Cellular pharmacology of multi- and duplex drugsconsisting of ethynylcytidine and 5-fluoro-2′-deoxyuridine

Prodrugs can have the advantage over parent drugs in increased activation and cellular uptake. The multidrug ETC-L-FdUrd and the duplex drug ETC-FdUrd are composed of two different monophosphate-nucleosides, 5-fluoro-2′deoxyuridine (FdUrd) and ethynylcytidine (ETC), coupled via a glycerolipid or phosphodiester, respectively. The aim of the study was to determine cytotoxicity levels and mode of drug cleavage. Moreover, we determined whether a liposomal formulation of ETC-L-FdUrd would improve cytotoxic activity and/or cleavage. Drug effects/cleavage were studied with standard radioactivity assays, HPLC and LC-MS/MS in FM3A/0 mammary cancer cells and their FdUrd resistant variants FM3A/TK−. ETC-FdUrd was active (IC50 of 2.2 and 79 nM) in FM3A/0 and TK− cells, respectively. ETC-L-FdUrd was less active (IC50: 7 nM in FM3A/0 vs 4500 nM in FM3A/TK−). Although the liposomal formulation was less active than ETC-L-FdUrd in FM3A/0 cells (IC50:19.3 nM), resistance due to thymidine kinase (TK) deficiency was greatly reduced. The prodrugs inhibited thymidylate synthase (TS) in FM3A/0 cells (80–90%), but to a lower extent in FM3A/TK− (10–50%). FdUMP was hardly detected in FM3A/TK− cells. Inhibition of the transporters and nucleotidases/phosphatases resulted in a reduction of cytotoxicity of ETC-FdUrd, indicating that this drug was cleaved outside the cells to the monophosphates, which was verified by the presence of FdUrd and ETC in the medium. ETC-L-FdUrd and the liposomal formulation were neither affected by transporter nor nucleotidase/phosphatase inhibition, indicating circumvention of active transporters. In vivo, ETC-FdUrd and ETC-L-FdURd were orally active. ETC nucleotides accumulated in both tumor and liver tissues. These formulations seem to be effective when a lipophilic linker is used combined with a liposomal formulation

Metabolism and accumulation of the lipophilic deoxynucleoside analogs elacytarabine and CP-4126

Cytarabine (ara-C) and gemcitabine (dFdC) are commonly used anticancer drugs, which depend on the equilibrative (ENT) and concentrative-nucleoside-transporters to enter the cell. To bypass transport-related drug resistance, lipophilic derivatives elacytarabine (CP-4055), ara-C-5′elaidic-acid-ester, and CP-4126, (CO 1.01) gemcitabine-5′elaidic-acid-ester, were investigated for the entry into the cell, distribution, metabolism and retention. The leukemic CEM-cell-line and its deoxycytidine-kinase deficient variant (CEM/dCK-) were exposed for 30 and 60 min to the radiolabeled drugs; followed by culture in drug-free medium in order to determine drug retention in the cell. The cellular fractions were analyzed with thin-layer-chromatography and HPLC. Elacytarabine and CP-4126 were converted to the parent compounds both inside and outside the cell (35–45%). The ENT-inhibitor dipyridamole did not affect their uptake or retention. Inside the cell Elacytarabine and CP-4126 predominantly localized in the membrane and cytosolic fraction, leading to a long retention after removal of the medium. In contrast, in cells exposed to the parent drugs ara-C and dFdC, intracellular drug concentration increased during exposure but decreased to undetectable levels after drug removal. In the dCK- cell line, no metabolism was observed. The concentrations of ara-CTP and dFdCTP reached a peak at the end of the incubation with the drugs, and decreased after drug removal; peak levels of dFdCTP were 35 times higher than ara-CTP and was retained better. In contrast, after exposure to elacytarabine or CP-4126, ara-CTP and dFdCTP levels continued to increase not only during exposure but also during 120 min after removal of the elacytarabine and CP-4126. Levels of ara-CTP and dFdCTP were higher than after exposure to the parent drugs. In conclusion, the lipophilic derivatives elacytarabine and CP-4126 showed a nucleoside-transporter independent uptake, with long retention of the active nucleotides. These lipophilic nucleoside analogues are new chemical entities suitable for novel clinical applications

Adjuvant Pharmacotherapy in the Management of Elderly Patients with Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is the fourth or fifth leading cause of death from cancer in Western industrialized countries. Surgical resection is the only chance of cure, but only 15-20 % of cases are potentially resectable at presentation, and despite complete resection, the overall prognosis remains relatively poor. Adjuvant therapy has modestly improved cure rates. The majority of patients with pancreatic cancer are over the age of 65 years. But this age group is underrepresented within clinical trials, and it is unknown whether older patients achieve similar results to younger ones in terms of survival and treatment tolerance. In addition, there are no clinical trials dedicated to the elderly. Retrospective studies coming from the non-resectable setting provide some understanding on outcomes in older patients with PDAC. To date, we can reasonably argue that selected elderly patients with PDAC can benefit from curative surgery and postoperative chemotherapy as do their younger counterparts, without a significant increase in morbidity and mortality. Gemcitabine should be preferred to 5-fluorouracil on the basis of a better risk-benefit balance.JOURNAL ARTICLESCOPUS: re.jinfo:eu-repo/semantics/publishe

Carrot floral development and reproductive biology

The defining characteristic of the botanical family of Apiaceae (former Umbelliferae) is the inflorescence. The flowers aggregate in terminal umbels that may be commonly compound, often umbelliform cymes. Likewise, flowers of the carrot are clustered in flat, dense umbels, partially with zygomorphic petals at the edges. Carrot producers and consumers mainly consider the vegetative phase namely the storage root as vegetable. Nevertheless, the reproductive phase is an important topic for genetic research, for breeding new cultivars and seed production. Hence, an improved knowledge on the genetic control mechanisms of reproduction such as flowering time, flower development and architecture, pollen fertility and male sterility as well as seed set are of essential importance. The chapter reviews key steps on carrot floral development and reproductive biology especially under consideration of the comprehensive genomic data set recently obtained from carrot.Fil: Linke, Betina. Humboldt-Universität zu Berlin; AlemaniaFil: Alessandro, Maria Soledad. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Mendoza-San Juan. Estación Experimental Agropecuaria La Consulta; ArgentinaFil: Galmarini, Claudio Romulo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Mendoza-San Juan. Estación Experimental Agropecuaria La Consulta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; ArgentinaFil: Nothnagel, Thomas. Institute for Breeding Research on Horticultural Crops; Alemani