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Biomedical subjects

J S Kovach

Publications and source records attributed to J S Kovach.

At least 19 recordsLinked to original sources
PubMed2001

Low frequency of p53 gene mutations in breast cancers of Japanese-American women.

Differences in frequencies and patterns of somatic p53 gene mutations among racially and geographically diverse populations presumably reflect exposure to different mutagens or different responses to certain mutagens. On emigration to the United States, Japanese women experience, over several generations, a four- to fivefold increase in the incidence of breast cancer. To determine whether this increased incidence is associated with a change in the frequency and/or type of p53 mutation in their tumors, we examined paraffin-embedded samples of primary breast cancers from Japanese-American women in Los Angeles County, CA. Mutations in exons 5-9 and adjacent intronic regions of the p53 gene were identified and confirmed by direct sequencing. Seven mutations, including 5 missense, were detected in 44 primary breast carcinomas, a frequency of 16%. There were six transitions and one transversion. As expected, overexpression of p53 protein, detected by immunohistochemistry, occurred in tumors with missense mutations; tumors with nonsense or splice junction mutations had no detectable p53 protein. The frequency of p53 gene mutations showed no increase over that previously found in breast cancers of native Japanese women. The increased incidence of breast cancer in Japanese-American women is likely to be multifactorial in nature and warrants further studies.

Adult↗
PubMed2000

A prospective trial of midwest breast cancer patients: a p53 gene mutation is the most important predictor of adverse outcome.

Several retrospective studies have suggested p53 gene mutation as an adverse prognostic indicator in breast cancer patients, based on a selective growth advantage of p53 mutant cancer cells and their presumed resistance to current adjuvant therapy regimens. A cohort of 90 Caucasian midwestern breast cancer patients was analyzed prospectively (60 months of follow-up) with a rigorous mutation detection methodology. The presence of a p53 gene mutation was the single most adverse prognostic indicator for recurrence (p = 0.0032) and death (p = 0.0001), and was associated with poor response to both adjuvant (p = 0.0001) and palliative (p = 0.006) therapy. Analysis of the p53 gene with appropriate mutation detection methodology markedly improves the prediction of early recurrence, treatment failure, and death in breast cancer patients.

Breast Neoplasms↗
PubMed1998

Clinical and pharmacokinetic studies of high-dose levamisole in combination with 5-fluorouracil in patients with advanced cancer.

PURPOSE: To determine the maximum tolerable dose (MTD) and activity of levamisole administered concurrently with 5-fluorouracil (5-FU) in a standard 5-day course. To determine the pharmacokinetics of levamisole during the course of treatment. PATIENTS AND METHODS: Levamisole was administered to 38 patients orally three times a day for 5 days concurrently with a course of 5-FU administered daily by rapid intravenous injection for 5 days. Toxicity was evaluated in 20 patients who received escalating doses of levamisole. The activity of the combination was evaluated in 18 patients who received levamisole at the MTD with 5-FU. The pharmacokinetics of levamisole were characterized in ten patients at the MTD level. RESULTS: Intractable vomiting, confusion and vertigo were the major dose-limiting toxicities. The MTD of oral levamisole was 100 mg/m2 administered three times a day concurrently with 450 mg/m2 per day intravenous 5-FU for 5 consecutive days. Partial responses lasting 5 and 11 months were observed in 2/18 patients with measurable disease at the MTD. Peak plasma concentrations of 1 microg/ml (range 0.6-1.3 microg/ml) were achieved 90 min (range 60-360 min) after an oral dose of 100 mg/m2 levamisole with a 3.5-fold accumulation noted following 4 days of administration. Peak plasma concentrations of p-hydroxylevamisole were about 5% of parent drug. Little parent drug (2-5%) was detected in urine. CONCLUSIONS: Levamisole may be administered safely with 5-FU at doses which are up to four to five times greater than those presently given in conventional regimens. The recommended dose of levamisole combined with 5-FU for future research protocols is 75 mg/m2 t.i.d for 5 days.

Adult↗
PubMed1997

The molecular epidemiology of p53 gene mutations in human breast cancer.

The P53 tumor-suppressor gene is an advantageous tool for analyzing the molecular epidemiology of cancer. We describe the utility of the P53 gene as a 'mutagen test' and a prognostic indicator in breast cancer. Aspects of study design and methodology are discussed. Two major conclusions emerge: (1) there is an extraordinary diversity of mutational patterns among cohorts, hinting that the unique biology of mammary cells results in exposure to high doses of a diversity of ingested lipophilic mutagens; and (2) mutations in the P53 gene predict poor outcome in breast cancer.

