Epigenetic Regulation of Ameloblast Differentiation by HMGN Proteins

Dental enamel formation is coordinated by ameloblast differentiation, production of enamel matrix proteins, and crystal growth. The factors regulating ameloblast differentiation are not fully understood. Here we show that the high mobility group N (HMGN) nucleosomal binding proteins modulate the rate of ameloblast differentiation and enamel formation. We found that HMGN1 and HMGN2 proteins are downregulated during mouse ameloblast differentiation. Genetically altered mice lacking HMGN1 and HMGN2 proteins show faster ameloblast differentiation and a higher rate of enamel deposition in mice molars and incisors. In vitro differentiation of induced pluripotent stem cells to dental epithelium cells showed that HMGN proteins modulate the expression and chromatin accessibility of ameloblast-specific genes and affect the binding of transcription factors epiprofin and PITX2 to ameloblast-specific genes. Our results suggest that HMGN proteins regulate ameloblast differentiation and enamel mineralization by modulating lineage-specific chromatin accessibility and transcription factor binding to ameloblast regulatory sites.

Bone Sialoprotein Is Critical for Alveolar Bone Healing in Mice

Bone sialoprotein (BSP) is an extracellular matrix (ECM) protein associated with mineralized tissues, particularly bone and cementum. BSP includes functional domains implicated in collagen binding, hydroxyapatite nucleation, and cell signaling, although its function(s) in osteoblast and osteoclast differentiation and function remain incompletely understood. Genetic ablation of BSP in Ibsp knockout (Ibsp-/-) mice results in developmental bone mineralization and remodeling defects, with alveolar bone more severely affected than the femurs and tibias of the postcranial skeleton. The role of BSP in alveolar bone healing has not been studied. We hypothesized that BSP ablation would cause defective alveolar bone healing. We employed a maxillary first molar extraction socket healing model in 42-d postnatalIbsp-/- and wild-type (WT) control mice. Tissues were collected at 0, 7, 14, 21, and 56 d postprocedure (dpp) for analysis by micro-computed tomography (microCT), histology, in situ hybridization (ISH), immunohistochemistry (IHC), and quantitative polymerase chain reaction (qPCR) array. As expected, alveolar bone healing progressed in WT mice with increasing bone volume fraction (BV/TV), bone mineral density (BMD), and tissue mineral density (TMD), transitioning from woven to mature bone from 7 to 56 dpp. Ibsp messenger RNA (mRNA) and BSP protein were strongly expressed during alveolar bone healing in parallel with other osteogenic markers. Compared to WT, Ibsp-/- mice exhibited 50% to 70% reduced BV/TV and BMD at all time points, 7% reduced TMD at 21 dpp, abnormally increased Col1a1 and Alpl mRNA expression, and persistent presence of woven bone and increased bone marrow in healing sockets. qPCR revealed substantially dysregulated gene expression in alveolar bone of Ibsp-/- versus WT mice, with significantly disrupted expression of 45% of tested genes in functional groups, including markers for osteoblasts, osteoclasts, mineralization, ECM, cell signaling, and inflammation. We conclude that BSP is a critical and nonredundant factor for alveolar bone healing, and its absence disrupts multiple major pathways involved in appropriate healing.

Seven-day holter monitoring detects more significant arrhythmias than 24-hour and 3-day monitoring

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction

24-hour Holter monitors have been used widely to assess patients with suspected and known arrhythmias. Recent studies have shown increased yield of arrhythmia detection with longer durations of Holter monitoring.

Purpose

The aim of the study was to evaluate the incremental yield in significant arrhythmias detected using a 7-day continuous Holter monitor, as compared to what can be achieved within a 24-hour and 48 to 72 hours study.

Methods

A retrospective study of patients from 72 sites in two geographical locations, A and B, who completed a continuous 7-days patch monitor study was performed. 801 of these studies detected significant arrhythmias; pauses 3 seconds or more (PA), ventricular tachycardia of 6 beats or more (VT), and paroxysmal atrial fibrillation (PAF). The day of the first occurrence of a significant arrhythmia was noted and tallied to determine the incremental yield of a multiday Holter monitoring.

