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Biomedical subjects

A Ashworth

Publications and source records attributed to A Ashworth.

At least 19 recordsLinked to original sources
PubMed2007

Analysis by array CGH of genomic changes associated with the progression or relapse of Wilms' tumour.

Despite aggressive salvage regimens, approximately half of all children who suffer a Wilms' tumour recurrence will die of their disease. Although there are increasing data on molecular genetic prognostic factors present in the tumour at diagnosis, there is little information regarding the molecular events that occur with Wilms' tumour progression and relapse. In the present study, microarray-based comparative genomic hybridization (aCGH) analysis has been carried out on 58 Wilms' tumour samples, which included 38 untreated primary and 20 recurrent tumours. A higher degree of copy number changes was observed in the recurrent tumours (33.0% genomic clones) than in the primary tumour (21.2%). Paired analysis highlighted the acquisition of 15q gain with high levels of IGF1R expression in the tumour recurrence in two cases. The most statistically significant abnormality acquired between diagnosis and relapse was loss of 17p. One case that experienced 17p loss was classified as favourable histology at diagnosis, but exhibited diffuse anaplasia at recurrence and had a homozygous TP53 deletion. Another instructive case with a constitutional 11p13 deletion presented with bilateral tumours and suffered two subsequent recurrences in the left kidney. A somatic WT1 mutation was found only in the right kidney tumour, while the constitutional 11p13 deletion was the only abnormality detected in the initial left kidney tumour by aCGH. The two subsequent relapses in the left kidney contained an accumulation of additional genetic alterations, including an independent WT1 mutation.

Aniridia↗
PubMed2007

A mouse model of basal-like breast carcinoma with metaplastic elements.

Breast cancers arising in carriers of germline BRCA1 mutations frequently have a basal-like phenotype. Basal-like cancers are characterized by high histological grade, central necrotic areas, foci with metaplastic differentiation, lack of hormone receptor and HER2 (ErbB2) expression, and consistent positivity for basal markers, including CK5/6, CK14, and EGFR. We have used germline manipulation to generate a conditional mouse model of Brca1 deficiency. Transgenic expression of Cre recombinase in the mammary gland of these mice results in deletion of exons encoding the C-terminus of Brca1 and leads to tumour formation when combined with heterozygosity for a p53 mutation. Histologically, these mammary gland tumours were characterized by high histological grade, central necrotic areas, and presence of homologous metaplastic elements. These metaplastic elements consisted of neoplastic spindle cells or squamous cell differentiation in the form of keratin pearls or individual cell keratinization. Immunohistochemical analysis revealed expression of basal-like markers in all cases. The tumour phenotype generated in our mouse model was compared with published data on human basal-like breast carcinomas and also with metaplastic breast cancers with a basal-like phenotype; the comparison showed that we have generated a mouse model of basal-like breast cancer, which should prove useful in testing new and targeted treatments for this type of breast cancer.

Animals↗
PubMed2006

Microarray-based comparative genomic hybridisation of breast cancer patients receiving neoadjuvant chemotherapy.

We analysed the molecular genetic profiles of breast cancer samples before and after neoadjuvant chemotherapy with combination doxorubicin and cyclophosphamide (AC). DNA was obtained from microdissected frozen breast core biopsies from 44 patients before chemotherapy. Additional samples were obtained before the second course of chemotherapy (D21) and after the completion of the treatment (surgical specimens) in 17 and 21 patients, respectively. Microarray-based comparative genome hybridisation was performed using a platform containing approximately 5800 bacterial artificial chromosome clones (genome-wide resolution: 0.9 Mb). Analysis of the 44 pretreatment biopsies revealed that losses of 4p, 4q, 5q, 12q13.11-12q13.12, 17p11.2 and 17q11.2; and gains of 1p, 2p, 7q, 9p, 11q, 19p and 19q were significantly associated with oestrogen receptor negativity. 16q21-q22.1 losses were associated with lobular and 8q24 gains with ductal types. Losses of 5q33.3-q4 and 18p11.31 and gains of 6p25.1-p25.2 and Xp11.4 were associated with HER2 amplification. No correlations between DNA copy number changes and clinical response to AC were found. Microarray-based comparative genome hybridisation analysis of matched pretreatment and D21 biopsies failed to identify statistically significant differences, whereas a comparison between matched pretreatment and surgical samples revealed a statistically significant acquired copy number gain on 11p15.2-11p15.5. The modest chemotherapy-driven genomic changes, despite profound loss of cell numbers, suggest that there is little therapeutic selection of resistant non-modal cell lineages.

