[show abstract][hide abstract] ABSTRACT: Up-regulation of the dolichol pathway, a "hallmark" of asparagine-linked protein glycosylation, enhances angiogenesis in vitro. The dynamic relationship between these two processes is now evaluated with tunicamycin. Capillary endothelial cells treated with tunicamycin were growth inhibited and could not be reversed with exogenous VEGF(165). Inhibition of angiogenesis is supported by down-regulation of (i) phosphorylated VEGFR1 and VEGFR2 receptors; (ii) VEGF(165)-specific phosphotyrosine kinase activity; and (iii) Matrigel(TM) invasion and chemotaxis. In vivo, tunicamycin prevented the vessel development in Matrigel(TM) implants in athymic Balb/c (nu/nu) mice. Immunohistochemical analysis of CD34 (p < 0.001) and CD144 (p < 0.001) exhibited reduced vascularization. A 3.8-fold increased expression of TSP-1, an endogenous angiogenesis inhibitor in Matrigel(TM) implants correlated with that in tunicamycin (32 h)-treated capillary endothelial cells. Intravenous injection of tunicamycin (0.5 mg/kg to 1.0 mg/kg) per week slowed down a double negative (MDA-MB-435) grade III breast adenocarcinoma growth by ∼50-60% in 3 weeks. Histopathological analysis of the paraffin sections indicated significant reduction in vessel size, the microvascular density and tumor mitotic index. Ki-67 and VEGF expression in tumor tissue were also reduced. A significant reduction of N-glycan expression in tumor microvessel was also observed. High expression of GRP-78 in CD144-positive cells supported unfolded protein response-mediated ER stress in tumor microvasculature. ∼65% reduction of a triple negative (MDA-MB-231) breast tumor xenograft in 1 week with tunicamycin (0.25 mg/kg) given orally and the absence of systemic and/or organ failure strongly supported tunicamycin's potential for a powerful glycotherapeutic treatment of breast cancer in the clinic.
Journal of Biological Chemistry 06/2011; 286(33):29127-38. · 4.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although previous in vitro studies predicted that CCN5/WISP-2 may act as an anti-invasive gene in breast cancer, the distribution pattern of CCN5 in breast cancer samples is conflicting. Thus, we systematically investigated the CCN5 expression profile in noninvasive and invasive breast tumor samples and its functional relevance in breast cancer progression. The studies showed that CCN5 expression is biphasic, such that in normal samples CCN5 expression is undetectable, whereas its expression is markedly increased in noninvasive breast lesions, including atypical ductal hyperplasia and ductal carcinoma in situ. Further, CCN5 mRNA and protein levels are significantly reduced as the cancer progresses from a noninvasive to invasive type. Additionally, we showed that CCN5 mRNA and protein level was almost undetectable in poorly differentiated cancers compared with the moderately or well-differentiated samples and its expression inversely correlated with lymph node positivity. The result was further supported by evaluating the RNA expression profile in microdissected sections using real-time PCR analysis. Therefore, our data suggest a protective function of CCN5 in noninvasive breast tumor cells. This hypothesis was further supported by our in vitro studies illuminating that CCN5 is a negative regulator of migration and invasion of breast cancer cells, and these events could be regulated by CCN5 through the modulation of the expression of genes essential for an invasive front. These include Snail-E-cadherin signaling and matrix metalloproteinase (MMP)-9 and MMP-2. Collectively, these studies suggest that the protective effect of CCN5 in breast cancer progression may have important therapeutic implications.
