miR-141 confers docetaxel chemoresistance of breast cancer cells via regulation of EIF4E expression

Lau AT, Xu YM. The regulation of microRNAs on chemoresistance in triple-negative breast cancer: a recent update

Triple-negative breast cancer (TNBC) has negative expressions of ER, PR and HER2. Due to the insensitivity to both endocrine therapy and HER2-targeted therapy, the main treatment method for TNBC is cytotoxic chemotherapy. However, the curative effect of chemotherapy is limited because of the existence of acquired or intrinsic multidrug resistance. MicroRNAs (miRNAs) are frequently dysregulated in malignant tumors and involved in tumor occurrence and progression. Interestingly, growing studies show that miRNAs are involved in chemoresistance in TNBC. Thus, targeting dysregulated miRNAs could be a plausible way for better treatment of TNBC. Here, we present the updated knowledge of miRNAs associated with chemoresistance in TNBC, which may be helpful for the early diagnosis, prognosis and treatment of this life-threatening disease.

Deregulated miRNA Expression in Triple-Negative Breast Cancer of Ancestral Genomic-Characterized Latina Patients

Among patients with triple-negative breast cancer (TNBC), several studies have suggested that deregulated microRNA (miRNA) expression may be associated with a more aggressive phenotype. Although tumor molecular signatures may be race- and/or ethnicity-specific, there is limited information on the molecular profiles in women with TNBC of Hispanic and Latin American ancestry. We simultaneously profiled TNBC biopsies for the genome-wide copy number and miRNA global expression from 28 Latina women and identified a panel of 28 miRNAs associated with copy number alterations (CNAs). Four selected miRNAs (miR-141-3p, miR-150-5p, miR-182-5p, and miR-661) were validated in a subset of tumor and adjacent non-tumor tissue samples, with miR-182-5p being the most discriminatory among tissue groups (AUC value > 0.8). MiR-141-3p up-regulation was associated with increased cancer recurrence; miR-661 down-regulation with larger tumor size; and down-regulation of miR-150-5p with larger tumor size, high p53 expression, increased cancer recurrence, presence of distant metastasis, and deceased status. This study reinforces the importance of integration analysis of CNAs and miRNAs in TNBC, allowing for the identification of interactions among molecular mechanisms. Additionally, this study emphasizes the significance of considering the patients ancestral background when examining TNBC, as it can influence the relationship between intrinsic tumor molecular characteristics and clinical manifestations of the disease.

Breast cancer: miRNAs monitoring chemoresistance and systemic therapy

With a high mortality rate that accounts for millions of cancer-related deaths each year, breast cancer is the second most common malignancy in women. Chemotherapy has significant potential in the prevention and spreading of breast cancer; however, drug resistance often hinders therapy in breast cancer patients. The identification and the use of novel molecular biomarkers, which can predict response to chemotherapy, might lead to tailoring breast cancer treatment. In this context, accumulating research has reported microRNAs (miRNAs) as potential biomarkers for early cancer detection, and are conducive to designing a more specific treatment plan by helping analyze drug resistance and sensitivity in breast cancer treatment. In this review, miRNAs are discussed in two alternative ways-as tumor suppressors to be used in miRNA replacement therapy to reduce oncogenesis and as oncomirs to lessen the translation of the target miRNA. Different miRNAs like miR-638, miR-17, miR-20b, miR-342, miR-484, miR-21, miR-24, miR-27, miR-23 and miR-200 are involved in the regulation of chemoresistance through diverse genetic targets. For instance, tumor-suppressing miRNAs like miR-342, miR-16, miR-214, and miR-128 and tumor-promoting miRNAs like miR101 and miR-106-25 cluster regulate the cell cycle, apoptosis, epithelial to mesenchymal transition and other pathways to impart breast cancer drug resistance. Hence, in this review, we have discussed the significance of miRNA biomarkers that could assist in providing novel therapeutic targets to overcome potential chemotherapy resistance to systemic therapy and further facilitate the design of tailored therapy for enhanced efficacy against breast cancer.

Expression of eIF4E Gene in Glioma and Its Sensitivity to Oxidative Stress

Objective

Increased expression of eIF4E has been observed in various cancers, which makes eIF4E an attractive target of anticancer drugs. This study mainly discussed eIF4E gene expression in glioma and its sensitivity to oxidative stress (OS).

Methods

Relevant data from The Cancer Genome Atlas (TCGA) database regarding eIF4E gene expression and its prognostic significance in glioma samples were analyzed. Additionally, we measured eIF4E at mRNA and protein levels in clinical samples collected between July 2019 and September 2021, as well as glioma cell strains. U251 cells cultured in vitro were treated with OS injury induced by hydrogen peroxide (H₂O₂) and then transfected with si-eIF4E to determine changes in cell multiplication, invasiveness, and migration capacities as well as apoptosis rate. ELISA quantified cell malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) concentrations, and flow cytometry measured reactive oxygen species (ROS) level.

Results

In glioma samples from the TCGA database, eIF4E showed obviously elevated levels in LGG and GBM patients, which was usually associated with adverse patient prognosis (P < 0.05). eIF4E was also upregulated in glioma cell strains than in HBE cells. In comparison with the blank control group, transfection of si-eIF4E statistically suppressed the capacity of U251 cells to proliferate, invade and migrate, and enhance apoptosis rate, while reducing SOD and GSH-Px and increasing MDA and ROS. In addition, H₂O₂ induced the upregulation of eIF4E in U251 cells. H₂O₂ + si-eIF4E exhibited reduced multiplication and number of clone cell formation, invasion, and migration of U251 cells, as well as increased apoptosis rate than H₂O₂ + si-NC group.

Conclusions

eIF4E is highly expressed in glioma. Knocking down eIF4E can effectively inhibit the capacity of U251 to proliferate, invade and migrate, and significantly increase apoptosis. In addition, eIF4E knock-down is able to lower OS reaction under H₂O₂ inducement and enhance U251 cells' sensitivity to OS.

