The tRNA-Derived Fragment-3017A Promotes Metastasis by Inhibiting NELL2 in Human Gastric Cancer.

tRNA-derived fragments (tRFs) are a new classification of small non-coding RNAs (sncRNAs) derived from the specific cleavage of precursors and mature tRNAs. Accumulating recent evidence has shown that tRFs are frequently abnormal in several cancers. Nevertheless, the role of tRFs in gastric cancer and its mechanism remain unclear. In this study, we found abnormal expression of tRF-3017A (derived from tRNA-Val-TAC) in gastric cancer tissues and cell lines and confirmed its effect on promoting the invasion and migration of gastric cancer cells through functional experiments in vitro. Analysis of clinicopathologic data showed patients with higher tRF-3017A were associated with significantly higher lymph node metastasis. Mechanistic investigation implies that tRF-3017A regulates the tumor suppressor gene NELL2 through forming the RNA-induced silencing complex (RISC) with Argonaute (AGO) proteins. In this study, we found that higher tRF-3017A were associated with significantly higher lymph node metastasis in gastric cancer patients and the tRF-3017A may play a role in promoting the migration and invasion of gastric cancer cells by silencing tumor suppressor NELL2.

Long noncoding RNA H19 participates in metformin-mediated inhibition of gastric cancer cell invasion.

Recent research suggests that the first-line oral antidiabetes drug metformin may prevent gastric cancer progression and improve prognosis. Many studies have also shown that long noncoding RNAs (lncRNAs) play important roles in many biological processes. Therefore, we aimed to explore whether lncRNAs participate in the mechanisms by which metformin affects gastric cancer cells. In the current study, we found that metformin significantly inhibited the cellular functions of gastric cancer cells through Cell Counting Kit-8 and invasion assays. We found that lncRNA H19 was greatly downregulated in gastric cancer cells treated with metformin using lncRNA microassays. Based on bioinformatics analyses of the Oncomine and The Cancer Genome Atlas databases, H19 is shown to be overexpressed in gastric cancer tissues, with increased expression of H19 relating to advanced pathological tumor stage and pathological tumor node metastasis stage, indicating that H19 may be associated with the invasive ability of gastric cancer. We knocked down H19 in AGS and SGC7901 cell lines and found that knocked-down H19 could decrease gastric cancer cell invasion and that metformin could not further decrease invasion after the knock down. Moreover, H19 depletion increased AMPK activation and decreased MMP9 expression, and metformin could not further activate AMPK or decrease MMP9 in H19 knocked-down gastric cancer cells. In summary, metformin has a profound antitumor effect on gastric cancer cells, and H19 is a key component in the process of metformin suppressing gastric cancer cell invasion.

Laparoscopic intersphincteric resection versus an open approach for low rectal cancer: a meta-analysis.

AIM: The aim of this study was to compare the short-term and mid-term effects of laparoscopic intersphincteric resection with the conventional open approach for patients with low rectal cancer through a meta-analysis. METHODS: The PubMed, EMBASE, Cochrane, and Ovid databases were searched for eligible studies until March 2017. Operation time, blood loss, circumferential resection margin-positive rate, distal margin length, number of resected lymph nodes, diverting stoma rate, postoperative overall morbidity, anastomotic leakage, and hospital stay were the main short-term effect endpoints. We also examined disease-free survival, overall survival, local recurrence, and post-operational anal function as secondary outcomes to evaluate the mid-term effects of laparoscopic surgery. RESULTS: Five studies involving 620 patients were included in the analyses. Compared with the open approach, the laparoscopic ISR had less blood loss (weighted mean difference [WMD] = - 214.65 ml, 95% CI [- 370.44, - 196.13], p < 0.01), less postoperative overall morbidity (OR = 0.58, 95% CI [0.40, 0.86], p < 0.01), and shorter duration of hospital stay (WMD = - 5.87 days, 95% CI [- 11.35, - 0.40], p < 0.05); however, the operation time was significantly longer in the laparoscopic group (WMD = 47.34 min, 95% CI [4.10, 90.58], p < 0.05). No other significant differences were observed. CONCLUSION: Laparoscopic ISR for low rectal cancer offers fewer complications and faster recovery, with similar operation quality and mid-term oncological results than the conventional approach. Although this technique is comparatively more complex than the conventional approach and requires practice, laparoscopic ISR shows great potential as a surgical option and deserves further clinical study.