Elevated HOTAIR expression associated with cisplatin resistance in non-small cell lung cancer patients

Green-synthesized copper oxide nanoparticles induce apoptosis and up-regulate HOTAIR and HOTTIP in pancreatic cancer cells

Aim: Cu2O nanoparticles were synthesized using an extract from S. latifolium algae (SLCu2O NPs). Their effect on PANC-1 cells and the expression of two drug resistance-related lncRNAs were evaluated in comparison with Arsenic trioxide.Materials & methods: SLCu2O NPs were characterized using XRD, SEM, and TEM microscopies. The effects of SLCu2O NPs on cell cytotoxicity, cell cycle, and apoptosis, and expression of two drug resistance-related lncRNAs were examined using MTT assay, flow cytometry, and real-time PCR, respectively.Results: SLCu2O NPs demonstrated anti-cancer properties against PANC-1 cells comparable to Arsenic trioxide, and the expression of lncRNAs increased upon treatment with them.Conclusion: SLCu2O NPs demonstrate anti-cancer properties against PANC-1 cells; however, using gene silencing strategies along with SLCu2O NPs is suggested.

The Potential Links between lncRNAs and Drug Tolerance in Lung Adenocarcinoma

Lung cancer patients treated with targeted therapies frequently respond well but invariably relapse due to the development of drug resistance. Drug resistance is in part mediated by a subset of cancer cells termed "drug-tolerant persisters" (DTPs), which enter a dormant, slow-cycling state that enables them to survive drug exposure. DTPs also exhibit stem cell-like characteristics, broad epigenetic reprogramming, altered metabolism, and a mutagenic phenotype mediated by adaptive mutability. While several studies have characterised the transcriptional changes that lead to the altered phenotypes exhibited in DTPs, these studies have focused predominantly on protein coding changes. As long non-coding RNAs (lncRNAs) are also implicated in the phenotypes altered in DTPs, it is likely that they play a role in the biology of drug tolerance. In this review, we outline how lncRNAs may contribute to the key characteristics of DTPs, their potential roles in tolerance to targeted therapies, and the emergence of genetic resistance in lung adenocarcinoma.

The role of HOTAIR in the modulation of resistance to anticancer therapy

Leading anti-tumour therapeutic strategies typically involve surgery and radiotherapy for locally advanced (non-metastatic) cancers, while hormone therapy, chemotherapy, and molecular targeted therapy are the current treatment options for metastatic cancer. Despite the initially high sensitivity rate to anticancer therapies, a large number of patients develop resistance, leading to a poor prognosis. The mechanisms related to drug resistance are highly complex, and long non-coding RNAs appear to play a crucial role in these processes. Among these, the lncRNA homeobox transcript antisense intergenic RNA (HOTAIR), widely implicated in cancer initiation and progression, likewise plays a significant role in anticancer drug resistance. It can modulate cell activities such as proliferation, apoptosis, hypoxia, autophagy, as well as epithelial-mesenchymal transition, thereby contributing to the development of resistant tumour cells. In this manuscript, we describe different mechanisms of antitumor drug resistance in which HOTAIR is involved and suggest its potential as a therapeutic predictive biomarker for the management of cancer patients.

Non-coding RNAs and exosomal non-coding RNAs in lung cancer: insights into their functions

Lung cancer is the second most common form of cancer worldwide Research points to the pivotal role of non-coding RNAs (ncRNAs) in controlling and managing the pathology by controlling essential pathways. ncRNAs have all been identified as being either up- or downregulated among individuals suffering from lung cancer thus hinting that they may play a role in either promoting or suppressing the spread of the disease. Several ncRNAs could be effective non-invasive biomarkers to diagnose or even serve as effective treatment options for those with lung cancer, and several molecules have emerged as potential targets of interest. Given that ncRNAs are contained in exosomes and are implicated in the development and progression of the malady. Herein, we have summarized the role of ncRNAs in lung cancer. Moreover, we highlight the role of exosomal ncRNAs in lung cancer.

Silencing lncRNA-DARS-AS1 suppresses nonsmall cell lung cancer progression by stimulating miR-302a-3p to inhibit ACAT1 expression

Long noncoding RNAs (LncRNAs) have been gaining attention as potential therapeutic targets for lung cancer. In this study, we investigated the expression and biological behavior of lncRNA DARS-AS1, its predicted interacting partner miR-302a-3p, and ACAT1 in nonsmall cell lung cancer (NSCLC). The transcript level of DARS-AS1, miR-302a-3p, and ACAT1 was analyzed using qRT-PCR. Endogenous expression of ACAT1 and the expression of-and changes in-AKT/ERK pathway-related proteins were determined using western blotting. MTS, Transwell, and apoptosis experiments were used to investigate the behavior of cells. The subcellular localization of DARS-AS1 was verified using FISH, and its binding site was verified using dual-luciferase reporter experiments. The binding of DARS-AS1 to miR-302a-3p was verified using RNA co-immunoprecipitation. In vivo experiments were performed using a xenograft model to determine the effect of DARS-AS1 knockout on ACAT1 and NSCLC. lncRNA DARS-AS1 was upregulated in NSCLC cell lines and tissues and the expression of lncRNA DARS-AS1 was negatively correlated with survival of patients with NSCLC. Knockdown of DARS-AS1 inhibited the malignant behaviors of NSCLC via upregulating miR-302a-3p. miR-302a-3p induced suppression of malignancy through regulating oncogene ACAT1. This study demonstrates that the DARS-AS1-miR-302a-3p-ACAT1 pathway plays a key role in NSCLC.

Z-Ligustilide Combined with Cisplatin Reduces PLPP1-Mediated Phospholipid Synthesis to Impair Cisplatin Resistance in Lung Cancer

Lung cancer is a malignant tumor with one of the highest morbidity and mortality rates in the world. Approximately 80-85% of lung cancer is diagnosed as non-small lung cancer (NSCLC), and its 5-year survival rate is only 21%. Cisplatin is a commonly used chemotherapy drug for the treatment of NSCLC. Its efficacy is often limited by the development of drug resistance after long-term treatment. Therefore, determining how to overcome cisplatin resistance, enhancing the sensitivity of cancer cells to cisplatin, and developing new therapeutic strategies are urgent clinical problems. Z-ligustilide is the main active ingredient of the Chinese medicine Angelica sinensis, and has anti-tumor activity. In the present study, we investigated the effect of the combination of Z-ligustilide and cisplatin (Z-ligustilide+cisplatin) on the resistance of cisplatin-resistant lung cancer cells and its mechanism of action. We found that Z-ligustilide+cisplatin decreased the cell viability, induced cell cycle arrest, and promoted the cell apoptosis of cisplatin-resistant lung cancer cells. Metabolomics combined with transcriptomics revealed that Z-ligustilide+cisplatin inhibited phospholipid synthesis by upregulating the expression of phospholipid phosphatase 1 (PLPP1). A further study showed that PLPP1 expression was positively correlated with good prognosis, whereas the knockdown of PLPP1 abolished the effects of Z-ligustilide+cisplatin on cell cycle and apoptosis. Specifically, Z-ligustilide+cisplatin inhibited the activation of protein kinase B (AKT) by reducing the levels of phosphatidylinositol 3,4,5-trisphosphate (PIP3). Z-ligustilide+cisplatin induced cell cycle arrest and promoted the cell apoptosis of cisplatin-resistant lung cancer cells by inhibiting PLPP1-mediated phospholipid synthesis. Our findings demonstrate that the combination of Z-Ligustilide and cisplatin is a promising approach to the chemotherapy of malignant tumors that are resistant to cisplatin.