Breast Neoplasms↗
PubMed1997

Distribution of endogenous tumour necrosis factor alpha in gliomas.

AIMS: To determine the distribution and cellular origin of endogenous tumour necrosis factor alpha (TNF alpha) in the cellular components of human gliomas. METHODS: Frozen sections of 26 gliomas (four astrocytomas (As); two oligoastrocytomas (OA); one ansplastic astrocytoma (AA); one anaplastic oligoastrocytoma (AOA); 18 glioblastomas (GB)) were examined immunohistochemically using antihuman TNF alpha and anti-Leu-M5 (CD11c) antibodies. Additional studies with double immunohistocchemical procedures were performed with anti-glial fibrillary acidic protein and anti-neurofilament antibodies. RESULTS: Eighty per cent of the AA, AOA, and GB (16 of 20) had a positive reaction for TNF alpha, but only 17% of As and OA (one of six) were positive. Positive cells were seen in both the tumour tissue and adjacent brain tissues. TNF alpha protein was detected not only in the tumour cells but also in the endothelium of tumour vessels as well as reactive astrocytes and neurons. CONCLUSIONS: Endogenous TNF alpha is present in cells of various origins in glial tumours including tumour vessels; however, the role of TNF alpha may be different in different types of cells or altered microenvironment.

Brain Chemistry↗
PubMed1996

Molecular epidemiology of breast cancers in northern and southern Japan: the frequency, clustering, and patterns of p53 gene mutations differ among these two low-risk populations.

Comparison of acquired mutations in the p53 tumor suppressor gene can illuminate factors contributing to carcinogenesis among cancer cohorts. Japan has an ethnically homogeneous population with a low incidence of breast cancer. Previously we reported an unusual frequency, allelic status, and clustering of mutations in breast cancers from the northern part of the main Japanese island. To extend these findings, exons 2-11 and adjacent intronic sequences were analysed in tumors of women from northern (Hokkaido) and southern (Tokushima) Japan. The frequency of breast cancers with p53 gene mutations in the Hokkaido group is the highest reported (81%) while that in Tokushima (28%) is similar to most other populations. Thirteen of the 19 mutations (68.4%) in the Hokkaido cohort were heterozygous, an unusually high frequency for p53 mutations in any tumor type. There were three missense mutations at codon 175, a known hotspot for alterations in the p53 gene, and three missense mutations at codon 179, a rare site for p53 changes. In addition, the patterns of p53 gene mutation differed between the two Japanese cohorts (P=0.04). The multiple differences in acquired p53 mutations suggest unsuspected biological differences among breast cancers in northern and southern Japan. In addition, the high frequency of p53 mutations in breast cancers from Hokkaido predicted a poorer prognosis for this population which was confirmed on examination of mortality data.

Adult↗
PubMed1996

Overexpression and mutations of p53 in metastatic malignant melanomas.

Alterations of the p53 tumor suppressor gene are the most frequent genetic abnormalities in human malignancies, but the role of p53 in the etiology of malignant melanomas is unclear. Fifty unselected malignant melanomas were analyzed for p53 overexpression by immunohistochemistry using 3 monoclonal antibodies (MAbs). Fifteen tumors (29.4%) showed positive staining with at least 2 different antibodies. In the first 20 consecutive tumors exons 5-9 and adjacent splice sites of the p53 gene were analyzed by genomic sequencing. There were 4 mutations in 20 metastatic melanomas. Three of 4 mutations were C:G-->T:A transitions. A search of our database of p53 mutations revealed that out of 8 p53 mutations reported by others, 4 are C:G-->T:A transitions at dipyrimidine sites, and one is a tandem CC-->TT mutation. This mutational pattern is comparable with the pattern of p53 mutations in squamous cell and basal cell carcinomas of the skin and is related to exposure to ultraviolet B (UV-B) wavelength radiation. Taken together with a predominance of UV-induced mutations in the CDKN2/ p16 gene demonstrated in melanoma cell lines, our data support a role of sunlight exposure in the etiology of malignant melanoma. The low frequency of p53 mutants in melanomas compared with other types of skin cancers suggests that although mutations in this gene are likely to be involved in the development of some malignant melanomas, they do not play as large a role as in squamous and basal cell carcinomas of the skin.

Genes, p53↗
PubMed1996

Mutation detection by highly sensitive methods indicates that p53 gene mutations in breast cancer can have important prognostic value.

