Synthesis and biological evaluation of phenstatin metabolites.

Previous investigations on the incubation of phenstatin with rat and human microsomal fractions revealed the formation of nine main metabolites. The structures of eight of these metabolites have been now confirmed by synthesis and their biological properties have been reported. Eaton's reagent was utilized as a convenient condensing agent, allowing, among others, a simple multigram scale preparation of phenstatin. Synthesized metabolites and related compounds were evaluated for their antiproliferative activity in the NCI-60 cancer cell line panel, and for their effect on microtubule assembly. Metabolite 23 (2'-methoxyphenstatin) exhibited the most potent in vitro cytotoxic activity: inhibition of the growth of K-562, NCI-H322M, NCI-H522, KM12, M14, MDA-MB-435, NCI/ADR-RES, and HS 578T cell lines with GI(50) values <10nM. It also showed more significant tubulin polymerization inhibitory activity than parent phenstatin (3) (IC(50)=3.2 µM vs 15.0 µM) and induced G2/M arrest in murine leukemia DA1-3b cells. The identification of this active metabolite led to the design and synthesis of analogs with potent in vitro cytotoxicity and inhibition of microtubule assembly.

In vitro metabolism of phenstatin: potential pharmacological consequences.

Phenstatin and its derivatives are potential anticancer drug candidates according to their inhibitory properties on tubulin polymerization, cell growth and antivascular activity. However, at the present time, neither pharmacological nor metabolic studies have been conducted in order to strengthen the relevance of phenstatine as a drug discovery candidate. In the present work, the metabolic fate of phenstatin in rat and human microsomal preparations was studied to investigate the stability of this tubulin polymerization inhibitor and any effects of the metabolites on polymerization and on PC3 cancer cell proliferation. The metabolites were separated by high-performance liquid chromatography and, after their synthesis, characterized by simultaneous LC-DAD-UV and LC-ESI-MS analyses. Thus, eight metabolites were identified. The major biotransformation pathways are carbonyl reduction, O-methylation at C-3', O-methylation after aromatic hydroxylation at the position C-2' on phenyl B ring and O-demethylation on A ring. Four of the identified metabolites were as active or more active, than phenstatin in vitro. Moreover, the better stability of phenstatin versus CA-4 and the lack of quinone formation could justify the design of new analogues which could include various substituents on phenyl rings or linker group in order to modulate the metabolism of phenstatin toward even more active metabolites and so up-regulate the pharmacological activity.

Potent farnesyltransferase inhibitors with 1,4-diazepane scaffolds as novel destabilizing microtubule agents in hormone-resistant prostate cancer.

A new class of potent farnesyltransferase inhibitors based on a 1,4-diazepane scaffold was synthesized with protein farnesyltransferase inhibition potencies in the low nanomolar range. The compounds block the growth on two hormone-resistant tumor prostatic cell lines (DU145 and PC3). The advanced cellular evaluation of the more potent farnesyltransferase inhibitors was explored and revealed a disorganization of tubulin in PC3 cells.

Assembly/disassembly of drug conjugates using imide ligation.

A strategy is described that allows the easy assembly and controlled disassembly of drug conjugates. Imide ligation, that is, the reaction of a peptide thioacid with an azidoformate, is used for conjugate assembly. The imide bond participates also with an endopeptidase-triggered cyclization-based disassembly mechanism.

Synthesis and biological activity of N-aroyl-tetrahydro-gamma-carbolines.

Research on dual inhibitors of both 5-LOX and COXs gained interest due to the overexpressions of these enzymes during the malignant state of the evolution of prostate cancer. In order to take part in this research, new N-aroyl-tetrahydro-gamma-carbolines issued from the modification of Indomethacin have been synthesised. As for the NSAIDs, the compounds have been tested for their activity against COX(1), COX(2) plus against 5-LOX and against the proliferation of malignant prostate cancer. Interesting cytotoxic activities and selectivities of some tetrahydro-gamma-carboline derivatives have been obtained.

New NSAIDs-NO hybrid molecules with antiproliferative properties on human prostatic cancer cell lines.

The design of profen hybrids containing a NO donor moiety connected to an aliphatic spacer led to compounds with a similar cyclooxygenase inhibition compared to their parent profen and with significant antiproliferative activities on PC3 cells. However, inhibition of COX-2 pathway alone did not seem sufficient to inhibit cancer cell proliferation, and NO-release in a time-dependent manner strongly contributes to this activity.

