MicroRNA-320a sensitizes tamoxifen-resistant breast cancer cells to tamoxifen by targeting ARPP-19 and ERRγ

Estrogen-related Receptor Signaling in Skeletal Muscle Fitness

Skeletal muscle is a highly plastic tissue that can alter its metabolic and contractile features, as well as regenerative potential in response to exercise and other conditions. Multiple signaling factors including metabolites, kinases, receptors, and transcriptional factors have been studied in the regulation of skeletal muscle plasticity. Recently, estrogen-related receptors (ERRs) have emerged as a critical transcriptional hub in control of skeletal muscle homeostasis. ERRα and ERRγ - the two highly expressed ERR sub-types in the muscle respond to various extracellular cues such as exercise, hypoxia, fasting and dietary factors, in turn regulating gene expression in the skeletal muscle. On the other hand, conditions such as diabetes and muscular dystrophy suppress expression of ERRs in the skeletal muscle, likely contributing to disease progression. We highlight key functions of ERRs in the skeletal muscle including the regulation of fiber type, mitochondrial metabolism, vascularization, and regeneration. We also describe how ERRs are regulated in the skeletal muscle, and their interaction with important muscle regulators (e. g. AMPK and PGCs). Finally, we identify critical gaps in our understanding of ERR signaling in the skeletal muscle, and suggest future areas of investigation to advance ERRs as potential targets for function promoting therapeutics in muscle diseases.

Non-Coding RNAs Modulating Estrogen Signaling and Response to Endocrine Therapy in Breast Cancer

The largest part of human DNA is transcribed into RNA that does not code for proteins. These non-coding RNAs (ncRNAs) are key regulators of protein-coding gene expression and have been shown to play important roles in health, disease and therapy response. Today, endocrine therapy of ERα-positive breast cancer (BC) is a successful treatment approach, but resistance to this therapy is a major clinical problem. Therefore, a deeper understanding of resistance mechanisms is important to overcome this resistance. An increasing amount of evidence demonstrate that ncRNAs affect the response to endocrine therapy. Thus, ncRNAs are considered versatile biomarkers to predict or monitor therapy response. In this review article, we intend to give a summary and update on the effects of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) on estrogen signaling in BC cells, this pathway being the target of endocrine therapy, and their role in therapy resistance. For this purpose, we reviewed articles on these topics listed in the PubMed database. Finally, we provide an assessment regarding the clinical use of these ncRNA types, particularly their circulating forms, as predictive BC biomarkers and their potential role as therapy targets to overcome endocrine resistance.

Methods for assessing the effect of microRNA on stemness genes

According to the latest concepts, for micrometastasis to develop into macrometastasis, differentiated cancer cells must revert to a dedifferentiated state. Activation of stemness genes plays a key role in this transition. Suppression of stemness gene expression using microRNAs can become the basis for the development of effective anti-metastatic drugs. This article provides an overview of the existing methods for assessing the effect of microRNAs on stemness genes and cancer cell dedifferentiation.

Exosomal miRNAs as novel avenues for breast cancer treatment

Breast cancer is the most commonly diagnosed cancer and a leading cause of death in women worldwide. It is a heterogeneous disease, as shown by the gene expression profiles of breast cancer samples. It begins in milk-producing ducts, with a high degree of diversity between and within tumors, as well as among cancer-bearing individuals. The enhanced prevalence of breast cancer is influenced by various hormonal, lifestyle, and environmental factors, and very early onset of the disease correlates strongly with the risk of local and distant recurrence. Many subtypes are difficult to treat with conventional therapeutic modalities, and therefore, optimal management and early diagnosis are the first steps to minimizing the mortality linked with breast cancer. The use of newer methods of nanotechnology extends beyond the concept of synthesizing drug delivery mechanisms into the creation of new therapeutics, such as delivering chemotherapeutics with nanomaterial properties. Exosomes, a class of nanovesicles, are emerging as novel tools for deciphering the patient-specific proteins and biomarkers across different disease models, including breast cancer. In this review, we address the role of exosomal miRNA in breast cancer diagnosis and treatment.

LINC00460 Facilitates Cell Proliferation and Inhibits Ferroptosis in Breast Cancer Through the miR-320a/MAL2 Axis

Background: Emerging evidence suggests that long noncoding RNAs (lncRNAs) play an important role in the progression of multiple human cancers including breast cancer. In this study, we aimed to research novel functions of long intergenic noncoding RNA 460 (LINC00460) on cell proliferation and ferroptosis in breast cancer. Method: UALCAN, TANRIC, and GSE16446 data were used to analyze the expression of LINC00460 in breast cancer tissues. Furthermore, real-time quantitative PCR, western blot, cell proliferation assay, iron assay, and malondialdehyde (MDA) assay were applied to detect the function and mechanism of particular molecules. Results: The LINC00460 expression was significantly increased in breast cancer tissues compared with normal tissues. Importantly, patients with high LINC00460 expression showed a longer overall survival rate. LINC00460 knockdown markedly suppressed the proliferation of breast cancer cells and promoted ferroptosis. Mechanistic analysis revealed that LINC00460 promoted myelin and lymphocyte protein 2 (MAL2) expression by sponging miR-320a. Moreover, both miR-320a knockdown and MAL2 overexpression could reverse the effects of LINC00460 silencing on cell proliferation and ferroptosis. Conclusions: In summary, our results reveal an alternative mechanism by which breast cancer cells can acquire resistance to ferroptosis via the LINC00460/miR-320a/MAL2 axis.

Research Progress on the Effect of Traditional Chinese Medicine on Signal Pathway Related to Premature Ovarian Insufficiency

The occurrence and development of premature ovarian insufficiency involves the abnormality of multiple signal pathways. It is a complex disease. Traditional Chinese medicine affects the relevant factors of the occurrence and development of premature ovarian insufficiency (granulosa cell apoptosis, ovarian blood supply, ovarian reserve, ovarian oxidative damage, gap junction, ovarian fibrosis, follicular development, follicular atresia, and other biological processes) by regulating a variety of signal pathways, thus playing the role in antioxidant stress, prevention and treatment of chemotherapy side effects, protection of ovarian function, control of aging, and improvement of ovarian reserve function. The research shows that the research on the related pathways of traditional Chinese medicine in the treatment of premature ovarian insufficiency has been quite extensive. Based on the search of the domestic and foreign literature, it is found that Yulinzhu and Xianziyizhen capsule and ginsenoside Rg₁ can promote the proliferation and differentiation of granulosa cells, inhibit apoptosis, and reduce follicular atresia by affecting the PI3K/Akt/mTOR signal pathway; Guiluo's Anzang decoction, Kuntai capsule, and Yangyin Shugan granule can maintain the balance between pro-apoptotic protein and anti-apoptotic protein through the Bax/cytc/caspase-3 pathway to improve ovarian reserve function; Bushen Jianpi recipe can control cell apoptosis and promote the proliferation and development of ovarian granulosa cells by regulating the MAPK signal pathway; Siwu mixture and Zuo Gui pill can regulate the TGF-β/Smads signaling pathway to promote the recruitment of primordial follicles, promotes follicular development, inhibits follicular atresia, and regulates ovarian function; Erxian decoction, Yiqi Yangrong Fujing formula, and Cistanche deserticola can antagonize the inflammatory symptoms of premature ovarian failure, promote the secretion of relevant vascular growth factors, and enhance the ovarian reserve function through the NF-KB signal pathway; Bushen Culuan decoction can promote damage repair and protect normal ovarian cells through antioxidant stress. The above summary aims at providing reference for the in-depth study of traditional Chinese medicine in the treatment of premature ovarian insufficiency and inspiring new diagnosis and treatment ideas.

