Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent evidence suggests tumor-initating cells (TICs), also called cancer stem cells, are responsible for tumor initiation and progression; therefore, they represent an important cell population for development of future anti-cancer therapies. In this study, we show that the sesquiterpene lactone parthenolide (PTL) is cytotoxic to prostate TICs isolated from prostate cancer cell lines: DU145, PC3, VCAP, and LAPC4, as well as primary prostate TICs. Furthermore, PTL inhibited TIC-driven tumor formation in mouse xenografts. Using an integrated molecular profiling approach encompassing proteomics, profiles of activated transcription factors and genomics we ascertained the effects of PTL on prostate cancer cells. In addition to the previously described effects of PTL, we determined that the non-receptor tyrosine kinase src, and many src signaling components, including: Csk, FAK, beta1-arrestin, FGFR2, PKC, MEK/MAPK, CaMK, ELK-1, and ELK-1-dependent genes are novel targets of PTL action. Furthermore, PTL altered the binding of transcription factors important in prostate cancer including: C/EBP-alpha, fos related antigen-1 (FRA-1), HOXA-4, c-MYB, SNAIL, SP1, serum response factor (SRF), STAT3, X-box binding protein-1 (XBP1), and p53. In summary, we show PTL is cytotoxic to prostate TICs and describe the molecular events of PTL-mediated cytotoxicity. Therefore, PTL represents a promising therapeutic for prostate cancer treatment.
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PMID:Effects of the sesquiterpene lactone parthenolide on prostate tumor-initiating cells: An integrated molecular profiling approach. 1920 13

Members of the protein kinase C (PKC) family have long been studied for their contributions to oncogenesis. Among the ten different isoforms of this family of serine/threonine kinases, protein kinase C epsilon (PKC epsilon) is one of the best understood for its role as a transforming oncogene. In vitro, overexpression of PKC epsilon has been demonstrated to increase proliferation, motility, and invasion of fibroblasts or immortalized epithelial cells. In addition, xenograft and transgenic animal models have clearly shown that overexpression of PKC epsilon is tumorigenic resulting in metastatic disease. Perhaps most important in implicating the epsilon isoform in oncogenesis, PKC epsilon has been found to be overexpressed in tumor-derived cell lines and histopathological tumor specimens from various organ sites. Combined, this body of work provides substantial evidence implicating PKC epsilon as a transforming oncogene that plays a crucial role in establishing an aggressive metastatic phenotype. Reviewed here is the literature that has led to the current understanding of PKC epsilon as an oncogene. Moreover, this review focuses on the PKC epsilon-mediated signaling network for cell motility and explores the interaction of PKC epsilon with three major PKC epsilon signaling nodes: RhoA/C, STAT3 and Akt. Lastly, the emerging role of PKC epsilon as a tumor biomarker is discussed.
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PMID:Protein kinase C epsilon: an oncogene and emerging tumor biomarker. 1922 72

