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)

The hormonally active form of vitamin D3, 1,25-dihydroxyvitamin D3, and its two analogues, EB 1089 and CB 1093, are novel putative anticancer agents with an interesting profile of induction of growth inhibition, differentiation, and apoptosis in tumor cells. To study the signaling pathways mediating these events, we used two human breast cancer cell lines: MCF-7 cells, expressing a wild-type p53 tumor suppressor protein, and T47D cells, lacking a functional p53. Vitamin D compounds induced a growth arrest followed by apoptosis in both cell lines at concentrations ranging from 1 to 100 nM, indicating that p53 is not necessary for growth-inhibitory effects induced by vitamin D compounds. Surprisingly, apoptosis induced by these compounds occurred also independently of known caspases. Inhibition of caspase activation by overexpression of a cowpox-derived caspase inhibitor CrmA or by addition of inhibitory peptides acetyl-Asp-Glu-Val-Asp-aldehyde (200 microM), acetyl-Ile-Glu-Thr-Asp-aldehyde (50 microM), and Z-Val-Ala-D,L-Asp-fluoromethylketone (1 microM) showed no effect on the induction of growth arrest or apoptosis by vitamin D compounds under assay conditions in which apoptosis induced by TNF or staurosporine was effectively inhibited. Moreover, overexpression of caspase-3 in MCF-7 cells had no sensitizing effect to vitamin D compounds, and neither caspase-3-like protease activity nor cleavage of a caspase substrate poly(ADP)ribose polymerase was detected in lysates from apoptotic cells following the treatment with these compounds. Contrary to CrmA, overexpression of an antiapoptotic protein Bcl-2 in MCF-7 cells conferred a nearly complete protection from apoptosis induced by vitamin D compounds. Taken together, these data indicate that vitamin D compounds induce apoptosis via a novel caspase- and p53-independent pathway that can be inhibited by Bcl-2. This may prove useful in the treatment of tumors that are resistant to therapeutic agents that are dependent on the activation of p53 and/or caspases.
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PMID:Apoptosis induced by vitamin D compounds in breast cancer cells is inhibited by Bcl-2 but does not involve known caspases or p53. 1051 95

While the role of vitamin D in bone and mineral metabolism has been investigated extensively, the role of the vitamin D receptor in other tissues is less well understood. 1,25-Dihydroxyvitamin D3 (calcitriol) can act as a differentiating agent in normal tissues and can inhibit the growth of many cancer cell lines including LNCaP prostate cancer cells. We have shown previously that calcitriol causes LNCaP cell accumulation in the G0/G1 phase of the cell cycle. In this study, we demonstrate that calcitriol also induces apoptosis of LNCaP cells. The calcitriol-induced apoptosis is accompanied by a down-regulation of Bcl-2 and Bcl-X(L) proteins, both of which protect cells from undergoing apoptosis. Other proteins important in apoptotic control, Bax, Mcl-1, and Bcl-X(S), are unaffected by calcitriol treatment. We find that overexpression of Bcl-2 blocks calcitriol-induced apoptosis and reduces, but does not eliminate, calcitriol-induced growth inhibition. We conclude that both regulation of cell cycle and the apoptotic pathway are involved in calcitriol action in prostate cancer cells.
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PMID:Calcitriol-induced apoptosis in LNCaP cells is blocked by overexpression of Bcl-2. 1061 17

