Anuria after kidney transplantation diagnosed as early recurrence of focal segmental glomerulosclerosis combined with acute calcineurin inhibitor nephrotoxicity: a case report and literature review.

BACKGROUND: Primary focal segmental glomerulosclerosis (FSGS) is a glomerular disease that sometimes recurs in patients after kidney transplantation (KT) and increases the risk of graft loss. Proteinuria is a common early sign of recurrent FSGS, but an abrupt decrease in urine volume is rare. Herein, we report a patient with early recurrence of FSGS with anuria following KT. CASE PRESENTATION: A 55-year-old man with end-stage kidney disease caused by primary FSGS experienced anuria on postoperative day 2 following deceased donor KT. Laboratory results revealed that serum tacrolimus trough levels were consistently elevated at the time of anuria. At first, we considered acute calcineurin inhibitor (CNI) nephrotoxicity based on graft biopsy on light microscopy, laboratory findings, and clinical courses. However, the allograft function did not recover even after discontinuation of CNI, and recurrent FSGS was diagnosed 2 weeks later on electron microscopy. A total of 13 sessions of plasmapheresis and two administrations of rituximab (375 mg/m2) were required to treat recurrent FSGS. The patient achieved a partial response, and the spot urine protein-to-creatinine ratio decreased from 15.5 g/g creatinine to 5.2 g/g creatinine. At 5 months following KT, the serum creatinine level was stable at 1.15 mg/dL. CONCLUSIONS: These findings highlight that anuria can occur in cases of early recurrence of FSGS combined with acute CNI nephrotoxicity.

Adenovirus VA RNAs impair maturation of primary microRNA.

BACKGROUND: Adenovirus expresses two non-coding virus-associated (VA) RNAs: VA I RNA and VA II RNA. Adenovirus-expressed VA RNAs interfere with the microRNA (miRNA) pathway by competing with precursor miRNAs. The processing pattern of primary miRNA (pri-miRNA) and factors to affect its processing are not exactly known when using adenovirus for the delivery of pri-miRNA. METHODS: To observe pri-miRNA processing, plasmid construct encoding pri-miRNA was co-transfected with VA I/II RNA expression plasmid, or recombinant adenovirus encoding pri-miRNA was generated and infected. Levels of miRNAs, VA I RNA and VA II RNA were analyzed by a quantitative real-time PCR (RT-PCR). VA I-II full-length RNA was analyzed by a RT-PCR. RNA immunoprecipitation analysis to pull-down the VA I-II full-length RNA binding with Drosha was conducted with Drosha antibody. RESULTS: pri-miRNA was normally processed into mature miRNA when it was expressed in cells using plasmid. However, miRNA maturation was impaired when pri-miRNA was delivered and expressed using adenovirus. Of note, pri-miRNA processing was observed to be blocked by VA RNA expression. Such blocked processing could be recovered by introducing antisense RNA of VA RNA, anti-3'VA RNA. In addition, VA RNAs were transcribed into VA I-II full-length RNA, which was found to bind and sequester Drosha. CONCLUSIONS: Adenovirus infection downregulated the processing of pri-miRNAs in cells, and such downregulation could be derived from VA I-II full-length RNAs in pri-miRNA-like form through competitively binding to Drosha protein. These results indicated that the expression of adenovirus VA RNAs should be inhibited for successful delivery and expression of pri-miRNA or shRNA in cells using adenovirus.

Therapeutic Application of Genome Editing Technologies in Viral Diseases.

Viral infections can be fatal and consequently, they are a serious threat to human health. Therefore, the development of vaccines and appropriate antiviral therapeutic agents is essential. Depending on the virus, it can cause an acute or a chronic infection. The characteristics of viruses can act as inhibiting factors for the development of appropriate treatment methods. Genome editing technology, including the use of clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) proteins, zinc-finger nucleases (ZFNs), and transcription activator-like effector nucleases (TALENs), is a technology that can directly target and modify genomic sequences in almost all eukaryotic cells. The development of this technology has greatly expanded its applicability in life science research and gene therapy development. Research on the use of this technology to develop therapeutics for viral diseases is being conducted for various purposes, such as eliminating latent infections or providing resistance to new infections. In this review, we will look at the current status of the development of viral therapeutic agents using genome editing technology and discuss how this technology can be used as a new treatment approach for viral diseases.

