Comprehensive microRNA Profiling of Prostate Cancer

A potential regulatory loop between Lin28B:miR‑212 in androgen-independent prostate cancer

Lin28 is a family of RNA binding proteins and microRNA regulators. Two members of this family have been identified: Lin28A and Lin28B, which are encoded by genes localized in different chromosomes but share a high degree of sequence identity. The role of Lin28B in androgen-independent prostate cancer (AIPC) is not well understood. Lin28B is expressed in all grades of prostatic carcinomas and prostate cancer cell lines, but not in normal prostate tissue. In this study we found that Lin28B co-localized in the nucleus and cytoplasm of the DU145 AIPC. The expression of Lin28B protein positively correlated with the expression of the c-Myc protein in the prostate cancer cell lines and silencing of Lin28B also correlated with a lower expression of the c-Myc protein, but not with the downregulation of c-Myc messenger RNA (mRNA) in the DU145 AIPC cells. We hypothesized that Lin28B regulates the expression of c-Myc protein by altering intermediate c-Myc suppressors. Therefore, a microRNA profile of DU145 cells was performed after Lin28B siRNA silencing. Nineteen microRNAs were upregulated and eleven microRNAs were downregulated. The most upregulated microRNAs were miR-212 and miR-2278. Prior reports have found that miR-212 is suppressed in prostate cancer. We then ran TargetScan software to find potential target mRNAs of miR-212 and miR-2278, and it predicted Lin28B mRNA as a potential target of miR-212, but not miR-2278. TargetScan also predicted that c-Myc mRNA is not a potential target of miR-212 or miR-2278. These observations suggest that Lin28B:miR-212 may work as a regulatory loop in androgen-independent prostate cancer. Furthermore, we report a predictive 2-fold symmetric model generated by the superposition of the Lin28A structure onto the I-TASSER model of Lin28B. This structural model of Lin28B suggests that it shows unique microRNA binding characteristics. Thus, if Lin28B were to bind miRNAs in a manner similar to Lin28A, conformational changes would be necessary to prevent steric clashes in the C-terminal and linker regions between the CSD and ZNF domains.

MiR-198 represses tumor growth and metastasis in colorectal cancer by targeting fucosyl transferase 8

In this study we investigated the biological role and mechanism of miR-198 in colorectal carcinoma (CRC). MiR-198 expression was shown to exhibit a strongly negative correlation with lymph node invasion, distant metastasis and patient survival in examinations of colorectal cancer tissues and paired normal colorectal mucosa tissues. fucosyl transferase 8 (FUT8) was identified as a potential target of miR-198 in bioinformatics analysis and luciferase reporter assays. Overexpression of miR-198 in CRC cell lines decreased FUT8 levels as shown by immunofluorescence analysis, and inhibited cell proliferation, migration, and invasion. These anti-tumor phenotypes were rescued by reconstitution of FUT8 expression. Furthermore, miR-198 was shown to target the 3′UTR of FUT8 directly to downregulate FUT8 expression at both mRNA and protein levels in qRT-PCR and Western blot analyses, respectively. In vivo, restoration of miR-198 significantly inhibited xenograft growth and invasion of CRC tumors in nude mice. Therefore, it could be concluded that miR-198 suppresses the proliferation and invasion of CRC by directly targeting FUT8.

Noncoding RNAs as novel biomarkers in prostate cancer

Prostate cancer (PCa) is the second most common diagnosed malignant disease in men worldwide. Although serum PSA test dramatically improved the early diagnosis of PCa, it also led to an overdiagnosis and as a consequence to an overtreatment of patients with an indolent disease. New biomarkers for diagnosis, prediction, and monitoring of the disease are needed. These biomarkers would enable the selection of patients with aggressive or progressive disease and, hence, would contribute to the implementation of individualized therapy of the cancer patient. Since the FDA approval of the long noncoding PCA3 RNA-based urine test for the diagnosis of PCa patients, many new noncoding RNAs (ncRNAs) associated with PCa have been discovered. According to their size and function, ncRNAs can be divided into small and long ncRNAs. NcRNAs are expressed in (tumor) tissue, but many are also found in circulating tumor cells and in all body fluids as protein-bound or incorporated in extracellular vesicles. In these protected forms they are stable and so they can be easily analyzed, even in archival specimens. In this review, the authors will focus on ncRNAs as novel biomarker candidates for PCa diagnosis, prediction, prognosis, and monitoring of therapeutic response and discuss their potential for an implementation into clinical practice.

