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

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.

TIMP-3 as a therapeutic target for cancer

Tissue inhibitor of metalloproteinase-3 (TIMP-3), a secreted glycoprotein, plays an important role in carcinogenesis. It can bind to many proteinases to suppress their activity and thus protect the extracellular matrix from degradation. TIMP-3 may have many anticancer properties, including apoptosis induction and antiproliferative, antiangiogenic, and antimetastatic activities. This review summarizes the structure, proteinase inhibition ability, genetic and epigenetic regulation, cancer therapy potential, and contribution to cancer development of TIMP-3. Furthermore, in this review we discuss its potential as a biomarker for predicting cancer progression and the current state of drugs that target TIMP-3, either alone or in combination with clinical treatment. In conclusion, TIMP-3 can be a biomarker of cancer and a potential target for cancer therapy. This review article can serve as a basis to understand how to modulate TIMP-3 levels as a drug target of cancers.

LncRNA H19 promotes lung cancer proliferation and metastasis by inhibiting miR-200a function

Lung cancer is the major cause leading to cancer mortality, and the 5-year survival rate for patients with lung cancer still remains low. It is urgent to fully understand the development and progression of lung cancer to discover new therapeutic targets and develop new therapeutic approaches. H19 was documented to be upregulated in lung cancer and related to cell proliferation. However, it is still unclear if H19 has other functions in lung cancer. The mRNA levels of genes were detected by qRT-PCR, and the cell proliferation rate and cell viability were measured through cell count assay and MTT assay. Transwell assays were applied to detect cell abilities to migration and invasion, while luciferase reporter assay and RNA pull-down assay were used to examine interaction between H19 and miR-200a. H19 expression was elevated in the lung cancer tissues and cell lines, while H19 overexpression promoted the lung cancer cell growth, cell migration and invasion, as well as the epithelial mesenchymal transition (EMT). Meantime, RNA pull-down assay showed that H19 interacted with miR-200a, and miR-200a inhibited the activity of H19-fused luciferase. Furthermore, H19 overexpression inhibited miR-200a function and thereby upregulated miR-200a target genes, ZEB1 and ZEB2.H19 sponged and inhibited miR-200a to de-repress expression of ZEB1 and ZEB2, and thereby enhanced lung cancer proliferation and metastasis.

A bibliometric analysis of long non-coding RNA and chemotherapeutic resistance research

The global outputs of annual publication in long non-coding RNAs (lncRNAs) and chemotherapeutic resistance research exponentially increased from 2 in 2008 to 176 in 2017. Using Java application CiteSpace V and VOSviewer, this study assessed the publication model of lncRNAs and chemoresistance by bibliometric analysis. Totally, 2883 authors contributed 528 publications of lncRNAs and chemoresistance in 215 academic journals in the recent decade (2008-2018). Oncotarget in the 215 academic journals published the highest number of publications (60). China had the highest number of publication outputs (358). The leading institute was Nanjing Medical University. Wang Y was the most influential author (13 counts). Gupta RA had the most cited documents (87 counts). “Gene expression” and “poor prognosis” were identified as the hotspots. “Cancer stem cell”, “HOTAIR” and “UCA1” were the frontiers of the fields in recent years. The increase of publications on lncRNAs and chemotherapeutic resistance will continue in the next years. HOTAIR and UCA1 with multiple roles in drug resistance may offer big opportunities for targeted chemoresistance in cancer therapy. These results may help us discover and explain the possible underlying laws of the subject.

Induction/reversal of drug resistance in gastric cancer by non-coding RNAs (Review)

Gastric cancer (GC) is one of the most prevalent and malignant types of cancer worldwide. In China, it is the second most common type of cancer and the malignancy with the highest incidence and mortality rate. Chemotherapy for GC is not always effective due to the development of drug resistance. Drug resistance, which is frequently observed in GC, undermines the success rate of chemotherapy and the survival of patients with GC. The dysregulation of non‑coding RNAs (ncRNAs), primarily microRNAs (miRNAs or miRs) and long non‑coding RNAs (lncRNAs), is involved in the development of GC drug resistance via numerous mechanisms. These mechanisms contribute to the involvement of a large and complex network of ncRNAs in drug resistance. In this review, we focus on and summarize the latest research on the specific mechanisms of action of miRNAs and lncRNAs that modulate drug resistance in GC. In addition, we discuss future prospects and clinical applications of ncRNAs as potential targeted therapies against the chemoresistance of GC.

Retracted Article: Long non-coding RNA GACAT1 alleviates doxorubicin and vincristine resistance through a PTEN/AKT/mTOR/S6K1 regulatory pathway in gastric cancer

Gastric cancer (GC) is a major global health problem. Chemotherapy is a common therapeutic strategy for cancers including GC. However, chemoresistance strikingly limits the clinical applications of chemotherapeutic drugs. Long non-coding RNAs (lncRNAs) have been widely reported to be implicated in the pathogenesis and chemoresistance of cancers including GC. Our work aims to investigate the roles and molecular mechanisms of lncRNA gastric cancer-associated transcript 1 (GACAT1) in regulating doxorubicin (ADR) and vincristine (VCR) resistance in GC. In this text, RT-qPCR assay showed that GACAT1 expression was markedly reduced in ADR- or VCR-resistant GC (SGC7901/ADR or SGC7901/VCR) cells and GC tissues. CCK-8 assay and flow cytometry analysis revealed that GACAT1 overexpression alleviated the resistance of GC cells to ADR and VCR. RT-qPCR and western blot assay disclosed that GACAT1 deactivated the AKT/mTOR/S6K1 signaling pathway and promoted PTEN expression in SGC7901/ADR or SGC7901/VCR cells. Restoration experiments demonstrated that GACAT1 attenuated ADR or VCR resistance by regulating the PTEN/AKT/mTOR/S6K1 pathway in SGC7901/ADR or SGC7901/VCR cells. In vivo experiments demonstrated that GACAT1 overexpression inhibited tumor growth and enhanced ADR- or VCR-mediated anti-tumor effects in GC xenograft tumor models. Taken together, these data revealed that GACAT1 weakened the resistance of GC cells to ADR and VCR by the PTEN/AKT/mTOR/S6K1 regulatory pathway in vitro and in vivo, shedding new light on GACAT1 upregulation as a potential strategy to alleviate chemoresistance in GC.