EV-miRome-wide profiling uncovers miR-320c for detecting metastatic colorectal cancer and monitoring the therapeutic response

PURPOSE

Molecular composition of circulating small extracellular vesicles (EVs) does not merely reflect the cells of origin, but also is enriched in specific biomolecules directly associated with the cellular transformation. However, while most of the currently identified EV-miRs are only geared towards one-dimensional disease detection, their application for long-term tracking and treatment response monitoring has been largely elusive.

METHODS

We established and optimized a rapid, sensitive and robust liquid biopsy sampling method, and further used small RNA sequencing to comprehensively catalogue EV-miRomes in association with the progression and outcome of metastatic colorectal cancer (mCRC).

RESULTS

By cross-comparison of EV-miRomes (n = 290) from multi-stage and longitudinal cohorts, we uncovered a 15-EV-miR signature with dual detection and long-term monitoring of tumor size progression for mCRC. From this panel, EV-miR-320c was uncovered as a strong clinical marker - aside from its diagnostic power and a therapeutic monitoring performance superior to carcinoembryonic antigen (CEA), its high expression has also been linked to lower overall survival and a greater likelihood of disease recurrence. Further, integrative analyses of tissue transcriptomic and liquid biopsy implicated this 15-EV-miR signature in programming the mesenchymal-epithelial transition (MET) for distant localization of the metastasized cells and also in creating a tumor-favoring metastatic niche.

CONCLUSION

Our clinically-oriented delineation of the mCRC-associated circulating EV-miRomes systematically revealed the functional significance of these liquid biopsy markers and further strengthen their translational potential in mCRC therapeutic monitoring.

MicroRNAs miR-142-5p, miR-150-5p, miR-320a-3p, and miR-4433b-5p in Serum and Tissue: Potential Biomarkers in Sporadic Breast Cancer

Breast cancer (BC) is a heterogeneous disease, and establishing biomarkers is essential to patient management. We previously described that extracellular vesicle–derived miRNAs (EV-miRNAs) miR-142-5p, miR-150-5p, miR-320a, and miR-4433b-5p in serum discriminated BC from control samples, either alone or combined in a panel. Using these previously described markers, we intend to evaluate whether the same markers identified in EVs are also potential biomarkers in tissue and serum. Expression analysis using RT-qPCR was performed using serum of 67 breast cancer patients (BC-S), 19 serum controls (CT), 83 fresh tumor tissues (BC-T), and 29 adjacent nontumor tissue samples (NT). In addition, analysis from The Cancer Genome Atlas (TCGA) data (832 BC-T and 136 NT) was performed. In all comparisons, we found concordant high expression levels of miR-320a and miR-4433b-5p in BC-S compared to CT in both EVs and cell-free miRNAs (cf-miRNAs). Although miR-150-5p and miR-142-5p were not found to be differentially expressed in serum, panels including these miRNAs improved sensitivity and specificity, supporting our previous findings in EVs. Fresh tissue and data from the TCGA database had, in most comparisons, an opposite behavior when compared to serum and EVs: lower levels of all miRNAs in BC-T than those in NT samples. TCGA analyses revealed reduced expression levels of miR-150-5p and miR-320a-3p in BC-T than those in NT samples and the overexpression of miR-142-5p in BC-T, unlike our RT-qPCR results from tissue in the Brazilian cohort. The fresh tissue analysis showed that all miRNAs individually could discriminate between BC-T and NT in the Brazilian cohort, with high sensitivity and sensibility. Furthermore, combining panels showed higher AUC values and improved sensitivity and specificity. In addition, lower levels of miR-320a-3p in serum were associated with poor overall survival in BC Brazilian patients. In summary, we observed that miR-320a and miR-4433b-5p distinguished BC from controls with high specificity and sensibility, regardless of the sample source. In addition, lower levels of miR-150-5p and higher levels of miR-142-5p were statistically significant biomarkers in tissue, according to TCGA. When combined in panels, all combinations could distinguish BC patients from controls. These results highlight a potential application of these miRNAs as BC biomarkers.

Engineered Exosomes-Mediated Transfer of hsa-miR-320a Overcomes Chemoresistance in Cervical Cancer Cells via Targeting MCL1

In cervical cancer (CC), cisplatin resistance greatly restricts the application in clinical. Here, we report that engineered exosomes-mediated transfer of hsa-miR-320a overcomes chemoresistance in cervical cancer cells via targeting Myeloid Cell Leukemia Sequence 1 (MCL1). In DDP resistant CC tissues, as well as cell lines, it was found that miR-320a expression is lower, engineered miR-320a exosomes were used to attenuate DDP resistance in Hela/DDP and Caski/DDP cells. Mechanistically, we find that MCL1, which is a target of miR-320a, overcomes DDP resistance in Hela/DDP cells and in mice. In conclusion, we report that the engineered miR-320a exosomes is proved to be effective and safe.

The Roles of microRNAs in Cancer Multidrug Resistance

Simple Summary

The resistance of neoplastic cells to multiple drugs is a serious problem in cancer chemotherapy. The molecular causes of multidrug resistance in cancer are largely known, but less is known about the mechanisms by which cells deliver phenotypic changes that resist the attack of anticancer drugs. The findings of RNA interference based on microRNAs represented a breakthrough in biology and pointed to the possibility of sensitive and targeted regulation of gene expression at the post-transcriptional level. Such regulation is also involved in the development of multidrug resistance in cancer. The aim of the current paper is to summarize the available knowledge on the role of microRNAs in resistance to multiple cancer drugs.

Abstract

Cancer chemotherapy may induce a multidrug resistance (MDR) phenotype. The development of MDR is based on various molecular causes, of which the following are very common: induction of ABC transporter expression; induction/activation of drug-metabolizing enzymes; alteration of the expression/function of apoptosis-related proteins; changes in cell cycle checkpoints; elevated DNA repair mechanisms. Although these mechanisms of MDR are well described, information on their molecular interaction in overall multidrug resistance is still lacking. MicroRNA (miRNA) expression and subsequent RNA interference are candidates that could be important players in the interplay of MDR mechanisms. The regulation of post-transcriptional processes in the proteosynthetic pathway is considered to be a major function of miRNAs. Due to their complementarity, they are able to bind to target mRNAs, which prevents the mRNAs from interacting effectively with the ribosome, and subsequent degradation of the mRNAs can occur. The aim of this paper is to provide an overview of the possible role of miRNAs in the molecular mechanisms that lead to MDR. The possibility of considering miRNAs as either specific effectors or interesting targets for cancer therapy is also analyzed.

NUDT21 Promotes Tumor Growth and Metastasis Through Modulating SGPP2 in Human Gastric Cancer

Gastric cancer is one of the major malignancies with poor survival outcome. In this study, we reported that NUDT21 promoted cell proliferation, colony formation, cell migration and invasion in gastric cancer cells. The expression levels of NUDT21 were found to be much higher in human gastric cancer tissues compared with normal gastric tissues. NUDT21 expression was positively correlated with tumor size, lymph node metastasis and clinical stage in gastric cancer patients. High level of NUDT21 was associated with poor overall survival (OS) rates in gastric cancer patients. The expression levels of NUDT21 were also much higher in gastric cancer tissues from patients with tumor metastasis compared with those of patients without tumor metastasis. Moreover, forced expression of NUDT21 in gastric cancer cells promoted tumor growth and cell proliferation in xenograft nude mice, and depletion of NUDT21 in gastric cancer cells restrained lung metastasis in vivo. Through high throughput RNA-sequencing, SGPP2 was identified to be positively regulated by NUDT21 and mediated the tumor promoting role of NUDT21 in gastric cancer cells. Therefore, NUDT21 played an oncogenic role in human gastric cancer cells. NUDT21 could be considered as a novel potential target for gastric cancer therapy.