Binding sites of miR-1273 family on the mRNA of target genes

This study examined binding sites of 2,578 miRNAs in the mRNAs of 12,175 human genes using the MirTarget program. It found that the miRNAs of miR-1273 family have between 33 and 1,074 mRNA target genes, with a free hybridization energy of 90% or more of its maximum value. The miR-1273 family consists of miR-1273a, miR-1273c, miR-1273d, miR-1273e, miR-1273f, miR-1273g-3p, miR-1273g-5p, miR-1273h-3p, and miR-1273h-5p. Unique miRNAs (miR-1273e, miR-1273f, and miR-1273g-3p) have more than 400 target genes. We established 99 mRNA nucleotide sequences that contain arranged binding sites for the miR-1273 family. High conservation of each miRNA binding site in the mRNA of the target genes was found. The arranged binding sites of the miR-1273 family are located in the 5′UTR, CDS, or 3′UTR of many mRNAs. Five repeating sites containing some of the miR-1273 family's binding sites were found in the 3′UTR of several target genes. The oligonucleotide sequences of miR-1273 binding sites located in CDSs code for homologous amino acid sequences in the proteins of target genes. The biological role of unique miRNAs was also discussed.

Systematic identification and characterization of RNA editing in prostate tumors

RNA editing modifies the sequence of primary transcripts, potentially resulting in profound effects to RNA structure and protein-coding sequence. Recent analyses of RNA sequence data are beginning to provide insights into the distribution of RNA editing across the entire transcriptome, but there are few published matched whole genome and transcriptome sequence datasets, and designing accurate bioinformatics methodology has proven highly challenging. To further characterize the RNA editome, we analyzed 16 paired DNA-RNA sequence libraries from prostate tumor specimens, employing a comprehensive strategy to rescue low coverage sites and minimize false positives. We identified over a hundred thousand putative RNA editing events, a third of which were recurrent in two or more samples, and systematically characterized their type and distribution across the genome. Within genes the majority of events affect non-coding regions such as introns and untranslated regions (UTRs), but 546 genes had RNA editing events predicted to result in deleterious amino acid alterations. Finally, we report a potential association between RNA editing of microRNA binding sites within 3′ UTRs and increased transcript expression. These results provide a systematic characterization of the landscape of RNA editing in low coverage sequence data from prostate tumor specimens. We demonstrate further evidence for RNA editing as an important regulatory mechanism and suggest that the RNA editome should be further studied in cancer.

Epithelial and stromal expression of miRNAs during prostate cancer progression

Global microRNA (miRNA) profile may predict prostate cancer (PCa) behaviors. In this study, we examined global miRNA expression by miRNA profiling as well as specific miRNA expression levels in PCa epithelium and stroma by in situ hybridization (ISH) and correlated with various clinicopathological features. We first performed comprehensive miRNA profiling on 27 macrodissected cases of PCa by miRNA microarray. A total of 299 miRNAs were significantly dysregulated in high grade and advanced stage PCa. We demonstrated that PCa can be readily classified into high grade/stage and low-grade/stage groups by its global miRNA expression profile. Next, we examined the expression of several selected dysregulated miRNAs, including let-7c, miR-21, miR-27a, miR-30c, and miR-219, in PCa by ISH. The levels of miRNA expression in epithelial and stromal cells were scored semiquantitatively and compared with clinicopathological features, including age, race, Gleason score, stage, PSA recurrence, metastasis, hormone resistance and survival. We found that the expression of miR-30c and miR-219 were significantly down-regulated in PCa. miR-21 and miR-30c were significantly down-regulated in PCa in African Americans compared to Caucasian Americans. In addition, down-regulation of let-7c, miR-21, miR-30c, and miR-219 are associated with metastatic disease. Furthermore, down-regulation of miR-30c and let-7c are significantly associated with androgen-dependent PCa. In PCa stromal cells, let-7c downregulation is significantly associated with extraprostatic extension. Our data suggest that selected miRNAs may serve as potential biomarkers to predict cancer progression.

miR-212 promotes pancreatic cancer cell growth and invasion by targeting the hedgehog signaling pathway receptor patched-1

Background

microRNAs (miRNAs) are a class of small non-coding RNAs that play important roles in carcinogenesis. In the present study, we investigated the effect of miR-212 on pancreatic ductal adenocarcinoma (PDAC) and its target protein.

Methods

Quantitative real-time PCR(qRT-PCR) was performed to detect the expression of miR-212 in PDAC tissues and pancreatic cancer cell lines. miR-212 mimic, miR-212 inhibitor and negative control were transfected into pancreatic cancer cells and the effect of miR-212 up-regulation and down-regulation on the proliferation, migration and invasion of cells were investigated. Furthermore, the mRNA and protein levels of Patched-1(PTCH1) were measured. Meanwhile, luciferase assays were performed to validate PTCH1 as miR-212 target in PDAC.

Results

miR-212 was up-regulated in PDAC tissues and cells.Using both gain-of function and loss-of function experiments, a pro-oncogenic function of miR-212 was demonstrated in PDAC. Moreover, up-regulated of PTCH1 could attenuate the effect induced by miR-212.

Conclusion

These data suggest that miR-212 could facilitate PDAC progression and metastasis through targeting PTCH1, implicating a novel mechanism for the progression of PDAC.

