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

Genetic Biomarkers in Astrocytoma: Diagnostic, Prognostic, and Therapeutic Potential

Astrocytoma is the most common adult brain tumor, with glioblastoma being the deadliest neuro-related malignancy. Despite advances in oncology, the prognosis for astrocytoma, especially glioblastoma, remains poor, and tracking disease progression is challenging due to a lack of robust biomarkers. Genetic biomarkers, including microRNAs, cell-free DNA, circulating tumor DNA, circular RNA, and long noncoding RNA, can serve as potential diagnostic and therapeutic targets. In this review, we examine the existing literature, analyzing the various less established liquid and tumor genetic biomarkers and their potential to act as diagnostic, prognostic, and therapeutic targets. We highlight the clinical challenges and limitations in implementing liquid biopsy strategies in clinical practice. The article discusses the potential of liquid biopsies as valuable tools for personalized astrocytoma management while emphasizing the need for standardized protocols and further advancements to establish their clinical utility and therapeutic application.

Noncoding RNAs and programmed cell death in hepatocellular carcinoma: Significant role of epigenetic modifications in prognosis, chemoresistance, and tumor recurrence rate

Hepatocellular carcinoma (HCC) is the most common type of liver cancer with a high death rate in the world. The molecular mechanisms related to the pathogenesis of HCC have not been precisely defined so far. Hence, this review aimed to address the potential cross-talk between noncoding RNAs (ncRNAs) and programmed cell death in HCC. All related papers in the English language up to June 2023 were collected and screened. The searched keywords in scientific databases, including Scopus, PubMed, and Google Scholar, were HCC, ncRNAs, Epigenetic, Programmed cell death, Autophagy, Apoptosis, Ferroptosis, Chemoresistance, Tumor recurrence, Prognosis, and Prediction. According to the reports, ncRNAs, comprising long ncRNAs, microRNAs, circular RNAs, and small nucleolar RNAs can affect cell proliferation, migration, invasion, and metastasis, as well as cell death-related processes, such as autophagy, ferroptosis, necroptosis, and apoptosis in HCC by regulating cancer-associated genes and signaling pathways, for example, phosphoinositide 3-kinase/Akt, extracellular signal-regulated kinase/MAPK, and Wnt/β-catenin signaling pathways. It seems that ncRNAs, as epigenetic regulators, can be utilized as biomarkers in diagnosis, prognosis, survival and recurrence rates prediction, chemoresistance, and evaluation of therapeutic response in HCC patients. However, more scientific evidence is suggested to be accomplished to confirm these results.

Unrevealing the vital role of ncRNAs in Gastric Cancer chemoresistance

The high incidence of gastric cancer in many nations and poor overall survival rates has remained a serious global health concern. Chemoresistance in gastric cancer is a significant issue that hinders the efficacy of available treatment options. In gastric cancer, non-coding RNAs like microRNAs, long non-coding RNAs, and circular RNAs have become effective regulators of chemoresistance. These non-coding RNAs can influence several mechanisms, including drug efflux transporters, drug metabolism, and detoxification, cancer stem cells and the epithelial-mesenchymal transition, autophagy and apoptosis, and the tumor microenvironment. In this article review, we summarize the key roles non-coding RNAs play in the chemoresistance of gastric cancer and consider how they might be used in clinical settings as markers for diagnosis and prognosis, as well as potential targets and treatment plans. We also emphasize the need for additional study and collaborations in this area and highlight the difficulties and opportunities in non-coding RNA research for gastric cancer chemoresistance. This review offers crucial insights into the intricate relationship between non-coding RNAs and chemoresistance in gastric cancer, with implications for precision oncology and personalized medicine.

Oral squamous cell carcinomas: state of the field and emerging directions

Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% of oral malignancies and impairs appearance, pronunciation, swallowing, and flavor perception. In 2020, 377,713 OSCC cases were reported globally. According to the Global Cancer Observatory (GCO), the incidence of OSCC will rise by approximately 40% by 2040, accompanied by a growth in mortality. Persistent exposure to various risk factors, including tobacco, alcohol, betel quid (BQ), and human papillomavirus (HPV), will lead to the development of oral potentially malignant disorders (OPMDs), which are oral mucosal lesions with an increased risk of developing into OSCC. Complex and multifactorial, the oncogenesis process involves genetic alteration, epigenetic modification, and a dysregulated tumor microenvironment. Although various therapeutic interventions, such as chemotherapy, radiation, immunotherapy, and nanomedicine, have been proposed to prevent or treat OSCC and OPMDs, understanding the mechanism of malignancies will facilitate the identification of therapeutic and prognostic factors, thereby improving the efficacy of treatment for OSCC patients. This review summarizes the mechanisms involved in OSCC. Moreover, the current therapeutic interventions and prognostic methods for OSCC and OPMDs are discussed to facilitate comprehension and provide several prospective outlooks for the fields.

FTO-mediated epigenetic upregulation of LINC01559 confers cell resistance to docetaxel in breast carcinoma by suppressing miR-1343-3p

This study was to explore the regulatory effect of long non-coding RNA LINC01559 on Docetaxel resistance in breast carcinoma (BCa) and its underlying mechanism. In the present study, we found that LINC01559 expression was elevated and LINC01559 overexpression facilitated docetaxel resistance in BCa cells. Moreover, it was revealed that the upregulation of LINC01559 in BCa cells was induced by FTO-mediated demethylation in an m6A-YTHDF2-dependent manner. Additionally, Dual-luciferase reporter assay confirmed the binding ability between LINC01559 and miR-1343-3p, and Pearson correlation analysis showed a negative correlation between them. Particularly, miR-1343-3p inhibition partly abolished the suppression on docetaxel resistance in BCa cells caused by LINC01559 knockdown. To sum up, FTO-mediated epigenetic upregulation of LINC01559 promoted cell resistance to Docetaxel in BCa by negatively regulating miR-1343-3p.

Radix ranunculus temate saponins sensitizes ovarian cancer to Taxol via upregulation of miR‑let‑7b

A common cause of treatment failure in ovarian cancer is acquired drug resistance. Therefore, effective novel drugs against chemoresistance need to be developed. MicroRNAs (miRNAs or miRs) serve key regulatory roles in tumorigenesis and chemoresistance. The objective of the present study was to explore the role of miR-let-7b in ovarian cancer chemoresistance, and to develop novel strategy for the treatment of drug-resistant ovarian cancer. For this purpose, reverse transcription-quantitative PCR was performed to evaluate the expression level of miR-let-7b in fresh ovarian cancer tissues and cell lines. miR-let-7b mimic was transfected into ovarian cancer cell lines. Functional experiments, cell apoptosis and cell viability assays were carried out to identify the tumor-suppressor function of miR-let-7b. The treatment effect of Radix ranunculus temate saponins (RRTS), one of the primary constituents extracted from the traditional Chinese medicine radix Ranunculi ternati, was identified in vitro and in vivo. The results revealed that miR-let-7b was downregulated significantly in chemoresistant ovarian cancer patients. miR-let-7b overexpression suppressed cell growth and invasion and enhanced sensitivity to Taxol of ovarian cancer cells. Furthermore, miR-let-7b levels in ovarian cancer tissue were inversely associated with collagen type III α1 chain (COL3A1) levels. COL3A1, a non-fibrillar collagen associated with chemoresistance, was targeted by miR-let-7b. RRTS showed cytotoxic effects on ovarian cancer cells through inducing miR-let-7b expression and decreasing COL3A1 expression. In addition, RRTS sensitized ovarian cancer to Taxol both in vitro and in vivo. In conclusion, the present results revealed synergistic cytotoxicity of RRTS and Taxol on against ovarian cancer cells via upregulating expression of miR-let-7b. Combination of Taxol and RRTS may be a novel treatment strategy for patients with TR ovarian cancer.

Long noncoding RNA CBR3-AS1 mediates tumorigenesis and radiosensitivity of non-small cell lung cancer through redox and DNA repair by CBR3-AS1 /miR-409-3p/SOD1 axis

The long noncoding RNA CBR3-AS1 has important functions in various cancers. However, the biological functions of CBR3-AS1 in non-small cell lung cancer (NSCLC) remain unclear. This study aimed to investigate the roles and molecular mechanisms of CBR3-AS1 in NSCLC tumorigenesis and radiosensitivity. Here, we demonstrate CBR3-AS1 overexpression in NSCLC tissue compared with adjacent normal tissue. CBR3-AS1 downregulation reduced proliferation, invasion, and migration; inhibited cell cycle progression; and promoted apoptosis of NSCLC cells. CBR3-AS1 also promoted tumor growth in vivo. CBR3-AS1 may regulate the expression and functions of the miR-409-3p target gene SOD1. CBR3-AS1 expression was negatively correlated with radiosensitivity. CBR3-AS1 downregulation decreased post-irradiation SOD1 expression, increased γH2AX formation, raised levels of reactive oxygen species, and promoted apoptosis. Our results suggest that CBR3-AS1 functions as an oncogene through the CBR3-AS1/miR-409-3p/SOD1 pathway, and may represent a new therapeutic target, especially to regulate radiosensitivity in NSCLC.

