The role of microRNA-34 family in Alzheimer's disease: A potential molecular link between neurodegeneration and metabolic disorders

Growing evidence indicates that overexpression of the microRNA-34 (miR-34) family in the brain may play a crucial role in Alzheimer's disease (AD) pathogenesis by targeting and downregulating genes associated with neuronal survival, synapse formation and plasticity, Aβ clearance, mitochondrial function, antioxidant defense system, and energy metabolism. Additionally, elevated levels of the miR-34 family in the liver and pancreas promote the development of metabolic syndromes (MetS), such as diabetes and obesity. Importantly, MetS represent a well-documented risk factor for sporadic AD. This review focuses on the recent findings regarding the role of the miR-34 family in the pathogenesis of AD and MetS, and proposes miR-34 as a potential molecular link between both disorders. A comprehensive understanding of the functional roles of miR-34 family in the molecular and cellular pathogenesis of AD brains may lead to the discovery of a breakthrough treatment strategy for this disease.

Role of microRNAs in the anticancer effects of the flavonoid luteolin: a systematic review

Flavonoids, a broad class of polyphenolic compounds, can potentially have several therapeutic properties in human diseases, including protective effects against oxidative stress, inflammation, cardiovascular disease, diabetes, neurodegenerative disorders, and cancers. Luteolin as a member of flavonoids has been found to exhibit several anticancer properties mainly through cell apoptosis induction, inhibition of invasion, cell proliferation, network formation, and migration. Recent studies have revealed that phytochemicals such as luteolin may exert therapeutic properties through microRNAs (miRNAs or miRs), which have been emerged as important molecules in cancer biology in recent years. miRNAs, as a class of noncoding RNAs, have several important roles in cancer progression or regression. In this review, we aimed to summarize and discuss the role of miRNAs in the luteolin effects on different cancers. This review can be in line with the studies, which have shown that miRNAs may be potential therapeutic targets in cancer treatment.

The Role of Non-Coding RNAs in Controlling Cell Cycle Related Proteins in Cancer Cells

Cell cycle is regulated by a number of proteins namely cyclin-dependent kinases (CDKs) and their associated cyclins which bind with and activate CDKs in a phase specific manner. Additionally, several transcription factors (TFs) such as E2F and p53 and numerous signaling pathways regulate cell cycle progression. Recent studies have accentuated the role of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in the regulation of cell cycle. Both lncRNAs and miRNAs interact with TFs participating in the regulation of cell cycle transition. Dysregulation of cell cycle regulatory miRNAs and lncRNAs results in human disorders particularly cancers. Understanding the role of lncRNAs, miRNAs, and TFs in the regulation of cell cycle would pave the way for design of anticancer therapies which intervene with the cell cycle progression. In the current review, we describe the role of lncRNAs and miRNAs in the regulation of cell cycle and their association with human malignancies.

The role of noncoding RNAs and sirtuins in cancer drug resistance

Cancer is a rising and major health issue around the world. The acquisition of resistance to chemotherapeutic drugs is a great obstacle for the effective treatment of nearly all cancers. Drug resistance is regulated by multiple factors and mechanisms including genetic mutations, abnormal expression of some cellular transporters such as multidrug resistance (MDR) transporters, changes in apoptotic pathways, cancer stem cells, tumor microenvironment, and noncoding RNAs (ncRNAs). Evidence clearly indicates a key role for sirtuins in several characteristics of cancer drug resistance. Recent studies demonstrated the crucial impact of some ncRNAs on sirtuins expression leading to modulation of chemotherapy resistance in cancers. In this review, we will focus on the current findings about the impacts of ncRNAs on the sirtuins pathway and their role in drug resistance of cancer.

MiR-203a-3p targets PTEN to promote hepatocyte proliferation by regulating PI3K/Akt pathway in BRL-3A cells

This study was designed to investigate the role of miR-203a-3p in hepatocyte proliferation. Data analysis showed that up-regulation of miR-203a-3p increased the cell viability and cell proliferation, and inhibited apoptosis. Further experiments demonstrated that PTEN was a target gene of miR-203a-3p, and miR-203a-3p targeted PTEN to regulate the above functions. Overexpression of PTEN partially reversed the inhibition of PTEN and the activation of p-Akt/Akt induced by miR-203a-3p mimic. Our study revealed that miR-203a-3p might activate PI3K/Akt signaling pathway by inhibiting PTEN expression, thereby promoting cell proliferation.

Polymeric Hybrid Nanomicelles for Cancer Theranostics: An Efficient and Precise Anticancer Strategy for the Codelivery of Doxorubicin/miR-34a and Magnetic Resonance Imaging

