Multiple-pulse drug delivery systems: setting a new paradigm for infectious disease therapy

Background: Pulsatile drug delivery of actives based on the body's biological rhythms came into sight as a novel and emerging concept in the field of drug delivery. The concept of late has given birth to another field of research worth exploring: multiple-pulse drug delivery. Objective: Delivering a drug in multiple pulses has been applied to antibiotics for effective and patient compliant drug delivery. Delivering antibiotics in divided pulses results in better annihilation of microbes, as it prevents them going into a resistant/dormant stage and developing biological tolerance. The concept appears to have potential, and on 16 March 2009 MiddleBrook^? Pharmaceuticals, Inc. will launch the first of such once-daily product based on their proprietary pulsatile drug delivery technology, PULSYS^?. Methods: This review focuses on the rationale, possible strategies and technologies employed for multiple-pulse delivery, as well as current status and future trends. Conclusion: The concept is in its infancy and promises great potential in the fight against microbial resistance; many approved formulations based on similar approaches with new and improved therapeutic paradigms are anticipated in the near future.     

Gene therapy approaches for the selective killing of cancer cells

This review describes gene therapy strategies that take advantage of defective signal transduction pathways to selectively kill cancer cells without adversely affecting normal cells. The distinctive features of cancer cells currently exploited by gene therapy include mitosis, cell permissiveness to infection, specific protease activity, and the activity of the p53, Rb/E2F and wnt/catenin signal transduction pathways. In most cases, proof of concept has been obtained in vitro and in vivo, but only a few approaches made it to the clinic. Overall, the clinical success rate has been disappointing and it is concluded that the gene therapy of cancer requires more innovation and hard work before its potential can be fully realized.     

Differential cytostatic and cytotoxic action of Metallocorroles against human cancer cells: potential platforms for anticancer drug development

A gallium(III)-substituted amphiphilic corrole noncovalently associated with a targeting protein was previously found by us to confer promising cytotoxic and antitumor activities against a breast cancer cell line and a mouse xenograft breast cancer model. To further explore potential anticancer applications, the cytostatic and cytotoxic properties of six nontargeted metallocorroles were evaluated against seven human cancer cell lines. Results indicated that toxicity toward human cancer cells depended on the metal ion as well as corrole functional group substitution. Ga(III)-substituted metallocorrole 1-Ga inhibited proliferation of breast (MDA-MB-231), melanoma (SK-MEL-28), and ovarian (OVCAR-3) cancer cells primarily by arrest of DNA replication, whereas 2-Mn displayed both cytostatic and cytotoxic properties. Confocal microscopy revealed extensive uptake of 1-Ga into the cytoplasm of melanoma and ovarian cancer cells, while prostate cancer cells (DU-145) displayed extensive nuclear localization. The localization of 1-Ga to the nucleus in DU-145 cells was exploited to achieve a 3-fold enhancement in the IC(50) of doxorubicin upon coadministration. Time-course studies showed that over 90% of melanoma cells incubated with 30 μM 1-Ga internalized metallocorrole after 15 min. Cellular uptake of 1-Ga and 1-Al was fastest and most efficient in melanoma, followed by prostate and ovarian cancer cells. Cell cycle analyses revealed that bis-sulfonated corroles containing Al(III), Ga(III), and Mn(III) induced late M phase arrest in several different cancer cell lines, a feature that could be developed for potential therapeutic benefit.     

Update on non-viral delivery methods for cancer therapy: possibilities of a drug delivery system with anticancer activities beyond delivery as a new therapeutic tool

Importance of the field: Cancer is the most formidable human disease. Owing to the heterogeneity of cancer, a single-treatment modality is insufficient for the complete elimination of cancer cells. Therapeutic strategies from various aspects are needed for cancer therapy. These therapeutic agents should be carefully selected to enhance multiple therapeutic pathways. Non-viral delivery methods have been utilized to enhance the tumor-selective delivery of therapeutic molecules, including proteins, synthetic oligonucleotides, small compounds and genes.

Areas covered in this review: As non-viral delivery methods, liposomes and polymer-based delivery materials to target tumors mainly by systemic delivery, physical methods including electroporation, sonoporation, and so on, to locally inject therapeutic molecules, and virosomes to use the viral infectious machinery for the delivery of therapeutic molecules are summarized.

What the reader will gain: This article aims to provide an overview of the characteristic properties of each non-viral vector. It will be beneficial to utilize appropriately the vector for cancer treatment.

Take home message: Efficient and minimally invasive vectors are generally considered to be the ideal drug delivery system (DDS). However, against cancer, DDS equipped with antitumor activities may be a therapeutic choice. By combining therapeutic molecules with DDS having antitumor activities, enhancement of the multiple therapeutic pathways may be achieved.     

