Implications of the histological determination of microRNAs in the screening, diagnosis and prognosis of colorectal cancer

High microRNA-28-5p expression in colorectal adenocarcinoma predicts short-term relapse of node-negative patients and poor overall survival of patients with non-metastatic disease

BACKGROUND

MicroRNAs (miRNAs) may function either as oncogenes or tumor suppressors and are heavily involved in the initiation and progression of cancer, and in metastasis of tumor cells. MicroRNA-28-5p (miR-28-5p) targets several cancer-related genes and is hence involved in cell proliferation, migration, invasion and epithelial-mesenchymal transition. In this study, we investigated the potential diagnostic and prognostic significance of miR-28-5p expression in colorectal adenocarcinoma, the most frequent type of colorectal cancer (CRC).

METHODS

Therefore, we isolated total RNA from 182 colorectal adenocarcinoma specimens and 86 paired non-cancerous colorectal mucosae. After polyadenylation of 2 μg total RNA and its reverse transcription using an oligo-dT-adapter primer, we quantified miR-28-5p levels using an in-house-developed reverse-transcription real-time quantitative polymerase chain reaction (RT-qPCR) method, based on the SYBR Green chemistry.

RESULTS

Comparison of miR-28-5p levels among 86 pairs of colorectal tumors and their adjacent non-cancerous mucosae uncovered the downregulation of miR-28-5p expression in the majority of malignant colorectal tumors. More importantly, high miR-28-5p expression predicts poor disease-free survival (DFS) and overall survival (OS) of colorectal adenocarcinoma patients. Multivariate Cox regression analysis revealed that miR-28-5p overexpression is a significant predictor of poor prognosis in colorectal adenocarcinoma, independent of tumor size, histological grade, TNM staging, radiotherapy and chemotherapy. Interestingly, strong miR-28-5p expression retains its predictive potential regarding relapse among patients with negative regional lymph nodes, and predicts poor OS in patients diagnosed with non-metastatic colorectal adenocarcinoma.

CONCLUSIONS

High miR-28-5p expression predicts poor DFS and OS of colorectal adenocarcinoma patients, independently of clinicopathological prognosticators and standard patient treatment, including radiotherapy and chemotherapy.

miR-15a-5p, A Novel Prognostic Biomarker, Predicting Recurrent Colorectal Adenocarcinoma

INTRODUCTION

Colorectal cancer is one of the most common gastrointestinal diseases and the second leading cause of cancer-associated deaths among adults. miR-15a-5p is a post-transcriptional regulator of the proto-oncogene MYB, a transcription factor essential for prolonged cancer cell proliferation and survival. In the current study, we assessed the potential diagnostic and prognostic utility of miR-15a-5p expression in colorectal adenocarcinoma.

METHODS

To accomplish this goal, total RNA was extracted from 182 colorectal adenocarcinoma specimens and 86 non-cancerous colorectal mucosae. After polyadenylation by poly(A) polymerase and subsequent reverse transcription with an oligo-dT adapter primer, miR-15a-5p expression was analyzed using an in-house developed reverse transcription quantitative real-time PCR method, based on SYBR Green chemistry. SNORD43 (RNU43) was used as an internal control gene.

RESULTS

miR-15a-5p was significantly upregulated in colorectal tumors compared to non-cancerous colorectal mucosae, while ROC analysis suggested its potential use for diagnostic purposes. Moreover, miR-15a-5p overexpression predicts poor disease-free survival (DFS) and overall survival (OS). Multivariate Cox regression analysis confirmed that miR-15a-5p overexpression is a significant unfavorable prognosticator of DFS in colorectal adenocarcinoma, independent of other established prognostic factors plus treatment of patients. Importantly, miR-15a-5p overexpression retains its unfavorable prognostic value in patients with T3 colorectal adenocarcinoma and in those without distant metastasis (M0). More importantly, the cumulative DFS probability of patients with early stage disease was significantly lower for those with colorectal adenocarcinoma overexpressing miR-15a-5p.