Vitamin D3 is believed to reduce the risk of colon cancer, and serum levels inversely correlate with colorectal cancer incidence. The active metabolite, 1alpha,25-dihydroxyvitamin D3, has previously been shown to inhibit growth and promote differentiation of colon cancer cells. The vitamin D analogue, EB1089, is currently under clinical trial in a variety of cancers because of its growth-inhibitory effects in vitro and reduced hypercalcemic effects in vivo. The mechanism of growth inhibition by EB1089, however, remained to be determined. In this study we examined the effects of alpha,25-dihydroxyvitamin D3 and EB1089 on five colorectal tumor cell lines (two adenoma and three carcinoma) to determine the mechanism of growth inhibition and to ascertain whether premalignant adenoma cells were responsive to these agents. 1alpha,25-Dihydroxyvitamin D3 and EB1089 induced p53-independent apoptosis in adenoma and carcinoma cell lines in a dose-dependent manner between 10(-10) and 10(-6) M. EB1089, as well as inducing apoptosis, increased the proportion of cells in the G1 phase, particularly in the adenoma cell lines. In two of the three carcinoma cell lines (SW620 and PC/JW), levels of apoptosis induced by EB1089 were similar or greater than those induced by 1alpha,25-dihydroxyvitamin D3. Although the carcinoma cell line HT29 was relatively resistant to apoptosis induced by EB1089 compared with 1alpha,25-dihydroxyvitamin D3, EB1089 markedly inhibited cell yields. These observations offer promise for the clinical use of EB1089. To determine whether the induction of apoptosis by 1alpha,25-dihydroxyvitamin D3 and EB1089 was potentially via a differentiation pathway, alkaline phosphatase activity was measured as a marker of differentiation. Induction of alkaline phosphatase was observed in the floating apoptotic cells as well as in the adherent population. A link between the induction of differentiation and apoptosis by 1alpha,25-dihydroxyvitamin D3 and EB1089 is suggested by the occurrence of apoptosis subsequent to the induction of differentiation. To investigate the molecular pathway to apoptosis induction, members of the Bcl-2 family of proteins were examined (Bcl-2, Bcl-x, Bax, and Bak). Decreased Bcl-2 was observed in some cell lines, particularly in response to EB1089, but was not essential for apoptosis. Levels of the proapoptotic protein Bak, however, were consistently increased in all of the five cell lines in association with apoptosis induced by either agent. The results implicate Bak protein in the induction of apoptosis by 1alpha,25-dihydroxyvitamin D3 or its analogue EB1089. The ability of EB1089 to induce apoptosis in colorectal carcinoma cells suggests that this or other vitamin D analogues may prove clinically effective for the treatment of colorectal cancer. Furthermore, the fact that it induces cell cycle arrest and apoptosis in the premalignant adenoma cells may suggest an application in colorectal cancer chemoprevention.
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PMID:Apoptosis is induced by the active metabolite of vitamin D3 and its analogue EB1089 in colorectal adenoma and carcinoma cells: possible implications for prevention and therapy. 1078 99

Most breast cancer patients treated with anti-oestrogens will eventually develop resistance towards treatment. Therefore it is important to find new therapeutic agents effective for treatment of patients relapsing on anti-oestrogen. The vitamin D analogue EB1089 (Seocalcitol(TM)) is a promising new agent for treatment of breast cancer patients with advanced disease, and in this study we show that two different anti-oestrogen-resistant human breast cancer cell lines are more sensitive towards treatment with EB1089, than the parent MCF-7 cell line. The two resistant cell lines both express a lower content of the anti-apoptotic protein Bcl-2, and we suggest that this may explain the higher sensitivity towards EB1089. The importance of Bcl-2 for response to EB1089 is supported by our observation that oestradiol abrogates the effect of EB1089 in cell lines which increase Bcl-2 in response to oestradiol treatment. Overall these results indicate that treatment with Seocalcitol(TM)may prove effective when patients become refractory to anti-oestrogen therapy, and that Bcl-2 may be used as a predictive marker.
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PMID:Anti-oestrogen resistant human breast cancer cell lines are more sensitive towards treatment with the vitamin D analogue EB1089 than parent MCF-7 cells. 1123 91

