8q24 Cancer risk allele associated with major metastatic risk in inflammatory breast cancer

Deciphering the molecular biology of inflammatory breast cancer through molecular characterization of patient samples and preclinical models

Inflammatory breast cancer is an aggressive subtype of breast cancer with dismal patient prognosis and a unique clinical presentation. In the past two decades, molecular profiling technologies have been used in order to gain insight into the molecular biology of IBC and to search for possible targets for treatment. Although a gene signature that accurately discriminates between IBC and nIBC patient samples and preclinical models was identified, the overall genomic and transcriptomic differences are small and ambiguous, mainly due to the limited sample sizes of the evaluated patient series and the failure to correct for confounding effects of the molecular subtypes. Nevertheless, data collected over the past 20 years by independent research groups increasingly support the existence of several IBC-specific biological characteristics. In this review, these features are classified as established, emerging and conceptual hallmarks based on the level of evidence reported in the literature. In addition, a synoptic model is proposed that integrates all hallmarks and that can explain how cancer cell intrinsic mechanisms (i.e. NF-κB activation, genomic instability, MYC-addiction, TGF-β resistance, adaptive stress response, chromatin remodeling, epithelial-to-mesenchymal transition) can contribute to the establishment of the dynamic immune microenvironment associated with IBC. It stands to reason that future research projects are needed to further refine (parts of) this model and to investigate its clinical translatability.

Single Nucleotide Polymorphisms of EXOC1, BCL2, CCAT2, and CARD8 Genes and Susceptibility to Cervical Cancer in the Northern Chinese Han Population

Cervical cancer (CC) is one of the main malignant tumors that threaten the health and lives of women around the world, and its morbidity and mortality rate ranks fourth. At present, most studies on the genetic background of CC focus on genetic polymorphisms. Single nucleotide polymorphisms (SNPs) are considered clinically as potential diagnostic and therapeutic biomarkers for a variety of tumors. Therefore, we aimed to explore the association between SNPs in different genes (EXOC1 gene, BCL2 gene, CCAT2 gene and CARD8 gene) and susceptibility to CC. This study is a case-control study based on women in northern Chinese, which included 492 women with CC and 510 healthy women. This study used multiplex PCR combined with next-generation sequencing to genotype the selected SNPs (rs13117307(C/T) in EXOC1 gene, rs2279115(C/A) in BCL2 gene, rs6983267(G/T) in CCAT2 gene and rs7248320(G/A) in CARD8 gene). The results of the study showed that there was no significant association between the four SNPs and the susceptibility to CC. However, in further stratified analysis, we found that rs13117307 and rs2279115 were significantly related to squamous cell carcinoma antigen (SCC-Ag) levels in women with CC, and rs6983267 was significantly related to the menopausal status of women with CC. Specifically, alleles T of rs13117307 and genoytpe AA of rs2279115 when SCC-Ag is greater than 1.5 ng/ml increase the risk of CC. The genotype TG/TG+TT of rs6983267 increases the risk of CC in premenopausal women. In conclusion, although we did not directly find a significant correlation between four SNPs, rs13117307 in EXOC1 gene,rs2279115 in BCL2 gene, rs6983267 in CCAT2 gene and rs7248320 in CARD8 gene, and CC susceptibility, we found that SNPs rs13117307, rs2279115, rs6983267 were associated with the clinical characteristics of several patients' CC patients. Therefore, this study provides us with new ideas for understanding CC and the diagnosis and treatment of CC in the future.

The possible role of long non-coding RNAs in recurrent miscarriage

Recurrent miscarriage (RM) is a complicated disease in reproductive medicine that impacts many families. Currently, the etiology of RM is thought to include chromosome abnormalities, reproductive tract malformations, autoimmune dysfunction, infection, and environmental factors. However, the underlying mechanisms of RM remain unknown. At present, research on long non-coding RNAs (lncRNAs) is rapidly emerging and becoming a hot research topic in epigenetic studies. Recent studies revealed that lncRNAs are strongly linked to RM and play a crucial role in epigenetic, cell cycle, cell differentiation regulation, and other life activities. This article mainly reviews the difference in lncRNA expression in patients with RM and regulation of susceptibility, endometrial receptivity, and the maternal-fetal interface. Meanwhile, the correlation between lncRNAs and RM is expounded, which provides new insights for the early diagnosis and treatment of RM.

Comparative transcriptional analyses of preclinical models and patient samples reveal MYC and RELA driven expression patterns that define the molecular landscape of IBC

Inflammatory breast cancer (IBC) is an aggressive disease for which the spectrum of preclinical models was rather limited in the past. More recently, novel cell lines and xenografts have been developed. This study evaluates the transcriptome of an extended series of IBC preclinical models and performed a comparative analysis with patient samples to determine the extent to which the current models recapitulate the molecular characteristics of IBC observed clinically. We demonstrate that the IBC preclinical models are exclusively estrogen receptor (ER)-negative and of the basal-like subtype, which reflects to some extent the predominance of these subtypes in patient samples. The IBC-specific 79-signature we previously reported was retrained and discriminated between IBC and non-IBC preclinical models, but with a relatively high rate of false positive predictions. Further analyses of gene expression profiles revealed important roles for cell proliferation, MYC transcriptional activity, and TNFɑ/NFκB in the biology of IBC. Patterns of MYC expression and transcriptional activity were further explored in patient samples, which revealed interactions with ESR1 expression that are contrasting in IBC and nIBC and notable given the comparatively poor outcomes of ER+ IBC. Our analyses also suggest important roles for NMYC, MXD3, MAX, and MLX in shaping MYC signaling in IBC. Overall, we demonstrate that the IBC preclinical models can be used to unravel cancer cell intrinsic molecular features, and thus constitute valuable research tools. Nevertheless, the current lack of ER-positive IBC models remains a major hurdle, particularly since interactions with the ER pathway appear to be relevant for IBC.

