Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inhibitors of proteases are currently emerging as a potential anti-cancer modality. Nonselective protease inhibitors are cytotoxic to leukemia and cancer cell lines and we found that this cytotoxicity is correlated with their potency as inhibitors of the proteasome but not as inhibitors of calpain and cathepsin. Highly selective inhibitors of the proteasome were more cytotoxic and fast-acting than less selective inhibitors (PS341>>ALLN>>ALLM). Induction of wt p53 correlated with inhibition of the proteasome and antiproliferative effect in MCF7, a breast cancer cell line, which was resistant to apoptosis caused by proteasome inhibitors. In contrast, inhibitors of the proteasome induced apoptosis in four leukemia cell lines lacking wt p53. The order of sensitivity of leukemia cells was: Jurkat>HL60> or =U937>>K562. The highly selective proteasome inhibitor PS-341 induced cell death with an IC50 as low as 5 nM in apoptosis-prone leukemia cells. Cell death was preceded by p21WAF1/CIP1 accumulation, an alternative marker of proteasome inhibition, and by cleavage of PARP and Rb proteins and nuclear fragmentation. Inhibition of caspases abrogated PARP cleavage and nuclear fragmentation and delayed, but did not completely prevent cell death caused by PS-341. Reintroduction of wt p53 into p53-null PC3 prostate carcinoma cells did not increase their sensitivity to proteasome inhibitors. Likewise, comparison of parental and p21-deficient cells demonstrated that p21WAF1/CIP1 was dispensable for proteasome inhibitor-induced cytotoxicity. We conclude that accumulation of wt p53 and induction of apoptosis are independent markers of proteasome inhibition.
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PMID:Protease inhibitor-induced apoptosis: accumulation of wt p53, p21WAF1/CIP1, and induction of apoptosis are independent markers of proteasome inhibition. 1091 53

Estrogen, via its binding to the estrogen receptor (ER), plays an important role in breast cancer cell proliferation and tumor development. Indole-3-carbinol (I3C), a compound occurring naturally in cruciferous vegetables, exhibits a potent antitumor activity via its regulation of estrogen activity and metabolism. This study was designed to determine the effect of I3C on the potential to inhibit the ER-alpha. Using a reporter gene driven by the estrogen receptor, I3C (10-125 micromol/L) significantly repressed the 17ss-estradiol (E2)-activated ER-alpha signaling in a dose-dependent manner. I3C and breast cancer susceptibility gene 1 (BRCA1) synergistically inhibited transcriptional activity of ER-alpha. Moreover, I3C down-regulated the expression of the estrogen-responsive genes, pS2 and cathepsin-D, and up-regulated BRCA1. The inhibitory effects of I3C did not contribute to its cytotoxic effects because these activities were observed at less than toxic concentrations. These results further suggest that antitumor activities of I3C are associated not only with its regulation of estrogen activity and metabolism, but also its modulation of ER transcription activity.
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PMID:Indole-3-carbinol is a negative regulator of estrogen receptor-alpha signaling in human tumor cells. 1111 Aug 48

Proteolytic enzymes have been proposed as new biological prognostic indicators to facilitate decisions about treatment of breast cancer patients following surgery. We reported earlier that the activities of cysteine proteinases (CP), cathepsin (Cat) B and cathepsin (Cat) L and the expression of stefin A might be associated with breast tumor progression and prognosis. Here, the protein concentrations of Cats D, B and L and stefin A have been measured in a series of 60 matched pairs of breast tumours and control adjacent tissues, using ELISAs developed in our laboratory. Median tumor concentrations of Cat D (47 pm/mg), Cat B (222 ng/mg) and Cat L (88 ng/mg) were significantly (p<0.0005) increased by 7 fold, 27 fold and 6 fold, respectively. Much greater increases in the activities of Cat B (63 fold) and of Cat L (274 fold) were found, indicating activation of proCat B and proCat L and/or to a decrease in specific endogenous cystatins. However, the 1.6-fold decreased (p<0.0001) levels of inhibition by cystatins could not be entirely responsible for more than 100-fold increased ratio of CP:cystatins activity. Moreover, stefin A was either increased or decreased in tumor samples, resulting in a 1.4-fold median increase in tumors. Comparing the biological parameters with the established histo-pathological prognosticators, we found that the increased protein concentration of Cat B was associated with lymph node involvement (p<0.009) and higher stage (p<0.003), and both Cat B and Cat L activities were more increased in high grade tumours (p<0.05). Survival analysis revealed that stefin A was the most significant prognostic factor for disease-free (p<0.008) and overall survival (p<0.02), followed by increased Cat B activity and protein concentration. Cat L was of borderline significance while Cat D was not significant for prognosis. We conclude that enhanced activation of CP, due partially to an imbalance between cysteine proteinases and inhibitors is linked to the progression of breast cancer. Larger sample size is needed to confirm the prognostic significance of stefin A, Cat B and Cat L.
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PMID:The Expression of Lysosomal Proteinases and Their Inhibitors in Breast Cancer: Possible Relationship to Prognosis of the Disease. 1117 33

