Table_3_PDIA2 Bridges Endoplasmic Reticulum Stress and Metabolic Reprogramming During Malignant Transformation of Chronic Colitis.docx

BackgroundChronic inflammation contributes to approximately 20% of cancers; the underlying mechanisms are still elusive. Here, using an animal model of colitis to colon-cancerous transformation, we demonstrated that endoplasmic reticulum (ER) stress couples with metabolic reprogramming to promote a malignant transformation of chronic inflammation.MethodsThe animal model for chronic colitis to colon-cancerous transformation was established in C57BL/6N mice by azoxymethane (AOM) and dextran sodium sulfate (DSS) treatments. The differential proteins in control and AOM/DSS-treated colon mucosa were determined using proteomic analysis; the kinetics of metabolic modifications were monitored by mitochondrial oxygen flux, extracellular acidification, and targeted metabolomics; the molecule linker between ER stress and metabolic modifications were identified by coimmunoprecipitation, KEGG pathway analysis, and the subcutaneous tumor model using gene-specific knockdown colon cancer cells. Tissue array analysis were used to evaluate the differential protein in cancer and cancer-adjacent tissues.ResultsAOM/DSS treatment induced 38 tumors in 10 mice at the 14th week with the mean tumor size 9.35 ± 3.87 mm2, which was significantly decreased to 5.85 ± 0.95 mm2 by the ER stress inhibitor 4-phenylbutyric acid (4PBA). Seven differential proteins were determined from control (1,067 ± 48) and AOM/DSS-treated mucosa (1,077 ± 59); the level of ER protein PDIA2 (protein disulfide isomerase-associated 2) was increased over 7-fold in response to AOM/DSS treatment. PDIA2 interacted with 420 proteins that were involved in 8 signaling pathways, in particular with 53 proteins in metabolic pathways. PDIA2 translocated from ER to mitochondria and interacted with the components of complexes I and II to inhibit oxophosphorylation but increase glycolysis. Knockdown PDIA2 in colon cancer cells restored the metabolic imbalance and significantly repressed tumor growth in the xenograft animal model. 4PBA therapy inhibited the AOM/DSS-mediated overexpression of PDIA2 and metabolic modifications and suppressed colon cancer growth. In clinic, PDIA2 was overexpressed in colon cancer tissues rather than cancer-adjacent tissues and was related with the late stages and lymph node metastasis of colon cancer.ConclusionsPersistent ER stress reprograms the metabolism to promote the malignant transformation of chronic colitis; PDIA2 serves as a molecule linker between ER stress and metabolic reprogramming. The inhibition of ER stress restores metabolic homeostasis and attenuates the cancerous transformation of chronic inflammation.

背景：慢性炎症约导致20%的癌症发生，其潜在机制尚不明确。本研究采用结肠炎向结肠癌转化的动物模型，揭示了内质网应激与代谢重编程相互耦合，共同促进慢性炎症的恶性转化。方法：通过在C57BL/6N小鼠中应用偶氮甲烷（AOM）和葡聚糖硫酸钠（DSS）处理，建立了慢性结肠炎向结肠癌转化的动物模型。利用蛋白质组学分析确定了对照组与AOM/DSS处理组结肠黏膜中的差异蛋白；通过线粒体氧 flux、细胞外酸化和靶向代谢组学监测代谢改变的动力学；通过共免疫沉淀、KEGG通路分析和利用基因特异性敲低结肠癌细胞构建的皮下肿瘤模型，确定了内质网应激与代谢改变之间的分子连接。采用组织芯片分析评估了癌症及其相邻组织中的差异蛋白。结果：AOM/DSS处理在第14周诱导了10只小鼠中的38个肿瘤，平均肿瘤大小为9.35 ± 3.87 mm²，经内质网应激抑制剂4-苯基丁酸（4PBA）处理后显著降低至5.85 ± 0.95 mm²。从对照组（1,067 ± 48）和AOM/DSS处理组黏膜（1,077 ± 59）中确定了7个差异蛋白；响应于AOM/DSS处理，内质网蛋白PDIA2（蛋白二硫键异构酶相关蛋白2）的水平增加了7倍。PDIA2与420个蛋白质相互作用，涉及8个信号通路，特别是与代谢通路中的53个蛋白质相互作用。PDIA2从内质网转移至线粒体，并与复合物I和II的组分相互作用，抑制氧化磷酸化但增加糖酵解。在结肠癌细胞中敲低PDIA2恢复了代谢失衡，并在异种移植动物模型中显著抑制了肿瘤生长。4PBA治疗抑制了AOM/DSS介导的PDIA2过度表达和代谢改变，并抑制了结肠癌的生长。在临床上，PDIA2在结肠癌组织中而非癌旁组织中过表达，并与结肠癌的晚期阶段和淋巴结转移相关。结论：持续的ER应激重编程代谢以促进慢性结肠炎的恶性转化；PDIA2作为ER应激与代谢重编程之间的分子连接者。抑制ER应激恢复代谢稳态并减轻慢性炎症的癌变转化。