Systematic analysis of gene expression pattern in has-miR-760 overexpressed resistance of the MCF-7 human breast cancer cell to doxorubicin

Riddling Substitution of "hsa" to "has" in the Enigmatic MicroRNA Nomenclature

This concise review and analysis offers an initial unpacking of a previously under-recognized issue within the microRNA research and communications field regarding the inadvertent use of "has" instead of "hsa" in article titles in the microRNA nomenclature. This subtle change, often the result of grammar auto correction tools, introduces considerable ambiguity and confusion among readers and researchers in reporting of microRNA-related discoveries. The impact of this issue cannot be underestimated, as precise and consistent nomenclature is vital for science communication and computational retrieval of relevant scientific literature and to advance science and innovation. We suggest that the recognition and correction of these often inadvertent "hsa" to "has" substitution errors are timely and important so as to ensure a higher level of accuracy throughout the writing and publication process in the microRNA field in particular. Doing so will also contribute to clarity and consistency in the field of microRNA research, ultimately improving scientific veracity, communication, and progress.

ABC transporters in breast cancer: their roles in multidrug resistance and beyond

ATP-binding cassette (ABC) transporters are membrane-spanning proteins involved in cholesterol homeostasis, transport of various molecules in and out of cells and organelles, oxidative stress, immune recognition, and drug efflux. They are long implicated in the development of multidrug resistance in cancer chemotherapy. Existing clinical and molecular evidence has also linked ABC transporters with cancer pathogenesis, prognostics, and therapy. In this review, we aim to provide a comprehensive update on all ABC transporters and their roles in drug resistance in breast cancer (BC). For solid tumours such as BC, various ABC transporters are highly expressed in less differentiated subtypes and metastases. ABCA1, ABCB1 and ABCG2 are key players in BC chemoresistance. Restraining these transporters has evolved as a possible mechanism to reverse this phenomenon. Further, ABCB1 and ABCC1 are important in BC prognosis. Newer therapeutic approaches have been developed to target all these molecules to dysregulate their effect, reduce cell viability, induce apoptosis, and increase drug sensitivity. In the future, targeted therapy for specific genetic variations and upstream or downstream molecules can help improve patient prognosis.

The Role of miRNAs in the Resistance of Anthracyclines in Breast Cancer: A Systematic Review

Breast cancer has been reported as the most common cancer in women globally, with 2.26 million new cases in 2020. While anthracyclines are the first-line drug for breast cancer, they cause a variety of adverse reactions and drug resistance, especially for triple-negative breast cancer, which can lead to poor prognosis, high relapse, and mortality rate. MicroRNAs (miRNAs) have been shown to be important in the initiation, development and metastasis of malignancies and their abnormal transcription levels may influence the efficacy of anthracyclines by participating in the pathologic mechanisms of breast cancer. Therefore, it is essential to understand the exact role of miRNAs in the treatment of breast cancer with anthracyclines. In this review, we outline the mechanisms and signaling pathways involved in miRNAs in the treatment of breast cancer using anthracyclines. The role of miRNA in the diagnosis, prognosis and treatment of breast cancer patients is discussed, along with the involvement of miRNAs in chemotherapy for breast cancer.

The Alterations and Potential Roles of MCMs in Breast Cancer

The minichromosome maintenance (MCM) protein family plays a key role in eukaryotic DNA replication and has been confirmed to be associated with the occurrence and progression of many tumors. However, the expression levels, functions, and prognostic values of MCMs in breast cancer (BC) have not been clearly and systematically explained. In this article, we studied the transcriptional levels of MCMs in BC based on the Oncomine database. Kaplan-Meier plotter was used to analyze prognostic value of MCMs in human BC patients. Furthermore, we constructed a MCM coexpression gene network and performed functional annotation analysis through DAVID to reveal the functions of MCMs and coexpressed genes. The data showed that the expression of MCM2–8 and MCM10 but not MCM1 and MCM9 was upregulated in BC. Kaplan-Meier plotter analysis revealed that high transcriptional levels of MCM2, MCM4–7, and MCM10 were significantly related to low relapse-free survival (RFS) in BC patients. In contrast, high levels of MCM1 and MCM9 predicted high RFS for BC patients. This study suggests that MCM2, MCM4–7, and MCM10 possess great potential to be valuable prognostic biomarkers for BC and that MCM1 and MCM9 may serve as potential treatment targets for BC patients.

