CCAAT/enhancer-binding protein delta: a molecular target of 1,25-dihydroxyvitamin D3 in androgen-responsive prostate cancer LNCaP cells

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3], the active metabolite of vitamin D3, inhibits the proliferation of prostate cancer cells. However, the molecular mechanisms by which 1,25(OH)2D3 inhibits the proliferation of these cells remain to be fully elucidated. In this study, we used microarray technology to identify target genes of 1,25(OH)2D3 in androgen-responsive prostate cancer LNCaP cells. 1,25(OH)2D3 up-regulated CCAAT/enhancer-binding protein delta (C/EBPdelta) by approximately 5-fold in these cells. Knockdown of C/EBPdelta expression by RNA interference showed that C/EBPdelta is essential for the significant growth inhibition of LNCaP cells in response to 1,25(OH)2D3 treatment. Moreover, we found that 1,25(OH)2D3 induced C/EBPdelta in other cancer cells, including the estrogen receptor (ER)-expressing MCF-7 and T47D breast cancer cells that are sensitive to the growth inhibitory effects of 1,25(OH)2D3. On the other hand, 1,25(OH)2D3 was not able to induce C/EBPdelta in either androgen receptor-negative PC-3 and DU145 or ER-negative breast cancer MDA-MB-231 cells that were relatively resistant to growth inhibition by 1,25(OH)2D3. Furthermore, forced expression of C/EBPdelta in prostate cancer LNCaP as well as breast cancer MCF-7 and T47D cells dramatically reduced their clonal growth. Taken together, forced expression of C/EBPdelta in cancer cells may be a promising therapeutic strategy.     

1,25-dihydroxyvitamin D3 and retonic acid analogues induce differentiation in breast cancer cells with function- and cell-specific additive effects

Vitamin D₃ derivatives and retinoids can induce cell cycle arrest, differentiation and cell death in many cell lines. These compounds can act cooperatively in some of their functions and may be of potential use either individually or in combination in the treatment of breast cancer. The effects of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), all-trans retinoic acid (ATRA) and several analogues were evaluated on malignant phenotypic traits of breast cancer cell lines MCF-7, T-47D and MDA-MB-231. Both 1,25(OH)₂D₃ and ATRA caused a decrease in anchorage independent colony formation in MCF-7 and T-47D cells in a dose-dependent manner. The effects of 1,25(OH)₂D₃ 10^–10 and 10^–9M were synergistic with ATRA 10^–8M in T-47D cells but were antagonistic in both MCF-7 and in T-47D cells at most concentrations. Both 1,25(OH)₂D₃ and ATRA individually induced an accumulation of MCF-7 cells in the G₁ phase of the cell cycle and an associated increase in p21^WAF1/Cip1, p27^Kipl and a dephosphorylation of Rb but the effects were not additive. Both compounds inhibited the invasive capacity of MDA-MB-231 cells. 1,25(OH)₂D₃ but not ATRA caused an increase in E-cadherin levels in MDA-MB-231 cells. These two functions were not additive. The compounds 1,25(OH)₂D₃, a noncalcemic analogue 1,25(OH)₂-16-ene-23-yne-D₃, ATRA, AGN195183, an RAR-specific agonist, and AGN190168 (tazarotene), an RAR-selective agonist, induced differentiation as determined by measurements of lipid droplet formation. The individual effects of 1,25(OH)₂-16-ene-23-yne-D₃ combined with ATRA or with tazarotene at 10^–9M each were additive in MCF-7 and MDA-MB-231 cells on lipid formation. The data demonstrate that both 1,25(OH)₂D₃, ATRA, and selected analogues induce a more differentiated phenotype in breast cancer cells with additive effects that are function- and cell-specific.     