MicroRNAs as a clue to overcome breast cancer treatment resistance

Breast cancer is the most frequent cancer in women worldwide. Despite the improvement in diagnosis and treatments, the rates of cancer relapse and resistance to therapies remain higher than desirable. Alterations in microRNAs have been linked to changes in critical processes related to cancer development and progression. Their involvement in resistance or sensitivity to breast cancer treatments has been documented by different in vivo and in vitro experiments. The most significant microRNAs implicated in modulating resistance to breast cancer therapies are summarized in this review. Resistance to therapy has been linked to cellular processes such as cell cycle, apoptosis, epithelial-to-mesenchymal transition, stemness phenotype, or receptor signaling pathways, and the role of microRNAs in their regulation has already been described. The modulation of specific microRNAs may modify treatment response and improve survival rates and cancer patients' quality of life. As a result, a greater understanding of microRNAs, their targets, and the signaling pathways through which they act is needed. This information could be useful to design new therapeutic strategies, to reduce resistance to the available treatments, and to open the door to possible new clinical approaches.

From Micro to Long: Non-Coding RNAs in Tamoxifen Resistance of Breast Cancer Cells

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer mortality among women. Two thirds of patients are classified as hormone receptor positive, based on expression of estrogen receptor alpha (ERα), the main driver of breast cancer cell proliferation, and/or progesterone receptor, which is regulated by ERα. Despite presenting the best prognosis, these tumors can recur when patients acquire resistance to treatment by aromatase inhibitors or antiestrogen such as tamoxifen (Tam). The mechanisms that are involved in Tam resistance are complex and involve multiple signaling pathways. Recently, roles for microRNAs and lncRNAs in controlling ER expression and/or tamoxifen action have been described, but the underlying mechanisms are still little explored. In this review, we will discuss the current state of knowledge on the roles of microRNAs and lncRNAs in the main mechanisms of tamoxifen resistance in hormone receptor positive breast cancer. In the future, this knowledge can be used to identify patients at a greater risk of relapse due to the expression patterns of ncRNAs that impact response to Tam, in order to guide their treatment more efficiently and possibly to design therapeutic strategies to bypass mechanisms of resistance.

MicroRNA 320, an Anti-Oncogene Target miRNA for Cancer Therapy

MicroRNAs are a set of highly conserved non-coding RNAs that control gene expression at the post-transcriptional/translational levels by binding to the 3′-UTR of diverse target genes. Increasing evidence indicates that miRNAs not only play a vital role in many biological processes, but they are also frequently deregulated in pathological conditions, including cancer. The miR-320 family is one of many tumor suppressor families and is composed of five members, which has been demonstrated to be related to the repression of epithelial-mesenchymal transition (EMT) inhibition, cell proliferation, and apoptosis. Moreover, this family has been shown to regulate drug resistance, and act as a potential biomarker for the diagnosis, prognosis, and prediction of cancer. In this review, we summarized recent research with reference to the tumor suppressor function of miR-320 and the regulation mechanisms of miR-320 expression. The collected evidence shown here supports that miR-320 may act as a novel biomarker for cancer prognosis and therapeutic response to cancer treatment.

Radix Actinidiae extract affects proliferation and apoptosis of colorectal cancer cells by regulating miR-192-5p/ARPP19

BACKGROUND

Radix Actinidiae extract (RAE) can inhibit the proliferation of gastric cancer, lung cancer, and other tumor cells, and has appreciated anti-tumor effects, but it is unknown whether it affects the malignant phenotype of colorectal cancer cells. The expression of miR-192-5p is reduced in colorectal cancer tissues, and its low expression is related to clinicopathological characteristics such as tumor size. Thus, it can be used as a potential biomarker for the diagnosis and treatment of colorectal cancer. StarBase bioinformatics software predicts that cAMP-regulated phosphoprotein 19 (ARPP19) may be a target gene of miR-192-5p. This study hypothesized that RAE can affect the proliferation and apoptosis of colorectal cancer cells by regulating the miR-192-5p/ARPP19 axis.

AIM

To investigate the effects and mechanism of RAE on proliferation and apoptosis of colorectal cancer SW480 cells.

METHODS

After SW480 cells were treated with RAE, cell proliferation was detected by MTT assay, apoptosis was detected by flow cytometry, and the protein expression levels of Cyclin D1, cleaved Caspase-3, and ARPP19 were detected by Western blot. The expression of miR-192-5p and ARPP19 mRNA in cells was detected by RT-qPCR. miR-192-5p mimic or ARPP19 small interfering RNA was transfected into SW480 cells, and then the above methods were used to observe the effects of over-expressing miR-192-5p or inhibiting ARPP19 on cell proliferation, apoptosis, and the protein expression of CyclinD1 and cleaved Caspase-3 in SW480 cells. The regulatory relationship between miR-192-5p and ARPP19 was verified by the dual luciferase reporter gene assay.

RESULTS

RAE decreased the survival rate of SW480 cells and the expression of ARPP19 mRNA and protein (P < 0.05), but increased the apoptosis rate of SW480 cells and the expression of cleaved Caspase-3 protein and miR-192-5p (P < 0.05). Over-expressing miR-192-5p or inhibiting ARPP19 expression could decrease the survival rate of SW480 cells and the expression of CyclinD1 protein (P < 0.05), but increase the apoptosis rate of SW480 cells and the expression of cleaved Caspase-3 protein (P < 0.05). miR-192-5p negatively regulated the expression of ARPP19 in SW480 cells. Inhibiting miR-192-5p reversed the effects of RAE on proliferation, apoptosis, and the protein expression of CyclinD1 and cleaved Caspase-3 in SW480 cells. Inhibiting ARPP19 reversed the effects of inhibiting miR-192-5p on proliferation, apoptosis, and the protein expression of CyclinD1 and cleaved Caspase-3 of SW480 cells treated with RAE.

CONCLUSION

RAE inhibits the proliferation of colorectal cancer SW480 cells and promotes apoptosis, and its mechanism of action is related to the regulation of the miR-192-5p/ARPP19 axis.

Exosomal microRNAs: Pleiotropic Impacts on Breast Cancer Metastasis and Their Clinical Perspectives

As a major threat factor for female health, breast cancer (BC) has garnered a lot of attention for its malignancy and diverse molecules participating in its carcinogenesis process. Among these complex carcinogenesis processes, cell proliferation, epithelial-to-mesenchymal transition (EMT), mesenchymal-to-epithelial transition (MET), and angiogenesis are the major causes for the occurrence of metastasis and chemoresistance which account for cancer malignancy. MicroRNAs packaged and secreted in exosomes are termed "exosomal microRNAs (miRNAs)". Nowadays, more researches have uncovered the roles of exosomal miRNAs played in BC metastasis. In this review, we recapitulated the dual actions of exosomal miRNAs exerted in the aggressiveness of BC by influencing migration, invasion, and distant metastasis. Next, we presented how exosomal miRNAs modify angiogenesis and stemness maintenance. Clinically, several exosomal miRNAs can govern the transformation between drug sensitivity and chemoresistance. Since the balance of the number and type of exosomal miRNAs is disturbed in pathological conditions, they are able to serve as instructive biomarkers for BC diagnosis and prognosis. More efforts are needed to connect the theoretical studies and clinical traits together. This review provides an outline of the pleiotropic impacts of exosomal miRNAs on BC metastasis and their clinical implications, paving the way for future personalized drugs.

miR-320a/SP1 negative reciprocal interaction contributes to cell growth and invasion in colorectal cancer