The role of microRNAs on doxorubicin drug resistance in breast cancer

OBJECTIVES

Resistance to chemotherapeutic drugs is a serious challenge for effective therapy of cancers. Doxorubicin is a drug which is typically used for breast cancer treatment. Several mechanisms are involved in resistance to doxorubicin including overexpression of ATP-binding cassette (ABC) transporters, altering apoptosis, autophagy and cell cycle arrest. In this review, we focus on the potential effects of microRNAs on doxorubicin resistance in breast cancer.

METHODS

Literature review focusing on the 'microRNAs and doxorubicin drug resistance in breast cancer' was conducted comprehensively. The search was performed in PubMed, Scopus, Google and Google Scholar databases and reference lists of relevant articles were also included.

KEY FINDINGS

MicroRNAs play essential role in resistance of breast cancer to doxorubicin by affecting several key cellular pathways, including overexpression of ABC transporters, altering apoptosis, autophagy and cell signaling pathways, cell cycle arrest, epithelial to mesenchymal transition (EMT) and cancer stem cells (CSCs).

CONCLUSIONS

Cancer treatment methods are moving from conventional therapies to targeted therapies such as using microRNAs. MiRNAs can act as regulatory molecules to overcome breast cancer doxorubicin resistance by controlling the expression levels of genes involved in different cellular pathways. Thus, exact elucidation of their role in different cellular processes can help overcome the breast cancer development and drug resistance.

microRNAs targeting cellular cholesterol: implications for combating anticancer drug resistance

Over sixty percent of all mammalian protein-coding genes are estimated to be regulated by microRNAs (miRNAs), and unsurprisingly miRNA dysregulation has been linked with cancer. Aberrant miRNA expression in cancer cells has been linked with tumourigenesis and drug resistance. In the past decade, increasing number of studies have demonstrated that cholesterol accumulation fuels tumour growth and contributes to drug resistance, therefore, miRNAs controlling cholesterol metabolism and homeostasis are obvious hypothetical targets for investigating their role in cholesterol-mediated drug resistance in cancer. In this review, we have collated published evidences to consolidate this hypothesis and have scrutinized it by utilizing computational tools to explore the role of miRNAs in cholesterol-mediated drug resistance in breast cancer cells. We found that hsa-miR-128 and hsa-miR-223 regulate genes mediating lipid signalling and cholesterol metabolism, cancer drug resistance and breast cancer genes. The analysis demonstrates that targeting these miRNAs in cancer cells presents an opportunity for developing new strategies to combat anticancer drug resistance.

Association of miR-760 with cancer: An overview

MicroRNAs (miRNAs) are small non-coding RNA molecules of around 22 nucleotides in length. They are crucially involved in the post transcriptional regulation and thus play a significant role in the modulation of different diseases. Several studies have suggested that miRNA expression is dysregulated in various cancers through different mechanisms and the dysregulated miRNA in return affects different cancer hallmarks including cell proliferation, cell death suppression, metastasis and angiogenesis. Compilation of the available miRNA data can be a stimulator for proper understanding of the correlation between the miRNA expression and cancer progression. In this review, we have focussed on the role of miR-760 in the progression of different cancer. MicroRNA-760 (miR-760) has been found to be down regulated in various cancers, thus it can be utilized as a possible prognostic marker for cancer detection. Here, we have tried to fill a gap regarding the role of miR-760 in relation to cervical cancer also. Moreover, unravelling the role of miR-760 in different cancers will enlighten the researchers with proper understanding of biology of miR-760 in regulation of different cancers.