Ceramide analogues in apoptosis: a new strategy for anticancer drug development

A survey on the role played by ceramide within the sphingolmyelin pathway is here reported, taking into account its importance as an intracellular effector molecule in apoptosis. Recently, several analogs of ceramide, able to pass the cell membrane and then to induce apoptosis, have been developed as a new potential approach in anticancer therapy.     

Induction chemotherapy in head and neck cancer: a new paradigm

Five hundred and fifty thousand new head and neck cancer cases are diagnosed each year worldwide. They are mostly locally advanced squamous cell carcinoma with a poor prognosis in terms of locoregional and distant failure. A major challenge for patients with locally advanced squamous cell carcinoma is to achieve a high cure rate while preserving functions. Treatment strategies are designed according to the disease stage, primary site, operable status, patient age, and performance status. Surgery, radiation therapy, chemotherapy, and more recently molecular-targeted therapies are part of these strategies, but their sequence remains to be defined. Over the last 30 years, induction chemotherapy has attained an important position in the management of patients with locally advanced squamous cell carcinoma, particularly since the introduction of taxanes. The decision to deliver induction chemotherapy (and its intensification) must be considered in the light of other treatments aiming at better locoregional control (normofractioned radiotherapy, accelerated or hyperfractionated radiotherapy, addition of concurrent chemotherapy, or of targeted therapy) with or without adjuvant treatment. This review summarizes the rationale, these data, and perspectives on induction chemotherapy-based strategies.     

Targeted molecular strategies for cancer therapy based on the blockage of oncogenic pathways in human tumor cells

Constitutive activation of the extracellular signal-regulated kinase (ERK) and/or phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathways is associated with neoplastic transformation of a variety of human tumor cells. Treatment of such tumor cells with agents that specifically inhibit the activity of mitogen-activated protein kinase/ERK kinase (MEK) or PI3K completely suppresses their proliferation. However, treatment of cells with these inhibitors leads to only a modest increase in apoptotic cell death. Efficient induction of apoptosis is essential for the development of effective cancer chemotherapy. Therefore, we have examined whether specific blockade of these two signaling pathways affects the efficacy of the induction of apoptosis by various anti-cancer agents in tumor cells. We found that MEK inhibitors markedly enhance the efficacy of histone deacetylase inhibitors to induce the generation of reactive oxygen species and apoptosis. This effect was only observed in tumor cells in which the ERK pathway was constitutively activated. Furthermore, we found that PI3K inhibitors selectively and markedly enhanced the efficacy of the induction of apoptosis by doxorubicin. This latter effect was only detected in tumor cells in which the PI3K/Akt pathway was constitutively activated and in which the p53 pathway was functional. These combination treatments provide an efficient chemotherapeutic strategy for the treatment of tumor cells in which the ERK pathway or PI3K/Akt pathway is constitutively activated. This review gives an overview of the development of new targeted molecular strategies for cancer therapy based on the suppression of the activity of oncogenic pathways involved in the proliferation or survival of tumor cells.     

Induction of apoptosis in human ovarian cancer cells by new anticancer compounds,epothilone A and B

Epothilones are a new group of compounds with action mechanisms similar to taxanes. The aim of this study was to compare the effects of epothilone A (Epo A) and epothilone B (Epo B) on ovarian cancer cell line SKOV-3 with those of paclitaxel (PTX), a classic taxane. We evaluate glycoprotein P (P-gp) activity in the ovarian cancer cell line. Apoptotic and necrotic cell levels were measured by double staining with Hoechst 33258 and propidium iodide (PI) as well as Annexin V staining. The production of reactive oxygen species (ROS) and changes in mitochondrial membrane potential (ΔΨm) in cells exposed to Epo A, Epo B and PTX were studied using specific fluorescence probes, DCFH₂-DA (2′,7′-dichlorodihydrofluorescein diacetate) and JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolcarbocyanine). The cytotoxic activity of the drugs was determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide) test. All probes were analyzed in both the presence and absence of the antioxidant N-acetylcysteine (NAC). The results obtained demonstrated that the antiproliferative capacity of Epo A and Epo B in SKOV-3 cell line (measured as IC₅₀ after 72 h continuous treatment) was six and five times greater than that of PTX’s respectively. Epothilones induced timecourse-dependent apoptosis and necrosis. Apoptotic and necrotic events were partially blocked by NAC, indicating ROS played a substantial role in epothilone-induced apoptosis. Cell death was also associated with a decrease in mitochondrial membrane potential, which was more pronounced after treatment with epothilones as compared to paclitaxel.     