Synthesis and biological activities of a series of 4,5-diaryl-3-hydroxy-2(5H)-furanones.

A series of thirteen 4,5-diaryl-3-hydroxy-2(5H)-furanones were synthesized. They were evaluated for their antioxidant potencies and inhibitory properties of 5-lipoxygenase, cyclooxygenases, HIV-1 integrase and PC3 cell proliferation. New hits were discovered either in the anti-proliferation test or in the HIV anti-integrase test.

Design, synthesis and biological evaluation of substituted dioxodibenzothiazepines and dibenzocycloheptanes as farnesyltransferase inhibitors.

A new series of FTase inhibitors containing a tricyclic moiety--dioxodibenzothiazepine or dibenzocycloheptane--has been designed and synthesized. Among them, dioxodibenzothiazepine 18d displayed significant inhibitory FTase activity (IC(50)=17.3 nM) and antiproliferative properties.

COX-2/5-LOX dual acting anti-inflammatory drugs in cancer chemotherapy.

Emerging reports now indicate alterations of arachidonic acid metabolism with carcinogenesis and many COX and LOX inhibitors (used for the treatment of inflammatory diseases) are being investigated as potential anticancer drugs. Results from clinical trials seem to be encouraging but a better knowledge of the dynamic balance that shifts toward lipoxygenases (and different isoforms of LOXs) and cyclooxygenase-2 are essential to progress in the design of new drugs more specially directed on chemoprevention or chemotherapy of human cancers. So, on the basis of these results, it seemed useful to study the advantages of combination of COX inhibitor with LOX inhibitor and a next step will be the conception of dual inhibitors able to induce the anticarcinogenic and/or to inhibit the procarcinogenic enzymes responsible for polyunsaturated fatty acid metabolism. After a rapid summary of some recent reviews published on the involvement of different COX and LOX isoforms present in human cells, we will discuss on cross-talk reported between the downstream pathways which contribute to the development and progression of human cancers. This will lead us to evoke and to justify alternative strategies to develop agents that modulate multiple targets simultaneously with the aim of enhancing efficacy or improving safety relative to drugs that address only a single enzyme.

Derivatives of Iressa, a specific epidermal growth factor receptor inhibitor, are powerful apoptosis inducers in PC3 prostatic cancer cells.

The tyrosine kinase activity of the epidermal growth factor receptor (EGFR) is widely involved in signaling pathways and often deregulated in cancer. Its role in the development of prostate cancer is well established, and therapeutic strategies such as blockade of the intracellular tyrosine kinase domain with small-molecule tyrosine kinase inhibitors have been proposed. Herein we describe the synthesis and in vitro pharmacological properties of C6- and C7-substituted 4-anilinoquinazolines, analogues of Iressa and powerful proapoptotic inducers in hormone-independent prostate cancer PC3 cell lines.

Mechanisms leading to COX-2 expression and COX-2 induced tumorigenesis: topical therapeutic strategies targeting COX-2 expression and activity.

The biological role of COX-2, the inducible form of cyclooxygenase, is to convert arachidonic acid into prostaglandins (PGs) and thromboxanes (TXs). Overexpressed in many tumors, COX-2 plays a crucial role in cancer through synthesis of PGs which stimulate PGs receptors with subsequent enhancement of cellular proliferation, promotion of angiogenesis, inhibition of apoptosis, stimulation of invasion/motility, and suppression of immune responses. Depending on the tissue specificity and the cell type, several signaling pathways (Kinases, Rho, cGMP and Wnt), and transcription factors such as AP1, NFAT or NF-kappaB, are involved in COX-2 expression. In this review, we will describe mechanisms required by COX-2 metabolites to promote cancer development, and also the signaling pathways leading to COX-2 expression. In order to counteract the negative effects of COX-2 in cancerogenesis, chemicals interfering with COX-2 activity and expression were designed. We will give in the last part of this article, an overview of these potent chemicals interfering with the COX-2 signaling pathways involved in its expression or with its activity.

Involvement of PI3K/Akt pathway in prostate cancer--potential strategies for developing targeted therapies.

This review presents some therapeutic interventions actually considered in prostate cancer therapy to compensate constitutive activation of the PI3K/Akt signalling pathway induced, particularly, by mutations of PTEN gene. Special emphasis is placed on applicability of EGF-R tyrosine kinase, COX-2, PDK-1, mTOR and farnesyltransferase inhibitors.

