Autophagy regulated by lncRNA HOTAIR contributes to the cisplatin-induced resistance in endometrial cancer cells

Ambra1 induces autophagy and desensitizes human prostate cancer cells to cisplatin

Prostate cancer (PCa), the second most mortal cancer from developed countries, presents a high level of chemoresistance. There is emerging evidence underscores the critical role of autophagy in the onset, progression, and chemoresistance of PCa. In the present study, we investigated the possible role of a novel autophagy regulator, activating molecule in beclin1-regulated autophagy1 (Ambra1), a novel ATG gene in the sensitivity or PCa cells to cisplatin. We explored the regulation by the Ambra1 manipulation on the induction of apoptosis and autophagy in human PCa DU145 cells in the presence of cisplatin, via up- or down-regulating Ambra1 expression. In addition, we examined the colony forming of DU145 cells post cisplatin treatment and Ambra1 manipulation. Our results demonstrated that the Ambra1 up-regulation reduced, whereas Ambra1 knockdown increased the cisplatin-induced apoptosis, caspase 3 cleavage, and poly ADP-ribose polymerase (PARP) cleavage. Interestingly, we also found significant autophagy induction in the cisplatin-treated DU145 cells, with increased autophagic vesicles, up-regulated autophagy-related markers. However, the cisplatin-induced autophagy was up-regulated by the Ambra1 overexpression or was down-regulated by the Ambra1 knockdown. In addition, the colony forming was also positively regulated by Ambra1 in DU145 cells post cisplatin treatment. In conclusion, Ambra1 negatively regulates the cisplatin-induced apoptosis and the cisplatin-mediated growth reduction in DU145 cells, in association with the Ambra1-mediated autophagy promotion. It implies that Ambra1-mediated autophagy might be an important mechanism underlining the sensitivity reduction of PCa cells.

Role of Endometrial Autophagy in Physiological and Pathophysiological Processes

Endometrium is the mucosal lining of the uterus which expressed a cyclic process of proliferation, secretion and scaling under the control of hormones secreted by the ovary, and it also plays an indispensable role in the embryo implantation, the constitution of fetal-maternal interface, and the maintaining of pregnancy. In pathophysiological conditions, the abnormality or disorder of endometrium may lead to endometrium-related diseases, such as endometriosis, endometrium hyperplasia and even endometrial carcinoma. In recent years, more and more evidence revealed that autophagy exists in both the endometrium stroma cells and epithelial cells, and the activity of autophagy is changed in the different phases of menstruation, as well as in the endometrium-related diseases. Here, we aim to review the activity level, the regulatory factors and the function of autophagy in physiological and pathophysiological endometria, and to discuss the potential value of autophagy as a target for therapies of endometrium-related diseases.

Exploring lncRNA-Mediated Regulatory Networks in Endometrial Cancer Cells and the Tumor Microenvironment: Advances and Challenges

Recent studies have revealed both the promise and challenges of targeting long non-coding RNAs (lncRNAs) to diagnose and treat endometrial cancer (EC). LncRNAs are upregulated or downregulated in ECs compared to normal tissues and their dysregulation has been linked to tumor grade, FIGO stage, the depth of myometrial invasion, lymph node metastasis and patient survival. Tumor suppressive lncRNAs (GAS5, MEG3, FER1L4 and LINC00672) and oncogenic lncRNAs (CCAT2, BANCR, NEAT1, MALAT1, H19 and Linc-RoR) have been identified as upstream modulators or downstream effectors of major signaling pathways influencing EC metastasis, including the PTEN/PI3K/AKT/mTOR, RAS/RAF/MEK/ERK, WNT/β-catenin and p53 signaling pathways. TUG1 and TDRG1 stimulate the VEGF-A pathway. PCGEM1 is implicated in activating the JAK/STAT3 pathway. Here, we present an overview of the expression pattern, prognostic value, biological function of lncRNAs in EC cells and their roles within the tumor microenvironment, focusing on the influence of lncRNAs on established EC-relevant pathways. We also describe the emerging classification of EC subtypes based on their lncRNA signature and discuss the clinical implications of lncRNAs as valuable biomarkers for EC diagnosis and potential targets for EC treatment.

