Twist1 and Slug mediate H2AX-regulated epithelial-mesenchymal transition in breast cells

MicroRNA-495: a therapeutic and diagnostic tumor marker

Therapeutic and diagnostic progresses have significantly reduced the mortality rate among cancer patients during the last decade. However, there is still a high rate of mortality among cancer patients. One of the important reasons involved in the high mortality rate is the late diagnosis in advanced tumor stages that causes the failure of therapeutic strategies in these patients. Therefore, investigating the molecular mechanisms involved in tumor progression has an important role in introducing the efficient early detection markers. MicroRNAs (miRNAs) as stable factors in body fluids are always considered as non-invasive diagnostic and prognostic markers. In the present review, we investigated the role of miR-495 in tumor progression. It has been reported that miR-495 has mainly a tumor suppressor function through the regulation of transcription factors and tyrosine kinases as well as cellular processes such as multidrug resistance, chromatin remodeling, and signaling pathways. This review can be an effective step towards introducing the miR-495 as a non-invasive diagnostic/prognostic marker as well as a suitable target in tumor therapy.

Nuclear envelope, chromatin organizers, histones, and DNA: The many achilles heels exploited across cancers

In eukaryotic cells, the genome is organized in the form of chromatin composed of DNA and histones that organize and regulate gene expression. The dysregulation of chromatin remodeling, including the aberrant incorporation of histone variants and their consequent post-translational modifications, is prevalent across cancers. Additionally, nuclear envelope proteins are often deregulated in cancers, which impacts the 3D organization of the genome. Altered nuclear morphology, genome organization, and gene expression are defining features of cancers. With advances in single-cell sequencing, imaging technologies, and high-end data mining approaches, we are now at the forefront of designing appropriate small molecules to selectively inhibit the growth and proliferation of cancer cells in a genome- and epigenome-specific manner. Here, we review recent advances and the emerging significance of aberrations in nuclear envelope proteins, histone variants, and oncohistones in deregulating chromatin organization and gene expression in oncogenesis.

Transcription factors in DNA damage response

Transcription factors (TFs) constitute a wide and highly diverse group of proteins capable of controlling gene expression. Their roles in oncogenesis, tumor progression, and metastasis have been established, but recently their role in the DNA damage response pathway (DDR) has emerged. Many of them can affect elements of canonical DDR pathways, modulating their activity and deciding on the effectiveness of DNA repair. In this review, we focus on the latest reports on the effects of two TFs with dual roles in oncogenesis and metastasis (hypoxia-inducible factor-1 α (HIF1α), proto-oncogene MYC) and three epithelial-mesenchymal transition (EMT) TFs (twist-related protein 1 (TWIST), zinc-finger E-box binding homeobox 1 (ZEB1), and zinc finger protein 281 (ZNF281)) associated with control of canonical DDR pathways.

Circulating Tumor Cells in Breast Cancer Patients: A Balancing Act between Stemness, EMT Features and DNA Damage Responses

Circulating tumor cells (CTCs) traverse vessels to travel from the primary tumor to distant organs where they adhere, transmigrate, and seed metastases. To cope with these challenges, CTCs have reached maximal flexibility to change their differentiation status, morphology, migratory capacity, and their responses to genotoxic stress caused by metabolic changes, hormones, the inflammatory environment, or cytostatic treatment. A significant percentage of breast cancer cells are defective in homologous recombination repair and other mechanisms that protect the integrity of the replication fork. To prevent cell death caused by broken forks, alternative, mutagenic repair, and bypass pathways are engaged but these increase genomic instability. CTCs, arising from such breast tumors, are endowed with an even larger toolbox of escape mechanisms that can be switched on and off at different stages during their journey according to the stress stimulus. Accumulating evidence suggests that DNA damage responses, DNA repair, and replication are integral parts of a regulatory network orchestrating the plasticity of stemness features and transitions between epithelial and mesenchymal states in CTCs. This review summarizes the published information on these regulatory circuits of relevance for the design of biomarkers reflecting CTC functions in real-time to monitor therapeutic responses and detect evolving chemoresistance mechanisms.