1,25-dihydroxyvitamin D3[1,25(OH)2D3] is a well-known potent regulator of cell growth and differentiation and there is recent evidence of an effect on cell death, tumour invasion and angiogenesis, which makes it a candidate agent for cancer regulation. The classical synthetic pathway of 1,25(OH)2D3 involves 25- and 1 alpha-hydroxylation of vitamin D3, in the liver and kidney, respectively, of absorbed or skin-synthesized vitamin D3. There is recent focus on the importance in growth control of local metabolism of 1,25(OH)2D3, which is a function of local tissue synthetic hydroxylases and particularly the principal catabolizing enzyme, 24-hydroxylase. The classical signalling pathway of 1,25(OH)2D3 employs the vitamin D nuclear receptor (VDR), which is a transcription factor for 1,25(OH)2D3 target genes. Effects of this pathway include inhibition of cellular growth and invasion. Cytoplasmic signalling pathways are increasingly being recognized, which similarly may regulate growth and differentiation but also apoptosis. 1,25(OH)2D3 has a major inhibitory effect on the G1/S checkpoint of the cell cycle by upregulating the cyclin dependent kinase inhibitors p27 and p21, and by inhibiting cyclin D1. Indirect mechanisms include upregulation of transforming growth factor-beta and downregulation of the epidermal growth factor receptor. 1,25(OH)2D3 may induce apoptosis either indirectly through effects on the insulin-like growth receptor and tumour necrosis factor-alpha or more directly via the Bcl-2 family system, the ceramide pathway, the death receptors (e.g. Fas) and the stress-activated protein kinase pathways (Jun N terminal kinase and p38). Inhibition of tumour invasion and metastasis potential has been demonstrated and mechanisms include inhibition of serine proteinases, metalloproteinases and angiogenesis. The lines of evidence for an effect of vitamin D3 in systemic cancer are the laboratory demonstration of relevant effects on cellular growth, differentiation, apoptosis, malignant cell invasion and metastasis; epidemiological findings of an association of the occurrence and outcome of cancers with derangements of vitamin D3/1,25(OH)2D3 and the association of functional polymorphisms of the VDR with the occurrence of certain cancers. In addition, vitamin D3 analogues are being developed as cancer chemotherapy agents. There is accumulating evidence that the vitamin D3/1,25(OH)2D3/VDR axis is similarly important in malignant melanoma (MM). MM cells express the VDR, and the antiproliferative and prodifferentiation effects of 1,25(OH)2D3 have been shown in cultured melanocytes, MM cells and MM xenografts. Recently, an inhibitory effect on the spread of MM cells has been demonstrated, low serum levels of 1,25(OH)2D3 have been reported in MM patients and the VDR polymorphisms have been shown to be associated with both the occurrence and outcome of MM. The relationship between solar irradiation and MM is more complex than for the systemic cancers. As in other cancers, there is evidence of a protective effect of vitamin D3 in MM, but ultraviolet radiation, which is a principal source of vitamin D3, is mutagenic. Further work is necessary on the influence of serum vitamin D3 levels on the occurrence and prognosis of MM, the effects of sun protection measures on serum vitamin D3 levels in temperate climates and epidemiological studies on geographical factors and skin type on the prognosis of MM. Meanwhile, it would seem mandatory to ensure an adequate vitamin D3 status if sun exposure were seriously curtailed, certainly in relation to carcinoma of breast, prostate and colon and probably also MM.
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PMID:Vitamin D and systemic cancer: is this relevant to malignant melanoma? 1217 89

We have recently found that analog V (BXL-353, a calcitriol analog) inhibits growth factor (GF)-stimulated human benign prostate hyperplasia (BPH) cell proliferation by disrupting signal transduction, reducing Bcl-2 expression, and inducing apoptosis. We now report that BXL-353 blocks in vitro and in vivo testosterone (T) activity. BPH cells responded to T and dihydrotestosterone (DHT) with dose-dependent growth and reduced apoptosis. Exposure of BPH cells to BXL-353 significantly antagonized both T- and DHT-induced proliferation and induced apoptosis, even in the presence of T. To verify whether BXL-353 reduced prostate growth in vivo, we administered it orally to either intact or castrated rats, supplemented with T enanthate. Nonhypercalcemic doses of BXL-353 time- and dose-dependently reduced the androgen effect on ventral prostate weight, similarly to finasteride. Comparable results were obtained after chronic administration of BXL-353 to intact rats. Clusterin (an atrophy marker) gene and protein were up-regulated by BXL-353 in rat prostate, and nuclear fragmentation was widely present. The antiandrogenic properties of BXL-353 did not interfere with pituitary and testis function, as assessed by serum determination of rat LH and T. BXL-353 did not compete for androgen binding to BPH homogenates and failed to inhibit 5alpha-reductase type 1 and type 2 activities. In conclusion, BXL-353 blocks in vitro and in vivo androgen-stimulated prostate cell growth, probably acting downstream from the androgen receptor, without affecting calcemia or sex hormone secretion. BXL-353 and other vitamin D(3) analogs might thus represent an interesting class of compounds for treating patients with BPH.
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PMID:Inhibition of spontaneous and androgen-induced prostate growth by a nonhypercalcemic calcitriol analog. 1281 May 61

