Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P31749 (AKT)
 22,954 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutational activation of RAS proteins occurs in nearly 30% of all human tumors. To date direct pharmacological inhibition of RAS oncoproteins has not been possible. As a consequence, current strategies are focusing on the development of inhibitors that target those kinases acting downstream of RAS proteins, including those of the RAF/MEK/ERK and PI3K/AKT pathways. Most of these inhibitors have undesired off-target effects that mask the potential therapeutic effect of blocking their targeted kinases. To facilitate the screening of selective inhibitors, we have generated lines of mouse embryonic fibroblasts that lack endogenous Ras proteins. These cells proliferate due to ectopic expression of either Ras oncoproteins that selectively activate the Raf/Mek/Erk pathway such as H-Ras(G12V/D38E) or constitutively active kinases such as B-Raf and Mek1. These cell lines were exposed to inhibitors against the RAF, MEK, and AKT kinases as well as inhibitors of other kinases known to crosstalk with RAS signaling such as JNK and p38. Amongst all compounds tested, only the MEK inhibitors U0126 and PD0325901, showed the expected specificity pattern. Yet, PD0325901, but not U0126, was able to inhibit a cell line lacking Ras proteins that owed its proliferative properties to loss of p53. Thus, suggesting unexpected off-target activities for this compound. The use of cell lines whose proliferative properties exclusively depend on selective targets provide a novel strategy to analyze the specificity of selective inhibitors designed against molecular targets implicated in human cancer.
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PMID:Using cells devoid of RAS proteins as tools for drug discovery. 1952 60

The basic biology underlying the development of clear-cell renal cell carcinoma (ccRCC) is critically dependent on the von Hippel-Lindau gene (VHL), whose protein product is important in the cell's normal response to hypoxia. Aberrations in VHL's function, either through mutation or promoter hypermethylation, lead to accumulation of the transcriptional regulatory molecule, hypoxia-inducible factor alpha (HIFalpha). HIFalpha can then dimerize with HIFbeta and translocate to the nucleus, where it will transcriptionally upregulate a series of hypoxia-responsive genes, including vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and others. Binding of these ligands to their cognate receptors activates a series of kinase- dependent signaling pathways, including the RAF-MEK-ERK and phosphatidylinositol-3 kinase-AKT-mTOR pathways. Targeted agents developed and now approved for use in advanced ccRCC include humanized monoclonal antibodies against VEGF, small-molecule tyrosine kinase inhibitors, and inhibitors of mTOR. Understanding the biology of ccRCC is critical in understanding the current therapy for the disease and in developing novel therapeutics in the future. This review will provide an overview of the genetics of ccRCC, with an emphasis on how this has informed the development of the targeted therapeutics for this disease.
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PMID:The role of VHL in clear-cell renal cell carcinoma and its relation to targeted therapy. 1965 25

Lovastatin is a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor. Its inhibitory action on HMG-CoA reductase leads to depletion of isoprenoids, which inhibits post-translational modification of RAS. In this study, we investigated the effect of combining lovastatin with gefitinib on gefitinib-resistant human non-small cell lung cancer (NSCLC) cell lines with K-Ras mutations. Antitumor effects were measured by growth inhibition and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Effects on apoptosis were determined by flow cytometry, DNA fragmentation, and immunoblots. Protein levels of RAS, AKT/pAKT, and RAF/ERK1/2 in cancer cells were analyzed by immunoblot. Compared with gefitinib alone, a combination of gefitinib with lovastatin showed significantly enhanced cell growth inhibition and cytotoxicity in gefitinib-resistant A549 and NCI-H460 human NSCLC cells. In addition, lovastatin combination treatment significantly increased gefitinib-related apoptosis, as determined by fluorescence microscopy and flow cytometric analysis. These effects correlated with up-regulation of cleaved caspase-3, poly (ADP-ribose) polymerase (PARP), and Bax and down-regulation of Bcl-2. The combination of lovastatin and gefitinib effectively down-regulated RAS protein and suppressed the phosphorylation of RAF, ERK1/2, AKT, and EGFR in both cell lines. Taken together, these results suggest lovastatin can overcome gefitinib resistance, in NSCLC cells with K-Ras mutations, by down regulation of RAS protein, which leads to inhibition of both RAF/ERK and AKT pathways.
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PMID:Lovastatin overcomes gefitinib resistance in human non-small cell lung cancer cells with K-Ras mutations. 1976 Jan 59

Patients with neurofibromatosis type 1 (NF1) carry approximately a 10% lifetime risk of developing a malignant peripheral nerve sheath tumor (MPNST). Although the molecular mechanisms underlying NF1 to MPNST malignant transformation remain unclear, alterations of both the RAS/RAF/MAPK and PI3K/AKT/mTOR signaling pathways have been implicated. In a series of genetically engineered murine models, we perturbed RAS/RAF/MAPK or/and PTEN/PI3K/AKT pathway, individually or simultaneously, via conditional activation of K-ras oncogene or deletion of Nf1 or Pten tumor suppressor genes. Only K-Ras activation in combination with a single Pten allele deletion led to 100% penetrable development of NF lesions and subsequent progression to MPNST. Importantly, loss or decrease in PTEN expression was found in all murine MPNSTs and a majority of human NF1-associated MPNST lesions, suggesting that PTEN dosage and its controlled signaling pathways are critical for transformation of NFs to MPNST. Using noninvasive in vivo PET-CT imaging, we demonstrated that FDG can be used to identify the malignant transformation in both murine and human MPNSTs. Our data suggest that combined inhibition of RAS/RAF/MAPK and PTEN/PI3K/AKT pathways may be beneficial for patients with MPNST.
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PMID:PTEN dosage is essential for neurofibroma development and malignant transformation. 2037 64

