Informula, Etargetand Erefreflect PCR efficiencies of the primers for target genes and reference genes, respectively

Informula, Etargetand Erefreflect PCR efficiencies of the primers for target genes and reference genes, respectively. both the HCC cell lines and tissues:ROBO1,ROBO2,SLIT1in one cluster, KIP1 andROBO4,SLIT2,SLIT3in the other, respectively. Moreover,SLIT-ROBOexpression predictedAFP-dependent subgrouping of HCC cell lines, but not that of liver tissues.ROBO1andROBO2were significantly up-regulated, whereasSLIT3was significantly down-regulated in cell lines with high-AFPbackground. When compared to normal liver tissue,ROBO1was found to be significantly overexpressed, whileROBO4was CZC-25146 hydrochloride down-regulated in HCC. We also observed thatROBO1andSLIT2differentiated histopathological subgroups of liver tissues depending on both tumor staging and differentiation status. However,ROBO4could discriminate poorly differentiated HCC from other subgroups. == Conclusion == The present study is the first in comprehensive and quantitative evaluation ofSLIT-ROBOfamily gene expression in HCC, and suggests that the expression ofSLIT-ROBOgenes is regulated in hepatocarcinogenesis. Our results implicate thatSLIT-ROBOtranscription profile is bi-modular in nature, and that each module shows intrinsic variability. We also provide quantitative evidence for potential use ofROBO1,ROBO4andSLIT2for prediction of tumor stage and differentiation status. == Background == Drosophila slitandroundabout(robo) genes were identified in genetic screens of mutants for embryonic patterning and commissural axon pathfinding defects [1]. Subsequently, it was shown that SLIT acts as a ligand for ROBO receptor, preventing axons from recrossing the central nervous system (CNS) midline, and that this binding is conserved among vertebrates including mammals [2,3]. In mammals, threeSLIT(SLIT1-3) and fourROBO(ROBO1-4) genes have been described [4,5]. SLITandROBOgenes are mainly expressed in the CNS but there are affirmative data that they are also expressed in non-neuronal tissues, such as mouse lung and kidney [6,7]. Binding of SLIT2 to ROBO1 inhibits CXCL12-induced chemotaxis of leukocytes, T cells and monocytes [8-10]. However, ROBO4 expression has been found to be confined to vasculature and Robo4 signaling modulates endothelial cell migration [11]. On the other hand, like other developmental pathways, aberrant expression of theSLIT-ROBOgenes has been observed in a wide variety of cancers. Mice with targeted homozygous deletion of first Ig domain ofRobo1/Dutt1died at birth because of abnormal lung CZC-25146 hydrochloride development, and few survivors eventually developed epithelial bronchial hyperplasia [6]. In breast carcinoma tissue samplesROBO1was shown to be overexpressed while SLIT2 induced migration of breast cancer cell lines [12]. SLIT2-ROBO1 signaling was involved in angiogenesis by increasing microvessel density and tumor mass in a tumor xenograft model [13]. In the same study,SLIT2exhibited overexpression in tumor cell lines and primary tumors of a variety of tissues. In contrast,SLIT2also was proposed to be CZC-25146 hydrochloride a tumor suppressor gene, which was silenced epigenetically in lung, breast, colon cancers and gliomas [14-16].SLIT3was silenced by promoter hypermethylation in gliomas and colorectal cancers [17].SLIT1andSLIT3were overexpressed in prostate tumors [18], whereas along withSLIT2they were slightly expressed only in poorly differentiated HCC [19]. CXCL12 was reported to activate the migration of human melanoma and breast cancer cells that express CXCR4, ROBO1 and ROBO2, while SLIT2-ROBO interaction was demonstrated to inhibit chemotaxis, chemoinvasion and adhesion of breast cancer cells [20]. Furthermore, ROBO4 was overexpressed in tumor endothelial cells in comparison to normal adult endothelial cells [21]. Despite the compiling evidence ofSLIT-ROBOderegulation in various tumors, only few reports with apparent controversies exist with regard to the expression pattern of these genes in hepatocellular carcinoma (HCC). The overexpression of ROBO1 in HCC CZC-25146 hydrochloride was recently reported and this receptor was proposed as an HCC marker in humans [19]. In contrast, another study reported thatRobo1heterozygous mice developed spontaneous HCC tumors [22]. It was shown by immunohistochemical staining that SLIT2 protein also was present in HCC tumor sections [13]. Moreover, karyotyping analyses of HCC do not reveal any chromosomal gains or losses associated withSLIT-ROBOgenes [23,24]. Therefore, in this study, we quantifiedSLIT1,SLIT2,SLIT3,ROBO1,ROBO2andROBO4transcripts in HCC cell lines and tissues. We observed thatSLIT-ROBOgenes could be partitioned into two main clusters based on their expression in either the HCC cell lines or tissues.SLIT-ROBOexpression also clustered the HCC cell lines in two groups according to theirAFPexpression pattern. In liver tissues, differential expression ofROBO1,ROBO4andSLIT2was found to be associated with clinicopathological parameters such as tumor staging and differentiation. Herein, we describe a comprehensiveSLIT-ROBOexpression signature in HCC. == Methods == == HCC Cell Lines and Tissues == 13 hepatoma and 1 hepatoblastoma (HepG2) cell lines were.