Inhibition of aromatase expression by a psoralen‐linked triplex‐forming oligonucleotide targeted to a coding sequence

Macaulay, Val; Bates, Paula J.; McLean, Michael J.; Rowlands, Martin; Jenkins, Terence C.; Ashworth, Alan; Neidle, Stephen

doi:10.1016/0014-5793(95)00987-k

Cited by 21 publications

(12 citation statements)

References 24 publications

(36 reference statements)

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“…The amount of triplex-mediated cross-links was a function of the UVA dose (Fig 2B), and increasing amounts of cross-links have been observed with increasing UVA dosages in previous studies (Macaulay et al, 1995;Besch et al, 2002). The observed UVA-associated inhibition of CAT expression was not due to psoralen/UVA-associated cellular phototoxic effects (Lü ftl et al, 1998;Hö nigsmann et al, 2003), because UVA irradiation was performed prior to transfection into cells.…”

Section: Figurementioning

confidence: 58%

“…Hence, triple helix technology may be used to modify PUVA therapy so as to inhibit specifically genes of interest in addition to antiproliferative PUVA effects. The inhibitory activity of psoralen-conjugated TFO has been observed with other plasmid-based systems both with regard to inhibition of transcription elongation (Degols et al, 1994;Macaulay et al, 1995;Musso et al, 1996;Intody et al, 2000) and transcription initiation (Grigoriev et al, 1993).…”

Section: Figurementioning

confidence: 91%

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Triple Helix-Mediated Inhibition of Gene Expression Is Increased by PUVA

Besch

Marschall

Schuh

et al. 2004

Journal of Investigative Dermatology

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The combination of psoralens with UVA is used as PUVA therapy for psoriasis and other skin diseases. UVA-induced psoralen/DNA photoadducts act via suppression of DNA replication and cell proliferation, but do not sufficiently repress gene transcription. To explore whether PUVA may also be used for gene repression, psoralen was conjugated to a triplex-forming oligonucleotide (TFO) that targets a gene sequence of ICAM-1, a key molecule in cutaneous inflammation. Triplex formation between TFO and target sequence was detected by non-denaturing gel electrophoresis. UVA-irradiation induced psoralen cross-links at the triplex-duplex junction as verified by denaturing gel electrophoresis. When the target sequence was placed within the transcribed portion of the chloramphenicol acetyltransferase (CAT) gene, TFO inhibited CAT expression in A431 cells. Inhibition was sequence-specific, since a scrambled control oligonucleotide or mismatched or scrambled target sequences failed to inhibit CAT expression. Inhibition was not significant without UVA exposure, but was strongly enhanced by PUVA-mediated cross-links at the TFO target site. These results suggest that TFO may add a new quality to PUVA therapy by transcriptionally repressing pathogenically relevant genes, in addition to antiproliferative PUVA effects. TFO designed to repress only after PUVA activation may allow the development of a cutaneous organ specific strategy for gene repression.

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Section: Figurementioning

confidence: 58%

Section: Figurementioning

confidence: 91%

Triple Helix-Mediated Inhibition of Gene Expression Is Increased by PUVA

Besch

Marschall

Schuh

et al. 2004

Journal of Investigative Dermatology

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“…Previous reports (29,30,32,47,48) indicate that free psoralen preferentially cross-links 5′-TpA and 5′-ApT sites, with 5′-TpA sites favored by at least 10-fold. Most studies using psoralen-conjugated TFOs have targeted 5′-TpA sites located at the duplex-triplex junction or immediately adjacent to it and have demonstrated cross-linking efficiencies approaching 100% (50,(53)(54)(55), but more typically in the range of 25-80% (46,(56)(57)(58)(59). In this study, two 5′-ApT sites at the junction were cross-linked with efficiencies of 56 and 65% (Figure 3).…”

