to the microbial associated regression of tumors. Since the use of live or attenuated bacteria for tumor regression has associated toxic effects, studies are in progress to identify a pure microbial metabolite or any component of the microbial cell that might have anti-cancer activity. It has now been demonstrated that a redox protein from Pseudomonas aeruginosa, a cupredoxin, can enter into human cancer cells and trigger the apoptotic cell death. In vivo, this cupredoxin can lead to the regression of tumor growth in immunodeficient mice harboring xenografted melanomas and breast cancer tumors without inducing significant toxic effects, suggesting that it has potential anti-cancer activity. This bacterial protein interacts with p53 and modulates mammalian cellular activity. Hence, it could potentially be used as an anti-cancer agent for solid tumors and has translational value in tumor-targeted or in combinational-biochemotherapy strategies for cancer treatments. Here, we focus on diverse approaches to cancer biotherapy, including bacteriolytic and bacterially-derived anti-cancer agents with an emphasis on their mechanism of action and therapeutic potential.

Chemotherapy in the elderly

The number of elderly patients with malignancy is growing and is likely to have a major impact on resources, quality of care, health economics and treatment options. Decisions regarding treatment options with chemotherapy are limited by the scarcity of data specifically addressing the issues regarding chemotherapy in the elderly. The problem is further confounded by issues such as co morbidity, poly-pharmacy, cognitive impairments, emotional problems, functional limitations, sensory impairment and a lack of social support. Ageing is associated with specific physiologic changes in functional status, organ function and drug pharmacokinetics. Optimising cancer care and chemotherapy delivery in the elderly requires a better understanding of the specific pharmacokinetic and pharmacodynamic issues and administration of chemotherapy in this age group. Elderly participation in clinical trials and specific research is essential to guide treatment decisions and further research is required to provide evidence-based models to guide treatment decisions. In an Australian setting, the development of a geriatric oncology specific group as a means of facilitating collaboration with geriatricians, development of specific elderly research programs and clinical trials, education and development of treatment guidelines would further improve outcomes of our elderly patients undergoing cancer treatment.

X-ray diffraction line broadening from gold and platinum thin films

X-ray diffraction line profile analysis has been used to study the microstructure of (Ill) oriented gold and platinum thin films deposited by thermal evaporation and DC magnetron sputtering. In addition to crystallite size broadening, the profiles from these films displayed broadening arising from dislocations. A parallel investigation, using transmission electron microscopy (TEM) was undertaken to study the nature of dislocations formed, and to provide information on the dimensions of the crystallite columns in the films. X-ray data were collected at room temperature to determine the anisotropy of the broadening with (hkl), using a Siemens D5000 powder diffractometer (CuKa radiation) and two high-resolution synchrotron instruments (BM 16 at the ESRF [A=0.35A] and station 2.3 at the Daresbury laboratory. Two approaches to instrument deconvolution were investigated; Fourier deconvolution and fundamental parameters profile fitting, using Lab6 as a reference material to determine the instrument profile function. After removal of the crystallite size broadening contribution from the measured integral breadths, the residual microstrain broadening was modelled assuming dislocations based on a FCC a/2<110>{ Ill} slip system. The results of the X-ray analysis agreed with dark field TEM micrographs, which showed that many of the crystallites contained dislocations of mixed character (screw- edge).

Evaluation of selected platinum group metal complexes as chemiluminescence reagents

This research extends the investigations into the chemiluminescence and electrochemiluminescence of platinum group metal reagents and their applications. The effect of the chemical nature of tris(2,2'-bipyridyl)ruthenium(II) and selected analogues on the chemiluminescence reaction is further explored, and this chemistry is extended to include novel iridium(III) and osmium(II) based chemiluminescence reagents.

