Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Kahalalide F (KF) is a novel antitumor drug of marine origin under clinical investigation. KF showed a potent cytotoxic activity against a panel of human prostate and breast cancer cell lines, with IC(50) ranging from 0.07 micro M (PC3) to 0.28 micro M (DU145, LNCaP, SKBR-3, BT474, MCF7). Importantly, nontumor human cells (MCF10A, HUVEC, HMEC-1, IMR90) were 5-40 times less sensitive to the drug (IC(50) = 1.6-3.1 micro M). KF cytotoxicity did not correlate with the expression level of the multidrug resistance MDR1 and of the tyrosine kinase HER2/NEU, and only slightly by the anti-apoptotic BCL-2 protein. KF action was triggered rapidly by short pulse treatments (15 min caused 50% maximum cytotoxicity). Neither a general caspase inhibitor (Z-VAD-fmk) nor transcription or translation inhibitors (actinomycin D, cycloheximide) blocked KF action. Flow cytometry analysis revealed that KF induced neither cell-cycle arrest nor apoptotic hypodiploid peak. Using mitochondrial (JC-1)- and lysosomal (LysoTracker Green, Acridine Orange)-specific fluorophores, we detected loss of mitochondrial membrane potential and of lysosomal integrity following KF treatment. Confocal laser and electron microscopy revealed that KF-treated cells underwent a series of profound alterations including severe cytoplasmic swelling and vacuolization, dilation and vesiculation of the endoplasmic reticulum, mitochondrial damage, and plasma membrane rupture. In contrast, the cell nucleus showed irregular clumping of chromatin into small, condensed masses, while chromatin disappeared from other nuclear domains, but the nuclear envelope was preserved and no DNA degradation was detected. Together, these data indicate that KF induces cell death via oncosis preferentially in tumor cells.
Mol Cancer Ther 2003 Sep
PMID:Kahalalide F, a new marine-derived compound, induces oncosis in human prostate and breast cancer cells. 1455 5

Immunohistochemical double staining with estrogen receptor (ER) and epidermal growth factor receptor 2 (HER2) was conducted in tissue sample of 125 women with invasive breast cancer. The age at the time of surgery ranged from 28 to 82 years. The tumor size was 2 cm or less in 42 patients and larger than 2 cm in 83. Axillary lymph node status was positive in 53 patients and negative in 72. Estrogen receptor (ER) which was measured using enzyme immunoassay (EIA) was positive in 67 patients, negative in 50 and unknown in 8. Of the 125 patients evaluated, 83 (66.4%) were immunohistochemically positive for ER. ER by immunohistochemistry (IHC) (ER-IHC) was significantly (p<0.01) correlated with ER by EIA (ER-EIA). ER-EIA values in ER-IHC scores were 1.4 fmol/mg protein in score 0, 0.0 in score 1, 19.0 in score 3, 21.2 in score 4, 12.2 in score 5, 17.6 in score 6, 30.0 in score 7 and 114.8 in score 8. ER-EIA values in ER-IHC-score 8 were significantly higher than in scores 0, 2, 3, 4, 5, 6 and 7. Of the 125 patients, 35 (28%) were immunohistologically positive for HER2. HER2 expression was inversely correlated with ER expression. When evaluated even in ER-positive patients, HER2 overexpression was associated with lower ER levels. In this study, we conducted immunohistochemical double staining with ER and HER2, and demonstrated that low ER levels might be one factor in the relative resistance of HER2-positive and ER-positive tumors to hormonal therapy.
Int J Mol Med 2003 Dec
PMID:Immunohistochemical double staining with estrogen receptor and HER2 on primary breast cancer. 1461 57