Cathepsin-D, a lysosomal aspartyl proteinase, is highly secreted by breast cancer cells and its over-expression by transfection stimulates cancer cell proliferation. The mechanism by which this protease affects proliferation remains, however, unknown. In order to determine whether proteolytic activity is necessary, we abolished its enzymatic activity using site-directed mutagenesis followed by stable transfection in 3Y1-Ad12 cancer cells. Substitution of the aspartic acid residue 231 by an asparagine residue in its catalytic site abrogated the cathepsin-D proteolytic activity but did not affect its expression level, processing or secretion. However, like wild-type cathepsin-D, this mutated catalytically-inactive cathepsin-D retained its capacity to stimulate proliferation of cells embedded in Matrigel or collagen I matrices, colony formation in soft agar and tumor growth in athymic nude mice. Addition on the mock-transfected cells, of either conditioned media containing the wild-type or the mutated pro-cathepsin-D, or of the purified mutated pro-cathepsin-D, partially mimicked the mitogenic activity of the transfected cathepsin-D, indicating a role of the secreted pro-enzyme. Moreover, addition of two anti-cathepsin-D antibodies on the cathepsin-D transfected cells inhibited their proliferation, suggesting an action of the secreted pro-cathepsin-D via an autocrine loop. A synthetic peptide containing the 27-44 residue moiety of the cathepsin-D pro-fragment was, however, not mitogenic suggesting that a receptor for the pro-fragment was not involved. Furthermore, the cathepsin-D mitogenicity was not blocked by inhibiting the interaction of pro-cathepsin-D with the mannose-6-phosphate receptors. Our results altogether demonstrate that a mutated cathepsin-D devoid of catalytic activity is still mitogenic and suggest that it is acting extra-cellularly by triggering directly or indirectly a yet unidentified cell surface receptor.
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PMID:A mutated cathepsin-D devoid of its catalytic activity stimulates the growth of cancer cells. 1168 71

Overexpression of cathepsin-D in primary breast cancer has been associated with rapid development of clinical metastasis. To investigate the role of this protease in breast cancer growth and progression to metastasis, we stably transfected a highly metastatic human breast cancer cell line, MDA-MB-231, with a plasmid containing either the full-length cDNA for cathepsin-D or a 535 bp antisense cathepsin-D cDNA fragment. Clones expressing antisense cathepsin-D cDNA that exhibited a 70-80% reduction in cathepsin-D protein, both intra- and extracellularly compared to controls, were selected for further experiments. These antisense-transfected cells displayed a reduced outgrowth rate when embedded in a Matrigel matrix, formed smaller colonies in soft agar and presented a significantly decreased tumor growth and experimental lung metastasis in nude mice compared with controls. However, manipulating the cathepsin-D level in the antisense cells has no effect on their in vitro invasiveness. These studies demonstrate that cathepsin-D enhances anchorage-independent cell proliferation and subsequently facilitates tumorigenesis and metastasis of breast cancer cells. Our overall results provide the first evidence on the essential role of cathepsin-D in breast cancer, and support the development of a new cathepsin-D-targeted therapy.
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PMID:Down-regulation of cathepsin-D expression by antisense gene transfer inhibits tumor growth and experimental lung metastasis of human breast cancer cells. 1214 Jul 63

Cathepsin-D is an independent marker of poor prognosis in human breast cancer. We previously showed that human wild-type cathepsin-D, as well as its mutated form devoid of proteolytic activity stably transfected in 3Y1-Ad12 cancer cells, stimulated tumor growth. To investigate the mechanisms by which human cathepsin-D and its catalytically-inactive counterpart promoted tumor growth in vivo, we quantified the expression of proliferating cell nuclear antigen, the number of blood vessels and of apoptotic cells in 3Y1-Ad12 tumor xenografts. We first verified that both human wild-type and mutated cathepsin-D were expressed at a high level in cathepsin-D xenografts, whereas no human cathepsin-D was detected in control xenografts. Our immunohistochemical studies then revealed that both wild-type cathepsin-D and catalytically-inactive cathepsin-D, increased proliferating cell nuclear antigen expression and tumor angiogenesis. Interestingly, wild-type cathepsin-D significantly inhibited tumor apoptosis, whereas catalytically-inactive cathepsin-D did not. We therefore propose that human cathepsin-D stimulates tumor growth by acting-directly or indirectly-as a mitogenic factor on both cancer and endothelial cells independently of its catalytic activity. Our overall results provide the first mechanistic evidences on the essential role of cathepsin-D at multiple tumor progression steps, affecting cell proliferation, angiogenesis and apoptosis.
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PMID:Cathepsin-D affects multiple tumor progression steps in vivo: proliferation, angiogenesis and apoptosis. 1218 97

