Background: 5-Fluorouracil (5-FU) is an antimetabolite that interferes with DNA synthesis and has been widely used as a chemotherapeutic drug in various types of cancers. However, the development of drug resistance greatly limits its application. Overexpression of ATP-binding cassette (ABC) transporters in many types of cancer is responsible for the reduction of the cellular uptake of various anticancer drugs causing multidrug resistance (MDR), the major obstacle in cancer chemotherapy. Recently, we have obtained a novel synthetic 5-FU analog, U-332 [(R)-3-(4-bromophenyl)-1-ethyl-5-methylidene-6-phenyldihydrouracil], combining a uracil skeleton with an exo-cyclic methylidene group. U-332 was highly cytotoxic for HL-60 cells and showed similar cytotoxicity in the 5-FU resistant subclone (HL-60/5FU), in which this analog almost completely abolished expression of the ATP-binding cassette (ABC) transporter, multidrug resistance associate protein 1 (ABCC1). The expression of ABC transporters is usually correlated with NF-κB activation. The aim of this study was to determine the level of NF-κB subunits in the resistant HL-60/5-FU cells and to evaluate the potential of U-332 to inhibit activation of NF-κB family members in this cell line. Methods: Anti-proliferative activity of compound U-332 was assessed by the MTT assay. In order to disclose the mechanism of U-332 cytotoxicity, quantitative real-time PCR analysis of the NF-κB family genes, c-Rel, RelA, RelB, NF-κB1, and NF-κB2, was investigated. The ability of U-332 to reduce the activity of NF-κB members was studied by ELISA test. Results: In this report it was demonstrated, using RT-PCR and ELISA assay, that members of the NF-κB family c-Rel, RelA, RelB, NF-κB1, and NF-κB2 were all overexpressed in the 5-FU-resistant HL-60/5FU cells and that U-332 potently reduced the activity of c-Rel, RelA and NF-κB1 subunits in this cell line. Conclusions: This finding indicates that c-Rel, RelA and NF-κB1 subunits are responsible for the resistance of HL-60/5FU cells to 5-FU and that U-332 is able to reverse this resistance. U-332 can be viewed as an important lead compound in the search for novel drug candidates that would not cause multidrug resistance in cancer cells.

Activated vinylphosphonates constitute a very important group of organic reagents which have found broad application in organic synthesis. The most important feature of activated vinylphosphonates is certainly their ability to undergo Michael additions in which a wide variety of carbo-and heteronucleophiles can be used. This review presents the potential of activated vinylphosphonates as Michael acceptors and shows possible applications of the thusformed adducts, in particular as Horner-Wadsworth-Emmons olefinating reagents, in the synthesis of important carbo-and heterocycles as well as acyclic compounds. Selected preparations of activated vinylphosphonates are also described.

The synthesis of alpha-, beta- and gamma-substituted alpha-phosphono-gamma-lactones was accomplished using different ring closure and ring homologation strategies. It was found that the lactones could be selectively transformed into the corresponding ethyl cyclopropanecarboxylates by treatment with sodium ethoxide in boiling THF. The reported reaction provides an attractive alternative to the classical homologous Horner-Wadsworth-Emmons approach to the construction of cyclopropanes with electron-withdrawing functionalities.

A Novel Approach to g-Hydroxy-a,b-unsaturated Compounds S y n t h e s i s o f g -H y d r o x y -a , b -u n s a t u r a t e d C o m p o u n d s Abstract: A simple synthesis of (E)-alk-1-enyl mesylates from (E)-alk-1-enylphosphonates is reported. Construction of g-hydroxya,b-unsaturated compounds was achieved by a two-step process involving dihydroxylation of the enol mesylates followed by HWE reaction of the resulting a-hydroxy aldehydes with activated methylphosphonates. Enantioselective synthesis of the title compounds is also reported.