Identification and characterization of functional long noncoding RNAs in cancer

Long noncoding RNAs (lncRNAs) have emerged as key regulators in a variety of cellular processes that influence disease states. In particular, many lncRNAs are genetically or epigenetically deregulated in cancer. However, whether lncRNA alterations are passengers acquired during cancer progression or can act as tumorigenic drivers is a topic of ongoing investigation. In this review, we examine the current methodologies underlying the identification of cancer-associated lncRNAs and highlight important considerations for evaluating their biological significance as cancer drivers.

Quantitative hormone receptor (HR) expression and gene expression analysis in HR+ inflammatory breast cancer (IBC) vs non-IBC

Background

The purpose of this study was to determine the prognostic role of hormone receptor (HR) on inflammatory breast cancer (IBC) to elucidate its aggressive biological behavior.

Methods

We evaluated the expression of estrogen receptor (ER) and progesterone receptor (PR) by immunohistochemical staining and determined the predictive and prognostic role of HR expression on 189 patients with HR+/HER2– IBC and 677 patients with HR+/HER2– stage III non-IBC. Furthermore, we performed gene expression (GE) analyses on 137 patients with HR+/HER2– IBC and 252 patients with HR+/HER2– non-IBC to detect genes that are specifically overexpressed in IBC.

Results

The expression of ER% was significantly associated with longer distant disease-free survival and overall survival. However, there was no significant relationship between ER% and neoadjuvant chemotherapy outcome. In the GE study, 84 genes were identified as significantly distinguishing HR+ IBC from non-IBC. Among the top 15 canonical pathways expressed in IBC, the ERK/MAPK, PDGF, insulin receptor, and IL-7 signaling pathways were associated with the ER signaling pathway. Upregulation of the MYC gene was observed in three of these four pathways. Furthermore, HR+/HER2– IBC had significantly higher MYC amplification, and the genetic alteration was associated with poor survival outcome.

Conclusions

Higher ER expression was significantly associated with improved survival in both HR+/HER2– IBC and HR+/HER2– stage III non-IBC patients. HR+/HER2– IBC had several activated pathways with MYC upregulation, and the genetic alteration was associated with poor survival outcome. The results indicate that MYC may be a key gene for understanding the biology of HR+/HER2– IBC.

Inflammatory breast cancer cells are characterized by abrogated TGFβ1-dependent cell motility and SMAD3 activity

PURPOSE

Inflammatory breast cancer (IBC) is an aggressive form of breast cancer with elevated metastatic potential, characterized by tumor emboli in dermal and parenchymal lymph vessels. This study has investigated the hypothesis that TGFβ signaling is implicated in the molecular biology of IBC.

METHODS

TGFβ1-induced cell motility and gene expression patterns were investigated in three IBC and three non-IBC (nIBC) cell lines. Tissue samples from IBC and nIBC patients were investigated for the expression of nuclear SMAD2, SMAD3, and SMAD4. SMAD protein levels were related to gene expression data.

RESULTS

TGFβ1-induced cell motility was strongly abrogated in IBC cells (P = 0.003). Genes differentially expressed between IBC and nIBC cells post TGFβ1 exposure revealed attenuated expression of SMAD3 transcriptional regulators, but overexpression of MYC target genes in IBC. IBC patient samples demonstrated a near absence of SMAD3 and -4 expression in the primary tumor compared to nIBC patient samples (P < 0.001) and a further reduction of staining intensity in tumor emboli. Integration of gene and protein expression data revealed that a substantial fraction of the IBC signature genes correlated with SMAD3 and these genes are indicative of attenuated SMAD3 signaling in IBC.

CONCLUSION

We demonstrate attenuated SMAD3 transcriptional activity and SMAD protein expression in IBC, together with obliterated TGFβ1-induced IBC cell motility. The further reduction of nuclear SMAD expression levels in tumor emboli suggests that the activity of these transcription factors is involved in the metastatic dissemination of IBC cells, possibly by enabling collective invasion after partial EMT.

Variants in the 8q24 region associated with risk of breast cancer: Systematic research synopsis and meta-analysis

Breast cancer is a molecularly heterogeneous disorder associated with high lethal malignant tumors among women worldwide. Genetic factors play an important role in breast cancer development. Several single nucleotide polymorphisms in the 8q24 region associated with risk of breast cancer have been identified. Fifteen studies including 32,955 cases and 43,716 controls were collected to conduct a meta-analysis to evaluate the associations between variants in 8q24 region and risk of breast cancer. Our study showed that only rs13281615 is associated with breast cancer risk in this large-scale research synopsis and meta-analysis. Further studies are needed to explore the role of the 8q24 variants in the development of breast cancer.

