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C A Moskaluk

Publications and source records attributed to C A Moskaluk.

At least 37 records · Page 2Linked to original sources
PubMed1999

Incidence of loss of heterozygosity at p53 and BRCA1 loci in serous surface carcinoma.

Serous surface carcinoma (SSC) is a neoplasm histologically indistinguishable from typical serous carcinomas that arise from the ovary but has a distinct clinical presentation. It is characterized by widespread peritoneal dissemination at presentation, but the ovaries are grossly normal in size and shape. If the carcinoma involves the ovaries microscopically, the tumor is confined to the surface or is minimally invasive. The recognition of this entity is important, because in some studies it appears to have a poorer prognosis than stage-matched serous cancers of the ovary. Loss of heterozygosity (LOH) of the p53 (17p) and BRCA1 (17q) tumor suppressor genes has been frequently identified in sporadic ovarian carcinomas. Although 17p LOH is correlated with common p53 gene mutations, inactivating mutations of the BRCA1 gene are uncommon in sporadic ovarian cases. In contrast, germline BRCA1 mutations are responsible for some hereditary forms of ovarian cancer, where it has been suggested that germline BRCA1 mutations confer a more favorable prognosis. In this study, 12 sporadic SSC were assessed for the presence of allelic deletions on the p53 and BRCA1 gene loci. DNA from both tumor and normal cells was obtained for LOH studies using tissue microdissection. Polymerase chain reaction (PCR) amplification was performed with the polymorphic DNA markers TP53 (17p13.1/p53 gene) and D17S579 (17q/BRCA1 gene). LOH in the p53 and BRCA1 loci was detected in 62.5% and 66.6% of the cases, respectively. In 50% of tumors informative for both markers, it is possible that an entire chromosome may be lost. In conclusion, we have shown that LOH of the p53 and BRCA1 loci is a frequent event in sporadic SSC, similar to what has been described in the usual form of serous ovarian carcinoma. Mutational analysis will be necessary to determine the exact role of these genes in this group of tumors.

Chromosomes, Human, Pair 17↗
PubMed1999

KIT protein expression and analysis of c-kit gene mutation in adenoid cystic carcinoma.

The c-kit proto-oncogene encodes a transmembrane receptor tyrosine kinase (KIT), which is expressed in several normal human tissues, especially mast cells and interstitial cells of Cajal. Expression of KIT has been noted in several types of neoplasms and gene mutation has been shown as a mechanism of c-kit oncogene activation in some tumors. Recently, a single adnexal adenoid cystic carcinoma (ACC) was reported to demonstrate KIT expression, however, examination of KIT expression or c-kit mutation in ACC of salivary glands has not been performed. We examined archival tissue samples from 30 ACC of major and minor salivary glands for KIT protein expression by immunohistochemistry with a polyclonal antibody and c-kit gene mutation by polymerase chain reaction amplification and DNA sequencing. KIT protein expression was noted in 90% of ACCs. An association between the presence of at least 50% KIT positive neoplastic cells and Grade 3 ACC or a solid growth pattern was observed (P < .05). KIT expression in normal or nonneoplastic salivary gland tissue was absent. No c-kit juxtamembrane domain (exon 11) or phosphotransferase domain (exon 17) mutations were found in any of the tumors examined. In conclusion, KIT protein expression is correlated with tumor grade of salivary ACC. However, gene mutation of exon 11 or exon 17 is not a mechanism of c-kit activation in these neoplasms.

Adult↗
PubMed1998

Allelic deletion in 11p15 is a common occurrence in esophageal and gastric adenocarcinoma.

BACKGROUND: Esophageal adenocarcinoma and gastric adenocarcinoma have distinct epidemiologic characteristics, but they are morphologically identical and sometimes clinically indistinguishable. Recent work in molecular oncology suggests that cancer types have distinct molecular genetic profiles that may explain their biologic differences. Gastric adenocarcinoma has previously been shown to have a relatively high rate of deletion in chromosome 11. To determine whether similar genetic loci are involved in esophageal adenocarcinoma, we assayed for genetic loss in chromosome 11 in samples of these cancers. METHODS: Dissection of neoplastic and nonneoplastic tissue was performed under direct microscopic visualization from histologic sections of 15 gastric adenocarcinomas and 15 esophageal adenocarcinomas. After DNA extraction, polymerase chain amplification products of a series of polymorphic microsatellite markers on chromosome 11 were analyzed by polyacrylamide gel electrophoresis. Tumor specific chromosomal deletion was signaled by the loss of microsatellite alleles. RESULTS: A panel of 3 polymorphic markers in 11p15 revealed overall incidences of loss of heterozygosity (LOH) of 53.3% in esophageal adenocarcinomas and 61.5% in gastric adenocarcinomas. A panel of 3 polymorphic markers in 11q22-23.3 revealed overall incidences of LOH of 14.3% in esophageal adenocarcinomas and 31% in gastric adenocarcinomas. Diffuse microsatellite instability, which was consistent with a replication error phenotype, was found in 2 of 15 (13.3%) gastric adenocarcinomas but was not deleted in esophageal adenocarcinomas. CONCLUSIONS: Esophageal and gastric adenocarcinoma have a similar significant incidence of genetic loss in 11p15. This is suggestive of the presence of a tumor suppressor gene that may be inactivated in both tumor types.