Adult↗
PubMed2006

BRCA1 dysfunction in sporadic basal-like breast cancer.

Basal-like breast cancers form a distinct subtype of breast cancer characterized by the expression of markers expressed in normal basal/myoepithelial cells. Breast cancers arising in carriers of germline BRCA1 mutations are predominately of basal-like type, suggesting that BRCA1 dysfunction may play a role in the pathogenesis of sporadic basal-like cancers. We analysed 37 sporadic breast cancers expressing the basal marker cytokeratin 5/6, and age- and grade-matched controls, for downregulation of BRCA1. Although BRCA1 promoter methylation was no more common in basal-like cancers (basal 14% vs controls 11%, P=0.72), BRCA1 messenger RNA expression was twofold lower in basal-like breast cancers compared to matched controls (P=0.008). ID4, a negative regulator of BRCA1, was expressed at 9.1-fold higher levels in basal-like breast cancer (P<0.0001), suggesting a potential mechanism of BRCA1 downregulation. BRCA1 downregulation correlated with the presence of multiple basal markers, revealing heterogeneity in the basal-like phenotype. Finally, we found that 63% of metaplastic breast cancers, a rare type of basal-like cancers, had BRCA1 methylation, in comparison to 12% of controls (P<0.0001). The high prevalence of BRCA1 dysfunction identified in this study could be exploited in the development of novel approaches to targeted treatment of basal-like breast cancer.

BRCA1 Protein↗
PubMed2006

The roles of BRCA1 and BRCA2 and associated proteins in the maintenance of genomic stability.

The BRCA1 and BRCA2 proteins are important in maintaining genomic stability by promoting efficient and precise repair of double-strand breaks. The main role of BRCA2 appears to involve regulating the function of RAD51 in the repair by homologous recombination. BRCA1 has a broader role upstream of BRCA2, participating in various cellular processes in response to DNA damage. The DNA repair defect associated with mutations in BRCA1 or BRCA2 could be exploited to develop new targeted therapeutic approaches for cancer occurring in mutation carriers.

BRCA1 Protein↗
PubMed2006

Basal-like breast carcinomas: clinical outcome and response to chemotherapy.

BACKGROUND: Grade-III invasive ductal carcinomas of no special type (IDCs-NST) constitute a heterogeneous group of tumours with different clinical behaviour and response to chemotherapy. As many as 25% of all grade-III IDCs-NST are known to harbour a basal-like phenotype, as defined by gene expression profiling or immunohistochemistry for basal cytokeratins. Patients with basal-like breast carcinomas (BLBC) are reported to have a shorter disease-free and overall survival. MATERIAL AND METHODS: A retrospective analysis of 49 patients with BLBC (as defined by basal cytokeratin expression) and 49 controls matched for age, nodal status and grade was carried out. Histological features, immunohistochemical findings for oestrogen receptor (ER), progesterone receptor (PgR) and HER2, and clinical outcome and survival after adjuvant chemotherapy were compared between the two groups. RESULTS: It was more likely for patients with BLBCs to be found negative for ER (p<0.0001), PgR (p<0.0001) and HER2 (p<0.01) than controls. Patients with BLBCs were found to have a significantly higher recurrence rate (p<0.05) and were associated with significantly shorter disease-free and overall survival (both p<0.05). In the group of patients who received anthracycline-based adjuvant chemotherapy (BLBC group, n = 47; controls, n = 49), both disease-free and overall survival were found to be significantly shorter in the BLBC group (p<0.05). CONCLUSIONS: BLBCs are a distinct clinical and pathological entity, characterised by high nuclear grade, lack of hormone receptors and HER2 expression and a more aggressive clinical course. Standard adjuvant chemotherapy seems to be less effective in these tumours and new therapeutic approaches are indicated.

Adult↗
PubMed2006

EGFR amplification and lack of activating mutations in metaplastic breast carcinomas.