The role of miR-200 family in the regulation of hallmarks of cancer

MiRNAs are short non-coding RNAs that regulate gene expression post-transcriptionally contributing to the development of different diseases including cancer. The miR-200 family consists of five members, miR-200a, miR-200b, miR-200c, miR-141, and miR-429. Their expression is dysregulated in cancer tissue and their level is altered in the body fluids of cancer patients. Moreover, the levels of miR-200 family members correlate with clinical parameters such as cancer patients' survival which makes them potentially useful as diagnostic and prognostic biomarkers. MiRNAs can act as either oncomiRs or tumor suppressor miRNAs depending on the target genes and their role in the regulation of key oncogenic signaling pathways. In most types of cancer, the miR-200 family acts as tumor suppressor miRNA and regulates all features of cancer. In this review, we summarized the expression pattern of the miR-200 family in different types of cancer and their potential utility as biomarkers. Moreover, we comprehensively described the role of miR-200 family members in the regulation of all hallmarks of cancer proposed by Hanahan and Weinberg with the focus on the epithelial-mesenchymal transition, invasiveness, and metastasis of tumor cells.

Translation initiation and its relationship with metabolic mechanisms in cancer development, progression and chemoresistance

Pathways that regulate protein homeostasis (proteostasis) in cells range from mRNA processing to protein degradation; perturbations in regulatory mechanisms of these pathways can lead to oncogenic cellular processes. Protein synthesis modulation failures are common phenomena in cancer cells, wherein specific conditions that promote the translation of protein factors promoting carcinogenesis are present. These specific conditions may be favored by metabolic lipid alterations like those found in metabolic syndrome and obesity. Protein translation modifications have been described in obesity, favoring the translation of protein targets that benefit lipid accumulation; a determining factor is the activity of the cap-binding eukaryotic translation initiation factor 4E (eIF4E), a crosstalk in protein translation and lipogenesis. Besides, alterations of protein translation initiation steps are critical participants for the development of both pathogenic conditions, cancer, and obesity. This chapter is focused on the regulation of recognition and processing of carcinogenic-mRNA and the connections among lipid metabolism and cell signaling pathways that promote oncogenesis, tumoral microenvironment generation and potentially the development of chemoresistance. We performed an in-depth analysis of events, such as those occurring in obesity and dyslipidemias, that may influence protein translation, driving the recognition of certain mRNAs and favoring cancer development and chemoresistance.

Relationship of micro-RNA, mRNA and eIF Expression in Tamoxifen-Adapted MCF-7 Breast Cancer Cells: Impact of miR-1972 on Gene Expression, Proliferation and Migration

Background: Tamoxifen-adapted MCF-7-Tam cells represent an in-vitro model for acquired tamoxifen resistance, which is still a problem in clinics. We here investigated the correlation of microRNA-, mRNA- and eukaryotic initiation factors (eIFs) expression in this model. Methods: MicroRNA- and gene expression were analyzed by nCounter and qRT-PCR technology; eIFs by Western blotting. Protein translation mode was determined using a reporter gene assay. Cells were transfected with a miR-1972-mimic. Results: miR-181b-5p,-3p and miR-455-5p were up-, miR-375, and miR-1972 down-regulated and are significant in survival analysis. About 5% of the predicted target genes were significantly altered. Pathway enrichment analysis suggested a contribution of the FoxO1 pathway. The ratio of polio-IRES driven to cap-dependent protein translation shifted towards cap-dependent initiation. Protein expression of eIF2A, -4G, -4H and -6 decreased, whereas eIF3H was higher in MCF-7-Tam. Significant correlations between tamoxifen-regulated miRNAs and eIFs were found in representative breast cancer cell lines. Transfection with a miR-1972-mimic reverses tamoxifen-induced expression for a subset of genes and increased proliferation in MCF-7, but reduced proliferation in MCF-7-Tam, especially in the presence of 4OH-tamoxifen. Migration was inhibited in MCF-7-Tam cells. Translation mode remained unaffected. Conclusions: miR-1972 contributes to the orchestration of gene-expression and physiological consequences of tamoxifen adaption.

Functional mechanism and clinical implications of miR-141 in human cancers

Cancer is caused by the abnormal proliferation of local tissue cells under the control of many oncogenic factors. MicroRNAs (miRNAs) are a class of evolutionarily conserved, approximately 22-nucleotide noncoding small RNAs that influence transcriptional regulationby binding to the 3'-untranslated region of target messenger RNA. As a member of the miRNA family, miR-141 acts as a suppressor or an oncomiR in various cancers and regulates cancer cell proliferation, apoptosis, invasion, and metastasis through a variety of signaling pathways, such as phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) and constitutive activation of nuclear factor-κB (NF-κB). Target gene validation and pathway analysis have provided mechanistic insight into the role of this miRNA in different tissues. This review also outlines novel findings that suggest miR-141 may be useful as a noninvasive biomarker and as a therapeutic target in several cancers.

Overexpression of microRNA-145 enhanced docetaxel sensitivity in breast cancer cells via inactivation of protein kinase B gamma-mediated phosphoinositide 3-kinase -protein kinase B pathway

Chemoresistance is a major challenge for the treatment of breast cancer (BC). Previous studies showed that miR-145 level decreases in chemoresistant BC tissues. Nevertheless, the biological function of miR-145 on docetaxel resistance of BC cells remains unclear, which is what our research attempted to clarify. RT-qPCR analyzed miR-145 level, and cell viability and colony formation assays assessed the impact of miR-145 on docetaxel resistance. Molecular mechanisms of miR-145-mediated docetaxel sensitivity were examined by Luciferase reporter assay and Western Blot assessed the function of AKT3 and PI3K/AKT signaling. Our research found that miR-145 expression presented significant downregulation in docetaxel-resistant BC cells. Meanwhile, miR-145 overexpression facilitated the docetaxel sensitivity of BC cells in vivo and in vitro, while the miR-145 inhibitor decreased the sensitivity of BC cells to docetaxel. We also observed that miR-145 inhibited docetaxel resistance mainly via downregulation of the AKT3 expression and further inhibited PI3K/AKT pathway. To conclude, this research provides a novel strategy for improving chemosensitivity through the newly identified miR-145-AKT3/PI3K-AKT signaling pathway in BC.