细胞周期相关因子与乳腺细胞的癌变及生物学特性的相关性研究

目的：研究正常乳腺上皮细胞与乳腺癌细胞之间以及不同恶性程度的乳腺癌细胞之间的细胞周期相关因子的表达异同。方法：采用Western印迹法检测正常乳腺细胞株AG11132A、ER阳性和乳腺癌细胞株MCF－7及ER阴性的乳腺癌细胞株MDA－MB－231之间细胞周期蛋白D1、E及P21蛋白表达的异同及与其生物学特性的关系。结果：（1）正常乳腺上皮细胞株高表达P21蛋白,低表达周期蛋白E。与正常细胞相比,乳腺癌细胞株MCF－7、MDA－MB－231细胞高表达周期蛋白E,其中表达的周期蛋白E中存在异常的你分子量周期蛋白E成分,而正常乳腺上皮细胞不表达这种异常 的周期蛋白E。（2）在乳腺癌细胞株之间,相对ER阳性的MCF－7细胞,ER阴性的MDA－MB－231细胞则高表达周期蛋白E,基本无表达P21蛋白。结论L（1）正常细胞与这间、相对低恶性程度的民相对高恶性和蔼的癌细胞之间的差别是多环节的、质和量异常导致的结果;（2）周期蛋白E及P21均可反映乳腺癌细胞的增殖活性和恶性程度,可能是乳腺癌的临床预后指标。     

Action of low calcemic 1alpha,25-dihydroxyvitamin D3 analogue EB1089 in head and neck squamous cell carcinoma

BACKGROUND: 1alpha,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] and its analogues inhibit growth of various types of cancer cells. Although the therapeutic potential of 1,25(OH)(2)D(3) is limited by its tendency to induce hypercalcemia, analogues such as EB1089 are potent inhibitors of cell growth and exhibit reduced calcemic effects. We analyzed the antiproliferative and calcemic effects of EB1089 in tissue culture and animal models of head and neck squamous cell carcinoma (SCC) to investigate its potential as a chemotherapeutic/chemopreventive agent. METHODS: The effects of 1,25(OH)(2)D(3) and EB1089 on cell growth and expression of p21(WAF1/CIP1) and p27(KIP1), which encode cyclin-dependent kinase inhibitors, and a novel target, gadd45alpha, a growth-arrest and DNA-damage gene, were monitored in cultured murine AT-84 SCC cells. The effects of these agents on AT-84 cell growth in vitro and on growth of AT-84 tumors in syngeneic C3H mice were monitored; treatment started at the time of tumor implantation (early tumor model) or after 12 days (late tumor model). Weight and serum calcium levels were also monitored in these animals. All P values were two-sided. RESULTS: Both 1,25(OH)(2)D(3) and EB1089 arrested proliferation of AT-84 cells in G(0)/G(1) phase, inhibited p21(WAF1/CIP1) expression, and induced expression of p27(KIP1) protein. 1,25(OH)(2)D(3) also enhanced the expression of gadd45alpha, apparently by a p53-independent mechanism. There was a statistically significant decrease in tumor growth for 1,25(OH)(2)D(3)-treated mice (P<.001 for early tumor model) and EB1089-treated mice (P<.001 and P =.001 for early and late tumor models, respectively). Unlike 1,25(OH)(2)D(3), EB1089 did not induce cachexia or hypercalcemia. The effects of 1,25(OH)(2)D(3) and EB1089 on expression of p21(WAF1/CIP1) and GADD45alpha were similar in tumors and in vitro. CONCLUSIONS: EB1089 completely inhibited growth of AT-84 SCC cells at nanomolar concentrations, reduced tumor growth, and did not have calcemic effects. Our results support continued investigation of EB1089 as a chemopreventive/chemotherapeutic agent for head and neck SCC.     

Inhibition of angiogenesis as a mechanism for inhibition by 1alpha-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 of colon carcinogenesis induced by azoxymethane in Wistar rats.

