MicroRNA-302c represses epithelial-mesenchymal transition and metastasis by targeting transcription factor AP-4 in colorectal cancer

TFAP4 Regulation of MCM5 Activates the PI3K/AKT Pathway to Promote Invasion and Metastasis of Gastric Cancer

AIMS

To investigate the role of transcription factor activating enhancer-binding protein 4 (TFAP4) in gastric cancer (GC) progression and elucidate its mechanism in promoting metastasis and invasion through the PI3K/AKT signaling pathway.

METHODS

Bioinformatics analysis was performed to assess TFAP4 expression in GC tissues. Clinical specimens were collected and validated for TFAP4 expression. Functional assays were conducted to evaluate the effects of TFAP4 overexpression and inhibition on GC cell proliferation, invasion, and metastasis. In vivo studies with HGC27 cells in BALB/c nude mice were used to assess tumor growth and metastasis. Mechanistic analysis included the measurement of MCM5 expression and activation of the PI3K/AKT signaling pathway, with PI3K inhibitor LY294002 and MCM5 knockdown applied to confirm the pathways involved.

RESULTS

Elevated TFAP4 expression was observed in GC tissues, and its overexpression promoted GC cell proliferation, invasion, and metastasis. Conversely, TFAP4 inhibition suppressed these behaviors. In vivo studies confirmed that TFAP4 knockdown reduced tumor growth and metastasis in nude mice. Mechanistically, TFAP4 was found to activate MCM5, which in turn facilitated GC cell invasion and metastasis. Furthermore, TFAP4 and MCM5 activated the PI3K/AKT signaling pathway, as evidenced by increased p-PI3K and p-AKT expression. The effects of TFAP4 overexpression were reversed by MCM5 knockdown or treatment with the PI3K inhibitor LY294002.

CONCLUSION

The TFAP4-MCM5 signaling axis promotes GC progression through the PI3K/AKT pathway, suggesting that targeting this axis could provide a potential therapeutic strategy for managing gastric cancer.

Role of microRNAs in regulation of doxorubicin and paclitaxel responses in lung tumor cells

Lung cancer as the leading cause of cancer related mortality is always one of the main global health challenges. Despite the recent progresses in therapeutic methods, the mortality rate is still significantly high among lung cancer patients. A wide range of therapeutic methods including chemotherapy, radiotherapy, and surgery are used to treat lung cancer. Doxorubicin (DOX) and Paclitaxel (TXL) are widely used as the first-line chemotherapeutic drugs in lung cancer. However, there is a significant high percentage of DOX/TXL resistance in lung cancer patients, which leads to tumor recurrence and metastasis. Considering, the side effects of these drugs in normal tissues, it is required to clarify the molecular mechanisms of DOX/TXL resistance to introduce the efficient prognostic and therapeutic markers in lung cancer. MicroRNAs (miRNAs) have key roles in regulation of different pathophysiological processes including cell division, apoptosis, migration, and drug resistance. MiRNA deregulations are widely associated with chemo resistance in various cancers. Therefore, considering the importance of miRNAs in chemotherapy response, in the present review, we discussed the role of miRNAs in regulation of DOX/TXL response in lung cancer patients. It has been reported that miRNAs mainly induced DOX/TXL sensitivity in lung tumor cells by the regulation of signaling pathways, autophagy, transcription factors, and apoptosis. This review can be an effective step in introducing miRNAs as the non-invasive prognostic markers to predict DOX/TXL response in lung cancer patients.

BPTF in bone marrow provides a potential progression biomarker regulated by TFAP4 through the PI3K/AKT pathway in neuroblastoma

BACKGROUND

Neuroblastoma (NB) is the most common extracranial malignant solid tumor in children, which is highly prone to bone marrow (BM) metastasis. BM can monitor early signs of mild disease and metastasis. Existing biomarkers are insufficient for the diagnosis and treatment of NB. Bromodomain PHD finger transcription factor (BPTF) is an important subunit of the chromatin-remodeling complex that is closely associated with tumors. Here, we evaluated whether BPTF in BM plays an important role in predicting NB progression, and explore the molecular mechanism of BPTF in NB.

METHODS

The clinical relevance of the BPTF was predicted in the GEO (GSE62564) and TARGET database. The biological function of BPTF in NB was investigated by constructing cell lines and employing BPTF inhibitor AU1. Western blot was used to determine the changes of BPTF, TFAP4, PI3K/AKT signaling and Epithelial-mesenchymal transition (EMT) related markers. A total of 109 children with newly diagnosed NB in Beijing Children's Hospital from January 2018 to March 2021 were included in this study. RT-PCR was used to measure the BPTF and TFAP4 expression in BM. The cut-off level was set at the median value of BPTF expression levels.

RESULTS

Databases suggested that BPTF expression was higher in NB and was significantly associated with stage and grade. Proliferation and migration of NB cells were slowed down when BPTF was silenced. Mechanistically, TFAP4 could positively regulate BPTF and promotes EMT process through activating the PI3K/AKT signaling pathway. Moreover, detection of the newly diagnosed BM specimens showed that BPTF expression was significantly higher in high-risk group, stage IV group and BM metastasis group. Children with high BPTF at initial diagnosis were considered to have high risk for disease progression and recurrence. BPTF is an independent risk factor for predicting NB progression.

