Marek Svoboda

Altered Expression of miR-21, miR-31, miR-143 and miR-145 Is Related to Clinicopathologic Features of Colorectal Cancer

Objectives: Development and metastases of colorectal cancer (CRC) are characterized by multiple genetic alterations. MicroRNAs (miRNAs) are endogenously expressed regulatory noncoding RNAs. Previous, mainly preclinical studies showed altered expression levels of several miRNAs in CRC. Methods: In our study, the expression levels of miR-21, miR-31, miR-143 and miR-145 in 29 primary colorectal carcinomas and 6 non-tumor adjacent tissue specimens were examined by real-time polymerase chain reaction. miRNA expression levels were also correlated with commonly used clinicopath-ologic features of CRC. Results: Expression levels of analyzed miRNAs significantly differed among tumors and adjacent non-tumor tissues: miR-21 (p = 0.0001) and miR-31 (p = 0.0006) were upregulated, and miR-143 (p = 0.011) and miR-145 (p = 0.003) were downregulated in tumors. For the first time, a high expression of miR-21 was associated with lymph node positivity (p = 0.025) and the development of distant metastases (p = 0.009) in CRC patients. Thus, expression of miR-21 correlated with CRC clinical stage (p = 0.032). Furthermore, tumors >50 mm in maximal tumor diameter were characterized by lower expression of miR-143 (p = 0.006) and miR-145 (p = 0.003). We found no correlation between analyzed miRNAs and serum levels of carcinoembryonic antigen. Conclusion: Our results suggest possible roles of miR-21, miR-31, miR-143 and miR-145 in CRC.

Circulating miR-378 and miR-451 in serum are potential biomarkers for renal cell carcinoma

BackgroundThere is no standard serum biomarker used for diagnosis or early detection of recurrence for renal cell carcinoma (RCC) patients. MicroRNAs (miRNAs) are abundant and highly stable in blood serum, and have been recently described as powerful circulating biomarkers in a wide range of solid cancers. Our aim was to identify miRNA signature that can distinguish the blood serum of RCC patients and matched healthy controls and validate identified miRNAs as potential biomarkers for RCC.MethodsIn the screening phase of the study, blood serum of 15 RCC patients and 12 matched healthy controls were analyzed by use of the TaqMan Low-Density Arrays enabling parallel identification of expression levels of 667 miRNAs through qRT-PCR-based approach. In the validation phase, identified miRNAs were further evaluated on the independent group of 90 RCC patients and 35 matched healthy controls by use of individual qRT-PCR assays and statistically evaluated.ResultsWe identified 30 miRNAs differentially expressed between serum of RCC patients and healthy controls: 19 miRNAs were up-regulated and 11 miRNAs were down-regulated in RCC patients. MiR-378, miR-451 and miR-150 were further evaluated in the independent group of patients, and two of them were successfully validated: levels of miR-378 were increased (p = 0.0003, AUC = 0.71), miR-451 levels were decreased (p < 0.0001, AUC = 0.77) in serum of RCC patients. Combination of miR-378 and miR-451 enable identification of RCC serum with the sensitivity of 81%, specificity 83% and AUC = 0.86.ConclusionsCirculating miRNAs in serum are promising biomarkers in RCC.

Novel classes of non-coding RNAs and cancer

For the many years, the central dogma of molecular biology has been that RNA functions mainly as an informational intermediate between a DNA sequence and its encoded protein. But one of the great surprises of modern biology was the discovery that protein-coding genes represent less than 2% of the total genome sequence, and subsequently the fact that at least 90% of the human genome is actively transcribed. Thus, the human transcriptome was found to be more complex than a collection of protein-coding genes and their splice variants. Although initially argued to be spurious transcriptional noise or accumulated evolutionary debris arising from the early assembly of genes and/or the insertion of mobile genetic elements, recent evidence suggests that the non-coding RNAs (ncRNAs) may play major biological roles in cellular development, physiology and pathologies. NcRNAs could be grouped into two major classes based on the transcript size; small ncRNAs and long ncRNAs. Each of these classes can be further divided, whereas novel subclasses are still being discovered and characterized. Although, in the last years, small ncRNAs called microRNAs were studied most frequently with more than ten thousand hits at PubMed database, recently, evidence has begun to accumulate describing the molecular mechanisms by which a wide range of novel RNA species function, providing insight into their functional roles in cellular biology and in human disease. In this review, we summarize newly discovered classes of ncRNAs, and highlight their functioning in cancer biology and potential usage as biomarkers or therapeutic targets.

