On the origins of the DNA sequence selectivity of mitomycin monoalkylation transformations

Kohn, Harold; Li, Ven Shun; Schiltz, Pascal; Tang, Moon Shong

doi:10.1021/ja00049a082

Cited by 49 publications

(17 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have attributed the observed low yield of 23 to the competitive hydrolytic cleavage of the oxy(thiocarbonyl)imidazole moiety in 8 rather than to the instability of the product 23 under the study conditions. This assumption is based, in part, upon the identification of 10 and 12 as major byproducts in the reaction and upon our observation that N-methyl ethylthiocarbamate (24) did not undergo hydrolysis in D 2 O solutions maintained at 22 °C for 4 days (NMR analysis, data not shown). 3 The low phosphorothioate oligodeoxynucleotide coupling yields observed for N-[10-decarbamoyl-10-O-thiocarbonyl-[N(1a)-(methylthio)carbonyl]mitomycin]imidazole (8) and our inability to satisfactorily purify the DNA conjugates led us to use 10-des(carbamoyloxy)-10isothiocyanatoporfiromycin (9) in place of 8.…”

Section: Conjugation Of the N-[10-decarbamoyl-10-o-thiocarbonyl-[n(1a...mentioning

confidence: 99%

“…These criteria led us, in part, to select 5-9 as substrates for DNA attachment. The porfiromycin substrates 5, 6, and 9 were designed to target mRNA sequences that contained 5′CG* sites at the 5′ termini (21)(22)(23), whereas 7 and 8 were projected to react preferentially with mRNAs having an appropriately disposed 5′AG* or 5′TG* site (24).…”

Section: Conjugation Of the N-[10-decarbamoyl-10-o-thiocarbonyl-[n(1a...mentioning

confidence: 99%

“…This base sequence has low C content and has a CG*G sequence at the 3′ end. We anticipated that the 9-DNA conjugate would modify this sequence since porfiromycin (2) has been shown to preferentially alkylate this trinucleotide sequence upon in vitro reductive activation (24). Furthermore, we expected that the antisense strand would not readily undergo complementary self-base pairing due to the low G content.…”

Section: Conjugation Of the N-[10-decarbamoyl-10-o-thiocarbonyl-[n(1a...mentioning

confidence: 99%

“…Alkylation occurs exclusively at guanine 2-amino residues located within the DNA minor groove (20). In vitro reductive activation of mitomycin C (1) and porfiromycin (2) leads to preferential alkylation of 5′CG* (G* ) alkylation site) 1 sites (21)(22)(23), while N(1a)-[(methylthio)carbonyl]mitomycin C (3) selectively modifies 5′AG* and 5′TG* loci (24).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Design, Synthesis, and Evaluation of Mitomycin-Tethered Phosphorothioate Oligodeoxynucleotides

et al. 1996

Self Cite

View full text Add to dashboard Cite

Mitomycin C (1) is the prototypical bioreductive alkylating agent. Studies have shown that mitomycin C and its derivatives selectively alkylate guanine residues within di- and trinucleotide DNA sequences. This investigation sought to improve the selective DNA bonding properties of the mitomycins by coupling them with antisense oligodeoxynucleotides. Two procedures were developed that allowed the attachment of a phosphorothioate oligodeoxynucleotide containing a hexylamino spacer at the 5' terminus with a C(10)-activated mitomycin. In the first procedure, decarbamoylation of 1 (NaOCH3/ benzene) afforded 10-decarbamoylmitomycin C (10), which was treated with either dimethyl sulfate or methylthiochloroformate and base to yield 10-decarbamoylporfiromycin (11) and N(1a)-[(methylthio)-carbonyl]-10-decarbamoylmitomycin C (12), respectively. Activation of the C(10) site in 11 and 12 with 1,1'-carbonyldiimidazole or with 1,1'-thiocarbonyldiimidazole provided the N(1a)-substituted mitomycin 10-decarbamoyl-10-O-carbonylimidazoles (5, 7) and 10-decarbamoyl-10-O-thiocarbonylimidazoles (6, 8), respectively. Compounds 5-8 were reacted with glycine methyl ester hydrochloride (17) and base in both methylene chloride and aqueous buffered solutions to determine the ease and efficiency in which these C(10)-activated mitomycin derivatives coupled to amines. It was found that 5-8 all reacted with 17 in methylene chloride to give the coupled products 18-21 but that improved amine coupling yields in water were observed for the 10-decarbamoyl-10-O-thiocarbonylimidazoles 6 and 8 as compared with the 10-decarbamoyl-10-O-carbonylimidazoles 5 and 7. This finding led to the coupling of the phosphorothioate oligodeoxynucleotide, H2N(CH2)6-P(S)(OH)-GGCCCCGTG-GTGGCTCCAT (22) to 8. Compound 22 complemented a 19-base sequence in the translation initiation region of the human A-raf-1 gene. Use of excess 8 (28 equiv) with 22 gave only a 36% yield of the coupled product 23, which proved difficult to separate from 22. In the second procedure, phosphorothioate oligodexynucleotides that contained a hexylamino spacer at the 5'termini were coupled to 10-des(carbamoyloxy)-10-isothiocyanatoporfiromycin (9). Compound 9 was prepared in four steps from 11. Mesylation (methanesulfonyl chloride/pyridine) of 11 gave the C(10) mesylate 13, which was then treated with NaN3 (dimethylformamide, 90 degrees C) to give 10-des(carbamoyloxy)-10-azidoporfiromycin (14). Catalytic reduction (PtO2, H2) of 14 in pyridine afforded C(10) amine 15. Treatment of 15 with di-2-pyridyl thionocarbonate provided the desired 10-des(carbamoyloxy)-10-isothiocyanatoporfiromycin (9). Compound 9 readily coupled with 17 and base in both methylene chloride and aqueous buffered solutions to give 25. Use of the 5'hexylaminophosphorothioate oligodeoxynucleotides 32-35 in place of 17 gave the conjugated adducts 28-31, respectively, in a 12% to near-quantitative yield. The products were purified by semipreparative HPLC. Antisense agents 28-31 were designed to target a 30-base-long region from the c...

show abstract

Section: Conjugation Of the N-[10-decarbamoyl-10-o-thiocarbonyl-[n(1a...mentioning

confidence: 99%

Section: Conjugation Of the N-[10-decarbamoyl-10-o-thiocarbonyl-[n(1a...mentioning

confidence: 99%

Section: Conjugation Of the N-[10-decarbamoyl-10-o-thiocarbonyl-[n(1a...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Design, Synthesis, and Evaluation of Mitomycin-Tethered Phosphorothioate Oligodeoxynucleotides

et al. 1996

Self Cite

View full text Add to dashboard Cite

show abstract

“…Alkylation and crosslinking are sequence-specific. Monoalkylation shows selectivity for guanine in the sequence 5'-CpG-3' (CpG) [33][34][35], while crosslinking is completely specific for CpG · GpC duplex sequences [36][37][38]. It has also been demonstrated that the efficiency and guanine selectivity of alkylation and crosslinking by mitomycin C is enhanced when the target guanines are base-paired with 5-methylcytosine [39][40][41][42].…”

Section: Mode Of Actionmentioning

confidence: 99%