Differentially expressed miRNAs in cancer-stem-like cells: markers for tumor cell aggressiveness of pancreatic cancer

Pancreatic cancer (PC) is one of the most deadly cancers. The higher mortality is in part due to treatment resistance and early onset of metastasis. The existence of cancer-stem-like cells (CSLCs) has been widely accepted to be responsible for tumor aggressiveness in PC. Emerging evidence suggests that CSLCs have the capacity for increased cell growth, cell migration/invasion, metastasis, and treatment resistance, which leads to poor clinical outcome. However, the molecular role of CSLCs in tumor development and progression is poorly understood. Therefore, mechanistic understanding, and targeted killing of CSLCs may provide a newer therapeutic strategy for the treatment of PC. It has been well accepted that microRNAs (miRNAs) play critical roles during tumor development and progression through deregulation of multiple genes. Moreover, deregulated expression of miRNAs may also play a key role in the regulation of CSLC characteristics and functions. Here we show that isolated CD44(+)/CD133(+)/EpCAM(+) cells (triple-marker-positive cells) from human PC cell lines, MiaPaCa-2 and L3.6pl cells, display aggressive characteristics, such as increased cell growth, clonogenicity, cell migration, and self-renewal capacity, which is consistent with overexpression of CSLC signatures/markers. We also found deregulated expression of over 400 miRNAs, including let-7, miR-30, miR-125b, and miR-335, in CSLCs. As a proof-of-concept, knockdown of miR-125b resulted in the inhibition of tumor cell aggressiveness of CSLCs (triple-marker-positive cells), consistent with the downregulation of CD44, EpCAM, EZH2, and snail. These results clearly suggest the importance of miRNAs in the regulation of CSLC characteristics, and may serve as novel targets for therapy.

Age-associated miRNA alterations in skeletal muscle from rhesus monkeys reversed by caloric restriction

The levels of microRNAs (miRNAs) are altered under different conditions such as cancer, senescence, and aging. Here, we have identified differentially expressed miRNAs in skeletal muscle from young and old rhesus monkeys using RNA sequencing. In old muscle, several miRNAs were upregulated, including miR-451, miR-144, miR-18a and miR-15a, while a few miRNAs were downregulated, including miR-181a and miR-181b. A number of novel miRNAs were also identified, particularly in old muscle. We also examined the impact of caloric restriction (CR) on miRNA abundance by reverse transcription (RT) followed by real-time, quantitative (q)PCR analysis and found that CR rescued the levels of miR-181b and chr1:205580546, and also dampened the age-induced increase in miR-451 and miR-144 levels. Our results reveal that there are changes in expression of known and novel miRNAs with skeletal muscle aging and that CR may reverse some of these changes to a younger phenotype.

Different miRNA expression profiles between human breast cancer tumors and serum

A bunch of microRNAs (miRNAs) have been demonstrated to be aberrantly expressed in cancer tumor tissue and serum. The miRNA signatures identified from the serum samples could serve as potential noninvasive diagnostic markers for breast cancer. The role of the miRNAs in cancerigenesis is unclear. In this study, we generated the expression profiles of miRNAs from the paired breast cancer tumors, normal, tissue, and serum samples from eight patients using small RNA-sequencing. Serum samples from eight healthy individuals were used as normal controls. We identified total 174 significantly differentially expressed miRNAs between tumors and the normal tissues, and 109 miRNAs between serum from patients and serum from healthy individuals. There are only 10 common miRNAs. This suggests that only a small portion of tumor miRNAs are released into serum selectively. Interestingly, the expression change pattern of 28 miRNAs is opposite between breast cancer tumors and serum. Functional analysis shows that the differentially expressed miRNAs and their target genes form a complex interaction network affecting many biological processes and involving in many types of cancer such as prostate cancer, basal cell carcinoma, acute myeloid leukemia, and more.

miRNA in Prostate Cancer: New Prospects for Old Challenges

Prostate cancer (PCa) is one of the most commonly diagnosed cancers among men but has limited prognostic biomarkers available for follow up. MicroRNAs (miRNAs) are small non-coding RNAs that regulate expression of their target genes. Accumulating experimental evidence reports differential miRNA expression in PCa, and that miRNAs are actively involved in the pathogenesis and progression of PCa. miRNA and androgen receptor signaling cross-talk is an established factor in PCa pathogenesis. Differential miRNA expression was found between patients with high versus low Gleason scores, and was also observed in patients with biochemical failure, hormone-resistant cancer and in metastasis. Metastasis requires epithelial-mesenchymal transition which shares many cancer stem cell biological characteristics and both are associated with miRNA dysregulation. In the era of personalized medicine, there is a broad spectrum of potential clinical applications of miRNAs. These applications can significantly improve PCa management including their use as diagnostic and/or prognostic markers, or as predictive markers for treatment efficiency. Preliminary evidence demonstrates that miRNAs can also be used for risk stratification. Circulatory miRNAs can serve as non-invasive biomarkers in urine and/or serum of PCa patients. More recently, analysis of miRNAs and circulating tumor cells are gaining significant attention. Moreover, miRNAs represent an attractive new class of therapeutic targets for PCa. Here, we summarize the current knowledge and the future prospects of miRNAs in PCa, their advantages, and potential challenges as tissue and circulating biomarkers. Prostate cancer (PCa) is the most commonly diagnosed cancer among men in western populations. The American Cancer Society estimated 239, 590 new cases and 29, 720 expected deaths in the USA in 2013. One in every six men are at risk of developing PCa during their lifetime (1). Currently, the standard biomarker for PCa diagnosis is prostate-specific antigen (PSA), which has its limitations, leading to the risks of PCa over diagnosis and harmful overtreatment. The prognostic value of PSA is also questionable (2). Stepping into the new epoch of personalized medicine, molecular markers are urgently needed to improve the different aspects of PCa management (3). miRNAs represent an attractive class of emerging biomarkers that can help in this regard (4;5).

