title: Metastasis suppressor NME1 regulates melanoma cell morphology, self-adhesion and motility via induction of fibronectin expression.
abstract: Expression of the metastasis suppressor NME1 in melanoma is associated with reduced cellular motility and invasion in vitro and metastasis in vivo, but the underlying molecular mechanisms are not completely understood. Herein, we report a novel mechanism through which NME1 controls melanoma cell morphology via upregulation of the extracellular matrix (ECM) protein fibronectin. Expression of NME1 strongly suppressed cell motility in melanoma cell lines 1205LU and M14. The resulting sedentary phenotype was associated with a more flattened appearance and marked increases in actin stress fibre and focal adhesion formation. NME1-induced focal adhesions were colocalized with dense deposits of fibronectin, which were absent or minimal in the corresponding NME1-deficient parental lines. NME1 was a strong inducer of fibronectin mRNA and protein expression, shown with reciprocal approaches of forced NME1 expression and shRNA-mediated knock-down. Increased synthesis and ECM deposition of fibronectin was necessary for NME1-induced cell spreading, as knock-down of fibronectin opposed the effects of NME1 on cell morphology. Fibronectin knock-down also reversed the ability of NME1 to promote aggregation when cells were plated on a non-adherent substratum. Similarly, inhibiting activation of the fibronectin receptor integrin α4β1 with an anti-α4 antibody reversed the motility-suppressing effect of NME1. A positive correlation was observed between NME1 and fibronectin mRNA in clinical biopsies of normal skin, benign nevi and primary melanomas, but not in metastatic forms, suggesting the NME1/fibronectin axis represents a barrier to melanoma progression. In summary, these findings indicate fibronectin is an important effector of the motility-suppressing function of NME1 in melanoma cells.
authors: Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, School of Medicine, University of Maryland-Baltimore, Baltimore, MD, USA.
authors: Marián
authors: M
authors: Novak
authors: Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, School of Medicine, University of Maryland-Baltimore, Baltimore, MD, USA.
authors: Mary Kathryn
authors: MK
authors: Leonard
authors: Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky, Lexington, KY, USA.
authors: Xiuwei H
authors: XH
authors: Yang
authors: Department of Pharmaceutical Sciences, John D. Dingell VA Medical Center, Wayne State University, Detroit, MI, USA.
authors: Anjan
authors: A
authors: Kowluru
authors: Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, School of Medicine, University of Maryland-Baltimore, Baltimore, MD, USA.|Center for Vascular and Inflammatory Disease, School of Medicine, University of Maryland-Baltimore, Baltimore, MD, USA.
authors: Alexey M
authors: AM
authors: Belkin
authors: Department of Biochemistry and Molecular Biology, Greenebaum Cancer Center, School of Medicine, University of Maryland-Baltimore, Baltimore, MD, USA.
authors: David M
authors: DM
authors: Kaetzel
mesh_terms: D002448:Cell Adhesion / Q000502:physiology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D018450:Disease Progression; D005109:Extracellular Matrix / Q000473:pathology / Q000502:physiology; D005353:Fibronectins / Q000235:genetics / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008545:Melanoma / Q000473:pathology* / Q000503:physiopathology; D054778:NM23 Nucleoside Diphosphate Kinases / Q000235:genetics / Q000502:physiology*; D009362:Neoplasm Metastasis / Q000473:pathology / Q000503:physiopathology; D012333:RNA, Messenger / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D012878:Skin Neoplasms / Q000473:pathology* / Q000503:physiopathology
chemical_list: D005353:Fibronectins; D054778:NM23 Nucleoside Diphosphate Kinases; D012333:RNA, Messenger; C517938:NME1 protein, human
keywords: NME1; fibronectin; melanoma; motility