miR-217 and CAGE form feedback loop and regulates the response to anti-cancer drugs through EGFR and HER2

Structural insight into crystal structure of helicase domain of DDX53

DEAD box helicase proteins are a family of RNA helicases that participate in various RNA metabolisms such as RNA unwinding, RNA processing, and RNPase activities. A particular DEAD box protein, the DDX53 protein, is primarily expressed in cancer cells and plays a crucial role in tumorigenesis. Numerous studies have revealed that DDX53 interacts with various microRNA and Histone deacetylases. However, its molecular structure and the detailed binding interaction between DDX53 and microRNA or HDAC is still unclear. In this study, we used X-ray crystallography to investigate the 3D structure of the hlicase C-terminal domain of DDX53, and successfully determined its crystal structure at a resolution of 1.97 Å. Subsequently, a functional analysis of RNA was conducted by examining the binding properties thereof with DDX53 by transmission electron microscopy and computing-based molecular docking simulation. The defined 3D model of DDX53 not only provides a structural basis for the fundamental understanding of DDX53 but is also expected to contribute to the field of anti-cancer drug discovery such as structure-based drug discovery and computer-aided drug design.

miR-429 Suppresses Endometrial Cancer Progression and Drug Resistance via DDX53

(1) Background: To examine miR-429-meditated DEAD (Asp-Glu-Ala-Asp) box polypeptide 53 (DDX53) function in endometrial cancer (EC). (2) Methods: DDX53 and miR-429 levels were measured using quantitative real-time polymerase chain reaction and western blotting assays, cell invasion and migration using Transwell invasion and wound healing assays, and cell proliferation using colony-forming/proliferation assays. A murine xenograft model was also generated to examine miR-429 and DDX53 functions in vivo. (3) Results: DDX53 overexpression (OE) promoted key cancer phenotypes (proliferation, migration, and invasion) in EC, while in vivo, DDX53 OE hindered tumor growth in the murine xenograft model. Moreover, miR-429 was identified as a novel miRNA-targeting DDX53, which suppressed EC proliferation and invasion. (4) Conclusions: DDX53 and miR-429 regulatory mechanisms could provide novel molecular therapies for EC.

DDX43 mRNA expression and protein levels in relation to clinicopathological profile of breast cancer

BACKGROUND

Breast cancer (BC) is the most often diagnosed cancer in women globally. Cancer cells appear to rely heavily on RNA helicases. DDX43 is one of DEAD- box RNA helicase family members. But, the relationship between clinicopathological, prognostic significance in different BC subtypes and DDX43 expression remains unclear. Therefore, the purpose of this study was to assess the clinicopathological significance of DDX43 protein and mRNA expression in different BC subtypes.

MATERIALS AND METHODS

A total of 80 females newly diagnosed with BC and 20 control females that were age-matched were recruited for this study. DDX43 protein levels were measured by ELISA technique. We used a real-time polymerase chain reaction quantification (real-time PCR) to measure the levels of DDX43 mRNA expression. Levels of DDX43 protein and mRNA expression within BC patients had been compared to those of control subjects and correlated with clinicopathological data.

RESULTS

The mean normalized serum levels of DDX43 protein were slightly higher in control than in both benign and malignant groups, but this result was non-significant. The mean normalized level of DDX43 mRNA expression was higher in the control than in both benign and malignant cases, although the results were not statistically significant and marginally significant, respectively. Moreover, the mean normalized level of DDX43 mRNA expression was significantly higher in benign than in malignant cases. In malignant cases, low DDX43 protein expression was linked to higher nuclear grade and invasive duct carcinoma (IDC), whereas high mRNA expression was linked to the aggressive types of breast cancer such as TNBC, higher tumor and nuclear grades.

CONCLUSION

This study explored the potential of using blood DDX43 mRNA expression or protein levels, or both in clinical settings as a marker of disease progression in human breast cancer. DDX43 mRNA expression proposes a less invasive method for discriminating benign from malignant BC.

