Publications by authors named "Randal K Wada"

15 Publications

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Genomic and Transcriptomic Analysis of Relapsed and Refractory Childhood Solid Tumors Reveals a Diverse Molecular Landscape and Mechanisms of Immune Evasion.

Cancer Res 2021 12 5;81(23):5818-5832. Epub 2021 Oct 5.

Translational Genomics Research Institute (TGen), Phoenix, Arizona.

Children with treatment-refractory or relapsed (R/R) tumors face poor prognoses. As the genomic underpinnings driving R/R disease are not well defined, we describe here the genomic and transcriptomic landscapes of R/R solid tumors from 202 patients enrolled in Beat Childhood Cancer Consortium clinical trials. Tumor mutational burden (TMB) was elevated relative to untreated tumors at diagnosis, with one-third of tumors classified as having a pediatric high TMB. Prior chemotherapy exposure influenced the mutational landscape of these R/R tumors, with more than 40% of tumors demonstrating mutational signatures associated with platinum or temozolomide chemotherapy and two tumors showing treatment-associated hypermutation. Immunogenomic profiling found a heterogenous pattern of neoantigen and MHC class I expression and a general absence of immune infiltration. Transcriptional analysis and functional gene set enrichment analysis identified cross-pathology clusters associated with development, immune signaling, and cellular signaling pathways. While the landscapes of these R/R tumors reflected those of their corresponding untreated tumors at diagnosis, important exceptions were observed, suggestive of tumor evolution, treatment resistance mechanisms, and mutagenic etiologies of treatment. SIGNIFICANCE: Tumor heterogeneity, chemotherapy exposure, and tumor evolution contribute to the molecular profiles and increased mutational burden that occur in treatment-refractory and relapsed childhood solid tumors.
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http://dx.doi.org/10.1158/0008-5472.CAN-21-1033DOI Listing
December 2021

Leadership, behavioral science, and interprofessional teamwork.

Authors:
Randal K Wada

Transl Behav Med 2020 10;10(4):905-908

School of Nursing and Dental Hygiene, John A. Burn School of Medicine, University of Hawaii, Honolulu, HI, USA.

The greatest challenge I face as a pediatric oncologist is breaking life-threatening news to patients and their parents. I frequently felt the need to improve my ability to deliver such information in a professional, yet compassionate way. I was fortunate to participate in the Leadership Institute, which provided me with the skills and perspectives that inspired me to seek out team-centered methodologies and medical decision-making theories. After learning techniques for priority setting, situational leadership, expressing empathy, and conveying bad news, guidance from the Leadership Institute prompted me to collaborate with nursing, social work, and chaplaincy colleagues to develop a team-based approach for helping families facing end-of-life decisions. Our success in the clinical arena led to my leadership project, which focused on academic collaborations to develop an educational exercise for pediatric residents, and students in nursing, social work, and chaplaincy, designed to introduce learners to these techniques and the experience of conducting end-of-life discussions as part of an interprofessional team. We published an initial description of this 4-hour simulation-based training session and now plan to submit our cumulative 3-year quantitative and qualitative results. This commentary describes my growing appreciation of the power of behavioral medicine, and how the lessons learned through the Society of Behavioral Medicine and the Leadership Institute have not only facilitated the success of my project but also enriched multiple aspects of my professional life.
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http://dx.doi.org/10.1093/tbm/ibaa063DOI Listing
October 2020

A subset analysis of a phase II trial evaluating the use of DFMO as maintenance therapy for high-risk neuroblastoma.

Int J Cancer 2020 12 24;147(11):3152-3159. Epub 2020 May 24.

Helen DeVos Children's Hospital at Spectrum Health, Grand Rapids, Michigan, USA.