CONCLUSIONS

A novel and convenient BPTF-targeted humoral detection that can prompt minimal residual and predict NB progression in the early stages of the disease were identified. BPTF inhibitor AU1 is expected to become a new targeted drug for NB therapy. It's also reveal previously unknown mechanisms of BPTF in NB cell proliferation and metastasis through TFAP4 and PI3K/AKT pathways.

Comprehensive analysis of prognostic value, immune implication and biological function of CPNE1 in clear cell renal cell carcinoma

Background: Elevated expression of Copine-1 (CPNE1) has been proved in various cancers; however, the underlying mechanisms by which it affects clear cell renal cell carcinoma (ccRCC) are unclear.

Methods: In this study, we applied multiple bioinformatic databases to analyze the expression and clinical significance of CPNE1 in ccRCC. Co-expression analysis and functional enrichment analysis were investigated by LinkedOmics, cBioPortal and Metascape. The relationships between CPNE1 and tumor immunology were explored using ESTIMATE and CIBERSORT method. In vitro experiments, CCK-8, wound healing, transwell assays and western blotting were conducted to investigate the effects of gain- or loss-of-function of CPNE1 in ccRCC cells.

Results: The expression of CPNE1 was notably elevated in ccRCC tissues and cells, and significantly correlated with grade, invasion range, stage and distant metastasis. Kaplan–Meier and Cox regression analysis displayed that CPNE1 expression was an independent prognostic factor for ccRCC patients. Functional enrichment analysis revealed that CPNE1 and its co-expressed genes mainly regulated cancer-related and immune-related pathways. Immune correlation analysis showed that CPNE1 expression was significantly related to immune and estimate scores. CPNE1 expression was positively related to higher infiltrations of immune cells, such as CD8+ T cells, plasma cells and regulatory T cells, exhibited lower infiltrations of neutrophils. Meanwhile, elevated expression of CPNE1 was characterized by high immune infiltration levels, increased expression levels of CD8+ T cell exhaustion markers (CTLA4, PDCD1 and LAG3) and worse response to immunotherapy. In vitro functional studies demonstrated that CPNE1 promoted proliferation, migration and invasion of ccRCC cells through EGFR/STAT3 pathway.

Conclusion: CPNE1 is a reliable clinical predictor for the prognosis of ccRCC and promotes proliferation and migration by activating EGFR/STAT3 signaling. Moreover, CPNE1 significantly correlates with immune infiltration in ccRCC.

MicroRNAs (miRNAs): Novel potential therapeutic targets in colorectal cancer

Colorectal cancer (CRC) is the most common malignant tumor and one of the most lethal malignant tumors in the world. Despite treatment with a combination of surgery, radiotherapy, and/or systemic treatment, including chemotherapy and targeted therapy, the prognosis of patients with advanced CRC remains poor. Therefore, there is an urgent need to explore novel therapeutic strategies and targets for the treatment of CRC. MicroRNAs (miRNAs/miRs) are a class of short noncoding RNAs (approximately 22 nucleotides) involved in posttranscriptional gene expression regulation. The dysregulation of its expression is recognized as a key regulator related to the development, progression and metastasis of CRC. In recent years, a number of miRNAs have been identified as regulators of drug resistance in CRC, and some have gained attention as potential targets to overcome the drug resistance of CRC. In this review, we introduce the miRNAs and the diverse mechanisms of miRNAs in CRC and summarize the potential targeted therapies of CRC based on the miRNAs.

Chemokines and chemokine receptors in colorectal cancer; multifarious roles and clinical impact

Colorectal cancer (CRC) is considered the second cause of cancer death worldwide. The early diagnosis plays a key role in patient prognosis and subsequently overall survival. Similar to several types of cancer, colorectal cancer is also characterised by drug resistance and heterogeneity that contribute to its complexity -especially at advanced stages. However, despite the extensive research related to the identification of biomarkers associated to early diagnosis, accurate prognosis and the management of CRC patients, little progress has been made thus far. Therefore, the mortality rates, especially at advanced stages, remain high. A large family of chemoattractant cytokines called chemokines are known for their significant role in inflammation and immunity. Chemokines released by the different tumorous cells play a key role in increasing the complexity of the tumour's microenvironment. The current review investigates the role of chemokines and chemokine receptors in colorectal cancer and their potential as clinical molecular signatures that could be effectively used as a personalised therapeutic approach. We discussed how chemokine and chemokine receptors regulate the microenvironment and lead to heterogeneity in CRC. An important aspect of chemokines is their role in drug resistance which has been extensively discussed. This review also provides an overview of the current advances in the search for chemokines and chemokine receptors in CRC.

