Glycolysis regulated exosomal LINC01214 inhibited CD8+ T cell function and induced anti-PD1 resistance in melanoma via modulating miR-4492/PPP1R11 axis

Background: Long non-coding RNAs (lncRNAs) can be incorporated into exosomes to mediate the intercellular communication, regulating the occurrence, development, and immunosuppression of cancers. T cell dysfunction has been a hallmark of many cancers, including melanoma, which enables Cancer cells escape from host immune surveillance. However, the molecular mechanism of exosome-transmitted lncRNAs in CD8⁺ T cell dysfunction in melanoma remains largely unclear.

Method: The expression of circulating LINC01214 (cirLINC01214) was detected by quantitative real-time polymerase chain reaction (RT-qPCR). Exosomes were isolation from the culture medium and plasma of melanoma patients via ultracentrifugation and characterized by transmission electronic microscopy. The regulation of exosomal LINC01214 on CD8⁺ T cell function was determined by ELISA. The molecular mechanism of exosomal LINC01214 in CD8⁺ T cells were assessed by the RNA immunoprecipitation and pull-down assay. A mouse model with reconstituted human immune system was used to explore the role of exosomal LINC01214 in the resistance to anti-PD1 therapy.

Results: LINC01214 was highly expressed in melanoma tissues compared with matched adjacent normal tissues. Increased levels of circulating LINC01214 (cirLINC01214) was observed in melanoma patient plasma and correlated with poor PD-1 immunotherapy response. The cirLINC01214 was predominantly released by melanoma cells in an exosome manner. Melanoma cell-derived exosomal LINC01214 inhibits the production of IFN-γ, TNF-α, Granzyme-B and Perforin by CD8⁺ T cells. Further mechanism study found that cirLINC01214 delivered by exosomes suppressed CD8⁺ T cell function by up-regulating the expression of Protein Phosphatase 1 Regulatory Inhibitor Subunit 11 (PPP1R11) through sponging miR-4492. CirLINC01214 conferred resistance to PD-1 immunotherapy in melanoma xenograft mouse model. Melanoma patients with poor prognosis after PD-1 treatment carried high levels of exosomal LINC01214. Additionally, the secretion of exosomal cirLINC01214 was enhanced by the Warburg effect, which was consistent with the reprogrammed glucose metabolism of melanoma.

Conclusions: Our results demonstrated that exosomal LINC01214 released by melanoma cells promoted immunotherapy resistance by inducing CD8⁺ T cell dysfunction via the miR-4492/PPP1R11 regulatory loop. Targeting cirLINC01214 might be a potential therapeutic strategy to enhance the outcome of immunotherapy in melanoma.

CD8+ T; Exosome; LINC01214; Melanoma; PD-1.