Amplification and up-regulation of microRNA-30b in oral squamous cell cancers

MicroRNA copy number alterations in the malignant transformation of pleomorphic adenoma to carcinoma ex pleomorphic adenoma

OBJECTIVE

This study used array comparative genomic hybridization to assess copy number alterations (CNAs) involving miRNA genes in pleomorphic adenoma (PA), recurrent pleomorphic adenoma (RPA), residual PA, and carcinoma ex pleomorphic adenoma (CXPA).

MATERIALS AND METHODS

We analyzed 13 PA, 4 RPA, 29 CXPA, and 14 residual PA using Nexus Copy Number Discovery software. The miRNAs genes affected by CNAs were evaluated based on their expression patterns and subjected to pathway enrichment analysis.

RESULTS

Across the groups, we found 216 CNAs affecting 2261 miRNA genes, with 117 in PA, 59 in RPA, 846 in residual PA, and 2555 in CXPA. The chromosome 8 showed higher involvement in altered miRNAs in PAs and CXPA patients. Six miRNA genes were shared among all groups. Additionally, miR-21, miR-455-3p, miR-140, miR-320a, miR-383, miR-598, and miR-486 were prominent CNAs found and is implicated in carcinogenesis of several malignant tumors. These miRNAs regulate critical signaling pathways such as aerobic glycolysis, fatty acid biosynthesis, and cancer-related pathways.

CONCLUSION

This study was the first to explore CNAs in miRNA-encoding genes in the PA-CXPA sequence. The findings suggest the involvement of numerous miRNA genes in CXPA development and progression by regulating oncogenic signaling pathways.

Mir-30b-3p affects the migration and invasion function of ovarian cancer cells by targeting the CTHRC1 gene

BACKGROUND

The aim of this study was to investigate the effect role and mechanism of miR-30b-3p on ovarian cancer cells biological function.

METHODS

The expression of miR-30b-3p was detected in ovarian cancer cell lines and normal ovarian epithelial cell line by qRT-PCR. Mir-30b-3p mimic was transfected into OVCAR3 cells. Cell-counting kit-8 (CCK-8) assay was conducted to explore the effect of mir-30b-3p on the OVCAR3 cells' proliferation. Cell cycle and apoptosis were detected by Flow cytometry. Cell invasion ability was detected by Transwell test. The regulation of putative target of miR-30b-3p was verified by double luciferase reporter assays and Western blot.

RESULT

We found that miR-30b-3p was downregulated in OVCAR3 cells. Overexpression of miR-30b-3p suppressed proliferation, promoted apoptosis, slowed cell cycle and inhibited migration and invasion of OVCAR3 cells. Bioinformatics analysis identified 3'-untranslated region (3'UTR) of Collagen triple helix repeat-containing 1 (CTHRC1) as the presumed binding site for miR-30b-3p. Detection of double luciferase reporter and Western-Blot result confirmed that CTHRC1 was the target gene of miR-30b-3p. Furthermore, E-cadherin, β-cadherin and Vimentin protein expression level were changed after transfection of miR-30b-3p.

CONCLUSION

miR-30b-3p function as an anti-cancer gene. Overexpression of miR-30b-3p can inhibit the biological function of ovarian cancer cells. MiR-30b-3p targets CTHRC1 gene plays an important role in epithelial-mesenchymal transformation (EMT), and supports miR-30b-3p as a potential biological indicator for ovarian cancer in the future.

MicroRNA-30b-5p functions as a metastasis suppressor in colorectal cancer by targeting Rap1b

Colorectal liver metastasis (CRLM) is the leading cause of death in patients with colorectal cancer (CRC). MiR-30b-5p can function as an oncogene or tumor suppressor in cancers, but its role in CRLM is still unknown. Here, we found that miR-30b-5p overexpression suppressed the invasion, migration, adhesion, and motility of HCT116 and LoVo cells. The expression of EMT (Zeb1, Snail, and vimentin) and adhesion-related proteins (p-paxillin and p-Src) was decreased. We validated Rap1b, a Ras family small GTPase that regulates cell adhesion and mobility, as the direct and functional target of miR-30b-5p. Rap1b overexpression rescued the aggressive characteristics of CRC cells that were inhibited by miR-30b-5p. Rap1b knockdown suppressed invasion and migration and decreased CRC cell-matrix adhesion and spreading, which was consistent with the results of miR-30b-5p overexpression. Further in vivo experiments demonstrated that miR-30b-5p overexpression inhibited CRLM, but Rap1b rescue attenuated the inhibitory effect of miR-30b-5p. In addition, miR-30b-5p was downregulated in CRC specimens, and Rap1b showed a negative correlation with miR-30b-5p expression in primary CRC and LM tissues. These results indicate that miR-30b-5p functions as a metastasis suppressor by targeting Rap1b and may provide a new target for the treatment of CRLM.

