Knockdown of microRNA-29a Changes the Expression of Heat Shock Proteins in Breast Carcinoma MCF-7 Cells

Current knowledge on therapeutic, diagnostic, and prognostics applications of exosomes in multiple myeloma: Opportunities and challenges

Interactions between the plasma cells and the BM microenvironment of Multiple myeloma (MM) take place through factors such as exosomes. Many studies have confirmed the role of exosomes in these interactions. By carrying proteins, cytokines, lipids, microRNAs, etc. as their cargo, exosomes can regulate the interactions between MM plasma cells and neighboring cells and participate in the signaling between cancer cells and the environment. It has been shown that MM-derived exosomes can induce angiogenesis, enhance osteoblast activity, confer drug resistance, and have immunosuppressive properties. Abnormal cargos in endosomes originating from MM patients, can be used as a cancer biomarker to detect or screen early prognosis in MM patients. The native nanostructure of exosomes, in addition to their biocompatibility, stability, and safety, make them excellent candidates for therapeutic, drug delivery, and immunomodulatory applications against MM. On the other hand, exosomes derived from dendritic cells (DC) may be used as vaccines against MM. Thanks to the development of new 'omics' approaches, we anticipate to hear more about exosomes in fight against MM. In the present review, we described the most current knowledge on the role of exosomes in MM pathogenesis and their potential role as novel biomarkers and therapeutic tools in MM.

Prospects and challenges of noncoding-RNA-mediated inhibition of heat shock protein 90 for cancer therapy

Heat Shock Protein 90 (HSP90) is a potential drug target for cancer therapy as it is often dysregulated in several cancers, including lung, breast, pancreatic, and prostate cancers. In cancer, HSP90 fails to maintain the structural and functional integrity of its several client proteins which are involved in the hallmarks of cancer such as cell proliferation, invasion, migration, angiogenesis, and apoptosis. Several small molecule inhibitors of HSP90 have been shown to exhibit anticancer effects in vitro and in vivo animal models. However, a few of them are currently under clinical studies. The status and potential limitations of these inhibitors are discussed here. Studies demonstrate that several noncoding RNAs (ncRNAs) such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) regulate HSP90 and its client proteins to modulate cellular processes to exhibit oncogenic or tumor suppressing properties. Over the last decade, miRNAs and lncRNAs have drawn significant interest from the scientific community as therapeutic agents or targets for clinical applications. Here, we discuss the detailed mechanistic regulation of HSP90 and its client proteins by ncRNAs. Moreover, we highlight the significance of these ncRNAs as potential therapeutic agents/targets, and the challenges associated with ncRNA-based therapies. This article aims to provide a holistic view on HSP90-regulating ncRNAs for the development of novel therapeutic strategies to combat cancer.

Regulation of rat HspB5/alphaB-Crystallin by microRNAs miR-101a-3p, miR-140-5p, miR-330-5p, and miR-376b-3p

HspB5/alphaB-crystallin is an ubiquitously expressed member of the small heat shock protein family which help cells to survive cellular stress conditions and are also implicated in neurodegenerative diseases. MicroRNAs are small non-coding RNAs fine-tuning protein expression mainly by inhibiting the translation of target genes. Our earlier finding of an increase in HspB5/alphaB-crystallin protein amount after heat shock in rat hippocampal neurons without a concomitant increase of mRNA prompted us to look for microRNAs as a posttranscriptional regulatory mechanism. Microarray miRNA expression data of rat hippocampal neurons under control and stress conditions in combination with literature search, miRNA binding site prediction and conservation of target sites yielded nine candidate microRNAs. Of these candidates, five (miR-101a-3p, miR-129-2-3p, miR-330-5p, miR-376b-3p, and miR-491-5p) were able to convey a downregulation by binding to the HspB5 3'- or 5'-UTR in a luciferase reporter gene assay while one (miR-140-5p) led to an upregulation. Overexpression of these six microRNAs in C6 glioma cells showed that three of them (miR-101a-3p, miR-140-5p, and miR-376b-3p) regulated endogenous HspB5 protein amount significantly in the same direction as in the reporter gene assay. In addition, overexpression of miR-330-5p and miR-491-5p in C6 cells resulted in regulation of HspB5 in the opposite direction as expected from the luciferase assay. Analysis of miRNA expression in rat hippocampal neurons after cellular stress by qPCR showed that miR-491-5p was not expressed in these cells. In total, we therefore identified four microRNAs, namely miR-101a-3p, miR-140-5p, miR-330-5p, and miR-376b-3p, which can regulate rat HspB5 directly or indirectly.