The therapeutic role of long non-coding RNAs in human diseases: A focus on the recent insights into autophagy

Long non-coding RNA (lncRNA) is a class of non-coding RNA with ≥200 nucleotides in length which are involved as critical regulators in various cellular processes. LncRNAs contribute to the development and progression of many human diseases. Autophagy is a key catabolic process which helps to maintain the cellular homeostasis through the decay of damaged or unwanted proteins and dysfunctional cytoplasmic organelles. The impairment of the autophagy process has been described in numerous diseases. The autophagy possess can have either a protective or a detrimental role in cells depending on its activation status and other cellular conditions. LncRNAs have been shown to have an important function in the regulation of important biological processes such as autophagy. The relationship between lncRNAs and autophagy has been shown to be involved in the progression and possibly in the prevention of many diseases. In this review, recent findings on the regulatory roles of lncRNAs in the cell autophagy pathway, as well as their relevance to different diseases such as cardiovascular disease, cerebral ischemic stroke and cancer are highlighted.

Autophagy-Modulating Long Non-coding RNAs (LncRNAs) and Their Molecular Events in Cancer

Cancer is a global threat of health. Cancer incidence and death is also increasing continuously because of poor understanding of diseases. Although, traditional treatments (surgery, radiotherapy, and chemotherapy) are effective against primary tumors, death rate is increasing because of metastasis development where traditional treatments have failed. Autophagy is a conserved regulatory process of eliminating proteins and damaged organelles. Numerous research revealed that autophagy has dual sword mechanisms including cancer progressions and suppressions. In most of the cases, it maintains homeostasis of cancer microenvironment by providing nutritional supplement under starvation and hypoxic conditions. Over the past few decades, stunning research evidence disclosed significant roles of long non-coding RNAs (lncRNAs) in the regulation of autophagy. LncRNAs are RNA containing more than 200 nucleotides, which have no protein-coding ability but they are found to be expressed in most of the cancers. It is also proved that, autophagy-modulating lncRNAs have significant impacts on pro-survival or pro-death roles in cancers. In this review, we highlighted the recently identified autophagy-modulating lncRNAs, their signaling transduction in cancer and mechanism in cancer. This review will explore newly emerging knowledge of cancer genetics and it may provide novel targets for cancer therapy.

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.

How does estrogen work on autophagy?

Macroautophagy/autophagy is vital for intracellular quality control and homeostasis. Therefore, careful regulation of autophagy is very important. In the past 10 years, a number of studies have reported that estrogenic effectors affect autophagy. However, some results, especially those regarding the modulatory effect of 17β-estradiol (E2) on autophagy seem inconsistent. Moreover, several clinical trials are already in place combining both autophagy inducers and autophagy inhibitors with endocrine therapies for breast cancer. Not all patients experience benefit, which further confuses and complicates our understanding of the main effects of autophagy in estrogen-related cancer. In view of the importance of the crosstalk between estrogen signaling and autophagy, this review summarizes the estrogenic effectors reported to affect autophagy, subcellular distribution and translocation of estrogen receptors, autophagy-targeted transcription factors (TFs), miRNAs, and histone modifications regulated by E2. Upon stimulation with estrogen, there will always be opposing functional actions, which might occur between different receptors, receptors on TFs, TFs on autophagy genes, or even histone modifications on transcription. The huge signaling network downstream of estrogen can promote autophagy and reduce overstimulated autophagy at the same time, which allows autophagy to be regulated by estrogen in a restricted range. To help understand how the estrogenic regulation of autophagy affects cell fate, a hypothetical model is presented here. Finally, we discuss some exciting new directions in the field. We hope this might help to better understand the multiple associations between estrogen and autophagy, the pathogenic mechanisms of many estrogen-related diseases, and to design novel and efficacious therapeutics. Abbreviations: AP-1, activator protein-1; HATs, histone acetyltransferases; HDAC, histone deacetylases; HOTAIR, HOX transcript antisense RNA.

RNA interference of long noncoding RNA HOTAIR suppresses autophagy and promotes apoptosis and sensitivity to cisplatin in oral squamous cell carcinoma

BACKGROUND

Long noncoding RNA HOX transcript antisense RNA (lncRNA HOTAIR) is overexpressed in many types of human cancers and is correlated with clinical stage and lymph node metastasis in oral squamous cell carcinoma (OSCC). Autophagy, an important mechanism of self-protection, plays vital roles in adapting to hypoxia, tolerating external stimulation, and inducing chemotherapy resistance in OSCC cells. This study aims to investigate the effect of HOTAIR on autophagy, apoptosis, and invasion of OSCC cells.

METHODS

HOTAIR expression in OSCC cells was knocked down by small RNA interference. Transmission electron microscope, Western blot, and flow cytometry assay were used to detect the level of autophagy and apoptosis. OSCC cells were medicated with cisplatin, and median lethal dose (LD50) was performed to evaluate the effect on chemosensitivity of HOTAIR.