The effects of 1alpha-hydroxyvitamin D3[1alpha(OH)D3] and 1,25-dihydroxyvitamin D3[1,25(OH)2D3] on the incidence of colon tumors induced by azoxymethane and on the labeling index and angiogenesis of colon tumors were investigated in Wistar rats. Rats received 10 weekly injections of 7.4 mg/kg body weight of azoxymethane and i.p. injections of 1alpha(OH)D3 and 1,25(OH)2D3 at lower and higher doses every other day for 45 weeks. Prolonged administration of both 1alpha(OH)D3 and 1,25(OH)2D3 at a higher dose significantly reduced the incidence of colon tumors in week 45. However, administration of 1alpha(OH)D3 or 1,25(OH)2D3 had little or no effect on the histologic type of colon tumors and cancers. Administration of 1alpha(OH)D3 and 1,25(OH)2D3 at higher doses significantly decreased the labeling index, the immuno-histochemical staining for vascular endothelial growth factor and microvessel counts in colon tumors. Our findings suggest that both 1alpha(OH)D3 and 1,25(OH)2D3 inhibit development of colon tumors. A possible mechanism of inhibition of colon carcinogenesis by 1alpha(OH)D3 and 1,25(OH)2D3 is the inhibition of angiogenesis as well as an anti-proliferative effect.     

Pancreatic cancer cells express 25-hydroxyvitamin D-1 alpha-hydroxylase and their proliferation is inhibited by the prohormone 25-hydroxyvitamin D3

The steroid hormone 1,25-dihydroxyvitamin D(3), [1,25(OH)(2)D(3), calcitriol], the active metabolite of vitamin D, exerts pleiotropic antitumor effects against several malignancies. However, the clinical use of this hormone is limited by hypercalcemia. 25-Hydroxyvitamin D(3), the prohormone of 1,25(OH)(2)D(3), is hydroxylated to the active hormone by the enzyme 25-hydroxyvitamin-1-alpha-hydroxylase [1 alpha(OH)ase]. 1 alpha(OH)ase is found primarily in the kidney, but also is expressed in the prostate, colon and other tissues. Using immunohistochemistry, we report that 1 alpha(OH)ase is highly expressed in both normal and malignant pancreatic tissue. Expression of this enzyme and enzymatic activity was also detected in four pancreatic tumor cell lines. 25(OH)D(3) inhibited the growth of three of four pancreatic cell lines in a manner that correlated with the level of induction of the cyclin-dependent kinase inhibitors p21 and p27 and with the induction of cell cycle arrest at the G(1)/S checkpoint. The growth of a cell line stably transfected with a mutant Ki-ras allele and of a second cell line with an endogenous Ki-ras activating mutation was also inhibited by 25(OH)D(3), indicating that activating Ki-Ras mutations, which occur in almost 90% of pancreatic adenocarcinomas, do not interfere with the growth-inhibitory effects of 25(OH)D(3). The expression of 1 alpha(OH)ase in normal and malignant pancreatic tissue and the antiproliferative effects of the prohormone in these cells, suggest that 25(OH)D(3) may offer possible therapeutic and chemopreventive options for pancreatic cancer.     

Expression of a novel factor, com1, is regulated by 1,25-dihydroxyvitamin D3 in breast cancer cells

Tumor cells and their surrounding microenvironment produce a variety of factors that promote tumor growth and metastasis. We recently identified a nuclear factor, termed com1, that is up-regulated in human breast carcinoma cells on formation of experimental metastatic tumors and is assumed to act as a growth-promoting factor in breast cancer. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] is a potent inhibitor of growth in breast cancer both in vitro and in vivo. We compared the growth-regulatory mechanisms of nontumorigenic and estrogen-dependent MCF-7 cells with those of the tumorigenic and tamoxifen-resistant subline MCF7/ LCC2 in the presence of 1,25(OH)2D3. Proliferation of MCF7/LCC2 cells, which revealed constitutive com1 expression, was inhibited by 1,25(OH)2D3 (10(-7) M). This was strongly associated with cell cycle arrest in G1 phase, consistent with accumulation of the hypophosphorylated form of the retinoblastoma protein as well as the induction of the cyclin-dependent kinase inhibitor p21. These cell cycle events were preceded by a transient up-regulation (5-8-fold) of com1 mRNA. Furthermore, clonal growth of the MCF7/LCC2 cells was also inhibited by 1,25(OH)2D3 (10(-7) M), and when the com1-negative MCF-7 cells were stably transfected with com1, the resulting MCF7/com1 cells showed a significant decrease in colony formation. These results seem to indicate that rather than promoting growth, com1 may participate in the regulatory pathway involved in cellular growth inhibition when recruited by inhibitory signals.     

