Targeting pyroptosis reverses KIAA1199-mediated immunotherapy resistance in colorectal cancer ============================================================================================= * Lisha Li * Lei Zhao * Diwei Zhou * Yuanhang Yu * Peiyi Zhang * Jinge Zheng * Zhenyu Lin * Dandan Yu * Jinghua Ren * Jing Zhang * Pengfei Zhou * Dejun Zhang * Tao Zhang ## Abstract **Background** Despite advancements in treatment modalities, several patients with colorectal cancer (CRC) remain unresponsive to immune checkpoint inhibitor therapy. Pyroptosis, an inflammatory programmed cell death process, holds substantial promise for tumor immunotherapy. In this study, we explored the use of pyroptosis to overcome immunotherapy resistance in CRC. **Methods** We used a pyroptosis-related gene panel to construct an immunotherapy efficacy evaluation model and validated its performance by immunohistochemical staining of CRC patient samples. Pyroptosis and its underlying mechanisms were examined both in vitro and in vivo using PCR, western blotting, lactate dehydrogenase release assay, ELISA, co-immunoprecipitation, immunohistochemistry, fluorescence cell assays, microscopic imaging, flow cytometry analysis and bioinformatics approaches. **Results** We established a model to define high or low levels of pyroptosis in CRC, revealed that low pyroptosis led to immunotherapy resistance, and identified KIAA1199 as a characteristic protein of low pyroptosis CRC. We further demonstrated that KIAA1199 contributes to low pyroptosis, resulting in resistance to immunotherapy. Mechanistically, KIAA1199 bound to and stabilized DNA methyltransferase-1 (DNMT1), thereby inhibiting GSDME-mediated pyroptosis. Importantly, our study highlighted that decitabine reversed KIAA1199-mediated immunotherapy resistance by enhancing pyroptosis to restore IL-1B release and CD8+ T cell infiltration. **Conclusions** We found a critical role of KIAA1199 in promoting immunotherapy resistance by suppressing pyroptosis via the DNMT1/GSDME pathway in CRC. Decitabine has emerged as a promising therapeutic agent for reversing KIAA1199-mediated immunotherapy resistance by enhancing pyroptosis. Our findings provide valuable insights for enhancing the efficacy of immunotherapy in patients with CRC who exhibit resistance to conventional immunotherapy approaches. * Colorectal Cancer * Biomarker * Combination therapy * Immune Checkpoint Inhibitor * T cell * Pyroptosis * Decitabine #### WHAT IS ALREADY KNOWN ON THIS TOPIC * Several patients with colorectal cancer (CRC) remain unresponsive to immune checkpoint inhibitor (ICI) therapy. Pyroptosis, an inflammatory programmed cell death process, holds substantial promise for enhancing tumor immunity. However, its potential and specific mechanism for overcoming immunotherapy resistance in CRC has not been fully explored. #### WHAT THIS STUDY ADDS * KIAA1199 plays a critical role in promoting immunotherapy resistance by stabilizing DNMT1, which subsequently inhibits the expression and cleavage of GSDME and suppresses cell pyroptosis. #### HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY * We explored the clinical significance of pyroptosis-related genes and KIAA1199 as potential biomarkers for predicting immunotherapy responses and proposed a novel treatment strategy combining decitabine with ICIs to reverse KIAA1199-mediated immunotherapy resistance by enhancing pyroptosis. ## Background Colorectal cancer (CRC) is the third most prevalent cancer globally and the second leading cause of cancer-related mortality.1 Anti-programmed cell death-1 (PD-1) antibody has proven to be the first-line treatment for CRC with deficient mismatch repair, which occurs in approximately 4%–5% of patients.2–5 However, it is imperative to acknowledge that other patients, do not demonstrate substantial clinical benefits of immune checkpoint inhibitors (ICIs).6 Antitumor immune escape is a critical factor contributing to immunotherapy resistance; however, the underlying mechanisms remain elusive. Thus, exploring the regulatory mechanisms of immune evasion in CRC and identifying effective inhibitory targets and clinical strategies are crucial. This effort is key to improving immunotherapy outcomes and CRC patient prognosis. Pyroptosis, a well-studied form of programmed cell death (PCD), prominently implicates the gasdermin (GSDM) family that has been investigated across a spectrum of disease models, including autoimmune and inflammatory diseases, infectious diseases, deafness, and cancer.7 8 Following cleavage, GSDM liberates the GSDM-N