ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Mutations in the p53 tumor suppressor gene are the most common genetic alterations found in human cancer. Most mutations are accompanied by stabilization of the protein, which renders the mutations detectable through immunohistochemical techniques. The immunoreactivity of p53, however, might not correlate with the result of p53 DNA sequencing. In order to explain the discrepancy, we studied the p53 expressions, mutations, and changes of the three-dimensional protein structure of mutant p53 in a series of 61 pancreatic adenocarcinoma specimens using immunohistochemistry, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), DNA sequencing, and computerized protein modeling. PCR-SSCP followed by DNA sequencing of the p53 gene showed mutations in 31.2% (19 of 61) of the pancreatic adenocarcinomas. Eight of 19 cases showed p53 immunopositivity. These mutations were located on the surface of the three-dimensional structure or formed unfolded proteins, which were easily recognized by the antibody. Among other mutations in which p53 was immunonegative, five cases with deletions and insertion caused frameshift and formation of severely truncated p53 protein structures unreactive with the antibody used. In three cases with point mutations, the mutant amino acids were located in the core of the tightly packed β sandwich inaccessible to the antibody. Three silent mutations were immunonegative, corresponding with the absence of amino acid changes. These results strongly suggest that the analysis of a computer-generated p53 three-dimensional model based on DNA sequencing data can assist in evaluating the significance of p53 immunostaining and mutations for clinical applications.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Most studies of the reverse transcriptase in situ polymerase chain reaction technique have reported results from assessments of cultured cells, frozen sections, and cytospin preparations. For application to routine diagnosis, it will be necessary to adapt the technique for use with formalin-fixed, paraffinembedded tissues, the materials that are generally available. We have evaluated the feasibility of such an approach, using surgical pathology archival material from 25 UCLA patients: 15 tissues from primary and metastatic melanoma, 7 from non-melanocytic tumors, including cancer of the lung, colon, kidney and skin and a thyroid adenoma, and 3 nontumorous tissues. Seven of 15 melanoma tissues gave a strong positive signal, 5 gave a weak signal, and 3 were negative. None of the 10 non-melanoma tissues gave a positive signal. The specific reaction product was mainly located in the cytoplasm. None of the nonmelanocytic tumors or normal tissues demonstrated this pattern of cytoplasmic staining. Some nonspecific nuclear staining was observed in melanocytic and nonmelanocytic tumors and must not be overread as a true positive result. It is possible to detect tyrosinase mRNA in formalin-fixed, paraffinembedded tissue sections of melanoma, but the technique remains too demanding for routine application.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The authors report a recurred neoplasm showing distinctive histologic, immunophenotypic, and ultrastructural features characteristic of biphasic synovial sarcoma with neural differentiation. The features include areas with a growth pattern of densely packed spindle cells in irregularly intersecting, broad fascicles, diffuse vimentin and HBA 71 immunoreactivity, expression of S-100 protein, and other neural markers. Moreover, areas with glandular structures and cellular expression of cytokeratin and epithelial membrane antigen were noted. Additionally, areas of neural-like growth pattern were positive for neuron-specific enolase, HNK-1, and protein gene product 9.5. Furthermore, cytogenetic analysis, two-color interphase fluorescence in situ hybridization, and reverse transcription polymerase chain reaction demonstrated the reciprocal translocation between chromosomes X and 18 associated with the different subtypes of tumor cells. The establishment and characterization of the tumor cell line are detailed. This cell line retains the distinct morphologic and genetic characteristics of the original biphasic synovial sarcoma with neural differentiation.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We report two cases of desmoplastic small round cell tumor (DSRCT) with novel molecular variants of the specific EWS-WT1 gene fusion. This fusion usually encodes a chimeric RNA with an in-frame junction of exon 7 of EWS to exon 8 of WT1. In one variant patient, the EWS-WT1 fusion transcript contained an in-frame junction of exon 9 of EWS to exon 8 of WT1. Moreover, in this patient the tumor arose in the hand, an extremely unusual site for DSRCT. In the second patient, an in-frame junction of exon 10 of EWS to exon 8 of WT1 was present. These two cases of DSRCT show that the molecular variability in the EWS breakpoint observed in the EWS-FLI1 fusion of Ewing's sarcoma can occur in DSRCT as well. This type of heterogeneity is relevant to the interpretation of molecular diagnostic assays and could also affect the functional properties of the encoded chimeric transcription factors.