24-Oxo metabolites of vitamin D3 analogues: disassociation of their prominent antileukemic effects from their lack of calcium modulation

The seco-steroid hormone, 1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] inhibits proliferation and induces differentiation of malignant cells including those of the hematopoietic system. The 24-oxo metabolite of 1,25(OH)(2)D(3) also has prominent antiproliferative activities against various cancer cells. We chemically synthesized five novel 24-oxo vitamin D(3) analogues and evaluated their abilities both to inhibit clonal growth and induce differentiation of myeloid leukemia cells and to cause hypercalcemia. The 1alpha,25-dihydroxy-16-ene-D(3) [1,25(OH)(2)-16-ene-D(3)] and 1alpha,25-dihydroxy-16-ene-19-nor-D(3) [1,25(OH)(2)-16-ene-19-nor-D(3)] and their 24-oxo metabolites showed greater potency than 1,25(OH)(2)D(3) in their abilities to inhibit clonal proliferation of HL-60, NB4, and U937 leukemic cell lines as measured by methylcellulose soft-gel assay. Their inhibition of clonal growth was irreversible as analyzed by pulse exposure studies. The synthetic analogues also had greater potency than 1,25(OH)(2)D(3) to induce differentiation of HL-60 and NB4 cells as measured by generation of superoxide, nonspecific esterase production, and induction of CD11b and CD14 cell surface antigens and to increase the proportion of these cells in the G(0)-G(1) phase of the cell cycle. For most assays, the 24-oxo metabolite was slightly more potent than the unmodified analogue, and 50% activity was usually found in the nanomolar range. These analogues and their 24-oxo metabolites also inhibited fresh leukemic cell clonal proliferation. Expression of p27(KIP1), a cyclin-dependent kinase inhibitor that plays an important role in blocking the cell cycle, was found by Western blot analysis to be induced by the analogues and their 24-oxo metabolites in both HL-60 and U937 cells, suggesting a possible mechanism by which these analogues inhibit leukemic growth. Notably, the calcemic activity tested by injections of 1alpha,25-dihydroxy-16-ene-24-oxo-19-nor-D(3) in mice was at least 12-fold less than 1alpha,25(OH)(2)-16-ene-19-nor-D(3). Taken together, chemically synthesized 24-oxo metabolites of 1alpha,25(OH)(2)-16-ene-D(3) and 1alpha,25(OH)(2)-16-ene-19-nor-D(3) irreversibly inhibited proliferation and induced differentiation of acute myeloid leukemia cells with minimal toxicity; these compounds may have a role in the maintenance phase of therapy for acute myeloid leukemia.     

Two novel 14-Epi-analogues of 1,25-dihydroxyvitamin D3 inhibit the growth of human breast cancer cells in vitro and in vivo