DISCUSSION

In conclusion, elevated expression of the cancer-associated miR-15a-5p predicts poor DFS and OS of colorectal adenocarcinoma patients. The prognostic value of miR-15a-5p expression regarding DFS is independent of clinicopathological factors currently used for colorectal adenocarcinoma prognosis.

High expression of miR-181c as a predictive marker of recurrence in stage II colorectal cancer

INTRODUCTION

A standard treatment for stage II colorectal cancer (CRC) is surgical resection without adjuvant chemotherapy. However, the recurrence rate of these patients is approximately 20%. To date, there are no robust biomarkers suitable for predicting recurrence in stage II CRC patients. In this study, microRNAs (miRNAs) extracted from CRC tissues were examined for a possible biomarker to predict recurrence in stage II CRC patients.

RESULTS

From the comprehensive analysis, 15 miRNAs were selected as candidates for further study. Regarding let-7a, -7d, -7e, miR-23c, -26b, -128a, -151-5p, and -181c, recurrence rates in training cohort patients with higher expression of these miRNAs isolated from their frozen tissues samples were significantly higher than those with lower expression (P < 0.05). According to multivariate analysis, the higher expression of miR-181c was detected as an independent predictive factor of recurrence (P = 0.001, OR: 9.43, 95% CI: 2.57–34.48). Results were similar in miR-181c extracted from FFPE tissues obtained from the training cohort (P = 0.003, OR: 7.46, 95% CI: 1.97–28.57). In the validation cohort using FFPE tissues, the recurrence rate in patients with higher miR-181c expression was significantly higher than those with lower miR-181c expression (P < 0.001).

MATERIAL AND METHODS

Comprehensive analysis using a highly sensitive miRNA chip was initially performed to select candidate miRNAs associated with recurrence. Candidate miRNAs were analyzed by real-time RT-PCR using RNA from frozen and formalin-fixed, paraffin-embedded (FFPE) tissues.

CONCLUSIONS

Higher expression of miR-181c may be a useful recurrence predictor of stage II CRC patients.

miR-34a overexpression predicts poor prognostic outcome in colorectal adenocarcinoma, independently of clinicopathological factors with established prognostic value

OBJECTIVES

MicroRNA-34a (miR-34a) is regulated by TP53 and, in response, downregulates the expression of a gamut of protein-coding genes, including apoptosis regulators, transcription factors, cyclins, and cyclin-dependent kinases. Its upregulation initiates a reprogramming of gene expression and promotes apoptosis. The purpose of this study was the investigation of the potential clinical significance of miR-34a as a molecular prognostic biomarker in colorectal adenocarcinoma using an in-house real-time quantitative PCR (qPCR) methodology.

DESIGN AND METHODS

Total RNA was extracted from 113 primary colorectal adenocarcinoma specimens and 61 paired non-cancerous colorectal tissue samples. After polyadenylation and reverse transcription, miR-34a molecules were determined using qPCR based on SYBR Green chemistry. Calculations were performed using the comparative C_T method. Finally, extensive biostatistical analysis was performed.

RESULTS

miR-34a expression does not significantly differ between colorectal adenocarcinoma tissue specimens and adjacent non-cancerous mucosae. However, miR-34a expression increases progressively as colorectal adenocarcinoma loses its differentiation, being highest in grade III tumors (P=0.010). Moreover, miR-34a expression is a potential unfavorable prognostic biomarker in colorectal adenocarcinoma, predicting poor disease-free and overall survival (P=0.002 and P=0.019, respectively), independently of classical clinicopathological parameters. Most importantly, miR-34a expression stratifies patients without local (N0) and/or distant metastasis (M0) at the time of diagnosis into two groups with substantially different prognosis (P=0.013 and P=0.002, respectively).

CONCLUSIONS

High miR-34a levels in colorectal adenocarcinoma predict a rather increased risk for disease recurrence and poor overall survival, particularly in patients at an early TNM stage. The unfavorable prognostic potential of miR-34a expression is independent of established prognostic features of colorectal adenocarcinoma.