The effect of COVID-19 derived cytokine storm on cancer cells progression: double-edged sword

OBJECTIVE

Severe acute respiratory syndrome coronavirus 2 (SARS-COV2) was first detected in Wuhan, China in December, 2019. The emerging virus causes a respiratory illness, that can trigger a cytokine storm in the body.

METHOD

Cytokine storm in patient's body is associated with severe forms of disease. It is one of the main complications of coronavirus disease-2019 (COVID-19), in which immune cells play a major role. Studies have shown immune cells in the tumor environment can be effective to induce resistance to chemotherapy in cancer patients.

RESULT

Therefore, considering the role of immune cells to induce cytokine storm in COVID-19 patients, and their role to cause resistance to chemotherapy, they are effective on disease progression and creation of severe form of disease.

CONCLUSION

By examining the signaling pathways and inducing resistance to chemotherapy in tumor cells and the cells affect them, it is possible to prevent the occurrence of severe forms of the disease in cancer patients with COVID-19; it is applicable using target therapy and other subsequent treatment strategies.

DNA double-strand break repair in cancer: A path to achieving precision medicine

The assessment of DNA damage can be a significant diagnostic for precision medicine. DNA double strand break (DSBs) pathways in cancer are the primary targets in a majority of anticancer therapies, yet the molecular vulnerabilities that underlie each tumor can vary widely making the application of precision medicine challenging. Identifying and understanding these interindividual vulnerabilities enables the design of targeted DSB inhibitors along with evolving precision medicine approaches to selectively kill cancer cells with minimal side effects. A major challenge however, is defining exactly how to target unique differences in DSB repair pathway mechanisms. This review comprises a brief overview of the DSB repair mechanisms in cancer and includes results obtained with revolutionary advances such as CRISPR/Cas9 and machine learning/artificial intelligence, which are rapidly advancing not only our understanding of determinants of DSB repair choice, but also how it can be used to advance precision medicine. Scientific innovation in the methods used to diagnose and treat cancer is converging with advances in basic science and translational research. This revolution will continue to be a critical driver of precision medicine that will enable precise targeting of unique individual mechanisms. This review aims to lay the foundation for achieving this goal.

DNA methylation and histone variants in aging and cancer

Aging-related diseases such as cancer can be traced to the accumulation of molecular disorder including increased DNA mutations and epigenetic drift. We provide a comprehensive review of recent results in mice and humans on modifications of DNA methylation and histone variants during aging and in cancer. Accumulated errors in DNA methylation maintenance lead to global decreases in DNA methylation with relaxed repression of repeated DNA and focal hypermethylation blocking the expression of tumor suppressor genes. Epigenetic clocks based on quantifying levels of DNA methylation at specific genomic sites is proving to be a valuable metric for estimating the biological age of individuals. Histone variants have specialized functions in transcriptional regulation and genome stability. Their concentration tends to increase in aged post-mitotic chromatin, but their effects in cancer are mainly determined by their specialized functions. Our increased understanding of epigenetic regulation and their modifications during aging has motivated interventions to delay or reverse epigenetic modifications using the epigenetic clocks as a rapid readout for efficacity. Similarly, the knowledge of epigenetic modifications in cancer is suggesting new approaches to target these modifications for cancer therapy.

