KCNQ1OT1 hypomethylation: a novel disguised genetic predisposition in sporadic pediatric adrenocortical tumors?

Molecular and Clinical Features of Adrenocortical Tumors in Beckwith-Wiedemann Spectrum

BACKGROUND/OBJECTIVES

Adrenocortical tumors (ACTs), including adrenocortical adenoma (ACA) and carcinoma (ACC), represent 0.3-0.4% of pediatric tumors. Beckwith-Wiedemann spectrum (BWSp) confer an increased risk of ACTs, but prognosis, management, and associated molecular characteristics are unclear.

METHODS

This paper combines a literature review of 54 published cases of BWSp-ACT with a report of one newly identified patient, totaling 55 cases with a confirmed BWSp clinical and/or molecular diagnosis.

RESULTS

Nineteen patients with ACA, 33 with ACC, and 3 with ACT of uncertain malignant potential (umACT) were included. Twenty patients had uniparental disomy of chromosome 11p15.5 (patUPD11), 11imprinting Center 2 Loss-of-methylation (IC2-LoM), and had 2 11p15 locus duplication. Eleven patients were diagnosed during cancer screening procedures, including two metastatic at diagnosis ACC.

CONCLUSIONS

Almost half of ACC patients reached the minimum score for clinical BWSp diagnosis only after ACC onset, suggesting that the BWSp score has limited value for the early diagnosis in such a setting. Two patients with metastatic ACC had a histopathological Wieneke score ≤2, not correlating with clinical malignancy and confirming limitations of the current histopathological classification, as previously documented. Ultrasound screening failed identifying the ACC before metastasis in two cases, indicating an urgent need to develop new strategies for screening of ACTs in BWSp. Furthermore, some cases of metastatic ACC exhibited unexpectedly indolent behavior despite being malignant.

Beckwith-Wiedemann syndrome: Clinical, histopathological and molecular study of two Tunisian patients and review of literature

Background

Beckwith–Wiedemann syndrome (BWS) is a rare overgrowth syndrome characterized by congenital malformations and predisposition to embryonic tumors. Loss of methylation of imprinting center 2 (IC2) is the most frequent alteration and rarely associated with tumors compared to paternal uniparental disomy of chromosome 11 (UPD(11)pat) and gain of methylation of imprinting center 1.

Methods

Our study aimed to describe the clinical, histopathological and genetic characteristics of two patients and establish genotype‐phenotype correlations. The clinical diagnosis was based on the criteria defined by the international expert consensus of BWS. Molecular study of 11p15.5 methylation status was assessed using methylation‐specific‐multiplex ligation probe amplification (MS‐MLPA).

Results

Patients were aged 12 months and 3 months and fulfilled the clinical score of BWS. MS‐MLPA showed molecular alterations consisting of loss of methylation in IC2 (IC2‐LOM) at the maternal allele for one patient and a mosaic UPD(11)pat for the second patient in whom follow‐up at 6months revealed adrenocortical carcinoma (ACC) with low grade of malignancy. Molecular subtypes guide the follow‐up and tumor surveillance, our major concern.

Conclusion

We have to take into account the psychological impact of a possible tumor whatever the underlying mechanism is. Nevertheless, the tumor risk remains high for UPD(11)pat. Our study extended the phenotype of BWS with absence of macrosomia in Tunisian patients, contrasting with literature, and added a supplementary case of ACC in the tumor spectrum of BWS patients with UPD(11)pat.

Adrenocortical Tumors in Children With Constitutive Chromosome 11p15 Paternal Uniparental Disomy: Implications for Diagnosis and Treatment

Pediatric adrenocortical tumors (ACTs) are rare and heterogeneous. Approximately 50% of children with ACT carry a germline TP53 variant; however, the genetic underpinning of remaining cases has not been elucidated. In patients having germline TP53 variants, loss of maternal chromosome 11 and duplication of the paternal copy [paternal uniparental disomy, (UPD)] occurs early in tumorigenesis and explains the overexpression of IGF2, the hallmark of pediatric ACT. Beckwith-Wiedemann syndrome (BWS) is also associated with overexpression of IGF2 due to disruption of the 11p15 loci, including segmental UPD. Here, we report six children with ACT with wild type TP53 and germline paternal 11p15 UPD. Median age of five girls and one boy was 3.2 years (range 0.5-11 years). Two patients met the criteria for BWS before diagnosis of ACT. However, ACT was the first and only manifestation of paternal 11p15 UPD in four children. Tumor weight ranged from 21.5 g to 550 g. Despite poor prognostic features at presentation, such as pulmonary metastasis, bilateral adrenal involvement, and large tumors, all patients are alive 8-21 years after cancer diagnosis. Our observations suggest that children with ACT and wild type TP53, irrespective of their age, should be screened for germline abnormalities in chromosome 11p15.

