miR-22 Suppresses EMT by Mediating Metabolic Reprogramming in Colorectal Cancer through Targeting MYC-Associated Factor X.

Colorectal cancer (CRC) is one of the most frequent gastrointestinal cancers. MicroRNAs (miRNAs) have been proved to be unusually expressed in CRC progression and thus alter multiple pathological processes in CRC cells. However, the specific roles and mechanisms of miR-22 in CRC have not been clearly reported. MicroRNA-22 (miR-22) and MYC-associated factor X (MAX) expressions were determined by RT-qPCR in CRC tissues and cells. The targeted regulatory effects of miR-22 and MAX were confirmed by luciferase reporter and coimmunoprecipitation assays. Also, gain- and loss-of-function and rescue experiments were used to elucidate the function and mechanism of miR-22 and MAX in CRC cells and the mouse xenograft model. We discovered that miR-22 was hypermethylated and downregulated, while MAX was upregulated in CRC. miR-22 markedly inhibited migration, invasion, glycolysis, and cancer stem cell transcription factors in CRC cells. In addition, it was found that miR-22 can directly target MAX. Additional functional experiments confirmed that MAX overexpression can rescue the effects of miR-22 on the behavior of CRC cells. This study suggested that miR-22, as a cancer suppressor, participates in CRC progression by targeting MAX, which might provide basic information for therapeutic targets for CRC.

Cytochrome C Oxidase Assembly Factor 1 Homolog Predicts Poor Prognosis and Promotes Cell Proliferation in Colorectal Cancer by Regulating PI3K/AKT Signaling.

PURPOSE: Colorectal cancer (CRC) is one of the most common malignancies in the world. The prognosis of advanced CRC is still poor. The purpose of this study was to identify a gene expression profile associated with CRC that may contribute to the early diagnosis of CRC and improve patient prognosis. PATIENTS AND METHODS: Five pairs of CRC tissues and paracancerous tissues were used to identify causative genes using microarray assays. The prognostic value of Cytochrome C Oxidase Assembly Factor 1 Homolog (COA1) in CRC was assessed in 90 CRC patients. Loss-of-function assays, cell proliferation assays using Celigo and MTT, colony formation assays, a subcutaneous xenograft mouse model, and apoptosis assays were used to define the effects of downregulation of COA1 in CRC cells in vitro and in vivo. The underlying molecular mechanisms of COA1 in CRC were also investigated. RESULTS: The causative gene COA1 was identified through microarray analysis. COA1 expression in CRC was notably associated with pathologic differentiation, tumor size, and tumor depth. COA1 expression may act as an independent prognostic factor for overall survival of CRC. Knockdown of COA1 inhibited the proliferation of CRC cells in vitro and the tumorigenicity of CRC cells in vivo. Decreased COA1 expression induced apoptosis of CRC cells. Based on the microarray assay results comparing HCT116 cells transfected with lentivirus encoding anti-COA1 shRNA or negative control shRNA, ingenuity pathway analysis (IPA) revealed that the PI3K/AKT signaling pathway was significantly enriched. Moreover, CCND1, mTOR, AKT1, and MDM2 were identified as the downstream genes of COA1. CONCLUSION: These findings demonstrate that COA1 promotes CRC cell proliferation and inhibits apoptosis by regulating the PI3K/AKT signaling pathway. Our results implicate COA1 as a potential oncogene involved in tumor growth and progression of CRC.

Discovery of Prognostic Signature Genes for Overall Survival Prediction in Gastric Cancer.