Psychological Consequences of Breast Cancer in Iran: A Meta-Analysis

BACKGROUND

Breast cancer is known as one of the most common cancers among women and has severe psychological effects. This study aimed to identify the psychological consequences of breast cancer in previous studies based on meta-analysis.

METHODS

Meta-analytic procedures were conducted by Prisma guidelines. A literature search was conducted by using following electronic databases including scientific information databases (SID), Magiran, Medlib, ScienceDirect, PubMed, Google Scholar, Web of Science, Scopus, CINAHL and Medline from 1991 through 2017 regarding the psychological consequences associated with breast cancer in Iran. The content of all articles was evaluated by the Prisma checklist and analyzed meta-analysis in CMA software.

RESULTS

The final synthesis was carried out on 56 quantitative studies. Considering the findings of meta-analysis of the psychological consequences of patients with breast cancer in seven classes, anxiety (ES=-0.76), body image (ES=0.199), coping strategies (ES= 0.214), depression (ES=-0.700), fatigue (ES=0.322), quality of life (ES= 0.428), and sexual function (ES=0.355) were achieved.

CONCLUSION

Based on the results of the high level of psychological consequences of breast cancer in women with breast cancer, it is necessary to formulate appropriate therapeutic protocols in order to adjust the psychological consequences.

The lncRNA CCAT2 rs6983267 G allele is associated with decreased susceptibility to recurrent miscarriage

Genetics might play various roles in susceptibility to recurrent miscarriage, and previous studies suggest that some gene polymorphisms might be associated with abortion and breast cancer onset. Colon cancer-associated transcript 2 (CCAT2) is a novel long noncoding RNA (lncRNA) transcript that might be correlated with susceptibility to multiple cancers, including breast cancer. However, whether lncRNA CCAT2 polymorphisms are related to susceptibility to recurrent miscarriage is unclear. We genotyped two lncRNA CCAT2 polymorphisms (rs6983267 and rs3843549) in 248 patients with recurrent miscarriage and 392 controls through a TaqMan real-time polymerase chain reaction assay, and the strength of each association was evaluated via 95% confidence intervals (CIs) and odds ratios (ORs). Our results showed that the rs6983267 G allele in lncRNA CCAT2 was associated with decreased susceptibility to recurrent miscarriage (TG vs. TT: adjusted OR = 0.603; 95% CI = 0.420-0.866; p = 0.0062; GG/TG vs. TT: adjusted OR = 0.620; 95% CI = 0.441-0.873; p = 0.0061). The combined analysis of the two protective polymorphisms (rs3843549 AA and rs6983267 TG/GG) revealed that individuals with two unfavorable alleles exhibited a lower risk of recurrent miscarriage than those with no or only one unfavorable allele (adjusted OR = 0.531; 95% CI = 0.382-0.739). Moreover, the decreased risk associated with the two protective alleles was most obvious in women aged less than 35 years (OR = 0.551; 95% CI = 0.378-0.8803; p = 0.0019) and in women with two to three miscarriages (adjusted OR = 0.466; 95% CI = 0.318-0.683; p < 0.0001). In conclusion, our study indicates that the rs6983267G allele might contribute to a decreased risk of recurrent miscarriage in the South Chinese population.

KATZLGO: Large-Scale Prediction of LncRNA Functions by Using the KATZ Measure Based on Multiple Networks

Aggregating evidences have shown that long non-coding RNAs (lncRNAs) generally play key roles in cellular biological processes such as epigenetic regulation, gene expression regulation at transcriptional and post-transcriptional levels, cell differentiation, and others. However, most lncRNAs have not been functionally characterized. There is an urgent need to develop computational approaches for function annotation of increasing available lncRNAs. In this article, we propose a global network-based method, KATZLGO, to predict the functions of human lncRNAs at large scale. A global network is constructed by integrating three heterogeneous networks: lncRNA-lncRNA similarity network, lncRNA-protein association network, and protein-protein interaction network. The KATZ measure is then employed to calculate similarities between lncRNAs and proteins in the global network. We annotate lncRNAs with Gene Ontology (GO) terms of their neighboring protein-coding genes based on the KATZ similarity scores. The performance of KATZLGO is evaluated on a manually annotated lncRNA benchmark and a protein-coding gene benchmark with known function annotations. KATZLGO significantly outperforms state-of-the-art computational method both in maximum F-measure and coverage. Furthermore, we apply KATZLGO to predict functions of human lncRNAs and successfully map 12,318 human lncRNA genes to GO terms.

