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R Roylance

Publications and source records attributed to R Roylance.

12 recordsLinked to original sources
PubMed2006

A comprehensive study of chromosome 16q in invasive ductal and lobular breast carcinoma using array CGH.

We analysed chromosome 16q in 106 breast cancers using tiling-path array-comparative genomic hybridization (aCGH). About 80% of ductal cancers (IDCs) and all lobular cancers (ILCs) lost at least part of 16q. Grade I (GI) IDCs and ILCs often lost the whole chromosome arm. Grade II (GII) and grade III (GIII) IDCs showed less frequent whole-arm loss, but often had complex changes, typically small regions of gain together with larger regions of loss. The boundaries of gains/losses tended to cluster, common sites being 54.5-55.5 Mb and 57.4-58.8 Mb. Overall, the peak frequency of loss (83% cancers) occurred at 61.9-62.9 Mb. We also found several 'minimal' regions of loss/gain. However, no mutations in candidate genes (TRADD, CDH5, CDH8 and CDH11) were detected. Cluster analysis based on copy number changes identified a large group of cancers that had lost most of 16q, and two smaller groups (one with few changes, one with a tendency to show copy number gain). Although all morphological types occurred in each cluster group, IDCs (especially GII/GIII) were relatively overrepresented in the smaller groups. Cluster groups were not independently associated with survival. Use of tiling-path aCGH prompted re-evaluation of the hypothetical pathways of breast carcinogenesis. ILCs have the simplest changes on 16q and probably diverge from the IDC lineage close to the stage of 16q loss. Higher-grade IDCs probably develop from low-grade lesions in most cases, but there remains evidence that some GII/GIII IDCs arise without a GI precursor.

Breast Neoplasms↗
PubMed2002

Methods of molecular analysis: assessing losses and gains in tumours.

The study of chromosomal aberrations has facilitated the understanding of tumorigenesis. By applying molecular genetic techniques to regions highlighted by cytogenetic study, many genes important in tumorigenesis have been identified. This review will describe the cytogenetic and molecular cytogenetic techniques used to identify these changes. The clinical information that they can provide, including diagnostic and prognostic information, will also briefly be discussed.

Chromosome Aberrations↗
PubMed2001

Multiple ways of silencing E-cadherin gene expression in lobular carcinoma of the breast.

The cell-cell adhesion receptor gene E-cadherin (CDH1) is expressed by epithelial cells, in which it mediates adhesion and morphogenesis. Invasive lobular carcinoma (ILC) characteristically infiltrates diffusely as single cells; by immunohistochemistry, many of these tumours lack E-cadherin expression. In the present study we investigated various ways in which loss of function of the E-cadherin gene could occur in ILCs, namely, promoter methylation, mutation and allelic loss. We analysed 22 ILCs and found 12 (55%) E-cadherin-negative samples by immunohistochemical analysis. Methylation-specific polymerase chain reaction (PCR) showed that 17/22 (77%) of these tumours had methylation of the CDH1 promoter, including 11/12 (91%) of the E-cadherin-negative tumours. All 16 exons of E-cadherin (including intron-exon boundaries) were amplified from chromosomal DNA and screened for mutations by conformation-sensitive gel electrophoresis (CSGE). Bands with altered mobility were analysed by direct sequencing. We identified five frameshift mutations, which resulted in downstream stop codons and one splice site mutation in six different tumours (29%). Loss of heterozygosity (LOH) was assessed using microsatellite markers, and 9/18 (50%) informative tumours showed LOH. We conclude that most ILCs show genetic or epigenetic changes affecting the E-cadherin gene and that many of these tumours lack E-cadherin expression. In all cases in which there was loss of expression, this was consistent with biallelic inactivation of CDH1 by promoter methylation, mutation or allelic loss in any combination.

Breast Neoplasms↗
PubMed2001

Two hits revisited again.

INTRODUCTION AND METHODS: Since the concept of the "two hit hypothesis" was introduced over 20 years ago, a wealth of genetic data has accumulated on the mutations found at tumour suppressor loci. Perhaps surprisingly, these data conceal large gaps in our knowledge which genetic and functional studies are beginning to uncover. The "two hit hypothesis" must be updated to take account of this new information. RESULTS AND DISCUSSION: Here, we discuss both the results of recent studies and some of the questions that they highlight. In particular, how valid are conclusions from inherited Mendelian syndromes when applied to sporadic cancers? Why is allelic loss so common and how does it occur? Are the "two hits" random or interdependent? Is abolition of protein function always optimal for tumorigenesis? Can "third hits" occur and, if so, why? How can mismatch repair deficiency and the methylator phenotype be incorporated into the "two hit" hypothesis? We suggest that the "two hit hypothesis" is not fixed but is evolving as our knowledge expands.

Humans↗
PubMed2000

Expression of the multidrug resistance gene in human prostate cancer.