Long Non-Coding RNAs as Emerging Targets in Lung Cancer

Long non-coding RNAs (LncRNAs) are mRNA-like molecules that do not encode for proteins and that are longer than 200 nucleotides. LncRNAs play important biological roles in normal cell physiology and organism development. Therefore, deregulation of their activities is involved in disease processes such as cancer. Lung cancer is the leading cause of cancer-related deaths due to late stage at diagnosis, distant metastasis, and high rates of therapeutic failure. LncRNAs are emerging as important molecules in lung cancer for their oncogenic or tumor-suppressive functions. LncRNAs are highly stable in circulation, presenting an opportunity for use as non-invasive and early-stage cancer diagnostic tools. Here, we summarize the latest works providing in vivo evidence available for lncRNAs role in cancer development, therapy-induced resistance, and their potential as biomarkers for diagnosis and prognosis, with a focus on lung cancer. Additionally, we discuss current therapeutic approaches to target lncRNAs. The evidence discussed here strongly suggests that investigation of lncRNAs in lung cancer in addition to protein-coding genes will provide a holistic view of molecular mechanisms of cancer initiation, development, and progression, and could open up a new avenue for cancer treatment.

Tobacco nicotine promotes TRAIL resistance in lung cancer through SNHG5

Tobacco nicotine use is carcinogenic and a well-known risk factor for lung cancer. However, whether tobacco nicotine can induce drug resistance in lung cancer is not clear. The objective of the present study was to identify the TNF-related apoptosis-inducing ligand (TRAIL) resistance of long noncoding RNAs (lncRNAs) that are differentially expressed in smokers and nonsmokers with lung cancer. The results suggested that the nicotine upregulated small nucleolar RNA host gene 5 (SNHG5) and markedly decreased the levels of cleaved caspase-3. The present study found that cytoplasm lncRNA SNHG5 overexpression was associated with TRAIL resistance in lung cancer and that SNHG5 can interact with X-linked inhibitor of apoptosis protein to promote TRAIL resistance. Therefore, nicotine promoted TRAIL resistance in lung cancer through SNHG5/X-linked inhibitor of apoptosis protein.

Cancer-associated fibroblasts in nonsmall cell lung cancer: From molecular mechanisms to clinical implications

Lung cancer is the common and leading cause of cancer death worldwide. The tumor microenvironment has been recognized to be instrumental in tumorigenesis. To have a deep understanding of the molecular mechanism of nonsmall cell lung carcinoma (NSCLC), cancer-associated fibroblasts (CAFs) have gained increasing research interests. CAFs belong to the crucial and dominant cell population in the tumor microenvironment to support the cancer cells. The interplay and partnership between cancer cells and CAFs contribute to each stage of tumorigenesis. CAFs exhibit prominent heterogeneity and secrete different kinds of cytokines and chemokines, growth factors and extracellular matrix proteins involved in cancer cell proliferation, invasion, metastasis and chemoresistance. Many studies focused on the protumorigenic functions of CAFs, yet many challenges about the heterogeneity of CAFS remain unresolved. This review comprehensively summarized the tumor-promoting role and molecular mechanisms of CAFs in NSCLC, including their origin, phenotypic changes and heterogeneity and their functional roles in carcinogenesis. Meanwhile, we also highlighted the updated molecular classifications based on the molecular features and functional roles of CAFs. With the development of cutting-edge platforms and further investigations of CAFs, novel therapeutic strategies for accurately targeting CAFs in NSCLC may be developed based on the increased understanding of the relevant molecular mechanisms.

Functions and underlying mechanisms of lncRNA HOTAIR in cancer chemotherapy resistance

Chemotherapy has been one of the most important treatments for advanced cancer in recent decades. Although the sensitivity rate of initial chemotherapy is high, patients with chemotherapy resistant tumors, experience tumor recurrence. In recent years, many studies have shown that homeobox transcript antisense intergenic RNA (HOTAIR) is involved in many pathological processes including carcinogenesis. The abnormal regulation of a variety of cell functions by HOTAIR, such as apoptosis, the cell cycle, epithelial-mesenchymal transition, autophagy, self-renewal, and metabolism, is associated with chemotherapy resistance. Therefore, there is an urgent need to understand the biology and mechanism underlying the role of HOTAIR in tumor behavior and its potential as a biomarker for predicting the effect of chemotherapy. In this manuscript, we review the mechanisms underlying HOTAIR-related drug resistance and discuss the limitations of current knowledge and propose potential future directions.

Emerging roles of long noncoding RNAs in chemoresistance of pancreatic cancer

Pancreatic cancer is one of the most common causes of cancer death in the world due to the lack of early symptoms, metastasis occurrence and chemoresistance. Therefore, early diagnosis by detection of biomarkers, blockade of metastasis, and overcoming chemoresistance are the effective strategies to improve the survival of pancreatic cancer patients. Accumulating evidence has revealed that long noncoding RNA (lncRNA) and circular RNAs (circRNAs) play essential roles in modulating chemosensitivity in pancreatic cancer. In this review article, we will summarize the role of lncRNAs in drug resistance of pancreatic cancer cells, including HOTTIP, HOTAIR, PVT1, linc-ROR, GAS5, UCA1, DYNC2H1-4, MEG3, TUG1, HOST2, HCP5, SLC7A11-AS1 and CASC2. We also highlight the function of circRNAs, such as circHIPK3 and circ_0000284, in regulation of drug sensitivity of pancreatic cancer cells. Moreover, we describe a number of compounds, including curcumin, genistein, resveratrol, quercetin, and salinomycin, which may modulate the expression of lncRNAs and enhance chemosensitivity in pancreatic cancers. Therefore, targeting specific lncRNAs and cicrRNAs could contribute to reverse chemoresistance of pancreatic cancer cells. We hope this review might stimulate the studies of lncRNAs and cicrRNAs, and develop the new therapeutic strategy via modulating these noncoding RNAs to promote chemosensitivity of pancreatic cancer cells.

Long Noncoding RNAs in Lung Cancer: From Disease Markers to Treatment Roles

There is an urgent need to identify reliable biomarkers that can be used in early diagnosis, prognostication prediction and as possible therapeutic targets for lung cancer due to its current poor prognosis. Long noncoding RNAs (lncRNAs) have recently attracted additional attention due to their potential role in carcinogenesis, invasion and metastasis. Issues involved in the biofunctions and regulatory mechanisms of oncogenic and tumor-suppressive lncRNAs in lung cancer are discussed. Some lncRNAs have shown good diagnostic value, especially in combination with conventional serum protein markers. The use of antisense oligonucleotides, small molecules and RNA interference techniques have shown promise as direct therapeutic tools for targeting lncRNAs in preclinical studies. The biomarker function of lncRNAs may also indirectly involved in tumor therapy as a reference to conventional therapy. Overall, the concept of using lncRNAs as biomarkers for prognostication and intervention in lung cancer is still in its infancy, and only with more in-depth studies could they have a significant impact.