miR-760 exerts an antioncogenic effect in esophageal squamous cell carcinoma by negatively driving fat metabolism via targeting c-Myc

miR-760 is downregulated in various human tumors, and fat metabolism disorder correlates with tumor progression, especially anomalism of key fat metabolic enzymes that are positively modulated by c-Myc. The aim of our study is to elucidate the presumptive molecular mechanisms of miR-760-mediated esophageal squamous cell carcinoma (ESCC) cell function and to assess the therapeutic significance of miR-760 in ESCC patients. Quantitative real-time PCR (RT-qPCR) analysis indicated that miR-760 was significantly downexpressed in ESCC tissues and cell lines. Cell counting kit-8 (CCK-8) assay, colony formation assay, transwell assay, and flow cytometry denoted that induced ectopic overexpression of miR-760 dramatically inhibited ESCC cells proliferation, attenuated migration, and invasion facilitated apoptosis in vitro. Mechanistically, c-Myc predicted using bioinformatics was identified as a potential target gene of miR-760 by luciferase reporter assay. Furthermore, mRNA and protein expression levels of c-Myc and key fat metabolic enzymes were downregulated with miR-760 mimics. The above investigation results, responsible for the antineoplastic properties of miR-760 in ESCC, preliminarily highlighted that the hypothetical signal amongst miR-760, c-Myc, and key fat metabolic enzymes may develop a novel diagnostic marker, therapeutic target, and independent prognostic indicator.

The Stem Cell Phenotype of Aggressive Breast Cancer Cells

Aggressive cancer cells are characterized by their capacity to proliferate indefinitely and to propagate a heterogeneous tumor comprised of subpopulations with varying degrees of metastatic propensity and drug resistance properties. Particularly daunting is the challenge we face in the field of oncology of effectively targeting heterogeneous tumor cells expressing a variety of markers, especially those associated with a stem cell phenotype. This dilemma is especially relevant in breast cancer, where therapy is based on traditional classification schemes, including histological criteria, differentiation status, and classical receptor markers. However, not all patients respond in a similar manner to standard-of-care therapy, thereby necessitating the need to identify and evaluate novel biomarkers associated with the difficult-to-target stem cell phenotype and drug resistance. Findings related to the convergence of embryonic and tumorigenic signaling pathways have identified the embryonic morphogen Nodal as a promising new oncofetal target that is reactivated only in aggressive cancers, but not in normal tissues. The work presented in this paper confirms previous studies demonstrating the importance of Nodal as a cancer stem cell molecule associated with aggressive breast cancer, and advances the field by providing new findings showing that Nodal is not targeted by standard-of-care therapy in breast cancer patients. Most noteworthy is the linkage found between Nodal expression and the drug resistance marker ATP-binding cassette member 1 (ABCA1), which may provide new insights into developing combinatorial approaches to overcome drug resistance and disease recurrence.

Prognostic role of miR-760 in hepatocellular carcinoma

Previous studies have demonstrated that microRNA (miR)-760 serves an important role in various cancer types. However, to the best of our knowledge, its role in hepatocellular carcinoma (HCC) has not been fully elucidated. The current study investigated the prognostic role of miR-760 in HCC by using the Kaplan-Meier plotter database. The current data indicated that low expression of miR-760 was associated with higher overall survival (OS) for all patients with HCC from both the RNA-seq [hazard ratio (HR)=2.04; 95% confidence interval (CI)=1.44–2.89; P=4.9×10⁻⁵] and the non-commercial spotted microarray (HR=1.71; CI=1.05–2.76; P=0.028). In the RNA-seq platform, a lower expression of miR-760 was strongly associated with improved OS in male patients with HCC, but not in female patients with HCC. Additionally, low expression of miR-760 was associated with improved OS in patients with stage I, II and III HCC, and was associated with improved OS in Asian and Caucasian patients. The current results indicated that miR-760 serves as an oncogene for HCC and high expression of miR-760 is significantly associated with tumor progression and poor prognosis in patients with HCC.