Potential of the miR-200 Family as a Target for Developing Anti-Cancer Therapeutics

MicroRNAs (miRNAs) are small non-coding RNAs (18–24 nucleotides) that play significant roles in cell proliferation, development, invasion, cancer development, cancer progression, and anti-cancer drug resistance. miRNAs target multiple genes and play diverse roles. miRNAs can bind to the 3′UTR of target genes and inhibit translation or promote the degradation of target genes. miR-200 family miRNAs mostly act as tumor suppressors and are commonly decreased in cancer. The miR-200 family has been reported as a valuable diagnostic and prognostic marker. This review discusses the clinical value of the miR-200 family, focusing on the role of the miR-200 family in the development of cancer and anti-cancer drug resistance. This review also provides an overview of the factors that regulate the expression of the miR-200 family, targets of miR-200 family miRNAs, and the mechanism of anti-cancer drug resistance regulated by the miR-200 family.

The CAGE-MiR-181b-5p-S1PR1 Axis Regulates Anticancer Drug Resistance and Autophagy in Gastric Cancer Cells

Cancer-associated gene (CAGE), a cancer/testis antigen, has been known to promote anticancer drug resistance. Since the underlying mechanisms of CAGE-promoted anticancer drug resistance are poorly understood, we established Anticancer drug-resistant gastric cancer cells (AGS^R) to better elucidate possible mechanisms. AGS^R showed an increased expression level of CAGE and autophagic flux compared with anticancer drug-sensitive parental gastric cancer cells (AGS cells). AGS^R cells showed higher invasion potential, growth rate, tumor spheroid formation, and angiogenic potential than AGS cells. CAGE exerted effects on the response to anticancer drugs and autophagic flux. CAGE was shown to bind to Beclin1, a mediator of autophagy. Overexpression of CAGE increased autophagic flux and invasion potential but inhibited the cleavage of PARP in response to anticancer drugs in CAGE CRISPR–Cas9 cell lines. TargetScan analysis was utilized to predict the binding of miR-302b-5p to the promoter sequences of CAGE, and the results show that miR-302b-5p directly regulated CAGE expression as illustrated by luciferase activity. MiR-302b-5p regulated autophagic flux and the response to anticancer drugs. CAGE was shown to bind the promoter sequences of miR-302b-5p. The culture medium of AGS^R cells increased CAGE expression and autophagic flux in AGS cells. ImmunoEM showed CAGE was present in the exosomes of AGS^R cells; exosomes of AGS^R cells and human recombinant CAGE protein increased CAGE expression, autophagic flux, and resistance to anticancer drugs in AGS cells. MicroRNA array revealed miR-181b-5p as a potential negative regulator of CAGE. MiR-181b-5p inhibitor increased the expression of CAGE and autophagic flux in addition to preventing anticancer drugs from cleaving poly(ADP-ribose) polymerase (PARP) in AGS cells. TargetScan analysis predicted sphingosine 1-phosphate receptor 1 (SIPR1) as a potential target for miR-181b-5p. CAGE showed binding to the promoter sequences of S1PR1. The downregulation or inhibition of S1PR1 led to decreased autophagic flux but enhanced the sensitivity to anticancer drugs in AGS^R cells. This study presents a novel role of the CAGE–miR-181b-5p–S1PR1 axis in anticancer drug resistance and autophagy.

Improving Gemcitabine Sensitivity in Pancreatic Cancer Cells by Restoring miRNA-217 Levels

