lncRNA HOTAIR overexpression induced downregulation of c-Met signaling promotes hybrid epithelial/mesenchymal phenotype in hepatocellular carcinoma cells

Abstract

Background: Epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) are both reversible processes, and regulation of phenotypical transition is very important for progression of several cancers including hepatocellular carcinoma (HCC). Recently, it is defined that cancer cells can attain a hybrid epithelial/ mesenchymal (hybrid E/M) phenotype. Cells with hybrid E/M phenotype comprise mixed epithelial and mesenchymal properties, they can be more resistant to therapeutics and also more capable of initiating metastatic lesions. However, the mechanisms regulating hybrid E/M in HCC are not well described yet. In this study, we investigated the role of the potential crosstalk between lncRNA HOTAIR and c-Met receptor tyrosine kinase, which are two essential regulators of EMT and MET, in acquiring of hybrid E/M phenotype in HCC. Methods: Expression of c-Met and lncRNA HOTAIR were defined in HCC cell lines and patient tissues through HCC progression. lncRNA HOTAIR was overexpressed in SNU-449 cells and its effects on c-Met signaling were analyzed. c-Met was overexpressed in SNU-398 cells and its effect on HOTAIR expression was analyzed. Biological significance of HOTAIR/c-Met interplay was defined in means of adhesion, proliferation, motility behavior, invasion, spheroid formation and metastatic ability. Effect of ectopic lncRNA HOTAIR expression on phenotype was defined with investigation of molecular epithelial and mesenchymal traits. Results: In vitro and in vivo experiments verified the pivotal role of lncRNA HOTAIR in acquisition of hybrid E/M phenotype through modulating expression and activation of c-Met and its membrane co-localizing partner Caveolin-1, and membrane organization to cope with the rate limiting steps of metastasis such as survival in adhesion independent microenvironment, escaping from anoikis and resisting to fluidic shear stress (FSS) in HCC. Conclusions: Our work provides the first evidence suggesting a role for lncRNA HOTAIR in the modulation of c-Met to promote hybrid E/M phenotype. The balance between lncRNA HOTAIR and c-Met might be critical for cell fate decision and metastatic potential of HCC cells.

Hypoxia, partial EMT and collective migration: Emerging culprits in metastasis

“…Recent high-throughput studies have emphasized that EMT is not a binary process but can progress through multiple stable hybrid states [ 39 , 76 ] referred often interchangeably as intermediate EMT, intermediate mesenchymal, partial EMT, hybrid epithelial/mesenchymal, incomplete EMT, semi-mesenchymal, EMT-like, metastable [ 10 ]. The importance of hybrid E/M state(s) is supported by observations that induction of fully mesenchymal state results into loss of tumor-initiating and/or colonization potential [ 40 , 77 ] while cells in the hybrid E/M state might display maximum tumor-initiation potential when compared with cells in epithelial or mesenchymal states [ 38 , [77] , [78] , [79] ].…”

Emerging Concepts of Hybrid Epithelial-to-Mesenchymal Transition in Cancer Progression

“…The upregulation of long noncoding RNA (lncRNA) myocardin-induced smooth muscle lncRNA, inducer of differentiation (MYOSLID) was associated with the modulation of partial EMT, leading to metastasis and poor prognosis in head and neck squamous cell carcinoma (HNSCC) [24]. Overexpression of lncRNA HOX Transcript Antisense Intergenic RNA (HOTAIR), maintained hybrid EMT phenotypes and induced migration in HCC cells [25].…”

The Intimate Relationship among EMT, MET and TME: A T(ransdifferentiation) E(nhancing) M(ix) to Be Exploited for Therapeutic Purposes

“…Finally, noncoding RNAs, like long noncoding RNAs and miRs are important players in regulating pEMT states. Overexpression of the lncRNA, HOTAIR (HOX transcript antisense intergenic RNA), maintained pEMT phenotypes and induced migratory activity in HCC (hepatocellular carcinoma) cells [113]. Upregulation of MYOSLID (myocardin-induced smooth muscle lncRNA, inducer of differentiation), was associated with the modulation of pEMT, resulting in metastasis and poor prognosis in head-and-neck squamous cell carcinoma [114].…”