BACKGROUND

Transcription factors (TFs) may be engaged in reciprocal regulatory circuits with certain miRNAs to maintain cellular homeostasis. Disequilibrium of the reciprocities by certain tumor-related stimuli may give rise to deregulation of downstream cellular signaling pathways, thus promoting malignant tumor phenotypes. Specificity Protein 1 (SP1) is the most representative member of the tumor-related transcription factors. Previous studies disclosed that SP1 can transcriptionally regulate miRNAs and coding genes to facilitate tumor progression. In our study, we used bioinformatic analysis to predict several SP1-binding sites within the miR-320a promoter and found that SP1 is a predicted target gene of miR-320a. Therefore, we hypothesize a reciprocal regulatory link between SP1 and miR-320a that participates in colorectal cancer (CRC) development METHODS: We performed bioinformatic analysis, quantitative polymerase chain reaction (qPCR), immunoblotting, dual-luciferase reporter assays, and a series of in vitro and in vivo functional assays to describe a novel SP1/miR-320a reciprocal interaction in CRC RESULTS: First, we found that miR-320a was significantly downregulated in CRC tissues and cell lines. Consistent with findings in other cancers, miR-320a exhibited inhibitory effects on cell growth and invasion of CRC in vitro and in vivo. Moreover, we identified SP1 as a target gene of miR-320a, and ectopic SP1 expression partly abolished miR-320a-induced inhibitory effects. Conversely, we confirmed that SP1 interacts with the miR-320a promoter, leading to depression of miR-320a. This illustrates a double-negative feedback loop between miR-320a and SP1. Additionally, based on the fact that SP1 promotes MACC1 transcription, we determined via immunoblotting that the oncogenic MACC1/MET signaling pathway was inactivated in the context of miR-320a-induced SP1 downregulation CONCLUSION: Taken together, our study is the first to describe a miR-320a/SP1 negative reciprocal interaction, which contributes to cell growth and invasion in CRC through modulation of the MACC1/MET signaling pathway.

Transcriptional Regulation of ROS Homeostasis by the ERR Subfamily of Nuclear Receptors

Reactive oxygen species (ROS) such as superoxide anion (O₂^•-) and hydrogen peroxide (H₂O₂) are generated endogenously by processes such as mitochondrial oxidative phosphorylation, or they may arise from exogenous sources like bacterial invasion. ROS can be beneficial (oxidative eustress) as signaling molecules but also harmful (oxidative distress) to cells when ROS levels become unregulated in response to physiological, pathological or pharmacological insults. Indeed, abnormal ROS levels have been shown to contribute to the etiology of a wide variety of diseases. Transcriptional control of metabolic genes is a crucial mechanism to coordinate ROS homeostasis. Therefore, a better understanding of how ROS metabolism is regulated by specific transcription factors can contribute to uncovering new therapeutic strategies. A large body of work has positioned the estrogen-related receptors (ERRs), transcription factors belonging to the nuclear receptor superfamily, as not only master regulators of cellular energy metabolism but, most recently, of ROS metabolism. Herein, we will review the role played by the ERRs as transcriptional regulators of ROS generation and antioxidant mechanisms and also as ROS sensors. We will assess how the control of ROS homeostasis by the ERRs can be linked to physiology and disease and the possible contribution of manipulating ERR activity in redox medicine.

LncRNA ATXN8OS enhances tamoxifen resistance in breast cancer

Background

Tamoxifen (TAMR) resistance remains a massive obstacle for breast cancer (BC) management. The precise parts of long non-coding RNA ataxin 8 opposite strand (ATXN8OS) in BC TAMR resistance have not been defined.

Methods

The levels of ATXN8OS, vasodilator-stimulated phosphoprotein (VASP), and miR-16-5p were assessed by quantitative real-time polymerase chain reaction or western blot. Colony formation and cell viability were analyzed by MTT and colony formation assays, respectively. Targeted interactions among miR-16-5p, ATXN8OS, and VASP were confirmed by dual-luciferase reporter assay. Animal studies were performed to observe the role of ATXN8OS in TAMR sensitivity in vivo.

Results

ATXN8OS expression was increased in BC tissues and cells. ATXN8OS depletion promoted BC cell sensitivity to TAMR. ATXN8OS sequestered miR-16-5p by directly binding to miR-16-5p. The promotional effect of ATXN8OS knockdown on BC cell TAMR sensitivity was mediated by miR-16-5p. VASP was a direct target of miR-16-5p, and miR-16-5p overexpression enhanced TAMR sensitivity by VASP. Moreover, ATXN8OS regulated VASP expression by acting as a miR-16-5p sponge. In addition, ATXN8OS knockdown augmented BC TAMR sensitivity in vivo.

Conclusion

ATXN8OS knockdown enhanced BC TAMR sensitivity partially through the miR-16-5p/VASP axis, highlighting a potential therapeutic target for improving the clinical benefits of TAMR treatment in BC patients.

PP2A-B55 Holoenzyme Regulation and Cancer

Protein phosphorylation is a post-translational modification essential for the control of the activity of most enzymes in the cell. This protein modification results from a fine-tuned balance between kinases and phosphatases. PP2A is one of the major serine/threonine phosphatases that is involved in the control of a myriad of different signaling cascades. This enzyme, often misregulated in cancer, is considered a tumor suppressor. In this review, we will focus on PP2A-B55, a particular holoenzyme of the family of the PP2A phosphatases whose specific role in cancer development and progression has only recently been highlighted. The discovery of the Greatwall (Gwl)/Arpp19-ENSA cascade, a new pathway specifically controlling PP2A-B55 activity, has been shown to be frequently altered in cancer. Herein, we will review the current knowledge about the mechanisms controlling the formation and the regulation of the activity of this phosphatase and its misregulation in cancer.

Regulation of the expression of the estrogen related receptors (ERRs)

Estrogen related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several tissues and cells and they display various physiological and pathological functions, controlling, amongst others and depending on the receptor, bone homeostasis, energy metabolism, embryonic stem cell pluripotency, and cancer progression. In contrast to classical nuclear receptors, the activities of the ERRs are not controlled by a natural ligand. Regulation of their activities thus rely on other means such as post-translational modification or availability of transcriptional co-regulators. In addition, regulation of their mere expression under given physiological or pathological conditions is a particularly important level of control. Here we discuss the mechanisms involved in the regulation of ERRs expression and the reported means to impact on it using pharmacological approaches.

1H, 13C and 15N NMR chemical shift assignments of cAMP-regulated phosphoprotein-19 and -16 (ARPP-19 and ARPP-16)

Protein Phosphatase 2A, PP2A, the principal Serine/threonine phosphatase, has major roles in broad range of signaling pathways that include regulation of cell cycle, cell proliferation and neuronal signaling. The loss of function of PP2A is linked with many human diseases, like cancer and neurodegenerative disorders. Protein phosphatase 2A (PP2A) functions as tumor suppressor and its tumor suppressor activity is inhibited by the overexpression of PP2A inhibitor proteins in most of the cancers. ARPP-19/ARPP-16 has been identified as one of the potential PP2A inhibitor proteins. Here, we report the resonance assignment of backbone ¹H, ¹³C and ¹⁵N atoms of human ARPP-19 and ARPP-16 proteins. These chemical shift values can provide valuable information for the further study of the dynamics and interaction of ARPP-proteins to PP2A using NMR spectroscopy.

