Signal Transduction
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"The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway." (Source: MeSH)

An overview of major signal transduction pathways
Figure: An overview of major signal transduction pathways
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Latest Research Publications

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Latest Research Publications

This list of publications is regularly updated (Source: PubMed).

Parker BC, Engels M, Annala M, Zhang W
Emergence of FGFR family gene fusions as therapeutic targets in a wide spectrum of solid tumours.
J Pathol. 2014; 232(1):4-15 [PubMed] Related Publications
The emergence of fibroblast growth factor receptor (FGFR) family fusions across diverse cancers has brought attention to FGFR-derived cancer therapies. The discovery of the first recurrent FGFR fusion in glioblastoma was followed by discoveries of FGFR fusions in bladder, lung, breast, thyroid, oral, and prostate cancers. Drug targeting of FGFR fusions has shown promising results and should soon be translating into clinical trials. FGFR fusions form as a result of various mechanisms – predominantly deletion for FGFR1, translocation for FGFR2, and tandem duplication for FGFR3. The ability to exploit the unique targetability of FGFR fusions proves that FGFR-derived therapies could have a promising future in cancer therapeutics. Drug targeting of fusion genes has proven to be an extremely effective therapeutic approach for cancers such as the recurrent BCR–ABL1 fusion in chronic myeloid leukaemia. The recent discovery of recurrent FGFR family fusions in several cancer types has brought to attention the unique therapeutic potential for FGFR-positive patients. Understanding the diverse mechanisms of FGFR fusion formation and their oncogenic potential will shed light on the impact of FGFR-derived therapy in the future.

Related: Cancer Prevention and Risk Reduction FGFR1 gene FGFR2 gene

Parker M, Mohankumar KM, Punchihewa C, et al.
C11orf95-RELA fusions drive oncogenic NF-κB signalling in ependymoma.
Nature. 2014; 506(7489):451-5 [PubMed] Related Publications
Members of the nuclear factor-κB (NF-κB) family of transcriptional regulators are central mediators of the cellular inflammatory response. Although constitutive NF-κB signalling is present in most human tumours, mutations in pathway members are rare, complicating efforts to understand and block aberrant NF-κB activity in cancer. Here we show that more than two-thirds of supratentorial ependymomas contain oncogenic fusions between RELA, the principal effector of canonical NF-κB signalling, and an uncharacterized gene, C11orf95. In each case, C11orf95-RELA fusions resulted from chromothripsis involving chromosome 11q13.1. C11orf95-RELA fusion proteins translocated spontaneously to the nucleus to activate NF-κB target genes, and rapidly transformed neural stem cells--the cell of origin of ependymoma--to form these tumours in mice. Our data identify a highly recurrent genetic alteration of RELA in human cancer, and the C11orf95-RELA fusion protein as a potential therapeutic target in supratentorial ependymoma.

Related: Chromosome 11

Kirkegaard T, Hansen SK, Larsen SL, et al.
T47D breast cancer cells switch from ER/HER to HER/c-Src signaling upon acquiring resistance to the antiestrogen fulvestrant.
Cancer Lett. 2014; 344(1):90-100 [PubMed] Related Publications
In this study, T47D cell lines resistant to the antiestrogen fulvestrant were established and analyzed to explore, whether a switch to HER signaling, as seen in fulvestrant resistant MCF-7 cell lines, is a general resistance mechanism. We find that parental T47D cells depend on ER and HER signaling for growth. Fulvestrant resistant T47D cells have lost ER expression and, although HER2 was over expressed, growth was only partially driven by HER receptors. Instead c-Src was important for resistant growth. Thus, the T47D and MCF-7 model system unravel different resistance mechanisms which may be important for fulvestrant resistant breast cancer patients.

Related: Breast Cancer

Principe DR, Doll JA, Bauer J, et al.
TGF-β: duality of function between tumor prevention and carcinogenesis.
J Natl Cancer Inst. 2014; 106(2):djt369 [PubMed] Article available free on PMC after 01/02/2015 Related Publications
Several mechanisms underlying tumor progression have remained elusive, particularly in relation to transforming growth factor beta (TGF-β). Although TGF-β initially inhibits epithelial growth, it appears to promote the progression of advanced tumors. Defects in normal TGF-β pathways partially explain this paradox, which can lead to a cascade of downstream events that drive multiple oncogenic pathways, manifesting as several key features of tumorigenesis (uncontrolled proliferation, loss of apoptosis, epithelial-to-mesenchymal transition, sustained angiogenesis, evasion of immune surveillance, and metastasis). Understanding the mechanisms of TGF-β dysregulation will likely reveal novel points of convergence between TGF-β and other pathways that can be specifically targeted for therapy.

