Identification of microRNA-21 as a biomarker for chemoresistance and clinical outcome following adjuvant therapy in resectable pancreatic cancer

High miR-21 expression from FFPE tissues is associated with poor survival and response to adjuvant chemotherapy in colon cancer

Colon cancer (CC) is a leading cause of cancer mortality. Novel biomarkers are needed to identify CC patients at high risk of recurrence and those who may benefit from therapeutic intervention. The aim of this study is to investigate if miR-21 expression from RNA isolated from formalin-fixed paraffin-embedded (FFPE) tissue sections is associated with prognosis and therapeutic outcome for patients with CC. The expression of miR-21 was measured by quantitative reverse transcriptase-polymerase chain reaction in a Japanese cohort (stage I-IV, n = 156) and a German cohort (stage II, n = 145). High miR-21 expression in tumors was associated with poor survival in both the stage II/III Japanese (p = 0.0008) and stage II German (p = 0.047) cohorts. These associations were independent of other clinical covariates in multivariable models. Receipt of adjuvant chemotherapy was not beneficial in patients with high miR-21 in either cohort. In the Japanese cohort, high miR-21 expression was significantly associated with poor therapeutic outcome (p = 0.0001) and adjuvant therapy was associated with improved survival in patients with low miR-21 (p = 0.001). These results suggest that miR-21 is a promising biomarker to identify patients with poor prognosis and can be accurately measured in FFPE tissues. The expression of miR-21 may also identify patients who will benefit from adjuvant chemotherapy.

Targeting microRNAs in pancreatic cancer: microplayers in the big game

The prognosis of patients with pancreatic cancer is extremely poor, and current systemic therapies result in only marginal survival rates for patients. The era of targeted therapies has offered a new avenue to search for more effective therapeutic strategies. Recently, microRNAs (miRNA) that are small noncoding RNAs (18-24 nucleotides) have been associated with a number of diseases, including cancer. Disruption of miRNAs may have important implications in cancer etiology, diagnosis, and treatment. So far, focus has been on the mechanisms that are involved in translational silencing of their targets to fine tune gene expression. This review summarizes the approach for rational validation of selected candidates that might be involved in pancreatic tumorigenesis, cancer progression, and disease management. Herein, we also focus on the major issues hindering the identification of miRNAs, their linked pathways and recent advances in understanding their role as diagnostic/prognostic biomarkers, and therapeutic tools in dealing with this disease. miRNAs are expected to be robust clinical analytes, valuable for clinical research and biomarker discovery.

miRNA-141, downregulated in pancreatic cancer, inhibits cell proliferation and invasion by directly targeting MAP4K4

miRNAs are associated with various types of cancer due to their ability to affect expression of genes that modulate tumorigenesis. In this study, we explored the role of miR-141 in pancreatic cancer. The analysis of clinical characteristics showed that miR-141 was significantly downregulated in tissues and cell lines of pancreatic cancer. Moreover, the decreased miR-141 level was significantly associated with tumor size and TNM stage, as well as lymph node and distant metastasis. Meanwhile, both Kaplan-Meier and multivariate survival analysis showed decreased miR-141 were associated with overall survival. Overexpression of miR-141 in pancreatic cancer cells inhibited cell proliferation, clonogenicity, and invasion; induced G1 arrest and apoptosis; and enhanced chemosensitivity. To understand how miR-141 mediates the phenotype of pancreatic cancer cells, a bioinformatics tool was used to identify MAP4K4 as a potential target of miR-141. The Dual-Luciferase reporter gene assay showed that miR-141 binds directly to the 3'-untranslated region (3'UTR) of MAP4K4 to inhibit MAP4K4 expression. Western blot and quantitative real-time PCR (qRT-PCR) analyses revealed that MAP4K4 expression was inversely correlated with miR-141 expression both in pancreatic cancer samples and cell lines. Knockdown of MAP4K4 inhibited cell proliferation, clonogenicity, and invasion, induced G1 arrest and apoptosis, and enhanced chemosensitivity. In a nude mouse xenograft model, both overexpression of miR-141 and knockdown of MAP4K4 significantly repressed pancreatic cancer cell growth. Therefore, we conclude that miR-141 targets MAP4K4, acts as a tumor suppressor in pancreatic cancer cells, and may serve as a novel therapeutic agent for miRNA-based pancreatic cancer therapy.

MicroRNA-21 promotes oral cancer invasion via the Wnt/β-catenin pathway by targeting DKK2

MicroRNA-21 (miR-21) is overexpressed in a wide variety of cancers and has been related to cellular proliferation, apoptosis, and invasion; however, the function of miR-21 is unknown in oral tongue squamous cell carcinoma (OTSCC). The purpose of this study was to examine miR-21 expression in OTSCC, correlate it with clinicopathological factors, and investigate its contribution to OTSCC cell invasion. MiR-21 expression in 79 primary OTSCCs was evaluated using locked nucleic acid in situ hybridization, and correlation was examined with the clinicopathological factors. To determine the miR-21 target, we searched for molecular genes involved in tumor invasion using the commonly cited prediction program miRanda. In an OTSCC cell line, SCC25 cells, we further evaluated whether miR-21 contributes to cell invasiveness by blocking its expression with a specific knockdown LNA probe and confirmed the direct target by Matrigel invasion assay and Western blotting. MiR-21 overexpression was detected in 60 of 79 cases (75.9 %) and correlated with the pattern of invasion (P = 0.016). We selected DKK2 as a Wnt/antagonist involved in tumor invasion. MiR-21 overexpression was significantly correlated with the DKK2-/β-catenin- immunohistochemical phenotype. Knockdown of miR-21 significantly decreased the invasion potential of SCC25 cells with up-regulated DKK2. It was found that miR-21 is overexpressed and associated with tumor invasion in OTSCC, and that miR-21 promotes OTSCC cell invasion via the Wnt/β-catenin pathway by targeting DKK2 in vitro. These results suggest that miR-21 may be a potential therapeutic target for OTSCC treatment.

MicroRNA-21 in pancreatic ductal adenocarcinoma tumor-associated fibroblasts promotes metastasis

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is projected to rise to the second leading cause of U.S. cancer-related deaths by 2020. Novel therapeutic targets are desperately needed. MicroRNAs (miRs) are small noncoding RNAs that function by suppressing gene expression and are dysregulated in cancer. miR-21 is overexpressed in PDAC tumor cells (TC) and is associated with decreased survival, chemoresistance and invasion. Dysregulation of miR regulatory networks in PDAC tumor-associated fibroblasts (TAFs) have not been previously described. In this study, we show that miR-21 expression in TAFs promotes TC invasion.

METHODS

In-situ hybridization for miR-21 was performed on the 153 PDAC patient UCLA tissue microarray and 23 patient-matched lymph node metastases. Stromal and TC histoscores were correlated with clinicopathologic parameters by univariate and multivariate Cox regression. miR-21 positive cells were further characterized by immunofluorescence for mesenchymal/epithelial markers. For in vitro studies, TAFs were isolated from freshly resected human PDAC tumors by the outgrowth method. miR-21 was overexpressed/inhibited in fibroblasts and then co-cultured with GFP-MiaPaCa TCs to assess TC invasion in modified Boyden chambers.

RESULTS

miR-21 was upregulated in TAFs of 78% of tumors, and high miR-21 significantly correlated with decreased overall survival (P = 0.04). Stromal miR-21 expression was also significantly associated with lymph node invasion (P = 0.004), suggesting that it is driving TC spread. Co-immunofluorescence revealed that miR-21 colocalized with peritumoral fibroblasts expressing α-smooth muscle actin. Moreover, expression of miR-21 in primary TAFs correlated with miR-21 in TAFs from patient-matched LN metastases; evidence that PDAC tumor cells induce TAFs to express miR-21. miR-21 expression in TAFs and TCs promotes invasion of TCs and is inhibited with anti-miR-21.