Overexpression of circulating MiR-30b-5p identifies advanced breast cancer

BACKGROUND

Breast cancer (BrC) remains the leading cause of cancer-related death in women, mainly due to recurrent and/or metastatic events, entailing the need for biomarkers predictive of progression to advanced disease. MicroRNAs hold promise as noninvasive cancer biomarkers due to their inherent stability and resilience in tissues and bodily fluids. There is increasing evidence that specific microRNAs play a functional role at different steps of the metastatic cascade, behaving as signaling mediators to enable the colonization of a specific organ. Herein, we aimed to evaluate the biomarker performance of microRNAs previously reported as associated with prognosis for predicting BrC progression in liquid biopsies.

METHODS

Selected microRNAs were assessed using a quantitative reverse transcription-polymerase chain reaction in a testing cohort of formalin-fixed paraffin-embedded primary (n = 16) and metastatic BrC tissues (n = 22). Then, miR-30b-5p and miR-200b-3p were assessed in a validation cohort #1 of formalin-fixed paraffin-embedded primary (n = 82) and metastatic BrC tissues (n = 93), whereas only miR-30b-5p was validated on a validation cohort #2 of liquid biopsies from BrC patients with localized (n = 20) and advanced (n = 25) disease. ROC curve was constructed to evaluate prognostic performance.

RESULTS

MiR-30b-5p was differentially expressed in primary tumors and paired metastatic lesions, with bone metastases displaying significantly higher miR-30b-5p expression levels, paralleling the corresponding primary tumors. Interestingly, patients with advanced disease disclosed increased circulating miR-30b-5p expression compared to patients with localized BrC.

CONCLUSIONS

MiR-30b-5p might identify BrC patients at higher risk of disease progression, thus, providing a useful clinical tool for patients' monitoring, entailing earlier and more effective treatment. Nonetheless, validation in larger multicentric cohorts is mandatory to confirm these findings.

A 3-miRNA signature predicts survival of patients with hypopharyngeal squamous cell carcinoma after post-operative radiotherapy

Since the prognosis of hypopharyngeal squamous cell carcinoma (HSCC) remains poor, identification of miRNA as a potential prognostic biomarker for HSCC may help improve personalized therapy. In the 2 cohorts with a total of 511 patients with HSCC (discovery: N = 372 and validation: N = 139) after post-operative radiotherapy, we used miRNA microarray and qRT-PCR to screen out the significant miRNAs which might predict survival. Associations of miRNAs and the signature score of these miRNAs with survival were performed by Kaplan-Meier survival analysis and multivariate Cox hazard model. Among 9 candidate, miRNAs, miR-200a-3p, miR-30b-5p, miR-3161, miR-3605-5p, miR-378b and miR-4451 were up-regulated, while miR-200c-3p, miR-429 and miR-4701 were down-regulated after validation. Moreover, the patients with high expression of miR-200a-3p, miR-30b-5p and miR-4451 had significantly worse overall survival (OS) and disease-specific survival (DSS) than did those with low expression (log-rank P < .05). Patients with a high-risk score had significant worse OS and DSS than those with low-risk score. Finally, after adjusting for other important prognostic confounders, patients with high expression of miR-200a-3p, miR-30b-5p and miR-4451 had significantly high risk of overall death and death owing to HSCC and patients with a high-risk score has approximately 2-fold increased risk in overall death and death owing to HSCC compared with those with a low-risk score. These findings indicated that the 3-miRNA-based signature may be a novel independent prognostic biomarker for patients given surgery and post-operative radiotherapy, supporting that these miRNAs may jointly predict survival of HSCC.

miRNA‑30a‑3p inhibits metastasis and enhances radiosensitivity in esophageal carcinoma by targeting insulin‑like growth factor 1 receptor