LncRNA SNHG6 knockdown inhibits cisplatin resistance and progression of gastric cancer through miR-1297/BCL-2 axis

Cisplatin (DDP) resistance is a huge obstacle to gastric cancer (GC) treatment. Long non-coding RNAs (lncRNAs) have been manifested to exert pivotal functions in GC development. Herein, we aimed to explore the functional impact of lncRNA small nucleolar RNA host gene 6 (SNHG6) on DDP resistance and progression of GC. Quantitative real-time PCR (qRT-PCR) assay or Western blotting was performed to detect the expression of SNHG6, microRNA(miR)-1297, and epithelial-mesenchymal transition (EMT)-related factors and B-Cell Lymphoma 2 (Bcl-2) in DDP-resistant GC cells. Half inhibition concentration (IC50) to DDP, clonogenicity, apoptosis and invasion were examined via CCK-8 assay, colony formation assay, flow cytometry and Transwell assay, respectively. Target association between miR-1297 and SNHG6 or BCL-2 was demonstrated via dual-luciferase reporter assay or RIP assay. Xenograft models in nude mice were formed to investigate role of SNHG6 in vivo. We found that SNHG6 and BCL-2 were up-regulated, while miR-1297 expression was declined in GC tissues and DDP-resistant cells. Moreover, depletion of SNHG6 or gain of miR-1297 could repress DDP resistance, proliferation and metastasis of DDP-resistant cells, which was weakened by miR-1297 inhibition or BCL-2 overexpression. Besides, SNHG6 positively regulated BCL-2 expression by sponging miR-1297. Furthermore, SNHG6 knockdown repressed GC tumor growth in vivo. In a word, lncRNA SNHG6 knockdown had inhibitory effects on DDP resistance and progression of GC by sponging miR-1297, highlighting its potential in GC treatment.

Analyzing the whole-transcriptome profiles of ncRNAs and predicting the competing endogenous RNA networks in cervical cancer cell lines with cisplatin resistance

Background

Cervical cancer (CC) is one of the most common malignant tumors in women. In order to identify the functional roles and the interaction between mRNA and non-coding RNA (ncRNA, including lncRNA, circRNA and miRNA) in CC cisplatin (DDP) resistance, the transcription profile analysis was performed and a RNA regulatory model of CC DDP resistance was proposed.

Methods

In this study, whole-transcriptome sequencing analysis was conducted to study the ncRNA and mRNA profiles of parental SiHa cells and DDP resistant SiHa/DDP cells. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed for pathway analysis based on the selected genes with significant differences in expression. Subsequently, ceRNA network analyses were conducted using the drug resistance-related genes and signal-transduction pathways by Cytoscape software. Furthermore, a ceRNA regulatory pathway, namely lncRNA-AC010198.2/hsa-miR-34b-3p/STC2, was selected by RT-qPCR validation and literature searching. Further validation was done by both dual-luciferase reporter gene assays and RNA pull-down assays. Besides that, the changes in gene expression and biological function were further studied by performing si-AC010198.2 transfection and DDP resistance analyses in the SiHa and SiHa/DDP cells, respectively.

Results

Using bioinformatics and dual-luciferase reporter gene analyses, we found that AC010198.2/miR-34b-3p/STC2 may be a key pathway for DDP resistance in CC cells. Significant differences in both downstream gene expression and the biological function assays including colony formation, migration efficiency and cell apoptosis were identified in AC010198.2 knockdown cells.

Conclusions

Our study will not only provide new markers and potential mechanism models for CC DDP resistance, but also discover novel targets for attenuating it.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02239-6.

The long non-coding RNA HOTAIRM1 promotes tumor aggressiveness and radiotherapy resistance in glioblastoma

Glioblastoma is the most common malignant primary brain tumor. To date, clinically relevant biomarkers are restricted to isocitrate dehydrogenase (IDH) gene 1 or 2 mutations and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation. Long non-coding RNAs (lncRNAs) have been shown to contribute to glioblastoma pathogenesis and could potentially serve as novel biomarkers. The clinical significance of HOXA Transcript Antisense RNA, Myeloid-Specific 1 (HOTAIRM1) was determined by analyzing HOTAIRM1 in multiple glioblastoma gene expression data sets for associations with prognosis, as well as, IDH mutation and MGMT promoter methylation status. Finally, the role of HOTAIRM1 in glioblastoma biology and radiotherapy resistance was characterized in vitro and in vivo. We identified HOTAIRM1 as a candidate lncRNA whose up-regulation is significantly associated with shorter survival of glioblastoma patients, independent from IDH mutation and MGMT promoter methylation. Glioblastoma cell line models uniformly showed reduced cell viability, decreased invasive growth and diminished colony formation capacity upon HOTAIRM1 down-regulation. Integrated proteogenomic analyses revealed impaired mitochondrial function and determination of reactive oxygen species (ROS) levels confirmed increased ROS levels upon HOTAIRM1 knock-down. HOTAIRM1 knock-down decreased expression of transglutaminase 2 (TGM2), a candidate protein implicated in mitochondrial function, and knock-down of TGM2 mimicked the phenotype of HOTAIRM1 down-regulation in glioblastoma cells. Moreover, HOTAIRM1 modulates radiosensitivity of glioblastoma cells both in vitro and in vivo. Our data support a role for HOTAIRM1 as a driver of biological aggressiveness, radioresistance and poor outcome in glioblastoma. Targeting HOTAIRM1 may be a promising new therapeutic approach.

miR-139-5p sponged by LncRNA NEAT1 regulates liver fibrosis via targeting β-catenin/SOX9/TGF-β1 pathway

Liver fibrosis is a patho-physiological process which can develop into cirrhosis, and hepatic carcinoma without intervention. Our study extensively investigated the mechanisms of lncRNA NEAT1 and miR-139-5p in regulating liver fibrosis progression. Our results demonstrated that the expression of lncRNA NEAT1 was increased and the expression of miR-139-5p was decreased in fibrotic liver tissues. LncRNA NEAT1 could sponge miR-139-5p and promoted hepatic stellate cells (HSCs) activation by directly inhibiting the expression of miR-139-5p. The co-localization of lncRNA NEAT1 with miR-139-5p was shown in the cytosols of activated HSCs. miR-139-5p upregulation could suppress the expression of β-catenin. The overexpression of β-catenin promoted HSCs activation. Moreover, we found that β-catenin could interact with SOX9 promoted HSCs activation. Our further studies demonstrated that SOX9 could bind with the TGF-β1 promoter and promoted the transcription activity of TGF-β1. The upregulation of TGF-β1 further promoted HSCs activation. In vivo study also suggested that lncRNA NEAT1 knockdown and miR-139-5p overexpression alleviated murine liver fibrosis. LncRNA NEAT1 exacerbated liver fibrosis by suppressing the expression of miR-139-5p. Collectively, our study suggested that miR-139-5p sponged by lncRNA NEAT1 regulated liver fibrosis via targeting β-catenin/SOX9/TGF-β1 Pathway.

Long noncoding RNA SATB1-AS1 contributes to the chemotherapy resistance through the microRNA-580/ 2'-5'-oligoadenylate synthetase 2 axis in acute myeloid leukemia

Acute myeloid leukemia (AML) represents a hematopoietic cancer with an invasive property. Chemoresistance blunts the therapeutic effect of chemotherapeutics in AML. Long noncoding RNAs (lncRNAs) have been implicated in chemotherapy resistance in AML. Transcriptome sequencing in the current study was applied to clarify the differentially expressed lncRNAs between peripheral blood mononuclear cells of AML and normal samples. The expression of special AT-rich sequence binding protein 1 antisense RNA 1 (SATB1-AS1) and 2ʹ-5ʹ-oligoadenylate synthetase 2 (OAS2) in AML patients was evaluated by qRT-PCR. The relationships among SATB1-AS1, microRNA-580 (miR-580) and OAS2 were investigated by dual-luciferase reporter assay. We observed that SATB1-AS1 and OAS2 were upregulated, while miR-580 was downregulated in AML patients. SATB1-AS1 depletion suppressed proliferation, and enhanced apoptosis and sensitivity of AML cells. Additionally, SATB1-AS1 promoted the expression of OAS2 by acting as a molecular sponge of miR-580 in AML. miR-580 downregulation, OAS2 overexpression and a selective glycogen synthase kinase (GSK)-3β inhibitor AR-A014418 abolished the effects of SATB1-AS1 deletion on the chemosensitivity of AML cells. In conclusion, SATB1-AS1 knockdown promotes the sensitivity of AML cells by upregulating miR-580 and downregulating OAS2 through the GSK3β/β-catenin pathway, providing new insights into the function of SATB1-AS1 as a miRNA sponge in AML.