CONCLUSIONS

miR-21 expression in PDAC TAFs is associated with decreased overall survival and promotes TC invasion. Anti-miR-21 may represent a novel therapeutic strategy for dual targeting of both tumor and stroma in PDAC.

miRNAs and long noncoding RNAs as biomarkers in human diseases

Noncoding RNAs (ncRNAs) are transcripts that have no apparent protein-coding capacity; however, many ncRNAs have been found to play a major biological role in human physiology. Their deregulation is implicated in many human diseases, but their exact roles are only beginning to be elucidated. Nevertheless, ncRNAs are extensively studied as a novel source of biomarkers, and the fact that they can be detected in body fluids makes them extremely suitable for this purpose. The authors mainly focus on ncRNAs as biomarkers in cancer, but also touch on other human diseases such as cardiovascular diseases, autoimmune diseases, neurological disorders and infectious diseases. The authors discuss the established methods and provide a selection of emerging new techniques that can be used to detect and quantify ncRNAs. Finally, the authors discuss ncRNAs as a new strategy for therapeutic interventions.

The microRNA-218 and ROBO-1 signaling axis correlates with the lymphatic metastasis of pancreatic cancer

Pancreatic cancer is known for its poor prognosis and early lymphatic metastasis is a notable characteristic. microRNAs (miRNAs) have been shown to be involved in the initiation and progression of pancreatic cancer. We, therefore, established a screening strategy to find miRNAs related to the lymphatic metastasis of pancreatic cancer and explored the target genes of miRNAs. miRNA array profiles were analyzed in tissue samples [pancreatic ductal adenocarcinoma (PDAC) and matched adjacent benign tissues (MAT)] and cell lines (BxPC-3-LN and BxPC-3). Combined analysis of profiling data from tissue samples and cell lines was used to identify miRNAs related to the lymphatic metastasis of pancreatic cancer. The expression levels of miRNAs were confirmed by real‑time reverse transcription PCR (RT-PCR) in tissue samples and cell lines. The correlation between miRNAs and clinicopathological characteristics was investigated. The expression features of miRNAs in pancreatic cancer, precursor lesions and metastatic lymph nodes were characterized by in situ hybridization (ISH). Predicted target genes of miRNAs were validated by RT-PCR and the protein levels of target genes were revealed by western blotting. Seventy and 63 miRNAs were differentially expressed in pancreatic cancer and BxPC-3-LN, compared to MAT and BxPC-3, respectively. Combined microarray analysis found 4 co-differentially expressed miRNAs (miRNA-663, miRNA-145, miRNA-218 and let-7) related to the lymphatic metastasis of pancreatic cancer. miRNA-218 was significantly downregulated in BxPC-3-LN (fold-change>10) and the expression levels of miRNA-218 were confirmed by RT-PCR. The group with lymph node metastasis and the elder group (age>64) showed lower expression of miRNA-218 (P=0.003 and 0.002), compared to patients without lymph nodes metastasis and patients in the younger group (age≤64), respectively. The expression of miRNA‑218 showed a decreasing trend from normal acinar/ductal epithelium, intraductal papillary mucinous neoplasm (IPMN), pancreatic cancer to metastatic lymph nodes by ISH. Among 8 predicted target genes of miRNA-218, rodent bone (ROBO-1) was confirmed to be upregulated in both mRNA and protein levels in pancreatic cancer. In conclusion, we established a screening strategy based on microarray results and found miRNA-218 to be a notable gene related to lymphatic metastasis of pancreatic cancer. Downregulation of miRNA-218 and upregulation of ROBO-1 were first demonstrated in pancreatic cancer. The miRNA-218 and ROBO-1 signaling axis may contribute to the lymphatic metastasis of pancreatic cancer.

Endoscopically acquired pancreatic cyst fluid microRNA 21 and 221 are associated with invasive cancer

OBJECTIVES

Pancreatic cysts are a group of lesions with heterogeneous malignant potential. Currently, there are no reliable biomarkers to aid in cyst diagnosis and classification. The objective of this study was to identify potential microRNA (miR) biomarkers in endoscopically acquired pancreatic cyst fluid that could be used to distinguish between benign, premalignant, and malignant cysts.

METHODS

A list of candidate miRs was developed using a whole-genome expression array analysis of pancreatic cancer (pancreatic ductal adenocarcinoma) and nonmalignant samples overlapped with existing literature and predicted gene targets. Endoscopically acquired pancreatic cyst fluid samples were obtained from a group of 38 patients who underwent cyst fluid aspiration and surgical resection. Selected miR expression levels in cyst fluid samples were assessed by quantitative real-time-PCR. Additionally, in situ hybridization (ISH) on corresponding cyst tissue samples was performed to identify the source and validate the expression level of fluid miRs.

RESULTS

Of the six miRs that were profiled in the study, two showed differential expression in malignant cysts. miR-221 was expressed at significantly higher levels in malignant cysts compared with benign or premalignant cysts (P=0.05). miR-21 was also expressed at significantly higher levels in malignant cysts (P<0.01). Additionally, the expression of miR-21 was significantly higher in premalignant cysts than benign cysts (P=0.03). The differential expression of miR-21 among cyst categories was confirmed by ISH.

CONCLUSIONS

In this small single-center study, miRs are potential pancreatic cyst fluid diagnostic biomarkers. In particular, miR-21 is identified as a candidate biomarker to distinguish between benign, premalignant, and malignant cysts. Additionally miR-221 may be of use in the identification of more advanced malignant disease.

Relative expressions of miR-205-5p, miR-205-3p, and miR-21 in tissues and serum of non-small cell lung cancer patients

Objective was to assess and compare the relative expressions of miR-205-5p, miR-205-3p, and miR-21-3p in tissues and serum among non-small cell lung carcinoma (NSCLC) patients, benign pulmonary conditions patients, and healthy volunteers. Serum samples were obtained between October 2011 and September 2012 from 20 NSCLC patients undergoing surgical treatment, 20 patients diagnosed with a benign lung disease (pulmonary tuberculosis, pneumonia, chronic obstructive pulmonary disease, or interstitial pneumonia) (lesion group), and 20 healthy volunteers (control group). NSCLC patients provided cancer tissues and cancer-adjacent normal tissues during surgery (paired specimens). Quantitative RT-PCR was used to assess miR-205-5p, miR-205-3p, and miR-21-3p expressions in serum and tissue samples. The relative expressions of miR-205-5p and miR-205-3p were significantly higher in NSCLC tissues compared with cancer-adjacent paired specimens (both P < 0.001). In the serum, significantly higher miR-205-5p, miR-205-3p, and miR-21-3p relative expressions were observed in the NSCLC group compared with the two other groups (all P < 0.001). The relative expressions of miR-205-5p and miR-21-3p in NSCLC tissues and serum were significantly correlated (r = 0.553, P = 0.011; and r = -0.541, P = 0.014, respectively), while no significant correlation was observed for miR-205-3P (P = 0.120). Expressions of miR-205-5p and miR-205-3P in squamous cell carcinoma specimens were significantly higher than in lung adenocarcinoma specimens (both P = 0.001). Similarly, higher serum miR-205-5p and miR-205-3p levels were observed in squamous cell carcinoma patients (P = 0.033 and P = 0.002, respectively). In this preliminary and novel study, miR-205-5p was more useful as a marker for NSCLC than miR-205-3p or miR-21, indicating a potential for future applications in NSCLC diagnosis and prognosis.

MicroRNA-21: a therapeutic target for reversing drug resistance in cancer

INTRODUCTION

Drug resistance is a major clinical obstacle to the successful treatment of human cancer. The microRNAs-21 (miR-21), an oncomiR, may play an important role in the progress of drug resistance.

