Modulation of immune infiltration profile and radiotherapy response in melanomas by miR-195-enriched extracellular vesicles

Abstract

Melanoma is considered the most aggressive form of skin cancer. Although recently approved treatments, including immunotherapy with immune checkpoint blockage, resulted in improved patient prognosis, resistance mechanisms still represent major obstacles. Immune infiltration profile within the tumor microenvironment is among the factors influencing tumor response, and a highly immunosuppressive environment, characterized by the presence of exhausted and pro-tumoral immune cells, is associated with poorer therapeutic response. Thus, modulation of immune infiltration profile aiming to restore anti-tumoral response, represent promising strategies for melanoma treatment. In this matter, the use of immune modulatory miRNAs has been showing encouraging results and their delivery by Extracellular Vesicles (EVs) has been studied as a new therapeutic approach. Recently we showed that EVs carrying miR-195 can transfer this miRNA do recipient cells inducing anti-proliferative effect and increasing their sensitivity to combined targeted therapy. Preliminary results showed that this miRNA can potentially act as immune modulator through the regulation of PD-1/PD-L1 immune checkpoint axis. Gene expression analysis by RT-qPCR showed that miR-195 overexpression is correlated with decreased PDL-1 expression. Additionally, according to TCGA data, the expression of this miRNA is positively correlated with the expression of immune cells markers in melanoma tumors, including lymphocytes (T and B), dendritic cells and natural killers. Moreover, in silico results showed that CD163, a pro-tumoral macrophage marker (M2) and VEGFA, a growth factor capable to induce immunosuppression, are predicted miR-195 targets, evincing its role as immunomodulator. Moreover, recent studies showed that PD-L1 can also regulate DNA damage response, inducing tumor resistance to radiotherapy and alkylating chemotherapy. In melanoma, radiotherapy is often used as adjuvant or palliative care and preliminary results showed an increased PD-L1 expression after radiotherapy treatment in murine melanoma cell line. Based on these facts, the aim of this project is to analyze the effect of EVs carrying miR-195 in the modulation of immune infiltration and radiotherapy response in melanoma pre-clinical model.