CUDC-305 is a heat shock protein 90 (HSP90) inhibitor of the novel imidazopyridine class. Here, we report its activities in non-small cell lung cancer (NSCLC) cell lines with gene deregulations conferring primary or secondary resistance to epidermal growth factor receptor (EGFR) inhibitors. We show that CUDC-305 binds strongly to HSP90 extracted from erlotinib-resistant NSCLC cells (IC50 70 nmol/L). This result correlates well with the potent antiproliferative activity in erlotinib-resistant NSCLC cell lines (IC50 120-700 nmol/L) reported previously. Furthermore, it exhibits durable inhibition of multiple oncoproteins and induction of apoptosis in erlotinib-resistant NSCLC cells. CUDC-305 potently inhibits tumor growth in subcutaneous xenograft models of H1975 and A549, which harbor EGFR T790M mutation or K-ras mutations conferring acquired and primary erlotinib resistance, respectively. In addition, CUDC-305 significantly prolongs animal survival in orthotopic lung tumor models of H1975 and A549, which may be partially attributed to its preferential exposure in lung tissue. Furthermore, CUDC-305 is able to extend animal survival in a brain metastatic model of H1975, further confirming its ability to cross the blood-brain barrier. Correlating with its effects in various tumor models, CUDC-305 induces degradation of receptor tyrosine kinases and downstream signaling molecules of the PI3K/AKT and RAF/MEK/ERK pathways simultaneously, with concurrent induction of apoptosis in vivo. In a combination study, CUDC-305 enhanced the antitumor activity of a standard-of-care agent in the H1975 tumor model. These results suggest that CUDC-305 holds promise for the treatment of NSCLC with primary or acquired resistance to EGFR inhibitor therapy.
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PMID:Targeting heat shock protein 90 with CUDC-305 overcomes erlotinib resistance in non-small cell lung cancer. 1995 21

Activation of phosphatidylinositol-3-kinase (PI3K)-AKT and Kirsten rat sarcoma viral oncogene homologue (KRAS) can induce cellular immortalization, proliferation, and resistance to anticancer therapeutics such as epidermal growth factor receptor inhibitors or chemotherapy. This study assessed the consequences of inhibiting these two pathways in tumor cells with activation of KRAS, PI3K-AKT, or both. We investigated whether the combination of a novel RAF/vascular endothelial growth factor receptor inhibitor, RAF265, with a mammalian target of rapamycin (mTOR) inhibitor, RAD001 (everolimus), could lead to enhanced antitumoral effects in vitro and in vivo. To address this question, we used cell lines with different status regarding KRAS, PIK3CA, and BRAF mutations, using immunoblotting to evaluate the inhibitors, and MTT and clonogenic assays for effects on cell viability and proliferation. Subcutaneous xenografts were used to assess the activity of the combination in vivo. RAD001 inhibited mTOR downstream signaling in all cell lines, whereas RAF265 inhibited RAF downstream signaling only in BRAF mutant cells. In vitro, addition of RAF265 to RAD001 led to decreased AKT, S6, and Eukaryotic translation initiation factor 4E binding protein 1 phosphorylation in HCT116 cells. In vitro and in vivo, RAD001 addition enhanced the antitumoral effect of RAF265 in HCT116 and H460 cells (both KRAS mut, PIK3CA mut); in contrast, the combination of RAF265 and RAD001 yielded no additional activity in A549 and MDAMB231 cells. The combination of RAF and mTOR inhibitors is effective for enhancing antitumoral effects in cells with deregulation of both RAS-RAF and PI3K, possibly through the cross-inhibition of 4E binding protein 1 and S6 protein.
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PMID:Dependence on phosphoinositide 3-kinase and RAS-RAF pathways drive the activity of RAF265, a novel RAF/VEGFR2 inhibitor, and RAD001 (Everolimus) in combination. 2012 52