AREAS COVERED

This review covers all related literature on miR-21 in drug resistance of human cancers and analyzes the expression, biological functions and targets of it. This study also envisages future developments toward its clinical and therapeutic applications in cancer treatment.

EXPERT OPINION

The miR-21 may promote the drug resistance of various cancers. Inhibitors of miR-21 may function as effective approaches for reversing drug resistance in cancer cells. There is a tough way from discovering the function of miR-21 to clinical use. Further understanding of miR-21-mediated signaling pathways will help to promote the therapeutic-clinical use of miR-21 in cancer.

Progress in understanding role of microRNAs in multidrug resistance in digestive system cancers

Multidrug resistance (MDR) is a dominant obstacle to successful cancer chemotherapy, especially in digestive cancers. Therefore, reversing multidrug resistance has become a hot research topic. Recently, studies have shown that MDR is associated with aberrant expression of microRNAs (miRNA) in several types of cancer. MicroRNAs are a class of endogenous non-coding RNA molecules, which act as master regulators of gene expression through mRNA cleavage or translational repression. This review discusses the biological characteristics of miRNAs, their relationship with MDR in digestive system cancers, and potential signal transduction pathways involved, with an aim to provide new insights into the prevention and targeted therapy of MDR in digestive system cancers.

Sweating the small stuff: microRNAs and genetic changes define pancreatic cancer

MicroRNAs (miRNAs) are 18- to 22-nucleotide-long, single-stranded, noncoding RNAs that regulate important biological processes including differentiation, proliferation, and response to cellular stressors such as hypoxia, nutrient depletion, and traversion of the cell cycle by controlling protein expression within the cell. Many investigators have profiled cancer tissue and serum miRNAs to identify potential therapeutic targets, understand the pathways involved in tumorigenesis, and identify diagnostic tumor signatures. In the setting of pancreatic cancer, obtaining pancreatic tissue is invasive and impractical for early diagnosis. Several groups have profiled miRNAs that are present in the blood as a means to diagnose tumor progression and predict prognosis/survival or drug resistance. Several miRNA signatures found in pancreatic tissue and the peripheral blood, as well as the pathways that are associated with pancreatic cancer, are reviewed here in detail. Three miRNA biomarkers (miR-21, miR-155, and miR-200) have been repetitively identified in both pancreatic cancer tissue and patients' blood. Those miRNAs regulate and are regulated by the central genetic and epigenetic changes observed in pancreatic cancer including p53, transforming growth factor β, p16(INK4A), BRCA1/2, and Kras. These miRNAs are involved in DNA repair, cell cycle, and cell invasion and also play important roles in promoting metastases.

Involvement of microRNA-181b in the gemcitabine resistance of pancreatic cancer cells

BACKGROUND/OBJECTIVES

MicroRNAs (miRs) have been shown to regulate the sensitivity to several chemotherapeutic agents in various types of cancers. MiR-181b is one of such regulators, yet its importance in pancreatic cancer is not determined so far. The aim of this study was to investigate the relationship between microRNA (miR)-181b expression and gemcitabine resistance in pancreatic cancer cells.

METHODS

The effects of overexpression or knockdown of miR-181b on four pancreatic cancer cell lines exposed to gemcitabine were examined. The induction of apoptosis and the changes of the cylindromatosis (CYLD) protein were examined. Furthermore, the effect of small interference RNA for CYLD (siCYLD) on cell viability and the relationship between CYLD and nuclear factor kappa B (NF-κB) were investigated.

RESULTS

The expression of miR-181b was higher in BxPC3, Panc1 and PSN1 cells compared with MiaPaCa2 cells. Pre-miR-181b transfection into MiaPaCa2 cells increased their gemcitabine resistance, whereas anti-miR-181b transfection into the other pancreatic cancer cell lines reduced their resistance to gemcitabine and led to the induction of apoptosis. The protein levels of CYLD were increased by anti-miR-181b in Panc1 and PSN1 cells. Inhibition of CYLD increased the NF-κB activity and gemcitabine resistance in Panc1 and PSN1 cells.

CONCLUSIONS

The present study demonstrated that miR-181b was associated with the resistance of pancreatic cancer cells to gemcitabine, and verified that miR-181b enhances the activity of NF-κB by inhibiting CYLD, leading to the resistance to gemcitabine. Our results suggest that miR-181b is a potential target for decreasing gemcitabine resistance.

miR-320c regulates gemcitabine-resistance in pancreatic cancer via SMARCC1

Background:

Gemcitabine-based chemotherapy is the standard treatment for pancreatic cancer. However, the issue of resistance remains unresolved. The aim of this study was to identify microRNAs (miRNAs) that govern the resistance to gemcitabine in pancreatic cancer.

Methods:

miRNA microarray analysis using gemcitabine-resistant clones of MiaPaCa2 (MiaPaCa2-RGs), PSN1 (PSN1-RGs), and their parental cells (MiaPaCa2-P, PSN1-P) was conducted. Changes in the anti-cancer effects of gemcitabine were studied after gain/loss-of-function analysis of the candidate miRNA. Further assessment of the putative target gene was performed in vitro and in 66 pancreatic cancer clinical samples.

Results:

miR-320c expression was significantly higher in MiaPaCa2-RGs and PSN1-RGs than in their parental cells. miR-320c induced resistance to gemcitabine in MiaPaCa2. Further experiments showed that miR-320c-related resistance to gemcitabine was mediated through SMARCC1, a core subunit of the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex. In addition, clinical examination revealed that only SMARCC1-positive patients benefited from gemcitabine therapy with regard to survival after recurrence (P=0.0463).

Conclusion:

The results indicate that miR-320c regulates the resistance of pancreatic cancer cells to gemcitabine through SMARCC1, suggesting that miR-320c/SMARCC1 could be suitable for prediction of the clinical response and potential therapeutic target in pancreatic cancer patients on gemcitabine-based therapy.

MicroRNA signatures and treatment response in patients with advanced classical Hodgkin lymphoma

Although specific microRNA (miRNA) signatures in classical Hodgkin lymphoma (cHL) have been proposed, their relationship with clinical outcome remains unclear. Despite treatment advances, a substantial subset of patients with advanced cHL are refractory to standard therapies based on adriamycin and its variants. Global miRNA expression data of 29 advanced cHL patients and five cHL-derived cell lines were used to identify profiles from Hodgkin-Reed-Sternberg (HRS) cells and their non-tumoural microenvironment. A cHL-miRNA signature was identified with 234 miRNAs differentially expressed. A subset of these miRNAs was associated with outcome and selected for study in an independent set of 168 cHL samples using quantitative reverse transcription polymerase chain reaction. Multivariate Cox regression analyses including cross-validation with failure-free survival (FFS) as clinical endpoint revealed a miRNA signature with MIR21, MIR30E, MIR30D and MIR92B* that identified two risk-groups with significant differences in 5-year FFS (81% vs. 35.7%; P < 0.001). Additionally, functional silencing of MIR21 and MIR30D in L428 cells showed increased sensitivity to doxorubicin-induced apoptosis, pointing towards abnormalities of mitochondrial intrinsic and TP53-CDKN1A pathways as related to miRNA deregulation in cHL. These results suggest that clinical outcome in cHL is associated with a specific miRNA signature. Moreover, functional analyses suggest a role for MIR21 and MIR30D in cHL pathogenesis and therapeutic resistance.

