MicroRNA-218 is a prognostic indicator in colorectal cancer and enhances 5-fluorouracil-induced apoptosis by targeting BIRC5

Competitive endogenous RNA networks: Decoding the role of long non-coding RNAs and circular RNAs in colorectal cancer chemoresistance

Colorectal cancer (CRC) is recognized as one of the most common gastrointestinal malignancies across the globe. Despite significant progress in designing novel treatments for CRC, there is a pressing need for more effective therapeutic approaches. Unfortunately, many patients undergoing chemotherapy develop drug resistance, posing a significant challenge for cancer treatment. Non-coding RNAs (ncRNAs) have been found to play crucial roles in CRC development and its response to chemotherapy. However, there are still gaps in our understanding of interactions among various ncRNAs, such as long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and microRNAs (miRNAs). These ncRNAs can act as either oncogenes or tumour suppressors, affecting numerous biological functions in different cancers including CRC. A class of ncRNA molecules known as competitive endogenous RNAs (ceRNAs) has emerged as a key player in various cellular processes. These molecules form networks through lncRNA/miRNA/mRNA and circRNA/miRNA/mRNA interactions. In CRC, dysregulation of ceRNA networks has been observed across various cellular processes, including proliferation, apoptosis and angiogenesis. These dysregulations are believed to play a significant role in the progression of CRC and, in certain instances, may contribute to the development of chemoresistance. Enriching our knowledge of these dysregulations holds promise for advancing the field of diagnostic and therapeutic modalities for CRC. In this review, we discuss lncRNA- and circRNA-associated ceRNA networks implicated in the emergence and advancement of drug resistance in colorectal carcinogenesis.

Post-transcriptional regulation of BIRC5/survivin expression and induction of apoptosis in breast cancer cells by tristetraprolin

Inhibition of apoptosis is one of the hallmarks of cancer and is a target of various therapeutic interventions. BIRC5 is an inhibitor of apoptosis that is aberrantly expressed in cancer leading to sustained growth of tumours. Post-transcriptional control mechanisms involving RNA-binding proteins and AU-rich elements (AREs) are fundamental to many cellular processes and changes in the expression or function of these proteins can promote an aberrant and pathological phenotype. BIRC5 mRNA has an ARE in its 3' UTR making it a candidate for regulation by the RNA binding proteins tristetraprolin (TTP) and HuR (ELAVL1). In this study, we investigated the binding of TTP and HuR by RNA-immunoprecipitation assays and found that these proteins were associated with BIRC5 mRNA to varying extents. Consequently, BIRC5 expression decreased when TTP was overexpressed and apoptosis was induced. In the absence of TTP, BIRC5 mRNA was stabilized, protein expression increased and the number of apoptotic cells declined. As an ARE-mRNA stabilizing protein, recombinant HuR led to upregulation of BIRC5 expression, whereas HuR silencing was concomitant with downregulation of BIRC5 mRNA and protein and increased cell death. Survival analyses demonstrated that increased TTP and low BIRC5 expression predicted an overall better prognosis compared to dysregulated TTP and high BIRC5. Thus, the results present a novel target of ARE-mediated post-transcriptional regulation.

MiR-548c-3p through suppressing Tyms and Abcg2 increases the sensitivity of colorectal cancer cells to 5-fluorouracil

Background

Colorectal cancer, is one of most prevalent the cancer in the world. 5-Fluorouracil is a standard chemotherapeutic drug while the acquisition of resistance to 5-Fluorouracil is one of the problems during treatment. In this study, we aimed to find the miRNAs that modulate the expression of Tyms and Abcg2 as resistance-inducing genes in the resistant cell lines to 5-Fluorouracil.

Methods

5-Fluorouracil-resistant HCT116 and SW480 cell lines were generated by consecutive treatment of cells with 5-Fluorouracil. This resistance induction was validated by MTT assays. The expression of the Tyms and Abcg2 gene and miR-548c-3p were studied by quantitative real-time PCR in the cell lines.

Results

We hypothesized that miR-548c-3p is targeting Tyms and Abcg2 simultaneously. Increased expression Tyms gene in the two most resistant cell lines derived from HCT116 and all resistant cell lines derived from SW480 except one were seen. Increased expression of Abcg2 was observed in the most resistant HCT116-derived cell line and all resistant cell lines, derived from SW480. In all resistant cell lines, the expression of miR-548c-3p was decreased.

Conclusion

It can be concluded downregulation of miR548c-3p is in line with Tyms and Abcg2 overexpression in resistant cell lines to 5-Fluorouracil.

Tumor suppressor miR-218 directly targets epidermal growth factor receptor (EGFR) expression in triple-negative breast cancer, sensitizing cells to irradiation

PURPOSE

MicroRNA-218 (miR-218) is a key regulator of numerous processes relevant to tumor progression. In the present study, we aimed to characterize the relationship between miR-218 and the Epidermal Growth Factor Receptor (EGFR) as well as to understand downstream effects in triple-negative breast cancer (TNBC).

METHODS

We assessed miR-218 and EGFR expression in cell lines and publicly available primary breast cancer gene expression data. We then overexpressed miR-218 in two TNBC cell lines and investigated effects on EGFR and downstream mitogen-activated protein (MAP) kinase signaling. Luciferase reporter assay was used to characterize a direct binding interaction between miR-218 and EGFR mRNA. Digital holographic microscopy helped investigate cell migration and dry mass after miR-218 overexpression. Cell division and invasion were assessed microscopically, while radiation response after miR-218 overexpression alone or combined with additional EGFR knockdown was investigated via clonogenic assays.

RESULTS

We found an inverse correlation between EGFR expression and miR-218 levels in cell lines and primary breast cancer tissues. MiR-218 overexpression resulted in a downregulation of EGFR via direct binding of the mRNA. Activation of EGFR and downstream p44/42 MAPK signaling were reduced after pre-miR-218 transfection. Cell proliferation, motility and invasiveness were inhibited whereas cell death and mitotic catastrophe were upregulated in miR-218 overexpressing cells compared to controls. MiR-218 overexpressing and EGFR siRNA-treated cells were sensitized to irradiation, more than miR-218 overexpressing cells alone.

CONCLUSION

This study characterizes the antagonistic relationship between miR-218 and EGFR. It also demonstrates downstream functional effects of miR-218 overexpression, leading to anti-tumorigenic cellular changes.

A Systematic Review of Clinical Validated and Potential miRNA Markers Related to the Efficacy of Fluoropyrimidine Drugs

Colorectal cancer (CRC) is becoming increasingly prevalent worldwide. Fluoropyrimidine drugs are the primary chemotherapy regimens in routine clinical practice of CRC. However, the survival rate of patients on fluoropyrimidine-based chemotherapy varies significantly among individuals. Biomarkers of fluoropyrimidine drugs'' efficacy are needed to implement personalized medicine. This review summarized fluoropyrimidine drug-related microRNA (miRNA) by affecting metabolic enzymes or showing the relevance of drug efficacy. We first outlined 42 miRNAs that may affect the metabolism of fluoropyrimidine drugs. Subsequently, we filtered another 41 miRNAs related to the efficacy of fluoropyrimidine drugs based on clinical trials. Bioinformatics analysis showed that most well-established miRNA biomarkers were significantly enriched in the cancer pathways instead of the fluoropyrimidine drug metabolism pathways. The result also suggests that the miRNAs screened from metastasis patients have a more critical role in cancer development than those from non-metastasis patients. There are five miRNAs shared between these two lists. The miR-21, miR-215, and miR-218 can suppress fluoropyrimidine drugs'' catabolism. The miR-326 and miR-328 can reduce the efflux of fluoropyrimidine drugs. These five miRNAs could jointly act by increasing intracellular levels of fluoropyrimidine drugs'' cytotoxic metabolites, leading to better chemotherapy responses. In conclusion, we demonstrated that the dynamic changes in the transcriptional regulation via miRNAs might play significant roles in the efficacy and toxicity of the fluoropyrimidine drug. The reported miRNA biomarkers would help evaluate the efficacy of fluoropyrimidine drug-based chemotherapy and improve the prognosis of colorectal cancer patients.