Results

Of 801 total cases detected with significant arrhythmia, only 278 (35%) were detected in the first 24hours, while 523 (65%) cases were detected after Day 1. 331 (41%) had first significant arrhythmia detected after the 3rd day of monitoring, with 68 (44%) being PA, 125 (40%) PAF, and 138 (41%) VT. Notably, in Group A, 31 (72%) of total VT detected and 35 (72%) of total PAF detected were first picked up after Day 1, 21 (49%) of total VT were first detected only after the 3rd day of monitoring.

Conclusions

1-day (24-hour) monitoring period fails to detect a significant number of potentially serious cardiac arrhythmias. Extended continuous Holter monitoring increases the yield of detection, with a substantial fraction (40-49%) detected after the 3rd day of monitoring. No difference in results obtained between two geographical locations demonstrates strong evidence that findings are consistent across different sites. Review of current practice and guidelines is necessary to further expand usage of multiday Holter monitoring, thus increasing benefits to patients.

First-in-human phase I study of copanlisib (BAY 80-6946), an intravenous pan-class I phosphatidylinositol 3-kinase inhibitor, in patients with advanced solid tumors and non-Hodgkin's lymphomas

BACKGROUND

To evaluate the safety, tolerability, pharmacokinetics, and maximum tolerated dose (MTD) of copanlisib, a phosphatidylinositol 3-kinase inhibitor, in patients with advanced solid tumors or non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Phase I dose-escalation study including patients with advanced solid tumors or NHL, and a cohort of patients with type 2 diabetes mellitus. Patients received three weekly intravenous infusions of copanlisib per 28-day cycle over the dose range 0.1-1.2 mg/kg. Plasma copanlisib levels were analyzed for pharmacokinetics. Biomarker analysis included PIK3CA, KRAS, BRAF, and PTEN mutational status and PTEN immunohistochemistry. Whole-body [(18)F]-fluorodeoxyglucose positron emission tomography ((18)FDG-PET) was carried out at baseline and following the first dose to assess early pharmacodynamic effects. Plasma glucose and insulin levels were evaluated serially.

RESULTS

Fifty-seven patients received treatment. The MTD was 0.8 mg/kg copanlisib. The most frequent treatment-related adverse events were nausea and transient hyperglycemia. Copanlisib exposure was dose-proportional with no accumulation; peak exposure positively correlated with transient hyperglycemia post-infusion. Sixteen of 20 patients treated at the MTD had reduced (18)FDG-PET uptake; 7 (33%) had a reduction >25%. One patient achieved a complete response (CR; endometrial carcinoma exhibiting both PIK3CA and PTEN mutations and complete PTEN loss) and two had a partial response (PR; both metastatic breast cancer). Among the nine NHL patients, all six with follicular lymphoma (FL) responded (one CR and five PRs) and one patient with diffuse large B-cell lymphoma had a PR by investigator assessment; two patients with FL who achieved CR (per post hoc independent radiologic review) were on treatment >3 years.

CONCLUSION

Copanlisib, dosed intermittently on days 1, 8, and 15 of a 28-day cycle, was well tolerated and the MTD was determined to be 0.8 mg/kg. Copanlisib exhibited dose-proportional pharmacokinetics and promising anti-tumor activity, particularly in patients with NHL.

CLINICALTRIALSGOV

NCT00962611; https://clinicaltrials.gov/ct2/show/NCT00962611.

Restless legs syndrome: an underappreciated and distressing problem for haemodialysis patients

Restless legs syndrome is a distressing condition that is more common in patients with end-stage renal failure. Despite the significant impact it has on quality of life and the documented association between restless legs syndrome and increased mortality, limited data regarding the epidemiology of restless legs syndrome in Australian dialysis patients are available. We report a prospective study that assessed the prevalence and factors associated with restless legs syndrome in an in-centre haemodialysis population.

Does it matter what you call it? A randomized trial of language used to describe palliative care services

INTRODUCTION

Integration of palliative care into oncology practice remains suboptimal. Misperceptions about the meaning of palliative care may negatively impact utilization.

PURPOSE

We assessed whether the term and/or description of palliative care services affected patient views.

METHODS

2x2 between-subject randomized factorial telephone survey of 169 patients with advanced cancer. Patients were randomized into one of four groups that differed by name (supportive care vs. palliative care) and description (patient-centered vs. traditional). Main outcomes (0-10 Likert scale) were patient understanding, impressions, perceived need, and intended use of services.

