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)

A substrate for PKBalpha (protein kinase Balpha) was detected in liver extracts, and was purified and identified as CRHSP24 (calcium-regulated heat-stable protein of apparent molecular mass 24 kDa). PKBalpha, as well as SGK1 (serum- and glucocorticoid-induced protein kinase 1) and RSK (p90 ribosomal S6 kinase), phosphorylated CRHSP24 stoichiometrically at Ser52 in vitro and its brain-specific isoform PIPPin at the equivalent residue (Ser58). CRHSP24 became phosphorylated at Ser52 when HEK-293 (human embryonic kidney) cells were stimulated with IGF-1 (insulin-like growth factor-1) and this was prevented by inhibitors of PI3K (phosphoinositide 3-kinase), but not by rapamycin [an inhibitor of mTOR (mammalian target of rapamycin)] or PD 184352, an inhibitor of the classical MAPK (mitogen-activated protein kinase) cascade and hence the activation of RSK. IGF-1 induced a similar phosphorylation of CRHSP24 in ES (embryonic stem) cells from wild-type mice or mice that express the PDK1 (3-phosphoinositide-dependent kinase 1) mutant (PDK1[L155E]) that activates PKBalpha normally, but cannot activate SGK. CRHSP24 also became phosphorylated at Ser52 in response to EGF (epidermal growth factor) and this was prevented by blocking activation of both the classical MAPK cascade and the activation of PKBalpha, but not if just one of these pathways was inhibited. DYRK2 (dual-specificity tyrosine-phosphorylated and -regulated protein kinase 2) phosphorylated CRHSP24 at Ser30, Ser32 and Ser41 in vitro, and Ser41 was identified as a site phosphorylated in cells. These and other results demonstrate that CRHSP24 is phosphorylated at Ser52 by PKBalpha in response to IGF-1, at Ser52 by PKBalpha and RSK in response to EGF, and at Ser41 in the absence of IGF-1/EGF by a DYRK isoform or another proline-directed protein kinase(s).
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PMID:Identification of calcium-regulated heat-stable protein of 24 kDa (CRHSP24) as a physiological substrate for PKB and RSK using KESTREL. 1591 Feb 84

Interferon-gamma (IFN-gamma) is known to downregulate HER2 oncoprotein (p185(HER2) or briefly p185) in prostate cancer cells. We demonstrate that the IFN-gamma-induced retinoid-inducible gene 1 (RIG1) acts as a transrepressor of p185. Furthermore, we exhibit that RIG1 downregulates the activated (phosphorylated) form of p185 and phosphoinositide-3 kinase (PI3K)/serine/threonine-specific protein kinase (Akt) and the mammalian target of rapamycin (mTOR), downstream substrates of HER2. We also elucidate that heregulin (HRG) specifically restores the activation of p185 and Akt after their activities are reduced by RIG1. Additionally, expression of vascular endothelial growth factor (VEGF) increases through the HER2- and Akt/mTOR-signaling pathways, indicating that VEGF is downregulated by RIG1 within the cell. These findings suggest that RIG1 plays a role in IFN-gamma-mediated therapy by downregulating p185 and its downstream PI3K/Akt/mTOR/VEGF-signaling pathway. These results may provide a new therapeutic mechanism for the clinical use of IFN-gamma and RIG1.
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PMID:Downregulation of HER2 by RIG1 involves the PI3K/Akt pathway in ovarian cancer cells. 1817 56

Molecular targeted therapies represent an interesting field of pharmacological research in endometrial cancer. The loss of PTEN (phosphatase and tensin homolog deleted on chromosome 10) function, with consequent activation of the PI3K (phosphatidylinositol-3-kinase)-AKT (serine/threonine-specific protein kinase)-mTOR (mammalian target of rapamycin) signaling pathway, occurs in 32-83% of endometrioid-type endometrial carcinomas, thus suggesting a role for mTOR inhibition in this malignancy. Some analogues of rapamycin (CCI-799, RAD-001, AP-23573) have been developed and tested in different tumors including endometrioid-type endometrial carcinoma. For example, AP-23573 achieved a clinical benefit response in 33% of 27 heavily pretreated patients, and CCI-799 obtained a 26% partial response rate and a 63% stable disease rate in 19 patients. Overexpression of ErbB-2 (epidermal growth factor type II receptor) has been detected in 18-80% of uterine papillary serous carcinomas (UPSCs), thus providing a biological rationale for the use of trastuzumab in these aggressive tumors. UPSC often overexpresses claudin-3 and claudin-4, which represent the epithelial receptors for Clostridium perfringens enterotoxin (CPE). CPE-mediated therapy might be a novel treatment modality for UPSC resistant to chemotherapy. A better understanding of the signaling transduction pathways that are dysregulated in endometrioid-type endometrial carcinoma and UPSC will allow the development of novel molecular targeted therapies.
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PMID:Molecular target therapies in endometrial cancer: from the basic research to the clinic. 1856 27

