Synthesis and intramolecular hydrogen bonding and biochemical studies of clitocine, a naturally occurring exocyclic amino nucleoside

Rj, Moss; Cr, Petrie; Rb, Meyer; Ld, Nord; Rc, Willis; Smith, R. A.; Sb, Larson; Gd, Kini; Rk, Robins

doi:10.1021/jm00399a017

Cited by 45 publications

(20 citation statements)

References 8 publications

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“…Clitocine, (2R,3R,4S,5R)-2-([6-amino-5-nitropyrimidin-4-yl]amino)-5-(hydroxymethyl) tetrahydrofuran-3,4-diol, (Fig. 1B) was synthesized according to a published procedure (Moss et al 1988) in which 4,6-diamino-5-nitropyrimidine was coupled with 1-oacetyl-2,3,5tri-O-benzoyl-D-ribofuranose following the procedure of Vorbrueggen (Niedballa and Vorbruggen 1974). Removal of the benzoyl protecting groups resulted in the nucleoside clitocine in a 92:8 ratio of β/α anomers.…”

Section: Organic Synthesismentioning

confidence: 99%

The nucleoside analog clitocine is a potent and efficacious readthrough agent

Friesen

Trotta

Tomizawa

et al. 2017

RNA

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Nonsense mutations resulting in a premature stop codon in an open reading frame occur in critical tumor suppressor genes in a large number of the most common forms of cancers and are known to cause or contribute to the progression of disease. Low molecular weight compounds that induce readthrough of nonsense mutations offer a new means of treating patients with genetic disorders or cancers resulting from nonsense mutations. We have identified the nucleoside analog clitocine as a potent and efficacious suppressor of nonsense mutations. We determined that incorporation of clitocine into RNA during transcription is a prerequisite for its readthrough activity; the presence of clitocine in the third position of a premature stop codon directly induces readthrough. We demonstrate that clitocine can induce the production of p53 protein in cells harboring p53 nonsense-mutated alleles. In these cells, clitocine restored production of full-length and functional p53 as evidenced by induced transcriptional activation of downstream p53 target genes, progression of cells into apoptosis, and impeded growth of nonsense-containing human ovarian cancer tumors in xenograft tumor models. Thus, clitocine induces readthrough of nonsense mutations by a previously undescribed mechanism and represents a novel therapeutic modality to treat cancers and genetic diseases caused by nonsense mutations.

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Section: Organic Synthesismentioning

confidence: 99%

The nucleoside analog clitocine is a potent and efficacious readthrough agent

Friesen

Trotta

Tomizawa

et al. 2017

RNA

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“…Some agents extracted from fruits, vegetables, oilseeds, and plant herbs were able to modulate the activity of P-gp [22], [23], [24]. Clitocine, a nucleoside firstly isolated from the mushroom Clitocybe inversa in 1980s, was found to be a substrate and inhibitor of adenosine kinase [25]. Recent years, clitocine was reported to exert an anti-tumor effect in varies cancer cell lines such as Hela and MCF-7 cells, and many derivatives of this compound were also synthesized and examined for their biological properties [25], [26], [27], [28].…”

Section: Introductionmentioning

confidence: 99%

“…Clitocine, a nucleoside firstly isolated from the mushroom Clitocybe inversa in 1980s, was found to be a substrate and inhibitor of adenosine kinase [25]. Recent years, clitocine was reported to exert an anti-tumor effect in varies cancer cell lines such as Hela and MCF-7 cells, and many derivatives of this compound were also synthesized and examined for their biological properties [25], [26], [27], [28]. In the present study, we found that clitocine reverse the P-gp associated multidrug resistance in cancer cells.…”

Section: Introductionmentioning

confidence: 99%

Clitocine Reversal of P-Glycoprotein Associated Multi-Drug Resistance through Down-Regulation of Transcription Factor NF-κB in R-HepG2 Cell Line