RESULTS

When compared to palliative care, the term supportive care was associated with better understanding (7.7 vs. 6.8; p = 0.021), more favorable impressions (8.4 vs. 7.3; p = 0.002), and higher future perceived need (8.6 vs. 7.7; p = 0.017). There was no difference in outcomes between traditional and patient-centered descriptions. In adjusted linear regression models, the term supportive care remained associated with more favorable impressions (p = 0.003) and higher future perceived need (p = 0.022) when compared to palliative care.

CONCLUSIONS

Patients with advanced cancer view the name supportive care more favorably than palliative care. Future efforts to integrate principles of palliative medicine into oncology may require changing impressions of palliative care or substituting the term supportive care.

Correlation between oxidative stress and L-type calcium channel expression in the ventricular myocardia of selenium-deficient mice

OBJECTIVE

Expression of the Cacna1c (calcium channel, voltage-dependent, L-type, α1C subunit) gene was studied to investigate the relationship between oxidative stress and L-type calcium channels in the myocardium of selenium-deficient mice.

METHODS

Selenium levels in liver and heart tissue samples from mice fed normal or selenium-deficient diets were evaluated by fluorometry. In the same mice, glutathione peroxidase (GPx) and Cacna1c gene expression were analysed, malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were measured, oxidoreductase gene expression profiles were analysed (by DNA microarray), and myocardial structural changes were studied.

RESULTS

In selenium-deficient versus control mice, GPx expression and SOD activity were decreased, and Cacna1c expression and MDA concentration were increased. Selenoprotein oxidoreductase and nonselenoprotein oxidoreductase gene expression differed significantly between selenium-deficient and control mice. In selenium-deficient mice, myocardial fibres were separated by loose collagenous tissue; electron microscopy showed shortened sarcomeres, dilated sarcoplasmic reticulum, scattered myofibril lysis and increased mitochondria with amorphous matrix densities.

CONCLUSION

L-type calcium channels were involved in selenium deficiency-induced cardiomyocyte injury, which was positively related to oxidative stress.

Accelerated cellular senescence in solid tumor therapy

Accelerated cellular senescence (ACS) is an emerging concept that implicates sustained, telomere-independent cell cycle arrest of neoplastic cells in response to chemotherapeutic agents, ionizing radiation, oxidative stress, or the presence of selective oncogenic stimuli. Recent evidence suggests that a subset of tumor cells induced in a state of reversible ACS can escape cell cycle arrest and resume proliferation accounting for cancer progression. The purpose of this review is to describe our current understanding of ACS including signaling pathways of senescence escape, role of senescence biomarkers, and rationale for senescence-based therapy. This article is part of a Special Issue entitled "Apoptosis: Four Decades Later".

Comparative clinical efficacy of adjuvant chemotherapy regimens in randomized controlled trials (RCTs) of early-stage colon cancer: Systematic review and meta-analysis

498

Background: A systematic review was conducted to identify RCTs of adjuvant chemotherapy regimens for early-stage colon cancer and a network meta-analysis performed to compare efficacy of oxaliplatin/fluoropyrimidine regimens.

Methods: A systematic review identified RCTs recruiting adult patients with early-stage (adjuvant) stage II/III colon cancer. Outcome measures included hazard ratios for DFS and OS. Only publications in English were considered. Study quality was assessed using the Cochrane Collaboration “risk of bias” assessment tool. A single reviewer screened abstracts/titles using predefined selection criteria, with critical appraisal and data extraction conducted independently by two reviewers. A Bayesian network meta-analysis was used to estimate comparative efficacy of adjuvant chemotherapy across RCTs.

Results: 56 articles describing 40 trials were selected, of which six reported data on regimens accepted as current standard of care (capecitabine/X-ACT, XELOX/NO16968, FOLFOX/MOSAIC, FLOX/C-07) or common comparators: bolus 5FU/LV and LV5FU2 (C-96-1, PETACC-2). Statistical assessment of heterogeneity was not possible due to the limited study network. Baseline characteristics were similar across trials with the exception of three trials recruiting only stage III patients; sub-group analysis on these trials was not possible due to lack of common comparators. There was no significant difference in DFS at a median follow-up of 3-years (or closest reported analysis) for XELOX vs. FLOX (HR=0.99, 95% CI 0.80–1.22) or FOLFOX (HR=1.00, 95% CI 0.72–1.41). There was also no significant difference in OS at a median follow-up of at least 5 years. Taken as a class, oxaliplatin-containing regimens (XELOX, FOLFOX, FLOX) improved DFS vs. non-oxaliplatin-containing regimens (HR=0.80, 95% CI 0.73–0.87). This result was confirmed for OS.