WNT5A is a cancer-associated gene involved in invasion and metastasis of melanoma, breast cancer, pancreatic cancer, and gastric cancer. WNT5A transduces signals through Frizzled, ROR1, ROR2 or RYK receptors to beta-catenin-TCF/LEF, DVL-RhoA-ROCK, DVL-RhoB-Rab4, DVL-Rac-JNK, DVL-aPKC, Calcineurin-NFAT, MAP3K7-NLK, MAP3K7-NF-kappaB, and DAG-PKC signaling cascades in a context-dependent manner. SNAI1 (Snail), CD44, G3BP2, and YAP1 are WNT5A target genes. We and other groups previously reported that IL6- or LIF-induced signaling through JAK-STAT3 signaling cascade is involved in WNT5A upregulation (STAT3-WNT5A signaling loop). Here, refined integrative genomic analyses of WNT5A were carried out to elucidate other mechanisms of WNT5A transcription. The WNT5A gene was found to encode two isoforms by using alternative first exons 1A and 1B. Quadruple Smad-binding elements (SBEs), single Sp1-binding site (GC-box), PPARgamma-binding site, C/EBP-binding site and bHLH-binding site within the promoter A region, 5'-adjacent to exon 1A, were conserved in human WNT5A, chimpanzee WNT5A, mouse Wnt5a, and rat Wnt5a. NF-kappaB-binding site, CUX1-binding site, double SBEs and double GC-boxes within the promoter B region, 5'-adjacent to exon 1B, were conserved in mammalian WNT5A orthologs. Quadruple FOX-binding sites and double SBEs within ultra-conserved intron 1 were also conserved in mammalian WNT5A orthologs. Conserved NF-kappaB-binding site within the WNT5A promoter B region elucidated the mechanisms that TNFalpha and toll-like receptor (TLR) signals upregulate WNT5A via MAP3K7. Quadruple FOX-binding sites rather than GLI-binding site revealed that Hedgehog signals induce WNT5A upregulation indirectly via FOX family members, such as FOXA2, FOXC2, FOXE1, FOXF1 and FOXL1. TGFbeta signals were found to upregulate WNT5A expression directly through the Smad complex, and also indirectly through Smad-induced CUX1 and MAP3K7-mediated NF-kappaB. Together these facts indicate that WNT5A is transcribed based on multiple mechanisms, such as NF-kappaB, Hedgehog, TGFbeta, and Notch signaling cascades.
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PMID:Transcriptional mechanisms of WNT5A based on NF-kappaB, Hedgehog, TGFbeta, and Notch signaling cascades. 1942 2

Hepatocyte growth factor/scatter factor (HGF/SF) receptor c-Met is implicated in growth, invasion and metastasis of many tumors. Tumor cells harboring MET gene amplification are initially sensitive to c-Met tyrosine kinase inhibitors (TKI), but escape from long-term treatment has not been investigated. C-Met is a client of heat shock protein 90 (Hsp90) and is destabilized by Hsp90 inhibitors, suggesting that these drugs may inhibit tumors driven by MET amplification, although tumor escape under these conditions also has not been explored. Here, we evaluated the initial inhibitory effects of, and the likelihood of escape from, the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) and the c-Met TKI SU11274, using two cell lines harboring MET gene amplification. 17-AAG inhibited cell growth in both cell lines and induced substantial apoptosis, whereas SU11274 was only growth inhibitory in one cell line. In both cell lines, c-Met-dependent Akt, Erk and/or STAT3 signaling, as well as activation of the EGFR family, resumed shortly after treatment with c-Met TKI despite sustained c-Met inhibition. PKC delta upregulation may participate in reactivation of c-Met downstream signaling in both cell lines. In contrast to c-Met TKI, 17-AAG destabilized c-Met protein and durably blocked reactivation of downstream signaling pathways and EGFR family members. Our data demonstrate that downstream signaling in tumor cells overexpressing c-Met is not stably suppressed by c-Met TKI, even though c-Met remains fully inhibited. In contrast, Hsp90 inhibitors provide long-lasting suppression of c-Met-dependent signaling, and these drugs should be further evaluated in tumors driven by MET gene amplification.
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PMID:Cancer cells harboring MET gene amplification activate alternative signaling pathways to escape MET inhibition but remain sensitive to Hsp90 inhibitors. 1971 82

Here we demonstrate that elevation of cyclic AMP (cAMP) levels in human umbilical vein endothelial cells (HUVECs) specifically attenuates ERK1,2 activation in response to either leptin or a soluble interleukin IL-6 receptor-alpha/IL-6 (sIL-6R alpha/IL-6) trans-signalling complex but not protein kinase C activator phorbol 12-myristate 13-acetate. The inhibitory effects of cAMP on sIL-6R alpha/IL-6-stimulated phosphorylation of ERK1,2 and STAT3 were abolished by either short interfering (si) RNA-mediated knockdown or genetic ablation of suppressor of cytokine signalling-3 (SOCS-3). The inhibitory effect of cAMP could not be reversed by inhibition of cAMP-dependent protein kinase (PKA) but was blocked by depletion of the alternative intracellular cAMP sensor exchange protein activated by cAMP 1 (Epac1), which is also required to observe SOCS-3 accumulation in response to cAMP. Interestingly, the ability of cAMP elevation to inhibit IL-6 signalling was blocked by ERK inhibition. Consistent with this observation, cAMP elevation in HUVECs produced a transient yet robust activation of ERK, and subsequent phosphorylation of transcription factor C/EBP beta, both of which were resistant to PKA inhibition. However, siRNA depletion and immunoblotting experiments revealed that neither Epac1 nor Epac2 contributed to the PKA-independent activation of ERK1,2 observed following cAMP elevation. Together, these observations suggest that while SOCS-3 induction and subsequent inhibition of cytokine-mediated phosphorylation of ERK1,2 and STAT3 in response to cAMP require Epac1 and a transient PKA-independent activation of the ERK pathway, these two events are controlled by distinct mechanisms. In addition, it reveals a novel Epac-dependent mechanism by which cAMP can specifically inhibit ERK in response to cytokine receptor activation.
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PMID:Selective inhibition of cytokine-activated extracellular signal-regulated kinase by cyclic AMP via Epac1-dependent induction of suppressor of cytokine signalling-3. 1963 20