Potential tumor‑suppressive role of microRNA‑99a‑3p in sunitinib‑resistant renal cell carcinoma cells through the regulation of RRM2

Sunitinib is the most common primary molecular‑targeted agent for metastatic clear cell renal cell carcinoma (ccRCC); however, intrinsic or acquired sunitinib resistance has become a significant problem in medical practice. The present study focused on microRNA (miR)‑99a‑3p, which was significantly downregulated in clinical sunitinib‑resistant ccRCC tissues in previous screening analyses, and investigated the molecular network associated with it. The expression levels of miR‑99a‑3p and its candidate target genes were evaluated in RCC cells, including previously established sunitinib‑resistant 786‑o (SU‑R‑786‑o) cells, and clinical ccRCC tissues, using reverse transcription‑quantitative polymerase chain reaction. Gain‑of‑function studies demonstrated that miR‑99a‑3p significantly suppressed cell proliferation and colony formation in RCC cells, including the SU‑R‑786‑o cells, by inducing apoptosis. Based on in silico analyses and RNA sequencing data, followed by luciferase reporter assays, ribonucleotide reductase regulatory subunit‑M2 (RRM2) was identified as a direct target of miR‑99a‑3p in the SU‑R‑786‑o cells. Loss‑of‑function studies using small interfering RNA against RRM2 revealed that cell proliferation and colony growth were significantly inhibited via induction of apoptosis, particularly in the SU‑R‑786‑o cells. Furthermore, the RRM2 inhibitor Didox (3,4‑dihydroxybenzohydroxamic acid) exhibited anticancer effects in the SU‑R‑786‑o cells and other RCC cells. To the best of our knowledge, this is the first report demonstrating that miR‑99a‑3p directly regulates RRM2. Identifying novel genes targeted by tumor‑suppressive miR‑99a‑3p in sunitinib‑resistant RCC cells may improve our understanding of intrinsic or acquired resistance and facilitate the development of novel therapeutic strategies.

MALAT1 knockdown inhibits proliferation and enhances cytarabine chemosensitivity by upregulating miR-96 in acute myeloid leukemia cells

Drug resistance remains a major cause of relapse and therapeutic failure in acute myeloid leukemia (AML). Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been documented to act as an oncogene and is frequently highly expressed in human cancers including AML. However, the function and molecular mechanism of MALAT1 in regulating cytarabine (Ara-C) resistance of AML are largely unknown. The expressions of MALAT1 and miR-96 in AML patients and healthy controls were examined by qRT-PCR. CCK-8 and flow cytometry assay were performed to assess the proliferation and apoptosis of AML cells. The interaction between MALAT1 and miR-96 was investigated by luciferase reporter assay. We found that MALAT1 was upregulated while miR-96 was downregulated in AML patients compared with healthy controls. A negative correlation between MALAT1 and miR-96 expressions was observed in AML patients. Knockdown of MALAT1 inhibited the proliferation, induced apoptosis, and enhanced Ara-C sensitivity of AML cells. Additionally, MALAT1 suppressed miR-96 expression by acting as a molecular sponge of miR-96 in AML cells. miR-96 downregulation abolished the effects of MALAT1 knockdown on the proliferation, apoptosis, Ara-C sensitivity in AML cells. In conclusion, MALAT1 knockdown inhibited proliferation, promoted apoptosis and enhanced Ara-C sensitivity in AML cells by upregulating miR-96, providing novel insights into the critical role of MALAT1 as a miRNA sponge in AML.

MicroRNA Regulation of Energy Metabolism to Induce Chemoresistance in Cancers

Since “Warburg effect” has been firstly uncovered in cancer cells in 1956, mounting evidence has supported the molecular mechanism underlying the energy metabolism in induced chemoresistance in cancers. MicroRNAs can mediate fine-tuning of genes in physiological process. MicroRNAs’ energy metabolic role in chemoresistance has been probed recently. In this review, we summarize 5 microRNAs in regulating glucose and lipid metabolism and other energy metabolism. They partially modulate chemoresistance to cancer treatments. Furthermore, we discuss the great therapeutic potential of metabolism-related microRNAs in novel combinatorial means to treat human cancers.

TUG1 knockdown enhances adriamycin cytotoxicity by inhibiting glycolysis in adriamycin-resistant acute myeloid leukemia HL60/ADR cells

Taurine-upregulated gene 1 (TUG1) has been reported as an oncogenic long non-coding RNA (lncRNA) in acute myeloid leukemia (AML). Nevertheless, the roles and molecular mechanism of TUG1 in drug resistance of AML cells are still unclear. Glycolysis level was evaluated by detecting glucose consumption and lactate production. qRT-PCR and Western blot were performed to detect TUG1, hexokinase2 (HK2) and pyruvate kinase isoenzyme M2 (PKM2) expressions. Adriamycin (ADR) cytotoxicity and apoptosis were assessed by MTT assay and flow cytometry, respectively. The changes of the protein kinase B (Akt) pathway were determined by Western blot analysis of phosphorylated-Akt (p-Akt) (ser473) and Akt. Our results showed that glycolysis was increased in HL60/ADR cells, as evidenced by the elevated glucose consumption and lactate production, as well as the increased HK2 and PKM2 expressions at mRNA and protein levels. TUG1 was up-regulated in HL60/ADR cells and TUG knockdown inhibited glycolysis. TUG1 knockdown enhanced ADR-induced cytotoxicity and apoptosis in HL60/ADR cells. TUG1 knockdown inhibited the Akt pathway and activation of the Akt pathway by 740Y-P attenuated the effects of TUG1 knockdown on ADR-induced cytotoxicity and apoptosis, as well as glycolysis in HL60/ADR cells. Taken together, TUG1 knockdown enhances adriamycin cytotoxicity in HL60/ADR cells via inhibiting the glycolysis by inactivating the Akt pathway.

