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Overexpression and constitutive nuclear localization of cohesin protease Separase protein correlates with high incidence of relapse and reduced overall survival in glioblastoma multiforme. J Neurooncol 2014; 119:27-35. [PMID: 24792645 DOI: 10.1007/s11060-014-1458-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 04/20/2014] [Indexed: 12/31/2022]
Abstract
Separase, an enzyme that cleaves the chromosomal cohesin during mitosis, is overexpressed in a wide range of human epithelial cancers of breast, bone and prostate (Meyer et al., Clin Cancer Res 15(8):2703-2710, 2009). Overexpression of Separase in animal models results in aneuploidy and tumorigenesis. We have examined the expression and localization of Separase protein in adult and pediatric glioblastoma and normal brain specimens. Immunofluorescence microscopy and Western blot analysis showed significant overexpression of Separase in all adult and a subset of pediatric glioblastoma cells. Tumor status and patient survival strongly correlate with the mislocalization of Separase into the nucleus throughout all stages of the cell cycle. Unlike exclusively nuclear localization in mitotic control cells, glioblastoma samples have a significantly higher number of resting (interphase) cells with strong nuclear Separase staining. Additionally, patient survival analysis demonstrated a strong correlation between overexpression of Separase protein in adult glioblastoma and a high incidence of relapse and reduced overall survival. These results further strengthen our hypothesis that Separase is an oncogene whose overexpression induces tumorigenesis, and indicate that Separase overexpression and aberrant nuclear localization are common in many tumor types and may predict outcome in some human malignancies.
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Zhang N, Scorsone K, Ge G, Kaffes CC, Dobrolecki LE, Mukherjee M, Lewis MT, Berg S, Stephan CC, Pati D. Identification and Characterization of Separase Inhibitors (Sepins) for Cancer Therapy. ACTA ACUST UNITED AC 2014; 19:878-89. [PMID: 24525869 DOI: 10.1177/1087057114520972] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 01/03/2014] [Indexed: 11/15/2022]
Abstract
Separase is an endopeptidase that cleaves cohesin subunit Rad21, facilitating the repair of DNA damage during interphase and the resolution of sister chromatid cohesion at anaphase. Separase activity is negatively regulated by securin and Cdk1-cyclin B in vivo. Separase overexpression is reported in a broad range of human tumors, and its overexpression in mouse models results in tumorigenesis. To elucidate further the mechanism of separase function and to test if inhibition of overexpressed separase can be used as a strategy to inhibit tumor-cell proliferation, small-molecule inhibitors of separase enzyme are essential. Here, we report a high-throughput screening for separase inhibitors (Sepins). We developed a fluorogenic separase assay using rhodamine 110-conjugated Rad21 peptide as substrate and screened a small-molecule compound library. We identified a noncompetitive inhibitor of separase called Sepin-1 that inhibits separase enzymatic activity with a half maximal inhibitory concentration (IC50) of 14.8 µM. Sepin-1 can inhibit the growth of human cancer cell lines and breast cancer xenograft tumors in mice by inhibiting cell proliferation and inducing apoptosis. The sensitivity to Sepin-1 in most cases is positively correlated to the level of separase in both cancer cell lines and tumors.
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Affiliation(s)
- Nenggang Zhang
- Texas Children's Cancer Center, and Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Kathleen Scorsone
- Texas Children's Cancer Center, and Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Gouqing Ge
- Texas Children's Cancer Center, and Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Caterina C Kaffes
- Texas Children's Cancer Center, and Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Lacey E Dobrolecki
- Lester & Sue Smith Breast Center, and Departments of Molecular and Cellular Biology and Radiology, Baylor College of Medicine, Houston, TX, USA
| | - Malini Mukherjee
- Texas Children's Cancer Center, and Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Michael T Lewis
- Lester & Sue Smith Breast Center, and Departments of Molecular and Cellular Biology and Radiology, Baylor College of Medicine, Houston, TX, USA
| | - Stacey Berg
- Texas Children's Cancer Center, and Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | | | - Debananda Pati
- Texas Children's Cancer Center, and Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
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