MiR-145, a new regulator of the DNA fragmentation factor-45 (DFF45)-mediated apoptotic network

Therapeutic potential of pentamidine for glioma-initiating cells and glioma cells through multimodal antitumor effects

Glioma-initiating cells, which comprise a heterogeneous population of glioblastomas, contribute to resistance against aggressive chemoradiotherapy. Using drug reposition, we investigated a therapeutic drug for glioma-initiating cells. Drug screening was undertaken to select candidate agents that inhibit proliferation of two different glioma-initiating cells lines. The alteration of proliferation and stemness of the two glioma-initiating cell lines, and proliferation, migration, cell cycle, and survival of these two differentiated glioma-initiating cell lines and three different glioblastoma cell lines treated with the candidate agent were evaluated. We also used a xenograft glioma mouse model to evaluate anticancer effects of treated glioma cell lines. Among the 1301 agents, pentamidine-an antibiotic for Pneumocystis jirovecii-emerged as a successful antiglioma agent. Pentamidine treatment suppressed proliferation and stemness in glioma-initiating cell lines. Proliferation and migration were inhibited in all differentiated glioma-initiating cells and glioblastoma cell lines, with cell cycle arrest and caspase-dependent apoptosis induction. The in vivo study reproduced the same findings as the in vitro studies. Pentamidine showed a stronger antiproliferative effect on glioma-initiating cells than on differentiated cells. Western blot analysis revealed pentamidine inhibited phosphorylation of signal transducer and activator of transcription 3 in all cell lines, whereas Akt expression was suppressed in glioma-initiating cells but not in differentiated lines. In the present study, we identified pentamidine as a potential therapeutic drug for glioma. Pentamidine could be promising for the treatment of glioblastomas by targeting both glioma-initiating cells and differentiated cells through its multifaceted antiglioma effects.

The function of miR-145 in colorectal cancer progression; an updated review on related signaling pathways

MicroRNAs (miRNA) are a broad class of small, highly conserved non-coding RNAs that largely influence gene expression after transcription through binding to various target mRNAs. miRNAs are frequently dysregulated in a wide array of human cancers, possessing great value as diagnostic and therapeutic targets. miR-145, as promising tumor suppressor miRNA, also exhibits deregulated expression levels in human malignancies and participates in various processes, including cell proliferation, apoptosis, migration and differentiation. In particular, miR-145 has been shown to be downregulated in colorectal cancer (CRC), which in turn leads to cell growth, invasion, metastasis and drug resistance. Furthermore, miR-145 is involved in the regulation of multiple tumor specific signaling pathways, such as KRAS and P53 signaling by targeting various genes through colorectal tumorigenesis. Therefore, considering its diagnostic and therapeutic potential, it was aimed to present the recent finding focusing on miR-145 functions to better understand its involvement in CRC incidence and progression through interplay with various signaling pathways. This study is based on articles indexed in PubMed and Google scholar until 2021.

Potential Phytochemicals for Prevention of Familial Breast Cancer with BRCA Mutations

Breast cancer has remained a global challenge and the second leading cause of cancer mortality in women and family history. Hereditary factors are some of the major risk factors associated with breast cancer. Out of total breast cancer cases, 5-10% account only for familial breast cancer, and nearly 50% of all hereditary breast cancer are due to BRCA1/BRCA2 germline mutations. BRCA1/2 mutations play an important role not only in determining the clinical prognosis of breast cancer but also in the survival curves. Since this risk factor is known, a significant amount of the healthcare burden can be reduced by taking preventive measures among people with a known history of familial breast cancer. There is increasing evidence that phytochemicals of nutrients and supplements help in the prevention and cure of BRCA-related cancers by different mechanisms such as limiting DNA damage, altering estrogen metabolism, or upregulating expression of the normal BRCA allele, and ultimately enhancing DNA repair. This manuscript reviews different approaches used to identify potential phytochemicals to mitigate the risk of familial breast cancer with BRCA mutations. The findings of this review can be extended for the prevention and cure of any BRCAmutated cancer after proper experimental and clinical validation of the data.

Analysis of miR-143, miR-1, miR-210 and let-7e Expression in Colorectal Cancer in Relation to Histopathological Features

Background: MicroRNAs (miRNAs) are small RNA molecules involved in the control of the expression of many genes and are responsible for, among other things, cell death, differentiation and the control of their division. Changes in miRNA expression profiles have been observed in colorectal cancer. This discovery significantly enriches our knowledge of the pathogenesis of colorectal cancer and offers new goals in diagnostics and therapy. Aim: The aim of this study was to analyze the expression of four miRNA sequences—miR-143, miR-1, miR-210 and let-7e—and to investigate their significance in the risk of developing colorectal cancer. Materials and methods: miRNA sequences were investigated in formalin-fixed, paraffin-embedded (FFPE) tissue in colorectal cancer patients (n = 150) and in cancer-free controls (n = 150). The real-time PCR method was used. Results: This study revealed a lower expression of miR-143 in colorectal cancer patients than in the controls. miR-143 was positively correlated with the degree of tumor differentiation (grading). Three out of four analyzed miRNA (miR-1, miR-210 and let-7e) were found to be statistically insignificant in terms of colorectal carcinoma risk. Conclusions: miR-143 may be associated with the development of colorectal cancer.

MiRNA-145 and Its Direct Downstream Targets in Digestive System Cancers: A Promising Therapeutic Target

MicroRNAs (miRNAs) play a vital role in the onset and development of many diseases, including cancers. Emerging evidence shows that numerous miRNAs have the potential to be used as diagnostic biomarkers for cancers, and miRNA-based therapy may be a promising therapy for the treatment of malignant neoplasm. MicroRNA-145 (miR-145) has been considered to play certain roles in various cellular processes, such as proliferation, differentiation and apoptosis, via modulating the expression of direct target genes. Recent reports show that miR-145 participates in the progression of digestive system cancers, and plays crucial and novel roles in cancer treatment. In this review, we summarize the recent knowledge concerning the function of miR-145 and its direct targets in digestive system cancers. We discuss the potential role of miR-145 as a valuable biomarker for digestive system cancers and how miR-145 regulates these digestive system cancers via different targets to explore the potential strategy of targeting miR-145.

The Role of miRNA in the Pathophysiology of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) represent a tumor group that is both rare and heterogeneous. Prognosis is largely determined by the tumor grading and the site of the primary tumor and metastases. Despite intensive research efforts, only modest advances in diagnostic and therapeutic approaches have been achieved in recent years. For patients with non-respectable tumor stages, prognosis is poor. In this context, the development of novel diagnostic tools for early detection of NETs and prediction of tumor response to therapy as well as estimation of the overall prognosis would greatly improve the clinical management of NETs. However, identification of novel diagnostic molecules is hampered by an inadequate understanding of the pathophysiology of neuroendocrine malignancies. It has recently been demonstrated that microRNA (miRNA), a family of small RNA molecules with an established role in the pathophysiology of quite different cancer entities, may also play a role as a biomarker. Here, we summarize the available knowledge on the role of miRNAs in the development of NET and highlight their potential use as serum-based biomarkers in the context of this disease. We discuss important challenges currently preventing their use in clinical routine and give an outlook on future directions of miRNA research in NET.

