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Author: Daniel Bassi
Publisher: Biota Publishing
ISBN: 1615045090
Category : Medical
Languages : en
Pages : 60
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Book Description
Many proprotein convertases (PC), especially furin and PACE4, are involved in pathological processes such as viral infection, inflammation, hypercholesterolemia, and cancer, and have been postulated as therapeutic targets for some of these diseases. In this chapter, we review mostly our work using animal models of squamous cancers that have been induced by chemical or UV carcinogenesis protocols to highlight the role of PCs in the development and progression of experimental tumors. After demonstrating in wild type mice the role of PACE4 in tumor progression as well as detecting the expression of PACE4 and furin in human non-melanoma skin cancers, we developed transgenic mice that over-express either PACE4 or furin in squamous epithelia, including the epidermis. This was accomplished by targeting the expression of the corresponding PC by using the promoter of the bovine keratin 5. Both K5-PACE4 and K5-Furin transgenic mice showed increased susceptibility to a two-stage carcinogenesis protocol of chemical carcinogenesis. Similar studies conducted in K5-PACE4 mice also showed an increased sensitivity to ultraviolet B radiation carcinogenesis. In most of these experiments, we were able to demonstrate that compared to the control wild type mice, the over-expression of the transgene in the epidermis increased the number of benign and malignant skin tumors and also had an effect on tumor progression as evidenced by the presence of less differentiated tumors and more frequent local and distant metastases in many of the transgenic lines. Interestingly, double transgenic mice in which PACE4 and furin are targeted to the epidermis did not show any additive effect, pointing to a probable in vivo overlap of functions at least in cutaneous tissues. The tumor-enhancing effects of PACE4 and furin further support their possible role as therapeutic targets. Furthermore, a proof of principle for PC inhibition as a therapeutic tool has been substantiated by an in vivo experiment in which the PC-inhibitor, decanoyl-RVKRchloromethylketone, was topically administrated to the skin of wild type and transgenic mice treated with chemical carcinogenesis protocols, resulting in a significant decrease of tumor development and progression.
Author: Daniel Bassi
Publisher: Biota Publishing
ISBN: 1615045090
Category : Medical
Languages : en
Pages : 60
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Book Description
Many proprotein convertases (PC), especially furin and PACE4, are involved in pathological processes such as viral infection, inflammation, hypercholesterolemia, and cancer, and have been postulated as therapeutic targets for some of these diseases. In this chapter, we review mostly our work using animal models of squamous cancers that have been induced by chemical or UV carcinogenesis protocols to highlight the role of PCs in the development and progression of experimental tumors. After demonstrating in wild type mice the role of PACE4 in tumor progression as well as detecting the expression of PACE4 and furin in human non-melanoma skin cancers, we developed transgenic mice that over-express either PACE4 or furin in squamous epithelia, including the epidermis. This was accomplished by targeting the expression of the corresponding PC by using the promoter of the bovine keratin 5. Both K5-PACE4 and K5-Furin transgenic mice showed increased susceptibility to a two-stage carcinogenesis protocol of chemical carcinogenesis. Similar studies conducted in K5-PACE4 mice also showed an increased sensitivity to ultraviolet B radiation carcinogenesis. In most of these experiments, we were able to demonstrate that compared to the control wild type mice, the over-expression of the transgene in the epidermis increased the number of benign and malignant skin tumors and also had an effect on tumor progression as evidenced by the presence of less differentiated tumors and more frequent local and distant metastases in many of the transgenic lines. Interestingly, double transgenic mice in which PACE4 and furin are targeted to the epidermis did not show any additive effect, pointing to a probable in vivo overlap of functions at least in cutaneous tissues. The tumor-enhancing effects of PACE4 and furin further support their possible role as therapeutic targets. Furthermore, a proof of principle for PC inhibition as a therapeutic tool has been substantiated by an in vivo experiment in which the PC-inhibitor, decanoyl-RVKRchloromethylketone, was topically administrated to the skin of wild type and transgenic mice treated with chemical carcinogenesis protocols, resulting in a significant decrease of tumor development and progression.