Crosstalk between non-coding RNAs expression profile, drug resistance and immune response in breast cancer

Drug resistance is one of the most critical challenges facing researchers in treating breast cancer. Despite numerous treatments for breast cancer, including conventional chemical drugs, monoclonal antibodies, and immunotherapeutic drugs known as immune checkpoint inhibitors (ICI), many patients resist various approaches. In recent years, the relationship between gene expression profiles and drug resistance phenotypes has attracted much attention. Non-coding RNAs (ncRNAs) are regulatory molecules that have been shown to regulate gene expression and cell transcriptome. Two categories, microRNAs and long non-coding RNAs have been more considered and studied among these ncRNAs. Studying the role of different ncRNAs in chemical drug resistance and ICI resistance together can be beneficial in selecting more effective treatments for breast cancer. Changing the expression and action mechanism of these regulatory molecules on drug resistance phenotypes is the main topic of this review article.

The Role of Non-Coding RNAs in Breast Cancer Drug Resistance

Breast cancer (BC) is one of the commonly occurring malignancies in females worldwide. Despite significant advances in therapeutics, the mortality and morbidity of BC still lead to low survival and poor prognosis due to the drug resistance. There are certain chemotherapeutic, endocrine, and target medicines often used for BC patients, including anthracyclines, taxanes, docetaxel, cisplatin, and fluorouracil. The drug resistance mechanisms of these medicines are complicated and have not been fully elucidated. It was reported that non-coding RNAs (ncRNAs), such as micro RNAs (miRNA), long-chain non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) performed key roles in regulating tumor development and mediating therapy resistance. However, the mechanism of these ncRNAs in BC chemotherapeutic, endocrine, and targeted drug resistance was different. This review aims to reveal the mechanism and potential functions of ncRNAs in BC drug resistance and to highlight the ncRNAs as a novel target for achieving improved treatment outcomes for BC patients.

New Insight into the Effects of Metformin on Diabetic Retinopathy, Aging and Cancer: Nonapoptotic Cell Death, Immunosuppression, and Effects beyond the AMPK Pathway

Under metabolic stress conditions such as hypoxia and glucose deprivation, an increase in the AMP:ATP ratio activates the AMP-activated protein kinase (AMPK) pathway, resulting in the modulation of cellular metabolism. Metformin, which is widely prescribed for type 2 diabetes mellitus (T2DM) patients, regulates blood sugar by inhibiting hepatic gluconeogenesis and promoting insulin sensitivity to facilitate glucose uptake by cells. At the molecular level, the most well-known mechanism of metformin-mediated cytoprotection is AMPK pathway activation, which modulates metabolism and protects cells from degradation or pathogenic changes, such as those related to aging and diabetic retinopathy (DR). Recently, it has been revealed that metformin acts via AMPK- and non-AMPK-mediated pathways to exert effects beyond those related to diabetes treatment that might prevent aging and ameliorate DR. This review focuses on new insights into the anticancer effects of metformin and its potential modulation of several novel types of nonapoptotic cell death, including ferroptosis, pyroptosis, and necroptosis. In addition, the antimetastatic and immunosuppressive effects of metformin and its hypothesized mechanism are also discussed, highlighting promising cancer prevention strategies for the future.

MicroRNAs involved in drug resistance of breast cancer by regulating autophagy

Autophagy is a conserved catabolic process characterized by degradation and recycling of cytosolic components or organelles through a lysosome-dependent pathway. It has a complex and close relationship to drug resistance in breast cancer. MicroRNAs (miRNAs) are small noncoding molecules that can influence numerous cellular processes including autophagy, through the posttranscriptional regulation of gene expression. Autophagy is regulated by many proteins and pathways, some of which in turn have been found to be regulated by miRNAs. These miRNAs may affect the drug resistance of breast cancer. Drug resistance is the main cause of distant recurrence, metastasis and death in breast cancer patients. In this review, we summarize the causative relationship between autophagy and drug resistance of breast cancer. The roles of autophagy-related proteins and pathways and their associated miRNAs in drug resistance of breast cancer are also discussed.

Breast Cancer Response to Therapy: Can microRNAs Lead the Way?

Breast cancer (BC) is a leading cause of death among women with malignant diseases. The selection of adequate therapies for highly invasive and metastatic BCs still represents a major challenge. Novel combinatorial therapeutic approaches are urgently required to enhance the efficiency of BC treatment. Recently, microRNAs (miRNAs) emerged as key regulators of the complex mechanisms that govern BC therapeutic resistance and susceptibility. In the present review we aim to critically examine how miRNAs influence BC response to therapies, or how to use miRNAs as a basis for new therapeutic approaches. We summarized recent findings in this rapidly evolving field, emphasizing the challenges still ahead for the successful implementation of miRNAs into BC treatment while providing insights for future BC management.The goal of this review was to propose miRNAs, that might simultaneously improve the efficacy of all four therapies that are the backbone of current BC management (radio-, chemo-, targeted, and hormone therapy). Among the described miRNAs, miR-21 and miR-16 emerged as the most promising, closely followed by miR-205, miR-451, miR-182, and miRNAs from the let-7 family. miR-21 inhibition might be the best choice for future improvement of invasive BC treatment.New therapeutic strategies of miRNA-based agents alongside current standard treatment modalities could greatly benefit BC patients. This review represents a guideline on how to navigate this elaborate puzzle.

