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Gut 60:1544-1553 doi:10.1136/gut.2011.237495
  • Colon

Statins augment the chemosensitivity of colorectal cancer cells inducing epigenetic reprogramming and reducing colorectal cancer cell ‘stemness’ via the bone morphogenetic protein pathway

  1. James C H Hardwick1
  1. 1Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, The Netherlands
  2. 2Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
  3. 3Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
  4. 4Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center Rotterdam, Rotterdam, The Netherlands
  5. 5Department of Gastroenterology & Hepatology, Academic Medical Center, Amsterdam, The Netherlands
  1. Correspondence to James Hardwick, Leiden University Medical Center, Leiden University Medical Center, Albinusdreef 2, Leiden 2300RC, The Netherlands; j.c.h.hardwick{at}lumc.nl
  • Revised 2 March 2011
  • Accepted 19 March 2011
  • Published Online First 6 May 2011

Abstract

Background Promoter hypermethylation is an important and potentially reversible mechanism of tumour suppressor gene silencing in cancer. Compounds that demethylate tumour suppressor genes and induce differentiation of cancer cells, but do not have toxic side effects, would represent an exciting option in cancer therapy. Statins are cholesterol-lowering drugs with an excellent safety profile and associated with a reduced incidence of various cancers including colorectal cancer (CRC). The authors have previously shown that statins act by activating tumour suppressive bone morphogenetic protein (BMP) signalling in CRC, increasing expression of BMP2. BMP2 is silenced by hypermethylation in gastric cancer.

Aim To investigate whether BMP2 is methylated in CRC, whether statins can reverse this, and what implications this has for the use of statins in CRC.

Methods Methylation-specific PCR, bisulphite sequencing, immunoblotting, reverse transcription PCR, quantitative PCR, fluorescence-activated cell sorting analysis, an in vitro DNA methyltransferase (DNMT) assay, and cell viability studies were performed on CRC cells. The effect of statins was confirmed in a xenograft mouse model.

Results BMP2 is silenced by promoter hypermethylation in cell lines with the hypermethylator phenotype and in primary tumours. Treatment with lovastatin downregulates DNMT activity, leading to BMP2 promoter demethylation and to upregulation of expression of BMP2 as well as other genes methylated in CRC. Statins alter gene expression, indicating a shift from a stem-like state to a more differentiated state, thereby sensitising cells to the effects of 5-fluorouracil. In a xenograft mouse model, simvastatin treatment induces BMP2 expression, leading to differentiation and reduced proliferation of CRC cells.

Conclusions Statins act as DNMT inhibitors, demethylating the BMP2 promoter, activating BMP signalling, inducing differentiation of CRC cells, and reducing ‘stemness’. This study indicates that statins may be able to be used as differentiating agents in combined or adjuvant therapy in CRC with the CpG island methylator phenotype.

Footnotes

  • LLK and RJJ contributed equally to this work.

  • Funding JCHH is supported by The Netherlands Organization for Health Research and Development – (ZonMw VENI 916.76.087). LLK and RJJ are supported by the Dutch Cancer Society (KWF 2007-3725).

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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