Upregulating microRNA-373-3p promotes apoptosis and inhibits metastasis of hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies in the digestive system. Abnormal miR-373-3p and TFAP4 expressions are critical in many malignant tumors, but it is unclear whether they work in the context of HCC. qRT-PCR measured miR-373-3p expression in HCC tissues and adjacent normal tissues. Flow cytometry and Western blot analyzed cell apoptosis. EMT, Transwell, and wound healing assay examined HCC cell migration and EMT, respectively. Western blot determined the profile of TFAP4/PI3K/AKT. IHC detected Ki67, E-cadherin, and vimentin in the tumor tissues. Moreover, the downstream target of miR-373-3p was predicted using the database. Dual luciferase activity assay and RIP verified the binding correlation between TFAP4 and miR-373-3p. In HCC tissues and cell lines, miR-373-3p was downregulated, and its overexpression stepped up HCC cell apoptosis and suppressed migration and EMT. Furthermore, miR-373-3p overexpression elevated Bax and caspase 3 expressions and attenuated Bcl2’s level. A xenograft tumor experiment in nude mice unveiled that miR-373-3p overexpression dampened tumor growth and proliferation. miR-373-3p cramped PI3K/AKT pathway activation. miR-373-3p negatively modulated TFAP4, and TFAP4 overexpression inverted miR-373-3p-mediated anti-tumor effects. Additionally, TFAP4 enhanced IGF1 expression, and promoted IGF1R-PI3K/AKT pathway activation. Collectively, miR-373-3p functions as an anti-tumor gene in HCC by inhibiting TFAP4/PI3K/AKT pathway.

The Role of MiRNA in Cancer: Pathogenesis, Diagnosis, and Treatment

Cancer is also determined by the alterations of oncogenes and tumor suppressor genes. These gene expressions can be regulated by microRNAs (miRNA). At this point, researchers focus on addressing two main questions: "How are oncogenes and/or tumor suppressor genes regulated by miRNAs?" and "Which other mechanisms in cancer cells are regulated by miRNAs?" In this work we focus on gathering the publications answering these questions. The expression of miRNAs is affected by amplification, deletion or mutation. These processes are controlled by oncogenes and tumor suppressor genes, which regulate different mechanisms of cancer initiation and progression including cell proliferation, cell growth, apoptosis, DNA repair, invasion, angiogenesis, metastasis, drug resistance, metabolic regulation, and immune response regulation in cancer cells. In addition, profiling of miRNA is an important step in developing a new therapeutic approach for cancer.

Silencing of the Long Non-Coding RNA TTN-AS1 Attenuates the Malignant Progression of Osteosarcoma Cells by Regulating the miR-16-1-3p/TFAP4 Axis

Objectives

Osteosarcoma (OS) is a type of bone malignancy. This study attempted to explore the effect of long non-coding RNA TTN-AS1 (TTN-AS1) on OS and to determine its molecular mechanisms.

Methods

The expression of TTN-AS1, microRNA-16-1-3p (miR-16-1-3p), and transcription factor activating enhancer binding protein 4 (TFAP4) in OS was assessed using qRT-PCR. The OS cell proliferation, migration, and invasion were measured using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound-healing, and transwell assays. N-cadherin and MMP-2 protein level was determined with western blot. Interactions between TTN-AS1 and miR-16-1-3p or TFAP4 and miR-16-1-3p were confirmed using the dual-luciferase reporter assay. Additionally, an OS xenograft tumor model was constructed to assess the effect of TTN-AS1 on tumor growth.

Results

TTN-AS1 and TFAP4 expression was increased in OS, while miR-16-1-3p expression was decreased. TTN-AS1 silencing restrained OS cell proliferation, migration, invasion, N-cadherin and MMP-2 protein expression, and hindered tumor growth. MiR-16-1-3p overexpression retarded the malignant behavior of OS cells. TTN-AS1 played a carcinostatic role by down-regulating miR-16-1-3p in the OS cells. Moreover, miR-16-1-3p inhibition or TFAP4 elevation weakened the suppressive effect of TTN-AS1 silencing on OS cell tumor progression.

Conclusion

TTN-AS1 promoted the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of OS cells via mediating the miR-16-1-3p/TFAP4 axis. TTN-AS1 may be a critical target for improving OS.

Inhibition of MicroRNA-302c on Stemness of Colon Cancer Stem Cells via the CARF/Wnt/β-Catenin Axis

BACKGROUND

Even though the relevance of microRNA (miR)-302c has been studied, little is known about its involvement in colon cancer (CC).

AIMS

Our aim here was to investigate the role of miR-302c in the cancer stem cells (CSCs) of CC.

METHODS

Firstly, the CSCs were screened out from cultured SW1116 and SW480 cells by flow cytometry, and the differentially expressed miRNAs in cell were obtained by microarray analysis. The expression of miR-302c, collaborator of ARF (CARF), and Wnt/β-catenin-related genes in CSCs was determined by means of RT-qPCR and Western blot. A dual-luciferase reporter assay was conducted to authenticate the binding relationship between miR-302c and CARF. Proliferation, migration, invasion, sphere formation as well as apoptosis of CSCs were assessed by cell counting kit-8, Transwell assay, sphere formation assay as well as flow cytometric analysis, respectively. The roles of miR-302c and CARF in tumor growth were determined in vivo.