Role of microRNA in response to ionizing radiations: evidences and potential impact on clinical practice for radiotherapy

MicroRNAs (miRNA) are small, non-coding, RNAs with gene expression regulator roles. As an important class of regulators of many cellular pathways, miRNAs are involved in many signaling pathways and DNA damage repair processes, affecting cellular radiosensitivity. Their role has led to interest in oncological implications to improve treatment results. MiRNAs represent a great opportunity to enhance the efficacy of radiotherapy treatments-they can be used to profile the radioresistance of tumors before radiotherapy, monitor their response throughout the treatment, thus helping to select intensification strategies, and also to define the final response to therapy along with risks of recurrence or metastatization. Even though many interesting studies support such potential, nowadays most studies on patient data are limited to experiments profiling tumor aggressiveness and response to radiotherapy. Moreover many studies report different although not conflicting results on the miRNAs evaluated for each tumor type. Without doubt, the clinical potential of such molecules for radiotherapy is striking and of high interest.

Influence of peripheral whole-blood microRNA-7 and microRNA-221 high expression levels on the acquisition of castration-resistant prostate cancer: evidences from in vitro and in vivo studies

Prostate cancer (PC) is the more frequently diagnosed neoplasia in men in developed countries. The evolution of PC to castration-resistant prostate cancer (CRPC) represents real problems of clinical management, in consequence to the limited therapeutic options. MicroRNAs (miRNAs) are small noncoding RNAs that play an important role in gene expression and function regulation. The increased evidence that miRNAs are involved in cancer development and progression has made them potential biomarkers for cancer diagnosis, prognosis, and aggressiveness. Our purpose was to identify a miRNA expression profile associated with the development of CRPC. We firstly observed a miRNA expression profile differentially expressed between the castration-resistant (CR) PC3 cell line and the hormone-sensitive LnCaP cell line, where miR-7, miR-221, and miR-222 were upregulated in PC3 (11.3-fold increase, P = 0.012; 11.3-fold increase, P = 0.002; 8.6-fold increase, P = 0.002, respectively). We also observed that the trend of miR-1233 expression levels was higher in PC3 (3.7-fold increase, P = 0.057). These miRNAs differentially expressed in vitro were studied in a peripheral whole-blood samples from PC patients. We observed that patients presenting an early CR acquisition (≤ 20 months) had higher expression levels of miR-7 and miR-221 (P = 0.034 and P = 0.036, respectively). Furthermore, we found that patients diagnosed with high-Gleason score tumors and presenting simultaneous higher miR-7 expression levels have a significant reduce time to CR compared with patients who present lower miR-7 expression levels (11 vs. 51 months, log-rank test P = 0.004). We also found that patients diagnosed with high-Gleason score tumors and higher expression levels of miR-221 have an early CRPC compared to patients with lower miR-221 expression levels (10 vs. 46 months, log-rank test P = 0.012). We observed a significantly lower overall survival in patients with higher peripheral whole-blood expression levels of miR-7 (28 vs. 116 months, log-rank test P = 0.001). Our results suggest that miR-7 and miR-221 peripheral whole-blood expression levels can be potential predictive biomarkers of CRPC development.

PAX6, a novel target of miR-335, inhibits cell proliferation and invasion in glioma cells

Paired box 6 (PAX6), a highly conserved transcription factor, is important in glioma. However, the molecular mechanisms involved remain unclear. The present study demonstrated that the expression of PAX6 was significantly reduced with the malignancy of glioma and also identified PAX6 as a novel target of microRNA (miR)‑335, which was significantly upregulated in glioma. The inhibition of miR‑335 increased the protein expression of PAX6, whereas the upregulation of miR‑335 suppressed its expression in human glioma U251 and U87 cells. Furthermore, upregulation of miR-335 promoted U251 cell proliferation, colony formation and invasion, which was reversed by the overexpression of PAX6. Furthermore, the present study demonstrated that the effect of miR‑335 on U251 cell invasion was via the modulation of matrix metalloproteinase (MMP)‑2 and MMP‑9 expression by targeting PAX6. In conclusion, the present study demonstrated that PAX6, as a novel target of miR‑335, has an anti‑oncogenic function in glioma, and thus PAX6 may serve as a therapeutic target for glioma.

