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Results for “Cancer genetics”

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At least 271 records · Page 15Linked to original sources
PubMed1996

Human breast cancer: genetic alterations in the MET gene region.

OBJECTIVE: to test whether the MET gene at chromosome 7q31, which encodes a receptor protein (tyrosine kinase) related to normal histological differentiation, undergoes structural changes in breast cancer. A previous study reported somatic alterations detected as loss of heterozygosity (LOH) at this locus in breast cancer. DESIGN: Analysis of DNA from tumours and matched normal tissue by Southern blot hybridization with the metH probe; the tumours were also analysed for estrogen and progesterone receptors, ploidy and S phase, and protein expression of the MET and c-erbB-2 protooncogenes. PARTICIPANTS: Eighty-two patients with breast cancer. RESULTS: Fifty-three percent of the patients were informative for polymorphism with the metH marker. Somatic alterations of MET, consisting of LOH, were demonstrated in 22% of women who were informative and had breast cancer. No correlation was found between LOH of MET and conventional prognostic factors, or status for c-erbB-2 proto-oncogene expression. Estrogen-receptor status correlated with progesterone-receptor status, and S phase correlated with ploidy and size of the tumour. CONCLUSIONS: Somatic alterations of MET, detected as LOH with the metH probe, occur in 22% of informative patients. These alterations do not correlate with the prognostic factors established when the mastectomy is performed. It remains to be determined whether the patients' overall survival and disease-free survival rates are correlated with genetic alteration of MET.

Breast Neoplasms↗
PubMed2006

Analysis of referrals to a multi-disciplinary breast cancer genetics clinic: practical and economic considerations.

Analysis of activity was undertaken in an established regional clinic providing risk assessment, counselling, screening and management for women with a family history of breast or ovarian cancer. The objectives were to determine: (1) how closely the route and pattern of referrals matched official guidelines (2) whether the previously recorded socio-economic imbalance among clinic clientele persisted and (3) the economic and practical consequences of committing resources to verification and extension of reported family histories. The findings were: (1) after some years of operation, the proportion of referrals direct from primary care had increased from less than 50% to over 75%, with a concomitant slight decrease in overall referral rate; (2) the socio-economic distribution of patients referred had become less selective and (3) extension and verification of reported family histories led to a redistribution of risk categories, increasing the proportion of referrals judged to be in the "low risk" category, from 25% (based on referral letter alone) to 41% (at the end of the process). The costs associated with this approach are offset by the savings generated and it allows specialised counselling and screening services to be targeted more efficiently.

Breast Neoplasms↗
PubMed1999

Genetic cancer susceptibility and DNA adducts: studies in smokers, tobacco chewers, and coke oven workers.

Preventive strategies require identification of cancer-susceptible individuals resulting from combinations of carcinogen exposure, cancer-predisposing genes, and lack of protective factors. To this aim, related to tobacco smoking and chewing (betel quid), we measured PAH-DNA adducts as exposure and susceptibility markers together with genetic polymorphism in drug-metabolizing enzymes related to CYP1A1, GSTM1, and GSTT1 genes in case-control studies. (+)-anti-Benzo(a)pyrene diol-epoxide (BPDE)-DNA adduct levels were quantitated in white blood cells (WBCs) and lung tissue DNA. CYP1A1 polymorphism and GSTM1 or GSTT1 gene deletion was analyzed in genomic DNA from lung parenchyma, WBCs, or oral biopsies (leukoplakia patients from India) and from oral exfoliated cells (healthy controls). Results from lung cancer patients and PAH-exposed coke oven workers correlated CYP1A1-GSTM1 genotype combinations with BPDE-DNA adduct levels. Smokers with homozygous CYP1A1 variant and GSTM1 null had the highest adduct levels and were, as shown in Japanese smokers, most susceptible to lung cancer. In oral premalignant leukoplakia cases associated with betel quid/tobacco chewing, the prevalence of the GSTM1 null and GSTT1 null genotypes was significantly higher, as compared to healthy controls. The combined GST null genotypes prevailed in 60% of the cases with none detected in controls. Based on this short review we conclude that (i) BPDE-DNA adduct levels resulting from "at risk" genotype combinations may serve as markers to identify most susceptible individuals; (ii) in Indian betel quid/tobacco chewers, the null genotypes of GSTM1 and GSTT1 greatly increased the risk for developing oral leukoplakia.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2006

Epstein-Barr virus (EBV) and its associated human cancers--genetics, epigenetics, pathobiology and novel therapeutics.