MALAT1-miRNAs network regulate thymidylate synthase and affect 5FU-based chemotherapy

Background

The active metabolite of 5-Fluorouracil (5FU), used in the treatment of several types of cancer, acts by inhibiting the thymidylate synthase encoded by the TYMS gene, which catalyzes the rate-limiting step in DNA replication. The major failure of 5FU-based cancer therapy is the development of drug resistance. High levels of TYMS-encoded protein in cancerous tissues are predictive of poor response to 5FU treatment. Expression of TYMS is regulated by various mechanisms, including involving non-coding RNAs, both miRNAs and long non-coding RNAs (lncRNAs).

Aim

To delineate the miRNAs and lncRNAs network regulating the level of TYMS-encoded protein.

Main body

Several miRNAs targeting TYMS mRNA have been identified in colon cancers, the levels of which can be regulated to varying degrees by lncRNAs. Due to their regulation by the MALAT1 lncRNA, these miRNAs can be divided into three groups: (1) miR-197-3p, miR-203a-3p, miR-375-3p which are downregulated by MALAT1 as confirmed experimentally and the levels of these miRNAs are actually reduced in colon and gastric cancers; (2) miR-140-3p, miR-330-3p that could potentially interact with MALAT1, but not yet supported by experimental results; (3) miR-192-5p, miR-215-5p whose seed sequences do not recognize complementary response elements within MALAT1. Considering the putative MALAT1-miRNAs interaction network, attention is drawn to the potential positive feedback loop causing increased expression of MALAT1 in colon cancer and hepatocellular carcinoma, where YAP1 acts as a transcriptional co-factor which, by binding to the TCF4 transcription factor/ β-catenin complex, may increase the activation of the MALAT1 gene whereas the MALAT1 lncRNA can inhibit miR-375-3p which in turn targets YAP1 mRNA.

Conclusion

The network of non-coding RNAs may reduce the sensitivity of cancer cells to 5FU treatment by upregulating the level of thymidylate synthase.

MicroRNAs and drug resistance in colorectal cancer with special focus on 5-fluorouracil

Colorectal cancer is globally one of the most common cancers in all age groups. The current chemotherapy combinations for colorectal cancer treatment include 5-fluorouracil-based regimens; however, drug resistance remains one of the main reasons for chemotherapy failure and disease recurrence. Many studies have determined colorectal cancer chemoresistance mechanisms such as drug efflux, cell cycle arrest, DNA damage repair, apoptosis, autophagy, vital enzymes, epigenetic, epithelial-mesenchymal transition, stem cells, and immune system suppression. Several microRNAs affect drug resistance by regulating the drug resistance-related target genes in colorectal cancer. These drug resistance-related miRNAs may be used as promising biomarkers for predicting drug response or as potential therapeutic targets for treating patients with colorectal cancer. This work reviews and discuss the role of selected microRNAs in 5-fluorouracil resistance and their molecular mechanisms in colorectal cancer.

Epigenetic Approaches to Overcome Fluoropyrimidines Resistance in Solid Tumors

Simple Summary

Fluoropyrimidines represent the backbone of many combination chemotherapy regimens for the treatment of solid cancers but are still associated with toxicity and mechanisms of resistance. In this review, we focused on the epigenetic modifiers histone deacetylase inhibitors (HDACis) and on their ability to regulate specific genes and proteins involved in the fluoropyrimidine metabolism and resistance mechanisms. We presented emerging preclinical and clinical studies, highlighting the mechanisms by which HDACis can prevent/overcome the resistance and/or enhance the therapeutic efficacy of fluoropyrimidines, potentially reducing their toxicity, and ultimately improving the overall survival of cancer patients.

Abstract

Although fluoropyrimidines were introduced as anticancer agents over 60 years ago, they are still the backbone of many combination chemotherapy regimens for the treatment of solid cancers. Like other chemotherapeutic agents, the therapeutic efficacy of fluoropyrimidines can be affected by drug resistance and severe toxicities; thus, novel therapeutic approaches are required to potentiate their efficacy and overcome drug resistance. In the last 20 years, the deregulation of epigenetic mechanisms has been shown to contribute to cancer hallmarks. Histone modifications play an important role in directing the transcriptional machinery and therefore represent interesting druggable targets. In this review, we focused on histone deacetylase inhibitors (HDACis) that can increase antitumor efficacy and overcome resistance to fluoropyrimidines by targeting specific genes or proteins. Our preclinical data showed a strong synergistic interaction between HDACi and fluoropyrimidines in different cancer models, but the clinical studies did not seem to confirm these observations. Most likely, the introduction of increasingly complex preclinical models, both in vitro and in vivo, cannot recapitulate human complexity; however, our analysis of clinical studies revealed that most of them were designed without a mechanistic approach and, importantly, without careful patient selection.

MicroRNA-155-5p Contributes to 5-Fluorouracil Resistance Through Down-Regulating TP53INP1 in Oral Squamous Cell Carcinoma

The anticancer drug 5-fluorouracil (5-FU) resistance is a major obstacle to reducing the effectiveness of cancer treatment, and its detailed mechanism has not been fully elucidated. Here, in 5-FU-resistant human oral squamous cell carcinoma (OSCC) HSC3 cells (HSC3/5-FU), the levels of 21 miRNA candidates were detected using RT-PCR and miR-155-5p level increased strikingly in HSC3/5-FU cells compared to HSC3 cells. Compared with HSC3 cells, the CCK-8 assay showed that the HSC3/5-FU cells transfected with miR-155-5p inhibitors decreased 5-FU IC50. Ectopic expression of miR-155-5p in HSC3 and HSC4 cells increased 5-FU IC50 (CCK-8 assay), migration (wound-healing and transwell assays) and invasion (transwell assay) abilities. Seven miR-155-5p target candidates were discovered by miRNA prediction algorithms (miRDB, Targetscan, and miRWalk), and the RT-PCR results showed that in HSC3/5-FU cells TP53INP1 was of the lowest mRNA expression level compared with HSC3 cells. The RT-PCR and Western blotting assays showed that ectopic expression of miR-155-5p in HSC3 and HSC4 cells decreased TP53INP1 expression level. Furthermore, the luciferase reporter and RNA pull-down assays determined the interference effect of miR-155-5p on TP53INP1 expression. The enhancement of cell viability (CCK-8 assay), migration (wound-healing and transwell assays) and invasion (transwell assay) by miR-155-5p after 5-FU treatment was reversed by TP53INP1 overexpression. After treatment with 5-FU, HSC3-miR-155-5p tumor-bearing nude mice presented growing tumors, while HSC3-TP53INP1 group possessed shrinking tumors. In conclusion, these results lead to the proposal that miR-155-5p enhances 5-FU resistance by decreasing TP53INP1 expression in OSCC.

lncRNA MCF2L-AS1/miR-105/ IL-1β Axis Regulates Colorectal Cancer Cell Oxaliplatin Resistance

Background

Interactions between non-coding RNAs and mRNAs have been shown to play key roles in colorectal cancer (CRC) resistance to chemotherapeutic drugs, but the regulatory network of these ncRNA/mRNA interactions in the context of CRC cell resistance to oxaliplatin has yet to be fully defined.

Methods

MCF2L-AS1, miR-105, and IL-1β expression levels were measured in cells and serum samples via qPCR, while ELISAs were additionally used to quantify IL-1β levels in these samples. Interactions between MCF2L-AS1, miR-105, and IL-1β were detected through pull-down, RNA immunoprecipitation, and luciferase reporter assays. Cellular viability and OXA IC50 values were established through MTT assays, while in vivo OXA resistance was assessed using a tumor xenograft model system.

Results

MCF2L-AS1 levels were significantly elevated in CRC patients that did not respond to chemotherapy and in CRC/OXA cells relative to responders and chemosensitive CRC cells. From a mechanistic perspective, miR-105 was identified as a MCF2L-AS1 target, with this miRNA, in turn, suppressing the expression of IL-1β. Knocking down MCF2L-AS1 or overexpressing miR-105 was sufficient to alleviate CRC/OXA cell chemoresistance, while overexpressing IL-1β reversed this effect.