Landscape of SNPs-mediated lncRNA structural variations and their implication in human complex diseases

An increasing number of functional studies shows that long noncoding RNAs (lncRNAs) are involved in many aspects of cellular physiology and fulfills a wide variety of regulatory roles at almost every stage of gene expression. A major feature of lncRNAs is the highly folded modular domains in transcripts. With improved modeling and definition, it is now feasible to explore and gain novel insights into the structural-functional relationship of lncRNAs and their association with complex human diseases. In this study, we utilized an automatic computational pipeline to scan lncRNA architecture at the genome-wide scale and to obtain a landscape of functional domains. An accurate alignment algorithm was performed to identify 40 triple pairs between single-nucleotide polymorphisms (SNPs), lncRNAs and diseases. In order to detect the potential contribution of a lncRNA's modular character, we estimated and evaluated structural rearrangements, which were derived from disease-associated SNPs. In addition, we focused on annotating and comparing the global and local heterogeneity of the wild-type and mutant lncRNAs. Assessing lncRNA architecture has yielded how variations in structured regions impact the molecular mechanisms of lncRNAs and how SNPs disturb binding and recruiting ability. These observations are the first glimpse of the 'lncRNA structurome' and make it possible to robustly explore and assemble intricate space conformation and their stress variation. This result also successfully demonstrates that lncRNA transcripts contain a complex structural landscape and highlights the proposed contribution of lncRNA structure in controlling RNA functions and disease mechanisms.

miR-1204 targets VDR to promotes epithelial-mesenchymal transition and metastasis in breast cancer

Plasmacytoma variant translocation 1 (PVT1) is an lncRNA that plays vital roles in breast cancer (BC) pathogenesis. Increasing evidence suggests that miRNAs that reside in the PVT1 locus are the main driver of the oncogenic roles of PVT1 in cancer. However, the oncogenic role and underlying mechanism of miR-1204, located in the PVT1 locus, in human cancer is still unclear. In this study, we discovered that increased expression of miR-1204 is associated with poor prognosis in BC. Moreover, miR-1204 promotes proliferation, epithelial-mesenchymal transition and invasion of BC cells both in vitro and in vivo. Mechanistic investigations demonstrated that VDR is a novel target gene of miR-1204. Interference of VDR restored miR-1204-mediated BC cell proliferation, tumorigenesis, and metastasis. Collectively, our results demonstrated that the miR-1204-VDR pathway exerts oncogenic effects in BC with potential therapeutic applications in blocking BC development and progression.

The association of CCAT2 rs6983267 SNP with MYC expression and progression of uterine cervical cancer in the Polish population

PURPOSE

Previous studies have reported a significant contribution of NC_000008.10:g.128413305 G>T (rs6983267) single-nucleotide polymorphism (SNP) in the MYC enhancer region to the susceptibility of various cancers. However, the role of rs6983267 SNP in cervical cancer (CC) development and progression has not been demonstrated to date. Therefore, we evaluated the role of rs6983267 SNP in MYC expression in cervical cancers and non-cancerous cervical tissues. In addition, we assessed the role of this SNP in the development and progression of CC.

METHODS

Using high-resolution melting analysis, we evaluated rs6983267 SNP frequency in women diagnosed with cervical squamous cell carcinoma (SCC) (n = 481) and controls (n = 502) in a Polish Caucasian population. Logistic regression analysis was employed to adjust for the effects of age, parity, oral contraceptive use, tobacco smoking, and menopausal status.

RESULTS

Dividing patients based on clinical characteristics demonstrated an association of the rs6983267 genotype with tumor stage III and grade of differentiation G2 and G3. The p trend value calculated for the rs6983267 SNP in patients with stage III was 0.0006. We also observed a significant contribution of rs6983267 SNP to tumor grade of differentiation G2 and G3. Additional contributors were oral contraceptive use, smoking, and postmenopausal age. We found statistically significant increase of MYC transcript levels in cervical SCC tissues from carriers of the GG vs. T/T (p < 0.00001), G/T vs. T/T (p = 0.0002), and in the non-cancerous cervical tissues from carriers of the GG vs. T/T (p = 0.00046).

CONCLUSION

The rs6983267 SNP may contribute to the increased MYC expression as well as the spread and rapid growth of cervical SCC as compared to lower grade carcinomas.

Long noncoding RNAs in gastric cancer carcinogenesis and metastasis

Recent studies of the human transcriptome, most prominently by the ENCyclopedia Of DNA Elements project, have revealed an unexpected number of noncoding RNAs (ncRNAs). Long noncoding RNAs (lncRNAs) are typically referred to a heterogeneous group of polyadenylated long ncRNAs, with a length of > 200 nt. LncRNAs constitute an integral part of tumor biology, with many lncRNAs discovered to be aberrantly expressed in various cancer types. They are involved in many aspects of cancer pathogenesis from its initiation to progression, metastasis and treatment response. Gastric cancer (GC) is the third leading cause of cancer death worldwide. Despite the current improvements of life expectancy and survival rate, most of the patients are diagnosed when their cancer has been progressed to advanced stages. Therefore, unraveling the molecular mechanisms of GC to find early-stage biomarkers is urgent. As the list of lncRNAs with deregulated expression in GC is steadily expanding, these molecules offer a source for developing GC-specific biomarkers. In this review, we will present and discuss those lncRNAs whose expression has been shown to be deregulated in GC.