RESULTS

The expression of miR-302c in CC cells was reduced versus that in normal cells. The overexpression of miR-302c weakened the stemness, proliferation, invasion, and migration abilities while induced apoptosis of CSCs in CC. Also, miR-302c reduced tumor size and weight in mice, accompanied with lowered CARF expression. The mechanistic analysis manifested that miR-302c bound to CARF and suppressed its expression and disrupted the Wnt/β-catenin signaling.

CONCLUSION

This study offers a novel characterization of miR-302c function in CSCs in CC, which may be beneficial to the development of capable therapeutic options for CC.

The Role of non-coding RNAs in colorectal cancer, with a focus on its autophagy

Colorectal cancer (CRC) is one of malignant afflictions burdening people worldwide, mainly caused by shortages of effective medical intervention and poorly mechanistic understanding of the pathogenesis of CRC. Non-coding RNAs (ncRNAs) are a type of heterogeneous transcripts without the capability of coding protein, but have the potency of regulating protein-coding gene expression. Autophagy is an evolutionarily conserved catabolic process in which cytoplasmic contents are delivered to cellular lysosomes for degradation, resulting in the turnover of cellular components and producing energy for cell functions. A growing body of evidence reveals that ncRNAs, autophagy, and the crosstalks of ncRNAs and autophagy play intricate roles in the initiation, progression, metastasis, recurrence and therapeutic resistance of CRC, which confer ncRNAs and autophagy to serve as clinical biomarkers and therapeutic targets for CRC. In this review, we sought to delineate the complicated roles of ncRNAs, mainly including miRNAs, lncRNAs and circRNAs, in the pathogenesis of CRC, particularly focus on the regulatory role of ncRNAs in CRC-related autophagy, attempting to shed light on the complex pathological mechanisms, involving ncRNAs and autophagy, responsible for CRC tumorigenesis and development, so as to underpin the ncRNAs- and autophagy-based therapeutic strategies for CRC in clinical setting.

Tissue micro-RNAs associated with colorectal cancer prognosis: a systematic review

Colorectal cancer (CRC) is a multifactorial disease commonly diagnosed worldwide, with high mortality rates. Several studies demonstrate important associations between differential expression of micro-RNAs (miRs) and the prognosis of CRC. The present study aimed to identify differentially expressed tissue miRs associated with prognostic factors in CRC patients, through a systematic review of the Literature. Using the PubMed database, Cochrane Library and Web of Science, studies published in English evaluating miRs differentially expressed in tumor tissue and significantly associated with the prognostic aspects of CRC were selected. All the included studies used RT-PCR (Taqman or SYBR Green) for miR expression analysis and the period of publication was from 2009 to 2018. A total of 115 articles accomplished the inclusion criteria and were included in the review. The studies investigated the expression of 100 different miRs associated with prognostic aspects in colorectal cancer patients. The most frequent oncogenic miRs investigated were miR-21, miR-181a, miR-182, miR-183, miR-210 and miR-224 and the hyperexpression of these miRs was associated with distant metastasis, lymph node metastasis and worse survival in patients with CRC. The most frequent tumor suppressor miRs were miR-126, miR-199b and miR-22 and the hypoexpression of these miRs was associated with distant metastasis, worse prognosis and a higher risk of disease relapse (worse disease-free survival). Specific tissue miRs are shown to be promising prognostic biomarkers in patients with CRC, given their strong association with the prognostic aspects of these tumors, however, new studies are necessary to establish the sensibility and specificity of the individual miRs in order to use them in clinical practice.

MicroRNA-124 suppresses the invasion and proliferation of breast cancer cells by targeting TFAP4

MicroRNA (miRNA/miR)-124 is widely accepted as the suppressor of different tumors. The present study aimed to improve understanding of the potential role of miR-124 in breast cancer. The gene expression profile change derived from the overexpression of miR-124 was investigated using RNA sequencing and bioinformatics analysis of the breast cancer cell line SKBR3. The results demonstrated that the gene expression profile of SKBR3 cells significantly changed. In addition, the transcription factor activating enhancer-binding protein 4 (TFAP4) gene was identified among the top 10 differentially expressed genes, and was identified as a novel target gene of miR-124 using a dual-luciferase reporter assay. TFAP4 knockdown in notably impaired SKBR3 cell migration and proliferation, which was consistent with decreasing migration and proliferation ability following overexpression of miR-124. Taken together, these results suggest that overexpression of miR-124 can suppress the migration and proliferation of SKBR3 cells by tarsgeting TFAP4. Thus, TFAP4 may act as a novel therapeutic target of breast cancer.

Transcription Factor AP4 Mediates Cell Fate Decisions: To Divide, Age, or Die

Simple Summary

Here, we review the literature on Activating Enhancer-Binding Protein 4 (AP4)/transcription factor AP4 (TFAP4) function and regulation and its role in cancer. Elevated expression of AP4 was detected in tumors of various organs and is associated with poor patient survival. AP4 is encoded by a Myc target gene and mediates cell fate decisions by regulating multiple processes, such as cell proliferation, epithelial-mesenchymal transition, stemness, apoptosis, and cellular senescence. Thereby, AP4 may be critical for tumor initiation and progression. In this review article, we summarize published evidence showing how AP4 functions as a transcriptional activator and repressor of a plethora of direct target genes in various physiological and pathological conditions. We also highlight the complex interactions of AP4 with c-Myc, N-Myc, p53, lncRNAs, and miRNAs in feed-back loops, which control AP4 levels and mediate AP4 functions. In the future, a better understanding of AP4 may contribute to improved prognosis and therapy of cancer.