The putative role of mannose-6-phosphate/insulin-like growth factor-II receptor (M6P/IGFII-R) as a tumour suppressor and its value as a prognostic marker of breast cancer was studied in 42 benign breast diseases (BBD), 61 in situ carcinomas (CIS) and 133 invasive carcinomas. The receptor was quantified by immunohistochemistry with a computerised image analyser, using specific polyclonal IGY antibodies. The M6P/IGFII-R level varied markedly according to the different patient samples, but median values and distributions were similar in lesions and normal adjacent glands. However, the receptor level was significantly increased in high-grade ductal carcinomas in situ (DCIS) and decreased in invasive carcinomas relative to adjacent normal tissue. The M6P/IGFII-R protein concentration in invasive breast carcinomas was mostly independent of prognostic parameters: tumour size, histological grade, lymph node (N) invasiveness and oestrogen receptor alpha (ERalpha) status. The only positive correlation was with cathepsin D, the progesterone receptor (PgR) and with patients aged >60 years. These results do not support the hypothesis of a frequent and early inactivation of the M6P/IGFII-R gene in breast cancer. Clinical follow-up of patients might reveal a prognostic value for one of the cathepsin receptors.
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PMID:Mannose-6-phosphate/insulin-like growth factor-II receptor expression levels during the progression from normal human mammary tissue to invasive breast carcinomas. 1262 43

Pseudomonas exotoxin (PE)-containing immunotoxins (ITs) act by arresting protein synthesis and promoting apoptosis, but the mechanisms of the induced apoptosis and the relationship to protein synthesis inhibition is not well elucidated. We studied these effects in MA-11 human breast cancer cells treated with 425.3PE, an unmodified PE covalently linked to the 425.3 antibody, which targets the EGF receptor. This IT induced efficient inhibition of protein synthesis with simultaneous induction of apoptosis. Thus, treatment of cells with 10 ng/ml of IT for 5 hr caused 85% inhibition of protein synthesis in parallel with caspase-3, -8 and -9 activation and PARP inactivation. Even after 72 hr of IT treatment, preincubation with the broad-spectrum caspase inhibitor z-VAD-FMK caused a significant increase in cell survival without affecting IT-induced protein synthesis inhibition. Interestingly, a combination of z-VAD-FMK and the cathepsin B/L inhibitor z-FA-FMK prevented completely IT-induced cell death in MA-11 cells after 24 hr, indicating that cathepsin activation may be important for optimal induction of IT-induced cell death. IT treatment caused after 2.5 hr a significant decrease in the level of the antiapoptotic protein Mcl-1 but not of Bcl-2 and Bcl-XL. Furthermore, Mcl-1 expression was not sensitive to caspase inhibitors but was totally prevented by the lactacystin proteasome inhibitor, suggesting that IT-induced apoptosis may be triggered by a reduction in the Mcl-1 level. Mitochondrial membrane potential (DeltaPsi mito) decreased concurrently with caspase activation, showing the involvement of DeltaPsi mito as a regulator of IT-induced apoptosis. Our results demonstrate that 425.3PE-mediated cell death involves simultaneous induction of apoptosis and protein synthesis inhibition in MA-11 cells, thus contributing to an understanding of the mechanisms involved in IT-induced apoptosis.
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PMID:Downregulation of the antiapoptotic MCL-1 protein and apoptosis in MA-11 breast cancer cells induced by an anti-epidermal growth factor receptor-Pseudomonas exotoxin a immunotoxin. 1538 75

Cathepsin D is a lysosomal protease which plays an important role in cancer invasion and metastasis. There are known inhibitors of that enzyme, such as pepstatin and potato inhibitor. In this study, we examined effects of the cathepsin D inhibitor from Vicia sativa L. seed hulls on cell cultures of human skin fibroblasts and breast cancer cells. There is no effect of the D-cathepsin inhibitor from Vicia sativa L. seed hulls on the proliferative activity of either human skin fibroblasts or breast cancer cells, measured by the [3H] thymidine incorporation assay.
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PMID:Effects of cathepsin D inhibitor from Vicia sativa L. seed hulls on human skin fibroblasts and breast cancer cells (in vitro studies). 1563 34

Estrogen receptor alpha (ERalpha) is a ligand-inducible transcription factor that acts to regulate gene expression by binding to palindromic DNA sequence, known as the estrogen response element, in promoters of estrogen-regulated genes. In breast cancer ERalpha plays a central role, where estrogen-regulated gene expression leads to tumor initiation, growth and survival. As an approach to silencing estrogen-regulated genes, we have studied the activities of a fusion protein between ERalpha and the promyelocytic leukemia zinc-finger (PLZF) protein, a transcriptional repressor that acts through chromatin remodeling. To do this, we have developed lines from the estrogen-responsive MCF-7 breast cancer cell line in which the expression of the fusion protein PLZF-ERalpha is conditionally regulated by tetracycline and shows that these feature long-term silencing of the expression of several well-characterized estrogen-regulated genes, namely pS2, cathepsin-D and the progesterone receptor. However, the estrogen-regulated growth of these cells is not inhibited unless PLZF-ERalpha expression is induced, an observation that we have confirmed both in vitro and in vivo. Taken together, these results show that PLZF-ERalpha is a potent repressor of estrogen-regulated gene expression and could be useful in distinguishing estrogen-regulated genes required for the growth of breast cancer cells.
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PMID:Inhibiting estrogen responses in breast cancer cells using a fusion protein encoding estrogen receptor-alpha and the transcriptional repressor PLZF. 1564 73


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