Identification of HDM2 as a regulator of VEGF expression in cancer cells

Narasimhan, Madhusudhanan; Rose, R. Wesley; Ramakrishnan, R.; Zell, Jason A.; Rathinavelu, Appu

doi:10.1016/j.lfs.2008.04.004

Cited by 10 publications

(10 citation statements)

References 41 publications

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“…Although the changes of VEGFR2 mRNA and protein expressions were temporally associated, the mRNA and protein expressions of VEGF and VEGFR1 were not coincident. These results may be due to the fact that VEGF and VEGFR1 translation takes more time than the transcription process as reported in cells derived from adenocarcinoma [39].…”

Section: Discussionmentioning

confidence: 78%

Expression of VEGF and Its Receptors in the Bovine Endometrium Throughout the Estrous Cycle: Effects of VEGF on Prostaglandin Production in Endometrial Cells

Tasaki

Nishimura

Shibaya

et al. 2010

Journal of Reproduction and Development

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Abstract. Vascular endothelial growth factor (VEGF) is a well known angiogenic factor that has been suggested to play some physiological roles in reproductive organs. To clarify whether VEGF is involved in regulating bovine endometrial function locally, in experiment 1, we determined the expression of VEGF, VEGF receptor (VEGFR) 1 and VEGFR2 throughout the estrous cycle in endometrial tissues. Endometrial tissue was collected at estrus (Day 0), the early I (Days 2-3), early II (Days 5-6), mid and late luteal stages and the follicular stage . RT-PCR and Western blotting analysis revealed that VEGF mRNA expression at estrus was higher than at the early I, early II and late luteal stages (P<0.05), whereas VEGF protein content was greatest at the early I luteal stage and decreased thereafter. VEGFR1 mRNA expression was lower at estrus and at the early I and early II luteal stages than at the other stages, whereas VEGFR1 protein expression did not change significantly throughout the estrous cycle (P<0.05). VEGFR2 mRNA expression was higher at the mid and late luteal stages than at the early I and early II luteal stages, and VEGFR2 protein was higher at the mid and late luteal stages than at estrus (P<0.05). In experiment 2, to determine the effect of VEGF on prostaglandin (PG) F2α and PGE2 production by endometrial cells, cultured endometrial epithelial and stromal cells were exposed to VEGF (0, 5, 50, 100 and 200 ng/ml) for 24 h. VEGF (200 ng/ml) stimulated PGF2α production by stromal cells (P<0.05), but not PGE2 production. VEGF did not affect PG production by endometrial epithelial cells. The overall results suggest that VEGF and its receptors are regulated throughout the estrous cycle and that VEGF participates in the local regulation of bovine endometrial function by a selective modulation of PGF2α production in stromal cells in an auto-and/or paracrine manner. Key words: Bovine, Endometrium, Estrous cycle, VEGF, VEGF receptors (J. Reprod. Dev. 56: [223][224][225][226][227][228][229] 2010) ascular endothelial growth factor (VEGF) is a well known angiogenic factor that plays important physiological roles in a wide range of cells and tissues [1]. In reproductive organs, VEGF is required for normal ovarian angiogenesis and growth of the endometrium throughout the ovulatory cycle in humans [2,3] and rodents [4,5]. In addition, the vascular hyperpermeability induced by VEGF seems to be essential for normal implantation in rodents [6]. The above findings suggest that VEGF has pivotal roles in regulating the functions of the cyclic and pregnant endometrium. In cows, VEGF expression has been observed in the ovary [7,8] The biological actions of VEGF are mediated by two types of tyrosine kinase receptors, VEGFR1 (Flt-1) and VEGFR2 (Flk-1/ KDR) [1,11]. VEGFR1 has a high affinity for VEGF, and its signal for angiogenesis is weak [12]. Although VEGFR1 mediates an essential signal for normal vascularization, it seems that VEGFR1 does not mediate stimulation of endothelial cell proliferation [13]. The exact function of ...

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Section: Discussionmentioning

confidence: 78%

Expression of VEGF and Its Receptors in the Bovine Endometrium Throughout the Estrous Cycle: Effects of VEGF on Prostaglandin Production in Endometrial Cells

Tasaki

Nishimura

Shibaya

et al. 2010

Journal of Reproduction and Development

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“…Hypoxia is a defining characteristic of solid tumors, and HIF-1a plays a central role in tumor adaptation to hypoxia through transcription of a variety of genes such as vascular endothelial growth factor (VEGF) and glycolytic enzymes [28]. Overexpression of MDM2 leads to increased transcriptional activity of HIF-1a [26,29], while in vitro inhibition of MDM2 by siRNA, antisense oligonucleotides, and Nutlin-3a has demonstrated decreased transcription of downstream targets [27, [30][31][32]. Most important of these is VEGF, a specific endothelial cell mitogen, permeability and survival factor, which has been found to be overexpressed in almost all human tumors [33].…”