It has been demonstrated that microRNAs (miRNAs) serve important roles in various biological processes, such as tumorigenesis. In the present study, the role of miR‑30a‑3p in the pathogenesis of esophageal carcinoma (EC) was investigated. Reverse transcription‑quantitative polymerase chain reaction was performed to determine the levels of miR‑30a‑3p expression in EC tissues and cell lines. Then, the effects of miR‑30a‑3p on the migration, invasion and radiosensitivity of EC cells were investigated using scratch‑wound, Transwell and radiosensitivity assays, respectively. A dual‑luciferase reporter assay was performed to determine potential interactions between miR‑30a‑3p and the 3'‑untranslated region (3'‑UTR) of insulin‑like growth factor 1 receptor (IGF‑1R). The results demonstrated that the levels of miR‑30a‑3p expression in EC tissues and cell lines were significantly decreased compared with those in paired healthy tissues and a human esophageal epithelial cell line. Upregulation of miR‑30a‑3p expression significantly suppressed migration, invasion and epithelial‑mesenchymal transition (EMT), and enhanced radiosensitivity in EC cells. Analysis of luciferase activity demonstrated that miR‑30a‑3p interacted with the 3'‑UTR of IGF‑1R, and knockdown of IGF‑1R induced similar effects on the migration, invasion, EMT and radiosensitivity of EC cells. The results indicated that miR‑30a‑3p suppressed metastasis and enhanced the radiosensitivity of EC cells via downregulation IGF‑1R, suggesting that miR‑30a‑3p may be a potential therapeutic target in the treatment of EC.

Quantification of microRNAs directly from body fluids using a base-stacking isothermal amplification method in a point-of-care device

MicroRNAs have been proposed to be a class of biomarkers of disease as expression levels are significantly altered in various tissues and body fluids when compared to healthy controls. As such, the detection and quantification of microRNAs is imperative. While many methods have been established for quantification of microRNAs, they typically rely on time consuming handling such as RNA extraction, purification, or ligation. Here we describe a novel method for quantification of microRNAs using direct amplification in body fluids without upstream sample preparation. Tested with a point-of-care device (termed Gene-Z), the presence of microRNA promotes base-stacking hybridization, and subsequent amplification between two universal strands. The base-stacking approach, which was achieved in <60 min, provided a sensitivity of 1.4 fmol per reaction. Tested in various percentages of whole blood, plasma, and faeces, precision (coefficient of variation = 2.6%) was maintained and comparable to amplification in pristine samples. Overall, the developed method represents a significant step towards rapid, one-step detection of microRNAs.

The miR-30 family: Versatile players in breast cancer

The microRNA family, miR-30, plays diverse roles in regulating key aspects of neoplastic transformation, metastasis, and clinical outcomes in different types of tumors. Accumulating evidence proves that miR-30 family is pivotal in the breast cancer development by controlling critical signaling pathways and relevant oncogenes. Here, we review the roles of miR-30 family members in the tumorigenesis, metastasis, and drug resistance of breast cancer, and their application to predict the prognosis of breast cancer patients. We think miR-30 family members would be promising biomarkers for breast cancer and may bring a novel insight in molecular targeted therapy of breast cancer.

Identification of miR‑30b as an oncogene in renal cell carcinoma

microRNAs (miRs) have been investigated as a novel class of regulators of cellular processes, including proliferation, apoptosis and metabolism. In particular, miR‑30b has been demonstrated to be deregulated in certain types of cancer, including lung, colorectal and gastric cancer. Previous studies of miR‑30b in renal clear cell carcinoma demonstrated that the expression level of miR‑30b was associated with distant metastasis. However, the function of miR‑30b in renal cell carcinoma (RCC) remained to be elucidated. In the present study, the expression of miR‑30b in 31 paired RCC tissues from four cell lines (786‑O, 769‑P, ACHN and 293T) was detected by reverse transcription‑quantitative polymerase chain reaction. In addition, the effect of miR‑30b on cell proliferation in RCC cells was also determined using MTT and Cell Counting Kit‑8 assay analyses. Furthermore, the function of miR‑30b in cell migration and invasion was determined by wound scratch and Transwell assays. Flow cytometry was also performed to quantify the effect of miR‑30b on cell apoptosis. The results of the current study indicated that miR‑30b was upregulated in RCC tissues from affected cell lines when compared with adjacent normal tissues and a normal kidney cell line, which is different to the downregulation of miR‑30b as observed in other types of cancer. miR‑30b is associated with RCC cell proliferation, invasion, migration and apoptosis, which indicated that miR‑30b acts as an oncogene in RCC. To the best of our knowledge, the present study is the first to demonstrate the upregulation of miR‑30b in RCC tissues and describe miR‑30b as an oncogene in RCC in the regulation of cell proliferation, migration, invasion and apoptosis. Further studies will define the target gene of miR‑30b in RCC and investigate the potential role of miR‑30b as a biomarker for RCC.