The alteration of miR-222 and its target genes in nickel-induced tumor

Nickel is an important kind of metal and a necessary trace element in people's production and livelihood; it is also a well-confirmed human carcinogen. In the past few years, researchers did a large number of studies about the molecular mechanisms of nickel carcinogenesis, and they focused on activation of proto-oncogenes and inactivation of anti-oncogenes caused by gene point mutation, gene deletion, gene amplification, DNA methylation, chromosome condensation, and so on that were induced by nickel. However, the researches on tumorigenic molecular mechanisms regulated by microRNAs (miRNAs) are rare. In this study, we established nickel-induced tumor by injecting Ni3S2 compounds to Wistar Rattus. By establishing a cDNA library of miRNA from rat muscle tumor tissue induced by Ni3S2, we found that the expression of miR-222 was significantly upregulated in tumor tissue compared with the normal tissue. As we expected, the expression levels of target genes of miR-222, CDKN1B and CDKN1C, were downregulated in the nickel-induced tumor. The same alteration of miR-222 and its target genes was also found in malignant 16HBE cells induced with Ni3S2 compounds. We conclude that miR-222 may promote cell proliferation infinitely during nickel-induced tumorigenesis in part by regulating the expression of its target genes CDKN1B and CDKN1C. Our study elucidated a novel molecular mechanism of nickel-induced tumorigenesis.

Prognostic microRNAs in cancer tissue from patients operated for pancreatic cancer--five microRNAs in a prognostic index

BACKGROUND

The aim of the present study was to identify a panel of microRNAs (miRNAs) that can predict overall survival (OS) in non micro-dissected cancer tissues from patients operated for pancreatic cancer (PC).

METHODS

MiRNAs were purified from formalin-fixed paraffin embedded (FFPE) cancer tissue from 225 patients operated for PC. Only a few of those patients received adjuvant chemotherapy. Expressions of miRNAs were determined with the TaqMan MicroRNA Array v2.0. Two statistical methods, univariate selection and the Lasso (Least Absolute Shrinkage and Selection Operator) method, were applied in conjunction with the Cox proportional hazard model to relate miRNAs to OS.

RESULTS

High expression of miR-212 and miR-675 and low expression of miR-148a, miR-187, and let-7g predicted short OS independent of age, gender, calendar year of operation, KRAS mutation status, tumor stage, American Society of Anesthesiologists (ASA) score, localization (not miR-148a), and differentiation of tumor. A prognostic index (PI) based on these five miRNAs was calculated for each patient. The median survival was 1.09 years (Confidence Interval [CI] 0.98-1.43) for PI > median PI compared to 2.23 years (CI 1.84-4.36) for PI < median. MiR-212, miR-675, miR-187, miR-205, miR-944, miR-431, miR-194, miR-148a, and miR-769-5p showed the strongest prediction ability by the Lasso method. Thus miR-212, miR-675, miR-187, and miR-148a were predictors for OS in both statistical methods.

CONCLUSIONS

The combination of five miRNAs expression in non micro-dissected FFPE PC tissue can identify patients with short OS after radical surgery. The results are independent of chemotherapy treatment. Patients with a prognostic index > median had a very short median OS of only 1 year.

Reduction of Plasma MicroRNA-21 is Associated with Chemotherapeutic Response in Patients with Non-small Cell Lung Cancer

OBJECTIVE

To examine plasma microRNA-21 (miR-21) level in patients with non-small cell lung cancer (NSCLC) and its potential correlation with chemotherapeutic response.

METHODS

77 NSCLC patients and 36 age and sex-matched healthy controls were included. Plasma miR-21 concentration was examined using a quantitative real-time reverse transcription polymerase chain reaction assay (qRT-PCR). Potential correlation between plasma mir-21 concentrations with chemotherapeutic responses was analyzed in 35 patients with advanced NSCLC (stages IIIB and IV).

RESULTS

Plasma miR-21 was significantly higher in NSCLC patients relative to the healthy controls (P<0.0001). As a biomarker, plasma mir-21 had a receiver operating characteristic (ROC) curve area of 0.729 with 61.04% sensitivity and 83.33% specificity. Chemotherapeutic response in the 35 patients with advanced NSCLC (stages IIIB and IV) included partial response (PR) (n=11), stable disease and progression disease (SD+PD) (n=24). The overall response rate (CR+PR) was 31.4%. Plasma miR-21 in patients who achieved PR was significantly lower than those who did not respond (SD+PD) (P=0.0487), and comparable to that of the healthy controls (P=0.2744).

CONCLUSION

Plasma miR-21 is a good biomarker for NSCLC, and could be used to predict responses to chemotherapy.

The good, the bad and the ugly: a tale of miR-101, miR-21 and miR-155 in pancreatic intraductal papillary mucinous neoplasms

BACKGROUND

This multicenter study evaluated three candidate microRNAs (miRNAs) (miR-21, miR-155 and miR-101) as potential biomarkers in intraductal papillary mucinous neoplasms (IPMNs) of the pancreas.

PATIENTS AND METHODS

miRNA expression was quantified by quantitative RT-PCR in 86 laser-microdissected specimens, including 65 invasive IPMNs, 16 non-invasive IPMNs and 5 normal pancreatic ductal tissues. Univariate and multivariate analyses compared miRNAs and clinical parameters with overall (OS) and disease-free survival (DFS).

RESULTS

miR-21 and miR-155 were up-regulated in invasive IPMNs compared with non-invasive IPMNs, as well as in non-invasive IPMNs compared with normal tissues. Conversely, miR-101 levels were significantly higher in non-invasive IPMNs and normal tissues compared with invasive IPMNs. High levels of miR-21 were associated with worse OS [hazard ratio (HR) = 2.47, 95% confidence interval (CI) = 1.37-5.65, P = 0.0047]. Patients with high-miR-21 expression also had a shorter median DFS (10.9 versus 29.9 months, P = 0.01). Multivariate analysis confirmed miR-21 as independently prognostic for mortality and disease progression (death risk: HR = 3.3, 95% CI = 1.5-7.0, P = 0.02; progression risk: HR = 2.3, 95% CI = 1.2-4.8, P = 0.02), as well as positive lymph-node status (death risk: HR = 2.6, 95% CI = 1.1-6.3, P = 0.03; progression risk: HR = 2.2, 95% CI = 1.0-4.8, P = 0.04).

CONCLUSIONS

miR-21, miR-155 and miR-101 showed significant differences in invasive versus non-invasive IPMNs. miR-21 emerged as an independent prognostic biomarker in invasive IPMNs and should be validated in prospective studies.

3D pancreatic carcinoma spheroids induce a matrix-rich, chemoresistant phenotype offering a better model for drug testing

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is the fourth most common cause of cancer related death. It is lethal in nearly all patients, due to an almost complete chemoresistance. Most if not all drugs that pass preclinical tests successfully, fail miserably in the patient. This raises the question whether traditional 2D cell culture is the correct tool for drug screening. The objective of this study is to develop a simple, high-throughput 3D model of human PDAC cell lines, and to explore mechanisms underlying the transition from 2D to 3D that might be responsible for chemoresistance.

METHODS

Several established human PDAC and a KPC mouse cell lines were tested, whereby Panc-1 was studied in more detail. 3D spheroid formation was facilitated with methylcellulose. Spheroids were studied morphologically, electron microscopically and by qRT-PCR for selected matrix genes, related factors and miRNA. Metabolic studies were performed, and a panel of novel drugs was tested against gemcitabine.

RESULTS

Comparing 3D to 2D cell culture, matrix proteins were significantly increased as were lumican, SNED1, DARP32, and miR-146a. Cell metabolism in 3D was shifted towards glycolysis. All drugs tested were less effective in 3D, except for allicin, MT100 and AX, which demonstrated effect.

CONCLUSIONS

We developed a high-throughput 3D cell culture drug screening system for pancreatic cancer, which displays a strongly increased chemoresistance. Features associated to the 3D cell model are increased expression of matrix proteins and miRNA as well as stromal markers such as PPP1R1B and SNED1. This is supporting the concept of cell adhesion mediated drug resistance.

