title: Sec6/8 regulates Bcl-2 and Mcl-1, but not Bcl-xl, in malignant peripheral nerve sheath tumor cells.
abstract: Sec6 and Sec8, which are components of the exocyst complex, has been concerned with various roles independent of its role in secretion, such as cell migration, invadopodia formation, cytokinesis, glucose uptake, and neural development. Given the vital roles of the exocyst complex in cellular and developmental processes, the disruption of its function may be closely related to various diseases such as cancer, diabetes, and neuronal disorders. Malignant peripheral nerve sheath tumors (MPNSTs) have high malignant potential and poor prognosis because of aggressive progression and metastasis. To date, no chemotherapeutic agents have been validated for MPNSTs treatment because how MPNSTs are resistant to chemotherapeutic agents remains unknown. This study demonstrates that combination of doxorubicin and sorafenib induces apoptosis in MPNST cells through downregulation of B cell lymphoma protein 2 (Bcl-2), Bcl-2-related protein long form of Bcl-x (Bcl-xl), and myeloid cell leukemia 1 (Mcl-1). Moreover, both Sec6 and Sec8 levels decreased after treatment with doxorubicin and sorafenib and were found to be associated with Bcl-2 and Mcl-1 expressions, but not Bcl-xl. Although Sec8 was found to be involved in the regulation of both Bcl-2 and Mcl-1 at the mRNA level, Sec6 regulated Bcl-2 at the mRNA level and the binding affinity of F-box and WD repeat domain containing 7 and Mcl-1, thereby controlling Mcl-1 at the protein level. Bcl-2 or Mcl-1 mRNA suppression by Sec6 or Sec8 depletion resulted in significant changes in nuclear factor-kappa B, cAMP response element, and p53 transcriptional activity. These results suggest that Sec6 and Sec8 are therapeutic target molecules in MPNST.
authors.affiliation: Department of Anatomy and Cell Biology, School of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata, 990-9585, Japan. ttanaka@med.id.yamagata-u.ac.jp.|Department of Dentistry, Oral and Maxillofacial Surgery, Plastic and Reconstructive Surgery, School of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata, Japan. ttanaka@med.id.yamagata-u.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Dentistry, Oral and Maxillofacial Surgery, Plastic and Reconstructive Surgery, School of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Kikuchi
authors.affiliation: Department of Anatomy and Cell Biology, School of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata, 990-9585, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Goto
authors.affiliation: Department of Dentistry, Oral and Maxillofacial Surgery, Plastic and Reconstructive Surgery, School of Medicine, Yamagata University, 2-2-2 Iidanishi, Yamagata, Japan.
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Iino
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000235:genetics* / Q000378:metabolism; D018317:Nerve Sheath Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D009536:Niacinamide / Q000031:analogs & derivatives / Q000494:pharmacology; D010671:Phenylurea Compounds / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics* / Q000378:metabolism; D000077157:Sorafenib; D014158:Transcription, Genetic; D033921:Vesicular Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C490685:EXOC3 protein, human; C489607:EXOC4 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D010671:Phenylurea Compounds; D019253:Proto-Oncogene Proteins c-bcl-2; D033921:Vesicular Transport Proteins; D051020:bcl-X Protein; D009536:Niacinamide; D004317:Doxorubicin; D000077157:Sorafenib
keywords: B-cell lymphoma protein 2; F-box and WD repeat domain containing 7; Malignant peripheral nerve sheath tumors; Myeloid cell leukemia 1; Sec6; Sec8