I-Ping Yang

MicroRNA-93 inhibits tumor growth and early relapse of human colorectal cancer by affecting genes involved in the cell cycle

PURPOSE Colorectal cancer (CRC) is associated with high recurrence and mortality. Because deregulation of microRNAs is associated with CRC development and recurrence, the expression levels of microRNAs can be a simple and reliable biomarker to detect postoperative early relapse, thereby helping physicians to treat high-risk patients more efficiently. EXPERIMENTAL DESIGN We used microRNA arrays and observed that microRNA-93 had substantially different expression levels in early (recurrence within 12 months after surgery) and non-early relapse CRC patients. The replication study, which included 35 early relapse and 42 non-early relapse subjects, further confirmed overexpression of microRNA-93 in non-early relapse samples. The in vitro and in vivo effects of microRNA-93 were investigated by examining cell proliferation, migration and invasion, as well as cell cycles, target-gene expression and xenograft in null mice. RESULTS Cellular studies showed that the overexpression of microRNA-93 inhibited colon cancer cell proliferation and migration but not invasion. The cell cycle studies also revealed that microRNA-93 caused an accumulation of the G2 population. However, microRNA-93 could not induce cell apoptosis or necrosis. Functional studies showed that microRNA-93 could suppress CCNB1 protein expression leading to cell cycle arrest in the G2 phase. Moreover, microRNA-93 repressed expression of ERBB2, p21 and VEGF, all of which are involved in cell proliferation. MicroRNA-93 also suppressed tumor growth in null mice. CONCLUSIONS This study showed that microRNA-93 can inhibit tumorigenesis and reduce the recurrence of CRC; these findings may have potential clinical applications for predicting the recurrence of CRC.

Computational Analysis of mRNA Expression Profiles Identifies MicroRNA-29a/c as Predictor of Colorectal Cancer Early Recurrence

Colorectal cancer (CRC) is one of the leading malignant cancers with a rapid increase in incidence and mortality. The recurrences of CRC after curative resection are sometimes unavoidable and often take place within the first year after surgery. MicroRNAs may serve as biomarkers to predict early recurrence of CRC, but identifying them from over 1,400 known human microRNAs is challenging and costly. An alternative approach is to analyze existing expression data of messenger RNAs (mRNAs) because generally speaking the expression levels of microRNAs and their target mRNAs are inversely correlated. In this study, we extracted six mRNA expression data of CRC in four studies (GSE12032, GSE17538, GSE4526 and GSE17181) from the gene expression omnibus (GEO). We inferred microRNA expression profiles and performed computational analysis to identify microRNAs associated with CRC recurrence using the IMRE method based on the MicroCosm database that includes 568,071 microRNA-target connections between 711 microRNAs and 20,884 gene targets. Two microRNAs, miR-29a and miR-29c, were disclosed and further meta-analysis of the six mRNA expression datasets showed that these two microRNAs were highly significant based on the Fisher p-value combination (p = 9.14×10−9 for miR-29a and p = 1.14×10−6 for miR-29c). Furthermore, these two microRNAs were experimentally tested in 78 human CRC samples to validate their effect on early recurrence. Our empirical results showed that the two microRNAs were significantly down-regulated (p = 0.007 for miR-29a and p = 0.007 for miR-29c) in the early-recurrence patients. This study shows the feasibility of using mRNA profiles to indicate microRNAs. We also shows miR-29a/c could be potential biomarkers for CRC early recurrence.

The functional significance of microRNA-29c in patients with colorectal cancer: a potential circulating biomarker for predicting early relapse.