Autophagy, or autophagocytosis, is a selective intracellular degradative process involving the cell's own lysosomal apparatus. An essential component in cell development, homeostasis, repair and resistance to stress, autophagy may result in either cell death or survival. The targeted region of the cell is sequestered within a membrane structure, the autophagosome, for regulation of the catabolic process. A key factor in both autophagosome formation and autophagosome maturation is a protein encoded by the ultraviolet irradiation resistance-associated gene (UVRAG). Conversely, the serine/threonine-specific protein kinase B (PKB, also known as Akt), which regulates survival in various cancers, inhibits autophagy through mTOR activation. We found that Akt1 may also directly inhibit autophagy by down-regulating UVRAG both in a 293T transient transfection system and breast cancer cells stably expressing Akt1. The UVRAG with mutations at putative Akt1-phosphorylation sites were still inhibited by Akt1, and dominant-negative Akt1 also inhibited UVRAG expression, suggesting that Akt1 down-regulates UVRAG by a kinase activity-independent mechanism. We showed that Akt1 overexpression in MDA-MB-231 breast cancer cells down-regulated UVRAG transcription. Cells over-expressing Akt1 were more resistant than control cells to ultraviolet light-induced autophagy and exhibited the associated reduction in cell viability. Levels of the autophagosome indicator protein LC3B-II and mRFP-GFP-LC3 were reduced in cells that over-expressing Akt1. Inhibiting Akt1 by siRNA or reintroducing UVRAG gene rescued the level of LC3B-II in UV-irradiation. Altogether, these data suggest that Akt1 may inhibit autophagy by decreasing UVRAG expression, which also sensitizes cancer cells to UV irradiation.
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PMID:Protein kinase B/Akt1 inhibits autophagy by down-regulating UVRAG expression. 2320 Sep 33

Akt, better known as protein kinase B (PKB), is a serine/threonine-specific protein kinase which acts as mediator via PI3K/Akt pathway in many biological processes like glucose metabolism, apoptosis, cell differentiation and transcription. Akt1 gene amplification has been implicated in gastric carcinoma while Akt2 amplification has been linked with ovarian, pancreas, breast and stomach tumors. The use of Akt inhibitors as monotherapy or in combination with other anticancer drugs could be useful for combating drug resistance and improving response. Thus, comprehensive understanding of Akt and its linked signaling pathways (PI3K, PKB, mTOR etc.) is necessary to lead to newer drug development and use.
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PMID:Akt inhibitors: mechanism of action and implications for anticancer therapeutics. 2433 Aug 34

Iminosugars have gained a remarkable importance as new therapeutic agents since 1966. In this study, compounds A and B, two iminosugar analogs synthesized previously, showed an inhibition of the growth of K562 cells. They allowed cell cycle arrested at the G0/G1 phase, promoted apoptotic activities and also lowered the mitochondrial membrane potential. Further exploration of the apoptosis mechanism revealed that compound B significantly suppressed the expression of Hsp70, which is a major anti-apoptotic molecular chaperone. Significant decrease was also found in the expression of Akt, a serine/threonine-specific protein kinase with anti-apoptosis activities also known as protein kinase B (PKB). At mitochondria level in comparison with compound A, compound B brought a better promotion in the expression of pro-apoptotic protein Bad in Bcl-2 family. As a result of the promotion, the expression of anti-apoptotic protein Bcl-xL was down-regulated. Cytochrome c was released, activating the intrinsic signaling pathways of caspase and resulting in the occurrence of cascade reaction. In addition, compound B stimulated autophagy effectively by up-regulating Beclin 1, thus causing the conversion of LC3-I to LC3-II through Akt/mTOR signaling pathway. In summary, these results indicated that compounds A and B induced cell death through multiple pathways. The disclosed results not only provide an evidence of antitumor activity of iminosugars as a foundation for further studies, but also may find potential applications in chronic myeloid leukemia therapy as new heat shock protein inhibitors and autophagy inducer.
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PMID:Cell cycle arrest, apoptosis and autophagy induced by iminosugars on K562 cells. 2465 62