domain, which induces the piercing of the cell membrane. This process results in discernible morphological alterations, including cytoplasmic swelling, membrane rupture, and discharge of inflammatory factors into the extracellular environment.9 10 Thus, pyroptosis surpasses its role as a cellular endpoint. The induction of pyroptosis in tumor cells leads to the release of cytokines, including interleukin (IL)-1β, IL-18, high mobility group box 1 protein (HMGB1), interferon-gamma (IFN-γ), granzyme (Gzm) -A/B/K, and Fas ligand (FasL).9 11 This process facilitates the recruitment of immune cells such as CD4+ T cells, CD8+ T cells, and natural killer (NK) cells into the tumor microenvironment, thereby orchestrating and amplifying the antitumor activity of the immune response. Wang *et al* have devised a bioorthogonal chemical system engineered to trigger GSDMA3-mediated pyroptosis in breast cancer cells. Pyroptosis-induced inflammation activates antitumor immunity and augments the therapeutic efficacy of anti-PD-1 treatment.12 Another study introduced a bionic nanoparticle loaded with indocyanine green and decitabine specifically designed to trigger pyroptosis in tumor cells and enhance the sensitivity of immunotherapy for solid tumors.13 In conclusion, the inflammatory response elicited by pyroptosis can activate antitumor immunity and augment immunotherapy sensitivity. Consequently, the extent of pyroptosis in tumor cells may serve as a predictor of the antitumor immune response and effectiveness of immunotherapy. KIAA1199 is also known as cell migration-inducing and hyaluronan-binding protein.14–20 Our previous research revealed increased expression levels of KIAA1199 in CRC tissues, correlating with invasion, metastasis, drug resistance, and poor prognosis in patients with CRC.21–24 Importantly, KIAA1199 acts as a pivotal suppressor in modulating the immune response and enabling CRC cells to evade immune surveillance.25 26 However, the molecular network underlying KIAA1199-mediated immunotherapy resistance in CRC remains poorly understood. In this study, we investigated the involvement of pyroptosis in regulating the response to immunotherapy and the underlying mechanisms in patients with CRC. Mechanistically, KIAA1199 promoted resistance to immunotherapy by inhibiting pyroptosis via the DNA methyltransferase-1 (DNMT1)/GSDME pathway. Additionally, we explored the clinical significance of KIAA1199 as a target in immunotherapy resistance and proposed a new therapeutic strategy involving the combination of decitabine and ICIs to reverse KIAA1199-mediated immunotherapy resistance by enhancing pyroptosis. ## Methods ### Cell culture and reagents MC38 cells were obtained from the American Type Culture Collection (Rockville, Maryland, USA). Human CRC cells (HCT116, SW480, and LOVO) and CT26 cells were procured from the Cell Bank, Type Culture Collection, Chinese Academy of Sciences (CBTCCCAS, Shanghai, China). These cells were cultured in DMEM (HCT116, MC38) or RPMI 1640 (SW480, LOVO, CT26) (GIBCO, Grand Island, New York, USA), supplemented with 10% fetal bovine serum (BI, Israel), 50 µg/mL gentamicin, 100 U/mL penicillin, and 0.1 mg/mL streptomycin. All human cell lines were authenticated using STR profiling within the last 3 years, and all experiments were performed with mycoplasma-free cells. ### Patients, tissue samples, and gene chips analysis Cancer tissue samples were obtained from patients with histopathologically confirmed CRC who were hospitalized at the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, from July 2020 to December 2022. None of the patients underwent adjuvant radiation treatment prior to surgery. The study protocol was thoroughly explained to the patients and written informed consent was obtained from each participant. ### Immunohistochemistry 42 paraffin-embedded CRC specimens were obtained from the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. Tumor samples were sectioned into 4 µm slices. Primary reactions were performed using anti-GSDMD, anti-caspase-1, anti-caspase-3, anti-NLRP3, anti-KIAA1199, anti-DNMT1, and anti-GSDME antibodies (Proteintech). This was followed by incubation with the secondary antibody and immunoperoxidase staining. The mean density of immunohistochemistry (IHC) staining was quantified using Image-Pro Plus 6.0, with scores of 0, 1, 2, and 3 assigned based on cell staining intensity and the percentage of positive cells. The scoring was based on the percentage of positive cells, classified into four levels: 1 point for 0%≤positive cells≤25%, 2 points for 25%