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  • Anticancer peptidylarginine deiminase (PAD) inhibitors regulate the autophagy flux and the mammalian target of rapamycin complex 1 activity.

Anticancer peptidylarginine deiminase (PAD) inhibitors regulate the autophagy flux and the mammalian target of rapamycin complex 1 activity.

The Journal of biological chemistry (2012-05-19)
Yuji Wang, Pingxin Li, Shu Wang, Jing Hu, Xiangyun Amy Chen, Jianhui Wu, Megan Fisher, Kira Oshaben, Na Zhao, Ying Gu, Dong Wang, Gong Chen, Yanming Wang
ABSTRACT

Tumor suppressor genes are frequently silenced in cancer cells by enzymes catalyzing epigenetic histone modifications. The peptidylarginine deiminase family member PAD4 (also called PADI4) is markedly overexpressed in a majority of human cancers, suggesting that PAD4 is a putative target for cancer treatment. Here, we have generated novel PAD inhibitors with low micromolar IC(50) in PAD activity and cancer cell growth inhibition. The lead compound YW3-56 alters the expression of genes controlling the cell cycle and cell death, including SESN2 that encodes an upstream inhibitor of the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. Guided by the gene expression profile analyses with YW3-56, we found that PAD4 functions as a corepressor of p53 to regulate SESN2 expression by histone citrullination in cancer cells. Consistent with the mTORC1 inhibition by SESN2, the phosphorylation of its substrates including p70S6 kinase (p70S6K) and 4E-BP1 was decreased. Furthermore, macroautophagy is perturbed after YW3-56 treatment in cancer cells. In a mouse xenograft model, YW3-56 demonstrates cancer growth inhibition activity with little if any detectable adverse effect to vital organs, whereas a combination of PAD4 and histone deacetylase inhibitors further decreases tumor growth. Taken together, our work found that PAD4 regulates the mTORC1 signaling pathway and that PAD inhibitors are potential anticancer reagents that activate tumor suppressor gene expression alone or in combination with histone deacetylase inhibitors.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-p21WAF1/Cip1antibody, Mouse monoclonal, clone CP74, purified from hybridoma cell culture
Sigma-Aldrich
Anti-β-Actin antibody, Mouse monoclonal, clone AC-15, purified from hybridoma cell culture