Preclinical and Clinical Epigenetic-Based Reconsideration of Beckwith-Wiedemann Syndrome

Epigenetics has achieved a profound impact in the biomedical field, providing new experimental opportunities and innovative therapeutic strategies to face a plethora of diseases. In the rare diseases scenario, Beckwith-Wiedemann syndrome (BWS) is a pediatric pathological condition characterized by a complex molecular basis, showing alterations in the expression of different growth-regulating genes. The molecular origin of BWS is associated with impairments in the genomic imprinting of two domains at the 11p15.5 chromosomal region. The first domain contains three different regions: insulin growth like factor gene (IGF2), H19, and abnormally methylated DMR1 region. The second domain consists of cell proliferation and regulating-genes such as CDKN1C gene encoding for cyclin kinase inhibitor its role is to block cell proliferation. Although most cases are sporadic, about 5-10% of BWS patients have inheritance characteristics. In the 11p15.5 region, some of the patients have maternal chromosomal rearrangements while others have Uniparental Paternal Disomy UPD(11)pat. Defects in DNA methylation cause alteration of genes and the genomic structure equilibrium leading uncontrolled cell proliferation, which is a typical tumorigenesis event. Indeed, in BWS patients an increased childhood tumor predisposition is observed. Here, we summarize the latest knowledge on BWS and focus on the impact of epigenetic alterations to an increased cancer risk development and to metabolic disorders. Moreover, we highlight the correlation between assisted reproductive technologies and this rare disease. We also discuss intriguing aspects of BWS in twinning. Epigenetic therapies in clinical trials have already demonstrated effectiveness in oncological and non-oncological diseases. In this review, we propose a potential "epigenetic-based" approaches may unveil new therapeutic options for BWS patients. Although the complexity of the syndrome is high, patients can be able to lead a normal life but tumor predispositions might impair life expectancy. In this sense epigenetic therapies should have a supporting role in order to guarantee a good prognosis.

Regulatory roles of long noncoding RNAs implicated in cancer hallmarks

Cancer cells acquire numerous biological properties (designated "cancer hallmarks"), such as cell survival and energy metabolism, that facilitate tumor growth and metastatic dissemination during development. To date, eight hallmarks of cancer have been identified that provide a logical framework for understanding the remarkable diversity of neoplastic diseases, as proposed by Douglas Hanahan and Robert A. Weinberg. Long noncoding RNAs (lncRNAs), a category of transcripts widely demonstrated to exert significant regulatory effects on biological processes, have attracted considerable research attention due to their association with the occurrence and development of cancer. The mechanisms by which lncRNAs exert their functions require elucidation to optimize their potential utility as alternative biomarkers and therapeutic targets during tumor occurrence and progression. In this review, we have discussed recent research progress on lncRNAs involved in various cancer hallmarks and their related mechanisms of action, with a view to providing an updated picture of their immense therapeutic potential in the fight against cancer.

lncRNA Epigenetic Landscape Analysis Identifies EPIC1 as an Oncogenic lncRNA that Interacts with MYC and Promotes Cell-Cycle Progression in Cancer

We characterized the epigenetic landscape of genes encoding long noncoding RNAs (lncRNAs) across 6,475 tumors and 455 cancer cell lines. In stark contrast to the CpG island hypermethylation phenotype in cancer, we observed a recurrent hypomethylation of 1,006 lncRNA genes in cancer, including EPIC1 (epigenetically-induced lncRNA1). Overexpression of EPIC1 is associated with poor prognosis in luminal B breast cancer patients and enhances tumor growth in vitro and in vivo. Mechanistically, EPIC1 promotes cell-cycle progression by interacting with MYC through EPIC1's 129-283 nt region. EPIC1 knockdown reduces the occupancy of MYC to its target genes (e.g., CDKN1A, CCNA2, CDC20, and CDC45). MYC depletion abolishes EPIC1's regulation of MYC target and luminal breast cancer tumorigenesis in vitro and in vivo.

Overexpression of long non-coding RNA KCNQ1OT1 is related to good prognosis via inhibiting cell proliferation in non-small cell lung cancer

Background

Lung cancer (LC) is the most common malignancy in the world. Many long non‐coding RNAs (lncRNAs) have been reported to be associated with LC; however, the function of KCNQ1OT1 in LC requires exploration.

Methods

We conducted in silico analysis with data from The Cancer Genome Atlas to investigate the association between KCNQ1OT1 and LC. A Kaplan–Meier plotter was used to analyze the function of KCNQ1OT1 on LC patient prognosis. Quantitative reverse transcription‐PCR (qRT‐PCR) was performed to confirm previous results. An A549 lung cancer cell was transfected with pcDNA‐KCNQ1OT1, and methyl thiazolyl tetrazolium assay was performed to investigate the function of KCNQ1OT1 on cell proliferation. in vivo assay was performed with nude mice.

Results

Bioinformatics analysis and qRT‐PCR indicated that KCNQ1OT1 expression was higher in stage I LC patients (P < 0.01), and survival analysis showed that high expression of KCNQ1OT1 in LC patients was associated with better prognosis (P < 0.05). qRT‐PCR showed a negative correlation between KCNQ1OT1 and Ki67 expression and tumor size (P < 0.01), which indicated that KCNQ1OT1 is associated with tumor growth in LC. There was no significant correlation between KCNQ1OT1 level and lymph node metastasis (P > 0.05). KCNQ1OT1 overexpression significantly inhibited cell proliferation and tumor growth in vitro and in vivo (P < 0.05).

Conclusion

Our preliminary data showed that KCNQ1OT1 is overexpressed in early stage LC and is correlated with better prognosis in LC patients, possibly by suppressing cell proliferation.

Long noncoding RNAs in development and cancer: potential biomarkers and therapeutic targets

Long noncoding RNAs are emerging as key players in various fundamental biological processes. We highlight the varied molecular mechanisms by which lncRNAs modulate gene expression in diverse cellular contexts and their role in early mammalian development in this review. Furthermore, it is being increasingly recognized that altered expression of lncRNAs is specifically associated with tumorigenesis, tumor progression and metastasis. We discuss various lncRNAs implicated in different cancer types with a focus on their clinical applications as potential biomarkers and therapeutic targets in the pathology of diverse cancers.

Long noncoding RNAs in development and cancer: potential biomarkers and therapeutic targets

Long noncoding RNAs are emerging as key players in various fundamental biological processes. We highlight the varied molecular mechanisms by which lncRNAs modulate gene expression in diverse cellular contexts and their role in early mammalian development in this review. Furthermore, it is being increasingly recognized that altered expression of lncRNAs is specifically associated with tumorigenesis, tumor progression and metastasis. We discuss various lncRNAs implicated in different cancer types with a focus on their clinical applications as potential biomarkers and therapeutic targets in the pathology of diverse cancers.

DNA methylation of channel-related genes in cancers

DNA methylation at CpG sites is an epigenetic mechanism that regulates cellular gene expression. In cancer cells, aberrant methylation is correlated with the abnormalities in expression of genes that are known to be involved in the particular characteristics of cancer cells such as proliferation, apoptosis, migration or invasion. During the past 30 years, accumulating data have definitely convinced the scientific community that ion channels are involved in cancerogenesis and cancer properties. As they are situated at the cell surface, they might be prime targets in the development of new therapeutic strategies besides their potential use as prognostic factors. Despite the progress in our understanding of the remodeling of ion channels in cancer cells, the molecular mechanisms underlying their over- or down-expression remained enigmatic. In this review, we aimed to summarize the available data on gene promoter methylation of ion channels and to investigate their clinical significance as novel biomarkers in cancer. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

LncRNA: a link between RNA and cancer

Unraveling the gene expression networks governing cancer initiation and development is essential while remains largely uncompleted. With the innovations in RNA-seq technologies and computational biology, long noncoding RNAs (lncRNAs) are being identified and characterized at a rapid pace. Recent findings reveal that lncRNAs are implicated in serial steps of cancer development. These lncRNAs interact with DNA, RNA, protein molecules and/or their combinations, acting as an essential regulator in chromatin organization, and transcriptional and post-transcriptional regulation. Their misexpression confers the cancer cell capacities for tumor initiation, growth, and metastasis. The review here will emphasize their aberrant expression and function in cancer, and the roles in cancer diagnosis and therapy will be also discussed.

Uncovering the role of genomic "dark matter" in human disease

The human genome encodes thousands of long noncoding RNAs (lncRNAs). Although most remain functionally uncharacterized biological "dark matter," lncRNAs have garnered considerable attention for their diverse roles in human biology, including developmental programs and tumor suppressor gene networks. As the number of lncRNAs associated with human disease grows, ongoing research efforts are focusing on their regulatory mechanisms. New technologies that enable enumeration of lncRNA interaction partners and determination of lncRNA structure are well positioned to drive deeper understanding of their functions and involvement in pathogenesis. In turn, lncRNAs may become targets for therapeutic intervention or new tools for biotechnology.