MicroRNA-215 is a potential prognostic marker for cervical cancer

Recently, microRNAs (miRNAs) have been shown to be involved in multiple biological pathways that can influence tumor progression and metastasis and they can serve as prognostic biomarkers in many cancers. The present study examined the prognostic significance of miR-215 in cervical cancer. The paraffin-embedded paired cervical scrape samples and tumor tissue samples from 302 patients with stage II cervical cancer were detected for the expression of miR-215 by using qRT-PCR. A miR-215-based classifier was established by using the Cox regression model. The prognostic and predictive accuracy of this classifier was determined in both the internal testing group of 138 patients, and the external independent group of 280 patients. Moreover, cervical cancer HeLa cells overexpressing miR-215 (HeLa-miR-215) were constructed and subcutaneously injected into the nude mice to examine the effect of miR-215 on tumor growth and metastasis in vivo. The results showed that the expression level of miR-215 was significantly higher in cervical cancer tissues than in paired normal tissues (P<0.0001). When patients were classified into high- and low-risk cancer progression groups according to miR-215 level, the 5-year disease-free survival in high- and low-risk groups were 43% (95% CI: 32.1-51.6) and 67% (95% CI: 48.6-77.3) (hazard ratio [HR] 2.02, 95% CI: 1.16-3.52; P=0.013) respectively. Moreover, the expression level of miR-215 was negatively associated with survival rate in patients at TNM stage T3 (HR: 3.317; 95% CI: 1.18-5.14, P=0.017) and TNM stage T4 (HR: 3.48; 95% CI: 1.49-4.45, P=0.008). Tumor volume in nude mice injected with HeLa-miR-215 cells was significantly larger than that in mice injected with control HeLa cells. It was concluded that the expression level of miR-215 is associated with cervical tumor progression and worse survival rate, suggesting that it may serve as a potential prognostic marker to identify patients at higher risk of recurrence.

Clinical significance of microRNA 138 and cyclin D3 in hepatocellular carcinoma

BACKGROUND

MicroRNA 138 (miR-138) is recently shown to inhibit tumor growth and block cell cycle arrest of hepatocellular carcinoma (HCC) by targeting cyclin D3 (CCND3). The aim of this study was to investigate the clinical significance of miR-138 and CCND3 in human HCC, which remains unclear.

METHODS

Quantitative real-time polymerase chain reaction analysis was performed to detect the expression levels of miR-138 and CCND3 messenger RNA (mRNA) in 180 self-pairs of HCC and noncancerous liver tissues.

RESULTS

Compared with noncancerous liver tissues, the expression levels of miR-138 in HCC tissues were significantly downregulated (P < 0.001), whereas the expression levels of CCND3 mRNA in HCC tissues were significantly upregulated (P < 0.001). There was a negative correlation between miR-138 and CCND3 mRNA expression in HCC tissues (r = -0.56, P = 0.02). Additionally, statistical analysis showed that the combined miR 138 downregulation and CCND3 upregulation (miR-138-low-CCND3-high) was significantly associated with the advanced tumor-node-metastasis stage (P = 0.008) and the presence of portal vein invasion (P = 0.008) and lymph node metastasis (P = 0.01). More importantly, a significant trend was identified between the combined expression of miR-138-low-CCND3-high in HCC and worsening clinical prognosis. Multivariate survival analysis further recognized miR-138-low-CCND3-high expression as an independent prognostic factor for patients with HCC.

CONCLUSIONS

Our data suggest that the combined expression of miR-138 and its direct target CCND3 may be correlated with significant characteristics of HCC. MiR-138 downregulation and CCND3 upregulation maybe concurrently associated with prognosis in patients with HCC.

Mir-184 post-transcriptionally regulates SOX7 expression and promotes cell proliferation in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common human malignancies and the third leading cause of cancer mortality worldwide. The development and progression of HCC is a complicated process, involving the deregulation of multiple genes that are essential to cell biological processes. Recently, microRNAs (miRNAs) have been suggested to be closely associated with tumorigenesis. Our study showed that miR-184 is upregulated in HCC cell lines and tissues. Overexpression of miR-184 in HCC cells increased cell proliferation, tumorigenicity, and cell cycle progression, whereas inhibition of miR-184 reduced cell proliferation, tumorigenicity, and cell cycle progression. Additionally, we identified SOX7 as a direct target of miR-184. Ectopic expression of miR-184 led to downregulation of the SOX7 protein, resulting in upregulation of c-Myc, Cyclin D1, and phosphorylation of Rb. Our findings suggested that miR-184 represents a potential onco-miR and plays an important role in HCC progression by suppressing SOX7 expression.

Elevated expression of prostate cancer-associated genes is linked to down-regulation of microRNAs

Background

Recent evidence suggests that the prostate cancer (PCa)-specific up-regulation of certain genes such as AMACR, EZH2, PSGR, PSMA and TRPM8 could be associated with an aberrant expression of non-coding microRNAs (miRNA).