High miR-96 levels in colorectal adenocarcinoma predict poor prognosis, particularly in patients without distant metastasis at the time of initial diagnosis

MicroRNA-96 (miR-96) is an oncomiR that facilitates the development of malignant tumors by promoting growth, proliferation, and survival of cancer cells. Previous studies using high-throughput techniques have shown that miR-96 is upregulated in colorectal cancer compared to adjacent normal colorectal tissue. The aim of this study was the investigation of the potential clinical value of miR-96 as a molecular prognostic biomarker in colorectal adenocarcinoma. For this purpose, total RNA was extracted from 108 primary colorectal adenocarcinoma samples and 54 paired non-cancerous colorectal tissue specimens. After polyadenylation and reverse transcription, miR-96 molecules were determined using an in-house developed real-time quantitative PCR based on SYBR Green chemistry. Calculations were carried out with the comparative C_T method, using SNORD48 as endogenous reference gene. Finally, extensive biostatistical analysis was performed and showed that miR-96 is significantly upregulated in colorectal adenocarcinoma specimens compared to their non-cancerous counterparts (p < 0.001) as well as in tumors having invaded regional lymph nodes (p = 0.009) and those of advanced TNM stage (p = 0.008). miR-96 expression is an unfavorable prognostic marker in colorectal adenocarcinoma, predicting poor disease-free and overall survival (p = 0.041 and 0.028, respectively), independently of classical clinicopathological parameters. Most importantly, miR-96 expression stratifies patients without distant metastasis (M0) at the time of diagnosis into two groups with substantially different prognosis (p = 0.040). In conclusion, high tissue levels of miR-96 are associated with advanced stages of colorectal adenocarcinoma and predict an increased risk for disease recurrence and poor overall survival, especially in patients without distant metastasis at the time of diagnosis.

MiR-score: a novel 6-microRNA signature that predicts survival outcomes in patients with malignant pleural mesothelioma

BACKGROUND

Prognosis of malignant pleural mesothelioma (MPM) is poor, and predicting the outcomes of treatment is difficult. Here we investigate the potential of microRNA expression to estimate prognosis of MPM patients.

METHODS

Candidate microRNAs from microarray profiling of tumor samples from 8 long (median: 53.7 months) and 8 short (median: 6.4 months) survivors following extrapleural pneumonectomy (EPP) were validated by RT-qPCR in 48 additional EPP samples. Kaplan-Meier log ranking was used to further explore the association between microRNA expression and overall survival (OS). Binary logistic regression was used to construct a microRNA signature (miR-Score) that was able to predict an OS of ≥20 months. Performance of the miR-Score was evaluated by receiver operating characteristic (ROC) curve analysis and validated in a series of 43 tumor samples from patients who underwent palliative surgery [pleurectomy/decortication (P/D)].

RESULTS

The miR-Score, using expression data of six microRNAs (miR-21-5p, -23a-3p, -30e-5p, -221-3p, -222-3p, and -31-5p), enabled prediction of long survival with an accuracy of 92.3% for EPP and 71.9% for palliative P/D. Hazard ratios for score-negative patients were 4.12 (95% CI: 2.03-8.37) for EPP and 1.93 (95% CI: 1.01-3.69) for P/D. Importantly, adding the miR-Score to a set of clinical selection criteria (histology, age, gender) increased predictive accuracy in the independent validation set from 76.3% for clinical factors only to 87.3%.