Systematic analysis of hsa-miR-363 gene overexpression pattern in endometrial stromal cells

Endometriosis is a benign disease, but has invasion and metastasis characteristics similar to malignant tumors. Clinically, it is a difficult problem of gynecological clinical treatment for its high recurrence rate. It has been confirmed that miR-363 was downregulated in endometriosis tissues and miR-363 overexpression inhibited the invasion ability of endometrial stromal cells (ESCs). In order to explore the potential mechanism of miR-363-reduced ESC migration and invasion progression, we sought to demonstrate the targeted mRNA expression levels of miR-363 through microarray, and performed cluster analysis to identify potential functions of these targeted genes in ESCs. The wound migration assay showed that there was an observable trend of cell migration potential decrease after transfection with hsa-miR-363. The qRT-PCR result showed that compared to miR-363 negative control cell group, miR-363 was upregulated 3,264.58-fold after miR-363 lentiviral transfection in miR-363 mimics group. The microarray data showed that compared to ESCs miR-363 negative control cell group, 249 genes were upregulated in ESCs miR-363 mimics cells group, and 139 genes were downregulated. Gene Ontology analysis and the pathway analysis data demonstrated that these target genes are mainly involved in cell migration, cell adhesion and invasion, proliferation, apoptosis, alteration of endometrial cells and some related signaling pathways. Our study explored the gene expression pattern after miR-363 overexpression, which could expand the insights into the miR-363 function and molecular mechanisms in endometriosis.

The Network of Non-coding RNAs in Cancer Drug Resistance

Non-coding RNAs (ncRNAs) have been implicated in most cellular functions. The disruption of their function through somatic mutations, genomic imprinting, transcriptional and post-transcriptional regulation, plays an ever-increasing role in cancer development. ncRNAs, including notorious microRNAs, have been thus proposed to function as tumor suppressors or oncogenes, often in a context-dependent fashion. In parallel, ncRNAs with altered expression in cancer have been reported to exert a key role in determining drug sensitivity or restoring drug responsiveness in resistant cells. Acquisition of resistance to anti-cancer drugs is a major hindrance to effective chemotherapy and is one of the most important causes of relapse and mortality in cancer patients. For these reasons, non-coding RNAs have become recent focuses as prognostic agents and modifiers of chemo-sensitivity. This review starts with a brief outline of the role of most studied non-coding RNAs in cancer and then highlights the modulation of cancer drug resistance via known ncRNAs based mechanisms. We identified from literature 388 ncRNA-drugs interactions and analyzed them using an unsupervised approach. Essentially, we performed a network analysis of the non-coding RNAs with direct relations with cancer drugs. Within such a machine-learning framework we detected the most representative ncRNAs-drug associations and groups. We finally discussed the higher integration of the drug-ncRNA clusters with the goal of disentangling effectors from downstream effects and further clarify the involvement of ncRNAs in the cellular mechanisms underlying resistance to cancer treatments.

Analysis of change in microRNA expression profiles of lung cancer A549 cells treated with Radix tetrastigma hemsleyani flavonoids

Background

The aim of this study was to determine the inhibition effects of Radix tetrastigma hemsleyani (RTH) flavonoids on human lung adenocarcinoma A549 cells and the underlying molecular mechanism. RTH is an important Chinese traditional herb that has been widely used in cancer therapy. As an important type of active substance, RTH flavones (RTHF) have been shown to have good antiproliferative effects on various cancer cells. MicroRNAs (miRNAs) are small, noncoding RNA molecules that play important roles in cancer progression and prevention. However, the miRNA profile of RTHF-treated A549 cells has not yet been studied.

Materials and methods

The miRNA expression profile changes of A549 cell treated with RTHF were determined using the miRNA-seq analysis. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of differentially expressed miRNAs' (DE-miRNAs) target genes were carried out.

Results

In this study, we identified 162 miRNAs that displayed expression changes >1.2-fold in RTHF-treated A549 cells. GO analysis results showed that target genes of DE-miRNAs were significantly enriched in protein binding, binding, cell, cell part, intracellular, cellular process, single-organism process, and single-organism cellular process. Pathway analysis illustrated that target genes of DE-miRNAs are mainly involved in endocytosis, axon guidance, lysosome, melanogenesis, and acute myeloid leukemia pathway.