Abstract

Activating Enhancer-Binding Protein 4 (AP4)/transcription factor AP4 (TFAP4) is a basic-helix-loop-helix-leucine-zipper transcription factor that was first identified as a protein bound to SV40 promoters more than 30 years ago. Almost 15 years later, AP4 was characterized as a target of the c-Myc transcription factor, which is the product of a prototypic oncogene that is activated in the majority of tumors. Interestingly, AP4 seems to represent a central hub downstream of c-Myc and N-Myc that mediates some of their functions, such as proliferation and epithelial-mesenchymal transition (EMT). Elevated AP4 expression is associated with progression of cancer and poor patient prognosis in multiple tumor types. Deletion of AP4 in mice points to roles of AP4 in the control of stemness, tumor initiation and adaptive immunity. Interestingly, ex vivo AP4 inactivation results in increased DNA damage, senescence, and apoptosis, which may be caused by defective cell cycle progression. Here, we will summarize the roles of AP4 as a transcriptional repressor and activator of target genes and the contribution of protein and non-coding RNAs encoded by these genes, in regulating the above mentioned processes. In addition, proteins interacting with or regulating AP4 and the cellular signaling pathways altered after AP4 dysregulation in tumor cells will be discussed.

MicroRNA-206 inhibits the proliferation, migration and invasion of colorectal cancer cells by regulating the c-Met/AKT/GSK-3β pathway

An imbalance in microRNA (miRNA/miR) expression is closely associated with tumorigenesis and progression. miR-206 is downregulated in different types of tumors, including colorectal cancer (CRC). However, the effects of miR-206 on the progression of CRC, and its underlying molecular mechanisms are yet to be elucidated. The present study aimed to investigate the effects of miR-206 on the proliferation, migration and invasion of colorectal cancer cells, and determine its potential molecular mechanism. The results of the present study demonstrated that the expression levels of miR-206 and c-Met were affected in HCT116 and SW480 cells by transfected with miR-206 mimic, inhibitor or small interfering RNA-c-Met. A Dual-luciferase reporter assay was performed to identify the miRNA targets. Cell proliferation, migration and invasion assays were also performed. The results demonstrated that overexpression of miR-206 significantly decreased the viability of HCT116 and SW480 cells. The results of the Transwell assay indicated that the cell migratory and invasive abilities were inhibited following transfection with miR-206 mimic. As a target of miR-206, knockdown of c-Met significantly suppressed cell viability, migration and invasion. In addition, c-Met knockdown or overexpression of miR-206 inhibited activation of the AKT/GSK-3β pathway. Collectively, these results suggest that miR-206 suppresses the proliferation, migration and invasion of CRC cells by targeting the c-Met/AKT/GSK-3β pathway.

Cucurbitacin E Chemosensitizes Colorectal Cancer Cells via Mitigating TFAP4/Wnt/β-Catenin Signaling

Chemoresistance and toxicity are the main obstacles that limit the efficacy of 5-fluorouracil (5-FU) in colorectal cancer (CRC) therapy. Hence, it is urgent to identify new adjuvants that can sensitize CRC cells to conventional chemotherapeutic approaches. Cucurbitacin E (CE) is a natural triterpenoid, widely distributed in dietary plants, and shows antitumor effects. Here, we report that CE enhances the sensitivity of CRC cells to chemotherapy via attenuating the expression of adenosine 5'-triphosphate (ATP)-binding cassette transporters ABCC1 and MDR1. Combined with CE-functionalized magnetite nanoparticles and gene ontology analysis, we found that CE-binding proteins may involve Wnt/β-catenin signaling. To validate the findings, β-catenin was upregulated in drug-resistant cell lines, and the synergistic effects of CE and chemotherapeutics were accompanied by the downregulation of β-catenin. Moreover, TFAP4 was identified as an intracellular target of CE. Remarkably, the combination of CE and 5-FU treatment attenuated β-catenin, MDR1, and ABCC1 expressions, while TFAP4 overexpression reversed their expressions by 2.68 ± 0.46-, 0.72 ± 0.44-, and 0.93 ± 0.21-fold, respectively. Thus, our results indicate that CE sensitizes CRC cells to chemotherapy by decreasing the TFAP4/Wnt/β-catenin signaling, suggesting that the dietary compound CE can be used as a chemosensitizing adjuvant for CRC treatment.

