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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a previous paper, we suggested that tamoxifen (TAM)-mediated endometrial carcinogenesis may not involve estrogenic pathways because of random estrogen receptor positivity among endometrial carcinomas with and without TAM treatment for breast cancer. DNA adduct formation (reported in rat liver and human endometrium) was considered to be a more plausible mechanism for TAM-mediated carcinogenesis. To examine the reported correlation between DNA adduct formation and p53, the present study examined p53 expression in the endometrial carcinomas reported in the previous study. Seven endometrial adenocarcinomas associated with long-term TAM treatment for breast carcinoma and 4 carcinomas without TAM treatment but with history of breast carcinoma were immunohistochemically investigated for nuclear p53 expression. The bcl-2 product was also examined. Diffuse and intense nuclear reactivity for p53 protein was present in only one TAM-related case. Essentially, no differences were observed in the bcl-2 staining patterns of TAM-treated and -untreated patients with cancer. Thus, p53 overexpression in endometrial carcinomas occurring in patients with breast cancer seems to be not specific for TAM-treated patients, and, if DNA adduct formation has any role in this type of endometrial carcinogenesis, it may not be related preferentially to p53 gene alteration. Further studies are needed to understand the precise mechanism(s) of the endometrial carcinogenesis.
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PMID:Random nuclear p53 overexpression pattern in tamoxifen-mediated endometrial carcinoma. 955 10

To characterize the biological features of breast cancer associated with germ-line mutations in BRCA1 and BRCA2, invasive tumors were studied from 58 Jewish women ascertained through studies of early-onset breast cancer. All women were tested for the BRCA1 founder mutations 187delAG (commonly known as 185delAG) and 5385insC (commonly known as 5382insC) and the BRCA2 founder mutation 6174delT. Mutations were detected in 17 of 58 (29.3%) women. Comparing BRCA-associated breast cancers (BABCs) to cases arising in women without founder mutations, no differences were noted in tumor size, tumor stage, or frequency of axillary nodal involvement. Infiltrating ductal carcinoma was the predominant histological type in both groups. BABCs were significantly more likely to be of histological grade III (100 versus 63%; P = 0.04), estrogen receptor negative (75 versus 35%; P = 0.004), and HER2/neu negative (87 versus 58%; P = 0.04). An associated intraductal component was present in 59% of BABCs and 76% of cancers not associated with mutations (P = not significant). A high Ki-67 labeling index was more commonly observed in BABCs than in cases without mutations (83 versus 48%; P = 0.09). There were no differences between the two groups in the frequency of expression of epidermal growth factor receptor, cathepsin D, bcl-2, p27, p53, or cyclin D. There were no significant differences in relapse-free or overall survival. These observations suggest that breast cancers arising in Jewish women with germ-line BRCA founder mutations have a greater proliferative potential than cancers in women without such mutations. Additional studies of BABC are required to determine the nature and implications of additional genetic abnormalities occurring in these tumors.
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PMID:BRCA-associated breast cancer: absence of a characteristic immunophenotype. 958 22

Beta-lapachone (beta-lap) affects a number of enzymes in vitro, including type I topoisomerase (Topo I); however, its exact intracellular target(s) and mechanism of cell killing remain unknown. We compared the cytotoxic responses of MCF-7:WS8 (MCF-7) human breast cancer cells after 4-h pulses of beta-lap or camptothecin (CPT), a known Topo I poison. A direct correlation between loss of survival and apoptosis was seen after beta-lap treatment (LD50 = 2.5 microM). A concentration-dependent, transient sub-2 N preapoptotic cell population was observed at 4-8 h. Estrogen deprivation-induced synchronization and bromodeoxyuridine-labeling studies revealed an apoptotic exit point near the G1-S border. Apoptosis activated by beta-lap was closely correlated with cleavage of lamin B but not with increases in p53/p21 or decreases in bcl-2. Loss of hyperphosphorylated forms of the retinoblastoma protein was observed within 5 h, but cyclins A, B1, and E levels were unaltered for up to 72 h after 5 microM beta-lap. Topo I and Topo IIalpha levels decreased at > 24 h. Logarithmic-phase MCF-7 cells were not affected by < or = 1 microM beta-lap. In contrast, dramatic and irreversible G2-M arrest with no apoptosis was observed in MCF-7 cells treated with 1 microM CPT, monitored for 6-10 days posttreatment. MCF-7 cells treated with supralethal doses of CPT (5 microM) resulted in only approximately 20% apoptosis. No correlation between apoptosis and loss of survival was observed. MCF-7 cells exposed to > 5 microM CPT arrested at key cell cycle checkpoints (i.e., G1, S, and G2-M), with little or no movement for 6 days. Ten-fold increases in p53/p21 and 2-5-fold decreases in bcl-2, Topo I, Topo IIalpha, and cyclins A and B1, with no change in cyclin E, were observed. Temporal decreases in bcl-2 and cleavage of lamin B corresponded to the minimal apoptotic response observed. Beta-lap activated apoptosis without inducing p53/p21 or cell cycle arrest responses and killed MCF-7 cells solely by apoptosis. In contrast, concentration-dependent increases in nuclear p53/p21 and various cell cycle checkpoint arrests were seen in MCF-7 cells after CPT. Despite dramatic p53/p21 protein induction responses, CPT-treated MCF-7 cells showed low levels of apoptosis, possibly due to protective cell cycle checkpoints or the lack of specific CPT-activated apoptotic pathways in MCF-7 cells.
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PMID:Induction of apoptosis in MCF-7:WS8 breast cancer cells by beta-lapachone. 958 28