Mammalian sterile 20-like 1 (Mst1), an upstream serine/threonine-specific protein kinase of the Hippo pathway, is reported to play important roles in tumor suppression and organ size regulation in mammals via regulating cell proliferation and survival. However, whether it is involved in the pathogenesis of malignant gliomas remains poorly understood. Therefore, in the present work, we examined the effect and mechanism of Mst1 on the proliferation and apoptosis of malignant glioma cells. The cell proliferation and growth of glioma cells were examined by EdU incorporation and CCK-8 assay. In addition, the cell apoptosis was assessed by flow cytometry. We found that down-regulation of Mst1 promoted glioma cell proliferation and growth, but inhibited the cell apoptosis. Consistent with this, over-expression of Mst1 inhibited glioma cell proliferation and growth. Interestingly, Mst1 did not affect the phosphorylation of YAP1, the key downstream molecule of Hippo pathway. However, Mst1 was found to bind to AKT in glioma cell and negatively regulated AKT and mTOR activity. Finally, the increased cell proliferation rate induced by Mst1 down-regulation was partially abolished by down-regulation of AKT1. Meanwhile, glioma cell growth inhibition induced by Mst1 over-expression was partially rescued by over-expression of AKT1. Taken together, these findings suggest that Mst1 regulates proliferation of glioma cells via AKT/mTOR signaling pathway.
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PMID:Mst1 regulates glioma cell proliferation via the AKT/mTOR signaling pathway. 2537 46

Despite the development of standard therapies, including surgery, radiotherapy and chemotherapy, survival rates for head and neck squamous cell carcinoma (HNSCC) have not changed significantly over the past three decades. Complete recovery is achieved in <50% of patients. The treatment of advanced HNSCC frequently requires multimodality therapy and involves significant toxicity. The promising, novel treatment option for patients with HNSCC is molecular-targeted therapies. The best known targeted therapies include: Epidermal growth factor receptor (EGFR) monoclonal antibodies (cetuximab, panitumumab, zalutumumab and nimotuzumab), EGFR tyrosine kinase inhibitors (gefitinib, erlotinib, lapatinib, afatinib and dacomitinib), vascular endothelial growth factor (VEGF) inhibitor (bevacizumab) or vascular endothelial growth factor receptor (VEGFR) inhibitors (sorafenib, sunitinib and vandetanib) and inhibitors of phosphatidylinositol 3-kinase/serine/threonine-specific protein kinase/mammalian target of rapamycin. There are also various inhibitors of other pathways and targets, which are promising and require evaluation in further studies.
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PMID:Application of molecular targeted therapies in the treatment of head and neck squamous cell carcinoma. 2972 56

Cardiovascular diseases comprise of non-communicable disorders that involve the heart and/or blood vessels and have become the leading cause of death worldwide with increased prevalence by age. mTOR is a serine/threonine-specific protein kinase which plays a central role in many physiological processes including cardiovascular diseases, and also integrates various proliferative signals, nutrient and energy abundance and stressful situations. mTOR also acts as central regulator during chronic stress, mitochondrial dysfunction and deregulated autophagy which are associated with senescence. Under oxidative stress, mTOR has been reported to exert protective effects regulating apoptosis and autophagy processes and favoring tissue repair. On the other hand, inhibition of mTOR has been suggested to have beneficial effects against atherosclerosis, cardiac hypertrophy and heart failure, and also in extending the lifespan. In this aspect, the use of drugs or natural compounds, which can target mTOR is an interesting approach in order to reduce the number of deaths caused by cardiovascular disease. In the present review, we intend to shed light on the possible effects and molecular mechanism of natural agents like polyphenols via regulating mTOR.
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PMID:Therapeutic potential of polyphenols in cardiovascular diseases: Regulation of mTOR signaling pathway. 3190 7