Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of molecular markers predicting the response to cytotoxic chemotherapy is not established. A potential predictive factor, topoisomerase IIalpha, is a target for certain cytotoxic drugs, and its concentration has been shown to correlate with chemosensitivity in vitro. We evaluated expression of topo IIalpha immunohistochemically in 230 breast cancer samples and studied its association with known clinicopathological factors and factors previously shown to predict response to cytotoxic drugs. Topo IIalpha protein expression was found in 0.6 to 39.4% (10.6 +/- 7.9%, mean +/- SD) of breast carcinoma cells, whereas expression was undetectable in nonmalignant breast epithelium. Topo IIalpha protein expression correlated well with semi-quantitative mRNA in situ hybridization (P = 0.007). A significant association was found between the proportion of topo-IIalpha-positive cells and low estrogen and progesterone receptor content (P<0.0001), high grade (P<0.0001), DNA aneuploidy (P=0.003), and c-erbB-2 oncoprotein overexpression (P<0.0001). Topo IIalpha expression was not associated with clinical variables, such as age of the patient, primary tumor size, or axillary nodal status. A highly significant linear correlation was found between topo IIalpha and tumor proliferation rate (S-phase fraction, r=0.46; P<0.0001). Because hormone receptors, grade, and ploidy are associated with tumor proliferation rate, topo IIalpha expression was adjusted for S-phase fraction to reveal the proliferation-independent clinopathological associations. According to the analysis of co-variance, only aneuploidy (P=0.0003) and c-erb-2 overexpression (P=0.01) were associated with proliferation-adjusted expression of topo IIalpha. In conclusion, the close association of Topo IIalpha with other potential predictive factors (tumor proliferation rate, c-erbB-2 oncoprotein) suggests that topo IIalpha, having a defined role as a target for cytotoxic drugs, may be a valuable predictor of response to chemotherapy.
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PMID:Expression of topoisomerase IIalpha is associated with rapid cell proliferation, aneuploidy, and c-erbB2 overexpression in breast cancer. 866 91

The erbB-2 receptor plays an important role in the prognosis of breast cancer and is expressed at high levels in nearly 30% of tumors in breast cancer patients. While evidence accumulates to support the relationship between erbB-2 overexpression and poor overall survival in human breast cancer, understanding of the biological consequence(s) of erbB-2 overexpression remains elusive. The discovery of heregulin has allowed us to identify a number of related but distinct biological endpoints which appear responsive to signal transduction through the erbB-2/4 receptor. These endpoints of growth, invasiveness, and differentiation have clear implications for the emergence, maintenance, and/or control of malignancy, and represent established endpoints in the assessment of malignant progression in human breast cancer. Preliminary studies in vitro have shown that heregulin induces a biphasic growth effect on cells with erbB-2 overexpression. Interestingly, we observed that expression of heregulin correlates with a more aggressive/invasive, vimentin-positive phenotype in breast cancer cells lines. Therefore, we have postulated that heregulin is involved in breast cancer tumor progression. We have shown that heregulin induces in vitro chemoinvasion and chemotaxis of breast cancer cells as well as growth in an anchorage dependent and independent manner. Interestingly, a heregulin neutralizing antibody inhibits chemotaxis and results in cell growth inhibition and blockade of the invasive phenotype. Strikingly, genetically engineered cells which constitutively express heregulin demonstrate critical phenotypic changes that are associated with a more aggressive phenotype. Specifically, these cells are no longer dependent on estrogen for growth and are resistant to tamoxifen in vitro and in vivo, and moreover these cells metastasize to lymph nodes in athymic nude mice. These tumors appear to have lost bcl-2 expression as compared with the control tumors. In addition, presumably by activation/regulation of topoisomerase II, the heregulin-transfected cells become exquisitely sensitive to doxorubicin and VP-16. Clearly, mechanistic aspects of the erbB-2/4 and heregulin interaction need to be understood from a therapeutic standpoint which could provide additional insights into synergistic treatments for certain patients, or improve treatment regimens for a large number of women. The study of heregulin and its co-expression with erbB-2/4 receptor and the assessment of its involvement in the progression from the in situ stage of breast tumors to the invasive one will additionally increase the relevance of heregulin as a prognostic/diagnostic factor. We believe that our studies provide new insights into breast cancer diagnosis, prognosis, and treatment.
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PMID:The significance of heregulin in breast cancer tumor progression and drug resistance. 882 23