Background The recurrence of colorectal cancer (CRC) is frequent within the first year of curative resection surgery and may be unavoidable. microRNAs have been suggested to play roles in carcinogenesis and cancer recurrence. We recently identified microRNA-29c (miRNA-29c) as a predictor of early recurrence in CRC. In the present study, we further investigated the functions and serum level of miRNA-29c in relation to early recurrence of CRC. Methods First we further confirmed overexpression of miRNA-29c in non-early relapse subjects. Gain-of-function in vitro studies were used to evaluate the effect of miRNA-29c on cell proliferation, migration, invasion, and cell cycle progression. The colon cancer cell line Caco2 and a stable clone overexpressing miRNA-29c were xenografted to evaluate the in vivo effect of miRNA-29c in null mice. Finally, circulating miRNA-29c was investigated as a potential biomarker for identifying early relapse. Results miRNA-29c expression significantly decreased during early relapse compared to non-early relapse in UICC stage II and III CRC patients (P = 0.021). In vitro studies showed that overexpression of miRNA-29c inhibited cell proliferation and migration. The cell cycle studies also revealed that miRNA-29c caused an accumulation of the G1 and G2 population. In vivo, miRNA-29c suppressed tumor growth in null mice. The serum miRNA-29c increased significantly in early relapsed patients compared to non-early elapsed patients (P = 0.012). Conclusions miRNA-29c shows anti-tumorigenesis activity, and preoperative circulating miRNA-29c levels can be used to predict postoperative early relapse of CRC.

Predictive value of vascular endothelial growth factor overexpression in early relapse of colorectal cancer patients after curative resection

BackgroundPreclinical and clinical studies have indicated that vascular endothelial growth factor (VEGF) is the predominant angiogenic factor. Recently, there was a consistent trend of poorer survival rates in colorectal cancer (CRC) patients of earlier relapse. The purpose of this study was to investigate novel predictors of early relapse in stage I–III CRC and further to determine their correlation with disease outcomes.Materials and methodsWe retrospectively analyzed clinicopathological features and VEGF expression by immunohistochemical staining in 100 stage I–III CRC patients undergoing curative resection to identify predictors of postoperative early relapse.ResultsAmong 100 patients, 40 patients were classified into early relapse group, and 60 patients were categorized into non-early relapse group. A multivariate logistic regression analysis showed that vascular invasion (P = 0.048), perineural invasion (P = 0.042), VEGF overexpression (P = 0.023), and high postoperative carcinoembryonic antigen (CEA) levels (P = 0.004) were independent predictors of early relapse. Additionally, we found that with more predictors such as the combined incidence of vascular invasion, perineural invasion, VEGF overexpression, and postoperative CEA levels are involved, the incidence of early postoperative relapse increases. Moreover, VEGF overexpression predicted not only early postoperative relapse but also disease-free survival (P < 0.001) and overall survival (P = 0.002).ConclusionsThis study suggests that VEGF overexpression is an important predictor of early postoperative relapse in patients with stage I–III CRC and may help identify patients who would benefit from intensive follow-up and therapeutic programs.

High blood sugar levels significantly impact the prognosis of colorectal cancer patients through down-regulation of microRNA-16 by targeting Myb and VEGFR2

The high prevalence of type 2 diabetes mellitus in colorectal cancer patients is a crucial public health issue worldwide. The deregulation of microRNAs has been shown to be associated with the progression of CRC; however, the effects of high blood sugar levels on miR deregulation and, in turn, CRC remain unexplored. In this study, 520 CRC patients were classified into two groups according to their blood sugar levels (≧110 or <110 mg/dL). Clinicopathologic features, clinical outcomes, and serum miR-16 levels of the two groups were then analyzed, while cell cycles, cell proliferation, migration, and cellular miR-16 expression were investigated via D-(+)-glucose administration. Additionally, the target genes of miR-16 were identified. Through multivariate analysis, both the disease-free survival and overall survival of the CRC patients were found to be associated with the UICC stage, perineural invasion, and blood glucose levels (P < 0.05). Serum miR-16 levels were significantly lower in the high blood glucose patients than in the normal blood glucose patients (P = 0.0329). With D-(+)-glucose administration, the proliferation and migration of CRC cells in vitro increased remarkably (P < 0.05), while their accumulation in the G1 phase decreased significantly. Cellular miR-16 expression was suppressed by D-(+)-glucose administration. The expression levels of two target genes, Myb and VEGFR2, were affected significantly by miR-16, while glucose administration inhibited miR-16 expression and enhanced tumor cell proliferation and migration. Hyperglycemia can impact the clinical outcomes of CRC patients, likely by inhibiting miR-16 expression and the expression of its downstream genes Myb and VEGFR2.

Co-existence of cyclin D1 and vascular endothelial growth factor protein expression is a poor prognostic factor for UICC stage I-III colorectal cancer patients after curative resection.