Conclusion

The MCF2L-AS1/miR-105/IL-1β regulatory axis regulates the resistance of CRC cells to OXA treatment.

Role of Long Non-Coding RNA Polymorphisms in Cancer Chemotherapeutic Response

Genetic polymorphisms are defined as the presence of two or more different alleles in the same locus, with a frequency higher than 1% in the population. Since the discovery of long non-coding RNAs (lncRNAs), which refer to a non-coding RNA with a length of more than 200 nucleotides, their biological roles have been increasingly revealed in recent years. They regulate many cellular processes, from pluripotency to cancer. Interestingly, abnormal expression or dysfunction of lncRNAs is closely related to the occurrence of human diseases, including cancer and degenerative neurological diseases. Particularly, their polymorphisms have been found to be associated with altered drug response and/or drug toxicity in cancer treatment. However, molecular mechanisms are not yet fully elucidated, which are expected to be discovered by detailed studies of RNA–protein, RNA–DNA, and RNA–lipid interactions. In conclusion, lncRNAs polymorphisms may become biomarkers for predicting the response to chemotherapy in cancer patients. Here we review and discuss how gene polymorphisms of lncRNAs affect cancer chemotherapeutic response. This knowledge may pave the way to personalized oncology treatments.

CircANKRD52 Promotes the Tumorigenesis of Hepatocellular Carcinoma by Sponging miR-497-5p and Upregulating BIRC5 Expression

CircRNAs participate in the pathogenesis of a variety of cancers. Previous studies showed that baculoviral IAP repeat containing 5 (BIRC5) can promote tumor progression. But, the mechanisms by which circRNAs regulate BIRC5 expression in hepatocellular carcinoma (HCC) remain unknown. The clinical prognosis of BIRC5 or miR-497-5p expression in patients with HCC was assessed by TCGA RNA-seq dataset. hsa_circ_0026939 (circANKRD52) or BIRC5 was identified to bind with miR-497-5p by luciferase gene report, RIP and circRIP assays. MTT, colony formation, Transwell assays and a xenograft tumor model were used to estimate the role of miR-497-5p or circANKRD52 in HCC cells. As a result, we found that elevated expression of BIRC5 or decreased expression of miR-497-5p was linked to poor survival in HCC. Restored expression of miR-497-5p repressed cell proliferation, colony formation and invasiveness by targeting BIRC5, but its inhibitor showed the opposite results. Furthermore, circANKRD52 possessed a tumor-promoting effect by acting as a sponge of miR-497-5p and thereby upregulated BIRC5 in HCC cells. In conclusion, our findings demonstrated that circANKRD52 enhances the tumorigenesis of HCC by sponging miR-497-5p and upregulating BIRC5 expression.

MiR-21 Is Required for the Epithelial-Mesenchymal Transition in MDA-MB-231 Breast Cancer Cells

Breast cancer (BCa) is one of the leading health problems among women. Although significant achievements have led to advanced therapeutic success with targeted therapy options, more efforts are required for different subtypes of tumors and according to genomic, transcriptomic, and proteomic alterations. This study underlines the role of microRNA-21 (miR-21) in metastatic MDA-MB-231 breast cancer cells. Following the knockout of miR-21 from MDA-MB-231 cells, which have the highest miR-21 expression levels compared to MCF-7 and SK-BR-3 BCa cells, a decrease in epithelial-mesenchymal transition (EMT) via downregulation of mesenchymal markers was observed. Wnt-11 was a critical target for miR-21, and the Wnt-11 related signaling axis was altered in the stable miR-21 knockout cells. miR-21 expression was associated with a significant increase in mesenchymal markers in MDA-MB-231 BCa cells. Furthermore, the release of extracellular vesicles (EVs) was significantly reduced in the miR-21 KO cells, alongside a significant reduction in relative miR-21 export in EV cargo, compared with control cells. We conclude that miR-21 is a leading factor involved in mesenchymal transition in MDA-MB-231 BCa. Future therapeutic strategies could focus on its role in the treatment of metastatic breast cancer.

Long non-coding RNA MALAT1 regulates oxaliplatin-resistance via miR-324-3p/ADAM17 axis in colorectal cancer cells

Background

Colorectal cancer (CRC) is one of the most general malignant tumors. Accumulating evidence implied that long non-coding RNA Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1) participated in the tumorigenesis of CRC. However, the effect of MALAT1 in drug-resistance needed to be further illustrated.

Methods

Levels of MALAT1, microRNA (miR)-324-3p, and a disintegrin and metalloprotease metallopeptidase domain 17 (ADAM17) were detected using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell Counting Kit 8 (CCK-8) was used to assess the half maximal inhibitory concentration (IC50) of oxaliplatin (Ox). Meanwhile, cell proliferation, migration and apoptosis were detected by CCK-8, transwell assay, and flow cytometry, respectively. The interaction between miR-324-3p and MALAT1 or ADAM17 was clarified by dual-luciferase reporter assay. Also, the effect of MALAT1 on tumor growth was detected in xenograft tumor mice treated with Ox.

Results

Significant up regulation of MALAT1 and ADAM17, and decrease of miR-324-3p were observed in Ox-resistant CRC tissues and cells. MALAT1 deficiency enhanced the sensitivity of Ox-resistant CRC cells response to Ox, while miR-324-3p repression or ADAM17 acceleration could overturn this effect. Moreover, MALAT1 silencing repressed tumor growth in Ox-treated nude mice. Mechanically, MALAT1 exerted promotion effect on the resistance response to Ox via miR-324-3p/ADAM17 axis in Ox-resistant CRC cells.

Conclusion

MALAT1 modulated the sensitivity of Ox through ADAM17 in Ox-resistant CRC cells by sponging miR-324-3p, thus MALAT1 might serve as a novel insight for the therapy of CRC.

Molecular determinants of response to 5-fluorouracil-based chemotherapy in colorectal cancer: The undisputable role of micro-ribonucleic acids

5-flurouracil (5-FU)-based chemotherapy is the main pharmacological therapy for advanced colorectal cancer (CRC). Despite significant progress in the treatment of CRC during the last decades, 5-FU drug resistance remains the most important cause of failure in CRC therapy. Resistance to 5-FU is a complex and multistep process. Different mechanisms including microsatellite instability, increased expression level of key enzyme thymidylate synthase and its polymorphism, increased level of 5-FU-activating enzymes and mutation of TP53 are proposed as the main determinants of resistance to 5-FU in CRC cells. Recently, micro-ribonucleic acids (miRNA) and their alterations were found to have a crucial role in 5-FU resistance. In this regard, the miRNA-mediated mechanisms of 5-FU drug resistance reside among the new fields of pharmacogenetics of CRC drug response that has not been completely discovered. Identification of the biological markers that are related to response to 5-FU-based chemotherapy is an emerging field of precision medicine. This approach will have an important role in defining those patients who are most likely to benefit from 5-FU-based chemotherapy in the future. Thereby, the identification of 5-FU drug resistance mechanisms is an essential step to predict and eventually overcome resistance. In the present comprehensive review, we will summarize the latest knowledge regarding the molecular determinants of response to 5-FU-based chemotherapy in CRC by emphasizing the role of miRNAs.

Molecular mechanisms and clinical implications of miRNAs in drug resistance of colorectal cancer

Systemic chemotherapy is identified as a curative approach to prolong the survival time of patients with colorectal cancer (CRC). Although great progress in therapeutic approaches has been achieved during the last decades, drug resistance still extensively persists and serves as a major hurdle to effective anticancer therapy for CRC. The mechanism of multidrug resistance remains unclear. Recently, mounting evidence suggests that a great number of microRNAs (miRNAs) may contribute to drug resistance in CRC. Certain of these miRNAs may thus be used as promising biomarkers for predicting drug response to chemotherapy or serve as potential targets to develop personalized therapy for patients with CRC. This review mainly summarizes recent advances in miRNAs and the molecular mechanisms underlying miRNA-mediated chemoresistance in CRC. We also discuss the potential role of drug resistance-related miRNAs as potential biomarkers (diagnostic and prognostic value) and envisage the future orientation and challenges in translating the findings on miRNA-mediated chemoresistance of CRC into clinical applications.