HER2 (erbB-2) proto-oncogene amplification and/or overexpression correlate with poor prognosis in many malignancies. The precise biological role of this oncogenic signaling pathway (which also involves the HER4 gene) in breast cancer is unclear. One property conferred by this oncogene relates to response to drug therapy. Clinical studies support an association between HER2 overexpression and resistance to alkylating agents (cisplatinum and cyclophosphamide). Data from the Cancer and Leukemia Group B 8869/8541 study indicate enhanced dose responsiveness to doxorubicin (Adriamycin) in patients who overexpress the HER2 receptor. Heregulin beta-2, a naturally occurring ligand that activates the HER2 receptor by inducing its heterodimerization with the HER4 receptor, has recently been cloned. The ability of this ligand to phosphorylate the HER2 receptor exogenously allows us to study the effect of HER2 activation on cancer cell behavior. To study the relationship between chemotherapy response and activation of HER2, MCF-7 cells expressing biologically active heregulin were assessed for response to doxorubicin and etoposide, both of which are topoisomerase IIalpha (topo IIalpha) inhibitors. Several clones show markedly increased sensitivity to these drugs. In addition, the same wild-type MCF-7 cells transfected with heregulin beta-2 under the control of an inducible promoter also show this dose-response relationship to doxorubicin after the expression of heregulin beta-2 is activated by zinc. The modulation of topo IIalpha was studied in the cell lines transfected with heregulin. topo IIalpha mRNA and protein (total protein and enzymatic decatenating activity) were found to be up-regulated in heregulin beta-2-transfected cells. Moreover, topo IIalpha promoter activity was also modestly increased in heregulin beta-2-transfected cells. Because up-regulation of topo IIalpha in vitro and in clinical specimens is associated with increased response to doxorubicin (presumptively by an increase in drug substrate), this may be the mechanism of the increased sensitivity to doxorubicin seen in heregulin beta-2-transfected cells. This implies that activation of HER2 or one of the other members of the receptor family may increase sensitivity to doxorubicin by up-regulation of topo IIalpha. This finding suggests the use of receptor/ligand expression to direct patient-specific therapeutic choices (e.g., doxorubicin versus alkylator-based regimens) and the use of biological agents (such as heregulin) in combination with certain chemotherapeutic agents to enhance response to treatment in breast cancer patients.
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PMID:Induction of sensitivity to doxorubicin and etoposide by transfection of MCF-7 breast cancer cells with heregulin beta-2. 956 96