LncRNA-HEIH is a Novel Diagnostic and Predictive Biomarker in Gastric Cancer

Background: Gastric cancer (GC) is associated with a high mortality rate. Long noncoding RNA (lncRNA)-high expressed in hepatocellular carcinoma (HEIH) has recently gained interest as a marker for the detection of several cancer types. This study was designed to uncover the function of lncRNA-HEIH in GC. Materials and Methods: Oncomine was used to analyze HEIH expression in cancerous and paired noncancerous tissues of GC patients. Subsequently, the expression levels of HEIH in GC cells was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, the effects of HEIH expression level on clinicopathological parameters and prognosis were further studied by statistical analysis and Kaplan-Meier survival curves. GC cell proliferation and the influence of HEIH on the sensitivity of cells to oxaliplatin following HEIH knockdown were assessed using sulforhodamine blue (SRB) assays in the MKN45 and AGS cell lines. In addition, the expression levels of p53 were detected by RT-qPCR following knockdown of HEIH. Results: The lncRNA-HEIH was highly expressed in both GC tissues and GC cell lines. Patients with high HEIH expression were associated with medium-high differentiation (p = 0.0058), distant metastasis (M, p = 0.0378), lymph node metastasis (N, p = 0.0083), and a deeper tumor invasion (T, p = 0.0204). The elevated expression levels of HEIH in GC patients were associated with a worse prognosis compared to GC patients with low HEIH expression. This finding was supported by the parameters overall survival (p = 3.3e-06), first progression (p = 0.00028), and postprogression (p = 1.5e-08). Downregulation of HEIH expression inhibited cell proliferation, enhanced oxaliplatin sensitivity, and induced the expression of p53 in MKN45 and AGC cells. Conclusion: These findings provide evidence that HEIH may be useful as a prognostic biomarker in GC. This lncRNA may also serve as a potential therapeutic target in GC patients.

Downregulation of NEAT1 sensitizes gemcitabine-resistant pancreatic cancer cells to gemcitabine through modulation of the miR-506-3p/ZEB2/EMT axis

Chemoresistance is a major cause of treatment failure in pancreatic cancer (PC). It has been demonstrated that epithelial-to-mesenchymal transition (EMT) is closely related to drug resistance in PC; however, the underlying mechanisms are not yet fully understood. Recently found evidence has suggested that nuclear-enriched abundant transcript 1 (NEAT1) is involved in the development of chemoresistance. However, the role and mechanism of NEAT1 in PC gemcitabine resistance remain unknown. In the present study, we first established two independent gemcitabine-resistant (GR) PC cell lines, PANC-1/GR and SW1990/GR. We found that GR cells displayed markedly enhanced migration and invasion abilities, decreased expression of E-cadherin, and upregulation of N-cadherin, Vimentin, Snail, ZEB1, and ZEB2. Our findings suggested that downregulation of NEAT1 enhanced the sensitivity of GR cells to gemcitabine by reversing the EMT process. Mechanistically, NEAT1 mediates ZEB2 mRNA expression through sponging miR-506-3p. Downregulation of NEAT1 can reverse the EMT process of GR PC cells by reducing the expression of ZEB2, thus enhancing the sensitivity of GR PC cells to gemcitabine. These findings were further confirmed in a nude mouse xenograft model. Taken together, downregulation of NEAT1 sensitized the GR PC cells to gemcitabine through modulation of the miR-506-3p/ZEB2/EMT axis. These results provide the novel evidence for understanding the function and molecular mechanism of NEAT1, and a new direction for improving the chemotherapeutic effects in PC.

Long non-coding RNAs orchestrate various molecular and cellular processes by modulating epithelial-mesenchymal transition in head and neck squamous cell carcinoma

Long noncoding RNAs (lncRNAs) regulate various hallmarks associated with the progression of human cancers through their binding with RNA, DNA, and proteins. Epithelial-Mesenchymal Transition (EMT) is a cardinal and multi-stage process where epithelial cells acquire a mesenchymal-like phenotype that is instrumental for tumor cells to initiate invasion and metastasis. LncRNAs can potentially promote tumor onset and progression as well as drug resistance by directly or indirectly altering the EMT program. Head and neck squamous cell carcinoma (HNSCC) are a dreadful malignancy affecting public health globally. The past few years have provided a better insight into the mechanism of EMT in HNSCC. The differential expression of the lncRNAs that can act either as promoters or suppressors in the process of EMT is of great importance. In this review, we aim to sum up, the highly structured mechanism with the diverse role of lncRNAs and their interaction with different molecules in the regulation of EMT. Moreover, discussing principal EMT pathways modulated by lncRNAs and their prospective potential value as therapeutic targets.

Non-coding RNAs as Novel Biomarkers in Cancer Drug Resistance

Chemotherapy is often the primary and most effective anticancer treatment; however, drug resistance remains a major obstacle to it being curative. Recent studies have demonstrated that non-coding RNAs (ncRNAs), especially microRNAs and long non-coding RNAs, are involved in drug resistance of tumor cells in many ways, such as modulation of apoptosis, drug efflux and metabolism, epithelial-to-mesenchymal transition, DNA repair, and cell cycle progression. Exploring the relationships between ncRNAs and drug resistance will not only contribute to our understanding of the mechanisms of drug resistance and provide ncRNA biomarkers of chemoresistance, but will also help realize personalized anticancer treatment regimens. Due to the high cost and low efficiency of biological experimentation, many researchers have opted to use computational methods to identify ncRNA biomarkers associated with drug resistance. In this review, we summarize recent discoveries related to ncRNA-mediated drug resistance and highlight the computational methods and resources available for ncRNA biomarkers involved in chemoresistance.

An Overview of the Role of Long Non-Coding RNAs in Human Choriocarcinoma

Choriocarcinoma (CC), a subtype of trophoblastic disease, is a rare and highly aggressive neoplasm. There are two main CC subtypes: gestational and non-gestational, (so called when it develops as a component of a germ cell tumor or is related to a somatic mutation of a poorly differentiated carcinoma), each with very diverse biological activity. A therapeutic approach is highly effective in patients with early-stage CC. The advanced stage of the disease also has a good prognosis with around 95% of patients cured following chemotherapy. However, advancements in diagnosis and treatment are always needed to improve outcomes for patients with CC. Long non-coding (lnc) RNAs are non-coding transcripts that are longer than 200 nucleotides. LncRNAs can act as oncogenes or tumor suppressor genes. Deregulation of their expression has a key role in tumor development, angiogenesis, differentiation, migration, apoptosis, and proliferation. Furthermore, detection of cancer-associated lncRNAs in body fluids, such as blood, saliva, and urine of cancer patients, is emerging as a novel method for cancer diagnosis. Although there is evidence for the potential role of lncRNAs in a number of cancers of the female genital tract, their role in CC is poorly understood. This review summarizes the current knowledge of lncRNAs in gestational CC and how this may be applied to future therapeutic strategies in the treatment of this rare cancer.

LncRNA UCA1 elevates the resistance of human leukemia cells to daunorubicin by the PI3K/AKT pathway via sponging miR-613

Acute leukemia is a hematological malignant tumor. Long non-coding RNA urothelial cancer-associated 1 (UCA1) is involved in the chemo-resistance of diverse cancers, but it is unclear whether UCA1 is associated with the sensitivity of acute leukemia cells to daunorubicin (DNR). DNR (100 nM) was selected for functional analysis. The viability, cell cycle progression, apoptosis, and invasion of treated acute leukemia cells (HL-60 and U-937) were evaluated by cell counting kit-8 (CCK-8) assay, flow cytometry assay, or transwell assay. Protein levels were detected with Western blot analysis. Expression patterns of UCA1 and miR-613 were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). The relationship between UCA1 and microRNA-613 (miR-613) was verified by dual-luciferase reporter assay. We observed that UCA1 expression was elevated in HL-60 and U-937cells. DNR constrained viability, cell cycle progression, invasion, and facilitated apoptosis of HL-60 and U-937 cells in a dose-dependent manner, but these impacts mediated by DNR were reverted after UCA1 overexpression. MiR-613 was down-regulated in HL-60 and U-937 cells, and UCA1 was verified as a miR-613 sponge. MiR-613 inhibitor reversed DNR treatment-mediated effects on viability, cell cycle progression, apoptosis, and invasion of HL-60 and U-937 cells, but these impacts mediated by miR-613 inhibitor were counteracted after UCA1 inhibition. Notably, the inactivation of the PI3K/AKT pathway caused by DNR treatment was reversed after miR-613 inhibitor introduction, but this influence mediated by miR-613 inhibitor was offset after UCA1 knockdown. In conclusion, UCA1 up-regulation facilitated the resistance of acute leukemia cells to DNR via the PI3K/AKT pathway by sponging miR-613.

