Aberrant allele-switch imprinting of a novel IGF1R intragenic antisense non-coding RNA in breast cancers

Downregulation of IRAIN long non-coding RNA predicts unfavourable clinical outcome in acute myeloid leukaemia patients

BACKGROUND

Although it has been shown that the long non-coding RNA (lncRNA) insulin-like growth factor type 1 receptor (IGF1R) antisense imprinted non-protein coding RNA (IRAIN) is downregulated in leukaemia cell lines, its usefulness as a prognostic marker in acute myeloid leukaemia (AML) has not yet been thoroughly investigated. Here, we sought to determine whether the expression of IRAIN is associated with clinical outcome of AML patients.

SUBJECTS & METHODS

Using quantitative real-time polymerase chain reaction (qRT-PCR), IRAIN expression levels were assessed in peripheral blood leukocyte samples from 150 patients with AML and 50 healthy controls. Analysis was done on the relationship between IRAIN expression and clinical outcomes in AML patients.

RESULTS

When compared to healthy controls, IRAIN expression was markedly reduced in AML patients (P = 0.019). IRAIN expression could distinguish French-American-British (FAB) subtypes of AML (P = 0.024). Low IRAIN expression status was associated with shorter event-free survival (EFS) in the non-t(15;17) cytogenetically abnormal AML subset (P = 0.004). IRAIN downregulation was identified as an independent adverse prognostic marker for complete remission (CR) not only in the in the non-t(15;17) cytogenetically abnormal AML subset (P = 0.006) but also in the AML-M4/M5 subgroup (P = 0.033).

CONCLUSION

Aberrantly low IRAIN expression is closely associated with lower CR rates in AML patients, particularly in non-t(15;17) cytogenetically abnormal AML and M4/M5 AML, suggesting that the determination of IRAIN expression level at diagnosis provides valuable prognostic information, serves as a promising biomarker for evaluating treatment response, and helps predicting clinical outcome of AML patients.

HULC targets the IGF1R-PI3K-AKT axis in trans to promote breast cancer metastasis and cisplatin resistance

Insulin-like growth factor I receptor (IGF1R) is frequently upregulated in breast cancer. Due to its intrinsic tyrosine kinase activity, aberrant activation of the IGF1R signaling axis may enhance tumor cell proliferation and cancer stemness, causing tumor relapse, metastasis and resistance to chemotherapy. We utilized a chromatin RNA in situ reverse transcription (CRIST) approach to characterize molecular factors that regulate the IGF1R network. We identified lncRNA HULC (Highly Upregulated in Liver Cancer) as a key trans-regulator of IGF1R in breast cancer cells. Loss of HULC suppressed the expression of IGF1R and the activation of its downstream PI3K/AKT pathway, while HULC overexpression activated the axis in breast cancer cells. Using a transcription-associated trap (RAT) assay, we demonstrated that HULC functioned as a nuclear lncRNA and epigenetically activated IGF1R by directly binding to the intragenic regulatory elements of the gene, orchestrating intrachromosomal interactions, and promoting histone H3K9 acetylation. The activated HULC-IGF1R/PI3K/AKT pathway mediated tumor resistance to cisplatin through the increased expression of cancer stemness markers, including NANOG, SOX2, OCT4, CD44 and ALDH1A1. In immunodeficient mice, stimulation of the HULC-IGF1R pathway promoted tumor metastasis. These data suggest that HULC may be a new epigenetic target for IGF1R axis-targeted therapeutic intervention.

Environmentally sensitive hotspots in the methylome of the early human embryo

In humans, DNA methylation marks inherited from gametes are largely erased following fertilisation, prior to construction of the embryonic methylome. Exploiting a natural experiment of seasonal variation including changes in diet and nutritional status in rural Gambia, we analysed three datasets covering two independent child cohorts and identified 259 CpGs showing consistent associations between season of conception (SoC) and DNA methylation. SoC effects were most apparent in early infancy, with evidence of attenuation by mid-childhood. SoC-associated CpGs were enriched for metastable epialleles, parent-of-origin-specific methylation and germline differentially methylated regions, supporting a periconceptional environmental influence. Many SoC-associated CpGs overlapped enhancers or sites of active transcription in H1 embryonic stem cells and fetal tissues. Half were influenced but not determined by measured genetic variants that were independent of SoC. Environmental 'hotspots' providing a record of environmental influence at periconception constitute a valuable resource for investigating epigenetic mechanisms linking early exposures to lifelong health and disease.