Identification of the Differentially Expressed Genes of Muscle Growth and Intramuscular Fat Metabolism in the Development Stage of Yellow Broilers

High-quality chicken meat is an important source of animal protein for humans. Gene expression profiles in breast muscle tissue were determined, aiming to explore the common regulatory genes relevant to muscle and intramuscular fat (IMF) during the developmental stage in chickens. Results show that breast muscle weight (BMW), breast meat percentage (BMP, %), and IMF (%) continuously increased with development. A total of 256 common differentially expressed genes (DEGs) during the developmental stage were screened. Among them, some genes related to muscle fiber hypertrophy were upregulated (e.g., CSRP3, LMOD2, MUSTN1, MYBPC1), but others (e.g., ACTC1, MYL1, MYL4) were downregulated from Week 3 to Week 18. During this period, expression of some DEGs related to the cells cycle (e.g., CCNB3, CCNE2, CDC20, MCM2) changed in a way that genetically suggests possible inhibitory regulation on cells number. In addition, DEGs associated with energy metabolism (e.g., ACOT9, CETP, LPIN1, DGAT2, RBP7, FBP1, PHKA1) were found to regulate IMF deposition. Our data identified and provide new insights into the common regulatory genes related to muscle growth, cell proliferation, and energy metabolism at the developmental stage in chickens.

Molecular Insights into miRNA-Driven Resistance to 5-Fluorouracil and Oxaliplatin Chemotherapy: miR-23b Modulates the Epithelial–Mesenchymal Transition of Colorectal Cancer Cells

Although treatment of colorectal cancer with 5-florouracil and oxaliplatin is widely used, it is frequently followed by a relapse. Therefore, there is an urgent need for profound understanding of chemotherapy resistance mechanisms as well as the profiling of predictive markers for individualized treatment. In this study, we identified the changes in 14 miRNAs in 5-fluouracil and 40 miRNAs in oxaliplatin-resistant cell lines by miRNA sequencing. The decrease in miR-224-5p expression in the 5-fluorouracil-resistant cells correlated with drug insensitivity due to its overexpression-induced drug-dependent apoptosis. On the other hand, the miR-23b/27b/24-1 cluster was overexpressed in oxaliplatin-resistant cells. The knockout of miR-23b led to the partial restoration of oxaliplatin susceptibility, showing the essential role of miR-23b in the development of drug resistance by this cluster. Proteomic analysis identified target genes of miR-23b and showed that endothelial-mesenchymal transition (EMT) was implicated in oxaliplatin insensibility. Data revealed that EMT markers, such as vimentin and SNAI2, were expressed moderately higher in the oxaliplatin-resistant cells and their expression increased further in the less drug-resistant cells, which had miR-23b knockout. This establishes that the balance of EMT contributes to the drug resistance, showing the importance of the miR-23b-mediated fine-tuning of EMT in oxaliplatin-resistant cancer cells.

microRNA-21 promotes breast cancer proliferation and metastasis by targeting LZTFL1

Background

Breast cancer is the most common cancer type in female. As microRNAs play vital role in breast cancer, this study aimed to explore the molecular mechanism and clinical value of miR-21 in breast cancer.

Methods

qRT-PCR was performed to detect miR-21 levels in plasma of 127 healthy controls, 82 benign breast tumor, 252 breast cancer patients, as well as in breast cancer cell lines. Transwell and wound healing assay were used to analyze breast cancer metastasis in response to miR-21 inhibitor. Colony formation and eFluor™ 670 based flow cytometric analysis were used to test breast cancer proliferation following miR-21 inhibitor treatment. Leucine zipper transcription factor-like 1 (LZTFL1), the target gene of miR-21 was predicted by MIRDB, TargetScan 5.1, PicTar and miRanda. Survival analysis of LZTFL1 levels in breast cancer prognosis was estimated with the Kaplan–Meier method by log-rank test according to data from the Cancer Genome Atlas. Luciferase activity assay was performed to confirm the regulation of miR-21 on LZTFL1. LZTFL1 siRNA and miR-21 inhibitor were co-transfected to breast cancer cells, then cell proliferation, migration and epithelial–mesenchymal transition (EMT) makers were tested. BALB/c nude mice were injected in situ with Hs578T cells stably overexpressing miR-21. Breast tumor growth, metastasis and the expression of EMT markers or LZTFL1 were detected in vivo.

Results

Plasma miR-21 levels were elevated in breast cancer patients compared with healthy controls and benign breast tumor patients, and the miR-21 levels were significantly decreased after surgery comparing with pre operation in 44 patients. Inhibition of miR-21 suppressed cell proliferation and metastasis in breast cancer cells. LZTFL1 was identified as a novel target gene of miR-21. Knockdown of LZTFL1 overcame the suppression of miR-21 inhibitor on cell proliferation, metastasis and the expression of EMT markers in breast cancer cells. miR-21 overexpression promoted breast cancer cell proliferation and metastasis in vivo.

Conclusions

These results indicate that plasma miR-21 level is a crucial biomarker for breast cancer diagnosis and targeting miR-21–LZTFL1–EMT axis might be a promising strategy in breast cancer therapy.

Trial registration

Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5951-3) contains supplementary material, which is available to authorized users.

Novel tetrahydroacridine derivatives with iodobenzoic moieties induce G0/G1 cell cycle arrest and apoptosis in A549 non-small lung cancer and HT-29 colorectal cancer cells

A series of nine tetrahydroacridine derivatives with iodobenzoic moiety were synthesized and evaluated for their cytotoxic activity against cancer cell lines—A549 (human lung adenocarcinoma), HT-29 (human colorectal adenocarcinoma) and somatic cell line—EA.hy926 (human umbilical vein cell line). All compounds displayed high cytotoxicity activity against A549 (IC₅₀ 59.12–14.87 µM) and HT-29 (IC₅₀ 17.32–5.90 µM) cell lines, higher than control agents—etoposide and 5-fluorouracil. Structure–activity relationship showed that the position of iodine in the substituent in the para position and longer linker most strongly enhanced the cytotoxic effect. Among derivatives, 1i turned out to be the most cytotoxic and displayed IC₅₀ values of 14.87 µM against A549 and 5.90 µM against HT-29 cell lines. In hyaluronidase inhibition assay, all compounds presented anti-inflammatory activity, however, slightly lower than reference compound. ADMET prediction showed that almost all compounds had good pharmacokinetic profiles. 1b, 1c and 1f compounds turned out to act against chemoresistance in cisplatin-resistant 253J B-V cells. Compounds intercalated into DNA and inhibited cell cycle in G0/G1 phase—the strongest inhibition was observed for 1i in A549 and 1c in HT-29. Among compounds, the highest apoptotic effect in both cell lines was observed after treatment with 1i. Compounds caused DNA damage and H2AX phosphorylation, which was detected in A549 and HT-29 cells. All research confirmed anticancer properties of novel tetrahydroacridine derivatives and explained a few pathways of their mechanism of cytotoxic action.

MicroRNA-218 regulates the chemo-sensitivity of cervical cancer cells through targeting survivin

Background: Cervical cancer is one of the most lethal malignancies among women in the world. Every year about 311,365 women die because of cervical cancer. Chemo-resistance is the main reason of the lethal malignancies, and the mechanism of chemo-resistance in cervical cancer still remains largely elusive. Purpose: Previous studies reported that microRNAs played important biological roles in the chemo-resistance in many types of cancers, in the present study we tried to investigate the biological roles of microRNA-218 in chemo-resistance in cervical cancer cells. Results: Real-time PCR results indicated microRNA-218 was downregulated in cisplatin-resistant HeLa/DDP and SiHa/DDP cells compared with the mock HeLa and SiHa cells. CCK-8 assay results showed upregulation of microRNA-218 enhanced the cisplatin sensitivity of cervical cancer cells; while downregulation of microRNA-218 decreased the cisplatin sensitivity of cervical cancer cells. Dual-luciferase assay indicated survivin was a direct target of microRNA-218. Western blotting and PCR results indicated the expression of survivin in HeLa/DDP and SiHa/DDP cells was significantly increased compared with HeLa and SiHa cells. Further study indicated induction of microRNA-218 decreased the expression of survivin while inhibition of microRNA-218 increased the expression of survivin in cervical cancer cells. Cell apoptosis results indicated induction of microRNA-218 induced the cell apoptosis in cervical cancer cells. Conclusion: Our data revealed microRNA-218 enhanced the cisplatin sensitivity in cervical cancer cells through regulation of cell growth and cell apoptosis, which could potentially benefit to the cervical cancer treatment in the future.

