Extracellular-matrix mediated regulation of human uterine leiomyoma smooth muscle cells and potential targeting by the anti-fibrotic drug halofuginone

Koohestani, Faezeh

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Description

Title

Extracellular-matrix mediated regulation of human uterine leiomyoma smooth muscle cells and potential targeting by the anti-fibrotic drug halofuginone

Author(s)

Koohestani, Faezeh

Issue Date

2013-02-03T19:47:25Z

Director of Research (if dissertation) or Advisor (if thesis)

Nowak, Romana A.

Doctoral Committee Chair(s)

Nowak, Romana A.

Committee Member(s)

• Flaws, Jodi A.
• Kim, Julie
• Miller, David J.

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Uterine leiomyoma
• Fibroids
• Extracellular Matrix (ECM)
• Collagen
• Smooth muscle cell
• platelet-derived growth factor (PDGF)
• Halofuginone
• Xenograft

Abstract

Uterine leiomyomas are known as the most commonly occurring neoplasms in women during their reproductive years. The overall incidence of these benign tumors can be as high as 70-80%, which represents a significant health problem to women. Patients suffer from abnormal uterine bleeding, pelvic pain, and reproductive dysfunctions. Available treatments for symptomatic patients are limited and this is in large part due to the fact that the mechanisms regulating the development and growth of these tumors are still not well understood. Two essential features of leiomyoma tumors, which arise from the uterine smooth muscle cells, are an increase in smooth muscle cell (SMC) proliferation and excessive, aberrant deposition of extracellular matrix (ECM) collagen. The objective of this dissertation was to first understand the mechanisms regulating the development and growth of leiomyoma tumors in the context of ECM collagen and second, to test the inhibitory effects of the anti-fibrotic drug, halofuginone (HF), on the growth of leiomyoma tumors in both in vitro and in vivo model systems. Our research in understanding the pathogenesis of leiomyomas showed that (1) monomeric and fibrillar forms of ECM collagen can differentially regulate the morphology and proliferation of leiomyoma smooth muscle cells (LSMCs); (2) physical properties of fibrillar collagen such as density and thickness can modulate the morphology and growth of LSMCs; (3) expression and localization of actin stress fibers as well as focal adhesion proteins such as vinculin and focal adhesion kinase are altered on different collagen matrices; (4) a synergistic effect between monomeric collagen and PDGF can further enhance the proliferation of LSMCs; and (5) the MAPK signaling pathway is involved in the interaction of LSMCs with collagen matrices. These findings demonstrate how the excess, aberrant deposition of ECM collagen in fibrotic uterine tissue can contribute to the the formation and growth of leiomyoma tumors through modulation of major cell signaling pathways. Our in vitro studies with the anti-fibrotic drug HF demonstrated that (1) this drug can inhibit LSMC proliferation under both basal and PDGF-stimulated conditions; (2) HF can significantly reduce transcript levels of COL11A1, COL3A1, TGFβ1, TGFβ3, DMT and LOX3 in a time-depenedent manner; (3) expression of collagen I and III proteins were reduced by HF in a time-dependent manner; (4) PDGF-stimulated activation of the MAPK and SRC signaling pathways is not significantly inhibited by HF; and (5) HF itself could also activate the MAPK and SRC signaling pathways. These findings suggest that the antifibrotic drug HF may be an effective therapeutic treatment for patients with ULs. Our compelementary in vivo studies on the effects of HF in a mouse model xenografted with human LSMCs showed that (1) treatment with HF at 0.25 mg/kg body weight/day and 0.5 mg/kg body weight/ every-other-day (EOD) were safe for host mice while 0.50 mg/kg body weight treatment on a daily basis was not well tolerated by mouse hosts; (2) all HF treatment regiments significantly reduced the volume of xenografted tumors; (3) tumor reduction in ULs xenografted on mice treated with 0.25 mg/kg body weight/day or 0.50 mg/kg body weight/EOD HF occurred through decreased cellular proliferation and increased apoptosis; (4) 0.25 mg/kg body weight/day or 0.50 mg/kg body weight/EOD HF did not change the expression of collagens I and III at the protein or transcript level; (5) transcripts of COL13A1 and TGFβ1, but not COL1A1, TGFβ3, DMT and LOX3, were altered by EOD HF treatment at 0.5 mg/kg body weight. These findings not only further validate the use of the UL-xenografted mouse model as an excellent model system to explore the mechanisms involved in the regulation of leiomyoma tumor growth, but also as a tool to fully assess the effectiveness of novel therapeutic drugs such as HF as well as their potential side effects for future clinical trials.

Graduation Semester

2012-12

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Copyright 2012 Faezeh Koohestani

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