Adenocarcinoma↗
PubMed1998

Novel germline p16(INK4) allele (Asp145Cys) in a family with multiple pancreatic carcinomas. Mutations in brief no. 148. Online.

As part of a search for causative genes of familial pancreatic carcinoma, the p16 genes were sequenced in members of 21 families with a phenotype of familial pancreatic carcinoma (2 or more first degree relatives affected). One family was found in which members carried a novel p16 allele with a G to T transversion at position 451, creating a missense amino acid change at codon 145 (Asp to Cys) and possibly disrupting the donor splice site of the exon 2/3 boundary. This coding change is not a known polymorphism, and occurs at a codon position in which another missese/splicing change has been shown to be linked to familial melanoma/pancreas cancer.

Alleles↗
PubMed1998

Comparative genomic hybridization of esophageal and gastroesophageal adenocarcinomas shows consensus areas of DNA gain and loss.

Relatively little is known about the genetic changes that occur in esophageal and gastroesophageal adenocarcinomas. To provide a survey of relative DNA gains and losses in these cancers, we microdissected 15 primary human esophageal and gastroesophageal adenocarcinomas to enrich for cancer cells and subsequently performed comparative genomic hybridization. Eighteen regions of high-level amplification were detected in 11 tumors, with 8p23, 17q21, and 18p11 showing four, three, and two such events, respectively. The most common minimal regions of gain were 8q24 (8/15), 20q (7/15), 17q21 (7/15), and 7p 1-15 (7/15 ). The most common minimal regions of loss were 5q 12-21 (8/15), 4q10-24 (5/15), 4p (5/15), and 18q (3/15). These results implicate the well-characterized oncogenes MYC (8q24) and ERBB2 (17q21), and they predict the involvement of additional oncogenes on 8p23, 20q, and chromosome 7 in the pathogenesis of these cancers. Chromosomes 4 and 5 are frequent targets of deletion in these tumors and may harbor novel tumor suppressor genes.

Adenocarcinoma↗
PubMed1997

Abrogation of the Rb/p16 tumor-suppressive pathway in virtually all pancreatic carcinomas.

The Rb/p16 tumor-suppressive pathway is abrogated frequently in human tumors, either through inactivation of the Rb or p16INK4a/CDKN2/MTS1 tumor-suppressor proteins, or through alteration or overexpression of the cyclin D1 or cyclin-dependent kinase 4 oncoproteins. We reported previously that the p16 gene was genetically inactivated in 82% of pancreatic carcinomas. Nearly half of these inactivations were by intragenic mutation of p16, and the remainder were by homozygous deletion of the gene. Here, we analyzed pancreatic carcinomas for additional mechanisms by which the Rb/p16 pathway might be inactivated. Transcriptional silencing of the p16 gene in association with methylation of its 5'-CpG island was examined by methylation-specific PCR in 18 pancreatic carcinomas. Nine of these were known to harbor an intragenic mutation in p16, and nine had a wild-type p16 coding sequence. Seven of the 18 tumors were hypermethylated, and all 7 were p16 wild-type (P = 0.001). Complete silencing of transcription from methylated wild-type gene sequences was demonstrated. Immunohistochemical analysis revealed normal expression levels of the Rb protein in all carcinomas studied. None of the carcinomas had genomic amplification of the cyclin D1 or CDK4 genes, and none had mutation of the p16-binding domain of CDK4. An additional p16 mutation was identified. In total, the Rb/p16 pathway was abrogated in 49 of the 50 carcinomas (98%) studied, all through inactivation of the p16 gene. Similar results were obtained in an independently analyzed series of 19 pancreatic carcinomas. These data demonstrate the central role of the Rb/p16 pathway in the development of pancreatic carcinoma.

Carrier Proteins↗
PubMed1997

p16 and K-ras gene mutations in the intraductal precursors of human pancreatic adenocarcinoma.