Exosomes: Insights from Retinoblastoma and Other Eye Cancers

Exosomes, considered as cell debris or garbage bags, have been later characterized as nanometer-sized extracellular double-membrane lipid bilayer bio-vesicles secreted by the fusion of vesicular bodies with the plasma membrane. The constituents and the rate of exosomes formation differ in different pathophysiological conditions. Exosomes are also observed and studied in different parts of the eye, like the retina, cornea, aqueous, and vitreous humor. Tear fluid consists of exosomes that are shown to regulate various cellular processes. The role of exosomes in eye cancers, especially retinoblastoma (RB), is not well explored, although few studies point towards their presence. Retinoblastoma is an intraocular tumor that constitutes 3% of cases of cancer in children. Diagnosis of RB may require invasive procedures, which might lead to the spread of the disease to other parts. Due to this reason, better ways of diagnosis are being explored. Studies on the exosomes in RB tumors and serum might help designing better diagnostic approaches for RB. In this article, we reviewed studies on exosomes in the eye, with a special emphasis on RB. We also reviewed miRNAs expressed in RB tumor, serum, and cell lines and analyzed the targets of these miRNAs from the proteins identified in the RB tumor exosomes. hsa-miR-494 and hsa-miR-9, upregulated and downregulated, respectively in RB, have the maximum number of targets. Although oppositely regulated, they share the same targets in the proteins identified in RB tumor exosomes. Overall this review provides the up-to-date progress in the area of eye exosome research, with an emphasis on RB.

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.

ARPP-19 Mediates Herceptin Resistance via Regulation of CD44 in Gastric Cancer

Purpose

As the first-line drug for treatment of HER2-positive metastatic gastric cancer (GC), Herceptin exhibits significant therapeutic efficacy. However, acquired resistance of Herceptin limits the therapeutic benefit of gastric cancer patients, in which the molecular mechanisms remain to be further determined.

Methods

Quantitative real-time polymerase chain reaction was performed to detect the mRNA levels of ARPP-19 and CD44 in GC cells. Protein levels were determined using Western blot and IHC staining. MTT and soft agar colony formation assays were used to measure cell proliferation. Xenograft model was established to verify the functional role of ARPP-19 in Herceptin resistance in vivo. Sphere formation assay was conducted to determine cell stemness.

Results

We observed ARPP-19 was up-regulated in Herceptin resistance gastric cancer cells NCI-N87-HR and MKN45-HR. The forced expression of ARPP-19 promoted, whereas the silencing of ARPP-19 impaired Herceptin resistance of HER2-positive gastric cancer cells both in vitro and in vivo. Moreover, ARPP-19 significantly enhanced the sphere formation capacity and CD44 expression, CD44 was also a positive factor of Herceptin resistance in HER2-positive gastric cancer cells. In addition, high level of ARPP-19 was positively associated with Herceptin resistance and poor survival rate of gastric cancer patients.

Conclusion

We have demonstrated that ARPP-19 promoted Herceptin resistance of gastric cancer via up-regulation of CD44, our study suggested that ARPP-19 could be a potential diagnostic and therapeutic candidate for HER2-positive gastric cancer.

Perspectives on the Role of Non-Coding RNAs in the Regulation of Expression and Function of the Estrogen Receptor

Estrogen receptors (ERs) comprise several nuclear and membrane-bound receptors with different tissue-specific functions. ERα and ERβ are two nuclear members of this family, whereas G protein-coupled estrogen receptor (GPER), ER-X, and Gq-coupled membrane estrogen receptor (Gq-mER) are membrane-bound G protein-coupled proteins. ERα participates in the development and function of several body organs such as the reproductive system, brain, heart and musculoskeletal systems. ERβ has a highly tissue-specific expression pattern, particularly in the female reproductive system, and exerts tumor-suppressive roles in some tissues. Recent studies have revealed functional links between both nuclear and membrane-bound ERs and non-coding RNAs. Several oncogenic lncRNAs and miRNAs have been shown to exert their effects through the modulation of the expression of ERs. Moreover, treatment with estradiol has been shown to alter the malignant behavior of cancer cells through functional axes composed of non-coding RNAs and ERs. The interaction between ERs and non-coding RNAs has functional relevance in several human pathologies associated with estrogen regulation, such as cancers, intervertebral disc degeneration, coronary heart disease and diabetes. In the current review, we summarize scientific literature on the role of miRNAs and lncRNAs on ER-associated signaling and related disorders.

MiR-320a is associated with cisplatin resistance in lung adenocarcinoma and its clinical value in non-small cell lung cancer: A comprehensive analysis based on microarray data

BACKGROUND

Currently, the main treatment for non-small cell lung cancer (NSCLC) is surgery and chemotherapy. Although major progress has been made in targeted treatment and immunotherapy, the survival rates for this disease are still low and associated with resistance to chemotherapy. Previous studies have shown that histone acetylation and microRNAs (miRNAs) might play an important role in chemotherapy resistance. The aim of this study was to identify candidate miRNAs related to cisplatin (DDP) resistance in lung adenocarcinoma.

METHODS

We used 5-aza-2'-deoxycytidine and trichostatin A to reverse the drug resistance of A549/DDP cells in vitro, and miRNA expression profiling was performed by microarrays to identify candidate miRNAs. In addition, we investigated the correlations between miR-320a expression and clinical characteristics through data collected from Gene Expression Omnibus (GEO) microarrays, and The Cancer Genome Atlas (TCGA) to determine the clinical role of miR-320a in lung adenocarcinoma. Furthermore, we investigated the biological function of miR-320a. TargetScanHuman, PicTar2005 and miRanda v5.1. were used to predict the target genes of miR-320a; then, the function of these genes were suggested from the enrichment of GO categories items and KEGG analyses.

RESULTS

Treatment with 5-Aza-dc significantly inhibited cellular proliferation, and increased apoptosis in the A549/DDP cells compared with the untreated cells. TSA did not reverse cisplatin resistance. MiR-320a was up-regulated during reversal of cisplatin resistance. The lung adenocarcinoma groups had a significantly lower level of miR-320a expression than the control groups. For the bioinformatics analyses, we found some target genes involved in cell cycle progression, tumor progression, the MAPK signaling pathway, and the ErbB signaling pathway. The promising target genes were highly enriched in various pathways in cancer.

CONCLUSIONS

The current study confirmed miR-320a was up-regulated during the revering of cisplatin resistance. The results of bioinformatics analyses may present a new method for investigating the pathogenesis of lung adenocarcinoma.

PSF Promotes ER-Positive Breast Cancer Progression via Posttranscriptional Regulation of ESR1 and SCFD2

Endocrine therapy is standard treatment for estrogen receptor (ER)-positive breast cancer, yet long-term treatment often causes acquired resistance, which results in recurrence and metastasis. Recent studies have revealed that RNA-binding proteins (RBP) are involved in tumorigenesis. Here, we demonstrate that PSF/SFPQ is an RBP that potentially predicts poor prognosis of patients with ER-positive breast cancer by posttranscriptionally regulating ERα (ESR1) mRNA expression. Strong PSF immunoreactivity correlated with shorter overall survival in patients with ER-positive breast cancer. PSF was predominantly expressed in a model of tamoxifen-resistant breast cancer cells, and depletion of PSF attenuated proliferation of cultured cells and xenografted tumors. PSF expression was significantly associated with estrogen signaling. PSF siRNA downregulated ESR1 mRNA by inhibiting nuclear export of the RNA. Integrative analyses of microarray and RNA immunoprecipitation sequencing also identified SCFD2, TRA2B, and ASPM as targets of PSF. Among the PSF targets, SCFD2 was a poor prognostic indicator of breast cancer and SCFD2 knockdown significantly suppressed breast cancer cell proliferation. Collectively, this study shows that PSF plays a pathophysiologic role in ER-positive breast cancer by posttranscriptionally regulating expression of its target genes such as ESR1 and SCFD2. Overall, PSF and SCFD2 could be potential diagnostic and therapeutic targets for primary and hormone-refractory breast cancers. SIGNIFICANCE: This study defines oncogenic roles of RNA-binding protein PSF, which exhibits posttranscriptional regulation in ER-positive breast cancer.