Cancer Research 10/2008; 68(18):7606-12. · 8.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Vascular smooth muscle cells (SMCs), one of the major cell types of the vascular wall, play a critical role in the process of angiogenesis under both physiological and pathophysiological conditions, including the cancer microenvironment. Previous studies have shown that VEGF-A 165 augments vascular SMC migration via VEGFR2 (KDR/Flk1) pathways. In this study, we found that VEGF-A 165 (recombinant protein or breast tumor cell-secreted) is also capable of inducing migration of VEGFR2-negative human aortic smooth muscle cells (hAOSMCs), and this induction is mediated through a molecular cross-talk of neuropilin-1 (NRP-1), VEGFR1 (Flt-1), and phosphoinositide 3-kinase (PI3K)/Akt signaling kinase. We found that VEGF-A 165 induces hAOSMC migration parallel with the induction of NRP-1 and VEGFR1 expressions and their associations along with the activation of PI3K/Akt. Neutralization of VEGF action by its antibody or inhibition of VEGF-induced PI3K/Akt kinase activation by wortmannin, a PI3K/Akt specific inhibitor, results in inhibition of VEGF-induced hAOSMC migration. Moreover, RNAi-mediated elimination of the NRP-1 expression or blocking of the activity of VEGFR1 by its antibody in hAOSMCs impairs the VEGF-A 165-induced migration of these cells as well as activation of PI3K/Akt kinase. Collectively, these results establish, for the first time, a mechanistic link among VEGF-A 165, NRP-1, VEGFR1, and PI3K/Akt in the regulation of migration of human vascular smooth muscle cells that eventually could be involved in the angiogenic switch.
[show abstract][hide abstract] ABSTRACT: Previously, we have shown that the expression of Wnt-1-induced signaling protein-2 (WISP-2), also known as CCN5, can be regulated by multiple stimulants in estrogen receptor (ER)-positive breast tumor cells to exert their mitogenic action in these cells. Here, we show that insulin-like growth factor-1 (IGF-1), a strong mitogen, enhanced the expression of the WISP-2/CCN5 gene parallel with the induction of proliferation of ER-positive breast tumor cells. An additive effect was also seen in combination with estrogen. Perturbation of IGF-1-induced WISP-2/CCN5 expression by WISP-2-specific RNA interference impaired the mitogenic action of IGF-1 on ER-positive breast tumor cells. Furthermore, the studies have shown that the multiple molecular cross-talks and side-talks among IGF-1R, ER-alpha, and phosphatidylinositol 3-kinase (PI3K)/Akt signaling molecules are required to induce WISP-2/CCN5 mRNA by IGF-1 in ER-positive, noninvasive breast tumor cells. Because a pure anti-ER ICI 182,780 is not only able to suppress the up-regulation of WISP-2/CCN5 mRNA expression by IGF-1, it also suppresses the PI3K/Akt activity induced by IGF-1 in MCF-7 cells; we anticipate that the membrane ER receptor may participate in this event. Collectively, these studies propose for the first time that WISP-2/CCN5 is an integral signaling molecule in mitogenic action of IGF-1 axis in ER-positive human breast tumor cells.
Cancer Research 03/2007; 67(4):1520-6. · 8.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Motility of vascular smooth muscle cells (SMCs) is an essential step for both normal and pathologic angiogenesis. We report here that breast tumor cells, such as MCF-7 and MDA-MB-231, can modulate this SMC migration. We present evidence that the tumor cell-derived platelet-derived growth factor (PDGF) is the key regulator of vascular SMCs motility induced by breast cancer cells. PDGF significantly upregulates neuropilin-1 (NRP-1) mRNA expression and protein production in aortic smooth muscle cells (AOSMCs) and depletion of NRP-1 production by AOSMCs with specific short hairpin RNA (shRNA) prevents the PDGF-dependent migration of vascular SMCs. Moreover, we demonstrate that PDGF physically interacts with NRP-1. We propose that tumor-derived PDGF and NRP-1 of AOSMCs function as a relay system that promotes motility of vascular SMCs.
[show abstract][hide abstract] ABSTRACT: PMA and active phorbol esters stimulate the proliferation of various tumor cells, including ER-positive human breast tumor cell lines. However, the specific signaling pathways involved in the PMA-induced mitogenic effect on breast tumor cells have not been fully elucidated. In the present study, we explored the mechanisms associated with the mitogenic influence of PMA on breast tumor cells. Following an acute exposure (i.e., within 2 to 6 h) to PMA (50 nM), a mitogenic effect was observed on WISP-2/CCN5-positive breast tumor cell lines, including MCF-7, ZR-75-1 and SKBR-3 cells, and induction of WISP-2/CCN5 mRNA expression paralleled the observed mitogenic proliferation. This effect was undetected in WISP-2/CCN5 negative MDA-MB-231 breast tumor cells or human mammary epithelial cells with or without ER-alpha transfection. The mitogenic effect of PMA was perturbed by short hairpin RNA (shRNA)-mediated inhibition of WISP-2/CCN5 signaling in MCF-7 cells. Moreover, the upregulation of WISP-2/CCN5 by PMA is not ER dependent but is instead mediated through a complex PKCalpha-MAPK/ERK and SAPK/JNK signaling pathway, which leads to growth stimulation of MCF-7 breast tumor cells. These series of experiments provide the first evidence that WISP-2/CCN5 is a novel signaling molecule that critically participates in the mitogenic action of PMA on noninvasive, WISP-2/CCN5-positive breast tumor cells through PKCalpha-dependent, multiple molecular signal transduction pathways.