Chemoresistance is a major problem in the therapeutic management of pancreatic cancer, concurring to poor clinical outcome. A number of mechanisms have been proposed to explain resistance to gemcitabine, a standard of care for this malignancy, among which is included aberrant miRNA expression. In the current study, we investigated the role of miR-217, which is strongly down-regulated in cancerous, compared to normal, pancreatic tissues or cells, in sensitizing human pancreatic cancer cell lines to this drug. The low expression of miR-217 in pancreatic cancer patients was confirmed in two gene expression datasets (GSE41372 and GSE60980), and the prognostic value of two target genes (ANLN and TRPS1), was estimated on clinical data from the Tumor Cancer Genome Atlas (TCGA). Transfecting miR-217 mimic in pancreatic cancer cells reduced viability, enhanced apoptosis, and affected cell cycle by promoting a S phase arrest in gemcitabine-treated cells. Moreover, in drug-exposed cells subjected to miR-217 forced expression, a down-regulation for several genes involved in cancer drug resistance was observed, many of which are cell cycle regulators, such as CCND1, CCNE1, CDK2, CDKN1A, CDKN1B, while others, such as ARNT, BRCA1, BRCA2, ELK1, EGFR, ERBB4, and RARA are involved in proliferation and cell cycle progression. Our results support the notion that miR-217 enhances pancreatic cancer sensitivity to gemcitabine, mainly impairing cell cycle progression.

Histone Deacetylase Inhibitors to Overcome Resistance to Targeted and Immuno Therapy in Metastatic Melanoma

Therapies that target oncogenes and immune checkpoint molecules constitute a major group of treatments for metastatic melanoma. A mutation in BRAF (BRAF V600E) affects various signaling pathways, including mitogen activated protein kinase (MAPK) and PI3K/AKT/mammalian target of rapamycin (mTOR) in melanoma. Target-specific agents, such as MAPK inhibitors improve progression-free survival. However, BRAF^V600E mutant melanomas treated with BRAF kinase inhibitors develop resistance. Immune checkpoint molecules, such as programmed death-1 (PD-1) and programmed death ligand-1(PD-L1), induce immune evasion of cancer cells. MAPK inhibitor resistance results from the increased expression of PD-L1. Immune checkpoint inhibitors, such as anti-PD-L1 or anti-PD-1, are main players in immune therapies designed to target metastatic melanoma. However, melanoma patients show low response rate and resistance to these inhibitors develops within 6–8 months of treatment. Epigenetic reprogramming, such as DNA methylaion and histone modification, regulates the expression of genes involved in cellular proliferation, immune checkpoints and the response to anti-cancer drugs. Histone deacetylases (HDACs) remove acetyl groups from histone and non-histone proteins and act as transcriptional repressors. HDACs are often dysregulated in melanomas, and regulate MAPK signaling, cancer progression, and responses to various anti-cancer drugs. HDACs have been shown to regulate the expression of PD-1/PD-L1 and genes involved in immune evasion. These reports make HDACs ideal targets for the development of anti-melanoma therapeutics. We review the mechanisms of resistance to anti-melanoma therapies, including MAPK inhibitors and immune checkpoint inhibitors. We address the effects of HDAC inhibitors on the response to MAPK inhibitors and immune checkpoint inhibitors in melanoma. In addition, we discuss current progress in anti-melanoma therapies involving a combination of HDAC inhibitors, immune checkpoint inhibitors, and MAPK inhibitors.

Targeting Autophagy for Overcoming Resistance to Anti-EGFR Treatments

Epidermal growth factor receptor (EGFR) plays critical roles in cell proliferation, tumorigenesis, and anti-cancer drug resistance. Overexpression and somatic mutations of EGFR result in enhanced cancer cell survival. Therefore, EGFR can be a target for the development of anti-cancer therapy. Patients with cancers, including non-small cell lung cancers (NSCLC), have been shown to response to EGFR-tyrosine kinase inhibitors (EGFR-TKIs) and anti-EGFR antibodies. However, resistance to these anti-EGFR treatments has developed. Autophagy has emerged as a potential mechanism involved in the acquired resistance to anti-EGFR treatments. Anti-EGFR treatments can induce autophagy and result in resistance to anti-EGFR treatments. Autophagy is a programmed catabolic process stimulated by various stimuli. It promotes cellular survival under these stress conditions. Under normal conditions, EGFR-activated phosphoinositide 3-kinase (PI3K)/AKT serine/threonine kinase (AKT)/mammalian target of rapamycin (mTOR) signaling inhibits autophagy while EGFR/rat sarcoma viral oncogene homolog (RAS)/mitogen-activated protein kinase kinase (MEK)/mitogen-activated protein kinase (MAPK) signaling promotes autophagy. Thus, targeting autophagy may overcome resistance to anti-EGFR treatments. Inhibitors targeting autophagy and EGFR signaling have been under development. In this review, we discuss crosstalk between EGFR signaling and autophagy. We also assess whether autophagy inhibition, along with anti-EGFR treatments, might represent a promising approach to overcome resistance to anti-EGFR treatments in various cancers. In addition, we discuss new developments concerning anti-autophagy therapeutics for overcoming resistance to anti-EGFR treatments in various cancers.

