A role for RASSF1A in tunneling nanotube formation between cells through GEFH1/Rab11 pathway control

Abstract

BackgroundBy allowing intercellular communication between cells, tunneling nanotubes (TNTs) could play critical role in cancer progression. If TNT formation is known to require cytoskeleton remodeling, key mechanism controlling their formation remains poorly understood.MethodsThe cells of human bronchial (HBEC-3, A549) or mesothelial (H2452, H28) lines are transfected with different siRNAs (inactive, anti-RASSF1A, anti-GEFH1 and / or anti-Rab11). At 48 h post-transfection, i) the number and length of the nanotubes per cell are quantified, ii) the organelles, previously labeled with specific tracers, exchanged via these structures are monitored in real time between cells cultured in 2D or 3D and in normoxia, hypoxia or in serum deprivation condition.ResultsWe report that RASSF1A, a key-regulator of cytoskeleton encoded by a tumor-suppressor gene on 3p chromosome, is involved in TNTs formation in bronchial and pleural cells since controlling proper activity of RhoB guanine nucleotide exchange factor, GEF-H1. Indeed, the GEF-H1 inactivation induced by RASSF1A silencing, leads to Rab11 accumulation and subsequent exosome releasing, which in turn contribute to TNTs formation. Finally, we provide evidence involving TNT formation in bronchial carcinogenesis, by reporting that hypoxia or nutriment privation, two almost universal conditions in human cancers, fail to prevent TNTs induced by the oncogenic RASSF1A loss of expression.ConclusionsThis finding suggests for the first time that loss of RASSF1A expression could be a potential biomarker for TNTs formation, such TNTs facilitating intercellular communication favoring multistep progression of bronchial epithelial cells toward overt malignancy.Electronic supplementary materialThe online version of this article (10.1186/s12964-018-0276-4) contains supplementary material, which is available to authorized users.

Role of the YAP-1 Transcriptional Target cIAP2 in the Differential Susceptibility to Chemotherapy of Non-Small-Cell Lung Cancer (NSCLC) Patients with Tumor RASSF1A Gene Methylation from the Phase 3 IFCT-0002 Trial

“…The authors have previously demonstrated that the loss of RASSF1A expression leads to the inappropriate activity of YAP, the subcellular localization of which becomes preferentially nuclear and coincides with an increase in the transcription of several target genes [4,5,28]. Some IAPs, proteins acting as negative apoptosis regulators by inhibiting the activity of several caspases [29], could also be the transcriptional targets of YAP as shown in drosophila [13].…”

Investigating Tunneling Nanotubes in Cancer Cells: Guidelines for Structural and Functional Studies through Cell Imaging

“…In addition, several teams describe that TNTs also allow tumor cells to reprogram the healthy neighboring cells to make them more conducive to the formation of a tumor niche. Interestingly, not only a hostile environment (inflammation, hypoxia, and inadequate pH) enhances TNT formation [4,[8][9][10][11], but also TNTs could contribute to the escape of the cells from the cell death induced by apoptosis [10,[12][13][14]. On the other hand, TNTs convey resistance to chemotherapy by exporting the mitochondria [15,16].…”

Tunneling Nanotubes and the Eye: Intercellular Communication and Implications for Ocular Health and Disease

“…Of particular interest to vision researchers is the role of the tumor suppressor gene, RASSF1A, in uveal melanomas [115]. RASSF1A binds cytoskeletal proteins such as actin and microtubules, playing an important role in TNT formation, cell cycle regulation, and apoptosis to maintain cellular homeostasis [35,111]. Loss of RASSF1A gene expression is observed in certain cancers, including uveal melanomas in the eye [115,116].…”

“…Loss of RASSF1A gene expression is observed in certain cancers, including uveal melanomas in the eye [115,116]. In malignant mesothelial cell lines, downregulation of RASSF1A increased the number of TNT connections, while overexpression decreased the TNT number and length [35]. Thus, increased TNT-mediated communication concomitant with downregulation of RASSF1A appears linked to cancer progression.…”

“…As the name implies, this latter mechanism depends on actin. Several molecules are also implicated in TNT formation, including M-Sec, myosin-Va, myosin-X, synaptophysin, Rho GTPases (cdc42, Rac1), RASSF1A, LST1, and Rab8/Rab11a [25,[32][33][34][35][36][37][38][39].…”