Conclusions: Despite the limited number of available trials, the results of these analyses demonstrate a clear benefit of incorporating oxaliplatin into combination regimens for early-stage colon cancer. XELOX, FOLFOX and FLOX appear to be equivalent in terms of efficacy in this setting.

[Table: see text]

A phase II study of capecitabine (CAP) plus PHY906 in patients (pts) with advanced pancreatic cancer (APC)

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Background: Gemcitabine (G) is regarded as the standard treatment for pts with APC. However, a standard second-line chemotherapy regimen has yet to be defined after G. PHY906, a 4-herb traditional Chinese medicine has a history of > 1,800 yrs of human use to treat GI symptoms including diarrhea. Preclinical studies showed that PHY906 may potentiate antitumor activity of CAP in human PANC-1 xenograft (ASCO 2007). A phase I study showed that CAP can be escalated up to 1750 mg/m2 PO BID on d1- 7 and PHY906 800mg PO BID on d1–4 q 2 wks with no DLTs (ASCO, 2008). Delivered dose-intensity of CAP was similar at 1750mg/m2 dose level as 1500mg/m2. Therefore, 1500mg/m2 of CAP and PHY906 was further tested in a phase II study as second-line treatment in pts with APC. Methods: Pts with G-refractory APC with ECOG PS <2 were treated with CAP 1500mg/m2 d1–7 with PHY906 800mg d1–4 q 2 wks. Response was assessed by CT scan according to RECIST q 6 wks and toxicity according to NCI-CTC v3.0. Primary objective is overall survival. Secondary objectives include overall RR, PFS and measurement of cytokines to assess inhibition of NF-kappa B, a possible mechanism responsible for PHY906's pharmacological activity. Results: As of January 5, 2009, 25 pts have been enrolled. Baseline characteristics include median age, 65 (range, 40–85); male/female,15/10; ECOG PS 0/1, 4/19; median cycles: 3 (r: 0.5–15). At this point 5 pts are still in active treatment. 4 pts have confirmed OS > 6 ms (1 still on study) with 2 further pts approaching 6 ms. Among evaluable pts, 1 had PR (5.3%), 11 SD (57.9%) and 7 PD (36.8%) after initial restaging scan. 36 % pts had >30% reduction in CA19–9 as biochemical response. There were 7 deaths on/within 30 days of study treatment, 6 related to PD and 1 had acute MI. G3/4 toxicities diarrhea 3/25 (12%), fatigue, 1/25 (4%), HFS 1/25 (4%) and mucositis 1/25 (4%). 1 pt was removed from study due to G3 HFS. Biomarker studies (IL4, GM-CSF, TNF-alpha, IL10, MCP-1, IL2, IL6) are ongoing. Conclusions: This is the first clinical study to evaluate a botanical formulation PHY906 with CAP in G-refractory APC pts. CAP + PHY906 regimen appears a safe and feasible salvage therapy in APC and warrants further investigation. In addition, PHY906 may have a cytoprotective antidiarrheal and anti-HFS effect, making treatment with CAP more tolerable.

[Table: see text]