The Akt pathway is frequently hyperactivated in human cancer and functions as a cardinal nodal point for transducing extracellular and intracellular oncogenic signals and, thus, presents an exciting target for molecular therapeutics. Here we report the identification of a small molecule Akt/protein kinase B inhibitor, API-1. Although API-1 is neither an ATP competitor nor substrate mimetic, it binds to pleckstrin homology domain of Akt and blocks Akt membrane translocation. Furthermore, API-1 treatment of cancer cells results in inhibition of the kinase activities and phosphorylation levels of the three members of the Akt family. In contrast, API-1 had no effects on the activities of the upstream Akt activators, phosphatidylinositol 3-kinase, phosphatidylinositol-dependent kinase-1, and mTORC2. Notably, the kinase activity and phosphorylation (e.g. Thr(P)(308) and Ser(P)(473)) levels of constitutively active Akt, including a naturally occurring mutant AKT1-E17K, were inhibited by API-1. API-1 is selective for Akt and does not inhibit the activation of protein kinase C, serum and glucocorticoid-inducible kinase, protein kinase A, STAT3, ERK1/2, or JNK. The inhibition of Akt by API-1 resulted in induction of cell growth arrest and apoptosis selectively in human cancer cells that harbor constitutively activated Akt. Furthermore, API-1 inhibited tumor growth in nude mice of human cancer cells in which Akt is elevated but not of those cancer cells in which it is not. These data indicate that API-1 directly inhibits Akt through binding to the Akt pleckstrin homology domain and blocking Akt membrane translocation and that API-1 has anti-tumor activity in vitro and in vivo and could be a potential anti-cancer agent for patients whose tumors express hyperactivated Akt.
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PMID:A small molecule inhibits Akt through direct binding to Akt and preventing Akt membrane translocation. 2782 94

Under hypoxia, mouse embryonic stem cells (mESCs) lose their self-renewal activity and display an early differentiated morphology mediated by the hypoxia-inducible factor-1 alpha (HIF-1 alpha). Previous studies have demonstrated that PKC-delta is activated by hypoxia and increases the protein stability and transcriptional activity of HIF-1 alpha in human cancer cells. Furthermore, activation of PKC-delta mediates cardiac differentiation of ESCs and hematopoietic stem cells. However, the role of PKC-delta in hypoxia-induced early differentiation of mESCs remains largely unknown. Here, we show the inhibition of PKC-delta activity prevents the early differentiation of mESCs under hypoxia using PKC-delta inhibitors, GF 109203X and rottlerin. Reduction of PKC-delta activity under hypoxia effectively decreased HIF-1 alpha protein levels and substantially recovered the expression of LIF-specific receptor (LIFR) and phosphorylated-STAT3 in mESCs. Furthermore, PKC-delta inhibitors aid to sustain the expression of self-renewal markers and suppress the expression of early differentiation markers in mESCs under hypoxia. Taken together, these results suggest that PKC-delta inhibitors block the early differentiation of mESCs via destabilization of HIF-1 alpha under hypoxia.
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PMID:PKC-delta inhibitors sustain self-renewal of mouse embryonic stem cells under hypoxia in vitro. 2017 47