Human cancer cells with a mutated p53 tumor-suppressor gene have a selective growth advantage and may exhibit resistance to ionizing radiation and certain chemotherapeutic agents. To examine the prognostic value of mutations in the p53 gene, a cohort of 90 Midwestern Caucasian breast cancer patients were analyzed with methodology that detects virtually 100% of all mutations. The presence of a p53 gene mutation was by far the single most predictive indicator for recurrence and death (relative risks of 4.7 and 23.2, respectively). Direct detection of p53 mutations had substantially greater prognostic value than immunohistochemical detection of p53 overexpression. Analysis of p53 gene mutations may permit identification of a subset of breast cancer patients who, despite lack of conventional indicators of poor prognosis, are at high risk of early recurrence and death.

Alternative Splicing↗
PubMed1996

Database of mutations in the p53 and APC tumor suppressor genes designed to facilitate molecular epidemiological analyses.

Germline and somatic mutations in the p53 and APC genes contribute to neoplasia. The patterns of these and other acquired mutations in cancers reflect environmental mutagens and endogenous factors that contribute to carcinogenesis. Herein, we describe a database of almost 2,300 mutations in the p53 and APC genes published until September 1, 1993. In addition to cataloging the mutations, multiple fields of information have been added to facilitate future molecular epidemiological analyses of human cancer. The accuracy of the database has been checked by the present authors and, by soliciting feedback from the original corresponding authors. The strengths and limitations of the primary literature are discussed.

Computer Communication Networks↗
PubMed1996

A polymorphism but no mutations in the GADD45 gene in breast cancers.

The p53 gene product is part of a pathway regulating growth arrest at the G1 checkpoint of the cell cycle. Mutation of other components of this pathway, including the products of the ataxia telangiectasia (AT), GADD45, mdm2, and p21WAF1/CIP1 genes may have effects comparable to mutations in the p53 gene. The GADD45 gene is induced by ionizing radiation and several DNA-damaging xenobiotics. Induction requires the binding of wild-type p53 to an evoulutionarily highly conserved putative intronic p53 binding site in intron 3 of GADD45. We recently analyzed the entire coding region of the p53 gene in primary breast cancers of Midwestern white women and found 21 mutations among 53 tumors (39.6%). We now have shown by direct sequencing that there are no mutations in the intronic p53 binding site of the GADD45 gene in any of the 53 primary breast cancers and no mutations in the entire coding region of the GADD45 gene in a subset of 26 consecutive tumors (12 with p53 mutation and 14 without p53 mutation). The only sequence variation detected was a common polymorphism in intron 3. The absence of mutations in the GADD45 gene, including the putative p53-binding intronic site, suggests that this gene is not a frequent target of mutations in breast cancer. Although mutations of the p53 gene have been studied in a wide spectrum of human cancers, GADD45 has not been examined in any tumor or cell line to the best of our knowledge. Our results raise the possibility that mutation of the GADD45 gene alone is not functionally equivalent to loss of wild-type p53 activity.

Base Sequence↗
PubMed1996

High frequency of p53 gene mutations in primary breast cancers in Japanese women, a low-incidence population.

The pattern of acquired mutations in the p53 tumour-suppressor gene is potentially useful for determining factors contributing to carcinogenesis in diverse populations differing in incidence and/or mortality from the disease. We previously reported differences in mutational patterns of the p53 gene in primary breast cancers from Midwest US Caucasian, African-American and Austrian women. Herein, we report 16 mutations in 27 primary breast cancers from Japanese women from Hirosaki, a population with a low incidence of breast cancer. The frequency of 59.3% of p53 mutations is the highest reported in breast cancers from a particular ethnic group thus far. A relatively high number of mutations (7/16) were heterozygous in at least some tumour cell clusters. Intergroup comparisons of the mutational pattern between this population and several other US, European and Japanese populations do not show any statistically significant differences. There were recurrent mutations at two sites, codon 273 (R --> H; three mutations), a common hotspot of mutations in breast and other cancers, and codon 183 (S --> Stop; two mutations), a very rare location for p53 mutations. These mutations were shown to be independent and presumably not in the germ line. The highest frequency of p53 mutations raises the possibility that p53 mutagenesis is a predominant factor for breast cancer development in this low-risk Japanese group, whereas in other cohorts different mechanisms are likely to account for the higher proportion of breast cancer. Further studies are needed to confirm the present observations.

Adult↗
PubMed1996

Need for standardization of cancer practice via nationally accepted treatment guidelines.