Pancreatic adenocarcinoma is thought to arise from a noninvasive neoplastic precursor, the pancreatic intraductal lesion (PIL). Mutations of the K-ras gene are known to occur in PILs, but their high prevalence among PILs within the general population probably limit the use of K-ras as a marker of eventual clinical risk. In search of genetic constellations that might indicate the progression of some PILs toward an invasive phenotype, mutations at both the K-ras and p16 genes were sought within PILs of 10 pancreata resected for adenocarcinoma. K-ras mutations were present in most PILs and in nearly all PILs having nuclear atypia. In half of the patients, two or more unique K-ras mutations were identified among distinct PILs, which is evidence for the separate clonal evolution of multiple pancreatic neoplasms within individual patients. p16 alterations (one homozygous deletion and three point mutations) were found in 4 of the 10 carcinomas; these four pancreata harbored p16 alterations in three of nine PILs, of which one was a "histologically early" lesion. Two patients had p16 alterations in PILs matching those of the associated carcinomas. p16 mutations were not found in PILs of pancreata having wild-type p16 in the carcinoma, nor were they found in ducts having normal histology. It is suggested that alterations of the p16 gene affect a subset of PILs that contain mutations of the K-ras gene and that these mutations might identify high-risk precursors of the invasive malignancy.

Adenocarcinoma↗
PubMed1997

Immunohistochemical expression of pi-class glutathione S-transferase is down-regulated in adenocarcinoma of the prostate.

BACKGROUND: Glutathione S-transferase is often up-regulated in neoplastic tissues. A single previous study found a loss of expression associated with carcinogenesis of the prostate. METHODS: To extend these results, the authors performed immunohistochemical staining for the pi-class of glutathione S-transferase (GSTpi) on 74 archival sequential prostate specimens. The antibody used was derived from rabbits immunized against purified human GSTpi. Paraffin blocks containing both benign tissue and adenocarcinoma were studied. RESULTS: Heterogeneous expression of GSTpi in benign acini was found in 96% of cases, but GSTpi was not expressed in 95% of invasive adenocarcinomas of the prostate, nor was it expressed in any of the foci of high grade prostatic intraepithelial neoplasia. Basal cells of benign acini showed strong, diffuse staining for GSTpi, whereas the secretory luminal epithelium expressed GSTpi weakly and focally. CONCLUSIONS: This study confirms the down-regulation of GSTpi in adenocarcinoma of the prostate and shows that the loss of GSTpi expression is a phenotype associated with malignant transformation.

Adenocarcinoma↗
PubMed1997

The multiple endocrine neoplasia type I gene locus is involved in the pathogenesis of type II gastric carcinoids.

BACKGROUND & AIMS: Both gastrin and genetic factors were suggested to underlie the pathogenesis of multiple gastric enterochromaffin-like (ECL) cell carcinoids. To assess the role of genetic alterations in carcinoid tumorigenesis, loss of heterozygosity (LOH) at the locus of the multiple endocrine neoplasia type 1 (MEN-1) gene was studied in gastric carcinoids of patients with MEN-1 and chronic atrophic type A gastritis (A-CAG), as well as in sporadically arising intestinal carcinoids. METHODS: DNA extracted from archival tissue sections of 35 carcinoid tumors was assessed for LOH with eight polymorphic markers on chromosome 11q13. A combined tumor and family study was performed in 1 patient with MEN-1-Zollinger-Ellison syndrome (ZES). RESULTS: LOH at 11q13 loci was detected in 15 of 20 (75%) MEN-1-ZES carcinoids, and each ECL-cell carcinoid with LOH showed deletion of the wild-type allele. Only 1 of 6 A-CAG carcinoids displayed LOH at the MEN-1 gene locus, and none of the 9 intestinal and rectal carcinoids showed 11q13 LOH. CONCLUSIONS: Gastric ECL-cell carcinoid is an independent tumor type of MEN-1 that shares a common developmental mechanism (via inactivation of the MEN-1 gene) with enteropancreatic and parathyroid MEN-1 tumors. Further analysis of sporadic and A-CAG carcinoids is needed to elucidate genetic factors involved in their tumorigenesis.

Adult↗
PubMed1997

Genomic sequencing of DPC4 in the analysis of familial pancreatic carcinoma.