An Analysis of Mechanisms for Cellular Uptake of miRNAs to Enhance Drug Delivery and Efficacy in Cancer Chemoresistance

Up until recently, it was believed that pharmaceutical drugs and their metabolites enter into the cell to gain access to their targets via simple diffusion across the hydrophobic lipid cellular membrane, at a rate which is based on their lipophilicity. An increasing amount of evidence indicates that the phospholipid bilayer-mediated drug diffusion is in fact negligible, and that drugs pass through cell membranes via proteinaceous membrane transporters or carriers which are normally used for the transportation of nutrients and intermediate metabolites. Drugs can be targeted to specific cells and tissues which express the relevant transporters, leading to the design of safe and efficacious treatments. Furthermore, transporter expression levels can be manipulated, systematically and in a high-throughput manner, allowing for considerable progress in determining which transporters are used by specific drugs. The ever-expanding field of miRNA therapeutics is not without its challenges, with the most notable one being the safe and effective delivery of the miRNA mimic/antagonist safely to the target cell cytoplasm for attaining the desired clinical outcome, particularly in miRNA-based cancer therapeutics, due to the poor efficiency of neo-vascular systems revolting around the tumour site, brought about by tumour-induced angiogenesis. This acquisition of resistance to several types of anticancer drugs can be as a result of an upregulation of efflux transporters expression, which eject drugs from cells, hence lowering drug efficacy, resulting in multidrug resistance. In this article, the latest available data on human microRNAs has been reviewed, together with the most recently described mechanisms for miRNA uptake in cells, for future therapeutic enhancements against cancer chemoresistance.

The role of miRNAs and lncRNAs in conferring resistance to doxorubicin

Doxorubicin is a chemotherapeutic agent that inhibits topoisomerase II, intercalates within DNA base pairs and results in oxidative DNA damage, thus inducing cell apoptosis. Although it is effective in the treatment of a wide range of human cancers, the emergence of resistance to this drug can increase tumour growth and impact patients' survival. Numerous molecular mechanisms and signalling pathways have been identified that induce resistance to doxorubicin via stimulation of cell proliferation, cell cycle switch and preclusion of apoptosis. A number of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) have also been identified that alter sensitivity to doxorubicin. Understanding the particular impact of these non-coding RNAs in conferring resistance to doxorubicin has considerable potential to improve selection of chemotherapeutic regimens for cancer patients. Moreover, modulation of expression of these transcripts is a putative strategy for combating resistance. In the current paper, the influence of miRNAs and lncRNAs in the modification of resistance to doxorubicin is discussed.

The Mechanistic Roles of ncRNAs in Promoting and Supporting Chemoresistance of Colorectal Cancer

Colorectal Cancer (CRC) is one of the most common gastrointestinal malignancies which has quite a high mortality rate. Despite the advances made in CRC treatment, effective therapy is still quite challenging, particularly due to resistance arising throughout the treatment regimen. Several studies have been carried out to identify CRC chemoresistance mechanisms, with research showing different signalling pathways, certain ATP binding cassette (ABC) transporters and epithelial mesenchymal transition (EMT), among others to be responsible for the failure of CRC chemotherapies. In the last decade, it has become increasingly evident that certain non-coding RNA (ncRNA) families are involved in chemoresistance. Research investigations have demonstrated that dysregulation of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) contribute towards promoting resistance in CRC via different mechanisms. Considering the currently available data on this phenomenon, a better understanding of how these ncRNAs participate in chemoresistance can lead to suitable solutions to overcome this problem in CRC. This review will first focus on discussing the different mechanisms of CRC resistance identified so far. The focus will then shift onto the roles of miRNAs, lncRNAs and circRNAs in promoting 5-fluorouracil (5-FU), oxaliplatin (OXA), cisplatin and doxorubicin (DOX) resistance in CRC, specifically using ncRNAs which have been recently identified and validated under in vivo or in vitro conditions.

Long noncoding RNAs have pivotal roles in chemoresistance of acute myeloid leukemia

Many patients with acute myeloid leukemia (AML) experience poor outcomes following traditional high-dose chemotherapies and complete remission rates remain suboptimal. Chemoresistance is an obstacle to effective chemotherapy and the precise mechanisms involved remain to be determined. Recently, long noncoding RNAs (lncRNAs) have been identified as relevant factors in the development of drug resistance in patients with AML. Furthermore, accumulating data support the importance of lncRNAs as potentially useful novel therapeutic targets in many cancers. Here, we review the role of lncRNAs in the development and induction of the chemoresistance in AML, and suggest lncRNAs as novel molecular markers for diagnosis, prediction of patient response to chemotherapy, and novel therapeutic targets for AML.

Circular RNA circCSPP1 knockdown attenuates doxorubicin resistance and suppresses tumor progression of colorectal cancer via miR-944/FZD7 axis

BACKGROUND

Circular RNAs (circRNAs) have been reported to play vital roles in colorectal cancer (CRC). However, only a few circRNAs have been experimentally validated and functionally described. In this research, we aimed to reveal the functional mechanism of circCSPP1 in CRC.

METHODS

36 DOX sensitive and 36 resistant CRC cases participated in this study. The expression of circCSPP1, miR-944 and FZD7 were detected by quantitative real time polymerase chain reaction (qRT-PCR) and the protein levels of FZD7, MRP1, P-gp and LRP were detected by western blot. Cell proliferation, migration, invasion, and apoptosis were assessed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay, transwell assay, or flow cytometry analysis, respectively. The interaction between miR-944 and circCSPP1 or frizzled-7 (FZD7) was predicted by Starbase 3.0 and verified by the dual luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull down assay. Xenograft tumor assay was performed to examine the effect of circCSPP1 on tumor growth in vivo.

RESULTS

The expression of circCSPP1 and FZD7 was upregulated while miR-944 expression was downregulated in doxorubicin (DOX)-resistant CRC tissues and cells. CircCSPP1 knockdown significantly downregulated enhanced doxorubicin sensitivity, suppressed proliferation, migration, invasion, and induced apoptosis in DOX-resistant CRC cells. Interestingly, we found that circCSPP1 directly downregulated miR-944 expression and miR-944 decreased FZD7 level through targeting to 3' untranslated region (UTR) of FZD7. Furthermore, circCSPP1 mediated DOX-resistant CRC cell progression and doxorubicin sensitivity by regulating miR-944/FZD7 axis. Besides, circCSPP1 downregulation dramatically repressed CRC tumor growth in vivo.

CONCLUSION

Our data indicated that circCSPP1 knockdown inhibited DOX-resistant CRC cell growth and enhanced doxorubicin sensitivity by miR-944/FZD7 axis, providing a potential target for CRC therapy.

MiRNA-200C expression in Fanconi anemia pathway functionally deficient lung cancers

The Fanconi Anemia (FA) pathway is essential for human cells to maintain genomic integrity following DNA damage. This pathway is involved in repairing damaged DNA through homologous recombination. Cancers with a defective FA pathway are expected to be more sensitive to cross-link based therapy or PARP inhibitors. To evaluate downstream effectors of the FA pathway, we studied the expression of 734 different micro RNAs (miRNA) using NanoString nCounter miRNA array in two FA defective lung cancer cells and matched control cells, along with two lung tumors and matched non-tumor tissue samples that were deficient in the FA pathway. Selected miRNA expression was validated with real-time PCR analysis. Among 734 different miRNAs, a cluster of microRNAs were found to be up-regulated including an important cancer related micro RNA, miR-200C. MiRNA-200C has been reported as a negative regulator of epithelial-mesenchymal transition (EMT) and inhibits cell migration and invasion by promoting the upregulation of E-cadherin through targeting ZEB1 and ZEB2 transcription factors. miRNA-200C was increased in the FA defective lung cancers as compared to controls. AmpliSeq analysis showed significant reduction in ZEB1 and ZEB2 mRNA expression. Our findings indicate the miRNA-200C potentially play a very important role in FA pathway downstream regulation.

