A sensitized RNA interference screen identifies a novel role for the PI3K p110γ isoform in medulloblastoma cell proliferation and chemoresistance.

Medulloblastoma is the most common malignant brain tumor in children and is associated with a poor outcome. We were interested in gaining further insight into the potential of targeting the human kinome as a novel approach to sensitize medulloblastoma to chemotherapeutic agents. A library of small interfering RNA (siRNA) was used to downregulate the known human protein and lipid kinases in medulloblastoma cell lines. The analysis of cell proliferation, in the presence or absence of a low dose of cisplatin after siRNA transfection, identified new protein and lipid kinases involved in medulloblastoma chemoresistance. PLK1 (polo-like kinase 1) was identified as a kinase involved in proliferation in medulloblastoma cell lines. Moreover, a set of 6 genes comprising ATR, LYK5, MPP2, PIK3CG, PIK4CA, and WNK4 were identified as contributing to both cell proliferation and resistance to cisplatin treatment in medulloblastoma cells. An analysis of the expression of the 6 target genes in primary medulloblastoma tumor samples and cell lines revealed overexpression of LYK5 and PIK3CG. The results of the siRNA screen were validated by target inhibition with specific pharmacological inhibitors. A pharmacological inhibitor of p110γ (encoded by PIK3CG) impaired cell proliferation in medulloblastoma cell lines and sensitized the cells to cisplatin treatment. Together, our data show that the p110γ phosphoinositide 3-kinase isoform is a novel target for combinatorial therapies in medulloblastoma.

Neuropathies périphériques d'origine médicamenteuse [Drug-induced peripheral neuropathy].

Drug-induced peripheral neuropathies are common, secondary to multiple drug classes, in particular chemotherapeutic agents. They have an important impact on patients' quality of life. In recent years, significant progress has been made in the understanding of some pathophysiological mechanisms. The use of more objective assessment tools should allow the development of individualized and more effective therapeutic strategies.

Expression of O⁶-methylguanine-DNA methyltransferase in childhood medulloblastoma.

Medulloblastomas (MB) are the most common malignant brain tumors in childhood. Alkylator-based drugs are effective agents in the treatment of patients with MB. In several tumors, including malignant glioma, elevated O(6)-methylguanine-DNA methyltransferase (MGMT) expression levels or lack of MGMT promoter methylation have been found to be associated with resistance to alkylating chemotherapeutic agents such as temozolomide (TMZ). In this study, we examined the MGMT status of MB and central nervous system primitive neuroectodermal tumor (PNET) cells and two large sets of primary MB. In seven MB/PNET cell lines investigated, MGMT promoter methylation was detected only in D425 human MB cells as assayed by the qualitative methylation-specific PCR and the more quantitative pyrosequencing assay. In D425 human MB cells, MGMT mRNA and protein expression was clearly lower when compared with the MGMT expression in the other MB/PNET cell lines. In MB/PNET cells, sensitivity towards TMZ and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) correlated with MGMT methylation and MGMT mRNA expression. Pyrosequencing in 67 primary MB samples revealed a mean percentage of MGMT methylation of 3.7-92% (mean: 13.25%, median: 10.67%). Percentage of MGMT methylation and MGMT mRNA expression as determined by quantitative RT-PCR correlated inversely (n = 46; Pearson correlation r (2) = 0.14, P = 0.01). We then analyzed MGMT mRNA expression in a second set of 47 formalin-fixed paraffin-embedded primary MB samples from clinically well-documented patients treated within the prospective randomized multicenter trial HIT'91. No association was found between MGMT mRNA expression and progression-free or overall survival. Therefore, it is not currently recommended to use MGMT mRNA expression analysis to determine who should receive alkylating agents and who should not.

Targeting PI3KC2β Impairs Proliferation and Survival in Acute Leukemia, Brain Tumours and Neuroendocrine Tumours.

BACKGROUND: Eight human catalytic phosphoinositide 3-kinase (PI3K) isoforms exist which are subdivided into three classes. While class I isoforms have been well-studied in cancer, little is known about the functions of class II PI3Ks. MATERIALS AND METHODS: The expression pattern and functions of the class II PI3KC2β isoform were investigated in a panel of tumour samples and cell lines. RESULTS: Overexpression of PI3KC2β was found in subsets of tumours and cell lines from acute myeloid leukemia (AML), glioblastoma multiforme (GBM), medulloblastoma (MB), neuroblastoma (NB), and small cell lung cancer (SCLC). Specific pharmacological inhibitors of PI3KC2β or RNA interference impaired proliferation of a panel of human cancer cell lines and primary cultures. Inhibition of PI3KC2β also induced apoptosis and sensitised the cancer cells to chemotherapeutic agents. CONCLUSION: Together, these data show that PI3KC2β contributes to proliferation and survival in AML, brain tumours and neuroendocrine tumours, and may represent a novel target in these malignancies.