Long Non-Coding RNAs in Lung Cancer: The Role in Tumor Microenvironment

The development of various therapeutic interventions, particularly immune checkpoint inhibitor therapy, have effectively induced tumor remission for patients with advanced lung cancer. However, few cancer patients can obtain significant and long-lasting therapeutic effects for the limitation of immunological nonresponse and resistance. For this case, it’s urgent to identify new biomarkers and develop therapeutic targets for future immunotherapy. Over the past decades, tumor microenvironment (TME)-related long non-coding RNAs (lncRNAs) have gradually become well known to us. A large number of existing studies have indicated that TME-related lncRNAs are one of the major factors to realize precise diagnosis and treatment of lung cancer. Herein, this paper discusses the roles of lncRNAs in TME, and the potential application of lncRNAs as biomarkers or therapeutic targets for immunotherapy in lung cancer.

The expression of long non-coding RNA HOTAIR in advanced hepatocellular carcinoma and its prognostic correlation with sunitinib therapy

INTRODUCTION

The study was designed to assess the expression of long non-coding RNA HOTAIR (lncRNA HOTAIR) in tissues and peripheral blood of patients with advanced hepatocellular carcinoma (HCC). In addition, we also investigated the prognostic correlation between the expression level of lncRNA HOTAIR in tumour tissues and peripheral blood of patients with advanced HCC and sunitinib monotherapy.

MATERIAL AND METHODS

A total of 60 patients with advanced HCC who received sunitinib monotherapy and another 60 healthy individuals who were examined at the physical examination centre during the same period were included in the study. Real-time quantitative PCR (RT-QPCR) was used to determine the relative expression of lncRNA HOTAIR in tumour tissue, adjacent tissue, and peripheral blood of HCC patients as well as peripheral blood of healthy controls. Moreover, the clinicopathological information, overall survival (OS), and progression-free survival (PFS) were collected, followed by correlation analysis with lncRNA HOTAIR expression.

RESULTS

The expression of lncRNA HOTAIR was significantly higher in tumour tissues compared to that in adjacent tissues (t = 9.03, p < 0.001). The expression of lncRNA HOTAIR in peripheral blood of HCC patients was higher than that in healthy controls (t = 8.04, p < 0.001). There was a correlation between the expression of lncRNA HOTAIR in tumour tissue and peripheral blood in HCC patients (r = 0.638, p < 0.001). Patients with low lncRNA HOTAIR expression in tumour tissues harboured significantly longer OS (13.4 vs. 9.5, p < 0.001) and PFS (8.4 vs. 6.2, p < 0.001) compared to those with high expression. Consistently, patients with low lncRNA HOTAIR expression in peripheral blood had significantly prolonged OS (12.8 vs. 9.1, p < 0.001) and PFS (8.9 vs. 6.4, p < 0.001) compared to those with high expression. Patients with low expression both in tumour tissue and peripheral blood had prolonged OS (14.3 vs. 8.8, p < 0.001) and PFS (10.6 vs. 6.0, p < 0.001) compared to the rest of the patients. Cox regression analysis indicated that the expression level of lncRNA HOTAIR in tumour tissue and peripheral blood was an independent predictive factor of OS and PFS in patients with advanced HCC treated by sunitinib.

CONCLUSIONS

The expression of lncRNA HOTAIR was up-regulated in tumour tissue and peripheral blood in patients with advanced HCC. In addition, the expression level of lncRNA HOTAIR was one of the indicators predicting the effectiveness of sunitinib therapy.

The Role of lncRNAs in Rare Tumors with a Focus on HOX Transcript Antisense RNA (HOTAIR)

Rare cancers are identified as those with an annual incidence of fewer than 6 per 100,000 persons and includes both epithelial and stromal tumors from different anatomical areas. The advancement of analytical methods has produced an accurate molecular characterization of most human cancers, suggesting a “molecular classification” that has allowed the establishment of increasingly personalized therapeutic strategies. However, the limited availability of rare cancer samples has resulted in very few therapeutic options for these tumors, often leading to poor prognosis. Long non coding RNAs (lncRNAs) are a class of non-coding RNAs mostly involved in tumor progression and drug response. In particular, the lncRNA HOX transcript antisense RNA (HOTAIR) represents an emergent diagnostic, prognostic and predictive biomarker in many human cancers. The aim of this review is to highlight the role of HOTAIR in rare cancers, proposing it as a new biomarker usable in the management of these tumors.

Cancer-associated fibroblast-derived CCL5 contributes to cisplatin resistance in A549 NSCLC cells partially through upregulation of lncRNA HOTAIR expression

Aberrant C-C motif chemokine ligand 5 (CCL5) is associated with disease progression, poor prognosis and chemotherapy resistance in human malignancy. The tumor microenvironment (TME) contributes to chemotherapy resistance. However, the role of cancer-associated fibroblasts (CAFs)-derived CCL5 is not well documented. Hence, the present study aimed to investigate the effects of CAFs on chemotherapy resistance in A549 non-small cell lung cancer (NSCLC) cells and the underlying mechanism. Primary CAFs isolated from patients with NSCLC were found to express and secrete elevated levels of CCL5, which attenuated cisplatin (DDP)-induced apoptosis, as indicated by flow cytometry analysis. In addition, CCL5 upregulated the expression levels of long non-coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) in the tumor cells, and silencing HOTAIR in tumor cells enhanced the cytotoxic effect of cisplatin, characterized by decreased cell viability and increased apoptotic rate. Mechanistically, HOTAIR was found to inactivate the caspase-3/BCL-2 signaling pathway in A549 NSCLC cells. Collectively, the current study demonstrated that CAFs in the TME may serve a crucial role in the higher expression levels of CCL5 in tumors and that CAF-derived CCL5 may promote cisplatin resistance via upregulating lncRNA HOTAIR expression.

Norcycloartocarpin targets Akt and suppresses Akt-dependent survival and epithelial-mesenchymal transition in lung cancer cells

In searching for novel targeted therapeutic agents for lung cancer treatment, norcycloartocarpin from Artocarpus gomezianus was reported in this study to promisingly interacted with Akt and exerted the apoptosis induction and epithelial-to-mesenchymal transition suppression. Selective cytotoxic profile of norcycloartocarpin was evidenced with approximately 2-fold higher IC50 in normal dermal papilla cells (DPCs) compared with human lung cancer A549, H460, H23, and H292 cells. We found that norcycloartocarpin suppressed anchorage-independent growth, cell migration, invasion, filopodia formation, and decreased EMT in a dose-dependent manner at 24 h, which were correlated with reduced protein levels of N-cadherin, Vimentin, Slug, p-FAK, p-Akt, as well as Cdc42. In addition, norcycloartocarpin activated apoptosis caspase cascade associating with restoration of p53, down-regulated Bcl-2 and augmented Bax in A549 and H460 cells. Interestingly, norcycloartocarpin showed potential inhibitory role on protein kinase B (Akt) the up-stream dominant molecule controlling EMT and apoptosis. Computational molecular docking analysis further confirmed that norcycloartocarpin has the best binding affinity of -12.52 kcal/mol with Akt protein at its critical active site. As Akt has recently recognized as an attractive molecular target for therapeutic approaches, these findings support its use as a plant-derived anticancer agent in cancer therapy.