Taxanes in cancer treatment: Activity, chemoresistance and its overcoming

Since 1984, when paclitaxel was approved by the FDA for the treatment of advanced ovarian carcinoma, taxanes have been widely used as microtubule-targeting antitumor agents. However, their historic classification as antimitotics does not describe all their functions. Indeed, taxanes act in a complex manner, altering multiple cellular oncogenic processes including mitosis, angiogenesis, apoptosis, inflammatory response, and ROS production. On the one hand, identification of the diverse effects of taxanes on oncogenic signaling pathways provides opportunities to apply these cytotoxic drugs in a more rational manner. On the other hand, this may facilitate the development of novel treatment modalities to surmount anticancer drug resistance. In the latter respect, chemoresistance remains a major impediment which limits the efficacy of antitumor chemotherapy. Taxanes have shown impact on key molecular mechanisms including disruption of mitotic spindle, mitosis slippage and inhibition of angiogenesis. Furthermore, there is an emerging contribution of cellular processes including autophagy, oxidative stress, epigenetic alterations and microRNAs deregulation to the acquisition of taxane resistance. Hence, these two lines of findings are currently promoting a more rational and efficacious taxane application as well as development of novel molecular strategies to enhance the efficacy of taxane-based cancer treatment while overcoming drug resistance. This review provides a general and comprehensive picture on the use of taxanes in cancer treatment. In particular, we describe the history of application of taxanes in anticancer therapeutics, the synthesis of the different drugs belonging to this class of cytotoxic compounds, their features and the differences between them. We further dissect the molecular mechanisms of action of taxanes and the molecular basis underlying the onset of taxane resistance. We further delineate the possible modalities to overcome chemoresistance to taxanes, such as increasing drug solubility, delivery and pharmacokinetics, overcoming microtubule alterations or mitotic slippage, inhibiting drug efflux pumps or drug metabolism, targeting redox metabolism, immune response, and other cellular functions.

Dysregulation of lnc-SNHG1 and miR-216b-5p correlate with chemoresistance and indicate poor prognosis of serous epithelial ovarian cancer

Aim

This study aimed to explore whether the dysregulation of lnc-small nucleolar RNA host gene 1 (SNHG1) and miR-216b-5p correlated with chemoresistance and indicated poor prognosis of serous epithelial ovarian cancer (EOC).

Methods and results

The expression of lnc-SNHG1 was upregulated, while miR-216b-5p showed low expression in patients with chemoresistant EOC compared with patients with chemosensitive EOC. The multivariate Cox regression analysis showed that the expression of miR-216b-5p and FIGO stage were independent prognostic factors for the overall survival (OS) of patients with serous EOC. Kaplan–Meier curves revealed a significant association of the increased expression level of lnc-SNHG1 with shorter OS and disease-free survival (DFS). Patients with a low expression level of miR-216b-5p also had shorter OS and DFS. The biological functions were tested using CCK-8 assay, colony formation assay, wound healing assay, and cell apoptosis. The knockdown of SNHG1 and the overexpression of miR-216b-5p stimulated paclitaxel sensitivity in A2780/Taxol cells through inhibiting cell growth and migration and promoting apoptosis. The inhibition of miR-216b-5p could rescue the effect of lnc-SNHG1 inhibition on the sensitivity of A2780/Taxol cells to paclitaxel. Luciferase reporter assay, RNA Binding Protein Immunoprecipitation Assay (RIP), and quantitative reverse transcription–polymerase chain reaction (qRT-PCR) indicated that lnc-SNHG1 acted as a sponge of miR-216b-5p in A2780/Taxol cells.

Conclusions

This study showed that the overexpression of lnc-SNHG1 and decreased expression level of miR-216b-5p correlated with the chemoresistance of patients with serous EOC and indicated shorter OS and DFS. Lnc-SNHG1 functioned as a ceRNA with miR-216b-5p, which was critical in modulating the paclitaxel sensitivity of ovarian cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-020-00750-4.

ncDRMarker: a computational method for identifying non-coding RNA signatures of drug resistance based on heterogeneous network

Background

Drug resistance is the primary cause of failure in the treatment of cancer. Identifying signatures of chemoresistance will help to overcome this problem. Current drug resistance studies focus on protein-coding genes and ignore non-coding RNAs (ncRNAs), rendering it a challenging task to systematically identify ncRNAs involved in drug resistance.

Methods

In this study, protein-protein, miRNA-target gene, miRNA-lncRNA interactions were integrated to construct a mRNA-miRNA-lncRNA network. Then, the random walk with restart (RWR) method was extended to the network for identifying ncRNA signatures of drug resistance. The leave-one-out cross validation (LOOCV) and receiver operating characteristic curve (ROC) were used to estimate the performance of ncDRMarker. Wilcoxon rank-sum test was used to validate the identified ncRNAs in NCI-60 cancer cell lines. KEGG pathway enrichment analysis was implemented to characterize the biological function of some identified ncRNAs.

Results

We performed this method on ten common clinical chemotherapy drugs and analyzed the results in detail. The region beneath the ROC was up to 0.881–0.951, which did not change significantly in the incomplete network, indicating the high performance and robustness of the method. Further, we confirmed the role of the identified ncRNAs in drug resistance, i.e., miR-92a-3p, a candidate chemoresistance ncRNA of tamoxifen and paclitaxel, can significantly classify cancer cell lines into sensitive or resistant to tamoxifen (or paclitaxel). We also dissected the mRNA-miRNA-lncRNA composite network and found that some hub ncRNAs, such as miR-124-3p, were involved in resistance of multiple drugs and engaged in many significant cancer-related pathways. Lastly, we have provided a ncDRMarker platform for users to identify candidate ncRNAs of drug resistance, which is available at http://bio-bigdata.hrbmu.edu.cn/ncDRMarker/index.

Conclusions

Our findings suggest that ncDRMarker is an effective computational technique for prioritizing candidate ncRNAs of drug resistance. Additionally, the identified ncRNAs could be targeted to overcome drug resistance and help realize individualized treatment.

LncRNA LINC01116 Contributes to Cisplatin Resistance in Lung Adenocarcinoma

Background

Long non-coding RNAs (lncRNAs) have been found to contribute to cisplatin resistance in several cancers; however, the role of lncRNA LINC01116 in cisplatin resistance remains unknown in non-small-cell lung cancer. This study aimed to examine the contribution of LINC01116 to cisplatin resistance in lung adenocarcinoma (LAD).

Materials and Methods

Cisplatin-resistant A549/DDP cells were generated by treatment with cisplatin by dose escalation. LINC01116 expression was compared between A549 and A549/DDP cells, and between cisplatin-resistant and non-resistant LAD specimens. The cell viability, colony formation, proliferation, migration and invasion were measured using MTT and Transwell assays, and cell apoptosis and cell cycle were detected using flow cytometry. The expression of E-cadherin and Vimentin was quantified. LAD xenografts were modeled in nude mice to investigate the role of LINC01116 on the resistance of LAD to cisplatin.

Results

MTT assay measured the IC₅₀ values of 13.49 ± 1.62 and 3.52 ± 1.33 μg/mL for A549/DDP and A549 cells, respectively. LINC01116 was overexpressed in cisplatin-resistant LAD specimens and A549/DDP cells (P < 0.05). Knockdown of LINC01116 inhibited cell viability, proliferation, migration and invasion, promoted apoptosis and enhanced the sensitivity to cisplatin in A549/DDP cells, while LINC01116 overexpression promoted cell viability, proliferation, migration and invasion, inhibited apoptosis and reduced the sensitivity to cisplatin in A549 cells. LINC01116 knockdown resulted in a 2.1-fold increase in E-cadherin expression and a 56% reduction in Vimentin expression in A549/DDP cells, and LINC01116 overexpression resulted in a 45% reduction in E-cadherin expression and a 1.82-fold increase in Vimentin expression in A549 cells.

Conclusion

Dysregulation of lncRNA LINC01116 expression results in resistance of LAD to cisplatin via the EMT process. Our findings support the oncogenic role of LINC01116 to promote the development of cisplatin resistance in LAD, and LINC01116 may be a novel predictor of poor response to cisplatin.