Pros and Cons of In Vitro Methods for Circular RNA Preparation.

mRNA is gaining success as a new therapeutic agent and vaccine. However, mRNA has limitations in stability. To overcome the shortcomings of mRNA, circular RNA is emerging as a new modality. In this review, several current methods of manufacturing circular RNA in vitro are introduced and their advantages and disadvantages are reviewed. Furthermore, this study discusses which fields and directions of research and development are needed for the increase in the efficacy and productivity of circular RNA as a therapeutic agent and vaccine formulation.

Aptamers for Anti-Viral Therapeutics and Diagnostics.

Viral infections cause a host of fatal diseases and seriously affect every form of life from bacteria to humans. Although most viral infections can receive appropriate treatment thereby limiting damage to life and livelihood with modern medicine and early diagnosis, new types of viral infections are continuously emerging that need to be properly and timely treated. As time is the most important factor in the progress of many deadly viral diseases, early detection becomes of paramount importance for effective treatment. Aptamers are small oligonucleotide molecules made by the systematic evolution of ligands by exponential enrichment (SELEX). Aptamers are characterized by being able to specifically bind to a target, much like antibodies. However, unlike antibodies, aptamers are easily synthesized, modified, and are able to target a wider range of substances, including proteins and carbohydrates. With these advantages in mind, many studies on aptamer-based viral diagnosis and treatments are currently in progress. The use of aptamers for viral diagnosis requires a system that recognizes the binding of viral molecules to aptamers in samples of blood, serum, plasma, or in virus-infected cells. From a therapeutic perspective, aptamers target viral particles or host cell receptors to prevent the interaction between the virus and host cells or target intracellular viral proteins to interrupt the life cycle of the virus within infected cells. In this paper, we review recent attempts to use aptamers for the diagnosis and treatment of various viral infections.

Epidemiological Study of Hereditary Hemolytic Anemia in the Korean Pediatric Population during 1997-2016: a Nationwide Retrospective Cohort Study.

BACKGROUND: Hereditary hemolytic anemia (HHA) is a rare disease characterized by premature red blood cell (RBC) destruction due to intrinsic RBC defects. The RBC Disorder Working Party of the Korean Society of Hematology established and updated the standard operating procedure for making an accurate diagnosis of HHA since 2007. The aim of this study was to investigate a nationwide epidemiology of Korean HHA. METHODS: We collected the data of a newly diagnosed pediatric HHA cohort (2007-2016) and compared this cohort's characteristics with those of a previously surveyed pediatric HHA cohort (1997-2006) in Korea. Each participant's information was retrospectively collected by a questionnaire survey. RESULTS: A total of 369 children with HHA from 38 hospitals distributed in 16 of 17 districts of Korea were investigated. RBC membranopathies, hemoglobinopathies, RBC enzymopathies, and unknown etiologies accounted for 263 (71.3%), 59 (16.0%), 23 (6.2%), and 24 (6.5%) of the cases, respectively. Compared to the cohort from the previous decade, the proportions of hemoglobinopathies and RBC enzymopathies significantly increased (P < 0.001 and P = 0.008, respectively). Twenty-three of the 59 hemoglobinopathy patients had immigrant mothers, mostly from South-East Asia. CONCLUSION: In Korea, thalassemia traits have increased over the past 10 years, reflecting both increased awareness of this disease and increased international marriages. The enhanced recognition of RBC enzymopathies is due to advances in diagnostic technique; however, 6.5% of HHA patients still do not have a clear diagnosis. It is necessary to improve accessibility of diagnosing HHA.

