Students with specific learning disabilities experiences of pre-registration physiotherapy education: a qualitative study.

BACKGROUND: Attainment gaps for students with disabilities have been noted in pre-registration physiotherapy courses in the UK. Previous research suggests disclosure, lack of staff knowledge and poor communication between University and placement sites may be relevant, but these are limited to small case studies with students with visual or physical disabilities. The purpose of this study was to explore disabled physiotherapy students' experiences of their education in order to elucidate factors that may influence success. METHODS: Qualitative study drawing on phenomenological traditions. Four focus groups including 15 students with disabilities were conducted. Transcripts were analysed thematically. Procedures for transparency and rigour such as member checking and peer debriefing were implemented. RESULTS: Three major themes were derived from data. "It was quite a relief" explores the personal and social implications of diagnosis. "They're not natural" focuses on academic assessment and the specifics of adjustments made and not made within that context. "My dyslexia doesn't switch off" explores the inaccessibility of the learning environment and dissects the contrast between the 24-h nature of having a specific learning condition and the somewhat piecemeal nature of adjustments during their education. CONCLUSIONS: This study indicates that having a specific learning disability or anxiety creates a number of hurdles to success in physiotherapy education. Most were within the University setting and were perceived to result from staff ignorance or piecemeal approaches to inclusion. A lack of consistency alongside facilitated dialogue and acknowledgement of enhancements results in frustration, ambiguity towards disclosure and reinforcement of a deficit model. Such an approach belies the intention of the profession and the NHS and does not maximise the potential of widening participation.

Using the Provenance of Sediment and Bioavailable Phosphorus to Help Mitigate Water Quality Impact in an Agricultural Catchment.

The quality and health of surface waters can be impaired by sediment and sediment-bound phosphorus (P). The Waituna Lagoon catchment in southern New Zealand has undergone agricultural intensification that has been linked to increases in sediment and sediment-bound bioavailable P (BAP) in the lagoon. Time-integrated samplers trapped suspended sediment from the water column, and their geochemical signature was compared with likely sources (stream banks, stream beds, topsoil, and subsoil) in each of the lagoon's contributing streams and rivers. The proportion of BAP, but not necessarily total P, within trapped sediment was much greater in samples from the Moffat and Carran Creeks than from the Waituna Creek, probably due to the erosion of organic-rich soils that had little capacity to retain P compared with the more mineral soils of the Waituna Creek. Annually, most BAP and sediment came from bank erosion, and strategies such as fencing out stock should focus on minimizing this throughout the catchment. However, when considering losses in space and time relative to the impact on the Waituna Lagoon, strategies the Waituna Creek catchment should also minimize contributions from topsoil in winter-spring, whereas in the Carran and Moffat Creek catchments strategies need to decrease P inputs (e.g., effluent) to Organic soils likely to lose much BAP in summer-autumn when the impact on the Lagoon is quickest. This study highlighted the need to identify sources and timings of BAP and sediment loss before recommending mitigation practices, which without this information may be slow or not succeed.

ß-blockers increase response to chemotherapy via direct antitumour and anti-angiogenic mechanisms in neuroblastoma.

BACKGROUND: The use of ß-blockers for the management of hypertension has been recently associated with significant clinical benefits in cancer patients. Herein, we investigated whether ß-blockers could be used in combination with chemotherapy for the treatment of neuroblastoma. METHODS: Seven ß-blockers were tested for their antiproliferative and anti-angiogenic properties alone, and in combination with chemotherapy in vitro; the most potent drug combinations were evaluated in vivo in the TH-MYCN mouse model of neuroblastoma. RESULTS: Three ß-blockers (i.e., carvedilol, nebivolol and propranolol) exhibited potent anticancer properties in vitro and interacted synergistically with vincristine, independently of P-glycoprotein expression. ß-blockers potentiated the anti-angiogenic, antimitochondrial, antimitotic and ultimately pro-apoptotic effects of vincristine. In vivo, ß-blockers alone transiently slowed tumour growth as compared with vehicle only (P<0.01). More importantly, when used in combination, ß-blockers significantly increased the tumour regression induced by vincristine (P<0.05). This effect was associated with an increase in tumour angiogenesis inhibition (P<0.001) and ultimately resulted in a four-fold increase in median survival, as compared with vincristine alone (P<0.01). CONCLUSION: ß-blockers can increase treatment efficacy against neuroblastoma, and their combination with chemotherapy may prove beneficial for the treatment of this disease and other drug-refractory cancers.

Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems.

Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS.

Improved Sleep Quality Is Associated with Reduced Insulin Resistance in Cancer Survivors Undertaking Circuit, Interval-Based Exercise.

PURPOSE: Cancer patients often experience poor sleep quality, typically induced by cancer-related treatments, a sedentary lifestyle, and psychological distress, leading to an increased risk of metabolic dysregulation such as obesity and insulin resistance. In this novel 16-week pilot study, we examined the effect of a circuit-based aerobic and resistance exercise intervention on self-reported sleep quality in breast, prostate, and colorectal cancer survivors and explored the association between changes in sleep quality and insulin resistance. METHODS: Survivors of breast, prostate or colorectal cancers who were sedentary, overweight or obese (BMI>25.0 kg/m2) were randomized to exercise (n=60) or usual care (n=30). The 16-week intervention included supervised moderate-vigorous aerobic (65-85% of VO2max) and resistance (65-85% of 1-repetition maximum) exercise performed in a circuit, interval fashion three times per week. Patient-reported sleep quality and insulin resistance were assessed at baseline and post-intervention using Pittsburgh Sleep Quality Index (PSQI) and Homeostasis Model of Assessment (HOMA-IR), respectively. Mean changes in PSQI score that are negative demonstrate improvements in sleep. Between-group differences were determined using repeated-measures analysis of variance. Associations between changes in PSQI and insulin resistance were computed using Pearson correlations. RESULTS: Participants were 63.2±10.8 years old, obese (87%), female (55%), and completed chemotherapy + radiation therapy (75%). Adherence to the intervention was 92% and the retention rate was 100%. Post-intervention, the PSQI global score improved significantly in the exercise group when compared to usual care (mean between-group difference, -2.7; 95% CI, -4.2 to -0.6). Change in PSQI was inversely associated with change in HOMA-IR (r=-0.91; p<0.01) among the exercise group. CONCLUSIONS: A circuit, interval-based aerobic and resistance exercise intervention improved patient-reported sleep quality in breast, prostate, and colorectal cancer survivors. Additionally, this exercise-induced improvement in sleep-quality may result in reduced insulin resistance.

HLA-G polymorphisms, genetic susceptibility, and clinical outcome in childhood neuroblastoma.

Neuroblastoma is the most common solid tumor in children less than 5 years of age. The early onset of neuroblastoma suggests that genes involved in fetal development and pregnancy may have a putative role in the etiology of neuroblastoma. The human leukocyte antigen subtype G (HLA-G) molecule plays an important role in immune response regulation and appears to regulate immune tolerance during early pregnancy as well as tumor immunosurveillance. Elevated levels of soluble HLA-G (sHLA-G) have been detected in a number of malignancies including serum samples from neuroblastoma and have been reported to be predictive of tumor relapse in neuroblastoma. In light of previous investigations suggesting that single nucleotide polymorphisms in the HLA-G gene may impact on protein expression levels and isoform production, we examined the influence of HLA-G polymorphisms on the susceptibility and clinical outcome of neuroblastoma in 163 neuroblastoma patients and 404 healthy controls. The distribution of HLA-G polymorphisms, alleles, or allelic groups did not differ between children diagnosed with neuroblastoma and healthy controls. Our analyses did not detect an association between common HLA-G polymorphisms and clinical outcome in patients treated for neuroblastoma.

ATP7A is a novel target of retinoic acid receptor beta2 in neuroblastoma cells.

Increased retinoic acid receptor beta (RARbeta(2)) gene expression is a hallmark of cancer cell responsiveness to retinoid anticancer effects. Moreover, low basal or induced RARbeta(2) expression is a common feature of many human cancers, suggesting that RARbeta(2) may act as a tumour suppressor gene in the absence of supplemented retinoid. We have previously shown that low RARbeta(2) expression is a feature of advanced neuroblastoma. Here, we demonstrate that the ABC domain of the RARbeta(2) protein alone was sufficient for the growth inhibitory effects of RARbeta(2) on neuroblastoma cells. ATP7A, the copper efflux pump, is a retinoid-responsive gene, was upregulated by ectopic overexpression of RARbeta(2). The ectopic overexpression of the RARbeta(2) ABC domain was sufficient to induce ATP7A expression, whereas, RARbeta(2) siRNA blocked the induction of ATP7A expression in retinoid-treated neuroblastoma cells. Forced downregulation of ATP7A reduced copper efflux and increased viability of retinoid-treated neuroblastoma cells. Copper supplementation enhanced cell growth and reduced retinoid-responsiveness, whereas copper chelation reduced the viability and proliferative capacity. Taken together, our data demonstrates ATP7A expression is regulated by retinoic acid receptor beta and it has effects on intracellular copper levels, revealing a link between the anticancer action of retinoids and copper metabolism.