Metaplastic breast carcinomas are reported to harbour epidermal growth factor receptor (EGFR) overexpression in up to 80% of the cases, but EGFR gene amplification is the underlying genetic mechanism in around one-third of these. In this study, EGFR gene amplification as defined by chromogenic in situ hybridization and protein overexpression was examined in a cohort of 47 metaplastic breast carcinomas. Furthermore, the presence of activating EGFR mutations in exons 18, 19, 20, and 21 was investigated. Thirty-two cases showed EGFR overexpression and of these, 11 (34%) harboured EGFR gene amplification. In addition, EGFR amplification showed a statistically significant association with EGFR overexpression (p < 0.0094) and was restricted to carcinomas with homologous metaplasia. Ten cases, five with and five without EGFR amplification, were subjected to microarray-based CGH, which demonstrated that EGFR copy number gain may occur by amplification of a discrete genomic region or by gains of the short arm of chromosome 7 with a breakpoint near the EGFR gene locus, the minimal region of amplification mapping to EGFR, LANCL2, and SEC61G. No activating EGFR mutations were identified, suggesting that this is unlikely to be a common alternative underlying genetic mechanism for EGFR expression in metaplastic breast carcinomas. Given that metaplastic breast carcinomas are resistant to conventional chemotherapy or hormone therapy regimens and that tumours with EGFR amplification are reported to be sensitive to EGFR tyrosine kinase inhibitors, these findings indicate that further studies are warranted to explore EGFR tyrosine kinase inhibitors as potential therapeutic agents for metaplastic breast carcinomas harbouring amplification of 7p11.2.

Breast Neoplasms↗
PubMed2006

Array CGH profiling of favourable histology Wilms tumours reveals novel gains and losses associated with relapse.

Despite the excellent survival of Wilms tumour patients treated with multimodality therapy, approximately 15% will suffer from tumour relapse, where response rates are markedly reduced. We have carried out microarray-based comparative genomic hybridisation on a series of 76 Wilms tumour samples, enriched for cases which recurred, to identify changes in DNA copy number associated with clinical outcome. Using 1Mb-spaced genome-wide BAC arrays, the most significantly different genomic changes between favourable histology tumours that did (n = 37), and did not (n = 39), subsequently relapse were gains on 1q, and novel deletions at 12q24 and 18q21. Further relapse-associated loci included losses at 1q32.1, 2q36.3-2q37.1, and gain at 13q31. 1q gains correlated strongly with loss of 1p and/or 16q. In 3 of 11 cases with concurrent 1p(-)/1q(+), a breakpoint was identified at 1p13. Multiple low-level sub-megabase gains along the length of 1q were identified using chromosome 1 tiling-path arrays. One such recurrent region at 1q22-q23.1 included candidate genes RAB25, NES, CRABP2, HDGF and NTRK1, which were screened for mRNA expression using quantitative RT-PCR. These data provide a high-resolution catalogue of genomic copy number changes in relapsing favourable histology Wilms tumours.

Chromosome Aberrations↗
PubMed2006

Improving child survival: Malnutrition Task Force and the paediatrician's responsibility.

Malnutrition (underweight) contributes to approximately 60% of all child deaths, yet health professionals, policy makers, and donor agencies often fail to recognise its relevance to child survival. There is a need for the paediatric community to champion the importance of adequate nutrition for normal growth and development, and of placing sufficient emphasis on the prevention and treatment of malnutrition. Many severely malnourished children die from inappropriate treatment. Case fatality rates of 25-30% are commonly found and in some hospitals as many as 50-70% will die. Many of these deaths are avoidable. Weaknesses in health systems, inappropriate training of doctors and nurses, inadequate supervision, and lack of support for staff all contribute to compromised quality of care. The International Union of Nutritional Sciences, with support from the International Pediatric Association, Launched a global Malnutrition Task Force in 2005. The main objective is to ensure that an integrated system of prevention and treatment of malnutrition is actively supported as a fundamental aspect of care, and becomes an integral part of all training programmes.

Case Management↗
PubMed2006

Training nurses to save lives of malnourished children.

