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Biomedical subjects

R C Bast

Publications and source records attributed to R C Bast.

At least 109 records · Page 6Linked to original sources
PubMed1994

Differential expression of the 67-kD laminin receptor and 31-kD human laminin-binding protein in human ovarian carcinomas.

The expression of the 67-kD laminin receptor (67LR) and the 31-kD human laminin-binding protein (HLBP31), two proteins involved in cancer cell laminin interaction, was evaluated on 30 ovarian cancer specimens. Expression of the 67LR was increased (up to 2.5-fold, in 87% of the patients), while HLBP31 expression was downregulated in cancer cells compared with the normal tissue, as detected by northern blotting and immunohistochemistry. The immunohistochemical study demonstrated that the 67LR was significantly overexpressed (P < 0.05) in the group of patients whose cytoreductive surgery was suboptimal, and those with poor clinical outcome. No correlation was observed between HLBP31 expression and clinicopathological features. Increased expression of the 67LR appears to correlate with the invasive phenotype of ovarian cancer cells and suggests a role of the latter in ovarian cancer invasion.

Carrier Proteins↗
PubMed1994

Overexpression of the tyrosine phosphatase PTP1B is associated with human ovarian carcinomas.

OBJECTIVE: Our purpose was to determine whether protein tyrosine phosphatase 1B is overexpressed in ovarian cancers, possibly altering the balance of intracellular tyrosine phosphorylation. STUDY DESIGN: The expression of protein tyrosine phosphatase 1B was assayed in frozen sections from 54 human ovarian carcinomas and seven normal ovaries by immunochemical staining with monoclonal antibody AE4-2J, which is specific for protein tyrosine phosphatase 1B. The expression of protein tyrosine phosphatase 1B-specific messenger ribonucleic acid in tumors was determined by Northern analysis. The results were analyzed statistically by means of Fisher's exact test. RESULTS: Minimal staining was observed in normal ovarian epithelium. In contrast, 43 of 54 (79.6%) tumors displayed increased protein tyrosine phosphatase 1B expression, which is statistically associated with malignancy. Overexpression was associated with the expression of the p185c-erbB-2, p170EGFR, and p165mCSFR growth factor receptor protein tyrosine kinases. Protein tyrosine phosphatase 1B messenger ribonucleic acid expression was inconsistently increased in tumor cells. CONCLUSION: Increased expression of protein tyrosine phosphatase 1B in ovarian cancers that also express protein tyrosine kinases suggests that protein tyrosine phosphatase 1B may play a role in the growth regulation of ovarian cancers.

Female↗
PubMed1994

Coordinate expression of urinary-type plasminogen activator and its receptor accompanies malignant transformation of the ovarian surface epithelium.

OBJECTIVE: Because elevated expression and cell surface association of urinary-type plasminogen activator have been linked to invasive potential in certain tumor types, we examined the expression of urinary-type plasminogen activator and urinary-type plasminogen activator receptor in ovarian epithelial carcinoma tissues and cells as compared with normal ovarian epithelium. STUDY DESIGN: Monoclonal antibodies specific for urinary-type plasminogen activator and urinary-type plasminogen activator receptor were used for immunohistochemical staining of tissues and cells to assess expression of these antigens in frozen sections of normal and tumor tissue. Substrate zymography was used to detect plasminogen activator activity in ovarian carcinoma ascites and in conditioned media of cultured cells, whereas a Western blot assay was used to identify urinary-type plasminogen activator receptor in cultured cells. RESULTS: Normal ovarian epithelium expressed urinary-type plasminogen activator receptor (4/4 positive) but little or no urinary-type plasminogen activator (0/4 positive), whereas epithelial ovarian carcinomas frequently expressed urinary-type plasminogen activator (4/8 positive) in conjunction with urinary-type plasminogen activator receptor (7/9 positive). High levels of urinary-type plasminogen activator were detected in 15 of 19 samples of ascites. DOV 13, OVCA 420, OVCA 429, OVCA 432, and OVCA 433 cell lines secreted urinary-type plasminogen activator in variable quantities, whereas normal ovarian epithelial cells did not secrete any detectable plasminogen activator. Urinary-type plasminogen activator receptor had similar levels of expression in all cancer cell lines and normal ovarian epithelium. CONCLUSION: Overexpression of urinary-type plasminogen activator is associated with malignant transformation of the ovarian epithelium. Increased cell surface proteolysis mediated by urinary-type plasminogen activator bound to cell surface urinary-type plasminogen activator receptor may contribute to metastatic behavior in ovarian carcinoma.