Methods

In silico analyses were used to search for miRNAs being putative regulators of PCa-associated genes. The expression of nine selected miRNAs (hsa-miR-101, -138, -186, -224, -26a, -26b, -374a, -410, -660) as well as of the aforementioned PCa-associated genes was analyzed by quantitative PCR using 50 malignant (Tu) and matched non-malignant (Tf) tissue samples from prostatectomy specimens as well as 30 samples from patients with benign prostatic hyperplasia (BPH). Then, correlations between paired miRNA and target gene expression levels were analyzed. Furthermore, the effect of exogenously administered miR-26a on selected target genes was determined by quantitative PCR and Western Blot in various PCa cell lines. A luciferase reporter assay was used for target validation.

Results

The expression of all selected miRNAs was decreased in PCa tissue samples compared to either control group (Tu vs Tf: -1.35 to -5.61-fold; Tu vs BPH: -1.17 to -5.49-fold). The down-regulation of most miRNAs inversely correlated with an up-regulation of their putative target genes with Spearman correlation coefficients ranging from -0.107 to -0.551. MiR-186 showed a significantly diminished expression in patients with non-organ confined PCa and initial metastases. Furthermore, over-expression of miR-26a reduced the mRNA and protein expression of its potential target gene AMACR in vitro. Using the luciferase reporter assay AMACR was validated as new target for miR-26a.

Conclusions

The findings of this study indicate that the expression of specific miRNAs is decreased in PCa and inversely correlates with the up-regulation of their putative target genes. Consequently, miRNAs could contribute to oncogenesis and progression of PCa via an altered miRNA-target gene-interaction.

Low expression of microRNA-126 is associated with poor prognosis in colorectal cancer

MicroRNA-126 (miR-126) has been reported to be a tumor suppressor that targets CXCR4 in colorectal cancer (CRC) cells. This study investigated whether miR-126 has any prognostic impact in patients with CRC. MiR-126 and CXCR4 mRNA expression in 92 pairs of CRC and adjacent nontumorous tissues was examined using quantitative real-time PCR, and CXCR4 protein expression was assessed by immunohistochemistry (IHC) and Western blotting. The correlation between miR-126 and CXCR4 protein expression and clinicopathological features and overall survival rate was determined. MiR-126 was downregulated in CRC tissues that expressed high levels of CXCR4 mRNA. IHC and Western blotting detected high expression of CXCR4 protein in CRC tissues. An inverse correlation was observed between miR-126 and CXCR4 protein expression in CRC tissues. Moreover, low miR-126 and high CXCR4 protein expression was associated with distant metastasis, clinical TNM stage, and poor survival. Multivariate analysis indicated that miR-126 was an independent prognostic factor for overall survival, suggesting its clinical significance as a prognostic predictor in CRC patients.

Comprehensive microRNA profiling of prostate cancer cells after ionizing radiation treatment

MicroRNAs (miRNAs) are small, non-coding RNAs that negatively regulate gene expression and have emerged as potential biomarkers in radiation response to human cancer. Only a few miRNAs have been identified in radiation response to prostate cancer and the involvement of the radiation-associated miRNA machinery in the response of prostate cancer cells to radiation is not thoroughly understood. Therefore, the purpose of the present study was to comprehensively investigate the expression levels, arm selection preference and isomiRs of radiation-response miRNAs in radiation-treated PC3 cells using a next-generation sequencing (NGS) approach. Our data revealed that the arm selection preference and 3′ modification of miRNAs may be altered in prostate cancer after radiation exposure. In addition, the proportion of AA dinucleotide modifications at the end of the read gradually increased in a time-dependent manner after PC3 radiation treatment. We also identified 6 miRNAs whose expression increased and 16 miRNAs whose expression decreased after exposure to 10 Gy of radiation. A pathway enrichment analysis revealed that the target genes of these radiation-induced miRNAs significantly co-modulated the radiation response pathway, including the mitogen-activated protein kinase (MAPK), Wnt, transforming growth factor-β (TGF-β) and ErbB signaling pathways. Furthermore, analysis of The Cancer Genome Atlas (TCGA) database revealed that the expression of these radiation-induced miRNAs was frequently dysregulated in prostate cancer. Our study identified radiation-induced miRNA candidates which may contribute to radiosensitivity and can be used as biomarkers for radiotherapy.

Enhanced shedding of extracellular vesicles from amoeboid prostate cancer cells: potential effects on the tumor microenvironment

The gene encoding the cytoskeletal regulator DIAPH3 is lost at high frequency in metastatic prostate cancer, and DIAPH3 silencing evokes a transition to an amoeboid tumor phenotype in multiple cell backgrounds. This amoeboid transformation is accompanied by increased tumor cell migration, invasion, and metastasis. DIAPH3 silencing also promotes the formation of atypically large (> 1 μm) membrane blebs that can be shed as extracellular vesicles (EV) containing bioactive cargo. Whether loss of DIAPH3 also stimulates the release of nano-sized EV (e.g., exosomes) is not established. Here we examined the mechanism of release and potential biological functions of EV shed from DIAPH3-silenced and other prostate cancer cells. We observed that stimulation of LNCaP cells with the prostate stroma-derived growth factor heparin-binding EGF-like growth factor (HB-EGF), combined with p38MAPK inhibition caused EV shedding, a process mediated by ERK1/2 hyperactivation. DIAPH3 silencing in DU145 cells also increased rates of EV production. EV isolated from DIAPH3-silenced cells activated AKT1 and androgen signaling, increased proliferation of recipient tumor cells, and suppressed proliferation of human macrophages and peripheral blood mononuclear cells. DU145 EV contained miR-125a, which suppressed AKT1 expression and proliferation in recipient human peripheral blood mononuclear cells and macrophages. Our findings suggest that EV produced as a result of DIAPH3 loss or growth factor stimulation may condition the tumor microenvironment through multiple mechanisms, including the proliferation of cancer cells and suppression of tumor-infiltrating immune cells.