A qualitative study with a pre- and post-intervention component was undertaken among 66 professional nurses at 11 hospitals in the Eastern Cape to assess their perceptions and attitudes towards severely malnourished children and their mothers/caregivers. Nurses' attitudes were compared before and after attending a 5-day training course to improve the management of malnutrition along with implementing World Health Organization (WHO) guidelines. Severe malnutrition is a major cause of death among paediatric patients in many hospitals in South Africa. A qualitative study with a pre- and post-intervention component was undertaken among 66 professional nurses at 11 hospitals in the Eastern Cape to assess their perceptions and attitudes towards severely malnourished children and their mothers/caregivers. Nurses' attitudes were compared before and after attending a 5-day training course to improve the management of severe malnutrition through implementing the World Health Organisation (WHO) guidelines. Focus group discussions were conducted in isiXhosa following a semi-structured discussion guide. Three themes emerged from these discussions, i.e. nurses placed blame on the mothers for not giving adequate care at home; nurses valued malnourished children less than those with other conditions; and nurses felt resentment towards caregivers. Underlying reasons for the negative attitudes towards severely malnourished children and their caregivers were misunderstandings of the causes of malnutrition, misinterpretation of clinical signs, especially poor appetite, and high mortality during treatment. However, the training course and successful application of the treatment guidelines altered these perceptions and helped nurses to have a better understanding of the causes of the presenting clinical signs. These nurses have begun advocating for raised awareness of the physiological differences that occur in malnutrition and the need to include the WHO Ten Steps of treatment in the nursing curricula and inservice training. A cadre of volunteer nurse-trainers has been formed in Eastern Cape. Experience in this province has shown that in-service training changes attitudes to malnutrition and treatment practices, as well as saving lives.

Anger↗
PubMed2005

Genome-wide screening for genetic changes in a matched pair of benign and prostate cancer cell lines using array CGH.

Copy number alterations in a matched pair of benign epithelial and prostate cancer cell lines derived from the same patient were assessed using array-based comparative genomic hybridisation (aCGH). The cancer cell line showed a gain of chromosome 7, deletion of chromosome 8, gains (including high level) and losses on chromosome 11, loss of 18p and gain of 20q. Deletions on chromosome 8 were confirmed with microsatellite markers. The aCGH results were compared to gene expression data obtained using DNA microarrays and suggested the involvement of caspases and ICEBERG on 11q and E2F1 on chromosome 20q.

Cell Line, Tumor↗
PubMed2005

An improved definition of mouse mammary epithelial side population cells.

BACKGROUND: Mammary epithelial side population cells have been suggested as candidate mammary stem cells. To date, for technical reasons, these cells have been poorly defined and cross-comparison of data between different laboratories has been difficult. Here, we set out to define mammary side population cells in a way that improves the ability to carry out such comparisons. METHODS: Mouse mammary epithelial cells were stained with Hoechst 33342. Light scatter, PI staining and clonogenicity of different regions of the Hoechst profile were examined. Time-course analyzes of Hoechst 33342 loading were carried out. RESULTS: Detailed examination of the light scatter and PI staining of Hoechst 33342-stained mammary cells enabled single live side population and non-side population cells to be defined with greater accuracy. Comparison of ABC pump inhibitors identified potential discrepancies in results obtained using these inhibitors. Time-course analyzes enabled side populations cells to be identified as a dynamic cell population that could be defined accurately by using the relationship between Hoechst 33342-staining profiles of consecutive time points. DISCUSSION: Defining the side population of solid tissues as a 'stabilized side population percentage' will enable a more rigorous study of the side population phenomenon and improve evaluation of results from different laboratories.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

Exploiting the DNA repair defect in BRCA mutant cells in the design of new therapeutic strategies for cancer.

Individuals harboring germ-line mutations in the BRCA1 or BRCA2 genes are at highly elevated risk of a variety of cancers. Ten years of research has revealed roles for BRCA1 and BRCA2 in a wide variety of cellular processes. However, it seems likely that the function of these proteins in DNA repair is critically important in maintaining genome stability. Despite this increasing knowledge of the defects present in BRCA-deficient cells, BRCA mutation carriers developing cancer are still treated similarly to sporadic cases. Here we describe our efforts, based on understanding the DNA repair defects in BRCAdeficient cells, to define the optimal existing treatment for cancers arising in BRCA mutation carriers and, additionally, the development of novel therapeutic approaches. Finally, we discuss how therapies developed to treat BRCA mutant tumors might be applied to some sporadic cancers sharing similar specific defects in DNA repair.

Animals↗
PubMed2004

Molecular profiling of breast cancer: clinical implications.