Enhancement of chemosensitivity in 5-fluorouracil-resistant colon cancer cells with carcinoembryonic antigen-specific RNA aptamer.

Colorectal cancer (CRC) is one of the most common cancers, and rates of incidence and diagnosis of CRC have gradually increased. Carcinoembryonic antigen (CEA) is overexpressed in patients with CRC and is associated with cell adhesion, anoikis resistance, and promotion of metastasis to the liver. 5-Fluorouracil (5-FU) is a chemotherapeutic drug used to treat cancer, including CRC. However, a major issue of 5-FU therapy is the occurrence of chemoresistance, and the fact that 5-FU induces CEA overexpression, which may induce the 5-FU resistance. We previously isolated a CEA-specific RNA aptamer that was able to inhibit hepatic metastasis of colon cancer cells in a mouse model. In the present study, we tested whether protecting CEA using the CEA aptamer could enhance 5-FU sensitivity in chemoresistant LS174T colon cancer cells. We observed that the CEA aptamer sensitized the 5-FU-resistant colon cancer cell line to 5-FU more than five-fold (IC50 ~ 5.995 µM), compared with cells treated with 5-FU alone (IC50 ~ 31.46 µM). Moreover, treatment with CEA aptamer combined with 5-FU synergistically regressed growth of chemoresistant tumors in mouse xenografted models. Combinatorial treatment of 5-FU and CEA aptamer augmented caspase-8 activity in the 5-FU-resistant colon cancer cell line via aptamer-mediated disruption of CEA interaction with death receptor 5 and in mouse xenograft tumors. In conclusion, CEA-specific aptamer improved 5-FU sensitivity in chemoresistant colon cancer cells in vitro and in vivo, and thus represents a novel 5-FU adjuvant to overcome the chemoresistance in CRC patients.

Effects of Human Mesenchymal Stem Cells Coculture on Calcium-Induced Differentiation of Normal Human Keratinocytes.

The influence of mesenchymal stem cells (MSCs) on keratinocytes in altered microenvironments is poorly understood. Here, we cocultured umbilical cord blood-derived MSCs with normal human epidermal keratinocytes to evaluate their paracrine effect in the presence of high extracellular calcium (Ca2+ ) concentration. High Ca2+ environment to keratinocytes can disrupt normal skin barrier function due to abnormal/premature differentiation of keratinocytes. Surprisingly, we found that MSCs suppress both proliferation and differentiation of keratinocytes under a high Ca2+ environment in transforming growth factors ß1 (TGFß1)-dependent manner. Furthermore, we determined that MSCs can regulate the mitogen-activated protein kinases, phosphatidylinositol 3-kinase/protein kinase B, and protein kinase C pathways in Ca2+ -induced differentiated keratinocytes. Knockdown of TGFß1 from MSCs results in decreased suppression of differentiation with significantly increased proliferation of keratinocytes compared with control MSCs. MSCs-derived TGFß1 further induced growth inhibition of keratinocyte in high extracellular Ca2+ environment as analyzed by a decrease in DNA synthesis, accumulation of phosphorylated retinoblastoma protein, cdc2, and increased mRNA level of p21, and independent of TGFß1/SMAD pathway. Taken together, we found that MSCs-derived TGFß1 is a critical regulator of keratinocyte function, and involves multiple proximal signaling cascades. Stem Cells 2017;35:1592-1602.

Specific and Efficient Regression of Cancers Harboring KRAS Mutation by Targeted RNA Replacement.