HSP90 and Noncoding RNAs

Heat shock protein 90 (HSP90) family is a class of proteins known as molecular chaperones that promote client protein folding and translocation in unstressed cells and regulate cellular homeostasis in the stress response. Noncoding RNAs (ncRNAs) are defined as RNAs that do not encode proteins. Previous studies have shown that ncRNAs are key regulators of multiple fundamental cellular processes, such as development, differentiation, proliferation, transcription, post-transcriptional modifications, apoptosis, and cell metabolism. It is known that ncRNAs do not act alone but function via the interactions with other molecules, including co-chaperones, RNAs, DNAs, and so on. As a kind of molecular chaperone, HSP90 is also involved in many biological procedures of ncRNAs. In this review, we systematically analyze the impact of HSP90 on various kinds of ncRNAs, including their synthesis and function, and how ncRNAs influence HSP90 directly and indirectly.

The Chaperone System in Breast Cancer: Roles and Therapeutic Prospects of the Molecular Chaperones Hsp27, Hsp60, Hsp70, and Hsp90

Breast cancer (BC) is a major public health problem, with key pieces of information needed for developing preventive and curative measures still missing. For example, the participation of the chaperone system (CS) in carcinogenesis and anti-cancer responses is poorly understood, although it can be predicted to be a crucial factor in these mechanisms. The chief components of the CS are the molecular chaperones, and here we discuss four of them, Hsp27, Hsp60, Hsp70, and Hsp90, focusing on their pro-carcinogenic roles in BC and potential for developing anti-BC therapies. These chaperones can be targets of negative chaperonotherapy, namely the elimination/blocking/inhibition of the chaperone(s) functioning in favor of BC, using, for instance, Hsp inhibitors. The chaperones can also be employed in immunotherapy against BC as adjuvants, together with BC antigens. Extracellular vesicles (EVs) in BC diagnosis and management are also briefly discussed, considering their potential as easily accessible carriers of biomarkers and as shippers of anti-cancer agents amenable to manipulation and controlled delivery. The data surveyed from many laboratories reveal that, to enhance the understanding of the role of the CS in BS pathogenesis, one must consider the CS as a physiological system, encompassing diverse members throughout the body and interacting with the ubiquitin–proteasome system, the chaperone-mediated autophagy machinery, and the immune system (IS). An integrated view of the CS, including its functional partners and considering its highly dynamic nature with EVs transporting CS components to reach all the cell compartments in which they are needed, opens as yet unexplored pathways leading to carcinogenesis that are amenable to interference by anti-cancer treatments centered on CS components, such as the molecular chaperones.

Long non-coding RNAs and microRNAs as crucial regulators in cardio-oncology

Cancer is one of the leading causes of morbidity and mortality worldwide. Significant improvements in the modern era of anticancer therapeutic strategies have increased the survival rate of cancer patients. Unfortunately, cancer survivors have an increased risk of cardiovascular diseases, which is believed to result from anticancer therapies. The emergence of cardiovascular diseases among cancer survivors has served as the basis for establishing a novel field termed cardio-oncology. Cardio-oncology primarily focuses on investigating the underlying molecular mechanisms by which anticancer treatments lead to cardiovascular dysfunction and the development of novel cardioprotective strategies to counteract cardiotoxic effects of cancer therapies. Advances in genome biology have revealed that most of the genome is transcribed into non-coding RNAs (ncRNAs), which are recognized as being instrumental in cancer, cardiovascular health, and disease. Emerging studies have demonstrated that alterations of these ncRNAs have pathophysiological roles in multiple diseases in humans. As it relates to cardio-oncology, though, there is limited knowledge of the role of ncRNAs. In the present review, we summarize the up-to-date knowledge regarding the roles of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in cancer therapy-induced cardiotoxicities. Moreover, we also discuss prospective therapeutic strategies and the translational relevance of these ncRNAs.