Taurine-upregulated gene 1 (TUG1) has been reported as an oncogenic long non-coding RNA (lncRNA) in acute myeloid leukemia (AML).

MicroRNA‑29a enhances cisplatin sensitivity in non‑small cell lung cancer through the regulation of REV3L

Cisplatin-based chemotherapy may greatly enhance patient prognosis; however, chemotherapy resistance remains an obstacle to curing patients with non-small cell lung cancer (NSCLC). The aim of the present study was to explore the microRNAs (miRs) that could regulate cisplatin sensitivity and provide a potential treatment method for cisplatin resistance in clinical. Results from the present study revealed that miR-29a overexpression enhanced and miR-29a inhibition reduced the sensitivity of two NSCLC cell lines, A549 and H1650, to cisplatin treatment. In addition, reduced miR-29a expression levels were observed in cisplatin-resistant A549 cells (A549rCDDP), and increased expression of miR-29a augmented cisplatin-induced inhibition of proliferation and apoptosis in A549rCDDP cells. These data indicated that miR-29a expression may be involved in the development of cisplatin resistance. miR-29a was revealed to negatively regulate REV3-like DNA-directed polymerase ζ catalytic subunit (REV3L) expression in both A549 and H1650 cells; elevated expression of REV3L in A549rCDDP cells was also detected. REV3L encodes the catalytic subunit of DNA polymerase ζ and was hypothesized, based on results from the online tool TargetScan 7.1, to be a target gene of miR-29a; this was confirmed with a dual luciferase assay. Cells treated with a very low concentration of cisplatin exhibited a significant reduction in proliferation and cell cycle arrest at the G2/M phase in REV3L-knockdown as well as in miR-29a-upregulated A549 cells. Notably, reduced miR-29a expression and an increase in REV3L mRNA expression were observed in tumor tissues from patients with NSCLC. Additionally, a negative correlation between miR-29a and REV3L mRNA expression levels in tumor tissues from patients with NSCLC was observed; low expression of miR-29a and high expression of REV3L were closely associated with an advanced tumor-node-metastasis classification. The results of the present study suggested a pivotal role of miR-29a in mediating NSCLC cell sensitivity towards cisplatin through the regulation of REV3L.

LncRNA MALAT1 potentiates autophagy‑associated cisplatin resistance by regulating the microRNA‑30b/autophagy‑related gene 5 axis in gastric cancer

Gastric cancer (GC) is the fourth most common type of cancer worldwide and chemoresistance is a major obstacle to successful GC treatment. In the present study, reverse transcription‑quantitative polymerase chain reaction analysis was used to measure the expression of metastasis‑associated lung adenocarcinoma transcript 1 (MALAT1) and microRNA (miR)‑30b. Western blot analysis was conducted to detect the protein expression of autophagy‑related gene 5 (ATG5), p62 and LC3 (LC3‑I and LC3‑II). Cell viability and half maximal inhibitory concentration were determined by the Cell Counting Kit‑8 assay. The green fluorescent protein (GFP)‑LC3‑positive cell percentage was determined by the GFP‑LC3 puncta experiment. Luciferase reporter and RNA immunoprecipitation assays were used to explore the molecular associations among MALAT1, miR‑30b and ATG5. MALAT1 was found to be highly expressed in CDDP‑resistant AGS(AGS/CDDP) cells and CDDP‑resistant HGC‑27 (HGC‑27/CDDP) cells. Cell viability was markedly increased in MALAT1‑overexpressing AGS/CDDP cells, but was notably reduced in MALAT1‑depleted HGC‑27/CDDP cells. Moreover, MALAT1 potentiated CDDP resistance by facilitating autophagy in AGS/CDDP and HGC‑27/CDDP cells. Further investigations demonstrated that MALAT1 inhibited miR‑30b expression by direct interaction. Moreover, miR‑30b abolished MALAT1‑induced CDDP resistance by inhibiting autophagy in AGS/CDDP and HGC‑27/CDDP cells. Furthermore, ATG5 was found to be a target of miR‑30b. miR‑30b weakened resistance to CDDP by inhibiting autophagy in AGS/CDDP and HGC‑27/CDDP cells, while this effect was abrogated by increased ATG5 expression. Additionally, MALAT1 sequestered miR‑30b from ATG5 to increase ATG5 expression in AGS/CDDP and HGC‑27/CDDP cells. Therefore, MALAT1 potentiated autophagy‑related CDDP resistance through suppressing the miR‑30b/ATG5 axis in AGS/CDDP and HGC‑27/CDDP cells, indicating that it may represent a promising target for the reversal of chemoresistance in GC.