[show abstract][hide abstract] ABSTRACT: 2-Methoxyestradiol (2-ME(2)), a promising anticancer drug, induces growth arrest and apoptosis in various androgen-dependent (LNCaP) and -independent (DU145 and PC-3) prostate cancer cell lines. Moreover, flow cytometric analysis indicated a novel dual impact of 2-ME(2) on the cell division cycle of prostate cancer cells. Chronic exposure of high doses of 2-ME(2) enhance the accumulation of cells in S and G2/M phases, while cell numbers in the G1 phase were reduced significantly by this treatment. Because cyclin B1 overexpression, induction of cdc2 phosphorylation, and its regulatory proteins wee1 and phospho-cdc25C (interphase and mitotic forms) by 2-ME(2) treatment correlated with the induction of apoptosis, growth arrest at the G2/M phase, and accumulation of the S phase, we reasoned that cyclin B1 and cdc2 phosphorylation and its upstream regulatory molecular networks may be associated with the ultimate impacts of 2-ME(2). Because phosphorylation of cdc2 and upregulation of wee1 by 2-ME(2) can be abolished by both extracellular receptor kinase (ERK) inhibitor (U0126) and c-Jun N-terminal kinase (JNK) inhibitor (SP600125), our studies indicate that the 2-ME(2)-induced upregulation of wee1 and subsequent cdc2 phosphorylation are mediated through mitogen-activated protein kinase (MAPK)-ERK-JNK signaling pathways.
[show abstract][hide abstract] ABSTRACT: Epidermal growth factor (EGF) is a mitogen for estrogen receptor (ER)-positive breast tumor cells, and it has been proven that EGF occasionally mimicked estrogen action and cross-talks with ER-alpha to exert its activity. Therefore, the present study was undertaken to explore whether EGF is able to modulate the expression of Wnt-1-induced signaling protein-2/connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed 5 (WISP-2/CCN5), an estrogen-responsive gene, in normal and transformed cell lines of the human breast and, if so, whether this induction is critical for EGF mitogenesis and what downstream signaling pathways are associated with this event. Here, we show that EGF-induced WISP-2 expression in ER- and EGF receptor-positive noninvasive MCF-7 breast tumor cells was dose and time dependent and that expression was modulated at transcription level. A synergism was seen in combination with estrogen. Moreover, small interfering RNA-mediated inhibition of WISP-2/CCN5 activity in MCF-7 cells resulted in abrogation of proliferation by EGF. The multiple molecular cross-talks, including the interactions between phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase signaling pathways and two diverse receptors (i.e., ER-alpha and EGFR), were essential in the event of EGF-induced WISP-2/CCN5 up-regulation in MCF-7 cells. Moreover, EGF action on WISP-2/CCN5 is restricted to ER- and EGFR-positive noninvasive breast tumor cells, and this effect of EGF cannot be instigated in ER-alpha-negative and EGFR-positive normal or invasive breast tumor cells by introducing ER-alpha. Finally, regulation of phosphorylation of ER-alpha and EGFR may play critical roles in EGF-induced transcriptional activation of WISP-2 gene in breast tumor cells.