A first-degree relative with pancreatic cancer is found in 5% to 10% of patients with pancreatic carcinomas, suggesting an inherited predisposition for this neoplasm. The recently identified DPC4 tumor suppressor gene is a strong candidate for the gene responsible for the familial form of pancreatic carcinoma. DPC4 was identified in a consensus area of homozygous deletion in pancreatic carcinomas, and it is biallelically inactivated in approximately 50% of sporadic pancreatic carcinomas. The coding sequence of this gene is 1660 nucleotides in length, covering 11 exons. We describe optimized primers and conditions used in polymerase chain reaction and cycle sequencing of the entire DPC4 coding sequence of 25 individuals (eight with pancreatic carcinoma) from 11 kindreds with a familial aggregation of pancreatic carcinoma. No mutations in the coding sequences of the DPC4 gene were found; hence, it appears that germline mutations in DPC4 cannot account for many of the familial aggregations of pancreatic carcinoma.

Carcinoma↗
PubMed1997

Genetic alterations and epithelial dysplasia in juvenile polyposis syndrome and sporadic juvenile polyps.

Juvenile polyps are regarded as hamartomatous polyps and occur in sporadic and familial syndromic settings. There is increased risk of gastrointestinal neoplasia in patients with juvenile polyposis syndrome, but the molecular mechanisms are not known. We therefore studied 78 colorectal juvenile polyposis from 12 patients with juvenile polyps syndrome and 34 sporadic juvenile polyps for epithelial dysplasia and genetic changes associated with colorectal neoplasia. Dysplasia occurred in 31% of syndromic juvenile polyps but not in sporadic juvenile polyps (P < 0.0001). Topographic control of proliferation and expression of the cyclin-dependent kinase inhibitor p21(WAFI/CIP1) seen in native colorectal epithelium was lost in 79% of dysplastic juvenile polyps and in 8% of nondysplastic juvenile polyps (P < 0.000001). Somatic mutations in the adenomatous polyposis coli (APC) gene were demonstrated in 50% of dysplastic juvenile polyps (3 of 6) but not in any of 16 juvenile polyps without dysplasia (P = 0.01). Both sporadic and syndromic juvenile polyps had K-ras mutations (14%) and there was no relationship to dysplasia. p53 gene product overexpression identified by immunohistochemical staining occurred rarely in dysplastic juvenile polyps (2 of 24, 8%). Our results indicate that the multiple genetic alterations involved in usual colorectal neoplasia also play a role in neoplastic transformation of juvenile polyps, predominantly in juvenile polyposis syndrome.

Adenomatous Polyposis Coli↗
PubMed1997

Microdissection and polymerase chain reaction amplification of genomic DNA from histological tissue sections.

Polymerase chain reaction (PCR)-based assays are being used increasingly to study the molecular genetic changes that occur in minute cellular lesions that are identified in histological sections. It is often desirable to microdissect the cells of interest in a lesion, isolating them from surrounding normal tissue to obtain the purest representation of genomic DNA possible. We present here an optimized microdissection and DNA extraction protocol that reliably produces PCR-amplifiable DNA from lesional tissue less than 0.1 mm in diameter. The utility of this technique is demonstrated by PCR amplification and sequencing of the K-ras gene and microsatellite PCR analysis of proliferative epithelial lesions in the small ducts of a human pancreas involved by cancer.

DNA↗
PubMed1996

Germline BRCA2 gene mutations in patients with apparently sporadic pancreatic carcinomas.

Germline mutations in BRCA2 predispose carriers to the development of breast, ovarian, and a variety of other cancers. The original localization of the BRCA2 gene was aided by its homozygous deletion in a pancreatic carcinoma; indeed, an excess of pancreatic carcinoma has been seen in some BRCA2 cancer families. To determine the involvement of BRCA2 in pancreatic carcinomas, we screened for BRCA2 alterations in an unselected panel of 41 adenocarcinomas of the pancreas (30 pancreatic adenocarcinoma xenografts and 11 pancreatic cancer cell lines). Of the 15 (27%) that had allelic loss at the BRCA2 locus, 4 (9.8%) had abnormalities in the second allele upon screening of the entire BRCA2 gene by in vitro synthesized protein assay. Three of the four mutations were considered germline in origin (7.3% overall; two were confirmed in normal tissue, and one was the 6174delT mutation from the pancreatic cancer cell line CAPAN-1, for which normal tissue was unavailable). The identification of two 6174delT mutations in this series prompted us to evaluate the prevalence of this mutation in an overlapping consecutive series of 245 patients who underwent pancreatoduodenectomy for adenocarcinoma of the pancreas. Sequence analysis of this limited region of the gene identified two additional mutations: (a) one additional germline 6174delT mutation (2 of 245, 0.8% overall); and (b) a second nearby germline 6158insT mutation. One of the patients with a germline mutation had a single relative with breast cancer, and another had a single relative with prostate cancer. None had a family history of pancreatic cancer. The incidence of germline BRCA2 mutations in apparently sporadic pancreatic cancer may be at least as high as in breast or ovarian cancer. Our results suggest that some familial risks for carcinoma will be evident only through a population-based application of gene screening techniques because a low disease penetrance of the germline mutations in some families often evades clinical suspicion.