Targeting Epigenetics in Lung Cancer

The epigenetic landscape, which in part includes DNA methylation, chromatin organization, histone modifications, and noncoding RNA regulation, greatly contributes to the heterogeneity that makes developing effective therapies for lung cancer challenging. This review will provide an overview of the epigenetic alterations that have been implicated in all aspects of cancer pathogenesis and progression as well as summarize clinical applications for targeting epigenetics in the treatment of lung cancer.

Regulation of Long Non-Coding RNAs by Plant Secondary Metabolites: A Novel Anticancer Therapeutic Approach

Simple Summary

Cancer is caused by the rapid and uncontrolled growth of cells that eventually lead to tumor formation. Genetic and epigenetic alterations are among the most critical factors in the onset of carcinoma. Phytochemicals are a group of natural compounds that play an essential role in cancer prevention and treatment. Long non-coding RNAs (lncRNAs) are potential therapeutic targets of bioactive phytochemicals, and these compounds could regulate the expression of lncRNAs directly and indirectly. Here, we critically evaluate in vitro and in vivo anticancer effects of phytochemicals in numerous human cancers via regulation of lncRNA expression and their downstream target genes.

Abstract

Long non-coding RNAs (lncRNAs) are a class of non-coding RNAs that play an essential role in various cellular activities, such as differentiation, proliferation, and apoptosis. Dysregulation of lncRNAs serves a fundamental role in the progression and initiation of various diseases, including cancer. Precision medicine is a suitable and optimal treatment method for cancer so that based on each patient’s genetic content, a specific treatment or drug is prescribed. The rapid advancement of science and technology in recent years has led to many successes in this particular treatment. Phytochemicals are a group of natural compounds extracted from fruits, vegetables, and plants. Through the downregulation of oncogenic lncRNAs or upregulation of tumor suppressor lncRNAs, these bioactive compounds can inhibit metastasis, proliferation, invasion, migration, and cancer cells. These natural products can be a novel and alternative strategy for cancer treatment and improve tumor cells’ sensitivity to standard adjuvant therapies. This review will discuss the antineoplastic effects of bioactive plant secondary metabolites (phytochemicals) via regulation of expression of lncRNAs in various human cancers and their potential for the treatment and prevention of human cancers.

Functional Interaction among lncRNA HOTAIR and MicroRNAs in Cancer and Other Human Diseases

Simple Summary

This review aimed to describe the contribution of functional interaction between the lncRNA HOTAIR and microRNAs in human diseases, including cancer. HOTAIR/miRNAs complexes interfere with different cellular processes during carcinogenesis, mainly deregulating a series of oncogenic signaling pathways. A great number of ncRNAs-related databases have been established, supported by bioinformatics technologies, to identify the ncRNA-mediated sponge regulatory network. These approaches need experimental validation through cells and animal models studies. The optimization of systems to interfere with HOTAIR/miRNAs interplay could represent a new tool for the definition of diagnostic therapeutics in cancer patients.

Abstract

LncRNAs are a class of non-coding RNAs mostly involved in regulation of cancer initiation, metastatic progression, and drug resistance, through participation in post-transcription regulatory processes by interacting with different miRNAs. LncRNAs are able to compete with endogenous RNAs by binding and sequestering miRNAs and thereby regulating the expression of their target genes, often represented by oncogenes. The lncRNA HOX transcript antisense RNA (HOTAIR) represents a diagnostic, prognostic, and predictive biomarker in many human cancers, and its functional interaction with miRNAs has been described as crucial in the modulation of different cellular processes during cancer development. The aim of this review is to highlight the relation between lncRNA HOTAIR and different microRNAs in human diseases, discussing the contribution of these functional interactions, especially in cancer development and progression.

LncRNAs and miRNAs participate in determination of sensitivity of cancer cells to cisplatin

Cisplatin is an extensively used chemotherapeutic substance for various types of human malignancies including sarcomas, carcinomas and lymphomas. Yet, the vast application of this drug is hampered by the emergence of chemoresistance in some treated patients. Several mechanisms such as degradation of the membrane transporters by cisplatin have been implicated in the pathogenesis of this event. Recent researches have also indicated the role of long non-coding RNAs (lncRNAs) as well as micoRNAs (miRNAs) in the emergence of resistance to cisplatin in several cancer types. For instance, up-regulation of miR-21 has been associated with resistance to this agent in ovarian cancer, oral squamous cell cancer, gastric malignancy and non-small cell lung cancer (NSCLC). On the other hand, down-regulation of miR-218 has been implicated in emergence of chemoresistance in breast cancer and esophageal squamous cell carcinoma. MALAT1 is implicated in the chemoresistance of bladder cancer cells, NSCLC, gastric cancer and cervical cancer. Most notably, the expression profile of resistance-associated miRNAs and lncRNAs can predict overall survival of cancer patients. Mechanistic assays have revealed that interference with expression of some miRNAs and lncRNAs can reverse the resistance phenotype in cancer cells. In this paper, we review the scientific writings on the role of lncRNAs and miRNAs in the evolution of chemoresistance to cisplatin in cancer cells.

Overexpression of LncRNA-HOTAIR promotes chemoresistance in acute leukemia cells

Chemotherapy treatment of acute myeloid leukemia (AML) can be compromised due to the multidrug resistance (MDR) of leukemia cells. HOTAIR, a long noncoding RNA (LncRNA), is involved in MDR development of various solid tumors. However, whether it functions in MDR development of leukemia remains unclear. In this study, expressions of HOTAIR in leukemia cell line K562/A02 and bone marrow samples from 10 patients with refractory and relapsed AML were detected by qRT-PCR. The apoptosis, proliferation, and susceptibility of K562/A02 cells to Adriamycin (ADR) were analyzed by flow cytometry and CCK8 assay, respectively. The expression of cell cycle regulator P21 and Notch1 in the K562/A02 cells was examined by qRT-PCR. The accumulation of total AKT and the phosphorylated AKT (pAKT^S473) were detected by western blotting. We found that the expression of HOTAIR in drug-resistant cells and patient samples was increased. Inhibition of HOTAIR expression could suppress the proliferation, increase the apoptosis, and promote the doxorubicin sensitivity of K562/A02 cells. Moreover, inhibiting expression of HOTAIR could attenuate the expression of P21 and Notch1 and inhibit the phosphorylation of AKT in drug-resistant cells. In conclusion, our results demonstrated that LncRNA-HOTAIR is involved in MDR development of leukemia cells by regulating the expression of P21 and the AKT/Notch1 signaling pathway.

Knockdown of Long Non-Coding RNA HOTAIR Suppresses Cisplatin Resistance, Cell Proliferation, Migration and Invasion of DDP-Resistant NSCLC Cells by Targeting miR-149-5p/Doublecortin-Like Kinase 1 Axis

Background

Long non-coding RNA (lncRNA) HOTAIR has been reported to be associated with cisplatin (DDP) resistance in different human cancers including non-small cell lung cancer (NSCLC). However, the mechanism of HOTAIR in cisplatin resistance of NSCLC remains largely undefined.

Materials and Methods

Expression of HOTAIR, miR-149-5p and doublecortin-like kinase 1 (DCLK1) was detected using real-time quantitative PCR (RT-qPCR) and Western blotting. Cisplatin resistance was determined with cell counting kit (CCK)-8 assay and transwell assays in vitro, and xenograft tumor models in vivo. The target binding between miR-149-5p and either HOTAIR or DCLK1 was predicted on Diana Tools website, and confirmed by dual-luciferase reporter assay and RNA immunoprecipitation.

