Browsing by Author "Miranda, Micaella"
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- Adherens Junction Integrity Is a Critical Determinant of Sodium Iodide Symporter Residency at the Plasma Membrane of Thyroid CellsPublication . Faria, Márcia; Vareda, José; Miranda, Micaella; Bugalho, Maria João; Silva, Ana Luísa; Matos, PauloWhile most cases of differentiated thyroid carcinoma (DTC) are associated with a good prognosis, a significant number progress to advanced disease exhibiting aggressive clinical characteristics and often becoming refractory to radioactive iodine (RAI) treatment, the current gold-standard therapeutic option for metastatic disease. RAI-refractoriness is caused by defective functional expression of the sodium-iodide symporter (NIS), which is responsible for the active transport of iodide across the plasma membrane (PM) into thyroid follicles. NIS deficiency in these tumors often reflects a transcriptional impairment, but also its defective targeting and retention at the cells’ PM. Using proteomics, we previously characterized an intracellular signaling pathway derived from SRC kinase that acts through the small GTPase RAC1 to recruit and bind the actin-anchoring adaptor EZRIN to NIS, regulating its retention at the PM of both non-transformed and cancer thyroid cells. Here, we describe how by reanalyzing the proteomics data, we identified cell–cell adhesion as the molecular event upstream the pathway involved in the anchoring and retention at the PM. We show that by interacting with NIS at the PM, adherens junction (AJ)-associated P120-catenin recruits and is phosphorylated by SRC, allowing it to recruit RAC1 to the complex. This enables SRC-phosphorylated VAV2 exchange factor to activate RAC1 GTPase, inducing NIS retention at the PM, thus increasing its abundance and function at the surface of thyroid cells. Our findings indicate that the loss of epithelial cell–cell adhesion may contribute to RAI refractoriness, indicating that in addition to stimulating NIS expression, successful resensitization therapies might require the employment of agents that improve cell–cell adhesion and NIS PM retention in refractory TC cells.
- CCL2 expression predicts clinical outcomes and regulates E-cadherin and angiogenesis in pituitary tumoursPublication . Silva, Ana Luísa; Barry, Sayka; Lopes-Pinto, Mariana; Joaquim, Rita; Miranda, Catarina; Reis, Fábio; Miranda, Micaella; Matos, Paulo; Suleyman, Oniz; Oliveira, Tiago; López-Presa, Dolores; Borrecho, Gonçalo; Tortosa, Francisco; Faria, Claúdia C.; Korbonits, Márta; Marques, PedroThe crosstalk between tumour cells and microenvironment components in pituitary neuroendocrine tumours (PitNETs), including chemokines, may impact tumour behaviour and clinical outcomes. CCL2 was previously identified as a key chemokine in PitNETs, but its role remains unknown. We aimed to study the role of CCL2 in defining the phenotype and clinical outcomes of PitNETs and in regulating macrophage chemotaxis, epithelial-to-mesenchymal transition (EMT) and angiogenesis. We studied CCL2 and E-cadherin expression, macrophages (CD68 and CD163) and vessels (CD31) in samples from 86 PitNET patients. Higher CCL2 mRNA expression was found in patients who required multimodal and multiple treatments and had active disease at the last follow-up. Higher CCL2 immunoreactivity was observed in patients with larger PitNETs. Among somatotroph tumours, CCL2 mRNA expression correlated with serum IGF-1 at the last follow-up. CCL2 mRNA expression levels correlated negatively with CDH1 expression and with E-cadherin complete membranous staining. In vitro, CCL2 downregulated E-cadherin expression in GH3 cells but did not affect cell morphology or migration. CCL2 expression correlated with the number of vessels, vessel perimeter and vessel area in PitNETs but not with PitNET-infiltrating macrophages. Our data suggest that CCL2 may lead to (or is at least a predictive marker of) poorer clinical outcomes and more difficult-to-treat PitNETs, potentially through its regulatory effects on different tumour-related mechanisms beyond immune cell chemotaxis, including in the activation of the EMT pathway and modulation of angiogenesis in PitNETs. Further studies are needed to corroborate our findings and to validate CCL2 as a potential predictive marker and therapeutic target in PitNETs.