Insulin Resistance and Cancer: In Search for a Causal Link

Insulin resistance (IR) is a condition which refers to individuals whose cells and tissues become insensitive to the peptide hormone, insulin. Over the recent years, a wealth of data has made it clear that a synergistic relationship exists between IR, type 2 diabetes mellitus, and cancer. Although the underlying mechanism(s) for this association remain unclear, it is well established that hyperinsulinemia, a hallmark of IR, may play a role in tumorigenesis. On the other hand, IR is strongly associated with visceral adiposity dysfunction and systemic inflammation, two conditions which favor the establishment of a pro-tumorigenic environment. Similarly, epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNA, in IR states, have been often associated with tumorigenesis in numerous types of human cancer. In addition to these observations, it is also broadly accepted that gut microbiota may play an intriguing role in the development of IR-related diseases, including type 2 diabetes and cancer, whereas potential chemopreventive properties have been attributed to some of the most commonly used antidiabetic medications. Herein we provide a concise overview of the most recent literature in this field and discuss how different but interrelated molecular pathways may impact on tumor development.

Aberrant allelic-switch of antisense lncRNA IRAIN may be an early diagnostic marker in laryngeal cancer

Laryngeal carcinoma is a common head and neck malignancy, however, the molecular mechanism of the disease has not yet been elucidated. The present study aimed to investigate the role of IGF1R antisense imprinted non-protein coding RNA (IRAIN) long non-coding (lnc)RNA in laryngeal carcinoma. In total, specimens of healthy pharynx tissue from 6 healthy individuals, carcinoma tissue and paracancerous tissue from 37 patients with laryngeal carcinoma were used in this study. The single nucleotide polymorphism (SNP) rs8034564 was used to distinguish the two parental alleles of IRAIN. DNA and RNA were extracted from tissue specimens and the IRAIN allelic gene was sequenced. Reverse transcription-quantitative PCR was used to determine the expression levels of IRAIN and Insulin-like growth factor 1 receptor (IGF1R) in laryngeal carcinoma and paracancerous tissue. Bisulfite genomic sequencing was used to determine IRAIN promoter DNA methylation status in laryngeal carcinoma tissue. The expression of IRAIN was di-allelic in healthy pharynx tissue, laryngeal carcinoma tissue and paracancerous tissue. Moreover, IRAIN expression in laryngeal carcinoma tissue was lower compared with paracancerous tissue (P<0.05). IRAIN expression was not associated with age, histological type, tumor stage and grade and lymph node metastasis. IRAIN allelic expression imbalance was present in laryngeal carcinoma and paracancerous tissue, but not in healthy pharynx tissue. SNP analysis (rs8034564) indicated there was an allelic-switch of the two parental alleles. Furthermore, epigenetic analysis revealed no extensive DNA methylation of CpG islands in the IRAIN gene promoter of laryngeal carcinoma. Therefore, it was suggested that IRAIN allele was non-imprinted in laryngeal carcinoma and healthy pharynx tissue. It was also demonstrated that IRAIN may be a potential tumor suppressor in laryngeal carcinoma, and that DNA methylation is not involved in the regulation of IRAIN gene immobilization in laryngeal carcinoma tissue. Thus, detection of IRAIN allelic expression imbalance and aberrant allele-switch may serve as an early diagnostic marker of laryngeal carcinoma.

Critical roles of long noncoding RNAs in breast cancer

Breast cancer is a major clinical challenge that affects a wide range of the female population and heavily burdens the health system. In the past few decades, attempts have been made to understand the etiology of breast cancer, possible environmental risk factors, and the genetic predispositions, pathogenesis, and molecular aberrations involved in the process. Studies have shown that breast cancer is a heterogeneous entity; each subtype has its specific set of aberrations in different cell signaling pathways, such as Notch, Wnt/β-catenin, transforming growth factor-β, and mitogen-activated protein kinase pathways. One novel group of molecules that have been shown to be inducted in the regulation of multiple cell signaling pathways is the long noncoding RNAs (lncRNAs). These molecules have important implications in the regulation of multiple signaling pathways by interacting with various genes, affecting the transcription process, and finally, playing roles in posttranslational control of these genes. There is growing evidence that lncRNAs are involved in the process of breast cancer formation by effecting the aforementioned signaling pathways, and that this involvement can have significant diagnostic and prognostic values in clinical contexts. The present review aims to elicit the significance of lncRNAs in the regulation of cell signaling pathways, and the resulting changes in cell survival, proliferation, and invasion, which are the hallmarks of breast cancer.

