PAD1 promotes epithelial-mesenchymal transition and metastasis in triple-negative breast cancer cells by regulating MEK1-ERK1/2-MMP2 signaling.

UMMS Affiliation

Thompson Lab; Department of Biochemistry and Molecular Pharmacology

Publication Date


Document Type



Biochemistry | Cancer Biology | Enzymes and Coenzymes | Medicinal-Pharmaceutical Chemistry


Peptidylargininedeiminase 1 (PAD1) catalyzes protein for citrullination, and this activity has been linked to the epidermal cornification. However, a role for PAD1 in tumorigenesis, including breast cancers has not been previously explored. Here we first showed that PAD1 is overexpressed in human triple negative breast cancer (TNBC). In cultured cells and xenograft mouse models, PAD1 depletion or inhibition reduced cell proliferation, suppressed epithelial-mesenchymal transition, and prevented metastasis of MDA-MB-231 cells. These changes were correlated with a dramatic decrease in MMP2/9 expression. Furthermore, ERK1/2 and P38 MAPK signaling pathways are activated upon PAD1 silencing. Treatment with MEK1/2 inhibitor in PAD1 knockdown cells significantly recovered MMP2 expression, while inhibiting P38 activation only slightly elevated MMP9 levels. We then showed that PAD1 interacts with and citrullinates MEK1 thereby disrupting MEK1-catalyzed ERK1/2 phosphorylation, thus leading to the MMP2 overexpression. Collectively, our data indicate that PAD1 appears to promote tumorigenesis by regulating MEK1-ERK1/2-MMP2 signaling in TNBC. These results also raise the possibility that PAD1 may function as an important new biomarker for TNBC tumors and suggest that PAD1-specific inhibitors could potentially be utilized to treat metastatic breast cancer.


Animals, Cell Line, Tumor, Cell Proliferation, Epithelial-Mesenchymal Transition, Female, HEK293 Cells, Humans, Hydrolases, MAP Kinase Kinase 1, MAP Kinase Signaling System, MCF-7 Cells, Matrix Metalloproteinase 2, Mice, Mice, Inbred BALB C, Mice, Nude, Ornithine, Triple Negative Breast Neoplasms, Xenograft Model Antitumor Assays

DOI of Published Version



Cancer Lett. 2017 Nov 28;409:30-41. doi: 10.1016/j.canlet.2017.08.019. Epub 2017 Aug 24. Link to article on publisher's site

Journal/Book/Conference Title

Cancer letters

Related Resources

Link to article in PubMed

PubMed ID