Yichao Yan

MiR-194, commonly repressed in colorectal cancer, suppresses tumor growth by regulating the MAP4K4/c-Jun/MDM2 signaling pathway

Tumor growth cascade is a complicated and multistep process with numerous obstacles. Until recently, evidences have shown the involvement of microRNAs (miRNAs) in tumorigenesis and tumor progression of various cancers, including colorectal cancer (CRC). In this study, we explored the role of miR-194 and its downstream pathway in CRC. We acquired data through miRNA microarray profiles, showing that the expression of miR-194 was significantly suppressed in CRC tissues compared with corresponding noncancerous tissues. Decreased miR-194 expression was obviously associated with tumor size and tumor differentiation, as well as TNM stage. Both Kaplan–Meier and multivariate survival analysis showed that downregulated miR-194 was associated with overall survival. Moreover, functional assays indicated that overexpression of miR-194 in CRC cell lines inhibited cell proliferation both in vitro and in vivo. In addition, using dual-luciferase reporter gene assay, we found MAP4K4 was the direct target of miR-194. Silencing of MAP4K4 resulted in similar biological behavior changes to that of overexpression of miR-194. We also observed through Human Gene Expression Array that MDM2 was one of the downstream targets of MAP4K4. Knockdown of MAP4K4 downregulated MDM2 expression through transcription factor c-Jun binding to the −1063 to -1057 bp of the promoter. These results suggest that miR-194, regulating the MAP4K4/c-Jun/MDM2 signaling pathway, might act as a tumor suppressor and serve as a novel target for CRC prevention and therapy.

MicroRNA-217 functions as a prognosis predictor and inhibits colorectal cancer cell proliferation and invasion via an AEG-1 dependent mechanism.

BackgroundRecent studies have indicated the possible function of miR-217 in tumorigenesis. However, the roles of miR-217 in colorectal cancer (CRC) are still largely unknown.MethodsWe examined the expression of miR-217 and AEG-1 in 50 CRC tissues and the corresponding noncancerous tissues by qRT-PCR. The clinical significance of miR-217 was analyzed. CRC cell lines with miR-217 upregulation and AEG-1 silencing were established and the effects on tumor growth in vitro and in vivo were assessed. Dual-luciferase reporter gene assays were also performed to investigate the interaction between miR-217 and AEG-1.ResultsOur data demonstrated that miR-217 was significantly downregulated in 50 pairs of colorectal cancer tissues. MiR-217 expression levels were closely correlated with tumor differentiation. Moreover, decreased miR-217 expression was also associated with shorter overall survival of CRC patients. MiR-217 overexpression significantly inhibited proliferation, colony formation and invasiveness of CRC cells by promoting apoptosis and G0/G1 phase arrest. Interestingly, ectopic miR-217 expression decreased AEG-1 expression and repressed luciferase reporter activity associated with the AEG-1 3′-untranslated region (UTR). AEG-1 silencing resulted in similar biological behavior changes to those associated with miR-217 overexpression. Finally, in a nude mouse xenografted tumor model, miR-217 overexpression significantly suppressed CRC cell growth.ConclusionsOur findings suggest that miR-217 has considerable value as a prognostic marker and potential therapeutic target in CRC.

Downregulation of miR-199b is associated with distant metastasis in colorectal cancer via activation of SIRT1 and inhibition of CREB/KISS1 signaling

The progression of distant metastasis cascade is a multistep and complicated process, frequently leading to a poor prognosis in cancer patients. Recently, growing evidence has indicated that deregulation of microRNAs (miRNAs) contributes to tumorigenesis and tumor progression in colorectal cancer (CRC). In the present study, by comparing the miRNA expression profiles of CRC tissues and corresponding hepatic metastasis tissues, we established the downregulation of miR-199b in CRC metastasis tissues. The decrease in miR-199b expression was significantly correlated to late TNM stage and distant metastasis. Moreover, Kaplan–Meier curves showed that CRC patients with high expression level of miR-199b had a longer median survival. Functional assays results indicated that the restoration of miR-199b considerably reduced cell invasion and migration in vitro and in vivo, and increased the sensitivity to 5-FU and oxaliplatin. Further dual-luciferase reporter gene assays revealed that SIRT1 was the direct target of miR-199b in CRC. The expression of miR-199b was inversely correlated with SIRT1 in CRC specimens. SIRT1 knockdown produced effects on biological behavior that were similar to those of miR-199b overexpression. Furthermore, through Human Tumor Metastasis PCR Array we discovered KISS1 was one of the downstream targets of SIRT1. Silencing of SIRT1 upregulated KISS1 expression by enhancing the acetylation of the transcription factor CREB. The latter was further activated via binding to the promoter of KISS1 to induce transcription. Thus, we concluded that miR-199b regulates SIRT1/CREB/KISS1 signaling pathway and might serve as a prognosis marker or a novel therapeutic target for patients with CRC.