Carcinoma↗
PubMed1994

The p53 tumor suppressor gene frequently is altered in gynecologic cancers.

Mutation of the p53 tumor suppressor gene, often accompanied by overexpression of mutant p53 protein, is the most frequent molecular genetic event described thus far in human cancers. In adenocarcinomas of the ovary and endometrium, p53 overexpression is seen in approximately 10% to 15% of early and 40% to 50% of advanced cancers. Similar to many other types of human cancers, ovarian and endometrial cancers that overexpress p53 protein contain mutations in conserved regions of the p53 gene. These mutations are predominantly transitions, which suggests that they arise spontaneously rather than being caused by carcinogen exposure. Alteration of the p53 gene does not appear to be a feature of endometrial hyperplasias or benign or borderline ovarian tumors. Although mutation and overexpression of p53 rarely occur in cancers of the cervix, vulva, and vagina, it has been shown that human papillomavirus E6 oncoproteins bind to and inactivate p53 protein. Studies of the p53 gene have begun to provide insight into the molecular pathogenesis of gynecologic cancers.

Adenocarcinoma↗
PubMed1994

Determination of proliferation index with MIB-1 in advanced ovarian cancer using quantitative image analysis.

A new monoclonal antibody, MIB-1, reacts with the same epitope recognized by Ki-67. The authors investigated the feasibility of using image analysis to quantitate the MIB-1 staining (proliferation index [PI]) of epithelial ovarian cancers. The PI was determined in 50 advanced-stage primary ovarian cancers. Paraffin sections were immunostained with the MIB-1 monoclonal antibody, and the PI was calculated using a CAS 200 image analyzer. Among 36 stage III ovarian carcinomas, the median PI was 15.1%, compared with 18.9% in 14 stage IV cancers (P = .47). Based on exploratory methods, a cutoff point of 7% best dichotomized these patients into two prognostic groups. Of 39 patients whose cancers had a high MIB-1 expression (> or = 7%), the median survival was 16.5 months, which differed significantly (P = .01) from the median survival of 33.2 months observed in the 11 patients whose tumors demonstrated low MIB-1 expression (< 7%). Using MIB-1 as a binary variable, a strong correlation was found between overexpression of c-erbB-2 (2+ and 3+) and MIB-1 > or = 7% (P = .001). No relationship was found between PI and histologic grade. Further studies are warranted to investigate the relationship between MIB-1, PI expression, and other known clinicopathologic and genetic features of early- and late-stage ovarian cancer.

Antibodies, Monoclonal↗
PubMed1994

A novel gene encoding a B-box protein within the BRCA1 region at 17q21.1.

A novel cDNA clone was isolated using a polyclonal serum directed against partially purified ovarian carcinoma antigen CA125. The deduced peptide sequence lacked membrane protein characteristics expected for CA125 but encompassed a B-box/coiled coil motif present in many genes with transformation potential. The gene was mapped by fluorescence in situ hybridization within the minimum region known to contain the familial breast/ovarian carcinoma gene, BRCA1. YAC and cosmid clones were isolated and used to refine the location of this gene adjacent and proximal to the RNU2 locus. The exon structure of the gene was determined. Extensive SSCP and sequence analysis of over 100 tumour and normal DNAs from familial and sporadic breast cancers and sporadic ovarian cancers failed to detect mutations in the coding region of this gene.

Amino Acid Sequence↗
PubMed1994

Transforming growth factor beta 1 can induce CIP1/WAF1 expression independent of the p53 pathway in ovarian cancer cells.

