Phenotype anchoring in zebrafish reveals a potential role for matrix metalloproteinases (MMPs) in tamoxifen's effects on skin epithelium.

TitlePhenotype anchoring in zebrafish reveals a potential role for matrix metalloproteinases (MMPs) in tamoxifen's effects on skin epithelium.
Publication TypeJournal Article
Year of Publication2016
AuthorsBugel, SM, Wehmas, LC, La Du, JK, Tanguay, RL
JournalToxicol Appl Pharmacol
Date Published2016 Apr 01
KeywordsAnimals, Animals, Genetically Modified, Dose-Response Relationship, Drug, Epidermis, Epithelium, Estrogen Antagonists, Matrix Metalloproteinases, Necrosis, Phenotype, Skin, Tamoxifen, Zebrafish

The zebrafish is a powerful alternative model used to link phenotypes with molecular effects to discover drug mode of action. Using a zebrafish embryo-larval toxicity bioassay, we evaluated the effects of tamoxifen--a widely used anti-estrogen chemotherapeutic. Zebrafish exposed to ≥ 10 μM tamoxifen exhibited a unique necrotic caudal fin phenotype that was rapidly induced regardless of developmental life-stage when treatment was applied. To define tamoxifen's bioactivity resulting in this phenotype, targeted gene expression was used to evaluate 100 transcripts involved in tissue remodeling, calcium signaling, cell cycle and cell death, growth factors, angiogenesis and hypoxia. The most robustly misregulated transcripts in the tail were matrix metalloproteinases mmp9 and mmp13a, induced 127 and 1145 fold, respectively. Expression of c-fos, c-jun, and ap1s1 were also moderately elevated (3-7 fold), consistent with AP-1 activity--a transcription factor that regulates MMP expression. Immunohistochemistry confirmed high levels of induction for MMP13a in affected caudal fin skin epithelial tissue. The necrotic caudal fin phenotype was significantly attenuated or prevented by three functionally unique MMP inhibitors: EDTA (metal chelator), GM 6001 (broad MMP inhibitor), and SR 11302 (AP-1 transcription factor inhibitor), suggesting MMP-dependence. SR 11302 also inhibited induction of mmp9, mmp13a, and a putative MMP target, igfbp1a. Overall, our studies suggest that tamoxifen's effect is the result of perturbation of the MMP system in the skin leading to ectopic expression, cytotoxicity, and the necrotic caudal fin phenotype. These studies help advance our understanding of tamoxifen's non-classical mode of action and implicate a possible role for MMPs in tissues such as skin.

Alternate JournalToxicol. Appl. Pharmacol.
PubMed ID26908177
PubMed Central IDPMC4792761
Grant ListK99 ES025280 / ES / NIEHS NIH HHS / United States
P30 ES000210 / ES / NIEHS NIH HHS / United States
P42 ES016465 / ES / NIEHS NIH HHS / United States
T32 ES007060 / ES / NIEHS NIH HHS / United States