Non-Coding RNAs in IGF-1R Signaling Regulation: The Underlying Pathophysiological Link between Diabetes and Cancer

The intricate molecular network shared between diabetes mellitus (DM) and cancer has been broadly understood. DM has been associated with several hormone-dependent malignancies, including breast, pancreatic, and colorectal cancer (CRC). Insulin resistance, hyperglycemia, and inflammation are the main pathophysiological mechanisms linking DM to cancer. Non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), are widely appreciated as pervasive regulators of gene expression, governing the evolution of metabolic disorders, including DM and cancer. The ways ncRNAs affect the development of DM complicated with cancer have only started to be revealed in recent years. Insulin-like growth factor 1 receptor (IGF-1R) signaling is a master regulator of pathophysiological processes directing DM and cancer. In this review, we briefly summarize a number of well-known miRNAs and lncRNAs that regulate the IGF-1R in DM and cancer, respectively, and further discuss the potential underlying molecular pathogenesis of this disease association.

Long noncoding RNA IRAIN acts as tumor suppressor via miR-125b in multiple myeloma

Long noncoding RNAs (lncRNAs) are aberrantly expressed in a variety of cancer types. The lncRNA IGF1R antisense imprinted non-protein coding RNA (IRAIN) is associated with various cancer types, yet the role of IRAIN in multiple myeloma (MM) progression remains unclear. In the present study it was identified that IRAIN may act as a tumor suppressor in MM, whilst microRNA (miR)-125b may promote tumorigenesis. Downregulation of IRAIN significantly increased the expression of miR-125b. Furthermore, by using dual-luciferase reporter assays, IRAIN was identified as a target of miR-125b. Knockdown of IRAIN promoted MM cell proliferation in vitro. Thus, expression levels of IRAIN may be used to predict the clinical prognosis of patients with MM and may be a novel therapeutic target for treating MM.

A novel FLI1 exonic circular RNA promotes metastasis in breast cancer by coordinately regulating TET1 and DNMT1

Background

Friend leukemia virus integration 1 (FLI1), an ETS transcription factor family member, acts as an oncogenic driver in hematological malignancies and promotes tumor growth in solid tumors. However, little is known about the mechanisms underlying the activation of this proto-oncogene in tumors.

Results

Immunohistochemical staining showed that FLI1 is aberrantly overexpressed in advanced stage and metastatic breast cancers. Using a CRISPR Cas9-guided immunoprecipitation assay, we identify a circular RNA in the FLI1 promoter chromatin complex, consisting of FLI1 exons 4-2-3, referred to as FECR1.Overexpression of FECR1 enhances invasiveness of MDA-MB231 breast cancer cells. Notably, FECR1 utilizes a positive feedback mechanism to activate FLI1 by inducing DNA hypomethylation in CpG islands of the promoter. FECR1 binds to the FLI1 promoter in cis and recruits TET1, a demethylase that is actively involved in DNA demethylation. FECR1 also binds to and downregulates in trans DNMT1, a methyltransferase that is essential for the maintenance of DNA methylation.

Conclusions

These data suggest that FECR1 circular RNA acts as an upstream regulator to control breast cancer tumor growth by coordinating the regulation of DNA methylating and demethylating enzymes. Thus, FLI1 drives tumor metastasis not only through the canonical oncoprotein pathway, but also by using epigenetic mechanisms mediated by its exonic circular RNA.

Electronic supplementary material

The online version of this article (10.1186/s13059-018-1594-y) contains supplementary material, which is available to authorized users.

