Data from Attenuation of Argininosuccinate Lyase Inhibits Cancer Growth via Cyclin A2 and Nitric Oxide

Abstract

<div>Abstract<p>Arginine biosynthesis and nitric oxide (NO) production are important for cancer homeostasis. Degradation of arginine may be used to inhibit liver tumors with low argininosuccinate synthetase (ASS) expression. In this report, we investigated an alternative therapeutic approach by targeting argininosuccinate lyase (ASL). ASL is transcriptionally induced by endoplasmic reticulum stress and is overexpressed in some human liver tumors. Knockdown of ASL expression by short hairpin RNA (shRNA) in three liver cancer cell lines, ML-1, HuH-7, and HepG2, decreased colony formation <i>in vitro</i> and tumor growth <i>in vivo</i>. Furthermore, lentiviral infection of <i>ASL</i> shRNA inhibited tumor growth in a therapeutic animal tumor model. Analysis of <i>ASL</i> shRNA on the cell-cycle progression revealed a G<sub>2</sub>–M delay. Among cell-cycle regulatory molecules, cyclin A2 expression was reduced. Reintroduction of exogenous cyclin A2 restored the cell growth in ASL-knockdown cells. Autophagy was observed in the cells treated with <i>ASL</i> shRNA, as shown by an increase in LC3-II levels and autophagosome formation. The total cellular arginine level was not altered significantly. Inhibition of autophagy further attenuated cell growth, suggesting that autophagy induced by <i>ASL</i> shRNA plays a feedback prosurvival function. Knockdown of ASL reduced NO content, and addition of NO donor partially recovered the growth inhibition by <i>ASL</i> shRNA. In summary, downregulation of ASL attenuated tumor growth and the inhibition was mainly mediated by a decrease of cyclin A2 and NO. <i>Mol Cancer Ther; 12(11); 2505–16. ©2013 AACR</i>.</p></div>