Conclusion

These results may assist in the better understanding of the anticancer effects of RTHF in A549 cells.

MicroRNA-760 Inhibits Doxorubicin Resistance in Hepatocellular Carcinoma through Regulating Notch1/Hes1-PTEN/Akt Signaling Pathway

Accumulating studies have suggested that microRNA-760 (miR-760) plays an important role in chemoresistance of various cancer cells. However, whether miR-760 regulates the chemoresistance of hepatocellular carcinoma (HCC) remains unclear. In this study, we found that miR-760 was decreased in HCC cell lines, and doxorubicin (Dox) treatment significantly decreased miR-760 expression in HCC cells. Overexpression of miR-760 sensitized HCC cells to Dox-induced cytotoxicity and apoptosis, whereas miR-760 inhibition showed the opposite effects. Notch1 was predicted as a target gene of miR-760. miR-760 negatively regulated Notch1 expression and Notch1/Hes1 signaling. Overexpression of miR-760 increased PTEN expression and decreased the phosphorylation of Akt. Activation of Notch signaling significantly reversed the inhibitory effect of miR-760 on Dox-resistance and abrogated the effect of miR-760 on the PTEN/Akt signaling pathway in HCC cells. Overall, our results demonstrate that miR-760 inhibits Dox-resistance in HCC cells through inhibiting Notch1 and promoting PTEN expression.

MiR-760 suppresses non-small cell lung cancer proliferation and metastasis by targeting ROS1

MicroRNAs (miRNAs) have been shown to be critical regulators in many types of tumors. The aim of our study was to investigate the role of miR-760 in non-small cell lung cancer (NSCLC). We demonstrated that the expression of miR-760 was downregulated in NSCLC tissues compared with the adjacent normal tissues. We also demonstrated that the expression of miR-760 was downregulated in the NSCLC cell lines. Overexpression of miR-760 suppressed the NSCLC cell proliferation, cell cycle, and migration. Moreover, we identified that ROS1 was a direct target of miR-760 in the NSCLC cell. Elevated expression of miR-760 suppressed ROS1 expression in the NSCLC cell. We also demonstrated that the expression of ROS1 was higher in the NSCLC tissues than in the adjacent lung tissues. MiR-760 expression level was reversely associated with the expression level of ROS1 in the NSCLC tissues. In summary, we showed that miR-760 suppressed the NSCLC cell proliferation, cell cycle, and migration through regulating the ROS1 expression. These data suggested that miR-760 may act as a tumor suppressor gene in the NSCLC partly through regulating ROS1 expression.

MicroRNA‑760 inhibits cell proliferation and invasion of colorectal cancer by targeting the SP1‑mediated PTEN/AKT signalling pathway

Colorectal cancer (CRC), one of the most commonly diagnosed types of cancer worldwide, is the third most prevalent and fourth most frequent cause of cancer‑related mortality. Dysregulated microRNAs (miRNAs) have potential regulatory roles in the development and progression of various cancer types. Therefore, the investigation of the miRNAs involved in CRC formation and progression may lead to the development of highly effective therapeutic strategies for CRC. In the present study, miRNA‑760 (miR‑760) was frequently downregulated in CRC tissues and cell lines. The low levels of miR‑760 expression were significantly correlated with the tumor size, lymph node metastasis and TNM stage of CRC. Functional assays revealed that restoring miR‑760 expression inhibited CRC cell proliferation and invasion in vitro. The results of bioinformatics analysis, luciferase reporter assay, reverse transcription‑quantitative polymerase chain reaction and western blot analysis suggested that specificity protein 1 (SP1) is a direct target of miR‑760 in CRC. The high expression of SP1 in CRC tissues was inversely correlated with the expression of miR‑760. Rescue experiments demonstrated that enforced SP1 expression rescued the tumor‑suppressing effects of miR‑760 on CRC cell proliferation and invasion. In addition, miR‑760 overexpression is involved in the regulation of the PTEN/AKT signalling pathway. Collectively, the present data demonstrated that miR‑760 directly targets SP1 to inactivate the PTEN/AKT signalling pathway, thus implicating miR‑760 in the regulation of CRC cell proliferation and invasion. Therefore, miR‑760 may be a novel biomarker and therapeutic target for CRC.