The critical need for a reduction in health-care costs has revolutionized the management of a significant segment of the American health-care system. The competition, at least on the basis of cost, will continue to restrict access to care and may reduce quality. For patients with diseases such as specific cancers that have been demonstrated by reproducible methods in comparative trials to be potentially curable or strikingly ameliorated, assurance of treatment by these methods must be guaranteed. Achievement of a national consensus on cancer treatment guidelines for potentially curable cancers is needed as the benchmark of quality health-care plans for patients and payors alike. Documenting adherence to such guidelines and finding mechanisms for improving treatments for future patients remain unresolved challenges of the managed-care era.

Clinical Trials as Topic↗
PubMed1995

p53 gene mutations inside and outside of exons 5-8: the patterns differ in breast and other cancers.

Most studies of mutations in the p53 tumor suppressor gene in tumors have examined only exons 5-8. Our laboratory previously found 64 mutations in exons 5-8 of the p53 gene in 194 primary breast cancers. Herein, we report 18 additional mutations found outside of exons 5-8. Mutations are present in exons 4, 9 and 10, and flanking splice junctions, but not in the promotor region or in exons 1, 2, 3 and 11. No missense mutations are found outside of exons 5-8. Instead, there is a predominance of frameshift mutations with lesser numbers of nonsense and splice site mutations. In contrast, the majority of mutations in exons 5-8 in this sample are missense changes and all of these are at amino acids that are identical in the 11 known p53 sequences that represent about 1.6 billion years of evolutionary divergence. The difference in mutational pattern between these two regions of the p53 gene is due to a lack of missense mutations and inframe microdeletions outside of exons 5-8. A review of our database of p53 mutations (De Vries et al., in preparation) shows that the patterns of mutation inside and outside of exons 5-8 differ in other types of cancers as well. The paucity of missense mutations in exons 2-4 and 9-11 in breast and other cancers (even at amino acids identical throughout p53 gene evolution) suggest that at least some missense mutations result in a phenotype other than malignant transformation. These data also illustrate the importance of examining identical exons when comparing the pattern of p53 gene mutations in different populations.

Adult↗
PubMed1995

Novel pattern of P53 mutation in breast cancers from Austrian women.

Since mutagens produce an extraordinary diversity of mutational patterns, differential mutational exposures among populations are expected to produce different patterns of mutation. Classical epidemiological methods have been successful in implicating specific mutagens in cancers such as those of lung and skin in which one mutagen predominates. In breast cancer, however, no mutagens have been implicated in an unequivocal manner. In an attempt to facilitate epidemiological studies, we have been studying the pattern of p53 gene mutations in breast cancers from multiple populations with high and low breast cancer incidences. We previously reported that breast cancers from Midwest United States, predominantly rural Caucasian women, have a different pattern of p53 gene mutation from populations of Western European women. Herein, we analyze patterns of p53 mutations from Graz, Austria, another population with a high incidence of breast cancer. Among the 60 Austrian breast cancers analyzed, 14 (23%) have a p53 gene mutation in exons 5-9 or in adjacent splice junctions. Analysis of the patterns of mutation shows differences between the "Western European" profile and the Austrian and Midwest United States groups (P = 0.027 and 0.024, respectively). The Austrian pattern is characterized by a high frequency of A:T-->T:A transversions (P = 0.006). The presence of distinct patterns of mutation among the limited number of analyzed populations of Western European origin supports the idea that differential mutagenic exposure and/or genetic differences contribute to breast cancer mutagenesis among geographically distinct Caucasians of Western European origin.

Aged↗
PubMed1995

Rapid and efficient screening for p53 gene mutations by dideoxy fingerprinting.

Dideoxy fingerprinting (ddF) is an efficient method for detecting single base and other sequence changes in PCR-amplified DNA segments. This screening method is a hybrid between single-strand conformation polymorphism analysis (SSCP) and Sanger dideoxy sequencing. It involves a Sanger sequencing reaction with one dideoxynucleotide followed by non-denaturing gel electrophoresis. We are using ddF to screen for mutations in the p53 tumor suppressor gene in primary breast cancers. ddF detected more than 100 mutations in different regions of the gene, including all types of single-base mutations and microdeletions/microinsertions of various sizes. Furthermore, ddF reliably detected heterozygous mutations, if the region of interest was screened in both directions. In a blinded, prospective study, ddF detected all 25 mutations within exons 4-10 and adjacent flanking intronic regions previously found by direct sequencing. ddF was also useful in scoring two common polymorphisms within the p53 gene. Guidelines for preventing false-positive and false-negative results are summarized.

Breast Neoplasms↗