Molecular Cancer Research 04/2005; 3(3):151-62. · 4.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Prostate cancer is the most common non-skin cancer affecting men in United States and the second leading cause of death after lung cancer. The clinical course of patients after given diagnosis of prostate cancer is highly variable and the underlying reasons for such variability remain elusive. To better understand the pathophysiology of prostate cancer, there has been a push to elucidate the molecular mechanisms that mediate the development and progression of prostate cancer. Recent literature has pointed that a complex interplay between various cytokines, growth factors, and androgen receptors regulate the growth and functions of the prostate gland. Amongst the currently implicated anomalous pathways involved in prostate oncogenesis, the IGF-IGFBP axis has been demonstrated to play a very important role, although the precise molecular events regulated by IGF remain to be elucidated. The tumor promoting functions of VEGF has been defined in tumor angiogenesis and currently remains the central focus of anti-angiogenesis therapy in prostate cancer. Another key cytokine, TGF-beta has tumor-suppressor functions in normal prostate gland, but its pleiotropic functions in prostate cancer are influenced by the hormonal state of the disease. In partnership with other deregulated growth factor signaling, the TGF-beta cascade has also been implicated in the spread of prostate cancer. Lastly, members of the EGFR family, particularly the HER2 receptor, have also been recognized as crucial elements of aberrant signal transduction pathways, which induce activation of downstream signaling, involved in cellular proliferation, cell survival, and angiogenesis. The abnormal function of a number of growth factors in prostate cancer biology explains the heterogeneity of its histologic grade, mode of presentation and disease prognosis. At the same time, continued research in this field allows for the potential development of drug therapies against a diverse pool of cancer causing targets.
Frontiers in Bioscience 02/2005; 10:1355-67. · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Expression of epidermal growth factor receptors (EGFR) is exaggerated in pancreatic adenocarcinoma and activation of EGFR appears to have an important role in the growth and differentiation of this and in other tumors. Therefore, blockade or inactivation of EGFR by monoclonal antibodies or by tyrosine kinase inhibitors has significant potential as an effective anti-cancer therapy. One of the very recent significant developments in the field of molecular biology involves the use of antisense of EGFR or EGFR gene silencing in pancreatic cancer cells as a potential targeted therapy for patients with pancreatic adenocarcinoma.
Frontiers in Bioscience 02/2005; 10:1763-7. · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Beta-estradiol (17beta-E2) augments VEGF-A expression in various estrogen targeted organs and cells including breast tumor derived cell lines, via an ER-alpha mediated pathway. Ironically, 17beta-E2 is able to regulate some genes via ER-alpha independent pathways. In the present study, we sought to determine whether 17beta-E2 can modulate VEGF-A expression in absence of ER-alpha, and therefore, three different cell lines including ER-alpha+ MCF-7, and ER-alpha SKBR-3 and HMEC were used for this study. The present study demonstrates that 17beta-E2 also induces VEGF-A mRNA expression in ER-negative SKBR-3 breast tumor cells in a manner similar to that observed in ER-positive MCF-7 cells. Blocking the induced-expression by antiestrogen ICI 182,780 indicates the induction pathway is ER dependent. While ER-alpha mRNA is absent in both HMEC and SKBR-3 cells, the impact of estrogen was found only in SKBR-3 cells, suggesting the existence of an analogue to ER-alpha or overlapping signal in these cells. Consistent with this suggestion, the present studies demonstrate the existence of an ER-alpha(var2) protein in MCF-7 and in SKBR-3 cells. This variant is predominantly localized in the nuclei of SKBR-3 cells. Importantly, specific binding of 17beta-E2 by these cells suggest the ER-alpha(var2) may act as active receptor in SKBR-3 cells.