Previous studies have demonstrated a synergistic interaction between rhuMAb HER2 and the cytotoxic drug cisplatin in human breast and ovarian cancer cells. To define the nature of the interaction between rhuMAb HER2 and other classes of cytotoxic drugs, we applied multiple drug effect/combination index (CI) isobologram analysis to a variety of chemotherapeutic drug/rhuMAb HER2 combinations in vitro. Synergistic interactions at clinically relevant drug concentrations were observed for rhuMAb HER2 in combination with cisplatin (CI=0.48, P=0.003), thiotepa (CI=0.67, P=0.0008), and etoposide (CI=0.54, P=0.0003). Additive cytotoxic effects were observed with rhuMAb HER2 plus doxorubicin (CI=1.16, P=0.13), paclitaxel (CI=0.91, P=0.21), methotrexate (CI=1.15, P=0.28), and vinblastine (CI=1.09, P=0.26). One drug, 5-fluorouracil, was found to be antagonistic with rhuMAb HER2 in vitro (CI=2.87, P=0.0001). In vivo drug/rhuMAb HER2 studies were conducted with HER-2/neu-transfected, MCF7 human breast cancer xenografts in athymic mice. Combinations of rhuMAb HER2 plus cyclophosphamide, doxorubicin, paclitaxel, methotrexate, etoposide, and vinblastine in vivo resulted in a significant reduction in xenograft volume compared to chemotherapy alone (P<0.05). Xenografts treated with rhuMAb HER2 plus 5-fluorouracil were not significantly different from 5-fluorouracil alone controls consistent with the subadditive effects observed with this combination in vitro. The synergistic interaction of rhuMAb HER2 with alkylating agents, platinum analogs and topoisomerase II inhibitors, as well as the additive interaction with taxanes, anthracyclines and some antimetabolites in HER-2/neu-overexpressing breast cancer cells demonstrates that these are rational combinations to test in human clinical trials.
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PMID:Inhibitory effects of combinations of HER-2/neu antibody and chemotherapeutic agents used for treatment of human breast cancers. 1032 70

Overexpression of the c-erbB-2 (HER-2/neu) oncogene, which encodes a transmembrane receptor tyrosine kinase, has been shown to be associated with poor prognosis in ovarian and breast cancer. Recent studies indicate that c-erbB-2 may also be involved in determining the chemosensitivity of human cancers. In the present study, we examined the role of c-erbB-2 for chemoresistance in ovarian cancer. Overexpression of c-erbB-2 mRNA in tumor tissue was associated with a shorter survival of patients with primary ovarian cancer (P = 0.0001; n = 77) and was an independent prognostic factor in the proportional-hazard model adjusted for International Federation of Gynecologists and Obstetricians stage, residual disease, chemotherapy, and age (P = 0.035). A significant association between expression of c-erbB-2 mRNA and survival was obtained for the subgroup of patients who received a standard chemotherapy with carboplatin or cisplatin and cyclophosphamide (P = 0.0003), whereas only a nonsignificant trend was observed for patients who did not receive a standard chemotherapy (P = 0.124). In addition, the application of a standard chemotherapy improved the survival of patients with relatively low c-erbB-2 expression (P = 0.013) but not of patients with overexpression of c-erbB-2 (P = 0.359). Expression of c-erbB-2 mRNA correlated with expression of topoisomerase IIalpha mRNA determined by a reverse semiquantitative PCR technique (P = 0.009), whereas expression of c-erbB-2 and topoisomerase IIbeta mRNA did not correlate (P = 0.221). To examine the hypothesis that coamplified and/or coregulated topoisomerase IIalpha contributes to the resistance of c-erbB-2-overexpressing carcinomas, we established a chemosensitivity assay using primary cells from an ovarian carcinoma that overexpressed both c-erbB-2 and topoisomerase IIalpha. The combination of carboplatin with nontoxic concentrations of the topoisomerase II inhibitors etoposide or novobiocin enhanced the toxicity of carboplatin. In contrast, the tyrosine kinase inhibitor emodin exhibited no chemosensitizing effect in cells of this individual carcinoma. In conclusion, overexpression of c-erbB-2 was associated with poor prognosis and poor response to chemotherapy. The data suggest that topoisomerase IIlalpha, which correlates with c-erbB-2 expression, contributes to the resistance of c-erbB-2-overexpressing carcinomas.
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PMID:Contribution of c-erbB-2 and topoisomerase IIalpha to chemoresistance in ovarian cancer. 1039 67