CircRNAs: biogenesis, functions, and role in drug-resistant Tumours

Targeted treatment, which can specifically kill tumour cells without affecting normal cells, is a new approach for tumour therapy. However, tumour cells tend to acquire resistance to targeted drugs during treatment. Circular RNAs (circRNAs) are single-stranded RNA molecules with unique structures and important functions. With the development of RNA sequencing technology, circRNAs have been found to be widespread in tumour-resistant cells and to play important regulatory roles. In this review, we present the latest advances in circRNA research and summarize the various mechanisms underlying their regulation. Moreover, we review the role of circRNAs in the chemotherapeutic resistance of tumours and explore the clinical value of circRNA regulation in treating tumour resistance.

Overexpression of miR-382 Sensitizes Hepatocellular Carcinoma Cells to γδ T Cells by Inhibiting the Expression of c-FLIP

Human γδ T lymphocytes were reported to display anti-tumor effects against multiple cancers, including hepatocellular carcinoma (HCC). Aberrant expression of microRNAs (miRNAs) leads to a low response to immunotherapy. Thirty-five HCC tumor tissues and their adjacent healthy tissues were collected from patients with primary HCC who underwent tumor resection in the Third People’s Hospital of Hainan Province, China. The purity of the resulting γδ T cells was identified by anti-γδ-T cell receptor-phycoerythrin (anti-γδ-TCR-PE) and anti-CD3-fluorescein isothiocyanate (anti-CD3-FITC) antibodies on flow cytometry. Human HCC cell lines HepG2 and PLC were cultured. We observed that ex vivo, expanded human γδ T cells were able to induce cell lysis of HCC. Furthermore, as miR-382 was observed to be downregulated in HCC tissues and cell lines, we found that overexpression of miR-382 increased the sensitivity of HCC cells to γδ T cells. We proved that mRNA of cellular FADD-like interleukin-1β-converting enzyme-inhibitory protein (c-FLIP) was the target of miR-382. Inhibition of c-FLIP by miR-382 significantly promotes the cell lysis of HCC through strengthening the activation caspase 8 induced by γδ T cell treatment. In conclusion, overexpression of miR-382 promotes HCC cell lysis induced by γδ T cells through inhibiting the expression of c-FLIP.

Long Non-Coding RNAs in Drug Resistance of Breast Cancer

Breast cancer (BC) is the most common cancer and the leading cause of death in women. Advances in early diagnosis and therapeutic strategies have decreased the mortality of BC and improved the prognosis of patients to some extent. However, the development of drug resistance has limited the success rate of systemic therapies. Long non-coding RNAs (lncRNAs) are involved in drug resistance in BC via various mechanisms, which contribute to a complex regulatory network. In this review, we summarize the latest findings on the mechanisms underlying drug resistance modulated by lncRNAs in BC. In addition, we discuss the potential clinical applications of lncRNAs as targeted molecular therapy against drug resistance in BC.

Non-coding RNAs in drug resistance of head and neck cancers: A review

Head and neck cancer (HNC), which includes epithelial malignancies of the upper aerodigestive tract (oral cavity, oropharynx, pharynx, hypopharynx, larynx, and thyroid), are slowly but consistently increasing, while the overall survival rate remains unsatisfactory. Because of the multifunctional anatomical intricacies of the head and neck, disease progression and therapy-related side effects often severely affect the patient's appearance and self-image, as well as their ability to breathe, speak, and swallow. Patients with HNC require a multidisciplinary approach involving surgery, radiation therapy, and chemotherapeutics. Chemotherapy is an important part of the comprehensive treatment of tumors, especially advanced HNC, but drug resistance is the main cause of poor clinical efficacy. The most important determinant of this phenomenon is still largely unknown. Recent studies have shown that non-coding RNAs have a crucial role in HNC drug resistance. In addition, they can serve as biomarkers in the diagnosis, treatment, and prognosis of HNCs. In this review, we summarize the relationship between non-coding RNAs and drug resistance of HNC, and discuss their potential clinical application in overcoming HNC chemoresistance.

miR-548e Sponged by ZFAS1 Regulates Metastasis and Cisplatin Resistance of OC by Targeting CXCR4 and let-7a/BCL-XL/S Signaling Axis

Ovarian cancer (OC) is a severe malignancy featuring a poor prognosis due to rapid metastasis and chemotherapy resistance. In this study, we extensively investigated the upstream and downstream mechanisms of miR-548e in regulating OC progression and cisplatin resistance. Our results indicated that ZFAS1 was highly expressed and promoted OC cell proliferation, migration, invasion, and cisplatin resistance by directly suppressing miR-548e expression. ZFAS1 co-localized with miR-548e in the cytosols of OC cells. miR-548e repressed CXCR4 expression, and elevated CXCR4 expression promoted OC cell proliferation, migration, invasion, and cisplatin resistance. Cisplatin resistance induced by ZFAS1 and CXCR4 overexpression in OC cells was mediated by their suppression on let-7a and elevation of BCL-XL/S expression. ZFAS1 knockdown and miR-548e and let-7a overexpression impaired cisplatin resistance and suppressed lung metastatic nodule formation in nude mice. In conclusion, ZFAS1 binds with miR-548e to enhance CXCR4 expression to promote OC cell proliferation and metastasis, which also enhances cisplatin resistance by suppressing let-7a and elevating BCL-XL/S protein expression.

miR-27a is a master regulator of metabolic reprogramming and chemoresistance in colorectal cancer

BACKGROUND

Metabolic reprogramming towards aerobic glycolysis in cancer supports unrestricted cell proliferation, survival and chemoresistance. The molecular bases of these processes are still undefined. Recent reports suggest crucial roles for microRNAs. Here, we provide new evidence of the implication of miR-27a in modulating colorectal cancer (CRC) metabolism and chemoresistance.

METHODS

A survey of miR-27a expression profile in TCGA-COAD dataset revealed that miR-27a-overexpressing CRCs are enriched in gene signatures of mitochondrial dysfunction, deregulated oxidative phosphorylation, mTOR activation and reduced chemosensitivity. The same pathways were analysed in cell lines in which we modified miR-27a levels. The response to chemotherapy was investigated in an independent cohort and cell lines.

RESULTS

miR-27a upregulation in vitro associated with impaired oxidative phosphorylation, overall mitochondrial activities and slight influence on glycolysis. miR-27a hampered AMPK, enhanced mTOR signalling and acted in concert with oncogenes and tumour cell metabolic regulators to force an aerobic glycolytic metabolism supporting biomass production, unrestricted growth and chemoresistance. This latter association was confirmed in our cohort of patients and cell lines.

CONCLUSIONS

We disclose an unprecedented role for miR-27a as a master regulator of cancer metabolism reprogramming that impinges on CRC response to chemotherapy, underscoring its theragnostic properties.

NCALD affects drug resistance and prognosis by acting as a ceRNA of CX3CL1 in ovarian cancer

Drug resistance, an impenetrable barrier in the treatment of ovarian cancer (OC), is often associated with poor outcomes. Hence, it is urgent to discover new factors controlling drug resistance and survival. The association between neurocalcin delta (NCALD) and cancer drug resistance is poorly understood. Here, we reveal that NCALD messenger RNA expression, probably regulated by DNA methylation and microRNAs, was significantly downregulated in at least three independent microarrays covering 633 ovarian carcinomas and 16 normal controls, which includes the Cancer Genome Atlas (TCGA) ovarian cohort. In the sub-groups of the TCGA cohort, NCALD was suppressed in 90 platinum-resistant tissues vs in 197 sensitive tissues. It is consistent with the quantitative reverse transcription polymerase chain reaction results revealing gene downregulation in carboplatin-resistant SKOV3 and HeyA8 OC cells as compared with that in controls. Low expression of NCALD predicted poor overall survival (OS) in sub-groups of 1656 patients, progression-free survival (PFS) in 1435 patients, and post-progression survival (PPS) in 782 patients according to Kaplan-Meier plotter covering 1815 OC patients. Comprehensive bioinformatic analyses strongly implicated NCALD in the regulation of drug resistance, probably via competing for endogenous RNA (ceRNA) interactions with CX3CL1 and tumor immune-microenvironment. NCALD acted as a ceRNA for CX3CL1 in 21 different cancers includes OC according to Starbase. These two genes negatively correlated with tumor purity and positively correlated with infiltration levels of neutrophils and dendritic cells in OC. The combined low expression of NCALD and CX3CL1 showed better prognosis potential for OS, PFS, and PPS in the 1815 OC patients than any of the individually tested genes. In summary, NCALD acts as a ceRNA for CX3CL1, and its downregulation may affect drug resistance and prognosis in OC. Thus, NCALD could be a new therapeutic target for anticancer therapy and a new biomarker for survival prediction in OC.