Parent of origin gene expression in a founder population identifies two new candidate imprinted genes at known imprinted regions

Genomic imprinting is the phenomena that leads to silencing of one copy of a gene inherited from a specific parent. Mutations in imprinted regions have been involved in diseases showing parent of origin effects. Identifying genes with evidence of parent of origin expression patterns in family studies allows the detection of more subtle imprinting. Here, we use allele specific expression in lymphoblastoid cell lines from 306 Hutterites related in a single pedigree to provide formal evidence for parent of origin effects. We take advantage of phased genotype data to assign parent of origin to RNA-seq reads in individuals with gene expression data. Our approach identified known imprinted genes, two putative novel imprinted genes, PXDC1 and PWAR6, and 14 genes with asymmetrical parent of origin gene expression. We used gene expression in peripheral blood leukocytes (PBL) to validate our findings, and then confirmed imprinting control regions (ICRs) using DNA methylation levels in the PBLs.

Long noncoding RNAs and their epigenetic function in hematological diseases

Recent discoveries demonstrate the importance of long noncoding RNA (lncRNA) in the regulation of multiple major processes impacting development, differentiation, and metastasis of hematological diseases through epigenetic mechanisms. In contrast to genetic changes, epigenetic modification does not modify genes but is frequently reversible, thus providing opportunities for targeted treatment using specific inhibitors. In this review, we will summarize the function and epigenetic mechanism of lncRNA in malignant hematologic diseases.

Targeting the IGF1R Pathway in Breast Cancer Using Antisense lncRNA-Mediated Promoter cis Competition

Aberrant insulin-like growth factor I receptor (IGF1R) signaling pathway serves as a well-established target for cancer drug therapy. The intragenic antisense long noncoding RNA (lncRNA) IRAIN, a putative tumor suppressor, is downregulated in breast cancer cells, while IGF1R is overexpressed, leading to an abnormal IGF1R/IRAIN ratio that promotes tumor growth. To precisely target this pathway, we developed an “antisense lncRNA-mediated intragenic cis competition” (ALIC) approach to therapeutically correct the elevated IGF1R/IRAIN bias in breast cancer cells. We used CRISPR-Cas9 gene editing to target the weak promoter of IRAIN antisense lncRNA and showed that in targeted clones, intragenic activation of the antisense lncRNA potently competed in cis with the promoter of the IGF1R sense mRNA. Notably, the normalization of IGF1R/IRAIN transcription inhibited the IGF1R signaling pathway in breast cancer cells, decreasing cell proliferation, tumor sphere formation, migration, and invasion. Using “nuclear RNA reverse transcription-associated trap” sequencing, we uncovered an IRAIN lncRNA-specific interactome containing gene targets involved in cell metastasis, signaling pathways, and cell immortalization. These data suggest that aberrantly upregulated IGF1R in breast cancer cells can be precisely targeted by cis transcription competition, thus providing a useful strategy to target disease genes in the development of novel precision medicine therapies.

Decitabine Inhibits Gamma Delta T Cell Cytotoxicity by Promoting KIR2DL2/3 Expression

Gamma delta (γδ) T cells, which possess potent cytotoxicity against a wide range of cancer cells, have become a potential avenue for adoptive immunotherapy. Decitabine (DAC) has been reported to enhance the immunogenicity of tumor cells, thereby reinstating endogenous immune recognition and tumor lysis. However, DAC has also been demonstrated to have direct effects on immune cells. In this study, we report that DAC inhibits γδ T cell proliferation. In addition, DAC increases the number of KIR2DL2/3-positive γδ T cells, which are less cytotoxic than the KIR2DL2/3-negative γδ T cells. We found that DAC upregulated KIR2DL2/3 expression in KIR2DL2/3-negative γδ T cells by inhibiting KIR2DL2/3 promoter methylation, which enhances the binding of KIR2DL2/3 promoter to Sp-1 and activates KIR2DL2/3 gene expression. Our data demonstrated that DAC can inhibit the function of human γδ T cells at both cellular and molecular levels, which confirms and extrapolates the results of previous studies showing that DAC can negatively regulate the function of NK cells and αβ T cells of the immune system.

Long non-coding RNA as potential biomarkers in non-small-cell lung cancer: What do we know so far?