Distinctive pattern of let-7 family microRNAs in aggressive carcinoma of the oral tongue in young patients

Oral cavity squamous cell carcinoma may be more aggressive at presentation and recurrence in young patients compared with older patients. Dysregulation of microRNAs (miRNAs or miRs) has been associated with the development and prognosis of oral cavity cancer. The present study investigated miRNA expression in carcinoma of the oral tongue in young patients. miRNA expression profiles were evaluated in formalin-fixed, paraffin-embedded samples of tumor and normal mucosa from 12 patients aged <30 years old with squamous cell carcinoma of the tongue. The levels of let-7f-5p, miR-30b-5p and let-7e-5p were upregulated in tumors (P<0.05). The expression of let-7f-5p was upregulated in non-aggressive tumors, while the expression of let-7e-5p was upregulated in aggressive tumors, compared with the corresponding normal tissue. Aggressive tumors had higher levels of let-7c, miR-130a-3p, miR-361-5p, miR-99a-5p, miR-29c-3p and let-7d-5p than non-aggressive tumors (P<0.05). The findings remained significant for let-7c upon false-discovery rate correction. An excellent correlation was noticed on validation of NanoString counts by quantitative polymerase chain reaction. The comparison with published findings in adults demonstrated a unique miRNA signature in young patients with aggressive disease. Aggressive oral cavity cancer in patients <30 years old is associated with a distinctive expression pattern of the let-7 family. Larger studies including direct comparison with older patients are warranted.

Genome-wide association studies and epigenome-wide association studies go together in cancer control

Completion of the human genome a decade ago laid the foundation for: using genetic information in assessing risk to identify individuals and populations that are likely to develop cancer, and designing treatments based on a person's genetic profiling (precision medicine). Genome-wide association studies (GWAS) completed during the past few years have identified risk-associated single nucleotide polymorphisms that can be used as screening tools in epidemiologic studies of a variety of tumor types. This led to the conduct of epigenome-wide association studies (EWAS). This article discusses the current status, challenges and research opportunities in GWAS and EWAS. Information gained from GWAS and EWAS has potential applications in cancer control and treatment.

Clinical implications of epigenetic regulation in oral cancer

Oral cancer is a high incidence cancer which is of major public health concern in India being the most common cancer in males and fifth most common cancer in females in India, contributing to 26% of the global oral cancer burden. The major risk factors of oral cancer are tobacco, alcohol and high risk Human Papilloma Virus type 16/18. However, only 3-12% of the high risk individuals with dysplasia develop oral cancer. Thus, individual genomic variants representing the genomic constitution and epigenetic alterations play a critical role in the development of oral cancer. Extensive epigenetic studies on the molecular lesions including oncogenes, tumor suppressor genes, genes associated with apoptosis, DNA damage repair have been reported. The current review highlights epigenetic regulation with a focus on molecular biomarkers and epidrug therapy in oral cancer. Epigenetic regulation by hypermethylation, histone modifications and specific microRNAs are often associated with early events and advanced stages in oral cancer, and thus indicate epidrug therapy for intervention. The presence of epigenetic marks in oral lesions, cancers and tumor associated mucosa emphasizes indications as biomarkers and epidrugs with therapeutic potential for better patient management.

MiR-30b suppresses tumor migration and invasion by targeting EIF5A2 in gastric cancer

AIM

To elucidate the potential biological role of miR-30b in gastric cancer and investigate the underlying molecular mechanisms of miR-30b to inhibit metastasis of gastric cancer cells.

METHODS

The expression of miR-30b was detected in gastric cancer cell lines and samples by reverse transcription-polymerase chain reaction. CCK-8 assays were conducted to explore the impact of miR-30b overexpression on the proliferation of gastric cancer cells. Flow cytometry was used to examine the effect of miR-30b on the apoptosis. Transwell test was used for the migration and invasion assays. Luciferase reporter assays and Western blot were employed to validate regulation of putative target of miR-30b.