Phase I/II study of PHY906/capecitabine in hepatocellular carcinoma

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Traditional botanical formulations in combination with conventional antitumor chemotherapeutics may prove a powerful approach in reducing toxicity and improving clinical outcomes. In vivo studies show that PHY906, a traditional Chinese formulation, can reduce chemo-induced gastrointestinal toxicity while enhancing the therapeutic efficacy of a broad-spectrum of common anticancer agents in various cancer models, including capecitabine, CPT-11, thalidomide, adriamycin, and sorafenib in liver cancer; gemcitabine, capecitabine, oxaliplatin, gem/ox in pancreatic cancer; and CPT-11, 5-FU, sorafenib, VP-16, L-OddC, CPT-11/5-FU/LV, and oxaliplatin/5-FU/LV in colorectal cancer. Co- administration of PHY906 with a host of chemotherapeutic agents appears to neither alter the pharmacokinetic profiles of the chemotherapeutic agents nor their respective metabolites. PHY906 is currently being studied in a phase I/II, multicenter, open-label, dose-modification, safety and efficacy study in combination with capecitabine in patients with non-resectable HCC in the U.S. and Taiwan. Phase I patients (n=18) were enrolled at COH, Yale, VA and Stanford beginning November 2003. The primary objective of phase I was the determination of a safe dose regimen by varying the dose levels of PHY906 and/or capecitabine. Three dose levels of PHY906 + capecitabine were evaluated: PHY906 1000 mg BID + Capecitabine 1000 mg/m2 BID; PHY906 600 mg BID + Capecitabine 750 mg/m2 BID; and PHY906 800 mg BID + Capecitabine 750 mg/m2 BID. The final dosing level was chosen for the phase II portion of the study. Preliminary results suggest that the quality of life of patients on PHY906 + capecitabine was improved when compared to historical controls studying capecitabine alone. There is also no evidence of drug-induced toxicity caused by PHY906; nor does PHY906 reduce capecitabine antitumor activity. For patients receiving capecitabine at 750 mg/m2 BID and PHY906 at either 600 mg BID (N=4) or 800 mg BID (N=24), 10.7% (N=3) achieved minor response (MR), 50% (N=14) had stable disease (SD) and 39.3% (N=11) had progressive disease (PD). These findings support the further investigation of PHY906 as an adjuvant therapy of capecitabine in a larger HCC population.

No significant financial relationships to disclose.

Translational regulation as a novel mechanism for the development of cellular drug resistance

Cellular drug resistance is one of the principal obstacles to the clinical efficacy of cancer chemotherapy. In this review, we describe the potential role for translational regulation as a novel mechanism for modulating chemosensitivity. The evidence for the translational control of thymidylate synthase, dihydrofolate reductase, and p53 will be presented, as will experimental data showing how disruptions in this important regulatory process can lead to the rapid emergence of cellular drug resistance.

An adverse interaction between warfarin and capecitabine: a case report and review of the literature

Warfarin is one of the most commonly used oral anticoagulants in the clinic. It is well established that a wide range of antineoplastic drugs interact with warfarin, resulting in altered coagulation parameters and/or bleeding sequelae. While altered coagulation parameters have been observed in patients taking the oral 5-fluorouracil prodrug, capecitabine, in combination with warfarin, no report to date has described clinically overt evidence of bleeding. Herein, we report 2 cancer patients who presented with bleeding episodes that most likely resulted from an adverse interaction between capecitabine and warfarin after 6 weeks of concomitant therapy. In each case, there was a marked elevation in both the prothrombin time and international normalized ratio (> 10), with subsequent gastrointestinal bleeding. The exact mechanism of this interaction is yet unknown, but it is possible that capecitabine might, in some manner, reduce the hepatic metabolism of warfarin. Close monitoring of coagulation parameters is recommended for all patients receiving concomitant warfarin and capecitabine, with appropriate adjustment of warfarin dosage. The nature and extent of this interaction requires further investigation.

A prospective study of stress among women undergoing in vitro fertilization or gamete intrafallopian transfer

OBJECTIVE

To evaluate whether baseline or procedural stress during in vitro fertilization (IVF) or gamete intrafallopian transfer (GIFT) affects pregnancy or live birth delivery rates.

DESIGN

Prospective study.

SETTING

Seven clinics in Southern California between 1993 and 1998.

PATIENT(S)

One hundred and fifty-one women completed two questionnaires.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The number of oocytes aspirated and fertilized, the number of embryos transferred, the achievement of a pregnancy, live birth delivery, and infant outcomes.

RESULT(S)

Positive-affect negative-affect score at baseline negatively influenced the number of oocytes retrieved and embryos transferred. A higher expectation of pregnancy was associated with greater numbers of oocytes fertilized and embryos transferred. At baseline, the risk of no live birth was 93% lower for women who had the highest positive-affect score compared to those with the lowest score. Furthermore, the score on the Infertility Reaction Scale was related to negative outcomes in live birth delivery, infant birth weight, and multiple births. During the time of the procedure, the PANAS and Bipolar Profile of Moods States results were related to the number of oocytes fertilized and embryos transferred; stress did not affect pregnancy or delivery.