Sanguisorba officinalis L. Suppresses Triple-Negative Breast Cancer Metastasis by Inhibiting Late-Phase Autophagy via Hif-1α/Caveolin-1 Signaling

Sanguisorba officinalis L. (SA) is a common herb for cancer treatment in the clinic, particularly during the consolidation phase to prevent occurrence or metastasis. Nevertheless, there are limited studies reporting the molecular mechanisms about its anti-metastatic function. It is well demonstrated that autophagy is one of the critical mechanisms accounting for metastasis and anti-cancer pharmacological actions of Chinese herbs. On the threshold, the regulatory effects and molecular mechanisms of SA in suppressing autophagy-related breast cancer metastasis were investigated in this study. In vitro findings demonstrated that SA potently suppressed the proliferation, colony formations well as metastasis process in triple-negative breast cancer. Network and biological analyses predicted that SA mainly targeted caveolin-1 (Cav-1) to induce anti-metastatic effects, and one of the core mechanisms was via regulation of autophagy. Further experiments—including western blotting, transmission electron microscopy, GFP-mRFP-LC3 immunofluorescence, and lysosomal-activity detection—validated SA as a potent late-stage autophagic inhibitor by increasing microtubule-associated light chain 3-II (LC3-II) conversion, decreasing acidic vesicular-organelle formation, and inducing lysosomal dysfunction even under conditions of either starvation or hypoxia. Furthermore, the anti-autophagic and anti-metastatic activity of SA was Cav-1-dependent. Specifically, Cav-1 knockdown significantly facilitated SA-mediated inhibition of autophagy and metastasis. Furthermore, hypoxia inducible factor-1α (Hif-1α) overexpression attenuated the SA-induced inhibitory activities on Cav-1, autophagy, and metastasis, indicating that SA may have inhibited autophagy-related metastasis via Hif-1α/Cav-1 signaling. In both mouse breast cancer xenograft and zebrafish xenotransplantation models, SA inhibited breast cancer growth and inhibited late-phase autophagy in vivo, which was accompanied by suppression of Hif-1α/Cav-1 signaling and the epithelial-mesenchymal transition. Overall, our findings not only indicate that SA acts as a novel late-phase autophagic inhibitor with anti-metastatic activities in triple-negative breast cancer, but also highlight Cav-1 as a regulator in controlling late-phase autophagic activity.

MicroRNA, Diabetes Mellitus and Colorectal Cancer

Diabetes mellitus (DM) is an endocrinological disorder that is due to either the pancreas not producing enough insulin, or the body does not respond appropriately to insulin. There are many complications of DM such as retinopathy, nephropathy, and peripheral neuropathy. In addition to these complications, DM was reported to be associated with different cancers. In this review, we discuss the association between DM and colorectal cancer (CRC). CRC is the third most commonly diagnosed cancer worldwide that mostly affects older people, however, its incidence and mortality are rising among young people. We discuss the relationship between DM and CRC based on their common microRNA (miRNA) biomarkers. miRNAs are non-coding RNAs playing important functions in cell differentiation, development, regulation of cell cycle, and apoptosis. miRNAs can inhibit cell proliferation and induce apoptosis in CRC cells. miRNAs also can improve glucose tolerance and insulin sensitivity. Therefore, investigating the common miRNA biomarkers of both DM and CRC can shed a light on how these two diseases are correlated and more understanding of the link between these two diseases can help the prevention of both DM and CRC.

Cross-talk between oxidative stress signaling and microRNA regulatory systems in carcinogenesis: Focused on gastrointestinal cancers

Molecular mechanisms underlying development and progression of gastrointestinal (GI) cancers are mediated by both oxidative stress (OS) and microRNAs (miRNAs) involvement. Notably, OS signaling may regulate the expression of miRNAs, and miRNAs function as imperative players in OS-initiated tumors. Given the defined biological roles of both OS systems and miRNAs in GI carcinogenesis, a possible interplay between these two key cellular networks is considered. A growing body of evidence has indicated a reciprocal connection between OS signaling pathways and miRNA regulatory machines in GI cancer development and progression. Illumination of the molecular cross-talking between miRNAs and the OS would improve our pathophysiological insight into carcinogens. Also, understanding the molecular mechanisms in which these systems are reciprocally regulated may imply in future medical practice mainly GI cancer therapy. Nowadays, therapeutic strategies focusing on miRNA and OS in GI cancer treatment are increasingly delineated. Since the use of antioxidants is limited owing to the contrasting consequences of OS signaling in cancer, the discovery of OS-responsive miRNAs may provide a potential new strategy to overcome OS-mediated GI carcinogenesis. Given the possible interaction between OS and miRNAs in GI cancers, this review aimed to elucidate the existing evidence on the interaction between OS and miRNA regulatory machinery and its role in GI carcinogenesis. In this regard, we will illustrate the function of miRNAs which target OS systems during homeostasis and tumorigenesis. We also discuss the biological cross-talk between OS systems and miRNAs and corresponding cell signaling pathways.

MicroRNAs and Apoptosis in Colorectal Cancer

Colorectal cancer (CRC) is the third leading cause of cancer death in the world, and its incidence is rising in developing countries. Treatment with 5-Fluorouracil (5-FU) is known to improve survival in CRC patients. Most anti-cancer therapies trigger apoptosis induction to eliminate malignant cells. However, de-regulated apoptotic signaling allows cancer cells to escape this signaling, leading to therapeutic resistance. Treatment resistance is a major challenge in the development of effective therapies. The microRNAs (miRNAs) play important roles in CRC treatment resistance and CRC progression and apoptosis. This review discusses the role of miRNAs in contributing to the promotion or inhibition of apoptosis in CRC and the role of miRNAs in modulating treatment resistance in CRC cells.

Downregulation of MicroRNA-551b Correlates With Dissemination of Human Oral Squamous Cell Carcinoma

PURPOSE

Altered expression of microRNAs contributes to invasion and metastasis of many human cancers; however, the importance of microRNAs in head and neck cancers remains to be elucidated. In this study, we examined whether altered microRNA (miR)-551b expression correlated with invasive phenotypes of human oral squamous cell carcinoma (OSCC) in vivo and in vitro.

MATERIALS AND METHODS

Real-time polymerase chain reaction was used to detect the expression level of miR-551b in 71 OSCC tissues with lymph node metastasis and 50 nonmetastatic OSCC tissues. We also constructed miR-551b mimic-transfected cell lines HN4 and HN12. The effects of overexpressing miR-551b on the proliferation, migration, and invasion of OSCC cells were examined using Cell Counting Kit 8 (Dojindo, Kumamoto, Japan), plate clone formation, wound healing, and Transwell invasion experiments (Corning, Corning, NY). The association between clinical pathologic parameters and the expression level of miR-551b was analyzed using Kaplan-Meier survival analysis.

RESULTS

The expression of miR-551b measured 0.33 ± 0.11 in the 71 OSCC tissues with lymph node metastasis versus 0.54 ± 0.06 in the 50 tissues with non-lymph node metastasis (P = .021). Regarding OSCC patients, the expression of miR-551b negatively correlated with patients' overall survival (P = .035). The ectopic expression of miR-551b inhibited the invasion and migration of OSCC cells.

CONCLUSIONS

This is the first report showing that reduced miR-551b expression may be an event leading to OSCC invasion and metastasis.

miR-145 promotes miR-133b expression through c-myc and DNMT3A-mediated methylation in ovarian cancer cells

Ovarian cancer presents as malignant tumors in the female reproductive system with high mortality. MicroRNAs are involved in the progression of ovarian cancer; however, the regulatory relationship among miRs remains unclear. In our study, we verified that both miR-145 and miR-133b messenger RNA (mRNA) levels in ovarian cancer tissues were lower than in normal ovarian tissues, and their mRNA level in serum of patients with ovarian cancer was reduced. We demonstrated miR-145 targeted c-myc, and c-myc interacted physically with DNMT3A in ovarian cancer cells. We confirmed that c-myc recruited DNMT3A to the miR-133b promoter. miR-133b overexpression also inhibited target gene PKM2 expression along with the Warburg effect. Our results indicate that miR-145 inhibited the Warburg effect through miR-133b/PKM2 pathways, which may improve approaches to ovarian cancer diagnosis and treatment.