Mining therapeutic and prognostic significance of STATs in renal cell carcinoma with bioinformatics analysis

Renal cell carcinoma is one of the most common malignancies with high morbidity and mortality. STAT proteins play a significant role in cell biological behavior and immune response associated with cancer progression. In our study, the datasets analyzed for the expression and potential functions can be found in several bioinformatics analysis tools. We found that STAT1/2/4/6 were upregulated in RCC while STAT3/5B were downregulated. The expression of STAT2/4/5B were significantly associated with the pathological stage of RCC patients. RCC patients with high expression of STAT2/4 and low/medium expression of STAT5B had a poor overall survival. The function of STATs and the neighboring genes mainly enriched in JAK-STAT signaling pathway and NOD-like receptor signaling pathway. Several transcription factor, kinase, and miRNA targets were identified. Close correlations were obtained between immune cell infiltration and STATs in RCC. Our results have provided novel insights for the selection of immunotherapeutic targets and prognostic biomarkers.

MicroRNAs: Multifaceted Regulators of Colorectal Cancer Metastasis and Clinical Applications

Colorectal cancer (CRC) is the third-commonest malignant cancer, and its metastasis is the major reason for cancer-related death. The process of metastasis is highly coordinated and involves a complex cascade of multiple steps. In recent years, miRNAs, as highly conserved, endogenous, noncoding, single-stranded RNA, has been confirmed to be involved in the development of various cancers. Considering that miRNA is also involved in a series of biological behaviors, regulating CRC occurrence and development, we review and summarize the role of miRNAs and related signaling pathways in several CRC-metastasis stages, including invasion and migration, mobility, metabolism, epithelial-mesenchymal transition, tumor-microenvironment communication, angiogenesis, anoikis, premetastatic-niche formation, and cancer stemness. In addition, we review the application of miRNAs as diagnostic CRC markers and in clinical treatment resistance. This review can contribute to understanding of the mechanism of miRNAs in CRC progression and provide a theoretical basis for clinical CRC treatment.

miRNA Clusters with Down-Regulated Expression in Human Colorectal Cancer and Their Regulation

Regulation of microRNA (miRNA) expression has been extensively studied with respect to colorectal cancer (CRC), since CRC is one of the leading causes of cancer mortality worldwide. Transcriptional control of miRNAs creating clusters can be, to some extent, estimated from cluster position on a chromosome. Levels of miRNAs are also controlled by miRNAs "sponging" by long non-coding RNAs (ncRNAs). Both types of miRNA regulation strongly influence their function. We focused on clusters of miRNAs found to be down-regulated in CRC, containing miR-1, let-7, miR-15, miR-16, miR-99, miR-100, miR-125, miR-133, miR-143, miR-145, miR-192, miR-194, miR-195, miR-206, miR-215, miR-302, miR-367 and miR-497 and analysed their genome position, regulation and functions. Only evidence provided with the use of CRC in vivo and/or in vitro models was taken into consideration. Comprehensive research revealed that down-regulated miRNA clusters in CRC are mostly located in a gene intron and, in a majority of cases, miRNA clusters possess cluster-specific transcriptional regulation. For all selected clusters, regulation mediated by long ncRNA was experimentally demonstrated in CRC, at least in one cluster member. Oncostatic functions were predominantly linked with the reviewed miRNAs, and their high expression was usually associated with better survival. These findings implicate the potential of down-regulated clusters in CRC to become promising multi-targets for therapeutic manipulation.

CircFAT1 Suppresses Colorectal Cancer Development Through Regulating miR-520b/UHRF1 Axis or miR-302c-3p/UHRF1 Axis

Background: It was reported that circular RNAs (circRNAs) exerted important functions in various human cancers. However, the function of circFAT1 was less known. The purpose of this study was to reveal the functional mechanism of circFAT1 in colorectal cancer (CRC). Materials and Methods: Quantitative real-time polymerase chain reaction and Western blot assay were used to detect the levels of genes. Cell proliferation ability was assessed by 3-(4, 5-dimethyl-2-thiazoyl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry was used to investigate cell apoptosis rate. The glucose consumption and lactate production were determined using related kits. Furthermore, the interaction between circFAT1 or ubiquitin-like PHD and RING finger domain-containing protein 1 (UHRF1) and miR-520b or miR-302c-3p was predicted by starbase3.0, and then confirmed by the dual-luciferase reporter assay. Besides, xenograft experiment was performed to analyze the effect of circFAT1 on tumor growth in vivo. Results: The levels of circFAT1 and UHRF1 were increased, as well as the levels of miR-520b and miR-302c-3p were decreased in CRC tissues and cells. CircFAT1 knockdown suppressed cell proliferation, cycle, and glycolysis as well as induced apoptosis. Interestingly, circFAT1 was a sponge of miR-520b and miR-302c-3p, and miR-520b and miR-302c-3p could target UHRF1. Both miR-520b overexpression and miR-302c-3p overexpression inhibited CRC cell growth. Furthermore, both miR-520b knockdown and miR-302c-3p depletion weakened the effect of circFAT1 knockdown on the growth of CRC cells. Besides, circFAT1 depletion repressed tumor growth in vivo. Conclusion: The authors' findings suggested that circFAT1 upregulated UHRF1 to affect CRC cell proliferation, apoptosis, and glycolysis through targeting miR-520b and miR-302c-3p, providing theoretical basis for the treatment of CRC.