Pancreatic cancer cells retain the epithelial-related phenotype and modify mitotic spindle microtubules after the administration of ukrain in vitro

The aim of this study is to characterize the phenotype of pancreatic ductal adenocarcinoma (PDAC) cells in relation to the expression of epithelial-to-mesenchymal transition (EMT) markers and determine whether ukrain, an anticancer drug based on the alkaloids extracted from greater celandine, modulates in vitro the malignant behavior of PDAC cells in order to extend our understanding of its therapeutic potential. Three cell lines (HPAF-II, HPAC, and PL45) were treated with ukrain (5, 10, and 20 μmol/l) for 48 h or left untreated (control). Cell proliferation was assessed by growth curves. Apoptosis was determined by Hoechst nuclear staining and by cytochrome c and caspase-8 expressions. The EMT markers E-cadherin, β-catenin, and vimentin, as well as actin and tubulin cytoskeletons, were analyzed by immunofluorescence. Interphase and mitotic microtubules as well as abnormal mitotic figures were studied by fluorescence microscopy after tubulin immunolabeling. Ukrain strongly suppressed cell proliferation and induced apoptosis possibly through an extrinsic pathway as cytochrome c immunoreactivity suggested that the integrity of the mitochondria was not affected. Tubulin expression indicated an antiproliferative effect of ukrain on the basis of alterations in mitotic spindle microtubule dynamics, leading to abnormal mitosis. Membranous E-cadherin/β-catenin immunoreactivity was similarly expressed in control-treated and ukrain-treated cells, although the drug upregulated E-cadherin in cell lysates. Our results suggest that ukrain exerts its chemotherapeutic action on PDAC cells targeting mitotic spindle microtubules, leading to abnormal mitosis and apoptosis, and favoring cell cohesiveness. The differentiated epithelial phenotype of HPAF-II, HPAC, and PL45 cell lines concomitant with a highly invasive potential suggests that further experiments will be necessary to definitively clarify the role of EMT in PDAC progression.

Garcinol sensitizes human pancreatic adenocarcinoma cells to gemcitabine in association with microRNA signatures

BACKGROUND

Alterations in microRNA (miRNA/miR) genes are of biological importance in the pathophysiology of cancers, including pancreatic cancer (PaCa). Although growing evidence supports the role of miRNA in cancer, their response to dietary phytochemicals is less known. Previously, we showed that garcinol induces PaCa cell growth arrest and apoptosis in vitro. The present study, discusses chemo-sensitization by garcinol in synergism with first-line PaCa drug, gemcitabine. The miRNA expression profile of gemcitabine-resistant Panc-1 cells treated with garcinol and/or gemcitabine was also evaluated.

METHODS AND RESULTS

Garcinol synergizes with gemcitabine to inhibit cell proliferation and induce apoptosis in PaCa cells with significant modulation of key cancer regulators including PARP, VEGF, MMPs, ILs, caspases, and NF-κB. In addition, biostatistical analyses, quantitative reverse transcription PCR data, and in silico modeling using TargetScan5, PicTar, and DNA intelligent analysis, microT-V.B4 database showed that these two agents modulated a number of microRNAs (miR-21, miR-196a, miR-495, miR-605, miR-638, and miR-453) linked to various canonical oncogenic signaling pathways.

CONCLUSION

We identified garcinol-specific miRNA biomarkers that sensitize PaCa cells to gemcitabine treatment, thus attenuating the drug-resistance phenotype. These results prompt further interest in garcinol and gemcitabine combination strategy as a drug modality to improve treatment outcome in patients diagnosed with PaCa.

Aberrant expression of miR-199a-3p and its clinical significance in colorectal cancers

Aberrant miR-199a-3p expression has been reported in several cancers. However, the clinical significance of miR-199a-3p in human colorectal cancer has not been addressed. In this study, we detected miR-199a-3p expression in 92 colorectal cancer cases to evaluate its clinicopathologic characteristics in colorectal cancer. We showed that miR-199a-3p expression was significantly upregulated in cancer tissues than NATs. Clinicopathologic analysis revealed that high miR-199a-3p expression contributed to more advanced lymphatic invasion, lymph node metastasis, liver metastases and late TNM stage in colorectal cancer. Kaplan-Meier analysis showed that high expression of miR-199a-3p could lead to a significantly shorter overall survival rate. Cox's proportional hazards model also indicated that the high expression of miR-199a-3p could serve as an independent and significant prognostic factor for survival. We transfected miR-199a-3p inhibitor into SW480 cells and observed that miR-199a-3p inhibitor could markedly inhibit the cell proliferation. Flow cytometry analysis also found that miR-199a-3p inhibitor could cause G0/G1 arrest, decreased percentage of S and G2/M phase and induce more cell apoptosis in SW480 cells. These results suggested that miR-199a-3p may serve as an efficient biomarker for diagnosis and novel prognostic indicator in colorectal cancer.

Current status and implications of microRNAs in ovarian cancer diagnosis and therapy

Ovarian cancer is the fifth most common cancer among women and causes more deaths than any other type of female reproductive cancer. Currently, treatment of ovarian cancer is based on the combination of surgery and chemotherapy. While recurrent ovarian cancer responds to additional chemotherapy treatments, the progression-free interval becomes shorter after each cycle, as chemo-resistance increases until the disease becomes incurable. There is, therefore, a strong need for prognostic and predictive markers to help optimize and personalize treatment in order to improve the outcome of ovarian cancer. An increasing number of studies indicate an essential role for microRNAs in ovarian cancer progression and chemo-resistance. MicroRNAs (miRNAs) are small endogenous non-coding RNAs (~22bp) which are frequently dysregulated in cancer. Typically, miRNAs are involved in crucial biological processes, including development, differentiation, apoptosis and proliferation. Two families of miRNAs, miR-200 and let-7, are frequently dysregulated in ovarian cancer and have been associated with poor prognosis. Both have been implicated in the regulation of epithelial-to-mesenchymal transition, a cellular transition associated with tumor aggressiveness, tumor invasion and chemo-resistance. Moreover, miRNAs also have possible implications for improving cancer diagnosis; for example miR-200 family, let-7 family, miR-21 and miR-214 may be useful in diagnostic tests to help detect ovarian cancer at an early stage. Additionally, the use of multiple target O-modified antagomirs (MTG-AMO) to inhibit oncogenic miRNAs and miRNA replacement therapy for tumor suppressor miRNAs are essential tools for miRNA based cancer therapeutics. In this review we describe the current status of the role miRNAs play in ovarian cancer and focus on the possibilities of microRNA-based therapies and the use of microRNAs as diagnostic tools.

Epigenetic alterations involved in cancer stem cell reprogramming

Current hypotheses suggest that tumors originate from cells that carry out a process of "malignant reprogramming" driven by genetic and epigenetic alterations. Multiples studies reported the existence of stem-cell-like cells that acquire the ability to self-renew and are able to generate the bulk of more differentiated cells that form the tumor. This population of cancer cells, called cancer stem cells (CSC), is responsible for sustaining the tumor growth and, under determined conditions, can disseminate and migrate to give rise to secondary tumors or metastases to distant organs. Furthermore, CSCs have shown to be more resistant to anti-tumor treatments than the non-stem cancer cells, suggesting that surviving CSCs could be responsible for tumor relapse after therapy. These important properties have raised the interest in understanding the mechanisms that govern the generation and maintenance of this special population of cells, considered to lie behind the on/off switches of gene expression patterns. In this review, we summarize the most relevant epigenetic alterations, from DNA methylation and histone modifications to the recently discovered miRNAs that contribute to the regulation of cancer stem cell features in tumor progression, metastasis and response to chemotherapy.

