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MiR-218 inhibits invasion and metastasis of gastric cancer by targeting the Robo1 receptor.

Tie J, Pan Y, Zhao L, Wu K, Liu J, Sun S, Guo X, Wang B, Gang Y, Zhang Y, Li Q, Qiao T, Zhao Q, Nie Y, Fan D - PLoS Genet. (2010)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi, China.

ABSTRACT
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.

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Results of the expression analysis of miR-218, miR-218-1, miR-218-2, Slit2, and Slit3 in 40 matched GC tumors and corresponding normal tissues via qRT–PCR.(A) Schematic representation of the miR-218 genomic locus hosted in the intron of Slit. Expression patterns of Slit2 with miR-218-1 (B) and Slit3 with miR-218-2 (C) exhibited a significant positive correlation, as did mature miR-218 with the miR-218-2 precursor (D), but not with miR-218-1 (E), in GC. A significant differential gene expression pattern was detected between normal and tumor samples with regard to Slit3 (P<0.0001, paired Student's t-test, Figure 6F), but not Slit2 (P = 0.0772, Figure 6G). Using relative quantification methods, the results were expressed as –ΔCt. The left and right lines of (F,G) represent the mean values for the normal and tumor groups, respectively.
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pgen-1000879-g006: Results of the expression analysis of miR-218, miR-218-1, miR-218-2, Slit2, and Slit3 in 40 matched GC tumors and corresponding normal tissues via qRT–PCR.(A) Schematic representation of the miR-218 genomic locus hosted in the intron of Slit. Expression patterns of Slit2 with miR-218-1 (B) and Slit3 with miR-218-2 (C) exhibited a significant positive correlation, as did mature miR-218 with the miR-218-2 precursor (D), but not with miR-218-1 (E), in GC. A significant differential gene expression pattern was detected between normal and tumor samples with regard to Slit3 (P<0.0001, paired Student's t-test, Figure 6F), but not Slit2 (P = 0.0772, Figure 6G). Using relative quantification methods, the results were expressed as –ΔCt. The left and right lines of (F,G) represent the mean values for the normal and tumor groups, respectively.

Mentions: Two types of miRNAs exist: intergenic and intronic. The former are located in non-coding regions between genes, and their corresponding pri-miRNAs are generally transcribed from their own promoters by RNA polymerase II. The latter are located within the introns of host genes, and their biogenesis is controlled by the host gene promoters [41],[42]. miR-218 is an intronic miRNA. Two genes code for mature miR-218, miR-218-1 and miR-218-2, which are located within intron 15 of Slit2 and intron 14 of Slit3, respectively (Figure 6A). The intronic location of the two miR-218 genes prompted us to ask whether miR-218-1 and miR-218-2 are transcribed together with their host gene mRNAs. To test this hypothesis, we used qRT-PCR to examine the expression of the miR-218-1 precursor, the miR-218-2 precursor, mature miR-218, Slit2 mRNA, and Slit3 mRNA in the GC tissues used in the survival analysis. Statistical analysis of the correlation coefficient of the qRT-PCR results revealed a significant positive correlation between the levels of Slit2 mRNA and miR-218-1 and between the levels of Slit3 mRNA and miR-218-2 (Figure 6B and 6C). These results indicate that the miR-218 coding genes, miR-218-1 and miR-218-2, are transcribed together with their host genes, Slit2 and Slit3, respectively. A significant positive correlation between the levels of miR-218 and miR-218-2 (Figure 6D) was seen in GC; however, no such correlation was seen between the levels of miR-218 and miR-218-1 (Figure 6E). These results indicate that downregulation of miR-218 in GC is promoted by a decrease in miR-218-2, but not in miR-218-1. Consistent with this conclusion, Slit3 expression was significantly reduced in GC (−22.43±0.21, mean ± SE) compared to normal gastric tissue (−20.79±0.23, mean ± SE), (P<0.0001, t = 7.67, paired t-test) (Figure 6F), whereas Slit2 expression was not significantly different (P = 0.0772, paired t-test) (Figure 6G). In summary, our experimental results suggest that significant upregulation of the Robo1 gene in response to removal of miR-218 may induce a subsequent upregulation of the Slit-Robo1 pathway through its interaction with Slit2, facilitating tumor cell migration and invasion.


