6091

ROBO1

roundabout, axon guidance receptor, homolog 1 (Drosophila);ROBO1;roundabout, axon guidance receptor, homolog 1 (Drosophila)

deleted in U twenty twenty|roundabout homolog 1

3p12

protein-coding

OBJECTIVE: To detect the expression of Robo1 in different breast tumors and its association with the breast cancer brain metastasis. METHODS: Labelled streptavidin-biotin (LSAB) staining was used to examine the Robo1 expression in specimens from 24 cases of invasive ductal carcinoma (IDC) with brain metastasis, 71 cases of IDC without brain metastasis, 22 cases of ductal carcinoma in situ (DCIS) and 23 cases of fibroadenoma. RESULTS: The expression pattern of Robo1 in DCIS (59.1%) and IDC (45.3%) was significantly lower than that in adenofibroma (87.0%, P < 0.05). The expression of Robo1 in IDC with brain metastasis (12.5%) was significantly lower than that in IDC without brain metastasis (56.3%, P < 0.05). The expression of Robo1 was much higher in more than 50 year-old-group (57.8%) than that in less than 50 year-old-group (34.0%) of IDC patients. The overall survival time in patients with the Robo1 negative expression was significantly shorter than those with positive expression (P < 0.05). No correlation was found between the Robo1 expression and the tumor size, lymph node metastasis, pathologic stage, histological grade and clinical stage (P > 0.05). CONCLUSIONS: The Robo1 expression correlates negatively with IDC brain metastasis, and correlates positively with the age and prognosis of IDC patients. Robo1 may be applied as a marker in evaluation of the IDC prognosis and brain metastasis.

MicroRNAs play key roles in tumor metastasis. Here, we describe the regulation and function of miR-218 in gastric cancer (GC) metastasis. miR-218 expression is decreased along with the expression of one of its host genes, Slit3 in metastatic GC. However, Robo1, one of several Slit receptors, is negatively regulated by miR-218, thus establishing a negative feedback loop. Decreased miR-218 levels eliminate Robo1 repression, which activates the Slit-Robo1 pathway through the interaction between Robo1 and Slit2, thus triggering tumor metastasis. The restoration of miR-218 suppresses Robo1 expression and inhibits tumor cell invasion and metastasis in vitro and in vivo. Taken together, our results describe a Slit-miR-218-Robo1 regulatory circuit whose disruption may contribute to GC metastasis. Targeting miR-218 may provide a strategy for blocking tumor metastasis.

The Slit family of guidance cues binds to Roundabout (Robo) receptors to modulate neuronal, leukocytic, and endothelial migration. Slit-Robo signaling had been reported to function as chemoattractive signal for vascular endothelial cells during angiogenesis. In this study, we found that Robo1 was expressed in lymphatic endothelial cells to mediate the migration and tube formation of these cells upon Slit2 stimulation, which were specifically inhibited by the function-blocking antibody R5 to Slit2/Robo1 interaction. To further explore the lymphangiogenic effect and significance mediated by Slit-Robo signaling, we intercrossed Slit2 transgenic mice with a non-metastatic RIP1-Tag2 mouse tumor model, and found that transgenic overexpression of Slit2 significantly enhanced tumor lymphangiogenesis and subsequently promoted mesenteric lymph node metastasis of pancreatic islet tumors. Taken together, our findings reveal that through interacting with Robo1, Slit2 is a novel and potent lymphangiogenic factor and contributes to tumor lymphatic metastasis.