Higher circulating expression levels of miR-221 associated with poor overall survival in renal cell carcinoma patients

The mechanisms involved in renal cell carcinoma (RCC) development and progression remain unclear, and new biomarkers for early detection, follow-up of the disease and prognosis are needed in routine practice to improve the diagnostic and/or prognostic accuracy. There is increasing evidence that microRNAs (miRNAs) are involved in cancer development and progression. The up-regulation of miR-221/222 has been described in several human cancers, and during RCC development, this up-regulation can modulate the metastatic process. Our purpose was to investigate the circulating expression levels of miR-221/222 as potential biomarkers for RCC detection and their influence in patients' overall survival. The circulating miR-221/222 was studied by relative quantification in 77 plasma samples. A follow-up study was undertaken to evaluate the overall survival. We observed that RCC patients presented higher circulating expression levels of miR-221 and miR-222 than healthy individuals (2(-ΔΔCt) = 2.8, P = 0.028; 2(-ΔΔCt) = 2.2, P = 0.044, respectively). The RCC patients with metastasis at diagnosis also presented higher circulating expression levels of miR-221 than patients with no metastasis (2(-ΔΔCt) = 10.9, P = 0.001). We also observed a significantly lower overall survival in patients with higher expression levels of miR-221 (48 vs 116 months, respectively; P = 0.024). Furthermore, multivariate Cox regression analysis using the tumour, nodes and metastasis stage (TNM stage); Fuhrman nuclear grade and age (≥60 years) as covariants demonstrated a higher risk of specific death by cancer in patients who presented higher expression levels of miR-221 (hazard ratio (HR) = 10.7, 95% confidence interval 1.33-85.65, P = 0.026). The concordance (c) index showed that the definition of profiles that contain information regarding tumour characteristics associated with circulating miR-221 expression information presents an increased capacity to predict the risk of death by RCC (c index model 1, 0.800 vs model 2, 0.961). Our results, which identified the plasma miR-221/222 at variable levels during RCC development, suggest that these miRNAs may have a potential as noninvasive biomarkers of RCC development.

Association of microRNA-126 expression with clinicopathological features and the risk of biochemical recurrence in prostate cancer patients undergoing radical prostatectomy

Objective

Numerous studies have suggested that microRNA-126 (miR-126) is involved in development of various cancer types as well as in malignant proliferation and invasion. However, its role in human prostate cancer (PCa) is still unclear. The aim of this study was to investigate miR-126 expression in PCa and its prognostic value for PCa patients undergoing radical prostatectomy.

Methods

A series of 128 cases with PCa were evaluated for the expression levels of miR-126 by quantitative reverse-transcription PCR (qRT-PCR). Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between miR-126 expression and prognosis of PCa patients.

Results

Compared with non-cancerous prostate tissues, the expression level of miR-126 was significantly decreased in PCa tissues (PCa vs. non-cancerous prostate: 1.05 ± 0.63 vs. 2.92 ± 0.98, P < 0.001). Additionally, the loss of miR-126 expression was dramatically associated with aggressive clinical pathological features, including advanced pathological stage (P = 0.001), positive lymph node metastasis (P = 0.006), high preoperative PSA (P = 0.003) and positive angiolymphatic invasion (P = 0.001). Moreover, Kaplan–Meier survival analysis showed that PCa patients with low miR-126 expression have shorter biochemical recurrence (BCR)-free survival than those with high miR-126 expression. Furthermore, multivariate analysis indicated that miR-126 expression was an independent prognostic factor for BCR-free survival after radical prostatectomy.

Conclusion

These findings suggest for the first time that the loss of miR-126 expression may play a positive role in the malignant progression of PCa. More importantly, the downregulation of miR-126 may serve as an independent predictor of BCR-free survival in patients with PCa.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1740080792113255.

Molecular markers for prostate cancer in formalin-fixed paraffin-embedded tissues

Prostate cancer (PCa) is the most frequently diagnosed type of cancer in developed countries. The decisive method of diagnosis is based on the results of biopsies, morphologically evaluated to determine the presence or absence of cancer. Although this approach leads to a confident diagnosis in most cases, it can be improved by using the molecular markers present in the tissue. Both miRNAs and proteins are considered excellent candidates for biomarkers in formalin-fixed paraffin-embedded (FFPE) tissues, due to their stability over long periods of time. In the last few years, a concerted effort has been made to develop the necessary tools for their reliable measurement in these types of samples. Furthermore, the use of these kinds of markers may also help in establishing tumor grade and aggressiveness, as well as predicting the possible outcomes in each particular case for the different treatments available. This would aid clinicians in the decision-making process. In this review, we attempt to summarize and discuss the potential use of microRNA and protein profiles in FFPE tissue samples as markers to better predict PCa diagnosis, progression, and response to therapy.