Non-small-cell lung cancer (NSCLC) remains one of the most frequent types of lung cancer characterized by its local advancement at diagnosis. Therefore, identification of new prognostic biomarkers has become one of the most important issue in NSCLC therapy. It is now well understood that genetic and epigenetic alterations are responsible for NSCLC development. Moreover, it has been recently revealed that the non-protein coding regions of the genome may serve as a template for transcription of various type of RNAs, collectively referred to as non-coding RNAs. Non-coding RNAs, including long non-coding RNAs (lncRNAs) are involved in multiple cellular processes and it has been suggested that aberrant expression of lncRNAs may lead to tumour development, including NSCLC. Furthermore, some of the established risk factors for NSCLC may have an impact on expression level of several types of lncRNAs, and thus, affect the lung carcinogenesis through lncRNAs regulation. In this review, we would like to summarise the to-date knowledge about lncRNAs as potential biomarkers in NSCLC and the role of various environmental factors, such as smoking and air pollution, in development and progression of this tumour and their effect on lncRNAs expression.

Lost in translation: The 3'-UTR of IGF1R as an ancient long noncoding RNA

Background and objectives

The insulin-like growth factor (IGF) signaling system is a major arena of intragenomic conflict over embryonic growth between imprinted genes of maternal and paternal origin and the IGF type 1 receptor (IGF1R) promotes proliferation of many human cancers. The 3'-untranslated region (3'-UTR) of the mouse Igf1r mRNA is targeted by miR-675-3p derived from the imprinted H19 long noncoding RNA. We undertook a comparative sequence analysis of vertebrate IGF1R 3'-UTRs to determine the evolutionary history of miR-675 target sequences and to identify conserved features that are likely to be involved in post-transcriptional regulation of IGF1R translation.

Methodology

Sequences of IGF1R 3'-UTRs were obtained from public databases and analyzed using publicly available algorithms.

Results

A very long 3'-UTR is a conserved feature of vertebrate IGF1R mRNAs. We found that some ancient microRNAs, such as let-7 and mir-182, have predicted binding sites that are conserved between cartilaginous fish and mammals. One very conserved region is targeted by multiple, maternally expressed imprinted microRNAs that appear to have evolved more recently than the targeted sequences.

Conclusions and implications

The conserved structures we identify in the IGF1R 3'-UTR are strong candidates for regulating cell proliferation during development and carcinogenesis. These conserved structures are now targeted by multiple imprinted microRNAs. These observations emphasize the central importance of IGF signaling pathways in the mediation of intragenomic conflicts over embryonic growth and identify possible targets for therapeutic interventions in cancer.

CRISPR Cas9-guided chromatin immunoprecipitation identifies miR483 as an epigenetic modulator of IGF2 imprinting in tumors

The normally imprinted insulin-like growth factor II (IGF2) gene is aberrantly upregulated in a variety of human malignancies, yet the mechanisms underlying this dysregulation are still poorly defined. In this report, we used a CRISPR Cas9-guided chromatin immunoprecipitation assay to characterize the molecular components that participate in the control of IGF2 gene expression in human tumor cells. We found that miR483, an oncogenic intronic miRNA, binds to the most upstream imprinted IGF2 promoter, P2. Ectopic expression of miR483 induced upregulation of IGF2 expression, in parallel with an increase in tumor cell proliferation, migration, invasion, and tumor colony formation. miR483 induced loss of IGF2 imprinting by altering the epigenotype at P2, with reduction in histone H3K27 methylation and a decrease in chromatin binding of two imprinting regulatory factors, CTCF and SUZ12. This study identifies a new role for miR483 in the regulation of IGF2 gene expression through the alteration of the promoter epigenotype.

Long noncoding RNA CCAT1 polymorphisms are associated with the risk of colorectal cancer

Colorectal cancer associated transcript 1 (CCAT1) is a novel long noncoding RNA, whose overexpression is evident in both early phase of tumorigenesis and later disease stages in colorectal cancer (CRC). No study has explored the relationship between CCAT1 polymorphisms and CRC risk. In the present study, a case-control study was conducted to investigate the association between CCAT1 polymorphisms and CRC risk in Chinese population. We identified that CCAT1 rs67085638 polymorphism was associated with an increased risk of CRC (OR = 1.72, 95%CI = 1.14-2.58, P = 0.009 in heterozygote codominant model; OR = 1.67, 95%CI = 1.13-2.47, P = 0.010 in dominant model). Moreover, CCAT1 rs7013433 polymorphism was associated with late clinical stage (OR = 1.82, 95%CI = 1.16-2.86, P = 0.009 in heterozygote codominant model; OR = 1.72, 95%CI = 1.13-2.63, P = 0.012 in dominant model). Our finding proposed a link between CCAT1 polymorphisms with CRC risk as well as different clinical stages.

