缬草酸通过激活Nrf2通路抑制胃癌生长及炎症反应的实验研究

Valeric acid inhibits gastric cancer growth and inflammatory response by activating the nrf2 pathway: an experimental study

摘要:

背景与目的 缬草酸是一种核因子E2相关因子2（Nrf2）通路的激活剂，近年来研究显示其在乳腺癌、口腔癌等领域具有良好的抗肿瘤活性。然而，缬草酸在胃癌治疗中的作用尚不明确。本研究旨在探讨缬草酸对胃癌移植瘤裸鼠炎症反应和生存情况的影响及其可能机制，期望为胃癌治疗提供新的思路。方法 将80只Balb/c裸鼠皮下注射人胃癌细胞MKN-45建立移植瘤裸鼠模型后，随机均分为对照组及低、中、高三个剂量组，分别每天腹腔注射生理盐水及10、20、40 mg/kg缬草酸，持续30 d。期间测定各组裸鼠肿瘤生长情况。末次给药12 h后，每组取5只裸鼠，颈椎脱臼处死，摘除眼球取血，同时收集移植瘤称重。随后，采用HE染色观察移植瘤的组织病理学情况；ELISA检测血清炎症因子巨噬细胞炎症蛋白2（MIP-2）、白细胞介素10（IL-10）、肿瘤坏死因子α（TNF-α）水平；qRT-PCR及Western blot检测移植瘤组织中Nrf2及Nrf2通路相关分子醌氧化还原酶-1（NQO-1）、血红素氧合酶-1（HO-1）mRNA及蛋白表达。每组各剩余的15只裸鼠继续喂养，观察生存情况。结果 与对照组比较，各缬草酸治疗组在各个观察时间点的肿瘤体积及最终的肿瘤质量均明显减少（均P<0.05），且呈一定的剂量依赖趋势。HE染色结果显示，对照组裸鼠移植瘤中的肿瘤细胞排列紧密，肿瘤细胞密度高，各缬草酸治疗组移植瘤组织均有不同程度坏死，肿瘤细胞密度降低，且高剂量组最为明显。ELISA结果显示，各缬草酸治疗组血清MIP-2、TNF-α水平均明显降低，IL-10水平均明显升高（均P<0.05），且呈一定的剂量依赖性。qRT-PCR与Western blot结果显示，与对照组比较，各缬草酸治疗组移植瘤中Nrf2、HO-1、NQO-1 mRNA与蛋白表达水平均明显升高（均P<0.05），且呈一定的剂量依赖性。生存分析显示，对照组及低、中、高三个剂量缬草酸治疗组裸鼠的中位生存时间依次为47 d、68 d、81 d、90 d，各缬草酸给药组裸鼠中位生存期均大于对照组（均P<0.05）。结论 缬草酸能够有效抑制胃癌移植瘤的生长，减轻系统性炎症反应，延长裸鼠生存期，其机制可能与激活Nrf2通路、调节肿瘤微环境相关。

Abstract:

Background and Aims Valeric acid activates the nuclear factor E2-related factor 2 (Nrf2) pathway. Recent studies have demonstrated its potent antitumor activity in breast and oral cancers. However, its role in gastric cancer treatment remains unclear. This study aimed to investigate the effects of valeric acid on inflammatory responses and survival in a gastric cancer xenograft model in nude mice and to explore the potential underlying mechanisms to provide new insights for gastric cancer therapy.Methods A xenograft model was established by subcutaneous injection of human gastric cancer MKN-45 cells into 80 Balb/c nude mice, which were then equally randomized into four groups: control and low-, medium-, and high-dose valeric acid groups (10, 20, and 40 mg/kg, respectively). The mice received daily intraperitoneal injections of either saline or valeric acid for 30 days. Tumor growth was monitored during the treatment period. Twelve hours after the final administration, five mice from each group were sacrificed by cervical dislocation; blood was collected via eyeball removal, and tumors were excised and weighed. Histopathological changes in the tumors were observed by HE staining. Serum levels of macrophage inflammatory protein-2 (MIP-2), interleukin-10 (IL-10), and tumor necrosis factor α (TNF-α) were measured by ELISA. mRNA and protein expression levels of Nrf2 and its downstream molecules, quinone oxidoreductase-1 (NQO-1) and heme oxygenase-1 (HO-1), were assessed in tumor tissues using qRT-PCR and Western blot. The remaining 15 mice per group were monitored for survival analysis.Results Compared with the control group, all valeric acid-treated groups showed a significant reduction in tumor volumes at all observation time points and final tumor weight (all P<0.05), with a dose-dependent trend. HE staining revealed densely arranged tumor cells with high cell density in the control group, while various degrees of tumor necrosis and reduced cell density were observed in valeric acid-treated groups, most pronounced in the high-dose group. ELISA results showed that serum levels of MIP-2 and TNF-α were significantly decreased, while IL-10 levels were significantly increased in valeric acid-treated groups compared to controls (all P<0.05), exhibiting dose dependence. qRT-PCR and Western blot analyses demonstrated that the mRNA and protein expression levels of Nrf2, HO-1, and NQO-1 in tumors were significantly elevated in the valeric acid groups compared with the control group (all P<0.05), also showing dose dependence. Survival analysis indicated that the median survival times were 47 d (control), 68 d (low dose), 81 d (medium dose), and 90 d (high dose), with all valeric acid groups having significantly prolonged survival compared to the control group (all P<0.05).Conclusion Valeric acid effectively inhibits the growth of gastric cancer xenografts, attenuates systemic inflammatory responses, and prolongs the survival of nude mice, possibly through activation of the Nrf2 pathway and modulation of the tumor microenvironment.