CD204-positive M2-like tumor-associated macrophages increase migration of gastric cancer cells by upregulating miR-210 to reduce NTN4 expression.

BACKGROUND: Tumor-associated macrophages (TAMs) are the predominant immune cells in the tumor microenvironment and portend poor prognosis. However, the molecular mechanisms underlying the tumor promotion of TAMs have not been fully elucidated. METHODS: Coculture of gastric cancer cells with U937 cells was performed to investigate the impact of TAMs on cancer cell behavior. MicroRNA (miRNA) microarray and bioinformatics were applied to identify the involved miRNAs and the functional target genes. The regulation of the miRNA on its target gene was studied using anti-miRNA and miRNA mimic. RESULTS: Coculture with CD204+ M2-like TAMs increased proliferation, migration, and epithelial-mesenchymal transition of gastric cancer cells. MiR-210 was the most upregulated miRNA in cancer cells identified by miRNA microarray after coculture. In gastric cancer tissues, miR-210 expression was positively correlated with CD204+ M2-like TAM infiltration. Inactivation of miR-210 by antimir attenuated CD204+ M2-like TAMs-induced cancer cell migration. Using pharmacological inhibitors and neutralizing antibodies, CD204+ M2-like TAMs-secreted TNFα was found to upregulate miR-210 through NF-κB/HIF-1α signaling. Bioinformatics analysis showed netrin-4 (NTN4) as a potential target of miR-210 to suppress gastric cancer cell migration. We also found an inverse expression between miR-210 and NTN4 in cancer cells after coculture or in tumor xenografts. Anti-miR-210 increased NTN4 expression, while miR-210 mimics downregulated NTN4 in cancer cells. Reporter luciferase assays showed that MiR-210 mimics suppressed NTN4 3' untranslated region-driven luciferase activity in cancer cells, but this effect was blocked after mutating miR-210 binding site. CONCLUSIONS: CD204+ M2-like TAMs can utilize the TNF-α/NF-κB/HIF-1α/miR-210/NTN4 pathway to facilitate gastric cancer progression.

Antifibrotic role of PGC-1α-siRNA against TGF-ß1-induced renal interstitial fibrosis.

Peroxisome proliferator-activated receptor coactivator-1 alpha (PGC-1α) is a transcriptional coactivator that regulates energy metabolism and mitochondrial biogenesis. Recently, mitochondrial dysfunction has been indicated as an established risk factor for the development of renal fibrosis. However, whether PGC-1α is involved in the pathogenesis of renal fibrosis is unknown. In this study, we treated NRK-49F (normal rat kidney fibroblast) cells with transforming growth factor-beta 1 (TGF-ß1) for 24 h to establish an in vitro fibrosis model. TGF-ß1 induced the upregulation of type I collagen, fibronectin, TGF-ß receptor I (TGFß-RI), TGFß-RII, Smad4, and pSmad2/3, as well as PGC-1α. NRK-49F cells transfected with pcDNA-PGC-1α showed significantly increased expression of fibronectin and type I collagen, as revealed by western blot assay. Interestingly, transfection with PGC-1α-siRNA caused a stark reversal of TGF-ß1-induced cellular fibrosis, with concomitant suppression of fibronectin and type I collagen, as revealed by western blot and immunofluorescence assays. Moreover, SB431542 (TGFß-RI), LY294002 (PI3K/Akt), and SB203580 (p38 MAPK), inhibitors of TGF-ß-associated pathways, markedly suppressed TGF-ß1-induced PGC-1α upregulation. These results implicate a role of PGC-1α in renal interstitial fibrosis mediated via the TGFß-RI, PI3K/Akt, and p38 MAPK pathways. Our findings that PGC-1α-siRNA downregulates fibronectin and type I collagen suggest that it can be used as a novel molecular treatment for renal fibrosis.

Duodenal angiosarcoma: an unusual cause of severe gastrointestinal bleeding.

Angiosarcoma is a rare soft-tissue neoplasm that occurs most often in the skin and the subcutaneous tissues but very rarely in the gastrointestinal tract. We report a case of primary intestinal angiosarcoma with severe gastrointestinal bleeding. This patient was referred to our institute for shock with tarry-bloody stool and severe anemia. Panendoscopy revealed multiple duodenal polypoid tumors, and initial biopsy specimen showed poorly differentiated adenocarcinoma. The tumors were treated with pancreaticoduodenectomy, but the patient died 2 weeks after the operation as a result of acute respiratory distress syndrome. The pathology was consistent with angiosarcoma of the duodenum. In our experience, this tumor may cause severe bleeding, and surgery should be performed as soon as possible to prevent complications of hypovolemic shock.

Tumor-Associated Macrophages Promote Epigenetic Silencing of Gelsolin through DNA Methyltransferase 1 in Gastric Cancer Cells.

Epigenetic repression of the tumor suppressor gelsolin (GSN) is frequently observed in cancers. Chronic inflammation can promote tumor progression via aberrant DNA methylation. In this study, we investigated the role of tumor-associated macrophages (TAMs) in DNA methylation of the GSN gene during gastric cancer progression. Immunofluorescence staining of 121 gastric cancer tissues showed aberrant localization of GSN and DNA methyltransferase 1 (DNMT1) and juxtaposition of DNMT1 and M2 TAMs. Decreased GSN protein and mRNA expression and increased DNA methylation in the GSN promoter were observed in gastric cancer cell lines and clinical specimens. To examine the effect of TAMs on DNA methylation in gastric cancer cells, we performed in vitro coculture assays and found increased DNMT1 expression but decreased GSN expression in gastric cancer cells after coculture with U937 cells. Knockdown of DNMT1 expression in gastric cancer cells could abort U937 coculture-mediated GSN downregulation. Meanwhile, CCL5 was the main chemokine upregulated in coculture medium. Treatment with CCL5 could induce DNMT1 expression in gastric cancer cells via STAT3 signaling. Inhibiting DNMT1 activity with procainamide, inhibiting DNA methylation with 5-AZA, or inhibiting CCL5/CCR5 signaling with maraviroc reduced tumor growth in vivo In conclusion, upregulation of DNMT1 by CCL5/CCR5/STAT3 signaling is critical for TAM-mediated GSN silencing in gastric cancer. This study identified potential targets for gastric cancer therapy. Cancer Immunol Res; 5(10); 885-97. ©2017 AACR.