To realize precise tumor therapy, a versatile oncotherapy nanoplatform integrating both diagnostic and therapeutic functions is necessary. Herein, we fabricated a hybrid micelle (HM) utilizing two amphiphilic diblock copolymers, polyethylenimine-polycaprolactone (PEI-PCL) and diethylenetriaminepentaacetic acid gadolinium(III)  (Gd-DTPA)-conjugated polyethyleneglycol-polycaprolactone (Gd-PEG-PCL), to codeliver the small-molecule chemotherapy drugs doxorubicin (Dox) and microRNA-34a (miR-34a), denoted as Gd-HM-Dox/34a. Conjugating Gd-DTPA on the surface of hybrid micelles, leading the relaxation rate of Gd-DTPA increased more than 1.4 times (13.6 mM^-1 S^-1). Furthermore, hybrid micelles enhanced the ability of miR-34a to escape from lysosomes/endosomes and Dox release to the nucleus. In addition, the released miR-34a subsequently downregulates Bcl-2, cyclin D1, CDK6, and Bax expression and inhibits proliferation and migration of MDA-MB-231 breast cancer cells. Moreover, the suitable micelle size improved the penetration of Dox into three-dimensional (3D) multicellular spheroids compared with Gd-HM-Dox and Free Dox, generating efficient cell killing in the 3D multicellular spheroids. Furthermore, the Gd-HM-Dox/34a exhibited augmented accumulation in the tumor tissue, which improved the magnetic resonance (MR) imaging contrast of solid tumors and enhanced the combined efficiency of chemotherapeutic drugs Dox and therapeutic gene miR-34a in suppressing tumor growth on MDA-MB-231 tumor-bearing mice. Therefore, we established a hybrid micelle to offer a promising theranostic approach that inhibits tumor growth and enhances MR imaging.

Selection of reference genes for miRNA quantitative PCR and its application in miR-34a/Sirtuin-1 mediated energy metabolism in Megalobrama amblycephala

MiRNAs are small, non-coding RNAs that downregulate gene expression at post-transcriptional levels. They have emerged as important regulators involved in metabolism, immunity, and cancer. Real-time quantitative PCR (RT-qPCR) is an effective and main method for quantifying target miRNA. For robust RT-qPCR method, suitable reference genes play crucial roles in data normalization. Blunt snout bream (Megalobrama amblycephala) is an economically important aquaculture species; however, no reference genes dedicated for qPCR method has been identified for this species so far. The objective of this study was to screen stable reference genes for miRNA RT-qPCR and demonstrated its application in energy metabolism in blunt snout bream. The stabilities of ten potential reference genes (miR-21-1-5p, miR-107a-3p, miR-222a-3p, miR-146a-5p, miR-101a-3p, miR-22a-3p, miR-103-3p, miR-456-3p, miR-221-3p, and U6 (RNU6A)) were evaluated in nine tissues (brain, muscle, liver, skin, spleen, heart, gill, intestine, and eye) under normal condition and in three tissues (liver, intestine, and spleen) under four stresses (heat stress, ammonia stress, bacterial challenge, and glycolipid stress). Using GeNorm, NormFinder, and RefFinder softwares, we discovered that different tissues and stresses are both important variability factors for the expression stability of miRNAs. After verifying miR-34a/Sirtuin-1 expressions in high-carbohydrate diet-induced blunt snout bream, we eventually identified that the most stable reference gene in this species was miR-221-3p, and the best combination of reference genes were miR-221-3p and miR-103-3p.

Interplay of non-coding RNAs and approved antimetabolites such as gemcitabine and pemetrexed in mesothelioma

Gemcitabine and pemetrexed are clinically approved antimetabolites for the therapy of mesothelioma diseases. These drugs are often applied in combination with platinum complexes and other drugs. The activity of antimetabolites depended on the expression levels of certain non-coding RNAs, in particular, of small microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). The development of tumor resistance towards antimetabolites was regulated by non-coding RNAs. An overview of the interplay between gemcitabine/pemetrexed antimetabolites and non-coding RNAs in mesothelioma is provided. Further to this, various non-coding RNA-modulating agents are discussed which displayed positive effects on gemcitabine or pemetrexed treatment of mesothelioma diseases. A detailed knowledge of the connections of non-coding RNAs with antimetabolites will be constructive for the design of improved therapies in future.

MicroRNAs for the Diagnosis and Management of Malignant Pleural Mesothelioma: A Literature Review

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor with a variable incidence among different countries. Occupational asbestos exposure is the most important etiological factor and a very long latency period is widely reported. In the early phase of the disease, clinical signs are absent or not specific. For this reason, the diagnosis is frequently achieved only in the advanced stages. The histopathological diagnosis per se is also very complex, and no known factor can predict the prognosis with certainty. Nonetheless, current survival rates remain very low, despite the use of standard treatments, which include surgery, chemotherapy and radiotherapy. The identification of new prognostic and/or diagnostic biomarkers, and the discovery of therapeutic targets is a priority and could lead to a real significant impact on the management of malignant pleural mesothelioma. In this scenario, the role of microRNAs is becoming increasingly relevant, with the promise of a quick translation in the current clinical practice. Despite the relative novelty of this field, the number of works and candidate microRNAs that are present in literature is striking. Unfortunately, to date the microRNAs with the most clinical relevance for MPM are still matter of debate, probably due to the variety of approaches, techniques, and collected samples. Although specific microRNAs (e.g., let-7, miR-15 and miR-16, miR-21, miR-34a, and the miR-200 family) have been reported several times from different groups, the heterogeneity of published data reinforces the need of more comprehensive and unified studies on this topic. In this review we collect and discuss the studies focused on the involvement of microRNAs in different aspects of MPM, from their biological role in tumorigenesis and progression, to their possible application as diagnostic, prognostic and predictive biomarkers. Lastly, we examine their potential value as for the design of therapeutic approaches that could benefit MPM patients.

