DNA methylation mediated down-regulation of ANGPTL4 promotes colorectal cancer metastasis by activating the ERK pathway.

Background: Colorectal cancer (CRC) imposes significant health burden and is increasing in incidence. NGPTL4 has been implicated in the development of CRC. The present study aimed to investigate the molecular mechanisms by which ANGPTL4 expression might regulate epithelial-mesenchymal transition (EMT) and the tumor microenvironment in CRC. Methods: CRC and para-carcinoma tissues were collected from 67 CRC patients. ANGPTL4 expression levels and DNA methylation of ANGPTL4 promoter region were determined. Next, the migration and invasion capacities of CRC cells were assessed. Immunofluorescence and Western blot were used to identify the signaling pathways by which ANGPTL4 mediated tumor metastasis. A tumorigenesis mice model with transplanted fibroblast cells and ANGPTL4 overexpressed CRC cells was established to investigate the effects of ANGPTL4 on the metastasis of cancer cells in vivo. Results: ANGPTL4 was significantly decreased in CRC tissues and DNA hypermethylation was involved in the regulation of ANGPTL4. Mechanistically, ANGPTL4 induced activation of cancer-associated fibroblasts in the tumor microenvironment and promoted EMT in CRC cells through the ERK signaling pathway. In vivo, the overexpression of ANGPTL4 was found to inhibit the metastasis of tumor cells in lung tissues. Conclusion: DNA hypermethylation induced ANGPTL4 downregulation promoted the activation of cancer-associated fibroblasts and epithelial mesenchymal transformation of CRC cells via the ERK signaling pathway, thereby promoting invasion and metastasis in CRC.

Long-Term Outcomes of Ligation of the Inter-Sphincteric Fistula Tract Plus Bioprosthetic Anal Fistula Plug (LIFT-Plug) in the Treatment of Trans-Sphincteric Perianal Fistula.

BACKGROUND The ligation of the inter-sphincteric fistula tract plus bioprosthetic anal fistula plug (LIFT-plug) is a new procedure in the treatment of trans-sphincteric perianal fistulas. The aim of this study was to evaluate its long-term outcomes. MATERIAL AND METHODS Clinical data of 78 patients with trans-sphincteric perianal fistula who were managed by the LIFT-plug technique between March 2014 to October 2016 were analyzed retrospectively. The operation time, healing rate, postoperative complications, recurrences, and length of stay were reviewed. RESULTS No serious complications occurred during the operation in all patients. The median follow-up was 30 months (16 to 47 months), clinical healing of the anal fistula occurred in 75 patients (96.2%). The median operative time was 25 minutes (18 to 45 minutes). The mean complete healing time was 16 days (9 to 46 days). The median healing time for the external anal fistula opening was 2 weeks (range, 2 to 3 weeks), and the inter-sphincteric groove incision healing time was 4 weeks (range, 3 to 7 weeks). The median hospital stay after operation was 5 days. Fistula recurred in 2 patients because of spontaneous expulsion of the plug at 7 days post-surgery; perianal abscess occurred in 1 patient. The anal function was evaluated in 70 patients of the 78 patients. Perfect control of continence was recorded for 97.1% of the patients (68 out of 70 patients). Two patients were identified to a rare complication of gas incontinence (Wexner score 1). CONCLUSIONS LIFT-plug procedure for the treatment of trans-sphincteric fistulas is a simple procedure with a high healing rate, minimal invasiveness, quick healing, and without disturbance to anal function. LIFT-plug is an ideal procedure for trans-sphincteric fistula.

AIM2 regulates viability and apoptosis in human colorectal cancer cells via the PI3K/Akt pathway.

Absent in melanoma 2 (AIM2) plays an important role in innate immunity as a DNA sensor in the cytoplasm by triggering the assembly of an AIM2 inflammasome that results in caspase-1-mediated inflammatory responses and cell death. In recent years, studies have indicated that AIM2 can suppress cancer cell proliferation, and mutations in the gene encoding AIM2 are frequently identified in patients with colorectal cancer (CRC). However, the mechanism by which AIM2 restricts tumor growth remains unclear. We reconstructed AIM2 expression in HCT116 CRC cells by lentivirus transfection. Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry, we demonstrated that expression of AIM2 inhibited the viability and increased the apoptosis rate of CRC cells, and cell cycle analysis suggested that AIM2 blocked cell cycle transition from G1 to S phase. Western blot analysis showed that AIM2 promoted apoptosis in CRC cells by suppressing the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway. Our data suggest that AIM2 plays a critical role as a tumor suppressor and might serve as a potential therapeutic target in CRC.