Results

Expression of HOTAIR was upregulated in DDP-resistant NSCLC tumor tissues and cell lines (A549/DDP and H1299/DDP). Knockdown of HOTAIR decreased the acquired cisplatin resistance of A549/DDP and H1299/DDP cells, as evidenced by attenuated 50% inhibitory concentration (IC50) of DDP, cell proliferation, migration and invasion in vitro, as well as tumor growth inhibition in vivo. Mechanically, HOTAIR negatively regulated miR-149-5p expression via targeting, and DCLK1 was a downstream target for miR-149-5p. DCLK1 was indirectly regulated by HOTAIR in DDP-resistant NSCLC cells as well. Functionally, miR-149-5p deletion could counteract the inhibitory effect of HOTAIR knockdown on cisplatin resistance; contrarily, restoring miR-149-5p exhibited the similar inhibition on cisplatin resistance in DDP-resistant cells in vitro, which was then abated by DCLK1 upregulation.

Conclusion

Knockdown of HOTAIR enhances DDP-resistant NSCLC cells to overcome cisplatin resistance partially via regulating miR-149-5p/DCLK1 axis.

Long non‑coding RNA LUCAT1 contributes to cisplatin resistance by regulating the miR‑514a‑3p/ULK1 axis in human non‑small cell lung cancer

Drug resistance is a major obstacle in the therapy of malignant tumors, including non-small cell lung cancer (NSCLC). Long non-coding RNAs (lncRNAs) have been demonstrated to be involved in chemoresistance. The present study aimed to investigate the role of lung cancer-associated transcript 1 (LUCAT1) in cisplatin (DDP) resistance in NSCLC. By using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), it was found that the expression of LUCAT1 was elevated and that of microRNA-514a-3p (miR-514a-3p) was decreased in DDP-resistant NSCLC tissues and cells. Functionally, LUCAT1 upregulation enhanced cisplatin resistance by promoting the viability, autophagy and metastasis, and inhibiting the apoptosis of NSCLC cells, as demonstrated by Cell Counting kit-8 (CCK-8) assay, western blot analysis, Transwell assay and flow cytometric analysis. LUCAT1 was identified as a sponge of miR-514a-3p and uncoordinated-51-like kinase 1 (ULK1) was proven to be a target gene of miR-514a-3p by bioinformatics analysis, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The enhancing effect of miR-514a-3p on cisplatin sensitivity was reversed by the elevation of LUCAT1. ULK1 knockdown suppressed cisplatin resistance, while this effect was attenuated by miR-514a-3p inhibition. Moreover, LUCAT1 positively regulated ULK1 expression by targeting miR-514a-3p. In addition, LUCAT1 knockdown suppressed tumor growth in vivo. On the whole, the findings of the present study demonstrate that LUCAT1 contributes to the resistance of NSCLC cells to cisplatin by regulating the miR-514a-3p/ULK1 axis, elucidating a novel regulatory network in cisplatin resistance in NSCLC.

The role of long non-coding RNAs in drug resistance of cancer

Long non-coding RNAs (lncRNAs), a class of long RNAs, are longer than 200 nucleotides in length but lack protein-coding capacity. LncRNAs, as critical genomic regulators, are involved in genomic imprinting regulation, histone modification and gene expression regulation as well as tumor initiation and progression. However, it is also found that lncRNAs are associated with drug resistance in several types of cancer. Drug resistance is an important reason for clinical chemotherapy failure, and the molecular mechanism of tumor resistance is complex, which is a process of multi-cause, multi-gene and multi-signal transduction pathway interaction. Then comprehending the mechanisms of chemoresistance will help find ways to control the tumor progression effectively. Therefore, in this review, we will construct lncRNAs /drug resistance interaction network and shed light on the role of lncRNAs in drug resistance.

HOTAIR induces EGFR-TKIs resistance in non-small cell lung cancer through epithelial-mesenchymal transition

OBJECTIVE

Previous research found that HOTAIR, a long non-coding RNA, is aberrantly expressed and associated with tumor invasion, metastasis and chemo-resistance in many cancers. The aim of this study was to investigate the role of HOTAIR in resistance of EGFR-TKIs in NSCLC.

METHODS

HOTAIR expression level was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR) in NSCLC cell lines or tumor tissues. A total of 62 samples with EGFR-mutant and EGFR-TKI-sensitive NSCLCs, 42 with acquired resistance and 27 with primary resistance to EGFR-TKIs were analyzed. The effect of HOTAIR on cell proliferation and apoptosis was undergone by CCK-8 and flow cytometry assays. The expression of EMT proteins was assessed by western blot.

RESULTS

HOTAIR was significantly down-regulated in lung cancer cells (PC9/R, H1975, H1299 and A549) and patients with primary and acquired resistance to EGFR-TKIs. In clinical setting, high levels of HOTAIR expression was significantly correlated with longer progression-free survival (PFS) [P < 0.01] compared with low HOTAIR expression subgroup in tumors which respond to EGFR-TKIs. In vitro, over-expression HOTAIR could restore gefitinib sensitivity in gefitinib-resistant cells (PC9/R, H1299 and A549), but this change in sensitivity was not observed in H1975. Up-regulated HOTAIR induced cell apoptosis in PC9/R, H1299 and A549, and activated epithelial-mesenchymal transition (EMT).

CONCLUSIONS

HOTAIR expression was associated with primary and acquired resistance to EGFR-TKIs and could regulate cell proliferation through activating cell apoptosis and EMT, which suggest that HOTAIR might be able to act as a biomarker to predict the EGFR-TKIs resistance.

The functional role of long noncoding RNA in resistance to anticancer treatment

Chemotherapy is one of the fundamental methods of cancer treatment. However, drug resistance remains the main cause of clinical treatment failure. We comprehensively review the newly identified roles of long noncoding RNAs (lncRNAs) in oncobiology that are associated with drug resistance. The expression of lncRNAs is tissue-specific and often dysregulated in human cancers. Accumulating evidence suggests that lncRNAs are involved in chemoresistance of cancer cells. The main lncRNA-driven mechanisms of chemoresistance include regulation of drug efflux, DNA damage repair, cell cycle, apoptosis, epithelial-mesenchymal transition (EMT), induction of signaling pathways, and angiogenesis. LncRNA-driven mechanisms of resistance to various antineoplastic agents have been studied extensively. There are unique mechanisms of resistance against different types of drugs, and each mechanism may have more than one contributing factor. We summarize the emerging strategies that can be used to overcome the technical challenges in studying and addressing lncRNA-mediated drug resistance.