The active vitamin D metabolite 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) and related substances have previously been tested in tissue culture and animal models of retinoblastoma for their use as anti-tumor drugs. However, despite of the potential therapeutic value, the molecular mechanisms through which 1,25-(OH)(2)D(3) inhibits the growth of retinoblastoma cells are incompletely understood. To elucidate possible signalling pathways for the anti-proliferative action of vitamin D compounds in retinal tumor cells, we analyzed the effect of 1,25-(OH)(2)D(3) and its synthetic analogue KH1060 on the growth of human retinoblastoma-derived Y79 cells. Vitamin D receptor (VDR) mRNA was detected by reverse transcription PCR in Y79 cells and in tissue specimens of human retinoblastoma. VDR transcripts were confirmed at the protein level by strong immunostaining of solid retinal tumors for VDR. Incubation with 1,25-(OH)(2)D(3) and KH1060 (10(-10)-10(-6)moll(-1)) decreased the number of Y79 cells in a timely and dose-dependent manner. Treatment with 1,25-(OH)(2)D(3) (10(-10)moll(-1)) for 24 hr caused cell cycle arrest in the G0/1 phase. Apoptosis of Y79 cells in response to 1,25-(OH)(2)D(3) was demonstrated by the means of TdT-dUTP terminal nick-end labelling (TUNEL), annexin V staining, and detection of DNA fragmentation on agarose gels. 1,25-(OH)(2)D(3)-induced programmed death of Y79 cells was accompanied by a concentration-dependent increase in Bax protein and a reduction in Bcl-2 content. These findings suggest that 1,25-(OH)(2)D(3) inhibits the growth of retinoblastoma cells by causing cell cycle arrest and apoptosis. 1,25-(OH)(2)D(3)-induced programmed death of retinoblastoma cells appears to involve reciprocal changes in Bcl-2 and Bax proteins.
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PMID:1,25-dihydroxyvitamin D3-induced apoptosis of retinoblastoma cells is associated with reciprocal changes of Bcl-2 and bax. 1282 82

Development of resistance to antihormonal therapy is a major problem in the treatment of breast cancer patients. Metastatic tumors, which progress after a period of response to treatment, often respond to second line endocrine treatment, but eventually develop estrogen independent growth. Vitamin D analogues are promising new drugs, using alternative mechanisms to inhibit growth of breast cancer cells. The sensitivity to antiestrogens and vitamin D analogues has been proposed to be inverse, indicating that the sensitivity to vitamin D analogues might increase after development of antiestrogen resistance and vice versa. In this study, the inverse sensitivity between antiestrogens and the vitamin D analogue EB1089 was examined in antiestrogen and vitamin D resistant breast cancer cell lines. The majority of the investigated antiestrogen resistant cell lines had increased sensitivity to treatment with the vitamin D analogue EB1089. In addition, growth of a vitamin D resistant cell line was more inhibited by the pure antiestrogen ICI 182,780 than the growth of the parental cells, indicating that the compounds may be used sequentially. An association between the expression level of the vitamin D receptor (VDR) and EB1089 sensitivity was observed, suggesting that VDR is a possible predictive marker for response to vitamin D treatment. Valuation of Bcl-2 gene expression may be useful in combination with VDR to predict the outcome of treatment with EB1089. Furthermore, we observed a synergistic growth inhibition and an abrogated development of resistance upon combined treatment with ICI 182,780 and EB1089. Therefore, antiestrogens and vitamin D analogues may also be used as combined treatment for breast cancer patients in the future.
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PMID:Sequential versus combined treatment of human breast cancer cells with antiestrogens and the vitamin D analogue EB1089 and evaluation of predictive markers for vitamin D treatment. 1503 97