Role of Extracellular Vesicles in Compromising Cellular Resilience to Environmental Stressors

Extracellular vesicles (EVs), like exosomes, are nanosized membrane-enveloped vesicles containing different bioactive cargo, such as proteins, lipids, mRNA, miRNA, and other small regulatory RNAs. Cell-derived EVs, including EVs originating from stem cells, may capture components from damaged cells or cells impacted by therapeutic treatments. Interestingly, EVs derived from stem cells can be preconditioned to produce and secrete EVs with different therapeutic properties, particularly with respect to heat-shock proteins and other molecular cargo contents. This behavior is consistent with stem cells that also respond differently to various microenvironments. Heat-shock proteins play roles in cellular protection and mediate cellular resistance to radiotherapy, chemotherapy, and heat shock. This review highlights the possible roles EVs play in mediating cellular plasticity and survival when exposed to different physical and chemical stressors, with a special focus on the respiratory distress due to the air pollution.

Curcumin loaded on graphene nanosheets induced cell death in mammospheres from MCF-7 and primary breast tumor cells

Elimination of tumor cells is still a therapeutic challenge for breast cancer (BC) in men and women. Mammospheres serve as valuablein vitrotools for evaluating tumor behavior and sensitivity to anticancer treatments. Graphene nanosheets with unique physicochemical properties have been considered as potential biomedical approaches for drug delivery, bioimaging, and therapy. Graphene oxide (GO) and graphene quantum dots (GQDs) are suitable nanocarriers for hydrophobic and low bioaccessible anti-tumor materials like curcumin. Despite extensive studies on the potential application of graphene nanosheets in medicine, our knowledge of how different cells function and respond to these nanoparticles remains limited. Here, we evaluated cell death in mammospheres from MCF-7 and primary tumor cells in response to curcumin loaded on graphene nanosheets. Mammospheres were exposed to graphene oxide-curcumin (GO-Cur) and graphene quantum dots-curcumin (GQDs-Cur), and the incidence of cell death was evaluated by Hoechst 33342/propidium iodide double staining and flow cytometry. Besides, the expression of miR-21, miR-29a, Bax, and Bcl-2 genes were assessed using RT-qPCR. We observed, GO, and GQDs had no cytotoxic effect on Kerman male breast cancer/71 (KMBC/71) and MCF-7 tumor cells, while curcumin induced death in more than 50% of tumor cells. GO-Cur and GQDs-Cur synergistically enhanced anti-tumor activity of curcumin. Moreover, GQDs-Cur induced cell death in almost all cells of KMBC/71 mammospheres (99%;p< 0.0001). In contrast, GO-Cur induced cell death in only 21% of MCF-7 mammosphere cells (p< 0.0001). Also, the expression pattern of miR-21, miR-29a, and Bax/Bcl-2 ratio in KMBC/71 and MCF-7 mammospheres was different in response to GO-Cur and GQDs-Cur. Although KMBC/71 and MCF-7 tumor cells had similar clinical features and displayed similar responses to curcumin, more investigations are needed to clarify the detailed molecular mechanisms underlying observed differences in response to GO-Cur and GQDs-Cur.

HSP60 in cancer: a promising biomarker for diagnosis and a potentially useful target for treatment

Heat shock proteins (HSPs), most of which are molecular chaperones, are highly conserved proteins produced by cells under physiological stress or pathological conditions. HSP60 (57-69 kDa) can promote or inhibit cell apoptosis through different mechanisms, and its abnormal expression is also related to tumour cell metastasis and drug resistance. In recent years, HSP60 has received increasing attention in the field of cancer research due to its potential as a diagnostic and prognostic biomarker or therapeutic target. However, in different types of cancer, the specific mechanisms of abnormally expressed HSP60 in tumour carcinogenesis and drug resistance are complicated and still require further study. In this article, we comprehensively review the regulative mechanisms of HSP60 on apoptosis, its applications as a cancer diagnostic biomarker and a therapeutic target, evidence of involvement in tumour resistance and the applications of exosomal HSP60 in liquid biopsy. By evaluating the current findings of HSP60 in cancer research, we highlight some core issues that need to be addressed for the use of HSP60 as a diagnostic or prognostic biomarker and therapeutic target in certain types of cancer.

