Abstract
Histone deacetylases (HDACs) are validated targets for anticancer therapy as attested by the approval of suberoylanilide hydroxamic acid (SAHA) and romidepsin (FK228) for treating cutaneous T cell lymphoma. We recently described the bioassay-guided isolation, structure determination, synthesis, and target identification of largazole, a marine-derived antiproliferative natural product that is a prodrug that releases a potent HDAC inhibitor, largazole thiol. Here, we characterize the anticancer activity of largazole by using in vitro and in vivo cancer models. Screening against the National Cancer Institute's 60 cell lines revealed that largazole is particularly active against several colon cancer cell types. Consequently, we tested largazole, along with several synthetic analogs, for HDAC inhibition in human HCT116 colon cancer cells. Enzyme inhibition strongly correlated with the growth inhibitory effects, and differential activity of largazole analogs was rationalized by molecular docking to an HDAC1 homology model. Comparative genomewide transcript profiling revealed a close overlap of genes that are regulated by largazole, FK228, and SAHA. Several of these genes can be related to largazole's ability to induce cell cycle arrest and apoptosis. Stability studies suggested reasonable bioavailability of the active species, largazole thiol. We established that largazole inhibits HDACs in tumor tissue in vivo by using a human HCT116 xenograft mouse model. Largazole strongly stimulated histone hyperacetylation in the tumor, showed efficacy in inhibiting tumor growth, and induced apoptosis in the tumor. This effect probably is mediated by the modulation of levels of cell cycle regulators, antagonism of the AKT pathway through insulin receptor substrate 1 down-regulation, and reduction of epidermal growth factor receptor levels.
Footnotes
-
This work was supported by the National Institutes of Health National Cancer Institute [Grant R01-CA138544].
-
Data Deposition: The microarray data have been deposited in the Gene Expression Omnibus database (accession no. GSE22061).
-
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.172387.
-
↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
-
ABBREVIATIONS:
- HDAC
- histone deacetylase
- CDK6
- cyclin-dependent kinase 6
- EGFR
- epidermal growth factor receptor
- HER-2
- ERBB2 (v-erb-b2 erythroblastic leukemia viral oncogene homolog 2)
- IRS-1
- insulin receptor substrate 1
- MET
- met protooncogene (hepatocyte growth factor receptor)
- MRM
- multiple reaction monitoring
- NCI
- National Cancer Institute
- PI3K
- phosphoinositide 3-kinase
- SAHA
- suberoylanilide hydroxamic acid
- SAR
- structure–activity relationship
- FK228
- romidepsin
- HPLC-MS
- high-performance liquid chromatography-mass spectrometry
- DP
- declustering potential
- EP
- entrance potential
- CE
- collision energy
- CXP
- collision cell exit potential
- CEP
- collision cell entrance potential.
- Received July 1, 2010.
- Accepted August 23, 2010.
- Copyright © 2010 by the American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|