Akt regulates RSK2 to alter phosphorylation level of H2A.X in breast cancer

Histone H2AX (H2A.X) is a variant of the histone H2A family. Phosphorylation of H2A.X is a marker of DNA strand breaks and the presence or absence of H2A.X is closely related to tumor susceptibility and drug resistance. The present study found that the activity of the serine/threonine kinase Akt was negatively associated with H2A.X phosphorylated at the Ser16 site (H2A.X S16ph), but the mechanism of the inverse relationship remains elusive. The aim of the present study was to elucidate the mechanism of action between Akt and H2A.X S16ph and the exact role of this mechanism. Western blot analysis was performed to detect the regulatory association between p-Akt and H2A.X S16ph/p-RSK2, and immunoprecipitation and chromatin immunoprecipitation were performed to prove that Akt, RSK2 and H2A.X combine and interact in human breast cancer cells. The changes of cellular proliferation and migration induced by the interaction of Akt, RSK2 and H2A.X was determined by MTT, soft agar colony formation and cell migration experiments. The effect of interaction of Akt, RSK2 and H2A.X on cancer-promoting genes, such as PSAT-1 was determined via reverse transcription-quantitative PCR analysis. The current study indicated that the serine/threonine kinase ribosomal S6 kinase 2 (RSK2) as a kinase of H2A.X could be phosphorylated by Akt at Ser19 site. Moreover, Akt positively regulated the phosphorylation of RSK2 to inhibit phosphorylation of H2A.X, thereby affecting the affinity between RSK2 and substrate histone, promoting the survival and migration of breast cancer cells. In conclusion, Akt-mediated phosphorylation of RSK2 regulated the phosphorylation of H2A.X, thereby promoting oncogenic activity. This finding provides new insights to understand the pathogenesis and treatment mechanisms of breast cancer.

Exosomes: Their Role in Pathogenesis, Diagnosis and Treatment of Diseases

Simple Summary

The aim of this review is to provide an overview of the current scientific evidence concerning the role played by exosomes in the pathogenesis, diagnosis and treatment of diseases. The potential use of exosomes as delivery vectors for small-molecule therapeutic agents will be discussed. In addition, a special emphasis will be placed on the involvement of exosomes in oncological diseases, as well as to their potential therapeutic application as liquid biopsy tools mainly in cancer diagnosis. A better understanding of exosome biology could improve the results of clinical interventions using exosomes as therapeutic agents.

Abstract

Exosomes are lipid bilayer particles released from cells into their surrounding environment. These vesicles are mediators of near and long-distance intercellular communication and affect various aspects of cell biology. In addition to their biological function, they play an increasingly important role both in diagnosis and as therapeutic agents. In this paper, we review recent literature related to the molecular composition of exosomes, paying special attention to their role in pathogenesis, along with their application as biomarkers and as therapeutic tools. In this context, we analyze the potential use of exosomes in biomedicine, as well as the limitations that preclude their wider application.

CDX2 inhibits epithelial-mesenchymal transition in colorectal cancer by modulation of Snail expression and β-catenin stabilisation via transactivation of PTEN expression

Background

Emerging evidence suggests the involvement of caudal-related homoeobox transcription factor 2 (CDX2) in tumorigenesis of various cancers. Although CDX2 functions in cancer invasion and metastasis, fewer studies focus on the role of CDX2 during the induction of epithelial–mesenchymal transition (EMT) in colorectal cancer (CRC).

Methods

Immunohistochemical analysis of CDX2 was performed. A series of in vitro and in vivo experiments were conducted to reveal the role of CDX2 in the invasion and metastasis of CRC.

Results

CDX2 was downregulated in CRC tissues and reduced CDX2 correlated with poor prognosis. Knockdown of CDX2 promoted colon cancer cell invasion in vitro and facilitated liver metastasis in vivo with inducing EMT phenotypes. Further investigation indicated that CDX2 retarded Akt and GSK-3β phosphorylation, and thereby diminished Snail expression, β-catenin stabilisation and nuclear translocation. The depletion of β-catenin neutralised the regulation of Slug and ZEB1 by CDX2 knockdown. Mechanistically, CDX2 antagonised PI3K/Akt activity in CRC by modulating PTEN expression. CDX2 directly bound to the promoter of PTEN and transactivated its expression.

Conclusions

Our study first uncovered that CDX2 inhibits EMT and metastasis of CRC by regulation of Snail expression and β-catenin stabilisation via transactivation of PTEN expression.

The Role of Histone Variants in the Epithelial-To-Mesenchymal Transition

The epithelial-to-mesenchymal transition (EMT) is a physiological process activated during early embryogenesis, which continues to shape tissues and organs later on. It is also hijacked by tumor cells during metastasis. The regulation of EMT has been the focus of many research groups culminating in the last few years and resulting in an elaborate transcriptional network buildup. However, the implication of epigenetic factors in the control of EMT is still in its infancy. Recent discoveries pointed out that histone variants, which are key epigenetic players, appear to be involved in EMT control. This review summarizes the available data on histone variants' function in EMT that would contribute to a better understanding of EMT itself and EMT-related diseases.

