title: Slit2 and Robo1 induce opposing effects on metastasis of hepatocellular carcinoma Sk-hep-1 cells.
abstract: The neural guidance molecular, Slit2, and its cognate receptor, Robo1, play critical roles in the development of the nervous system, nevertheless, their functions are not limited to this system. Numerous studies have shown decreased Slit2 expression in a wide variety of cancers, highlighting its potential as a tumor suppressor. However, the Slit2/Robo1 signaling axis was reported to induce either suppressive or stimulatory effects on tumor growth and metastasis, depending on cellular context. There is a paucity of information on the effects of the Slit2/Robo1 signaling axis on the growth and metastasis of human hepatocellular carcinoma (HCC). Large-scale data mining of the Oncomine database has revealed heterogeneous expression of Slit2 in HCC. We screened the Sk-hep-1, a cell line showing a relatively high level of Slit2, and low level of Robo1 expression. After Slit2 knockdown and Robo1 overexpression in these cells, we found Slit2 and Robo1 exerted opposing effects on tumor growth and metastasis both in in vitro and in vivo models. Slit2 knockdown and Robo1 overexpression in Sk-hep-1 cells promoted tumor growth and metastasis, suggesting a negative and positive role for Slit2 and Robo1, respectively, in tumor progression. Robo1 overexpression upregulated matrix metalloproteinase (MMP)2, -9 and membrane-type1 MMP (MT1-MMP) expression, stimulated MMP2, but not MMP9 activation, and downregulated expression of TIMP1 and 2. The PI3K/Akt signaling pathway is of importance in regulating MMP2 expression in Sk-hep-1 cells, since Robo1 overexpression stimulated phosphorylation of Akt while the PI3K inhibitor LY294002, significantly inhibited the upregulation of MMP2 and also the enhanced cell invasion induced by Robo1 overexpression. We postulate that Robo1 promotes tumor invasion partly by the upregulation of MMP2 after activation of PI3K/Akt signaling pathway. Notably, Slit2 knockdown caused the upregulation of Robo1 expression both at the mRNA and protein levels. Thus, the stimulatory effects of Slit2 knockdown on tumor progression can be ascribed, at least in part, to the upregulation of Robo1 and its positive role in tumor progression.
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Mingjing
authors.initials: M
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Chengzhi
authors.initials: C
authors.lastname: Sui
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Qin
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Yasir Hayat
authors.initials: YH
authors.lastname: Khan
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Liying
authors.initials: L
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Fuan
authors.initials: F
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Heng
authors.initials: H
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, P.R. China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ye
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D002867:Chromones / Q000008:administration & dosage; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics*; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D009025:Morpholines / Q000008:administration & dosage; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000096:biosynthesis; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
chemical_list: D002867:Chromones; D036341:Intercellular Signaling Peptides and Proteins; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D009025:Morpholines; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C522361:MMP2 protein, human; C579270:MMP9 protein, human