Macrophages are a major component of tumor stroma. Tumor-associated macrophages (TAMs) show anti- (M1) or protumor (M2) functions depending on the cytokine milieu of the tumor microenvironment. Cyclooxygenase-2 (COX-2) is constitutively expressed in a variety of tumors including colorectal cancer. TAMs are known to be a major source of COX-2 in human and mice intestinal tumors. COX-2 inhibitor reduces the number and size of intestinal adenomas in familial adenomatous polyposis patients and Apc(Min/+) mice. Although COX-2 inhibitor is thought to regulate cancer-related inflammation, its effect on TAM phenotype remains unknown. Here, we examined the effects of COX-2 inhibition on TAM phenotype and cytokine expression both in vivo and in vitro. Firstly, the selective COX-2 inhibitor celecoxib changed the TAM phenotype from M2 to M1, in proportion to the reduction in number of Apc(Min/+) mouse polyps. Concomitantly, the expression of M1-related cytokine interfron (IFN)-γ was significantly upregulated by celecoxib, although the M2-related cytokines interleukin (IL)-4, IL-13 and IL-10 were not significantly altered. Secondly, IFN-γ treatment attenuated M2 phenotype of mouse peritoneal macrophages and oriented them to M1 even in the presence of M2-polarizing cytokines such as IL-4, IL-13 and IL-10. Thus, our results suggest that COX-2 inhibition alters TAM phenotype in an IFN-γ-dependent manner and subsequently may reduce intestinal tumor progression.

Nardilysin (NRDc), a metalloendopeptidase of the M16 family, promotes ectodomain shedding of the precursor forms of various growth factors and cytokines by enhancing the protease activities of ADAM proteins. Here, we show the growth-promoting role of NRDc in gastric cancer cells. Analyses of clinical samples demonstrated that NRDc protein expression was frequently elevated both in the serum and cancer epithelium of gastric cancer patients. After NRDc knockdown, tumour cell growth was suppressed both in vitro and in xenograft experiments. In gastric cancer cells, NRDc promotes shedding of pro-tumour necrosis factor-alpha (pro-TNF-α), which stimulates expression of NF-κB-regulated multiple cytokines such as interleukin (IL)-6. In turn, IL-6 activates STAT3, leading to transcriptional upregulation of downstream growth-related genes. Gene silencing of ADAM17 or ADAM10, representative ADAM proteases, phenocopied the changes in cytokine expression and cell growth induced by NRDc knockdown. Our results demonstrate that gastric cancer cell growth is maintained by autonomous TNF-α–NF-κB and IL-6–STAT3 signalling, and that NRDc and ADAM proteases turn on these signalling cascades by stimulating ectodomain shedding of TNF-α.

Growth arrest-specific gene (Gas) 6 is a γ-carboxyglutamic acid domain-containing protein, which shares 43% amino acid identity with protein S. Gas6 has been shown to enhance cancer cell proliferation in vitro. On the other hand, recent studies have demonstrated that Gas6 inhibits toll-like receptor-mediated immune reactions. Immune reactions are known to affect intestinal tumorigenesis. In this study, we investigated how Gas6 contributes to tumorigenesis in the intestine. Administration of recombinant Gas6 weakly, but significantly, enhanced proliferation of intestinal cancer cells (SW480 and HT29), whereas it suppressed the inflammatory responses of Lipopolysaccharide (LPS)-stimulated monocytes (THP-1). Compared with Gas6(+/+) mice, Gas6(-/-) mice exhibited enhanced azoxymethane/dextran sulfate sodium (DSS)-induced tumorigenesis and had a shorter survival. Gas6(-/-) mice also exhibited more severe DSS-induced colitis. DSS-treated Gas6(-/-) mice showed attenuated Socs1/3 messenger RNA expression and enhanced nuclear factor-kappaB activation in the colonic stroma, suggesting that the target of Gas6 is stromal cells. Bone marrow transplantation experiments indicated that both epithelial cells and bone marrow-derived cells are Gas6 sources. Furthermore, the number of intestinal tumors in Apc(Min) Gas6(-/-) mice was higher than that in Apc(Min) Gas6(+/+) mice, resulting in shorter survival. In a group of 62 patients with advanced colorectal cancer, Gas6 immunoreactivity in cancer tissues was positively correlated with prognosis. Thus, we revealed a unique in vivo inhibitory role of Gas6 during the progression of intestinal tumors associated with suppression of stromal immune reactions. These results suggest a novel therapeutic approach for colorectal cancer patients by regulation of stromal immune responses.