MicroRNAs as Theranostics Targets in Oral Carcinoma Stem Cells

Oral cancer belongs to head and neck squamous cell carcinoma and has been recognized as one of the most prevalent malignancies worldwide. Recent studies have suggested that cancer stem cells (CSCs) may participate in tumor initiation, metastasis and even recurrence, so the regulation of CSCs has drawn significant attention over the past decade. Among various molecules that are associated with CSCs, non-coding RNAs (ncRNAs) have been indicated as key players in the acquisition and maintenance of cancer stemness. In addition, accumulating studies have shown that the aberrant expression of these ncRNAs may serve as surrogate diagnostic markers or even therapeutic targets for cancer treatment. The current study reviews the previous work by us and others to summarize how these ncRNAs affect oral cancer stemness and their potential theranostic applications. A better understanding of the implication of these ncRNAs in oral tumorigenesis will facilitate the translation of basic ncRNA research into clinical application in the future.

A Novel Tumor Suppressor SPINK5 Serves as an Independent Prognostic Predictor for Patients with Head and Neck Squamous Cell Carcinoma

BACKGROUND

In our previous study, serine protease inhibitor Kazal-type 5 (SPINK5), which encodes the product of serine protease inhibitor lymphoepithelial Kazal-type-related inhibitor (LEKTI) was found to be down-regulated in head and neck squamous cell carcinoma (HNSCC) using oligonucleotide microarrays. However, the function and clinical implications of SPINK5/LEKTI remain obscure in HNSCC.

METHODS

The endogenous expression level of SPINK5/LEKTI was further verified in 9 HNSCC cell lines and HNSCCs by means of reverse transcription-polymerase chain reaction, real-time PCR, Western blotting and immunohistochemistry. The biological function of SPINK5/LEKTI was investigated in vitro and in vivo experiments. Kaplan-Meier survival analysis and Cox proportional hazards regression model were used to determine the correlation between SPINK5/LEKTI expression and clinical outcome.

RESULTS

Down-regulation expression of SPINK5/LEKTI was found in six out of nine HNSCC cell lines and in 85.7% HNSCC specimens (P<0.0001). Upon silencing of SPINK5/LEKTI, the cell proliferation, plate colony formation and cell invasion of WU-HN6 cells were significantly increased, while exogenous overexpression of SPINK5/LEKTI, the proliferation, plate colony and invasion of WU-HN13 and HN30 cells were remarkably inhibited with the arrest of G1 cell cycle (P=0.0001, P=0.003, respectively). HNSCC patients with lower LEKTI levels had significantly inferior overall survival compared to those patients with higher LEKTI (P=0.0017) by Kaplan-Meier survival analysis. Univariate and multivariate Cox proportional hazards regression model analysis revealed that LEKTI expression was an independent prognostic predictor for HNSCC patients (HR=0.114, 95% CI:0.044-0.292, P<0.001).

CONCLUSION

Our results demonstrate that SPINK5/LEKTI might be a tumor suppressor in HNSCCs and serve as an independent prognostic predictor for HNSCC patients.

Association of genetic polymorphisms of miR-145 gene with telomere length in omethoate-exposed workers

Omethoate, an organophosphorous pesticide, causes a variety of health effects, especially the damage of chromosome DNA. The aim of the study was to assess the correlation between polymorphisms of encoding miRNA genes and telomere length in omethoate-exposure workers. 180 workers with more than 8 years omethoate-exposure and 115 healthy controls were recruited in the study. Genotyping for the selected single nucleotide polymorphisms loci were performed using the flight mass spectrometry. Real-time fluorescent quantitative polymerase chain reaction(PCR) method was applied to determine the relative telomere length(RTL) in human peripheral blood leukocytes DNA. After adjusting the covariate of affecting RTL, covariance analysis showed that the female was significantly longer than that of the male in control group(P < 0.046). For the miR-145 rs353291 locus, this study showed that RTL of mutation homozygous AG+GG individuals was longer than that of wild homozygous AA in the exposure group (P = 0.039). In the control group, RTL with wild homozygous TT genotype in miR-30a rs2222722 polymorphism locus was longer than that of the mutation homozygous CC genotype (P = 0.038). After multiple linear regression analysis, the independent variables of entering into the model were omethoate-exposure (b = 0.562, P < 0.001), miR-145 rs353291 (AG+GG) (b = 0.205, P = 0.010). The prolongation of relative telomere length in omethoate exposed workers was associated with AG+GG genotypes in rs353291 polymorphism of encoding miR-145 gene.

MicroRNA-145 inhibits growth of laryngeal squamous cell carcinoma by targeting the PI3K/Akt signaling pathway

Purpose: In this study, we used a nude mouse model of human laryngeal squamous cell carcinoma (LSCC) to investigate inhibition of tumor growth by microRNA-145 (miR-145) and the mechanisms underlying this inhibition. Methods: Tumors were established in nude mice by transplantation of the LSCC AMC-HN-8 cell line. Forty-eight nude mice were randomly divided into groups of eight mice each and treated with high (1.0 optical density [OD]) or low (0.5 OD) doses of miR-145, or relevant control treatments. Tumor growth was observed in each group and used to calculate the inhibition rate. Routine pathological and electron microscopic examinations were used to determine tumor apoptosis and proliferation. Changes in levels of miR-145 and PI3K and Akt protein levels were also analyzed. Results: MiR-145 inhibited LSCC growth in a dose-dependent manner, as tumor growth was significantly inhibited in mice injected intratumorally with high-dose miR-145 compared with both the untreated and low-dose miR-145 groups (p<0.05). Pathological examination showed increased tumor necrotic and apoptotic changes in treated mice, which was confirmed by electron microscopy. PI3K and Akt protein expression were significantly lower in tumors treated with high-dose miR-145 group compared with those in the untreated and low-dose miR-145 groups (p<0.05). Conclusions: MiR-145 was associated with inhibited tumor growth in a nude mouse model of LSCC. The underlying mechanism may be inhibition of the PI3K/Akt signaling pathway, which regulates tumor growth, invasion, and metastasis and also plays an important role in tumor angiogenesis and proliferation of tumor stem cells. MiR-145 may act as a tumor suppressor gene and is a promising candidate for cancer treatment.

miR‑145 suppresses ovarian cancer progression via modulation of cell growth and invasion by targeting CCND2 and E2F3

MicroRNAs (miRNA/miRs) have been demonstrated to be critical post‑transcriptional modulators of gene expression during tumorigenesis. Numerous miRNAs have been revealed to be downregulated in human epithelial ovarian cancer (EOC). In the present study, it was observed that the expression of miR‑145 was decreased in EOC tissues and cell lines. Overexpression of miR‑145 inhibited the proliferation, migration and invasion of EOC cells. The D‑type cyclin 2, cyclin D2 (CCND2), and E2F transcription factor 3 (E2F3) were confirmed to be targets of miR‑145. In addition, restoration of these 2 genes significantly reversed the tumor suppressive effects of miR‑145. Collectively, the results indicated that miR‑145 serves a critical role in suppressing the biological behavior of EOC cells by targeting CCND2 and E2F3. Therefore, miR‑145 was suggested to be a potential miRNA‑based therapeutic target in ovarian cancer.

