MKK7 mediates miR-493-dependent suppression of liver metastasis of colon cancer cells.
Bottom Line: MKK7 was expressed in six out of seven colon cancer cell lines examined but not in non-transformed colon epithelial cells, and its expression was required for the activating phosphorylation of JNK.RNA interference-mediated inhibition of MKK7 resulted in marked suppression of liver metastasis of colon cancer cells.Immunohistochemical examination in human primary colon tumors revealed that the occurrence of liver metastasis is associated with elevated levels of MKK7.
Affiliation: Division of Cancer Development System, National Cancer Center Research Institute, Tokyo, Japan.Show MeSH
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Mentions: Identification of MKK7 as a novel target gene of miR-493 prompted us to examine whether MKK7 is involved in liver metastasis of colon cancer cells. We inhibited MKK7 expression in GFP-expressing HCT116 cells(11) by siRNA-mediated knockdown (Fig. 3a), and after mixing them with an equal number of the RFP-expressing HCT116 cells, injected the mixture of these cells into the spleen of immunocompromized NOG mice. Ten days after the splenic injection, formation of metastatic foci of both GFP-expressing and RFP-expressing cells was confirmed by dual fluorescence imaging (Fig. S2, left panel). Subsequently, the transfected HCT116/GFP and HCT116/RFP cells were recovered from the metastasized liver, and the ratio of the GFP cells versus the RFP-positive internal control cells was calculated by flow cytometry to determine the inhibitory effect of each oligonucleotide on liver metastasis.(11) Two different siRNAs that correspond to MKK7 were used (Fig. 3a), and in both cases the knockdown of MKK7 caused significant reduction (˜60%) of liver metastasis in comparison to the control siRNAs (Fig. 3b).
Affiliation: Division of Cancer Development System, National Cancer Center Research Institute, Tokyo, Japan.