CONCLUSION(S)

Baseline (acute and chronic) stress affected biologic end points (i.e., number of oocytes retrieved and fertilized), as well as pregnancy, live birth delivery, birth weight, and multiple gestations, whereas (procedural) stress only influenced biologic end points.

Remarkable application of serum EBV EBER-1 in monitoring response of nasopharyngeal cancer patients to salvage chemotherapy

Nineteen consecutive patients with metastatic or recurrent nasopharyngeal cancer (NPC) receiving combination chemotherapy were monitored for EBV DNA in their serum. EBV DNA (EBER-1) concentration in serum was measured before, during, and after chemotherapy. Thirteen patients had additional multiple prechemotherapy readings. There was a significant lead time from first detection of serum EBER-1 to clinical recurrence in 62% of patients by a mean of 17.4 weeks (range: 8-74.5 weeks; mean = 28.2 weeks if confined to the 8 patients with significant lead time). The median EBER-1 concentration was significantly higher in those with distant metastasis as compared to those with loco-regional recurrence only (17,468 vs. 684 pg/mL serum; p = 0.046, Mann-Whitney U test). Among the 13 patients who responded to chemotherapy, 4 exhibited clinical complete remission (CR) who were only found in the group with EBER-1 DNA drop to background level, while the magnitude of EBER-1 drop did not discriminate partial remission (PR) and stable disease (SD) patients clearly. Subsequent profile of EBER-1 DNA showed concordance with clinical course of either continuous remission or later progression. EBER-1 DNA in serum can become a useful adjunctive surrogate marker to monitor chemotherapeutic response in NPC patients with distant metastasis or advanced local recurrence.

Physical interaction between p53 and primary response gene Egr-1

The tumor suppressor p53 and primary response gene Egr-1 are nuclear transcription factors with regulatory roles in signal transduction pathways mediating cellular proliferation and growth arrest as well as the complex genetic programs controlling differentiation and programmed cell death. We identified a physical association between these regulatory proteins in vitro and in vivo. Recombinant p53 and Egr-1 fusion proteins complexed with in vitro translates of Egr-1 or p53, respectively, or with these respective proteins in cell lysates. This protein-protein interaction was detected in vivo by immunoprecipitation and Western blot analysis of serum-activated cellular lysates with high levels of induced Egr-1 and of human lung cancer cell lines with constitutive overexpression of Egr-1 and mutant p53. A p53 mutant at codon 154 did not bind Egr-1, while p53 proteins with point mutations at residues 156, 246, 247, and 273 associated with this zinc finger transcription factor. p53 bound full-length Egr-1 and an Egr-1 mutant with a deletion of the 5' transactivation region but did not associate with Egr-1 protein lacking an internal segment that included the first two zinc finger domains, suggesting that binding may require the presence of intact zinc finger motifs. A variant-sized Egr-1 protein expressed by lung fibroblast cell line MRC-9 was also bound by p53. The interaction of these regulatory proteins may alter multiple features of their biological activity especially with regard to the specificity of transcriptional control.

Effect of 2'-O-methyl antisense ORNs on expression of thymidylate synthase in human colon cancer RKO cells

Translation of thymidylate synthase (TS) mRNA is controlled by its own protein end-product TS in a negative autoregulatory manner. Disruption of this regulation results in increased synthesis of TS and may lead to the development of cellular drug resistance to TS-directed anticancer agents. As a strategy to inhibit TS expression, antisense 2'-O-methyl RNA oligoribonucleotides (ORNs) were designed to directly target the 5' upstream cis-acting regulatory element (nucleotides 80-109) of TS mRNA. A 30 nt ORN, HYB0432, inhibited TS expression in human colon cancer RKO cells in a dose-dependent manner but had no effect on the expression of beta-actin, alpha-tubulin or topoisomerase I. TS expression was unaffected by treatment with control sense or mismatched ORNs. HYB0504, an 18 nt ORN targeting the same core sequence, also repressed expression of TS protein. However, further reduction in oligo size resulted in loss of antisense activity. Following HYB0432 treatment, TS protein levels were reduced by 60% within 6 h and were maximally reduced by 24 h. Expression of p53 protein was inversely related to that of TS, suggesting that p53 expression may be directly linked to intracellular levels of TS. Northern blot analysis demonstrated that TS mRNA was unaffected by HYB0432 treatment. The half-life of TS protein was unchanged after antisense treatment suggesting that the mechanism of action of antisense ORNs is mediated through a process of translational arrest. These findings demonstrate that an antisense ORN targeted at a critical cis-acting element on TS mRNA can specifically inhibit expression of TS protein in RKO cells.