Photodynamic therapy as an adjunct to surgery for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is increasingly observed in industrial countries. Despite concerted efforts and combined treatments including surgery, chemotherapy and irradiation patients eventually succumb from relentless local progression of the disease. Recent publications have demonstrated an improved response rate with the cytostatic agent pemetrexed which will be tested in a neoadjuvant setting followed by surgery. However, effective tumor control requires new loco-regional treatment modalities, eventually in combination with neoadjuvant chemotherapy. Intraoperative photodynamic therapy (PDT) of the chest cavity has been proposed as an attractive treatment concept for MPM since a selective treatment of the tumor bed following resection has the potential to improve local tumor control. It has been shown to afford tumor destruction in patients with mesothelioma but efficiency and selectivity is not yet sufficient for routine clinical application. Experimental work on MPM has shown that tumor selectivity of PDT depend on treatment conditions and can be improved by structural modification and improved targeting of the sensitizers. Refinements of PDT for mesothelioma will depend on a more detailed understanding of the pathways for preferential sensitizer accumulation within the tumor as well as on synergistic effects between PDT and chemotherapeutic agents.

Role of trabectedin in the treatment of soft tissue sarcoma.

Interest in marine natural products has allowed the discovery of new drugs and trabectedin (ET-743, Yondelis), derived from the marine tunicate Ecteinascidia turbinata, was approved for clinical use in 2007. It binds to the DNA minor groove leading to interferences with the intracellular transcription pathways and DNA-repair proteins. In vitro antitumor activity was demonstrated against various cancer cell lines and soft tissue sarcoma cell lines. In phase I studies tumor responses were observed also in osteosarcomas and different soft tissue sarcoma subtypes. The most common toxicities were myelosuppression and transient elevation of liver function tests, which could be reduced by dexamethasone premedication. The efficacy of trabectedin was established in three phase II studies where it was administered at 1.5 mg/m2 as a 24 h intravenous infusion repeated every three weeks, in previously treated patients. The objective response rate was 3.7%-8.3% and the tumor control rate (which included complete response, partial response and stable disease) was obtained in half of patients for a median overall survival reaching 12 months. In nonpretreated patients the overall response rate was 17%. Twenty-four percent of patients were without progression at six months. The median overall survival was almost 16 months with 72% surviving at one year. Predictive factors of response are being explored to identify patients who are most likely to respond to trabectedin. Combination with other agents are currently studied with promising results. In summary trabectedin is an active new chemotherapeutic agents that has demonstrated its role in the armamentarium of treatments for patients with sarcomas.

Agentes antineoplásicos biorredutíveis: uma nova alternativa para o tratamento de tumores sólidos

A problem often encountered in cancer therapy is the presence of tumor cell subpopulation that are resistant to treatment. Solid tumors frequently contain hypoxic cells that are resistant to killing by ionizing radiation and also by many chemotherapeutic agents. However, these hypoxic cells can be exploited for therapy by non-toxic hypoxic-activated prodrugs. Bioreductive drugs require metabolic reduction to generate cytotoxic metabolites. This process is facilitated by appropriate reductases and the lower oxygen conditions present in solid tumors. The unique presence of hypoxic cells in human tumors provides an important target for selective cancer therapy.

Síntese e caracterização de novos complexos de platina (II) com ligantes derivados do furano e nitrofurano

Platinum (II) complexes, for example, cisplatin and carboplatin, have been used as chemotherapeutic agents for the treatment of various types of cancer. Several other complexes of this metallic ion are also under clinical evaluation. This work describes the synthesis of five new platinum (II) complexes having furan and 5-nitrofuran derivatives and chloride as ligands. The compounds were characterized by NMR, IR and elemental analysis.

Estratégias utilizadas no combate a resistência bacteriana

This article provides an overview on the recent achievements to combat Gram-positive bacteria and the mechanisms related to antimicrobial activity and bacterial resistance. Selected synthetic methodologies to access structurally diverse bioactive compounds are presented in order to emphasize the most important substances currently developed to overcome multiresistant strains. The main properties of vancomycin and related glycopeptide antibiotics are also discussed as a background to understanding the design of new chemotherapeutic agents.