BACKGROUND: Gastric cancer (GC) is one of the most common malignant tumors in the digestive system with high mortality globally. However, the biomarkers that accurately predict the prognosis are still lacking. Therefore, it is important to screen for novel prognostic markers and therapeutic targets. METHODS: We conducted differential expression analysis and survival analysis to screen out the prognostic genes. A stepwise method was employed to select a subset of genes in the multivariable Cox model. Overrepresentation enrichment analysis (ORA) was used to search for the pathways associated with poor prognosis. RESULTS: In this study, we designed a seven-gene-signature-based Cox model to stratify the GC samples into high-risk and low-risk groups. The survival analysis revealed that the high-risk and low-risk groups exhibited significantly different prognostic outcomes in both the training and validation datasets. Specifically, CGB5, IGFBP1, OLFML2B, RAI14, SERPINE1, IQSEC2, and MPND were selected by the multivariable Cox model. Functionally, PI3K-Akt signaling pathway and platelet-derived growth factor receptor (PDGFR) were found to be hyperactive in the high-risk group. The multivariable Cox regression analysis revealed that the risk stratification based on the seven-gene-signature-based Cox model was independent of other prognostic factors such as TNM stages, age, and gender. CONCLUSION: In conclusion, we aimed at developing a model to predict the prognosis of gastric cancer. The predictive model could not only effectively predict the risk of GC but also be beneficial to the development of therapeutic strategies.

MiR-92a promotes stem cell-like properties by activating Wnt/ß-catenin signaling in colorectal cancer.

We previously reported the oncogenic function of miR-92a in colorectal cancer. This study identified that miR-92a was upregulated in chemoresistant colorectal cancer cells and tissues. Ectopic expression of miR-92a conferred resistance to 5-fluorouracil-induced apoptosis in vitro, while antagomiR-92a significantly enhanced chemosensitivity in vivo. Moreover, Overexpression of miR-92a promoted the tumor sphere formation and the expression of stem cell markers. MiR-92a overexpression also displayed higher tumourigenesis in vivo. Furthermore, we demonstrated that miR-92a upregulates the Wnt/ß-catenin signaling activity via directly targeting KLF4, GSK3ß and DKK3, which are multiple level negative regulators of the Wnt/ß-catenin signaling cascade. In addition, our results indicate IL-6/STAT3 pathway increases miR-92a expression by directly targeting its promoter, resulting in Wnt/ß-catenin signaling activation and consequent promotion of stem-like phenotypes of colorectal cancer cells. Our present results suggest the essential role of IL-6/STAT3/miR-92a/Wnt/ß-catenin pathway in regulating the stem cell-like traits of colorectal cancer cells and provide a potential target for colorectal cancer therapy.

MicroRNA-22 suppresses the growth, migration and invasion of colorectal cancer cells through a Sp1 negative feedback loop.

MicroRNAs have recently emerged as regulators of many biological processes including cell proliferation, development and differentiation. This study identified that miR-22 was statistically decreased in colorectal cancer clinical specimens and highly metastatic cell lines. Moreover, low miR-22 expression was associated with tumor metastasis, advanced clinical stage and relapse. Consistent with clinical observations, miR-22 significantly suppressed the ability of colorectal cancer cells to growth and metastasize in vitro and in vivo. Sp1 was validated as a target of miR-22, and ectopic expression of Sp1 compromised the inhibitory effects of miR-22. In addition, Sp1 repressed miR-22 transcription by binding to the miR-22 promoter, hence forming a negative feedback loop. Further study has shown that miR-22 suppresses the activity of PTEN/AKT pathway by Sp1. Our present results implicate the newly indentified miR-22/Sp1/PTEN/AKT axis might represent a potential therapeutic target for colorectal cancer.

Laparoscopic rectal resection versus open rectal resection with minilaparotomy for invasive rectal cancer.