The biological activity of two novel 14-epi-analogues of 1,25(OH)2D3, 19-nor-14-epi-23-yne-1,25(OH)2D3 (TX 522) and 19-nor-14,20-bisepi-23-yne-1,25(OH)2D3 (TX 527), is described. Both analogues were at least 10 times more potent than 1,25(OH)2D3 in inhibiting in vitro cell proliferation and had much lower in vivo calcemic effects than 1,25(OH)2D3. Treatment with 1,25(OH)2D3, TX 522, or TX 527 in vitro was accompanied by an accumulation of cells in the G1 phase of the cell cycle. Protein levels of cyclin C and cyclin D1 in in vitro cultures of MCF-7 cells were down-regulated to 50 and 30%, respectively, of control levels at 72 and 120 h after stimulation. Protein levels of p21 and p27 at 72 h were significantly enhanced by 1,25(OH)2D3 and TX 522 but surprisingly not by TX 527. The inability of TX 527 to up-regulate p21 seemed to be cell type specific because p21 was induced in other cell types. Diminished phosphorylation of the retinoblastoma protein after treatment with 1,25(OH)2D3, TX 522, or TX 527 may ultimately contribute to the growth inhibition caused by these compounds. According to the data presented, the induction of apoptosis seemed not to be a major mechanism responsible for the growth-inhibitory effect of 1,25(OH)2D3 and analogues. Both 14-epianalogues significantly retarded tumor progression (40% reduced compared with control mice) in an in vivo model of MCF-7 breast cancer cells established in nude mice. In conclusion, these novel analogues have the eligible profile to be tested as therapeutic agents for the treatment of hyperproliferative diseases such as breast cancer.     

Androgen receptor and vitamin D receptor in human ovarian cancer: growth stimulation and inhibition by ligands

The data suggest that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and androgens are essential for regulation of growth and differentiation in, e.g., human reproductive tissues. We investigated the possible cross-talk between 1,25(OH)2D3 and androgens in the human ovarian cancer cell line OVCAR-3. Our data demonstrate that 1,25(OH)2D3 and androgen (dihydrotestosterone, DHT) regulate the growth of OVCAR-3 cells. Nine days' treatment of OVCAR-3 cells with 100 nM DHT resulted in 48% stimulation of growth, whereas growth inhibition (73%) was observed after treatment with 100 nM 1,25(OH)2D3. The combination of 1,25(OH)2D3 and DHT showed that 1,25(OH)2D3 clearly reduces the growth-stimulatory effect of DHT on OVCAR-3 cells. Moreover, Western blot analysis revealed that these cells contain receptors for 1,25(OH)2D3 (VDR) and androgen (AR). Expression of VDR and AR was up-regulated by their cognate ligands. Up-regulation of AR by 1,25(OH)2D3 and of VDR by DHT provides evidence of cross-talk between 2 signaling pathways in OVCAR-3 cells. We also studied the immuno-histochemical distribution of VDRs and ARs in rat ovaries and human ovarian cancer cases. In rat ovaries, VDRs were observed mainly in granulosa and theca cells and ARs in granulosa cells and surface epithelium. In the human ovarian cancer cases studied, 43% were VDR-positive and 64% AR-positive. Combining the results suggests that the growth of ovarian tissue might be regulated by 1,25(OH)2D3 and androgen.     

The iroquois homeobox gene 5 is regulated by 1,25-dihydroxyvitamin D3 in human prostate cancer and regulates apoptosis and the cell cycle in LNCaP prostate cancer cells.

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3], the most active metabolite of vitamin D3, has significant antitumor activity in a broad range of preclinical models of cancer. In this study, we show that the Iroquois homeobox gene 5 (Irx5) is down-regulated by 1,25(OH)2D3 in human prostate cancer samples from patients randomly assigned to receive weekly high-dose 1,25(OH)2D3 or placebo before radical prostatectomy. Down-regulation of Irx5 by 1,25(OH)2D3 was also shown in the human androgen-sensitive prostate cancer cell line LNCaP and in estrogen-sensitive MCF-7 breast cancer cells. Knockdown of Irx5 by RNA interference showed a significant reduction in LNCaP cell viability, which was accompanied by an increase in p21 protein expression, G2-M arrest, and an increase in apoptosis. The induced apoptosis was partially mediated by p53, and p53 protein expression was increased as a result of Irx5 knockdown. Cell survival was similarly reduced by Irx5 knockdown in the colon cancer cell line HCT 116 and in MCF-7 breast cancer cells, each being derived from clinical tumor types that seem to be inhibited by 1,25(OH)2D3. Overexpression of Irx5 led to a reduction of p21 and p53 expression. This is the first report that Irx5 is regulated by 1,25(OH)2D3 in humans and the first report to show that Irx5 is involved in the regulation of both the cell cycle and apoptosis in human prostate cancer cells. Irx5 may be a promising new therapeutic target in cancer treatment.     

