Shanmugasundaram, K; Block, K; Nayak, B K; Livi, C B; Venkatachalam, M A; Sudarshan, S
The cyclin-dependent kinase inhibitor p27 is a key regulator of cell-cycle progression. Its expression and localization are altered in several types of malignancies, which has prognostic significance in cancers such as renal cell carcinoma (RCC). S-phase kinase-associated protein 2 (SKP-2) is an F-box protein that is part of the SKP-1/Cul1/F-box ubiquitin ligase complex that targets nuclear p27 among many other cell-cycle proteins for proteosomal degradation. Its overexpression has been observed in several tumor types. Signaling by phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) has previously been shown to regulate the SKP-2/p27 axis. Recent evidence suggests that PI3K signaling may activate mammalian target of rapamycin complex 2 (mTORC2) activity. As PI3K signaling is known to regulate SKP-2 and p27, we sought to determine whether these effects were mediated by mTORC2. Here we provide additional genetic evidence that PI3K signaling activates mTORC2 kinase activity. We also demonstrate a novel role for mTORC2 in the modulation of nuclear p27 levels. In particular, mTORC2 signaling promotes the reduction of nuclear p27 protein levels through the increased protein expression of SKP-2. These are the first data to demonstrate a role for mTOR in the regulation of SKP-2. In concordance with these findings, mTORC2 activity promotes cell proliferation of RCC cells at the G1-S interphase of the cell cycle. Collectively, these data implicate mTORC2 signaling in the regulation of the SKP-2/p27 axis, a signaling node commonly altered in cancer.
Diseases/Pathways annotated by Medline MESH:
Carcinoma, Renal Cell, Kidney Neoplasms
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Text Mining Data
mTORC2 → PI3K: " Here we provide additional genetic evidence that PI3K
signaling activates mTORC2
kinase activity "
p27 ⊣ mTORC2: " We also demonstrate a novel role for mTORC2 in the modulation of nuclear p27 levels "
SKP-2 ⊣ mTOR: " These are the first data to demonstrate a role for mTOR in the regulation of SKP-2 "
Manually curated Databases
No curated data.