RESULTS

The results showed that miR-30b was downregulated in gastric cancer tissues and cancer cell lines and functioned as a tumor suppressor. Overexpression of miR-30b promoted cell apoptosis, and suppressed proliferation, migration and invasion of the gastric cancer cell lines AGS and MGC803. Bioinformatic analysis identified the 3'-untranslated region of eukaryotic translation initiation factor 5A2 (EIF5A2) as a putative binding site of miR-30b. Luciferase reporter assays and Western blot analysis confirmed the EIF5A2 gene as a target of miR-30b. Moreover, expression levels of the EIF5A2 targets E-cadherin and Vimentin were altered following transfection of miR-30b mimics.

CONCLUSION

Our findings describe a link between miR-30b and EIF5A2, which plays an important role in mediating epithelial-mesenchymal transition.

MicroRNA-30b functions as a tumour suppressor in human colorectal cancer by targeting KRAS, PIK3CD and BCL2

Colorectal cancer (CRC) is the third most common cancer in the USA. MicroRNAs play important roles in the pathogenesis of CRC. In this study, we investigated the role of miR-30b in CRC and found that its expression was significantly lower in CRC tissues than that in normal tissues. We showed that a low expression level of miR-30b was closely related to poor differentiation, advanced TNM stage and poor prognosis of CRC. Further experiments showed that over-expression of miR-30b suppressed CRC cell proliferation in vitro and tumour growth in vivo. Specifically, miR-30b promoted G1 arrest and induced apoptosis. Moreover, KRAS, PIK3CD and BCL2 were identified as direct and functional targets of miR-30b. MiR-30b directly targeted the 3'-untranslated regions of their mRNAs and repressed their expression. This study revealed functional and mechanistic links between miRNA-30b and oncogene KRAS, PIK3CD and BCL2 in the pathogenesis of CRC. MiR-30b not only plays important roles in the regulation of cell proliferation and tumour growth in CRC, but is also a potential prognostic marker or therapeutic target for CRC. Restoration of miR-30b expression may represent a promising therapeutic approach for targeting malignant CRC.

Comparisons of microRNA patterns in plasma before and after tumor removal reveal new biomarkers of lung squamous cell carcinoma

Lung cancer is the major human malignancy, accounting for 30% of all cancer-related deaths worldwide. Poor survival of lung cancer patients, together with late diagnosis and resistance to classic chemotherapy, highlights the need for identification of new biomarkers for early detection. Among different cancer biomarkers, small non-coding RNAs called microRNAs (miRNAs) are considered the most promising, owing to their remarkable stability, their cancer-type specificity, and their presence in body fluids. However, results of multiple previous attempts to identify circulating miRNAs specific for lung cancer are inconsistent, likely due to two main reasons: prominent variability in blood miRNA content among individuals and difficulties in distinguishing tumor-relevant miRNAs in the blood from their non-tumor counterparts. To overcome these impediments, we compared circulating miRNA profiles in patients with lung squamous cell carcinoma (SCC) before and after tumor removal, assuming that the levels of all tumor-relevant miRNAs would drop after the surgery. Our results revealed a specific panel of the miRNAs (miR-205, -19a, -19b, -30b, and -20a) whose levels decreased strikingly in the blood of patients after lung SCC surgery. Interestingly, miRNA profiling of plasma fractions of lung SCC patients revealed high levels of these miRNA species in tumor-specific exosomes; additionally, some of these miRNAs were also found to be selectively secreted to the medium by cultivated lung cancer cells. These results strengthen the notion that tumor cells secrete miRNA-containing exosomes into circulation, and that miRNA profiling of the exosomal plasma fraction may reveal powerful cancer biomarkers.

MicroRNA aberrances in head and neck cancer: pathogenetic and clinical significance

PURPOSE OF REVIEW

MicroRNAs (miRNAs) play crucial roles in modulating the neoplastic process of cancers including head and neck squamous cell carcinoma (HNSCC). miRNAs modulate pathogenesis by inhibiting target genes. Understanding how aberrant miRNAs are involved in HNSCC pathogenesis should help to validate potential clinical applications that target these entities.