Function of microRNA-145 and mechanisms underlying its role in malignant tumor diagnosis and treatment

miRNAs are single-stranded small RNAs that do not encode proteins. They can combine complementarily with the 3′-UTRs of target gene mRNA molecules to promote targeted mRNA degradation or inhibit mRNA translation, thereby regulating gene expression at the post-transcriptional level. MiRNAs participate in regulation of cell cycling, growth, apoptosis, differentiation, and stress responses. MiRNA-145 (miR-145) is a tumor suppressor that targets various tumor-specific genes and proteins, thereby influencing related signaling pathways. MiR-145 not only regulates tumor growth, invasion, and metastasis, but is also important for tumor angiogenesis and tumor stem cell proliferation. Here, we review the roles and mechanisms of miR-145 in the diagnosis and treatment of malignant tumors. Published data confirm that miR-145 expression in various tumors is significantly lower than that in normal tissues and that overexpression of miR-145 inhibits the growth of different tumor cells, significantly reduces the ability of tumors to spread, and improves sensitivity to chemotherapeutic drugs. We conclude that miR-145 is a potential marker for use in the early diagnosis and prognostic evaluation of patients with cancer, has a role as a tumor suppressor, and is a promising cancer treatment target candidate.

Network Pharmacology-Based Validation of Caveolin-1 as a Key Mediator of Ai Du Qing Inhibition of Drug Resistance in Breast Cancer

Chinese formulas have been paid increasing attention in cancer multidisciplinary therapy due to their multi-targets and multi-substances property. Here, we aim to investigate the anti-breast cancer and chemosensitizing function of Ai Du Qing (ADQ) formula made up of Hedyotis diffusa, Curcuma zedoaria (Christm.) Rosc., Astragalus membranaceus (Fisch.) Bunge, and Glycyrrhiza uralensis Fisch. Our findings revealed that ADQ significantly inhibited cell proliferation in both parental and chemo-resistant breast cancer cells, but with little cytotoxcity effects on the normal cells. Besides, ADQ was found to facilitate the G2/M arresting and apoptosis induction effects of paclitaxel. Network pharmacology and bioinformatics analysis further demonstrated that ADQ yielded 132 candidate compounds and 297 potential targets, and shared 22 putative targets associating with breast cancer chemoresponse. Enrichment analysis and experimental validation demonstrated that ADQ might improve breast cancer chemosensitivity via inhibiting caveolin-1, which further triggered expression changes of cell cycle-related proteins p21/cyclinB1 and apoptosis-associated proteins PARP1, BAX and Bcl-2. Besides, ADQ enhanced in vivo paclitaxel chemosensitivity on breast cancer. Our study not only uncovers the novel function and mechanisms of ADQ in chemosensitizing breast cancer at least partly via targeting caveolin-1, but also sheds novel light in utilizing network pharmacology in Chinese Medicine research.

Double-negative feedback interaction between DNA methyltransferase 3A and microRNA-145 in the Warburg effect of ovarian cancer cells

Ovarian cancer is the most lethal gynecological malignancy because of its poor prognosis. The Warburg effect is one of the key mechanisms mediating cancer progression. Molecules targeting the Warburg effect are therefore of significant therapeutic value for the treatment of cancers. Many microRNAs (miR) are dysregulated in cancers, and aberrant miR expression patterns have been suggested to correlate with the Warburg effect in cancer cells. In our study, we found that miR-145 negatively correlated with DNA methyltransferase (DNMT)3A expression at cellular/histological levels. miR-145 inhibited the Warburg effect by targeting HK2. Luciferase reporter assays confirmed that miR-145-mediated downregulation of DNMT3A occurred through direct targeting of its mRNA 3'-UTRs, whereas methylation-specific PCR (MSP) assays found that knockdown of DNMT3A increased mRNA level of miR-145 and decreased methylation levels of promoter regions in the miR-145 precursor gene, thus suggesting a crucial crosstalk between miR-145 and DNMT3A by a double-negative feedback loop. DNMT3A promoted the Warburg effect through miR-145. Coimmunoprecipitation assays confirmed no direct binding between DNMT3A and HK2. In conclusion, a feedback loop between miR-145 and DNMT3A is a potent signature for the Warburg effect in ovarian cancer, promising a potential target for improved anticancer treatment.

MiRNA-145 Induces Apoptosis in a Gallbladder Carcinoma Cell Line by Targeting DFF45

Bakcground

We measured expression of miRNA-145 in gallbladder carcinoma and its influence on propagation, invasion, and apoptosis of gallbladder carcinoma cells in vitro.

Methods

miRNA-145 expression was compared between normal gallbladder epithelial cells and GBS-SD (gallbladder series) cells using miRNA chip technology. Propagation, apoptosis, and invasion properties of each cell group were tested using MTT, a clone-formation assay, flow cytometry, Western blot, and Transwell assays.

Results

Expression of miRNA-145 was observed to be down-regulated and GBC-SD cell clones transiently transfected with hsa-miRNA-145 were substantially reduced compared with controls (p<0.01). We observed that GBC-SD cells transfected with hsa-miRNA-145 and double-positive (Annexin V and PI) for apoptosis were more numerous than controls. Moreover, GBC-SD cells over-expressing miRNA-145 had significantly greater expression of apoptosis-related protein, caspase-3. A Transwell assay confirmed that GBC-SD cells over-expressing miRNA-145 that migrated to the lower chamber were fewer compared with controls. Post-transcriptional regulation of gene expression was measured using dualluciferase reporter assays and data show that miRNA-145 facilitates the inhibition of GBC-SD cell growth and invasion while inducing apoptosis by targeting DFF45.

Conclusion

Thus, we speculate that miRNA-145 facilitates inhibition of GBC-SD cell growth and invasion while inducing apoptosis by targeting DFF45; however, miRNA-145 does not directly affect the GBC-SD cell cycle.

Epigenetically regulated miR-145 suppresses colon cancer invasion and metastasis by targeting LASP1

MiR-145 is a tumor-suppressive microRNA that participates in the malignant progression of colorectal cancer (CRC). Although miR-145 has been reported to inhibit proliferation and to induce apoptosis of CRC cells, the reports about its role in invasion and metastasis are controversial. The regulation of miR-145 its own expression also requires further elucidation. In this study, we firstly found that miR-145 is markedly downregulated in the metastatic tumors of CRC patients. Then through gain- and loss-of function studies, we demonstrated that miR-145 suppresses the invasion and metastasis of CRC cells. We also provided experimental evidences which include direct binding assays and verifications on tissue specimens to confirm that LIM and SH3 protein 1 (LASP1) is a direct target of miR-145. Furthermore, we identified the core promoter regions of miR-145 and observed the cooperation between histone methylation and transcription factors through binding to these core promoter regions to regulate the expression of miR-145 in CRC cells. Our study provides an insight into the regulatory network in CRC cells, thus offering new targets for treating CRC patients.

Convergence of miR-143 overexpression, oxidative stress and cell death in HCT116 human colon cancer cells

MicroRNAs (miRNAs) regulate a wide variety of biological processes, including tumourigenesis. Altered miRNA expression is associated with deregulation of signalling pathways, which in turn cause abnormal cell growth and de-differentiation, contributing to cancer. miR-143 and miR-145 are anti-tumourigenic and influence the sensitivity of tumour cells to chemotherapy and targeted therapy. Comparative proteomic analysis was performed in HCT116 human colon cancer cells stably transduced with miR-143 or miR-145. Immunoblotting analysis validated the proteomic data in stable and transient miRNA overexpression conditions in human colon cancer cells. We show that approximately 100 proteins are differentially expressed in HCT116 human colon cancer cells stably transduced with miR-143 or miR-145 compared to Empty control cells. Further, Gene Ontology and pathway enrichment analysis indicated that proteins involved in specific cell signalling pathways such as cell death, response to oxidative stress, and protein folding might be modulated by these miRNAs. In particular, antioxidant enzyme superoxide dismutase 1 (SOD1) was downregulated by stable expression of either miR-143 or miR-145. Further, SOD1 gain-of-function experiments rescued cells from miR-143-induced oxidative stress. Moreover, miR-143 overexpression increased oxaliplatin-induced apoptosis associated with reactive oxygen species generation, which was abrogated by genetic and pharmacological inhibition of oxidative stress. Overall, miR-143 might circumvent resistance of colon cancer cells to oxaliplatin via increased oxidative stress in HCT116 human colon cancer cells.