Low-dose bortezomib increases the expression of NKG2D and DNAM-1 ligands and enhances induced NK and γδ T cell-mediated lysis in multiple myeloma

Multiple myeloma (MM) is an incurable hematological malignancy, although bortezomib has markedly improved its outcomes. Growing clinical evidence indicates that enhancing induced natural killer (NK) or γδ T cells for infusion is useful in the treatment of MM. However, whether combination treatment with bortezomib and induced NK and γδ T cells further improves outcomes in MM, and how the treatments should be combined, remain unclear. Herein, we found that low-dose bortezomib did not suppress the viability of induced NK and γδ T cells, but did induce MM cell apoptosis. Importantly, low-dose bortezomib increased the expression of NKG2D and DNAM-1 ligands on MM cells, which sensitized the multiple myeloma cells to lysis by induced NK and γδ T cells. Our results suggested that combination treatment with low-dose bortezomib and induced NK or γδ T cells had a synergistic cytotoxic effect on MM cells. This study provided a proof of principle for the design of future trials and investigation of this combination therapeutic strategy for MM treatment.

Novel insights into chromosomal conformations in cancer

Exploring gene function is critical for understanding the complexity of life. DNA sequences and the three-dimensional organization of chromatin (chromosomal interactions) are considered enigmatic factors underlying gene function, and interactions between two distant fragments can regulate transactivation activity via mediator proteins. Thus, a series of chromosome conformation capture techniques have been developed, including chromosome conformation capture (3C), circular chromosome conformation capture (4C), chromosome conformation capture carbon copy (5C), and high-resolution chromosome conformation capture (Hi-C). The application of these techniques has expanded to various fields, but cancer remains one of the major topics. Interactions mediated by proteins or long noncoding RNAs (lncRNAs) are typically found using 4C-sequencing and chromatin interaction analysis by paired-end tag sequencing (ChIA-PET). Currently, Hi-C is used to identify chromatin loops between cancer risk-associated single-nucleotide polymorphisms (SNPs) found by genome-wide association studies (GWAS) and their target genes. Chromosomal conformations are responsible for altered gene regulation through several typical mechanisms and contribute to the biological behavior and malignancy of different tumors, particularly prostate cancer, breast cancer and hematologic neoplasms. Moreover, different subtypes may exhibit different 3D-chromosomal conformations. Thus, C-tech can be used to help diagnose cancer subtypes and alleviate cancer progression by destroying specific chromosomal conformations. Here, we review the fundamentals and improvements in chromosome conformation capture techniques and their clinical applications in cancer to provide insight for future research.

Friend leukemia virus integration 1 activates the Rho GTPase pathway and is associated with metastasis in breast cancer

Breast cancer is the most prevalent malignant disease in women worldwide. In patients with breast cancer, metastasis to distant sites directly determines the survival outcome. However, the molecular mechanism underlying metastasis in breast cancer remains to be defined. In this report, we found that Friend leukemia virus integration 1 (FLI1) proto-oncogene was differentially expressed between the aggressive MDA-MB231 and the non-aggressive MCF-7 breast cancer cells. Congruently, immunohistochemical staining of clinical samples revealed that FLI1 was overexpressed in breast cancers as compared with the adjacent tissues. The abundance of FLI1 protein was strongly correlated with the advanced stage, poor differentiation, and lymph node metastasis in breast cancer patients. Knockdown of FLI1 with small interfering RNAs significantly attenuated the potential of migration and invasion in highly metastatic human breast cancer cells. FLI1 oncoprotein activated the Rho GTPase pathway that is known to play a role in tumor metastasis. This study for the first time identifies FLI1 as a clinically and functionally important target gene of metastasis, providing a rationale for developing FLI1 inhibitors in the treatment of breast cancer.