Current Evidence on miRNAs as Potential Theranostic Markers for Detecting Chemoresistance in Colorectal Cancer: A Systematic Review and Meta-Analysis of Preclinical and Clinical Studies

BACKGROUND

Findings from observational clinical studies examining the relationship between biomarker expression and theranosis in colorectal cancer (CRC) have been conflicting.

OBJECTIVE

We conducted this systematic review and meta-analysis to summarise the existing evidence to demonstrate the involvement of microRNAs (miRNAs) in chemoresistance and sensitivity in CRC through drug genetic pathways.

METHODS

Using PRISMA guidelines, we systematically searched PubMed and Science Direct for relevant studies that took place between 2012 and 2017. A random-effects model of meta-analysis was applied to evaluate the pooled effect size of hazard ratios (HRs) across the included studies. Cochran's Q test and the I² statistic were used to detect heterogeneity. A funnel plot was used to assess potential publication bias.

RESULTS

Of the 4700 studies found, 39 studies comprising 2822 patients with CRC met the inclusion criteria. The included studies used one or a combination of 14 chemotherapy drugs, including 5-fluorouracil and oxaliplatin. Of the 60 miRNAs, 28 were associated with chemosensitivity, 20 with chemoresistance, and one with differential expression and radiosensitivity; ten miRNAs were not associated with any impact on chemotherapy. The results outline the importance of 34 drug-regulatory pathways of chemoresistance and sensitivity in CRC. The mean effect size was 0.689 (95% confidence interval 0.428-1.110), indicating that the expression of miRNAs decreased the likelihood of death by about 32%.

CONCLUSION

Studies have consistently shown that multiple miRNAs could act as clinical predictors of chemoresistance and sensitivity. An inclusion of supplementary miRNA estimation in CRC routine practice needs to be considered to evaluate the efficacy of chemotherapy after confirming our findings with large-scale prospective cohort studies.

PROSPERO REGISTRATION NUMBER

CRD42017082196.

MicroRNA expression profiling in the colorectal normal-adenoma-carcinoma transition

Colorectal adenoma is a major precursor to colorectal cancer. Investigating the alteration of microRNA (miRNA/miR) expression during the progression from normal colorectal tissue to adenoma, and finally to colorectal carcinoma may aid our understanding of the biological mechanisms of colorectal tumorigenesis. In the present study, the miRNA expression profiles of normal colorectal tissue, adenoma and colorectal carcinoma from 6 patients were evaluated using miRNA-sequencing. A total of 334 miRNAs were identified as differentially expressed. It was revealed that 34 miRNAs were upregulated in all 6 patients, including miR-135b-5p, miR-18a-5p and miR-29b-3p, and 28 miRNAs were downregulated, including miR-1-3p, miR-338-3p and miR-218-5p. Using bioinformatic analysis, the potential target genes of these 62 miRNAs were predicted and found to be enriched in 'transcription, DNA-dependent (GO:0006351)', 'signal transduction (GO:0007165)', 'small molecule metabolic process (GO:0044281)' 'PI3K/AKT signaling pathway (path ID:04151)' and 'MAPK signaling pathway (path ID:04010)'. The miRNA expression profiles identified in the present study may extend our understanding of the molecular mechanisms underlying colorectal tumorigenesis and promote novel perspectives for prevention, diagnosis and treatment.

Survivin is a prognostic indicator in glioblastoma and may be a target of microRNA-218

Accumulating evidence has revealed that survivin expression is associated with a malignant phenotype and poor prognosis in glioma. Survivin is also a potential target of microRNA (miRNA/miR)-218. The aim of the present study was to investigate the expression and function of survivin in glioblastoma, and to examine the association between survivin and miR-218. For that purpose, survivin mRNA levels were analyzed in 144 frozen samples of glioblastoma using whole-genome RNA sequencing. In vitro cell proliferation, migration, invasion and apoptosis assays were performed, and survivin expression was detected by western blotting. The results revealed that the mRNA expression levels of survivin were negatively and significantly associated with overall survival in glioblastoma. Further in vitro analyses suggested that miR-218 may inhibit the expression of survivin. Expression of miR-218 in the LN229 cell line was significantly lower than that in the immortalized human gliocyte HEB cell line. miR-218 markedly inhibited tumor cell proliferation, migration and invasion capacities, and decreased apoptosis. miR-218 also inhibited the expression of survivin. These results indicated that survivin may be a target of miR-218 and could serve as a predictive biomarker.

The Network of Non-coding RNAs in Cancer Drug Resistance

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

MicroRNAs in the prognosis and therapy of colorectal cancer: From bench to bedside

MicroRNAs (miRNAs) are small, single-stranded, noncoding RNAs that can post-transcriptionally regulate the expression of various oncogenes and tumor suppressor genes. Dysregulated expression of many miRNAs have been shown to mediate the signaling pathways critical in the multistep carcinogenesis of colorectal cancer (CRC). MiRNAs are stable and protected from RNase-mediated degradation, thereby enabling its detection in biological fluids and archival tissues for biomarker studies. This review focuses on the role and application of miRNAs in the prognosis and therapy of CRC. While stage II CRC is potentially curable by surgical resection, a significant percentage of stage II CRC patients do develop recurrence. MiRNA biomarkers may be used to stratify such high-risk population for adjuvant chemotherapy to provide better prognoses. Growing evidence also suggests that miRNAs are involved in the metastatic process of CRC. Certain of these miRNAs may thus be used as prognostic biomarkers to identify patients more likely to have micro-metastasis, who could be monitored more closely after surgery and/or given more aggressive adjuvant chemotherapy. Intrinsic and acquired resistance to chemotherapy severely hinders successful chemotherapy in CRC treatment. Predictive miRNA biomarkers for response to chemotherapy may identify patients who will benefit the most from a particular regimen and also spare the patients from unnecessary side effects. Selection of patients to receive the new targeted therapy is becoming possible with the use of predictive miRNA biomarkers. Lastly, forced expression of tumor suppressor miRNA or silencing of oncogenic miRNA in tumors by gene therapy can also be adopted to treat CRC alone or in combination with other chemotherapeutic drugs.

Prognostic value of microRNAs in colorectal cancer: a meta-analysis

Background

Numerous studies have shown that miRNA levels are closely related to the survival time of patients with colon, rectal, or colorectal cancer (CRC). However, the outcomes of different investigations have been inconsistent. Accordingly, a meta-analysis was conducted to study associations among the three types of cancers.

Materials and methods

Studies published in English that estimated the expression levels of miRNAs with survival curves in CRC were identified until May 20, 2017 by online searches in PubMed, Embase, Web of Science, and the Cochrane Library by two independent authors. Pooled HRs with 95% CIs were used to estimate the correlation between miRNA expression and overall survival.

Results

A total of 63 relevant articles regarding 13 different miRNAs, with 10,254 patients were ultimately included. CRC patients with high expression of blood miR141 (HR 2.52, 95% CI 1.68-3.77), tissue miR21 (HR 1.31, 95% CI 1.12-1.53), miR181a (HR 1.52, 95% CI 1.26-1.83), or miR224 (HR 2.12, 95% CI 1.04-4.34), or low expression of tissue miR126 (HR 1.55, 95% CI 1.24-1.93) had significantly poor overall survival (P<0.05).

Conclusion

In general, blood miR141 and tissue miR21, miR181a, miR224, and miR126 had significant prognostic value. Among these, blood miR141 and tissue miR224 were strong biomarkers of prognosis for CRC.