The Triad Hsp60-miRNAs-Extracellular Vesicles in Brain Tumors: Assessing Its Components for Understanding Tumorigenesis and Monitoring Patients

Brain tumors have a poor prognosis and progress must be made for developing efficacious treatments, but for this to occur their biology and interaction with the host must be elucidated beyond current knowledge. What has been learned from other tumors may be applied to study brain tumors, for example, the role of Hsp60, miRNAs, and extracellular vesicles (EVs) in the mechanisms of cell proliferation and dissemination, and resistance to immune attack and anticancer drugs. It has been established that Hsp60 increases in cancer cells, in which it occurs not only in the mitochondria but also in the cytosol and plasma-cell membrane and it is released in EVs into the extracellular space and in circulation. There is evidence suggesting that these EVs interact with cells near and far from their original cell and that this interaction has an impact on the functions of the target cell. It is assumed that this crosstalk between cancer and host cells favors carcinogenesis in various ways. We, therefore, propose to study the triad Hsp60-related miRNAs-EVs in brain tumors and have standardized methods for the purpose. These revealed that EVs with Hsp60 and related miRNAs increase in patients’ blood in a manner that reflects disease status. The means are now available to monitor brain tumor patients by measuring the triad and to dissect its effects on target cells in vitro, and in experimental models in vivo.

MicroRNAs Involved in Inflammatory Breast Cancer: Oncogene and Tumor Suppressors with Possible Targets

Inflammatory breast cancer (IBC) as a rare and highly aggressive type of breast cancer displays phenotypic characteristics. To date, the IBC-associated molecular mechanisms are entirely unknown. In addition, there is an urgent need to identify the new biomarkers involved in the diagnosis and therapeutic purposes of IBC. MicroRNAs, a category of short noncoding RNAs, are capable of controlling the post-transcriptional expression of genes and thus can act as diagnostic predictive tools. In this review, we addressed the status of oncogenic and tumor suppressor miRNA-mediated IBC in current studies. Furthermore, based on their targets, their involvement in cancer progression, angiogenesis, metastasis, and apoptosis were determined.

Differential Expression Profile of miR-27b, miR-29a, and miR-155 in Chronic Lymphocytic Leukemia and Breast Cancer Patients

Over the past decade, studies on microRNA (miRNA) and cancer quickly became known. miRNAs are small non-coding RNAs that play a vital role in regulation of gene expression. In the present study, the expression of miR-27b, miR-29a, and miR-155, their prognostic roles, and their potential targets in chronic lymphocytic leukemia (CLL) and breast cancer (BC) by qRT-PCR were investigated. In two case-control studies, qRT-PCR was used to analyze the peripheral blood serum of 15 CLL patients and tissue samples of 15 BC patients for the expression of miR-27b, miR-29a, and miR-155. miRNA expression levels were calculated using the qRT-PCR method. The results revealed a significant increase in the expression of all miRNAs in patients with BC and CLL compared with respective healthy groups (p < 0.001). In BC patients, there was a significant difference between the expression of miR-155 and miR-29a (p < 0.05), miR-155 and miR-27b (p < 0.01), and miR-27b and miR-29a (p < 0.001). In CLL patients, a significant difference between expression of both miR-27b and miR-29a compared with expression of miR-155 (p < 0.001) was found. Furthermore, a significant association between miR-155 and prevascular invasion was found. Significantly, elevated circulating miRNAs were shown to be BC specific and could differentiate BC tissues from the controls. It was demonstrated that miRNAs used in this study and their expression profiles can be developed as biomarkers for early diagnosis and prognosis of CLL and BC. Further studies utilizing a larger test group of patients would provide identification of miRNAs as key players in intercellular interactions.

Assessment of the Diagnostic Potential of miR-29a-3p and miR-92a-3p as Circulatory Biomarkers in Acute Myeloid Leukemia

Background:

Acute myeloid leukemia (AML) is a set of Myeloproliferative neoplasms that are identified by excessive growth of myeloid blasts and production of abnormal blood cells. AML is the most common type of acute leukemia that occurs in adults. In addition, AML progresses rapidly and is considered a fatal disease. Thus, there is an urgent need to find new targets for molecularly designed therapies. In This study, we evaluated the circulatory levels of microRNA-29a-3p (miR-29a-3p) and miR-92a-3p beside exploring the expression pattern of their target gene myeloid cell leukemia sequence1 (MCL1) to investigate the role of these molecules in AML pathophysiology and to assess their ability to diagnose AML patients.

