TY - JOUR
T1 - A ubiquitin ligase, skeletrophin, is a negative regulator of melanoma invasion
AU - Takeuchi, T.
AU - Adachi, Y.
AU - Sonobe, H.
AU - Furihata, M.
AU - Ohtsuki, Y.
N1 - Funding Information:
We are grateful to Drs Karen Artzt (The University of Texas at Austin), Ajay Chitnis (National Institutes of Health, USA) and YY Kong (Pohang University of Science and Technology, South Korea) for helpful suggestions and encouragements. We thank Mr Yamaguchi Takuya, Miss Nakamura Naoyo (Department of Pathology, Kochi Medical School, Japan) and Miss Matumura, Rumi (Division of Molecular Biology, Kochi Medical School, Japan) for providing their skillful techniques. We also thank Miss Minakuchi, Tomoko (Department of Gastroenterology and Hepatology, Kochi Medical School) for kind assistance with the quantitative RT–PCR. This study was supported by grants from the Ministry of Education of Japan (12670165, 13670177 and 17590270), the Medical Research Fund of Kochi Medical School and a Project Grant for short study abroad from the Vice-Chancellor of Kochi Medical School.
PY - 2006/11/9
Y1 - 2006/11/9
N2 - Skeletrophin (mindbomb homolog 2 (MIB2)) is a RING (Really Interesting New Gene) finger-dependent ubiquitin ligase, which targets the intracellular region of Notch ligands. A previous immunohistochemical study demonstrated that skeletrophin was downregulated in many melanomas. In the present study, we have identified a promoter region of skeletrophin on a CpG island and detected aberrant methylation of this region in six of 31 invasive melanomas, but in none of 25 benign nevi or five non-invasive superficial spreading melanomas. Subsequently, we found that a zinc-finger transcriptional factor Snail, which is overexpressed in many melanoma cells, repressed the skeletrophin promoter activity via an E-box-related element and was involved in downregulation of skeletrophin. An activator protein-2, which has a tumor suppressor-like role in melanoma, increased skeletrophin expression. Interestingly, exogenously expressed skeletrophin reduced melanoma cell invasion in vitro and in vivo. Colony formation in soft agar was also reduced in a RING motif-dependent manner, without affecting cell growth. We also found that skeletrophin downregulated transcription of the Met oncogene, which encodes the hepatocyte growth factor receptor and plays a role in the determination of the invasive phenotype of many malignant tumors. Finally, exogenously expressed skeletrophin, but not its RING mutant, increased transcription of Hes1 gene, a downstream effector of Notch pathway in melanoma cells. The present findings indicate that skeletrophin might be a novel suppressor factor for melanoma invasion.
AB - Skeletrophin (mindbomb homolog 2 (MIB2)) is a RING (Really Interesting New Gene) finger-dependent ubiquitin ligase, which targets the intracellular region of Notch ligands. A previous immunohistochemical study demonstrated that skeletrophin was downregulated in many melanomas. In the present study, we have identified a promoter region of skeletrophin on a CpG island and detected aberrant methylation of this region in six of 31 invasive melanomas, but in none of 25 benign nevi or five non-invasive superficial spreading melanomas. Subsequently, we found that a zinc-finger transcriptional factor Snail, which is overexpressed in many melanoma cells, repressed the skeletrophin promoter activity via an E-box-related element and was involved in downregulation of skeletrophin. An activator protein-2, which has a tumor suppressor-like role in melanoma, increased skeletrophin expression. Interestingly, exogenously expressed skeletrophin reduced melanoma cell invasion in vitro and in vivo. Colony formation in soft agar was also reduced in a RING motif-dependent manner, without affecting cell growth. We also found that skeletrophin downregulated transcription of the Met oncogene, which encodes the hepatocyte growth factor receptor and plays a role in the determination of the invasive phenotype of many malignant tumors. Finally, exogenously expressed skeletrophin, but not its RING mutant, increased transcription of Hes1 gene, a downstream effector of Notch pathway in melanoma cells. The present findings indicate that skeletrophin might be a novel suppressor factor for melanoma invasion.
KW - Invasion
KW - Melanoma
KW - Notch
KW - Skeletrophin
KW - Ubiquitin
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U2 - 10.1038/sj.onc.1209688
DO - 10.1038/sj.onc.1209688
M3 - Article
C2 - 16715130
AN - SCOPUS:33750869288
SN - 0950-9232
VL - 25
SP - 7059
EP - 7069
JO - Oncogene
JF - Oncogene
IS - 53
ER -