Evaluation of miRNA-196a2 and apoptosis-related target genes: ANXA1, DFFA and PDCD4 expression in gastrointestinal cancer patients: A pilot study

Previous reports have suggested the significant association of miRNAs aberrant expression with tumor initiation, progression and metastasis in cancer, including gastrointestinal (GI) cancers. The current preliminary study aimed to evaluate the relative expression levels of miR-196a2 and three of its selected apoptosis-related targets; ANXA1, DFFA and PDCD4 in a sample of GI cancer patients. Quantitative real-time PCR for miR-196a2 and its selected mRNA targets, as well as immunohistochemical assay for annexin A1 protein expression were detected in 58 tissues with different GI cancer samples. In addition, correlation with the clinicopathological features and in silico network analysis of the selected molecular markers were analyzed. Stratified analyses by cancer site revealed elevated levels of miR-196a2 and low expression of the selected target genes. Annexin protein expression was positively correlated with its gene expression profile. In colorectal cancer, miR-196a over-expression was negatively correlated with annexin A1 protein expression (r = -0.738, p < 0.001), and both were indicators of unfavorable prognosis in terms of poor differentiation, larger tumor size, and advanced clinical stage. Taken together, aberrant expression of miR-196a2 and the selected apoptosis-related biomarkers might be involved in GI cancer development and progression and could have potential diagnostic and prognostic roles in these types of cancer; particularly colorectal cancer, provided the results experimentally validated and confirmed in larger multi-center studies.

"Stealth dissemination" of macrophage-tumor cell fusions cultured from blood of patients with pancreatic ductal adenocarcinoma

Here we describe isolation and characterization of macrophage-tumor cell fusions (MTFs) from the blood of pancreatic ductal adenocarcinoma (PDAC) patients. The MTFs were generally aneuploidy, and immunophenotypic characterizations showed that the MTFs express markers characteristic of PDAC and stem cells, as well as M2-polarized macrophages. Single cell RNASeq analyses showed that the MTFs express many transcripts implicated in cancer progression, LINE1 retrotransposons, and very high levels of several long non-coding transcripts involved in metastasis (such as MALAT1). When cultured MTFs were transplanted orthotopically into mouse pancreas, they grew as obvious well-differentiated islands of cells, but they also disseminated widely throughout multiple tissues in "stealth" fashion. They were found distributed throughout multiple organs at 4, 8, or 12 weeks after transplantation (including liver, spleen, lung), occurring as single cells or small groups of cells, without formation of obvious tumors or any apparent progression over the 4 to 12 week period. We suggest that MTFs form continually during PDAC development, and that they disseminate early in cancer progression, forming "niches" at distant sites for subsequent colonization by metastasis-initiating cells.

MicroRNA-34a: A Key Regulator in the Hallmarks of Renal Cell Carcinoma

Renal cell carcinoma (RCC) incidence has increased over the past two decades. Recent studies reported microRNAs as promising biomarkers for early cancer detection, accurate prognosis, and molecular targets for future treatment. This study aimed to evaluate the expression levels of miR-34a and 11 of its bioinformatically selected target genes and proteins to test their potential dysregulation in RCC. Quantitative real-time PCR for miR-34a and its targets; MET oncogene; gene-regulating apoptosis (TP53INP2 and DFFA); cell proliferation (E2F3); and cell differentiation (SOX2 and TGFB3) as well as immunohistochemical assay for VEGFA, TP53, Bcl2, TGFB1, and Ki67 protein expression have been performed in 85 FFPE RCC tumor specimens. Clinicopathological parameter correlation and in silico network analysis have also implicated. We found RCC tissues displayed significantly higher miR-34a expression level than their corresponding noncancerous tissues, particularly in chromophobic subtype. MET and E2F3 were significantly upregulated, while TP53INP2 and SOX2 were downregulated. ROC analysis showed high diagnostic performance of miR-34a (AUC = 0.854), MET (AUC = 0.765), and E2F3 (AUC = 0.761). The advanced pathological grade was associated with strong TGFB1, VEGFA, and Ki67 protein expression and absent Tp53 staining. These findings indicate miR-34a along with its putative target genes could play a role in RCC tumorigenesis and progression.

Potential roles of microRNAs and ROS in colorectal cancer: diagnostic biomarkers and therapeutic targets

As one of the most commonly diagnosed cancers worldwide, colorectal adenocarcinoma often occurs sporadically in individuals aged 50 or above and there is an increase among younger patients under 50. Routine screenings are recommended for this age group to improve early detection. The multifactorial etiology of colorectal cancer consists of both genetic and epigenetic factors. Recently, studies have shown that the development and progression of colorectal cancer can be attributed to aberrant expression of microRNA. Reactive oxygen species (ROS) that play a key role in cancer cell survival, can also lead to carcinogenesis and cancer exacerbations. Given the rapid accumulating knowledge in the field, an updated review regarding microRNA and ROS in colorectal cancer is necessary. An extensive literature search has been conducted in PubMed/Medline databases to review the roles of microRNAs and ROS in colorectal cancer. Unique microRNA expression in tumor tissue, peripheral blood, and fecal samples from patients with colorectal cancer is outlined. Therapeutic approaches focusing on microRNA and ROS in colorectal cancer treatment is also delineated. This review aims to summarize the newest knowledge on the pathogenesis of colorectal cancer in the hopes of discovering novel diagnostic biomarkers and therapeutic techniques.

20(S)-Rg3 blocked epithelial-mesenchymal transition through DNMT3A/miR-145/FSCN1 in ovarian cancer

Epithelial-mesenchymal transition (EMT) is one of the key mechanisms mediating cancer progression. MicroRNAs (miRs) are essential regulators of gene expression by suppressing translation or causing degradation of target mRNA. Growing evidence illustrates the crucial roles of miRs dysregulation in cancer development and progression. Here, we have found for the first time that the ginsenoside 20(S)-Rg3, a pharmacologically active component of Panax ginseng, potently increases miR-145 expression by downregulating methyltransferase DNMT3A to attenuate the hypermethylation of the promoter region in the miR-145 precursor gene. Restoration of DNMT3A reverses the inhibitory effect of 20(S)-Rg3 on EMT. FSCN1 is verified as the target of miR-145 to suppress EMT in human ovarian cancer cells. The results from nude mouse xenograft models further demonstrate the suppressive effect of miR-145 on malignant progression of ovarian cancer. Taken together, our results show that 20(S)-Rg3 blocks EMT by targeting DNMT3A/miR-145/FSCN1 pathway in ovarian cancer cells, highlighting the potentiality of 20(S)-Rg3 to be used as a therapeutic agent for ovarian cancer.

Non-coding RNA/microRNA-modulatory dietary factors and natural products for improved cancer therapy and prevention: Alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins

Non-coding small RNA molecules, the microRNAs (miRNAs), contribute decisively to the epigenetic regulation processes in cancer cells. Problematic pathogenic properties of cancer cells and the response of cancers towards anticancer drugs are highly influenced by miRNAs. Both increased drug activity and formation of tumor resistance are regulated by miRNAs. Further to this, the survival and proliferation of cancer cells and the formation of metastases is based on the modulated expression of certain miRNAs. In particular, drug-resistant cancer stem-like cells (CSCs) depend on the presence and absence of specific miRNAs. Fortunately, several small molecule natural compounds were discovered that target miRNAs involved in the modulation of tumor aggressiveness and drug resistance. This review gives an overview of the effects of a selection of naturally occurring small molecules (alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins) on miRNAs that are closely tangled with cancer diseases.