Genomic instability and mitochondrial homeostasis in cancer: does chromatin have a say?

While genomic instability and mitochondrial homeostasis are integral for cancer progression, how these two hallmarks interact remains poorly understood. Here, we reflect on the dialogue between chromatin-based genomic instability and impairment of mitochondrial function and depict the importance of this interaction in cancer progression to metastasis.

Inhibition of the RUNX1-CBFβ transcription factor complex compromises mammary epithelial cell identity: a phenotype potentially stabilized by mitotic gene bookmarking

RUNX1 has recently been shown to play an important role in determination of mammary epithelial cell identity. However, mechanisms by which loss of the RUNX1 transcription factor in mammary epithelial cells leads to epithelial-to-mesenchymal transition (EMT) are not known. Here, we report that interaction between RUNX1 and its heterodimeric partner CBFβ is essential for sustaining mammary epithelial cell identity. Disruption of RUNX1-CBFβ interaction, DNA binding, and association with mitotic chromosomes alters cell morphology, global protein synthesis, and phenotype-related gene expression. During interphase, RUNX1 is organized as punctate, predominantly nuclear, foci that are dynamically redistributed during mitosis, with a subset localized to mitotic chromosomes. Genome-wide RUNX1 occupancy profiles for asynchronous, mitotically enriched, and early G1 breast epithelial cells reveal RUNX1 associates with RNA Pol II-transcribed protein coding and long non-coding RNA genes and RNA Pol I-transcribed ribosomal genes critical for mammary epithelial proliferation, growth, and phenotype maintenance. A subset of these genes remains occupied by the protein during the mitosis to G1 transition. Together, these findings establish that the RUNX1-CBFβ complex is required for maintenance of the normal mammary epithelial phenotype and its disruption leads to EMT. Importantly, our results suggest, for the first time, that RUNX1 mitotic bookmarking of a subset of epithelial-related genes may be an important epigenetic mechanism that contributes to stabilization of the mammary epithelial cell identity.

Downregulation of miR-22 Contributes to Epithelial-Mesenchymal Transition in Osteosarcoma by Targeting Twist1

The epithelial-mesenchymal transition (EMT) is a vital step in osteosarcoma (OS) progression toward metastasis, but the specific molecular events governing this process are incompletely characterized, with miRNAs having increasingly been found to regulate the EMT. In this study, We assessed levels of miR-22 and its target, Twist1, via real-time PCR (qRT-PCR). We further used functional proliferation assays, measures of cell morphology, and western blotting to assess the functional relevance of miR-22 in OS and confirmed Twist1 as a miR-22 target via luciferase reporter assay. We observed a significant decrease in miR-22 levels in OS tumor samples relative to normal tissue, with such downregulating being significantly associated with tumor histological grade. When overexpressed, miR-22 impaired OS cell proliferation and EMT progression. We found Twist1 to be a direct miR-22 target, with levels of miR-22 and Twist1 mRNA being inversely correlated in patient samples. When overexpressed, miR-22 suppressed Twist1 translation and thereby attenuated the EMT in OS cells. These results clearly demonstrate that miR-22 can regulate the EMT in OS cells via targeting Twist1, thus highlighting a potentially novel pathway that can be therapeutically targeted in order to treat OS.

H19/let‑7/Lin28 ceRNA network mediates autophagy inhibiting epithelial‑mesenchymal transition in breast cancer