Long non‑coding RNA GAS5 inhibits cell proliferation, induces G0/G1 arrest and apoptosis, and functions as a prognostic marker in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer worldwide and its treatment remains a challenge. Effective control of cell survival and proliferation is critical in the prevention of oncogenesis and successful treatment of cancer. Long non-coding RNAs (lncRNAs) have emerged as primary regulators of carcinogenesis. Growth arrest specific 5 (GAS5), a lncRNA, is known to be aberrantly expressed in several types of cancer, however, the role of GAS5 in CRC remains unclear. In the present study, GAS5 mRNA expression was measured in CRC and adjacent normal mucosa tissue samples from 53 patients using reverse transcription-quantitative polymerase chain reaction analysis, in addition to seven CRC cell lines. GAS5 mRNA expression was observed to be markedly downregulated in human CRC tissues and cell lines. Decreased GAS5 expression was associated with an increase in tumor diameter [odds ratio (OR), 0.176 (95% CI, 0.053-0.586); P=0.003] and later tumor-node-metastasis stage [OR, 0.261 (95% CI, 0.083-0.819); P=0.019]. Patients with decreased GAS5 expression exhibited decreased overall survival rates compared with patients with increased GAS5 expression (P=0.015). The Cox proportional hazards model demonstrated that downregulated GAS5 expression was an independent prognostic factor for CRC (hazard ratio, 0.236; 95% confidence interval, 0.067-0.827; P=0.024). Functional assays demonstrated that overexpression of GAS5 inhibited cell proliferation and survival, and induced G0/G1 cell cycle arrest and apoptosis; however, knockdown of GAS5 expression enhanced cell proliferation, and reduced G0/G1 arrest and apoptosis. In conclusion, the results of the present study suggest that GAS5 is essential in the control of apoptosis and cell growth in CRC. Therefore, GAS5 may represent a novel prognostic and diagnostic marker of CRC, in addition to being a potential therapeutic target.

Analysis of co-expression networks for circular RNAs and mRNAs reveals that circular RNAs hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 are candidate oncogenes in gastric cancer.

ABSTRACT Accumulating evidence has suggested that circular RNAs (circRNAs) play important roles in oncogenesis and tumor progression. However, our knowledge of circRNAs in gastric cancer (GC) remains limited. To investigate circRNAs involved in GC oncogenesis, we examined differentially-expressed circRNAs and mRNAs in GC tissues and paired noncancerous mucosa tissues using circRNA and mRNA microarrays. Next, we built gene co-expression networks according to the degree of correlation to predict the critical circRNAs in GC. Through bioinformatics analysis, we observed three newly identified circRNAs that are substantially upregulated in GC: hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15. Additionally, hsa_circ_0047905 and hsa_circ_0138960 positively correlated with their parental gene mRNA. Knockdown of hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 in GC cells, resulted in downregulation of parental gene expression. Functional assays suggested that inhibition of these three circular RNAs suppresses GC cell proliferation and invasion in vitro. Those findings suggest that hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 might act as tumor promoters in the pathogenesis of gastric cancer.

Ischemic preconditioning increases GSK-3β/β-catenin levels and ameliorates liver ischemia/reperfusion injury in rats

