Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Homeostasis in normal tissue is regulated by a balance between proliferative activity and cell loss by apoptosis. Apoptosis is a physiological mechanism of cell loss that depends on both pre-existing proteins and de novo protein synthesis, and the process of apoptosis is integral to normal mammary gland development and in many diseases, including breast cancer. The mammary gland is one of the few organ systems in mammals that completes its morphologic development postnatally during two discrete physiologic states, puberty and pregnancy. The susceptibility of the mammary gland to tumorigenesis is influenced by its normal development, particularly during stages of puberty and pregnancy that are characterized by marked alterations in breast cell proliferation and differentiation. Numerous epidemiologic studies have suggested that specific details in the development of the mammary gland play a critical role in breast cancer risk. Mammary gland development is characterized by dynamic changes in the expression profiles of Bcl-2 family members. The expression of Bcl-2 family proteins in breast cancer is also influenced by estradiol and by progestin. Since the ratio of proapoptotic to antiapoptotic proteins determines apoptosis or cell survival, hormone levels may have important implications in the therapeutic prevention of breast cancer.
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PMID:Apoptosis in mammary gland and cancer. 1117 47

Bcl-2 protein together with the pro-apoptotic protein bax, are thought to function by forming homo- and heterotypic dimers which control the progression to apoptosis. In this immunohistochemical study we investigated the expression of bcl-2 and bax apoptosis related proteins in cervical intraepithelial neoplasia and invasive squamous cell carcinoma of the uterine cervix. Twenty-four cervical intraepithelial neoplasias grade 1-2 (CIN I/II), 38 grade 3 (CIN III), and 53 invasive squamous cell carcinomas (ISCC) were investigated by immunohistochemical staining for bcl-2 and bax protein. Bcl-2 immunoreactivity was found in five of the 24 CIN I/II cases (20.8%), 18 of 38 CIN II cases (47.4%) and nine of 53 ISCC cases (17%). The positivity for CIN III was significantly higher than for CIN I/II or ISCC (p=0.0351 and p=0.0018, respectively). The percentage of bax immunopositivity was somewhat higher in CIN III than in CIN I/II but this slight difference was not statistically significant. Correlation of the immunostaining results with tumor grade revealed a significant difference for bcl-2 which was more frequently immunopositive in well-differentiated tumors than in poorly-differentiated tumors. There was no significant relation between bax expression and tumor differentiation. Our results suggest that alterations of bcl-2 and bax expression may occur as a relatively early event in cervical tumorigenesis.
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PMID:Expression of bcl-2 and bax in cervical intraepithelial neoplasia and invasive squamous cell carcinoma of the uterine cervix. 1119 41

Transgenic mice that overexpress transforming growth factor (TGF)-alpha develop liver tumors between 12 and 15 months of age. Tumor development is preceded by an overall increase in the rates of hepatocyte proliferation and cell death. To examine the role of apoptosis in the development of TGF-alpha-induced liver tumors, we generated TGF-alpha/Bcl-2 double transgenic mice by crossing TGF-alpha transgenic mice with Bcl-2 transgenic mice expressing a zinc-inducible Bcl-2 transgene. Overexpression of the Bcl-2 transgene protected hepatocytes from Fas-mediated apoptosis. We anticipated that hepatocytes in TGF-alpha/Bcl-2 double transgenic mice would be stimulated to proliferate but would fail to undergo apoptosis, leading to increased liver weights and accelerated tumorigenesis. At 4 weeks of age, both TGF-alpha single transgenic and TGF-alpha/Bcl-2 double transgenic mice had elevated hepatocyte proliferation and increased liver:body weight ratios. However, by 8 months, the liver:body weight ratios had normalized in both TGF-alpha single transgenic and TGF-alpha/Bcl-2 double transgenic mice. Furthermore, Bcl-2 functioned as a tumor suppressor, significantly decreasing the frequency and delaying the development of TGF-alpha-induced liver tumors, despite having comparable levels of TGF-alpha transgene expression in both single and double transgenic mice. Between 11 and 12 months of age, >80% of the TGF-alpha single transgenic mice had developed tumors, whereas only 54% of the double transgenic mice had developed tumors after 13 months of age. The tumors that eventually developed in the TGF-alpha/Bcl-2 double transgenic mice were histologically distinct and smaller in size and had lower hepatocyte mitotic activity than tumors from TGF-alpha single transgenic mice. Furthermore, delaying Bcl-2 expression until 8.5 months of age was sufficient to inhibit TGF-alpha-induced tumorigenesis. These results indicate that Bcl-2 inhibits tumor progression in the liver, possibly by interfering with hepatocyte proliferation.
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PMID:Bcl-2 delays and alters hepatic carcinogenesis induced by transforming growth factor alpha. 1121 55

