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The cancer-stromal interaction has been demonstrated to promote tumor progression, and cancer-associated fibroblasts (CAFs), which are the main components of stromal cells, have attracted attention as novel treatment targets. Chitinase 3-like 1 (CHI3L1) is a chitinase-like protein, which affects cell proliferation and angiogenesis. However, the mechanisms through which cells secrete CHI3L1 and through which CHI3L1 mediates tumor progression in the cancer microenvironment are still unclear. Accordingly, the present study assessed the secretion of CHI3L1 in the microenvironment of colorectal cancer and evaluated how CHI3L1 affects tumor angiogenesis. CAFs and normal fibroblasts (NFs) established from colorectal cancer tissue, and human colon cancer cell lines were evaluated using immunostaining, cytokine antibody array, RNA interference, reverse transcription-quantitative PCR (RT-qPCR), ELISA, western blotting and angiogenesis assays. The expression and secretion of CHI3L1 in CAFs were stronger than those in NFs and colorectal cancer cell lines. In addition, interleukin-13 receptor α2 (IL-13Rα2), a receptor for CHI3L1, was not expressed in colorectal cancer cell lines, but was expressed in fibroblasts, particularly CAFs. Furthermore, the expression and secretion of IL-8 in CAFs was stronger than that in NFs and cancer cell lines, and recombinant CHI3L1 addition increased IL-8 expression in CAFs, whereas knockdown of CHI3L1 suppressed IL-8 expression. Furthermore, IL-13Rα2 knockdown suppressed the enhancement of IL-8 expression induced by CHI3L1 treatment in CAFs. For vascular endothelial growth factor-A (VEGFA), similar results to IL-8 were observed in an ELISA for comparison of secretion between CAFs and NFs and for changes in secretion after CHI3L1 treatment in CAFs; however, no significant differences were observed for changes in expression after CHI3L1 treatment or IL-13Rα2 knockdown in CAFs assessed using RT-qPCR assays. Angiogenesis assays revealed that tube formation in vascular endothelial cells was suppressed by conditioned medium from CAFs with the addition of human CHI3L1 neutralizing antibodies compared with control IgG, and also suppressed by conditioned medium from CAFs transfected with CHI3L1, IL-8 or VEGFA small interfering RNA compared with negative control small interfering RNA. Overall, the present findings indicated that CHI3L1 secreted from CAFs acted on CAFs to increase the secretion of IL-8, thereby affecting tumor angiogenesis in colorectal cancer.

Cancer-associated fibroblasts (CAFs) are one of the major components of the cancer stroma in the tumor microenvironment. The interaction between cancer cells and CAFs (cancer-stromal interaction; CSI) promotes tumor progression, including metastasis. Recently, the tissue inhibitor of metalloproteinase-1 (TIMP-1) was reported to promote cancer cell migration and metastasis, which is contrary to its anticancer role as an inhibitor of matrix metalloproteinase. Moreover, CAF-derived TIMP-1 is reported to regulate CAF activity. In the present study, we investigated the effect of TIMP-1 on colon cancer cell migration in vitro. The TIMP-1 secretion levels from the CAFs and cancer cell lines were comparatively measured to determine the main source of TIMP-1. Furthermore, the effect of CSI on TIMP-1 secretion was investigated using the Transwell co-culture system. Cancer cell migration was evaluated using the wound-healing assay. The results demonstrated that TIMP-1 promoted the migration of LoVo cells, a colon cancer cell line, whereas TIMP-1 neutralization inhibited the enhanced migration. The TIMP-1 levels secreted from the cancer cells were approximately 10 times less than those secreted from the CAFs. TIMP-1 secretion was higher in CAFs co-cultured with cancer cells than in monocultured CAFs. Furthermore, the migration of LoVo cells increased upon co-culturing with the CAFs. TIMP-1 neutralization partially inhibited this enhanced migration. These results suggest that CAFs are the primary source of TIMP-1 and that the TIMP-1 production is enhanced through CSI in the tumor microenvironment, which promotes cancer cell migration.

