Differential requirement for DNA methyltransferase 1 in maintaining human cancer cell gene promoter hypermethylation

Angela H. Ting, Kam Wing Jair, Kornel E. Schuebel, Stephen B. Baylin

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


Previous work has shown that DNA hypermethylation of tumor suppressor genes in colorectal cancer cells may be maintained in the absence of the major mammalian methyltransferase, DNA methyltransferase 1 (DNMT1). In an effort to dissect the dependency on DNMT1 to maintain such hypermethylation in different cancer types, we performed a systematic analysis of depletion of DNMT1 in colorectal (SW48), bladder (T24), and breast (T47D) cancer cells by DNMT1-specific small hairpin RNA (shRNA) targeting. We show that although DNMT1-deficient SW48 and T24 cells exhibited no observable growth defects and were able to maintain promoter hypermethylation, DNMT1-deficient T47D breast cells failed to form comparable numbers of colonies when stably selected for the incorporation of the DNMT1-specific shRNA expression vector, suggesting a growth defect with reduced levels of DNMT1. Further treatment of T47D cells with transient transfection of small interfering RNA targeting DNMT1 revealed that severely DNMT1-deficient T47D cells could not fully maintain promoter hypermethylation, and gene silencing was partially reversed at two of the three assayed loci. These observations suggest that human cancer cells may differ in their reliance on DNMT1 for maintaining DNA methylation.

Original languageEnglish (US)
Pages (from-to)729-735
Number of pages7
JournalCancer Research
Issue number2
StatePublished - Jan 15 2006

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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