Non-coding RNA in drug resistance of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has been one of the most highly lethal cancers. The acquisition of drug resistance accounts for the majority of poor effects of chemotherapy in HCC. Non-coding RNAs (ncRNAs) including miRNAs, long ncRNAs (lncRNAs), and circular RNA (circRNA) have been well-documented to participate in cancer occurrence and progression. Recently, multiple studies have highlighted the key roles of ncRNAs in chemoresistance of HCC. In addition, accumulating evidence has demonstrated that they can serve as biomarkers in diagnosis, treatment, and prognosis of HCC. In this review, we first overviewed up-to-date findings regarding miRNA and lncRNA in drug resistance of HCC, then summarized specific mechanisms that they modulate chemoresistance of HCC, and finally discussed their potential clinical application in overcoming the obstacle of HCC chemoresistance in the future.

Non-coding RNA influences in dementia

Dementia is a complex clinical syndrome characterised by progressive decline in cognitive function. It usually presents itself as impairment in memory, loss of judgement, abstract thinking and other disturbances that are severe enough to interfere with activities of daily living. It has long been considered as one of the major challenges at present posing an ever-increasing demand on global health and social care systems. Of all the different forms of dementia, Alzheimer's disease (AD) is the most common. The term non-coding RNA (ncRNA) refers to RNA sequences which do not have the ability to be translated into proteins and therefore mainly fall within the realm of the recently acknowledged ‘dark matter’ of the genome. This genomic dark matter encompasses a whole spectrum of differing ncRNA families such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), PIWI-interacting RNAs (piRNAs), transfer RNAs (tRNAs), small nuclear RNAs (snoRNAs) and circular RNAs (circRNAs), to name but a few. Consequently, due to the widespread influences of miRNAs and lncRNAs across all disease pathways, it is of critical importance for researchers in the field of dementia to focus their attention on possible ncRNA-induced pathogeneses, with the ultimate goal of identifying novel diagnostic procedures and drug targets, together with the development of novel therapies to control such a devastating mental condition in the patient population.

The Network of Non-coding RNAs in Cancer Drug Resistance

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

NRAL mediates cisplatin resistance in hepatocellular carcinoma via miR-340-5p/Nrf2 axis

Recent studies have shown that long non-coding RNAs (lncRNAs) play a pivotal role in the pathogenesis and progression of hepatocellular carcinoma (HCC). However, the biological action and potential mechanism of liver cancer cell drug resistance have not been clearly clarified. In this study, lncRNAs were screened and differentially expressed in parental and cisplatin-resistant cell lines (HepG2 and HepG2/CDDP). A novel lncRNA, termed NRAL (Nrf2 regulation-associated lncRNA), was identified, and the initial results indicated that it was highly expressed in HepG2 cisplatin resistant cell lines compared to their parental counterparts. Functionally, NRAL depletion significantly enhanced CDDP-mediated cytotoxicity and apoptosis in two cisplatin-resistant HCC cell lines. Mechanistically, the results indicated that NRAL regulates Nrf2 expression through miR-340-5p serving as a competing endogenous RNA (ceRNA), thus influencing the CDDP-induced phenotype in HCC. Collectively, the present investigation suggest that the NRAL/miR-340-5p/Nrf2 axis mediates cisplatin resistance in HCC, which may provide novel targets for overcoming cisplatin resistance in hepatocellular carcinoma cells.

Screen for MicroRNA and Drug Interactions in Breast Cancer Cell Lines Points to miR-126 as a Modulator of CDK4/6 and PIK3CA Inhibitors

Background: Breast cancer (BC) represents the most common cancer in women worldwide. Due to its heterogeneous nature, breast cancer management might benefit from differential treatments toward personalized medicine. Additionally, drug resistance is a common phenomenon. We systematically investigated the effect of 14 different drugs administered on BC cell lines in combination with microRNAs (miRNA, miR).

Methods: Thirty-eight miRNAs, all associated with BC by clinical and molecular parameters including progression, prognosis and subtypes, were tested for their effects on the viability of 12 different BC cell lines. Four miRNAs with the strongest impact on viability were further assayed in combination with 14 BC drugs. Mann–Whitney U-test with Bonferroni correction was used for statistical analysis.

Results: In a miRNA only pre-screen we observed effects on BC cell lines' viability for 34 out of 38 candidate miRNAs. We then identified 14 miRNA/drug combinations for which the combination IC₅₀ was lower than that of both miRNA and drug as single agents. miR-181a, paired with GSK1070916, Doxorubicin, XL765 and AMG511, was the only miRNA active on the triple negative (TNBC) MDA-MB-468 cell line. miR-126 was the only miRNA (in combination with CDK4/6 or PIK3CA inhibitors) with significant effects on cell lines from different subtypes: MCF7 (Luminal) and MDA-MB-453 (HER2⁺). Because of its activity on different BC subtypes, we investigated the genome wide effects of miR-126 using transcriptomics and confirmed that expression of miR-126 in BC cell lines affected cell cycle and mitosis.

Conclusion: Our results show that a combination treatment with miRNAs, in particular miR-181a, miR-326, miR-9 and miR-126, enhance the activity of specific BC drugs in vitro, even on the most aggressive BC subtypes, HER2+ and TNBC. Finally, as expected from its drug interactions, based on a whole transcriptome study we could confirm a role for miR-126 in cell cycle regulation.

Involvement of non-coding RNAs in chemotherapy resistance of ovarian cancer

Ovarian cancer (OC) is the most lethal gynecological malignancy, with a low 5-year survival rate. Most patients with ovarian cancer are diagnosed in late-stages. A rising number of non-coding RNAs (ncRNAs) have been found to act as key regulators of gene expression by applying novel high-thought methods, such as next generation sequencing (NGS). Non-coding RNAs not only play important roles in carcinogenesis, but also affect the clinical treatment strategies. One of the biggest challenge in OC treatment was chemoresistance, which causes poor prognosis and high recurrence rate after applying traditional remedies. Of note, it has been proved that ncRNAs were deeply correlated with chemoresistance in several cancers, which made ncRNAs considered to be potential therapeutic targets in ovarian cancer. Among of all ncRNAs, the studies of miRNAs and lncRNAs in ovarian cancer chemoresistance were much clearer. In this study, we reviewed the most relevant researches in this field, and described the relationships between ncRNAs and chemoresistance in ovarian cancer.