Methods:

40 adult AML patients along with 20 healthy subjects were enrolled in this study. Plasma were separated from venous blood samples, collected on EDTA, of all individuals were used to assess circulating miRNAs’ levels. In the meantime, total RNA was extracted from isolated leukocytes and was used to quantify target mRNA transcript levels.

Results:

Our data revealed that the circulating levels of miR-29a-3p and miR-92a-3p exhibited significant reduction in 90% and 100% of AML patients, respectively, when compared to the control group (p<0.001). On the other hand, the transcript level of the target gene of these miRNAs, MCL1, showed a sharp increase in 77.5% (p<0.001) of AML patients, along with a negative correlation with its regulatory miRNAs, miR-29a-3p and miR-92a-3p.

Conclusion:

Our data validates the negative regulatory role of miR-29a-3p and miR-92a-3p to the expression levels of MCL1 in peripheral blood and indicates that these miRNAs can be used as non-invasive diagnostic markers. Furthermore, our study highlights the therapeutic potential of miR-29a-3p and miR-92a-3p to target and downregulate a very important gene (MCL1), which is highly implicated in the pathogenesis of AML.

Epigenetic Alterations of Heat Shock Proteins (HSPs) in Cancer

Heat shock proteins (HSPs) are associated with various physiological processes (protein refolding and degradation) involved in the responses to cellular stress, such as cytotoxic agents, high temperature, and hypoxia. HSPs are overexpressed in cancer cells and play roles in their apoptosis, invasion, proliferation, angiogenesis, and metastasis. The regulation or translational modification of HSPs is recognized as a therapeutic target for the development of anticancer drugs. Among the regulatory processes associated with HSP expression, the epigenetic machinery (miRNAs, histone modification, and DNA methylation) has key functions in cancer. Moreover, various epigenetic modifiers of HSP expression have also been reported as therapeutic targets and diagnostic markers of cancer. Thus, in this review, we describe the epigenetic alterations of HSP expression in cancer cells and suggest that HSPs be clinically applied as diagnostic and therapeutic markers in cancer therapy via controlled epigenetic modifiers.

MicroRNA-27a downregulates the expression of Hsp90 and enhances the radiosensitivity in esophageal squamous cell carcinoma

Purpose

Accumulating evidence suggests that microRNAs (miRNAs) possess diverse cellular regulatory roles in radiation responses. In this study, we aimed to identify the role of miR-27a in esophageal squamous cell carcinoma (ESCC) radiosensitivity by exploring the relationship between miR-27a and heat shock protein 90 (Hsp90).

Materials and methods

We performed quantitative real-time polymerase chain reaction (qRT-PCR) to detect miR-27a expression in the plasma of ESCC patients and healthy volunteers. The expression of Hsp90 and its key client proteins associated with radioresistance were analyzed by Western blotting. Then, the effects of miR-27a on proliferation, apoptosis, cell cycle and radiosensitivity in ESCC cell lines were determined by CCK-8, flow cytometry, and clonogenic survival assay. We also generated subcutaneous tumors to explore whether miR-27a enhanced radiosensitivity in vivo.

Results

In our current study, we found that miR-27a expression was downregulated in the plasma of ESCC patients compared with that of healthy volunteers. Overexpression of miR-27a in ESCC cell lines caused a reduction of Hsp90 mRNA and protein. We also demonstrated that upregulation of miR-27a induced degradation of Hsp90 key client proteins associated with radioresistance. In related functional experiments, miR-27a significantly inhibited growth, increased radiation-induced apoptosis, induced cell cycle arrest in G₀/G₁ phase and enhanced ESCC radiosensitivity both in vitro and in vivo.

Conclusion

From these findings, we concluded that miR-27a may contribute to radiosensitivity by modulating Hsp90 expression. Moreover, miR-27a-based therapy utilized to target Hsp90 could be contemplated as a compelling alternative for sensitize ESCC to radiotherapy with fewer side effects.