Generation of suppressor cells in normal rats by treatment with spirogermanium, a novel heterocyclic anticancer drug

Daily oral administration of spirogermanium to Lewis rats resulted in the generation of radiation-resistant (2000 Rad) suppressor cells which inhibited the proliferative response of normal spleen cells to an optimum concentration of concanavalin A. These suppressor cells became evident after three to six days of spirogermanium administration. After one day's treatment, although no suppressor cells could be detected, the response of these cells to concanavalin A was less than 50% of controls. Experiments designed to characterize the cell type(s) responsible for this suppression resulted in the finding that T cell-'depleted' populations of spleen cells were more suppressive than T cell-'enriched' populations. The induction of suppressor cells by spirogermanium and the previously described activity in the adjuvant arthritic rat model suggest therapeutic potential for autoimmune diseases.     

Selective anticancer effects of a synthetic flavagline on human Oct4-expressing cancer stem-like cells via a p38 MAPK-dependent caspase-3-dependent pathway

Cancer stem cells (CSCs) are considered as the initiators of the carcinogenic process and are therefore emerging targets for innovative anticancer therapies. In order to evaluate the anticancer chemopreventive activity of flavagline derivatives, we used the pluripotent teratocarcinomal cell as a model of Oct4-expressing cancer stem-like cell and determined the underlying cellular and molecular mechanisms induced by a synthetic flavagline. We precisely investigated the effects of the flavagline derivative FL3 on the human embryonal carcinoma (EC) cell line NT2/D1 and compared the responses to those of a normal more restrictive pluripotent stem cell line (i.e. BJ fibroblast cell line). FL3 selectively inhibited the proliferation of NT2/D1 cells by inducing G₁ phase cell cycle arrest in a dose-dependent manner. Moreover, FL3 treatment specifically triggered apoptosis in association with an induction of the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and caspase-3 activation followed by a drastic downregulation of the master regulator of stemness Oct4. Forced inhibition of p38 MAPK activity by the specific pharmacological inhibitor SB203580 or by p38 MAPK gene knockdown using small-interfering RNA (siRNA) counteracted the effects of FL3, demonstrating that its chemopreventive action is related to growth inhibition and a p38-dependent caspase-3-dependent induction of apoptosis in Oct4-expressing CSCs. This study also shows that FL3 selectively kills poorly differentiated and highly aggressive carcinomal cells, but has little effect on normal stem-like cells. Thus FL3 offers great promise for cancer treatment since it is able to target the carcinogenic process without affecting normal cells.     

胃癌及癌前病变中基因丢失的研究

目的选择9号染色体上10个位点的微卫星序列,检测35例胃癌及癌前病变的等位基因杂合性丢失(LOH),以了解9号染色体上与胃癌发生发展相关的抑癌基因的变化。方法从山西省肿瘤医院手术切除的800余例胃癌标本中选择伴有高级别异型增生的病例35例。标本经酒精固定,常规石蜡包埋制片,显微切割分别获取正常体细胞、异型增生和胃腺癌的DNA聚合酶链反应(PCR)扩增,高压电泳,放射自显影进行LOH分析。结果在胃癌组织中10个位点的LOH率依次为:IFNA50%,D9S17150%,D9S111848%,D9S94148%,D9S17548%,D9S182232%,D9S16631%,D9S91024%,D9S94223%,D9S187623%,可见前五者与胃癌关系密切,在高级别异型增生,仅个别病例发生LOH,无统计学意义。结论①胃癌的发生发展是一个多阶段、多基因参与的复杂过程;②9号染色体上基因的缺失是胃癌发生发展过程中的常见事件,并且可能主要与胃癌的演进有关;③D9S171、IFNA、D9S941、D9S175、D9S1118附近可能存在与胃癌发生有关的抑癌基因;④多位点检测LOH可以寻找与胃癌有关的抑癌基因,并对其早期诊断和治疗具有理论意义和一定的实用价值。     

CDC50A plays a key role in the uptake of the anticancer drug perifosine in human carcinoma cells

Functional aminophospholipid translocases are composed of at least two proteins: an alpha subunit from the P4 subfamily of P-type ATPases and a beta subunit from the CDC50-Lem3p family. Over-expression and knockdown of the human beta subunit CDC50A in KB cells enhanced and decreased, respectively, the uptake of both fluorescent aminophospholipid analogues and the anticancer alkyl-phospholipid perifosine. Confocal microscopy showed that CDC50A-V5 was localized at the endoplasmic reticulum and the Golgi complex of both KB (perifosine-sensitive) and KB PER-R (perifosine-resistant, alkyl-phospholipid uptake deficient) cells, but was only widely distributed in the early and late endosomes in KB cells. Biotinylation of cell surface proteins allowed CDC50A-V5 to be detected in the plasma membrane of KB cells but not in KB PER-R cells, thereby suggesting a defect in CDC50A trafficking that could explain the inability of KB PER-R to uptake perifosine. Over-expression of CDC50A in HeLa and HEK293T cells did not increase uptake, since the protein was retained at the endoplasmic reticulum and Golgi. However, when CDC50A was co-expressed with the P4-ATPase Atp8b1, the two proteins co-localized at the plasma membrane and the uptake of aminophospholipids and perifosine increased strikingly in both cell lines. These findings suggest that CDC50A plays a key role in perifosine uptake in human cells, presumably by forming a functional plasma membrane translocator in combination with a P4-ATPase.     