Author: Abdel-Majid Khatib
Publisher: Biota Publishing
ISBN: 1615045376
Category : Science
Languages : en
Pages : 88
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Book Description
Proprotein convertases (PCs) are a family of proteases including PC1, PC2, Furin, PC4, PACE4, PC5, and PC7. These enzymes are involved in the maturation of many precursor proteins involved in the process of tumorigenesis and metastasis. Since their discovery, PCs were suggested as potential targets for anti-cancer therapy, and their activity was found to directly affect tumor cell proliferation, migration invasion, and the malignant phenotypes of tumor cells. Here, we discuss a number of previous and recent findings on the PCs features, their implication in the regulation of multiple cellular functions that impact on the invasive/metastatic potential of cancer cells, and their clinical relevance in cancer patients. Among the substrates of the proprotein convertases, various growth factors, their receptors, adhesion molecules, and proteases were identified. The PCs are inhibited by endogenous and exogenous inhibitors. To date, only pro7B2, a specific chaperone of PC2, and the granine-like precursor of neuroendocrine protein proSAAS, a selective ligand of PC1, have been identified as endogenous inhibitors of the PCs found in the regulated pathway. However, only PCs prosegments, several bioengineered inhibitors, peptides, and non-peptide compounds were found to inhibit the activity of the PCs found in the secretory pathway.
Author: Xiaowei Sun
Publisher:
ISBN:
Category :
Languages : en
Pages :
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"Cancer is a leading cause of death worldwide and accounts for about one fifth of all death in the Western world. In 2008, nearly 12.7 million new cancer cases and 7.6 million cancer deaths occurred worldwide. The development of cancer is a multistage process, during which cells acquire a series of mutations that eventually lead to unrestrained cell growth, evasion of cell death, angiogenesis, invasion of the surrounding tissue and finally spreading to other parts of the body. The mammalian proprotein convertases (PCs) constitute a family of nine secretory serine proteases that are related to bacterial subtilisin and yeast kexin. They have been associated with cancer since the early 1990s. By processing cancer-associated factors, PCs are believed to play key roles in almost every step of cancer development. Seven of these PCs (PC1, PC2, furin, PC4, PC5/6, PACE4 and PC7) activate, or less frequently inactivate, a wide variety of substrates, including hormones, growth factors, receptors, adhesion molecules, angiogenic factors, metalloproteases. Among these substrates, some of them are key factors controlling cancer progression and metastasis. The last member of this family proprotein convertase subtilisin kexin 9 (PCSK9) only cleaves itself and participates in maintaining the levels of cholesterol, which was shown to have impacts on cancer incidence.In this thesis, I focused on the role of two PCs, PC5/6 and PCSK9, in cancer development. I first showed that PC5/6 is systematically down-regulated in human and mice intestinal tumors. In ApcMin/+ mice which are a colonic cancer model and develop numerous adenocarcinomas along the intestinal tract, the specific knockout of PC5/6 in the intestine and colon leads to higher number of tumors, particularly in duodenum. This suggests that PC5/6 plays a protective role against tumorigenesis in the intestine. Although PC5/6 is protective in intestinal cancer, it has been shown to promote tumor progression in other cancer types e.g., brain and skin. Interestingly, PC5/6 is inhibited by some natural inhibitors, the latent TGFbeta binding proteins 2 and 3 (LTBP-2, -3). These two proteins reduce the enzymatic activity of PC5/6A and reduce the bio-availability of PC5/6A by sequestering the zymogen proPC5/6 in the extracellular matrix. Finally, I demonstrated that the lack of PCSK9 leads to a significantly lower level of liver metastasis of melanoma cells. This cancer protective effect is due to low plasma cholesterol levels as well as high apoptosis in liver stroma and metastasized tumors that are associated with PCSK9 deficiency.In summary, the present cumulative data define some of the in vivo roles of PC5/6 and PCSK9 in cancer and should enhance our appreciation of the physiological impact of PC inhibition." --
Author: Abdel-Majid Khatib
Publisher: Springer Science & Business Media
ISBN: 1402051328
Category : Medical
Languages : en
Pages : 161
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Book Description
Convertases are widely expressed activating enzymes involved in various physiological and pathological processes. This book provides detailed and updated information on the role of these molecules in cancer. It is the first to summarize current knowledge of the importance of protein precursors maturation by the convertases in tumor progression, angiogenesis and metastasis. Each chapter discusses the importance of the convertases in the activation of various cancer-related molecules including growth factors, adhesion molecules and proteases.