Non-coding RNAs in Lung Cancer Chemoresistance

Background:

Lung cancer is the leading cause of cancer-associated death worldwide with limited treatment options. The major available treatment options are surgery, radiotherapy, chemotherapy and combinations of these treatments. In chemotherapy, tyrosine kinase inhibitors and taxol are the first lines of chemotherapeutics used for the treatment of lung cancer. Often drug resistance in the clinical settings hinders the efficiency of the treatment and intrigues the tumor relapse. Drug-resistance is triggered either by intrinsic factors or due to the prolonged cycles of chemotherapy as an acquired-resistance. There is an emerging role of non-coding RNAs (ncRNAs), including notorious microRNAs (miRNAs), proposed to be actively involved in the regulations of various tumor-suppressor genes and oncogenes.

Result:

The altered gene expression by miRNA is largely mediated either by the degradation or by interfering with the translation of targeted mRNA. Unlike miRNA, other type of ncRNAs, such as long non-coding RNAs (lncRNAs), can target the transcriptional activator or the repressor, RNA polymerase, and even DNA-duplex to regulate the gene expressions. Many studies have confirmed the crucial role of ncRNAs in lung adenocarcinoma progression and importantly, in the acquisition of chemoresistance. Recently, ncRNAs have become early biomarkers and therapeutic targets for lung cancer.

Conclusion:

Targeting ncRNAs could be an effective approach for the development of novel therapeutics against lung cancer and to overcome the chemoresistance.

Let-7a Could Serve as A Biomarker for Chemo-Responsiveness to Docetaxel in Gastric Cancer

BACKGROUND

MicroRNAs are noncoding RNAs which play critical roles in response to anti-cancer agents. Let-7a and miR-21 are well-known tumor-suppressor and oncomiR miRNAs, respectively. They are involved in tumorigenesis of gastric cancer and have potential to be used as markers in response to the therapy.

OBJECTIVE

We aimed to study alterations in the expression of Let-7a and miR-21, and their targets in gastric cancer cell lines after treatment with docetaxel.

METHODS

In order to determine the IC50 of docetaxel, MTT assay was performed in AGS, MKN45 and KATO III gastric cancer cell lines. The expression levels of Let-7a and miR-21 and their target genes, HMGA2 and PDCD4, were determined by reverse-transcription quantitative real-time PCR for both treated and untreated cell lines.

RESULTS

MTT assay showed higher IC50 concentration of docetaxel in KATO III in comparison with AGS and MKN45, indicating KATO III`s higher resistance to docetaxel. Following the treatment, the expression level of Let-7a was significantly increased in AGS and MKN45, while decreased in KATO III. Expression level of miR- 21 in the three treated cell lines was increased significantly. Not only Let-7a, but also expression level of HMGA2 and PDCD4 genes showed different patterns in KATO III in comparison with AGS and MKN45.

CONCLUSION

Down-regulation and up-regulation of Let-7a in docetaxel-resistant and sensitive cell lines, respectively indicates its potential usefulness as biomarker for responsiveness of gastric cancer to the therapy with docetaxel and also for predicting patient`s outcome.

MicroRNAs in Tumor Cell Metabolism: Roles and Therapeutic Opportunities

Dysregulated metabolism is a common feature of cancer cells and is considered a hallmark of cancer. Altered tumor-metabolism confers an adaptive advantage to cancer cells to fulfill the high energetic requirements for the maintenance of high proliferation rates, similarly, reprogramming metabolism confers the ability to grow at low oxygen concentrations and to use alternative carbon sources. These phenomena result from the dysregulated expression of diverse genes, including those encoding microRNAs (miRNAs) which are involved in several metabolic and tumorigenic pathways through its post-transcriptional-regulatory activity. Further, the identification of key actionable altered miRNA has allowed to propose novel targeted therapies to modulated tumor-metabolism. In this review, we discussed the different roles of miRNAs in cancer cell metabolism and novel miRNA-based strategies designed to target the metabolic machinery in human cancer.

LncRNA KCNQ1OT1 contributes to the progression and chemoresistance in acute myeloid leukemia by modulating Tspan3 through suppressing miR-193a-3p

AIMS

Acute myeloid leukemia (AML) is an aggressive cancer that invariably produces drug resistance after treatment. The aim is to explore the role of lncRNA potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 (KCNQ1OT1) and associated novel mechanisms in the progression and chemoresistance of AML.

MAIN METHODS

The expression of KCNQ1OT1, miR-193a-3p, and Tspan3 was measured by qRT-PCR. The values of IC50 for adriamycin (ADR) and the ability of proliferation were analyzed by CCK-8 assay. Cell migration and invasion were assessed by transwell assay. Cell apoptosis was monitored by flow cytometry assay. The expression of Tspan3, MRP1, P-gp and LRP at the protein level was quantified by western blot. The relationship between miR-193a-3p and KCNQ1OT1 or Tspan3 was predicted by bioinformatics tool Diana and verified by dual-luciferase reporter assay, RIP assay or RNA pull-down assay.

KEY FINDINGS

KCNQ1OT1 and Tspan3 were up-regulated, while miR-193a-3p was down-regulated in ADR resistant AML samples and cells. KCNQ1OT1 knockdown reduced ADR resistance, inhibited proliferation, migration and invasion but promoted apoptosis of ADR resistant AML cells, miR-193a-3p inhibition reversed these effects. MiR-193a-3p was a target of KCNQ1OT1 and combined with Tspan3 3' untranslated region (3' UTR). Enrichment of miR-193a-3p decreased ADR resistance, inhibited proliferation, migration and invasion and stimulated apoptosis in ADR resistant AML cells, but Tspan3 overexpression overturned these impacts.

SIGNIFICANCE

KCNQ1OT1 aggravates AML progression and chemoresistance to ADR by inducing Tspan3 expression via adsorbing miR-193a-3p in ADR resistant AML cells, providing a theoretical basis for the treatment of AML with chemoresistance.

The Roles of Hypoxia-Inducible Factors and Non-Coding RNAs in Gastrointestinal Cancer

Hypoxia-inducible factors (HIFs) are transcription factors that play central roles in cellular responses against hypoxia. In most cancers, HIFs are closely associated with tumorigenesis by regulating cell survival, angiogenesis, metastasis, and adaptation to the hypoxic tumor microenvironment. Recently, non-coding RNAs (ncRNAs) have been reported to play critical roles in the hypoxic response in various cancers. Here, we review the roles of hypoxia-response ncRNAs in gastrointestinal cancer, with a particular focus on microRNAs and long ncRNAs, and discuss the functional relationships and regulatory mechanisms between HIFs and ncRNAs.

microRNA-1914, which is regulated by lncRNA DUXAP10, inhibits cell proliferation by targeting the GPR39-mediated PI3K/AKT/mTOR pathway in HCC

Increasing studies have confirmed that abnormally expressed microRNAs (miRNAs) take part in the carcinogenesis as well as the aggravation of hepatocellular carcinoma (HCC). However, little information is currently available about miR-1914 in HCC. Here, we first confirmed that miR-1914 inhibition in HCC cell lines and tumour specimens correlates with tumour size and histological grade. In a series of functional experiments, miR-1914 inhibited tumour proliferation and colony formation, resulting in cell cycle arrest and increased apoptosis. Moreover, miR-1914 mediated its functional effects by directly targeting GPR39 in HCC cells, leading to PI3K/AKT/mTOR repression. Restoring GPR39 expression incompletely counteracted the physiological roles of miR-1914 in HCC cells. In addition, down-regulation of AKT phosphorylation inhibited the effects of miR-1914 in HCC. Furthermore, the overexpression of lncRNA DUXAP10 negatively correlated with the expression of miR-1914 in HCC; thus, lncRNA DUXAP10 regulated miR-1914 expression and modulated the GPR39/PI3K/AKT-mediated cellular behaviours. In summary, the present study demonstrated for the first time that lncRNA DUXAP10-regulated miR-1914 plays a functional role in inhibiting HCC progression by targeting GPR39-mediated PI3K/AKT/mTOR pathway, and this miRNA represents a novel therapeutic target for patients with HCC.