Potential genetic damage to nematode offspring following exposure to triclosan during pregnancy

Triclosan (TCS) is widely used as broad-spectrum antibacterial agent. However, it may threaten the health of human offspring if the mother is exposed to TCS during pregnancy. The present study aimed to identify potential mechanisms behind the toxic effect of TCS on the offspring of Caenorhabditis elegans (C. elegans), using this nematode as a suitable animal model. The results of the current study demonstrated that the locomotory behavior and reproductive capacity of C. elegans offspring was severely affected by prenatal exposure to different concentrations of TCS. A high-throughput gene microarray was performed to investigate molecular alterations in C. elegans offspring following TCS exposure during pregnancy. Microarray results indicated that 113 genes were differentially expressed following TCS treatment compared with the control group. Gene ontology analysis demonstrated that these dysregulated genes were primarily associated with neuron development, muscular strength and reproduction. Pathway analysis results demonstrated that differentially expressed genes participated in several signaling pathways, including arginine, proline, and purine metabolism, progesterone-mediated oocyte maturation and neuroactive ligand-receptor interaction. Finally, 7 TCS toxicity-associated genes were confirmed by reverse transcription-quantitative polymerase chain reaction. The present study indicates that TCS exposure during pregnancy may disturb the locomotory behavior and reproductive capacity of C. elegans offspring, primarily through 7 TCS toxicity-associated genes, which merits further study from an environmental health perspective.

Micro-RNAs as Potential Predictors of Response to Breast Cancer Systemic Therapy: Future Clinical Implications

Despite advances in diagnosis and new treatments such as targeted therapies, breast cancer (BC) is still the most prevalent tumor in women worldwide and the leading cause of death. The principal obstacle for successful BC treatment is the acquired or de novo resistance of the tumors to the systemic therapy (chemotherapy, endocrine, and targeted therapies) that patients receive. In the era of personalized treatment, several studies have focused on the search for biomarkers capable of predicting the response to this therapy; microRNAs (miRNAs) stand out among these markers due to their broad spectrum or potential clinical applications. miRNAs are conserved small non-coding RNAs that act as negative regulators of gene expression playing an important role in several cellular processes, such as cell proliferation, autophagy, genomic stability, and apoptosis. We reviewed recent data that describe the role of miRNAs as potential predictors of response to systemic treatments in BC. Furthermore, upon analyzing the collected published information, we noticed that the overexpression of miR-155, miR-222, miR-125b, and miR-21 predicts the resistance to the most common systemic treatments; nonetheless, the function of these particular miRNAs must be carefully studied and further analyses are still necessary to increase knowledge about their role and future potential clinical uses in BC.

Influence of microRNAs and Long Non-Coding RNAs in Cancer Chemoresistance

Innate and acquired chemoresistance exhibited by most tumours exposed to conventional chemotherapeutic agents account for the majority of relapse cases in cancer patients. Such chemoresistance phenotypes are of a multi-factorial nature from multiple key molecular players. The discovery of the RNA interference pathway in 1998 and the widespread gene regulatory influences exerted by microRNAs (miRNAs) and other non-coding RNAs have certainly expanded the level of intricacy present for the development of any single physiological phenotype, including cancer chemoresistance. This review article focuses on the latest research efforts in identifying and validating specific key molecular players from the two main families of non-coding RNAs, namely miRNAs and long non-coding RNAs (lncRNAs), having direct or indirect influences in the development of cancer drug resistance properties and how such knowledge can be utilised for novel theranostics in oncology.

MiR-760 overexpression promotes proliferation in ovarian cancer by downregulation of PHLPP2 expression

OBJECTIVE

Ovarian cancer is one of the most lethal gynecologic malignancies worldwide and with poor prognosis and survival rate in women. Identifying sensitive and specific molecular in carcinogenesis may improve diagnostic and therapeutic strategies for this malignancy and achieve a better clinical outcome.

