GNAI1 and GNAI3 Reduce Colitis-Associated Tumorigenesis in Mice by Blocking IL6 Signaling and Down-regulating Expression of GNAI2.

BACKGROUND & AIMS: Interleukin 6 (IL6) and tumor necrosis factor contribute to the development of colitis-associated cancer (CAC). We investigated these signaling pathways and the involvement of G protein subunit alpha i1 (GNAI1), GNAI2, and GNAI3 in the development of CAC in mice and humans. METHODS: B6;129 wild-type (control) or mice with disruption of Gnai1, Gnai2, and/or Gnai3 or conditional disruption of Gnai2 in CD11c+ or epithelial cells were given dextran sulfate sodium (DSS) to induce colitis followed by azoxymethane (AOM) to induce carcinogenesis; some mice were given an antibody against IL6. Feces were collected from mice, and the compositions of microbiomes were analyzed by polymerase chain reactions. Dendritic cells (DCs) and myeloid-derived suppressor cells (MDSCs) isolated from spleen and colon tissues were analyzed by flow cytometry. We performed immunoprecipitation and immunoblot analyses of colon tumor tissues, MDSCs, and mouse embryonic fibroblasts to study the expression levels of GNAI1, GNAI2, and GNAI3 and the interactions of GNAI1 and GNAI3 with proteins in the IL6 signaling pathway. We analyzed the expression of Gnai2 messenger RNA by CD11c+ cells in the colonic lamina propria by PrimeFlow, expression of IL6 in DCs by flow cytometry, and secretion of cytokines in sera and colon tissues by enzyme-linked immunosorbent assay. We obtained colon tumor and matched nontumor tissues from 83 patients with colorectal cancer having surgery in China and 35 patients with CAC in the United States. Mouse and human colon tissues were analyzed by histology, immunoblot, immunohistochemistry, and/or RNA-sequencing analyses. RESULTS: GNAI1 and GNAI3 (GNAI1;3) double-knockout (DKO) mice developed more severe colitis after administration of DSS and significantly more colonic tumors than control mice after administration of AOM plus DSS. Development of increased tumors in DKO mice was not associated with changes in fecal microbiomes but was associated with activation of nuclear factor (NF) κB and signal transducer and activator of transcription (STAT) 3; increased levels of GNAI2, nitric oxide synthase 2, and IL6; increased numbers of CD4+ DCs and MDSCs; and decreased numbers of CD8+ DCs. IL6 was mainly produced by CD4+/CD11b+, but not CD8+, DCs in DKO mice. Injection of DKO mice with a blocking antibody against IL6 reduced the expansion of MDSCs and the number of tumors that developed after CAC induction. Incubation of MDSCs or mouse embryonic fibroblasts with IL6 induced activation of either NF-κB by a JAK2-TRAF6-TAK1-CHUK/IKKB signaling pathway or STAT3 by JAK2. This activation resulted in expression of GNAI2, IL6 signal transducer (IL6ST, also called GP130) and nitric oxide synthase 2, and expansion of MDSCs; the expression levels of these proteins and expansion of MDSCs were further increased by the absence of GNAI1;3 in cells and mice. Conditional disruption of Gnai2 in CD11c+ cells of DKO mice prevented activation of NF-κB and STAT3 and changes in numbers of DCs and MDSCs. Colon tumor tissues from patients with CAC had reduced levels of GNAI1 and GNAI3 and increased levels of GNAI2 compared with normal tissues. Further analysis of a public human colorectal tumor DNA microarray database (GSE39582) showed that low Gani1 and Gnai3 messenger RNA expression and high Gnai2 messenger RNA expression were significantly associated with decreased relapse-free survival. CONCLUSIONS: GNAI1;3 suppresses DSS-plus-AOM-induced colon tumor development in mice, whereas expression of GNAI2 in CD11c+ cells and IL6 in CD4+/CD11b+ DCs appears to promote these effects. Strategies to induce GNAI1;3, or block GNAI2 and IL6, might be developed for the prevention or therapy of CAC in patients.

Jinwei Tang modulates HDAC2 expression in a rat model of COPD.

The aim of the present study was to investigate the effect of a Traditional Chinese Herbal Medicine (TCHM), named Jinwei Tang on histone deacetylase 2 (HDAC2) and its role in the regulation of corticosteroid resistance in a rat model of chronic obstructive pulmonary disease (COPD). Male Wistar rats were divided into five groups (each n=10): COPD group, established by the intratracheal instillation of lipopolysaccharide and passive smoke exposure, and control, budesonide, theophylline + budesonide and Jinwei Tang + budesonide groups. Lung function was measured, lung tissue histopathology was examined and HDAC2 expression in the lung was assessed by immunohistochemistry. In addition, protein levels of interleukin-8 (IL-8), tumor necrosis factor (TNF)-α and HDAC2 in lung homogenate were quantified by ELISA. The rat COPD model exhibited alterations of the ratio of forced expiratory volume in 0.2 sec (FEV0.2) to the forced vital capacity, FEV0.2, dynamic compliance and airway resistance. HDAC2 expression was markedly reduced in the lung tissue of the COPD group compared with the control group, and treatment with Jinwei Tang + budesonide or theophylline + budesonide resulted in significant attenuation of the reduction of HDAC2 expression in the lungs (P<0.05). However, treatment with budesonide alone did not significantly alter HDAC2 expression. In the Jinwei Tang + budesonide and theophylline + budesonide groups, IL-8 and TNF-α expression was significantly decreased (P<0.05) and the HDAC2 level increased (P<0.05) compared with that in the COPD group. In conclusion, Jinwei Tang modulates airway inflammation and may enhance the anti-inflammatory effect of glucocorticoid through the upregulation of HADC2 expression in a rat model of COPD.