Transforming growth factor beta (TGF beta) is an important regulator of cellular proliferation. In normal ovarian epithelial cells, TGF beta acts to inhibit growth. However, in ovarian cancer cell lines, this effect is usually lost. Although the regulatory pathway of TGF beta remains unclear, TGF beta-treated cells arrest late in G1. This inhibition appears to involve blocking of the cyclin-dependent kinase phosphorylation of the retinoblastoma protein. Recently, a general inhibitor of cyclin-dependent kinases, CIP1/WAF1/p21, was identified. Expression of CIP1 is positively regulated by binding of wild-type p53 to a consensus response element upstream of the CIP1 gene. Overexpression of the CIP1 protein causes growth suppression, analogous to TGF beta and wild-type p53. We have examined the induction of CIP1 by TGF beta 1 in ovarian cancer cell lines that have been previously characterized for their proliferative response to TGF beta 1. OVCA420, a cell line that is dramatically growth inhibited by TGF beta 1, significantly induced CIP1 expression in response to TGF beta 1. CIP1 induction was accompanied by a decrease in cdk2 kinase activity and cdk2 protein levels. In three other cell lines that respond weakly to TGF beta 1, CIP1 expression was not induced. To determine if TGF beta 1 induction occurs via p53, regulation of p53 RNA and protein was examined. No differences in p53 transcription, steady-state protein level, de novo synthesis, phosphorylation, or subcellular accumulation were noted. Furthermore, TGF beta 1 could not induce transcription from a consensus p53 DNA binding site in the TGF beta 1-response cell line.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1994

Mutation and overexpression of the p53 tumor suppressor gene frequently occurs in uterine and ovarian sarcomas.

OBJECTIVE: To determine the frequency of mutation and overexpression of the p53 tumor suppressor gene in female genital tract sarcomas. METHODS: Immunostaining for p53 was performed in frozen sections of 46 ovarian and uterine sarcomas. Single-stranded conformation polymorphism analysis of exons 4-9 of the p53 gene was performed in 33 sarcomas. We performed DNA sequencing of the p53 gene in 22 cases in which we found p53 protein overexpression and/or shifted bands on single-stranded conformation polymorphism analysis. RESULTS: Overexpression of p53 was seen in 27 of 46 sarcomas (59%), including 26 of 41 (63%) mixed mesodermal tumors, one of four (25%) leiomyosarcomas, and zero of one endometrial stromal sarcoma. Among the 33 sarcomas subjected to molecular analysis, 21 demonstrated mutations in the p53 gene (64%). Eighteen cancers had a single mutation, whereas three cases showed two mutations in the p53 gene. There was one mutation in exon 4, seven mutations in exon 5, three mutations in exon 6, six mutations in exon 7, six mutations in exon 8, and one mutation in exon 9. With the exception of one microdeletion, which predicted a truncated protein product, all of the mutations were missense point mutations. All but one of the point mutations resulted in changes in the predicted amino acid sequence. There were 18 transition mutations (75%), five transversions (21%), and one deletion (4%). CONCLUSIONS: Mutation of the p53 tumor suppressor gene, with resultant overexpression of p53 protein, frequently occurs in ovarian and uterine sarcomas. Because most of the mutations are transitions, p53 mutations in these cancers likely arise from spontaneous errors in DNA synthesis and repair rather than from exposure to carcinogens.

Adult↗
PubMed1993

Elevation of multiple serum markers in patients with stage I ovarian cancer.