Long non‑coding RNA (lncRNA) H19 and Lin28 protein have been shown to participate in various pathophysiological processes, including cellular proliferation, autophagy and epithelial‑mesenchymal transition (EMT). A number of studies have investigated lncRNAs, microRNAs and mRNAs, and their roles in the initiation and progression of cancer, in doing so identifying competitive endogenous RNA (ceRNA) networks, including the H19/let‑7/Lin28 network. However, whether the H19/let‑7/Lin28 ceRNA network is involved in autophagy and EMT in breast cancer (BC) remains unclear. The present study demonstrated that the H19/let‑7/Lin28 loop was required for the downregulation of autophagy in BC cells via western blot analysis, reverse transcription‑quantitative PCR and autophagy flux monitoring. Using wound healing, migration and invasion assays, and morphological assays, the H19/let‑7/Lin28 loop was revealed to promote EMT in BC cells. Moreover, the H19/let‑7/Lin28 network was found to contribute to autophagy by inhibiting EMT in BC cells. To the best of our knowledge, the present study is the first to suggest the important roles of the H19/let‑7/Lin28 ceRNA network in BC autophagy and EMT, thus providing insight for the use of these molecules as prognostic biomarkers and therapeutic targets in BC metastasis.

EMT and Stemness-Key Players in Pancreatic Cancer Stem Cells

Metastasis and tumor progression are the major cause of death in patients suffering from pancreatic ductal adenocarcinoma. Tumor growth and especially dissemination are typically associated with activation of an epithelial-to-mesenchymal transition (EMT) program. This phenotypic transition from an epithelial to a mesenchymal state promotes migration and survival both during development and in cancer progression. When re-activated in pathological contexts such as cancer, this type of developmental process confers additional stemness properties to specific subsets of cells. Cancer stem cells (CSCs) are a subpopulation of cancer cells with stem-like features that are responsible for the propagation of the tumor as well as therapy resistance and cancer relapse, but also for circulating tumor cell release and metastasis. In support of this concept, EMT transcription factors generate cells with stem cell properties and mediate chemoresistance. However, their role in pancreatic ductal adenocarcinoma metastasis remains controversial. As such, a better characterization of CSC populations will be crucial in future development of therapies targeting these cells. In this review, we will discuss the latest updates on the mechanisms common to pancreas development and CSC-mediated tumor progression.

CUL1 Knockdown Attenuates the Adhesion, Invasion, and Migration of Triple-Negative Breast Cancer Cells via Inhibition of Epithelial-Mesenchymal Transition

Cullin-1 (CUL1) is an important factor for tumor growth and a potential therapeutic target for breast cancer therapy, but the molecular mechanism in triple-negative breast cancer (TNBC) is unknown. In the present study, CUL1 shRNA was transfected into BT549 and MDA-MB-231 breast cancer cells. Cell morphology, adhesion, invasion, and migration assays were carried out in the CUL1 knockdown cells. Additionally, protein expression levels of epithelial-mesenchymal transition (EMT)-related factors, Akt phosphorylation at S473 (pAkt), glycogen synthase kinase-3β phosphorylation at ser9 (pGSK3β), cytoplasmic and nuclear β-catenin, and epidermal growth factor receptor phosphorylation at Tyr1068 (pEGFR) were detected by Western blot analysis. CUL1 knockdown significantly suppressed the adhesion, invasion and migration capabilities of the cells, and decreased the expression of Snail1/2, ZEB1/2, Twist1/2, Vimentin, and increased the expression of Cytokeratin 18 (CK18). Moreover, CUL1 knockdown significantly downregulated the phosphorylated levels of Akt, GSK3β, and EGFR, inhibiting the translocation of β-catenin from the cytoplasm to the nucleus. The results indicate that CUL1 knockdown prohibited the metastasis behaviors of breast cancer cells through downregulation (dephosphorylation) of the EMT signaling pathways of EGFR and Akt/GSK3β/β-catenin in breast cancer. These results strongly suggested that reinforcement of the EMT might be a key for CUL1 to accelerate TNBC metastasis.

DNA damage response and repair in colorectal cancer: Defects, regulation and therapeutic implications

DNA damage response, a key factor involved in maintaining genome integrity and stability, consists of several kinase-dependent signaling pathways, which sense and transduce DNA damage signal. The severity of damage appears to determine DNA damage responses, which can include cell cycle arrest, damage repair and apoptosis. A number of recent studies have demonstrated that defection in signaling through this network is thought to be an underlying mechanism behind the development and progression of various types of human malignancies, including colorectal cancer. In this review, colorectal cancer and its molecular pathology as well as DNA damage response is briefly introduced. Finally, the involvement of key components of this network in the initiation/progression, prognosis, response to treatment and development of drug resistance is comprehensively discussed.