Blocks of limited haplotype diversity revealed by high-resolution scanning of human chromosome 21.

Global patterns of human DNA sequence variation (haplotypes) defined by common single nucleotide polymorphisms (SNPs) have important implications for identifying disease associations and human traits. We have used high-density oligonucleotide arrays, in combination with somatic cell genetics, to identify a large fraction of all common human chromosome 21 SNPs and to directly observe the haplotype structure defined by these SNPs. This structure reveals blocks of limited haplotype diversity in which more than 80% of a global human sample can typically be characterized by only three common haplotypes.

Taxol-resistant epithelial ovarian tumors are associated with altered expression of specific beta-tubulin isotypes.

The treatment of advanced ovarian cancer with taxol is hindered by the development of drug resistance. The cellular target for taxol is the microtubule that is stabilized by the drug. Taxol preferentially binds to the beta subunit of tubulin of which there are six distinct isotypes in mammalian cells. We have used highly specific oligonucleotides and polymerase chain reaction to analyze expression of all six beta-tubulin genes. Human lung cancer cells (A549) were selected in 12 and 24 nM taxol resulting in cell lines that were 9- and 17-fold resistant, respectively. These cells displayed an altered ratio of classes I, II, III, and IVa beta-tubulin isotypes. Ovarian tumors, seven untreated primary and four taxol- resistant tumor-bearing ascites, displayed significant increases (P < 0.005) in classes I (3.6-fold), III (4.4-fold), and IVa (7.6-fold) isotypes in the taxol-resistant samples as compared with untreated primary ovarian tumors. The increased expression appears to be related to the resistance phenotype, as the basal levels of the class III and IVa isotypes in the untreated tumors were extremely low. This is the first report of altered expression of specific beta-tubulin genes in taxol-resistant ovarian tumors and we propose that the latter may play a role in clinical resistance to taxol.

Does pulse lavage reduce hip hemiarthroplasty infection rates?

This paper reports a prospective randomized trial involving four hospitals in the south of England, in which every hemiarthroplasty (American Association of Anaesthetists grade IV and above) was randomized to one of two limbs. In the first group, the patients received a 2-L pulse lavage normal saline washout; in the second group, they received a 2-L normal saline washout via a jug or a syringe. All wounds were reviewed during their time in hospital up to 30 days post surgery or discharge (using criteria from the Nosocomial Infection National Surveillance Survey). Any re-admissions for infection were recorded. The pulse lavage group had a significantly lower total infection rate and, specifically, a decreased 'joint space' or deep infection rate.

Uptake, metabolism, mutant frequencies and mutational spectra in lambda transgenic medaka embryos exposed to benzo[alpha]pyrene dosed sediments.

The goal of this study was to provide data supporting the use of lambda transgenic medaka (Oryzias latipes) embryos to evaluate mutagens in sediments. Embryos incubated directly on sediments dosed with the reference mutagen, benzo[alpha]pyrene (BaP), were examined for BaP uptake and metabolism. Mutant frequency and mutational spectrum were assessed in the cII transgene recovered from adult medaka livers exposed as embryos. Embryos rapidly accumulated 14C-BaP and metabolized BaP to polar metabolites, indicating sediment-sorbed BaP is available for bioaccumulation and medaka embryos are capable of bioactivating this mutagen. Exposure of embryos to BaP dosed sediments significantly induced cII transgene mutant frequencies with mutations predominantly being in G:C base pairs, consistent with known mechanisms of BaP mutagenesis in transgenic mice and fish.

Resistance to drugs associated with the multidrug resistance phenotype following selection with high-concentration methotrexate.

To study patterns of resistance at extreme but nevertheless clinically relevant drug concentrations, we developed a series of methotrexate-selected CCRF-CEM sublines, all of which were highly resistant to this antifolate (relative resistance, 10(2)- to greater than 10(5)-fold). The least methotrexate-resistant subline was completely sensitive to drugs associated with the multidrug resistance phenotype. However, more highly methotrexate-resistant sublines were significantly cross-resistant to vincristine, vinblastine, and dactinomycin (maximum relative resistance, 40-fold). These sublines were not cross-resistant to doxorubicin, daunorubicin, and teniposide. Regression analysis indicated that relative resistance to methotrexate was correlated with relative resistance to vincristine (r = 0.96) and vinblastine (r = 0.99). Such cross-resistance in highly methotrexate-resistant cells may have important clinical implications.