Knockdown of LncRNA-UCA1 suppresses chemoresistance of pediatric AML by inhibiting glycolysis through the microRNA-125a/hexokinase 2 pathway

Dysregulation of lncRNAs is implicated in chemoresistance in varieties of tumor including acute myeloid leukemia (AML). LncRNA urothelial carcinoma-associated 1 (UCA1) was reported to play an oncogenic role in AML. However, whether UCA1 was involved in chemoresistance in pediatric AML remains unclear. UCA1 expression in AML patients after adriamycin (ADR)-based chemotherapy and ADR-resistant AML cells was examined by qRT-PCR. The effects of UCA1 on the cytotoxicity of ADR and glycolysis were evaluated by MTT assay and measuring the glucose consumption and lactate production in HL60 and HL60/ADR cells, repectively. The protein levels of hypoxia-inducible factor 1α (HIF-1α) and hexokinase 2 (HK2) were determined by Western blot. Luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to confirm the relationships between UCA1, HK2, and miR-125a. We found that UCA1 expression was upregulated following ADR-based chemotherapy. Knockdown of UCA1 increased the cytotoxic effect of ADR and inhibited HIF-1α-dependent glycolysis in ADR-resistant AML cells. Additionally, UCA1 functioned as a ceRNA of miR-125a by directly binding to miR-125a. HK2, a target of miR-125a, was positively regulated by UCA1 in HL60 and HL60/ADR cells. More notably, UCA1 overexpression overturned miR-125-mediated inhibition on HIF-1α-dependent glycolysis in HL60 and HL60/ADR cells. Furthermore, 2-deoxy-glucose (2-DG) exposure inhibited HIF-1α-dependent glycolysis, and attenuated UCA1-induced increase of chemoresistance in HL60 and HL60/ADR cells. We conclude that knockdown of UCA1 plays a positive role in overcoming the chemoresistance of pediatric AML, through suppressing glycolysis by the miR-125a/HK2 pathway, contributing to a better understanding of the molecular mechanism of chemoresistance in AML.

TP53TG1 enhances cisplatin sensitivity of non-small cell lung cancer cells through regulating miR-18a/PTEN axis

Background

The acquisition of drug resistance has been considered as a main obstacle for cancer chemotherapy. Tumor protein 53 target gene 1 (TP53TG1), a p53-induced lncRNA, plays a vital role in the progression of human cancers. However, little is known about the detailed function and molecular mechanism of TP53TG1 in cisplatin resistance of NSCLC.

Methods

qRT-PCR analysis was used to detect the expression of TP53TG1, miR-18a and PTEN mRNA in NSCLC tissues and cells. Western blot analysis was performed to determine the protein level of PTEN and cleaved caspase-3. Cell viability and IC50 value were measured by MTT assay. Cell apoptosis was confirmed by flow cytometry assay. Subcellular fractionation assay was used to identify the subcellular location of TP53TG1. Dual-luciferase reporter assay, RNA pull down assay and RNA immunoprecipitation assay were carried out to verify the interaction between TP53TG1 and miR-18a. Xenografts in nude mice were established to verify the effect of TP53TG1 on cisplatin sensitivity of NSCLC cells in vivo.

Results

TP53TG1 level was downregulated in NSCLC tissues and cell lines. Upregulated TP53TG1 enhanced cisplatin sensitivity and apoptosis of A549/DDP cells, while TP53TG1 depletion inhibited cisplatin sensitivity and apoptosis of A549 cells. TP53TG1 suppressed miR-18a expression in A549 cells. Moreover, TP53TG1-mediated enhancement effect on cisplatin sensitivity was abated following the restoration of miR-18a expression in A549/DDP cells, while si-TP53TG1-induced decrease of cisplatin sensitivity and apoptosis was counteracted by miR-18a inhibitor in A549 cells. Furthermore, TP53TG1 promoted PTEN expression via inhibiting miR-18a. Finally, TP53TG1 sensitized NSCLC cells to cisplatin in vivo.

Conclusion

TP53TG1 increased the sensitivity of NSCLC cells to cisplatin by modulating miR-18a/PTEN axis, elucidating a novel approach to boost the effectiveness of chemotherapy for NSCLC.

Electronic supplementary material

The online version of this article (10.1186/s13578-018-0221-7) contains supplementary material, which is available to authorized users.

SOX9/miR-130a/CTR1 axis modulates DDP-resistance of cervical cancer cell

Cisplatin (DDP) -based chemotherapy is a standard strategy for cervical cancer, while chemoresistance remains a huge challenge. Copper transporter protein 1 (CTR1), a copper influx transporter required for high affinity copper (probably reduced Cu I) transport into the cell, reportedly promotes a significant fraction of DDP internalization in tumor cells. In the present study, we evaluated the function of CTR1 in the cell proliferation of cervical cancer upon DDP treatment. MicroRNAs (miRNAs) have been regarded as essential regulators of cell proliferation, apoptosis, migration, as well as chemoresistance. By using online tools, we screened for candidate miRNAs potentially regulate CTR1, among which miR-130a has been proved to promote cervical cancer cell proliferation through targeting PTEN in our previous study. In the present study, we investigated the role of miR-130a in cervical cancer chemoresistance to DDP, and confirmed the binding of miR-130a to CTR1. SOX9 also reportedly act on cancer chemoresistance. In the present study, we revealed that SOX9 inversely regulated miR-130a through direct targeting the promoter of miR-130a. Consistent with previous studies, SOX9 could affect cervical cancer chemoresistance to DDP. Taken together, we demonstrated a SOX9/miR-130a/CTR1 axis which modulated the chemoresistance of cervical cancer cell to DDP, and provided promising targets for dealing with the chemoresistance of cervical cancer.