Epstein-Barr virus (EBV) is a B-lymphotropic virus that is associated with a range of human malignancies. Although for many of these tumors the association has long been established, unraveling the precise role of EBV in disease pathogenesis has been more difficult. This review summarizes current knowledge concerning the association between EBV and human cancers, and illustrates how a deeper insight into viral latent gene expression, regulation and functions in different cell environments is already helping towards a better understanding of both the natural history of infection in normal individuals and how EBV contributes to malignant transformation. Finally, therapeutic strategies targeting EBV in tumors are discussed.

DNA Methylation↗
PubMed2005

Caveolin-1 promotes tumor progression in an autochthonous mouse model of prostate cancer: genetic ablation of Cav-1 delays advanced prostate tumor development in tramp mice.

Caveolin-1 (Cav-1) is the primary structural component of caveolae and is implicated in the processes of vesicular transport, cholesterol balance, transformation, and tumorigenesis. Despite an abundance of data suggesting that Cav-1 has transformation suppressor properties both in vitro and in vivo, Cav-1 is expressed at increased levels in human prostate cancer. To investigate the role of Cav-1 in prostate cancer onset and progression, we interbred Cav-1(-/-) null mice with a TRAMP (transgenic adenocarcinoma of mouse prostate) model that spontaneously develops advanced prostate cancer and metastatic disease. We found that, although the loss of Cav-1 did not affect the appearance of minimally invasive prostate cancer, its absence significantly impeded progression to highly invasive and metastatic disease. Inactivation of one (+/-) or both (-/-) alleles of Cav-1 resulted in significant reductions in prostate tumor burden, as well as decreases in regional lymph node metastases. Moreover, further examination revealed decreased metastasis to distant organs, such as the lungs, in TRAMP/Cav-1(-/-) mice. Utilizing prostate carcinoma cell lines (C1, C2, and C3) derived from TRAMP tumors, we also showed a positive correlation between Cav-1 expression and the ability of these cells to form tumors in vivo. Furthermore, down-regulation of Cav-1 expression in these cells, using a small interfering RNA approach, significantly reduced their tumorigenic and metastatic potential. Mechanistically, we showed that loss or down-regulation of Cav-1 expression results in increased apoptosis, with increased prostate apoptosis response factor-4 and PTEN levels in Cav-1(-/-) null prostate tumors. Our current findings provide the first in vivo molecular genetic evidence that Cav-1 does indeed function as a tumor promoter during prostate carcinogenesis, rather than as a tumor suppressor.

Animals↗
PubMed1999

Renal cancer genetics: von Hippel Lindau and other syndromes.

There have been significant advances in our understanding of the genetic basis of renal carcinogenesis. In particular, research in the last five years has demonstrated a central role for the inactivation of the von Hippel-Lindau gene by mutation or hypermethylation in the formation of the conventional type of renal cell carcinoma. The von Hippel-Lindau syndrome is characterised by germ-line inactivating mutation whereas sporadic renal carcinoma is associated with somatic mutations. Tumour formation is accompanied by loss of the remaining wild-type allele. The biology of the von Hippel-Lindau gene and its normal function continued to be unravelled but a role has been demonstrated for it in the regulation of gene transcription, the regulation of oxygen-dependent genes and their expression and the control of tumour angiogenesis acting via the vascular endothelial growth factor. Another form of familial renal cancer, the hereditary papillary renal cell carcinoma, has been shown to be consequent upon activating mutations of the c-met proto-oncogene. The genetic data continue to enhance our understanding of the biology of this common set of neoplasms.

Carcinoma, Renal Cell↗
PubMed2001

[Human papillomavirus and cervical cancer: genetic background of the neoplastic process].