Bax is a Bcl-2 family member that promotes apoptosis and counters the protective effect of Bcl-2. Bax is a downstream effector of p53-induced apoptosis and is transcriptionally regulated by p53. Moreover, the introduction of Bax deficiency accelerates the onset of tumors in transgenic mice expressing truncated large T antigen. These results implicate Bax as a tumor suppressor. Consequently, we asked whether the levels of Bax expression would influence tumor development by comparing Bax-deficient and Bax transgenic mice in the presence or absence of p53. We found that Bax-deficient mice did not display an increased incidence of spontaneous cancers when followed for > 1.5 years. In addition, Bax-deficiency did not further accelerate oncogenesis in mice also deficient in p53. We generated Lck(pr)-Bax transgenic mice to examine the effects of overexpressed BAX on T-cell development and tumorigenesis. Lck(pr)-Bax mice show increased apoptosis consistent with the pro-apoptotic function of Bax. The introduction of p53-deficiency did not interfere with BAX-induced apoptosis; this is consistent with BAX operating downstream or independent of p53. However, we found that Lck(pr)-Bax/p53-deficient mice have an increased incidence of T-cell lymphomas when compared with p53-deficient mice. The Lck(pr)-Bax transgenic mice have an increased percentage of cells in cycle. These findings extend previous work suggesting that Bcl-2 family proteins regulate proliferation as well as cell death. We conclude that BAX-induced proliferation is synergistic with a defect in apoptosis contributed by p53-deficiency. Thus, the dual roles of BAX can either accelerate or inhibit tumorigenesis depending on the genetic context.
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PMID:Bax accelerates tumorigenesis in p53-deficient mice. 1121 65

Iron is suspected to be involved in the induction and/or progression of various human tumors. The present study was designed to investigate the effects of iron on endothelial cells, keeping in mind that the homeostasis of microvessels plays a critical role in neo-angiogenesis. Applying a model of human dermal microvascular endothelial cell terminal differentiation and death induced by serum deprivation, we found that iron salts (iron chloride and ferric nitrilotriacetate) provided a survival advantage to endothelial cells. Using immunohistochemistry and Western Blot analysis, we found that the extended cellular life span induced by iron was paralleled by an increase of Bcl-2 protein expression. Taken together, these observations suggest that iron may give a survival advantage to endothelial cells and represent a novel mechanism through which iron may contribute to tumorigenesis.
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PMID:Iron induces Bcl-2 expression in human dermal microvascular endothelial cells. 1126 98

The cyclooxygenase (COX)-2 gene encodes an inducible prostaglandin synthase enzyme that is overexpressed in adenocarcinomas and other tumors. Deletion of the murine Cox-2 gene in Min mice reduced the incidence of intestinal tumors, suggesting that it is required for tumorigenesis. However, it is not known if overexpression of Cox-2 is sufficient to induce tumorigenic transformation. We have derived transgenic mice that overexpress the human COX-2 gene in the mammary glands using the murine mammary tumor virus promoter. The human Cox-2 mRNA and protein are expressed in mammary glands of female transgenic mice and were strongly induced during pregnancy and lactation. Female virgin Cox-2 transgenic mice showed precocious lobuloalveolar differentiation and enhanced expression of the beta-casein gene, which was inhibited by the Cox inhibitor indomethacin. Mammary gland involution was delayed in Cox-2 transgenic mice with a decrease in apoptotic index of mammary epithelial cells. Multiparous but not virgin females exhibited a greatly exaggerated incidence of focal mammary gland hyperplasia, dysplasia, and transformation into metastatic tumors. Cox-2-induced tumor tissue expressed reduced levels of the proapoptotic proteins Bax and Bcl-x(L) and an increase in the anti-apoptotic protein Bcl-2, suggesting that decreased apoptosis of mammary epithelial cells contributes to tumorigenesis. These data indicate that enhanced Cox-2 expression is sufficient to induce mammary gland tumorigenesis. Therefore, inhibition of Cox-2 may represent a mechanism-based chemopreventive approach for carcinogenesis.
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PMID:Overexpression of cyclooxygenase-2 is sufficient to induce tumorigenesis in transgenic mice. 1127 47

Tissue inhibitors of matrix metalloproteinase (TIMPs) are multifunctional proteins with both matrix metalloproteinase (MMP) inhibitory effects and growth-regulatory activity. TIMPs inhibit MMP activity, suggesting a use for cancer gene therapy. However, here we report that systemic administration of human TIMP-4 by electroporation-mediated i.m. injection of naked TIMP-4 DNA stimulates tumorigenesis of human breast cancer cells in nude mice. Consistent with tumor stimulation, TIMP-4 up-regulates Bcl-2 and Bcl-X(L) protein. TIMP-4 also inhibits apoptosis in human breast cancer cells in vitro and mammary tumors in vivo. A synthetic MMP inhibitor BB-94 did not have such antiapoptotic effect. Analysis of TIMP-4 expression in human mammary specimens indicates that TIMP-4 protein is increased in mammary carcinoma cells compared with normal mammary epithelial cells. These data indicate an antiapoptotic activity in breast cancer cells and a tumor-stimulating effect of TIMP-4 when administrated systemically.
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PMID:Stimulation of mammary tumorigenesis by systemic tissue inhibitor of matrix metalloproteinase 4 gene delivery. 1128 97