HER2, a member of the human epidermal growth factor (EGF) receptor family, not only plays important roles in the progression of breast cancer tumorigenesis and metastasis, but may protect cancer cells from conventional cytotoxic therapies as well. In the current study, we evaluated the effect of targeting HER2 on radiosensitization of human breast cancer cells. Using six breast cancer cell lines with various levels of HER2 (BT474, SKBR3, MDA453, MCF7, ZR75B, and MDA468), we found that trastuzumab (Herceptin), a humanized monoclonal antibody that may inhibit breast cancer cell proliferation but does not induce apoptosis when used alone, enhanced radiation-induced apoptosis of the cells in a HER2 level-dependent manner. We furthered this study in MCF7 cells transfected for high levels of HER2 (MCF7HER2). Compared with parental or control vector-transfected MCF7 cells, MCF7HER2 cells showed increased phosphorylation of at least two important HER2 downstream molecules, protein kinase B/Akt and mitogen-activated protein kinase (MAPK), and increased resistance to radiotherapy, as shown by reduced induction of apoptosis and increased cell clonogenic survival after radiation. Exposure of the cells to trastuzumab down-regulated the levels of HER2 and reduced phosphorylation levels of Akt and MAPK in MCF7HER2 cells, and sensitized these cells to radiotherapy. When specific inhibitors of the phosphatidylinositol 3-kinase (PI3-K) and MAPK kinase (MEK) pathways were used, we found that exposure of MCF7HER2 cells to the PI3-K inhibitor LY294002 inhibited Akt phosphorylation and radiosensitized the cells, whereas the radiosensitization effect by the MEK inhibitor PD98059 was relatively weaker, albeit the phosphorylation of MAPK was reduced by PD98059 treatment. Our results indicate that the PI3-K pathway might be the major pathway for trastuzumab-mediated radiosensitization of breast cancer cells.
Mol Cancer Ther 2003 Nov
PMID:Sensitization of breast cancer cells to radiation by trastuzumab. 1461 84

Adjuvant endocrine therapy reduces the risk of relapse and death from early stage hormone receptor positive breast cancer. However, tamoxifen is only partially effective because of the development of tumor resistance. Aromatase inhibitors (letrozole, anastrozole and exemestane) are also prone to the development of resistance but the pharmacologic action (estrogen deprivation) is distinct and so different mechanisms may be responsible. The problem of endocrine resistance can be directly studied in patients by examining the relationship between predictive tumor biomarkers and clinical outcome. In an example of a prospectively planned biomarker study, tumor samples were examined from a randomized trial of neoadjuvant endocrine treatment in which letrozole proved more effective than tamoxifen in terms of the rate of breast conservation and tumor regression. Interestingly letrozole was more effective at all levels of ER expression and was particularly more efficacious than tamoxifen for tumors that expressed HER1 and/or HER2 (with ER). This suggests that HER1/2 predicts primary tamoxifen resistance and relative sensitivity to potent estrogen deprivation, perhaps because HER1/2 signaling promotes the partial agonist effects of tamoxifen. A Phase 2 study of neoadjuvant letrozole is now underway to focus on gene expression profiling as a mechanism to further investigate the transcriptional programs that underlie resistance and sensitivity to estrogen deprivation. Expression profiles taken at baseline and after 1 month of therapy reveal dramatic reductions in the expression from genes responsible for DNA replication and synthesis, cell cycle progression, suppression of apoptosis and tissue invasion. When enough profiles have been generated it should be possible to detect complex interaction patterns that correctly reclassify ER+ disease into treatment responsive and resistant categories with high probability.
J Steroid Biochem Mol Biol 2003 Sep
PMID:Neoadjuvant comparisons of aromatase inhibitors and tamoxifen: pretreatment determinants of response and on-treatment effect. 1462 25

Here, we report that a significant increase in recombinant fusion antibody expression can be accomplished by adjusting the nucleotide sequence to conform to certain codon pairing rules. We investigated the expression of a protein in which a single chain Fv specific for HER2/neu with VH and VL joined by a flexible (GGGGS)3 linker was linked to the CH3 of a human anti-rat transferrin receptor IgG3 heavy chain with the same flexible (GGGGS)3 linker. In initial experiments we failed to achieve significant expression of this protein. However, when we made a single nucleotide change in each (GGGGS)3 linker we were able to achieve expression The change of one nucleotide within each linker did not alter either the amino acid sequence or the frequency score of these codon triplets' usage in mammalian cells. Instead they removed two codon pairs predicted to be detrimental to expression. In a transient transfection assay we find that this change results in an over 30-fold increase in expression that is not the result of an increase in the level of accumulated mRNA. In addition, the changes made it possible to isolate stably transfected mammalian cell clones producing high levels of fusion protein, which had not been possible using the original gene.
Mol Immunol 2004 Jan
PMID:Optimization of codon pair use within the (GGGGS)3 linker sequence results in enhanced protein expression. 1464 97