IPA: Integrated predictive gene signature from gene expression based breast cancer patient samples

Background: Novel predictive markers are needed to accurately diagnose the breast cancer patients so they do not need to undergo any unnecessary aggressive therapies. Various gene expression studies based predictive gene signatureshave generated in the recent past to predict the binary estrogen-receptor subclass or to predict the therapy response subclass. However, the existing algorithms comes with many limitations, including low predictive performances over multiple cohorts of patients and non-significant or limited biological roles associated with thepredictive gene signatures. Therefore, the aim of this study is to develop novel predictive markers with improved performances.Methods: We propose a novel prediction algorithm called IPA to construct a predictive gene signature for performing multiple prediction tasks of predicting estrogen-receptor based binary subclass and predicting chemotherapy response (neoadjuvantly) based binary subclass. The constructed gene signature with considering multiple classification techniques was used to evaluate the algorithm performance on multiple cohorts of breast cancer patients.Results: The evaluation on multiple validation cohorts demonstrated that proposed algorithm achieved stable and high performance to perform prediction tasks, with consideration given to any classification techniques. We show that the predictive gene signature of our proposed algorithm reflects the mechanisms underlying the estrogen-receptors or response to therapy with significant greater biological interpretations, compared with the other existing algorithm.

Electrochemistry of tris(2,2′-bipyridyl) cobalt(II) in ionic liquids and aprotic molecular solvents on glassy carbon and platinum electrodes

The tris(2,2′-bipyridyl) complexes of cobalt(II) and (III) ([Co(bpy)3]^2+/3+) produce a redox couple of great interest in thermoelectrochemical cells and dye sensitized solar cells including both types of devices based on ionic liquid electrolytes. We present a systematic study of the electrochemistry of [Co(bpy)3]²⁺ [NTf2]^-2 in two ionic liquids (ILs) based on the 1-ethyl-3-methylimidazolium (C2mim) cation and two ILs based on the 1-butyl-1-methylpyrrolidinium cation (C4mpyr), as well as three aprotic molecular solvents. Platinum (Pt) and glassy carbon (GC) working electrodes were compared. In all solvents better electrochemical responses were observed on GC, which yielded higher currents in the cyclic voltammograms and lower rate constants for the redox reaction. The [Co(bpy)3]^1+/2+ couple is also readily observed, but this redox reaction is chemically irreversible, possibly because the [Co(bpy)3]¹⁺ complex dissociates. However, the [Co(bpy)3]^1+/2+ reaction is chemically reversible in all of the solvents studied, except 3-methoxypropionitrile, if excess of 2,2′-bipyridyl is added to the solution.

Cisplatin-induced formation of biocompatible and biodegradable polypeptide-based vesicles for targeted anticancer drug delivery

Novel cisplatin (CDDP)-loaded, polypeptide-based vesicles for the targeted delivery of cisplatin to cancer cells have been prepared. These vesicles were formed from biocompatible and biodegradable maleimide-poly(ethylene oxide)114-b-poly(L-glutamic acid)12 (Mal-PEG114-b-PLG12) block copolymers upon conjugation with the drug itself. CDDP conjugation forms a short, rigid, cross-linked, drug-loaded, hydrophobic block in the copolymer, and subsequently induces self-assembly into hollow vesicle structures with average hydrodynamic diameters (Dh) of ∼ 270 nm. CDDP conjugation is critical to the formation of the vesicles. The reactive maleimide-PEG moieties that form the corona and inner layer of the vesicles were protected via formation of a reversible Diels-Alder (DA) adduct throughout the block copolymer synthesis so as to maintain their integrity. Drug release studies demonstrated a low and sustained drug release profile in systemic conditions (pH = 7.4, [Cl(-)] = 140 mM) with a higher "burst-like" release rate being observed under late endosomal/lysosomal conditions (pH = 5.2, [Cl(-)] = 35 mM). Further, the peripheral maleimide functionalities on the vesicle corona were conjugated to thiol-functionalized folic acid (FA) (via in situ reduction of a novel bis-FA disulfide, FA-SS-FA) to form an active targeting drug delivery system. These targeting vesicles exhibited significantly higher cellular binding/uptake into and dose-dependent cytotoxicity toward cancer cells (HeLa) compared to noncancerous cells (NIH-3T3), which show high and low folic acid receptor (FR) expression, respectively. This work thus demonstrates a novel approach to polypeptide-based vesicle assembly and a promising strategy for targeted, effective CDDP anticancer drug delivery.