Nrf2 基因敲除会削弱抗氧化应激通路,从而增强 Apc(min/+) 小鼠的肠道肿瘤发生,同时也会增强炎症反应。

Nrf2 knockout enhances intestinal tumorigenesis in Apc(min/+) mice due to attenuation of anti-oxidative stress pathway while potentiates inflammation.

机构信息

Graduate Program in Pharmaceutical Science, Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey; Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey; Center for Cancer Prevention Research, Rutgers, The State University of New Jersey, Piscataway, New Jersey.

出版信息

Mol Carcinog. 2014 Jan;53(1):77-84. doi: 10.1002/mc.21950. Epub 2012 Aug 21.

Abstract

Mutations in adenomatous polyposis coli (APC) gene are found in more than 80% of colorectal cancer (CRC) patients. The nuclear transcription factor Nrf2 plays a central role in the regulation of oxidative stress and inflammation. Previously, we have shown that chronic inflammation in Nrf2(-/-) (Nrf2 knockout; KO) mice resulted in higher expression of inflammatory markers and cytokines, coupled with higher inflammatory damage to the colonic crypt cells, as compared to the Nrf2(+/+) (wild type; WT) mice. Induction of mutation in the colon by administration of carcinogen, AOM prior to DSS-induced inflammation resulted in higher tumor incidence and numbers in Nrf2KO mice. These results indicate that Nrf2-dependent inhibition of inflammation appears to be critical in inhibiting mutation-initiated colorectal carcinogenesis. In this study, we aim to investigate if loss of Nrf2 would dose-dependently promote intestinal tumorigenesis in Apc(min/+) mice. To demonstrate the in vivo mechanisms, we constructed both Apc mutated and Nrf2 deficient strain Apc(min/+) mice with C57BL/6 Nrf2KO mice to obtain F1, Apc(min/+) ;Nrf2(+/-) and F2, Apc(min/+) ;Nrf2(-/-) mice. Nrf2KO decreased the protein expression of antioxidant enzyme NQO1 in Apc(min/+) . In contrast, Nrf2KO enhanced the expression of inflammatory markers such as COX-2, cPLA, LTB4 in Apc(min/+) . Finally, Nrf2KO resulted in higher level of PCNA and c-Myc expression in intestinal tissue, indicating the deficiency of Nrf2 promotes proliferation of intestinal crypt cells in Apc(min/+) . Taken together, our results suggest that Nrf2KO attenuates anti-oxidative stress pathway, induces inflammation, and increases proliferative potential in the intestinal crypts leading to enhanced intestinal carcinogenesis and adenomas in Apc(min/+) .

摘要

腺瘤性结肠息肉病(APC)基因突变存在于超过 80%的结直肠癌(CRC)患者中。核转录因子 Nrf2 在氧化应激和炎症的调节中发挥核心作用。先前,我们已经表明,Nrf2(-/-)(Nrf2 敲除;KO)小鼠的慢性炎症导致炎症标志物和细胞因子的表达更高,同时伴有结肠隐窝细胞的炎症损伤更高,与 Nrf2(+/+)(野生型;WT)小鼠相比。在用致癌剂 AOM 诱导炎症之前,在结肠中诱导突变会导致 Nrf2KO 小鼠的肿瘤发生率和数量更高。这些结果表明,Nrf2 依赖性抑制炎症似乎对于抑制突变引发的结直肠癌发生至关重要。在这项研究中,我们旨在研究 Nrf2 缺失是否会以剂量依赖的方式促进 Apc(min/+) 小鼠的肠道肿瘤发生。为了证明体内机制,我们构建了 Apc 突变和 Nrf2 缺失的 Apc(min/+) 小鼠与 C57BL/6 Nrf2KO 小鼠,以获得 F1,Apc(min/+);Nrf2(+/-)和 F2,Apc(min/+);Nrf2(-/-) 小鼠。Nrf2KO 降低了 Apc(min/+) 中的抗氧化酶 NQO1 的蛋白表达。相反,Nrf2KO 增强了 Apc(min/+) 中的炎症标志物的表达,如 COX-2、cPLA、LTB4。最后,Nrf2KO 导致肠道组织中 PCNA 和 c-Myc 表达水平更高,表明 Nrf2 的缺乏促进了 Apc(min/+) 中肠隐窝细胞的增殖。总之,我们的结果表明,Nrf2KO 减弱了抗氧化应激途径,诱导了炎症,并增加了肠隐窝中的增殖潜力,从而增强了 Apc(min/+) 中的肠道癌发生和腺瘤形成。

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