Neuroblastoma is a sympathetic nervous system tumor, primarily presenting in children under 6 years of age. The long-term prognosis for patients with high-risk neuroblastoma (HRNB) remains poor despite aggressive multimodal therapy. This report provides an update to a phase II trial evaluating DFMO as maintenance therapy in HRNB. Event-free survival (EFS) and overall survival (OS) of 81 subjects with HRNB treated with standard COG induction, consolidation and immunotherapy followed by 2 years of DFMO on the NMTRC003/003b Phase II trial were compared to a historical cohort of 76 HRNB patients treated at Beat Childhood Cancer Research Consortium (BCC) hospitals who were disease-free after completion of standard upfront therapy and did not receive DFMO. The 2- and 5-year EFS were 86.4% [95% confidence interval (CI) 79.3%-94.2%] and 85.2% [77.8%-93.3%] for the NMTRC003/003b subset vs 78.3% [69.5%-88.3%] and 65.6% [55.5%-77.5%] for the historical control group. The 2- and 5-year OS were 98.8% [96.4-100%] and 95.1% [90.5%-99.9%] vs 94.4% [89.3%-99.9%] and 81.6% [73.0%-91.2%], respectively. DFMO maintenance for HRNB after completion of standard of care therapy was associated with improved EFS and OS relative to historical controls treated at the same institutions. These results support additional investigations into the potential role of DFMO in preventing relapse in HRNB.
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http://dx.doi.org/10.1002/ijc.33044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7586843PMC
December 2020

Engaging a Community Chaplaincy Resource for Interprofessional Health Care Provider Training in Facilitating Family Decision Making for Children at End-of-Life.

Hawaii J Med Public Health 2019 06;78(6 Suppl 1):37-40

Office of Public Health Studies, Myron B. Thompson School of Social Work, University of Hawai‘i at Mānoa, Honolulu, HI

Coordinating the care of terminally ill children is difficult for both parents and the health care team. An underutilized resource is spiritual care, such as that provided by Pacific Health Ministry, a community-based nonprofit established to develop hospital ministry training programs in Hawai'i and provide chaplaincy services to local facilities. This paper describes a training exercise, called the Pediatric Interprofessional Program (PIPP), which is modeled after an adult program, the Hawai'i Interprofessional Training for End of Life Communication in the intensive care unit (HITEC-ICU). Both programs were developed to introduce teams of learners consisting of Pacific Health Ministry spiritual care residents, internal medicine or pediatric residents, undergraduate students in nursing, and graduate students in social work to techniques in delivering serious, life-altering information, and the dynamics of working as an interprofessional team through use of progressively unfolding clinical simulations. PIPP facilitators included chaplaincy instructors at Pacific Health Ministry, university faculty, and community practitioners in pediatrics, nursing, and social work. The simulations were conducted at the Translational Health Science Simulation Center (THSSC) of the University of Hawai'i at Mānoa (UHM) School of Nursing and Dental Hygiene (SONDH), with simulated patients from the HealthCAST (Collaborative Acting Simulation Training) program, a collaborative agreement between SONDH and the UHM Department of Theatre and Dance. The training is ongoing, but has thus far demonstrated that interprofessional education programs are feasible across community, academic, and clinical lines, and benefit from the engagement of community resources.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6603893PMC
June 2019

Maintenance DFMO Increases Survival in High Risk Neuroblastoma.

Sci Rep 2018 09 27;8(1):14445. Epub 2018 Sep 27.

Medical University of South Carolina, Charleston, USA.

High risk neuroblastoma (HRNB) accounts for 15% of all pediatric cancer deaths. Despite aggressive therapy approximately half of patients will relapse, typically with only transient responses to second-line therapy. This study evaluated the ornithine decarboxylase inhibitor difluoromethylornithine (DFMO) as maintenance therapy to prevent relapse following completion of standard therapy (Stratum 1) or after salvage therapy for relapsed/refractory disease (Stratum 2). This Phase II single agent, single arm multicenter study enrolled from June 2012 to February 2016. Subjects received 2 years of oral DFMO (750 ± 250 mg/m twice daily). Event free survival (EFS) and overall survival (OS) were determined on an intention-to-treat (ITT) basis. 101 subjects enrolled on Stratum 1 and 100 were eligible for ITT analysis; two-year EFS was 84% (±4%) and OS 97% (±2%). 39 subjects enrolled on Stratum 2, with a two-year EFS of 54% (±8%) and OS 84% (±6%). DFMO was well tolerated. The median survival time is not yet defined for either stratum. DFMO maintenance therapy for HRNB in remission is safe and associated with high EFS and OS. Targeting ODC represents a novel therapeutic mechanism that may provide a new strategy for preventing relapse in children with HRNB.
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http://dx.doi.org/10.1038/s41598-018-32659-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6160434PMC
September 2018

A Phase I Trial of DFMO Targeting Polyamine Addiction in Patients with Relapsed/Refractory Neuroblastoma.

