Extracellular matrix and HIF-1 signaling: The role of prolidase

Metabolism and Cancer Susceptibility Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, MD 21702, USA.
International Journal of Cancer (Impact Factor: 5.09). 03/2007; 122(6):1435-40. DOI: 10.1002/ijc.23263
Source: PubMed


Hypoxia-inducible factor-1 (HIF-1) plays an important role in stress-responsive gene expression. Although primarily sensitive to hypoxia, HIF-1 signaling can be regulated by a number of stress factors including metabolic stress, growth factors and molecules present in the extracellular matrix (ECM). Degradation of ECM by metalloproteinases (MMP) is important for tumor progression, invasion and metastasis. ECM is predominantly collagen, and the imino acids (Pro and HyPro) comprise 25% of collagen residues. The final step in collagen degradation is catalyzed by prolidase, the obligate peptidase for imidodipeptides with Pro and HyPro in the carboxyl terminus. Defective wound healing in patients with inherited prolidase deficiency is associated with histologic features of angiopathy suggesting that prolidase may play a role in angiogenesis. Because HIF-1 alpha is central to angiogenesis, we considered that prolidase may modulate this pathway. To test this hypothesis, we made expression constructs of human prolidase and obtained stable transfectants in colorectal cancer cells (RKO). Overexpression of prolidase resulted in increased nuclear hypoxia inducible factor (HIF-1 alpha) levels and elevated expression of HIF-1-dependent gene products, vascular endothelial growth factor (VEGF) and glucose transporter-1 (Glut-1). The activation of HIF-1-dependent transcription was shown by prolidase-dependent activation of hypoxia response element (HRE)-luciferase expression. We used an oxygen-dependent degradation domain (ODD)-luciferase reporter construct as a surrogate for HIF-1 alpha as an in situ prolyl-hydroxylase assay. Since this reporter is degraded by VHL-dependent mechanisms, the increased levels of luciferase observed with prolidase expression reflected the decreased HIF-1 alpha prolyl hydroxylase activity. Additionally, the differential expression of prolidase in 2 breast cancer cell lines showed prolidase-dependent differences in HIF-1 alpha levels. These findings show that metabolism of imidodipeptides by prolidase plays a previously unrecognized role in angiogenic signaling.

