Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Malignant and normal human breast tissue were compared by evaluating two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) maps of frozen tissue samples. Image analyzing software was used to scan and process 34 gels. Eight (8/34) of these gels (4 malignant breast tumor samples, 4 normal tissue samples) were selected on the basis of gel and image quality to build a database to identify and measure the expression of a previously unidentified proteome. Growth factor receptor proteins (GFRs), including ERBB2 (HER2) and ERBB3 (HER3), were expressed in the malignant tissue samples. Growth factor receptor proteins were not expressed in the normal tissue. Also, expression of PS2-protein (pS2) was detected in neither malignant nor normal tissue. In benign breast samples a higher intensity of protein expression could be observed for maspin, desmoglein 3 and keratin 8 than in malignant samples. Other proteins expressed in malignant breast tissue include mitogen-activated protein kinase 3 (MK03), heat shock protein 27 kDa (HS27), growth factor receptor-bound protein (GRB2), cathepsin D, G1/S specific cyclin E1 (CGEI), glucose transporter type 5 (GTR5), and a number of as yet unidentified proteins.
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PMID:Comparative analysis of two-dimensional protein patterns in malignant and normal human breast tissue. 1142 69

Tamoxifen resistance is common for estrogen receptor alpha (ERalpha) positive breast cancer. Second-line therapies include aromatase inhibitors or fulvestrant. We have shown previously that fulvestrant reversed 17beta-estradiol-induced tumor regression of tamoxifen-stimulated MCF-7 xenografts (MCF-7TAMLT) treated for >5 years with tamoxifen in athymic mice and paradoxically stimulated growth. We investigated mechanisms responsible for growth by fulvestrant in the presence of physiologic estradiol and therapeutic strategies in vivo. The results demonstrated that only estradiol increased expression of the estrogen-responsive genes, c-myc, igf-1, cathepsin D, and pS2 mRNAs, in MCF-7E2 and MCF-7TAMLT tumors. Tamoxifen or fulvestrant decreased the estradiol-induced increase of these mRNAs in both tumor models. However, tyrosine-phosphorylated HER2/ neu, HER3, phospho-extracellular-regulated kinase-1/2 (ERK-1/2), and phospho-glycogen synthetase kinase 3alpha (GSK3alpha) and beta proteins were increased in MCF-7TAMLT tumors treated with fulvestrant compared to estradiol, control, or tamoxifen. Phospho-HER2/neu interacted with HER3 protein in MCF-7TAMLT tumors. In order to determine whether the functional interaction of HER2/neu with HER3 is critical for growth of fulvestrant-stimulated MCF-7TAMLT tumors, pertuzumab (an antibody that blocks HER2/neu-HER3 interaction) was used in an in vivo xenograft growth assay. Only growth of fulvestrant-treated MCF-7TAMLT xenografts was decreased significantly by 37.2% in response to pertuzumab (P=0.004). Pertuzumab specifically decreased the interaction of HER2/neu protein with HER3 in fulvestrant-stimulated MCF-7TAMLT tumors. These results suggested growth of MCF-7TAMLT tumors by tamoxifen or fulvestrant is potentially independent of ERalpha transcriptional activity as evidenced by lack of induction of four estrogen-responsive genes. The results suggested that growth of MCF-7TAMLT tumors treated with fulvestrant in the presence of physiologic estradiol is in part mediated through enhanced signaling from the HER2/neu-HER3 pathway as pertuzumab partially inhibited growth and the interaction of HER2/neu with HER3 in vivo.
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PMID:Role for HER2/neu and HER3 in fulvestrant-resistant breast cancer. 1720 34