BACKGROUND: The minilaparotomy approach is technically feasible for the resection of rectal cancer in selected patients with rapid postoperative recovery and small incision. The study aimed to compare the clinical and oncological outcomes of minilaparotomy and laparoscopic approaches in patients with rectal cancer. METHODS: The 122 included patients with rectal cancer were assigned to either minilaparotomy group (n=65) or laparoscopic group (n=57) which ran from January 2005 to January 2008. Clinical characteristics, perioperative outcomes, postoperative and long-term complications, pathological results and survival rates were compared between the groups. RESULTS: The demographic data of the two groups were similar. The time to normal diet (P=0.024) and the hospital stay (P=0.043) were less in the laparoscopic group than that in the minilaparotomy group. Compared with the minilaparotomy group, the mean operation time was significantly longer [low anterior resection (LAR), P=0.030; abdominoperineal resection (APR), P=0.048] and the direct costs higher for laparoscopic group (P<0.001). The morbidity and mortality were comparable between the two groups. Local recurrence was similar (5.3% laparoscopic, 1.5% minilaparotomy, P=0.520). The 5-year overall and disease-free survival rates were also similar (overall survival is 87.1% in laparoscopic group, and 82.5%in minilaparotomy group, P=0.425; disease-free survival is 74.2% in the laparoscopic group, and 71.4% in mini- laparotomy group, P=0.633). CONCLUSIONS: The minilaparotomy approach was similarly safe and oncologically equivalent to laparoscopic approach for patients with rectal cancer. At the expense of a longer operative time and higher cost, laparoscopic surgery was associated with faster postoperative recovery.

Upregulation of microRNA-155 promotes the migration and invasion of colorectal cancer cells through the regulation of claudin-1 expression.

Human microRNA-155 (miR-155) has been demonstrated to regulate a variety of cellular functions, including epithelial-to-mesenchymal transition (EMT) by targeting multiple messenger RNAs (mRNAs). However, its role in colorectal cancer (CRC) remains unelucidated. Therefore, the aim of the present study was to investigate the effects of miR-155 on CRC cells. The expression level of miR-155 was quantified by quantitative real-time reverse transcriptase-PCR (qRT-PCR) in primary CRC tissues and normal adjacent mucosa. MTT, migration and invasion assays were used to examine the proliferation, migration and invasion of SW480 cells transfected with miR­155. The expression of miR-155 was significantly upregulated in the CRC tissues and the high expression of miR-155 correlated with an advanced clinical stage, lymph node and distant metastases. The ectopic expression of miR-155 enhanced the migration and invasive ability of the SW480 cells and altered their morphological appearance; however, cell proliferation was not affected. E-cadherin expression levels decreased, while ZEB1 expression levels increased in the SW480 cells overexpressing miR-155. Furthermore, the overexpression of miR-155 upregulated claudin-1 expression. Thus, our data suggest that miR-155 plays an important role in promoting CRC cell migration and invasion, at least in part through the regulation of claudin-1 expression and controlling metastasis in CRC.

High expression of ZEB1 correlates with liver metastasis and poor prognosis in colorectal cancer.

Zinc finger E-box binding homeobox 1 (ZEB1) has been shown to promote invasion and metastasis in several types of human cancer and to have a prognostic role in certain cancers. However, the clinical significance of ZEB1 in colorectal cancer (CRC) has not been sufficiently investigated. This study aimed to address this issue. In this study, we compared the expression of ZEB1 between CRC tissues and normal adjacent mucosa using quantitative real-time RT-PCR. The association of ZEB1 expression with clinicopathological characteristics was analyzed by appropriate statistical analyses. Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the association of ZEB1 expression with survival of patients. The results showed that the relative expression levels of ZEB1 were significantly higher in CRC tissues compared to the normal adjacent mucosa and higher expression of ZEB1 correlated with liver metastasis. Kaplan-Meier analysis indicated that patients with high ZEB1 had a poor overall survival. Moreover, the multivariate analysis showed that high expression of ZEB1 was an independent predictor of overall survival. Our data indicate the potential of ZEB1 as a novel prognostic biomarker for CRC.

Overexpression of miR-92a correlates with tumor metastasis and poor prognosis in patients with colorectal cancer.

