DNA methylation profiling of well-differentiated thyroid cancer uncovers markers of recurrence free survival.

Thyroid cancer is a heterogeneous disease with several subtypes characterized by cytological, histological and genetic alterations, but the involvement of epigenetics is not well understood. Here, we investigated the role of aberrant DNA methylation in the development of well-differentiated thyroid tumors. We performed genome-wide DNA methylation profiling in the largest well-differentiated thyroid tumor series reported to date, comprising 83 primary tumors as well as 8 samples of adjacent normal tissue. The epigenetic profiles were closely related to not only tumor histology but also the underlying driver mutation; we found that follicular tumors had higher levels of methylation, which seemed to accumulate in a progressive manner along the tumorigenic process from adenomas to carcinomas. Furthermore, tumors harboring a BRAF or RAS mutation had a larger number of hypo- or hypermethylation events, respectively. The aberrant methylation of several candidate genes potentially related to thyroid carcinogenesis was validated in an independent series of 52 samples. Furthermore, through the integration of methylation and transcriptional expression data, we identified genes whose expression is associated with the methylation status of their promoters. Finally, by integrating clinical follow-up information with methylation levels we propose etoposide-induced 2.4 and Wilms tumor 1 as novel prognostic markers related to recurrence-free survival. This comprehensive study provides insights into the role of DNA methylation in well-differentiated thyroid cancer development and identifies novel markers associated with recurrence-free survival.

Applications of 3-aminolactams: design, synthesis, and biological evaluation of a library of potential dimerisation inhibitors of HIV1-protease.

In the context of our studies on the applications of 3-aminolactams as conformationally restricted pseudodipeptides, we report here the synthesis of a library of potential dimerisation inhibitors of HIV1-protease. Two of the pseudopeptides were active on the wild type virus (HIV1) at micromolar levels (EC(50)). Although the peptides showed lower anti-viral activity than previously reported dimerisation inhibitors, our results demonstrate that the piperidone moiety does not prevent cell penetration, and hence that such derivatization is compatible with potential anti-HIV treatment.

DYRK1A, a novel determinant of the methionine-homocysteine cycle in different mouse models overexpressing this Down-syndrome-associated kinase.

BACKGROUND: Hyperhomocysteinemia, characterized by increased plasma homocysteine level, is associated with an increased risk of atherosclerosis. On the contrary, patients with Down syndrome appear to be protected from the development of atherosclerosis. We previously found a deleterious effect of hyperhomocysteinemia on expression of DYRK1A, a Down-syndrome-associated kinase. As increased expression of DYRK1A and low plasma homocysteine level have been associated with Down syndrome, we aimed to analyze the effect of its over-expression on homocysteine metabolism in mice. METHODOLOGY/PRINCIPAL FINDINGS: Effects of DYRK1A over-expression were examined by biochemical analysis of methionine metabolites, real-time quantitative reverse-transcription polymerase chain reaction, and enzyme activities. We found that over-expression of Dyrk1a increased the hepatic NAD(P)H:quinone oxidoreductase and S-adenosylhomocysteine hydrolase activities, concomitant with decreased level of plasma homocysteine in three mice models overexpressing Dyrk1a. Moreover, these effects were abolished by treatment with harmine, the most potent and specific inhibitor of Dyrk1a. The increased NAD(P)H:quinone oxidoreductase and S-adenosylhomocysteine hydrolase activities were also found in lymphoblastoid cell lines from patients with Down syndrome. CONCLUSIONS/SIGNIFICANCE: Our results might give clues to understand the protective effect of Down syndrome against vascular defect through a decrease of homocysteine level by DYRK1A over-expression. They reveal a link between the Dyrk1a signaling pathway and the homocysteine cycle.

Synthesis of novel polycyclic indolyldiamines.

A rapid and stereoselective access to novel polycyclic indolyldiamines is described. The key step involves simple chemoselective transformations of a common bicyclic aminal intermediate, easily available on a large scale from an enantiomerically pure cyano oxazolopiperidine precursor.