Novel N-(4-Piperidinyl)benzamide antimalarials with mammalian protein farnesyltransferase inhibitory activity.

Protein farnesyltransferase of Plasmodium falciparum is a potential target in the treatment of malaria for which increased drug resistance is observed. The design, synthesis and evaluation of a series of N-(4-piperidinyl)benzamides is reported. The most potent compounds showed in vitro activity against the parasite at submicromolar concentrations.

New antiproliferative benzoindolinothiazepines derivatives.

New benzoindolinothiazepines containing a piperazine moiety are described as potent antiproliferative agents against PC3 human prostatic cell lines. This activity could be explained by an accumulation of cells in G1 phase.

In vitro and in vivo evaluation of two rational-designed nonpeptidic farnesyltransferase inhibitors on HT29 human colon cancer cell lines.

FTase inhibitors constitute a new class of potential cancer therapeutics, especially in colorectal cancer where K-ras-selective mutations exist and have a role in tumorigenesis. The synthesis and biological evaluation of two nonpeptidic molecules (13 and 16) designed on the basis of a zinc chelator imidazole linked to two aromatic fragments able to fit in the "exit groove" and in the "A2 binding site" of FTase are described. These molecules are characterized respectively by a flexible phenylmethyl chain and a more constrained scaffold so as to evaluate their respective influences on site recognition. They have been evaluated in vitro and in vivo against human colon cancer cell lines and 13 not only inhibited tumor growth but also showed no toxic effects at the dose used.

Potent and selective farnesyl transferase inhibitors.

We recently described a novel series of CA(1)A(2)X peptidomimetics as farnesyl transferase inhibitors (FTIs). These compounds possess an N-(4-piperidinyl)benzamide scaffold mimicking A(1)A(2) residue. Extensive exploration of structure--activity relationships revealed that replacement of cysteine by substituted benzylimidazoles provided nanomolar FTIs with in vitro activities (18e, IC(50) = 4.60 nM on isolated enzyme, EC(50) = 20.0 nM for growth inhibition on a tumor cell line). The molecular docking of 18e and 19e in the active site of the enzyme provided details of key interactions with the protein and showed that the methionine or phenylalanine residue fits into the aryl binding site.

New COX-2/5-LOX inhibitors: apoptosis-inducing agents potentially useful in prostate cancer chemotherapy.

The arachidonic acid metabolizing enzymes cyclooxygenase-2 (COX-2) and lipoxygenases (LOXs) have been found to be implicated in a variety of cancers, including prostate cancer. To develop new therapeutic treatments, it therefore seemed interesting to design dual COX-2/5-LOX inhibitors. We report here the synthesis and in vitro pharmacological properties of diarylpyrazole derivatives that have in their structure key pharmacophoric elements to obtain optimal interaction with subsites of active pockets in both enzyme systems. Using a molecular modeling approach, a set of SAR data is proposed, highlighting the importance of the sulfonyl group of one of the aryl moieties in terms of proliferation inhibition and/or apoptosis induction.

DNA binding to guide the development of tetrahydroindeno[1,2-b]pyrido[4,3,2-de]quinoline derivatives as cytotoxic agents.

The tetrahydroindeno[1,2-b]pyrido[4,3,2-de]quinoline chromophore was initially designed as a DNA intercalating unit because of its planar structure. Unexpectedly, one molecule (15d) bearing two N-methylpiperazine chains on both sides of this condensed pentacyclic skeleton fits into the minor groove of DNA and preferentially recognizes AT-rich sequences. The monosubstituted compound 16d was identified as a potent cytotoxic DNA intercalator, whereas the disubstituted analogue 15d represents a new structural motif for the development of DNA sequence-reading small molecules.

New benzo[5,6]pyrrolizino[1,2-b]quinolines as cytotoxic agents.

An assessment of structure-activity relationships associated with the new benzo[5,6]pyrrolizino[1,2-b]quinoline system displaying potent in vitro cytotoxic activity against the MCF7 cell line is described.

New heteroarylbenzenesulphonamides as matrix metalloproteinase inhibitors.

A series of derivatives of 2,4- and 2,5-thiazolyl- or oxazolylbenzenesulphonamides has been prepared and evaluated as potential MMP inhibitors. The thiazole 15b have been found to exhibit MMP-2 and MMP-9 inhibitions higher than reference compounds GI 129471 and CGS 27023A.