MicroRNA expression profiles associated with pancreatic adenocarcinoma and ampullary adenocarcinoma

MicroRNAs have potential as diagnostic cancer biomarkers. The aim of this study was (1) to define microRNA expression patterns in formalin-fixed parafin-embedded tissue from pancreatic ductal adenocarcinoma, ampullary adenocarcinoma, normal pancreas and chronic pancreatitis without using micro-dissection and (2) to discover new diagnostic microRNAs and combinations of microRNAs in cancer tissue. The expression of 664 microRNAs in tissue from 170 pancreatic adenocarcinomas and 107 ampullary adenocarcinomas were analyzed using a commercial microRNA assay. Results were compared with chronic pancreatitis, normal pancreas and duodenal adenocarcinoma. In all, 43 microRNAs had higher and 41 microRNAs reduced expression in pancreatic cancer compared with normal pancreas. In all, 32 microRNAs were differently expressed in pancreatic adenocarcinoma compared with chronic pancreatitis (17 higher; 15 reduced). Several of these microRNAs have not before been related to diagnosis of pancreatic cancer (eg, miR-492, miR-614, miR-622). MiR-614, miR-492, miR-622, miR-135b and miR-196 were most differently expressed. MicroRNA profiles of pancreatic and ampullary adenocarcinomas were correlated (0.990). MicroRNA expression profiles for pancreatic cancer described in the literature were consistent with our findings, and the microRNA profile for pancreatic adenocarcinoma (miR-196b-miR-217) was validated. We identified a more significant expression profile, the difference between miR-411 and miR-198 (P=2.06 × 10(-54)) and a diagnostic LASSO classifier using 19 microRNAs (sensitivity 98.5%; positive predictive value 97.8%; accuracy 97.0%). We also identified microRNA profiles to subclassify ampullary adenocarcinomas into pancreatobiliary or intestinal type. In conclusion, we found that combinations of two microRNAs could roughly separate neoplastic from non-neoplastic samples. A diagnostic 19 microRNA classifier was constructed which without micro-dissection could discriminate pancreatic and ampullary adenocarcinomas from chronic pancreatitis and normal pancreas with high sensitivity and accuracy. Ongoing prospective studies will evaluate if these microRNA profiles are useful on fine-needle biopsies for early diagnosis of pancreatic cancer.

High-throughput microRNA (miRNAs) arrays unravel the prognostic role of MiR-211 in pancreatic cancer

BACKGROUND

Only a subset of radically resected pancreatic ductal adenocarcinoma (PDAC) patients benefit from chemotherapy, and identification of prognostic factors is warranted. Recently miRNAs emerged as diagnostic biomarkers and innovative therapeutic targets, while high-throughput arrays are opening new opportunities to evaluate whether they can predict clinical outcome. The present study evaluated whether comprehensive miRNA expression profiling correlated with overall survival (OS) in resected PDAC patients.

METHODOLOGY/PRINCIPAL FINDINGS

High-resolution miRNA profiles were obtained with the Toray's 3D-Gene™-miRNA-chip, detecting more than 1200 human miRNAs. RNA was successfully isolated from paraffin-embedded primary tumors of 19 out of 26 stage-pT3N1 homogeneously treated patients (adjuvant gemcitabine 1000 mg/m(2)/day, days-1/8/15, every 28 days), carefully selected according to their outcome (OS<12 (N = 13) vs. OS>30 months (N = 6), i.e. short/long-OS). Highly stringent statistics included t-test, distance matrix with Spearman-ranked correlation, and iterative approaches. Unsupervised hierarchical analysis revealed that PDACs clustered according to their short/long-OS classification, while the feature selection algorithm RELIEF identified the top 4 discriminating miRNAs between the two groups. These miRNAs target more than 1500 transcripts, including 169 targeted by two or more. MiR-211 emerged as the best discriminating miRNA, with significantly higher expression in long- vs. short-OS patients. The expression of this miRNA was subsequently assessed by quantitative-PCR in an independent cohort of laser-microdissected PDACs from 60 resected patients treated with the same gemcitabine regimen. Patients with low miR-211 expression according to median value had a significantly shorter median OS (14.8, 95%CI = 13.1-16.5, vs. 25.7 months, 95%CI = 16.2-35.1, log-rank-P = 0.004). Multivariate analysis demonstrated that low miR-211 expression was an independent factor of poor prognosis (hazard ratio 2.3, P = 0.03) after adjusting for all the factors influencing outcome.

CONCLUSIONS/SIGNIFICANCE

Through comprehensive microarray analysis and PCR validation we identified miR-211 as a prognostic factor in resected PDAC. These results prompt further prospective studies and research on the biological role of miR-211 in PDAC.

The serum miR-21 level serves as a predictor for the chemosensitivity of advanced pancreatic cancer, and miR-21 expression confers chemoresistance by targeting FasL

miR-21 expression in cancer tissue has been reported to be associated with the clinical outcome and activity of gemcitabine in pancreatic cancer. However, resection is possible in only a minority of patients due to the advanced stages often present at the time of diagnosis, and safely obtaining sufficient quantities of pancreatic tumor tissue for molecular analysis is difficult at the unresectable stages. In this study, we investigated whether the serum level of miR-21 could be used as a predictor of chemosensitivity. We tested the levels of serum miR-21 in a cohort of 177 cases of advanced pancreatic cancer who received gemcitabine-based palliative chemotherapy. We found that a high level of miR-21 in the serum was significantly correlated with a shortened time-to-progression (TTP) and a lower overall survival (OS). The serum miR-21 level was an independent prognostic factor for both the TTP and the OS (HR 1.920; 95% CI, 1.274-2.903, p = 0.002 for TTP and HR 1.705; 95% CI, 1.147-2.535, p = 0.008 for OS). The results from a functional study showed that gemcitabine exposure down-regulated miR-21 expression and up-regulated FasL expression. The increased FasL expression following gemcitabine treatment induced cancer cell apoptosis, whereas the ectopic expression of miR-21 partially protected the cancer cells from gemcitabine-induced apoptosis. Additionally, we confirmed that FasL was a direct target of miR-21. Therefore, the serum level of miR-21 may serve as a predictor of chemosensitivity in advanced pancreatic cancer. Additionally, we identified a new mechanism of chemoresistance mediated by the effects of miR-21 on the FasL/Fas pathway.

miRNA pharmacogenomics: the new frontier for personalized medicine in cancer?

In recent years pharmacogenomic research has highlighted several genetic biomarkers of treatment toxicity and efficacy, dealing with drug metabolism, transport and mechanism of action. More recently, polymorphisms in miRNA encoding genes, their targets or factors involved in their maturation are rising as new pharmacogenomic markers in cancer. miRNAs are brief ncRNAs involved in DNA translational control, with an effect on mRNA and protein-expression levels. The study of genetic polymorphisms in genes involved in miRNA translational control machinery could give innovative insights in pharmacogenomics. This review summarizes the most recent and promising results in the field and gives an overview of the future perspective of personalized cancer therapy.

Molecular pathology of pancreatic cancer: from bench-to-bedside translation

Pancreatic ductal adenocarcinoma (referred here as pancreatic cancer) is a lethal disease with the worst prognosis among all solid tumors. Surgical resection represents the only hope for cure but it is possible only in patients that present with local disease (about 20% of cases). Whether dismal prognosis of pancreatic cancer is a result of late diagnosis or early dissemination to distant organ is still a debate. Moreover, this disease shows an intrinsic chemotherapeutic resistance that has been mainly ascribed to the presence of a dense stromal reaction that significantly impairs drugs delivery. Clinical management of pancreatic cancer patients relies on few molecular markers (e.g., the diagnostic marker CA19-9) that, however, present several limitations to their use. The clinical usefulness of somatic alterations in well-characterized genes (such as KRAS and TP53), whose detection is technically feasible in different biological samples, has been extensively investigated leading to inconsistent results. Furthermore, none of the candidate molecular markers identified in recent years has shown an appropriate clinical performance and therefore none is routinely used. This depicts a scenario where the identification of novel and effective clinical biomarkers is mandatory. Very recent genome-wide comprehensive studies have shed light on the high degree of genetic complexity and heterogeneity of the pancreatic cancers. Although far from being introduced into the clinical settings, results from those studies are expected to change definitively the perspective through which we look at the clinical management of pancreatic cancer patients towards a personalized cancer medicine.