In vitro selection of an RNA sequence that interacts with high affinity with thymidylate synthase

Previous studies have shown that the repressive effect of thymidylate synthase (TS) mRNA translation is mediated by direct binding of TS itself to two cis-acting elements on its cognate mRNA. To identify the optimal RNA nucleotides that interact with TS, we in vitro synthesized a completely degenerate, linear RNA pool of 25 nt and employed in vitro selection to isolate high affinity RNA ligands that bind human TS protein. After 10 rounds of selection and amplification, a single RNA molecule was selected that bound TS protein with nearly 20-fold greater affinity than native, wild-type TS RNA sequences. Secondary structure analysis of this RNA sequence predicted it to possess a stem-loop structure. Deletion and/or modification of the UGU loop element within the RNA sequence decreased binding to TS by up to 1000-fold. In vivo transfection experiments revealed that the presence of the selected RNA sequence resulted in a significant increase in the expression of a heterologous luciferase reporter construct in human colon cancer H630 and TS-overexpressing HCT-C:His-TS+ cells, but not in HCT-C18 cells expressing a functionally inactive TS. In addition, the presence of this element in H630 cells leads to induced expression of TS protein. An immunoprecipitation method using RT-PCR confirmed a direct interaction between human TS protein and the selected RNA sequence in transfected human cancer H630 cells. This study identified a novel RNA sequence from a degenerate RNA library that specifically interacts with TS.

Molecular heterogeneity and function of EWS-WT1 fusion transcripts in desmoplastic small round cell tumors

Desmoplastic small round cell tumor (DSRCT) is a primitive sarcoma with a consistent cytogenetic abnormality, t(11;22)(p13;q12). This chromosomal translocation generates a chimeric transcript that is formed by fusion of the 5' region of the Ewing's sarcoma gene, EWS, with the 3' DNA-binding segment of WT1, the Wilms' tumor suppressor gene. We collected 14 DSRCT tumor samples and examined the hybrid transcripts. We identified: (a) combinatorial heterogeneity of EWS exons fused to WT1 including use of EWS exons 7, 8, and 9; (b) subpopulations of variant transcripts in 6 of 14 tumors characterized by aberrant splicing resulting in loss of EWS exon 6 or WT1 exon 9; (c) multiple cDNA products with large internal deletions; and (d) insertion of small stretches of heterologous DNA at the fusion site or exon splice region in transcripts from two tumors. Most of the splice variants were in-frame, and in vitro translated fusion proteins with intact DNA-binding motifs formed complexes with a WT1 response element in gel mobility assays. Each of the chimeric proteins retains the ability to bind to the GC and TC elements of the early transcription factor EGR-1 as well as WT1 consensus sequences. We present evidence that various EWS-WT1 proteins up-regulated EGR-1 promoter activity and that this up-regulation is specifically dependent upon the absence of the exon 9 KTS domain of WT1. The molecular diversity and functionality exhibited by these fusion transcripts may have significant biological implications for their transactivating and tumorigenic potential.

Thyroid cancer: patients' experiences of receiving iodine-131 therapy

PURPOSE/OBJECTIVES

To enhance understanding of the experiences and educational needs of patients receiving iodine-131 (131I) therapy for the treatment of thyroid cancer.

DESIGN

Qualitative design using interpretive description.

SETTING

A 24-bed oncology/acute-care medical unit in a large tertiary hospital in western Canada.

SAMPLE

5 men and 22 women (18-80 years of age) who have received 131I therapy in the past two years.

METHODS

Unstructured focus group and telephone interviews and field notes. Interviews were tape-recorded, transcribed verbatim, and subjected to thematic analysis.