Circulating miRNAs as biomarkers for endocrine disorders

Specific, sensitive and non-invasive biomarkers are always needed in endocrine disorders. miRNAs are short, non-coding RNA molecules with well-known role in gene expression regulation. They are frequently dysregulated in metabolic and endocrine diseases. Recently it has been shown that they are secreted into biofluids by nearly all kind of cell types. As they can be taken up by other cells they may have a role in a new kind of paracrine, cell-to-cell communication. Circulating miRNAs are protected by RNA-binding proteins or microvesicles hence they can be attractive candidates as diagnostic or prognostic biomarkers. In this review, we summarize the characteristics of extracellular miRNA's and our knowledge about their origin and potential roles in endocrine and metabolic diseases. Discussions about the technical challenges occurring during identification and measurement of extracellular miRNAs and future perspectives about their roles are also highlighted.

Implications of miR cluster 143/145 as universal anti-oncomiRs and their dysregulation during tumorigenesis

Tumorigenesis is a multistep process, de-regulated due to the imbalance of oncogenes as well as anti-oncogenes, resulting in disruption of tissue homeostasis. In many cases the effect of oncogenes and anti-oncogenes are mediated by various other molecules such as microRNAs. microRNAs are small non-coding RNAs established to post-transcriptionally regulate more than half of the protein coding genes. miR cluster 143/145 is one such cancer-related microRNA cluster which is down-regulated in most of the cancers and is able to hinder tumorigenesis by targeting tumor-associated genes. The fact that they could sensitize drug-resistant cancer cells by targeting multidrug resistant genes makes them potent tools to target cancer cells. Their low levels precede events which lead to cancer progression and therefore could be considered also as biomarkers to stage the disease. Interestingly, evidence suggests the existence of several in vivo mechanisms by which this cluster is differentially regulated at the molecular level to keep their levels low in cancer. In this review, we summarize the roles of miR cluster 143/145 in cancer, their potential prognostic applications and also their regulation during tumorigenesis.

Dysregulated miR-645 affects the proliferation and invasion of head and neck cancer cell

BACKGROUND AND PURPOSE

Dysregulated miRNAs play an important role in many malignant tumors. However, elucidating the roles of miRNAs in cancer biology, especially in epithelial cancers, remains an ongoing process. In this study, we identified the differentially expressed miR-645 in the progressing of head and neck squamous cell carcinoma (HNSCC) and investigated its biological function.

METHODS

The association between clinicopathological parameters and the expression levels of the candidated miRNAs were analyzed by using the Kaplan-Meier survival analysis. The cell growth, invasion and migration potential, and clone formation were observed to detect the functions of the miRNAs in HNSCC cells.

RESULTS

In the 34 HNSCC tissues with lymph node metastasis, the expression level of miR-645 was 0.54 ± 0.12, and the expression level was 0.22 ± 0.05 in the 28 tissues with non lymph node metastasis (p = 0.017). In patients with HNSCC, higher level of miR-645 expression significantly correlates with worse overall survival (p = 0.04). Ectopic expression of miR-645 promoted cell invasion and migration.

CONCLUSIONS

miR-645 play a key role in cell invasion and metastasis and their expression correlates with overall survival in the patients with HNSCC.

Hybrid-polymerase chain reaction to identify novel target genes of miR-134 in paclitaxel resistant human ovarian carcinoma cells

Increasing evidence has shown that miR-134 is involved in the promotion of tumorigenesis and chemoresistance. However, whether miR-134 participates in ovarian cancer chemoresistance and its functional targets still remains unclear. The objective of this study was to apply hybrid-polymerase chain reaction (PCR) to screen target genes of miR-134 in ovarian carcinoma paclitaxel resistant SKOV3-TR30 cells, and to provide a number of novel targets of miR-134 for further study of ovarian cancer paclitaxel resistance. The current study found that miR-134 was decreased in SKOV3-TR30 cells compared with the parental SKOV3 cell line. By applying hybrid-PCR, 8 putative target genes of miR-134 in SKOV3-TR30 cells were identified, including C16orf72, PNAS-105, SRM, VIM, F-box protein 2, GAPDH, PRPF6 and RPL41. Notably, the target sites of VIM and PRPF6 were not located in 3'untranslated region, but rather in the coding sequence region. By conducting a luciferase reporter assay, miR-134 was demonstrated to recognize the putative binding sites of these target genes including VIM and PRPF6. Transfecting SKOV3-TR30 cells with miR-134 mimic and performing reverse transcription-PCR in addition to western blot analysis confirmed that miR-134 regulates vimentin expression at a post transcriptional level. This finding provides a novel perspective for studying the mechanism of miR-134/mRNA interaction. In conclusion, this study was the first to apply an effective method of hybrid-PCR to screen putative target mRNAs of miR-134 in paclitaxel resistant SKOV3-TR30 cells and indicate that miR-134 may contribute to the induction of SKOV3-TR30 paclitaxel resistance by targeting these genes.

Salivary microRNAs in oral cancer

OBJECTIVE

This study investigated the use of three salivary microRNAs (miRNA-21, miRNA-184, and miRNA-145) as possible markers for malignant transformation in oral mucosal lesions.

MATERIALS AND METHODS

Salivary whole unstimulated samples were collected from a study group of 100 subjects, consisting of 20 clinically healthy controls, 40 patients with oral potentially malignant disorders (PMDs) [20 with dysplastic lesions and 20 without dysplasia], 20 with biopsy-confirmed oral squamous cell carcinoma (OSCC), and 20 with recurrent aphthous stomatitis (RAS) as disease controls. Total RNA was isolated and purified from saliva samples using the microRNA Isolation Kit (Qiagen, UL). miRNA expression analysis was performed using qRT-PCR (Applied Biosystems).

RESULTS

There was a highly significant increase in salivary miRNA-21 and miRNA-184 in OSCC and PMD (with and without dysplasia) when compared to healthy and disease controls (P < 0.001). Conversely, miRNA-145 levels showed a highly significant decrease in OSCC and PMD overall (P < 0.001). RAS cases showed no significant difference from normal controls in any measured miRNA (P > 0.05). The only microRNA to discriminate between OSCC and PMD with dysplasia was miRNA-184. When receiver operating characteristic curves were designed for the three miRNAs, cutoff points delineating the occurrence of malignant change were a fourfold increase in miRNA-21 with specificity 65% and sensitivity 65%, a 0.6 decrease in miRNA-145, with specificity 70% and sensitivity 60%, and a threefold increase of miRNA-184, with specificity 75% and sensitivity 80%. Calculating the area under the curve revealed that miRNA-184 was the only one among the studied miRNAs that provided good diagnostic value.

CONCLUSION

Salivary determination of the miRNAs tested might furnish a noninvasive, rapid adjunctive aid for revealing malignant transformation in oral mucosal lesions, particularly miRNA-184.

MiR-145 inhibits metastasis by targeting fascin actin-bundling protein 1 in nasopharyngeal carcinoma

Background

Based on our recent microarray analysis, we found that miR-145 was obviously downregulated in nasopharyngeal carcinoma (NPC) tissues. However, little is known about its function and mechanism involving in NPC development and progression.

