PRAS40 alleviates neurotoxic prion peptide-induced apoptosis via mTOR-AKT signaling.

AIMS: The proline-rich Akt substrate of 40-kDa (PRAS40) protein is a direct inhibitor of mTORC1 and an interactive linker between the Akt and mTOR pathways. The mammalian target of rapamycin (mTOR) is considered to be a central regulator of cell growth and metabolism. Several investigations have demonstrated that abnormal mTOR activity may contribute to the pathogenesis of several neurodegenerative disorders and lead to cognitive deficits. METHODS: Here, we used the PrP peptide 106-126 (PrP106-126 ) in a cell model of prion diseases (also known as transmissible spongiform encephalopathies, TSEs) to investigate the mechanisms of mTOR-mediated cell death in prion diseases. RESULTS: We have shown that, upon stress caused by PrP106-126 , the mTOR pathway activates and contributes to cellular apoptosis. Moreover, we demonstrated that PRAS40 down-regulates mTOR hyperactivity under stress conditions and alleviates neurotoxic prion peptide-induced apoptosis. The effect of PRAS40 on apoptosis is likely due to an mTOR/Akt signaling. CONCLUSION: PRAS40 inhibits mTORC1 hyperactivation and plays a key role in protecting cells against neurotoxic prion peptide-induced apoptosis. Thus, PRAS40 is a potential therapeutic target for prion disease.

Feasibility and activity of sorafenib and sunitinib in advanced penile cancer: a preliminary report.

INTRODUCTION: We describe our experience with sorafenib and sunitinib in the treatment of chemotherapy-refractory advanced penile squamous cell carcinoma (SCC). PATIENTS AND METHODS: Between May 2008 and June 2009, 6 advanced penile cancer patients were treated with sorafenib or sunitinib in our center. All of them had previously received at least two chemotherapy regimens. Tumor responses were evaluated by radiologic assessment and serum SCC antigen change. Immunohistochemical staining of CD34 and Ki-67 was performed in 3 paired tumor tissues before and after treatment. RESULTS: In the 6 patients, 1 partial response and 4 stable diseases were observed. Three patients showed pain response and had an improvement in quality of life. After molecular-targeted therapies, reduction in microvessel density and Ki-67 labeling index was observed in paired specimens. Serum SCC antigen levels were decreased in 5 patients after 1 week of medication. The patient who achieved partial response had an SCC antigen reduction of nearly 95% after treatment with sunitinib. Serious adverse events were fatal infection and rupture of the femoral vessel, which were unlikely related to the medication. CONCLUSIONS: The feasibility and activity of sorafenib and sunitinib in our series suggest that this approach may be a promising alternative in chemotherapy-refractory advanced penile SCC.