RESULTS

After HOTAIR silence, autophagy was inhibited with the downregulated expression of MAP1LC3B (microtubule-associated protein 1 light chain 3B), beclin1, and autophagy-related gene (ATG) 3 and ATG7. The expressions of mTOR increased. Proliferation, migration, and invasion of OSCC cells were suppressed. Furthermore, apoptosis rate was enhanced, and the sensitivity to cisplatin was promoted when compared with the negative control group.

CONCLUSION

HOTAIR acts as an oncogene in OSCC cells, and HOTAIR silence may be a potential therapeutic target for OSCC.

Modeling Endometrial Cancer: Past, Present, and Future

Endometrial cancer is the most common type of cancer of the female reproductive tract. Although prognosis is generally good for patients with low-grade and early-stage diseases, the outcomes for high-grade and metastatic/recurrent cases remain poor, since traditional chemotherapy regimens based on platinum and taxanes have limited effects. No targeted agents have been approved so far, although several new drugs have been tested without striking results in clinical trials. Over the last decades, many efforts have been made towards the establishment and development of preclinical models, aiming at recapitulating the structural and molecular determinants of the disease. Here, we present an overview of the most commonly used in vitro and in vivo models and discuss their peculiar features, describing their main applications and the value in the advancement of both fundamental and translational endometrial cancer research.

Identifying differentially expressed long non-coding RNAs in PBMCs in response to the infection of multidrug-resistant tuberculosis

Purpose

The aim of this paper was to identify differentially expressed long non-coding RNAs (lncRNAs) in peripheral blood mononuclear cells (PBMCs) influenced by the infection of multidrug-resistant tuberculosis (MDR-TB).

Materials and methods

IncRNA and mRNA expression profiles in PBMCs derived from healthy controls (HCs) and individuals with MDR-TB and drug-sensitive tuberculosis (DS-TB) were analyzed and compared by microarray assay. Six lncRNAs were randomly selected for validation by using real-time quantitative polymerase chain reaction (RT-qPCR). The biological functions and signaling pathways affected by the differentially expressed mRNAs were investigated by using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway-based approaches.

Results

Compared with the HC group, 1,429 lncRNAs (983 mRNAs) and 2,040 lncRNAs (1,407 mRNAs) were identified to be deregulated in the MDR-TB group and in the DS-TB group, respectively, and 1,511 lncRNAs and 1,047 mRNAs were identified to be differentially expressed in both MDR-TB and DS-TB groups. Between the three groups, 22 lncRNAs and 38 mRNAs were found deregulated. Most deregulated lncRNAs were from intergenic regions (~55% of the total), natural antisense to protein-coding loci (~32% of the total), or intronic antisense to protein-coding loci (~5% of the total). Significantly enriched signaling pathways regulated by the deregulated mRNAs were mainly associated with natural killer cell-mediated cytotoxicity, antigen processing and presentation, graft-vs-host disease, the transforming growth factor-β signaling pathway, and the Hippo signaling pathway.

Conclusion

This study is the first to report differentially expressed lncRNAs in PBMCs in response to MDR-TB infection. It revealed that some lncRNAs might be associated with regulating host immune response to MDR-TB infection. Further elucidation of the potential of these deregulated lncRNAs in MDR-TB and its reactivation requires further study.

MALAT1 promotes the colorectal cancer malignancy by increasing DCP1A expression and miR203 downregulation

The long non-coding RNA MALAT1 has been proved to promote the cell proliferation, drug resistance, invasion, and metastasis of colorectal cancer (CRC) in vitro and in vivo by regulating the expression of various oncogenes and their protein products. Our previous work discovered that the expression of the mRNA-decapping enzymes 1a (DCP1A) is upregulated in CRCs. However, the relationships between MALAT1 and DCP1A in the development of CRC and the underlying mechanisms are still unclear. In this study, we investigated the molecular mechanisms by which MALAT1 and DCP1A may be linked to contribute to the malignancies of CRCs. We found that DCP1A is a direct target molecule of MALAT1. Moreover, by screening the downstream genes of MALAT1, we noticed that microRNA 203(miR203), an oncogene suppressor in numerous cancers, is inversely correlated to both MALAT1 and DCP1A expressions. Following MALAT1 knockdown, we observed overexpression of miR203 accompanied with DCP1A downregulation to a level that reversed the promoted cell proliferation, invasion, and migration in vitro and in vivo, which could be restored by miR203 knockdown or DCP1A overexpression. These results proposed a new molecular mechanism of MALAT-miR203-DCP1A axis which is involved with the development and contributes to the malignancy of colorectal cancers.

