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INTRODUCTION: High-grade gliomas feature prominently among the most devastating cancers due to their prevalence in the younger population, highly invasive nature and low 5-year survival. Despite a combined treatment regime of surgical resection, radiation therapy and chemotherapy most patients die within 1 year of initial diagnosis. Alternative, novel ways to treat these tumours are urgently required. Histone deacetylase (HDAC) are important regulators of chromatin remodelling and gene expression and have been shown to be involved in cancer. There is an increasing interest in the study and development of HDAC inhibitors towards clinical application. Moreover, they have been recently reported to inhibit cell migration due to their modulation of tubulin acetylation. Thus HDAC inhibitors represent attractive candidates for chemotherapeutics especially when considering the infiltrative nature of high-grade gliomas. Here, the specific HDAC2/3 inhibitor MI192 developed at Leeds University was investigated for its ability to inhibit 2D and 3D migration of two established adult glioma cell lines. METHODS: U87 and U251 cell lines were used for migration and cytoskeletal studies in 2D and 3D assays. The HDAC inhibitor MI192 was assessed for its ability to inhibit migration alongside LiCl and Bio-Indirubin, two anti-migratory drugs commonly used in glioma in vitro studies. RESULTS: In random migration (2D) the MI192 inhibitor adversely affected the migratory ability of U87 and U251 as evidenced by reduced cell velocity and also cell displacement. This effect was more pronounced in U251 than U87. Immunofluorescence studies of the MI192-treated cells revealed an increase in the acetylation of tubulin in U87, whilst proliferation and apoptosis status remained unchanged. U251 did not appear to show increased levels of tubulin acetylation. In a 3D spheroid invasion assay U87 migration was inhibited by MI192 at 1 uM concentration, but not at 0.1 or 0.01 uM, whereas we did not see a significant change in U251. Immunohistochemistry of the treated spheroids revealed that proliferation was adversely affected in both the core and migratory cells in U87 spheroids with MI192 at a concentration of 1 uM but not in U251 spheroids. Tubulin acetylation appeared more pronounced in U251 after MI192 treatment. In addition, SOX-2 (as a marker of stemness) was reduced in both U251 cores and migratory cells with MI192. CONCLUSION: In addition to its activity as a chromatin remodelling inhibitor, MI192 appears to inhibit glioma cell migration via hyperacetylation of tubulin and possibly microtubule stabilisation in a cell line and topography dependent manner. Thus, the HDAC2/3 inhibitor MI192 may prove useful in targeting migration in certain subtypes of glioma cell. |
