Date of Award

5-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Environmental Toxicology

Advisor

Dr. Charles Rice

Committee Member

Dr. Lisa J. Bain

Committee Member

Dr. Vincent S. Gallicchio

Committee Member

Dr. Yanzhang Wei

Abstract

Indirubin is a deep-red bis-indole isomer of indigo blue, both of which are biologically active ingredients in Danggui Longhui Wan, an ancient Chinese herbal tea mixture used to treat neoplasia and chronic inflammation, and to enhance detoxification of xenobiotics. Multiple indirubin derivatives have been synthesized and shown to inhibit cyclin-dependent kinases (CDKs) and glycogen-synthase kinase (GSK-3β) with varying degrees of potency. Several indirubins are also aryl hydrocarbon receptor (AhR) agonists, with AhR-associated activities covering a wide range of potencies, depending on structure-activity-relationships (SAR). In this study, the effects on indirubin-3’-(2,3 dihydroxypropyl)-oximether (E804), a novel indirubin derivative with potent effects on STAT3 signaling, on LPS-stimulated inflammatory profiles in RAW264.7 murine macrophages were examined. Most genes, proteins, and biological functions up-regulated by LPS treatment were suppressed by E804, including LPS-induced expression and secretion of pro-inflammatory cytokines. Additionally, E804 enhanced HO-1 expression, which may promote antioxidant responses to control inflammation. However, RAW264.7 cells showed only modest CYP1A1 induction following treatment, thus at this time it is not clear if E804 modulates inflammatory responses in RAW264.7 cells through AhR signaling. To further explore the possible effects of E804 on AhR signaling, THP-1 human monocytes were differentiated to macrophages by a 48 hr treatment with phorbol-12-myristate-13-acetate (PMA), then treated with E804 and treatment with phorbol-12-myristate-13-acetate (PMA), then treated with E804 and and potent inducer of CYP1A1. CYP1A1 gene and protein expression were significantly induced by 7-bromoindirubin-3'-oxime (7BIO), another novel indirubin, and PCB-126, but not E804. Furthermore, both 7BIO and E804 suppressed IL-6 and IL-10 secretion, thus confirming that AhR signaling is not a requirement for the anti-inflammatory properties of this compound. Of particular note, 7BIO is a potent inducer of COX-2, another potent pro-inflammatory mediator known to be activated through the AhR. Taken together, this study demonstrates potent anti-inflammatory properties of E804 without the toxicities historically associated with AhR activity. These findings can be applied to development anti-inflammatory drugs that may replace current methods for topical inflammation control.

Included in

Toxicology Commons

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