Heterotransplantation of human lymphoid neoplasms using a nude mouse intraocular xenograft model.

There are few effective models for the study of human lymphoid neoplasms, including in vivo xenografts in immunocompromised animals. Exploiting the additional immune privilege of the anterior chamber of the nude mouse eye, a novel method of direct heterotransplantation of cells from childhood leukemias and lymphomas has been developed. The establishment and characterization of 18 lymphoid xenograft cell lines maintained in the nude mouse intraocular model are reported. Cell sources for heterotransplantation were specimens of bone marrow, peripheral blood, or lymphomatous masses obtained at either diagnosis or recurrence of disease in the patients. The 18 patients and resultant cell lines were grouped into four immunophenotypic categories: Category 1, B-lineage (pre-B and early pre-B), "common" acute lymphatic leukemias; Category 2, cell lines of similar immunophenotype derived from patients with unusual features; Category 3, B-cell neoplasms and cell lines; and Category 4, neoplasms and cell lines in part or totally of T-cell origin. With reference to these groupings, rates of ingraftment from clinical specimens varied according to immunophenotype and disease status: Category 1, 1 of 15 at diagnosis, 5 of 7 at relapse; Category 2, 1 of 1 at diagnosis, 2 of 2 at relapse; Category 3, 6 of 6 at diagnosis; and Category 4, 2 of 9 at diagnosis, 1 of 1 with persistent disease. Rearrangements of the genes for immunoglobulin heavy chain or kappa light chain and for beta subunit of the T-cell receptor gene were demonstrated according to immunophenotype, with the exception of one cell line which showed no rearrangements. Evidence of Epstein-Barr virus DNA was shown in only one cell line, of B-cell immunophenotype. Cytology, histopathology, and electron microscopy in representative patient and xenograft samples demonstrated correlations between the specimens of origin and cells or sections from ingrafted tumors in mice. It is concluded that the direct heterotransplantation of cells from childhood leukemias and lymphomas to the anterior chamber of the nude mouse eye provides a relevant and reproducible model for the maintenance and study of human lymphoid neoplasms.

Expression of the multidrug resistance-associated protein (MRP) gene correlates with amplification and overexpression of the N-myc oncogene in childhood neuroblastoma.

The MRP gene (Cole et al., Science (Washington DC), 258: 1650-1654, 1992) encodes a membrane-bound glycoprotein the expression of which correlates with non-P-glycoprotein-mediated multidrug resistance in a variety of cultured human cell lines. Using an RNA-polymerase chain reaction assay, expression of this gene was examined in the highly chemoresistant pediatric malignancy, neuroblastoma. MRP expression was observed in 5 human neuroblastoma cell lines and in all 25 primary neuroblastoma tumors of stage I through IVS. Tumors with amplification of the N-myc oncogene were found to have significantly higher MRP expression that those with no amplification (P = 0.0016). Expression of the MRP gene in the tumor specimens was highly correlated with expression of the N-myc gene (P = 0.0009), while expression of the MDR1 gene, encoding P-glycoprotein, was not related to expression of either the N-myc or MRP genes. Decreased expression of the N-myc oncogene in neuroblastoma cell lines SH-SY5Y and BE(2)-C, following treatment with retinoic acid, was paralleled by down-regulation of MRP gene expression, contrasting with increased expression of the MDR1 gene. Expression of the MRP gene is thus common in both primary neuroblastoma tumors and cultured cell lines, and correlates with amplification and overexpression of the N-myc oncogene, which is central to the malignant phenotype of this disease.

Atypical multidrug resistance in a therapy-induced drug-resistant human leukemia cell line (LALW-2): resistance to Vinca alkaloids independent of P-glycoprotein.