MicroRNA 495 Inhibits Proliferation and Metastasis and Promotes Apoptosis by Targeting Twist1 in Gastric Cancer Cells

Recently, microRNAs (miRNAs) have been reported to participate in multiple biological processes. However, the effects of miR-495 on gastric cancer (GC) remain unclear. The purpose of this study was to explore the functions of miR-495 in GC cell proliferation, metastasis, and apoptosis. SGC-7901 and BGC-823 cell lines were transfected with miR-495 mimic, miR-495 inhibitor, and negative controls (mimic control and inhibitor control). The expressions of miR-495, cell viability, migration, apoptosis, and apoptosis-related factors were examined by qRT-PCR, trypan blue staining, Transwell, flow cytometry, and Western blot, respectively. Simultaneously, key factor expression levels of EMT were detected by qRT-PCR and Western blot. The direct target of miR-495 was confirmed by dual-luciferase assay. Additionally, sh-Twist1, pc-Twist1, and corresponding controls were transfected into SGC-7901 and BGC-823 cells, and the protein levels of EMT-associated factors were detected by Western blot. miR-495 was downregulated in GC cells. miR-495 expression level was effectively overexpressed or suppressed in SGC-7901 and BGC-823 cells. Overexpression of miR-495 significantly decreased cell viability and migration, increased apoptosis, and inhibited the EMT process. Suppression of miR-495 showed contrary results. Twist1 was clarified as a target gene of miR-495, and Twist1 silencing obviously reduced the promoting effect of miR-495 suppression on these biological processes. Twist1 silencing significantly blocked the EMT process in both SGC-7901 and BGC-823 cells. miR-495 inhibited proliferation and metastasis and promoted apoptosis by targeting Twist1 in GC cells. These data indicated that miR-495 might be a novel antitumor factor of GC and provide a new method for the treatment of GC.

Post-Translational Modifications of H2A Histone Variants and Their Role in Cancer

Histone variants are chromatin components that replace replication-coupled histones in a fraction of nucleosomes and confer particular characteristics to chromatin. H2A variants represent the most numerous and diverse group among histone protein families. In the nucleosomal structure, H2A-H2B dimers can be removed and exchanged more easily than the stable H3-H4 core. The unstructured N-terminal histone tails of all histones, but also the C-terminal tails of H2A histones protrude out of the compact structure of the nucleosome core. These accessible tails are the preferential target sites for a large number of post-translational modifications (PTMs). While some PTMs are shared between replication-coupled H2A and H2A variants, many modifications are limited to a specific histone variant. The present review focuses on the H2A variants H2A.Z, H2A.X, and macroH2A, and summarizes their functions in chromatin and how these are linked to cancer development and progression. H2A.Z primarily acts as an oncogene and macroH2A and H2A.X as tumour suppressors. We further focus on the regulation by PTMs, which helps to understand a degree of context dependency.

Identification of genes related to proliferative diabetic retinopathy through RWR algorithm based on protein-protein interaction network

Proliferative diabetic retinopathy (PDR) is one of the most common complications of diabetes and can lead to blindness. Proteomic studies have provided insight into the pathogenesis of PDR and a series of PDR-related genes has been identified but are far from fully characterized because the experimental methods are expensive and time consuming. In our previous study, we successfully identified 35 candidate PDR-related genes through the shortest-path algorithm. In the current study, we developed a computational method using the random walk with restart (RWR) algorithm and the protein-protein interaction (PPI) network to identify potential PDR-related genes. After some possible genes were obtained by the RWR algorithm, a three-stage filtration strategy, which includes the permutation test, interaction test and enrichment test, was applied to exclude potential false positives caused by the structure of PPI network, the poor interaction strength, and the limited similarity on gene ontology (GO) terms and biological pathways. As a result, 36 candidate genes were discovered by the method which was different from the 35 genes reported in our previous study. A literature review showed that 21 of these 36 genes are supported by previous experiments. These findings suggest the robustness and complementary effects of both our efforts using different computational methods, thus providing an alternative method to study PDR pathogenesis.