1,25-Dihydroxyvitamin D3 and all-trans-retinoic acid sensitize breast cancer cells to chemotherapy-induced cell death

We investigated the capacity of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and all-trans-retinoic acid (ATRA) to sensitize three breast cancer cell lines to the cell killing effects of paclitaxel (Taxol) and Adriamycin, two chemotherapeutic agents commonly used in the treatment of breast cancer. In tissue culture colony assays, 1,25(OH)2D3 and ATRA were synergistic in inhibiting the clonogenicity of MCF-7 and T-47D cells that expressed estrogen receptor; vitamin D receptor; retinoic acid receptors (RARs) alpha, beta, and gamma; and retinoid X receptors alpha, beta, and gamma but were not additive in MDA-MB-231 cells that lacked expression of estrogen receptor, RARalpha, and RARbeta. The hormones used individually or in combination induced up to 40-50% cell death by a trypan blue exclusion assay in a dose-dependent manner up to concentrations of 10(-7) M in MCF-7 and T-47D cells, more modestly in MDA-MB-231 cells, and not at all in MCF-10 and MCF-12 nontransformed mammary epithelial cells. Pretreating the cancer cell lines with 1,25(OH)2D3 and ATRA individually or in combination for 3 days prior to a 1-h incubation with paclitaxel or Adriamycin decreased the ED50 for inhibition of colony formation or for cell death by trypan blue by up to 2 logs for paclitaxel and up to 1 log for Adriamycin in all three cell lines but had no effect on chemotherapy-induced MCF-12 cell death. The effects of the hormones were synergistic with those of the chemotherapy agents in all of the breast cancer cell lines, generally at the higher concentrations. Cell death took place by apoptosis. To determine one potential reason for the greater potentiation of the effects of paclitaxel than those of Adriamycin, we determined the effects of preincubation of MCF-7 cells on paclitaxel-induced phosphorylation of Bcl-2. Pretreatment of MCF-7 cells with either 1,25(OH)2D3 or ATRA increased the phosphorylation of Bcl-2 by variable concentrations of paclitaxel. These data suggest that pretreatment of breast cancer with 1,25(OH)2D3 or ATRA lowers the threshold for cell killing by chemotherapy agents and may provide a novel treatment option for this disease.     

