ARD1 stabilization of TSC2 suppresses tumorigenesis via the mTOR signaling pathway
Mammalian target of rapamycin (mTOR) plays an important role in regulating various cellular functions, and the tuberous sclerosis 1 (TSC1)/TSC2 complex serves as a major repressor of the mTOR pathway. Here we demonstrated that arrest-defective protein 1 (ARD1) physically interacts with, acetylates, and stabilizes TSC2, thereby reducing mTOR activity. The inhibition of mTOR by ARD1 suppresses cell proliferation and increases autophagy, which further impairs tumorigenicity. Correlation between the levels of ARD1 and TSC2 was found in multiple tumor types, suggesting the physiological importance of ARD1 in stabilizing TSC2. Moreover, evaluation of loss of heterozygosity (LOH) at Xq28 revealed allelic loss in 31% of tested breast cancer cell lines and tumor samples. Together, our findings suggest that ARD1 functions as a negative regulator of the mTOR pathway and that dysregulation of the ARD1/TSC2/mTOR axis may contribute to cancer development. To further explore the signaling pathway of ARD1, we provided evidence showing the phosphorylation of ARD1 by IKKβ, which mediated the destabilization of ARD1. Future work may be needed to study the biological effect of this post-translational modification. ^
Kuo, Hsu-Ping, "ARD1 stabilization of TSC2 suppresses tumorigenesis via the mTOR signaling pathway" (2009). Texas Medical Center Dissertations (via ProQuest). AAI3376906.