LncRNA IGFL2-AS1 functions as a ceRNA in regulating ARPP19 through competitive binding to miR-802 in gastric cancer

Gastric cancer (GC) is one of the most common malignancies of the digestive system worldwide. Multiple long noncoding RNAs (lncRNAs) participate in the regulation of GC development and metastasis. In this study, we aimed to elucidate the expression and function of lncRNA IGFL2-AS1 in GC. We found that IGFL2-AS1 was highly expressed in GC tissues and cell lines. Knockdown of IGFL2-AS1 suppressed GC cell proliferation, migration, and invasion in vitro. Furthermore, we identified that IGFL2-AS1 exerted its function as a molecular sponge of miR-802. MiR-802 was demonstrated to be a tumor suppressor, and overexpression of miR-802 suppressed GC cell growth, migration, and invasion. Mechanistically, we revealed that the cAMP-regulated phosphoprotein 19 (ARPP19) was a direct target of miR-802 and could reverse the inhibitory function of miR-802. Moreover, our results confirmed that knockdown of IGFL2-AS1 inhibited GC tumor development in an in vivo GC tumor xenograft model. In summary, our data suggest that the IGFL2-AS1/miR-802/ARPP19 axis plays a critical role in the progression and metastasis of GC. Therapies targeting the IGFL2-AS1/miR-802/ARPP19 axis can potentially improve GC treatment.

HDAC5-mediated deacetylation and nuclear localisation of SOX9 is critical for tamoxifen resistance in breast cancer

BACKGROUND

Tamoxifen resistance remains a significant clinical challenge for the therapy of ER-positive breast cancer. It has been reported that the upregulation of transcription factor SOX9 in ER⁺ recurrent cancer is sufficient for tamoxifen resistance. However, the mechanisms underlying the regulation of SOX9 remain largely unknown.

METHODS

The acetylation level of SOX9 was detected by immunoprecipitation and western blotting. The expressions of HDACs and SIRTs were evaluated by qRT-PCR. Cell growth was measured by performing MTT assay. ALDH-positive breast cancer stem cells were evaluated by flow cytometry. Interaction between HDAC5 and SOX9 was determined by immunoprecipitation assay.

RESULTS

Deacetylation is required for SOX9 nuclear translocation in tamoxifen-resistant breast cancer cells. Furthermore, HDAC5 is the key deacetylase responsible for SOX9 deacetylation and subsequent nuclear translocation. In addition, the transcription factor C-MYC directly promotes the expression of HDAC5 in tamoxifen resistant breast cancer cells. For clinical relevance, high SOX9 and HDAC5 expression are associated with lower survival rates in breast cancer patients treated with tamoxifen.

CONCLUSIONS

This study reveals that HDAC5 regulated by C-MYC is essential for SOX9 deacetylation and nuclear localisation, which is critical for tamoxifen resistance. These results indicate a potential therapy strategy for ER⁺ breast cancer by targeting C-MYC/HDAC5/SOX9 axis.

Clinical Theragnostic Relationship between Drug-Resistance Specific miRNA Expressions, Chemotherapeutic Resistance, and Sensitivity in Breast Cancer: A Systematic Review and Meta-Analysis

Awareness of breast cancer has been increasing due to early detection, but the advanced disease has limited treatment options. There has been growing evidence on the role of miRNAs involved in regulating the resistance in several cancers. We performed a comprehensive systematic review and meta-analysis on the role of miRNAs in influencing the chemoresistance and sensitivity of breast cancer. A bibliographic search was performed in PubMed and Science Direct based on the search strategy, and studies published until December 2018 were retrieved. The eligible studies were included based on the selection criteria, and a detailed systematic review and meta-analysis were performed based on PRISMA guidelines. A random-effects model was utilised to evaluate the combined effect size of the obtained hazard ratio and 95% confidence intervals from the eligible studies. Publication bias was assessed with Cochran’s Q test, I² statistic, Orwin and Classic fail-safe N test, Begg and Mazumdar rank correlation test, Duval and Tweedie trim and fill calculation and the Egger’s bias indicator. A total of 4584 potential studies were screened. Of these, 85 articles were eligible for our systematic review and meta-analysis. In the 85 studies, 188 different miRNAs were studied, of which 96 were upregulated, 87 were downregulated and 5 were not involved in regulation. Overall, 24 drugs were used for treatment, with doxorubicin being prominently reported in 15 studies followed by Paclitaxel in 11 studies, and 5 drugs were used in combinations. We found only two significant HR values from the studies (miR-125b and miR-4443) and our meta-analysis results yielded a combined HR value of 0.748 with a 95% confidence interval of 0.508–1.100; p-value of 0.140. In conclusion, our results suggest there are different miRNAs involved in the regulation of chemoresistance through diverse drug genetic targets. These biomarkers play a crucial role in guiding the effective diagnostic and prognostic efficiency of breast cancer. The screening of miRNAs as a theragnostic biomarker must be brought into regular practice for all diseases. We anticipate that our study serves as a reference in framing future studies and clinical trials for utilising miRNAs and their respective drug targets.

Cell Division Cycle Associated 8 Is a Key Regulator of Tamoxifen Resistance in Breast Cancer

Purpose

Breast cancer (BC) is one of the most common malignancies globally, and millions of women worldwide are diagnosed with BC every year. Up to 70% of BC patients are estrogen receptor (ER)-positive. Numerous studies have shown that tamoxifen has a significant therapeutic effect on both primary and metastatic ER-positive BC patients. Although tamoxifen is currently one of the most successful therapeutic agents for BC, a significant proportion of patients will eventually become resistant to tamoxifen, leading to tumor recurrence and metastasis. Knowledge about the development of tamoxifen resistance in BC patients is still limited.

Methods

We applied a loss-and-gain method to study the biological functional role of cell division cycle associated 8 (CDCA8) in tamoxifen resistance in BC cells.

Results

We found that CDCA8 was significantly elevated in tamoxifen-resistant BC cells. Knockdown of CDCA8 expression significantly inhibited the proliferation of tamoxifen-resistant BC cells and reduced their resistance to tamoxifen. In contrast, overexpression of CDCA8 promoted the growth of tamoxifen-sensitive BC cells and induced their resistance to tamoxifen.

Conclusion

In this study, we reported that CDCA8 is a key regulator of tamoxifen resistance in BC, suggesting that CDCA8 may serve as a potential therapeutic target for BC treatment.

LINC00162 confers sensitivity to 5-Aza-2'-deoxycytidine via modulation of an RNA splicing protein, HNRNPH1

DNA demethylation therapy is now expanding from hematological tumors to solid tumors. To exploit its maximum efficacy, long-term treatment is needed, and stratification of sensitive patients is critically important. Here, we identified a long non-coding RNA, LINC00162, as highly and frequently expressed in gastric cancer cell lines sensitive to 5-aza-2'-deoxycytidine (5-aza-dC). Knockdown of LINC00162 decreased the sensitivity while its overexpression increased the sensitivity. In vivo experiments also showed that LINC00162 overexpression increased the sensitivity. LINC00162 enhanced cell cycle arrest and apoptosis induced by 5-aza-dC, but did not affect its DNA demethylation effect. Mechanistically, LINC00162 interacted with an RNA splicing protein, HNRNPH1, and decreased splicing of an anti-apoptotic splicing variant, BCL-XL. LINC00162 may have translational value to predict patients who will respond to 5-aza-dC.