Methods

Quantitative RT-PCR was used to detect miR-145 expression in NPC cell lines and clinical samples. Wound healing, Transwell migration and invasion, three-dimension spheroid invasion assays, and lung metastasis model were performed to test the migratory, invasive, and metastatic ability of NPC cells. Luciferase reporter assay, quantitative RT-PCR, and Western blotting were used to verify the target of miR-145.

Results

MiR-145 was obviously decreased in NPC cell lines and clinical samples (P<0.01). Ectopic overexpression of miR-145 significantly inhibited the migratory and invasive ability of SUNE-1 and CNE-2 cells. In addition, stably overexpressing of miR-145 in SUNE-1 cells could remarkably restrain the formation of metastatic nodes in the lungs of mice. Furthermore, fascin actin-bundling protein 1 (FSCN1) was verified as a target of miR-145, and silencing FSCN1 with small RNA interfering RNA could suppress NPC cell migration and invasion.

Conclusions

Our findings demonstrated that miR-145 function as a tumor suppressor in NPC development and progression via targeting FSCN1, which could sever as a potential novel therapeutic target for patients with NPC.

Concurrent Targeting of KRAS and AKT by MiR-4689 Is a Novel Treatment Against Mutant KRAS Colorectal Cancer

KRAS mutations are a major cause of drug resistance to molecular-targeted therapies. Aberrant epidermal growth factor receptor (EGFR) signaling may cause dysregulation of microRNA (miRNA) and gene regulatory networks, which leads to cancer initiation and progression. To address the functional relevance of miRNAs in mutant KRAS cancers, we transfected exogenous KRAS(G12V) into human embryonic kidney 293 and MRC5 cells with wild-type KRAS and BRAF genes, and we comprehensively profiled the dysregulated miRNAs. The result showed that mature miRNA oligonucleotide (miR)-4689, one of the significantly down-regulated miRNAs in KRAS(G12V) overexpressed cells, was found to exhibit a potent growth-inhibitory and proapoptotic effect both in vitro and in vivo. miR-4689 expression was significantly down-regulated in cancer tissues compared to normal mucosa, and it was particularly decreased in mutant KRAS CRC tissues. miR-4689 directly targets v-ki-ras2 kirsten rat sarcoma viral oncogene homolog (KRAS) and v-akt murine thymoma viral oncogene homolog 1(AKT1), key components of two major branches in EGFR pathway, suggesting KRAS overdrives this signaling pathway through inhibition of miR-4689. Overall, this study provided additional evidence that mutant KRAS functions as a broad regulator of the EGFR signaling cascade by inhibiting miR-4689, which negatively regulates both RAS/mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT pathways. These activities indicated that miR-4689 may be a promising therapeutic agent in mutant KRAS CRC.

Technical Aspects Related to the Analysis of Circulating microRNAs

Specific and sensitive noninvasive biofluid-based biomarkers are always needed in the laboratory diagnosis of diseases. Biomarkers are applied not only for diagnostic purposes but for stratifying a disease and for assessing the therapy response or disease progression. MicroRNAs (miRNAs) are short noncoding RNA molecules regulating gene expression posttranscriptionally. They are frequently dysregulated in many physiological and pathophysiological conditions. miRNAs are present in the circulation and in other biofluids that are common matrices for clinical laboratory testing that has raised the possibility that miRNAs may serve as novel biomarkers. Their excellent stability also supports the possibility that miRNAs once will be routinely used biomarkers in clinical practice. From an analytical point of view, there are many factors (starting material, sample storage and processing, different RNA extraction and detection methods, intra- and interassay variability, and assay interferences) to consider if a miRNA as biomarker is aimed to be introduced as a clinical laboratory test. Despite several pre-analytical and analytical factors that still need standardization, a significant number of studies have been published about the potential role of circulating miRNAs as biomarkers. Due to the lack of standardization of methods, there are a lot of discrepancies among results. In this chapter, we aimed to summarize the current findings about circulating miRNAs focusing on the analytical points related to miRNAs measurements from biofluids.

MicroRNAs as biomarkers in pituitary tumors

The use of extracellular microRNAs (miRNAs) as circulating biomarkers is currently leading to relevant advances in the diagnosis and assessment of prognosis of several diseases. Specific miRNAs have also been shown to play a role in the pathophysiology of many neoplastic and non-neoplastic diseases. A number of studies have demonstrated that miRNAs show differential expression in various tumors, such as in the prostate, ovary, lung, breast, brain, and pituitary. Recent findings have built connections between miRNAs that are deregulated within the tumor and their presence in peripheral blood. MiRNAs have been shown to be stable in the blood where they are present in either free and/or uncomplexed form, as well as packed in microvesicles, exosomes, and apoptotic bodies, or bound to different proteins. Because the pituitary is a highly vascularized organ that releases hormones into the circulation, miRNAs would be useful biomarkers for the diagnosis of pituitary tumors, as well as for predicting or detecting recurrence after surgery. Here we review the biological significance of miRNAs in pituitary tumors and the potential value of circulating miRNAs as biomarkers.

MicroRNA-145: a potent tumour suppressor that regulates multiple cellular pathways

MicroRNAs are endogenous, small (18-25 nucleotides) non-coding RNAs, which regulate genes expression by directly binding to the 3'-untranslated regions of the target messenger RNAs. Emerging evidence shows that alteration of microRNAs is involved in cancer development. MicroRNA-145 is commonly down-regulated in many types of cancer, regulating various cellular processes, such as the cell cycle, proliferation, apoptosis and invasion, by targeting multiple oncogenes. This review aims to summarize the recent published literature on the role of microRNA-145 in regulating tumourigenesis and progression, and explore its potential for cancer diagnosis, prognosis and treatment.

miR-145 sensitizes ovarian cancer cells to paclitaxel by targeting Sp1 and Cdk6

Multidrug resistance (MDR) remains a major obstacle to effective chemotherapy treatment in ovarian cancer. In our study, paclitaxel-resistant ovarian cancer patients and cell lines had decreased miR-145 levels and expressed high levels of Sp1 and Cdk6. Introducing miR-145 into SKOV3/PTX and A2780/PTX cells led to a reduction in Cdk6 and Sp1 along with downregulation of P-gp and pRb. These changes resulted in increased accumulation of antineoplastic drugs and G1 cell cycle arrest, which rendered the cells more sensitive to paclitaxel in vitro and in vivo. These effects could be reversed by reintroducing Sp1 or Cdk6 into cells expressing high levels of miR-145, resulting in restoration of P-gp and pRb levels. Furthermore, we confirmed that both Cdk6 and Sp1 are targets of miR-145. Intriguingly, demethylation with 5-aza-dC led to reactivation of miR-145 expression in drug-resistant ovarian cancer cell lines, which also resulted in increased sensitivity to paclitaxel. Collectively, these findings begin to elucidate the role of miR-145 as an important regulator of chemoresistance in ovarian cancer by controlling both Cdk6 and Sp1.

miR-639 promotes the proliferation and invasion of breast cancer cell in vitro

Breast cancer is characterised by an elevated capacity for tumour invasion and lymph node metastasis, but the cause remains to be determined. Recent studies suggest that microRNAs can regulate the evolution of malignant behaviours by regulating multiple target genes. In this study, we have first confirmed that miR-639 is up-regulated in metastatic breast cancer tissues and cell line with highly invasive capacity. Furthermore, we provided evidence to demonstrate that up-regulation of miR-639 contributes breast cancer invasion and metastasis. These data reveal a key role of miR-639 in breast cancer metastasis and support biological and clinical links between miR-639 and breast cancer.