MiR-195, miR-196b, miR-181c, miR-21 expression levels and O-6-methylguanine-DNA methyltransferase methylation status are associated with clinical outcome in glioblastoma patients

Glioblastoma multiforme (GBM) is the most frequently occurring primary malignant brain tumor; patients with GBM often have a very poor prognosis and differing responses to treatment. Therefore, it is very important to find new biomarkers that can predict clinical outcomes and help in treatment decisions. MicroRNAs are small, non‐coding RNAs that function as post‐transcriptional regulators of gene expression and play a key role in the pathogenesis of GBM. In a group of 38 patients with primary GBM, we analyzed the expression of eight microRNAs (miR‐21, miR‐128a, miR‐181c, miR‐195, miR‐196a, miR‐196b, miR‐221, and miR‐222). In addition, we examined the methylation status of O‐6‐methylguanine‐DNA methyltransferase (MGMT) promoter by high‐resolution melting analysis, as this has been shown to be a predictive marker in GBM. MGMT methylation status correlated with progression‐free survival (P = 0.0201; log–rank test) as well as with overall survival (P = 0.0054; log–rank test). MiR‐195 (P = 0.0124; log–rank test) and miR‐196b (P = 0.0492; log–rank test) positively correlated with overall survival. Evaluation of miR‐181c in combination with miR‐21 predicted time to progression within 6 months of diagnosis with 92% sensitivity and 81% specificity (P < 0.0001). Our data confirmed that the methylation status of MGMT but also miR‐21, miR‐181c, miR‐195, and miR‐196b to be associated with survival of GBM patients. Above all, we suggest that the combination of miR‐181c and miR‐21 could be a very sensitive and specific test to identify patients at high risk of early progression after surgery. (Cancer Sci 2011; 102: 2186–2190)

Expression of miRNA-106b in conventional renal cell carcinoma is a potential marker for prediction of early metastasis after nephrectomy

BackgroundMicroRNAs are endogenously expressed regulatory noncoding RNAs. Previous studies have shown altered expression levels of several microRNAs in renal cell carcinoma.MethodsWe examined the expression levels of selected microRNAs in 38 samples of conventional renal cell carcinoma (RCC) and 10 samples of non-tumoral renal parenchyma using TaqMan real-time PCR method.ResultsThe expression levels of miRNA-155 (p < 0.0001), miRNA-210 (p < 0.0001), miRNA-106a (p < 0.0001) and miRNA-106b (p < 0.0001) were significantly over-expressed in tumor tissue, whereas the expression of miRNA-141 (p < 0.0001) and miRNA-200c (p < 0.0001) were significantly decreased in RCC samples. There were no significant differences between expression levels of miRNA-182 and miRNA-200b in tumor samples and renal parenchyma. Our data suggest that expression levels of miRNA-106b are significantly lower in tumors of patients who developed metastasis (p = 0.030) and miR-106b is a potential predictive marker of early metastasis after nephrectomy in RCC patients (long-rank p = 0.032).ConclusionsWe have confirmed previous observations obtained by miRNA microarray analysis using standardized real-time PCR method. For the first time, we have identified a prognostic significance of miRNA-106b, which, after validation on a larger group of patients, maybe useful as a promising biomarker in patients with RCC.

Identification and functional screening of microRNAs highly deregulated in colorectal cancer

MicroRNAs (miRNAs) constitute a robust regulatory network with post‐transcriptional regulatory efficiency for almost one half of human coding genes, including oncogenes and tumour suppressors. We determined the expression profile of 667 miRNAs in colorectal cancer (CRC) tissues and paired non‐tumoural tissues and identified 42 differentially expressed miRNAs. We chose miR‐215, miR‐375, miR‐378, miR‐422a and miR‐135b for further validation on an independent cohort of 125 clinically characterized CRC patients and for in vitro analyses. MiR‐215, miR‐375, miR‐378 and miR‐422a were significantly decreased, whereas miR‐135b was increased in CRC tumour tissues. Levels of miR‐215 and miR‐422a correlated with clinical stage. MiR‐135b was associated with higher pre‐operative serum levels of CEA and CA19‐9. In vitro analyses showed that ectopic expression of miR‐215 decreases viability and migration, increases apoptosis and promotes cell cycle arrest in DLD‐1 and HCT‐116 colon cancer cell lines. Similarly, overexpression of miR‐375 and inhibition of miR‐135b led to decreased viability. Finally, restoration of miR‐378, miR‐422a and miR‐375 inhibited G1/S transition. These findings indicate that miR‐378, miR‐375, miR‐422a and miR‐215 play an important role in CRC as tumour suppressors, whereas miR‐135b functions as an oncogene; both groups of miRNA contribute to CRC pathogenesis.