Relations between approved platinum drugs and non-coding RNAs in mesothelioma

Malignant mesothelioma diseases feature an increasing risk due to their severe forms and their association with asbestos exposure. Platinum(II) complexes such as cisplatin and carboplatin are clinically approved for the therapy of mesothelioma often in combination with antimetabolites such as pemetrexed or gemcitabine. It was observed that pathogenic properties of mesothelioma cells and the response of mesothelioma tumors towards platinum-based drugs are strongly influenced by non-coding RNAs, in particular, by small microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). These non-coding RNAs controlled drug sensitivity and the development of tumor resistance towards platinum drugs. An overview of the interactions between platinum drugs and non-coding RNAs is given and the influence of non-coding RNAs on platinum drug efficacy in mesothelioma is discussed. Suitable non-coding RNA-modulating agents with potentially beneficial effects on cisplatin treatment of mesothelioma diseases are mentioned. The understanding of mesothelioma diseases concerning the interactions of non-coding RNAs and platinum drugs will optimize existing therapy schemes and pave the way to new treatment options in future.

Doxorubicin-loaded poly(ε-caprolactone)-Pluronic micelle for targeted therapy of esophageal cancer

There is still lack of effective treatment of esophageal cancer, and it is urgently necessary to develop a new programs to treat this disease. More and more evidence suggests that the combination of 2 or more treatment strategies can enhance the antitumor activity in cancer treatment. We have established a new therapeutic strategy that combines doxorubicin-loaded poly(ε-caprolactone) (PCL)-Pluronic micelles and miR-34a to better combat esophageal cancer. Doxorubicin was loaded into PCL-Pluronic micelle to achieve better uptake. Confocal microscopy was used to assess in vitro cellular uptake of PCL-Pluronic micelle. Finally, the in vivo effect of this new combination therapy strategy was also studied. The results showed that PCL-Plannick micelles significantly enhanced the uptake of doxorubicin in esophageal cancer cells in vitro, thereby improving the accumulation of doxorubicin in the cells. In vitro and in vivo combination of doxorubicin-loaded PCL-Pluronic micelles and miR-34a, achieving a significantly synergistic therapeutic effect over the corresponding single treatment. These results suggested that the combinational therapy based on doxorubicin-loaded PCL-Pluronic micelle and miR-34a may provide a reasonable strategy for improving the outcome of esophageal cancer treatment.

In Vivo Analysis of miR-34a Regulated Glucose Metabolism Related Genes in Megalobrama amblycephala

The Megalobrama amblycephala (M. amblycephala) is one of the most important economic freshwater fish in China. The molecular mechanism under the glucose intolerance responses which affects the growth performance and feed utilization is still confused. miR-34a was reported as a key regulator in the glucose metabolism, but how did the miR-34a exert its function in the metabolism of glucose/insulin in M. amblycephala was still unclear. In this study, we intraperitoneally injected the miR-34a inhibitor (80 nmol/100 g body weight) into M. amblycephala (fed with high starch diet, 45% starch) for 12 h, and then analyzed the gene expression profiling in livers by RNA-seq. The results showed that miR-34a expression in M. amblycephala livers was inhibited by injection of miR-34a inhibitor, and a total of 2212 differentially expressed genes (DEGs) were dysregulated (including 1183 up- and 1029 downregulated DEGs). Function enrichment analysis of DEGs showed that most of them were enriched in the peroxisome proliferator-activated receptor (PPAR), insulin, AMP-activated protein kinase (AMPK) and janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathways, which were all associated with the glucose/lipid metabolic and biosynthetic processes. In addition, we examined and verified the differential expression levels of some genes involved in AMPK signaling pathway by qRT-PCR. These results demonstrated that the inhibition of miR-34a might regulate glucose metabolism in M. amblycephala through downstream target genes.

Multifunctional Glycoconjugate Assisted Nanocrystalline Drug Delivery for Tumor Targeting and Permeabilization of Lysosomal-Mitochondrial Membrane

Nanotechnology has emerged as the most successful strategy for targeting drug payloads to tumors with the potential to overcome the problems of low concentration at the target site, nonspecific distribution, and untoward toxicities. Here, we synthesized a novel polymeric conjugate comprising chondroitin sulfate A and polyethylene glycol using carbodiimide chemistry. We further employed this glycoconjugate possessing the propensity to provide stability, stealth effects, and tumor targeting via CD44 receptors, all in one, to develop a nanocrystalline system of docetaxel (DTX@CSA-NCs) with size < 200 nm, negative zeta potential, and 98% drug content. Taking advantage of the enhanced permeability and retention effect coupled with receptor mediated endocytosis, the DTX@CSA-NCs cross the peripheral tumor barrier and penetrate deeper into the cells of tumor mass. In MDA-MB-231 cells, this enhanced cellular uptake was observed to exhibit a higher degree of cytotoxicity and arrest in the G2 phase in a time dependent fashion. Acting via a mitochondrial-lysosomotropic pathway, DTX@CSA-NCs disrupted the membrane potential and integrity and outperformed the clinically used formulation. Upon intravenous administration, the DTX@CSA-NCs showed better pharmacokinetic profile and excellent 4T1 induced tumor inhibition with significantly less off target toxicity. Thus, this glycoconjugate stabilized nanocrystalline formulation has the potential to take nano-oncology a step forward.