Upregulation of long non‑coding RNA CCAT2 indicates a poor prognosis and promotes proliferation and metastasis in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (IHCC) is an aggressive cancer with a poor survival rate and is the second most common type of primary cancer of the hepatobiliary system. At present, the molecular mechanisms of IHCC initiation and progression remain unclear. Recent evidence has indicated that long non‑coding RNAs (lncRNAs) serve a crucial role in cancer development; however, the functional role of lncRNAs in IHCC has not been investigated in detail. In the present study, a marked overexpression of lncRNA colon cancer‑associated transcript 2 (CCAT2) was observed in IHCC cell lines and clinical specimens. Statistical analysis of IHCC clinicopathological characteristics and CCAT2 expression data revealed that high CCAT2 expression levels correlated with microvascular invasion, differentiation grade, tumor (T), lymph node (N), metastasis (M) and overall TNM stages of IHCC (P<0.05). Kaplan‑Meier analysis demonstrated that CCAT2 upregulation was associated with poor overall survival and progression‑free survival in IHCC. Furthermore, high CCAT2 expression was identified as an independent risk factor of IHCC poor prognosis in both univariate and multivariate Cox regression analyses. The role of CCAT2 in promoting IHCC cell proliferation, motility and invasion was further confirmed with in vitro assays. Therefore, CCAT2 may promote IHCC progression and metastasis, and may be a promising prognostic biomarker and therapeutic target in IHCC.

Association of rs6983267 at 8q24, HULC rs7763881 polymorphisms and serum lncRNAs CCAT2 and HULC with colorectal cancer in Egyptian patients

The impact of HULC rs7763881 on colorectal cancer (CRC) susceptibility is not yet known. Also, the biological function of the cancer-related rs6983267 remains unclear. We investigated the association of these SNPs with the risk of CRC and adenomatous polyps (AP), their correlation with CCAT2 and HULC expression, and the potential of serum CCAT2 and HULC as biomarkers for CRC. 120 CRC patients, 30 AP patients, and 96 healthy controls were included. Genotyping and serum lncRNAs were assayed by qPCR. Studied SNPs were not associated with AP susceptibility. rs6983267 GG was associated with increased CRC risk, whereas rs7763881 AC was protective. rs7763881 and rs6983267 CT haplotype was protective. Serum CCAT2 and HULC were upregulated in CRC and AP patients versus controls and discriminated these groups by ROC analysis. rs6983267 GG and rs7763881 AA patients demonstrated higher serum CCAT2 and HULC compared with GT/TT and AC, respectively. rs6983267 and serum HULC predicted CRC diagnosis among non-CRC groups (AP + controls) by multivariate analysis. Studied SNPs or serum long noncoding RNAs weren't correlated with nodal or distant metastasis. In conclusion, rs6983267 and rs7763881 are potential genetic markers of CRC predisposition and correlate with serum CCAT2 and HULC, two novel potential non-invasive diagnostic biomarkers for CRC.

Expression Study and Clinical Correlations of MYC and CCAT2 in Breast Cancer Patients

Background:

Colon cancer-associated transcript 2 (CCAT2) is a newly recognized lncRNA transcribed from the 8q24 genomic region. It functions as an oncogene in various types of cancers including breast cancer, in which it affects Wnt/β-catenin pathway. Previous studies have shown a putative interaction between this lncRNA and MYC proto-oncogene.

Methods:

In the current study, we evaluated the expression of CCAT2 in breast cancer tissues with regards to the expression of its target MYC. In addition, we assessed the relationship between CCAT2 and MYC expression levels in tumor tissues and the clinical prognostic characteristics of breast cancer patients.

Results:

MYC expression levels were significantly up-regulated in tumor tissues compared with adjacent non-cancerous tissues (ANCTs), while such analysis showed no statistically significant difference between these two tissue types in CCAT2 expression. Starkly increased CCAT2 gene expression levels were found in 12/48 (25%) of cancer tissue samples compared with their corresponding ANCTs. Furthermore, significant inverse correlations were found between CCAT2 expression and stage, as well as lymph node involvement. Besides, a significant inverse correlation was found between the relative MYC expression in tumor tissues compared with their corresponding ANCTs and disease stage.

Conclusions:

These results highlight the significance of MYC and CCAT2 expressions in the early stages of breast cancer development and suggest a potentially significant role for CCAT2 in a subset of breast cancer patients, which could be applied as a potential therapeutic target in these patients.

Long Noncoding RNAs in Lung Cancer

Despite great progress in research and treatment options, lung cancer remains the leading cause of cancer-related deaths worldwide. Oncogenic driver mutations in protein-encoding genes were defined and allow for personalized therapies based on genetic diagnoses. Nonetheless, diagnosis of lung cancer mostly occurs at late stages, and chronic treatment is followed by a fast onset of chemoresistance. Hence, there is an urgent need for reliable biomarkers and alternative treatment options. With the era of whole genome and transcriptome sequencing technologies, long noncoding RNAs emerged as a novel class of versatile, functional RNA molecules. Although for most of them the mechanism of action remains to be defined, accumulating evidence confirms their involvement in various aspects of lung tumorigenesis. They are functional on the epigenetic, transcriptional, and posttranscriptional level and are regulators of pathophysiological key pathways including cell growth, apoptosis, and metastasis. Long noncoding RNAs are gaining increasing attention as potential biomarkers and a novel class of druggable molecules. It has become clear that we are only beginning to understand the complexity of tumorigenic processes. The clinical integration of long noncoding RNAs in terms of prognostic and predictive biomarker signatures and additional cancer targets could provide a chance to increase the therapeutic benefit. Here, we review the current knowledge about the expression, regulation, biological function, and clinical relevance of long noncoding RNAs in lung cancer.

