PT - JOURNAL ARTICLE AU - Panpan Ma AU - Xinxin Jin AU - Zhiwei Fan AU - Zhou Wang AU - Suhui Yue AU - Changyue Wu AU - Shiyin Chen AU - Yuanyuan Wu AU - Miaomiao Chen AU - Donghua Gu AU - Siliang Zhang AU - Renfang Mao AU - Yihui Fan TI - Super-enhancer receives signals from the extracellular matrix to induce PD-L1-mediated immune evasion <em>via</em> integrin/BRAF/TAK1/ERK/ETV4 signaling AID - 10.20892/j.issn.2095-3941.2021.0137 DP - 2022 May 15 TA - Cancer Biology &amp; Medicine PG - 669--684 VI - 19 IP - 5 4099 - http://www.cancerbiomed.org/content/19/5/669.short 4100 - http://www.cancerbiomed.org/content/19/5/669.full SO - Cancer Biology &amp; Medicine2022 May 15; 19 AB - Objective: PD-L1 and PD-L2 expression levels determine immune evasion and the therapeutic efficacy of immune checkpoint blockade. The factors that drive inducible PD-L1 expression have been extensively studied, but mechanisms that result in constitutive PD-L1 expression in cancer cells are largely unknown.Methods: DNA elements were deleted in cells by CRISPR/Cas9-mediated knockout. Protein function was inhibited by chemical inhibitors. Protein levels were examined by Western blot, mRNA levels were examined by real-time RT-PCR, and surface protein expression was determined by cellular immunofluorescence and flow cytometry. Immune evasion was examined by in vitro T cell-mediated killing.Results: We determined the core regions (chr9: 5, 496, 378–5, 499, 663) of a previously identified PD-L1L2-super-enhancer (SE). Through systematic analysis, we found that the E26 transformation-specific (ETS) variant transcription factor (ETV4) bound to this core DNA region but not to DNA surrounding PD-L1L2SE. Genetic knockout of ETV4 dramatically reduced the expressions of both PD-L1 and PD-L2. ETV4 transcription was dependent on ERK activation, and BRAF/TAK1-induced ERK activation was dependent on extracellular signaling from αvβ3 integrin, which profoundly affected ETV4 transcription and PD-L1/L2 expression. Genetic silencing or pharmacological inhibition of components of the PD-L1L2-SE-associated pathway rendered cancer cells susceptible to T cell-mediated killing.Conclusions: We identified a pathway originating from the extracellular matrix that signaled via integrin/BRAF/TAK1/ERK/ETV4 to PD-L1L2-SE to induce PD-L1-mediated immune evasion. These results provided new insights into PD-L1L2-SE activation and pathways associated with immune checkpoint regulation in cancer.