FINDINGS

Researchers elicited four major themes from the analysis: (a) recognizing the totality of the cancer experience, (b) being isolated, (c) recognizing the totality of the treatment experience, and (d) understanding barriers to treatment.

CONCLUSIONS

Healthcare providers require a better understanding of thyroid disease and the treatment and side effects of 131I therapy. Furthermore, educational programs are required to adequately prepare nurses and patients for future care.

IMPLICATIONS FOR NURSING PRACTICE

A need exists to improve the care and education provided to patients receiving 131I therapy. In particular, recognition of the totality of the cancer experience and the need for both staff and patient education were illustrated. If nurses are to provide comprehensive cancer care, both psychosocial and physical needs must be addressed and fulfilling these needs requires a collaborative approach among patients, nurses, and other healthcare professionals.

Mechanisms and sites of ocular action of 7-hydroxy-2-dipropylaminotetralin: a dopamine(3) receptor agonist

The purpose of this study was to investigate mechanism(s) and site(s) of action involved in 7-hydroxy-2-dipropylaminotetralin (7-OH-DPAT)-induced ocular hypotension. As measured by pneumatonometry, the topical, unilateral application of 7-OH-DPAT (75 microg), a dopamine D(3)-preferring receptor agonist, decreased the intraocular pressure (IOP) bilaterally. The ocular hypotensive activity of 7-OH-DPAT was diminished in sympathetically denervated rabbits. Pretreatment with raclopride, a D(2)/D(3) receptor antagonist; UH232, a D(3) receptor antagonist; or U-99194A, a D(3) receptor antagonist antagonized 7-OH-DPAT-induced ocular hypotension. However, pretreatment with spiperone, a D(2) receptor antagonist, did not affect the 7-OH-DPAT-induced ocular hypotension. In addition, topically applied 7-OH-DPAT caused a reduction of aqueous humor flow rate. To examine sites of action, immunohistochemistry of D(3) dopamine receptors was performed. Dopamine D(3) receptors were found to be present on postganglionic sympathetic nerves in the ciliary body of normal rabbits but were virtually undetectable in the same tissue of sympathectomized rabbits. In summary, the IOP-lowering effect caused by 7-OH-DPAT was due, in part, to the suppression of aqueous humor flow. Immunohistochemical identification of D(3) receptors in the ciliary body, associated with the diminution of IOP-lowering effects by D(3) receptor agonist 7-OH-DPAT in sympathetically denervated rabbits provided evidence of neuronal site of action of 7-OH-DPAT. Suppression of 7-OH-DPAT-induced ocular hypotension by D(3) receptor antagonists (U-99194A and UH232) and sympathectomy, coupled with the immunohistochemical data, suggested that the primary site of D(3) receptor-mediated action of 7-OH-DPAT is located on postganglionic sympathetic nerve endings in the ciliary body of rabbit.

Characterization of a cis-acting regulatory element in the protein coding region of thymidylate synthase mRNA

Thymidylate synthase (TS) functions as an RNA-binding protein by interacting with two different sequences on its own mRNA. One site is located in the 5'-upstream region of human TS mRNA while the second site is located within the protein coding region corresponding to nt 434-634. In this paper, a 70 nt RNA sequence, corresponding to nt 480-550, was identified that binds TS protein with an affinity similar to that of full-length TS mRNA and TS434-634 RNA. In vitro translation studies confirmed that this sequence is critical for the translational autoregulatory effects of TS. To document in vivo biological significance, TS sequences contained within this region were cloned onto the 5'-end of a luciferase reporter plasmid and transient transfection experiments were performed using H630 human colon cancer cells. In cells transfected with p644/TS434-634 or p644/TS480-550, luciferase activity was decreased 2.5-fold when compared to cells transfected with p644 plasmid alone. Luciferase mRNA levels were identical for each of these conditions as determined by RNase protection and RT-PCR analysis. Immunoprecipitation of TS ribonucleoprotein complexes revealed a direct interaction between TS protein and TS480-550 RNA in transfected H630 cells. Treatment with 5-fluorouridine resulted in a nearly 2-fold increase in luciferase activity only in cells transfected with p644/TS434-634 and p644/TS480-550. This study identifies a 70 nt TS response element in the protein coding region of TS mRNA with in vitro and in vivo translational regulatory activity.