Mutations in the KRAS gene, which persistently activate RAS function, are most frequently found in many types of human cancers. Here, we proposed and verified a new approach against cancers harboring the KRAS mutation with high cancer selectivity and efficient anti-cancer effects based on targeted RNA replacement. To this end, trans-splicing ribozymes from Tetrahymena group I intron were developed, which can specifically target and reprogram the mutant KRAS G12V transcript to induce therapeutic gene activity in cells. Adenoviral vectors containing the specific ribozymes with downstream suicide gene were constructed and then infection with the adenoviruses specifically downregulated KRAS G12V expression and killed KRAS G12V-harboring cancer cells additively upon pro-drug treatment, but it did not affect the growth of wild-type KRAS-expressing cells. Minimal liver toxicity was noted when the adenoviruses were administered systemically in vivo. Importantly, intratumoral injection of the adenoviruses with pro-drug treatment specifically and significantly impeded the growth of xenografted tumors harboring KRAS G12V through a trans-splicing reaction with the target RNA. In contrast, xenografted tumors harboring wild-type KRAS were not affected by the adenoviruses. Therefore, RNA replacement with a mutant KRAS-targeting trans-splicing ribozyme is a potentially useful therapeutic strategy to combat tumors harboring KRAS mutation.

Development of RNA aptamer that inhibits methyltransferase activity of dengue virus.

OBJECTIVES: To develop an RNA aptamer specific for the methyltransferase (MTase) of dengue virus (DENV) which is essential for viral genome replication and translation acting directly on N-7 and 2'-O-methylation of the type-I cap structure of the viral RNA. RESULTS: We identified 2'-fluoro-modified RNA aptamers that can specifically bind DENV serotype 2 (DENV2) MTase using systematic evolution of ligands by exponential enrichment technology. We truncated the chosen aptamer into a 45-mer RNA sequence that can bind DENV2 MTase with K d  ~ 28 nM and inhibit N-7 methylation activity of the protein. Moreover, the 45-mer truncated aptamer could not only bind with an K d  ~ 15.6 nM but also inhibit methylation activity of DENV serotype 3 (DENV3) MTase. The 45-mer aptamer competitively impeded binding of both DENV2 and DENV3 genomic RNA to MTase of each serotype. CONCLUSION: The selected 45-mer truncated RNA aptamer specifically and avidly bound DENV MTase and competitively inhibited its methylation activity, and thus could be useful for the development of anti-DENV agents.

Inhibition of Japanese encephalitis virus (JEV) replication by specific RNA aptamer against JEV methyltransferase.

Japanese encephalitis virus (JEV) is the most common etiological agent of epidemic viral encephalitis. JEV encodes a single methyltransferase (MTase) domain located at the N-terminal region of the viral nonstructural protein NS5. JEV MTase is essential for viral replication and specifically catalyzes methylation of the viral RNA cap, which occurs exclusively in the cytoplasm. Therefore, JEV MTase is a potential target for antiviral therapy. Here, we identified specific and avid RNA aptamer (Kd âˆ¼ 12 nM) with modified 2'-O-methyl pyrimidines against JEV MTase. The RNA aptamer efficiently inhibited viral cap methylation activity of MTase and interfered with JEV production in cells. Moreover, we generated a 24-mer truncated aptamer that could specifically bind to JEV MTase with high affinity (Kd ∼16 nM). The 24-mer aptamer efficiently inhibited JEV production and replication in cells. Therefore, MTase-specific RNA aptamer might be useful as an anti-JEV agent.

Hematopoietic stem cell transplantation in pediatric patients with acute myeloid leukemia without favorable cytogenetics.

Intensified chemotherapy, HSCT, and supportive care improve the survival of pediatric patients with AML. However, no consensus has been reached regarding the role of HSCT in patients without favorable cytogenetics. We evaluated OS and EFS according to prognostic factors that affect clinical outcomes, including cytogenetics risk group, conditioning regimen, donor type, disease status at the time of HSCT, and number of chemotherapy cycles prior to HSCT in 65 pediatric patients with AML without favorable cytogenetics who underwent HSCT. Fifteen of the 65 patients died: three of TRM and 12 of disease-related mortality. The 5-year OS and EFS were 78.0% and 72.0%, respectively, and the 5-year cumulative relapse and TRM rates were 26.9% and 5.1%, respectively. Survival rates were not influenced by cytogenetic group (intermediated vs. poor), donor type (related vs. unrelated), transplant type (myeloablative vs. reduced-intensity conditioning), or number of pretransplant chemotherapy cycles (≤3 vs. >3 cycles). The low TRM rate and encouraging outcomes suggest that HSCT may be a feasible treatment for pediatric patients with AML without favorable cytogenetics.