Sun

Yeung

et al. 2012

PLoS ONE

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Multidrug resistance(MDR)is one of the major reasons for failure in cancer chemotherapy and its suppression may increase the efficacy of therapy. The human multidrug resistance 1 (MDR1) gene encodes the plasma membrane P-glycoprotein (P-gp) that pumps various anti-cancer agents out of the cancer cell. R-HepG2 and MES-SA/Dx5 cells are doxorubicin induced P-gp over-expressed MDR sublines of human hepatocellular carcinoma HepG2 cells and human uterine carcinoma MES-SA cells respectively. Herein, we observed that clitocine, a natural compound extracted from Leucopaxillus giganteus, presented similar cytotoxicity in multidrug resistant cell lines compared with their parental cell lines and significantly suppressed the expression of P-gp in R-HepG2 and MES-SA/Dx5 cells. Further study showed that the clitocine increased the sensitivity and intracellular accumulation of doxorubicin in R-HepG2 cells accompanying down-regulated MDR1 mRNA level and promoter activity, indicating the reversal effect of MDR by clitocine. A 5′-serial truncation analysis of the MDR1 promoter defined a region from position −450 to −193 to be critical for clitocine suppression of MDR1. Mutation of a consensus NF-κB binding site in the defined region and overexpression of NF-κB p65 could offset the suppression effect of clitocine on MDR1 promoter. By immunohistochemistry, clitocine was confirmed to suppress the protein levels of both P-gp and NF-κB p65 in R-HepG2 cells and tumors. Clitocine also inhibited the expression of NF-κB p65 in MES-SA/Dx5. More importantly, clitocine could suppress the NF-κB activation even in presence of doxorubicin. Taken together; our results suggested that clitocine could reverse P-gp associated MDR via down-regulation of NF-κB.

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“…Although the glycosidic bond between a sugar and a primary heterocyclic amine is less stable than that of a natural nucleoside in DNA and RNA, a variety of such exo-aminonucleosides from natural or synthetic origins are known. [22,23] If a potential candidate is chemically too unstable to be useful, the corresponding derivative with a carbocyclic sugar replacing the 2'-deoxyribofuranose unit can be considered as a stable alternative. Such nucleosides are easily accessible by synthesis, [24] are structurally isomorphous to natural nucleosides, and are known to base-pair with complementary nucleosides much in the same way as their natural congeners.…”

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confidence: 99%

A Parallel Screen for the Discovery of Novel DNA Base Pairs

2011

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The genetic information in DNA is encoded in the sequence of the four nucleobases, and its readout is based on the highly specific Watson-Crick pairing A-T and G-C. Over the years there has been growing interest in expanding this genetic alphabet by adding novel, orthogonal base pairs. Such additional base pairs could be used in biotechnology to introduce nonnatural amino acids into engineered proteins, [1][2][3] and to create novel tools for identifying aberrant or exogenous, disease-related nucleic acids. [4][5][6][7][8] The degree of freedom in designing novel base pairs, however, is limited by the structural scaffold of the double helix. The most logical approach is based on structurally isomorphic bases with an alternative Watson-Crick-like hydrogen-bonding network. [6,9,10] Alternatively, nonisomorphic aromatic heterocycles can serve as base replacements; they recognize each other by means other than classical hydrogen bonding and can be replicated and transcribed with high fidelity and similar kinetic properties. [11][12][13][14][15][16] This latter approach provides access to a larger structural space for potential base replacements. Unfortunately this approach is hampered by a lack of design rules which makes it necessary to screen a large number of potential candidates. From each potential base analogue the corresponding nucleoside must first be synthesized and incorporated into oligonucleotides before its coding properties can be evaluated. This is associated with multistep syntheses for each nucleoside candidate which is a timeconsuming procedure.To address these drawbacks we set out to design an assay for the rapid parallel screening of novel potential base candidates out of a library of heterocyclic amines. In a first step we identified selective, high-affinity binders to natural nucleobases. The assay is based on a dodecamer DNA duplex which carries an abasic site X in the center and a fluorescencequencher pair on one end of the duplex (Scheme 1). X structurally deviates from a natural DNA abasic site by the replacement of O(3') by a CH 2 group which renders it chemically stable towards base-or heat-induced strand cleavage at the 3'-end.[17] These duplexes were then incubated with a library of heterocyclic amines in a parallel fashion. During this treatment the amines become covalently attached to X through the formation of a hemiaminal, resulting in exoamino nucleosides that are structurally similar to the natural nucleosides. The thermal stabilities of these duplexes, which reflect the relative affinity of each amine to its target, were then determined by parallel fluorescence measurements of the melting temperature T m (see the Supporting Information).To validate the assay we searched a library of 34 randomly chosen, commercially available heterocyclic amines (Scheme 2) for individuals that bind selectively with high affinity to each of the four natural nucleobases. Duplexes (0.6 mm) were incubated with a 1000-fold excess of the amines in buffer at pH 8 for two days at 55 8C to form the hemiamin...

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Synthesis and intramolecular hydrogen bonding and biochemical studies of clitocine, a naturally occurring exocyclic amino nucleoside

Cited by 45 publications

References 8 publications

The nucleoside analog clitocine is a potent and efficacious readthrough agent

The nucleoside analog clitocine is a potent and efficacious readthrough agent

Clitocine Reversal of P-Glycoprotein Associated Multi-Drug Resistance through Down-Regulation of Transcription Factor NF-κB in R-HepG2 Cell Line

A Parallel Screen for the Discovery of Novel DNA Base Pairs

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