Section: Introductionmentioning

confidence: 99%

Effect of MDM2 and vascular endothelial growth factor inhibition on tumor angiogenesis and metastasis in neuroblastoma

et al. 2011

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Neuroblastoma is the most common pediatric abdominal tumor and principally a p53 wild-type, highly vascular, aggressive tumor, with limited response to anti-VEGF therapies alone. MDM2 is a key inhibitor of p53 and a positive activator of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) activity with an important role in neuroblastoma pathogenesis. We hypothesized that concurrent inhibition of both MDM2 and VEGF signaling would have cooperative anti-tumor effects, potentiating anti-angiogenic strategies for neuroblastoma and other p53 wild-type tumors. We orthotopically implanted SH-SY5Y neuroblastoma cells into nude mice (n = 40) and treated as follows: control, bevacizumab, Nutlin-3a, combination of bevacizumab plus Nutlin-3a. Expression of HIF-1α and VEGF were measured by qPCR, Western blot, and ELISA. Tumor apoptosis was measured by immunohistochemistry and caspase assay. Angiogenesis was evaluated by immunohistochemistry for vascular markers (CD-31, type-IV collagen, αSMA). Both angiogenesis and metastatic burden were digitally quantified. In vitro, Nutlin-3a suppresses HIF-1α expression with subsequent downregulation of VEGF. Bevacizumab plus Nutlin-3a leads to significant suppression of tumor growth compared to control (P < 0.01) or either agent alone. Combination treated xenograft tumors display a marked decrease in endothelial cells (P < 0.0001), perivascular basement membrane (P < 0.04), and vascular mural cells (P < 0.004). Nutlin-3a alone and in combination with bevacizumab leads to significant tumor apoptosis (P < 0.0001 for both) and significant decrease in incidence of metastasis (P < 0.05) and metastatic burden (P < 0.03). Bevacizumab plus Nutlin-3a cooperatively inhibits tumor growth and angiogenesis in neuroblastoma in vivo with dramatic effects on tumor vascularity. Concomitantly targeting VEGF and p53 pathways potently suppresses tumor growth, and these results support further clinical development of this approach.

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“…A recent series of studies indicate that MDM2 overexpression is associated with cancer metastases and predicts a poor prognosis for developing metastatic, but not localized, cancer (14,19,32,41). It has been reported that MDM2 expression is correlated with increased levels of the angiogenic factor vascular endothelial growth factor (VEGF) (31,42), which may facilitate vascularization, as well as intravasation and seeding of tumor cells in distant places, thus actively contributing to tumor metastasis.…”

mentioning

confidence: 99%

MDM2 Regulates Vascular Endothelial Growth Factor mRNA Stabilization in Hypoxia

Zhou

et al. 2011

Molecular and Cellular Biology

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Expression of vascular endothelial growth factor (VEGF) increases in cancer cells during hypoxia. Herein, we report that the MDM2 oncoprotein plays a role in hypoxia-mediated VEGF upregulation. In studying the characteristics of MDM2 and VEGF expression in neuroblastoma cells, we found that hypoxia induced significantly higher upregulation of both VEGF mRNA and protein in MDM2-positive cells than in the MDM2-negative cells, even in cells without wild-type (wt) p53. We found that hypoxia induced translocation of MDM2 from the nucleus to the cytoplasm, which was associated with increased VEGF expression. Enforcing overexpression of cytoplasmic MDM2 by transfection of the mutant MDM2/166A enhanced expression of VEGF mRNA and protein production, even without hypoxia. The results of mechanistic studies demonstrated that the C-terminal RING domain of the MDM2 protein bound to the AU-rich sequence within the 3 untranslated region (3UTR) of VEGF mRNA; this binding increased VEGF mRNA stability and translation. In addition, knockdown of MDM2 by small interfering RNA (siRNA) in MDM2-overexpressing cancer cells resulted in inhibition of VEGF protein production, cancer cell survival, and angiogenesis. Our results suggest that MDM2 plays a p53-independent role in the regulation of VEGF, which may promote tumor growth and metastasis.The MDM2 protein is a multifunctional oncoprotein that has been shown to play both p53-dependent and -independent roles in oncogenesis. Normally, MDM2 is a nuclear phosphoprotein that contains several conserved functional regions. The MDM2 NH 2 terminus is well characterized; it binds to p53 and represses p53-mediated transcription (30). Thus, it suppresses tumor suppressor activity. The COOH terminus contains a RING finger domain that is an E3 ligase that can regulate ubiquitination of p53 and MDM2 itself (16). Early studies show that in addition to its activity as an E3 ligase, the COOHterminal RING finger domain of MDM2 is able to directly bind specific RNA sequences or structures, at least in vitro (11,22). Recently published studies, including ours, show that the MDM2 RING finger domain binds to many cellular mRNAs, such as p53 and X-linked inhibitor of apoptosis (XIAP) mRNAs, in vivo, regulating mRNA translation and protein synthesis (5, 15).MDM2 gene amplification occurs in diverse human malignancies that include soft tissue sarcomas, neuroblastoma, and cancers of the brain, breast, ovary, cervix, lung, colon, prostate, and bone (9,23,29). In addition, high-level MDM2 expression can occur even in cancers without MDM2 gene amplification, sometimes associated with a single nucleotide polymorphism in the MDM2 gene promoter (3). Thus, overexpression of MDM2 appears to be a favorable state for cancer cells. In fact, in the clinic, overexpression of MDM2 in tumors does correlate with a poor prognosis for cancer patients (34). In addition, previous studies show that MDM2 overexpression occurs more frequently in metastatic and recurrent cancers than in primary tumors (10, 21). One study of 100 tumo...

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Identification of HDM2 as a regulator of VEGF expression in cancer cells

Cited by 10 publications

References 41 publications

Expression of VEGF and Its Receptors in the Bovine Endometrium Throughout the Estrous Cycle: Effects of VEGF on Prostaglandin Production in Endometrial Cells

Expression of VEGF and Its Receptors in the Bovine Endometrium Throughout the Estrous Cycle: Effects of VEGF on Prostaglandin Production in Endometrial Cells

Effect of MDM2 and vascular endothelial growth factor inhibition on tumor angiogenesis and metastasis in neuroblastoma

MDM2 Regulates Vascular Endothelial Growth Factor mRNA Stabilization in Hypoxia

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