Exosomal Long Non-Coding RNAs in Lung Diseases

Within the non-coding genome landscape, long non-coding RNAs (lncRNAs) and their secretion within exosomes are a window that could further explain the regulation, the sustaining, and the spread of lung diseases. We present here a compilation of the current knowledge on lncRNAs commonly found in Chronic Obstructive Pulmonary Disease (COPD), asthma, Idiopathic Pulmonary Fibrosis (IPF), or lung cancers. We built interaction networks describing the mechanisms of action for COPD, asthma, and IPF, as well as private networks for H19, MALAT1, MEG3, FENDRR, CDKN2B-AS1, TUG1, HOTAIR, and GAS5 lncRNAs in lung cancers. We identified five signaling pathways targeted by these eight lncRNAs over the lung diseases mentioned above. These lncRNAs were involved in ten treatment resistances in lung cancers, with HOTAIR being itself described in seven resistances. Besides, five of them were previously described as promising biomarkers for the diagnosis and prognosis of asthma, COPD, and lung cancers. Additionally, we describe the exosomal-based studies on H19, MALAT1, HOTAIR, GAS5, UCA1, lnc-MMP2-2, GAPLINC, TBILA, AGAP2-AS1, and SOX2-OT. This review concludes on the need for additional studies describing the lncRNA mechanisms of action and confirming their potential as biomarkers, as well as their involvement in resistance to treatment, especially in non-cancerous lung diseases.

Long Non-Coding RNA HOTAIR in Breast Cancer Therapy

Breast cancer (BC) is the most common cancer type among women, and morbidity and mortality rates are still very high. Despite new innovative therapeutic approaches for all BC molecular subtypes, the discovery of new molecular biomarkers involved in tumor progression has been fundamental for the implementation of personalized treatment strategies and improvement of patient management. Many experimental studies indicate that long non-coding RNAs (lncRNAs) are strongly involved in BC initiation, metastatic progression, and drug resistance. In particular, aberrant expression of HOX transcript antisense intergenic RNA (HOTAIR) lncRNA plays an important role in BC contributing to its progression and represents a predictor of BC metastasis. For its proven prognostic value, HOTAIR could represent a potential therapeutic target in BC. In the present review, we summarize the role of HOTAIR in cancer progression and drug resistance, in particular in BC, and we illustrate the main approaches for silencing it.

Long Non-Coding RNA in Drug Resistance of Non-Small Cell Lung Cancer: A Mini Review

Lung cancer is one of main causes of cancer mortality and 83% of lung cancer cases are classified as non-small cell lung cancer (NSCLC). Patients with NSCLC usually have a poor prognosis and one of the leading causes is drug resistance. With the progress of drug therapy, the emergence and development of drug resistance affected the prognosis of patients severely. Accumulating evidence reveals that long non-coding RNAs (lncRNAs), as “dark matters” of the human genome, is of great significance to drug resistance in NSCLC. Herein, we review the role of lncRNAs in drug resistance in NSCLC.

Circ_ZNF124 promotes non-small cell lung cancer progression by abolishing miR-337-3p mediated downregulation of JAK2/STAT3 signaling pathway

Background

Previous genome-wide transcriptome profiling found circ_ZNF124 was highly expressed in lung adenocarcinoma, however, the role of circ_ZNF124 in non-small cell lung cancer (NSCLC) is still unknown. The purpose of this study was to investigate the role and molecular mechanism of circ_ZNF124 in NSCLC development.

Methods

The expression of circ_ZNF124, miR-337-3p and JAK2 (Janus Kinase 2) in lung cancer cell lines and normal epithelial cells were detected by qRT-PCR (quantitative real-time PCR). siRNA was used to knockdown circ_ZNF124 expression in cells. The effects of circ_ZNF124 in NSCLC cells were determined by cell growth, cell migration, cell cycle analysis and colony formation. Bioinformatics analysis, RNA immunoprecipitation, luciferase assay and western blots were used to study the molecular mechanism of circ_ZNF124 in NSCLC.

Results

The results showed that circ_ZNF124 expression was highly upregulated in NSCLC cells than in normal epithelial cells. Knockdown of circ_ZNF124 by using siRNA significantly decreased cell growth, promoted cell cycle arrested in sub-G1 phase, impaired cell migration and colony formation. Bioinformatic analysis discovered that miR-337-3p was a direct target of circ_ZNF124. In contrast to circ_ZNF124, miR-337-3p expression was significantly downregulated in NSCLC cells. Biotin labeled circ_ZNF124 immunoprecipitation and luciferase assay showed that miR-337-3p could directly bind to and affect circ_ZNF124 activity. The regulation of circ_ZNF124 on miR-337-3p was also investigated. Further analysis showed that despite STAT3 (signal transducer and activator of transcription 3), JAK2 was also a target of miR-337-3p, overexpression of miR-337-3p greatly downregulated JAK2, STAT3 and JAK2/STAT3 downstream regulated oncogenes HIF1a (Hypoxia-inducible factor 1-alpha), BCL2 (B cell lymphoma 2) and c-FOS expression, however, the roles of miR-337-3p in JAK2/STAT3 signaling pathway were greatly inhibited in the presence of circ_ZNF124.

Conclusion

In NSCLC, highly expressed circ_ZNF124 promoted the activation of JAK2/STAT3 signaling pathway by acting as a sponge of miR-337-3p, thus promoting the occurrence and development of NSCLC. Circ_ZNF124 could be a potential biomarker or target for the treatment of NSCLC patients in the future.

KIFC1 promotes the proliferation of hepatocellular carcinoma in vitro and in vivo

Hepatocellular carcinoma (HCC) is a common type of malignant tumor worldwide with a high mortality rate. In the past 20 years, the morbidity rate of HCC has increased. Progress has been made in the clinical diagnosis and therapy for HCC. However, due to the high heterogeneity and metastasis targeted therapy for HCC exhibits great promise, and novel therapeutic targets for HCC are urgently required. Kinesin family member C1 (KIFC1) is a member of the kinesin superfamily of proteins. Previous studies have indicated a potential association between KIFC1 and cancer progression. However, the potential role of KIFC1 in the development of HCC remains unclear. The present study aimed to explore the function of KIFC1 in HCC. Immunohistochemical (IHC) assays were performed to explore the KIF15 expression levels in 74 samples of HCC and corresponding non-tumor tissues. The potential association between KIF15 expression levels and clinical features was analyzed, and the effects of KIF15 on cell proliferation of HCC were detected by colony formation and MTT assays. In addition, the proliferation-related proteins Ki67 and PCNA were detected by western blotting. The possible effects of KIF15 on tumor growth were measured in mice. The results demonstrated that a high expression level of KIFC1 was associated with poor prognosis of HCC. Further results indicated that KIFC1 promoted cell proliferation of HCC in vitro. In addition, knockdown of KIFC1 suppressed tumor formation and growth in mice. Therefore, these results provide a potential therapeutic target for the treatment of HCC.

Long non‑coding RNAs in lung cancer: Regulation patterns, biologic function and diagnosis implications (Review)

Lung cancer is the most common malignancy with the highest mortality worldwide. Emerging research has demonstrated that long non-coding RNAs (lncRNAs), a key genomic product, are commonly dysregulated in lung cancer and have significant functions in lung cancer initiation, progression and therapeutic response. lncRNAs may interact with DNA, RNA or proteins, as tumor suppressor genes or oncogenes, to regulate gene expression and cell signaling pathways. In the present review, first a summary was presented of the causal effects of dysregulated lncRNAs in lung cancer. Next, the function and specific mechanisms of lncRNA-mediated tumorigenesis, metastasis and drug resistance in lung cancer were discussed. Finally, the potential roles of lncRNAs as biomarkers for lung cancer were explored.