RECENT FINDINGS

miR-21, miR-31, miR-504 and miR-10b are important oncogenic miRNAs that are involved in HNSCC and target tumour suppressor genes. The tumour suppressor roles of the let-7 family, the miR-99 family, miR-107, miR-133a, miR-137, miR-138 and miR-375 with respect to their targeting of oncogenes are unequivocal and have been confirmed by many studies. In addition, miR-21, let-7, miR-107, miR-138 and miR-200c seem to play complicated roles in regulating stemness or the epithelial-mesenchymal transition of tumour cells. The clinical implications of these tumour-associated miRNAs are generally in agreement with their functional roles.

SUMMARY

A number of pathways that become disregulated by aberrant miRNAs have been identified specifically for HNSCC. Analysis of these networks and their therapeutic interception might facilitate the prediction of disease status and help with the design of therapeutic trials.

Identification of a set of miRNAs differentially expressed in transiently TIA-depleted HeLa cells by genome-wide profiling

BACKGROUND

T-cell intracellular antigen (TIA) proteins function as regulators of cell homeostasis. These proteins control gene expression globally at multiple levels in response to dynamic regulatory changes and environmental stresses. Herein we identified a micro(mi)RNA signature associated to transiently TIA-depleted HeLa cells and analyzed the potential role of miRNAs combining genome-wide analysis data on mRNA and miRNA profiles.

RESULTS

Using high-throughput miRNA expression profiling, transient depletion of TIA-proteins in HeLa cells was observed to promote significant and reproducible changes affecting to a pool of up-regulated miRNAs involving miR-30b-3p, miR125a-3p, miR-193a-5p, miR-197-3p, miR-203a, miR-210, miR-371-5p, miR-373-5p, miR-483-5p, miR-492, miR-498, miR-503-5p, miR-572, miR-586, miR-612, miR-615-3p, miR-623, miR-625-5p, miR-629-5p, miR-638, miR-658, miR-663a, miR-671-5p, miR-769-3p and miR-744-5p. Some up-regulated and unchanged miRNAs were validated and previous results confirmed by reverse transcription and real time PCR. By target prediction of the miRNAs and combined analysis of the genome-wide expression profiles identified in TIA-depleted HeLa cells, we detected connections between up-regulated miRNAs and potential target genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database analysis suggest that target genes are related with biological processes associated to the regulation of DNA-dependent transcription, signal transduction and multicellular organismal development as well as with the enrichment of pathways involved in cancer, focal adhesion, regulation of actin cytoskeleton, endocytosis and MAPK and Wnt signaling pathways, respectively. When the collection of experimentally defined differentially expressed genes in TIA-depleted HeLa cells was intersected with potential target genes only 7 out of 68 (10%) up- and 71 out of 328 (22%) down-regulated genes were shared. GO and KEGG database analyses showed that the enrichment categories of biological processes and cellular pathways were related with innate immune response, signal transduction, response to interleukin-1, glomerular basement membrane development as well as neuroactive ligand-receptor interaction, endocytosis, lysosomes and apoptosis, respectively.

CONCLUSION

All this considered, these observations suggest that individual miRNAs could act as potential mediators of the epigenetic switch linking transcriptomic dynamics and cell phenotypes mediated by TIA proteins.

The non-coding oncogene: a case of missing DNA evidence?

The evidence that links classical protein-coding proto-oncogenes and tumor suppressors, such as MYC, RAS, P53, and RB, to carcinogenesis is indisputable. Multiple lines of proof show how random somatic genomic alteration of such genes (e.g., mutation, deletion, or amplification), followed by selection and clonal expansion, forms the main molecular basis of tumor development. Many important cancer genes were discovered using low-throughput approaches in the pre-genomic era, and this knowledge is today solidified and expanded upon by modern genome-scale methodologies. In several recent studies, non-coding RNAs (ncRNAs), such as microRNAs and long ncRNAs (lncRNAs), have been shown to contribute to tumor development. However, in comparison with coding cancer genes, the genomic (DNA-level) evidence is sparse for ncRNAs. The coding proto-oncogenes and tumor suppressors that we know of today are major molecular hubs in both normal and malignant cells. The search for ncRNAs with tumor driver or suppressor roles therefore holds the additional promise of pinpointing important, biologically active, ncRNAs in a vast and largely uncharacterized non-coding transcriptome. Here, we assess the available DNA-level data that links non-coding genes to tumor development. We further consider historical, methodological, and biological aspects, and discuss future prospects of ncRNAs in cancer.