BACKGROUND: The high overall mortality from ovarian cancer (> 60%) relates, in part, to delays in diagnosis. When ovarian cancer is detected in stage I (International Federation of Gynecology and Obstetrics staging), up to 90% of patients can be cured. Transvaginal sonography can detect early-stage disease with great sensitivity, but it is expensive and lacks specificity. Although serum marker assays could provide a less expensive and more convenient initial screening test, the sensitivity of assays varies. Measurement of serum CA 125 in conjunction with ultrasound screening as a second-line test confers high specificity but detects only about one half of early stage ovarian carcinomas. PURPOSE: The purpose of this retrospective study was to determine whether assays of multiple serum markers would improve sensitivity by detecting a higher percentage of stage I ovarian cancers than the CA 125 assay alone. METHODS: Using immunoradiometric assays, we measured preoperative serum levels of CA 125 tumor-associated antigen, macrophage colony-stimulating factor (M-CSF), and OVX1 in 46 patients with stage I ovarian cancer of different histologies and 237 patients with benign pelvic masses. We also assayed sera from 204 apparently healthy women who had participated in a screening trial and remained free from cancer at 1 year of followup. All specimens were obtained from cryopreserved aliquots. Marker levels were considered to be elevated when levels of CA 125 were greater than 30 U/mL, M-CSF levels were greater than 3.1 ng/mL, or OVX1 levels were greater than 12.1 U/mL. RESULTS: At least one of the serum markers was elevated in 98% of patients with stage I ovarian cancer; CA 125 levels were elevated in 67%. By the same criteria, 11% of healthy individuals and 51% of patients with benign pelvic masses had at least one elevated marker value. Thus, the sensitivity of the combination of assays for the three serum markers was significantly greater than the sensitivity of the CA 125 assay (P < .0005) and specificity was moderate. CONCLUSION: A panel of these three tumor markers can identify early-stage ovarian cancer with extremely high sensitivity and moderate specificity. IMPLICATIONS: Elevation of one or more serum markers should be evaluated further as an indication for transvaginal sonography in apparently healthy women. Such a strategy might substantially reduce the expense and improve the specificity of screening compared to the use of ultrasound alone. Prospective studies with a large cohort of patients at high risk for ovarian cancer will be required to confirm these findings.

Antigens, Neoplasm↗
PubMed1993

Spectrum of mutation and frequency of allelic deletion of the p53 gene in ovarian cancer.

BACKGROUND: The p53 gene encodes a nuclear phosphoprotein present in low levels in normal human cells. The wild-type form of this protein functions to restrain inappropriate cellular proliferation. Approximately one half of human epithelial ovarian cancers have mutations in the p53 gene and overexpress the mutant protein product. Deletion of one allele of the p53 gene also frequently occurs in these cancers. PURPOSE: We sought to define the spectrum of mutations in the p53 gene in epithelial ovarian cancer with respect to both the specific codons involved and the type of mutations observed. We also examined the frequency of allelic deletion of the p53 gene in cancers containing p53 gene mutations. METHODS: Tissue samples from the epithelial ovarian cancers of 62 patients were obtained during initial laparotomy. Histologic examination was done to ensure that the experimental samples used in this study contained more than 75% cancer cells. Total RNA was extracted from these samples and separately from matched control noncancerous regions of the surgical specimen or white blood cells. The purified RNAs were reverse transcribed to generate cDNA copies of exons 4-10 of the p53 gene. Two rounds of polymerase chain reaction (PCR) were conducted to produce enough template for DNA sequence analysis of the regions of interest within the p53 gene. Dideoxy sequencing of at least two independent productions of each amplified DNA template was done to confirm the validity of the mutations found. Allelic deletions were identified by PCR and gel electrophoretic techniques to examine three polymorphisms within the p53 gene in cancer-normal DNA pairs. RESULTS: We identified 45 mutations in exons 5-8 of the p53 gene, where mutations frequently have been found in other cancer types. An additional mutation was identified in exon 4. Overall, 72% of the mutations were transitions, 24% transversions, and 4% microdeletions. Allelic deletion of the other p53 allele was seen in 67% of ovarian cancers in which a p53 mutation was present. Germ-line p53 mutations were not found in any patients whose cancers had p53 mutations. CONCLUSIONS AND IMPLICATIONS: Like p53 mutations in other types of human cancers, those in epithelial ovarian cancers are diverse and occur frequently in exons 5-8. The predominance of transition mutations suggests that p53 mutations in ovarian cancer arise because of spontaneous errors in DNA synthesis and repair rather than the direct interaction of carcinogens with DNA. These molecular data are consistent with data from epidemiologic studies that have failed to demonstrate a convincing relationship between exposure to environmental carcinogens and the development of ovarian cancer.