We have tested the sensitivity of human MCF-10A mammary epithelial cells and of their transformed derivatives overexpressing an activated c-Ha-ras gene (MCF-10A Ha-ras cells), the c-erbB-2 gene (MCF-10A c-erbB-2 cells) or both genes (MCF-10A HE cells) to different cytotoxic drugs. As compared with parental MCF-10A cells, the transformed cells exhibited an increased sensitivity to topoisomerase I- and topoisomerase II-inhibitors, and to platinum-derivatives with a 2- to 10-fold reduction in IC(50) values. A remarkable difference in sensitivity was observed following treatment with taxanes. While MCF-10A Ha-ras cells showed an increased sensitivity, MCF-10A c-erbB-2 and MCF-10A HE cells exhibited a relative resistance to taxol and taxotere, with an approximately 3.5- to 6.5-fold higher IC(50) as compared with MCF-10A cells suggesting that c-erbB-2 overexpression has a dominant effect compared with an activated c-Ha-ras gene. The type I cAMP-dependent protein kinase (PKAI) is overexpressed in cancer cells. Inhibition of PKAI by antisense oligonucleotides targeting its RIalpha regulatory subunit results in cancer cell growth inhibition. To evaluate the effect of blocking PKAI on MCF-10A cell sensitivity to taxanes, we treated these cells with taxol or taxotere in combination with a PKAI antisense oligonucleotide. Treatment with this agent, but not with a control scramble sequence, was able to overcome the effect of c-erbB-2 overexpression on MCF-10A cell sensitivity to taxol and taxotere, with a 20- to 40-fold shift in the IC(50) values for the 2 drugs.
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PMID:Resistance to taxanes is induced by c-erbB-2 overexpression in human MCF-10A mammary epithelial cells and is blocked by combined treatment with an antisense oligonucleotide targeting type I protein kinase A. 1069 53

DNA topoisomerase I (topo I) is the molecular target of the camptothecin group of anticancer drugs. These drugs are S-phase specific and require elevated topo I for tumor cell killing. To determine whether increased topo I expression occurs in testicular seminomas, 20 cases of testicular seminoma were retrieved from the surgical pathology files at the University of Utah Health Sciences Center and stained with an antibody that recognizes topo I in paraffin embedded human tissue sections. Topo I elevation was observed in 30% (6/20) of the seminomas. Because the response to topo I targeted drugs requires cell proliferation, the proliferative index of the seminomas was determined by immunohistochemical staining for DNA topoisomerase II-alpha (topo II-alpha) a new marker of cell proliferation. AU seminomas had easily detectable topo II-alpha. The average topo II-alpha index of the 20 cases was 52.1 +/- 15.3. Seminomas with elevated topo I had an average topo II-alpha proliferative index of 60.8 +/- 17.5 and seminomas with normal topo I expression had a topo II-alpha proliferative index of 48.4 +/- 13.2. This is significantly different at the 0.05% confidence level. Focal expression of CD30 was seen in 60% (12/20) of the neoplasms. None of the cases showed positive staining for CD15 and c-erbB-2. Our results suggest that chemotherapeutic protocols involving topoisomerase targeting drugs might be useful against testicular seminomas.
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PMID:Expression of DNA toposiomerase I and DNA topoisomerase II-alpha in testicular seminomas. 1087 53

