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Inhibition of tumorigenesis by a cytosine-DNA, methyltransferase, antisense oligodeoxynucleotide
S Ramchandani1, A R MacLeod, M Pinard
1Department of Pharmacology and Therapeutics, McGill University, Montreal, PQ, Canada.
Abstract:
This paper tests the hypothesis that cytosine DNA methyltransferase (DNA MeTase) is a candidate target for anticancer therapy. Several observations have suggested recently that hyperactivation of DNA MeTase plays a critical role in initiation and progression of cancer and that its up-regulation is a component of the Ras oncogenic signaling pathway. We show that a phosphorothioate-modified, antisense oligodeoxynucleotide directed against the DNA MeTase mRNA reduces the level of DNA MeTase mRNA, inhibits DNA MeTase activity, and inhibits anchorage independent growth of Y1 adrenocortical carcinoma cells ex vivo in a dose-dependent manner. Injection of DNA MeTase antisense oligodeoxynucleotides i.p. inhibits the growth of Y1 tumors in syngeneic LAF1 mice, reduces the level of DNA MeTase, and induces demethylation of the adrenocortical-specific gene C21 and its expression in tumors in vivo. These results support the hypothesis that an increase in DNA MeTase activity is critical for tumorigenesis and is reversible by pharmacological inhibition of DNA MeTase.
Insights
Antisense oligodeoxynucleotides targeting cytosine DNA methyltransferase (DNA MeTase) inhibit cancer cell growth. Pharmacological inhibition of DNA MeTase shows promise for reversing tumor progression and gene silencing in cancer therapy.
Area of Science:
- Oncology
- Molecular Biology
- Epigenetics
Background:
- Hyperactivation of DNA methyltransferase (DNA MeTase) is implicated in cancer initiation and progression.
- Up-regulation of DNA MeTase is linked to the Ras oncogenic signaling pathway.
- DNA MeTase is a potential therapeutic target for anticancer strategies.
Purpose of the Study:
- To test the hypothesis that DNA MeTase is a viable target for anticancer therapy.
- To investigate the effects of inhibiting DNA MeTase on cancer cell growth and tumor development.
Main Methods:
- Utilized phosphorothioate-modified, antisense oligodeoxynucleotides against DNA MeTase mRNA.
- Assessed DNA MeTase mRNA levels, enzyme activity, and anchorage-independent growth of Y1 adrenocortical carcinoma cells ex vivo.
- Administered DNA MeTase antisense oligodeoxynucleotides intraperitoneally to mice bearing Y1 tumors in vivo.
Main Results:
- Antisense oligodeoxynucleotides reduced DNA MeTase mRNA levels and inhibited enzyme activity.
- Inhibition of DNA MeTase reduced anchorage-independent growth of Y1 cells ex vivo.
- In vivo treatment reduced Y1 tumor growth, decreased DNA MeTase levels, and induced demethylation and expression of the C21 gene in tumors.
Conclusions:
- Increased DNA MeTase activity is critical for tumorigenesis.
- Pharmacological inhibition of DNA MeTase can reverse tumor progression and epigenetic alterations.
- Targeting DNA MeTase with antisense oligodeoxynucleotides represents a promising anticancer therapeutic approach.