MiR-192 and miR-662 enhance chemoresistance and invasiveness of squamous cell lung carcinoma

OBJECTIVES

Overexpression of miR-192, miR-192* and miR-662 was previously found to correlate with poor prognosis of early-stage squamous cell lung cancer (SCC) patients. In this study, we investigated the relevance of these miRNAs to cancer cell biology and chemoresistance.

MATERIALS AND METHODS

MiRNA expression profile was analysed in 10 non-small cell lung cancer (NSCLC) cell lines using RT-qPCR. H520 and H1703 cells were transfected with miRNA inhibitors (anti-miR-192, -192* and -662) for functional studies. Chemoresistance to cisplatin and etoposide was evaluated using MTT colorimetric assay. H520 cells were subjected to 3D soft-agar colony formation assay and H1703 cells to wound healing assay. Whole transcriptome analysis was used to assess the effect of miR-192 and miR-662 inhibition on gene expression.

RESULTS

SCC cell lines, H520 and H1703, differed in miRNA expression and phenotypic features. MiR-192 and miR-662 inhibition decreased clonogenicity and motility of SCC cells. MiR-192 and miR-662 inhibition sensitized SCC cells to etoposide but not to cisplatin. Whole transcriptome analysis revealed genes regulated by miR-192 and miR-662 in SCC, relevant to maintaining chemoresistance, invasiveness, epithelial-mesenchymal transition (EMT) and immune evasion.

CONCLUSIONS

We showed for the first time that miR-192 and miR-662 have functional role in SCC cells. Our findings suggest that targeting these miRNAs may impact both chemoresistance and invasiveness of SCC, and add to the evidence linking these aspects of tumour biology. Overexpression of miR-192 and miR-662 might be useful as a marker of resistance to etoposide.

miR-654-5p Targets GRAP to Promote Proliferation, Metastasis, and Chemoresistance of Oral Squamous Cell Carcinoma Through Ras/MAPK Signaling

Oral squamous cell carcinoma (OSCC) is characterized by rapid local migration and invasion. This study was aimed at clarifying the effect of miR-654-5p on progression of OSCC. miR-654-5p promoted proliferation, metastasis, and chemoresistance of OSCC in vitro and in vivo. Consistently, miR-654-5p was upregulated in late-stage OSCC and was correlated with poor prognosis of OSCC patients. Furthermore, miR-654-5p was mechanistically verified to target Grb-2-related adaptor protein (GRAP), accompanied by the activation of Ras/MAPK signaling and the facilitation of epithelial-mesenchymal transition in OSCC cells. GRAP was downregulated in T1-2 stage versus T3-4 stage head and neck squamous cell carcinoma (HNSC) and was negatively correlated with tumor-node-metastases (TNM) stage in HNSC patients based on The Cancer Genome Atlas (TCGA) analysis. In addition, GRAP was positively correlated with good prognosis in HNSC patients. Our findings suggest that the miR-654-5p/GRAP/Ras/Erk signaling pathway in OSCC cells might contribute to the underlying mechanism through which miR-654-5p participates in the regulation of OSCC progression. miR-654-5p, as a potential biomarker for the clinical diagnosis and prognosis of OSCC, may be an effective anticancer target for the treatment of OSCC.

Retracted Article: Linc00472 suppresses breast cancer progression and enhances doxorubicin sensitivity through regulation of miR-141 and programmed cell death 4

The existence of drug resistance strikingly hampers the therapy of many malignancies, including breast cancer. Long non-coding RNAs (LncRNAs) have been reported to participate in the regulation of various biological processes associated with cancer progression. Whereas, the role of linc00472 in breast cancer pathogenesis and doxorubicin (ADR) resistance have not been well elucidated. In the present study, it is found that linc00472 expression was decreased in breast cancer tissues and cells. Moreover, higher linc00472 expression was positively associated with favorable disease status and prognosis for breast cancer patients. Functional analyses revealed that linc00472 overexpression suppressed proliferation and invasion, facilitated apoptosis and enhanced ADR sensitivity in breast cancer cells. Mechanistic studies discovered that linc00472 acted as a competing endogenous RNA (ceRNA) of miR-141 to sequester miR-141 from its target mRNA PDCD4 (programmed cell death 4). Furthermore, the inhibition effect of linc00472 on breast cancer cell progression and ADR resistance could be partly abrogated by miR-141 up-regulation or PDCD4 knockdown. In vivo assays also demonstrated that linc00472 hindered tumor growth by suppressing miR-141 expression and enhancing PDCD4 expression. In conclusion, linc00472 blocked breast cancer progression and induced ADR sensitivity through regulation of miR-141 and PDCD4, highlighting a potential therapeutic strategy for breast cancer patients.

Linc00472 expression was down-regulated in breast cancer tissues and cells, and was associated with the development and prognosis of breast cancer.