Diagnostic value of microRNAs in asbestos exposure and malignant mesothelioma: systematic review and qualitative meta-analysis

Background

Asbestos is a harmful and exceptionally persistent natural material. Malignant mesothelioma (MM), an asbestos-related disease, is an insidious, lethal cancer that is poorly responsive to current treatments. Minimally invasive, specific, and sensitive biomarkers providing early and effective diagnosis in high-risk patients are urgently needed. MicroRNAs (miRNAs, miRs) are endogenous, non-coding, small RNAs with established diagnostic value in cancer and pollution exposure. A systematic review and a qualitative meta-analysis were conducted to identify high-confidence miRNAs that can serve as biomarkers of asbestos exposure and MM.

Methods

The major biomedical databases were systematically searched for miRNA expression signatures related to asbestos exposure and MM. The qualitative meta-analysis applied a novel vote-counting method that takes into account multiple parameters. The most significant miRNAs thus identified were then subjected to functional and bioinformatic analysis to assess their biomarker potential.

Results

A pool of deregulated circulating and tissue miRNAs with biomarker potential for MM was identified and designated as “mesomiRs” (MM-associated miRNAs). Comparison of data from asbestos-exposed and MM subjects found that the most promising candidates for a multimarker signature were circulating miR-126-3p, miR-103a-3p, and miR-625-3p in combination with mesothelin. The most consistently described tissue miRNAs, miR-16-5p, miR-126-3p, miR-143-3p, miR-145-5p, miR-192-5p, miR-193a-3p, miR-200b-3p, miR-203a-3p, and miR-652-3p, were also found to provide a diagnostic signature and should be further investigated as possible therapeutic targets.

Conclusion

The qualitative meta-analysis and functional investigation confirmed the early diagnostic value of two miRNA signatures for MM. Large-scale, standardized validation studies are needed to assess their clinical relevance, so as to move from the workbench to the clinic.

MiR-34a, as a suppressor, enhance the susceptibility of gastric cancer cell to luteolin by directly targeting HK1

Luteolin is a flavonoid compound derived from Lonicera japonica Thunb, which has been reported to exert anticancer effects on different types of tumors. miRNAs are a kind of endogenous non-coding small RNAs, which involved in occurrence and development of multi cancer, including miR-34a. However, the relationship between miR-34a and luteolin's susceptibility to cancer cells still remains unclear. In this study, we explored the roles of miR-34a and the effects of luteolin on GC cells as well as the underlying mechanism of miR-34a in mediating the susceptibility of GC cell to luteolin. Retrospectively study revealed that miR-34a expression was downregulated in human primary GC tissues compared with non-tumor tissues and low miR-34a expression was associated with a significantly shorter overall survival and disease-free survival. MiR-34a overexpression could inhibit GC cells and induce G1 phase arrest via p53/p21 and MAPK /ERK pathways. Luteolin decreased viability of GC cells in a dose-dependent manner. Meanwhile, miR-34a was found to be markedly upregulated in GC cells induced by luteolin and decreased miR-34a level was found in the artificial luteolin-resistant GC cells. Upregulation of miR-34a in luteolin-resistant GC cell could enhance the sensibility of GC cells to luteolin. On the other hand, miR-34a inhibitor could partly counter the anticancer effect of luteolin. In a further assay, we also found that targeting miR-34a could mediate the susceptibility of mouse xenografts to luteolin. Subsequent study found that HK1 was a direct target of miR-34a and downregulated HK1 mRNA or protein levels were presented after miRNA-34a overexpression in GC cells. Moreover, HK1 protein levels was decreased after luteolin treatment and partly restored when co-treated with luteolin and miR-34a inhibitor. Downregulation of HK1 in luteolin-resistant GC cell could increase the cell's sensitivity to luteolin. Therefore, our findings firstly suggested that miR-34a could modulate the susceptibility of gastric cancer cell to luteolin via targeting HK1, potentially benefiting GC patients' treatment in the future.

microRNAs are differentially regulated between MDM2-positive and negative malignant pleural mesothelioma

Background

Malignant pleural mesothelioma (MPM) is a highly aggressive tumour first-line treated with a combination of cisplatin and pemetrexed. MDM2 and P14/ARF (CDKN2A) are upstream regulators of TP53 and may contribute to its inactivation. In the present study, we now aimed to define the impact of miRNA expression on this mechanism.

Material and Methods

24 formalin-fixed paraffin-embedded (FFPE) tumour specimens were used for miRNA expression analysis of the 800 most important miRNAs using the nCounter technique (NanoString). Significantly deregulated miRNAs were identified before a KEGG-pathway analysis was performed.

Results

17 miRNAs regulating TP53, 18 miRNAs regulating MDM2, and 11 miRNAs directly regulating CDKN2A are significantly downregulated in MDM2-expressing mesotheliomas. TP53 is downregulated in MDM2-negative tumours through miRNAs with a miSVR prediction score of 11.67, RB1 with a prediction score of 8.02, MDM2 with a prediction score of 4.50 and CDKN2A with a prediction score of 1.27.

Conclusion

MDM2 expression seems to impact miRNA expression levels in MPM. Especially, miRNAs involved in TP53-signaling are strongly decreased in MDM2-positive mesotheliomas. A better understanding of its tumour biology may open the chance for new therapeutic approaches and thereby augment patients' outcome.