Near diploid leukemic T-cells (LALW-2), exposed to cytotoxic drugs only as a consequence of therapy administered to the donor patient, have been maintained by serial xenograft in nude mice. In comparison with the leukemic line CCRF-CEM, using a growth inhibition assay, LALW-2 cells were resistant to Vinca alkaloids and actinomycin D (relative resistance, 200-fold or more), were slightly resistant to Adriamycin (relative resistance, 4-fold), and showed no resistance to daunorubicin or teniposide. By comparison, a vincristine-resistant CEM subline developed in our laboratory (CEM/VCR R) was resistant to all these agents by at least 30-fold. The VCR R subline served as a positive control, confirming the previously reported correlation between multidrug resistance and amplification of the P-glycoprotein gene. Comparison of CEM, CEM/VCR R, and LALW-2 cells establish that the P-glycoprotein gene was not amplified or overexpressed in the LALW-2 cells; neither could the gene product be detected by immunoblotting in extracts from these cells. The LALW-2 cells were further distinguished from CEM/VCR R cells due to the lack of increased vincristine efflux by the xenografted cells, an effect readily demonstrable in the CEM/VCR R cells. However, although LALW-2 cells efflux vincristine at the same rate as CCRF-CEM cells, the xenografted cells exhibited a reduced rate of vincristine accumulation. Uptake of daunorubicin by LALW-2 cells was not distinguished from that by CEM cells, consistent with similar 50% inhibitory dose levels for this drug in both cell populations, and differentiating both from CEM/VCR R cells. Thus, clinical resistance in this case appears to be an "atypical" form of multidrug resistance specifically distinguished by resistance to Vinca alkaloids and actinomycin D occurring in the absence of increased amounts of P-glycoprotein and manifesting decreased drug uptake.

Multiple microtubule alterations are associated with Vinca alkaloid resistance in human leukemia cells.

Vinca alkaloids are used extensively in the treatment of childhood acute lymphoblastic leukemia (ALL) and despite their usefulness, drug resistance remains a serious clinical problem. Vinca alkaloids bind to the beta-tubulin subunit of the alpha/beta-tubulin heterodimer and inhibit polymerization of microtubules. Recent studies have implicated altered beta-tubulin isotype expression and mutations in resistance to microtubule-stabilizing agents. Microtubule-associated protein (MAP) MAP4 binds to and stabilizes microtubules, and increased expression is associated with decreased sensitivity to microtubule-depolymerizing agents. To address the significance of beta-tubulin and MAP4 alterations in childhood ALL, two CCRF-CEM-derived Vinca alkaloid resistant cell lines, VCR R (vincristine) and VLB100 (vinblastine), were examined. Decreased expression of class III beta-tubulin was detected in both VCR R and VLB100 cells. VCR R cells and to a lesser extent VLB100 cells expressed increased levels of MAP4 protein. Increased microtubule stability was observed in these VCR R cells as identified by the high levels of polymerized tubulin (45.6 +/- 2.6%; P < 0.005) compared with CEM and VLB100 cells (24.7 +/- 3.3% and 24.7 +/- 2.5%, respectively). Expression was associated with a single MAP4 isoform in the polymerized microtubule fraction in CEM and VCR cells. In contrast, VLB100 cells expressed a lower molecular weight isoform in the polymerized fraction. Two-dimensional-PAGE and immunoblotting revealed marked posttranslational changes in class I beta-tubulin in VCR R cells not evident in CEM cells. Sequencing of the beta-tubulin (HM40) gene identified a point mutation in VCR R cells in nucleotide 843 (CTC-->ATC; Leu(240)-->Ile) that was not present in CEM or VLB100 cells. This mutation resides in a region of beta-tubulin that lies in close proximity to the alpha/beta tubulin interface. Multiple alterations related to normal microtubule function were identified in ALL cells selected for resistance to Vinca alkaloids, and these alterations may provide important insight into mechanisms mediating resistance to Vinca alkaloids.

Expression of multiple endocrine neoplasia 2B RET in neuroblastoma cells alters cell adhesion in vitro, enhances metastatic behavior in vivo, and activates Jun kinase.

Point mutations, deletions, and recombinations of the RET proto-oncogene are associated with several inherited human diseases of neural crest-derived cells: Hirschsprung's disease, familial medullary thyroid carcinoma, and the multiple endocrine neoplasia (MEN) syndromes, types 2A and 2B. RET expression is restricted to normal and malignant cells of neural crest origin, such as human neuroblastoma cells. To better understand the role of the activated RET oncogene in neural crest cells, we transfected two adherent human neuroblastoma tumor cell lines with oncogenic MEN2 mutant RET cDNAs. Transfectant clones from both cell lines overexpressing MEN2B RET demonstrated a marked increase in the cell fraction growing in suspension. Both control and MEN2B cells formed tumors at the site of injection in all cases. However, mice injected with MEN2B cells developed lung metastases at a much higher frequency than control mice. Only RET protein derived from MEN2A transfectant cells had increased autokinase activity, whereas MEN2B transfectant cells demonstrated selective activation of the mitogen-activated protein kinase, Jun kinase-1 (Jnk1). These results indicate a biochemical signaling pathway that may link oncogenic RET with the metastatic process.