Exosomal Chaperones and miRNAs in Gliomagenesis: State-of-Art and Theranostics Perspectives

Gliomas have poor prognosis no matter the treatment applied, remaining an unmet clinical need. As background for a substantial change in this situation, this review will focus on the following points: (i) the steady progress in establishing the role of molecular chaperones in carcinogenesis; (ii) the recent advances in the knowledge of miRNAs in regulating gene expression, including genes involved in carcinogenesis and genes encoding chaperones; and (iii) the findings about exosomes and their cargo released by tumor cells. We would like to trigger a discussion about the involvement of exosomal chaperones and miRNAs in gliomagenesis. Chaperones may be either targets for therapy, due to their tumor-promoting activity, or therapeutic agents, due to their antitumor growth activity. Thus, chaperones may well represent a Janus-faced approach against tumors. This review focuses on extracellular chaperones as part of exosomes' cargo, because of their potential as a new tool for the diagnosis and management of gliomas. Moreover, since exosomes transport chaperones and miRNAs (the latter possibly related to chaperone gene expression in the recipient cell), and probably deliver their cargo in the recipient cells, a new area of investigation is now open, which is bound to generate significant advances in the understanding and treatment of gliomas.

miR-29a regulated ER-positive breast cancer cell growth and invasion and is involved in the insulin signaling pathway

Increasing amounts of evidence show that insulin can activate different insulin signaling pathways to promote breast cancer growth and invasion. miR-29a plays crucial roles in decreasing glucose-stimulated insulin secretion, as well as in regulating breast cancer cell proliferation and EMT. However, the mechanism responsible for the regulatory effects of miR-29a on breast cancer growth and invasion and the relationship between these effects and insulin signaling remains unclear. Herein, we showed that human insulin increased miR-29a expression in ER-positive breast cancer cells and that miR-29a facilitated the ability of insulin to promote breast cancer cell proliferation and migration. We found that miR-29a-induced cell proliferation and metastasis acceleration occurred primarily through ERK phosphorylation. The IGF-1R is the upstream target gene of miR-29a, while CDC42 and p85α are the downstream target genes of miR-29a. These results have provided us with information regarding the molecular mechanisms by which hyperinsulinemia promotes breast cancer occurrence and development and thus leads to a poor prognosis in breast cancer patients and indicate that miR-29a plays an important role in breast cancer development and invasion.

Overexpression of miR-29a reduces the oncogenic properties of glioblastoma stem cells by downregulating Quaking gene isoform 6

Glioblastoma is the most common type of malignant primary brain tumor and has high recurrence and lethality rates. Glioblastoma stem cells (GSCs), a subpopulation of glioblastoma cells, may promote rapid tumor recurrence and therapy resistance. Because altered microRNA (miR) expression in GSCs may lead to glioblastoma progression, we assessed the effects of miR-29a expression on the oncogenic behavior of GSCs. MiR-29a expression was lower in GSCs than non-GSCs, and overexpression of miR-29a in GSCs inhibited cell proliferation, migration and invasion, but promoted apoptosis. MiR-29a directly inhibited the expression of Quaking gene isoform 6 (QKI-6) by binding to its 3'-UTR, and thus inhibited GSC malignant behavior. In addition, Wilms' tumor 1-associating protein (WTAP) was identified as a downstream target of QKI-6. Overexpression of miR-29a in GSCs inhibited expression of WTAP and suppressed both phosphoinositide 3-kinase/AKT and extracellular signal-related kinase pathways by downregulating QKI-6, thereby inhibiting cell proliferation, migration, and invasion but promoting apoptosis. We have characterized a novel miR-29a/QKI-6/WTAP axis in GSCs, which may provide theoretical support for the treatment of glioblastoma with miR-29a agomirs.

Inhibition of breast cancer metastasis by co-transfection of miR-31/193b-mimics

OBJECTIVES

Various studies have been conducted to reduce the metastatic behavior of cancerous cells. In this regard, ectopic expression of anti-metastatic microRNAs by miR-mimic and miR-restoration-based therapies could bring new insights to the field. In the present study, the consequences of co-transfecting breast cancer cell lines with miR-193b and miR-31 were investigated via invasion and migration assays.