Role of HDAC3-miRNA-CAGE Network in Anti-Cancer Drug-Resistance

Histone modification is associated with resistance to anti-cancer drugs. Epigenetic modifications of histones can regulate resistance to anti-cancer drugs. It has been reported that histone deacetylase 3 (HDAC3) regulates responses to anti-cancer drugs, angiogenic potential, and tumorigenic potential of cancer cells in association with cancer-associated genes (CAGE), and in particular, a cancer/testis antigen gene. In this paper, we report the roles of microRNAs that regulate the expression of HDAC3 and CAGE involved in resistance to anti-cancer drugs and associated mechanisms. In this review, roles of HDAC3-miRNAs-CAGE molecular networks in resistance to anti-cancer drugs, and the relevance of HDAC3 as a target for developing anti-cancer drugs are discussed.

CAGE Binds to Beclin1, Regulates Autophagic Flux and CAGE-Derived Peptide Confers Sensitivity to Anti-cancer Drugs in Non-small Cell Lung Cancer Cells

The objective of this study was to determine the role of CAGE, a cancer/testis antigen, in resistance of non-small cell lung cancers to anti-cancer drugs. Erlotinib-resistant PC-9 cells (PC-9/ER) with EGFR mutations (ex 19 del + T790M of EGFR), showed higher level of autophagic flux than parental sensitive PC-9 cells. Erlotinib and osimertinib increased autophagic flux and induced the binding of CAGE to Beclin1 in PC-9 cells. The inhibition or induction of autophagy regulated the binding of CAGE to Beclin1 and the responses to anti-cancer drugs. CAGE showed binding to HER2 while HER2 was necessary for binding of CAGE to Beclin1. CAGE was responsible for high level of autophagic flux and resistance to anti-cancer drugs in PC-9/ER cells. A peptide corresponding to the DEAD box domain of CAGE, ²⁶⁶AQTGTGKT²⁷³, enhanced the sensitivity of PC-9/ER cells to erlotinib and osimertinib, inhibited the binding of CAGE to Beclin1 and regulated autophagic flux in PC-9/ER cells. Mutant CAGE-derived peptide ²⁶⁶AQTGTGAT²⁷³ or ²⁶⁶AQTGTGKA²⁷³ did not affect autophagic flux or the binding of CAGE to Beclin1. AQTGTGKT peptide showed binding to CAGE, but not to Beclin1. FITC-AQTGTGKT peptide showed co-localization with CAGE. AQTGTGKT peptide decreased tumorigenic potentials of PC-9/ER and H1975 cells, non-small cell lung cancer (NSCLC) cells with EGFR mutation (L885R/T790M), by inhibiting autophagic fluxand inhibiting the binding of CAGE to Beclin1. AQTGTGKT peptide also enhanced the sensitivity of H1975 cells to anti-cancer drugs. AQTGTGKT peptide showed tumor homing potential based on ex vivo homing assays of xenograft of H1975 cells. AQTGTGKT peptide restored expression levels of miR-143-3p and miR-373-5p, decreased autophagic flux and conferred sensitivity to anti-cancer drugs. These results present evidence that combination of anti-cancer drug with CAGE-derived peptide could overcome resistance of non-small cell lung cancers to anti-cancer drugs.