CONCLUSIONS

This study has identified a novel 6-microRNA signature (miR-Score) that can accurately predict prognosis of MPM patients.

miR-224 overexpression is a strong and independent prognosticator of short-term relapse and poor overall survival in colorectal adenocarcinoma

Colorectal adenocarcinoma constitutes the most frequent form of colorectal cancer and a serious cause of cancer-related deaths. The expression of multiple miRNAs, including miR-224, is deregulated in colorectal adenocarcinoma. The aim of this study was the investigation of the prognostic value of miR-224 in colorectal adenocarcinoma. For this purpose, total RNA was isolated from 115 colorectal adenocarcinomas and 66 adjacent non-cancer mucosae. Total RNA (2 µg) was polyadenylated and reverse transcribed. A quantitative PCR method based on SYBR-Green chemistry was developed and applied for the quantification of miR-224 levels, followed by extensive biostatistical analysis. miR-224 levels in malignant colorectal adenocarcinomas ranged between 1.81 and 187.75 RQU (miR-224 copies/1,000 SNORD48 copies) with a median of 34.27, and were significantly elevated, compared to miR-224 levels in adjacent non-cancer mucosae (p<0.001). Enhanced miR-224 expression constitutes a rather strong prognosticator in colorectal adenocarcinoma, predicting short-term relapse and poor overall survival in these patients (p=0.012 and p=0.005, respectively), independent of established clinicopathological parameters. In conclusion, miR-224 is significantly upregulated in malignant colorectal tumors compared to adjacent non-cancer mucosae, and its enhanced expression constitutes an independent predictor of short-term relapse and poor overall survival in colorectal adenocarcinoma patients.

The fusion of two worlds: non-coding RNAs and extracellular vesicles--diagnostic and therapeutic implications (Review)

The role of the extracellular non-coding RNAs, particularly microRNAs present in tumor-derived extravesicles, has been intensively exploited in human cancer as a promising tool for diagnostic and prognostic purposes. Current knowledge on exosomes shows an important role not only as vehicles in the intercellular communication, but the transfer of their content can specifically modulate the surrounding microenvironment, leading to tumor development and progression and affecting therapy response. Based on this, much effort has focused on understanding the mechanisms behind the biology of exosomes and their closely interaction with non-coding RNAs as an efficient tool in tumor diagnostic and therapy. Here we summarize the current knowledge on extracellular and exosomes-enclosed non-coding RNAs, and their importance as potential biomarkers and mediators of intercellular communication in tumor biology.

Role of micro-RNA in colorectal cancer screening

MicroRNAs are involved in carcinogenesis through postranscriptional gene regulatory activity. These molecules are involved in various physiological and pathological functions, such as apoptosis, cell proliferation and differentiation, which indicates their functionality in carcinogenesis as tumour suppressor genes or oncogenes. Several studies have determined the presence of microRNAs in different neoplastic diseases such as colon, prostate, breast, stomach, pancreas, and lung cancer. There are promising data on the usefulness of quantifying microRNAs in different organic fluids and tissues. We have conducted a review of the determinations of microRNAs in the diagnosis of colorectal cancer.

miR-181 subunits enhance the chemosensitivity of temozolomide by Rap1B-mediated cytoskeleton remodeling in glioblastoma cells

Glioblastoma multiforme (GBM) is the most malignant and frequent brain tumor, with an aggressive growth pattern and poor prognosis despite best treatment modalities. Although chemotherapy with temozolomide (TMZ) may restrain tumor growth for some months, TMZ resistance is also common and accounts for many treatment failures. Research into microRNA's role in GBM has shown that microRNAs play a key regulatory role in the GBM, making it a potential therapeutic target. In this study, we demonstrated that the lower expression of miR-181a/b/c/d subunits contributes to astrocytoma tumorigenesis, and their overexpression could inhibit the invasive proliferation of glioblastoma cells by targeting Rap1B-mediated cytoskeleton remodeling and related molecular (Cdc42, RhoA and N-cadherin) changes, suggesting that miR-181 was a critical regulator and might be an important target for glioblastoma treatment. TMZ as a standard chemotherapeutic agent for GBM inhibited the Rap1B expression and actin cytoskeleton remodeling to exert its cell killing by upregulating miR-181a/b/c/d subunits; conversely, each miR-181a/b/c/d subunit enhanced the chemosensitivity of TMZ in glioblastoma cells.