1,25-二羟基维生素D3对PM2.5所致HBE细胞氧化损伤的保护作用

目的： 探讨1,25-二羟基维生素D₃[1,25-（OH）₂D₃]对细颗粒物（PM_2.5）致人支气管上皮细胞（HBE）氧化损伤的保护作用。方法： 根据处理因素不同将细胞分为4组,溶剂（乙醇）对照组、1,25-（OH）₂D₃干预组、乙醇+PM_2.5染毒组、PM_2.5染毒+1,25-（OH）₂D₃干预组。溶剂对照组细胞用0.1%乙醇处理48 h,1,25-（OH）₂D₃干预组用1×10^-9 mol/L 1,25-（OH）₂D₃处理48 h,乙醇+PM_2.5染毒组用0.1%乙醇溶剂处理24 h后更换为含乙醇的PM_2.5（200 μg/mL）染毒液继续处理24 h,PM_2.5染毒+1,25-（OH）₂D₃干预组用1×10^-9 mol/L 1,25-（OH）₂D₃预处理24 h后更换为含1,25-（OH）₂D₃的PM_2.5（200 μg/mL）染毒液继续处理24 h。染毒结束后,用CCK-8试剂盒测定细胞存活率、丙二醛（MDA）和还原型谷胱甘肽（GSH）/氧化型谷胱甘肽（GSSG）-Glo^TM试剂盒分别测定MDA浓度和GSH/GSSG比值,Western blot实验测定维生素D受体（VDR）、转录因子NF-E2相关因子2（Nrf-2）与血红素加氧酶-1（HO-1）蛋白的表达水平。结果： PM_2.5染毒处理后,HBE细胞的存活率降至80.8%,1,25-（OH）₂D₃预处理24 h后再进行PM_2.5染毒的细胞存活率降低至75.8%。与对照相比,PM_2.5染毒后,HBE细胞MDA浓度显著增加（P < 0.05）,而GSH/GSSG的比值却明显降低（P < 0.01）。1,25-（OH）₂D₃处理48 h后可显著改善PM_2.5染毒细胞的抗氧化水平（P < 0.05）,主要表现为MDA浓度的降低和GSH/GSSG比值的增加。蛋白分析结果发现,PM_2.5可诱导细胞Nrf-2和HO-1蛋白表达的增加。1,25-（OH）₂D₃干预48 h后可上调HBE细胞内VDR水平,并可增加PM_2.5染毒组细胞内Nrf-2和HO-1蛋白的表达水平。结论： PM_2.5可诱导HBE细胞氧化损伤,主要表现为脂质过氧化水平升高、GSH/GSSG比值下降和抗氧化蛋白Nrf-2与HO-1表达水平的增加。在PM_2.5所致细胞氧化应激效应中,1,25-（OH）₂D₃可起到一定的保护作用,这可能与VDR及Nrf-2/HO-1信号通路有关。而1,25-（OH）₂D₃所致细胞存活率的降低可能与其诱导细胞周期阻滞及促进PM_2.5所诱导损伤细胞的凋亡有关。     

Vitamin D receptor and p21/WAF1 are targets of genistein and 1,25-dihydroxyvitamin D3 in human prostate cancer cells

We investigated mechanisms by which genistein and 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] act synergistically to inhibit the growth of the human prostate cancer cell line LNCaP. We demonstrate that 1,25(OH)(2)D(3) and genistein cooperate to up-regulate the vitamin D receptor protein by increasing the stability of the vitamin D receptor. Genistein and 1,25(OH)(2)D(3) also cooperate to up-regulate the levels of p21/WAF1 (p21). Small interfering RNA-mediated knockdown of p21 expression showed that p21 is essential for significant growth inhibition of LNCaP cells in response to either compound or their combination. We conclude that one mechanism of synergism between genistein and 1,25(OH)(2)D(3) is through genistein modulation of vitamin D signaling.     

Reciprocal changes in gene expression profiles of cocultured breast epithelial cells and primary fibroblasts

The importance of epithelial‐stroma interaction in normal breast development and tumor progression has been recognized. To identify genes that were regulated by these reciprocal interactions, we cocultured a nonmalignant (MCF10A) and a breast cancer derived (MDA‐MB231) basal cell lines, with fibroblasts isolated from breast benign‐disease adjacent tissues (NAF) or with carcinoma‐associated fibroblasts (CAF), in a transwell system. Gene expression profiles of each coculture pair were compared with the correspondent monocultures, using a customized microarray. Contrariwise to large alterations in epithelial cells genomic profiles, fibroblasts were less affected. In MDA‐MB231 highly represented genes downregulated by CAF derived factors coded for proteins important for the specificity of vectorial transport between ER and golgi, possibly affecting cell polarity whereas the response of MCF10A comprised an induction of genes coding for stress responsive proteins, representing a prosurvival effect. While NAF downregulated genes encoding proteins associated to glycolipid and fatty acid biosynthesis in MDA‐MB231, potentially affecting membrane biogenesis, in MCF10A, genes critical for growth control and adhesion were altered. NAFs responded to coculture with MDA‐MB231 by a decrease in the expression of genes induced by TGFβ1 and associated to motility. However, there was little change in NAFs gene expression profile influenced by MCF10A. CAFs responded to the presence of both epithelial cells inducing genes implicated in cell proliferation. Our data indicate that interactions between breast fibroblasts and basal epithelial cells resulted in alterations in the genomic profiles of both cell types which may help to clarify some aspects of this heterotypic signaling. © 2009 UICC