Association of rs6983267 Polymorphism and Thyroid Cancer Susceptibility: A Systematic Review and Meta-Analysis

Background

Recent genome-wide association studies have identified rs6983267 polymorphism as a key locus in the 8q24 region associated with multisite cancers. However, the information on its association with thyroid cancer is inconclusive. The aim of this study was to determine whether this locus is a risk factor for susceptibility to thyroid cancer by conducting a meta-analysis.

Material/Methods

Relevant studies were identified by searching PubMed and Embase databases. The pooled odds ratio (OR) and corresponding 95% confidence interval (95% CI) were calculated.

Results

A total of 4 studies including 2825 cases and 9684 controls were enrolled to this meta-analysis. The pooled data showed the G allele of the rs6983267 polymorphism is a risk factor for susceptibility to thyroid cancer (OR=1.08, 95%CI: 1.02–1.16, P=0.01). Significant associations were also found in homozygote comparison (GG vs. TT: OR=1.17, 95%CI: 1.03–1.33, P=0.02) and dominant model (GG+GT vs. TT: OR=1.13, 95%CI: 1.01–1.26, P=0.03). Borderline significant associations in similar directions were found in the recessive model (GG vs. GT+TT: OR=1.10, 95%CI: 0.99–1.22, P=0.07) and heterozygote comparison (GT vs. TT: OR=1.10, 95%CI: 0.99–1.24, P=0.09).

Conclusions

Our meta-analysis shows that the rs6983267 G>T polymorphism might be associated with higher risk of thyroid cancer. Further research with larger sample sizes and full investigation of confounding risk factors is needed to confirm or revise our conclusions.

Systematic meta-analyses and field synopsis of genetic association studies in colorectal adenomas

BACKGROUND

Low penetrance genetic variants, primarily single nucleotide polymorphisms, have substantial influence on colorectal cancer (CRC) susceptibility. Most CRCs develop from colorectal adenomas (CRA). Here we report the first comprehensive field synopsis that catalogues all genetic association studies on CRA, with a parallel online database [http://www.chs.med.ed.ac.uk/CRAgene/].

METHODS

We performed a systematic review, reviewing 9750 titles, and then extracted data from 130 publications reporting on 181 polymorphisms in 74 genes. We conducted meta-analyses to derive summary effect estimates for 37 polymorphisms in 26 genes. We applied the Venice criteria and Bayesian False Discovery Probability (BFDP) to assess the levels of the credibility of associations.

RESULTS

We considered the association with the rs6983267 variant at 8q24 as 'highly credible', reaching genome-wide statistical significance in at least one meta-analysis model. We identified 'less credible' associations (higher heterogeneity, lower statistical power, BFDP > 0.02) with a further four variants of four independent genes: MTHFR c.677C>T p.A222V (rs1801133), TP53 c.215C>G p.R72P (rs1042522), NQO1 c.559C>T p.P187S (rs1800566), and NAT1 alleles imputed as fast acetylator genotypes. For the remaining 32 variants of 22 genes for which positive associations with CRA risk have been previously reported, the meta-analyses revealed no credible evidence to support these as true associations.

CONCLUSIONS

The limited number of credible associations between low penetrance genetic variants and CRA reflects the lower volume of evidence and associated lack of statistical power to detect associations of the magnitude typically observed for genetic variants and chronic diseases. The CRA gene database provides context for CRA genetic association data and will help inform future research directions.

The non-coding transcriptome as a dynamic regulator of cancer metastasis

Since the discovery of microRNAs, non-coding RNAs (NC-RNAs) have increasingly attracted the attention of cancer investigators. Two classes of NC-RNAs are emerging as putative metastasis-related genes: long non-coding RNAs (lncRNAs) and small nucleolar RNAs (snoRNAs). LncRNAs orchestrate metastatic progression through several mechanisms, including the interaction with epigenetic effectors, splicing control and generation of microRNA-like molecules. In contrast, snoRNAs have been long considered “housekeeping” genes with no relevant function in cancer. However, recent evidence challenges this assumption, indicating that some snoRNAs are deregulated in cancer cells and may play a specific role in metastasis. Interestingly, snoRNAs and lncRNAs share several mechanisms of action, and might synergize with protein-coding genes to generate a specific cellular phenotype. This evidence suggests that the current paradigm of metastatic progression is incomplete. We propose that NC-RNAs are organized in complex interactive networks which orchestrate cellular phenotypic plasticity. Since plasticity is critical for cancer cell metastasis, we suggest that a molecular interactome composed by both NC-RNAs and proteins orchestrates cancer metastasis. Interestingly, expression of lncRNAs and snoRNAs can be detected in biological fluids, making them potentially useful biomarkers. NC-RNA expression profiles in human neoplasms have been associated with patients’ prognosis. SnoRNA and lncRNA silencing in pre-clinical models leads to cancer cell death and/or metastasis prevention, suggesting they can be investigated as novel therapeutic targets. Based on the literature to date, we critically discuss how the NC-RNA interactome can be explored and manipulated to generate more effective diagnostic, prognostic, and therapeutic strategies for metastatic neoplasms.