Adenocarcinoma↗
PubMed1996

Homozygous deletion map at 18q21.1 in pancreatic cancer.

Absolute genetic differences between neoplastic and nonneoplastic cells can be discerned at sites of homozygous deletions. These deletions are of critical interest because they might be useful in the identification of defective biochemical pathways in neoplastic cells, and subsequently for the development of new treatment strategies in human cancer. We identified an area at 18q21.1 involved by homozygous deletions in 30% of pancreatic carcinomas. To characterize the homozygous deletions, we constructed a detailed physical map of nearly 2 Mb, containing yeast artificial chromosomes, P1-derived artificial chromosomes, cosmids and 24 sequence-tagged sites. The homozygously deleted are contained a new candidate tumor-suppressor gene (DPC4). To date, 23 (64%) of 35 pancreatic carcinomas carry at least one homozygous deletion at a published locus. The study of the total gene content of these loci, facilitated by the sequence-tagged site markers and maps of these regions, should help to reveal the absolute biochemical differences between neoplastic and nonneoplastic cells for a common human tumor.

Alleles↗
PubMed1996

DPC4, a candidate tumor suppressor gene at human chromosome 18q21.1.

About 90 percent of human pancreatic carcinomas show allelic loss at chromosome 18q. To identify candidate tumor suppressor genes on 18q, a panel of pancreatic carcinomas were analyzed for convergent sites of homozygous deletion. Twenty-five of 84 tumors had homozygous deletions at 18q21.1, a site that excludes DCC (a candidate suppressor gene for colorectal cancer) and includes DPC4, a gene similar in sequence to a Drosophila melanogaster gene (Mad) implicated in a transforming growth factor-beta (TGF-beta)-like signaling pathway. Potentially inactivating mutations in DPC4 were identified in six of 27 pancreatic carcinomas that did not have homozygous deletions at 18q21.1. These results identify DPC4 as a candidate tumor suppressor gene whose inactivation may play a role in pancreatic and possibly other human cancers.

Alleles↗
PubMed1996

p53 and p21(WAF1/CIP1/SDI1) gene products in Barrett esophagus and adenocarcinoma of the esophagus and esophagogastric junction.

The WAF1 (CIP1/SDI1) gene encodes a cyclin-dependent kinase inhibitor which is induced by wild-type, but not mutated, p53 gene product. WAF1 immunohistochemistry has been suggested to clarify the phenotype of overexpressed p53 gene product. We evaluated both p53 and WAF1 gene products by immunohistochemistry in 98 esophagectomy specimens with Barrett esophagus and/or adenocarcinoma of the esophagus and esophagogastric junction. Diffuse positive p53 staining was found in 40 of 88 adenocarcinomas (45%) and in dysplastic Barrett epithelium in 20 of 65 cases (31%), but not in Barrett mucosa without dysplasia (n = 36, P = .0004). Eighty-eight percent of cancers exhibited WAF1 expression, but there was no association with p53 and WAF1 staining. WAF1 protein was also identified in Barrett epithelium and in esophageal squamous and gastric epithelium. In contrast to carcinomas, a unique pattern of mutually exclusive p53 and WAF1 expression was found in five cases of dysplastic Barrett epithelium; a missense mutation at codon 175 of p53 was identified in one. p53 staining of adenocarcinoma was associated with shorter patient survival but was not independent of stage; WAF1 status added no prognostic information. Our findings show that WAF1 immunohistochemistry complements p53 immunohistochemistry in some cases of Barrett dysplasia but not in adenocarcinomas. Positive p53 immunostaining can serve to confirm a neoplastic process in Barrett mucosa. Positive staining of adenocarcinomas may be an indication of advanced stage.

Adenocarcinoma↗
PubMed1995

Isolation of YAC insert sequences by representational difference analysis.

We present a method for the isolation of YAC insert sequences by representational difference analysis (RDA). To achieve maximal representation of the sequences, the amplicons were generated from a Mbol digestion product. RDA was performed using a 970 kb insert YAC clone. After two rounds of re-association and selective amplification 92% of the difference product represented sequences derived from the YAC insert. Twenty insert-specific sequence-tagged sites were readily defined. The difference product was also successfully used to isolate microsatellite markers, to identify clones from a human PAC library and as a chromosome painting probe in fluorescence in situ hybridization.

Base Sequence↗