Apoptosis plays an important role in the regulation of bone turnover. Previously, we showed that 1,25(OH)2D3, the active form of vitamin D, may increase osteoblast survival by inhibiting apoptosis induced by serum deprivation. Human osteoblasts express the Fas receptor on their surface and its interaction with Fas ligand has been closely associated with human osteoblast apoptosis. To investigate the mechanism of 1,25(OH)2D3 inhibition of apoptosis in osteoblasts isolated from human calvaria, cells were exposed to Fas antibody. Visualization of apoptotic cells using annexin V revealed a significant decrease in apoptosis at 48 h in the presence of 1,25(OH)2D3 (14 +/- 4%, P < 0.04) compared with non-treated cells (52 +/- 4%). Furthermore, flow cytometric analysis of TUNEL-labeled osteoblasts showed a significant decrease in apoptotic cells in 1,25(OH)2D3-treated cultures (12 +/- 2%) at 48 h compared with non-treated cultures (44 +/- 3%, P < 0.04). Additionally, cells treated with 1,25(OH)2D3 survived longer as found by MTS analysis. To further explore the mechanism of 1,25(OH)2D3-mediated inhibition of apoptosis, we examined the changes in activation of death domain proteins, cleavage of caspases and mitochondrial regulators of apoptosis by Western blot analysis. A significant inhibition of caspase-8 cleavage and activity in 1,25(OH)2D3-treated cells was observed in conjunction with a decrease in the expression of the proapoptotic protein Bax with a significant increase in the expression of antiapoptotic protein Bcl-2. Furthermore, the levels of p21Cip1/WAF1, which inhibits the cleavage of caspase-8, was found to be highly induced in 1,25(OH)2D3-treated cells. In summary, these results demonstrate that the anti-apoptotic effect of 1,25(OH)2D3 in human osteoblasts after the activation of Fas-ligand is mediated by the regulation of components of both the mitochondrial and Fas-related pathways.
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PMID:Vitamin D inhibits Fas ligand-induced apoptosis in human osteoblasts by regulating components of both the mitochondrial and Fas-related pathways. 1520 41

The aim of this study was to investigate whether the vitamin D analogue KH 1060 could exert a suppressive action on Tumor necrosis factor-alpha (TNF-alpha). The chimeric anti-TNF-alpha monoclonal antibody (anti-TNF), alone or in combination with KH 1060, was also used. KH 1060 (0.01, 0.1, 1 nM) significantly inhibited cell proliferation, determined after 5 days by [3H]thymidine incorporation, when peripheral blood mononuclear cells (PBMC), obtained from healthy subjects, were stimulated with phytohaemagglutinin (PHA) and incubated for 24 h in the absence and in the presence of lipopolysaccharide (LPS). In the same experimental conditions, anti-TNF exerted a significant inhibition on PBMC proliferation, at the lowest doses (0.001, 0.01 microg/ml) in the absence of LPS, and at 0.001, 1, 10 microg/ml in its presence. A synergistic inhibition was registered combining KH 1060 and anti-TNF, at well-defined concentrations. 0.1 nM KH 1060 produced a significant decrease in TNF-alpha levels, determined by ELISA, although less remarkable than in the presence of anti-TNF. This decrease was synergistic, associating 0.1 nM KH 1060 and 0.1 microg/ml anti-TNF. VDR protein levels were increased by 0.1 nM KH 1060, 0.1 microg/ml anti-TNF or their combination. The protein levels of two oncogenes, Bax and Bcl-2, remained unchanged, when PBMC were incubated with KH 1060, anti-TNF or their combination in the absence of LPS, while, in its presence, an increase was registered. The demonstrated anti-TNF-alpha effect of KH 1060 may suggest for this compound an immunosuppressive action and the possibility to synergistically act with other drugs.
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PMID:Biochemical effects of KH 1060 and anti-TNF monoclonal antibody on human peripheral blood mononuclear cells. 1571 Mar 34


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