Angiogenesis plays an important role in the progression of colorectal cancer (CRC). Studies have indicated vascular endothelial growth factor (VEGF) is the predominant angiogenic factor. Cyclin D1 (CCND1) induces production of VEGF and is required for migration of blood vessels. Our aim was to determine the roles of CCND1 and VEGF overexpression in CRC patients.

Factors affecting number of lymph nodes harvested and the impact of examining a minimum of 12 lymph nodes in stage I-III colorectal cancer patients: a retrospective single institution cohort study of 1167 consecutive patients.

BackgroundTo identify factors affecting the harvest of lymph nodes (LNs) and to investigate the association between examining a minimum of 12 LNs and clinical outcomes in stage I-III colorectal cancer (CRC) patients.MethodsThe clinicopathologic features and the number of examined LNs for 1167 stage I-III CRC patients were analyzed to identify factors affecting the number of LNs harvested and the correlations between clinical outcomes and high harvests (≧12 LNs) and low harvests (<12 LNs).ResultsA multivariate analysis showed that age (P = 0.007), tumor size (P = 0.030), and higher T stage (P = 0.001) were independent factors affecting the examinations of LNs in colon cancer and that tumor size (P = 0.015) was the only independent factor in rectal cancer. Patients with low harvests had poorer overall survival with stage II and stage III CRC (stage II: P < 0.0001; III: P = 0.001) and poorer disease-free survival for stages I-III (stage I: P = 0.023; II: P < 0.0001; III: P = 0.001).ConclusionsThe factors influencing nodal harvest are multifactorial, and an adequate number of examined LNs (≧12) is associated with a survival benefit. Removal of at least 12 LNs will determine the lymph node status reliably.

Tumorigenesis and tumor progression related gene expression profiles in colorectal cancer

BACKGROUND To investigate the different gene expression profiles in colorectal cancer (CRC) has important implications in understanding the correlation between candidate genes and clinical histopathological features, as well as in developing prognostic prediction markers. OBJECTIVE The purpose of this study was to identify the expression profiles of tumorigenesis and tumor progression related genes in Taiwanese CRC patients. METHODS In this study, we analyze 18 candidate gene expressions of 77 CRC tissues by a GeXP multiplexed assay. RESULTS The results showed VEGF (71.4%), SOX9 (68.8%), MYC (62.3%), CCND1 (59.7%), TP53 (59.4%), MMP9 (53.3%), and BIRC5 (50.6%) as significantly overexpressed genes in CRC tissues. VEGF was the most highly overexpressed gene. In addition, VEGF was overexpressed in larger tumors (P=0.037, OR=2.981, 95% CI, 1.049-8.477). MMP9 overexpression was correlated to deeper tumor invasion (P=0.001, OR=11.022, 95% CI, 2.281-53.262), and BIRC5 was overexpressed in the presence of perineural invasion (P=0.026, OR=4.250, 95% CI, 1.240-14.562). CONCLUSIONS The results of this study offered valuable information about the relationship between different gene expressions and clinical pathological features, and these biomarkers represent a potential role for CRC prognosis prediction and establishing therapeutic strategies.

The Association between DNA Copy Number Aberrations at Chromosome 5q22 and Gastric Cancer

Background Gastric cancer is common cancer. Discovering novel genetic biomarkers might help to identify high-risk individuals. Copy number variation (CNV) has recently been shown to influence risk for several cancers. The aim of the present study was sought to test the association between copy number at a variant region and GC. Methods A total of 110 gastric cancer patients and 325 healthy volunteers were enrolled in this study. We searched for a CNV and found a CNV (Variation 7468) containing part of the APC gene, the SRP19 gene and the REEP5 gene. We chose four probes targeting at APC-intron8, APC-exon9, SRP19 and REEP5 to interrogate this CNV. Specific Taqman probes labeled by different reporter fluorophores were used in a real-time PCR platform to obtain copy number. Both the original non-integer data and transformed integer data on copy number were used for analyses. Results Gastric caner patients had a lower non-integer copy number than controls for the APC-exon9 probe (Adjusted p = 0.026) and SRP19 probe (Adjusted p = 0.002). The analysis of integer copy number yielded a similar pattern although less significant (Adjusted p = 0.07 for APC-exon9 probe and Adjusted p = 0.02 for SRP19 probe). Conclusions Losses of a CNV at 5q22, especially in the DNA region surrounding APC-exon 9, may be associated with a higher risk of gastric cancer.