Ductal carcinoma in situ (DCIS) of the breast, a precursor lesion of invasive breast cancer, is a heterogeneous disease in terms of histomorphologic features and biologic behavior. Our aim was to assess the proliferative activity, expressed as topoisomerase IIalpha (Topo IIalpha) immunoreactivity and c-erbB-2 expression in relation to morphologic features and architectural pattern of DCIS. The study included 26 DCIS, which were reclassified according to the recommendations of Consensus Conference. Topo-IIalpha and c-erbB-2 immunoreactivity were detected on paraffin sections. Topo IIalpha was consistently negative in normal ductal epithelium. Topo IIalpha-labeling index (Topo IIalpha-LI) was 0.7+/-0.6% for grade I, 4.3+/-3.9% for grade II, and 13.4+/-8.9 for grade III lesions (P<.01). For mixed nuclear grade DCIS, Topo IIalpha-LI was 6.8+/-4.8. There was no difference in Topo IIalpha-LI between different architectural patterns in low- and intermediate-grade lesions. In high nuclear grade DCIS, there was a progressive increase in Topo IIalpha-LI from solid toward cribriform and comedo-type DCIS. Positive c-erbB-2 immunoreactivity was found in 46% of DCIS, being highest in DCIS with high nuclear grade (78%) and in lesions with extensive necrosis. Topo IIalpha-LI was significantly higher in c-erbB-2-positive lesions (Topo IIalpha-LI- 12.4+/-8.5) as compared with negative lesions (Topo IIalpha-LI- 3.9+/-4.5, P<. 0001). Overexpression of c-erbB-2 and Topo IIalpha is associated with poorly differentiated lesions. Proliferative activity in individual ducts of DCIS depended primarily on the nuclear grade and was independent of architectural patterns of individual ducts in architecturally heterogeneous lesions.
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PMID:Topoisomerase IIalpha expression in ductal carcinoma in situ of the breast: a preliminary study. 1107 Jan 18

Recurrent respiratory papillomatosis (RRP) has a juvenile aggressive form and an adult more indolent form. Most cases of RRP are cytologically benign; however, some undergo malignant transformation. At present, there are no known markers that help identify patients at risk for aggressive disease. We investigated by immunohistochemistry expressions of topoisomerase alpha II, MIB-1, p53, p21, E-cadherin, retinoblastoma (RB) gene protein product, HER-2/neu, and steroid hormone receptors in a case of juvenile respiratory papillomatosis with malignant transformation to determine whether these markers are associated with malignant transformation. Histologic examination of the pulmonary lobectomy specimen revealed well-differentiated squamous carcinoma and invasive papillomatosis. Increased staining was found in areas of invasive papillomatosis for topoisomerase alpha II, p53, and MIB-1, with highest labeling indices in areas of squamous carcinoma. Staining intensity for RB gene protein product showed gradual decline from benign papilloma (3+) and invasive papillomatosis (2+) to squamous carcinoma (0-1+). Expression of p21 was similar in benign papilloma and invasive papillomatosis but showed reduction in squamous carcinoma. Expressions of E-cadherin, HER-2/neu, and steroid hormone receptors did not appear to correlate with biologic behavior. Increased topoisomerase alpha II and p53 expression along with reduced RB gene protein product and p21 expression may serve as markers of transformation to invasive papillomatosis and squamous carcinoma.
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PMID:Topoisomerase alpha II, retinoblastoma gene product, and p53: potential relationships with aggressive behavior and malignant transformation in recurrent respiratory papillomatosis. 1127 21

Amplification of the HER-2/neu oncogene and amplification of the topoisomerase IIalpha gene are important determinators of the response to chemotherapy in advanced breast cancer. Assays of these genes are usually carried out using primary tumor samples, because biopsies from metastatic lesions are not usually taken. We studied the concordance of Her-2/neu and topoisomerase IIalpha amplification in primary breast tumors and their metastases by immunostaining and DNA in situ hybridization. HER-2/neu amplification, present in 28% of the primary tumors (n = 46), was always associated with amplification in its metastasis. Conversely, no metastases with HER-2/neu amplification were seen without amplification in the primary tumor. Topoisomerase IIalpha gene copy status (amplification/deletion/unaltered) remained generally unchanged in HER-2/neu-positive tumors, but in three cases, the predominant cell population in metastatic tissue was present only as a subpopulation in the primary tumor. We conclude that amplification of HER-2/neu measured in primary tumor reflects the status of metastases. Minor discrepancies between primary and metastatic tumors in topoisomerase IIalpha gene copy status may reflect evolvement of the amplicon structure in successive cell divisions.
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PMID:Amplification of HER-2/neu and topoisomerase IIalpha in primary and metastatic breast cancer. 1145 72


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