Mol Cancer Res. 2023 Oct 26.
Exosomal long noncoding RNAs (lncRNAs) derived from cancer cells are implicated in various processes, including cancer cell proliferation, metastasis, and immunomodulation. We investigated the role and underlying mechanism of exosome-transmitted lncRNA NEAT1 in the immune escape of multiple myeloma (MM) cells from natural killer (NK) cells. MM cells and samples from MM patients were obtained. The effects of MM cell-derived exosomes (MM exosomes) and exosomal NEAT1 on the functions of NK cells were evaluated using EdU staining, CCK-8, flow cytometry and ELISA. Chromatin and RNA immunoprecipitation were performed to identify interactions between NEAT1, enhancer of Zeste Homolog 2 (EZH2), and pre-B-cell leukemia transcription factor 1 (PBX1). A xenograft tumor model was constructed to verify the effects of exosomal NEAT1 on tumor growth. qRT-PCR, western blot and immunohistochemistry were conducted to detect related genes. NEAT1 levels were upregulated in MM tumor tissues, MM cells, and MM exosomes. MM exosomes suppressed cell proliferation, promoted apoptosis, reduced natural killer group 2, member D (NKG2D)-positive cells, and the production of tumor necrosis factor alpha (TNF-α) and interferon-gamma (IFN-γ) in NK cells, whereas NEAT1-silenced exosomes had little effect. NEAT1 silenced PBX1 by recruiting EZH2. PBX1 knockdown abrogated the effects of NEAT1-silenced exosomes on NK and MM cells. NEAT1-silenced exosomes inhibited tumor growth in mice, decreased Ki67 and PD-L1, and increased NKG2D, TNF-α, and IFN-γ in tumor tissues. In summary, MM cell-derived exosomal NEAT1 suppressed NK cell activity by downregulating PBX1, promoting MM cell immune escape. This study suggests a potential strategy for treating MM. Implications: This study reveals that exosomal NEAT1 regulates EZH2/PBX1 axis to inhibit NK cell activity, thereby promoting multiple myeloma cell immune escape, which offers a novel therapeutic potential for MM.