Síntese, avaliação biológica e modelagem molecular de arilfuranos como inibidores da enzima tripanotiona redutase

Trypanosoma cruzi is a protozoan parasite that causes a severe disease (Chagas'disease) in Central and South America. The currently available chemotherapeutic agents against this disease are still inadequate. The enzyme trypanothione reductase (TR) is considered a validated molecular target for the development of new drugs against this parasite. In this regard, a series of arylfurans based on 2,5-bis-(4-acetamidophenyl)furan was synthesized and tested for their in vitro inhibitory activity against TR. Molecular modeling studies of putative enzyme-inhibitor complexes revealed a possible mechanism of interaction. From synthesized compounds, a benzylaminofuran derivative was found to be more active than the lead compound.

First-Line Chemotherapy with Anthracycline and Taxane Combination in Metastatic Breast Cancer. Detection of bone metastases with TRACP 5b

Background: In Finland, breast cancer (BC) is the most common cancer among women, and prostate cancer (PC) that among men. At the metastatic stage both cancers remain essentially incurable. The goals of therapy include palliation of symptoms, improvement or maintenance of quality of life (QoL), delay of disease progression, and prolongation of survival. Balancing between efficacy and toxicity is the major challenge. With increasing costs of new treatments, appropriate use of resources is paramount. When new treatment regimes are introduced into clinical practice a comprehensive assessment of clinical benefit, adverse effects and cost is necessary. Both BC and PC show a predilection to metastasize to bone. Bone metastases cause significant morbidity impairing the patients´ QoL. Diagnosis of bone metastases relies mainly on radiological methods, which however lack optimal sensitivity and specificity. New tools are needed for detection and follow-up of bone metastases. Aims: Anthracyclines and taxanes are effective chemotherapeutic agents in the treatment of metastatic breast cancer (MBC) with different mechanisms of action. Therefore, evaluation of the combination of anthracyclines with taxanes was a justifiable approach in the treatment of MBC patients. We assessed the efficacy, toxicity, cost of treatment and QoL of BC patients treated with first-line chemotherapy for metastatic disease with the combination epirubicin and docetaxel. We also evaluated the diagnostic potential of tartrate-resistant acid phosphatase 5b (TRACP 5b) and carboxyterminal telopeptides of type I collagen (ICTP) in the diagnosis of bone metastases in BC and TRACP 5b in PC patients. Results: The combination of epirubicin and docetaxel was effective in this phase II study, but required individual dose adjustment to avoid neutropenic infections, and the use of growth factors to maintain a feasible dose level. The response rate was 54 % (95 % CI 37-71) and the median overall survival (OS) was 26 months. Of the patients, 87 % were treated for infections. The treatment of adverse events required additional use of health resources mainly due to neutropenic infections, thereby raising direct treatment costs by 20 %. Despite adverse events, the global QoL was not significantly compromised during the treatment. Clinically evident acute cardiac toxicity was not observed. The combination of serum TRACP 5b and ICTP was at least equally sensitive and specific in detection of of bone metastases as commonly used total alkaline phosphatise (tALP) in BC patients. In contrast, TRACP 5b was less specific and sensitive than tALP as a marker of skeletal changes in PC patients. Conclusions: Treatment with epirubicin and docetaxel showed high efficacy in first-line chemotherapy of MBC. The relatively high incidence of neutropenic infections requiring hospitalization increased the treatment costs. Despite adverse events, the global QoL of the patients was not significantly compromised. The combination of TRACP 5b and ICTP showed similar activity as tALP in detecting bone metastases in MBC. In contrast, TRACP 5b was less specific and sensitive than tALP as a marker of skeletal changes in PC.

In vitro cytotoxicity of the LDE: daunorubicin complex in acute myelogenous leukemia blast cells

Acute myelogenous leukemia (AML) blast cells show high-affinity degradation of low-density lipoprotein (LDL), suggesting an increased expression of cellular LDL receptors. LDE is a lipid microemulsion easily synthesized in vitro which is known to mimic the metabolic pathway of LDL. We used LDE as a carrier for daunorubicin and assayed the cytotoxicity of the complex using AML blast cells since RT-PCR analysis showed that AML cells express LDL receptor mRNA. The LDE:daunorubicin complex killed 46.7% of blast cells and 20.2% of normal bone marrow cells (P<0.001; Student t-test). Moreover, this complex destroyed AML blast cells as efficiently as free daunorubicin. Thus, LDE might be a suitable carrier of chemotherapeutic agents targeting these drugs to neoplastic cells and protecting normal tissues.