METHODS

miR-760 expression in ovarian cancer cell lines and patient tissues were determined using Real-time PCR. 145 human ovarian cancer tissue samples were analyzed by RT-PCR to investigate the association between miR-760expression and the clinicopathological characteristics of ovarian cancer patients. Functional assays, such as MTT, anchorage-independent growth, colony formation and BRDU assay were used to determine the oncogenic role of miR-760 in human ovarian cancer progression. Furthermore, western blotting and luciferase assay were used to determine the mechanism of miR-760 promotes proliferation in ovarian cancer cells.

RESULT

The expression of miR-760 was markedly upregulated in ovarian cancer cell lines and tissues, and high miR-760 expression was associated with an aggressive phenotype and poor prognosis with ovarian cancer patients. Upregulation of miR-760 promoted, whereas downregulation of miR-760 inhibited the proliferation of ovarian cancer cells in vitro. Additionally, we identified PHLPP2 as a direct target of miR-760, and silencing the expression of PHLPP2 is the essential biological function of miR-760 during ovarian cancer cell proliferation. Finally, we showed a significant correlation between miR-760 and PHLPP2 expression in ovarian cancer tissues.

CONCLUSION

Our findings suggest that miR-760 represents a potential onco-miR and participates in ovarian cancer carcinogenesis, which highlight its potential as a target for ovarian cancer therapy.

MicroR-760 suppresses cancer stem cell subpopulation and breast cancer cell proliferation and metastasis: By down-regulating NANOG

BACKGROUND AND OBJECTIVE

Emerging evidences suggest that cancer stem cells are responsible for tumor aggressive, metastasis and therapeutic resistance. To data, the mechanism underlying breast cancer stem cell (BCSC) population within tumor metastasis remains to be fully elucidated. The current study was to investigate the potential role of microRNA-760 (miR-760) and its associated target gene in population and metastasis of BCSC.

METHODS

Characteristic BCSCs surface markers (CD44(+)/CD24(-/low)) were determined by flow cytometry in breast cancer MCF-7 and BT-549 cells. Quantitative RT-PCR was used to evaluate miR-760 and NANOG mRNA expression. Expression of NANOG protein was determined using western blot. Cell proliferation was determined by MTT assay. The model of breast cancer cell xenograft was used to evaluate the effect of miR-760 on tumor growth.

RESULTS

BT-549 cell has substantially more CD44(+)/CD24(-/low) subpopulation than MCF-7 cell. Moreover, BT-549 cell expressed lower level of miR-760 and higher level of NANOG than MCF-7cell. By result from cellular miR-760 modulation, we found that miR-760 overexpression suppressed CD44(+)/CD24(-/low) population as well as inhibited cell proliferation and migration of BT-549. On the contrary, knockdown of miR-760 promoted CD44(+)/CD24(-/low) population and migration of MCF-7 cells. By luciferase reporter assay, miR-760 was proved to be functional associated with NANOG via regulating its expression. This functional interaction was showed to be involved in controlling proliferation and migration of MCF-7 and BT-549 cell.

CONCLUSION

These data suggest that the target of miR-760/NANOG axis may represent a new therapeutic approach to suppress breast cancer stem cell subpopulation thereby prevent cancer metastasis.

Mechanisms of doxorubicin resistance in hepatocellular carcinoma

Hepatocellular carcinoma, one of the most common solid tumors worldwide, is poorly responsive to available chemotherapeutic approaches. While systemic chemotherapy is of limited benefit, intra-arterial delivery of doxorubicin to the tumor frequently produces tumor shrinkage. Its utility is limited, in part, by the frequent emergence of doxorubicin resistance. The mechanisms of this resistance include increased expression of multidrug resistance efflux pumps, alterations of the drug target, topoisomerase, and modulation of programmed cell death pathways. Many of these effects result from changes in miRNA expression and are particularly prominent in tumor cells with a stem cell phenotype. This review will summarize the current knowledge on the mechanisms of doxorubicin resistance of hepatocellular carcinoma and the potential for approaches toward therapeutic chemosensitization.