Hsa_circ_0001946 Inhibits Lung Cancer Progression and Mediates Cisplatin Sensitivity in Non-small Cell Lung Cancer via the Nucleotide Excision Repair Signaling Pathway

Background: Despite great advances in the diagnosis and treatment of non-small cell lung cancer (NSCLC), early diagnosis remains a challenge because patients usually have advanced lung cancer at the time they are diagnosed. The limited efficacy of conventional chemotherapy is another major problem in the treatment of NSCLC. Based on a published set of sequencing data, we find that hsa_circ_0001946 is a circRNA molecule with a significantly different expression level in three cell lines (human normal lung fibroblasts cell line MRC-5, human NSCLC cell line A549, cisplatin-resistant cell line A549/DDP), NSCLC tissues and paired adjacent normal tissues. We believe that hsa_circ_0001946 may have an effect on the progression of NSCLC and its sensitivity to cisplatin.

Methods: We focused on investigating the circular RNA, hsa_circ_0001946. RNA interference of hsa_circ_0001946 was carried out in A549 cell lines to determine the effect of reduced hsa_circ_0001946 expression on lung cancer progression and was analyzed by Cell Counting Kit-8 (CCK-8), 5-ethynyl-20-deoxyuridine, clone formation, Hoechst, wound healing, and transwell assays. The nucleotide excision repair (NER) signaling pathway was identified by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Moreover, cellular responses to cisplatin were assessed through CCK-8 and flow cytometry assays. Western blot analysis and host-cell reactivation assay were used to determine the effect of hsa_circ_0001946 on NER signaling.

Results: In this study, we found that the reduced expression of hsa_circ_0001946 promoted the viability, proliferation, migration, and invasion of NSCLC cells, as well as inhibition of cell apoptosis. Our findings suggest that hsa_circ_0001946 can affect the sensitivity of NSCLC cells to the chemotherapeutic drug cisplatin via modulation of the NER signaling pathway.

Conclusions: Our study demonstrated the role of hsa_circ_0001946 in NSCLC pathogenesis, development, and chemosensitivity, and suggests that hsa_circ_0001946 may serve as a novel biomarker for the diagnosis and prediction of platinum-based chemosensitivity in patients with NSCLC.

Lidocaine alleviates cytotoxicity-resistance in lung cancer A549/DDP cells via down-regulation of miR-21

Lidocaine (Lido) is a commonly used local anesthetic, which has been reported in various types of cells. However, the effects of Lido on lung cancer cells remain not understood. The study aimed to investigate the underlying mechanisms of Lido in the cisplatin resistance of A549/DDP cells. Different concentrations of cisplatin (0-320 µM) were used to stimulate A549 and A549/DDP cells, and cell viability and apoptosis were examined. To investigate the effect of Lido on A549/DDP cells, the optimum concentration of Lido was selected to treat A549/DDP cells, and cell viability, apoptosis, migration and invasion were then detected. The relative expression of miR-21 in A549/DDP cells or in Lido-treated A549/DDP cells was analyzed by RT-qPCR. MiR-21 mimic, inhibitor and its control were transfected into A549/DDP cells to explore the regulatory effect of miR-21 on the cisplatin resistance in A549 or A549/DDP cells. The effects of miR-21 on PTEN/PI3K/AKT and PDCD4/JNK pathways were detected by western blot. The cisplatin resistance of A549/DDP cells was higher than that of A549 cells. Lido significantly suppressed cell viability, induced apoptosis, and inhibited cell migration and invasion in A549/DDP cells. Additionally, miR-21 expression in A549/DDP was higher than that in A549 cells, and Lido significantly down-regulated miR-21 expression in A549/DDP cells. MmiR-21 inhibition exhibited the same effects as Lido on the cisplatin resistance of A549/DDP cells. Further, miR-21 suppression regulated PTEN/PI3K/AKT and PDCD4/JNK pathways in A549/DDP cells. These findings indicated that Lido alleviated the cytotoxicity resistance of A549/DDP cells via down-regulation of miR-21.

HOX cluster-embedded antisense long non-coding RNAs in lung cancer

Homeobox (HOX) genes play vital roles in embryonic development and oncogenesis. In humans, there are 39 HOX genes found in four clusters that are located on different chromosomes. The HOX clusters also contain numerous non-protein-coding RNAs, including some lncRNAs. The HOX cluster-embedded lncRNAs (HOX-lncRNAs), most notably, HOTTIP and HOTAIR play a major role in the regulation of their adjacent coding genes. Recently, most HOX-lncRNAs have been shown to impact tumorigenesis and cancer progression. Several HOX-lncRNAs, including HOTTIP, HOXA11-AS, HOTAIRM1, HOXA-AS3, HOXA10-AS, HOTAIR, and HAGLR, are dysregulated in lung cancer. Moreover, their expression levels are correlated with the clinical features of this disease. These HOX-lncRNAs regulate the proliferation, invasion, migration, and chemo-resistance of lung cancer cells through various molecular mechanisms. Although lncRNAs have received much attention lately, the functions of some HOX-lncRNAs in the development of cancer are unclear. Thus, HOX-embedded lncRNAs should be widely investigated in cancer. Here, we review the functions of HOX-lncRNAs in lung cancer.

LncRNA HOTAIR up-regulation is strongly related with lymph nodes metastasis and LAR subtype of Triple Negative Breast Cancer

Triple-negative breast cancers (TNBCs) represent a heterogeneous disease characterized by several molecular subtypes with different prognoses and responses to therapy. For a correct clinical management of TNBC patients the knowledge of the gene regulation mechanisms related to tumor progression and drug response has become fundamental.

LncRNAs regulate gene expression through various processes, including chromatin modification, transcription and post-transcription and they are emerging as important cancer biomarkers being involved in tumor pathogenesis, metastatic progression and drug resistance.

In this study we aimed to analyze the expression of the lncRNA HOTAIR, mainly involved in breast cancer disease, in a large case series of TNBC patients. We used ISH methods by a RNA probe to better define its staining in tumor tissues and its relation with clinical-pathological parameters and outcomes of patients.

Our results show that high HOTAIR expression in tumor tissues is strongly correlated with lymph nodes metastasis (LNM) (p=0.039), as reported also for other tumor types, and has a direct strong association with Androgen Receptor (AR) expression (p= 0.019).

These data confirm the prognostic role of HOTAIR in TNBC, and, its involvement in the regulation of AR pathway, suggests the possibility to establish new therapeutic strategies for AR+TNBC patients.

LncRNA HOTAIR in Tumor Microenvironment: What Role?

lncRNAs participate in many cellular processes, including regulation of gene expression at the transcriptional and post-transcriptional levels. In addition, many lncRNAs can contribute to the development of different human diseases including cancer. The tumor microenvironment (TME) plays an important role during tumor growth and metastatic progression, and most of these lncRNAs have a key function in TME intracellular signaling. Among the numerous identified lncRNAs, several experimental evidences have shown the fundamental role of the lncRNA HOTAIR in carcinogenesis, also highlighting its use as a circulating biomarker. In this review we described the contribution of HOTAIR in the TME modulation, highlighting its relation with cellular and non-cellular components during tumor evolution and progression.