Transcription factor AP-4 (TFAP4)-upstream ORF coding 66 aa inhibits the malignant behaviors of glioma cells by suppressing the TFAP4/long noncoding RNA 00520/microRNA-520f-3p feedback loop

Upstream ORF (uORF) is a translational initiation element located in the 5′UTR of eukaryotic mRNAs. Studies have found that uORFs play an important regulatory role in many diseases. Based on The Cancer Genome Atlas database, the results of our experiments and previous research evidence, we investigated transcription factor AP‐4 (TFAP4) and its uORF, LIM and SH3 protein 1 (LASP1), long noncoding RNA 00520 (LINC00520), and microRNA (miR)‐520f‐3p as candidates involved in glioma malignancy, which is a poorly understood process. Both TFAP4‐66aa‐uORF and miR‐520f‐3p were downregulated, and TFAP4, LASP1, and LINC00520 were highly expressed in glioma tissues and cells. TFAP4‐66aa‐uORF or miR‐520f‐3p overexpression or TFAP4, LASP1, or LINC00520 knockdown inhibited glioma cell proliferation, migration, and invasion, but promoted apoptosis. TFAP4‐66aa‐uORF inhibited the translation of TFAP4 by binding to the TFAP4 mRNA. MicroRNA‐520f‐3p inhibited TFAP4 expression by binding to its 3′UTR. However, LINC00520 could promote the expression of TFAP4 by competitively binding to miR‐520f‐3p. In addition, TFAP4 transcriptionally activated LASP1 and LINC00520 expression by binding to their promoter regions, forming a positive feedback loop of TFAP4/LINC00520/miR‐520f‐3p. Our findings together indicated that TFAP4‐66aa‐uORF inhibited the TFAP4/LINC00520/miR‐520f‐3p feedback loop by directly inhibiting TFAP4 expression, subsequently leading to inhibition of glioma malignancy. This provides a basis for developing new therapeutic approaches for glioma treatment.

Mechanisms of Metastasis in Colorectal Cancer and Metastatic Organotropism: Hematogenous versus Peritoneal Spread

Metastasis is the major cause of death in patients with colorectal carcinoma (CRC). The most common sites of metastasis are the liver and the peritoneum. Peritoneal carcinomatosis is often considered the end stage of the disease after the tumor has spread to the liver. However, almost half of CRC patients with peritoneal carcinomatosis do not present with liver metastasis. This brings up the question of whether peritoneal spread can still be considered as the end stage of a metastasized CRC or whether it should just be interpreted as a site of metastasis alternative to the liver. This review tries to discuss this question and summarize the current status of literature on potential characteristics in tumor biology in the primary tumor, i.e., factors (transcription factors and direct and indirect E-cadherin repressors) and pathways (WNT, TGF-β, and RAS) modulating EMT, regulation of EMT on a posttranscriptional and posttranslational level (miRNAs), and angiogenesis. In addition to tumor-specific characteristics, factors in the tumor microenvironment, immunological markers, ways of transport of tumor cells, and adhesion molecules appear to differ between hematogenous and peritoneal spread. Factors such as integrins and exosomal integrins, cancer stem cell phenotype, and miRNA expression appear to contribute in determining the metastatic route. We went through each step of the metastasis process comparing hematogenous to peritoneal spread. We identified differences with respect to organotropism, epithelial-mesenchymal transition, angiogenesis and inflammation, and tumor microenvironment which will be further elucidated in this review. A better understanding of the underlying mechanisms and contributing factors of metastasis development in CRC has huge relevance as it is the foundation to help find specific targets for treatment of CRC.

MicroRNA-608 Promotes Apoptosis in Non-Small Cell Lung Cancer Cells Treated With Doxorubicin Through the Inhibition of TFAP4

Lung cancer is the most commonly diagnosed type of cancer and the leading cause of cancer-associated death worldwide. MicroRNAs (miRNAs) are non-coding single-stranded RNA molecules of ∼20–25 nucleotides in length. Single nucleotide polymorphisms are a class of genetic variation in the human genome, which when present in miRNA genes are associated with the risk of developing cancer. This study aimed to identify whether the miRNA (miR)-608 polymorphism rs4919510 influenced the incidence of lung cancer, and to explore the underlying mechanisms of miR-608 in the pathogenesis of the disease. A total of 37 patients with non-small cell lung cancer (NSCLC) were selected to determine the expression levels of miR-608; 96 NSCLC patients and 136 cancer-free healthy controls were recruited to determine the incidence of miR-608 rs4919510 in lung cancer patients. Additionally, the impact of miR-608 on the expression of predicted target genes, cell migration, viability, proliferation, and apoptosis was also assessed. We found that the presence of miR-608 rs4919510 did not affect the susceptibility of patients to NSCLC or the maturation of miR-608. miR-608 expression levels were found to be downregulated in NSCLC tissues. Furthermore, overexpression of miR-608 promoted doxorubicin-induced apoptosis in NSCLC cell lines A549 and HCC4006 by inhibiting the expression of transcription factor activating enhancer-binding protein 4 (TFAP4), and high expression levels of TFAP4 were observed in NSCLC tissues. Therefore, our results may provide valuable insights for the chemotherapeutical treatment of NSCLC.

miR-302 cluster inhibits angiogenesis and growth of K562 leukemia cells by targeting VEGFA

Background

miR-302 cluster has been reported as a tumor suppressor in many human cancers; yet, its function in chronic myeloid leukemia (CML) tumorigenesis remains largely unclear. The study was aimed to explore the functional roles of miR-302 cluster in CML progression.