Agonistic 4-1BB antibody fails to reduce disease burden during acute respiratory syncytial virus (RSV) infection.

Respiratory Syncytial Virus (RSV) remains a leading cause of infant morbidity and mortality worldwide. Despite this, there are limited therapeutic options. CD8 T cells have an integral role in controlling viral infections; strategies to enhance these responses may be clinically relevant. The T cell costimulatory receptor, 4-1BB, is known to play a role in expansion of antiviral CD8 T cells. In this study, we examined the effect of agonistic 4-1BB antibody at the time of RSV infection in mice. We show that this antibody did not improve outcomes in the setting of RSV infection but rather, led to increased weight loss and a reduction in RSV specific CD8 T cells in the lung. This work suggests caution in the use of agonistic 4-1BB antibody in the setting of viral infections.

Favorable prognostic significance of high-level retinoic acid receptor beta expression in neuroblastoma mediated by effects on cell cycle regulation.

We have previously shown that ectopic overexpression of retinoic acid receptor (RAR) subtypes alpha, beta and gamma in human neuroblastoma cells had different effects on growth and retinoid sensitivity. Only overexpressed RAR beta induced profound growth inhibition in the absence of additional retinoid, and increased retinoid sensitivity. In this study, we measured mRNA expression levels of RAR alpha, beta, and gamma in 50 primary neuroblastoma tumor samples, and found a strong correlation between favorable patient prognosis and high-level RAR beta expression. Human neuroblastoma cells transfected with a vector expressing RAR beta demonstrated irreversible growth arrest following a 1 week exposure to all-transretinoic acid, whereas control cells continued to proliferate. In the absence of additional retinoid, RAR beta transfectants demonstrated a higher proportion of cells in the G0/G1 phase of the cell cycle, increased p21WAF1/CIP1 expression and specific binding to a retinoic acid response element. These were changes which we also observed in control neuroblastoma cells following retinoid treatment. Our data indicate that RAR beta is an important factor mediating the growth inhibitory effects of retinoids in neuroblastoma cells. The favorable effect of high-level RAR beta expression on prognosis in primary tumor tissue may occur through RAR beta effects on p21 expression and consequent G0/G1 cell cycle arrest.

Increased retinoic acid receptor gamma expression suppresses the malignant phenotype and alters the differentiation potential of human neuroblastoma cells.

Human neuroblastoma (NB) tumor cell lines treated in vitro with the retinoid, all-trans-retinoic acid (aRA), form neurites and undergo growth arrest. Retinoids exert their diverse morphologic effects through a signalling pathway which involves the nuclear retinoid receptors. Defective retinoic acid receptor (RAR) function contributes to the malignant phenotype of several human and experimental tumors. Considerable evidence from gene disruption studies now suggests that one of the RARs, RAR gamma, may directly mediate some retinoid effects on embryonic and malignant cells. We, firstly, examined primary NB tumor tissue for a correlation between endogenous RAR gamma expression and clinical stage of the tumor and secondly, the effects of exogenous over-expression of the RAR gamma gene on a human NB tumor cell line. RAR gamma mRNA expression in 32 primary NB tumor tissue samples were significantly higher in clinically localised tumors compared with advanced or disseminated tumors. The human NB tumor cell line, BE(2)-C, was stably transfected with a mammalian expression vector (pREP4) over-expressing the human RAR gamma cDNA. Two selected clones over-expressing RAR gamma (BE/G1 and 2) exhibited a reduced growth rate compared to control cells. Tumorigenicity was inhibited for BE/G1 cells and there was a delayed onset to tumor formation for BE/G2 cells. aRA caused growth inhibition but not neuritic differentiation of the BE/G clones, while 9-cis-retinoic acid caused both growth arrest and neuritic differentiation. Taken together these results suggest that reduced endogenous RAR gamma expression may contribute to the malignant phenotype of human NB. In NB cells the retinoid signalling pathway for neuritic differentiation may be distinct from that causing growth inhibition.