The Ser/Thr kinase MAP4K4 drives c-Met-induced motility and invasiveness in a cell-based model of SHH medulloblastoma

Abstract

Medulloblastoma (MB) comprises four molecularly and genetically distinct subgroups of embryonal brain tumors that develop in the cerebellum. MB mostly affects infants and children and is difficult to treat because of frequent dissemination of tumor cells within the leptomeningeal space. A potential promoter of cell dissemination is the c-Met proto-oncogene receptor tyrosine kinase, which is aberrantly expressed in many human tumors including MB. Database analysis showed that c-Met is highly expressed in the sonic hedgehog (SHH) subgroup and in a small subset of Group 3 and Group 4 MB tumors. Using a cell-based three-dimensional cell motility assay combined with live-cell imaging, we investigated whether the c-Met ligand HGF could drive dissemination of MB cells expressing high levels of c-Met, and determined downstream effector mechanisms of this process. We detected variable c-Met expression in different established human MB cell lines, and we found that in lines expressing high c-Met levels, HGF promoted cell dissemination and invasiveness. Specifically, HGF-induced c-Met activation enhanced the capability of the individual cells to migrate in a JNK-dependent manner. Additionally, we identified the Ser/Thr kinase MAP4K4 as a novel driver of c-Met-induced invasive cell dissemination. This increased invasive motility was due to MAP4K4 control of F-actin dynamics in structures required for migration and invasion. Thus, MAP4K4 couples growth factor signaling to actin cytoskeleton regulation in tumor cells, suggesting that MAP4K4 could present a promising novel target to be evaluated for treating growth factor-induced dissemination of MB tumors of different subgroups and of other human cancers.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-0784-2) contains supplementary material, which is available to authorized users.

Computer-assisted quantification of motile and invasive capabilities of cancer cells

“…Both cell lines stably express lifeact-EGFP (LA-EGFP) for monitoring F-actin dynamics. Consistent with our previous quantifications 23 , blocking c-Met with pharmacological inhibitors reduced basal migration and prevented HGF-induced motility ( Fig. 3B,C and Supplementary Fig.…”

“…HGF/c-Met signalling promotes motility of MB tumour cells, and is associated with an aggressive invasive phenotype in patients 21 23 . Therefore, we used HGF stimulation to validate our assays in combination with aCDc.…”

“…Targeting cell motility alone might not be sufficient to eradicate the cancer; however, it may contribute to its control by restricting local infiltration, by limiting further dissemination and by preventing the evolution towards a more aggressive phenotype 3 . HGF 21 23 31 32 and EGF 33 were previously shown to promote motility of MB cells. No pro-migratory functions of bFGF have been described in MB so far.…”

“…Therefore, an ideal target for a future drug would be a molecular hub that integrates signals from all three pathways. With MAP4K4 we recently identified such a potential convergence kinase downstream of HGF function in MB 23 , which is also activated by EGF 36 and TNFa 37 to promote cell motility. aCDc also identified the specific response of UW228 cells to IL-6 stimulation.…”

“…DAOY and UW228 cells were cultured as described in 39 . DAOY LA-EGFP and UW228 LA-EGFP cells were produced by lentiviral transduction of DAOY and UW228 cells with pLenti-LA-EGFP 23 . Human primary medulloblastoma cells were derived from a resected tumour of a nine-year-old patient with an M2 stage medulloblastoma with cerebellar metastases.…”