Identification and functional characterization of circRNA-0008717 as an oncogene in osteosarcoma through sponging miR-203

Circular RNA (circRNA) is a key regulator in the development and progression of human cancers, however its role in osteosarcoma tumorigenesis is not well understood. The present study aims to investigate the expression profiles and potential modulation of circRNA on osteosarcoma carcinogenesis. Human circRNA microarray was performed to screen for abnormally expressed circRNA in osteosarcoma tissue and circRNA-0008717 was identified as one circRNA significantly upregulated in osteosarcoma tissue. Osteosarcoma patients with high circRNA-0008717 expression had shortened survival. Gain and loss functional assays suggested that knockdown of circRNA-0008717 suppressed cell proliferation, migration and invasion, but promoted cell apoptosis. By using biotin-labeled circRNA-0008717 probe to perform RNA precipitation in osteosarcoma cells, we identified miR-203 as the circ0008717-associated microRNA. Subsequently, Bmi-1 was identified as the functional target of miR-203. In addition, overexpression of circRNA-0008717 in osteosarcoma could elevate Bmi-1 expression, resulting in the promotion of osteosarcoma cell proliferation and invasion. Furthermore, the tumor promoting effect of circRNA-0008717 was abolished by miR-203 mimics or Bmi-1 silencing vector. In conclusion, circRNA-0008717 plays an oncogenic role in osteosarcoma and may serve as a promising prognostic biomarker for osteosarcoma patients. Therefore, silence of circRNA-0008717 could be a future direction to develop a novel treatment strategy.

Chronic oxymatrine treatment induces resistance and epithelial‑mesenchymal transition through targeting the long non-coding RNA MALAT1 in colorectal cancer cells

A major reason for colorectal cancer (CRC) chemoresistance is the enhanced migration and invasion of cancer cells, such as the cell acquisition of epithelial-mesenchymal transition (EMT). Long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been considered as a pro-oncogene in multiple cancers. However, the precise functional mechanism of lncRNA MALAT1 in chemoresistance and EMT is not well known. In the present study, we focused on the effect of oxymatrine on CRC cells and further investigated the role of MALAT1 in oxymatrine-induced resistance and EMT process. The human CRC cell line HT29 was exposed to increasing doses of oxymatrine to establish stable cell lines resistant to oxymatrine. The established HT29 oxymatrine resistant cells showed an EMT phenotype including specific morphologic changes, enhanced migratory and invasive capacity, and downregulation of E-cadherin protein expression. Subsequently, high-throughput HiSeq sequencing and RT-qPCR showed that lncRNA MALAT1 was significantly upregulated in the oxymatrine resistant cells (P<0.01), while knockdown of MALAT1 partially reversed the EMT phenotype in HT29 resistant cells. Furthermore, oxymatrine treatment suppressed the migration and invasion ability of CRC cells, however, this effect was significantly reversed by overexpression of MALAT1. Finally, we investigated the clinical role of MALAT1 and found that high lncRNA MALAT1 expression level is associated with poor prognosis in CRC patients receiving oxymatrine treatment (P<0.01). In conclusion, we demonstrate that lncRNA MALAT1 is a stimulator for oxymatrine resistance in CRC and it may provide therapeutic and prognostic information for CRC patients.

MACC1 is post-transcriptionally regulated by miR-218 in colorectal cancer

Metastasis is a multistep molecular network process, which is lethal for more than 90% of the cancer patients. Understanding the regulatory functions of metastasis-inducing molecules is in high demand for improved therapeutic cancer approaches. Thus, we studied the post-transcriptional regulation of the crucial carcinogenic and metastasis-mediating molecule metastasis associated in colon cancer 1 (MACC1). In silico analysis revealed MACC1 as a potential target of miR-218, a tumor suppressor miRNA. Expression of these two molecules inversely correlated in colorectal cancer (CRC) cell lines. In a cohort of CRC patient tissues (n = 59), miR-218 is significantly downregulated and MACC1 is upregulated compared with normal mucosa. Luciferase reporter assays with a construct of the MACC1-3′-UTR harboring either the wild type or the mutated miR-218 seed sequence confirmed the specificity of the targeting. miR-218 inhibited significantly MACC1 protein expression, and consistently, MACC1-mediated migration, invasion and colony formation in CRC cells. Anti-miR-218 enhanced the MACC1-mediated migration, invasion and colony formation. Similar findings were observed in the gastric cancer cell line MKN-45. Further, we performed methylation-specific PCR of the SLIT2 and SLIT3 promoter, where miR-218 is encoded in intronic regions. The SLIT2 and SLIT3 promoters are hypermethylated in CRC cell lines. miR-218 and SLIT2 expressions correlated positively. Methyltransferase inhibitor 5-Azacytidine induced miR-218 expression and inhibited the expression of its target MACC1. We also determined that MACC1 has alternative polyadenylation (APA) sites, which results in different lengths of 3′-UTR variants in a CRC cell line. Taken together, miR-218 is post-transcriptionally inhibiting the MACC1 expression and its metastasis-inducing abilities.

HIF‑1α‑induced upregulation of lncRNA UCA1 promotes cell growth in osteosarcoma by inactivating the PTEN/AKT signaling pathway

Increasing evidence indicates that long non-coding RNAs (lncRNAs) play an important role in multiple biological processes including cell growth, differentiation, proliferation and invasion. Urothelial carcinoma associated 1 (UCA1) is a highly conserved nuclear ncRNA and a key regulator of cell proliferation and apoptosis in several types of cancers. However, its role in osteosarcoma progression is not well known. In the present study, we aimed to determine the biological role of UCA1 in osteosarcoma progression. RT-qPCR analysis showed that UCA1 expression was significantly increased in osteosarcoma cell lines and promoted cell growth in osteosarcoma. We then sought to determine the mechanism underlying the upregulation of UCA1 in osteosarcoma. Luciferase reporter assay and chromatin immunoprecipitation assay suggested that lncRNA UCA1 was induced by HIF-1α and HIF-1α interacts with the HIF-1α response element in the promoter region of UCA1. In addition, the gain- and loss-of-functional assay showed that HIF-1α promoted osteosarcoma cell growth through inducing the UCA1 expression level. More importantly, Cignal Signal Transduction Reporter Array and western blot assay showed that lncRNA UCA1 inactivated the PTEN/AKT signaling pathway. Finally, we observed that HIF-1α induced cell growth through the UCA1/PTEN/AKT signaling pathway. To conclude, our integrated approach demonstrates that UCA1 confers a tumor promoter function by promoting cell proliferation and silencing of the PTEN/AKT signaling pathway in osteosarcoma. Thus, UCA1 can serve as a promising therapeutic target for osteosarcoma patients.

BIRC5 is a novel target of peroxisome proliferator‑activated receptor γ in brain microvascular endothelium cells during cerebral ischemia

Cerebral ischemia is a leading cause of ischemic stroke, which may lead to severe disability and mortality worldwide. There are some key factors concerned in cardioprotection, such as peroxisome proliferator-activated receptor γ (PPARγ), a ligand binding transcription factor involved in various biological functions including atherosclerosis, vascular dysfunction and hypertension, and baculoviral IAP repeat-containing 5 (BIRC5), which may protect human brain endothelial cells from ischemia-induced apoptosis. To determine the potential roles of PPARγ in brain microvascular endothelial (bEnd.3) cells during cerebral ischemia and the relationship between PPARγ and BIRC5, a cerebral ischemia model was established with bEnd.3 cells cells by oxygen-glucose deprivation (OGD) treatment. OGD treatment reduced proliferation and enhanced apoptosis of bEnd.3 cells in a time-dependent manner. PPARγ expression levels were decreased in bEnd.3 cells following OGD treatment. Upregulation of PPARγ expression protected bEnd.3 cells from ischemia injury and also upregulated BIRC5 expression. PPARγ-specific binding sites in the BIRC5 promoter were predicted bioinformatically and verified by luciferase reporter experiments. Results from electrophoretic mobility shift/supershift and chromatin immunoprecipitation assays suggested that BIRC5 may be a novel target of PPARγ transcriptional regulation during ischemic injury. The present results indicated that PPARγ may serve a protective role on bEnd.3 cells and that BIRC5 may be a downstream target of PPARγ regulation during cerebral ischemia.