Overexpression of miR-106a enhances oxaliplatin sensitivity of colorectal cancer through regulation of FOXQ1

Chemotherapy resistance poses a major challenge for the clinical treatment of colorectal cancer, therefore, the aim of the present study was to examine its underlying mechanisms. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to determine the microRNA (miRNA)/mRNA and protein expression levels, respectively. A dual luciferase assay was conducted for verification of the interaction between miR-106a and 3′untranslated region (UTR) of Forkhead box Q1 (FOXQ1). Cell viability was assessed using an MTT assay. In the present study, it was demonstrated that miR-106a is involved in regulating oxaliplatin sensitivity of colorectal cancer. Transfection of miR-106a mimics slightly inhibited colorectal cancer cell growth and sensitized colorectal cancer cells to oxaliplatin exposure. In addition, miR-106a overexpression induced a decrease of FOXQ1 at mRNA and protein levels in colorectal cancer cells. The enhanced expression of miR-106a also increased the expression of Wnt target genes, including vascular endothelial growth factor-A and matrix metallopeptidase 2, which were reported to be regulated by FOXQ1. It was predicted and validated that miR-106a could repress FOXQ1 expression via direct binding to 3′UTR. Elevation of miR-106a and a decrease of FOXQ1 expression levels were detected in tumor tissues from patients with oxaliplatin-sensitive colorectal cancer, compared with patients with oxaliplatin-resistant colorectal cancer. Furthermore, there was a significant association between miR-106a and FOXQ1 mRNA levels. In conclusion, the present study demonstrated that miR-106a increased oxaliplatin sensitivity of colorectal cancer cells through direct repression of FOXQ1 expression.

LINC01234/MicroRNA-31-5p/MAGEA3 Axis Mediates the Proliferation and Chemoresistance of Hepatocellular Carcinoma Cells

Hepatocellular carcinoma (HCC) is a prevalent malignancy characterized by aggressiveness and poor prognosis; however, the molecular mechanism remains to be fully identified. Based on the analysis of The Cancer Genome Atlas (TCGA) database, melanoma-associated antigen A3 (MAGEA3) and long non-coding RNA (lncRNA) LINC01234 were upregulated in HCC and associated with poor prognosis of HCC. We investigated the mechanism of how MAGEA3 and LINC01234 influenced HCC cellular functions and cisplatin resistance. MAGEA3 depletion inhibited proliferation, invasion, and cisplatin resistance of HepG2 cells and Huh7 cells in vitro, reduced resistance-associated protein 2 (MRP2), MRP3, and multidrug resistance protein 1 (MDR-1) expression, and elevated ALB expression. RNA pull-down and RIP assays identified the binding of LINC01234 and MAGEA3 to microRNA-31-5p (miR-31-5p). LINC01234 could restore MAGEA3 expression by binding to miR-31-5p. Furthermore, we delivered plasmids into HepG2 cells and Huh7 cells to alter the expression of LINC01234 and miR-31-5p. When miR-31-5p was downregulated, the proliferation and invasion of HepG2 cells and Huh7 cells were enhanced and the cisplatin-induced apoptosis was inhibited, while LINC01234 knockdown could diminish the effects caused by miR-31-5p depletion. In summary, these data highlight the vital role of MAGEA3/LINC01234/miR-31-5p axis in the HCC progression and chemoresistance of HCC cells.

LncRNA BANCR promotes tumorigenesis and enhances adriamycin resistance in colorectal cancer

Colorectal cancer (CRC) is the third most common malignancy in the United States. Chemotherapeutic resistance is a massive obstacle for cancer treatment. The roles and molecular basis of long non-coding RNA BRAF-activated noncoding RNA (BANCR) in CRC progression and adriamycin (ADR) resistance have not been extensively identified. In this study, we found that BANCR and CSE1L expressions were upregulated in CRC tumor tissues. Meanwhile, CSE1L expression was correlated with depth of CRC. BANCR silencing suppressed cell proliferation and invasion capacity, increased apoptotic rate and potentiated cell sensitivity to ADR. CSE1L downregulation triggered a reduction of cell proliferation and invasion ability, and an increase of apoptosis rate and cell sensitivity to ADR. CSE1L overexpression attenuated si-BANCR-mediated anti-proliferation, anti-invasion and pro-apoptosis effects in CRC cells. BANCR acted as a molecular sponge of miR-203 to sequester miR-203 away from CSE1L in CRC cells, resulting in the upregulation of CSE1L expression. CSE1L knockdown inhibited expressions of DNA-repair-related proteins (53BP1 and FEN1) in HCT116 cells. BANCR knockdown also inhibited tumor growth and enhanced ADR sensitivity in CRC mice model. In conclusion, BANCR knockdown suppressed CRC progression and strengthened chemosensitization of CRC cells to ADR possibly by regulating miR-203/CSE1L axis, indicating that BANCR might be a promising target for CRC treatment.

Role of a novel circulatory RNA-based biomarker panel expression in ovarian cancer

Ovarian cancer (OC) is considered the sixth commonest cancer affecting women globally. We choose novel integrated specific ovarian cancer RNA biomarker panel; pellino E3 ubiquitin protein ligase family member 3 (PELI3) gene expressions along with its selected epigenetic regulators (microRNA (miR-361-3p) and long noncoding RNA (lncRNA RP5-837J1.2) by bioinformatic methods. Then, differential expressions of the selected panel in the sera of 50 OC patients, 42 cases with benign ovarian lesions, and among 45 controls were determined using real-time polymerase chain reaction quantitative (qRT-PCR). Furthermore, their expression was measured also in malignant ovarian tissues and adjacent nontumor tissues in 23 of 50 OC patients by quantitative qRT-PCR. The current study reported, for the first time, upregulation of serum lncRNA RP5-837J1.2 with concomitant downregulation of miR-361-3p and PELI3 mRNA in malignant group compared with benign and controls groups. There were associations of serum lncRNA RP5-837J1.2 with the affected ovary and worse International Federation of Gynecology and Obstetrics staging; associations of miR-361-3p with tumor size, grade, stage, and presence of metastasis; as well as associations among PELI3 mRNA expression and tumor size, grade, stage, and presence of metastasis among the OC group. In tumor tissues, miR-361-3p and PELI3 mRNA levels were at a higher level than that of nontumor tissues; however, tumor tissue showed lower level of lncRNA RP5-837J1.2 compared to normal tissue. There were positive correlations between serum and tissue level of RNA RP5-837J1.2, miR-361-3p, and PELI3 mRNA, but they did not reach statistical significance. Receiver operating characteristics curve analyses showed that lncRNA RP5-837J1.2, miR-361-3p, and PELI3 mRNA expression levels can discriminate among OC patient, cases with benign mass, and controls with an accuracy of 96, 76, and 83%, respectively; which increased if they are combined. This novel diagnostic RNA-based panel biomarker could be helpful for OC diagnosis.

Quantifying Risk Pathway Crosstalk Mediated by miRNA to Screen Precision drugs for Breast Cancer Patients

Breast cancer has become the most common cancer that leads to women's death. Breast cancer is a complex, highly heterogeneous disease classified into various subtypes based on histological features, which determines the therapeutic options. System identification of effective drugs for each subtype remains challenging. In this work, we present a computational network biology approach to screen precision drugs for different breast cancer subtypes by considering the impact intensity of candidate drugs on the pathway crosstalk mediated by miRNAs. Firstly, we constructed and analyzed the subtype-specific risk pathway crosstalk networks mediated by miRNAs. Then, we evaluated 36 Food and Drug Administration (FDA)-approved anticancer drugs by quantifying their effects on these subtype-specific pathway crosstalk networks and combining with survival analysis. Finally, some first-line treatments of breast cancer, such as Paclitaxel and Vincristine, were optimized for each subtype. In particular, we performed precision screening of subtype-specific therapeutic drugs and also confirmed some novel drugs suitable for breast cancer treatment. For example, Sorafenib was applicable for the basal subtype treatment, Irinotecan was optimum for Her2 subtype treatment, Vemurafenib was suitable for the LumA subtype treatment, and Vorinostat could apply to LumB subtype treatment. In addition, the mechanism of these optimal therapeutic drugs in each subtype of breast cancer was further dissected. In summary, our study offers an effective way to screen precision drugs for various breast cancer subtype treatments. We also dissected the mechanism of optimal therapeutic drugs, which may provide novel insight into the precise treatment of cancer and promote researches on the mechanisms of action of drugs.

Circular RNAs in drug resistant tumors

Chemotherapy is an effective method to treat patients with advanced malignant tumors. However, tumor cells can develop resistance to multiple drugs during the therapy process, leading to treatment failure. Circular RNAs (circRNAs) are a new class of regulatory RNAs that can regulate endogenous gene expression. Previous studies revealed the diagnostic and prognostic value of circRNAs in malignant cancer and other diseases, but few reports have examined their association with clinical drug resistance. In this review, we summarize the up-to-date information regarding the role of circRNAs in the resistance of tumors to chemotherapy and discuss specific regulatory mechanisms. This analysis is expected to provide direction for the prevention and management of drug resistance in tumors.