Prostaglandin E2 plays important roles in the maintenance of colonic homeostasis. The recently identified prostaglandin E receptor (EP) 4–associated protein (EPRAP) is essential for an anti-inflammatory function of EP4 signaling in macrophages in vitro. To investigate the in vivo roles of EPRAP, we examined the effects of EPRAP on colitis and colitis-associated tumorigenesis. In mice, EPRAP deficiency exacerbated colitis induced by dextran sodium sulfate (DSS) treatment. Wild-type (WT) or EPRAP-deficient recipients transplanted with EPRAP-deficient bone marrow developed more severe DSS-induced colitis than WT or EPRAP-deficient recipients of WT bone marrow. In the context of colitis-associated tumorigenesis, both systemic EPRAP null mutation and EPRAP-deficiency in the bone marrow enhanced intestinal polyp formation induced by azoxymethane (AOM)/DSS treatment. Administration of an EP4-selective agonist, ONO-AE1-329, ameliorated DSS-induced colitis in WT, but not in EPRAP-deficient mice. EPRAP deficiency increased the levels of the phosphorylated forms of p105, MEK, and ERK, resulting in activation of stromal macrophages in DSS-induced colitis. Macrophages of DSS-treated EPRAP-deficient mice exhibited a marked increase in the expression of pro-inflammatory genes, relative to WT mice. By contrast, forced expression of EPRAP in macrophages ameliorated DSS-induced colitis and AOM/DSS-induced intestinal polyp formation. These data suggest that EPRAP in macrophages functions crucially in suppressing colonic inflammation. Consistently, EPRAP-positive macrophages were also accumulated in the colonic stroma of ulcerative colitis patients. Thus, EPRAP may be a potential therapeutic target for inflammatory bowel disease and associated intestinal tumorigenesis.

Sister Mary Joseph's nodule (SMJN) is a rare umbilical nodule that develops secondary to metastatic cancer. Primary malignancies are located in the abdomen or pelvis. Patients with SMJN have a poor prognosis. An 83-year-old woman presented to our hospital with a 1-month history of a rapidly enlarging umbilical mass. Endoscopic findings revealed advanced transverse colon cancer. computer tomography and fluorodeoxyglucose-positron emission tomography revealed tumors of the transverse colon, umbilicus, right inguinal lymph nodes, and left lung. The feeding arteries and drainage veins for the SMJN were the inferior epigastric vessels. Imaging findings of the left lung tumor allowed for identification of the primary lung cancer, and a diagnosis of advanced transverse colon cancer with SMJN and primary lung cancer was made. The patient underwent local resection of the SMNJ and subsequent single-site laparoscopic surgery involving right hemicolectomy and paracolic lymph node dissection. Intra-abdominal dissemination to the mesocolon was confirmed during surgery. Histopathologically, the transverse colon cancer was confirmed to be moderately differentiated tubular adenocarcinoma. We suspect that SMJN may occur via a hematogenous pathway. Although chemotherapy for colon cancer and thoracoscopic surgery for the primary lung cancer were scheduled, the patient and her family desired home hospice. Seven months after surgery, she died of rapidly growing lung cancer. Key words: Umbilicus; Sister Mary Joseph; Singleincision laparoscopic surgery; Palliative operation; Hematogenous metastasis Core tip: Cutaneous metastasis localized to the umbilicus is termed "Sister Mary Joseph's nodule" (SMJN). SMJN is a rare nodule that originates from tumors in the abdomen or pelvis, and patients with SMJN show a poor prognosis. Previous reports of SMJN described direct disseminative or lymphogenous pathways. To our knowledge, SMJN via the hematogenous pathway is very rare. We herein report a case of advanced colon cancer with SMJN via a hematogenous metastatic pathway treated by palliative single-incision laparoscopic surgery. CASE REPORTHori T, Okada N, Nakauchi M, Hiramoto S, Kikuchi-Mizota A, Kyogoku M, Oike F, Sugimoto H, Tanaka J, Morikami Y, Shigemoto K, Ota T, Kaneko M, Nakatsuji M, Okae S, Tanaka T, Gunji D, Yoshioka A. Hematogenous umbilical metastasis from colon cancer treated by palliative single-incision laparoscopic surgery.