Microbiome typing in uveal melanoma is associated with plaque radiotherapy

Background: Microbiomes have been identified in various tumor types and could affect tumor progression and treatment. As the most prevalent primary malignant eyetumor in adults, uveal melanoma (UM) has not been explored regarding its endogenous microbiome. Plaque radiotherapy (PRT) is the gold standard for the treatment of UM. Hereby, we recruited 71 UM patients, sequenced the 16S rRNA gene of their tumor tissues, and analyzed the association between UM microbiome and disease phenotypes.Results: Clear bacterial signals were observed in UM tissues by using in situ fluorescence hybridization. 523 bacterial species passed strict decontamination against 58 environmental control samples in 16S rRNA gene analysis, and these species formed three distinct types by unsupervised clustering. The UM microbiome types were significantly associated with PRT. A biomarker analysis showed that Pseudomonas and Sphingomonas were significantly enriched in the radiation group (RG) compared to the non-radiation group (NRG). A kind of radiation-resistant bacteria had a significantly higher positive rate in tumor tissues that underwent radiotherapy. We found that radioresistant bacteria Deinococcus was associated with larger tumor and later tumor stage, while Pedobacter, Bradyrhizobium, Variovorax, Pseudomonas and Stenotrophomonas were associated with later metastasis. Conclusion: There was an endogenous microbiome in UM tissues, and the distribution of microbiota was correlated with PRT and clinical features.