LncRNAs and cancer

Long non-coding RNAs (lncRNAs) are a group of non-coding RNAs composed of >200 nucleotides. Recent studies have revealed that lncRNAs exert an important role in the development and progression of cancer. In this review, the involvement of the most extensively investigated lncRNAs in cancers of the digestive, respiratory, reproductive, urinary and central nervous systems are discussed. LncRNAs function via molecular and biochemical mechanisms that include cis- and trans-regulation of gene expression, epigenetic modulation in the nucleus and post-transcriptional control in the cytoplasm. Although the detailed biological functions and molecular mechanisms of the majority of lncRNAs remain to be elucidated, this review aims to provide a novel insight into the diagnosis and treatment of cancer using lncRNAs.

Long noncoding RNAs in hematopoietic malignancies

Recent years have witnessed the discovery of several classes of noncoding RNAs (ncRNAs), which are indispensable for the regulation of cellular processes. Many of these RNAs are regulatory in nature with functions in gene expression regulation such as piwi-interacting RNAs, small interfering RNAs and micro RNAs. Long noncoding RNAs (lncRNAs) comprise the most recently characterized class. LncRNAs are involved in transcriptional regulation, chromatin remodeling, imprinting, splicing, and translation, among other critical functions in the cell. Recent studies have elucidated the importance of lncRNAs in hematopoietic development. Dysregulation of lncRNA expression is a feature of various diseases and cancers, and is also seen in hematopoietic malignancies. This article focuses on lncRNAs that have been implicated in the pathogenesis of hematopoietic malignancies.

Lentiviral Vector-Mediated Complementation Restored Fetal Viability but Not Placental Hyperplasia in Plac1-Deficient Mice

The X-linked Plac1 gene is maternally expressed in trophoblast cells during placentation, and its disruption causes placental hyperplasia and intrauterine growth restriction. In contrast, Plac1 is also reported to be one of the upregulated genes in the hyperplastic placenta generated by nuclear transfer. However, the effect of overexpressed Plac1 on placental formation and function remained unaddressed. We complemented the Plac1 knockout placental dysfunction by lentiviral vector-mediated, placenta-specific Plac1 transgene expression. Whereas fetal development and the morphology of maternal blood sinuses in the labyrinth zone improved, placental hyperplasia remained, with an expanded the junctional zone that migrated and encroached into the labyrinth zone. Further experiments revealed that wild-type placenta with transgenically expressed Plac1 resulted in placental hyperplasia without the encroaching of the junctional zone. Our findings suggest that Plac1 is involved in trophoblast cell proliferation, differentiation, and migration. Its proper expression is required for normal placentation and fetal development.

Association between indel polymorphism in the promoter region of lncRNA GAS5 and the risk of hepatocellular carcinoma

The growth arrest special 5 (GAS5) is known to be involved in various cancers. However, its expression regulation remains unclear. Polymorphisms in the promoter region of GAS5 may affect its expression and be associated with cancer susceptibility. In this research, we first evaluated the association of a 5-base pair indel polymorphism (rs145204276) in the promoter region of GAS5 with hepatocelluar carcinoma (HCC) susceptibility in Chinese populations. Logistic regression analysis showed that the deletion allele of rs145204276 significantly increased the risk of HCC in two independent case control sets (1034 HCC and 1054 controls). Further genotype-phenotype association analysis revealed that the deletion allele was markedly correlated with higher expression of GAS5 in HCC tissues. The luciferase activity analysis in an in vitro reporter gene system suggested that the deletion allele improved an increased expression of GAS5 in three hepatoma cell lines. Intriguingly, overexpression of GAS5 displayed an anti-apoptosis effect in HCC cell lines, GAS5 knockdown could partially revert this anti-apoptosis effect, suggesting that GAS5 may act as a proto-oncogene in HCC, in contrast with its inhibitory role in other cancers. Further pyrosequencing revealed that the genotypes of rs145204276 were associated with methylation status of GAS5 promoter region. Taken together, our findings provided evidence that rs145204276 may contribute to hepatocarcinogenesis by affecting methylation status of the GAS5 promoter and subsequently its transcriptional activity thus serving as a potential therapy target for HCC.