Apoptosis is considered to play a critical role in tumorigenesis. It has been shown that apoptosis is controlled by both pro-oncogenes bcl-2, c-myc and tumor-suppressor genes p53. We determined the apoptotic index (AI) on light microscopy and detected immunohistochemically the expression of bcl-2 and p53 in patients with breast cancer. The correlations between AI and clinicopathological factors, bcl-2 and p53 were also analyzed. Our results showed that bcl-2 expression was down-regulated in the process from normal breast epithelial cells to intraductal carcinoma and from intraductal carcinoma to invasive carcinoma. We failed to detect p53 protein in normal breast epithelial cells, and p53 positivity was 24% and 30% in intraductal and invasive cancer tissues, respectively. Moreover, AI was significantly associated with histological grade, mitotic index, and bcl-2 and p53 expression. In univariate analyses, lower AI and bcl-2 expression was significantly predictive of a better prognosis for both disease-free survival and overall survival. These results suggest that apoptosis and apoptosis-related gene (bcl-2, p53) are related to progression and prognosis in breast cancer.
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PMID:[Correlation between apoptotic index, bcl-2 protein expression and progression and prognosis in breast carcinoma]. 958 45

Experimental laboratory data suggest that tumour growth is a balance between apoptosis and proliferation and that suppression of drug-induced apoptosis by oncogenes such as bcl-2 may be an important cause of intrinsic chemoresistance. The aims of this study were to assess the in vivo relationship of apoptosis to proliferation and Bcl-2 protein in human breast tumours both prior to chemotherapy and in the residual resistant cell population at the completion of treatment. We examined apoptotic index (AI), Ki67 and Bcl-2 protein expression in the tissue of 40 patients with operable breast cancer immediately before ECF preoperative chemotherapy, and in 20 of these patients with residual tumour, at the completion of treatment. There was a significant positive association between AI and Ki67 both before and after chemotherapy, and in their percentage change with treatment. In the residual specimens AI and Ki67 were significantly reduced compared with pre-treatment biopsies, while Bcl-2 expression showed a significant increase. No differences were seen in the pre-treatment levels of any of the variables measured between patients obtaining pathological complete response and those who did not, although numbers were small. These data suggest that apoptosis and proliferation are closely related in vivo. It is possible that the phenotype of reduced apoptosis and proliferation, and increased Bcl-2 may be associated with breast cancer cells resistant to cytotoxic chemotherapy, although this can only be proven by assessing larger numbers of patients in relation to pathological response.
Breast Cancer Res Treat 1998 Mar
PMID:Reduced apoptosis and proliferation and increased Bcl-2 in residual breast cancer following preoperative chemotherapy. 959 82

Prognostic factors are clinical and pathological features that give information in estimating the likely clinical outcome of an individual suffering from cancer. The author gives a short review of the most important prognostic factors in breast cancer. 376 breast cancer cases of a ten year interval in a county hospital are summarized. Traditional clinico-pathological parameters i.e. TNM and steroid receptor status are discussed. The more common karyotipic, oncogene and tumor suppressor gene alterations are outlined in the study. Methods for their detection are presented and their value in prognostication is reviewed. Emphasis was laid on steroid receptors, c-erpB-2, p53 and bcl-2 alterations. Genes responsible for heritable forms of increased breast cancer risk are briefly reviewed.
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PMID:[Prognostic factors in breast cancer]. 960 69

Induction of differentiation and apoptosis in cancer cells through ligands of nuclear hormone receptors (NHRs) is a novel and promising approach to cancer therapy. All-trans-retinoic acid (ATRA), an RA receptor-specific NHR ligand, is now used for selective cancers. The NHR, peroxisome proliferator-activated receptor gamma (PPARgamma) is expressed in breast cancer cells. Activation of PPARgamma through a synthetic ligand, troglitazone (TGZ), and other PPARgamma-activators cause inhibition of proliferation and lipid accumulation in cultured breast cancer cells. TGZ (10(-5) M, 4 days) reversibly inhibits clonal growth of MCF7 breast cancer cells and the combination of TGZ (10(-5) M) and ATRA (10(-6) M, 4 days) synergistically and irreversibly inhibits growth and induces apoptosis of MCF7 cells, associated with a dramatic decrease of their bcl-2 protein levels. Similar effects are noted with in vitro cultured breast cancer tissues from patients, but not with normal breast epithelial cells. The observed apoptosis mediated by TGZ and ATRA may be related to the striking down-regulation of bcl-2, because forced over-expression of bcl-2 in MCF7 cells cultured with TGZ and ATRA blocks their cell death. TGZ significantly inhibits MCF7 tumor growth in triple immunodeficient mice. Combined administration of TGZ and ATRA causes prominent apoptosis and fibrosis of these tumors without toxic effects on the mice. Taken together, this combination may provide a novel, nontoxic and selective therapy for human breast cancers.
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PMID:Ligands for peroxisome proliferator-activated receptorgamma and retinoic acid receptor inhibit growth and induce apoptosis of human breast cancer cells in vitro and in BNX mice. 967 60