A Genome-Wide Scan Identifies Variants in NFIB Associated with Metastasis in Patients with Osteosarcoma

Metastasis is the leading cause of death in patients with osteosarcoma, the most common pediatric bone malignancy. We conducted a multistage genome-wide association study of osteosarcoma metastasis at diagnosis in 935 osteosarcoma patients to determine whether germline genetic variation contributes to risk of metastasis. We identified an SNP, rs7034162, in NFIB significantly associated with metastasis in European osteosarcoma cases, as well as in cases of African and Brazilian ancestry (meta-analysis of all cases: P = 1.2 × 10(-9); OR, 2.43; 95% confidence interval, 1.83-3.24). The risk allele was significantly associated with lowered NFIB expression, which led to increased osteosarcoma cell migration, proliferation, and colony formation. In addition, a transposon screen in mice identified a significant proportion of osteosarcomas harboring inactivating insertions in Nfib and with lowered NFIB expression. These data suggest that germline genetic variation at rs7034162 is important in osteosarcoma metastasis and that NFIB is an osteosarcoma metastasis susceptibility gene.

SIGNIFICANCE

Metastasis at diagnosis in osteosarcoma is the leading cause of death in these patients. Here we show data that are supportive for the NFIB locus as associated with metastatic potential in osteosarcoma.

Junk DNA and the long non-coding RNA twist in cancer genetics

The central dogma of molecular biology states that the flow of genetic information moves from DNA to RNA to protein. However, in the last decade this dogma has been challenged by new findings on non-coding RNAs (ncRNAs) such as microRNAs (miRNAs). More recently, long non-coding RNAs (lncRNAs) have attracted much attention due to their large number and biological significance. Many lncRNAs have been identified as mapping to regulatory elements including gene promoters and enhancers, ultraconserved regions, and intergenic regions of protein-coding genes. Yet, the biological function and molecular mechanisms of lncRNA in human diseases in general and cancer in particular remain largely unknown. Data from the literature suggest that lncRNA, often via interaction with proteins, functions in specific genomic loci or use their own transcription loci for regulatory activity. In this review, we summarize recent findings supporting the importance of DNA loci in lncRNA function, and the underlying molecular mechanisms via cis or trans regulation, and discuss their implications in cancer. In addition, we use the 8q24 genomic locus, a region containing interactive SNPs, DNA regulatory elements and lncRNAs, as an example to illustrate how single nucleotide polymorphism (SNP) located within lncRNAs may be functionally associated with the individual’s susceptibility to cancer.

CCAT2, a novel long non-coding RNA in breast cancer: expression study and clinical correlations

The clinical outcome of BC patients receiving the same treatment is known to vary considerably and thus, there is a compelling need to identify novel biomarkers that can select the patients that would benefit most from a given therapy and can predict the clinical outcome. The aim of this study was to determine the prognostic value of CCAT2, a novel long ncRNA recently characterized by our group and overlapping SNP rs6983267, in BC patients. We first evaluated by RT-qPCR and ISH the expression of CCAT2 in normal breast tissue and BC tissue and further analyzed CCAT2 expression in an independent set of 997 primary BC with regard to clinical, histological, pathological and other biological factors. Also, we explored the possibility of CCAT2 adding to the prognostic value of multivariate models that already included the traditional prognostic factors. Finally, we identified in in vitro models the impact of CCAT2 expression and SNP rs6983267 genotype on cell migration and chemoresistance. Our results revealed that although overexpressed in BCs in two out of three sets of patients, and having the highest expression in lymph node negative (LNN) disease, CCAT2 expression levels are informative solely for a subgroup of BC patients, namely for patients with LNP disease that have received adjuvant CMF chemotherapy. For this subgroup high levels of CCAT2 suggest the patients will not benefit from CMF containing adjuvant chemotherapy (shorter MFS and OS). Additionally, we found that CCAT2 upregulates cell migration and downregulates chemosensitivity to 5'FU in a rs6983267-independent manner.