In a 2-year period, 136 HPV positive cytological samples of the cervix uteri were analyzed at the Department of Molecular Pathology, National Institute of Oncology, Hungary. Comparison with the international data obtained from the literature revealed that the Hungarian epidemiological data bore closest resemblance to the European ones except some differences. The HPV18 is rather seldom encountered in this country. Similarly low occurrence was noted only in Japan. However, the 14.1% occurrence rate of HPV58 in Hungary is by far higher than that in any other country in this analysis except Japan where this virus is of similarly high frequency. In Hungary, the incidence of HPV59 is relatively high just like in Central and South America. HPV33 and HPV66 infections occur in a significantly higher number with Hungary than in any of the countries studied. In our study The European type variant of HPV16 (E-V-350G) occurred in 2/10 CIN II-III cases. The authors also compared the various clinico-pathological grouping of HPV types published, and identified several inconsistencies. Viruses considered to have high risk occurred in intact epithelium, CIN I-II-III and carcinoma alike. The general tendency was, however, that certain viruses correlated with specific clinico-pathological entities. At present there is no reason to include the PCR-based HPV typing in the mass screening of cervical cancers. HPV typing and physical state of the virus can reasonable be determined if the cervical cytology is suspect for HPV infection or even control examination after "loop" conisation. Negative cytology completed with negative HPV-DNA test means the lack of cancer risk even in the case of a previously removed CIN or carcinoma. However, a positive HPV test detected after conisation associated with negative cytology finding indicates a risk of 70% of the development of CIN within 2 years.

Carcinoma↗
PubMed1995

DNA index and %S-phase cells determined in acute lymphoblastic leukemia of children: a report from studies ALL V, ALL VI, and ALL VII (1979-1991) of the Dutch Childhood Leukemia Study Group and The Netherlands Workgroup on Cancer Genetics and Cytogenetics.

DNA per cell content was routinely recorded by single-parameter flow cytometry in leukemic blasts from 473 children with acute lymphoblastic leukemia (ALL), enrolled in national studies ALL V, VI, and VII (1979-1991) of the Dutch Childhood Leukemia Study Group. The parameters bonemarrow %S-value and DNA Index were compared with clinical features, with chromosome number based on cytogenetic analyses and with treatment results in study ALL VI. %S-values, ranging between 1 and 36%, were unrelated to initial white blood cell count, immunophenotype, and DNA index but were lowest in blasts with L1 morphology. In study ALL VI (non-high risk), the survival of patients with < or = 6% S-phase cells was superior to that of patients with %S-values of > 6 (P = 0.030). Hyperdiploidy, defined by a DNA index > or = 1.16, was compared to the cytogenetic hyperdiploid classification of n > 50. Initially there were 25 discrepancies in 189 samples jointly analysed by flow cytometry and cytogenetics. After review only five discrepancies remained unresolved. Hyperdiploidy, independent of the method used, was found to be unrelated to blast morphology and %S-phase cells but closely associated with c-ALL and was absent in T-ALL. In study ALL VI, event-free survival at 8 years of hyperdiploid patients was 90.6% but was not significantly different from non-hyperdiploid patients (EFS = 82.1%; P = 0.08). Routine DNA flow cytometry appeared a valuable adjunct to cytogenetic analyses and allowed the identification of a large subset of non-high-risk ALL patients in study ALL VI with a DNA index > or = 1.16 or %S-value of < or = 6.0 with highest survival probability.

Bone Marrow↗
PubMed1991

Breast cancer genetic evolution: I. Data from cytogenetics and DNA content.

A general scheme of chromosome alterations occurring during tumor progression is proposed from the cytogenetic study of 113 breast carcinomas. For 76 of these tumors, chromosome numbers and rate of chromosome rearrangements were correlated with DNA content studied by flow cytometry. A series of 536 cases was used as control for flow cytometry. The following evolution can be proposed: 1. occurrence of unbalanced rearrangements decreasing chromosome number and DNA content; 2. correlatively to the rate of chromosome rearrangements, formation of endoreduplications leading to hyperploid sidelines; 3. persistence of the near diploid cells and decrease of chromosome number to about 35 and of DNA index to .85; 4. more frequently, elimination of the near diploid cells and complete passage to hyperploidy; 5. further losses of chromosomes in the hyperploid tumors, whose karyotypes can decrease to about 55 chromosomes and a DNA index of 1.35; 6. eventually, occurrence of a second endoreduplication, leading to an apparent near tetraploidy. The rate of rearranged chromosomes may reach 80% in both near diploid tumors with 35-40 and hyperploid tumors with 55-65 chromosomes which can be regarded as those with the highest degree of tumor progression. It is shown that the increase of chromosome number and DNA index above diploidy is very limited, and that all tumors with more than 50 chromosomes and 1.35 DNA content passed through endoreduplication. This results in many possible losses of heterozygosity in these cases.

Adenocarcinoma↗