Emerging role of long non-coding RNAs in cisplatin resistance

Cisplatin (CDDP) is one of the most commonly used chemotherapy drugs for the treatment of various cancers. Although platinum-based therapies are highly efficacious against rapidly proliferating malignant tumors, the development of CDDP resistance results in significant relapse as well as decreased overall survival rates, which is a significant obstacle in CDDP-based cancer therapy. Long non-coding RNAs (lncRNAs) are involved in cancer development and progression by the regulation of processes related to chromatin remodeling, transcription, and posttranscriptional processing. Emerging evidence has recently highlighted the roles of lncRNAs in the development of CDDP resistance. In this review, we discuss the roles and mechanisms of lncRNAs in CDDP chemoresistance, including changes in cellular uptake or efflux of a drug, intracellular detoxification, DNA repair, apoptosis, autophagy, cell stemness, and the related signaling pathways, aiming to provide potential lncRNA-targeted strategies for overcoming drug resistance in cancer therapy.

Non-coding RNAs: long non-coding RNAs and microRNAs in endocrine-related cancers

The human genome is 'pervasively transcribed' leading to a complex array of non-coding RNAs (ncRNAs) that far outnumber coding mRNAs. ncRNAs have regulatory roles in transcription and post-transcriptional processes as well numerous cellular functions that remain to be fully described. Best characterized of the 'expanding universe' of ncRNAs are the ~22 nucleotide microRNAs (miRNAs) that base-pair to target mRNA's 3' untranslated region within the RNA-induced silencing complex (RISC) and block translation and may stimulate mRNA transcript degradation. Long non-coding RNAs (lncRNAs) are classified as >200 nucleotides in length, but range up to several kb and are heterogeneous in genomic origin and function. lncRNAs fold into structures that interact with DNA, RNA and proteins to regulate chromatin dynamics, protein complex assembly, transcription, telomere biology and splicing. Some lncRNAs act as sponges for miRNAs and decoys for proteins. Nuclear-encoded lncRNAs can be taken up by mitochondria and lncRNAs are transcribed from mtDNA. Both miRNAs and lncRNAs are dysregulated in endocrine cancers. This review provides an overview on the current understanding of the regulation and function of selected lncRNAs and miRNAs, and their interaction, in endocrine-related cancers: breast, prostate, endometrial and thyroid.

Non-Coding RNAs and Endometrial Cancer

Non-coding RNAs (ncRNAs) are involved in the regulation of cell metabolism and neoplastic transformation. Recent studies have tried to clarify the significance of these information carriers in the genesis and progression of various cancers and their use as biomarkers for the disease; possible targets for the inhibition of growth and invasion by the neoplastic cells have been suggested. The significance of ncRNAs in lung cancer, bladder cancer, kidney cancer, and melanoma has been amply investigated with important results. Recently, the role of long non-coding RNAs (lncRNAs) has also been included in cancer studies. Studies on the relation between endometrial cancer (EC) and ncRNAs, such as small ncRNAs or micro RNAs (miRNAs), transfer RNAs (tRNAs), ribosomal RNAs (rRNAs), antisense RNAs (asRNAs), small nuclear RNAs (snRNAs), Piwi-interacting RNAs (piRNAs), small nucleolar RNAs (snoRNAs), competing endogenous RNAs (ceRNAs), lncRNAs, and long intergenic ncRNAs (lincRNAs) have been published. The recent literature produced in the last three years was extracted from PubMed by two independent readers, which was then selected for the possible relation between ncRNAs, oncogenesis in general, and EC in particular.

Long noncoding RNA HOTAIR mediates the estrogen-induced metastasis of endometrial cancer cells via the miR-646/NPM1 axis

LncRNA homeobox (HOX) transcript antisense intergenic RNA (HOTAIR) has been confirmed to be involved in the tumorigenic progression of endometrial carcinoma (EC). However, the molecular mechanisms of HOTAIR in EC are not fully elucidated. The expression of HOTAIR and miR-646 in human EC tissues was determined by qRT-PCR. The effect of miR-646 on EC cells was assessed by the cell viability, migration, and invasion using CCK-8 assays and transwell assays. RNA-binding protein immunoprecipitation assays and RNA pull-down assays were performed to explore the interaction between HOTAIR and miR-646. The regulation of miR-646 on nucleophosmin 1 (NPM1) was tested using luciferase reporter assays. MiR-646 expression was significantly decreased both in human EC tissues ( n = 23) and cell lines (Ishikawa and HEC-1-A) compared with the control. Moreover, miR-646 expression was negatively related to HOTAIR in human EC tissues ( n = 23). Our results also showed that miR-646 overexpression considerably attenuated the E2-promoted viability, migration, and invasion of Ishikawa and HEC-1-A cells in vitro. In addition, HOTAIR was confirmed to regulate the viability, migration, and invasion of EC cells through negative regulating miR-646. More importantly, we also demonstrated that NPM1 was the target of miR-646, and HOTAIR promoted NPM1 expression through interacting with miR-646 in EC cells. Taken together, our findings presented that HOTAIR could regulate NPM1 via interacting with miR-646, thereby governing the viability, migration, and invasion of EC cells.