Prostate cancer has become the most common cancer in males and the second most common cause of male cancer death in England and Wales. Death rates have doubled over the last 20 years. Prostate cancer is characterized by a high initial response rate to hormonal therapy. Drug-resistance is a significant cause of relapse in cancer. The multidrug resistance genes (MDR) encode resistance to a diverse family of cytotoxic chemotherapy agents. There are four known MDR genes, two of which are present in humans. MDR1 encodes for P-glycoprotein, a 170-kDa transmembrane calcium-dependent efflux pump. We examined P-glycoprotein expression by immunocytochemistry in 96 patients with prostate cancer and 20 patients with benign prostatic hypertrophy. A direct correlate was found between tumor grade, stage, and prostate specific antigen levels, indicating the possible significance of this protein in recurrent prostate cancer.

Journal Article↗
PubMed2000

Adjuvant mitozantrone chemotherapy in advanced prostate cancer.

OBJECTIVE: To assess the role of mitozantrone, active in relapsed prostate cancer, as an adjuvant to hormonal treatment in patients with advanced prostate cancer. PATIENTS AND METHODS: Between October 1990 and May 1995, 96 patients were entered into a stratified, randomized, single-institution study of hormonal therapy with a luteinizing hormone-releasing hormone agonist and flutamide, with or without four cycles of adjuvant mitozantrone. Of these, 93 patients were evaluable and the results were analysed in June 1999. RESULTS: Patients with localized prostate cancer receiving adjuvant chemotherapy had a higher initial objective response rate (95% vs 53%, P = 0.008) and median survival (80 vs 36 months, P = 0.04) than patients who were treated with hormonal therapy alone. There was no advantage to adjuvant chemotherapy in patients with metastatic prostate cancer. There were insignificant advantages to chemotherapy in overall response rates (55% vs 39%, P = 0.3) and PSA responses (82% vs 64%, P = 0.11). There was no difference between the patient groups in time to treatment failure. CONCLUSION: There was a survival advantage in using adjuvant mitozantrone in patients with locally advanced prostate cancer. Although the study comprised relative few patients, the follow-up period was long and the advantage significant. We recommend that the study be extended to include more patients.

Aged↗
PubMed1999

Comparative genomic hybridization of breast tumors stratified by histological grade reveals new insights into the biological progression of breast cancer.

How does breast cancer progress? There is evidence both to support (S. W. Duffy et al., Br. J. Cancer, 64: 1133-1138, 1991; R. Rajakariar et al., Br. J. Cancer, 71: 150-154, 1995) and refute (M. Hakama et al., Lancet, 345: 221-224, 1995; R. R. Millis et al., Eur. J. Cancer, 34: 548-553, 1998) the hypothesis of dedifferentiation; the theory that as breast cancers grow they evolve from well differentiated (grade I) to poorly differentiated (grade III) tumors. We provide evidence to support the view that the majority of grade I tumors do not progress to grade III tumors. Comparative genomic hybridization was used to screen entire genomes of a large sample (40 grade I and 50 grade III) of invasive ductal breast carcinomas, stratified by grade. We found distinct genetic differences between grade I and grade III tumors. Significantly, we found that 65% of grade I tumors lost the long arm of chromosome 16 compared with only 16% of grade III tumors. This pattern of loss leads us to conclude that the majority of grade I tumors do not progress to grade III tumors. These findings have important implications because they suggest that different breast tumor grades may have distinct molecular origins, pathogenesis, and behavior and, therefore, potentially present distinct molecular targets for research and treatment.

Breast Neoplasms↗
PubMed1999

The type of somatic mutation at APC in familial adenomatous polyposis is determined by the site of the germline mutation: a new facet to Knudson's 'two-hit' hypothesis.

APC is often cited as a prime example of a tumor suppressor gene. Truncating germline and somatic mutations (or, infrequently, allelic loss) occur in tumors in FAP (familial adenomatous polyposis). Most sporadic colorectal cancers also have two APC mutations. Clues from attenuated polyposis, missense germline variants with mild disease and the somatic mutation cluster region (codons 1,250-1,450) indicate, however, that APC mutations might not result in simple loss of protein function. We have found that FAP patients with germline APC mutations within a small region (codons 1,194-1,392 at most) mainly show allelic loss in their colorectal adenomas, in contrast to other FAP patients, whose 'second hits' tend to occur by truncating mutations in the mutation cluster region. Our results indicate that different APC mutations provide cells with different selective advantages, with mutations close to codon 1,300 providing the greatest advantage. Allelic loss is selected strongly in cells with one mutation near codon 1,300. A different germline-somatic APC mutation association exists in FAP desmoids. APC is not, therefore, a classical tumor suppressor. Our findings also indicate a new mechanism for disease severity: if a broader spectrum of mutations is selected in tumors, the somatic mutation rate is effectively higher and more tumors grow.

Adenoma↗
PubMed1997

The genetic analysis of prostate carcinoma.

The molecular events underlying prostatic tumorigenesis remain incompletely understood. The application of cytogenetic, molecular genetic and molecular cytogenetic techniques have led to the identification of consistent genetic changes. This paper will discuss these techniques, review the genetic aberrations discovered, and consider how these aberrations contribute to our knowledge of the initiation, progression, metastatic spread and resistance to hormonal therapy of prostate cancer.

Cytogenetics↗