Hypoxia-inducible factor (HIF) plays an important role in renal tumourigenesis. In the majority of clear cell RCC (ccRCC), the most frequent and highly vascularized RCC subtype, HIF is constitutively activated by inactivation of the von Hippel-Lindau gene. Of the HIF subunits, HIF-2alpha appears to be more oncogenic than HIF-1alpha, in that HIF-2alpha activates pro-tumourigenic target genes. In addition, recent studies indicate that HIF-1alpha, more than HIF-2alpha, can undergo proteasomal degradation in VHL - /- RCC cells. A more detailed understanding of the molecular basis of hypoxia and angiogenesis in renal carcinogenesis has set the stage for the development of targeted therapies, inhibiting multiple HIF-related pathways, such as the phosphatidylinositol 3-kinase-AKT-mTOR, RAS/RAF/MAP, and VEGF signalling routes. However, despite the positive results of these targeting agents in progression-free survival, clinical resistance remains an issue. Recent pre-clinical studies have suggested new targeting approaches such as inhibition of HIF-driven key metabolic enzymes and have introduced new HIF targeting agents, such as histone deacetylase inhibitors, with successful anti-neoplastic effects. In this review, we discuss existing and novel findings about RCC carcinogenesis, with subsequent clinical implications.
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PMID:VHL and HIF signalling in renal cell carcinogenesis. 2022 41

SPARC (secreted protein acidic and rich in cysteine) is expressed in all grades of astrocytoma, including glioblastoma (GBM). SPARC suppresses glioma growth but promotes migration and invasion by mediating integrin and growth factor receptor-regulated kinases and their downstream effectors. PTEN (phosphatase and tensin homolog deleted on chromosome 10), which is commonly lost in primary GBMs, negatively regulates proliferation and migration by inhibiting some of the same SPARC-mediated signaling pathways. This study determined whether PTEN reconstitution in PTEN-mutant, SPARC-expressing U87MG cells could further suppress proliferation and tumor growth but inhibit migration and invasion in SPARC-expressing cells in vitro and in vivo, and thereby prolong survival in animals with xenograft tumors. In vitro, PTEN reduced proliferation and migration in both SPARC-expressing and control cells, with a greater suppression in SPARC-expressing cells. PTEN reconstitution suppressed AKT activation in SPARC-expressing and control cells but suppressed the SHC-RAF-ERK signaling pathway only in SPARC-expressing cells. Importantly, coexpression of SPARC and PTEN resulted in the smallest, least proliferative tumors with reduced invasive capacity and longer animal survival. Furthermore, direct inhibition of the AKT and SHC-RAF-ERK signaling pathways suppressed the proliferation and migration of SPARC-expressing cells in vitro. These findings demonstrate that PTEN reconstitution or inhibition of signaling pathways that are activated by the loss of PTEN provide potential therapeutic strategies to inhibit SPARC-induced invasion while enhancing the negative effect of SPARC on tumor growth.
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PMID:PTEN augments SPARC suppression of proliferation and inhibits SPARC-induced migration by suppressing SHC-RAF-ERK and AKT signaling. 2047 16

Proteomic approaches have been useful for the identification of aberrantly expressed proteins in complex diseases such as cancer. These proteins are not only potential disease biomarkers, but also targets for therapy. The aim of this study was to identify differentially expressed proteins in diffuse astrocytoma grade II, anaplastic astrocytoma grade III and glioblastoma multiforme grade IV in human tumor samples and in non-neoplastic brain tissue as control using 2-DE and MS. Tumor and control brain tissue dissection was guided by histological hematoxylin/eosin tissue sections to provide more than 90% of tumor cells and astrocytes. Six proteins were detected as up-regulated in higher grade astrocytomas and the most important finding was nucleophosmin (NPM) (p<0.05), whereas four proteins were down-regulated, among them raf kinase inhibitor protein (RKIP) (p<0.05). We report here for the first time the alteration of NPM and RKIP expression in brain cancer. Our focus on these proteins was due to the fact that they are involved in the PI3K/AKT/mTOR and RAS/RAF/MAPK pathways, known for their contribution to the development and progression of gliomas. The proteomic data for NPM and RKIP were confirmed by Western blot, quantitative real-time PCR and immunohistochemistry. Due to the participation of NPM and RKIP in uncontrolled proliferation and evasion of apoptosis, these proteins are likely targets for drug development.
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PMID:Proteomic analysis of low- to high-grade astrocytomas reveals an alteration of the expression level of raf kinase inhibitor protein and nucleophosmin. 2053 35

Treatment outcomes in advanced or metastatic non-small-cell lung cancer (NSCLC) remain unsatisfactory, with low long-term survival rates. Palliative chemotherapy offers a median survival not exceeding 1 year. To date, various combinations of cytotoxic drugs have not improved treatment results beyond what has been observed with platinum doublets. By contrast, molecular targeted drugs may block important pathways that drive cancer progression and achieve long-term disease control. Conflicting results have demonstrated marginal benefit with EGFR inhibitors, anti-EGFR monoclonal antibodies and antiangiogenic strategies in unselected populations of patients with advanced NSCLC. However, patients with an EGFR mutation are likely to respond to agents that target this gene. Novel targeted therapies that interfere with insulin-like growth factor 1 receptor, or the EML4-ALK fusion protein have shown promising activity. Aberrations in other key signaling pathways and molecules, such as RAS/RAF/MEK, PI3K/AKT/mTOR, or MET kinase, have been identified as crucial targets, especially in resistant patients. Novel drugs aimed at these abnormalities are already in the clinic. This Review outlines the current state-of-the-art research for targeted therapy in NSCLC.
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PMID:Targeted therapy in non-small-cell lung cancer--is it becoming a reality? 2055 45


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