Potential Regulatory Roles of MicroRNAs and Long Noncoding RNAs in Anticancer Therapies

MicroRNAs and long noncoding RNAs have long been investigated due to their roles as diagnostic and prognostic biomarkers of cancers and regulators of tumorigenesis, and the potential regulatory roles of these molecules in anticancer therapies are attracting increasing interest as more in-depth studies are performed. The major clinical therapies for cancer include chemotherapy, immunotherapy, and targeted molecular therapy. MicroRNAs and long noncoding RNAs function through various mechanisms in these approaches, and the mechanisms involve direct targeting of immune checkpoints, cooperation with exosomes in the tumor microenvironment, and alteration of drug resistance through regulation of different signaling pathways. Herein we review the regulatory functions and significance of microRNAs and long noncoding RNAs in three anticancer therapies, especially in targeted molecular therapy, and their mechanisms.

Role of DDX53 in taxol-resistance of cervix cancer cells in vitro

Cancer/Testis antigen DDX53 shows high expression level in various tumors and is involved in anti-cancer drug resistance. However, the functional study of DDX53 in cervix cancer remains unknown. In this study, the role of DDX53 in taxol-resistance of cervix cancer cells was investigated. In taxol-resistant Hela^TR cells, DDX53 was significantly increased as compared to the parental HeLa cells. Hela^TR cells also showed upregulation of multidrug resistant gene MDR1, invasive characteristics and decreased apoptosis. In addition, increased autophagy level was observed in Hela^TR cells. Overexpression of DDX53 in HeLa and SiHa markedly led to greater resistance to taxol and cisplatin, whereas knockdown of DDX53 in Hela^TR cells restored sensitivity, demonstrating that DDX53 regulated taxol resistance in cervix cancer cells. DDX53 overexpression in HeLa and SiHa cells enhanced invasion, migration and anchorage independent growth, DDX53 knockdown showed inverse effects in HeLa^TR cells. When DDX53 expression was suppressed by siRNA, autophagic flux and drug resistance of Hela^TR cells were decreased. In addition, DDX53 was upregulated in cervix cancer tissues from patient with a glassy cell carcinoma of cervix. Taken together, these results suggest that DDX53 plays a critical role in taxol-resistance by activating autophagy and a potential therapeutic target for the treatment of taxol-resistant cervix cancer.

Long non-coding RNA UCA1 desensitizes breast cancer cells to trastuzumab by impeding miR-18a repression of Yes-associated protein 1

Breast cancer resistance to the monoclonal erbB2/HER2 antibody trastuzumab (or herceptin) has become a significant obstacle in clinical targeted therapy of HER2-positive breast cancer. Previous research demonstrated that such drug resistance may be related to dysregulation of miRNA expression. Here, we found that knockdown of the long non-coding RNA, urothelial cancer associated 1 (UCA1), can promote the sensitivity of human breast cancer cells to trastuzumab. Mechanistically, UCA1 knockdown upregulated miR-18a and promoted miR-18a repression of Yes-associated protein 1 (YAP1). A luciferase reporter assay confirmed the association of miR-18a with wild-type UCA1 but not with UCA1 mutated at the predicted miR-18a-binding site. The direct targeting of YAP1 by miR-18a was verified by the observation that miR-18a mimic suppressed luciferase expression from a construct containing the YAP1 3' untranslated region. Meanwhile, reciprocal repression of UCA1 and miR-18a were found to be Argonaute 2-dependent. Knockdown of YAP1 recapitulated the effect of UCA1 silencing by reducing the viability of trastuzumab-treated breast cancer cells, whereas inhibition of miR-18a abrogated UCA1 knockdown-induced improvement of trastuzumab sensitivity in breast cancer cells. These findings demonstrate that the UCA1/miR-18a/YAP1 axis plays an important role in regulating the sensitivity of breast cancer cells to trastuzumab, which has implications for the development of novel approaches to improving breast cancer responses to targeted therapy.