PLoS One 2015 27;10(5):e0127246. Epub 2015 May 27.

College of Human Medicine, Michigan State University, Grand Rapids, Michigan, United States of America; University of Hawaii at Hilo, The Daniel K. Inouye College of Pharmacy, Hilo, Hawaii, United States of America.

Background: Neuroblastoma (NB) is the most common cancer in infancy and most frequent cause of death from extracranial solid tumors in children. Ornithine decarboxylase (ODC) expression is an independent indicator of poor prognosis in NB patients. This study investigated safety, response, pharmacokinetics, genetic and metabolic factors associated with ODC in a clinical trial of the ODC inhibitor difluoromethylornithine (DFMO) ± etoposide for patients with relapsed or refractory NB.

Methods And Findings: Twenty-one patients participated in a phase I study of daily oral DFMO alone for three weeks, followed by additional three-week cycles of DFMO plus daily oral etoposide. No dose limiting toxicities (DLTs) were identified in patients taking doses of DFMO between 500-1500 mg/m2 orally twice a day. DFMO pharmacokinetics, single nucleotide polymorphisms (SNPs) in the ODC gene and urinary levels of substrates for the tissue polyamine exporter were measured. Urinary polyamine levels varied among patients at baseline. Patients with the minor T-allele at rs2302616 of the ODC gene had higher baseline levels (p=0.02) of, and larger decreases in, total urinary polyamines during the first cycle of DFMO therapy (p=0.003) and had median progression free survival (PFS) that was over three times longer, compared to patients with the major G allele at this locus although this last result was not statistically significant (p=0.07). Six of 18 evaluable patients were progression free during the trial period with three patients continuing progression free at 663, 1559 and 1573 days after initiating treatment. Median progression-free survival was less among patients having increased urinary polyamines, especially diacetylspermine, although this result was not statistically significant (p=0.056).

Conclusions: DFMO doses of 500-1500 mg/m2/day are safe and well tolerated in children with relapsed NB. Children with the minor T allele at rs2302616 of the ODC gene with relapsed or refractory NB had higher levels of urinary polyamine markers and responded better to therapy containing DFMO, compared to those with the major G allele at this locus. These findings suggest that this patient subset may display dependence on polyamines and be uniquely susceptible to therapies targeting this pathway.

Trial Registration: Clinicaltrials.gov NCT#01059071.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0127246PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4446210PMC
April 2016

Hawai'i's multiethnic adolescent and young adult survivors of childhood cancer: are their health behavior risks similar to state and national samples?

Hawaii J Med Public Health 2013 Nov;72(11):380-5

University of Hawai'i at Manoa, School of Nursing and Dental Hygiene, Honolulu, HI (R.K.W., C.L.A.).

Due to toxicities associated with their malignancies and treatments, adolescent and young adult survivors of childhood cancer (AYASCC) are at high risk for developing chronic diseases. This can be compounded by a greater prevalence of unhealthy behaviors relative to similarly aged non-cancer peers. Disparities in health behaviors have been noted for Black and Hispanic AYASCC, but data on Asian American (AA) or Native Hawaiian and Other Pacific Islander (NHOPI) minorities are lacking. The purpose of this study was to help bridge these information gaps by gathering data from Hawai'i AA and NHOPI AYSCC. Telephone surveys were used to collect health behavior data from survivors 13-24 years of age (N=64); 55% of the sample was female, 77% AA or NHOPI, 63% leukemia/lymphoma survivors, and 32% overweight/obese. These were compared to state/national survey data for similarly aged individuals (Youth Risk Behavior Surveillance System data for 13-17 year olds, and Behavioral Risk Factor Surveillance System data for 18-24 year olds). While Hawai'i AYASCC had significantly lower rates of tobacco/alcohol use, a higher proportion did not eat five fruits/vegetables a day (96%) compared to state (83%) and national (78%) samples (P < .001). Although many met age-specific physical activity recommendations, 44% of <18 year olds and 29% of ≥18 year olds still failed to meet national guidelines. Low intake of fruits/vegetables and suboptimal levels of physical activity place these vulnerable, ethnic minority cancer survivors at higher risk for chronic disease. These findings underscore the need to assess and advise survivors about their diet and exercise habits as part of post-treatment care.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3831565PMC
November 2013

PEA15 impairs cell migration and correlates with clinical features predicting good prognosis in neuroblastoma.