The repair of DNA damage caused by chemotherapy in cancer cells occurs mainly at two cell cycle checkpoints (G1 and G2) and is a factor contributing to chemoresistance. Most colorectal cancers harbor mutations in p53, the main pathway involved in the G1 checkpoint, and thus, are particularly dependent on the G2 checkpoint for DNA repair. The present study examined the effect of AZD6738, a specific inhibitor of ataxia telangiectasia mutated and rad3-related (ATR) involved in the G2 checkpoint, combined with 5-fluorouracil (5-FU), a central chemotherapeutic agent, on colorectal cancer cells. Since 5-FU has a DNA-damaging effect, its combination with AZD6738 is likely to enhance the therapeutic effect. The effects of the AZD6738/5-FU combination were evaluated in various colorectal cancer cells (HT29, SW480, HCT116 and DLD-1 cells) by flow cytometry (HT29 cells), western blotting (HT29 cells) and water-soluble tetrazolium 1 assays (HT29, SW480, HCT116 and DLD-1 cells), as well as in an experimental animal model (HT29 cells). In vitro, the AZD6738/5-FU combination increased the number of mitotic cells according to flow cytometry, decreased the checkpoint kinase 1 phosphorylation levels and increased cleaved caspase-3 and phosphorylated form of H2A.X variant histone levels according to western blotting, and decreased the proliferation rate of four colon cancer cell lines according to cell viability experiments. In vivo, xenografted colorectal cancer cells treated with the AZD6738/5-FU combination exhibited a marked decrease in proliferation compared with the 5-FU alone group. The present results suggested that AZD6738 enhanced the effect of 5-FU in p53-mutated colorectal cancer.

The acquisition of resistance to apoptosis is one of the biggest problems in colorectal cancer (CRC) treatment. This study aimed to elucidate the mechanisms of resistance to apoptosis with a focus on interleukin (IL)-6 produced by the interaction between cancer cells and cancer-associated fibroblasts (CAFs). DLD-1 and HCT116 cell lines were treated with IL-6 and furthermore co-cultured with CAFs. The expression levels of Bcl-xL, Mcl-1 and phosphorylation of STAT3 were evaluated by western blotting. We also performed immunostaining for CRC specimens and evaluated the correlation between CAFs invasion and Bcl-xL/Mcl-1 expression. Both IL-6 and co-culturing enhanced Bcl-xL, Mcl-1 and the phosphorylation of STAT3. Immunohistochemistry showed a positive correlation between CAFs and Bcl-xL/Mcl-1. These results showed that the interaction between CAFs and cancer cells enhances Bcl-xL and Mcl-1 through the IL-6/STAT3 signaling pathway. Our findings provide new potential therapeutic targets and strategies for CRC treatment.

Vascular endothelial growth factor (VEGF) influences colorectal cancer (CRC) progression and is a key target in the treatment for metastatic CRC. However, the oncological impact of preoperative circulating VEGF in non-metastatic CRC (non-mCRC) has not been clearly elucidated. Herein, we have investigated the prognostic significance of elevated preoperative serum VEGF concentration in curatively resected non-mCRC without neoadjuvant therapy. A total of 474 patients with pStage I-III CRC who underwent curative resection without neoadjuvant therapy were included. The relationship between preoperative serum VEGF concentration and clinicopathologic characteristics, overall survival (OS), and recurrence-free survival (RFS) were investigated. The median follow-up duration was 47.4 months. No significant relationship between preoperative VEGF and clinicopathologic characteristics including tumor markers, pStage, and lymphovascular invasion was identified; however, VEGF values were wide-ranged in every pStage. Patients were categorized into four groups as follows: VEGF < median, median to 75th percentile, 75th percentile to 90th percentile, and ≥90th percentile. A tendency for a difference in 5-year OS (p=0.064) and RFS (p=0.089) was observed among the groups; however, OS and RFS were not correlated with VEGF elevation. In multivariate analyses, VEGF ≥90th percentile was paradoxically associated with better RFS. Preoperative elevated serum VEGF concentration was associated with neither worse clinicopathological characteristics nor worse long-term outcomes in curatively resected non-mCRC. The prognostic value of preoperative circulating VEGF in initially resectable non-mCRC remains limited.

ORAI1 constitutes the pore‐forming subunit of the calcium release‐activated calcium (CRAC) channel, which is responsible for store‐operated calcium entry into lymphocytes. It is known that ORAI1 is essential for the activation of T cells and mast cells and is considered to be a potent therapeutic target for autoimmune and allergic diseases. Here, we obtained a new humanized antibody, DS‐2741a, that inhibits ORAI1 function. DS‐2741a bound to human‐ORAI1 with high affinity and without cross‐reactivity to rodent Orai1. DS‐2741a demonstrated suppression of CRAC‐mediated human and mouse T‐cell activation and mast cell degranulation in human ORAI1 knock‐in mice. Furthermore, DS‐2741a ameliorated house dust mite antigen‐induced dermatitis in the human ORAI1 knock‐in mouse. Taken together, DS‐2741a inhibited T‐cell and mast cell functions, thus improving skin inflammation in animal models of atopic dermatitis and reinforcing the need for investigation of DS‐2741a for the treatment of allergic diseases in a clinical setting.