A novel cinnamic acid derivative that inhibits Cdc25 dual-specificity phosphatase activity

Chemical and molecular bases of dome formation in human colorectal cancer cells mediated by sulphur compounds from Cucumis melo var. conomon

Colorectal cancer was the third most commonly diagnosed malignant tumor and the fourth leading cause of cancer deaths worldwide in 2012. A human colorectal cancer cell line, RCM‐1, was established from a colon cancer tissue diagnosed as a well‐differentiated rectum adenocarcinoma. RCM‐1 cells spontaneously form ‘domes’ (formerly designated ‘ducts’) resembling villiform structures. Two sulphur‐containing compounds from Cucumis melo var. conomon (Katsura‐uri, or Japanese pickling melon), referred to as 3‐methylthiopropionic acid ethyl ester (MTPE) and methylthioacetic acid ethyl ester (MTAE), can induce the differentiation of the unorganized cell mass of an RCM‐1 human colorectal cancer cell culture into a dome. However, the underlying molecular mechanisms of such dome formation have not been previously reported. Here, we performed a structure–activity relationship analysis, which indicated that methylthioacetic acid (MTA) was the lowest molecular weight compound with the most potent dome‐inducing activity among 37 MTPE and MTAE analogues, and the methylthio group was essential for this activity. According to our microarray analysis, MTA resulted in down‐regulation of 537 genes and up‐regulation of 117 genes. Furthermore, MTA caused down‐regulation of many genes involved in cell‐cycle control, with the cyclin E2 (CCNE2) and cell division cycle 25A (CDC25A) genes being the most significantly reduced. Pharmacological analysis showed that the administration of two cell‐cycle inhibitors for inactivating CDC25A phosphatase (NSC95397) and the cyclin E2/cyclin‐dependent kinase 2 complex (purvalanol A) increased the dome number independently of MTA. Altogether, our results indicate that MTA is the minimum unit required to induce dome formation, with the down‐regulation of CDC25A and possibly CCNE2 being important steps in this process.

Inhibitors of Cdc25 phosphatases as anticancer agents: a patent review

IMPORTANCE OF THE FIELD

The cell division cycle 25 (Cdc25) family of proteins are highly conserved dual specificity phosphatases that regulate cyclin-dependent kinases, the main gatekeepers of the eukaryotic cell division cycle. The three isoforms of Cdc25, including Cdc25A, Cdc25B and Cdc25C, appear to act on different cyclin-dependent kinase/cyclin complexes at different stages of the cell cycle. Overexpression of Cdc25A and/or Cdc25B, but not Cdc25C, has been detected in numerous cancers and is often correlated with a poor clinical prognosis. Thus, inhibition of these phosphatases may represent a promising therapeutic approach in oncology.

AREAS COVERED IN THIS REVIEW

The main focus of the present review is to describe the development of Cdc25 inhibitors over the years. We describe different compounds according to the decade of discovery and focus attention on molecules that were published in patents.

WHAT THE READER WILL GAIN

Insight into the most clinically relevant therapeutic Cdc25 analogues that have been published in over 40 patents over the past 19 years.

TAKE HOME MESSAGE

Some Cdc25 inhibitors have suppressed in vivo the growth of human tumor xenografts in animals; this confirmed the validity of using Cdc25 phosphatase inhibition as an anticancer strategy, but side effects and toxicity remain to be investigated.

Is Cdc25 a druggable target?

Proper control of cell cycle progression requires the functionality of a small family of activating phosphatases termed Cdc25, which have been implicated in cancer and Alzheimer's disease. These protein tyrosine phosphatases are therefore recognized as attractive molecular targets for small molecules. We review the rationale, approaches, progress and challenges for developing small molecule inhibitors of the Cdc25 family. A number of potential chemical probes are discussed and their characteristics are summarized.

Gene-expression profiling in epithelial ovarian cancer

DNA-microarray technology has made it possible to simultaneously analyze the expression of thousands of genes in a small sample of tumor tissue. In epithelial ovarian cancer, gene-expression profiling has been used to provide prognostic information, to predict response to first-line platinum-based chemotherapy, and to discriminate between different histologic subtypes. Furthermore, DNA-microarray technology might permit identification of novel markers for early detection of disease and provide insights into the mechanisms of cancer growth and chemotherapy resistance. In this Review, we summarize the contributions of gene-expression profiling to the diagnosis and management of epithelial ovarian cancer and discuss ways in which this technique could become a useful tool in clinical management.