MATERIALS AND METHODS

Double stranded oligonucleotide of mature miR-193b-3p and miR-31-5p were cloned into pcDNA 6.2gw/EmGFP plasmid. The resulting plasmids were used for transfection. Real time-PCR was performed to assess the expression of miR-193b and miR-31 as well as Ras homolog gene family member A (RhoA) and urokinase-type plasminogen activator (uPA) as miR targets. Scratch, Transwell migration and Matrigel invasion assays were carried out to assess the extent of migration and invasion of cell lines.

RESULTS

The most significant increase in expression of miRs belonged to the single transfection of mimic-miRs in MDA-MB231. Although the co-transfection was not as successful as single transfection in miR expression, it was significantly more effective in inhibition of the cells invasive potential.

CONCLUSION

Although the miR-restoration therapy based on co-transfection of two miRs could be less effective in expression of each miRNA, the resulting decrease in metastatic behavior of the cells is more significant due to collective effect of co-transfection to decrease target gene expression. Our results revealed that employing this sort of combinatorial strategies could lead to more efficient reduction in metastatic behavior. It seems that using this strategy would bring about more successful therapeutic outcomes.

The Role of MicroRNAs in Environmental Risk Factors, Noise-Induced Hearing Loss, and Mental Stress

SIGNIFICANCE

MicroRNAs (miRNAs) are important regulators of gene expression and define part of the epigenetic signature. Their influence on every realm of biomedicine is established and progressively increasing. The impact of environment on human health is enormous. Among environmental risk factors impinging on quality of life are those of chemical nature (toxic chemicals, heavy metals, pollutants, and pesticides) as well as those related to everyday life such as exposure to noise or mental and psychosocial stress. Recent Advances: This review elaborates on the relationship between miRNAs and these environmental risk factors.

CRITICAL ISSUES

The most relevant facts underlying the role of miRNAs in the response to these environmental stressors, including redox regulatory changes and oxidative stress, are highlighted and discussed. In the cases wherein miRNA mutations are relevant for this response, the pertinent literature is also reviewed.

FUTURE DIRECTIONS

We conclude that, even though in some cases important advances have been made regarding close correlations between specific miRNAs and biological responses to environmental risk factors, a need for prospective large-cohort studies is likely necessary to establish causative roles. Antioxid. Redox Signal. 28, 773-796.

MiR-29a: a potential therapeutic target and promising biomarker in tumors

MiRNAs, small non-coding RNA molecules, were recognized to be associated with the incidence and development of diverse neoplasms. MiRNAs were small non-coding RNAs that could regulate post-transcriptional level by binding to 3'-UTR of target mRNAs. Amongst which, miR-29a was demonstrated that it had significant impact on oncogenicity in various neoplasms through binding to critical genes which enhanced or inhibited the progression of cancers. MiR-29a participated in kinds of physiological and pathological processes, including virus replication, cell proliferation, differentiation, apoptosis, fibrosis, angiogenesis, tumorigenicity, metastasis, drug-resistance, and so on. According to its sufficient sensitivity and specificity, many studies showed that miR-29a might serve as a potential therapeutic target and promising biomarker in various tumors. In this review, we discussed the functions of miR-29a and its potential application in the diagnosis, treatment and stages of carcinoma, which could provide additional insight to develop a novel therapeutic strategy.

Knockdown of microRNA-29a regulates the expression of apoptosis-related genes in MCF-7 breast carcinoma cells

MicroRNA (miR), as non-coding small RNA, are key regulators of cancer-related biological cell processes and contribute to tumor growth through regulation of groups of pro- and anti-apoptotic genes. The present study aimed to investigate the effects of miR-29a on the expression of genes involved in apoptosis, including p21, B-cell lymphoma 2 (BCL-2), p53 and survivin. The MCF-7 breast cancer cell line was transfected with anti-miR-29a and treated with Taxol in subdivided treatment groups including: Scramble; anti-miR-29a; anti-miR-29a + Taxol; Taxol; and control. Expression levels of p21, BCL-2, p53 and survivin were evaluated using reverse transcription-quantitative polymerase chain reaction. miR-29a knockdown resulted in p21 and p53 upregulation and a decrease in survivin expression. These results indicated that miR-29a inhibition regulates apoptosis. The present data suggested that miR-29a inhibition may be a promising strategy for the induction of apoptosis of tumor cells.