Blockage of epithelial to mesenchymal transition and upregulation of let 7b are critically involved in ursolic acid induced apoptosis in malignant mesothelioma cell

Malignant pleural mesothelioma (MPN), which is caused by asbestos exposure, is one of aggressive lung tumors. In the present study, we elucidated the anti-tumor mechanism of ursolic acid in malignant mesotheliomas. Ursolic acid significantly exerted cytotoxicity in a time and dose dependent manner in H28, H2452 and MSTO-211H mesothelioma cells and inhibited cell proliferation by colony formation assay in a dose-dependent fashion. Also, ursolic acid treatment accumulated the sub-G1 population, attenuated the expression of procapase 9, cyclin D1, pAKT, p-glycogen synthase kinase 3-alpha/beta (pGSK3α/β), β-catenin and nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB) and also cleaved caspase 3 and poly (ADP-ribose) polymerase (PARP) in mesothelioma cells. Furthermore, ursolic acid treatment blocked epithelial and mesenchymal transition (EMT) molecules by activating E-cadherin as an epithelial marker and attenuating Vimentin, and Twist as mesenchymal molecules. Interestingly, miRNA array revealed that 23 miRNAs (>2 folds) including let-7b and miRNA3613-5p, miRNA134 and miRNA196b were significantly upregulated while 33 miRNAs were downregulated in ursolic acid treated H2452 cells. Furthermore, overexpression of let 7b using let-7b mimics enhanced the antitumor effect of ursolic acid to attenuate the expression of procaspases 3, pro-PARP, pAKT, β-catenin and Twist and increase sub-G1 accumulation in H2452 mesothelioma cells. Overall, our findings suggest that ursolic acid induces apoptosis via inhibition of EMT and activation of let7b in mesothelioma cells as a potent chemotherapeutic agent for treatment of malignant mesotheliomas.

Role of microRNA in liver regeneration

BACKGROUND

Liver regeneration is a complex process. microRNAs (miRNAs) are short, single-stranded RNAs that modify gene expression at the post-transcriptional level. Recent investigations have revealed that miRNAs are closely linked to liver regeneration.

DATA SOURCES

All included studies were obtained from PubMed, Embase, the ScienceDirect databases and Web of Science, with no limitation on publication year. Only studies published in English were considered.

RESULTS

We grouped studies that involved miRNA and liver regeneration into two groups: miRNAs as promoters and as inhibitors of liver regeneration. We summarized the relevant miRNAs separately from the related pathways.

CONCLUSIONS

Blocking or stimulating the pathways of miRNAs in liver regeneration may be novel therapeutic strategies in future regeneration-related liver managements. We may discover additional chemotherapy targets of miRNA.

In Vivo Delivery of miR-34a Sensitizes Lung Tumors to Radiation Through RAD51 Regulation

MiR-34a, an important tumor-suppressing microRNA, is downregulated in several types of cancer; loss of its expression has been linked with unfavorable clinical outcomes in non-small-cell lung cancer (NSCLC), among others. MiR-34a represses several key oncogenic proteins, and a synthetic mimic of miR-34a is currently being tested in a cancer trial. However, little is known about the potential role of miR-34a in regulating DNA damage response and repair. Here, we demonstrate that miR-34a directly binds to the 3' untranslated region of RAD51 and regulates homologous recombination, inhibiting double-strand-break repair in NSCLC cells. We further demonstrate the therapeutic potential of miR-34a delivery in combination with radiotherapy in mouse models of lung cancer. Collectively, our results suggest that administration of miR-34a in combination with radiotherapy may represent a novel strategy for treating NSCLC.

Upregulation of miR-34a-5p antagonizes AFB1-induced genotoxicity in F344 rat liver

Aflatoxin B1 (AFB1) is a well-known human hepatotoxicant and genotoxicant. Recent studies demonstrated that aberrant miRNA expression patterns were correlated with the cellular and genetic lesions induced by chemicals. To explore the role of miRNAs in AFB1-induced hepatotoxicity and genotoxicity, we examined alterations in miRNA expression patterns in F334 rat livers after exposure to 100 μg/kg or 200 μg/kg AFB1 for 28 days. Using high-throughput sequencing, we discovered that rno-miR-34a-5p, rno-miR-200b-3p, and rno-miR-429 were up-regulated and that rno-miR-130a-3p was down-regulated in liver tissue from rats that received 200 μg/kg of AFB1; this finding was validated by real-time PCR. AFB1 treatment resulted in the upregulation of rno-miR-34a-5p and rno-miR-200b-3p in the rat H-4-II-E cell line similar to our in vivo observations. Moreover, rno-miR-34a-5p was transcriptionally elevated via p53 activation after AFB1 exposure. Upregulation of rno-miR-34a-5p suppressed the expression of the cell cycle-related genes CCND1, CCNE2 and MET and led to cell cycle arrest in the G0-G1 phase. The CBMN assay indicated that inhibition of rno-miR-34a-5p and p53 expression aggravated the DNA damage induced by AFB1, which might be associated with shortening of the DNA damage repair period. Circulating miR-34a-5p in rat sera preceded a significant increase in ALT activity and other miRNAs in the 100 μg/kg AFB1 group. These observations demonstrated that rno-miR-34a-5p responded sensitively to AFB1 exposure and facilitated p53 repair of DNA damage by impacting the cell cycle. Thus, circulating rno-miR-34a-5p may be a sensitive indicator for the induction of hepatic genotoxicity by AFB1 in rats.

