Vorinostat(SAHA)

Cancer Res,2001 Dec 1;61(23):8492-7.

The histone deacetylase inhibitor suberoylanilide hydroxamic acid induces differentiation of human breast cancer cells[Pubmed: 11016644]

Histone deacetylase (HDACs) regulate histone acetylation by catalyzing the removal of acetyl groups on the NH(2)-terminal lysine residues of the core nucleosomal histones. Modulation of the acetylation status of core histones is involved in the regulation of the transcriptional activity of certain genes. HDAC activity is generally associated with transcriptional repression. Aberrant recruitment of HDAC activity has been associated with the development of certain human cancers.
METHODS AND RESULTS:
We have developed a class of HDAC inhibitors, such as suberoylanilide hydroxamic acid (SAHA), that were initially identified based on their ability to induce differentiation of cultured murine erythroleukemia cells. Additional studies have demonstrated that SAHA inhibits the growth of tumors in rodents. In this study we have examined the effects of SAHA on MCF-7 human breast cancer cells. We found that SAHA causes the inhibition of proliferation, accumulation of cells in a dose-dependent manner in G(1) then G(2)-M phase of the cell cycle, and induction of milk fat globule protein, milk fat membrane globule protein, and lipid droplets. Growth inhibition was associated with morphological changes including the flattening and enlargement of the cytoplasm, and a decrease in the nuclear:cytoplasmic ratio. Withdrawal of SAHA led to reentry of cells into the cell cycle and reversal to a less differentiated phenotype. SAHA induced differentiation in the estrogen receptor-negative cell line SKBr-3 and the retinoblastoma-negative cell line MDA-468.
CONCLUSIONS:
We propose that SAHA has profound antiproliferative activity by causing these cells to undergo cell cycle arrest and differentiation that is dependent on the presence of SAHA. SAHA and other HDAC inhibitors are currently in Phase I clinical trials. These findings may impact the clinical use of these drugs.

Proc Natl Acad Sci U S A, 1998 Mar 17;95(6):3003-7.

A class of hybrid polar inducers of transformed cell differentiation inhibits histone deacetylases.[Pubmed: 9501205]

The lysate of Jurkat cells is incubated for 1 hour on ice and cleared by centrifugation at 12,000 g for 10 minutes at 4 °C. Supernatants are precleared with 30 μL of 50% protein G-Sepharose slurry for 1 hour at 4 °C. Beads are pelleted by centrifugation and supernatants are incubated for 1 hour at 4 °C with 10 μg of IgG fraction from anti-HDAC1 or HDAC3 polyclonal antisera (preincubated 2 hours at room temperature with either the homologous or heterologous immunizing peptide). Both antisera are raised in rabbits against the carboxylterminal peptide of HDAC1 and HDAC3 by using synthetic peptides coupled to keyhole limpet hemocyanin. 30 μL of 50% protein G-Sepharose slurry is added for 1 hour at 4 °C. Immune complexes are pelleted by centrifugation and washed three times with 1 mL of lysis buffer. Beads are resuspended in 200 μL of HDAC buffer (20 mM Tris-HCl, pH 8.0/150 mM NaCl/10% glycerol), and the HDAC assay is performed with an 3H-acetylated peptide corresponding to amino acids 1-24 of histone H4. Released [3H]acetic acid is quantified by scintillation counting. For inhibitions studies, the immunoprecipitated complexes are preincubated with the different concentrations of Vorinostat for 30 minutes at 4 °C.

Cancer Res,2000 Sep 15;60(18):5165-70.

Suberoylanilide hydroxamic acid, an inhibitor of histone deacetylase, suppresses the growth of prostate cancer cells in vitro and in vivo.[Pubmed: 11016644]

Cell lines: LNCaP, PC-3, and TSU-Pr1
Concentrations:  Dissolved in DMSO, final concentrations ~7.5 μM
Incubation Time:  1, 2, 3 and 4 days
Method:
Cells are exposed to various concentrations of Vorinostat for 1, 2, 3 and 4 days. Cell viability is assessed by trypan blue dye exclusion.