title: Breast cancer: coordinated regulation of CCL2 secretion by intracellular glycosaminoglycans and chemokine motifs.
abstract: The chemokine CCL2 (MCP-1) has been identified as a prominent tumor-promoting factor in breast cancer. The major source for CCL2 is in the tumor cells; thus, identifying the mechanisms regulating CCL2 release by these cells may enable the future design of modalities inhibiting CCL2 secretion and consequently reduce tumorigenicity. Using cells deficient in expression of glycosaminoglycans (GAGs) and short hairpin RNAs reducing heparan sulfate (HS) and chondroitin sulfate (CS) expression, we found that intracellular HS and CS (=GAGs) partly controlled the trafficking of CCL2 from the Golgi toward secretion. Next, we determined the secretion levels of GFP-CCL2-WT and GFP-CCL2-variants mutated in GAG-binding domains and/or in the 40s loop of CCL2 ((45)TIVA(48)). We have identified partial roles for R18+K19, H66, and the (45)TIVA(48) motif in regulating CCL2 secretion. We have also demonstrated that in the absence of R24 or R18+K19+(45)TIVA(48), the secretion of CCL2 by breast tumor cells was almost abolished. Analyses of the intracellular localization of GFP-CCL2-mutants in the Golgi or the endoplasmic reticulum revealed particular intracellular processes in which these CCL2 sequences controlled its intracellular trafficking and secretion. The R24, (45)TIVA(48) and R18+K19+(45)TIVA(48) domains controlled CCL2 secretion also in other cell types. We propose that targeting these chemokine regions may lead to reduced secretion of CCL2 by breast cancer cells (and potentially also by other malignant cells). Such a modality may limit tumor growth and metastasis, presumably without affecting general immune activities (as discussed below).
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Yaeli
authors.initials: Y
authors.lastname: Lebel-Haziv
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Tsipi
authors.initials: T
authors.lastname: Meshel
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Gali
authors.initials: G
authors.lastname: Soria
authors.affiliation: Bioinformatics Unit, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Adva
authors.initials: A
authors.lastname: Yeheskel
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Elad
authors.initials: E
authors.lastname: Mamon
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. Electronic address: aditbb@tauex.tau.ac.il.
authors.forename: Adit
authors.initials: A
authors.lastname: Ben-Baruch
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D018932:Chemokine CCL2 / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D002809:Chondroitin Sulfates / Q000378:metabolism; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport; D011993:Recombinant Fusion Proteins
chemical_list: D018932:Chemokine CCL2; D002809:Chondroitin Sulfates; D006025:Glycosaminoglycans; D006497:Heparan Sulfate; D011993:Recombinant Fusion Proteins