MicroRNA-34a induces a senescence-like change via the down-regulation of SIRT1 and up-regulation of p53 protein in human esophageal squamous cancer cells with a wild-type p53 gene background

MiR-34a has been reported as a non-coding RNA universally expressed in normal old cells and a probable suppressor of diverse cancer cells; however, this miRNA's expression and anti-tumor mechanism in esophageal squamous cancer cells (ESCC) remains unclear. We explored these questions in three human ESCC lines, KYSE-450, KYSE-410, and ECa-109, with wild-type p53 and mutant p53 backgrounds. Through a specific stem-loop RT primer for miR-34a, we examined the relevant expression level of miR-34a in these three cell lines using real-time reverse transcription PCR (qRT-PCR). We found that the expression level of miR-34a induced by the DNA damage agent adrmycin (ADR) was both p53- and time-dependent. Following incubation with miR-34a, cellular growth inhibition was exhibited differently in the three cell lines harbored with different p53 backgrounds. Furthermore, the MTT assay demonstrated an miR-34a-related cytotoxic effect in cell growth. Senescence-associated β-galactosidase (SA-β-Gal) staining was used to examine senescence-like phenotypes induced by miR-34a. Mechanistic investigation suggested that the down-regulation of Sirtuin1 (SIRT1) and up-regulation of p53/p21 contributed to the anti-tumor mechanism of miR-34a in wild-type p53 ECa-109 cells, while neither of the apoptosis-related proteins PARP and caspase-3 caused significant changes. In summary, our findings indicated that the intrinsic expression of miR-34a was relatively low and was expressed differently among different p53 backgrounds and ADR treatment times. The anti-tumor effect of miR-34a was primarily dependent on the regulation of SIRT1 and p53/p21 protein, not apoptosis-associated proteins.

Neoadjuvant Chemotherapy in Breast Cancer Patients Induces miR-34a and miR-122 Expression

Circulating microRNAs (miRNAs) have been extensively studied in cancer as biomarkers but little is known regarding the influence of anti-cancer drugs on their expression levels. In this article, we describe the modifications of circulating miRNAs profile after neoadjuvant chemotherapy (NAC) for breast cancer. The expression of 188 circulating miRNAs was assessed in the plasma of 25 patients before and after NAC by RT-qPCR. Two miRNAs, miR-34a and miR-122, that were significantly increased after NAC, were measured in tumor tissue before and after chemotherapy in 7 patients with pathological partial response (pPR) to NAC. These two chemotherapy-induced miRNAs were further studied in the plasma of 22 patients with adjuvant chemotherapy (AC) as well as in 12 patients who did not receive any chemotherapy. Twenty-five plasma miRNAs were modified by NAC. Among these miRNAs, miR-34a and miR-122 were highly upregulated, notably in pPR patients with aggressive breast cancer. Furthermore, miR-34a level was elevated in the remaining tumor tissue after NAC treatment. Studying the kinetics of circulating miR-34a and miR-122 expression during NAC revealed that their levels were especially increased after anthracycline-based chemotherapy. Comparisons of the plasma miRNA profiles after NAC and AC suggested that chemotherapy-induced miRNAs originated from both tumoral and non-tumoral compartments. This study is the first to demonstrate that NAC specifically induces miRNA expression in plasma and tumor tissue, which might be involved in the anti-tumor effects of chemotherapy in breast cancer patients.

The role of microRNAs 371 and 34a in androgen receptor control influencing prostate cancer behavior

BACKGROUND

The molecular mechanisms involved in androgen receptor (AR) signaling pathways are not completely understood, and deregulation of microRNAs (miRNAs) expression may play a role in prostate cancer (PC) development and progression.

METHODS

The expression levels of miRNA and AR were evaluated with quantitative real-time polymerase chain reaction using frozen tissue from the surgical specimens of 83 patients submitted to radical prostatectomy. The expression level of miRNAs was correlated with prognostic factors and biochemical recurrence during a follow-up period of 45 months. In vitro and in vivo experiments were performed to understand the effect of miRNAs over AR in the context of that seen in a PC model.

RESULTS

MiR-371 underexpression correlated with non-organ-confined (pT3) disease (P = 0.009). In vitro transfection of miR-371 reduced the levels of AR by 22% and 28% in LNCaP and PC3 cell lines, respectively, and in kallikrein 3, it was reduced by 51%. PC was induced in Balb/c mice using PC-3M-luc-C6 cells, and animals were treated with 3 local doses of miR-371. Tumor growth evaluated by in vivo imaging after luciferase injection was slower in animals treated with miR-371. To explore further the possible role of miRNAs in the AR pathway, LNCaP cell line was treated with 5α-dihydrotestosterone and flutamide showing alteration in miRNAs expression, especially miR-34a, which was significantly underexpressed after treatment with high doses of 5α-dihydrotestosterone.

CONCLUSION

Our data support a role for miRNAs, especially miR-371 and miR-34a, in the complex disarrangement of AR signaling pathway and in the behavior of PC.

miR-34: from bench to bedside

The mir-34 family was originally cloned and characterized in 2007 as a p53 target gene. Almost immediately it became clear that its major role is as a master regulator of tumor suppression. Indeed, when overexpressed, it directly and indirectly represses several oncogenes, resulting in an increase of cancer cell death (including cancer stem cells), and in an inhibition of metastasis. Moreover, its expression is deregulated in several human cancers. In 2013, a miR-34 mimic has become the first microRNA to reach phase 1 clinical trials. Here we review the miR-34 family and their role in tumor biology, and discuss the potential therapeutic applications of miR-34a mimic.

