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DIAPH3 governs the cellular transition to the amoeboid tumour phenotype.

ABSTRACT: Therapies for most malignancies are generally ineffective once metastasis occurs. While tumour cells migrate through tissues using diverse strategies, the signalling networks controlling such behaviours in human tumours are poorly understood. Here we define a role for the Diaphanous-related formin-3 (DIAPH3) as a non-canonical regulator of metastasis that restrains conversion to amoeboid cell behaviour in multiple cancer types. The DIAPH3 locus is close to RB1, within a narrow consensus region of deletion on chromosome 13q in prostate, breast and hepatocellular carcinomas. DIAPH3 silencing in human carcinoma cells destabilized microtubules and induced defective endocytic trafficking, endosomal accumulation of EGFR, and hyperactivation of EGFR/MEK/ERK signalling. Silencing also evoked amoeboid properties, increased invasion and promoted metastasis in mice. In human tumours, DIAPH3 down-regulation was associated with aggressive or metastatic disease. DIAPH3-silenced cells were sensitive to MEK inhibition, but showed reduced sensitivity to EGFR inhibition. These findings have implications for understanding mechanisms of metastasis, and suggest that identifying patients with chromosomal deletions at DIAPH3 may have prognostic value.

SUBMITTER: Hager MH

PROVIDER: S-EPMC3494074 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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DIAPH3 governs the cellular transition to the amoeboid tumour phenotype.

Hager Martin H MH Morley Samantha S Bielenberg Diane R DR Gao Sizhen S Morello Matteo M Holcomb Ilona N IN Liu Wennuan W Mouneimne Ghassan G Demichelis Francesca F Kim Jayoung J Solomon Keith R KR Adam Rosalyn M RM Isaacs William B WB Higgs Henry N HN Vessella Robert L RL Di Vizio Dolores D Freeman Michael R MR

EMBO molecular medicine 20120516 8

Therapies for most malignancies are generally ineffective once metastasis occurs. While tumour cells migrate through tissues using diverse strategies, the signalling networks controlling such behaviours in human tumours are poorly understood. Here we define a role for the Diaphanous-related formin-3 (DIAPH3) as a non-canonical regulator of metastasis that restrains conversion to amoeboid cell behaviour in multiple cancer types. The DIAPH3 locus is close to RB1, within a narrow consensus region o ...[more]

PMID: 22593025

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Project description:Diaphanous-related formin-3 (DIAPH3), a cytoskeletal regulator of the formin family, is lost at high frequency in metastatic breast and prostate cancers and has characteristics of a non-canonical metastasis suppressor. We previously demonstrated that DIAPH3 silencing evokes transition to an “amoeboid” phenotype, characterized by rapid motility, RhoA/ROCK and MEK/ERK pathway activation, dynamic membrane blebbing, and increased shedding of microvesicles. Here we report that low DIAPH3 mRNA expression correlates with reduced survival in multiple cancer patient cohorts. In line with induction of amoeboid behavior, traction force microscopy (TFM) revealed that polarized force generation, contractility, and response to substrate stiffness are reduced by DIAPH3 loss. Proteomic analyses revealed that DIAPH3 precipitates with tubulins, and reciprocal co-immunoprecipitation analyses revealed greater binding of DIAPH3 to MT polymers than soluble tubulin. DIAPH3 also bound to acetylated-tubulin (Ac-tubulin), suggesting association with a stable MT population. DIAPH3 silencing reduced Ac-tubulin and increased the cellular content of dynamic MT, as indicated by TFM and live cell imaging. DIAPH3 silencing also increased responsiveness to MT-disrupting agents. Treatment with the taxanes paclitaxel and docetaxel, and the non-taxane epothilone B, induced a greater change in Ac-tubulin when cells lacked DIAPH3. Intracellular accumulation of Oregon Green 488-paclitaxel was also increased by DIAPH3 loss, and accordingly, DIAPH3 silencing enhanced cytotoxicity by paclitaxel, docetaxel, or epothilone B. Gene expression profiles of breast cancer patients treated with chemotherapeutic regimens containing taxanes revealed an association of low DIAPH3 expression with improved relapse-free survival. Collectively, these results suggest that regulation of MT stability/dynamics by DIAPH3 enhances amoeboid tumor cell susceptibility to microtubule poisons. These findings have potential therapeutic implications.

Project description:Cellular plasticity confers cancer cells the ability to adapt to microenvironmental changes, a fundamental requirement for tumour progression and metastasis. The epithelial to mesenchymal transition (EMT) is a transcriptional programme associated with increased cell motility and stemness. Besides EMT, the mesenchymal to amoeboid transition (MAT) has been described during tumour progression but to date, little is known about its transcriptional control and involvement in stemness. The aim of this manuscript is to investigate (i) the transcriptional profile associated with the MAT programme and (ii) to study whether MAT acquisition in melanoma cancer cells correlates with clonogenic potential to promote tumour growth.By using a multidisciplinary approach, we identified four different treatments able to induce MAT in melanoma cells: EphA2 overexpression, Rac1 functional inhibition using its RacN17 dominant negative mutant, stimulation with Ilomastat or treatment with the RhoA activator Calpeptin. First, gene expression profiling identified the transcriptional pathways associated with MAT, independently of the stimulus that induces the MAT programme. Notably, gene sets associated with the repression of mesenchymal traits, decrease in the secretion of extracellular matrix components as well as increase of cellular stemness positively correlate with MAT. Second, the link between MAT and stemness has been investigated in vitro by analysing stemness markers and clonogenic potential of melanoma cells undergoing MAT. Finally, the link between MAT inducing treatments and tumour initiating capability has been validated in vivo.Taken together, our results demonstrate that MAT programme in melanoma is characterised by increased stemness and clonogenic features of cancer cells, thus sustaining tumour progression. Furthermore, these data suggest that stemness is not an exclusive feature of cells undergoing EMT, but more generally is associated with an increase in cellular plasticity of cancer cells.

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DIAPH3 governs the cellular transition to the amoeboid tumour phenotype.

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DIAPH3 governs the cellular transition to the amoeboid tumour phenotype.

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