Long noncoding RNA MALAT1 promotes cell proliferation through suppressing miR-205 and promoting SMAD4 expression in osteosarcoma

Increasing evidences have indicated that long non-coding RNAs (lncRNAs) play an important role in multiply biological processes including cell development, differentiation, proliferation and invasion. The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), is a highly conserved nuclear ncRNA and a key regulator of metastasis development in several cancers. However, its role in osteosarcoma progression is not well known. In this study, we sought to determine the clinical and bilogical role of MALAT1 in osteosarcoma progression. RT-qPCR analysis showed that MALAT1 expression was significantly increased in primary osteosarcoma tissues and cell lines. Kaplan-Meier analysis indicated that patients with high expression of MALAT1 was associated with poor overall survival compared with the low expressing patients. Furthermore, the gain and loss function assay showed that miR-205 was suppressed by MALAT1 in osteosarcoma and this interaction between miR-205 and MALAT1 has reciprocal effects. Cell viability assay showed that MALAT1 promoted MG-63 and SAOS-2 cell growth through suppressing miR-205. Subsequently, the downstream gene SMAD4 was identified as a direct functional target of miR-205, and miR-205 suppressed osteosarcoma cell growth through suppressing SMAD4. Finally, we demonstrated that MALAT1 promoted osteosarcoma progression via a miR-205-SMAD4 axis. In conclusion, we revealed that enhanced MALAT1 expression predicted unfavourable outcome in osteosarcoma and promoted cell proliferation through suppressing miR-205 and activating SMAD4 function. Thus, lncRNA MALAT1 may serve as a promising prognostic and therapeutic target for osteosarcoma patients.

Long noncoding RNA XIST is a prognostic factor in colorectal cancer and inhibits 5-fluorouracil-induced cell cytotoxicity through promoting thymidylate synthase expression

A major reason for the failure of advanced colorectal cancer (CRC) treatment is the occurrence of chemoresistance to 5-fluorouracil (5FU)-based treatment. Recent studies have shown that long non-coding RNAs (lncRNAs) are critical regulators in chemoresistance. By using the next generation HiSeq sequencing assay, we identified lncRNAs showing differential expression levels in 5FU resistant and non-resistant CRC patients. RT-qPCR was then performed for validation in tissues and serum samples, and lncRNA XIST was verified to be up-regulated in non-responding patients and have considerable diagnostic potential to identify responding patients from non-responding patients. In addition, increased serum XIST level was associated with poor response and lower survival rate in CRC patients receiving 5FU-based treatment. Subsequently, the 5FU resistant (5FU-R) cell lines were established, and lncRNA XIST was significantly up-regulated HT29 5FU-R and HCT116 5FU-R cells. Furthermore, knockdown of XIST reversed 5FU resistance while enhanced XIST could restrained the 5FU-induced cell cytotoxcity in both CRC cell lines. Western blotting and immunofluorescence analysis indicated that XIST promoted the expression of thymidylate synthase, a critical 5FU-targetd enzyme. In conclusion, our integrated approach demonstrates that increased expression of lncRNA XIST3 in CRC confers a potent poor therapeutic efficacy, and that lncRNA XIST participated in 5FU resistance through promoting the expression of thymidylate synthase. Thus, specific silence oflncRNA XIST could be a future direction to develop a novel therapeutic strategy to overcome 5FU resistance of CRC patients.

MEG3 is a prognostic factor for CRC and promotes chemosensitivity by enhancing oxaliplatin-induced cell apoptosis

A major reason for the failure of advanced colorectal cancer (CRC) treatment is the occurrence of chemoresistance to oxaliplatin-based chemotherapy. Recently, studies have shown that long non-coding RNAs (lncRNAs) play an important role in drug resistance. Using HiSeq sequencing methods, we identified that lncRNAs show differential expression levels in oxaliplatin-resistant (OxR) and non-resistant CRC patients. RT-qPCR was then performed in tissues and serum samples, and lncRNA MEG3 was verified to be downregulated in non-responding patients and to have considerable discriminating potential to identify responding patients from non-responding patients. Moreover, decreased serum MEG3 expression was associated with poor chemoresponse and low survival rate in CRC patients receiving oxaliplatin treatment. Subsequently, OxR cell lines were established, and MEG3 was significantly downregulated in HT29 OxR and SW480 OxR cells. In addition, overexpression of MEG3 with pMEG3 reversed oxaliplatin resistance in both CRC cell lines. Flow cytometric apoptosis analysis indicated that MEG3 promoted CRC cell apoptosis. More importantly, MEG3 enhanced oxaliplatin‑induced cell cytotoxicity in CRC. In conclusion, our integrated approach demonstrated that decreased expression of lncRNA MEG3 in CRC confers potent poor therapeutic efficacy, and that MEG3 promotes chemosensitivity by enhancing oxaliplatin-induced cell apoptosis. Thus, overexpression of MEG3 may be a future direction by which to develop a novel therapeutic strategy to overcome oxaliplatin resistance of CRC patients.

lncRNA HOTAIR Contributes to 5FU Resistance through Suppressing miR-218 and Activating NF-κB/TS Signaling in Colorectal Cancer

One major reason for the failure of advanced colorectal cancer (CRC) treatment is the occurrence of chemoresistance to fluoropyrimidine (FU)-based chemotherapy. Long non-coding RNA HOTAIR has been considered as a pro-oncogene in multiple cancers. However, the precise functional mechanism of HOTAIR in chemoresistance is not well known. In this study, we investigated the biological and clinical role of HOTAIR in 5FU resistance in CRC. Our results showed that HOTAIR negatively regulated miR-218 expression in CRC through an EZH2-targeting miR-218-2 promoter regulatory axis. HOTAIR knockdown dramatically inhibited cell viability and induced G1-phase arrest by promoting miR-218 expression. VOPP1 was shown to be a functional target of miR-218, and the main downstream signaling, NF-κB, was inactivated by HOTAIR through the suppression of miR-218 expression. Additionally, HOTAIR knockdown partially reversed 5FU resistance through promoting miR-218 and inactivating NF-κB signaling. Furthermore, HOTAIR restrained 5FU-induced cytotoxicity on CRC cells through promotion of thymidylate synthase expression. More importantly, high HOTAIR expression was associated with poor response to 5FU treatment. In conclusion, we demonstrated that HOTAIR contributes to 5FU resistance through suppressing miR-218 and activating NF-κB signaling in CRC. Thus, HOTAIR may serve as a promising therapeutic target for CRC patients.

Demethylation of the MIR145 promoter suppresses migration and invasion in breast cancer

miR-145 has been implicated in the progression of breast cancer. Here, we report that its expression is decreased in breast cancer specimens and cell lines and that this low level of expression is associated with DNA methylation of its gene, MIR145. Methylation of MIR145 has previously been correlated with cell migration and invasion, both in vivo and in vitro. We found that demethylation of MIR145 reactivates miR-145 and contributes to the anti-cancer properties of 5-aza-2'-deoxyazacytidine (5-AzaC). Therefore, miR-145 is a potentially valuable biomarker for breast cancer.

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

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

miR-506 enhances the sensitivity of human colorectal cancer cells to oxaliplatin by suppressing MDR1/P-gp expression

OBJECTIVES

Chemoresistance development represents a major obstacle to the successful treatment of colorectal cancer (CRC). The aim of this study was to elucidate the mechanism by which miR-506 reverses oxaliplatin chemoresistance in CRC.

METHODS

In this study, miR-506 levels were measured in 74 patients with colon cancer via quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH). We subsequently analysed the relationship between miR-506 expression and CRC patient survival via the Kaplan-Meier method. MTT assay demonstrated the fractional survival rates and cell viability of HCT116-OxR, HCT116-OxR-miR-Ctrl and HCT116-OxR-miR-506 cells treated with oxaliplatin at different concentrations. Cell proliferation and apoptosis were assessed via flow cytometry (FCM) analysis and apoptosis assay. MDR1 mRNA expression and P-gp protein expression were assessed via qRT-PCR and Western blotting (WB) respectively. Immunofluorescence (IF) staining demonstrated P-gp expression in HCT116-OxR and HCT116-OxR-miR-506 cells. qRT-PCR and WB were used to detect Wnt/β-catenin pathway activity after miR-506 overexpression.