MiR-34a inhibits migration and invasion by regulating the SIRT1/p53 pathway in human SW480 cells

MicroRNA-34a (miR-34a) is a direct transcriptional target of p53, and is downregulated in several different types of cancer. However, the underlying mechanism of the miR-34a effects in colorectal cancer is not well understood. In this study, we explored the role of miR-34a in cell invasion, migration, and apoptosis. Transient overexpression of miR-34a in SW480 cells caused a severe decrease in cell migration and invasion (both, p<0.05) compared to the control groups. Combining miR-34a transfection with 5-fluorouracil (5-FU) treatment further enhanced the inhibition in SW480 cell migration and invasion (both, p<0.05) compared to 5-FU treatment alone. These cellular changes were associated with upregulation of acetylated‑p53 (ac-p53) and p21 and downregulation of sirtuin 1 (SIRT1). These data demonstrate that miR-34a regulates the expression of a number of critical proteins involved in apoptosis, proliferation and the response to chemotherapy. In summary, miR-34a increases the sensitivity of colon cancer cells to 5-FU treatment through specific regulation of the SIRT1/p53 pathway.

Hypofractionated radiotherapy induces miR-34a expression and enhances apoptosis in human nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a relatively radiosensitive disease. However, the therapeutic effects of radiotherapy are not always satisfactory due to radioresistance. The hypofractionated schema is currently widely used in clinical practice. In the present study, we investigated the effects of hypofractionated radiotherapy on NPC cells and explored the mechanisms involved. In addition, we aimed to determine the role of miR-34a in the effects of hypofractionated radiotherapy and whether these effects occur in a p53-dependent manner. For this purpose, we used CNE1 and CNE2 NPC cells which were subjected to hyperfractionated and hypofractionated radiotherapy. The viability of the cells was measured by MTT assay and acridine orange (AO) and ethidium bromide (EB) staining was used to observe morphological changes. In addition, Annexin V-propidium iodide (PI) staining and flow cytometry were used to determine the number of apoptotic cells and mRNA and protein expression was measured by qPCR and western blot analysis, respectively. The results revealed that hypofractionated radiotherapy enhanced apoptosis and increased the expression of miR-34a and p53 in the NPC cells. In addition, it stimulated p53 promoter activity and downregulated the protein expression of c-Myc in the human NPC cells. Furthermore, the knockdown of miR-34a suppressed the growth inhibitory effects induced by hypofractionated radiotherapy. Thus, our results suggest that the enhanced apoptosis of NPC cells may be associated with the miR-34a-mediated suppression of c-Myc in a p53-dependent manner.

Discovery of an integrative network of microRNAs and transcriptomics changes for acute kidney injury

The contribution of miRNA to the pathogenesis of acute kidney injury (AKI) is not well understood. Here we evaluated an integrative network of miRNAs and mRNA data to discover a possible master regulator of AKI. Microarray analyses of the kidneys of mice treated with cisplatin were used to extract putative miRNAs that cause renal injury. Of them, miR-122 was mostly downregulated by cisplatin, whereas miR-34a was upregulated. A network integrating dysregulated miRNAs and altered mRNA expression along with target prediction enabled us to identify Foxo3 as a core protein to activate p53. The miR-122 inhibited Foxo3 translation as assessed using an miR mimic, an inhibitor, and a Foxo3 3'-UTR reporter. In a mouse model, Foxo3 levels paralleled the degree of tubular injury. The role of decreased miR-122 in inducing Foxo3 during AKI was strengthened by the ability of the miR-122 mimic or inhibitor to replicate results. Increase in miR-34a also promoted the acetylation of Foxo3 by repressing Sirt1. Consistently, cisplatin facilitated the binding of Foxo3 and p53 for activation, which depended not only on decreased miR-122 but also on increased miR-34a. Other nephrotoxicants had similar effects. Among targets of p53, Phlda3 was robustly induced by cisplatin, causing tubular injury. Consistently, treatment with miR mimics and/or inhibitors, or with Foxo3 and Phlda3 siRNAs, modulated apoptosis. Thus, our results uncovered an miR integrative network regulating toxicant-induced AKI and identified Foxo3 as a bridge molecule to the p53 pathway.

microRNA-34a promotes DNA damage and mitotic catastrophe

Efficient and error-free DNA repair is critical for safeguarding genome integrity, yet it is also linked to radio- and chemoresistance of malignant tumors. miR-34a, a potent tumor suppressor, influences a large set of p53-regulated genes and contributes to p53-mediated apoptosis. However, the effects of miR-34a on the processes of DNA damage and repair are not entirely understood. We explored tet-inducible miR-34a-expressing human p53 wild-type and R273H p53 mutant GBM cell lines, and found that miR-34a influences the broad spectrum of 53BP1-mediated DNA damage response. It escalates both post-irradiation and endogenous DNA damage, abrogates radiation-induced G 2/M arrest and drastically increases the number of irradiated cells undergoing mitotic catastrophe. Furthermore, miR-34a downregulates 53BP1 and inhibits its recruitment to the sites of DNA double-strand breaks. We conclude that whereas miR-34a counteracts DNA repair, it also contributes to the p53-independent elimination of distressed cells, thus preventing the rise of genomic instability in tumor cell populations. These properties of miR-34a can potentially be exploited for DNA damage-effecting therapies of malignancies.