Design, synthesis and biological activity of a targeted library of potential tryptase inhibitors.

We have designed, synthesized, and tested two small collections of potential tryptase inhibitors. The first library consists of diversely N-substituted 3-aminopiperidin-2-ones 6, and the second (compounds 7) was prepared by dimerising compounds 6 through the 3-amino function using diverse carbon chains. We have established efficient routes for obtaining 6 both in solution and on solid supports. We have also compared the dimerisation on-resin and in solution. Four of the compounds showed a high degree of tryptase inhibition at 1 microM, but none surpassed the tryptase inhibition activity of BABIM.

Constrained derivatives of stylostatin 1. 1. Synthesis and biological evaluation as potential anticancer agents.

Hydroxyaminolactams have been used as constrained surrogates of the Ser-Leu dipeptide in the synthesis of analogues of the cycloheptapeptide stylostatin 1 (2). The rate of cyclization through formation of the Ile-Pro amide bond allowed us to prove that the valerolactams used induced a turn in the linear precursor. Ring closure at the Pro-Phe amide bond was much quicker and provided access to larger amounts of the target structures, with high purity. The conformation of psi-stylostatin 4 was compared to that of native stylostatin 1 using NMR analysis. The ability of three psi-stylostatins and the native stylostatin 1 to inhibit growth of cancer cell lines was tested. None of the compounds showed activity below 1 microM. A possible relationship between the decrease in activity and the presence of the piperidone Ser-Leu surrogate is considered.

Synthesis of 3-aminolactams as X-Gly constrained pseudodipeptides and conformational study of a Trp-Gly surrogate.

3-Amino-delta-valerolactams trans-11a-c were synthesized through conjugate addition and Curtius rearrangement and converted into Fmoc-[Trp-Gly], Fmoc-[Ile-Gly], and Fmoc-[Phe-Gly] pseudodipeptides. Conformational analyses of tripeptide analogues Ac-[Trp-Gly]-Leu-NH(2) 17a and 17b by NMR experiments and molecular modeling calculations showed that diastereomer 17a adopted a gamma-turn/distorted type II beta-turn structure, whereas diastereomer 17b adopted mainly a gamma-turn structure.

Spirolactams as conformationally restricted pseudopeptides: synthesis and conformational analysis.

The synthesis of 1-(tert-butoxycarbonyl)-7-[1-(tert-butoxycarbonyl)-3-methylbutyl]-6-oxo-1,7-diazaspiro[4.5]decanes (S,S)-1a and (S,R)-1b is described. Derivatives 17a,b and 19a are prepared for use in peptide synthesis as constrained surrogates of the Pro-Leu and Gly-Leu dipeptides. The Ac-[Gly-Leu]-Met-NH(2) derivatives (S,S,S)-2a and (S,R,S)-2b, with the tripeptidic C-terminal region present in tachykinins, are also synthesized. Conformational analyses of these tripetide analogues by NMR experiments and molecular modeling calculations show that both (S,S,S)-2a and (S,R,S)-2b epimers are gamma-turn/distorted type II beta-turn mimetics.

Synthetic Applications of 2-(1,3-Dithian-2-yl)indoles. 7. Synthesis of Aspidospermidine.

A new method of synthesizing the alkaloid aspidospermidine (1), based on building ring E on the pyridocarbazole [ABCD] ring structure, is reported. The preparation of the pyridocarbazole framework of Aspidosperma alkaloids is a new three-step synthetic application of 2-(1,3-dithian-2-yl)indoles. A tandem conjugate addition-alkylation reaction starting from indolyldithiane (4), 3-methylenelactam 6, and EtI yields the adduct 17. Treatment of lactam 17 with DIBALH leads to formation of the naphthyridoindole 18. Compound 18 isomerizes in aqueous AcOH to yield pyridocarbazole 3. Finally, closure of ring E and subsequent reduction of the dithiane ring produces aspidospermidine. Pyridocarbazoles 2 and 10 were prepared as models.