Although formalin-based fixatives are used in pathologic laboratories, there is no strictly standardized fixation protocol in Japan. To examine interlaboratory variation caused by different conditions of fixation in the assessment of human epidermal growth factor receptor (HER) 2 status on pathologic tissues, 274 archival invasive breast carcinomas from 5 different laboratories were evaluated using the HercepTest. In 1 laboratory in which 10% neutral buffered formalin was used, as recommended by the manufacturer, the overexpression rate was 22.4% and fell within the statistical expected range (20%-30%) for HER2 overexpression in breast carcinomas. The overexpression rates in the other 4 laboratories, in which either 20% nonbuffered formalin or 15% neutral buffered formalin was used, were near the expected range for HER2 overexpression. To clarify the influence of prolonged formalin fixation on the HercepTest, we compared 1-day with 7-day fixations using 36 cases fixed with 20% nonbuffered formalin. Of the 36 cases, 7 showed 3+ staining with 1-day fixation and sustained the same scoring results with 7-day fixation, although the staining intensities in these cases were reduced with the prolonged fixation. These results indicated that the immunohistochemical assessment of HER2 status with the HercepTest was comparatively resistant to prolonged fixation conditions and provided stable staining results in positive cases, particularly 3+ patients.
Appl Immunohistochem Mol Morphol 2003 Dec
PMID:Interlaboratory comparison in HercepTest assessment of HER2 protein status in invasive breast carcinoma fixed with various formalin-based fixatives. 1466 61

One hallmark of tumor formation is the transcriptional upregulation of human telomerase reverse transcriptase, hTERT, and the resultant induction of telomerase activity. However, little is presently understood about how hTERT is differentially activated in tumor cells versus normal somatic cells. Specifically, it is unclear if oncoproteins can directly elicit hTERT expression. To this end, we now show that three oncoproteins, HER2/Neu, Ras, and Raf, stimulate hTERT promoter activity via the ETS transcription factor ER81 and ERK mitogen-activated protein (MAP) kinases. Mutating ER81 binding sites in the hTERT promoter or suppression of ERK MAP kinase-dependent phosphorylation of ER81 rendered the hTERT promoter unresponsive to HER2/Neu. Further, expression of dominant-negative ER81 or inhibition of HER2/Neu significantly attenuated telomerase activity in HER2/Neu-overexpressing SKBR3 breast cancer cells. Moreover, HER2/Neu, Ras, and Raf collaborated with ER81 to enhance endogenous hTERT gene transcription and telomerase activity in hTERT-negative, nonimmortalized BJ foreskin fibroblasts. Accordingly, hTERT expression was increased in HER2/Neu-positive breast tumors and breast tumor cell lines relative to their HER2/Neu-negative counterparts. Collectively, our data elucidated a mechanism whereby three prominent oncoproteins, HER2/Neu, Ras, and Raf, may facilitate tumor formation by inducing hTERT expression in nonimmortalized cells via the transcription factor ER81.
Mol Cell Biol 2004 Jan
PMID:Upregulation of the Catalytic Telomerase Subunit by the Transcription Factor ER81 and Oncogenic HER2/Neu, Ras, or Raf. 1467 40