Molecular and Cellular Biochemistry 08/2004; 262(1-2):215-24. · 2.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: 17-Estradiol (17-E2) augments VEGF-A expression in various estrogen targeted organs and cells including breast tumor derived cell lines, via an ER- mediated pathway. Ironically, 17-E2 is able to regulate some genes via ER- independent pathways. In the present study, we sought to determine whether 17-E2 can modulate VEGF-A expression in absence of ER-, and therefore, three different cell lines including ER-+ MCF-7, and ER- SKBR-3 and HMEC were used for this study. The present study demonstrates that 17-E2 also induces VEGF-A mRNA expression in ER-negative SKBR-3 breast tumor cells in a manner similar to that observed in ER-positive MCF-7 cells. Blocking the induced-expression by antiestrogen ICI 182,780 indicates the induction pathway is ER dependent. While ER- mRNA is absent in both HMEC and SKBR-3 cells, the impact of estrogen was found only in SKBR-3 cells, suggesting the existence of an analogue to ER- or overlapping signal in these cells. Consistent with this suggestion, the present studies demonstrate the existence of an ER-var2 protein in MCF-7 and in SKBR-3 cells. This variant is predominantly localized in the nuclei of SKBR-3 cells. Importantly, specific binding of 17-E2 by these cells suggest the ER-var2 may act as active receptor in SKBR-3 cells. (Mol Cell Biochem 262: 215–224, 2004)
Molecular and Cellular Biochemistry 06/2004; 262(1):215-224. · 2.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: The natural hormone 17beta-estradiol (17beta-E2) is known to induce tumor angiogenesis in various target organs by activating positive regulators of angiogenesis. In this study, we show for the first time that in human umbilical vein endothelial cells (HUVECs), 17beta-E2 transiently down-regulates the expression and secretion of a potent negative regulator of angiogenesis, thrombospondin-1 (TSP-1). This inhibitory effect of 17beta-E2 is mediated through nongenomic estrogen receptor (ER)/mitogen-activated protein kinase (MAPK)/extracellular-regulated kinase (ERK) 1/2 and c-Jun NH(2)-terminal kinase (JNK)/stress-activated protein kinase (SAPK) signaling pathways, because this effect can be abolished by a pure ER antagonist (ICI 182,780) and inhibitors of downstream signaling proteins of MAPK signaling cascades, including MAPK kinase 1/2 and ERK1/2 inhibitor and JNK/SAPK inhibitor. To understand the functional role(s) of TSP-1 during estradiol-induced angiogenesis, we examined the growth and migration of endothelial cells in different experimental environments. Using a recombinant protein, we show that increments of TSP-1 protein concentration in culture medium significantly reduce the migration and proliferation of HUVECs stimulated by 17beta-E2. Together, these studies suggest that TSP-1 can be considered an important negative factor in understanding the increased angiogenesis in response to estrogens.
Molecular Cancer Research 04/2004; 2(3):150-8. · 4.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Estrogens have been shown to regulate vascular endothelial growth factor-A (VEGF-A) for physiological and patho-physiological functions. However, estrogen action on VEGF-A mRNA expression has not been completely elucidated. We have identified two phases of activation of VEGF-A mRNA transcription, one early and one late response, induced by 17beta-estradiol (17beta-E2) in ER+ MCF-7 breast tumor cells, depending upon the length of exposure. VEGF-A mRNA level was significantly higher than control in tumor cells after 2 h of 17beta-E2 exposure. Furthermore this induction was not inhibited by cycloheximide, indicating that it was a direct effect of estrogen. In contrast VEGF-A mRNA expression was back at basal level in MCF-7 cells exposed to 17beta-E2 for 6 h. However, expression levels were again significantly augmented after 24 h of exposure, and this induction was unaltered by cycloheximide indicating that de novo protein synthesis was not required and like early response, it was a direct effect of estrogen. The antiestrogen ICI 182,780 was a pure antagonist for the early response phase of VEGF-A mRNA induction, but it had partial but significant effect on the late response phase, further suggesting that both early and late phases were ER dependent. In human mammary epithelial cells (HMEC) lacking estrogen receptor (ER-alpha) the early and late response phase of VEGF-A mRNA induction in response to 17beta-E2 was not found, but significant inductions were seen in the early and late phases when ER-alpha transfected HMEC were exposed to 17beta-E2 for 2 or 24 h. Taken together, these studies suggest that VEGF-A is an estrogen responsive gene and modulation of this gene expression by estrogen is biphasic and can be mediated through ER-alpha dependent pathway.
International Journal of Oncology 04/2003; 22(3):609-14. · 2.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: 17alpha-E(2), a weak estrogen exhibited both agonistic and antagonistic effects, and caused a time- and dose-dependent induction of VEGF-A mRNA expression in GH3 rat pituitary tumor cells. This effect was unaffected by the presence of the pure estrogen receptor antagonist ICI 182,780 but was specifically blocked by a protein synthesis inhibitor puromycin. Inhibition of phosphatidylinositol-3 kinase (PI3K) activity by wortmannin decreased the effect of 17alpha-E(2) on VEGF-A mRNA expression. This inhibitor also blocked the increase in phosphorylation of Akt induced by exposure to 17alpha-E(2). In contrast, exposure to the MAP kinase inhibitor, U0126, had no impact on 17alpha-E(2)-induced VEGF-A mRNA expression. Taken together, these studies indicate that like potent estrogens 17alpha-E(2) up-regulates VEGF-A mRNA expression in estrogen responsive GH3 rat pituitary tumor cells, but this induction is not mediated through a classical estrogen receptor pathway. PI3K-Akt signaling pathway is required for the induction of VEGF-A mRNA in GH3 cells by 17alpha-E(2).