Peroxisome proliferator-activated receptor γ-mediated induction of microRNA-145 opposes tumor phenotype in colorectal cancer

MicroRNAs (miRNAs) regulate diverse biological processes by inhibiting translation or inducing degradation of target mRNAs. miR-145 is a candidate tumor suppressor in colorectal carcinoma (CRC). Colorectal carcinogenesis involves deregulation of cellular processes controlled by a number of intertwined chief transcription factors, such as PPARγ and SOX9. Since PPAR family members are able to modulate complex miRNAs networks, we hypothesized a role of miRNA-145 in the interaction between PPARγ and SOX9 in colorectal carcinogenesis. To address this issue, we evaluated gene expression in tissue specimens of CRC patients and we took advantage of invitro models represented by CRC derived cell lines (CaCo2, SW480, HCT116, and HT-29), employing PPARγ activation and/or miRNA-145 ectopic overexpression to analyze how their interplay impact the expression of SOX9 and the development of a malignant phenotype.

RESULTS

PPARγ regulates the expression of miR-145 by directly binding to a PPAR response element (PPRE) in its promoter at -1207/-1194bp from the transcription start site. The binding is essential for miR-145 upregulation by PPARγ upon rosiglitazone treatment. Ectopic expression of miR-145, in turn, regulates SOX9 expression through the binding to specific seed motifs. The PPARγ-miR-145-SOX9 axis overarches cell cycle progression, invasiveness and differentiation of CRC derived cell lines. Together, these results suggest that miR-145 is a novel target of PPARγ, acts as a tumor suppressor in CRC cell lines and is a key regulator of intestinal cell differentiation by directly targeting SOX9, a marker of undifferentiated progenitors in the colonic crypts.

NF-kappaB-dependent microRNA-425 upregulation promotes gastric cancer cell growth by targeting PTEN upon IL-1β induction

Overexpression of the proinflammatory cytokine IL-1β is associated with diverse diseases, including cancer. Alteration of microRNAs has been observed in cancer cells exposed to proinflammatory cytokines, yet their function in inflammation stress remains elusive. Here, we show that IL-1β induces the upregulation of miR-425, which negatively regulates phosphatase and tensin homolog expression by targeting its 3’ UTR. An increase in miR-425 depends on IL-1β-induced NF-kappaB activation, which enhances miR-425 gene transcription upon IL-1β induction. Consequently, repression of phosphatase and tensin homolog by miR-425 promotes gastric cancer cell proliferation, which is required to protect cells from cisplatin-induced apoptosis. Taken together, our data support a critical role for NF-kappaB-dependent upregulation of miR-425, which represents a new pathway for the repression of phosphatase and tensin homolog activation and the promotion of cell survival upon IL-1β induction.

Protumorigenic effects of mir-145 loss in malignant pleural mesothelioma

We identified a discrete number of microRNAs differentially expressed in benign or malignant mesothelial tissues. We focused on mir-145 whose levels were significantly downregulated in malignant mesothelial tissues and malignant pleural mesothelioma (MPM) cell lines as compared to benign tissues (pleura, peritoneum or cysts). We show that promoter hyper-methylation caused very low levels in MPM cell lines and specimens. Treatment of MPM cell lines with mir-145 agonists negatively modulated some protumorigenic properties of MPM cells, such as clonogenicity, cell migration and resistance to pemetrexed treatment. The main effector mechanism of the clonogenic death induced by mir-145 was that of accelerated senescence. We found that mir-145 targeted OCT4 via specific binding to its 3'-UTR. Increased intracellular levels of mir-145 decreased the levels of OCT4 and its target gene ZEB1, thereby counteracting the increase of OCT4 induced by pemetrexed treatment which is known to favor the development of chemoresistant cells. In line with this, reintroduction of OCT4 into mimic-145 treated cells counteracted the effects on clonogenicity and replicative senescence. This further supports the relevance of the mir-145-OCT4 interaction for the survival of MPM cells. The potential use of mir-145 expression levels to classify benign vs malignant mesothelial tissues and the differences between pemetrexed-induced senescence and that induced by the re-expression of mir-145 are discussed.

The proto-oncogene TWIST1 is regulated by microRNAs

Upregulation of the proto-oncogene Twist1 is highly correlated with acquired drug resistance and poor prognosis in human cancers. Altered expression of this multifunctional transcription factor is also associated with inherited skeletal malformations. The mammalian Twist1 3′UTRs are highly conserved and contain a number of potential regulatory elements including miRNA target sites. We analyzed the translational regulation of TWIST1 using luciferase reporter assays in a variety of cell lines. Among several miRNAs tested, miR-145a-5p, miR-151-5p and a combination of miR-145a-5p + miR-151-5p and miR-151-5p + miR-337-3p were able to significantly repress Twist1 translation. This phenomena was confirmed with both exogenous and endogenous miRNAs and was dependent on the presence of the predicted target sites in the 3′UTR. Furthermore, the repression was sensitive to LNA-modified miRNA antagonists and resulted in decreased migratory potential of murine embryonic fibroblast cells. Understanding the in vivo mechanisms of this oncogene's regulation might open up a possibility for therapeutic interference by gene specific cancer therapies.

The loss of the tumour-suppressor miR-145 results in the shorter disease-free survival of prostate cancer patients

BACKGROUND

Prostate cancer (PCa) is characterised by great heterogeneity of the disease progression rate. Tumours range from insignificant and not life threatening to high risk for relapse ones. Consequently, a large number of patients undergo unnecessary treatment. miR-145 is a well-documented tumour suppressor and its expression, which is regulated by the p53 pathway, has been found to be decreased in the majority of human malignancies. The aim of our study was to evaluate the clinical utility of miR-145 for the prognostication of PCa.

METHODS

Total RNA was isolated from 137 prostate tissue specimens obtained from 73 radical prostatectomy-treated PCa patients and 64 transurethral- or open prostatectomy-treated benign prostate hyperplasia (BPH) patients. Following polyadenylation and reverse transcription, miR-145 levels were determined by quantitative real-time PCR assay, using SNORD48 (RNU48) for normalisation purposes.

RESULTS

Downregulated miR-145 expression was found in PCa compared with BPH patients. The reduction of miR-145 expression in PCa was correlated with higher Gleason score, advanced clinical stage, larger tumour diameter and higher prostate-specific antigen (PSA) and follow-up PSA levels. In addition, higher risk for biochemical recurrence and significantly shorter disease-free survival (DFS) was found for the PCa patients expressing lower miR-145. Focusing on 'low- and intermediate-recurrence risk' PCa patients, miR-145 loss was revealed to be a reliable predictor of biochemical relapse and poor DFS independent from Gleason score, clinical stage, PSA and patients' age.

CONCLUSION

The loss of the tumour-suppressor miR-145 increases the risk for disease progression and predicts the poor survival of PCa patients.

Dysregulated miR-363 affects head and neck cancer invasion and metastasis by targeting podoplanin

Head and neck squamous cell carcinoma (HNSCC) is characterised by an elevated capacity for tumour invasion and lymph node metastasis and the cause remains to be determined. Recent studies suggest that microRNAs can regulate the evolution of malignant behaviours by regulating multiple target genes. In this study, we have first confirmed that miR-363 is down-regulated in HNSCC tissues with lymph node metastasis and cell lines with highly invasive capacity. We used bioinformatics, cellular and molecular methods to predict and prove that miR-363 directly targeted to podoplanin (PDPN) and caused up-regulation of PDPN in HNSCC. MSP assay showed that DNA promoter methylation was involved in silencing the miR-363 in HNSCC. Furthermore, we provided evidence to demonstrate that PDPN dysregulation caused by down-regulation of miR-363 contributes to HNSCC invasion and metastasis. These data reveal a key role of miR-363-PDPN in HNSCC metastasis and support biological and clinical links between miR-363-PDPN and HNSCC.