RESULTS

In the present study, in ISH and qRT-PCR results demonstrated that miR-506 is weakly expressed in chemoresistant CRC tissues. The low miR-506 expression group exhibited lower 5-year OS and lower 5-year RFS than the high miR-506 expression group. miR-506 overexpression inhibited cell growth and increased oxaliplatin-induced cell apoptosis in HCT116-OxR cells, as shown via FCM and apoptosis assay. We subsequently noted low MDR1/P-gp expression in HCT116-OxR-miR-506 cells via qRT-PCR, WB and IF. Lastly, we demonstrated low MDR1/P-gp expression in HCT116-OxR-miR-506 cells via inhibition of the Wnt/β-catenin by WB, MTT and FCM analysis.

CONCLUSION

Taken together, the findings of our study demonstrate that miR-506 overexpression in HCT116-OxR cells enhances oxaliplatin sensitivity by inhibiting MDR1/P-gp expression via down-regulation of the Wnt/β-catenin pathway and thus provide a rationale for the development of miRNA-based strategies to reverse oxaliplatin resistance in CRC cells.

The Clinical Significance of MiR-429 as a Predictive Biomarker in Colorectal Cancer Patients Receiving 5-Fluorouracil Treatment

Background

5-Fluorouracil (5-FU) based treatment is the standard therapy for metastatic colorectal cancer (CRC), but the development of chemoresistance is inevitable. Increasing evidence shows that dysregulation of microRNAs (miRNAs) is involved in malignant transformation. Thus, it is imperative that we find new diagnostic and prognostic marker for chemotherapy in CRC.

Material/Methods

For clinical parameter analysis, 78 CRC tissues and adjacent normal tissues and 45 serum specimens from CRC patients were included in this study. For chemo-response analysis, 116 primary tissues were collected from the patients receiving first-line 5-FU treatment. Quantitative Real-Time PCR (qRT-PCR) was used to detect microRNAs expression.

Results

The expression of miR-429 was significantly increased in both serum and primary tissues from CRC patients, and enhanced miR-429 level was associated with tumor size, lymph node metastasis, and TNM stage. The diagnostic and prognostic values were also confirmed in CRC by using primary tissues. For patients receiving 5-FU-based treatment, miR-429 levels were significantly lower in responding group. The proportions of patients that did not experience response to therapy were higher in primary tumors with high miR-429 expression levels as compared with primary tumors with low miR-429 expression levels. Finally, Kaplan-Meier survival analysis showed that miR-429 is an independent prognostic indicator for chemo-response to 5-FU therapy among CRC patients.

Conclusions

High level of miR-429 expression was correlated with enhanced malignant potential and poor prognosis of CRC patients. Furthermore, miR-429 could affect the chemo-sensitivity of CRC patients to 5-FU therapy and was associated with poor response to 5-FU-based chemotherapy in patients with CRC.

Prognostic significance of low microRNA-218 expression in patients with different types of cancer: Evidence from published studies

BACKGROUND

Mounting evidence showed that microRNAs may be useful as prognostic biomarkers of cancer. Therefore, we summarize the predictive role of microRNA-218 (miR-218) for survival in patients with various cancers.

METHODS

We performed a systematic literature review and assessed the quality of included studies based on Meta-analysis of Observational Studies in Epidemiology group (MOOSE). Hazard ratios (HRs) with corresponding 95% confidence intervals (CIs) were calculated to assess the correlation between miR-218 expression and prognosis of different cancers.

RESULTS

We identified 10 studies for pooled analyses. For overall survival, a lower expression levels of miR-218 significantly predicted poorer survival, with the pooled HR of 2.61 (95% CI: 2.11-3.22, P < 0.001). For disease-free survival/progressive-free survival/recurrence-free survival (DFS/PFS/RFS), a lower expression level of miR-218 significantly predicted worse DFS/PFS/RFS in various carcinomas, with the pooled HR of 2.73 (95% CI: 2.08-3.58, P < 0.001). Similarly, subgroup analysis by detection method, ethnicity and cancer subtype analysis suggested that lower expression of miR-218 correlated with.

CONCLUSION

Our data demonstrated that lower miR-218 expression is significantly associated with poorer overall survival (OS) and DFS/PFS/RFS and may be a novel prognostic biomarker in some cancer types.

Reciprocal regulation of BMF and BIRC5 (Survivin) linked to Eomes overexpression in colorectal cancer

Eomesodermin (Eomes) is a T-box transcription factor that has been implicated in the etiology of colorectal cancer and other human malignancies. We screened a panel of human primary colon cancers and patient-matched controls (n = 30) and detected Eomes overexpression at the mRNA and protein level. Similar results were obtained in a panel of rat colon tumors and adjacent normal-looking colonic mucosa (n = 24). In human colon cancer cells, forced overexpression of Eomes enhanced cell viability and protected against staurosporine-induced apoptosis. On the other hand, knocking down Eomes resulted in reduced cell viability, G2/M cell cycle arrest, and apoptosis induction. The apoptotic mechanism centered on the reciprocal downregulation of anti-apoptotic BIRC5 (Survivin) and upregulation of proapoptotic Bcl-2 modifying factor (BMF). In patients with colorectal cancer, high EOMES expression (n = 95) was associated with poor overall survival compared with individuals exhibiting low EOMES levels (n = 80). We conclude from the current investigation, and prior literature, that Eomes has a divergent role in cancer development, with evidence for tumor suppressor and oncogenic functions, depending on stage and tissue context. Further studies are warranted on the apoptotic mechanisms linked to the reciprocal regulation of BMF and BIRC5 in human colorectal cancers characterized by Eomes overexpression.

Tumor-suppressing roles of miR-214 and miR-218 in breast cancer

MicroRNAs (miRNAs) are small non-coding RNAs that are key post-transcriptional regulators of gene expression. MicroRNA-214 (miR-214) and microRNA-218 (miR-218) have shown the function of tumor suppressors in various types of human cancers. However, the biological functions of miR-214 and miR-218 in breast cancer have not been elucidated completely. The present study evaluated the expression and biological function of miR-214 and miR-218 in human breast cancer. Our results revealed that the expression of miR-214 and miR-218 were significantly decreased in breast cancer tissues compared with adjacent tissues. The aberrant expression of miR-214 and miR-218 were negatively associated with Ki-67, and the miR-218 expression was positively associated with progesterone receptor (PR) in breast cancer tissues. In vitro, the cell proliferation and migration were decreased, cell apoptosis was induced, and cell cycle was also disturbed in miR-214 or miR-218 overexpressed breast cancer cells. Our results demonstrated that miR-214 and miR-218 function as tumor suppressors in breast cancer, and may become biomarkers and potential therapeutic targets in breast cancer.

miR-145 sensitizes gallbladder cancer to cisplatin by regulating multidrug resistance associated protein 1

Gallbladder cancer (GBC) is the most common malignancy in biliary tract with poor prognosis. Due to its high chemoresistance, systemic chemotherapies have had limited success in treating GBC patients. MicroRNAs (miRNAs) are emerging novel regulators of chemoresistance, which modulate the expression of drug resistance-related genes. In this study, we investigated the association between miR-145 expression and cisplatin sensitivity by both in vivo and in vitro analysis. Quantitative PCR (q-PCR) analysis indicated an increased miR-145 expression in GBC tissues. In addition, studies on GBC cell lines suggested an increased cisplatin efficacy with miR-145 overexpression, whereas decreasing miR-145 expression reduced cisplatin sensitivity. Further, we found that miR-145 accelerated MRP1 mRNA degradation by directly targeting its 3'-UTR and therefore caused increased cisplatin toxicity in GBC cells. Moreover, lower miR-145 and higher MRP1 expression levels predicted poor prognosis in GBC patients who received chemotherapy. Collectively, our findings established a rationale for using miR-145 expression as a biomarker to identify cisplatin-resistant GBC patients and propose that treatment strategies increasing the expression of miR-145 could be a new therapeutic approach for GBC patients.