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Most Ewing tumors (ET), including Ewing sarcomas, peripheral primitive neuroectodermal tumors (PNET), and Askin's tumors, can be defined according to the specific chromosomal translocations t(11; 22)(q24;q12) (EWS-FLI-1) or t(21;22)(q21; q12) (EWS-ERG).Detection of the chimeric RNA transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) has greatly facilitated the diagnosis of ET. Because of variable chromosomal breakpoint locations, however, the EWS gene fusions with FLI-I and ERG genes are highly heterogenous, resulting in different sizes of the amplification products. To improve the diagnostic usefulness of the RT-PCR assay, we have developed an assay to detect chimeric mRNA transcripts by nested RT-PCR, followed by digestion of the PCR fragments with three different restriction endonucleases. This allows confirmation of the specificity of the PCR product and provides a rapid method to determine the combination of exons present in a transcript. In the 12 Ewing tumors tested, five different exon combinations were detected. In nine repeat biopsies of four patients, the case-specific translocation remained unchanged. One additional central PNET had no ET-specific translocation. In conclusion, the suggested combination of RT-PCR and restriction analysis of the PCR products allows a rapid and specific determination of ET-specific translocations.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Ewing's sarcomas (ESs), primitive neuroectodermal tumors (PNETs), and neuroblastomas (NBs) are closely related neoplasms supposedly derived from the neural crest and belonging to the family of the small blue round cell tumors of infancy and childhood. We investigated the expression of the neuroendocrine and neuroectodermal markers chromogranin A (CgA) and secretogranin II (SgII) in ESs, PNETs, and NBs, both in primitive tumors (five, nine, and four cases, respectively) and in established cell lines (three ES and two PNET cell lines). Different technical approaches, namely immunohistochemistry, Northern blot analysis, and reverse transcriptase-polymerase chain reaction (RT-PCR) were used in parallel.Chromogranin A and secretogranin II production was constantly detectable in NBs by all procedures. CgA mRNA was detectable in most ESs and PNETs only by RT-PCR, whereas SgII mRNA was detectable in some ESs and PNETs by Northern blot analysis and in all tumors by RT-PCR. CgA and SgII proteins were never detectable by immunohistochemistry in ESs and PNETs.We conclude that neuroendocrine differentiation is shared by all three tumor entities, being more overt in NBs and rudimentary in ESs and PNETs; traces of chromogranin mRNA are detectable only by a highly sensitive RT-PCR procedure.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The expression of macrophage migration inhibitory factor (MIF) in prostate tissue was investigated by immunohistochemistry (IHC), enzyme-linked immunosorbent assay (ELISA), and Northern blot analysis using a prostate tissue bank. MIF expression was examined in each of the following established prostate tissue categories: prepubertal, pubertal, adult normal, benign hyperplastic (BPH), focal carcinoma within the prostate, and metastatic prostate cancer. IHC showed that all samples tested were positive for MIF protein, which localized to the glandular epithelial cells with no apparent staining of stroma. The most intense staining was observed in the metastatic prostatic adenocarcinoma and the human prostatic adenocarcinoma cell line LNCaP. Using quantitative ELISA, MIF expression was found to be at least three times higher in metastatic adenocarcinoma than in normal, BPH, or focal carcinoma in the adult prostate. This study is the first to report that prostate glandular epithelial cells express MIF. The exact role of MIF in prostate development and disease progression requires further study.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Chondrosarcoma is a primary bone tumor that has several different grades and variants. We evaluated 48 chondrosarcomas for p53 overexpression and p53 mutations. p53 expression was evaluated with immunohistochemistry using monoclonal antibodies PAb421, PAb1801, and PAb240. p53 mutations were identified with single-strand conformational polymorphism (SSCP) and DNA sequencing in selected cases. Immunohistochemistry revealed nuclear staining with PAb421 and PAb1801 in the spindle cell portion of one dedifferentiated chondrosarcoma. SSCP analysis was abnormal only in the case with positive immunostaining and localized the mutation to exons 7 and 8. DNA sequence analysis identified a point mutation of G to C in codon 276, resulting in an amino acid substitution of proline for alanine. This point mutation has been reported previously in other tumors but not in chondrosarcoma. Assimilation of our results with previous studies suggests that p53 mutations are present in a minority of chondrosarcomas but when present, are in higher grade chondrosarcomas and their variants.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Molecular genetic analysis indicates that the BRCA2 gene plays an important role in familial male breast cancer. To determine a possible involvement of this tumor suppressor gene in sporadic male breast cancer, we examined 30 sporadic male breast carcinomas for loss of heterozygosity (LOH) at two loci on chromosome 13q12–13, a region that spans the BRCA2 locus. Sixteen of 24 (67%) informative cases showed LOH in at least one marker on chromosome 13q12–13. The affected cases included both invasive ductal carcinomas and other types of invasive breast carcinoma and were detected preferentially in patients who were 50 years or older, in patients with lymph node metastasis, and in progesterone receptor-negative cases. We report, for the first time, a high frequency of LOH at chromosome 13q12–13 in sporadic male breast cancer and its association with factors indicating a poor prognosis for this tumor (e.g., lymph node metastasis and negative progesterone receptor status). These findings suggest an important role for BRCA2 in the development and progression of sporadic male breast cancer.

ISSN:1052-9551    

出版商:OVID    

年代:1998

数据来源: OVID