[Pancreatic cancer and microRNAs]

MicroRNAs (miRNAs) are recently discovered non-coding small RNAs that play a role as regulators of genetic expressions in eukaryotic cells. It comprises about 20 nucleotides, which contains seed sequence to bind 3'-untranslated lesion of specific target mRNA. It regulates self-renewal, proliferation and differentiation via post-transcriptional gene slicing in normal situation. Aberrant expressions of miRNAs are observed in many cancers as well. miRNAs in cancer cells have been investigated extensively to have a role in tumorigenesis, invasion, metastasis and chemoresistance. In cancer cells, miRNAs act both as tumor suppressors or oncogenes by doing down-regulation of oncogenes or up-regulation of tumor suppressors, respectively. This suggests miRNAs can be potential therapeutic and diagnostic targets in cancers. Pancreatic cancer is one of the most lethal tumors. In spite of many efforts, overall 5-year survival rate of pancreatic cancer is still very low (<5%). Recently, several miRNAs as an oncomir (acting like oncogenes or tumor suppressor genes) are discovered in pancreatic cancer. Here, the role of miRNAs in pancreatic cancer will be discussed and its possibility of diagnostic/therapeutic target will be also mentioned.

The role of microRNAs in breast cancer migration, invasion and metastasis

MicroRNAs (miRNAs) are a major class of small, noncoding RNA molecules that regulate gene expression by targeting mRNAs to trigger either translational repression or mRNA degradation. They have recently been more widely investigated due to their potential role as targets for cancer therapy. Many miRNAs have been implicated in several human cancers, including breast cancer. miRNAs are known to regulate cell cycle and development, and thus may serve as useful targets for exploration in anticancer therapeutics. The link between altered miRNA signatures and breast cancer development and metastasis can be observed either through the loss of tumor suppressor miRNAs, such as let-7s, miR-30a/31/34a/125s/200s/203/205/206/342 or the overexpression of oncogenic miRNAs, such as miR-10b/21/135a/155/221/222/224/373/520c in breast cancer cells. Some of these miRNAs have also been validated in tumor specimens of breast cancer patients, underscoring their potential roles in diagnostics, as well as targets for novel therapeutics for breast cancer. In this review article, we will provide an overview and update of our current understanding of the mode of action of several of these well characterized miRNAs in breast cancer models. Therefore, better understanding of the gene networks orchestrated by these miRNAs may help exploit the full potential of miRNAs in regards to cancer diagnosis, treatment, and therapeutics.

Circulating microRNAs: new biomarkers in diagnosis, prognosis and treatment of cancer (review)

MicroRNAs (miRNAs) are small non-coding, endogenous, single-stranded RNAs. MiRNAs have been implicated in different areas such as the immune response, neural development, DNA repair, apoptosis, oxidative stress response and cancer. However, while the majority of miRNAs are found intracellularly, a significant number of miRNAs have been observed outside of cells, including various body fluids. Circulating miRNAs function as 'extracellular communication RNAs' that play an important role in cell proliferation and differentiation. MiRNA regulation is essential to many cellular processes, and escape from this regulatory network seems to be a common characteristic of several disease processes and malignant transformation. The interest in circulating miRNAs reflects in fact their central role in regulation of gene expression and the implication of miRNA-specific aberrant expression in the pathogenesis of cancer, cardiac, metabolic, neurologic, immune-related diseases as well as others. In our review we aimed to summarize the data related to the action of cellular miRNAs on the onset of various diseases, thus bringing together some of the latest information available on the role of circulating miRNAs. Additionally, the role of circulating miRNAs could be particularly relevant in the context of neoplastic diseases. At least 79 miRNAs have been reported as plasma or serum miRNA biomarkers of solid and hematologic tumors. Circulating miRNA profiling could improve the diagnosis of cancer, and could predict outcome for cancer patients, while the profiling of alterations in circulating miRNA that may signal a predisposition to cancer, could also be a therapeutic target in these patients.

Identification of plasma microRNA-21 as a biomarker for early detection and chemosensitivity of non-small cell lung cancer

Studies have shown cell-free microRNA (miRNA) circulating in the serum and plasma with specific expression in cancer, indicating the potential of using miRNAs as biomarkers for cancer diagnosis and therapy. This study was to investigate whether plasma miRNA-21 (miR-21) can be used as a biomarker for the early detection of non-small cell lung cancer (NSCLC) and to explore its association with clinicopathologic features and sensitivity to platinum-based chemotherapy. We used real-time RT-PCR to investigate the expression of miR-21 in the plasma of 63 NSCLC patients and 30 healthy controls and correlated the findings with early diagnosis, pathologic parameters, and treatment. Thirty-five patients (stages IIIB and IV) were evaluable for chemotherapeutic responses: 11 had partial response (PR); 24 had stable and progressive disease (SD+ PD). Plasma miR-21 was significantly higher in NSCLC patients than in age- and sex-matched controls (P < 0.001). miR-21 was related to TNM stage (P < 0.001), but not related to age, sex, smoking status, histological classification, lymph node status, and metastasis (all P > 0.05). This marker yielded a receiver operating characteristic (ROC) curve area of 0.775 (95% CI: 0.681- 0.868) with 76.2% sensitivity and 70.0% specificity. Importantly, miR-21 plasma levels in PR samples were several folds lower than that in SD plus PD samples (P = 0.049), and were close to that in healthy controls (P = 0.130). Plasma miR-21 can serve as a circulating tumor biomarker for the early diagnosis of NSCLC and is related to the sensitivity to platinum-base chemotherapy.

New biomarkers and targets in pancreatic cancer and their application to treatment

Late diagnosis of pancreatic ductal adenocarcinoma (pancreatic cancer) and the limited response to current treatments results in an exceptionally poor prognosis. Advances in our understanding of the molecular events underpinning pancreatic cancer development and metastasis offer the hope of tangible benefits for patients. In-depth mutational analyses have shed light on the genetic abnormalities in pancreatic cancer, providing potential treatment targets. New biological studies in patients and in mouse models have advanced our knowledge of the timing of metastasis of pancreatic cancer, highlighting new directions for the way in which patients are treated. Furthermore, our increasing understanding of the molecular events in tumorigenesis is leading to the identification of biomarkers that enable us to predict response to treatment. A major drawback, however, is the general lack of an adequate systematic approach to advancing the use of biomarkers in cancer drug development, highlighted in a Cancer Biomarkers Collaborative consensus report. In this Review, we summarize the latest insights into the biology of pancreatic cancer, and their repercussions for treatment. We provide an overview of current treatments and, finally, we discuss novel therapeutic approaches, including the role of biomarkers in therapy for pancreatic cancer.

Molecular pathways: microRNAs as cancer therapeutics

MicroRNAs (miRNA) are approximately 18 to 25 nucleotides in length and affect gene expression by silencing the translation of messenger RNAs. Because each miRNA regulates the expression of hundreds of different genes, miRNAs can function as master coordinators, efficiently regulating and coordinating multiple cellular pathways and processes. By coordinating the expression of multiple genes, miRNAs are responsible for fine-tuning the cell's most important processes, like the ones involved in cellular growth and proliferation. Dysregulation of miRNAs appears to play a fundamental role in the onset, progression and dissemination of many cancers, and replacement of downregulated miRNAs in tumor cells results in a positive therapeutic response. Thus, in theory, inhibition of a particular miRNA linked to cancer onset or progression can remove the inhibition of the translation of a therapeutic protein-and conversely, administration of a miRNA mimetic can boost the endogenous miRNA population repressing the translation of an oncogenic protein. Although several basic questions about their biologic principles still remain to be answered, and despite the fact that all data with respect to miRNAs and therapy are still at the preclinical level, many specific characteristics of miRNAs in combination with compelling therapeutic efficacy data have triggered the research community to start exploring the possibilities of using miRNAs as potential therapeutic candidates.