Ischemic preconditioning (IPC) ameliorates ischemia/reperfusion (I/R) injury in a number of organs, and the glycogen synthase kinase-3β (GSK-3β)/β-catenin signaling pathway regulates I/R-induced proliferation and apoptosis in the central nervous system and heart. However, the function of this signaling pathway in IPC during liver I/R remains unclear. Thus, in this study, we aimed to investigte the role of the GSK-3β/β-catenin pathway during I/R and following ischemic preconditioning. For this purpose, 30 Sprague-Dawley rats were randomly divided into the sham-operated, the I/R and the IPC groups (n=10). Following reperfusion, liver pathology, as well as alanine aminotransferase (ALT), aspartate aminotransferase (AST), maleic dialdehyde (MDA) and superoxide dismutase (SOD) levels were assessed. Western blot analysis was performed to quantify the GSK-3β, Ser9-phospho-GSK-3β (p-GSK-3β), cytosolic and nuclear β-catenin, vascular endothelial growth factor (VEGF), Bcl-2 and survivin levels. In addition, the Bcl-2 and survivin mRNA levels were assessed by RT-qPCR. Compared with the sham-operated group, I/R increased serum ALT, AST and MDA activity and decreased SOD levels, while IPC significantly decreased serum ALT, AST and MDA activity and increased SOD levels, compared with the I/R group. Simultaneously, I/R increased p-GSK-3β protein expression, and decreased Bcl-2 and survivin protein and mRNA levels. IPC further increased the protein expression of p-GSK-3β, and also increased cytosolic and nuclear β-catenin and VEGF expression compared with the I/R group; the expression of Bcl-2 and survivin was also increased by IPC, both at the mRNA and protein level. The total GSK-3β expression remained unaltered in all the groups. In conclusion, our data demonstrate that IPC exerts protective effects against liver injury induced by I/R and activates the GSK-3β/β-catenin signaling pathway.

Long noncoding ribonucleic acid specific for distant metastasis of gastric cancer is associated with TRIM16 expression and facilitates tumor cell invasion in vitro

Increasing evidence has indicated that long noncoding ribonucleic acids (lncRNAs) play a major role in cancers. Although certain lncRNAs has been reported to play a role in gastric cancer (GC), specific lncRNAs involved in distant metastasis of GC remain unknown.

Comparison of the safety of electrotome, Harmonic scalpel, and LigaSure for management of thyroid surgery

Energy‐based surgical devices, including electrotome, the Harmonic scalpel, and LigaSure, have been widely applied in thyroid surgery, although a comparison of their safety and efficacy has not been reported yet. In this study, we investigated the feasibility of using hemostatic energy‐based surgical devices during thyroid surgery in a canine model.

The effect of Vasohibin-1 expression and tumor-associated macrophages on the angiogenesis in vitro and in vivo

Vasohibin-1 is an intrinsic inhibitor of angiogenesis induced by VEGF-A. However, there little is known about the relationship between Vasohibin-1 expression, angiogenesis, and tumor-associated macrophages (TAMs). Vasohibin-1 expression, VEGF-A expression, microvessel density (MVD) marked with CD34, and density of cells marked with CD68 were measured in 111 paraffin-embedded tissues of gastric cancer by immunohistochemistry. The length of tube forming structures of endothelial cells and mobility rate of gastric cancer cells in Matrigel were tested by three-dimensional live cell imaging system. The effect of TAMs on the tumor growth, MVD, and Vasohibin-1 expression was measured by nude mice tumor genesis assay in vivo. We found that high Vasohibin-1 protein expression correlated significantly with worse TNM stage (P = 0.002), metastatic lymph node (P = 0.014), distant metastasis (P = 0.022), overall survival (P < 0.001), and progression-free survival (P < 0.001) compared to those with low Vasohibin-1 expression. Vasohibin-1 protein expression had statistical correlation with the MVD (r = 0.860, P < 0.001), density of CD68+ cells (r = 0.882, P < 0.001), and VEGF-A expression (r = 0.719, P < 0.001) in the gastric cancer tissues. Decreasing Vasohibin-1 expression with siRNA increased the length of tube forming structures of endothelial cells in co-culture with endothelial cells (EA-hy923), macrophages, and gastric cancers (Hs746T). Tumor volume (P = 0.001), Vasohibin-1 (P < 0.001), and VEGF-A (P < 0.001) expression in mice inoculated with AGS and THP (10:1) was significantly higher than that with AGS alone (P = 0.001). Vasohibin-1 protein expression had statistical correlation with VEGF expression (r = 0.786, P < 0.001) and MVD (r = 0.496, P = 0.014) in gastric xenografted tumor. Therefore, Vasohibin-1 might be a potential marker of worse prognosis and therapeutic target in gastric cancer. Vasohibin-1 might play an important role in the process of angiogenesis regulated by TAMs.