title: Identification of beta-2 as a key cell adhesion molecule in PCa cell neurotropic behavior: a novel ex vivo and biophysical approach.
abstract: Prostate cancer (PCa) is believed to metastasize through the blood/lymphatics systems; however, PCa may utilize the extensive innervation of the prostate for glandular egress. The interaction of PCa and its nerve fibers is observed in 80% of PCa and is termed perineural invasion (PNI). PCa cells have been observed traveling through the endoneurium of nerves, although the underlying mechanisms have not been elucidated. Voltage sensitive sodium channels (VSSC) are multimeric transmembrane protein complexes comprised of a pore-forming α subunit and one or two auxiliary beta (β) subunits with inherent cell adhesion molecule (CAM) functions. The beta-2 isoform (gene SCN2B) interacts with several neural CAMs, while interacting putatively with other prominent neural CAMs. Furthermore, beta-2 exhibits elevated mRNA and protein levels in highly metastatic and castrate-resistant PCa. When overexpressed in weakly aggressive LNCaP cells (2BECFP), beta-2 alters LNCaP cell morphology and enhances LNCaP cell metastasis associated behavior in vitro. We hypothesize that PCa cells use beta-2 as a CAM during PNI and subsequent PCa metastasis. The objective of this study was to determine the effect of beta-2 expression on PCa cell neurotropic metastasis associated behavior. We overexpressed beta-2 as a fusion protein with enhanced cyan fluorescence protein (ECFP) in weakly aggressive LNCaP cells and observed neurotropic effects utilizing our novel ex vivo organotypic spinal cord co-culture model, and performed functional assays with neural matrices and atomic force microscopy. With increased beta-2 expression, PCa cells display a trend of enhanced association with nerve axons. On laminin, a neural CAM, overexpression of beta-2 enhances PCa cell migration, invasion, and growth. 2BECFP cells exhibit marked binding affinity to laminin relative to LNECFP controls, and recombinant beta-2 ectodomain elicits more binding events to laminin than BSA control. Functional overexpression of VSSC beta subunits in PCa may mediate PCa metastatic behavior through association with neural matrices.
authors.affiliation: Laboratory for Cancer Ontogeny and Therapeutics, Department of Biological Sciences, University of Delaware, Newark, Delaware, United States of America; The Center for Translational Cancer Research, University of Delaware, Newark, Delaware, United States of America.
authors.forename: Keith H
authors.initials: KH
authors.lastname: Jansson
authors.affiliation: Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Deborah G
authors.initials: DG
authors.lastname: Castillo
authors.affiliation: Laboratory for Cancer Ontogeny and Therapeutics, Department of Biological Sciences, University of Delaware, Newark, Delaware, United States of America; The Center for Translational Cancer Research, University of Delaware, Newark, Delaware, United States of America.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Morris
authors.affiliation: The Center for Translational Cancer Research, University of Delaware, Newark, Delaware, United States of America.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Boggs
authors.affiliation: The Center for Translational Cancer Research, University of Delaware, Newark, Delaware, United States of America; Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States of America.
authors.forename: Kirk J
authors.initials: KJ
authors.lastname: Czymmek
authors.affiliation: Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States of America.
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Adams
authors.affiliation: Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Lawrence P
authors.initials: LP
authors.lastname: Schramm
authors.affiliation: Laboratory for Cancer Ontogeny and Therapeutics, Department of Biological Sciences, University of Delaware, Newark, Delaware, United States of America; The Center for Translational Cancer Research, University of Delaware, Newark, Delaware, United States of America.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sikes
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D001426:Bacterial Proteins / Q000378:metabolism; D055592:Biophysical Phenomena / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D055119:Elastic Modulus / Q000187:drug effects; D006801:Humans; D007797:Laminin / Q000494:pharmacology; D008164:Luminescent Proteins / Q000378:metabolism; D008297:Male; D008822:Mice, Transgenic; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D013116:Spinal Cord / Q000473:pathology; D062548:Voltage-Gated Sodium Channel beta-2 Subunit / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D007797:Laminin; D008164:Luminescent Proteins; D011994:Recombinant Proteins; D062548:Voltage-Gated Sodium Channel beta-2 Subunit; C054562:yellow fluorescent protein, Bacteria