Long non-coding RNA NEAT1 transported by extracellular vesicles contributes to breast cancer development by sponging microRNA-141-3p and regulating KLF12

Objective

Breast cancer (BC) remains a public-health issue on a global scale. Long non-coding RNAs (lncRNAs) play functional roles in BC. This study focuses on effects of NEAT1 on BC cell invasion, migration and chemotherapy resistance via microRNA (miR)-141-3p and KLF12.

Methods

After extraction and identification of serum extracellular vesicles (EVs), NEAT1 expression in EVs was detected and its association with clinical characteristics of BC patients was analyzed. Besides, the gain-of function was performed to investigate the roles of NEAT1 and miR-141-3p in BC, and levels of NEAT1, miR-141-3p, KLF12 and MDR1 after EV treatment were detected by RT-qPCR and Western blot analysis. Furthermore, the in vitro findings were confirmed via lung metastases in nude mice.

Results

NEAT1 expression in serum EVs was high and related to lymph node metastasis, progesterone receptor, estrogen receptor and Ki-67 in BC patients. After EV treatment, NEAT1 and KLF12 levels were increased, miR-141-3p expression was decreased, the abilities of proliferation, invasion, migration and in vivo metastasis were enhanced, and the sensitivity of cells to cisplatin, paclitaxel and 5-fluorouracil was decreased. After NEAT1 interference, NEAT1 and KLF12 levels in BC cells treated with EVs were decreased, miR-141-3p expression was increased, cell proliferation, invasion, migration and in vivo metastasis were decreased, and drug resistance sensitivity was increased. NEAT1 can bind to miR-141-3p and upregulates KLF12 expression.

Conclusions

EVs inhibit the regulation of KLF12 by miR-141-3p by transporting NEAT1 to BC cells, thus promoting BC cell invasion, migration, and chemotherapy resistance.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

Linc00475 promotes the progression of glioma by regulating the miR-141-3p/YAP1 axis

Glioma is the most prevalent and lethal primary brain tumour. Abundant long non‐coding RNAs ( lncRNAs) are aberrant and play crucial roles in the oncogenesis of glioma. The exact functions of linc00475 in glioma remain blurred. Here, we analysed the expression levels of linc00475 by qRT‐PCR and discovered that linc00475 was up‐regulated in glioma and predicted a poor prognosis in patients with glioma. Besides, inhibiting linc00475 restrained the progression of glioma in vitro and in vivo. Further experiments confirmed that linc00475 regulated the progression of glioma by acting as a sponge for miR‐141‐3p. Moreover, we detected the binding sites of linc00475 and miR‐141‐3p, the YAP1‐ 3′UTR and miR‐141‐3p by luciferase reporters. The rescue assays confirmed that inhibiting linc00475 restrained the progression of glioma through the miR‐141‐3p/YAP1 pathway. Collectively, our research demonstrates the key roles of linc00475 in glioma, which could be a promising therapeutic target.

Connecting the Missing Dots: ncRNAs as Critical Regulators of Therapeutic Susceptibility in Breast Cancer

Whether acquired or de novo, drug resistance remains a significant hurdle in achieving therapeutic success in breast cancer (BC). Thus, there is an urge to find reliable biomarkers that will help in predicting the therapeutic response. Stable and easily accessible molecules such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are regarded as valuable prognostic biomarkers and therapeutic targets since they act as crucial regulators of the various mechanisms involved in BC drug resistance. Here, we reviewed the current literature on ncRNAs as mediators of resistance to systemic therapies in BC. Interestingly, upon integrating data results from individual studies, we concluded that miR-221, miR-222, miR-451, Urothelial Carcinoma Associated 1 (UCA1), and Growth arrest-specific 5 (GAS5) are strong candidates as prognostic biomarkers and therapeutic targets since they are regulating multiple drug resistance phenotypes in BC. However, further research around their clinical implications is needed to validate and integrate them into therapeutic applications. Therefore, we believe that our review may provide relevant evidence for the selection of novel therapeutic targets and prognostic biomarkers for BC and will serve as a foundation for future translational research in the field.

Exosome-Reversed Chemoresistance to Cisplatin in Non-Small Lung Cancer Through Transferring miR-613

Introduction

Non-small lung cancer (NSCLC) is one of the most common malignant tumors in the world. Chemoresistance is the main reason of adverse effects leading to the death of patients; thus, it is important to discover the potential target of chemotherapeutic resistance.

Methods

The expression of differentially expressed miRNA was detected in BEAS-2B, A549 and A549/cisplatin (DDP) by qRT-PCR. Transmission electron microscopy (TEM) and exosome biomarkers were used to validate the extracted exosome. Cells incubated with miR-613 enriched exosomes were used to detect the function of exo-miR-613 in vitro. Then, exo-miR-613 was injected to mice treated with DDP to investigate the function role of exo-miR-613 in vivo.

Results

Comparing to BEAS-2B, the expression of miR-613 inA549 was significantly reduced, which was more obvious in A549/DDP. After incubated with exo-miR-613 and corresponding exo-negative control (NC), we found overexpression of miR-613 remarkably increased the inhibition of cell proliferation induced by cisplatin. Exo-miR-613 fused into cells to significantly enhance the inhibited effect of DDP on the proliferation, migration and showed a promotion on cell apoptosis and DNA damage. The in vivo study showed that exo-miR-613 significantly inhibited the tumor growth, and promote the sensitivity to DDP, probably by down-regulating the expressions of GJA1, TBP and EIF-4E in tumor cells and tissues.

Conclusion

Exo-miR-613 reversed chemoresistance to DDP in NSCLC cell to involve in the process of tumor progression, and might be a potential therapeutic strategy for NSCLC.

