Integrin ß7 Inhibits Colorectal Cancer Pathogenesis via Maintaining Antitumor Immunity.

Immune cell infiltration is important for predicting the clinical outcomes of colorectal cancer. Integrin ß7 (ITGB7), which is expressed on the surface of leukocytes, plays an essential role in the homing of immune cells to gut-associated lymphoid tissue and facilitating the retention of lymphocytes in gut epithelium; however, its role in colorectal cancer pathogenesis is poorly explored. Here, we found that the number of ß7+ cells decreased significantly in tumor tissue compared with adjacent normal tissue. ß7 expression decreased in tumor-derived compared with normal tissue-derived CD8+ T cells. With bulk RNA expression data from public platforms, we demonstrated that higher ITGB7 expression correlated with longer patient survival, higher cytotoxic immune cell infiltration, lower somatic copy-number alterations, decreased mutation frequency of APC and TP53, and better response to immunotherapy. The possible cell-cell interactions mediated by ITGB7 and its ligands MAdCAM-1, VCAM-1, and CDH1 were investigated using public single-cell RNA sequencing data. ITGB7 deficiency led to exaggerated tumorigenesis and progression in both Apcmin /+ spontaneous and MC38 orthotopic models of colorectal cancer, which could be due to a reduced infiltration of activated CD8+ T cells, effector memory CD8+ T cells, IFNγ+ CD8+ T cells, IFNγ+ natural killer cells, CD103+ dendritic cells, and other immune cell subsets that are essential players in antitumor immunity. In conclusion, our data revealed that ITGB7 could inhibit the tumorigenesis and progression of colorectal cancer by maintaining antitumor immunity.

Isoflurane inhibits neutrophil recruitment in the cutaneous Arthus reaction model.

PURPOSE: Neutrophil recruitment to the inflammatory sites is regulated by a variety of adhesion molecules including ß2 integrins. The dependency of neutrophil recruitment on ß2 integrins is variable in different tissues, but has not yet been verified in the cutaneous passive reverse Arthus reaction. We examined this question and also evaluated the impact of isoflurane on neutrophil recruitment to the skin because we previously showed in vitro that isoflurane binds and inhibits ß2 integrins. METHODS: The dependency on ß2 integrins in neutrophil recruitment to the skin in the Arthus reaction was examined using αL, αM and ß2 knockout mice. Then, we evaluated the effect of isoflurane on neutrophil recruitment to the skin. In addition, the effects of isoflurane on neutrophil binding to intercellular adhesion molecule-1 (ICAM-1), one of the ß2 integrin ligands, were studied in vitro using cell adhesion assays. RESULTS: Neutrophil recruitment to the skin in the Arthus reaction model was totally dependent on ß2 integrins, as ß2 knockout mice completely abolished it. However, the defect of only one of the ß2 integrins was not sufficient to abolish neutrophil recruitment. Isoflurane reduced neutrophil recruitment to the skin by approximately 90 %. Also, isoflurane inhibited neutrophil adhesion to ß2 integrin ligand ICAM-1. CONCLUSIONS: We demonstrated that (1) neutrophil recruitment to the skin was totally dependent on ß2 integrins, and (2) isoflurane significantly impaired neutrophil recruitment. Based on the previous studies on the contribution of other adhesion molecules in neutrophil recruitment, it is likely that isoflurane at least partially affects on ß2 integrins in this model.

Maturation of dendritic cells depends on proteolytic cleavage by cathepsin X.

The maturation status of dendritic cells (DCs) is crucial for effective antigen presentation and initiation of the primary immune response. Maturation stimuli cause the adhesion of immature DCs to the extracellular matrix, which is accompanied by recruitment of the CD11b/CD18 [macrophage antigen-1 (Mac-1)] integrin receptor, cytoskeleton reorganization, and podosome formation. Cathepsin X, a cysteine protease expressed in DCs and other APCs, is involved in Mac-1 activation. We have shown that during maturation, cathepsin X translocates to the plasma membrane of maturing DCs, enabling Mac-1 activation and consequently, cell adhesion. In mature DCs, cathepsin X redistributes from the membrane to the perinuclear region, which coincides with the de-adhesion of DCs, formation of cell clusters, and acquisition of the mature phenotype. Inhibition of cathepsin X activity during DC differentiation and maturation resulted in an altered phenotype and function of mature DCs. It reduced surface expression of costimulatory molecules, increased expression of inhibitory Ig-like transcripts 3 and 4 (ILT3 and ILT4), almost completely abolished cytokine production, diminished migration, and reduced the capacity of DCs to stimulate T lymphocytes. These results stress the importance of cathepsin X in regulating DC adhesion, a crucial event for their maturation and T cell activation.

Expression and signaling activity of Wnt-5a/discoidin domain receptor-1 and Syk plays distinct but decisive roles in breast cancer patient survival.

PURPOSE: The loss of Wnt-5a, a G-protein-coupled receptor ligand, or Syk, an intracellular kinase, has in separate studies been associated with poor prognosis of breast cancer patients. Both proteins are involved in cell adhesion, a key event in epithelial cancer metastasis. Here, we have investigated whether Syk is part of the Wnt-5a/discoidin domain receptor-1 (DDR1) signaling pathway and if a signaling interaction of these proteins is important for breast cancer-specific survival. EXPERIMENTAL DESIGN: The signaling interactions between Wnt-5a/DDR1 and Syk were addressed in mammary cell lines. Their mRNA and protein levels and the respective clinical correlates were investigated in 94 cases of primary breast cancer. RESULTS: The expression of Wnt-5a and Syk correlated in four of five tumor cell lines. However, despite a constitutive association between Syk and the Wnt-5a-dependent adhesion receptor DDR1, we found no evidence of a Wnt-5a/DDR1-mediated activation of Syk. Instead, beta(1) integrins initiate the adhesion-induced activation of Syk. In tumors from breast cancer patients, the protein expression of Wnt-5a and Syk were differently regulated at the translational and transcriptional level, respectively. Analysis of breast cancer-specific survival revealed that the presence of Wnt-5a and Syk in primary tumors has good predictive value for a favorable outcome. Intriguingly, a simultaneous loss of both proteins did not reduce survival more than loss of either. CONCLUSIONS: Despite the difference in regulation of Wnt-5a and Syk protein expression and their lack of signaling interaction, our clinical data indicate that a favorable prognosis in breast cancer requires the expression and signaling activity of both.