The cell communication via extra-cellular vesicles after radiation therapy: perspectives on triple-negative breast cancer

Full text: Introduction: Breast cancer is among the neoplasms with the highest incidence and prevalence on a global scale, affecting mainly women. This heterogeneous disease encompasses a diversity of subtypes, whose biological characteristics and responses to therapeutic approaches are varied. Among the subtypes of breast cancer, triple-negative breast cancer (TNBC) stands out, differentiated by the absence of estrogen, progesterone, and HER2 receptors which difficult the application of targeted approaches, making it a more aggressive tumor. Radiotherapy (RT), in turn, has been widely used as an adjuvant treatment, but the mechanisms of resistance to radiotherapy seen in TNBC are not yet well elucidated. In this context, techniques used in the study of cell biology can promote a greater understanding of this intrinsic resistance. Here we hypothesize that TNBC increases the release of extracellular vesicles as a mechanism to respond to stress generated by RT. Objective: To detect variations in markers of cellular communication, extracellular vesicle production, and cellular stress in MDA-MB-231 cells due to irradiation. Methods: MDA-MB-231 cells were irradiated with 5 Gy and, 48 hours after the intervention, CD63, HSP70, and PD-L1 markers were explored by western blotting. Additionally, the expression and cellular distribution of CD63, a canonical EV-marker, was achieved by immunofluorescence under a confocal microscope. Results: WB did not show differences of the markers, which could be related to experimental details. There was a difference between the non-irradiated group and the treated group regarding the intensity of CD63. Cell morphology has also been altered and we have been looking for a relationship between this alteration and radioresistance. Conclusion: The increase in the fluorescence signal of CD63 labeling suggests an increase in the production of vesicles caused by the treatment with radiotherapy, in addition to the morphological alteration of the cell line studied. Despite the preliminary phase of our studies, we believe the results are a clue for the investigations of EVs pathways as possible mechanisms for TNBC resistance to RT. (author)