The Role of Necroptosis in ROS-Mediated Cancer Therapies and Its Promising Applications

Over the past decades, promising therapies targeting different signaling pathways have emerged. Among these pathways, apoptosis has been well investigated and targeted to design diverse chemotherapies. However, some patients are chemoresistant to these therapies due to compromised apoptotic cell death. Hence, exploring alternative treatments aimed at different mechanisms of cell death seems to be a potential strategy for bypassing impaired apoptotic cell death. Emerging evidence has shown that necroptosis, a caspase-independent form of cell death with features between apoptosis and necrosis, can overcome the predicament of drug resistance. Furthermore, previous studies have also indicated that there is a close correlation between necroptosis and reactive oxygen species (ROS); both necroptosis and ROS play significant roles both under human physiological conditions such as the regulation of inflammation and in cancer biology. Several small molecules used in experiments and clinical practice eliminate cancer cells via the modulation of ROS and necroptosis. The molecular mechanisms of these promising therapies are discussed in detail in this review.

Exosomal miR-200c suppresses chemoresistance of docetaxel in tongue squamous cell carcinoma by suppressing TUBB3 and PPP2R1B

BACKGROUND

Chemoresistance is the main challenge for treating tongue squamous cell carcinoma (TSCC). MiR-200c is an important regulator of chemoresistance. Exosomes are a promising molecule-delivery system for cancer treatment. Thus, this study aimed to investigate the role of miR-200c in chemoresistance of TSCC and whether exosomes could effectively deliver miR-200c to chemo-resistant cells and regulate cellular activities.

RESULTS

The results showed that the downregulation of miR-200c increased resistance to DTX, migration, and invasion and decreased apoptosis, which was reversed by the overexpression of miR-200c. The NTECs-derived exosomes transported miR-200c to HSC-3DR, increasing the sensitivity to DTX in vitro and in vivo. Also, epithelial-to-mesenchymal transition (EMT) and DNA damage responses were involved in DTX resistance. Furthermore, miR-200c regulated DTX resistance by targeting TUBB3 and PPP2R1B.

CONCLUSION

Exosome-mediated miR-200c delivery may be an effective and promising strategy to treat chemoresistance in TSCC.

METHODS

Docetaxel (DTX) resistant HSC-3 cells (HSC-3DR) were transfected with miR-200c lentivirus and cocultured with exosomes derived from normal tongue epithelial cells (NTECs) that were overexpressed with miR-200c. The roles of miR-200c and exosomal miR-200c in vitro and in vivo were determined by RNA-Seq, qRT-PCR, western blots, transmission electron microscopy, and flow cytometry, fluorescence, CCK8, Transwell, and wound healing assays.

Non-Coding RNAs as Regulators and Markers for Targeting of Breast Cancer and Cancer Stem Cells

Breast cancer is regarded as a heterogeneous and complicated disease that remains the prime focus in the domain of public health concern. Next-generation sequencing technologies provided a new perspective dimension to non-coding RNAs, which were initially considered to be transcriptional noise or a product generated from erroneous transcription. Even though understanding of biological and molecular functions of noncoding RNA remains enigmatic, researchers have established the pivotal role of these RNAs in governing a plethora of biological phenomena that includes cancer-associated cellular processes such as proliferation, invasion, migration, apoptosis, and stemness. In addition to this, the transmission of microRNAs and long non-coding RNAs was identified as a source of communication to breast cancer cells either locally or systemically. The present review provides in-depth information with an aim at discovering the fundamental potential of non-coding RNAs, by providing knowledge of biogenesis and functional roles of micro RNA and long non-coding RNAs in breast cancer and breast cancer stem cells, as either oncogenic drivers or tumor suppressors. Furthermore, non-coding RNAs and their potential role as diagnostic and therapeutic moieties have also been summarized.

Modulation of the dual-faced effects of miR-141 with chitosan/miR-141 nanoplexes in breast cancer cells

BACKGROUND

miR-141, known as a tumor suppressive microRNA, is downregulated in breast cancer. However, recent contrasting studies report that it also acts as oncogene when it is upregulated. The present study aimed to investigate whether miR-141 is a tumor suppressor or oncogenic when it reaches normal levels in chitosan/miR-141 nanoplexes.

METHODS

Chitosan nanoplexes were prepared using simple complexation method. Nanoplexes were characterized by a gel retardation assay and zeta potential and particle size measurements. To determine the expression level of miR-141, a quantitative real-time polymerase chain reaction was performed. The effects of miR-141 mimics were investigated with respect to angiogenesis by vascular endothelial growth factor (VEGF), epithelial-mesenchymal transition (EMT) by E-cadherin, metastasis by Igfbp-4 and Tinagl1 enzyme-linked immunosorbent assays, invasion by an invasion chamber, and apoptosis by Annexin V.

RESULTS

The miR-141 expression levels of MDA-MB-231 and MDA-MB-435 cells by administration of chitosan/mimic miR-141 nanoplexes reached endogenous miR-141 levels of a non-tumorigenic epithelial breast cell line, MCF-10A. According to our results, metastasis, VEGF, EMT and invasion in breast cancer cells were diminished, whereas apoptosis increased by 1.5- and 2.4-fold in breast cancer cell lines as a result of the miR-141 mimics.

CONCLUSIONS

In conclusion, we have demonstrated that administration of miR-141 mimics at the determined doses to breast cancer cells revealed a tumor suppressor effect, and not the oncogenic face. The delivery of miR-141 by chitosan nanoplexes presents a promising approach for the suppression of breast cancer.

Theragnosis by a miR-141-3p molecular beacon: simultaneous detection and sensitization of 5-fluorouracil resistant colorectal cancer cells through the activation of the TRIM13-associated apoptotic pathway

We developed a molecular beacon targeting miR-141-3p, aberrantly increased in 5-fluorouracil-resistant colorectal cancer cells (R-CRCCs). It consists of a fluorophore-labeled oligonucleotide, antisense to miR-141-3p, and a quencher. It detected R-CRCCs and recovered the chemosensitivity of them to 5-fluorouracil by hybridization with miR-141-3p, which is applicable to cancer treatment.