Increased expression of microRNA-21and its association with chemotherapeutic response in human colorectal cancer

The expression of microRNA-21 (miR-21) was determined in 42 patients with colorectal cancer (CRC) using real-time reverse transcription-polymerase chain reaction. The level of miR-21 in CRC tumour tissue was compared with paired normal adjacent tissue (NAT) and the relationships of miR-21 levels to clinicopathological characteristics and pathological tumour response to neoadjuvant chemotherapy were investigated. There was a significantly higher level of miR-21 in CRC tumour tissue than in NAT and high expression of miR-21 was significantly correlated with advanced clinical stage and poor cell differentiation. Receiver operating characteristic curve analysis indicated a maximum optimal cut-off cycle threshold value of 10.32 for differentiating pathological responders from non-responders, with a sensitivity of 80.0% and specificity of 88.2%. These data showed that miR-21 was significantly overexpressed in CRC tumour tissue and was associated with advanced CRC, and that miR-21 may be a potential candidate biomarker for predicting pathological tumour response to chemotherapy.

microRNA signature for human pancreatic cancer invasion and metastasis

Pancreatic cancer has the poorest prognosis among all human malignant solid tumors, mainly due to its high invasive and metastatic biological features. microRNAs (miRNAs) are a group of endogenous and small non-coding RNA molecules 18-25 nucleotides in length, functioning as either tumor-suppressor genes or oncogenes. Evidence has shown that regulation of miRNAs in pancreatic cancer is associated with tumor growth, invasion, metastasis and resistance to therapy. Over the last decade, many studies have also found that there is a close relationship between miRNAs and biological characteristics of pancreatic cancer invasion and metastasis, such as the presence of cancer stem cells, epithelial-mesenchymal transition (EMT) phenotype, DNA methylation or epigenetic alteration, and the activation of some specific signaling pathways. Therefore, better understanding of the complex role of miRNAs in the development and progression of pancreatic cancer metastasis may provide new insights that could be of therapeutic consequence. In this brief review, we discuss the literature concerning the correlation between miRNAs and pancreatic cancer, focusing on miRNAs that contribute to pancreatic cancer invasion and metastasis, particularly on cancer stem cell characteristics, the EMT process, epigenetic modifications and tumor-associated signaling pathways.

Altered microRNA expression in cisplatin-resistant ovarian cancer cells and upregulation of miR-130a associated with MDR1/P-glycoprotein-mediated drug resistance

microRNAs (miRNAs) are short non-coding RNA molecules which are involved in the regulation of various biological processes. Drug resistance has become a major obstacle to successful chemotherapy of ovarian cancer. The aim of this study was to investigate microRNA expression profiles in cisplatin-resistant ovarian cancer cells and the role of miR-130a in regulating drug resistance. Analysis of differentially expressed miRNAs between SKOV3 and SKOV3/CIS cells was assessed by miRNA microarrays. Target prediction of miRNAs was determined with the help of PicTar or TargetScan. Among these miRNAs, the expression of miR‑130a was verified using qRT-PCR. The expression of MDR1 mRNA and P-glycoprotein (P-gp) after cellular transfection was examined using qRT-PCR and western blotting, respectively. Cisplatin sensitivity was detected by the MTT assay. We indentified 35 downregulated and 54 upregulated miRNAs in SKOV3/CIS compared to those in SKOV3. We found that miR-130a was upregulated in SKOV3/CIS compared to the parental SKOV3 cells, and PTEN was predicted to be the potential target of miR-130a. Moreover, downregulation of miR-130a could inhibit MDR1 mRNA and P-gp expression and overcome the cisplatin resistance in SKOV3/CIS cells, which indicated that miR-130a may be associated with MDR1/P-gp-mediated drug resistance and plays the role of an intermediate in drug-resistance pathways of PI3K/Akt/PTEN/mTOR and ABC superfamily drug transporters in SKOV3/CIS cells. This study provides important information for the development of targeted gene therapy for reversing cisplatin resistance in ovarian cancer.

Oocytes selected using BCB staining enhance nuclear reprogramming and the in vivo development of SCNT embryos in cattle

The selection of good quality oocytes is crucial for in vitro fertilization and somatic cloning. Brilliant cresyl blue (BCB) staining has been used for selection of oocytes from several mammalian species. However, the effects of differential oocyte selection by BCB staining on nuclear reprogramming and in vivo development of SCNT embryos are not well understood. Immature compact cumulus-oocyte complexes (COCs) were divided into control (not exposed to BCB), BCB+ (blue cytoplasm) and BCB- (colorless cytoplasm) groups. We found that BCB+ oocytes yielded a significantly higher somatic cell nuclear transfer (SCNT) blastocyst rate and full term development rate of bovine SCNT embryos than the BCB- and control oocytes. BCB+ embryos (embryos developed from BCB+ oocytes) showed increased acetylation levels of histone H3 at K9 and K18 (AcH3K9, AcH3K18), and methylation levels of histone H3 at K4 (H3K4me2) than BCB- embryos (embryos developed from BCB- oocytes) at the two-cell stage. Furthermore, BCB+ embryos generated more total cells, trophectoderm (TE) cells, and inner cell mass (ICM) cells, and fewer apoptotic cells than BCB- embryos. The expression of SOX2, CDX2, and anti-apoptotic microRNA-21 were up-regulated in the BCB+ blastocysts compared with BCB- blastocysts, whereas the expression of pro-apoptotic gene Bax was down-regulated in BCB+ blastocysts. These results strongly suggest that BCB+ oocytes have a higher nuclear reprogramming capacity, and that BCB staining can be used to select developmentally competent oocytes for nuclear transfer.

Aberrant epigenetic grooming of miRNAs in pancreatic cancer: a systems biology perspective

Pancreatic cancer (PC) is a complex disease harboring a myriad of genetic and epigenetic changes. The dismal survival of patients diagnosed with PC is in part due to de novo and acquired resistance to conventional therapeutics, resulting from deregulated signaling including aberrant expression of small nc miRNAs. Emerging research in this area has lead to the identification and characterization of deregulated miRNAs, which have generated a renewed interest and hope in that novel targeting of miRNAs may lead to a better clinical outcome for patients diagnosed with PC. However, recent evidence suggests that miRNAs are also under a highly coordinated system of epigenetic regulation emphasizing the fact that the design of miRNAs as targeted therapy may not be as simple as originally anticipated. For a successful miRNA-based therapeutic regimen, a holistic integrated approach may be required to take into account because of these emerging epigenetic regulatory mechanisms. In this article, we will discuss miRNA epigenetics, it's significance in PC and the use of a systems science to identify these aberrant epigenetically groomed miRNAs, and we believe that such knowledge would likely benefit further research to realize the dream of miRNA-based targeted therapy for human malignancies.

miRNAs in breast cancer: ready for real time?

Over the past decade, major advances in our comprehension of breast cancer biology have led to improved diagnostic and prognostic techniques and the development of novel targeted therapies. However, the efficacy of new treatments remains limited by a combination of drug toxicity, resistance and persisting insufficiencies in our understanding of tumor-signaling pathways; furthermore, the reliability of identified biomarkers is contentious. Following their recent discovery, miRNAs have been established as critical regulators of gene expression, and their putative roles as oncogenes and tumor-suppressor genes has provided a potential new dimension to our clinical approach to breast cancer diagnosis and treatment. Their role as biomarkers and therapeutic targets is appealing; however, several barriers have limited our ability to translate this potential into a clinical reality. This review focuses on the currently accepted roles of miRNAs in breast cancer pathogenesis, and highlights the clinical challenges and breakthroughs in this field to date.