Cancer development, progression, and therapy: an epigenetic overview

Carcinogenesis involves uncontrolled cell growth, which follows the activation of oncogenes and/or the deactivation of tumor suppression genes. Metastasis requires down-regulation of cell adhesion receptors necessary for tissue-specific, cell-cell attachment, as well as up-regulation of receptors that enhance cell motility. Epigenetic changes, including histone modifications, DNA methylation, and DNA hydroxymethylation, can modify these characteristics. Targets for these epigenetic changes include signaling pathways that regulate apoptosis and autophagy, as well as microRNA. We propose that predisposed normal cells convert to cancer progenitor cells that, after growing, undergo an epithelial-mesenchymal transition. This process, which is partially under epigenetic control, can create a metastatic form of both progenitor and full-fledged cancer cells, after which metastasis to a distant location may occur. Identification of epigenetic regulatory mechanisms has provided potential therapeutic avenues. In particular, epigenetic drugs appear to potentiate the action of traditional therapeutics, often by demethylating and re-expressing tumor suppressor genes to inhibit tumorigenesis. Epigenetic drugs may inhibit both the formation and growth of cancer progenitor cells, thus reducing the recurrence of cancer. Adopting epigenetic alteration as a new hallmark of cancer is a logical and necessary step that will further encourage the development of novel epigenetic biomarkers and therapeutics.

Microenvironmental regulation of cancer metastasis by miRNAs

miRNAs are a class of small, non-coding RNAs that regulate cancer progression, especially the processes of invasion and metastasis. Although earlier studies in metastasis primarily focused on the impact that miRNAs have on the intrinsic properties of cancer cells, recent reports reveal that miRNAs also shape interactions between cancer cells and their associated stroma. In this review, we discuss current known mechanisms by which miRNAs execute their microenvironmental regulation of cancer metastasis, including regulating expression of cell membrane-bound and secreted proteins or directly transmitting mature miRNAs between different cell types. The significance of miRNA-mediated tumor-stroma interactions in regulating metastasis suggests that miRNAs may be a potential therapeutic target.

miR-184 functions as an oncogenic regulator in hepatocellular carcinoma (HCC)

Dysregulation of miRNAs has been proved to play a key role in carcinogenesis or tumor progression. In hepatocellular carcinoma (HCC), a number of miRNAs was reported to be related to the occurrence and development of HCC. Especially, miRNA-122, a liver-specific miRNA, has been elaborated its role in HCC. However, these studies was not involved in the effect of miRNA-184 on HCC. In the present study, we aimed to detect the miRNA-184 expression in HCC tissues and further evaluate the in vitro effect of miR-184 inhibition in HCC cells HepG2. We found that miR-184 expression was significantly high in HCC tissues, but INPPL1 expression was obviously low. Subsequently, INPPL1 was identified as a target of miRNA-184 by bioinformatics and dual luciferase assay. Moreover, after transfected with anti-miR-184 in HepG2 cells, INPPL1 expression was significantly decreased both at mRNA and protein levels. Additionally, we also proved that miR-184 silencing inhibited cellular proliferation by over expressing INPPL1 and induced HepG2 apoptosis by caspase 3/7. Together, our result was shown that miR-184 might play a part in proliferation of HCC cells by INPPL1 loss and act as antiapoptotic factor in the development of HCC by inhibiting the activities of caspases 3/7. Therefore, further elucidation of miRNA-184 silencing is helpful for understanding the pathogenesis of HCC and devising new strategies for its prevention and therapy.

Identification of aberrant microRNA expression pattern in pediatric gliomas by microarray

Background

Brain tumor remains the leading cause of disease-related death in children. Many studies have focused on the complex biological process involved in pediatric brain tumors but little is know about the possible role of microRNAs in the genesis of these tumors.

Methods

In this study, we used a microRNA microarray assay to study the expression pattern of microRNAs in pediatric gliomas and matched normal tissues.

Results

We found 40 differentially expressed microRNAs, among which miR-1321, miR-513b, miR-769-3p were found be related to cancer genesis for the first time. The expression of selected microRNAs were then confirmed by qRT-PCR. Furthermore, GO and pathway analysis showed that the target genes of the 40 differentially expressed microRNAs were significantly enriched in nervous system-related and tumor-related biological processes and signaling pathways. Additionally, an apoptosis-related network of microRNA–mRNA interaction, representing the critical microRNAs and their targets, was constructed based on microRNA status.

Conclusions

In the present study we identified the changed expression pattern of microRNAs in pediatric gliamas. Our study also provides a better understanding of pediatric brain tumor biology and may assist in the development of less toxic therapies and in the search for better markers for disease stratification.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1323049861105720