Int J Cancer 2012 Oct 31;131(7):1556-68. Epub 2012 Jan 31.

Cancer Biology Program, University of Hawai'i Cancer Center, University of Hawai'i at Manoa, Honolulu, HI 96813, USA.

ERK and RSK2 drive proliferation and invasion of many cancers. Phosphoprotein enriched in astrocytes 15 (PEA15) binds ERK and RSK2 and high PEA15 levels can impair ERK- and RSK2-dependent transcription. PEA15 expression also inversely correlates with cell motility and invasiveness. We therefore tested PEA15 effects on neuroblastoma cells in vitro. We further analyzed PEA15 expression in the context of clinical and genetic features of neuroblastoma in tumor samples to determine its correlation with disease progression. Affymetrix microarray analysis was performed using 24 different neuroblastoma cell lines. Cell lines expressing low to intermediate levels of PEA15 were chosen for in vitro functional studies. The cell line results were verified by Affymetrix analysis of three different neuroblastic tumor types (total of 110 samples) PEA15 overexpression inhibited neuroblastoma migration in vitro. We verified that inhibition of motility required PEA15 interaction with its binding partners ERK and RSK2. Additionally, synthetic inhibitors of RSK2 suppressed integrin-dependent migration. PEA15 expression correlates with clinical parameters and a 25% increase in patient survival rate. The highest PEA15 levels were found in low stage, more differentiated and less metastatic neuroblastic tumors, and correlated with lack of MYCN amplification. PEA15 blocks neuroblastoma migration through inhibition of ERK/RSK2 signaling. PEA15 expression levels correlate with favorable clinical features suggesting that PEA15 limits metastatic progression of neuroblastoma. Thus, PEA15 and its partners ERK and RSK2 are potential targets for the development of new therapeutics to impede progression of minimal residual disease in patients with high-risk neuroblastoma.
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http://dx.doi.org/10.1002/ijc.27415DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3757132PMC
October 2012

Retinoic acid induced downregulation of MYCN is not mediated through changes in Sp1/Sp3.

Pediatr Blood Cancer 2008 Apr;50(4):806-11

Natural Products and Cancer Biology Program, Cancer Research Center of Hawaii, Honolulu, Hawaii, USA.

Background: Use of retinoic acid (RA) has become the standard of care in the treatment of high risk neuroblastoma (NB). In vitro, RA induces growth arrest and differentiation, an effect that likely underlies its activity in the clinical setting. An important event in differentiation is the transcriptional downregulation of the MYCN oncogene, which is frequently activated in aggressive tumors. While it is known that Sp1/Sp3 and E2F are necessary to drive basal MYCN expression, the mechanism for its downregulation by RA remains enigmatic. Changes in E2F binding have been reported, however these occurred after the actual transcriptional response. Here, post-translational modifications of Sp proteins were examined as an alternate mechanism of RA-mediated promoter regulation.

Procedure: Western blot was used to evaluate steady state levels of nuclear/cytoplasmic Sp1/Sp3. Promoter binding and DNA conformation were determined by gel shift, circular permutation, and chromatin immunoprecipitation assays. Immunoprecipitation/western and (32)P-phosphoamino analyses were used to detect glycosylation, acetylation, sumoylation, and phosphorylation.

Results: RA did not affect the cellular level of Sp1/Sp3 proteins, their nuclear/cytoplasmic distribution, ability to bind the MYCN promoter, degree of Sp-induced DNA bending, or post-translational modifications.

Conclusions: MYCN RA response is not mediated solely though the region controlling basal activity. RA may be exerting its effects via multiple non-adjacent regulatory regions, potentially including basal motifs, either within the MYCN promoter or distally, on the same or even different chromosomes. Such cooperative trans-type DNA-protein interactions could explain the inaccessibility of this mechanism to the locus-specific approaches employed up to this point.
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http://dx.doi.org/10.1002/pbc.21273DOI Listing
April 2008

Assessment of optimal size and composition of the U.S. National Registry of hematopoietic stem cell donors.

Transplantation 2004 Jul;78(1):89-95

National Marrow Donor Program, Minneapolis, MN, USA.

