Biology subjects

Sechi, A.

Publications and source records attributed to Sechi, A..

4 recordsLinked to original sources

bioRxiv2022

SPAG6 promotes cell migration and induces epithelial-to-mesenchymal transition in luminal breast cancer cells

Understanding the involvement of promoter DNA methylation changes in the development of breast cancer may be highly informative for designing more effective therapeutic treatments. We recently characterized the Sperm Associated Antigen 6 (SPAG6) gene, encoding a flagellar motility protein, as a potential DNA methylation biomarker for blood-based early breast cancer detection. Here we present the first study to evaluate the functional role of SPAG6 in human breast cancer. In silico analysis of the HumanMethylation450 BeadChip and Illumina HiSeq data of The Cancer Genome Atlas (TCGA) was performed in both normal (n=114) and breast cancer patient tissues (n=1104) to determine SPAG6 DNA methylation and expression. Stable SPAG6 overexpressing cancer models for in vitro analysis were obtained by lentivirus-mediated gene delivery in T-47D, MCF-7, MDA-MB-231 and BT-549 breast cancer cells. Subsequently stable mock and SPAG6 cell lines were compared in cellular assays. In addition, involvement of SPAG6 in EMT was analysed by qPCR and immunolabeling experiments. All major molecular subtypes of breast cancer (luminal A, luminal B, basal-type, HER2-enriched) revealed a tumor-specific increased SPAG6 promoter hypermethylation that correlated with strong reduction in SPAG6 mRNA expression. Interestingly, a small group of luminal breast tumors exhibited SPAG6 mRNA overexpression compared to normal breast tissue. SPAG6 overexpression caused a significant reduction (p<0.05) in colony formation in basal MDA-MB-231 and BT-549 cells. In turn, luminal T-47D cells overexpressing SPAG6 showed a significant increase in colony formation (p=0.0004) and both T-47D-and MCF-7 cells overexpressing SPAG6 exhibited a robust increase in migration speed (p<0.0001). In SPAG6-positive T-47D cells SNAIL, TWIST1 and Vimentin expression was found to be significantly upregulated, while E-Cadherin expression was supressed. SPAG6 overexpressing T47D cells showed a typical epithelial-mesenchymal transition (EMT). This was accompanied by a nearly complete displacement of both actin and E-cadherin from cell-cell junctions. Our in vitro analyses give functional evidence that SPAG6 has a profound effect on colony formation, migration and intercellular junction composition in breast cancer cells. Our study is the first to show opposing SPAG6 effects in a single tumour entity depending on the molecular subtype. We propose that SPAG6 might be a key player for inducing the EMT program in luminal-type breast cancers, driving tumour progression and metastasis.

cell biology↗

bioRxiv2021

Met-signaling controls Dendritic Cell migration by regulating podosome formation and function

Signaling by the HGF receptor/Met in skin-resident Langerhans cells (LC) and dermal dendritic cells (dDC) is essential for their emigration toward draining lymph nodes upon inflammation-induced activation. Here we addressed the role of Met-signaling in distinct steps of LC/dDC emigration from skin by employing a conditional Met-deficient mouse model (Metflox/flox). We found that Met deficiency severely impaired podosome formation in DC and concomitantly decreased proteolytic degradation of gelatin. Accordingly, Met-deficient LC failed to efficiently cross the extracellular matrix (ECM) rich basement membrane between epidermis and dermis. We further observed that Met-signaling by HGF reduced adhesion of bone marrow-derived LC to various ECM factors and enhanced the motility of Met-signaling competent DC in a 3D collagen matrix, which was not the case for Met-deficient LC/DC. We found no impact of Met-signaling on the integrin-independent amoeboid migration of DC in response to the CCR7 chemokine CCL19. Collectively, our data show that the Met-signaling pathway regulates the migratory properties of DC in HGF-dependent and HGF-independent manners.

cell biology↗

bioRxiv2020

The Janus-faced role of KDM5B heterogeneity in melanoma: differentiation as a situational driver of both growth arrest and drug-resistance

Melanoma is a highly plastic tumor characterized by dynamic interconversion of different cell identities depending on the biological context. For example, melanoma cells with high expression of the H3K4 demethylase KDM5B (JARID1B) rest in a slow-cycling, yet reversible persister state. Over time, KDM5Bhigh cells can promote rapid tumor repopulation with equilibrated KDM5B expression heterogeneity. The cellular identity of KDM5Bhigh persister cells has not been studied so far, missing an important cell state-directed treatment opportunity in melanoma. Here, we have established a doxycycline-titratable system for genetic induction of permanent intratumor expression of KDM5B and screened for chemical agents that phenocopy this effect. Transcriptional profiling and cell functional assays confirmed that the dihydropyridine phenoxyethyl 4-(2-fluorophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxylate (termed Cpd1) supports high KDM5B expression and directs melanoma cells towards differentiation along the melanocytic lineage and to cell cycle-arrest. The high KDM5B state additionally prevents cell proliferation through negative regulation of cytokinetic abscission. Moreover, treatment with Cpd1 promoted the expression of the melanocyte-specific tyrosinase gene specifically sensitizing melanoma cells for the tyrosinase-processed antifolate prodrug 3-O-(3,4,5-trimethoxybenzoyl)-(-)-epicatechin (TMECG). In summary, our study provides proof-of-concept for a new dual hit strategy in melanoma, in which persister state-directed transitioning limits tumor growth and plasticity and primes melanoma cells towards lineage-specific elimination.

cancer biology↗

bioRxiv2020

LSP1-myosin1e bi-molecular complex regulates focal adhesion dynamics and cell migration

Several cytoskeleton-associated proteins and signalling pathways work in concert to regulate actin cytoskeleton remodelling, cell adhesion and migration. We have recently demonstrated that the bi-molecular complex between the leukocyte-specific protein 1 (LSP1) and myosin1e controls actin cytoskeleton remodelling during phagocytosis. In this study, we show that LSP1 down regulation severely impairs cell migration, lamellipodia formation and focal adhesion dynamics in macrophages. Inhibition of the interaction between LSP1 and myosin1e also impairs these processes resulting in poorly motile cells, which are characterised by few and small lamellipodia. Furthermore, cells in which LSP1-myosin1e interaction is inhibited are typically associated with inefficient focal adhesion turnover. Collectively, our findings show that the LSP1-myosin1e bimolecular complex plays a pivotal role in the regulation of actin cytoskeleton remodelling and focal adhesion dynamics required for cell migration.

cell biology↗