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Available from: James M Phang, Jan 15, 2015
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    • "However, rhPEPD, but not rhPEPD G278D , stimulated hypoxia-inducible factor 1α (HIF-1α) and its downstream targets, including vascular endothelial growth factor (VEGF) and glucose transporter 1 (GLUT-1) in the tumor tissues (Fig. 3E). The effects of rhPEPD on HIF-1α, VEGF and GLUT-1 likely stem from the metabolism of imidodipeptides by rhPEPD upon its internalization and the inhibition of HIF-1α degradation by the metabolites (Surazynski et al., 2008). Both rhPEPD and rhPEPD G278D accumulated in the tumor tissues (Fig. 3E) via ERBB2-mediated internalization (Supplementary Fig. 5). "
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    ABSTRACT: ERBB2 is an oncogenic receptor tyrosine kinase overexpressed in a subset of human breast cancer and other cancers. We recently found that human prolidase (PEPD), a dipeptidase, is a high affinity ERBB2 ligand and cross-links two ERBB2 monomers. Here, we show that recombinant human PEPD (rhPEPD) strongly inhibits ERBB2-overexpressing tumors in mice, whereas it does not impact tumors without ERBB2 overexpression. rhPEPD causes ERBB2 depletion, disrupts oncogenic signaling orchestrated by ERBB2 homodimers and heterodimers, and induces apoptosis. The impact of enzymatically-inactive mutant rhPEPDG278D on ERBB2 is indistinguishable from that of rhPEPD, but rhPEPDG278D is superior to rhPEPD for tumor inhibition. The enzymatic function of rhPEPD stimulates HIF-1α and other pro-survival factors in tumors, which likely attenuates its antitumor activity. rhPEPDG278D is also attractive in that it may not interfere with the physiologic function of endogenous PEPD in normal cells. Collectively, we have identified a human protein as an inhibitory ERBB2 ligand that inhibits ERBB2-overexpressing tumors in vivo. Several anti-ERBB2 agents are on the market but are hampered by drug resistance and high drug cost. rhPEPDG278D may synergize with these agents and may also be highly cost-effective, since it targets ERBB2 with a different mechanism and can be produced in bacteria.
    03/2015; 20(5). DOI:10.1016/j.ebiom.2015.03.016
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    • "In fact prolidase activity has been reported to affect both type I collagen synthesis and degradation and to be itself upregulated by stimulation of β1-integrin, the monomer of the integrin α1β1 specifically mediating type I collagen cell–matrix interaction [3] [4] [5]. Furthermore, its catalytic products, proline and hydroxyproline, stimulate hypoxia inducible factor α (HIF-1α), an important transcription factor having, among its target genes, vascular endothelial growth factor (VEGF) and glucose transporter-1 (GLUT1) [6]. Thus prolidase may also be indirectly involved in angiogenesis. "
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    ABSTRACT: The degradation of the main fibrillar collagens, collagens I and II, is a crucial process for skeletal development. The most abundant dipeptides generated from the catabolism of collagens contain proline and hydroxyproline. In humans, prolidase is the only enzyme able to hydrolyze dipeptides containing these amino acids at their C-terminal end, thus being a key player in collagen synthesis and turnover. Mutations in the prolidase gene cause prolidase deficiency (PD), a rare recessive disorder. Here we describe 12 PD patients, 9 of whom were molecularly characterized in this study. Following a retrospective analysis of all of them a skeletal phenotype associated with short stature, hypertelorism, nose abnormalities, microcephaly, osteopenia and genu valgum, independent of both the type of mutation and the presence of the mutant protein was identified. In order to understand the molecular basis of the bone phenotype associated with PD, we analyzed a recently identified mouse model for the disease, the dark-like (dal) mutant. The dal/dal mice showed a short snout, they were smaller than controls, their femurs were significantly shorter and pQCT and μCT analyses of long bones revealed compromised bone properties at the cortical and at the trabecular level in both male and female animals. The differences were more pronounce at 1month being the most parameters normalized by 2months of age. A delay in the formation of the second ossification center was evident at postnatal day 10. Our work reveals that reduced bone growth was due to impaired chondrocyte proliferation and increased apoptosis rate in the proliferative zone associated with reduced hyperthrophic zone height. These data suggest that lack of prolidase, a cytosolic enzyme involved in the final stage of protein catabolism, is required for normal skeletogenesis especially at early age when the requirement for collagen synthesis and degradation is the highest. Copyright © 2014 Elsevier Inc. All rights reserved.
    Bone 11/2014; 72C:53-64. DOI:10.1016/j.bone.2014.11.009 · 3.97 Impact Factor
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    • "Prolidase (E.C. is the enzyme that catalyzes the final step in ECM degradation by releasing proline or hydroxyproline from the carboxyl terminus of imidodipeptides [10]. Our previous study showed that prolidase participates not only in post-transcriptional regulation of collagen biosynthesis but also is involved in regulation at transcriptional level [11]. Several reports suggest that prolidase through regulation of expression of growth factors (e.g., vascular endothelial growth factor, VEGF; transforming growth factor β, TGF-β) and transcription factors (e.g., hypoxia inducible factor 1α, HIF-1α) may play important role in wound healing, inflammation, and angiogenesis [11–14]. "
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    ABSTRACT: The role of estrogen in breast cancer progression and activation of prolidase activity and HIF-1α led us to study the effect of estrogen on nuclear HIF-1α expression in breast cancer estrogen-dependent MCF-7 and estrogen-independent MDA-MB-231 cells. We have found that in MCF-7 cells (expressing α and β estrogen receptor) cultured without estrogen receptor activator (phenol red, estradiol), HIF-1α was down-regulated, compared to the cells cultured with estrogen receptor activator. This effect was not observed in MDA-MB-231 cells (expressing only β estrogen receptor), suggesting that α estrogen receptor is involved in down-regulation of HIF-1α. However, in MDA-MB-231 cells (expressing high prolidase activity) cultured in the presence of prolidase substrates, Gly-Pro or Gly-HyPro, HIF-1α expression was induced in a dose-dependent manner, independently of estrogen receptor activation. In MCF-7 cells (with constitutively low prolidase activity) the effect of studied iminodipeptides on HIF-1α expression was much less pronounced but it was estrogen-dependent, showing importance of prolidase activity in mechanism of this process. The data were supported by confocal microscopy bio-imaging of HIF-1α in nucleus of MCF-7 and MDA-MB-231 cells that were cultured in the presence and absence of estrogen activator and prolidase substrates. It suggests that estrogen receptor may represent important therapeutic target in pharmacotherapy of estrogen receptor positive breast cancer, while ECM degradation enzymes, including prolidase may represent target in pharmacotherapy of estrogen receptor negative breast cancers.
    Molecular and Cellular Biochemistry 04/2013; 379(1-2). DOI:10.1007/s11010-013-1623-9 · 2.39 Impact Factor
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