Alleles↗
PubMed1993

Serum levels of HER-2 neu (C-erbB-2) correlate with overexpression of p185neu in human ovarian cancer.

BACKGROUND: The HER-2 neu (c-erbB-2) oncogene product p185neu is expressed by most ovarian cancers and overexpressed in approximately 30%. METHODS: Sera from patients with ovarian cancer were evaluated for neu antigen using an enzyme-linked immunoassay and for CA 125 antigen by radioimmunoassay. Tissue levels of neu from the same patients were determined by immunohistochemical staining with anti-neu monoclonal antibody. RESULTS: Elevated levels (> 2050 human neu unit [HNU]/ml) of circulating neu determinants have been detected in sera from 15% of 48 patients. Of 45 patients for whom tumor tissue had been cryopreserved, overexpression of neu was found in 17 by immunohistochemical analysis; of these 17, serum neu levels were elevated in 5 (29%). Among the 28 patients with normal to moderate tissue expression of neu, only 2 (7%) had elevated serum neu levels. Thus, elevated serum neu levels predicted tissue overexpression with a specificity of 93%. Serum neu levels were not related to serum levels of CA 125. CONCLUSION: Serum and tissue levels of neu correlate in patients with epithelial ovarian cancer.

Adult↗
PubMed1993

Tumor necrosis factor alpha as an autocrine and paracrine growth factor for ovarian cancer: monokine induction of tumor cell proliferation and tumor necrosis factor alpha expression.

Ovarian tumor cells produce macrophage colony stimulating factor, a potent chemoattractant for monocytes. Monocytes and macrophages produce tumor necrosis factor alpha (TNF-alpha) and interleukin 1 alpha or interleukin 1 beta (IL-1 beta) that can stimulate ovarian tumor cell growth. The present study has explored whether paracrine stimulation by monocyte derived cytokines might induce autocrine growth stimulation of normal and malignant ovarian epithelial cells. Endogenous expression of TNF-alpha mRNA was detected in ascites ovarian cancer cells isolated directly from patients, but not in established cultures of normal or malignant ovarian epithelial cells. When ascites tumor cells were cultured for 7 days, TNF-alpha expression ceased but could be reinduced by treatment with TNF-alpha or IL-1 beta. Ascites fluid contained concentrations of the cytokines that could mediate these effects. Similarly, treatment of normal or malignant ovarian epithelial cells with purified recombinant IL-1 beta or TNF-alpha induced transcription of TNF-alpha mRNA within 1 h. TNF-alpha protein could be detected by enzyme-linked immunosorbent assay in conditioned medium from IL-1 beta treated ovarian cancer cells. [3H]thymidine incorporation by normal or malignant ovarian epithelial cells was stimulated by a 24-h incubation with IL-1 beta or TNF-alpha. Stimulation of proliferation by IL-1 beta could be partially blocked by an antibody against TNF-alpha or by soluble TNF-alpha-receptor. Thus, TNF-alpha may function as both an autocrine and a paracrine growth factor in ovarian cancer.

Animals↗
PubMed1993

Cell growth regulation in epithelial ovarian cancer.