Endocrine Resistance in Hormone Receptor Positive Breast Cancer-From Mechanism to Therapy

The importance and role of the estrogen receptor (ER) pathway has been well-documented in both breast cancer (BC) development and progression. The treatment of choice in women with metastatic breast cancer (MBC) is classically divided into a variety of endocrine therapies, 3 of the most common being: selective estrogen receptor modulators (SERM), aromatase inhibitors (AI) and selective estrogen receptor down-regulators (SERD). In a proportion of patients, resistance develops to endocrine therapy due to a sophisticated and at times redundant interference, at the molecular level between the ER and growth factor. The progression to endocrine resistance is considered to be a gradual, step-wise process. Several mechanisms have been proposed but thus far none of them can be defined as the complete explanation behind the phenomenon of endocrine resistance. Although multiple cellular, molecular and immune mechanisms have been and are being extensively studied, their individual roles are often poorly understood. In this review, we summarize current progress in our understanding of ER biology and the molecular mechanisms that predispose and determine endocrine resistance in breast cancer patients.

microRNA-98 inhibits the proliferation, invasion, migration and promotes apoptosis of breast cancer cells by binding to HMGA2

Breast cancer is a major contributor leading to cancer death in females worldwide. The aim of the present study was to investigate the effects of microRNA-98 (miR-98) on the processes of cell proliferation, invasion, migration and apoptosis by binding to high-mobility group AT-hook 2 (HMGA2) in breast cancer. Breast cancer tissues and adjacent normal tissues were collected from 112 patients suffering from breast cancer. The target relationship between miR-98 and HMGA2 was verified by in connection with the bioinformatics website as well as a dual-luciferase reporter assay, both of which provided evidence indicating that HMGA2 was a target gene of miR-98. Human breast cancer MDA-MB-231 cells were treated with miR-98 mimics, miR-98 inhibitors, siRNA-HMGA2 or miR-98 inhibitors + siRNA-HMGA2. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry methods were performed to determine cell proliferation, cell cycle and apoptosis, respectively, while a Transwell assay was employed to detect cell migration and invasion. Breast cancer tissues exhibited decreased miR-98 expression, while increased expression levels of HMGA2 were recorded. The mRNA and protein expressions of HMGA2, cell proliferation, cells at the S phase, cell migration, invasion, expressions of matrix metalloproteinase (MMP)2 as well as MMP9 were all reduced in response to miR-98 mimics or siRNA-HMGA2, while a contradictory trend was observed in the miR-98 inhibitors group. In conclusion, the results of the study demonstrate that miR-98 inhibits cell proliferation, migration and invasion, while acting to promote apoptosis by negatively regulating HMGA2 in breast cancer.

Integrated molecular analysis of Tamoxifen-resistant invasive lobular breast cancer cells identifies MAPK and GRM/mGluR signaling as therapeutic vulnerabilities

Invasive lobular breast cancer (ILC) is an understudied malignancy with distinct clinical, pathological, and molecular features that distinguish it from the more common invasive ductal carcinoma (IDC). Mounting evidence suggests that estrogen receptor-alpha positive (ER+) ILC has a poor response to Tamoxifen (TAM), but the mechanistic drivers of this are undefined. In the current work, we comprehensively characterize the SUM44/LCCTam ILC cell model system through integrated analysis of gene expression, copy number, and mutation, with the goal of identifying actionable alterations relevant to clinical ILC that can be co-targeted along with ER to improve treatment outcomes. We show that TAM has several distinct effects on the transcriptome of LCCTam cells, that this resistant cell model has acquired copy number alterations and mutations that impinge on MAPK and metabotropic glutamate receptor (GRM/mGluR) signaling networks, and that pharmacological inhibition of either improves or restores the growth-inhibitory actions of endocrine therapy.

Endometrial pinopode biomarkers: Molecules and microRNAs

Ultrastructural changes on the apical surface of the luminal epithelium of the uterus are known as pinopodes. Their morphology in species and in special species is associated with different results about size, duration, and percentage of surface area covered by pinopodes. The content of pinopodes is different in rodents and humans. In mice and rats pinopodes have many vacuoles and no organelle that extends to the actin stalk above the microvilli. Human pinopodes do not have a large vacuole and contain the golgi complex, a rough endoplasmic reticulum, secretory vesicles, and mitochondria that extend from the entire cell surface. It has been suggested that pinopodes are good markers of endometrial receptivity and implantation window. There are several molecular markers related to the presence of pinopodes, including integrins, leukemia inhibiting factor (LIF), l-selectin, HOXA10, glutaredoxin, glycodelinA, heparin-binding epidermal growth factor, mucins, and microRNAs (miRNAs). Multiple lines of evidence have indicated that miRNAs could affect the expression of LIF and pinopodes in the endometrium and these molecules play key roles in implantation window processes. Here, we have summarized the morphology and function of pinopodes. Moreover, we have highlighted several molecules in relation to pinopodes that could be used as biomarkers.

Downregulation of LINC00894-002 Contributes to Tamoxifen Resistance by Enhancing the TGF-β Signaling Pathway

Tamoxifen is a widely used personalized medicine for estrogen receptor (ER)-positive breast cancer, but approximately 30% of patients receiving the treatment relapse due to tamoxifen resistance (TamR). Recently, several reports have linked lncRNAs to cancer drug resistance. However, the role of lncRNAs in TamR is unclear. To identify TamR-related lncRNAs, we first used a bioinformatic approach to predict whether they have connection with known TamR-associated genes by starBase v2.0 and divided them into two groups. Group A contains lncRNAs that connect with known TamR genes and group B contains lncRNAs that show no predicted interaction. Among the 12 lncRNAs in group A, 58.3% of them are either up- or downregulated in MCF-7/TamR cells compared to the sensitive cells. In contrast, the expression levels of all group B lncRNAs are not changed in MCF-7/TamR cells. LINC00894-002 exhibits the most sophisticated network pattern and is the most downregulated lncRNA in MCF-7/TamR cells. Moreover, we find that LINC00894-002 is directly upregulated by ERα. Knocking down LINC00894-002 downregulates expression of miR-200a-3p and miR-200b-3p, upregulates the expression of TGF-β2 and ZEB1, and finally contributes to TamR. Herein, we report the first case of an inhibitory lncRNA against TamR through the miR-200-TGF-β2-ZEB1 signaling pathway.

MiR-26a inhibits thyroid cancer cell proliferation by targeting ARPP19

miRNA, which involves in pathogenesis of thyroid cancer via different targets, has been found aberrantly expressed in thyroid cancer. Modes of actions of miR-26a in papillary thyroid carcinoma (PTC), however, have not been fully understood to this date. In vitro results obtained from this research confirmed miR-26a was down-regulated in PTC cells (i.e. TPC-1 and BCPAP) where the down-regulation of miR-26a was found to be able to promote cell proliferation. In order to explore the mechanisms, potential targets of miR-26a were postulated: cAMP regulated phosphoprotein 19 (ARPP19) turned out to be the target of miR-26a and it was by depleting ARPP19 was the cell proliferation be suppressed. This suggested that miR-26a regulated cell proliferation by targeting ARPP19. In addition, such a depletion of ARPP19 sensitized PTC cells to tamoxifen (TMX) treatment. The above findings indicated miR-26a was a target of interest regarding the treatment of refractory thyroid carcinomas.

LMO4 mediates trastuzumab resistance in HER2 positive breast cancer cells

Breast cancer is the leading cause of cancer-related mortality in women worldwide. Trastuzumab (Herceptin) is an effective antibody drug for HER2 positive breast cancer; de novo or acquired trastuzumab resistance retarded the use of trastuzumab for at least 70% of HER2 positive breast cancers. In this study, we reported LMO4 (a member of LIM-only proteins) promoted trastuzumab resistance in human breast cancer cells. Over-expression of LMO4 was observed in acquired trastuzumab resistance breast cancer cells SKBR3 HR and BT474 HR. Depletion of LMO4 partly abolished the trastuzumab resistance of SKBR3 HR and BT474 HR cells. Forced expression of LMO4 significantly increased trastuzumab resistance of HER2 positive breast cancer cells both in vitro and in vivo. BCL-2 was regulated by LMO4 and mediated the promoting role of LMO4 in trastuzumab resistance of HER2 positive breast cancer cells. High level of LMO4 was associated with worse clinicopathological parameters (including tumor size and histological grade) and lower survival rate in HER2 positive breast cancer patients. LMO4 therefore could be used as a target to develop diagnostic and therapeutic methods for human HER2 positive breast cancer.