Characterization of etoposide- and cisplatin-chemoresistant retinoblastoma cell lines

Retinoblastoma (RB) is the most common malignant intraocular tumor in early childhood. Imminent chemotherapy resistance diminishes the clinical-therapeutic options and emphasizes the necessity for new therapeutic approaches. The present study aimed at characterizing and comparing etoposide and cisplatin-resistant human RB cell lines with regard to changes in proliferation and apoptosis levels, anchorage independent growth behavior in vitro as well as tumor formation capacity in vivo. The proliferation rates were significantly increased in the etoposide-resistant RB cell lines Y-79, WERI-Rb1 and RB-355 reflecting significantly higher growth kinetics compared to the parental controls. In line with these findings in in vivo chicken chorioallantoic (CAM) assays, etoposide-resistant cell lines generated significantly increased numbers of tumors with higher tumor weights compared to their parental counterparts. In contrast to etoposide, the cisplatin-resistant RB cell lines Y-79, WERI-Rb1 and RB-355 displayed significantly increased apoptosis rates and reduced proliferation rates resulting in significantly decreased growth kinetics. Tumor formation capacity of cisplatin-resistant cell lines did not significantly change, and in comparison with parental controls cisplatin-resistant Y-79 cells displayed significantly reduced tumor weight. Soft agarose assays indicated that anchorage-independent growth of all chemotherapy-resistant cell lines analyzed was significantly decreased. Summarizing, one can state that etoposide-resistant RB cells behave more aggressively than the tumor cells of origin and potentially represent a risk factor for local relapse, while cisplatin-resistant cells show a significantly decreased tumorigenic potential.

Lysosome-associated membrane protein 2 (LAMP-2) expression induced by miR-194-5p downregulation contributes to sunitinib resistance in human renal cell carcinoma cells

Sunitinib is a tyrosine kinase inhibitor that is used as the primary treatment in metastatic renal cell carcinoma (RCC). The main difficulty associated with its use is the development of drug resistance. In the present study, ACHN cells, a human renal cell carcinoma cell line, were used to establish sunitinib-resistant (SR) cells. Microarray analysis and reverse transcription-quantitative polymerase chain reaction revealed that miR-194-5p expression was significantly decreased in SR-ACHN cells when compared with that observed in ACHN cells (P<0.05). Transfection of miR-194-5p, though not with negative control miR, in SR-ACHN cells could significantly inhibit cell proliferation following sunitinib treatment (2.5–40 µM; P<0.05). Western blotting demonstrated that the expression of lysosome-associated membrane protein-2 (LAMP-2), which attenuates the anti-proliferative effect of sunitinib, was significantly higher in SR-ACHN than in ACHN cells (P<0.01). In addition, LAMP-2 expression was suppressed by miR-194-5p transfection in SR-ACHN cells. These data suggested that miR-194-5p downregulation may be associated with sunitinib resistance via the induction of LAMP-2 expression in human RCC.

LncRNA UCA1 promotes proliferation and cisplatin resistance of oral squamous cell carcinoma by sunppressing miR-184 expression

Chemotherapy resistance has become the main obstacle for the effective treatment of human cancers. Long non‐coding RNA urothelial cancer associated 1 (UCA1) is generally regarded as an oncogene in some cancers. However, the function and molecular mechanism of UCA1 implicated in cisplatin (CDDP) chemoresistance of oral squamous cell carcinoma (OSCC) is still not fully established. UCA1 expression in tumor tissues and cells was tested by qRT‐PCR. MTT, flow cytometry and caspase‐3 activity analysis were explored to evaluate the CDDP sensitivity in OSCC cells. Western blot analysis was used to measure BCL2, Bax and SF1 protein expression. Luciferase reporter assay was conducted to investigate the molecular relationship between UCA1, miR‐184, and SF1. Nude mice model was used to confirm the functional role of UCA1 in CDDP resistance in vivo. UCA1 expression was upregulated in OSCC tissues, cell lines, and CDDP resistant OSCC cells. Function analysis revealed that UCA1 facilitated proliferation, enhanced CDDP chemoresistance, and suppressed apoptosis in OSCC cells. Mechanisms investigation indicated that UCA1 could interact with miR‐184 to repress its expression. Rescue experiments suggested that downregulation of miR‐184 partly reversed the tumor suppression effect and CDDP chemosensitivity of UCA1 knockdown in CDDP‐resistant OSCC cells. Moreover, UCA1 could perform as a miR‐184 sponge to modulate SF1 expression. The OSCC nude mice model experiments demonstrated that depletion of UCA1 further boosted CDDP‐mediated repression effect on tumor growth. UCA1 accelerated proliferation, increased CDDP chemoresistance and restrained apoptosis partly through modulating SF1 via sponging miR‐184 in OSCC cells, suggesting that targeting UCA1 may be a potential therapeutic strategy for OSCC patients

MiR-204 enhances mitochondrial apoptosis in doxorubicin-treated prostate cancer cells by targeting SIRT1/p53 pathway

Chemotherapy is important for adjuvant treatment of prostate cancer. However, some cancer cells exhibited low sensitivity to chemotherapeutic agents. We are supposed to sensitize these prostate cancer cells to chemotherapeutic agents such as doxorubicin. Previous reports have suggested that microRNAs (miRNAs) regulate chemosensitivity in various cancers. In the present study, we observed that expression level of miR-204 was decreased in prostate cancer cell lines and patients’ tumors. Furthermore, we found that restore of miR-204 dramatically enhanced the cytotoxicity of doxorubicin (DOX) against prostate cancer cell lines C4-2 and LNCaP carrying wild type (WT) p53. Mechanically, miR-204 in prostate cancer cells targets SIRT1 which is a histone deacetylase, and thus decreasing deacetylation of p53. As the results, acetylated p53 induced by DOX upregulates the expression of Noxa and Puma followed by induction of mitochondrial apoptosis. These data demonstrate that restore of miR-204 in prostate cancer cells enhances the mitochondrial apoptosis induced by doxorubicin by targeting the SIRT1/p53 pathway.

