Depsipeptide inhibits migration of primary and metastatic uveal melanoma cell lines in vitro: a potential strategy for uveal melanoma.

Uveal melanoma (UM) is a highly malignant primary intraocular tumour in adults that has a high mortality rate due to haematogenous dissemination. The migration of UM cells through the basement membrane requires the presence of proteolytic enzymes, such as matrix metalloproteinases (MMPs). The expression of MMP-2, MMP-9 and membrane type-1/MMP (MT-1/MMP) in UM cells is a known risk factor for metastatic disease. We tested the effect of depsipeptide (DP) on UM cell migration and the level and activity of MMP-2, MMP-9, MT-1/MMP and tissue inhibitors of matrix metalloproteinases 1 and 2 (TIMP-1 and TIMP-2). Three primary and two metastatic (liver metastasis) UM cell lines were treated with DP (0, 1, 5 and 10 nmol/l) for 24 h. Migration of UM cells was studied in modified Boyden migration chambers for 24 h and only viable cells on both sides of the membrane were counted. Enzyme-linked immunosorbent assays (ELISAs) were used to quantify the level of MMP-2, MMP-9, MT-1/MMP, TIMP-1 and TIMP-2 after the cells had been exposed to DP (0, 1, 5 and 10 nmol/l) for 24 h. In addition, the activities of MMP-2, MMP-9 and MT-1/MMP were determined after DP treatment. A dose-dependent decrease in the migration of viable UM cells was observed for primary and metastatic cell lines (30-50% inhibition). We detected a dose-dependent: (1) decrease in the protein level of MMP-2, MMP-9 and MT-1/MMP; (2) decrease in the activity of MMP-2, MMP-9 and MT-1/MMP; and (3) increase in the protein level of TIMP-1 and TIMP-2. It can be concluded that DP is a potent inhibitor of primary and metastatic UM cell migration in vitro. Our data suggest that this inhibition is mediated by the downregulation of MMPs and the upregulation of TIMPs. DP may be a valuable adjunctive treatment modality for primary and metastatic UM in humans.

Depsipeptide (FR901228) inhibits proliferation and induces apoptosis in primary and metastatic human uveal melanoma cell lines.

PURPOSE: Uveal melanoma (UM) is the most common primary malignant ocular tumor in adults. No effective chemotherapy regimens are available for either intraocular or metastatic uveal melanoma. Therefore, the ability of the histone deacetylase inhibitors (HDACIs), depsipeptide, sodium butyrate (NaB) and trichostatin A (TSA), to induce apoptosis and inhibit cell growth of UM cell lines in vitro was examined. METHODS: Three primary and two metastatic UM cell lines were treated in vitro with different concentrations of histone deacetylase inhibitors (HDACIs). Cell proliferation was studied in 24-well plates. Induction of apoptosis was studied by flow cytometry. Changes in gene expression of Fas/FasL, p21(Waf/Cip1), and p27(Kip1) were studied by RT-PCR. Western blot analysis was used to study histone acetylation, Fas/FasL, p21(Waf/Cip1), p27(Kip1) and caspase-3 protein levels. Real-time PCR was used to study changes in bcl-2/bax gene expression. RESULTS: A dose-dependent increase in histone acetylation was observed in all cell lines. This corresponded to significant inhibition of cell growth and induction of apoptosis in all melanoma cell lines in a concentration-dependent manner. Western blot analysis revealed dose-dependent increases in the amount of caspase-3, Fas/FasL, p21(Waf/Cip1), and p27(Kip1) proteins. However, no changes in bcl-2/bax gene expression were detected by real-time PCR. CONCLUSIONS: HDACIs are potent inhibitors of primary and metastatic UM cell growth in vitro. The apoptosis is probably mediated through the Fas/FasL signaling pathway, whereas bcl-2 appears not to be involved. These data support further clinical evaluation of depsipeptide and other HDACIs in patients with primary and metastatic UM.