miR-217 targeting DKK1 promotes cancer stem cell properties via activation of the Wnt signaling pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies and exhibits heterogeneity in terms of clinical outcomes and biological activities. Emerging evidence has demonstrated that cancer stem cells (CSCs) play important roles in the tumorigenesis and progression of HCC. However, the molecular mechanisms underlying the stemness maintenance of CSCs remain largely unknown. In the present study, through real-time PCR, western blotting, luciferase assays, RNA immunoprecipitation, and in vitro and in vivo assays, we demonstrated that miR-217 expression was markedly increased in HCC tissues and cells. Overexpression of miR-217 promoted, while silencing miR-217 suppressed, the fraction of the side population and the expression of cancer stem cell factors in vitro and tumorigenicity in vivo in HCC cells. Our findings further demonstrated that miR-217 promoted the CSC-like phenotype via dickkopf-1 (DKK1) targeting, resulting in constitutive activation of Wnt signaling. Moreover, the stimulatory effects of miR-217 on stem cell properties and Wnt signaling were antagonized by the upregulation of DKK1 in miR-217-overexpressing cells. Conversely, the inhibitory effects of silencing miR-217 on stem cell properties and Wnt signaling were reversed by the downregulation of DKK1 in miR-217-downregulated cells. Therefore, our results indicate that miR-217 plays a vital role in the CSC-like phenotypes of HCC cells and may be used as a potential therapeutic target against HCC.

DDX53 Regulates Cancer Stem Cell-Like Properties by Binding to SOX-2

This study investigated the role of cancer/testis antigen DDX53 in regulating cancer stem cell-like properties. DDX53 shows co-expression with CD133, a marker for cancer stem cells. DDX53 directly regulates the SOX-2 expression in anticancer drug-resistant Malme3MR cells. DDX53 and miR-200b were found to be involved in the regulation of tumor spheroid forming potential of Malme3M and Malme3MR cells. Furthermore, the self-renewal activity and the tumorigenic potential of Malme3MR-CD133 (+) cells were also regulated by DDX53. A miR-200b inhibitor induced the direct regulation of SOX-2 by DDX53 We therefore, conclude that DDX53 may serve as an immunotherapeutic target for regulating cancer stem-like properties of melanomas.

DDX53 Promotes Cancer Stem Cell-Like Properties and Autophagy

Although cancer/testis antigen DDX53 confers anti-cancer drug-resistance, the effect of DDX53 on cancer stem cell-like properties and autophagy remains unknown. MDA-MB-231 (CD133+) cells showed higher expression of DDX53, SOX-2, NANOG and MDR1 than MDA-MB-231 (CD133-). DDX53 increased in vitro self-renewal activity of MCF-7 while decreasing expression of DDX53 by siRNA lowered in vitro self-renewal activity of MDA-MB-231. DDX53 showed an interaction with EGFR and binding to the promoter sequences of EGFR. DDX53 induced resistance to anti-cancer drugs in MCF-7 cells while decreased expression of DDX53 by siRNA increased the sensitivity of MDA-MB-231 to anti-cancer drugs. Negative regulators of DDX53, such as miR-200b and miR-217, increased the sensitivity of MDA-MB-231 to anti-cancer drugs. MDA-MB-231 showed higher expression of autophagy marker proteins such as ATG-5, pBeclin1Ser15 and LC-3I/II compared with MCF-7. DDX53 regulated the expression of marker proteins of autophagy in MCF-7 and MDA-MB-231 cells. miR-200b and miR-217 negatively regulated the expression of autophagy marker proteins. Chromatin immunoprecipitation assays showed the direct regulation of ATG-5. The decreased expression of ATG-5 by siRNA increased the sensitivity to anti-cancer drugs in MDA-MB-231 cells. In conclusion, DDX53 promotes stem cell-like properties, autophagy, and confers resistance to anti-cancer drugs in breast cancer cells.