Apoptosis is considered to play a critical role in tumorigenesis. In order to clarify the significance of apoptosis in breast cancers, we quantitated apoptotic cells by light microscopy in 126 patients with invasive breast cancers. The expression of bcl-2, and p53, as regulators of apoptosis, was immunohistochemically analyzed. Apoptotic index (AI) detected in the patients ranged from 0 to 48 per mm2 of breast cancer cells (mean +/- SE, 11.0 +/- 0.97). Significantly highly AI was found for the tumors with grade 3 (p < 0.0001), high mitotic index (p < 0.0001), and bcl-2 negatively (p = 0.004) compared with those with grade 1 or 2, low mitotic index, and bcl-2 expression, respectively. Moreover, high AI was associated with larger tumor size (p = 0.008), positive lymph nodes (p = 0.01), p53 positivity (p = 0.01), and advanced TNM stage (p = 0.03). In survival analysis, we found that low AI, like bcl-2 and other conventional prognostic indicators, was significantly predictive of better prognosis in terms of both disease-free survival (DFS) and overall survival (OS) (each, p < 0.0001). In multivariate analysis, AI failed to retain an independent significant value for DFS or OS. Our results indicate that low AI is related to a number of clinicopathologic and biologic parameters known to predict a lower risk of recurrence and is associated with a favourable survival in invasive breast cancer. However, it was not an independent prognostic factor for clinical outcome in this patient series.
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PMID:Apoptotic index correlates to bcl-2 and p53 protein expression, histological grade and prognosis in invasive breast cancers. 967 55

The proto-oncogene bcl-2 is demonstrated to block a final common pathway leading to apoptosis and is expressed in more than half of human breast cancers. Invasive breast cancer has reduced bcl-2 immunostaining compared with normal breast epithelia and preinvasive breast lesions. As an inhibitor of apoptosis, bcl-2 should correlate with highly aggressive tumor biology and resistance to hormonal/cytotoxic therapy. However, high bcl-2 expression has been shown to associate with a number of favorable prognostic factors including ER positivity, PgR positivity, low histological grade, well-differentiated tumor, absence of c-erbB-2 and p53. Unexpectedly, numerous studies have shown that tumors with high bcl-2 expression are more responsive to hormone therapy and have more favorable disease-free and overall survival. The clinical significance of bcl-2 in tumorigenesis and prognosis of breast carcinomas from the data recently published are reviewed. Its role in modulation of hormonal/cytotoxic therapy and future directions are also discussed.
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PMID:The role of bcl-2 expression in breast carcinomas (Review). 968 37

Recent evidence has emphasized the importance of programmed cell death or apoptosis in the maintenance of tissue homeostasis and pathogenesis of tumors. This study, analyzed in breast cancer, investigates the significance of apoptosis in relation to the expression of p53 and bcl-2 proteins, tissue proliferation defined by Ki-67 expression, hormone receptors and tumor grade. The extent of apoptosis was defined by morphological criteria and the TUNEL (Tdt-mediated dUTP biotin nick end labelling) assay. Immunocytochemistry was performed for p53, bcl-2, estrogen receptor, progesterone receptor and Ki-67 expression. Mutant p53 protein was detected using a mutant specific ELISA. Immunoreactivity of p53 significantly correlated with the presence of mutant p53 protein detected by ELISA (r = 0.654, p = 0.00001). An inverse correlation was observed between bcl-2 expression and the extent of apoptosis (r = -0.33369, p = 0.01912). The extent of apoptosis directly correlated with p53 protein accumulation (r = 0.485, p = 0.00041), Ki-67 immunoreactivity (r = 0.435, p = 0.001), histopathological grade (r = 0.492, p = 0.0003), tumor size (r = 0.326, p = 0.023) and lymph node status (r = 0.287, p = 0.047). A direct correlation was also observed between p53 expression and Ki-67 immunoreactivity (r = 0.623, p = 0.0002). There was no statistically significant association between estrogen and progesterone receptor status and apoptosis. In addition, the TNM stage of the disease correlated with immunoreactivity of p53 (r = 0.572, p = 0.00012) and Ki-67 (r = 0.3744, p = 0.00818). Bcl-2, by inhibiting apoptosis, may cause a shift in tissue kinetics towards the preservation of genetically aberrant cells, thereby facilitating tumor progression. These results imply that rapidly proliferating tumors appear to have a high "cell turnover state" in which there may be an increased chance of apoptosis amongst the proliferating cells. The ability of apoptosis to also occur in the presence of mutant p53 protein suggests the existence of at least two p53-dependent apoptotic pathways, one requiring activation of specific target genes and the other independent of it.
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PMID:Spontaneous programmed cell death in infiltrating duct carcinoma: association with p53, BCL-2, hormone receptors and tumor proliferation. 977 89


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