Glyceryl trinitrate‑induced cytotoxicity of docetaxel‑resistant prostatic cancer cells is associated with differential regulation of clusterin

Metastatic castration resistant prostate cancer (mCRPC) relapse due to acquired resistance to chemotherapy, such as docetaxel, remains a major threat to patient survival. Resistance of mCRPC to docetaxel can be associated with elevated levels of soluble clusterin (sCLU) and growth differentiation factor‑15 (GDF‑15). Any strategies aiming to modulate sCLU and/or GDF‑15 in docetaxel‑resistant prostate cancer cells present a therapeutic interest. The present study reports the cytotoxic effect of a nitric oxide donor, glyceryl trinitrate (GTN), on docetaxel‑resistant mCRPC human cell lines and demonstrates that GTN displays greater inhibition of cell viability toward docetaxel‑resistant mCRPC cells than on mCRPC cells. It is also demonstrated that GTN modulates the level of expression of clusterin (CLU) which is dependent of GDF‑15, two markers associated with docetaxel resistance in prostate cancer. The results indicate that GTN represses the level of expression of the cytoprotective isoform of CLU (sCLU) and can increase the level of expression of the cytotoxic isoform (nuclear CLU) in docetaxel resistant cells. Furthermore, it was observed that GTN differentially regulates the level of the precursor form of GDF‑15 between resistant and parental cells, and that recombinant GDF‑15 can modulate the expression of CLU isoforms and counteract GTN‑induced cytotoxicity in resistant cells. A link was established between GDF‑15 and the expression of CLU isoforms. The present study thus revealed GTN as a potential therapeutic strategy to overcome docetaxel‑resistant mCRPC.

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.

Nonredundant, Highly Connected MicroRNAs Control Functionality in Breast Cancer Networks

Alterations to transcriptional regulation are an important factor in breast cancer. Noncoding RNA, such as microRNA (miR), have very influential roles in the transcriptional regulation of genes. Transcriptional regulation can be successfully modeled and analyzed using complex network theory. Particularly, interactions between two distinct classes of biological elements, such as miR and genes, can be approached through the bipartite network formalism. Based on bipartite network properties, it is possible to identify highly influential miRs in the network, such as those that have a large number of connections indicating regulation of a large set of genes. Some miRs in a network are nonredundant, which indicates that they are solely responsible of the regulation of a particular set of genes, which in turn may be associated to a particular biological process. We hypothesize that highly influential, nonredundant miRs, which we call Commodore miRs (Cdre-miRs), have an important role on the control of biological functions through transcriptional networks. In this work, we analyze the regulation of gene expression by miRs in healthy and cancerous breast tissue using bipartite miR-gene networks inferred from the Cancer Genome Atlas (TCGA) expression data. We observe differences in the degree, clustering coefficient and redundancy distributions for miRs and genes in the network, indicating differences in the way that these elements interact with each other. Furthermore, we identify a small set of five Cdre-miRs in the breast cancer network: miR-190b, miR-let7i, miR-292-b, miR-511, and miR-141. The neighborhood of genes controlled by each of these miRs is involved in particular biological functions such as dynein structure-associated processes, immune response, angiogenesis, cytokine activity, and cell motility. We propose that these Cdre-miRs are important control elements of biological functions deregulated in breast cancer.

microRNA Expression in Ethnic Specific Early Stage Breast Cancer: an Integration and Comparative Analysis

Breast cancer (BC) has a higher incidence in young Lebanese woman as compared to the West. We assessed the microRNA (miRNA) microarray profile of tissues derived from Lebanese patients with early BC and performed mRNA-miRNA integration analysis. 173 miRNAs were significantly dysregulated in 45 BC versus 17 normal adjacent breast tissues, including 74 with a fold change more than two of which 17 were never reported before in cancer. Integration analysis of mRNA-miRNA microarray data revealed a potential role of 51 dysregulated miRNA regulating 719 tumor suppressive or oncogenic mRNA associated with increased proliferation and decreased migration and invasion. We then performed a comparative miRNA microarray profile analysis of BC tissue between these 45 Lebanese and 197 matched American BC patients. Notably, Lebanese BC patients had 21 exclusively dysregulated miRNA (e.g. miR-31, 362-3p, and 663) and 4 miRNA with different expression manner compared to American patients (e.g. miR-1288-star and 324-3p). Some of these differences could reflect variation in patient age at diagnosis or ethnic variation affecting miRNA epigenetic regulation or sequence of miRNA precursors. Our data provide a basis for genetic/epigenetic investigations to explore the role of miRNA in early stage BC in young women, including ethnic specific differences.

Genome-wide miRNA response to anacardic acid in breast cancer cells

MicroRNAs are biomarkers and potential therapeutic targets for breast cancer. Anacardic acid (AnAc) is a dietary phenolic lipid that inhibits both MCF-7 estrogen receptor α (ERα) positive and MDA-MB-231 triple negative breast cancer (TNBC) cell proliferation with IC50s of 13.5 and 35 μM, respectively. To identify potential mediators of AnAc action in breast cancer, we profiled the genome-wide microRNA transcriptome (microRNAome) in these two cell lines altered by the AnAc 24:1n5 congener. Whole genome expression profiling (RNA-seq) and subsequent network analysis in MetaCore Gene Ontology (GO) algorithm was used to characterize the biological pathways altered by AnAc. In MCF-7 cells, 69 AnAc-responsive miRNAs were identified, e.g., increased let-7a and reduced miR-584. Fewer, i.e., 37 AnAc-responsive miRNAs were identified in MDA-MB-231 cells, e.g., decreased miR-23b and increased miR-1257. Only two miRNAs were increased by AnAc in both cell lines: miR-612 and miR-20b; however, opposite miRNA arm preference was noted: miR-20b-3p and miR-20b-5p were upregulated in MCF-7 and MDA-MB-231, respectively. miR-20b-5p target EFNB2 transcript levels were reduced by AnAc in MDA-MB-231 cells. AnAc reduced miR-378g that targets VIM (vimentin) and VIM mRNA transcript expression was increased in AnAc-treated MCF-7 cells, suggesting a reciprocal relationship. The top three enriched GO terms for AnAc-treated MCF-7 cells were B cell receptor signaling pathway and ribosomal large subunit biogenesis and S-adenosylmethionine metabolic process for AnAc-treated MDA-MB-231 cells. The pathways modulated by these AnAc-regulated miRNAs suggest that key nodal molecules, e.g., Cyclin D1, MYC, c-FOS, PPARγ, and SIN3, are targets of AnAc activity.