Materials and methods

Quantitative reverse transcriptase PCR and Western blot were performed to evaluate miR-302 cluster and vascular endothelial growth factor A (VEGFA) expression levels. Cell Counting Kit-8 assay, colony formation assay and human umbilical vein endothelial cell line capillary tube formation were used to determine the influence of miR-302 cluster on the growth and angiogenesis of K562 cells, respectively. Luciferase reporter assay was employed to confirm the direct target interaction between miR-302 cluster and VEGFA.

Results

This study demonstrated that miR-302 cluster was frequently downregulated in CML samples and cell lines and high level of miR-302 cluster was significantly associated with good prognosis of CML patients. Compared with miRNA negative control, miR-302 cluster mimics obviously suppressed cell growth, colony formation and angiogenesis. Further studies revealed that VEGFA was a direct target gene of miR-302 cluster. Moreover, overexpression of VEGFA dramatically abated the inhibition of miR-302 cluster on cell growth and angiogenesis.

Conclusion

The present study, for the first time, identified miR-302 cluster as a tumor suppressor, and overexpression of miR-302 cluster inhibited growth and angiogenesis in K562 cells. miR-302 cluster may be a potential therapeutic target in CML to develop the adjuvant antiangiogenic therapy based on VEGFA.

microRNA-769 is downregulated in colorectal cancer and inhibits cancer progression by directly targeting cyclin-dependent kinase 1

BACKGROUND

In recent years, microRNAs (miRNAs) have been reported to be aberrantly expressed in colorectal cancer (CRC). The deregulation of miRNAs is implicated in the formation and progression of CRC, and participates in the regulation of a wide range of biological behaviors. Considering the crucial role of miRNAs in CRC, miRNAs are thought to have significant promise in the diagnosis and therapy of patients with this malignancy.

MATERIAL AND METHODS

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to detect miR-769 expression in CRC tissues and cell lines. MTT assay and flow cytometry analysis were used to determine the effects of miR-769 upregulation in CRC cell proliferation and apoptosis, respectively. The influence of miR-769 overexpression in CRC cell migration and invasion was evaluated through migration and invasion assays. Notably, the possible mechanisms underlying the action of miR-769 in CRC cells were explored.

RESULTS

In the present study, miR-769 was frequently found to be poorly expressed in CRC tissues and cell lines. Functional assays showed that recovery of miR-769 expression suppressed CRC cell proliferation, migration, and invasion, increased cell apoptosis in vitro, and inhibited tumor growth in vivo. Cyclin-dependent kinase 1 (CDK1) was the direct target of miR-769 in CRC cells. CDK1 was overexpressed in CRC tissue samples and negatively correlated with miR-769 expression. In addition, CDK1 inhibition imitated the tumor suppressor activity of miR-769 in CRC cells, and restoration of CDK1 expression partially abolished the tumor-suppressing roles of miR-769 in malignant CRC cells.

CONCLUSION

The results of this study demonstrated that miR-769 was downregulated in CRC and directly targeted CDK1 to be implicated in the regulation of CRC cell proliferation, apoptosis, migration and invasion. Thus, the miR-769/CDK1 axis might be an effective therapeutic target for treating patients with CRC.

miR-203 inhibits ovarian tumor metastasis by targeting BIRC5 and attenuating the TGFβ pathway

BACKGROUND

We previously reported that miR-203 functions as a tumor suppressor in ovarian cancer cells by directly targeting transcription factor Snai2 and inhibiting epithelial to mesenchymal transition (EMT), whereas BIRC5/survivin promotes EMT. In this study, we tested our hypothesis that miR-203 inhibits ovarian tumor metastasis by suppressing EMT through targeting BIRC5, using an orthotopic ovarian cancer mouse model.

METHODS

We overexpressed miR-203 in ovarian cancer SKOV3 and OVCAR3 cells using a lentiviral vector and examined cell migration and invasion using transwell plates. The small molecule inhibitor, YM155, was used to inhibit survivin expression. miR-203-expressing and control SKOV3 cells were intrabursally injected into immunocompromised NSG female mice. Primary tumors in ovaries and metastatic tumors were collected to determine the expression of survivin and EMT markers using Western blot and immunostaining.

RESULTS

Overexpression of miR-203 inhibits EMT by targeting BIRC5 in ovarian cancer SKOV3 and OVCAR3 cells. miR-203 expression enhances the ability of the survivin inhibitor YM155 to reduce tumor cell migration and invasion in vitro. We further showed that miR-203 expression attenuated the TGFβ pathway in both SKOV3 and OVCAR3 cells. miR-203 expression also inhibited primary tumor growth in ovaries and metastatic tumors in multiple peritoneal organs including liver and spleen.

CONCLUSION

miR-203 inhibits ovarian tumor metastasis by targeting BIRC5/survivin and attenuating the TGFβ pathway.