Radiation therapy-induced metastasis: radiobiology and clinical implications

Radiation therapy is an effective means of achieving local control in a wide range of primary tumours, with the reduction in the size of the tumour(s) thought to mediate the observed reductions in metastatic spread in clinical trials. However, there is evidence to suggest that the complex changes induced by radiation in the tumour environment can also present metastatic risks that may counteract the long-term efficacy of the treatment. More than 25 years ago, several largely theoretical mechanisms by which radiation exposure might increase metastatic risk were postulated. These include the direct release of tumour cells into the circulation, systemic effects of tumour and normal tissue irradiation and radiation-induced changes in tumour cell phenotype. Here, we review the data that has since emerged to either support or refute these putative mechanisms focusing on how the unique radiobiology underlying modern radiotherapy modalities might alter these risks.

MicroRNA-34a targets epithelial to mesenchymal transition-inducing transcription factors (EMT-TFs) and inhibits breast cancer cell migration and invasion

MicroRNA-34a (miR-34a) plays an essential role against tumorigenesis and progression of cancer metastasis. Here, we analyzed the expression, targets and functional effects of miR-34a on epithelial to mesenchymal transition-inducing transcription factors (EMT-TFs), such as TWIST1, SLUG and ZEB1/2, and an EMT-inducing protein NOTCH1 in breast cancer (BC) cell migration and invasion and its correlation with tumorigenesis and clinical outcomes. Expression of miR-34a is downregulated in human metastatic breast cancers (MBC) compared to normal breast tissues and is negatively correlated with clinicopathological features of MBC patients. Ectopic expression of miR-34a in MBC cell-line BT-549 significantly inhibits cell migration and invasion, but exhibits no clear effect on BC cell growth. We found that miR-34a is able to inactivate EMT signaling pathway with mediatory of NOTCH1, TWIST1, and ZEB1 upon 3′-UTR activity in MBC cell lines, but has no inhibitory effects on SLUG and ZEB2. Furthermore, we investigated the synergistic effects of Thymoquinone (TQ) and miR-34a together on the expression of EMT-associated proteins. Results showed that co-delivery of miR-34a and TQ is able to inactivate EMT signaling pathway by directly targeting TWIST1 and ZEB1 in BT-549 cell line, indicating that they might be a promising therapeutic combination against breast cancer metastasis. Epigenetic inactivation of the EMT-TFs/miR-34a pathway can potentially alter the equilibrium of these regulations, facilitating EMT and metastasis in BC. Altogether, our findings suggest that miR-34a alone could serve as a potential therapeutic agent for MBC, and together with TQ, their therapeutic potential is synergistically enhanced.

MicroRNA-610 suppresses osteosarcoma oncogenicity via targeting TWIST1 expression

Osteosarcoma is the most frequent primary bone tumor affects adolescents and young adults. Recently, microRNAs (miRNAs) are short, non-coding and endogenous RNAs that played as important roles in the initiation and progression of tumors. In this study, we try to explore the biological function and expression of miR-610 in the osteosarcoma. We showed that miR-610 expression was downregulated in the osteosarcoma tissues and cell lines. Elevated expression of miR-610 suppressed the osteosarcoma cell proliferation, cell cycle, invasion and EMT program. Moreover, overexpression of miR-610 increased sensitivity of MG-63 and U2OS cells to cisplatin. Twist1 was identified as a direct target gene of miR-610 in the osteosarcoma cell. Furthermore, we demonstrated that Twist1 was upregulated in the osteosarcoma tissues and cell lines. The expression of Twist1 was negatively associated with the expression of miR-610 expression in the osteosarcoma tissues. Ectopic expression of Twist1 inhibited the sensitivity of miR-610-overexpressing MG-63 cells to cisplatin. We also showed that overexpression of Twist1 increased the proliferation and invasion of miR-610-overexpressing MG-63 cells. These data indicated that ectopic expression of miR-610 suppressed the osteosarcoma cell proliferation, cell cylce, invasion and increased the sensitivity of osteosarcoma cells to cisplatin through targeting the Twist1 expression.