Background: The National Marrow Donor Program (NMDP) receives federal funding to operate a registry of over 4 million volunteer donors for patients in need of a hematopoietic stem cell transplant. Because minority patients are less likely to find a suitably matched donor than whites, special efforts have been aimed toward recruitment of minorities. Significant financial resources are required to recruit and tissue type additional volunteer donors.

Methods: Population genetics models have been constructed to project likelihoods of finding a human leukocyte antigen (HLA)-matched donor for patients of various racial/ethnic groups. These projections have been made under a variety of strategies for expansion of the NMDP Registry. Cost-effectiveness calculations incorporated donor unavailability and other barriers to transplantation.

Results: At current recruitment rates, the probability of an available HLA-A,B,DRB1 matched donor is projected to increase from 27% to 34%; 45% to 54%; 75% to 79%; and 48% to 55%, for blacks, Asians/Pacific Islanders, whites and Hispanics, respectively, by the year 2007. Substantial increases in minority recruitment would have only modest impacts on these projections. These projections are heavily affected by donor availability rates, which are less than 50% for minority volunteers.

Conclusions: Continued recruitment of additional volunteers can improve the likelihood of finding an HLA-matched donor, but will still leave significant numbers of patients of all racial/ethnic groups without a match. Efforts to improve donor availability (especially among minorities) and to increase the number of patients with access to the NMDP Registry may prove to be more cost-effective means of increasing transplants.
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http://dx.doi.org/10.1097/01.tp.0000132327.40702.97DOI Listing
July 2004

Na-K-2Cl cotransporter inhibition impairs human lung cellular proliferation.

Am J Physiol Lung Cell Mol Physiol 2004 Sep 21;287(3):L510-4. Epub 2004 May 21.

Dept. of Pediatrics, Honolulu, HI 96826, USA.

The widespread presence of the Na-K-2Cl (NKCC) cotransporter protein suggests that chronic administration of inhibitors may result in adverse effects. Inhibition of the NKCC cotransporter by loop diuretics is felt to underlie the diuretic and the pulmonary smooth muscle relaxant effects of this drug class. However, the fundamental regulation of salt and water movement by this cotransporter suggests that it may also mediate cell volume changes occurring during cell cycle progression. Thus we hypothesized that NKCC cotransporter inhibition by loop diuretics would decrease cellular proliferation. Normal human bronchial smooth muscle cells (BSMC) showed a significant concentration-dependent decrease in cell counts after 7 days of exposure to both bumetanide (n=5-10) and furosemide (n=6-16) compared with controls. Proliferation was similarly inhibited in normal human lung fibroblasts (n=5-9). To determine whether this was due to loss of cells, we performed apoptosis assays on BSMC. Both annexin V-propidium iodide staining (n=5-10) and single cell gel electrophoresis assays (n=4) were negative for necrosis and apoptosis in BSMC exposed to 10 microM bumetanide. Subsequent analysis of the cell cycle by flow cytometry showed that bumetanide-exposed BSMC were delayed in G1 phase compared with controls (n=4-8). This is the first evidence for loop diuretic inhibition of airway smooth muscle cell proliferation. NKCC cotransporter inhibition impeded G1-S phase transition without facilitating cell death. Thus although inhibition by loop diuretics relaxes airway smooth muscle, the NKCC cotransporter may have a more important role in cell proliferation regulation.
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http://dx.doi.org/10.1152/ajplung.00021.2004DOI Listing
September 2004

Cord blood units collected at a remote site: a collaborative endeavor to collect umbilical cord blood through the Hawaii Cord Blood Bank and store the units at the Puget Sound Blood Center.

Transfusion 2004 Jan;44(1):111-8

Puget Sound Blood Center/Northwest Tissue Center, Seattle, Washington 98104, USA.

Background: Umbilical cord blood is a useful source of hematopoietic stem cells, especially because compared to equivalent HLA-matched stem cells from unrelated adult donors. A network of community collection sites targeted at particular ethnic groups and serviced by a central processing and storage facility can maximize the genetic diversity of banked cord blood units (CBUs) in a cost-effective fashion.

Study Design And Methods: The present study compared CBUs collected near the Puget Sound Blood Center in Seattle, WA, with those collected in Honolulu, HI, and processed in Seattle. Evaluated variables include collection volume, total nucleated cell count, cellular viability, CD34+ cell count, clonogenic activity, and donor race for a total of 1646 CBUs received from July 1998 through November 2002.