Recombinant adenovirus infection suppresses hTERT expression through virus-associated RNA-mediated induction of type 1 interferon.

Adenovirus vector is one of the most widely used vectors in gene therapy applications for the treatment of diverse human diseases including cancer. In this study, we showed that infection with E1E3-deleted recombinant human adenovirus serotype 5 reduced human telomerase reverse transcriptase (hTERT) mRNA levels in hepatoma cell lines. We defined the mechanisms by which the recombinant adenovirus vector reduces hTERT mRNA levels as follows: Using the virus-associated RNA I/II (VAI/II) expression construct, we demonstrated that the expression of VAI and VAII RNAs led to an increase in IFN-α2 level, and IFN-α2 induction was responsible for the decrease in hTERT mRNA levels. We showed that the effects of VA RNAs were specific for the replication-incompetent E1E3-deleted adenovirus vector, because wild-type adenovirus affected neither IFN-α2 nor hTERT mRNA levels. Moreover, we demonstrated that adenovirus vector-mediated delivery of the hTERT-targeting anti-cancer reagent could additively reduce the levels of hTERT mRNA that were specifically overexpressed in most of the cancer cells. This study showed that E1E3-deleted adenovirus vector system reduced hTERT mRNA levels through VA RNA-mediated induction of type 1 interferon; hence the recombinant adenovirus itself could have anti-cancer activity. These results indicate that recombinant adenovirus vector could be an effective means to deliver anti-cancer reagents for combating cancerous cells more effectively.

Successful use of brentuximab vedotin for refractory anaplastic large cell lymphoma as a bridging therapy to haploidentical stem cell transplantation and maintenance therapy post-transplantation.

Brentuximab vedotin (BV) is a monoclonal antibody-drug conjugate that targets CD30, and has been reported to be effective for relapsed/refractory anaplastic large cell lymphoma. We here report a patient who experienced multiple relapses after conventional chemotherapy and autologous hematopoietic stem cell transplantation (HSCT). He achieved a complete metabolic response with BV and proceeded to undergo haploidentical HSCT. After HSCT, he received three doses of BV to prevent an early relapse, and remains in remission 16 months post-transplantation. Our case suggests the potential use of BV both as a bridging therapy to allogeneic HSCT and as a maintenance therapy post-transplantation.

In vitro selection of RNA aptamers that selectively bind danofloxacin.

Danofloxacin is a synthetic fluoroquinolone with broad spectrum antibacterial activity that is used for the treatment of respiratory diseases in animal husbandry. However, danofloxacin has many adverse reactions and is toxic to humans. Especially, it detrimentally affects muscle, central nerve system, peripheral nerve system, liver, and skin in those who ingest foods in which danofloxacin has accumulated. Prescreening and determination of the level of danofloxacin in foods or food products is necessary for human health. Aptamers are composing of oligonucleotides that specifically interact with target molecules. They are emerging as detection/diagnostic ligands. Here, we used the SELEX in vitro selection technology to identify specific and high-affinity RNA aptamers with 2'-fluoro-2'-deoxyribonucleotide modified pyrimidine nucleotides against danofloxacin. Selected RNA aptamers bound specifically to danofloxacin, but not to tetracycline. Truncation of RNA aptamer up to 36 mer did not comprise specificity and affinity. The truncated RNA aptamer specifically bound to target chemical, allowing the discrimination of danofloxacin from other fluoroquinolones. The isolated specific aptamer could be a potential agent used for the rapid and cost-effective detection and sensing of danofloxacin, replacing instrumental methods including the more expensive and time-consuming methods of high performance liquid chromatography and liquid chromatography/mass spectrometry.