BACKGROUND: As in the case of other epithelial neoplasms, most ovarian cancers arise from single clones of cells that have undergone multiple genetic alterations. A comparison of normal and malignant ovarian epithelium has identified several differences in growth regulation by peptide growth factors, protooncogenes, and tumor suppressor genes. METHODS: Recent articles and abstracts have been reviewed. RESULTS: The malignant ovarian epithelial phenotype has been associated with (1) autocrine growth stimulation by transforming growth factor-alpha, (2) loss of autocrine growth inhibition by transforming growth factor-beta, (3) mutation or amplification of ras in 2-12% of cases, (4) amplification of myc in 23% of specimens, (5) expression of fms in 56% of cases with potential autocrine stimulation by macrophage colony stimulating factor, (6) paracrine stimulation by macrophage products including interleukin-1, interleukin-6 and tumor necrosis factor, (7) overexpression of c-erbB-2 (HER-2/neu) in 30% of cases, and (8) mutation with consequent overexpression of p53 in 50% of advanced ovarian cancers. A poor clinical prognosis is associated with expression or overexpression of the epidermal growth factor receptor, fms, and HER-2/neu. Antibodies against the extracellular domain of the HER-2/neu gene product p185 inhibit the growth of tumor cells that overexpress HER-2/neu and are associated with marked decreases in diacylglycerol levels. The intracellular kinase domain is required for growth inhibition. Antibodies that inhibit growth stimulate phosphorylation of intracellular substrates. Ricin A chain monoclonal antibody conjugates that react with p185 also inhibit the growth of tumor cells that overexpress p185. The intracellular kinase region is not required for immunotoxin-mediated killing. Coexpression of HER-2/neu and the epidermal growth factor receptor has been observed in 65% of epithelial ovarian cancers and in a limited number of normal tissue from a fraction of donors. CONCLUSIONS: Multiple alterations in growth factors, protooncogenes and growth factors have been detected in different epithelial ovarian cancers. Inappropriate signalling from receptor tyrosine kinases may be particularly important for ovarian oncogenesis. Drugs that affect tyrosine kinase and phosphatase activity deserve attention as potential therapeutic agents for ovarian cancer. The extracellular domains of the HER-2/neu gene product p185 and the epidermal growth factor receptor may provide useful targets for serotherapy.

Carcinoma↗
PubMed1993

Antibody-induced growth inhibition is mediated through immunochemically and functionally distinct epitopes on the extracellular domain of the c-erbB-2 (HER-2/neu) gene product p185.

Over-expression of the c-erbB-2 (HER-2/neu) gene product p185 occurs in 30% of breast and ovarian cancers. The p185 protein might serve as a target for serotherapy in that antibodies against different epitopes on the extracellular domain of p185 can inhibit growth of tumor cells in the absence of cellular or humoral effector mechanisms. To define epitopes of functional relevance, 11 monoclonal antibodies (MAbs) were evaluated for their ability to bind to the extracellular domain of p185. Results of competition studies with 125I-labeled and non-labeled antibodies indicated that 10 of 11 epitopes were grouped in a linear array. Antibodies against 7 epitopes inhibited anchorage-independent growth and antibodies against 2 of these epitopes also inhibited anchorage-dependent growth of SKBr3 breast-cancer cells that over-expressed p185. Treatment with antibodies exerted cytotoxic rather than cytostatic effects. When antibodies were used in combination, additive or supra-additive inhibition of anchorage-independent and anchorage-dependent growth was observed between pairs of antibodies. Growth inhibition did not relate to the affinity of the antibody or its isotype. Two antibodies that inhibited both anchorage-dependent and anchorage-independent growth also blocked binding of the HER-2/neu ligand, whereas 5 antibodies that inhibited only anchorage-independent growth had no effect on ligand binding. Inhibition of cell growth did not correlate with internalization of p185 or down-regulation of p185 on the cell surface. Fab fragments of active antibodies could also inhibit anchorage-independent growth of SKBr3. Thus, murine MAbs and their fragments recognized both immunochemically distinct and functionally distinct epitopes on the p185 molecule. Whereas inhibition of anchorage-dependent growth correlated with the ability of antibodies to block ligand binding, inhibition of anchorage-independent growth did not correlate with effects on ligand binding, internalization, cell-surface expression or cross-linking of p185.

Antibodies, Monoclonal↗
PubMed1993

Growth regulation and transformation of ovarian epithelium.

The discovery of peptide growth factors and cancer-causing genes (oncogenes and tumor-suppressor genes) has provided us with the exciting opportunity to begin to understand the molecular pathology of human ovarian cancer. Activation of several genes, including HER-2/neu, myc, ras, and p53 have been described in some ovarian cancers. In addition, some protooncogenes such as the epidermal growth factor receptor (erbB) and the M-CSF receptor (fms) are expressed along with the respective ligands (peptide growth factors) in some ovarian cancers. Although the studies reviewed in this paper represent a promising beginning, we remain far from a comprehensive understanding of growth regulation and transformation of human ovarian epithelium.

Cell Division↗