Targetable long non-coding RNAs in cancer treatments

Aberrant expression of many long non-coding RNAs has been observed in various types of cancer, implicating their crucial roles in tumorigenesis and cancer progression. Emerging knowledge with regard to the critical physiological and pathological roles of long non-coding RNAs in cancers makes them potential targets in cancer treatments. In this review, we present a summary of the relatively well studied long non-coding RNAs that are involved in oncogenesis and outline their functions and functional mechanisms. Recent findings that may be utilized in therapeutic intervention are also highlighted. With the fast development in nucleic acid-based therapeutic reagents that can target disease associated RNAs, lncRNAs should be explored as potential targets in cancer treatments.

MiR-361-5p suppresses chemoresistance of gastric cancer cells by targeting FOXM1 via the PI3K/Akt/mTOR pathway

Gastric cancer is a prevalent cancer and chemotherapy is a main treatment for patients. Docetaxel is commonly used as a chemotherapeutic drug for gastric cancer patients. With the increasing emergence of docetaxel resistance, exploring the mechanism of chemoresistance may improve prognosis of patients. In this study, we found that overexpressed miR-361-5p suppressed chemoresistance to docetaxel of gastric cancer cells (SGC-7901, MKN-28) by decreasing IC₅₀ values of docetaxel while increasing cell apoptosis rate, especially in docetaxel resistant SGC-7901 cells. Further researches revealed that overexpressed miR-361-5p inhibited chemoresistance through inhibiting autophagy with a characteristic of declined number of LC3⁺ puncta, decreased expression of Beclin-1 and the ratio of LC3 II/I and increased expression of p62. Bioinformatics study and Luciferase reporter assay indicated that FOXM1 was a target of miR-361-5p and FOXM1 was negatively regulated by miR-361-5p in gastric cancer. Simultaneously, overexpression of FOXM1 counteracted the inhibitory effects of miR-361-5p on chemoresistance of gastric cancer cells through activating autophagy, further certifying the targeting relationship between the two. Moreover, overexpressed miR-361-5p activated the PI3K/Akt/mTOR pathway. The adding of PI3K inhibitor LY294002 played an opposite role to miR-361-5p mimic by inducing autophagy and chemoresistance to docetaxel of gastric cancer cells compared with docetaxel + miR-361-5p mimic group, indicating that miR-361-5p suppressed autophagy-induced chemoresistance via the PI3K/Akt/mTOR pathway in gastric cancer cells. In conclusion, we found that miR-361-5p suppressed autophagy-induced chemoresistance of gastric cancer cells through targeting FOXM1 via the PI3K/Akt/mTOR pathway, providing a foundation for the mechanism research and treatment of gastric cancer.

The Long Noncoding RNA HOTAIR in Breast Cancer: Does Autophagy Play a Role?

HOTAIR (HOX transcript antisense RNA) plays a critical role in chromatin dynamics through the interaction with histone modifiers resulting in transcriptional gene silencing. The promoter of the HOTAIR gene contains multiple estrogen response elements (EREs) and is transcriptionally activated by estradiol in estrogen receptor-positive breast cancer cells. HOTAIR competes with BRCA1, a critical protein in breast cancer and is a critical regulator of genes involved in epithelial-to-mesenchymal transition. It mediates an oncogenic action of c-Myc, essential for breast carcinogenesis. The carcinogenic action of HOTAIR was confirmed in breast cancer stem-like cells, in which it was essential for self-renewal and proliferation. Several miRNAs regulate the expression of HOTAIR and HOTAIR interacts with many miRNAs to support cancer transformation. Many studies point at miR-34a as a major component of HOTAIR–miRNAs–cancer cross-talk. The most important role of HOTAIR can be attributed to cancer progression as its overexpression stimulates invasion and metastasis. HOTAIR can regulate autophagy, important for breast cancer cells survival, through the interaction with miRNAs specific for autophagy genes and directly with these genes. The role of HOTAIR-mediated autophagy in breast cancer progression can be underlined by its interaction with matrix metalloproteinases, essential for cancer invasion, and β-catenin can be important for this interaction. Therefore, there are several mechanisms of the interplay between HOTAIR and autophagy important for breast cancer, but further studies are needed to determine more details of this interplay.