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.

MicroRNA-455-3p functions as a tumor suppressor by targeting eIF4E in prostate cancer

MicroRNAs (miRNAs) are strongly implicated in various cancers, including prostate cancer. Recently, microRNA-455-3p (miR-455-3p) has been shown to be aberrantly expressed in many tumor tissues, but its functions in tumorigenesis remain unknown. In this study, we investigated the role of miR-455-3p in prostate cancer. We found that miR-455-3p is markedly downregulated in prostate cancer cell lines and clinical tumor specimens. Gain-of-function and loss-of-function studies showed that miR-455-3p promotes prostate cancer cell growth both in vitro and in vivo. Bioinformatics analysis and Luciferase reporter assays demonstrated that miR-455-3p directly targets and suppresses eIF4E, the rate-limiting factor for cap-dependent translation, which plays important roles in the initiation and progression of prostate cancers. Further studies demonstrated that miR-455-3p inhibits cap-dependent translation and the proliferation of prostate cancer cells through targeting eIF4E. Taken together, our findings suggest that miR-455-3p functions as a tumor suppressor by directly targeting eIF4E in prostate carcinogenesis and may be used as a potential target for therapeutic intervention in prostate cancer.

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.

Taxotere-induced elevated expression of IL8 in carcinoma-associated fibroblasts of breast invasive ductal cancer

Breast cancer is the most common malignant tumor in women worldwide, and accounts for an estimated 29% of new cases and 15% of cancer-associated mortalities each year. Invasive ductal carcinoma represents 70-80% of all breast cancer cases, which are responsible for the majority of breast cancer fatalities. Though great progress has been made in understanding the tumorigenesis and development of breast cancer, problems surrounding treatment persist. It was previously reported that carcinoma-associated fibroblasts (CAFs) may be closely associated with chemotherapy resistance. In the present study, primary-cultured CAFs from surgically resected breast invasive ductal cancer tissues were prepared and tested to clarify the change of gene expression profile following treatment with 20 ng/ml Taxotere^® for 24 h through microarray analysis. In addition, quantitative polymerase chain reaction and western blotting were performed to compare the gene and protein expression of the candidate gene in CAFs prior to and following Taxotere treatment. Based on the obtained data, 35 differentially expressed genes were identified, including ACTA2, ACTC1, ACTG, ALDH1B1, AMY1A, C5orf13, CNN1, CXCR7, DDAH1, FGF1, PDLIM3, MAMLD1, MYH11, OXTR, PDLIM5, RARRES1, SERPINA3, TRIL, C14orf43, C1orf51, CXCL12, CXCL2, EGR2, EGR3, IER3, interleukin (IL)8, IRF1, JUNB, MMP1, NAV2, NFKBIA, NFKBIZ, TRIB1, WNT16 and ZC3H12A. It was observed that the expression of the candidate gene IL8 in the CAFs of breast invasive cancer following treatment with Taxotere was increased (P<0.05). Overall, elevated expression of IL8 induced by Taxotere in CAFs potentially supports the association between IL8 and chemotherapy response.

Molecular Pathways: The eIF4F Translation Initiation Complex-New Opportunities for Cancer Treatment

The eIF4F complex regulates the cap-dependent mRNA translation process. It is becoming increasingly evident that aberrant activity of this complex is observed in many cancers, leading to the selective synthesis of proteins involved in tumor growth and metastasis. The selective translation of cellular mRNAs controlled by this complex also contributes to resistance to cancer treatments, and downregulation of the eIF4F complex components can restore sensitivity to various cancer therapies. Here, we review the contribution of the eIF4F complex to tumorigenesis, with a focus on its role in chemoresistance as well as the promising use of new small-molecule inhibitors of the complex, including flavaglines/rocaglates, hippuristanol, and pateamine A. Clin Cancer Res; 23(1); 21-25. ©2016 AACR.

Mechanisms of breast cancer resistance to anthracyclines or taxanes: an overview of the proposed roles of noncoding RNA

PURPOSE OF REVIEW

Anthracyclines and taxanes are the two most active classes of cytotoxic agents that are commonly used for the treatment of breast cancer. However, resistance to these agents has become a major clinical obstacle. The aim of the present review is to define the roles of noncoding RNA (ncRNA) in breast cancer progression and the development of chemotherapy resistance. The ultimate goal is to exploit ncRNAs as new therapeutic tools to overcome resistance.

RECENT FINDINGS

Two important types of ncRNA include microRNA (miRNA) and long noncoding RNA (lncRNA). Both miRNA and lncRNA have recently impacted the field of breast cancer research as important pieces in the mechanistic puzzle of the genes and pathways involved in breast cancer development and progression.

SUMMARY

Herein, we review the roles of miRNA and lncRNA in breast cancer progression and the development of chemotherapy resistance. Future research should include identification of ncRNAs that could be potential therapeutic targets in chemotherapy-resistant tumors, as well as ncRNA biomarkers that facilitate more tumor-specific treatment options for chemotherapy-resistant breast cancer patients.

