Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P42345 (mTOR)
 26,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Constitutive expression of hypoxia-inducible factor (HIF) has been implicated in several proliferative disorders. Constitutive expression of HIF1 alpha and HIF2 alpha has been linked to a number of human cancers, especially renal cell carcinoma (RCC), in which HIF2 alpha expression is the more important contributor. Expression of HIF1 alpha is dependent on the mammalian target of rapamycin (mTOR) and is sensitive to rapamycin. In contrast, there have been no reports linking HIF2 alpha expression with mTOR. mTOR exists in two complexes, mTORC1 and mTORC2, which are differentially sensitive to rapamycin. We report here that although there are clear differences in the sensitivity of HIF1 alpha and HIF2 alpha to rapamycin, both HIF1 alpha and HIF2 alpha expression is dependent on mTOR. HIF1 alpha expression was dependent on both Raptor (a constituent of mTORC1) and Rictor (a constitutive of mTORC2). In contrast, HIF2 alpha was dependent only on the mTORC2 constituent Rictor. These data indicate that although HIF1 alpha is dependent on both mTORC1 and mTORC2, HIF2 alpha is dependent only on mTORC2. We also examined the dependence of HIF alpha expression on the mTORC2 substrate Akt, which exists as three different isoforms, Akt1, Akt2, and Akt3. Interestingly, the expression of HIF2 alpha was dependent on Akt2, whereas that of HIF1 alpha was dependent on Akt3. Because HIF2 alpha is apparently more critical in RCC, this study underscores the importance of targeting mTORC2 and perhaps Akt2 signaling in RCC and other proliferative disorders in which HIF2 alpha has been implicated.
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PMID:Differential dependence of hypoxia-inducible factors 1 alpha and 2 alpha on mTORC1 and mTORC2. 1894 81

The vascular endothelial growth factor (VEGF) pathway blockers and mammalian target of rapamycin (mTOR) inhibitors have dramatically improved the treatment options and outcome for patients with advanced renal cell carcinoma (RCC). However, because the vast majority of patients will still succumb to their disease, novel treatment approaches are still necessary. Efforts to identify novel therapeutic target treatments are focused on better understanding unique aspects of tumor cell biology guided the Cancer Genome Atlas analyses and the interaction of the tumor with its microenvironment. Areas of promising investigation include a) the identification of mechanisms of acquired resistance to VEGF pathway inhibition and developing agents targeting these in combination with VEGF receptor (VEGFR) pathway blockade; b) the identification of novel therapeutic targets, particularly for patients with VEGF pathway blocker refractory disease; and c) the development of novel immunotherapies, particularly those involving checkpoint inhibitors used alone or in combination with other immunotherapies of VEGF pathway blockers. Specific targets or agents of interest include angiopoietins (trebaninib), c-Met (cabozantinib), activin receptor-like kinase-1 (ALK-1; dalantercept), interleukin (IL)-8, and HDM2 for acquired resistance to VEGF pathway inhibition; hypoxia inducible factor-2 alpha (HIF-2 alpha), TORC1/2, and the Hippo pathway for novel targets, and PD1 and PDL1 antibodies given either alone or in combination with other checkpoint inhibitors, other immunotherapies, or VEGF pathway blockers for novel immunotherapies. In addition, the application of genetic, immunologic, or other biomarkers developed in the context of this research has the potential to select patients with specific tumor types for therapy targeted to specific vulnerabilities within the tumor or tumor microenvironment. Together, these developments should enable the transition to a new era of rational and more effective therapy for patients with advanced RCC.
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PMID:New agents and new targets for renal cell carcinoma. 2485 6