MiR-218 inhibits invasion and metastasis of gastric cancer by targeting the Robo1 receptor.

Tie J, Pan Y, Zhao L, Wu K, Liu J, Sun S, Guo X, Wang B, Gang Y, Zhang Y, Li Q, Qiao T, Zhao Q, Nie Y, Fan D - PLoS Genet. (2010)

Results of the expression analysis of miR-218, miR-218-1, miR-218-2, Slit2, and Slit3 in 40 matched GC tumors and corresponding normal tissues via qRT–PCR.(A) Schematic representation of the miR-218 genomic locus hosted in the intron of Slit. Expression patterns of Slit2 with miR-218-1 (B) and Slit3 with miR-218-2 (C) exhibited a significant positive correlation, as did mature miR-218 with the miR-218-2 precursor (D), but not with miR-218-1 (E), in GC. A significant differential gene expression pattern was detected between normal and tumor samples with regard to Slit3 (P<0.0001, paired Student's t-test, Figure 6F), but not Slit2 (P = 0.0772, Figure 6G). Using relative quantification methods, the results were expressed as –ΔCt. The left and right lines of (F,G) represent the mean values for the normal and tumor groups, respectively.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2837402&req=5

pgen-1000879-g006: Results of the expression analysis of miR-218, miR-218-1, miR-218-2, Slit2, and Slit3 in 40 matched GC tumors and corresponding normal tissues via qRT–PCR.(A) Schematic representation of the miR-218 genomic locus hosted in the intron of Slit. Expression patterns of Slit2 with miR-218-1 (B) and Slit3 with miR-218-2 (C) exhibited a significant positive correlation, as did mature miR-218 with the miR-218-2 precursor (D), but not with miR-218-1 (E), in GC. A significant differential gene expression pattern was detected between normal and tumor samples with regard to Slit3 (P<0.0001, paired Student's t-test, Figure 6F), but not Slit2 (P = 0.0772, Figure 6G). Using relative quantification methods, the results were expressed as –ΔCt. The left and right lines of (F,G) represent the mean values for the normal and tumor groups, respectively.
Mentions: Two types of miRNAs exist: intergenic and intronic. The former are located in non-coding regions between genes, and their corresponding pri-miRNAs are generally transcribed from their own promoters by RNA polymerase II. The latter are located within the introns of host genes, and their biogenesis is controlled by the host gene promoters [41],[42]. miR-218 is an intronic miRNA. Two genes code for mature miR-218, miR-218-1 and miR-218-2, which are located within intron 15 of Slit2 and intron 14 of Slit3, respectively (Figure 6A). The intronic location of the two miR-218 genes prompted us to ask whether miR-218-1 and miR-218-2 are transcribed together with their host gene mRNAs. To test this hypothesis, we used qRT-PCR to examine the expression of the miR-218-1 precursor, the miR-218-2 precursor, mature miR-218, Slit2 mRNA, and Slit3 mRNA in the GC tissues used in the survival analysis. Statistical analysis of the correlation coefficient of the qRT-PCR results revealed a significant positive correlation between the levels of Slit2 mRNA and miR-218-1 and between the levels of Slit3 mRNA and miR-218-2 (Figure 6B and 6C). These results indicate that the miR-218 coding genes, miR-218-1 and miR-218-2, are transcribed together with their host genes, Slit2 and Slit3, respectively. A significant positive correlation between the levels of miR-218 and miR-218-2 (Figure 6D) was seen in GC; however, no such correlation was seen between the levels of miR-218 and miR-218-1 (Figure 6E). These results indicate that downregulation of miR-218 in GC is promoted by a decrease in miR-218-2, but not in miR-218-1. Consistent with this conclusion, Slit3 expression was significantly reduced in GC (−22.43±0.21, mean ± SE) compared to normal gastric tissue (−20.79±0.23, mean ± SE), (P<0.0001, t = 7.67, paired t-test) (Figure 6F), whereas Slit2 expression was not significantly different (P = 0.0772, paired t-test) (Figure 6G). In summary, our experimental results suggest that significant upregulation of the Robo1 gene in response to removal of miR-218 may induce a subsequent upregulation of the Slit-Robo1 pathway through its interaction with Slit2, facilitating tumor cell migration and invasion.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Cancer Biology and Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi, China.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus