Gene Summary

Gene:KCNQ1; potassium voltage-gated channel subfamily Q member 1
Aliases: LQT, RWS, WRS, LQT1, SQT2, ATFB1, ATFB3, JLNS1, KCNA8, KCNA9, Kv1.9, Kv7.1, KVLQT1
Summary:This gene encodes a voltage-gated potassium channel required for repolarization phase of the cardiac action potential. This protein can form heteromultimers with two other potassium channel proteins, KCNE1 and KCNE3. Mutations in this gene are associated with hereditary long QT syndrome 1 (also known as Romano-Ward syndrome), Jervell and Lange-Nielsen syndrome, and familial atrial fibrillation. This gene exhibits tissue-specific imprinting, with preferential expression from the maternal allele in some tissues, and biallelic expression in others. This gene is located in a region of chromosome 11 amongst other imprinted genes that are associated with Beckwith-Wiedemann syndrome (BWS), and itself has been shown to be disrupted by chromosomal rearrangements in patients with BWS. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Aug 2011]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:potassium voltage-gated channel subfamily KQT member 1
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (23)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Genomic Imprinting
  • Promoter Regions
  • Cell Line
  • Molecular Sequence Data
  • Protein Folding
  • Chromosome 11
  • Protein-Serine-Threonine Kinases
  • Organic Cation Transport Proteins
  • Stomach Cancer
  • Wilms Tumour
  • Immunohistochemistry
  • Potassium Channels
  • Genome-Wide Association Study
  • Case-Control Studies
  • Loss of Heterozygosity
  • Genetic Predisposition
  • Beckwith-Wiedemann syndrome
  • Membrane Proteins
  • Base Sequence
  • Phenotype
  • Gene Expression Regulation
  • Cancer Gene Expression Regulation
  • beta Catenin
  • Tumor Suppressor Proteins
  • Nuclear Proteins
  • Long Noncoding RNA
  • KCNQ Potassium Channels
  • Messenger RNA
  • Single Nucleotide Polymorphism
  • Colorectal Cancer
  • KCNQ1 Potassium Channel
  • DNA Methylation
  • Genotype
  • Pregnancy
  • IGF2
  • Potassium Channels, Voltage-Gated
  • RNA, Untranslated
  • Alleles
  • Pedigree
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: KCNQ1 (cancer-related)

Ezzidi I, Mtiraoui N, Mohmmed Ali ME, et al.
Impact of variants on type-2 diabetes risk genes identified through genomewide association studies in polycystic ovary syndrome: a case-control study.
J Genet. 2018; 97(5):1213-1223 [PubMed] Related Publications
Polycystic ovary syndrome (PCOS) is a common endocrine disorder in females, and is associated with altered metabolic processes in particular insulin resistance and diabetes mellitus. PCOS shares with type-2 diabetes (T2D) a number of features, including beta cell dysfunction, impaired glucose tolerance and dyslipidaemia. Recently, genomewide association studies (GWAS) have reported a number of genes with reproducible associations and susceptibilities to T2D. To address this, we examined the association between the T2D GWAS candidate genes (

Fan H, Zhang M, Liu W
Hypermethylated KCNQ1 acts as a tumor suppressor in hepatocellular carcinoma.
Biochem Biophys Res Commun. 2018; 503(4):3100-3107 [PubMed] Related Publications
Potassium (K

Lu Q, Yu T, Ou X, et al.
Potential lncRNA diagnostic biomarkers for early gastric cancer.
Mol Med Rep. 2017; 16(6):9545-9552 [PubMed] Related Publications
Long noncoding RNAs (lncRNAs) serve important functions in many crucial biological processes; however, the effects of lncRNAs in early gastric cancer (EGC) are not entirely clear. The present study aimed to demonstrate the potential of lncRNAs to be used as biomarkers in EGC. Reverse transcription‑quantitative polymerase chain reaction was used to measure the expression levels of lncRNAs, including X inactive‑specific transcript (XIST), Yiya, brain cytoplasmic RNA 1 (BCYRN1), ribosomal RNA processing 1B (RRP1B), KCNQ1 opposite transcript 1 (KCNQ1OT1) and testes development related 1 (TDRG1), in EGC tissues compared with normal adjacent tissues (NATs). XIST, BCYRN1, RRP1B and TDRG1 were identified as differentially expressed in EGC tissues compared with NATs. The specificity and sensitivity of XIST, BCYRN1, RRP1B and TDRG1 were determined by receiver operating characteristic curve analysis. In addition, RRP1B expression was revealed to be significantly correlated with distal metastasis (P=0.020) and tumor‑node‑metastasis staging (P=0.018), and TDRG1 expression was significantly correlated with lymph node metastasis (P=0.001). Furthermore, BCYRN1, RRP1B and TDRG1 expression levels were compared between EGC tissues and plasma, and the results indicated that there were significant positive correlations of XIST, BCYRN1, RRP1B and TDRG1 expression levels between the EGC tissues and plasma. Therefore, the present study suggested that XIST, BCYRN1, RRP1B and TDRG1 may be served as potential diagnostic biomarkers for EGC.

Ren K, Xu R, Huang J, et al.
Knockdown of long non-coding RNA KCNQ1OT1 depressed chemoresistance to paclitaxel in lung adenocarcinoma.
Cancer Chemother Pharmacol. 2017; 80(2):243-250 [PubMed] Related Publications
Lung cancer, with the highest morbidity and second highest death rates, is one of the most common cancers in both males and females worldwide. Lung adenocarcinoma (LAD) is the main lung cancer class. KCNQ1 Opposite Strand/Antisense Transcript 1 (KCNQ1OT1) gene is an lncRNA which had been reported high-expression in colorectal cancer. In this study, the expression of KCNQ1OT1 was confirmed to be highly expressed in LAD tissues and cells contrast to control tissues and cells, and high KCNQ1OT1 expression correlated to malignant behaviors of LAD, including big tumor size, poor differentiation, positive lymphatic metastasis and high TNM stages. The transfection of si-KCNQ1OT1 could effectually knockdown the expression of KCNQ1OT1 in A549 and A549/PA cells. The KCNQ1OT1 knockdown depressed the proliferation and invasion of A549 cells, and advanced cellular apoptosis of A549 cells. The expression of KCNQ1OT1 in LAD patients insensitive to paclitaxel was much higher than that in LAD patients sensitive to paclitaxel; the KCNQ1OT1 expression in A549/PA cells was also much higher than that in control A549 cells. The half maximal inhibitory concentration (IC50) of paclitaxel in A549/PA cells was depressed by KCNQ1OT1 knockdown, chemoresistance of A549/PA cells was inhibited significantly. KCNQ1OT1 knockdown also depressed the expression of multidrug resistance 1 (MDR1) protein in A549/PA cells. In summary, lncRNA KCNQ1OT1 was highly expressed in LAD and functioned as a potential oncogene to inhibit malignancy and chemoresistance of LAD cells, which might be a novel potential therapeutic target for LAD.

Rapetti-Mauss R, Bustos V, Thomas W, et al.
Bidirectional KCNQ1:β-catenin interaction drives colorectal cancer cell differentiation.
Proc Natl Acad Sci U S A. 2017; 114(16):4159-4164 [PubMed] Free Access to Full Article Related Publications
The K

den Uil SH, Coupé VM, Linnekamp JF, et al.
Loss of KCNQ1 expression in stage II and stage III colon cancer is a strong prognostic factor for disease recurrence.
Br J Cancer. 2016; 115(12):1565-1574 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Colorectal cancer (CRC) is the third most common cancer worldwide. Accurately identifying stage II CRC patients at risk for recurrence is an unmet clinical need. KCNQ1 was previously identified as a tumour suppressor gene and loss of expression was associated with poor survival in patients with CRC liver metastases. In this study the prognostic value of KCNQ1 in stage II and stage III colon cancer patients was examined.
METHODS: KCNQ1 mRNA expression was assessed in 90 stage II colon cancer patients (AMC-AJCCII-90) using microarray gene expression data. Subsequently, KCNQ1 protein expression was evaluated in an independent cohort of 386 stage II and stage III colon cancer patients by immunohistochemistry of tissue microarrays.
RESULTS: Low KCNQ1 mRNA expression in stage II microsatellite stable (MSS) colon cancers was associated with poor disease-free survival (DFS) (P=0.025). Loss of KCNQ1 protein expression from epithelial cells was strongly associated with poor DFS in stage II MSS (P<0.0001), stage III MSS (P=0.0001) and stage III microsatellite instable colon cancers (P=0.041). KCNQ1 seemed an independent prognostic value in addition to other high-risk parameters like angio-invasion, nodal stage and microsatellite instability-status.
CONCLUSIONS: We conclude that KCNQ1 is a promising biomarker for prediction of disease recurrence and may aid stratification of patients with stage II MSS colon cancer for adjuvant chemotherapy.

Sunamura N, Ohira T, Kataoka M, et al.
Regulation of functional KCNQ1OT1 lncRNA by β-catenin.
Sci Rep. 2016; 6:20690 [PubMed] Free Access to Full Article Related Publications
Long noncoding RNAs (lncRNAs) have been implicated in many biological processes through epigenetic mechanisms. We previously reported that KCNQ1OT1, an imprinted antisense lncRNA in the human KCNQ1 locus on chromosome 11p15.5, is involved in cis-limited silencing within an imprinted KCNQ1 cluster. Furthermore, aberration of KCNQ1OT1 transcription was observed with a high frequency in colorectal cancers. However, the molecular mechanism of the transcriptional regulation and the functional role of KCNQ1OT1 in colorectal cancer remain unclear. Here, we show that the KCNQ1OT1 transcriptional level was significantly increased in human colorectal cancer cells in which β-catenin was excessively accumulated in the nucleus. Additionally, overexpression of β-catenin resulted in an increase in KCNQ1OT1 lncRNA-coated territory. On the other hand, knockdown of β-catenin resulted in significant decrease of KCNQ1OT1 lncRNA-coated territory and an increase in the mRNA expression of the SLC22A18 and PHLDA2 genes that are regulated by KCNQ1OT1. We showed that β-catenin can promote KCNQ1OT1 transcription through direct binding to the KCNQ1OT1 promoter. Our evidence indicates that β-catenin signaling may contribute to development of colorectal cancer by functioning as a novel lncRNA regulatory factor via direct targeting of KCNQ1OT1.

Chen J, Yao ZX, Chen JS, et al.
TGF-β/β2-spectrin/CTCF-regulated tumor suppression in human stem cell disorder Beckwith-Wiedemann syndrome.
J Clin Invest. 2016; 126(2):527-42 [PubMed] Free Access to Full Article Related Publications
Beckwith-Wiedemann syndrome (BWS) is a human stem cell disorder, and individuals with this disease have a substantially increased risk (~800-fold) of developing tumors. Epigenetic silencing of β2-spectrin (β2SP, encoded by SPTBN1), a SMAD adaptor for TGF-β signaling, is causally associated with BWS; however, a role of TGF-β deficiency in BWS-associated neoplastic transformation is unexplored. Here, we have reported that double-heterozygous Sptbn1+/- Smad3+/- mice, which have defective TGF-β signaling, develop multiple tumors that are phenotypically similar to those of BWS patients. Moreover, tumorigenesis-associated genes IGF2 and telomerase reverse transcriptase (TERT) were overexpressed in fibroblasts from BWS patients and TGF-β-defective mice. We further determined that chromatin insulator CCCTC-binding factor (CTCF) is TGF-β inducible and facilitates TGF-β-mediated repression of TERT transcription via interactions with β2SP and SMAD3. This regulation was abrogated in TGF-β-defective mice and BWS, resulting in TERT overexpression. Imprinting of the IGF2/H19 locus and the CDKN1C/KCNQ1 locus on chromosome 11p15.5 is mediated by CTCF, and this regulation is lost in BWS, leading to aberrant overexpression of growth-promoting genes. Therefore, we propose that loss of CTCF-dependent imprinting of tumor-promoting genes, such as IGF2 and TERT, results from a defective TGF-β pathway and is responsible at least in part for BWS-associated tumorigenesis as well as sporadic human cancers that are frequently associated with SPTBN1 and SMAD3 mutations.

Liu X, Chen Z, Zhao X, et al.
Effects of IGF2BP2, KCNQ1 and GCKR polymorphisms on clinical outcome in metastatic gastric cancer treated with EOF regimen.
Pharmacogenomics. 2015; 16(9):959-70 [PubMed] Related Publications
AIM: The present study analyzed Type 2 diabetes mellitus (T2D)-related gene polymorphisms and their impacts on chemotherapeutic response and survival in patients with metastatic gastric cancer (MGC).
PATIENTS & METHODS: This retrospective study enrolled 108 MGC patients treated with first-line EOF chemotherapy (epirubicin, oxaliplatin and 5-fluorouracil combination chemotherapy). Eleven single nucleotide polymorphisms of five T2D-related genes were determined.
RESULTS: Among the 11 single nucleotide polymorphisms, three (IGF2BP2 rs4402960, IGF2BP2 rs6769511 and KCNQ1 rs163182) were significantly associated with disease control rate and two (GCKR rs780093 and rs780094) were significantly associated with progression-free and overall survival.
CONCLUSION: Our results suggest IGF2BP2 and KCNQ1 polymorphisms might be independent predictors of chemotherapeutic response, while GCKR polymorphisms might be independent predictors of survival in MGC patients treated with first-line EOF chemotherapy. Original submitted 30 June 2014; revision submitted 15 April 2015.

Yoshizawa S, Fujiwara K, Sugito K, et al.
Pyrrole-imidazole polyamide-mediated silencing of KCNQ1OT1 expression induces cell death in Wilms' tumor cells.
Int J Oncol. 2015; 47(1):115-21 [PubMed] Related Publications
KvDMR (an intronic CpG island within the KCNQ1 gene) is one of the imprinting control regions on human chromosome 11p15.5. Since KvDMR exists within the promoter region of KCNQ1OT1 (antisense transcript of KCNQ1), it is likely that genomic alterations of this region including deletion, paternal uniparental disomy and de-methylation in maternal allele lead to aberrant overexpression of KCNQ1OT1. Indeed, de-methylation of KvDMR accompanied by uncontrolled overexpression of KCNQ1OT1 occurs frequently in Beckwith-Wiedemann syndrome (BWS), and around 10% of BWS patients developed embryonal tumors (Wilms' tumor or hepatoblastoma). These observations strongly suggest that silencing of KCNQ1OT1 expression might suppress its oncogenic potential. In the present study, we designed two pyrrole-imidazole (PI) polyamides, termed PI-a and PI-b, which might have the ability to bind to CCAAT boxes of the KCNQ1OT1 promoter region, and investigated their possible antitumor effect on Wilms' tumor-derived G401 cells. Gel retardation assay demonstrated that PI-a and PI-b specifically bind to their target sequences. Microscopic observations showed the efficient nuclear access of these PI polyamides. Quantitative real-time PCR analysis revealed that the expression level of KCNQ1OT1 was significantly decreased when treated with PI-a and PI-b simultaneously but not with either PI-a or PI-b single treatment. Consistent with these results, the combination of PI-a and PI-b resulted in a significant reduction in viability of G401 cells in a dose-dependent manner. Furthermore, FACS analysis demonstrated that combinatory treatment with PI-a and PI-b induces cell death as compared with control cells. Taken together, our present observations strongly suggest that the combinatory treatment with PI polyamides targeting KCNQ1OT1 might be a novel therapeutic strategy to cure patients with tumors over-expressing KCNQ1OT1.

Kuruma S, Egawa N, Kurata M, et al.
Case-control study of diabetes-related genetic variants and pancreatic cancer risk in Japan.
World J Gastroenterol. 2014; 20(46):17456-62 [PubMed] Free Access to Full Article Related Publications
AIM: To examine whether diabetes-related genetic variants are associated with pancreatic cancer risk.
METHODS: We genotyped 7 single-nucleotide polymorphisms (SNPs) in PPARG2 (rs1801282), ADIPOQ (rs1501299), ADRB3 (rs4994), KCNQ1 (rs2237895), KCNJ11 (rs5219), TCF7L2 (rs7903146), and CDKAL1 (rs2206734), and examined their associations with pancreatic cancer risk in a multi-institute case-control study including 360 cases and 400 controls in Japan. A self-administered questionnaire was used to collect detailed information on lifestyle factors. Genotyping was performed using Fluidigm SNPtype assays. Unconditional logistic regression methods were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between these diabetes-associated variants and pancreatic cancer risk.
RESULTS: With the exception of rs1501299 in the ADIPOQ gene (P = 0.09), no apparent differences in genotype frequencies were observed between cases and controls. Rs1501299 in the ADPIOQ gene was positively associated with pancreatic cancer risk; compared with individuals with the AA genotype, the age- and sex-adjusted OR was 1.79 (95%CI: 0.98-3.25) among those with the AC genotype and 1.86 (95%CI: 1.03-3.38) among those with the CC genotype. The ORs remained similar after additional adjustment for body mass index and cigarette smoking. In contrast, rs2237895 in the KCNQ1 gene was inversely related to pancreatic cancer risk, with a multivariable-adjusted OR of 0.62 (0.37-1.04) among individuals with the CC genotype compared with the AA genotype. No significant associations were noted for other 5 SNPs.
CONCLUSION: Our case-control study indicates that rs1501299 in the ADIPOQ gene may be associated with pancreatic cancer risk. These findings should be replicated in additional studies.

Girault A, Privé A, Trinh NT, et al.
Identification of KvLQT1 K+ channels as new regulators of non-small cell lung cancer cell proliferation and migration.
Int J Oncol. 2014; 44(3):838-48 [PubMed] Related Publications
K+ channels, which are overexpressed in several cancers, have been identified as regulators of cell proliferation and migration, key processes in cancer development/propagation. Their role in lung cancer has not been studied extensively; but we showed previously that KvLQT1 channels are involved in cell migration, proliferation and repair of normal lung epithelial cells. We now investigated the role of these channels in lung cancer cell lines and their expression levels in human lung adenocarcinoma (AD) tissues. First, we observed that the wound-healing rates of A549 lung adenocarcinoma cell monolayers were reduced by clofilium and chromanol or after silencing with KvLQT1-specific siRNA. Dose-dependent decrease of A549 cell growth and cell accumulation in G0/G1 phase were seen after KvLQT1 inhibition. Clofilium also affected 2D and 3D migration of A549 cells. Similarly, H460 cell growth, migration and wound healing were diminished by this drug. Because K+ channel overexpression has been encountered in some cancers, we assessed KvLQT1 expression levels in tumor tissues from patients with lung AD. KvLQT1 protein expression in tumor samples was increased by 1.5- to 7-fold, compared to paired non-neoplastic tissues, in 17 of 26 patients. In summary, our data reveal that KvLQT1 channel blockade efficiently reduces A549 and H460 cell proliferation and migration. Moreover, KvLQT1 overexpression in AD samples suggests that it could be a potential therapeutic target in lung cancer.

Shimizu T, Fujii T, Takahashi Y, et al.
Up-regulation of Kv7.1 channels in thromboxane A2-induced colonic cancer cell proliferation.
Pflugers Arch. 2014; 466(3):541-8 [PubMed] Related Publications
Thromboxane A2 (TXA2) is known to stimulate colonic cancer cell proliferation, although the mechanism has not been clarified. In this study, we compared the expression levels of Kv7.1 K(+) channels between human colorectal cancer tissue and the accompanying non-tumor mucosa. Kv7.1 proteins were found to be consistently up-regulated in the cancer tissues from different patients. Kv7.1 was also expressed in human colonic cancer cell lines. Treatment of colonic cancer cells with 9,11-epithio-11,12-methano-thromboxane A2 (STA2), a stable analogue of TXA2, significantly increased whole-cell K(+) currents sensitive to chromanol 293B, an inhibitor of Kv7.1 channels, in parallel with an increased expression of Kv7.1 proteins. In contrast, TXB2, an inactive metabolite of TXA2, had no effects on expression level and function of Kv7.1. A TXA2 receptor antagonist (SQ29548) and an inhibitor of cAMP-dependent protein kinase (Rp-8-Br-MB-cAMPS) inhibited STA2-induced increases in both Kv7.1 expression and chromanol 293B-sensitive K(+) currents. Interestingly, STA2-stimulated proliferation of colonic cancer cells was inhibited by chromanol 293B. These results suggest that Kv7.1 channels are involved in the TXA2-induced cancer cell proliferation and that they are up-regulated by the TXA2 receptor-mediated cAMP pathway.

Wan J, Huang M, Zhao H, et al.
A novel tetranucleotide repeat polymorphism within KCNQ1OT1 confers risk for hepatocellular carcinoma.
DNA Cell Biol. 2013; 32(11):628-34 [PubMed] Related Publications
KCNQ1 overlapping transcript 1 (KCNQ1OT1), a long noncoding RNA responsible for silencing a cluster of genes in cis, has been shown to be involved in multiple cancers. However, much remains unclear of how KCNQ1OT1 contributes to carcinogenesis. By thoroughly analyzing 510 hepatocellular carcinoma (HCC) cases and 1014 healthy controls in a Chinese population, we identified a novel short tandem repeat (STR) polymorphism (rs35622507) within the KCNQ1OT1 coding region and evaluated its association with HCC susceptibility. Logistic regression analysis showed that compared with individuals carrying the homozygote 10-10 genotype, those heterozygote subjects who carry only one allele 10 had a significantly decreased risk of HCC (adjusted odds ratio [OR]=0.67, 95% confidence interval [CI]=0.53-0.86, p=0.0009), with the risk decreased even further in those without allele 10 (adjusted OR=0.38, 95% CI=0.21-0.69, p=0.0005). Furthermore, genotype-phenotype correlation studies using four hepatoma cell lines support a significant association between STR genotypes and the expression of KCNQ1OT1. Cell lines without allele 10 conferred a 20.9-33.3-fold higher expression of KCNQ1OT1. Meanwhile, KCNQ1OT1 expression was reversely correlated with the expression of the cyclin-dependent kinase inhibitor 1C (CDKN1C), a tumor suppressor gene located within the CDKN1C/KCNQ1OT1 imprinted region, in three hepatoma cell lines. Finally, in silico prediction suggested that different alleles could alter the local structure of KCNQ1OT1. Taken together, our findings suggest that the STR polymorphism within KCNQ1OT1 contributes to hepatocarcinogenesis, possibly by affecting KCNQ1OT1 and CDKN1C expression through a structure-dependent mechanism. The replication of our studies and further functional studies are needed to validate our hypothesis and understand the roles of KCNQ1OT1 polymorphisms in predisposition for HCC.

Than BL, Goos JA, Sarver AL, et al.
The role of KCNQ1 in mouse and human gastrointestinal cancers.
Oncogene. 2014; 33(29):3861-8 [PubMed] Free Access to Full Article Related Publications
Kcnq1, which encodes for the pore-forming α-subunit of a voltage-gated potassium channel, was identified as a gastrointestinal (GI) tract cancer susceptibility gene in multiple Sleeping Beauty DNA transposon-based forward genetic screens in mice. To confirm that Kcnq1 has a functional role in GI tract cancer, we created Apc(Min) mice that carried a targeted deletion mutation in Kcnq1. Results demonstrated that Kcnq1 is a tumor suppressor gene as Kcnq1 mutant mice developed significantly more intestinal tumors, especially in the proximal small intestine and colon, and some of these tumors progressed to become aggressive adenocarcinomas. Gross tissue abnormalities were also observed in the rectum, pancreas and stomach. Colon organoid formation was significantly increased in organoids created from Kcnq1 mutant mice compared with wild-type littermate controls, suggesting a role for Kcnq1 in the regulation of the intestinal crypt stem cell compartment. To identify gene expression changes due to loss of Kcnq1, we carried out microarray studies in the colon and proximal small intestine. We identified altered genes involved in innate immune responses, goblet and Paneth cell function, ion channels, intestinal stem cells, epidermal growth factor receptor and other growth regulatory signaling pathways. We also found genes implicated in inflammation and in cellular detoxification. Pathway analysis using Ingenuity Pathway Analysis and Gene Set Enrichment Analysis confirmed the importance of these gene clusters and further identified significant overlap with genes regulated by MUC2 and CFTR, two important regulators of intestinal homeostasis. To investigate the role of KCNQ1 in human colorectal cancer (CRC), we measured protein levels of KCNQ1 by immunohistochemistry in tissue microarrays containing samples from CRC patients with liver metastases who had undergone hepatic resection. Results showed that low expression of KCNQ1 expression was significantly associated with poor overall survival.

Hayashi M, Novak I
Molecular basis of potassium channels in pancreatic duct epithelial cells.
Channels (Austin). 2013 Nov-Dec; 7(6):432-41 [PubMed] Free Access to Full Article Related Publications
Potassium channels regulate excitability, epithelial ion transport, proliferation, and apoptosis. In pancreatic ducts, K(+) channels hyperpolarize the membrane potential and provide the driving force for anion secretion. This review focuses on the molecular candidates of functional K(+) channels in pancreatic duct cells, including KCNN4 (KCa 3.1), KCNMA1 (KCa 1.1), KCNQ1 (Kv 7.1), KCNH2 (Kv 11.1), KCNH5 (Kv 10.2), KCNT1 (KCa 4.1), KCNT2 (KCa 4.2), and KCNK5 (K 2P 5.1). We will give an overview of K(+) channels with respect to their electrophysiological and pharmacological characteristics and regulation, which we know from other cell types, preferably in epithelia, and, where known, their identification and functions in pancreatic ducts and in adenocarcinoma cells. We conclude by pointing out some outstanding questions and future directions in pancreatic K(+) channel research with respect to the physiology of secretion and pancreatic pathologies, including pancreatitis, cystic fibrosis, and cancer, in which the dysregulation or altered expression of K(+) channels may be of importance.

Egashira T, Yuasa S, Suzuki T, et al.
Disease characterization using LQTS-specific induced pluripotent stem cells.
Cardiovasc Res. 2012; 95(4):419-29 [PubMed] Related Publications
AIMS: Long QT syndrome (LQTS) is an inheritable and life-threatening disease; however, it is often difficult to determine disease characteristics in sporadic cases with novel mutations, and more precise analysis is necessary for the successful development of evidence-based clinical therapies. This study thus sought to better characterize ion channel cardiac disorders using induced pluripotent stem cells (iPSCs).
METHODS AND RESULTS: We reprogrammed somatic cells from a patient with sporadic LQTS and from controls, and differentiated them into cardiomyocytes through embryoid body (EB) formation. Electrophysiological analysis of the LQTS-iPSC-derived EBs using a multi-electrode array (MEA) system revealed a markedly prolonged field potential duration (FPD). The IKr blocker E4031 significantly prolonged FPD in control- and LQTS-iPSC-derived EBs and induced frequent severe arrhythmia only in LQTS-iPSC-derived EBs. The IKs blocker chromanol 293B did not prolong FPD in the LQTS-iPSC-derived EBs, but significantly prolonged FPD in the control EBs, suggesting the involvement of IKs disturbance in the patient. Patch-clamp analysis and immunostaining confirmed a dominant-negative role for 1893delC in IKs channels due to a trafficking deficiency in iPSC-derived cardiomyocytes and human embryonic kidney (HEK) cells.
CONCLUSIONS: This study demonstrated that iPSCs could be useful to characterize LQTS disease as well as drug responses in the LQTS patient with a novel mutation. Such analyses may in turn lead to future progress in personalized medicine.

Arai E, Chiku S, Mori T, et al.
Single-CpG-resolution methylome analysis identifies clinicopathologically aggressive CpG island methylator phenotype clear cell renal cell carcinomas.
Carcinogenesis. 2012; 33(8):1487-93 [PubMed] Free Access to Full Article Related Publications
To clarify the significance of DNA methylation alterations during renal carcinogenesis, methylome analysis using single-CpG-resolution Infinium array was performed on 29 normal renal cortex tissue (C) samples, 107 non-cancerous renal cortex tissue (N) samples obtained from patients with clear cell renal cell carcinomas (RCCs) and 109 tumorous tissue (T) samples. DNA methylation levels at 4830 CpG sites were already altered in N samples compared with C samples. Unsupervised hierarchical clustering analysis based on DNA methylation levels at the 801 CpG sites, where DNA methylation alterations had occurred in N samples and were inherited by and strengthened in T samples, clustered clear cell RCCs into Cluster A (n = 90) and Cluster B (n = 14). Clinicopathologically aggressive tumors were accumulated in Cluster B, and the cancer-free and overall survival rates of patients in this cluster were significantly lower than those of patients in Cluster A. Clear cell RCCs in Cluster B were characterized by accumulation of DNA hypermethylation on CpG islands and considered to be CpG island methylator phenotype (CIMP)-positive cancers. DNA hypermethylation of the CpG sites on the FAM150A, GRM6, ZNF540, ZFP42, ZNF154, RIMS4, PCDHAC1, KHDRBS2, ASCL2, KCNQ1, PRAC, WNT3A, TRH, FAM78A, ZNF671, SLC13A5 and NKX6-2 genes became hallmarks of CIMP in RCCs. On the other hand, Cluster A was characterized by genome-wide DNA hypomethylation. These data indicated that DNA methylation alterations at precancerous stages may determine tumor aggressiveness and patient outcome. Accumulation of DNA hypermethylation on CpG islands and genome-wide DNA hypomethylation may each underlie distinct pathways of renal carcinogenesis.

Lang F, Stournaras C
Serum and glucocorticoid inducible kinase, metabolic syndrome, inflammation, and tumor growth.
Hormones (Athens). 2013 Apr-Jun; 12(2):160-71 [PubMed] Related Publications
Serum-and-glucocorticoid-inducible-kinase-1 (SGK1) is under regulation of several hormones, mediators and cell stressors. More specifically, SGK1 expression is particularly sensitive to glucocorticoids, mineralocorticoids, and TGFβ. Moreover, SGK1 expression is exquisitely sensitive to hypertonicity, hyperglycemia, and ischemia. SGK1 is activated by insulin and growth factors via phosphatidylinositol-3-kinase, 3-phosphoinositide dependent-kinase PDK1, and mTOR. SGK1 up-regulates the Na⁺/K⁺-ATPase, a variety of carriers (e.g. NCC, NKCC, NHE1, NHE3, SGLT1, several amino acid transporters) and many ion channels (e.g. ENaC, SCN5A, TRPV4-6, Orai1/STIM1, ROMK, KCNE1/KCNQ1, GluR6, CFTR). SGK1 further up-regulates a number of enzymes (e.g. glycogen-synthase-kinase-3, ubiquitin-ligase Nedd4-2), and transcription factors (e.g. forkhead-transcription-factor FOXO3a, β-catenin, nuclear-factor-kappa-B NFκB). SGK1 sensitive functions contribute to regulation of epithelial transport, excitability, degranulation, matrix protein deposition, coagulation, platelet aggregation, migration, cell proliferation, and apoptosis. Apparently, SGK1 is not required for housekeeping functions, as the phenotype of SGK1 knockout mice is mild. However, excessive SGK1 expression and activity participates in the pathophysiology of several disorders, including hypertension, obesity, diabetes, thrombosis, stroke, inflammation, autoimmune disease, fibrosis, and tumor growth. A SGK1 gene variant (prevalence ~3-5% prevalence in Caucasians, ~10% in Africans) predisposes to hypertension, stroke, obesity, and type 2 diabetes. Moreover, excessive salt intake and/or excessive release of glucocorticoids, mineralocorticoids, and TGFβ up-regulates SGK1 expression thus predisposing to SGK1-related diseases.

Kim JC, Lee HC, Cho DH, et al.
Genome-wide identification of possible methylation markers chemosensitive to targeted regimens in colorectal cancers.
J Cancer Res Clin Oncol. 2011; 137(10):1571-80 [PubMed] Related Publications
PURPOSE: Few efficient methylation markers of chemosensitivity have been discovered. The genome-wide analysis of methylation markers is needed to identify chemosensitive candidates to targeted therapy.
METHODS: This study describes a two-step process to select chemosensitive candidates of methylation genes. A genome-wide screening of methylation genes was performed using a Beadarray and an in vitro chemosensitivity assay of 119 colorectal cancers (CRCs). Ten candidate genes identified during the initial screening were verified by biological utility assessment using cell viability assays of transfected CRC cells.
RESULTS: Five methylation genes related to sensitivity to bevacizumab regimens (RASSF1, MMP25, KCNQ1, ESR1, and GALR2) or cetuximab regimens (SCL18A2, GPX7, NID2, IGFBP3, and ALX4) were chosen during the first step. A viability assay revealed that GALR2-overexpressing HCT116 cells were significantly more chemosensitive to bevacizumab regimens than control cells (P = 0.022 and 0.019 for bevacizumab with FOLFIRI and FOLFOX, respectively), concurrently verified on a caspase-3 activity assay. GPX7- or ALX4-overexpressed RKO cells were significantly less viable to cetuximab regimens compared to control cells (GPX7: P = 0.027 each for cetuximab with FOLFIRI and FOLFOX; ALX4: P = 0.049 and 0.003 for cetuximab with FOLFIRI and FOLFOX, respectively), but caspase-3 activity was not prominent in GPX7-overexpressed RKO cells.
CONCLUSIONS: Two novel genes, GALR2 and ALX4, have been identified as chemosensitive methylation candidates to bevacizumab and cetuximab regimens, respectively. As our study did not include a clinical association study, the two candidates should be validated in large clinical cohorts, hopefully predicting responsive patients to targeted regimens.

Roepke TK, Purtell K, King EC, et al.
Targeted deletion of Kcne2 causes gastritis cystica profunda and gastric neoplasia.
PLoS One. 2010; 5(7):e11451 [PubMed] Free Access to Full Article Related Publications
Gastric cancer is the second leading cause of cancer death worldwide. Predisposing factors include achlorhydria, Helicobacter pylori infection, oxyntic atrophy and TFF2-expressing metaplasia. In parietal cells, apical potassium channels comprising the KCNQ1 alpha subunit and the KCNE2 beta subunit provide a K(+) efflux current to facilitate gastric acid secretion by the apical H(+)K(+)ATPase. Accordingly, genetic deletion of murine Kcnq1 or Kcne2 impairs gastric acid secretion. Other evidence has suggested a role for KCNE2 in human gastric cancer cell proliferation, independent of its role in gastric acidification. Here, we demonstrate that 1-year-old Kcne2(-/-) mice in a pathogen-free environment all exhibit a severe gastric preneoplastic phenotype comprising gastritis cystica profunda, 6-fold increased stomach mass, increased Ki67 and nuclear Cyclin D1 expression, and TFF2- and cytokeratin 7-expressing metaplasia. Some Kcne2(-/-) mice also exhibited pyloric polypoid adenomas extending into the duodenum, and neoplastic invasion of thin walled vessels in the sub-mucosa. Finally, analysis of human gastric cancer tissue indicated reduced parietal cell KCNE2 expression. Together with previous findings, the results suggest KCNE2 disruption as a possible risk factor for gastric neoplasia.

Paulin FL, Klein GJ, Gula LJ, et al.
QT prolongation and monomorphic VT caused by pheochromocytoma.
J Cardiovasc Electrophysiol. 2009; 20(8):931-4 [PubMed] Related Publications
INTRODUCTION: Pheochromocytoma may present with ECG abnormalities as one of the few clues to the diagnosis.
METHODS AND RESULTS: A 30-year-old woman presented with chest pain and a QTc of 525 ms. Four weeks later following a syncopal episode, her QTc was 660 ms. Short runs of monomorphic ventricular tachycardia were recorded. Investigations revealed an adrenal pheochromocytoma. Her QTc normalized after excision of the tumor. Comprehensive QT gene screening of KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 was negative.
CONCLUSION: Pheochromocytoma may induce monomorphic VT and QT prolongation. The interaction of different catecholamines may have a compounding effect on cardiac repolarization.

Morokuma J, Blackiston D, Adams DS, et al.
Modulation of potassium channel function confers a hyperproliferative invasive phenotype on embryonic stem cells.
Proc Natl Acad Sci U S A. 2008; 105(43):16608-13 [PubMed] Free Access to Full Article Related Publications
Ion transporters, and the resulting voltage gradients and electric fields, have been implicated in embryonic development and regeneration. These biophysical signals are key physiological aspects of the microenvironment that epigenetically regulate stem and tumor cell behavior. Here, we identify a previously unrecognized function for KCNQ1, a potassium channel known to be involved in human Romano-Ward and Jervell-Lange-Nielsen syndromes when mutated. Misexpression of its modulatory wild-type beta-subunit XKCNE1 in the Xenopus embryo resulted in a striking alteration of the behavior of one type of embryonic stem cell: the pigment cell lineage of the neural crest. Depolarization of embryonic cells by misexpression of KCNE1 non-cell-autonomously induced melanocytes to overproliferate, spread out, and become highly invasive of blood vessels, liver, gut, and neural tube, leading to a deeply hyperpigmented phenotype. This effect is mediated by the up-regulation of Sox10 and Slug genes, thus linking alterations in ion channel function to the control of migration, shape, and mitosis rates during embryonic morphogenesis. Taken together, these data identify a role for the KCNQ1 channel in regulating key cell behaviors and reveal the molecular identity of a biophysical switch, by means of which neoplastic-like properties can be conferred upon a specific embryonic stem cell subpopulation.

Kim KP, Thurston A, Mummery C, et al.
Gene-specific vulnerability to imprinting variability in human embryonic stem cell lines.
Genome Res. 2007; 17(12):1731-42 [PubMed] Free Access to Full Article Related Publications
Disregulation of imprinted genes can be associated with tumorigenesis and altered cell differentiation capacity and so could provide adverse outcomes for stem cell applications. Although the maintenance of mouse and primate embryonic stem cells in a pluripotent state has been reported to disrupt the monoallelic expression of several imprinted genes, available data have suggested relatively higher imprint stability in the human equivalents. Identification of 202 heterozygous loci allowed us to examine the allelic expression of 22 imprinted genes in 22 human embryonic stem cell lines. Half of the genes examined (IPW, H19, MEG3, MEST isoforms 1 and 2, PEG10, MESTIT1, NESP55, ATP10A, PHLDA2, IGF2) showed variable allelic expression between lines, indicating vulnerability to disrupted imprinting. However, seven genes showed consistent monoallelic expression (NDN, MAGEL2, SNRPN, PEG3, KCNQ1, KCNQ1OT1, CDKN1C). Furthermore, four genes known to be monoallelic or to exhibit polymorphic imprinting in later-developing human tissues (TP73, IGF2R, WT1, SLC22A18) were always biallelic in hESCs. MEST isoform 1, PEG10, and NESP55 showed an association between the variability observed in interline allelic expression status and the DNA methylation of previously identified regulatory regions. Our results demonstrate gene-specific differences in the stability of imprinted loci in human embryonic stem cells and identify disrupted DNA methylation as one potential mechanism. We conclude the prudence of including comprehensive imprinting analysis in the continued characterization of human embryonic stem cell lines.

Bjornsson HT, Brown LJ, Fallin MD, et al.
Epigenetic specificity of loss of imprinting of the IGF2 gene in Wilms tumors.
J Natl Cancer Inst. 2007; 99(16):1270-3 [PubMed] Free Access to Full Article Related Publications
Loss of imprinting (LOI) of the IGF2 gene (which encodes insulin-like growth factor II) is the most common genetic or epigenetic alteration in Wilms tumor; LOI involves aberrant activation of the normally repressed maternally inherited allele. We found previously that LOI of IGF2 occurs in approximately half of all Wilms tumors (i.e., those arising from lineage-committed nephrogenic progenitor cells). We investigated whether LOI of IGF2 is associated with relaxation of imprinting at loci other than IGF2 or with widespread alterations in DNA methylation. We stratified 59 Wilms tumor samples by IGF2 LOI status by use of hot-stop reverse transcription-polymerase chain reaction and/or methylation analysis of the differentially methylated region of the H19 gene and identified 31 samples with and 28 without LOI. We used quantitative allele-specific expression analysis to determine whether six other imprinted genes (i.e., H19, KCNQ1, LIT1, TSSC5, GRB10, and MEG3) had subtle LOI. No statistically significant difference in allele-specific expression between Wilms tumor with or without LOI was found for LIT1, TSSC5, GRB10, and MEG3. For the KCNQ1 gene there was a slight difference between the groups with (37.0%, 95% confidence interval [CI] = 31.8% to 42.2%) and without (27.7%, 95% CI = 21.8% to 33.5%) LOI (P = .02 for F test of group differences in a mixed-effects model). For H19, we also found a slight difference between the groups with (7.5%, 95% CI = 2.4% to 12.7%) and without (2.2%, 95% CI = -3.2% to 7.6%) LOI of IGF2 (P = .15 for F test). In 27 tumor samples, we also used a microarray technique to analyze methylation of 378 genes, 38 of which were suspected or confirmed imprinted genes. We found that statistically significant alterations in only the differentially methylated region of the H19 gene were associated with LOI of IGF2. Thus, epigenetic alterations in Wilms tumors are not widespread, supporting the gene and lineage specificity of LOI of IGF2.

Stathopoulos A, Melas C, Attali B, et al.
Overexpression of mouse IsK protein fused to green fluorescent protein induces apoptosis of human astroglioma cells.
Neurol Res. 2007; 29(6):628-31 [PubMed] Related Publications
Intracellular K(+) plays an important role in controlling ion homeostasis for maintaining cell volume and inhibiting activity of pro-apoptotic enzymes. Cytoplasmic K(+) concentration is regulated by K(+) uptake via Na(+) -K(+) -ATPase and K(+) efflux through K(+) channels in the plasma membrane. The IsK (KCNE1) protein is known to co-assemble with KCNQ1 (KvLQT1) protein to form a K(+) channel underlying the slowly activating delayed rectifier K(+) outward current which delays voltage activation. In order to further study the activity and cellular localization of IsK protein, we constructed a C-terminal fusion of IsK with EGFP (enhanced green fluorescent protein). Expression of the fusion protein appeared as clusters located in the plasma membrane and induced degeneration of both transiently or stably transfected cells.

Kato H, Wake N
Differential diagnosis between complete and partial mole using a TSSC3 antibody: correlation with DNA polymorphic marker analysis.
J Reprod Med. 2006; 51(11):861-7 [PubMed] Related Publications
OBJECTIVE: To investigate the use of maternally expressed, imprinted genes for the differential diagnosis of complete hydatidiform mole (CHM) and partial hydatidiform mole (PHM).
STUDY DESIGN: Expression patterns of imprinted genes in CHM were validat ed by microarray analysis. Twenty CHMs and 10 PHMs were then subjected to Western blot analysis and immunostaining with appropriate antibodies.
RESULTS: TSSC3 (also known as PHLDA2, IPL), SLC22A1L, KCNQ1 and decorin were shown to be down-regulated, with the suppression of TSSC3 most marked. In all 20 CHM cases for which the diagnosis had been confirmed by DNA polymorphic markers, the expression of TSSC3 was completely lost on Western blots. In contrast, in 10 PHMs that had also been diagnosed by DNA analysis, TSSC3 was expressed normally. Immunohistochemistry showed an identical result.
CONCLUSION: Complete silencing of TSSC3 expression in CHM offers a convenient and novel diagnostic strategy for diagnosing molar lesions.

Feinberg AP
A genetic approach to cancer epigenetics.
Cold Spring Harb Symp Quant Biol. 2005; 70:335-41 [PubMed] Related Publications
In over 20 years since the discovery of altered methylation in cancer, many epigenetic alterations have been found in human cancer, including global and specific gene hypomethylation, hypermethylation, altered chromatin marks, and loss of genomic imprinting. Cancer epigenetics has been limited by questions of cause and effect, since epigenetic changes can arise secondary to the cancer process and its associated widespread changes in gene expression. Furthermore, mutations in the DNA methylation machinery have not been observed in tumors, whereas they have been for chromatin modification. To address the issue of human cancer etiology, we have taken a genetic approach to cancer epigenetics. One line of investigation has been on the disorder Beckwith-Wiedemann syndrome (BWS). We have found that loss of imprinting (LOI) of the autocrine growth factor gene IGF2 and of the untranslated antisense RNA LIT1, within the K(V)LQT1 gene, account for most cases of BWS, and that cancer risk is specifically associated with LOI of IGF2. Wilms' tumors, both in BWS and in the general population, involve LOI leading to an expansion of nephrogenic precursor cells. We have also developed an animal model for the role of LOI of IGF2 in cancer, showing that it cooperates with Apc mutations to increase cancer frequency, consistent with human data suggesting a severalfold increased cancer risk for this common epigenetic variant in the adult population. These data suggest that a major component of cancer risk involves epigenetic changes in normal cells that increase the probability of cancer after genetic mutation. They suggest a model of cancer prevention that involves the epigenetic analysis of normal cells for risk stratification and cancer prevention strategies.

Gallagher E, Mc Goldrick A, Chung WY, et al.
Gain of imprinting of SLC22A18 sense and antisense transcripts in human breast cancer.
Genomics. 2006; 88(1):12-7 [PubMed] Related Publications
The 11p15.5 region harbors three imprinted sense/antisense transcript pairs, SLC22A18/SLC22A18AS, IGF2/IGF2AS (PEG8), and KCNQ1/KCNQ1OT1 (LIT1). SLC22A18 (solute carrier family 22 (organic cation transporter) member 18) and its antisense transcript SLC22A18AS are paternally suppressed in fetal samples. In adult tissue, SLC22A18 displays polymorphic imprinting, but the imprinting status of SLC22A18AS remains elusive. SLC22AI8 DNA-PCR-RFLP analysis using NlaIII restriction digestion identified SLC22A18 heterozygotes within this breast tissue cohort (n = 89). Commercial sequencing identified informative SLC22A18AS samples. Random hexamer-primed cDNA synthesis, SLC22A18/SLC22A18AS-specific PCR, and imprinting evaluation by commercial sequencing demonstrated that SLC22A18AS displays a nonimprinted profile in reduction mastectomies (n = 6). However, SLC22A18 showed a gain of imprinting (GOI) in 1/4 of these normal cases. In the malignant cohort, GOI was also demonstrated in 18% for SLC22A18 and 14% for SLC22A18AS, occurring concomitantly in one case. This study reports the imprinting status of SLC22A18AS in adult tissue, and shows that GOI affects both the sense, and antisense transcripts at this locus in human breast tissue.

Sarzani R, Pietrucci F, Francioni M, et al.
Expression of potassium channel isoforms mRNA in normal human adrenals and aldosterone-secreting adenomas.
J Endocrinol Invest. 2006; 29(2):147-53 [PubMed] Related Publications
Increased aldosterone secretion has been found in a mouse lacking the KCNE1 gene which codes for a regulatory protein of the KCNQ1 gene product, forming the channel for the outward rectifying delayed K+ current. Abnormalities in proteins regulating the K+ fluxes across membranes may be responsible for aldosterone-secreting adenomas (aldosteronomas) also because K+ channels are involved in cell growth. Normal and adenomatous adrenal samples and NCI-H295 cell line were used to: a) evaluate KCNE1 and KCNQ1 gene expression, b) sequence the full length cDNAs of KCNE1 and both KCNQ1 isoforms. These differently spliced KCNE1 and KCNQ1 mRNAs were expressed in adrenal tissue. In contrast, KCNQ1 isoform 2 mRNA was not expressed in kidney control tissues and NCl-H295 cell line. NCI-H295 cell line also had a significantly lower expression of KCNQ1 isoform 1 mRNA than normal adrenals and aldosteronomas. We did not find any somatic mutations in the coding sequences of both genes. This different expression pattern of KCNQ1 isoforms in NCI-H295 cell line with the lack of the mRNA for the dominant-negative KCNQ1 isoform 2 supports the involvement of voltage-gated K+ channel in cell proliferation.

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