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 eye tumor 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 using fluorescence in situ hybridization. 450 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 was 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 the radio-resistant bacteria Deinococcus was associated with smaller and earlier tumor stages, while Pseudomonas and Stenotrophomonas were associated with later metastasis.

Conclusion

An endogenous microbiome might exist in UM tissues and was associated with UM features and treatment. Whether the tumor-residing microbiome has a role in UM development and metastasis is worth further investigation.