The molecular signals governing retinal development remain poorly understood, but some key molecules that play important roles have been identified. Activation of STAT3 by cytokines such as LIF and CNTF specifically blocks differentiation of rod photoreceptors. Here we test the hypothesis that PKC activation promotes development of rod photoreceptors by inhibiting STAT3. Explant cultures of mouse retina were used to study the effects of PKC activation on rod development. The expression of opsin, a rod specific marker, is induced at an early stage in retina explants cultured in the presence of PMA and this effect is prevented by the PKC inhibitor Go7874. Histological experiments show that there is expression of PKC beta1, but not PKC-alpha in the outer nuclear layer between E17.5 and PN5. In vitro data derived from cell lines shows that activation of PKC results in reduction of STAT3 phosphorylation. In addition, inhibition of PKC results in increase STAT3 phosphorylation. We suggest that cross talk of signals between STAT3 and PKC may determine the differentiation of rods from retinal progeitors.
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PMID:Protein kinase C regulates rod photoreceptor differentiation through modulation of STAT3 signaling. 2023 98

The protein kinase C (PKC) signaling pathway is a major regulator of cellular functions and is implicated in pathologies involving extracellular matrix remodeling. Inflammatory joint disease is characterized by excessive extracellular matrix catabolism, and here we assess the role of PKC in the induction of the collagenases, matrix metalloproteinase (MMP)-1 and MMP-13, in human chondrocytes by the potent cytokine stimulus interleukin-1 (IL-1) in combination with oncostatin M (OSM). IL-1 + OSM-stimulated collagenolysis and gelatinase activity were ameliorated by pharmacological PKC inhibition in bovine cartilage, as was collagenase gene induction in human chondrocytes. Small interfering RNA-mediated silencing of PKC gene expression showed that both novel (nPKC delta, nPKC eta) and atypical (aPKC zeta, aPKC iota) isoforms were involved in collagenase induction by IL-1. However, MMP1 and MMP13 induction by IL-1 + OSM was inhibited only by aPKC silencing, suggesting that only atypical isoforms play a significant role in complex inflammatory milieus. Silencing of either aPKC led to diminished IL-1 + OSM-dependent extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription (STAT) 3 phosphorylation, and c-fos expression. STAT3 gene silencing or ERK pathway inhibition also resulted in loss of IL-1 + OSM-stimulated c-fos and collagenase expression. Silencing of c-fos and c-jun expression was sufficient to abrogate IL-1 + OSM-stimulated collagenase gene induction, and overexpression of both c-fos and c-jun was sufficient to drive transcription from the MMP1 promoter in the absence of a stimulus. Our data identify atypical PKC isozymes as STAT and ERK activators that mediate c-fos and collagenase expression during IL-1 + OSM synergy in human chondrocytes. aPKCs may constitute potential therapeutic targets for inflammatory joint diseases involving increased collagenase expression.
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PMID:Protein kinase C isoforms zeta and iota mediate collagenase expression and cartilage destruction via STAT3- and ERK-dependent c-fos induction. 2046 8

Translocator protein (TSPO) is an 18 kDa high affinity cholesterol- and drug-binding protein found primarily in the outer mitochondrial membrane. Although TSPO is found in many tissue types, it is expressed at the highest levels under normal conditions in tissues that synthesize steroids. TSPO has been associated with cholesterol import into mitochondria, a key function in steroidogenesis, and directly or indirectly with multiple other cellular functions including apoptosis, cell proliferation, differentiation, anion transport, porphyrin transport, heme synthesis, and regulation of mitochondrial function. Aberrant expression of TSPO has been linked to multiple diseases, including cancer, brain injury, neurodegeneration, and ischemia-reperfusion injury. There has been an effort during the last decade to understand the mechanisms regulating tissue- and disease-specific TSPO expression and to identify pharmacological means to control its expression. This review focuses on the current knowledge regarding the chemicals, hormones, and molecular mechanisms regulating Tspo gene expression under physiological conditions in a tissue- and disease-specific manner. The results described here provide evidence that the PKCepsilon-ERK1/2-AP-1/STAT3 signal transduction pathway is the primary regulator of Tspo gene expression in normal and pathological tissues expressing high levels of TSPO.
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PMID:Regulation of translocator protein 18 kDa (TSPO) expression in health and disease states. 2060 May 83


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