Genetic polymorphisms and microRNAs: new direction in molecular epidemiology of solid cancer

•  Introduction •  Classification of miRNA‐related SNPs ‐  SNPs in miRNA processing machinery ‐  SNPs in pri‐, pre‐, mat‐miRNAs ‐  SNPs in miRNA‐binding sites •  MiRNA‐related SNPs and solid cancer ‐  Breast cancer ‐  Colorectal cancer ‐  Lung cancer ‐  Prostate cancer ‐  Renal cell carcinoma ‐  Cervical cancer ‐  Ovarian cancer ‐  Gastric cancer ‐  Bladder cancer ‐  Oesophageal cancer ‐  Hepatocellular carcinoma ‐  Head and neck cancer ‐  Thyroid cancer ‐  Glioma •  Conclusions and future directions

Identification of MicroRNAs associated with early relapse after nephrectomy in renal cell carcinoma patients

Renal cell carcinoma (RCC) is the most common neoplasm of adult kidney. One of the important unmet medical needs in RCC is prognostic biomarker enabling identification of patients at high risk of relapse after nephrectomy. MicroRNAs (miRNAs) constitute a robust regulatory network with posttranscriptional regulatory efficiency for almost one‐half of human coding genes, including oncogenes and tumor suppressors. To identify potential prognostic miRNAs, we analyzed expression profiles in tumors of different prognostic groups of RCC patients. Seventy‐seven patients with clear cell RCC and detailed clinicopathological data were enrolled in a single‐center study. Global miRNA expression profiles were obtained by use of TaqMan Low Density Arrays (754 parallel quantitative reverse‐transcriptase polymerase chain reactions (qRT‐PCR) reactions). For validation of identified miRNAs individual miRNA TaqMan assays were performed in an independent group of patients. We identified tumor relapse‐signature based on the expression of 64 miRNAs differentially expressed between relapse‐free RCC patients and RCC patients who developed relapse (20 miRNAs were increased, 44 miRNAs were decreased). In the validation phase of the study, we successfully confirmed that expression levels of miR‐143, miR‐26a, miR‐145, miR‐10b, miR‐195, and miR‐126 are lower in the tumors of RCC patients who developed tumor relapse, moreover, the lowest levels of these miRNAs we observed in primary metastatic tumors. By using Kaplan–Meier analysis, we identified that miR‐127‐3p, miR‐145, and miR‐126 are significantly correlated with relapse‐free survival of nonmetastatic RCC patients. If further validated, we suggest that identified miRNAs might be used for identification of RCC patients at high risk of early relapse after nephrectomy in clinical practice.

Evaluation of SNPs in miR-196-a2, miR-27a and miR-146a as risk factors of colorectal cancer.

AIM To investigate whether selected single nucleotide polymorphisms (SNPs) in miR-196a2, miR-27a and miR-146a genes are associated with sporadic colorectal cancer (CRC). METHODS In order to investigate the effect of these SNPs in CRC, we performed a case-control study of 197 cases of sporadic CRC and 212 cancer-free controls originating from the Central-European Caucasian population using TaqMan Real-Time polymerase chain reaction and allelic discrimination analysis. RESULTS The genotype and allele frequencies of SNPs were compared between the cases and the controls. None of the performed analysis showed any statistically significant results. CONCLUSION Our data suggest a lack of association between rs11614913, rs895819 and rs2910164 and colorectal cancer risk in the Central-European Caucasian population, a population with an extremely high incidence of sporadic colorectal cancer.

MicroRNA expression profile associated with response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer patients.

BackgroundRectal cancer accounts for approximately one third of all colorectal cancers (CRC), which belong among leading causes of cancer deaths worldwide. Standard treatment for locally advanced rectal cancer (cT3/4 and/or cN+) includes neoadjuvant chemoradiotherapy with fluoropyrimidines (capecitabine or 5-fluorouracil) followed by radical surgical resection. Unfortunately, a significant proportion of tumors do not respond enough to the neoadjuvant treatment and these patients are at risk of relapse. MicroRNAs (miRNAs) are small non-coding RNAs playing significant roles in the pathogenesis of many cancers including rectal cancer. MiRNAs could present the new predictive biomarkers for rectal cancer patients.MethodsWe selected 20 patients who underwent neoadjuvant chemoradiotherapy for advanced rectal cancer and whose tumors were classified as most sensitive or resistant to the treatment. These two groups were compared using large-scale miRNA expression profiling.ResultsExpression levels of 8 miRNAs significantly differed between two groups. MiR-215, miR-190b and miR-29b-2* have been overexpressed in non-responders, and let-7e, miR-196b, miR-450a, miR-450b-5p and miR-99a* have shown higher expression levels in responders. Using these miRNAs 9 of 10 responders and 9 of 10 non-responders (p < 0.05) have been correctly classified.ConclusionsOur pilot study suggests that miRNAs are part of the mechanisms that are involved in response of rectal cancer to the chemoradiotherapy and that miRNAs may be promising predictive biomarkers for such patients. In most miRNAs we identified (miR-215, miR-99a*, miR-196b, miR-450b-5p and let-7e), the connection between their expression and radioresistance or chemoresistance to inhibitors of thymidylate synthetase was already established.