What's new on CDC25 phosphatase inhibitors

The CDC25 phosphatases are key regulators of cell cycle progression and play a central role in the checkpoint response to DNA damage. Their inhibition may therefore represent a promising therapeutic approach in oncology, and small molecule design strategies are currently leading to the identification of various classes of CDC25 inhibitors. Most structures developed so far are quinonoid-based compounds, but also phosphate surrogates or electrophilic entities. Considering the characteristics of the highly conserved active sites of the enzymes, many mechanisms of action have been proposed for these inhibitors. Quinonoid compounds may oxidize the catalytic site cysteine, but can also be considered as Michaël acceptors capable of reacting with the activated thiolate or other electrophilic entities. Phosphate surrogates are thought to interfere with the arginine residue, leading to reversible enzyme inhibition. But some inhibitors can combine in the same molecule several of these mechanisms, thus by fitting into the active site of the enzyme through one part of the molecule and bringing the reactive moiety in close proximity to the catalytic cysteine. This review summarizes novel classes of inhibitors that show specificity for the CDC25s over other phosphatases, cause cell proliferation inhibition and cell cycle arrest in vitro but also, for several of them, inhibition of xenografted tumoral cell growth in vivo. These promising results confirm the interest of the inhibition of CDC25 phosphatases as an anticancer therapeutic strategy.

Synthesis and biological evaluation of dialkylsubstituted maleic anhydrides as novel inhibitors of Cdc25 dual specificity phosphatases

An efficient synthesis of dialkylsubstituted maleic anhydrides 1a-j is described. The inhibitory potential of these original anhydride derivatives was tested toward the three human isoforms A, B and C of dual specific phosphatases Cdc25. A micromolar range inhibition of Cdc25s was observed with the maleic anhydrides bearing simple alkyl side chains longer than C(9), to reach the optimal activity with a C(17) chain length.

High-performance liquid chromatography-diode array detection/electrospray ionization mass spectrometry for the simultaneous analysis of cis-, trans- and dihydro-2-glucosyloxycinnamic acid derivatives from Dendrobium medicinal plants

Sensitive, selective and reliable high-performance liquid chromatography (HPLC)-diode array detection (DAD)/electrospray ionization multi-stage mass spectrometry (ESI-MSn) methods have been developed for the characterization of nine 2-glucosyloxycinnamic acid derivatives and quantitative analysis of three of the major 2-glucosyloxycinnamic acids, cis-melilotoside, trans-melilotoside and dihydromelilotoside, present in Dendrobium medicinal plants. The identities of the latter three major 2-glucosyloxycinnamic acids were confirmed by comparing their retention times, UV and mass spectra with those of the reference standards. The characteristic ESI-MSn fragmentation patterns of the remaining six 2-glucosyloxycinnamic acid derivatives, which are similar to the three major compounds, have allowed the putative elucidation of their structures. The concentrations of the cis-, trans- and dihydromelilotosides were simultaneously determined by HPLC/ESI-MS2 using the multiple reaction monitoring (MRM) mode in extracts of Dendrobium species. The method was validated with respect to the overall intra- and inter-day variation (RSD less than 8%) and the limits of quantification for the cis-, trans- and dihydromelilotosides were 0.09, 0.09 and 0.01 microg/mL, respectively.

Low dietary folate initiates intestinal tumors in mice, with altered expression of G2-M checkpoint regulators polo-like kinase 1 and cell division cycle 25c

Clinical reports have suggested that low dietary folate increases risk for colorectal cancer. Animal studies for investigation of folate and tumorigenesis have used carcinogen induction or mice with germ-line mutations. We have developed a new spontaneous tumor model in which mice, with or without a null allele in a key folate-metabolizing enzyme, methylenetetrahydrofolate reductase (Mthfr), develop intestinal tumors due to low dietary folate alone. On folate-deficient diets, 12.5% of Mthfr(+/+) mice and 28.1% of Mthfr(+/-) mice developed tumors; mice on control diets were negative. Dietary and genotype effects on tumor development were significant. To investigate mechanisms of folate-dependent tumorigenesis, we examined levels of DNA damage and gene expression of two genes involved in DNA damage response and G(2)-M checkpoint regulation, polo-like kinase 1 (Plk1) and cell division cycle 25c (Cdc25c). Folate deficiency increased DNA damage and decreased expression of both genes (assessed by quantitative reverse transcription-PCR and immunofluorescence) in normal intestine compared with levels in mice on control diets. An immunofluorescence assay for CDC25c activity (phosphorylated CDC2) also found CDC25c activity to be decreased in folate-deficient normal intestine. In tumors, however, Plk1 and Cdc25c mRNA were found to be higher (11- and 3-fold, respectively) compared with normal intestine from folate-deficient mice; immunofluorescence studies of PLK1, CDC25c, and phosphorylated CDC2 supported these findings. Our data suggest that folate deficiency can initiate tumor development, that Mthfr mutation can enhance this phenomenon, and that altered expression of Plk1 and Cdc25c may contribute to folate-dependent intestinal tumorigenesis.