Inhibition of hepatitis C virus (HCV) replication by specific RNA aptamers against HCV NS5B RNA replicase.

This study identified specific and avid RNA aptamers consisting of 2'-hydroxyl- or 2'-fluoropyrimidines against hepatitis C virus (HCV) NS5B replicase, an enzyme that is essential for HCV replication. These aptamers acted as potent decoys to competitively impede replicase-catalyzed RNA synthesis activity. Cytoplasmic expression of the 2'-hydroxyl aptamer efficiently inhibited HCV replicon replication in human liver cells through specific interaction with, and sequestration of, the target protein without either off-target effects or escape mutant generation. A selected 2'-fluoro aptamer could be truncated to a chemically manufacturable length of 29 nucleotides (nt), with increase in the affinity to HCV NS5B. Noticeably, transfection of the truncated aptamer efficiently suppressed HCV replication in cells without escape mutant appearance. The aptamer was further modified through conjugation of a cholesterol or galactose-polyethylene glycol ligand for in vivo availability and liver-specific delivery. The conjugated aptamer efficiently entered cells and inhibited genotype 1b subgenomic and genotype 2a full-length HCV JFH-1 RNA replication without toxicity and innate immunity induction. Importantly, a therapeutically feasible amount of the conjugated aptamer was delivered in vivo to liver tissue in mice. Therefore, cytoplasmic expression of 2'-hydroxyl aptamer or direct administration of chemically synthesized and ligand-conjugated 2'-fluoro aptamer against HCV NS5B could be a potent anti-HCV approach.

Clinical significance of previously cryptic copy number alterations and loss of heterozygosity in pediatric acute myeloid leukemia and myelodysplastic syndrome determined using combined array comparative genomic hybridization plus single-nucleotide polymorphism microarray analyses.

The combined array comparative genomic hybridization plus single-nucleotide polymorphism microarray (CGH+SNP microarray) platform can simultaneously detect copy number alterations (CNA) and copy-neutral loss of heterozygosity (LOH). Eighteen children with acute myeloid leukemia (AML) (n=15) or myelodysplastic syndrome (MDS) (n=3) were studied using CGH+SNP microarray to evaluate the clinical significance of submicroscopic chromosomal aberrations. CGH+SNP microarray revealed CNAs at 14 regions in 9 patients, while metaphase cytogenetic (MC) analysis detected CNAs in 11 regions in 8 patients. Using CGH+SNP microarray, LOHs>10 Mb involving terminal regions or the whole chromosome were detected in 3 of 18 patients (17%). CGH+SNP microarray revealed cryptic LOHs with or without CNAs in 3 of 5 patients with normal karyotypes. CGH+SNP microarray detected additional cryptic CNAs (n=2) and LOHs (n=5) in 6 of 13 patients with abnormal MC. In total, 9 patients demonstrated additional aberrations, including CNAs (n=3) and/or LOHs (n=8). Three of 15 patients with AML and terminal LOH>10 Mb demonstrated a significantly inferior relapse-free survival rate (P=0.041). This study demonstrates that CGH+SNP microarray can simultaneously detect previously cryptic CNAs and LOH, which may demonstrate prognostic implications.

Excessively Delayed Radiation Changes After Proton Beam Therapy for Brain Tumors: Report of Two Cases.