Prognostic role of long non-coding RNA TUG1 expression in various cancers: a meta-analysis

Several studies were conducted to explore the prognostic role of long non-coding RNA taurine upregulated gene 1 (lncRNA TUG1) expression in various cancers, with contradictory. This study aims to summarize the prognostic role of lncRNA TUG1 expression in various cancers. Embase, PubMed and Cochrane Library were completely retrieved. The cohort studies focusing on the prognostic role of lncRNA TUG1 expression in various cancers were eligible. The endpoints were overall survival (OS) and clinicopathological parameters. 9 studies involving a total of 1,078 patients were identified. The results showed that high lncRNA TUG1 expression was obviously associated with worse OS when compared to the low lncRNA TUG1 expression (HR = 1.37, 95% CI = 1.07–1.76, P = 0.01; I² = 85%). However, No distinct relationship was observed between the lncRNA TUG1 expression and age (OR = 0.99, 95% CI = 0.76–1.28, P = 0.92; I2 = 4%), gender (OR = 0.92, 95% CI = 0.70–1.22, P = 0.57; I² = 0%), diameter (OR = 0.83, 95% CI = 0.34–2.01, P = 0.67; I² = 85%), smoking (OR = 1.09, 95% CI = 0.37–3.21, P = 0.87; I² = 73%), TNM stage (OR = 0.60, 95% CI = 0.25–1.43, P = 0.25; I² = 86%) and lymph node metastasis (OR = 1.07, 95% CI = 0.47–2.45, P = 0.87; I² = 86%). In conclusion, it was revealed that high lncRNA TUG1 expression is an unfavorable predictor of OS in patients with cancers, and lncRNA TUG1 expression is a promising prognostic biomarker for various cancers.

Long Noncoding RNA H19 Acts as a Competing Endogenous RNA to Mediate CTGF Expression by Sponging miR-455 in Cardiac Fibrosis

Cardiac fibrosis is closely related to multiple cardiovascular system diseases, and noncoding RNAs (ncRNAs), including long noncoding RNA (lncRNA) and microRNA (miRNA), have been reported to play a vital role in fibrogenesis. The present study aims to investigate the potential regulatory mechanism of lncRNA H19 and miR-455 on fibrosis-associated protein synthesis in cardiac fibroblasts (CFs). miRNA microarray assay revealed 34 significantly dysregulated miRNAs, including 13 upregulated miRNAs and 21 downregulated miRNAs. Among these aberrantly expressed miRNAs, we paid attention to miR-455, which was significantly downregulated in diabetic mouse myocardium and Ang II-induced CFs. Loss- and gain-of-function experiments showed that miR-455 expression levels were negatively correlated with collagen I and III expression in Ang II-induced CFs. Bioinformatic prediction programs (TargetScan, miRanda, starBase) predicted that miR-455 targeted connective tissue growth factor (CTGF) and H19 with complementary binding sites at the 3'-untranslated region, which was validated by luciferase reporter assay. Functional validation assay demonstrated that H19 knockdown could enhance the antifibrotic role of miR-455 and attenuate the CTGF expression and further decrease fibrosis-associated protein synthesis (collagen I, III, and α-SMA). The present study reveals a novel function of the H19/miR-455 axis targeting CTGF in cardiac fibrosis, suggesting its potential therapeutic role in cardiac diseases.

Epigenetic Modifications and Head and Neck Cancer: Implications for Tumor Progression and Resistance to Therapy

Head and neck squamous carcinoma (HNSCC) is the sixth most prevalent cancer and one of the most aggressive malignancies worldwide. Despite continuous efforts to identify molecular markers for early detection, and to develop efficient treatments, the overall survival and prognosis of HNSCC patients remain poor. Accumulated scientific evidences suggest that epigenetic alterations, including DNA methylation, histone covalent modifications, chromatin remodeling and non-coding RNAs, are frequently involved in oral carcinogenesis, tumor progression, and resistance to therapy. Epigenetic alterations occur in an unsystematic manner or as part of the aberrant transcriptional machinery, which promotes selective advantage to the tumor cells. Epigenetic modifications also contribute to cellular plasticity during tumor progression and to the formation of cancer stem cells (CSCs), a small subset of tumor cells with self-renewal ability. CSCs are involved in the development of intrinsic or acquired therapy resistance, and tumor recurrences or relapse. Therefore, the understanding and characterization of epigenetic modifications associated with head and neck carcinogenesis, and the prospective identification of epigenetic markers associated with CSCs, hold the promise for novel therapeutic strategies to fight tumors. In this review, we focus on the current knowledge on epigenetic modifications observed in HNSCC and emerging Epi-drugs capable of sensitizing HNSCC to therapy.

Long Noncoding RNA CCAT2 Knockdown Suppresses Tumorous Progression by Sponging miR-424 in Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the one of most common gynecological malignant tumors with high mortality. A series of long noncoding RNAs (lncRNAs) have been validated to play a vital role in EOC tumorigenesis. Colon cancer-associated transcript 2 (CCAT2) has been verified as an oncogenic lncRNA in multiple tumors; however, the role of CCAT2 in EOC genesis is still unclear. The purpose of the present study was to probe the function of CCAT2 on EOC. Preliminary experiments found that CCAT2 expression was significantly upregulated in EOC tissues and cell lines compared to noncancerous tissue and cells. CCAT2 knockdown induced by interfering oligonucleotides could inhibit proliferation and promote apoptosis and induce cell cycle arrest at the G₀/G₁ phase. Bioinformatics analysis predicted that miR-424 targeted CCAT2, which was confirmed by luciferase reporter assay. Moreover, the miR-424 inhibitor rescued the tumorigenesis inhibition induced by CCAT2 knockdown. In summary, our findings illustrate that CCAT2 acts as competing endogenous RNA (ceRNA) or sponge via negatively targeting miR-424, providing a novel diagnostic marker and therapeutic target for EOC.