We studied the feasibility of using real-time quantitative PCR to determine HER-2 DNA amplification and mRNA expression in microdissected formalin-fixed, paraffin-embedded breast tumors and compared this with standard immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) methods. Study cases (27 carcinomas and 3 ductal breast carcinoma in situ (DCIS) cases) showed varying Her-2 expression as determined by IHC (HercepTest). In carcinomas, there was a good correlation between HER-2 DNA amplification and strong HER-2 protein expression detected by FISH and IHC, respectively. A single DCIS case was amplified in FISH, but not in IHC. Both HER-2 gene amplification and expression could be quantified in microdissected paraffin-embedded tumors using real-time PCR, DNA and RNA being successfully detected in 146 of 150 (97%) and 141 of 150 (94%) samples, respectively. PCR analysis for HER-2 DNA amplification using the LightCycler HER2/neu DNA Quantification kit (Roche Molecular Biochemicals, Mannheim, Germany) correlated fairly well with IHC and FISH. All IHC HER-2 3+ tumors were amplified according to the kit, as was the FISH-amplified DCIS case. DNA-PCR identified five additional tumors as being amplified. Interestingly, all these scored 2+ with the HercepTest, but were negative using FISH. We believe that real-time quantitative PCR analysis of HER-2 DNA amplification following microdissection represents a useful supplementary or perhaps even an alternative technique for establishing HER-2 status in paraffin-embedded tumors.
J Mol Diagn 2004 Feb
PMID:Real-time quantitative PCR of microdissected paraffin-embedded breast carcinoma: an alternative method for HER-2/neu analysis. 1473 26

Bispecific antibodies (BiAbs) are being used to target T cells or other immune cells to antigen-specific tumor targets. Anti-CD3 activated T cells (ATC) armed with anti-CD3 x anti-HER2 BiAb (HER2Bi) have been used to target Her2/neu + breast and prostate carcinoma cells. We adapted BiAb technology to target stem cells to injured myocardium. Since myocardial infarctions can lead to cardiac death and disability, rapid repair and rejuvenation of damaged myocardium is critically needed. Effective homing of stem cells and transdifferentiation of the stem cells into functional elements of the myocardium is needed for repair of damaged myocardium. We use a BiAb that binds c-kit on murine stem cells and VCAM-1 adhesion molecules up-regulated on injured myocardial cells. To test for specific binding and homing in a mouse, we produced anti-c-kit x anti-VCAM-1 to target purified Lin-Sca+ murine stem cells to the injured myocardium. Mice with infarcts created by ligation of the left anterior descending artery (LAD) were directly injected with armed stem cells or injected via the internal jugular vein (IJ) with FACS sorted Lin-Sca+ stem cells from bone marrow after fluorescent dye labeling. There were increased numbers of armed Lin-Sca+ cells retained in infracted myocardium after direct injection of armed Lin-Sca+ cells and increased numbers of Lin-Sca+ cells that were found in injured myocardium after IJ injection. These results suggest that stem cells retargeted with BiAb can be directly injected and retained by injured myocardium or targeted to injured myocardial tissues for tissue regeneration.
Blood Cells Mol Dis
PMID:Targeting of Lin-Sca+ hematopoietic stem cells with bispecific antibodies to injured myocardium. 1475 18

The HER-2/neu oncogene, a member of the epidermal growth factor receptor or erb gene family, encodes a transmembrane tyrosine kinase receptor that has been linked to prognosis and response to therapy with the anti-HER-2-humanized monoclonal antibody, trastuzumab (Herceptin, Genentech, South San Francisco, CA) in patients with advanced metastatic breast cancer. HER-2/neu status has also been tested for its ability to predict the response of breast cancer to other therapies including hormonal therapies, topoisomerase inhibitors, and anthracyclines. This review includes an analysis of 80 published studies encompassing more than 25,000 patients designed to consider the relative advantages and disadvantages of the various methods of measuring HER-2/neu in clinical breast cancer specimens. Southern blotting, PCR amplification detection, and fluorescence in situ hybridization assays designed to detect HER-2/neu gene amplification are compared with HER-2/neu protein overexpression assays performed by immunohistochemical techniques applied to frozen and paraffin-embedded tissues and enzyme immunoassays performed on tumor cytosols. The significance of HER-2/neu overexpression in ductal carcinoma in situ and the HER-2/neu status in uncommon female breast conditions and male breast cancer are also considered. The role of HER-2/neu testing for the prediction of response to trastuzumab therapy in breast cancer is reviewed along with the current studies designed to test whether HER-2/neu status can predict the response to standard and newer hormonal therapies, cytotoxic chemotherapy, and radiation. The review will also evaluate the status of serum-based testing for circulating HER-2/neu receptor protein and its ability to predict disease outcome and therapy response.
Mol Cell Proteomics 2004 Apr
PMID:Targeted therapy in breast cancer: the HER-2/neu gene and protein. 1476 15


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