Prognostic relevance of urinary bladder cancer susceptibility loci

In the last few years, susceptibility loci have been identified for urinary bladder cancer (UBC) through candidate-gene and genome-wide association studies. Prognostic relevance of most of these loci is yet unknown. In this study, we used data of the Nijmegen Bladder Cancer Study (NBCS) to perform a comprehensive evaluation of the prognostic relevance of all confirmed UBC susceptibility loci. Detailed clinical data concerning diagnosis, stage, treatment, and disease course of a population-based series of 1,602 UBC patients were collected retrospectively based on a medical file survey. Kaplan-Meier survival analyses and Cox proportional hazard regression were performed, and log-rank tests calculated, to evaluate the association between 12 confirmed UBC susceptibility variants and recurrence and progression in non-muscle invasive bladder cancer (NMIBC) patients. Among muscle-invasive or metastatic bladder cancer (MIBC) patients, association of these variants with overall survival was tested. Subgroup analyses by tumor aggressiveness and smoking status were performed in NMIBC patients. In the overall NMIBC group (n = 1,269), a statistically significant association between rs9642880 at 8q24 and risk of progression was observed (GT vs. TT: HR = 1.08 (95% CI: 0.76-1.54), GG vs. TT: HR = 1.81 (95% CI: 1.23-2.66), P for trend = 2.6 × 10(-3)). In subgroup analyses, several other variants showed suggestive, though non-significant, prognostic relevance for recurrence and progression in NMIBC and survival in MIBC. This study provides suggestive evidence that genetic loci involved in UBC etiology may influence disease prognosis. Elucidation of the causal variant(s) could further our understanding of the mechanism of disease, could point to new therapeutic targets, and might aid in improvement of prognostic tools.

Ago1 Interacts with RNA polymerase II and binds to the promoters of actively transcribed genes in human cancer cells

Argonaute proteins are often credited for their cytoplasmic activities in which they function as central mediators of the RNAi platform and microRNA (miRNA)-mediated processes. They also facilitate heterochromatin formation and establishment of repressive epigenetic marks in the nucleus of fission yeast and plants. However, the nuclear functions of Ago proteins in mammalian cells remain elusive. In the present study, we combine ChIP-seq (chromatin immunoprecipitation coupled with massively parallel sequencing) with biochemical assays to show that nuclear Ago1 directly interacts with RNA Polymerase II and is widely associated with chromosomal loci throughout the genome with preferential enrichment in promoters of transcriptionally active genes. Additional analyses show that nuclear Ago1 regulates the expression of Ago1-bound genes that are implicated in oncogenic pathways including cell cycle progression, growth, and survival. Our findings reveal the first landscape of human Ago1-chromosomal interactions, which may play a role in the oncogenic transcriptional program of cancer cells.

Argonaute (Ago) proteins are an evolutionarily conserved family of proteins indispensable for a gene regulation mechanism known as RNA interference (RNAi) which is mediated by small RNA including microRNA (miRNA) and small interfering RNA (siRNA) and occurs mainly in the cytoplasm. In mammalian cells, however, the function of Agos in the nucleus is largely unknown despite a few examples in which Agos are shown to be involved in regulating gene transcription and alternative splicing. In this study, by taking a genome-wide approach, we found that human Ago1, but not Ago2, is pervasively associated with gene regulatory sequences known as promoter and interacts with the core component of the gene transcription machinery to exert positive impact on gene expression in cancer cells. Strikingly, the genes bound and regulated by Ago1 are mostly genes that stimulate cell growth and survival, and are known to be involved in the development of cancer. The findings from our study unveil an unexpected role of nuclear Ago1 in regulating gene expression which may be important both in normal cellular processes and in disease such as cancer.

CCAT2, a novel noncoding RNA mapping to 8q24, underlies metastatic progression and chromosomal instability in colon cancer

The functional roles of SNPs within the 8q24 gene desert in the cancer phenotype are not yet well understood. Here, we report that CCAT2, a novel long noncoding RNA transcript (lncRNA) encompassing the rs6983267 SNP, is highly overexpressed in microsatellite-stable colorectal cancer and promotes tumor growth, metastasis, and chromosomal instability. We demonstrate that MYC, miR-17-5p, and miR-20a are up-regulated by CCAT2 through TCF7L2-mediated transcriptional regulation. We further identify the physical interaction between CCAT2 and TCF7L2 resulting in an enhancement of WNT signaling activity. We show that CCAT2 is itself a WNT downstream target, which suggests the existence of a feedback loop. Finally, we demonstrate that the SNP status affects CCAT2 expression and the risk allele G produces more CCAT2 transcript. Our results support a new mechanism of MYC and WNT regulation by the novel lncRNA CCAT2 in colorectal cancer pathogenesis, and provide an alternative explanation of the SNP-conferred cancer risk.

CCAT2, a novel noncoding RNA mapping to 8q24, underlies metastatic progression and chromosomal instability in colon cancer

The functional roles of SNPs within the 8q24 gene desert in the cancer phenotype are not yet well understood. Here, we report that CCAT2, a novel long noncoding RNA transcript (lncRNA) encompassing the rs6983267 SNP, is highly overexpressed in microsatellite-stable colorectal cancer and promotes tumor growth, metastasis, and chromosomal instability. We demonstrate that MYC, miR-17-5p, and miR-20a are up-regulated by CCAT2 through TCF7L2-mediated transcriptional regulation. We further identify the physical interaction between CCAT2 and TCF7L2 resulting in an enhancement of WNT signaling activity. We show that CCAT2 is itself a WNT downstream target, which suggests the existence of a feedback loop. Finally, we demonstrate that the SNP status affects CCAT2 expression and the risk allele G produces more CCAT2 transcript. Our results support a new mechanism of MYC and WNT regulation by the novel lncRNA CCAT2 in colorectal cancer pathogenesis, and provide an alternative explanation of the SNP-conferred cancer risk.