Breast cancers are routinely subcategorised on the basis of clinical stage, cellular morphology and immunohistochemical analysis of a small number of markers. The recent development of gene expression microarray and related technologies provides an opportunity to perform more detailed profiling of the disease. It is anticipated that the molecular classification arising from such studies will be more powerful than its pathological predecessor at confining treatment to those patients who are most likely to benefit. It is likely that this will result in a much less frequent use of adjuvant chemotherapy. Furthermore, of those who do receive it, a higher proportion will benefit. If adopted, this will offer considerable patient benefits in terms of reducing unnecessary toxicity and have major health economic implications.

Breast Neoplasms↗
PubMed2004

Determinants of mental and motor development at 12 months in a low income population: a cohort study in northeast Brazil.

AIM: To identify biological and environmental factors associated with poorer mental and motor development at age 12 mo in urban communities in northeast Brazil. METHODS: A cohort of 245 infants born during January August 1998 in six hospitals in the interior of Pernambuco was followed twice weekly from birth until 12 mo of age. Socio-economic, demographic and environmental data were collected, together with daily information on morbidity and feeding patterns. Gestational age, birth anthropometry and nutritional status at 12 mo were measured. Multiple linear regression analysis was used to identify variables that had independent effects on mental and motor development assessed at 12 mo of age with the Bayley Scales of Infant Development. RESULTS: Environmental factors explained about 21% and 19% of the variance in mental and motor development, respectively. Of these, the most important were poverty-related. Significant biological factors associated with mental development were birthweight and infant sex. For motor development, the biological factors were weight-for-age and haemoglobin concentration. Biological factors explained only 6% and 5% of the variance in mental and motor development, respectively. CONCLUSION: Of the variables examined, environmental factors had a greater detrimental effect on child development than biological factors in this population. Interventions that enhance social capital and alleviate poverty are advocated.

Brazil↗
PubMed2002

BRCA1 and BRCA2 bind Stat5a and suppress its transcriptional activity.

Germline mutations in the breast cancer susceptibility genes, BRCA1 and BRCA2, are thought to account for a large portion of familial breast cancer. The increased risk of breast cancer in women carrying such mutations suggests that these proteins play a critical role in the growth regulation of mammary epithelial cells. Another protein, Stat5a, is known to be essential for growth and terminal differentiation of breast epithelial cells. Here we show that Stat5a forms a complex with both BRCA1 and BRCA2 in breast epithelial cells upon stimulation with prolactin. In addition, we show that the activity of Stat5a on the beta-casein promoter is modulated by both BRCA1 and BRCA2. This interaction may be important during the expansion and terminal differentiation of breast epithelial cells, as happens during pregnancy and lactation.

Animals↗
PubMed2001

LIP1, a cytoplasmic protein functionally linked to the Peutz-Jeghers syndrome kinase LKB1.

LKB1 is a serine/threonine kinase which is inactivated by mutation in the Peutz-Jeghers polyposis and cancer predisposition syndrome (PJS). We have identified a novel leucine-rich repeat containing protein, LIP1, that interacts with LKB1. The LIP1 gene consists of 25 exons, maps to human chromosome 2q36 and encodes a protein of 121 kDa. LIP1 appears to be a cytoplasmically located protein whereas we and others have shown previously that LKB1 is predominantly nuclear, with only a small proportion of cells showing strong cytoplasmic expression. However, when LKB1 and LIP1 are co-expressed, the proportion of cytoplasmic LKB1 dramatically increases, suggesting that LIP1 may regulate LKB1 function by controlling its subcellular localization. Ectopic expression of both LKB1 and LIP1 in Xenopus embryos induces a secondary body axis, providing further evidence for a functional link between the two proteins. This phenotype resembles the effects of ectopic expression of TGFbeta superfamily members and their downstream effectors. A possible role for LIP1 and LKB1 in TGFbeta signalling is supported by the observation that LIP1 interacts with the TGFbeta-regulated transcription factor SMAD4, forming a LKB1-LIP1-SMAD4 ternary complex. SMAD4 mutations give rise to juvenile polyposis syndrome, which is clinically similar to PJS. Our data suggest an unsuspected mechanistic link between these two syndromes.

AMP-Activated Protein Kinase Kinases↗