Synergistic effects of curcumin with emodin against the proliferation and invasion of breast cancer cells through upregulation of miR-34a

Curcumin, a biphenyl compound derived from rhizome, is a powerful anti-cancer agent. Emodin is an active component isolated from the root and rhizome of Rheum palmatum that has been widely used in traditional Chinese medicine for the treatment of various diseases. Currently, there are no studies examining the effect of curcumin in combination with emodin on tumor cell growth. In this study, we report for the first time that combined curcumin and emodin administration synergistically inhibits proliferation (MTT assay), survival (flow cytometry), and invasion (transwell migration assay) of breast cancer cells. Synergism is determined by the Chou-Talalay method. Moreover, we demonstrate that miR-34a is upregulated by curcumin and emodin. This microRNA helps mediate the anti-tumor effects of curcumin and emodin by downregulating Bcl-2 and Bmi-1. Our results not only provide insight into the mechanism of synergy between curcumin and emodin in breast cancer cells, but also suggest a new and potentially useful approach for breast cancer therapy.

New insights into understanding the mechanisms, pathogenesis, and management of malignant mesotheliomas

Malignant mesothelioma (MM) is a relatively rare but devastating tumor that is increasing worldwide. Yet, because of difficulties in early diagnosis and resistance to conventional therapies, MM remains a challenge for pathologists and clinicians to treat. In recent years, much has been revealed regarding the mechanisms of interactions of pathogenic fibers with mesothelial cells, crucial signaling pathways, and genetic and epigenetic events that may occur during the pathogenesis of these unusual, pleiomorphic tumors. These observations support a scenario whereby mesothelial cells undergo a series of chronic injury, inflammation, and proliferation in the long latency period of MM development that may be perpetuated by durable fibers, the tumor microenvironment, and inflammatory stimuli. One culprit in sustained inflammation is the activated inflammasome, a component of macrophages or mesothelial cells that leads to production of chemotactic, growth-promoting, and angiogenic cytokines. This information has been vital to designing novel therapeutic approaches for patients with MM that focus on immunotherapy, targeting growth factor receptors and pathways, overcoming resistance to apoptosis, and modifying epigenetic changes.

MiR-34a inhibits proliferation and migration of breast cancer through down-regulation of Bcl-2 and SIRT1

MicroRNA-34a(miR-34a), a pivotal member of the p53 network, was found to be down-regulated in multiple types of tumors and further reported as a tumor suppressor microRNA. However, the profile and biological effects of miR-34a in breast cancer are still unclear. In this study, we aimed to determine the effect of miR-34a on the growth of breast cancer and to investigate whether its effect is achieved by targeting Bcl-2 and SIRT1. We examined miR-34a levels in breast cancer cell lines and breast cancer specimens by qRT-PCR. Proliferation assay, apoptosis assay, and morphological monitoring were performed to assess the tumor suppression effect of miR-34a in breast cancer cell lines. Western blotting was used to identify the targets of miR-34a. We also investigated the anti-tumor effects of the treatment combining miR-34a with 5-FU in breast cancer cells. We found that miR-34a expression was down-regulated in 5 breast cancer cell lines compared with the immortalized normal mammary epithelial cell line 184A1, and was also down-regulated by almost 50 % in breast cancer samples compared with their corresponding adjacent non-malignant breast tissues. Ectopic restoration of miR-34a in breast cancer cells suppressed cells proliferation, invasion, and induced apoptosis. Bcl-2 and SIRT1 as the targets of miR-34a were found to be in reverse correlation with ectopic expression of miR-34a. Furthermore, the treatment combining miR-34a with 5-FU significantly showed more efficient anti-tumor effects than single treatment of miR-34a or 5-FU. Since miR-34a functions as tumor suppressor microRNA in breast cancer, modulating miR-34a level in breast cancer was suggested to be a new and useful approach of breast cancer therapy.

Novel drug delivery system based on docetaxel-loaded nanocapsules as a therapeutic strategy against breast cancer cells

In the field of cancer therapy, lipid nanocapsules based on a core-shell structure are promising vehicles for the delivery of hydrophobic drugs such as docetaxel. The main aim of this work was to evaluate whether docetaxel-loaded lipid nanocapsules improved the anti-tumor effect of free docetaxel in breast cancer cells. Three docetaxel-loaded lipid nanocapsules were synthesized by solvent displacement method. Cytotoxic assays were evaluated in breast carcinoma (MCF-7) cells treated by the sulforhodamine B colorimetric method. Cell cycle was studied by flow cytometry and Annexin V-FITC, and apoptosis was evaluated by using propidium iodide assays. The anti-proliferative effect of docetaxel appeared much earlier when the drug was encapsulated in lipid nanoparticles than when it was free. Docetaxel-loaded lipid nanocapsules significantly enhanced the decrease in IC₅₀ rate, and the treated cells evidenced apoptosis and a premature progression of the cell cycle from G(1) to G(2)-M phase. The chemotherapeutic effect of free docetaxel on breast cancer cells is improved by its encapsulation in lipid nanocapsules. This approach has the potential to overcome some major limitations of conventional chemotherapy and may be a promising strategy for future applications in breast cancer therapy.