Section: Discussionmentioning

confidence: 82%

Psoralen Photo-Cross-Linking by Triplex-Forming Oligonucleotides at Multiple Sites in the Human Rhodopsin Gene

1999

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Targeting DNA damage by triplex-forming oligonucleotides (TFOs) represents a way of modifying gene expression and structure and a possible approach to gene therapy. We have determined that this approach can deliver damage with great specificity to sites in the human gene for the G-protein-linked receptor rhodopsin, mutations of which can lead to the genetic disorder autosomal dominant retinitis pigmentosa. We have introduced DNA monoadducts and interstrand cross-links at multiple target sites within the gene using TFOs with a photoactivatable psoralen group at the 5'-end. The extent of formation of photoadducts (i.e., monoadducts and cross-links) was measured at target sites with a 5'-ApT sequence at the triplex-duplex junction and at a target site with 5'-ApT and 5'-TpA sequences located four and seven nucleotides away, respectively. To improve psoralen reactivity at more distant sites, psoralen moieties were attached to TFOs with nucleotide "linkers" from two to nine nucleotides in length. High-affinity binding was maintained with linkers of up to 10 nucleotides, but affinities tended to decrease somewhat with increasing linker length due to faster dissociation kinetics. DNase I footprinting indicated little, if any, interaction between linkers and the duplex. Psoralen-TFO conjugates formed DNA cross-links with high efficiency (56-65%) at 5'-ApT sequences located at triplex junctions. At a 5'-ApT site four nucleotides away, the efficiency varied with linker length; a four-nucleotide linker gave the highest efficiency. Duplexes with 5'-TpA and 5'-ApT sites two nucleotides away, in otherwise identical sequences, were cross-linked with efficiencies of 56 and 38%, respectively. These results indicate that TFO-linker-psoralen conjugates allow simultaneous, efficient targeting of multiple sites in the human rhodopsin gene.

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“…17b-estradiol is synthesized in ovarian granulosa cells by aromatase, CYP19 [44]. Macaulay et al [45] observed inhibition of aromatase expression in human breast cancer cells by a psoralenlinked oligonucleotide. It is thus tempting to speculate that the reduced circulating 17b-estradiol level may also be related to a direct e¡ect of the psoralens on the activity of this general class of enzymes.…”

Section: Resultsmentioning

confidence: 99%

Reproductive Toxicity of the Psoralens

Diawara

Kulkosky

2003

Pediatric Pathology & Molecular Medicine

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The psoralens are naturally occurring secondary metabolites in plants, including many fruits and vegetables. Health risks have been associated with handling or ingesting psoralen-containing plants, and with the use of synthetic psoralens in photochemotherapy of skin disorders. Our research has demonstrated that administration of the psoralens bergapten (5-methoxypsoralen) and xanthotoxin (8-methoxypsoralen) in the diet of female rats reduced birthrates, number of implantation sites, pups, corpora lutea, full and empty uterine weight, and circulating estrogen levels in a dose-dependent manner. Psoralens induced mRNAs of the liver enzymes CYP1A1 and UGT1A6, suggesting that enhanced metabolism of estrogens by psoralen treatment may explain the reproductive toxicity and the observed reduction of ovarian follicular function and ovulation. Rats also avoided repeated consumption of a flavored solution associated with psoralen administration. The findings indicate that the psoralens constitute a novel group of ovarian toxicants. Further examination of the safety of their use in photochemotherapy and diet is warranted.

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Inhibition of aromatase expression by a psoralen‐linked triplex‐forming oligonucleotide targeted to a coding sequence

Cited by 21 publications

References 24 publications

Triple Helix-Mediated Inhibition of Gene Expression Is Increased by PUVA

Triple Helix-Mediated Inhibition of Gene Expression Is Increased by PUVA

Psoralen Photo-Cross-Linking by Triplex-Forming Oligonucleotides at Multiple Sites in the Human Rhodopsin Gene

Reproductive Toxicity of the Psoralens

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