Ovarian cancer is among the most lethal cancers in women because of its high metastatic potential and lack of response to therapy. An experimental model to study this disease was developed using a transformed granulosa cell line expressing a mutant p53 and Ha-ras. When injected into the ovary of nude mice in the presence of laminin-1, tumors develop in the ovary and peritoneum and metastasize to various organs, leading to death within 21 days. In contrast, when cells were injected in the presence of gelatin, development of tumors was slower and no metastases were observed by day 21. Here we investigated the possible mechanism by which laminin-1 exerts its promotion of tumorigenesis and metastasis. Cells were co-injected with laminin-1 and active laminin peptides from the alpha1; (A13: RQVFQVAYIIIKA, A12: WVTVTLDL RQVFQ, AG73: LQVQLSIR, IKVAV) and beta1 (YIGSR) chains. Ovarian tumor growth and metastasis were increased in the presence of laminin-1 plus either AG73 peptide, IKVAV, or A13, and were significantly reduced in the presence of A12 or YIGSR. Expression of Bcl-2 and Mdm2 was higher by 3.5- and about 100-fold, respectively, in ovarian tumors grown in the presence of laminin compared to tumors grown in the presence of gelatin. Moreover, peptides A13 and AG73 further elevated Bcl-2 expression by 6- and 7-fold respectively, while IKVAV yielded expression similar to laminin-1. YIGSR and A12 reduced the expression of Bcl-2 by 7- and 3-fold, respectively, compared to treatment with laminin-1. A13 and AG73 increased Mdm2 expression by 1.8- and 1.3-fold, respectively, while IKVAV, A12, and YIGSR were without effect. Thus, laminin-1 exerts its proliferative effect on the development of ovarian tumors via upregulation of survival genes such as Bcl-2 and Mdm2. Peptides A13 and AG73 (which increased tumor growth and spread) enhance the expression of these genes and A12 and YIGSR (which decrease tumor growth and spread) attenuate their expression. IKVAV probably enhances tumor growth and metastasis by another mechanism.
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PMID:Role of laminin in ovarian cancer tumor growth and metastasis via regulation of Mdm2 and Bcl-2 expression. 1129 35

Our studies on the relationships among the lymphoid system, apoptosis and apoptosis-related proteins (ARP) in human ovarian benign cysts, borderline tumors, and carcinomas are reviewed and analyzed. Fas and Fas ligand are expressed in 50% to 80% of the epithelial cells in all studied tumors. Many bcl-2-positive tumor epithelial cells are seen in benign cysts and they disappear as tumorigenesis progresses, whereas p53 protein is found only in borderline tumors and in carcinomas. Many exceptions to the opinion that bcl-2 inhibits apoptosis and p53 promotes it are encountered. Bcl-2 is lacking in epithelial cells of mucoid tumors of all grades, and its absence does not stimulate their apoptosis. P53 protein is absent from most lymphocytes, macrophages and epithelial tumor cells, nevertheless, they undergo apoptosis. Indeed, in many tumors apoptosis is regulated without the participation of bcl-2 and p53. Different components of the immune system become active during different stages of tumor development. The weak reaction of T-cell killers and macrophages is typical in benign cysts. In borderline tumors, the activity of T-cell killers increases in the parenchyma, and that of T helpers and macrophages in the stroma. In carcinomas with high lymphoid infiltration, a strong reaction of macrophages and T cell killers in the tumoral parenchyma as well high reaction of T helpers and B lymphocytes in the stroma are typical. Apoptosis that should protect against tumor also stimulates apoptotic death of lymphocytes and macrophages, and this has catastrophic consequences, as seen in weakly infiltrated carcinomas. In conclusion, our studies indicate that during malignancy the major task of the immune system is curtailment and control of tumorigenesis.
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PMID:The immune system, apoptosis and apoptosis-related proteins in human ovarian tumors (a review). 1129 42

The transcription factor E2F1 is a key component of cell cycle that acts to transactivate genes required for S phase entry. Thus, it plays an important role in cellular proliferation, oncogenesis and differentiation. In order to investigate its potential implication in human lung carcinogenesis, we studied E2F1 protein expression by Western blotting and immunohistochemistry in a series of 58 human lung tumours of all histological types. We showed that E2F1 product was overexpressed in 92% (24/26) of small cell lung carcinoma (SCLC) and in 50% (5/10) of large cell neuroendocrine carcinoma (LCNEC) whereas it was undetectable in 90% (10/11) of adenocarcinoma and 82% (9/11) of squamous carcinoma when compared to corresponding normal lung. No amplification was found but an increase in E2F1 mRNA expression was detected in 75% (18/24) of SCLC overexpressing E2F1 product. In these tumours and in contrast with NSCLC, upregulation of E2F1 product was associated with its nuclear accumulation and with overexpression of several of its target-genes. Moreover, E2F1 overexpression in NE lung tumours was significantly associated with a high KI67 index (P<0.0001) as well as a Bcl-2:Bax ratio >1 (P<0.001). Overall, these results demonstrate a distinct pattern of E2F1 expression in human lung tumours and suggest that its deregulation could be involved in the carcinogenesis of SCLC.
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PMID:Distinct pattern of E2F1 expression in human lung tumours: E2F1 is upregulated in small cell lung carcinoma. 1131 16


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