title: Endostatin suppresses colorectal tumor-induced lymphangiogenesis by inhibiting expression of fibronectin extra domain A and integrin α9.
abstract: Endostatin is a natural occurring anti-angiogenic peptide and has been shown to inhibit tumor lymphangiogenesis by suppressing the expression of tumor-stimulating growth factors. We have previously shown that fibronectin alternative extra domain A (EDA) facilitates lymphangiogenesis of colorectal tumors. Since it is known that EDA interacts with integrin α9 in the lymphatic endothelial cells (LECs), we hypothesized that endostatin may target EDA-integrin α9 pathway to inhibit colorectal tumor-induced lymphangiogenesis. To test this hypothesis, we examined the effect of endostatin on EDA secreted by SW480 colorectal cancer cells and treated human LECs with different doses of endostatin in the presence of conditional medium from SW480 cells. We found that endostatin significantly reduced EDA secretion by SW480 cells and the expression of integrin α9 in LECs. Immunofluorescence studies showed that EDA and integrin α9 colocalized on the cell membrane of LECs and these colocalizations were dramatically reduced by endostatin. Co-immunoprecipitation studies demonstrated that EDA interacted with integrin α9 in LECs, and showed that endostatin treatment inhibited the formation of EDA-integrin α9 complex in LECs. Furthermore, we found that the arrangement and polarity of LEC cytoskeletons were destroyed by endostatin substantially, leading to a reduced formation of tube-like structures of LECs and a suppressed chemotaxis of LECs toward SW480 cells. Consistently, EDA and integrin α9 expressions as well as lymphangiogenesis were significantly suppressed by endostatin in colorectal cancer xenografts. In conclusion, our results suggest that endostatin reduces colorectal tumor-induced lymphangiogenesis, at least in part, by inhibiting EDA-integrin α9 pathway.
authors.affiliation: Department of Oncology and Southwest Cancer Center, Southwest Hospital, The Third Military Medical University, Chongqing, P. R. China.
authors.forename: Juanjuan
authors.initials: J
authors.lastname: Ou
authors.forename: Jianjun
authors.initials: J
authors.lastname: Li
authors.forename: Feng
authors.initials: F
authors.lastname: Pan
authors.forename: Ganfeng
authors.initials: G
authors.lastname: Xie
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
authors.forename: Haihui
authors.initials: H
authors.lastname: Huang
authors.forename: Houjie
authors.initials: H
authors.lastname: Liang
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D043169:Endostatins / Q000494:pharmacology*; D042783:Endothelial Cells / Q000378:metabolism*; D005353:Fibronectins / Q000096:biosynthesis*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D016023:Integrins / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D046912:Multiprotein Complexes / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism*; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000378:metabolism*; D014183:Transplantation, Heterologous
chemical_list: D020533:Angiogenesis Inhibitors; D043169:Endostatins; D005353:Fibronectins; C541973:ITGA9 protein, human; D016023:Integrins; D046912:Multiprotein Complexes; D009363:Neoplasm Proteins