MiR-181b promotes chemoresistance in breast cancer by regulating Bim expression

MicroRNAs are emerging as critical regulators of the initiation and progression of multiple types of human cancers, including breast cancer. In the present study, the expression of miR-181b in breast cancer patient serum and breast cancer cell lines was evaluated. It was demonstrated that the miR-181b level was significantly upregulated in patient serum and breast cancer cell lines compared with that in normal controls. The results of in vitro 3H thymidine incorporation and Transwell migration assay indicated that miR-181b overexpression markedly promoted the proliferation and metastasis of breast cancer cells. These data suggest that miR-181b is a tumor promoter in breast cancer. Furthermore, miR-181b expression was found to be upregulated in doxorubicin (DOX)-resistant T-47D cells (T-47D-R) compared with that in the parental T-47D cells, and upregulation of miR-181b expression decreased the anticancer effect of DOX in the T-47D cells. Mechanistic studies demonstrated that the Bim gene, an essential initiator of apoptosis, was inhibited by miR-181b overexpression. We observed that knockdown of miR-181b by its specific inhibitors significantly re-sensitized the T-47D-R cells to the cytotoxicity of DOX. Importantly, we demonstrated that miR-181b inhibitors increased the level of Bim in the T-47D-R cells, resulting in the loss of mitochondrial membrane potential (MMP) and the activation of caspases caused by DOX. In summary, the results of the present study suggest that miR-181b functions as an oncogene during breast cancer development, and the miR-181b/Bim pathway may be a novel target used to overcome the chemoresistance in breast cancer.

MiR-944 functions as a novel oncogene and regulates the chemoresistance in breast cancer

MircroRNAs are emerging as critical regulators in carcinogenesis and chemoresistance in multiple cancer types. In this study, we observed that the miR-944 level was upregulated in breast cancer patients' serum and tumor tissues, suggesting that miR-944 is a tumor promoter in breast cancer. To investigate the role of miR-944, we performed gain- and loss-of-function experiments in vitro. We then demonstrated that miR-944 promotes cell proliferation and tumor metastasis in breast cancer cell lines. Furthermore, we indicated that miR-944 is associated with cisplatin resistance by targeting BNIP3. Knockdown of the miR-944 by specific inhibitors significantly increased the cytotoxicity of cisplatin in cisplatin-resistant MCF-7 cells (MCF-7/R). Importantly, we found that the sensitization of miR-944 inhibitors to cisplatin cytotoxicity was abolished by BNIP3 siRNA which decreased the expression of BNIP3 gene. Finally, we demonstrated that miR-944 inhibitors promoted the loss of mitochondrial membrane potential (MMP) caused by cisplatin in MCF-7/R cells, resulting in the release of mitochondria-derived apoptogenic proteins into cytoplasm, and then, the caspase-3 was activated. In summary, our study showed that miR-944 functions as a novel oncogene and regulates the cisplatin resistance in breast cancer. The miR-944-BNIP3-MMP-caspase-3 pathway might be a novel target for the chemotherapy of breast cancer.

Genomic signatures for paclitaxel and gemcitabine resistance in breast cancer derived by machine learning

Increasingly, the effectiveness of adjuvant chemotherapy agents for breast cancer has been related to changes in the genomic profile of tumors. We investigated correspondence between growth inhibitory concentrations of paclitaxel and gemcitabine (GI50) and gene copy number, mutation, and expression first in breast cancer cell lines and then in patients. Genes encoding direct targets of these drugs, metabolizing enzymes, transporters, and those previously associated with chemoresistance to paclitaxel (n = 31 genes) or gemcitabine (n = 18) were analyzed. A multi-factorial, principal component analysis (MFA) indicated expression was the strongest indicator of sensitivity for paclitaxel, and copy number and expression were informative for gemcitabine. The factors were combined using support vector machines (SVM). Expression of 15 genes (ABCC10, BCL2, BCL2L1, BIRC5, BMF, FGF2, FN1, MAP4, MAPT, NFKB2, SLCO1B3, TLR6, TMEM243, TWIST1, and CSAG2) predicted cell line sensitivity to paclitaxel with 82% accuracy. Copy number profiles of 3 genes (ABCC10, NT5C, TYMS) together with expression of 7 genes (ABCB1, ABCC10, CMPK1, DCTD, NME1, RRM1, RRM2B), predicted gemcitabine response with 85% accuracy. Expression and copy number studies of two independent sets of patients with known responses were then analyzed with these models. These included tumor blocks from 21 patients that were treated with both paclitaxel and gemcitabine, and 319 patients on paclitaxel and anthracycline therapy. A new paclitaxel SVM was derived from an 11-gene subset since data for 4 of the original genes was unavailable. The accuracy of this SVM was similar in cell lines and tumor blocks (70-71%). The gemcitabine SVM exhibited 62% prediction accuracy for the tumor blocks due to the presence of samples with poor nucleic acid integrity. Nevertheless, the paclitaxel SVM predicted sensitivity in 84% of patients with no or minimal residual disease.

miR-1291 targets mucin 1 inhibiting cell proliferation and invasion to promote cell apoptosis in esophageal squamous cell carcinoma

MicroRNAs (miRNAs) are well known as important regulators in various cancer development. In the present study, we focused on the expression and biological function of miR-1291 in esophageal squamous cell carcinoma (ESCC). Compared with adjacent non-tumorous tissue samples, qRT-PCR data showed significant downregulation of miR-1291 in 54 ESCC tissue samples (P<0.05), which was also significantly associated with lymph node metastases and clinical stage (P<0.05). Cell Counting Kit-8 (CCK-8), colony formation, Transwell and flow cytometric apoptosis assays were performed to detect the effect of miR-1291 upregulation, and the results showed inhibition of the proliferation, invasion and promotion of apoptosis in EC9706 and EC-1 cells. Using bioinformatic analyses, we found that mucin 1 (MUC1) was a potential target for miR-1291. Luciferase assays were performed to reveal that miR-1291 inhibited MUC1 expression by targeting the seed region of MUC1 3'-untranslated region (3'UTR). We also found that the expression of MUC1 lacking in 3'UTR abrogated the anti-invasion and pro-apoptosis function of miR-1291. Our results demonstrated the importance of miR-1291 in targeting MUC1 for the regulation of esophagus cancer growth, invasion and apoptosis, and may be helpful for developing new targets for early diagnosis or new therapeutic targets for ESCC.