Functional miRNAs in breast cancer drug resistance

Owing to improved early surveillance and advanced therapy strategies, the current death rate due to breast cancer has decreased; nevertheless, drug resistance and relapse remain obstacles on the path to successful systematic treatment. Multiple mechanisms responsible for drug resistance have been elucidated, and miRNAs seem to play a major part in almost every aspect of cancer progression, including tumorigenesis, metastasis, and drug resistance. In recent years, exosomes have emerged as novel modes of intercellular signaling vehicles, initiating cell–cell communication through their fusion with target cell membranes, delivering functional molecules including miRNAs and proteins. This review particularly focuses on enumerating functional miRNAs involved in breast cancer drug resistance as well as their targets and related mechanisms. Subsequently, we discuss the prospects and challenges of miRNA function in drug resistance and highlight valuable approaches for the investigation of the role of exosomal miRNAs in breast cancer progression and drug resistance.

Antimitotic activity of DY131 and the estrogen-related receptor beta 2 (ERRβ2) splice variant in breast cancer

Breast cancer remains a leading cause of cancer-related death in women, and triple negative breast cancer (TNBC) lacks clinically actionable therapeutic targets. Death in mitosis is a tumor suppressive mechanism that occurs in cancer cells experiencing a defective M phase. The orphan estrogen-related receptor beta (ERRβ) is a key reprogramming factor in murine embryonic and induced pluripotent stem cells. In primates, ERRβ is alternatively spliced to produce several receptor isoforms. In cellular models of glioblastoma, short form (ERRβsf) and beta2 (ERRβ2) splice variants differentially regulate cell cycle progression in response to the synthetic agonist DY131, with ERRβ2 driving arrest in G2/M.The goals of the present study are to determine the cellular function(s) of ligand-activated ERRβ splice variants in breast cancer and evaluate the potential of DY131 to serve as an antimitotic agent, particularly in TNBC. DY131 inhibits growth in a diverse panel of breast cancer cell lines, causing cell death that involves the p38 stress kinase pathway and a bimodal cell cycle arrest. ERRβ2 facilitates the block in G2/M, and DY131 delays progression from prophase to anaphase. Finally, ERRβ2 localizes to centrosomes and DY131 causes mitotic spindle defects. Targeting ERRβ2 may therefore be a promising therapeutic strategy in breast cancer.

GSE1 predicts poor survival outcome in gastric cancer patients by SLC7A5 enhancement of tumor growth and metastasis

Gastric cancer remains a malignancy with poor survival outcome. We herein report that GSE1, a proline-rich protein, possesses a role in the progression of human gastric cancer. The expression of GSE1 was observed to be much higher in human gastric cancer tissues compared with normal gastric tissues, and GSE1 expression correlated positively with lymph node metastasis, histological grade, depth of invasion, and clinical stage in gastric cancer patients. Moreover, GSE1 expression was also associated with decreased post-operative relapse-free survival and overall survival in the cohort. The forced expression of GSE1 in gastric cancer cell lines resulted in increased cell proliferation, increased colony formation, enhanced cell migration, and invasion. Furthermore, forced expression of GSE1 also increased tumor size and enhanced lung metastasis in xenograft models. The depletion of endogenous GSE1 with shRNAs decreased the oncogenicity and invasiveness of gastric cancer cells both in vitro and in vivo In addition, GSE1 was determined to be a direct target of miR-200b and miR-200c. Furthermore, GSE1 positively regulated the downstream gene SLC7A5 (also known as LAT-1), which was scanned and verified from mRNA sequencing. GSE1 therefore possesses an oncogenic role in human gastric cancer, and targeted therapeutic approaches to inhibit GSE1 function in gastric cancer warrant further consideration.

miRNAs involved in LY6K and estrogen receptor α contribute to tamoxifen-susceptibility in breast cancer

Estrogen receptor-alpha (ERα) is a clinically important therapeutic target for breast cancer. However, tumors that lose ERα are less responsive to anti-estrogens such as tamoxifen. MicroRNAs (miRNAs) are small RNAs that regulate expression of their target gene and dysregulations of miRNA has been identified in many diseases including human cancer. However, only a few miRNAs associated with tamoxifen resistance has been reported. In this study, we found that lymphocyte antigen 6 complex (LY6K), which is a member of the Ly-6/μPAR superfamily and related to breast cancer progression and metastasis, is inversely correlated with ERα expression. We, for the first time, found miRNAs involved in the regulatory molecular mechanism between ERα and LY6K and related to tamoxifen susceptibility in breast cancer. miR-192-5p, induced by LY6K, downregulates ERα directly and induced tamoxifen resistance in ERα-positive breast cancer cells. In addition, re-expression of ERα in ERα-negative breast cancer cells increased miR-500a-3p expression and directly inhibits LY6K expression. Ectopic expression of miR-500a-3p sensitized ERα-negative cells to tamoxifen by increasing apoptosis. Finally, we observed an inverse correlation between LY6K and ERα in primary breast cancer samples. We found that patients with recurrence showed high expression of miR-192-5p after tamoxifen treatments. In addition, expression of miR-500a-3p was significantly correlated to survival outcome. As miRNAs involved in the regulatory mechanism between LY6K and ERα can affect tamoxifen resistance, downregulating miR-192-5p or re-expressing miR-500a-3p could be a potential therapeutic approach for treating tamoxifen resistant patients.

MiRNA-320a inhibits trophoblast cell invasion by targeting estrogen-related receptor-gamma

AIM

MicroRNAs (miRs) play an essential role in the modulation of trophoblast function. We explored miR-320a expression in the human placenta. In addition, we report the promising effect and target functional loop of miR-320a in trophoblasts.

METHODS

MiR-320a expression was investigated in both pre-eclamptic and healthy placenta tissues by quantitative real time-polymerase chain reaction to determine how miR-320a affected invasion, proliferation and migration in trophoblasts. A lipopolysaccharide (LPS) model was established in trophoblasts to reveal how LPS supplementation stimulated miR-320a expression. Western blot was applied to measure protein expression, which was involved in pathways modulated by miR-320a in pre-eclamptic placentas.

RESULTS

MiR-320a expression was enhanced in the placental specimens of pre-eclamptic patients. Excessive miR-320a expression remarkably suppressed trophoblast invasion but did not affect migration or proliferation. However, transfection with miR-320a inhibitor reinforced trophoblast invasion in vitro. Luciferase assays verified that estrogen-related receptor-gamma (ERRγ) served as a direct target of miR-320a. Quantitative real-time polymerase chain reaction and Western blot demonstrated that excessive miR-320a expression downregulated ERRγ transcription and translation. Additionally, LPS supplementation showed excessive miR-320a expression and ERRγ downregulation. Impaired ERRγ and enhanced miR-320a expression occurred in PE placentas compared to controls. Pearson correlation and linear regression analysis revealed that miR-320a expression was negatively related to ERRγ expression in normal and pre-eclamptic placentas.

CONCLUSIONS

These findings indicate that miR-320a overexpression causes anomalous placentation by targeting ERRγ. Our research reveals the promising effect of miR-320a and the ERRγ functional loop on placentation.