Author: Daniel Bassi
Publisher: Morgan & Claypool Publishers
ISBN: 1615044647
Category : Cancer
Languages : en
Pages : 51
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Book Description
Gynecological cancers include neoplasias of internal female genital organs, mainly ovarian, endometrial and cervical tumors, and cancers of the external female genital structures. Current scientific evidence indicates that both up- and down-regulation of the expression of PCs are part of the multiple changes occurring in these gynecological tumors. Nevertheless, the physiological significance of this puzzling pattern of PC expression remains elusive. The fact that PCs can activate both pro- and anticarcinogenic substrates may indicate that the nature of the overexpressed substrates in certain cancer types could determine the final outcome; i.e., slowing or accelerating cancer development.
Author: Peter Merakos
Publisher: Morgan & Claypool
ISBN: 9781615044863
Category : Medical
Languages : en
Pages :
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Author: Janet Kwan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Proprotein convertases (PC) are proteases implicated in the regulation of mediators crucial for cancer growth and progression. The literature suggests that over-expression of some PCs contributes to tumorigenesis, invasion and metastasis in vivo; but evidence of the contrary also exists, where PC inhibition enhances cell migration and lung metastasis. The balance of these two opposing outcomes may determine the overall effect of specific PCs, resulting in cancers with increased or decreased aggressiveness. Preliminary data suggests that the expression of several PCs and a chaperone protein 7B2 is altered in human colorectal cancer (CRC) liver metastasis, and we hypothesize that the levels of active PCs in the primary CRC might predict progression and metastasis. To determine the effect of PCs (PACE4, PC5/6, PC7, Furin, PC1/3) and 7B2 in metastatic colon cancer cells, human CRC line HT-29 transfected with shRNA to the given genes was studied. The phenotypic ...
Author: Robert Shiu
Publisher:
ISBN:
Category :
Languages : en
Pages : 43
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Book Description
Proprotein convertases are members of a new class of endoproteolytic enzymes that are believed to play important roles in human neoplasia. Based on our previous detection of proprotein convertases in human breast tumors, the present study is designed to study the biological significance of these enzymes in breast cancer. Proprotein convertase gene transfections into MCF-7 human breast cancer cells led to profound changes in the breast cancer cells. MCF-7 cells that over-expressed proprotein convertases have become more dependent on estrogen for growth both in vitro and in vivo as tumors grown in athymic mice. As well, convertase-transfected breast cancer cells become more resistant to the anti-estrogen Tamoxifen. To further study the role of proprotein convertases in mammary gland development and tumorigenesis, transgenic mice bearing a convertase transgene targeted to the mammary gland have been generated. Characterization of these novel transgenic mice with respect to breast development and tumorigenesis is in progress.
Author: Geraldine Siegfried
Publisher: Biota Publishing
ISBN: 1615046119
Category : Medical
Languages : en
Pages : 68
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Book Description
The vascular endothelial growth factor (VEGF) family members that include VEGF-A, -B, -C, -D, and placental growth factor (PlGF), display distinct binding affinities for their receptors VEGFR-1, -2, and/or -3. In addition to their requirements in the initiation, development, and maintenance of blood and lymphatic vasculature, VEGFs and VEGFRs are upregulated during neoplasia and are involved in the remodeling of tumoral blood and lymphatic vasculature. By activating VEGFR-1 and VEGFR-2, both expressed on blood endothelial cells, VEGF-A promotes the formation of new tumoral blood vessels and thereby accelerates tumor growth. In contrast, upregulation of VEGF-C, a ligand for lymphatic endothelial VEGFR-3 as well as for VEGFR-2, induces the formation of tumor-associated lymphatic vessels and thus promotes the passive metastatic dissemination of tumor cells to regional lymph nodes. Of the VEGF family members, only VEGF-C and -D were found to be proteolytically processed by Furin-like enzymes. This processing controls the selective activation of VEGFR-2 and -3 signaling during tumor angiogenesis and lymphangiogenesis. Here, we provide an overview of angiogenesis processes and discuss the importance of VEGF-C and VEGF-D precursors processing by the proprotein convertases during the activation of VEGFR-2 and VEGFR-3 receptors and the mediation of their functions during angiogenesis, lymphangiogenesis, and tumorigenesis.
Author: Hillary Michelle Boulay
Publisher:
ISBN:
Category : Ovaries
Languages : en
Pages : 0
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