OBJECTIVES: MicroRNAs regulate gene expression at the post-transcriptional level and play important roles in cancer development, progression, and metastasis. The aim of this study was to investigate the expression of miR-92a in colorectal cancer and the normal adjacent mucosa and its potential relevance to clinicopathological characteristics and patient survival. METHODS: Surgical specimens of cancer tissue and adjacent normal mucosa were obtained from 82 patients with colorectal carcinomas. The relative expression levels of miR-92a mRNA in the cancer and the normal adjacent mucosa were measured by quantitative real-time reverse transcriptase polymerase chain reaction. We analyzed their correlation with tumor metastasis, clinicopathologic parameters, and clinical outcome. RESULTS: The relative expression levels of miR-92a were significantly higher in colorectal cancer tissues than in the normal adjacent mucosa (p < 0.001), and a high expression of miR-92a correlated with advanced clinical stage (p = 0.025), lymph node metastases (p = 0.015), and distant metastases (p = 0.046). Kaplan-Meier analysis indicated that patients with high miR-92a expression had a poor overall survival (p = 0.001). Moreover, multivariate analysis showed that increased expression of miR-92a was an independent predictor of overall survival. CONCLUSION: This study revealed that miR-92a overexpression was correlated with specific colorectal cancer biopathologic features, such as TNM stage, lymph node and distant metastases, and poor survival of the patients, indicating that miR-92a may serve as a molecular prognostic marker for colorectal cancer and disease progression.

Plasma miR-200c and miR-18a as potential biomarkers for the detection of colorectal carcinoma.

It has been demonstrated that there are abundant stable microRNAs (miRNAs) in plasma/serum, which can be detected and are potentially disease-specific. The aim of this study was to investigate whether plasma miR-200c and miR-18a can be used as biomarkers for the detection of colorectal carcinoma (CRC). This study was divided into three parts: i) confirmation of higher miR-200c and miR-18a levels in primary CRC tissues compared to normal colorectal tissues; ii) evaluation of plasma miR-200c and miR-18a expression by comparing 78 patients with 86 healthy volunteers and iii) comparison of miR-200c and miR-18a levels in paired pre-and post-operative plasma in cancer patients who underwent curative CRC resection. Results showed that the expression of miR-200c and miR-18a was significantly higher in CRC compared to normal tissues. The plasma levels of miR-200c and miR-18a were significantly higher in CRC patients compared to controls. miR-200c yielded an area under the receiver-operating characteristics (ROC) curve (AUC) of 0.749 and miR-18a yielded an AUC of 0.804 when distinguishing CRC patients from the controls. Combined ROC analyses using the two miRNAs revealed an elevated AUC of 0.839 with 84.6% sensitivity and 75.6% specificity in discriminating CRC. Plasma levels of miR-200c and miR-18a were significantly lower in post-operative compared to pre-operative samples. The results of this study suggest that plasma miR-200c and miR-18a are significantly elevated in the plasma of CRC patients and that they may serve as non-invasive molecular markers for CRC screening.

Clinical significance of miR-22 expression in patients with colorectal cancer.

MicroRNAs (miRNAs) are non-coding RNAs that have been shown to be aberrantly expressed in several tumor types. Of these miRNAs, miR-22 as tumor suppressor has been shown to play a crucial role in human carcinogenesis. However, its association with the clinicopathological features of colorectal cancer has yet to be addressed. In this study, we compared the expression of miR-22 between colorectal cancer tissues and the normal adjacent mucosa using a quantitative real-time RT-PCR. The association of miR-22 expression with clinicopathological characters was analyzed by appropriate statistical analysis. Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the associations of miR-22 expression with survival of patients. Results showed that the relative expression levels of miR-22 were significantly lower in colorectal cancer tissues than those in the normal adjacent mucosa, and low expression of miR-22 correlated with liver metastasis. Kaplan-Meier analysis indicated that patients with reduced miR-22 had a poor overall survival. Moreover, the multivariate analysis showed that reduced expression of miR-22 was an independent predictor of overall survival. Our data indicate the potential of miR-22 as a novel prognostic biomarker for CRC.