Delayed cerebral necrosis is a well-known complication of radiation therapy (RT). Because of its irreversible nature, it should be avoided if possible, but avoidance occurs at the expense of potentially compromised tumor control, despite the use of the modern advanced technique of conformal RT that minimizes radiation to normal brain tissue. Risk factors for radiation-induced cerebral necrosis include a higher dose per fraction, larger treatment volume, higher cumulative dose, and shorter time interval (for re-irradiation). The same principle can be applied to proton beam therapy (PBT) to avoid delayed cerebral necrosis. However, conversion of PBT radiation energy into conventional RT is still short of clinical support, compared to conventional RT. Herein, we describe two patients with excessively delayed cerebral necrosis after PBT, in whom follow-up MRI showed no RT-induced changes prior to 3 years after treatment. One patient developed radiation necrosis at 4 years after PBT to the resection cavity of an astroblastoma, and the other developed brainstem necrosis that became symptomatic 6 months after its first appearance on the 3-year follow-up brain MRI. We also discuss possible differences between radiation changes after PBT versus conventional RT.

Severe Acute Kidney Injury Associated with Transformation of Chronic Myelomonocytic Leukemia into Acute Myeloid Leukemia: A Case Report.

Chronic myelomonocytic leukemia (CMML) is a rare hematologic disorder that infrequently causes acute kidney injury (AKI). CMML can transform into acute myeloid leukemia (AML), which can be accompanied by a deterioration in kidney function. However, severe AKI due to extramedullary manifestations of AML is rare. Herein, we present the case of a 67-year-old male patient with CMML that transformed into AML with severe AKI necessitating hemodialysis. The cause of the AKI was the AML transformation. The patient, with stable kidney function after chemotherapy for CMML, presented with a sudden decline in kidney function. Hemodialysis was initiated because of severe AKI, and histopathologic evaluation of the kidney biopsy specimen revealed severe, diffuse mixed inflammatory cell infiltrates in the interstitium and c-kit-immunopositive myeloblast-like cells. A bone marrow biopsy was performed because of the kidney biopsy findings suggesting that leukemic infiltration led to the diagnosis of AML. The patient received chemotherapy for AML, and his kidney function recovered. As illustrated in this case, severe AKI can develop as an early extramedullary manifestation during transformation from CMML to AML. Therefore, in patients with CMML and rapidly declining renal function, transformation into AML should be considered and histopathologically confirmed by kidney biopsy.

An RNA aptamer that binds carcinoembryonic antigen inhibits hepatic metastasis of colon cancer cells in mice.

BACKGROUND & AIMS: Carcinoembryonic antigen (CEA) is expressed by many types of cancer cells; its overexpression induces cell adhesion, increases resistance to anoikis, and promotes hepatic metastasis of colon cancer cells. The amino acid sequence PELPK in its hinge region, between the N and A1 domains, is required for migration of cancer cells to the liver. We sought to identify ligands of this domain for use in diagnosis and therapy. METHODS: We screened for RNA aptamers against the domain of CEA required for metastasis using systematic evolution of ligands by exponential enrichment. The specificity and affinity of the aptamer for CEA protein were characterized by mobility shift, uptake, and surface plasmon resonance assays. We analyzed the effects of the aptamer on metastatic properties of cells, as well as metastasis of colon cancer cells in mice. RESULTS: Using systematic evolution of ligands by exponential enrichment, we identified an RNA aptamer that bound to the PELPK sequence in CEA with high affinity and specificity. The isolated aptamer bound specifically to CEA-positive cells and inhibited interactions between CEA and heterogeneous nuclear ribonucleoprotein M4. The aptamer inhibited homotypic aggregation, migration, and invasion by CEA-positive cancer cells, but did not affect adhesion of endothelial cells. The aptamer induced colon cancer cell anoikis by interrupting the interaction between death receptor 5 and CEA. The aptamer prevented metastasis of human colon cancer cells to the livers of mice. CONCLUSIONS: An RNA aptamer that binds to the PELPK sequence in CEA inhibits its interactions with heterogeneous nuclear ribonucleoprotein M4 and death receptor 5, migration and invasion by colon cancer cells, and hepatic metastasis of colon cancer cells in mice. It promoted cancer cell anoikis and might be used to identify CEA-positive tumors in patients or be developed as an anti-cancer reagent.