Knockdown of lncRNA HOTAIR sensitizes breast cancer cells to ionizing radiation through activating miR-218

Radiotherapy is a major therapeutic strategy for breast cancer, while cancer radioresistance remains an obstacle for the successful control of the tumor. Novel radiosensitizing targets are to be developed to overcome radioresistance. Recently, long non-coding RNAs (lncRNAs) were proved to play critical roles in cancer progression. Among all, lncRNA HOTAIR was found to participate in cancer metastasis and chemoresistance. In the present study, we aimed to investigate the radiosensitizing effects of targeting HOTAIR and the underlying mechanism. Our data showed that HOTAIR (HOX antisense intergenic RNA) was up-regulated in breast cancer cells and tissues, and the expression of HOTAIR increased following irradiation. Knockdown of HOTAIR inhibited cell survival and increased cell apoptosis in response to ionizing radiation. Moreover, compared with control group, radiation induced more DNA damage and cell cycle arrest in HOTAIR knockdown cells. Finally, we found that the radiosentizing effects of HOTAIR were related to the up-regulation of miR-218, a ceRNA of HOTAIR. In conclusion, our finding showed that HOTAIR inhibition sensitizes breast cancer cells to ionizing radiation, induced severe DNA damage and activated apoptosis pathways, suggesting a possible role of HOTAIR as a novel target for breast cancer radiosensitization.

Emerging role of HOX genes and their related long noncoding RNAs in lung cancer

The transcription factor homeobox (Hox) proteins are the master regulator for the embryonic development. Studies have identified new functions for HOX in the regulation of metabolism and other primary cellular processes in humans. Their dysregulation has been observed in a variety of cancers and accumulating evidence has revealed the crucial role of HOX in cancer progression, metastasis, and resistance to therapy. HOX-related long non-coding RNAs (lncRNAs) became the most attracting lncRNAs recently that play critical role in gene regulation and chromatin dynamics in cancers. In this review, we explore the roles of HOX and their related lncRNAs in lung cancer, indicating HOX genes as potential therapeutic targets in lung cancer.

Epitranscriptomic Signatures in lncRNAs and Their Possible Roles in Cancer

In contrast to the amazing exponential growth in knowledge related to long non-coding RNAs (lncRNAs) involved in cell homeostasis or dysregulated pathological states, little is known so far about the links between the chemical modifications occurring in lncRNAs and their function. Generally, ncRNAs are post-transcriptional regulators of gene expression, but RNA modifications occurring in lncRNAs generate an additional layer of gene expression control. Chemical modifications that have been reported in correlation with lncRNAs include m⁶A, m⁵C and pseudouridylation. Up to date, several chemically modified long non-coding transcripts have been identified and associated with different pathologies, including cancers. This review presents the current level of knowledge on the most studied cancer-related lncRNAs, such as the metastasis associated lung adenocarcinoma transcript 1 (MALAT1), the Hox transcript antisense intergenic RNA (HOTAIR), or the X-inactive specific transcript (XIST), as well as more recently discovered forms, and their potential roles in different types of cancer. Understanding how these RNA modifications occur, and the correlation between lncRNA changes in structure and function, may open up new therapeutic possibilities in cancer.

Posterior HOX genes and HOTAIR expression in the proximal and distal colon cancer pathogenesis

BACKGROUND

Increasing evidences showed that the location of the primary tumor on the right (proximal) or left (distal) side of the colon have a prognostic/predictive value for colon cancer patients. However, the understanding of the molecular mechanisms that contribute to the pathogenesis in different location of colon is still unclear. Probably an important role could be played by genes that control the spatial-temporal development of bodily structures, such as HOX genes.

METHODS

The main purpose of this study was to analyze the expression of the paralogous 13 HOX genes and of the HOX regulating lncRNA HOTAIR in distal and proximal CRC cases. We have carried out a Tissue Micro Array with left and right CRC samples associated with all clinical-pathological parameters of patients. The expression of HOX genes was evaluated by immunohistochemistry and the staining of HOTAIR was performed by in situ hybridization using a specifically designed LNA probe.

RESULTS

All paralogous 13 HOX genes and HOTAIR are silent in normal tissue and expressed in CRC samples. HOXB13, HOXC13 and HOTAIR showed a statistical association with lymph nodes metastasis (p value = 0.003, p value = 0.05, p value = 0.04). HOXB13, HOXC13 and lncRNA HOTAIR are overexpressed in right CRCs samples (p value < 0 and p value = 0.021). HOTAIR is also strongly correlated with HOXB13 (p value = 0.02) and HOXC13 (p value = 0.042) expression.

CONCLUSIONS

Our data highlighted an important role of posterior HOX genes in colorectal cancer carcinogenesis. Specifically, the aberrant expression of the HOXB13, HOXC13 and HOTAIR in proximal colon cancers could add an important dowel in understanding molecular mechanisms related to tumor pathogenesis in this location.

LncRNA TATDN1 contributes to the cisplatin resistance of non-small cell lung cancer through TATDN1/miR-451/TRIM66 axis

BACKGROUND

Chemoresistance has been considered to be a major obstacle for cancer therapy clinically. Long non-coding RNAs (LncRNAs) are asscociated with the development, prognosis and drug-resistance of non-small cell lung cancer (NSCLC). Whereas, the regulatory mechanism of lncRNA TATDN1 in the cisplatin resistance of NSCLC is still not clear.

METHODS

The expression of TATDN1, miR-451 and TRIM66 in NSCLC tissues and cell lines were detected by qRT-PCR or western blot. Immunohistochemistry (IHC) assay was performed for the detection of TATDN1 expression profile. 88 patients who underwent cisplatin treatment were followed up to 60-months for the analysis of survival rate. MTT and Flow cytometry analysis were performed for the assessment of cell survival rate, proliferation and apoptosis. Bioinformatics, Dual-Luciferase reporter were employed to analyze the interaction among TATDN1, miR-451 and TRIM66. Xenograft tumor model was constructed to verify the role of TATDN1 in NSCLC treated with cisplatin (DDP) in vivo.

RESULTS

TATDN1 and TRIM66 was significantly upregulated while miR-451 was downregulated in NSCLC tissues and cell lines, especially in DDP-resistant tumor tissues and cells. Survival rates of NSCLC patients with low TATDN1 expression were improved following DDP chemotherapy. TATDN1 upregulated TRIM66 expression via sponge for miR-451. Moreover, TATDN1 knockdown improved DDP-sensitivity in NSCLC patients by regulation of miR-451/TRIM66 axis. Finally, knockdown of TATDN1 improved the sensitivity of NSCLC to DDP in vivo.

CONCLUSIONS

TATDN1 enhanced the DDP-tolerance of NSCLC cells by upregulating TRIM66 expression via sponging miR-451, hinting a novel regulatory pathway of chemoresistance in DDP-tolerant NSCLC cells and providing a potential therapeutic target for NSCLC patients with DDP-reistance.

Long noncoding RNAs as biotargets in cisplatin-based drug resistance

Since its discovery, cisplatin has become the key drug in chemotherapy for cancers. Nevertheless, chemoresistance in cancers has become an impediment in using cisplatin for cancer treatment. The resistance toward cisplatin is multifaceted as it involves multiple cellular pathways. Ever since the knowledge of long noncoding RNAs as modulators of various molecular pathways came to light, the interest in the biological function of lncRNAs as biomarkers has increased dramatically. Numerous studies have reported the link between the dysregulation of lncRNAs and drug resistance in cancers. More importantly, several lncRNAs were found to be vital in regulating cisplatin resistance. Therefore, this review summarizes the recent efforts in linking between cisplatin resistance and different types of lncRNAs.