Respiration, oxidative phosphorylation, and uncoupling protein in Candida albicans

The respiration, membrane potential (Dy), and oxidative phosphorylation of mitochondria in situ were determined in spheroplasts obtained from Candida albicans control strain ATCC 90028 by lyticase treatment. Mitochondria in situ were able to phosphorylate externally added ADP (200 µM) in the presence of 0.05% BSA. Mitochondria in situ generated and sustained stable mitochondrial Dy respiring on 5 mM NAD-linked substrates, 5 mM succinate, or 100 µM N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride plus 1 mM ascorbate. Rotenone (4 µM) inhibited respiration by 30% and 2 µM antimycin A or myxothiazole and 1 mM cyanide inhibited it by 85%. Cyanide-insensitive respiration was partially blocked by 2 mM benzohydroxamic acid, suggesting the presence of an alternative oxidase. Candida albicans mitochondria in situ presented a carboxyatractyloside-insensitive increase of Dy induced by 5 mM ATP and 0.5% BSA, and Dy decrease induced by 10 µM linoleic acid, both suggesting the existence of an uncoupling protein. The presence of this protein was subsequently confirmed by immunodetection and respiration experiments with isolated mitochondria. In conclusion, Candida albicans ATCC 90028 possesses an alternative electron transfer chain and alternative oxidase, both absent in animal cells. These pathways can be exceptional targets for the design of new chemotherapeutic agents. Blockage of these respiratory pathways together with inhibition of the uncoupling protein (another potential target for drug design) could lead to increased production of reactive oxygen species, dysfunction of Candida mitochondria, and possibly to oxidative cell death.

Downregulation of survivin by siRNA inhibits invasion and promotes apoptosis in neuroblastoma SH-SY5Y cells

Neuroblastoma is a solid tumor that occurs mainly in children. Malignant neuroblastomas have a poor prognosis because conventional chemotherapeutic agents are not very effective. Survivin, a member of the inhibitor of the apoptosis protein family, plays a significant role in cell division, inhibition of apoptosis, and promotion of cell proliferation and invasion. Previous studies found that survivin is highly expressed in some malignant neuroblastomas and is correlated with poor prognosis. The aim of this study was to investigate whether survivin could serve as a potential therapeutic target of human neuroblastoma. We employed RNA interference to reduce survivin expression in the human neuroblastoma SH-SY5Y cell line and analyzed the effect of RNA interference on cell proliferation and invasion in vitro and in vivo. RNA interference of survivin led to a significant decrease in invasiveness and proliferation and increased apoptosis in SH-SY5Y cells in vitro. RNA interference of survivin inhibited tumor growth in vivo by 68±13% (P=0.002) and increased the number of apoptotic cells by 9.8±1.2% (P=0.001) compared with negative small interfering RNA (siRNA) treatment controls. Moreover, RNA interference of survivin inhibited the formation of lung metastases by 92% (P=0.002) and reduced microvascular density by 60% (P=0.0003). Survivin siRNA resulted in significant downregulation of survivin mRNA and protein expression both in vitro and in vivo compared with negative siRNA treatment controls. RNA interference of survivin was found to be a potent inhibitor of SH-SY5Y tumor growth and metastasis formation. These results support further clinical development of RNA interference of survivin as a treatment of neuroblastoma and other cancer types.

Factors associated with Clostridium difficile diarrhea in a hospital in Beijing, China

Clostridium difficile is the most common cause of hospital-acquired diarrhea in patients treated with antibiotics, chemotherapeutic agents, and other drugs that alter the normal equilibrium of the intestinal flora. A better understanding of the risk factors for C. difficile-associated disease (CDAD) could be used to reduce the incidence of CDAD and the costs associated with its treatment. The aim of this study was to identify the risk factors for CDAD in a cohort of Chinese patients in a Beijing hospital. Medical charts of a total of 130 inpatients (62 males and 68 females) with hospital-acquired diarrhea (45 with CDAD; 85 without CDAD) were retrospectively reviewed. C. difficile toxins A and B were detected in fecal samples using enzyme-linked fluorescence assays. The drugs used by patients with and without CDAD before the onset of diarrhea were compared. Factors that differed significantly between the two groups by univariate analysis were analyzed by multivariate analysis using a logistic regression model. Multivariate analysis showed that cephalosporin treatment was associated with a significantly higher risk of CDAD in hospitalized patients, while treatment with glycopeptides was significantly associated with a reduction in CDAD (P<0.001 for cephalosporin; P=0.013 for glycopeptides). Our data confirmed previous findings that empirical treatment with cephalosporins is positively associated with CDAD compared to individuals using other CDAD-related drugs. Additionally, we showed that treatment with glycopeptides was negatively associated with CDAD, compared to individuals using other CDAD-related drugs.