Results: CBUs from the two sites did not differ with regard to volume or total nucleated cells. Those from Hawaii had significantly longer transit times (p < 0.001) and lower whole cord blood cell viability. However, the numbers of CFU and viable CD34+ cells were not affected by remote collection. CBUs screened from Seattle were largely from Caucasian donors, whereas over 85 percent of those from Honolulu were from donors of Asian-Pacific Islander or mixed ethnicity.

Conclusion: These studies demonstrate the feasibility of long-distance umbilical cord blood banking. Arrangements such as those described here could be used to help target cost-effective collection from minority populations and increase the HLA and ethnic diversity for CBUs.
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http://dx.doi.org/10.1046/j.0041-1132.2004.00614.xDOI Listing
January 2004

Targeting oncogene expression in a childhood cancer.

Hawaii Med J 2003 Oct;62(10):224-5

Cancer Research Center of Hawaii, USA.

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October 2003

N-myc oncogene expression in neuroblastoma is driven by Sp1 and Sp3.

Mol Genet Metab 2003 Sep-Oct;80(1-2):272-80

Molecular Carcinogenesis Section, Cancer Etiology Program, Cancer Research Center of Hawaii, The University of Hawaii at Manoa, 1236 Lauhala Street, Honolulu, HI 96813-2424, USA.

Regulation of N-myc oncogene expression is an important determinant of the biological behavior of neuroblastoma. The N-myc promoter contains several potential binding sites for transcription factors of the Sp1 family. Mutation of a CT-box motif contained within a 26 bp region required for N-myc downregulation by retinoic acid decreased basal transcriptional activity and altered DNA-protein interactions of the promoter, while mutations flanking this motif did neither. On super-shift, this region was shown to recruit Sp1 and Sp3 transcription factor proteins, while a functionally significant CT-box mutation resulted in their replacement by NF-1 transcription factor. Lysates from Drosophila S2 cells expressing exogenous Sp1, Sp3, and NF-1 proteins were able to partially mimic gel shift complexes seen with neuroblastoma nuclear extract and either wild type or mutant probes. Transient transfections of S2 cells showed that both individually and together, Sp1 and Sp3 were able to trans-activate a wild type CT-box-driven luciferase reporter construct in a dose-dependent manner. Transfection of the wild type but not mutant CT-box oligonucleotide was able to decrease endogenous N-myc expression in neuroblastoma cells. Together these results suggest that the CT-box element serves a critically functional role, and in the basal state, allows for N-myc trans-activation by Sp1 and Sp3. Moreover when mutated, the CT-box may still function as a binding motif for alternate transcription factors such as NF-1 that can allow persistent N-myc expression.
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http://dx.doi.org/10.1016/s1096-7192(03)00133-1DOI Listing
November 2004

Immunolocalization of a Na-K-2Cl cotransporter in human tracheobronchial smooth muscle.

J Appl Physiol (1985) 2003 Apr 6;94(4):1596-601. Epub 2002 Dec 6.

Department of Pediatrics, Kapiolani Medical Center for Women and Children and John A. Burns School of Medicine, Hawaii 96822, USA.

Inhibition of the Na-K-2Cl (NKCC) cotransporter by loop diuretics is associated with airway relaxation, but there has been no direct evidence for the expression of this protein in airway smooth muscle. Thus we hypothesized that a NKCC cotransporter is present and functional in airway smooth muscle cells. Monoclonal and polyclonal antibodies were used first to demonstrate the presence of a NKCC cotransporter protein in isolated human fetal trachea and normal human bronchial smooth muscle cells (BSMC) by Western blotting. The cotransporter protein was then localized by immunohistochemical staining to airway smooth muscle cells in culture and in situ. The localization was confirmed by indirect immunofluorescence and laser confocal microscopy in the BSMC. Cotransporter function in BSMC was also confirmed in vitro by bumetanide-mediated inhibition of rubidium uptake. Our present findings thus document the presence of a functional NKCC cotransporter in human airway smooth muscle, providing a basis for defining the role of this ion cotransporter in airway smooth muscle function.
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http://dx.doi.org/10.1152/japplphysiol.00621.2002DOI Listing
April 2003
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