A new nonlinear mixture response surface paradigm for the study of synergism: a three drug example

A flexible approach to response surface modeling for the study of the joint action of three active anticancer agents is used to model a complex pattern of synergism, additivity and antagonism in an in vitro cell growth assay. The method for determining a useful nonlinear response surface model depends upon a series of steps using appropriate scaling of drug concentrations and effects, raw data modeling, and hierarchical parameter modeling. The method is applied to a very large in vitro study of the combined effect of Trimetrexate (TMQ), LY309887 (LY), and Tomudex (TDX) on inhibition of cancer cell growth. The base model employed for modeling dose-response effect is the four parameter Hill equation [1]. In the hierarchical aspect of the final model, the base Hill model is treated as a function of the total amount of the three drug mixture and the Hill parameters, background B, dose for 50% effect D50, and slope m, are understood as functions of the three drug fractions. The parameters are modeled using the canonical mixture polynomials from the mixture experiment methodologies introduced by Scheff [2]. We label the model generated a Nonlinear Mixture Amount model with control observations, or zero amounts, an "NLMAZ" model. This modeling paradigm provides for the first time an effective statistical approach to modeling complex patterns of local synergism, additivity, and antagonism in the same data set, the possibility of including additional experimental components beyond those in the mixture, and the capability of modeling three or more drugs.     

Rimonabant: new drug. Obesity: loss of a few kilos, many questions

(1) The treatment of obesity is based on calorie reduction and moderate physical activity. (2) Rimonabant, a CB1 cannabinoid receptor antagonist, is marketed in Europe for the adjuvant treatment of obesity, in combination with a low-calorie diet and physical exercise. (3) Four double-blind placebo-controlled trials involving about 6500 patients show that, when combined with a low-calorie diet, rimonabant 20 mg/day leads to an average weight loss of 4 or 5 kg more than placebo after one year of treatment. This is similar to the weight loss reported with orlistat (indirect comparison). Effects on the lipid profile are similar to those reported with sibutramine. (4) Rimonabant has not been shown to reduce morbidity or mortality. Patients regain the weight they lost within about 9 months after rimonabant withdrawal. (5) Three placebo-controlled trials have evaluated rimonabant in smoking cessation. The available results (a single conference abstract) are inconclusive. In early 2006 the FDA and the European Medicines Agency refused to approve rimonabant for this use. (6) Adverse effects mentioned in published clinical trials of rimonabant include mental disorders (anxiety, depression), neurological disorders (dizziness) and gastrointestinal disorders (nausea, diarrhoea). No postmarketing safety data are available. The possible long-term adverse effects of rimonabant are unknown. (7) In practice, when drug therapy is considered for weight loss, it seems unwise to prescribe rimonabant: this new drug has only limited symptomatic effects and its adverse effects, especially in the long term, are poorly documented.     

Selective apoptotic effects of piceatannol and myricetin in human cancer cells

Numerous studies have shown the potential of dietary polyphenols as anticarcinogenic agents. The aim of the present study was to evaluate the apoptotic effects of piceatannol and myricetin, naturally occurring polyphenols in red wine, alone or in combination, in two human cell lines: HL‐60 (leukemia) and HepG2 (hepatoma). Apoptotic cells were identified by chromatin condensation, poly(ADP‐ribose) polymerase cleavage and flow cytometry analysis. Results from TUNEL assay showed that piceatannol or myricetin alone induced apoptotic cell death in a concentration‐ and time‐dependent manners in HL‐60 cells. Furthermore, in combined treatment the percentage of apoptotic HL‐60 cells was significantly higher. Nevertheless, the percentage of TUNEL positive HepG2 cells only was significant after piceatannol treatment and in combined treatment was even lower than in cells treated with piceatannol alone. Moreover, we also studied the relative reactive oxygen species (ROS) production. Our results indicate that apoptosis induced by piceatannol or myricetin occurs through an ROS‐independent cell death pathway. In conclusion, piceatannol and myricetin synergistically induced apoptosis in HL‐60 cells but not in HepG2 cells. These findings suggest that the potential anticarcinogenic properties of dietary polyphenols depend largely on the cell line used. The relevance of these data needs to be verified in human epidemiological studies. Copyright © 2011 John Wiley & Sons, Ltd.