Biochemical and Biophysical Research Communications 02/2003; 300(1):209-15. · 2.41 Impact Factor
[show abstract][hide abstract] ABSTRACT: WISP-2 mRNA and protein was overexpressed in preneoplastic and cancerous cells of human breast. Statistical analyses show a significant association between WISP-2 expression and estrogen receptor (ER) positivity. In normal breast, the expression was virtually undetected. The studies showed that WISP-2 is an estrogen-induced early response gene in MCF-7 cells and the expression was continuously increased to reach a maximum level at 24 h. The estrogen effect was inhibited by a pure antiestrogen (ICI 182,780). Human mammary epithelial cells, in which WISP-2 expression was undetected or minimally detected, responded to 17beta-estradiol by upregulating the WISP-2 gene after transfection with ER-alpha, providing further evidences that WISP-2 expression is mediated through ER-alpha. Overexpression of WISP-2 mRNA by estrogen may be accomplished by both transcriptional activation and stabilization. MCF-7 cells exposed to progesterone had a rapid but transient increase in WISP-2 expression, and PR antagonist RU38486 blocked this mRNA induction. In combination with estradiol, progesterone acted as an antagonist inhibiting the expression of WISP-2 mRNA. Moreover, disruption of WISP-2 signaling in MCF-7 cells by use of antisense oligomers caused a significant reduction in tumor cell proliferation. The results are consistent with the conclusion that WISP-2 expression is a requirement for breast tumor cells proliferation.
[show abstract][hide abstract] ABSTRACT: The transcriptional alterations of specific gene(s) are actively associated with the development of different cancers including breast. The preceding studies of different laboratories documented at least 40 genes that may contribute directly to the genesis of cancer. Using differential display, RT-PCR and DNA sequencing analyses in normal human mammary epithelial cells (HMEC) and various breast tumor cell lines including MCF-7, ZR-75, T-47D and SKBR2, we demonstrated that WISP-1 and WISP-2 genes are differentially transcribed in these cells. WISP-2 mRNA transcription was identified in all 4 tumor derived cell lines, but the mRNA expression was undetected or minimally detected in normal breast epithelial cells. WISP-1 mRNA expression was identified in normal and transformed cell lines. However, the level of expression was higher in different breast tumor cell lines as compared to HMEC. The mRNA expression profiles of WISP genes in normal breast epithelial cells and breast tumor derived cell lines indicated a strong possibility of the involvement of WISP-signaling in the development of human breast tumors, and can be utilized as genetic markers of this disease.
Molecular and Cellular Biochemistry 11/2001; 228(1):99-104. · 2.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: 2-Methoxyestradiol (2-ME2) was reported to elicit both stimulation and inhibition of tumor angiogenesis and growth depending on the dosage used. However, the mechanism(s) of the biphasic action of 2-ME2 has been elusive. Here we describe a regulatory role of vascular endothelial growth factor-A (VEGF-A) in the biphasic effects on estrogen receptor (ER)+ GH3 rat pituitary tumor cells and MCF-7 human breast tumor cells depending on the dosage of 2-ME2 used. We observed that acute exposure to 2-ME2, irrespective of dosage, did not alter cellular proliferation, but enhanced the VEGF-A mRNA level. As the treatment duration increased, biphasic effect was elicited. A concentration of 1 microM 2-ME2 increased both cell proliferation and VEGF-A levels in these cells, whereas higher doses exhibited reversed impact. A low dose of 2-ME2 also increased the VEGF-A mRNA expression in ER-alpha-transfected human mammary epithelial cells (HMECs). The effect was reversed in ER- cells. The enhanced expression of VEGF-A mRNA could be blocked by the pure estrogen antagonist, ICI 182,780, and reveal that the upregulation of VEGF-A expression by 2-ME2 is mediated through ER-alpha. Furthermore, the biphasic effect of 2-ME2 on cell proliferation can be modulated by administrating VEGF-A antibodies or VEGF-A proteins. Studies also demonstrate that the VEGF-A protein, induced by 2-ME2, is functionally active and upregulates the proliferation of adjacent endothelial cells.