Analysis of the miRNA Profiles of Melanoma Exosomes Derived Under Normoxic and Hypoxic Culture Conditions

Background/Aim: MicroRNAs (miRNAs) transported in melanoma-derived exosomes function as intercellular messengers supporting tumor survival and progression. Hypoxia increases melanoma phenotypic plasticity, drug resistance, and metastasis. Materials and Methods: We determined the miRNA profiles in exosomes derived from melanoma cells grown under hypoxic and normoxic conditions by microarray analyses and reverse transcription-polymerase chain reaction (RT-PCR) in order to analyze the potential influence of vesicle-transported miRNAs on cancer-related pathways and transcriptional programs. Results: Despite phenotypical differences of the four cell lines used, their exosomes shared the majority of miRNAs. The levels of three miRNAs were higher in normoxic exosomes, whereas 15 miRNAs were significantly more abundant under hypoxic conditions. Pathway analysis pointed at several cellular processes contributing to proliferation, drug resistance, and modification of the tumor microenvironment, including immunosuppression. Conclusion: The miRNA-expression profiles of exosomes from patient-derived melanoma cells are modified by oxygen concentration and reflect the phenotypic changes of melanoma cells under different growth conditions.