Study on the mechanism of herb cake-partitioned moxibustion inhibiting tumor growth in colitis-associated colorectal cancer based on KDM4D receptor

Objective To explore the inhibitory mechanism of herb cake-partitioned moxibustion on tumor growth in colitis-associated colorectal cancer (CAC) based on histone lysine demethylase 4D (KDM4D). Methods Inbred male Sprague-Dawley rats were randomly divided into a normal group, a CAC group, a herb cake-partitioned moxibustion group, and an inhibitor group. Except the normal group, rats in the other three groups were treated with azoxymethane (AOM) combined with dextran sulfate sodium (DSS) to make CAC rat models. Rats in the normal group and the CAC group did not receive interventions; rats in the herb cake-partitioned moxibustion group received moxibustion at Qihai (CV6) and bilateral Tianshu (ST25), 2 cones for one point each time, once a day for 30 d with 1-day rest every week; rats in the inhibitor group received intraperitoneal injection of KDM4D inhibitor, 5-chloro-8-hydroxyquinoline (5-c-8HQ), once a day for 30 d. After intervention, the general condition, colon length, tumor number and volume, and histopathological colon changes were observed. The expression of adenomatous polyposis coli (APC), axis inhibitor (Axin), cyclin D1, matrix metalloproteinase (MMP)-7 and MMP-9 mRNAs were detected by real-time quantitative polymerase chain reaction. The proliferating cell nuclear antigen (PCNA), cleaved caspase3, KDM4D, APC, and Axin proteins were detected by immunohistochemistry. Results Compared with the normal group, the general condition was poor, the colon length was significantly shortened ( P <0.01), the number and volume of colonic tumors were increased ( P <0.01), the structure of glandular duct was obviously disordered with “back-to-back” and cowall phenomenon, and also high-grade adenocarcinoma formed; the protein expression levels of PCNA and KDM4D were significantly increased ( P <0.01), while cleaved caspase3, APC, and Axin were significantly reduced ( P <0.01); the mRNA expression levels of cyclin D1, MMP-7, and MMP-9 were significantly increased ( P <0.01), while APC and Axin were significantly reduced ( P <0.01) in the CAC group. Compared with the CAC group, the general condition was improved, the length of colon was significantly increased ( P <0.01), the number and volume of the colonic tumors were reduced ( P <0.05), and the colon tissues showed epithelial cell proliferation with enlarged and deep staining nuclei, dysplasia and inflammatory cell infiltration; the protein expression levels of PCNA and KDM4D were significantly reduced ( P <0.01), while the cleaved caspase3, APC, and Axin were significantly increased ( P <0.01); the mRNA expression levels of cyclin D1, MMP-7, and MMP-9 were reduced ( P <0.05), while the APC and Axin were increased ( P <0.05) in the colon tissues of rats in the herb cake-partitioned moxibustion group and the inhibitor group. Conclusion Herb cake-partitioned moxibustion regulated abnormally expressed KDM4D in CAC rats, activated APC and Axin, the upstream molecules of Wnt/β-catenin pathway, inhibited abnormally activated downstream molecules of Wnt/β-catenin pathway. This may be a key mechanism of herb cake-partitioned moxibustion in inhibiting CAC tumor growth.