LASP-1: a nuclear hub for the UHRF1-DNMT1-G9a-Snail1 complex.

Duvall-Noelle N, Karwandyar A, Richmond A, Raman D
Oncogene. 2016 35 (9): 1122-33

PMID: 25982273 · PMCID: PMC4651668 · DOI:10.1038/onc.2015.166

Nuclear LASP-1 (LIM and SH3 protein-1) has a direct correlation with overall survival of breast cancer patients. In this study, immunohistochemical analysis of a human breast TMA showed that LASP-1 is absent in normal human breast epithelium but the expression increases with malignancy and is highly nuclear in aggressive breast cancer. We investigated whether the chemokines and growth factors present in the tumor microenvironment could trigger nuclear translocation of LASP-1.Treatment of human breast cancer cells with CXCL12, EGF and HRG, and HMEC-CXCR2 cells with CXCL8 facilitated nuclear shuttling of LASP-1. Data from the biochemical analysis of the nuclear and cytosolic fractions further confirmed the nuclear translocation of LASP-1 upon chemokine and growth factor treatment. CXCL12-dependent nuclear import of LASP-1 could be blocked by CXCR4 antagonist, AMD-3100. Knock down of LASP-1 resulted in alterations in gene expression leading to an increased level of cell-junction and extracellular matrix proteins and an altered cytokine secretory profile. Three-dimensional cultures of human breast cancer cells on Matrigel revealed an altered colony growth, morphology and arborization pattern in LASP-1 knockdown cells. Functional analysis of the LASP-1 knockdown cells revealed increased adhesion to collagen IV and decreased invasion through the Matrigel. Proteomic analysis of immunoprecipitates of LASP-1 and subsequent validation approaches revealed that LASP-1 associated with the epigenetic machinery especially UHRF1, DNMT1, G9a and the transcription factor Snail1. Interestingly, LASP-1 associated with UHRF1, G9a, Snail1 and di- and tri-methylated histoneH3 in a CXCL12-dependent manner based on immunoprecipitation and proximity ligation assays. LASP-1 also directly bound to Snail1 which may stabilize Snail1. Thus, nuclear LASP-1 appears to functionally serve as a hub for the epigenetic machinery.

MeSH Terms (23)

Active Transport, Cell Nucleus Adaptor Proteins, Signal Transducing Breast Neoplasms CCAAT-Enhancer-Binding Proteins Cell Line, Tumor Chemokine CXCL12 Cytoskeletal Proteins DNA (Cytosine-5-)-Methyltransferase 1 DNA (Cytosine-5-)-Methyltransferases Epigenesis, Genetic Gene Knockdown Techniques Heterocyclic Compounds Histocompatibility Antigens Histone-Lysine N-Methyltransferase Histones Humans LIM Domain Proteins Prognosis Proteomics Signal Transduction Snail Family Transcription Factors Transcription Factors Tumor Microenvironment

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