Related: Apoptosis Cancer Prevention and Risk Reduction Angiogenesis and Cancer TGFBR1

Li S, Mattar P, Dixit R, et al.
RAS/ERK signaling controls proneural genetic programs in cortical development and gliomagenesis.
J Neurosci. 2014; 34(6):2169-90 [PubMed] Related Publications
Neural cell fate specification is well understood in the embryonic cerebral cortex, where the proneural genes Neurog2 and Ascl1 are key cell fate determinants. What is less well understood is how cellular diversity is generated in brain tumors. Gliomas and glioneuronal tumors, which are often localized in the cerebrum, are both characterized by a neoplastic glial component, but glioneuronal tumors also have an intermixed neuronal component. A core abnormality in both tumor groups is overactive RAS/ERK signaling, a pro-proliferative signal whose contributions to cell differentiation in oncogenesis are largely unexplored. We found that RAS/ERK activation levels differ in two distinct human tumors associated with constitutively active BRAF. Pilocytic astrocytomas, which contain abnormal glial cells, have higher ERK activation levels than gangliogliomas, which contain abnormal neuronal and glial cells. Using in vivo gain of function and loss of function in the mouse embryonic neocortex, we found that RAS/ERK signals control a proneural genetic switch, inhibiting Neurog2 expression while inducing Ascl1, a competing lineage determinant. Furthermore, we found that RAS/ERK levels control Ascl1's fate specification properties in murine cortical progenitors--at higher RAS/ERK levels, Ascl1(+) progenitors are biased toward proliferative glial programs, initiating astrocytomas, while at moderate RAS/ERK levels, Ascl1 promotes GABAergic neuronal and less glial differentiation, generating glioneuronal tumors. Mechanistically, Ascl1 is phosphorylated by ERK, and ERK phosphoacceptor sites are necessary for Ascl1's GABAergic neuronal and gliogenic potential. RAS/ERK signaling thus acts as a rheostat to influence neural cell fate selection in both normal cortical development and gliomagenesis, controlling Neurog2-Ascl1 expression and Ascl1 function.

Akahane K, Hirokawa K
Strategy of Daiichi Sankyo discovery research in oncology.
Jpn J Clin Oncol. 2014; 44(2):109-15 [PubMed] Related Publications
We would like to introduce Daiichi Sankyo's approach to developing cancer targeted medicines with special reference to the drug discovery strategy, global discovery activities and external research collaboration leading to generation of innovative drugs for cancer patients. We are developing 14 clinical projects for cancer treatment and three of them have been previously approved. These are mostly targeted for growth and survival signals of cancer cells. To overcome the drug resistance mechanism derived from the heterogeneous nature of cancer, we are developing selective inhibitors in three major clusters of signal pathways which may allow future rational combinations of oncology products. In addition to the main research facility in Japan, research sites in the EU and the USA provide us with different technical expertise and diversified ideas of drug discovery. To access novel drug targets, we are facilitating research collaboration with leading academia and successful cancer research scientists. In conclusion, we intend to focus more on developing innovative personalized medicines for better treatment of cancer.

Related: Cancer Prevention and Risk Reduction USA

Deschênes-Simard X, Kottakis F, Meloche S, Ferbeyre G
ERKs in cancer: friends or foes?
Cancer Res. 2014; 74(2):412-9 [PubMed] Related Publications
The extracellular signal-regulated kinase ERK1 and ERK2 (ERK1/2) cascade regulates a variety of cellular processes by phosphorylating multiple target proteins. The outcome of its activation ranges from stimulation of cell survival and proliferation to triggering tumor suppressor responses such as cell differentiation, cell senescence, and apoptosis. This pathway is intimately linked to cancer as several of its upstream activators are frequently mutated in human disease and are shown to accelerate tumorigenesis when engineered in the mouse genome. However, measurement of activated ERKs in human cancers or mouse models does not always support a role in tumorigenesis, and data consistent with a role in tumor suppression have been reported as well. The intensity of ERK signaling, negative feedback loops that regulate the pathway, and cross-talks with other signaling pathways, seem to be of primary importance in determining the final cellular outcome. Cell senescence, a putative tumor-suppression mechanism, depends on high-intensity ERK signals that trigger phosphorylation-dependent protein degradation of multiple proteins required for cell-cycle progression. This response may be circumvented during carcinogenesis by a variety of mechanisms, some of them yet to be discovered, which in essence turn ERK functions from tumor suppression to tumor promotion. The use of pharmacologic inhibitors targeting this pathway must be carefully evaluated so they are applied to cases in which ERKs are mainly oncogenic.

Related: Apoptosis Cancer Prevention and Risk Reduction

Siegelin MD, Borczuk AC
Epidermal growth factor receptor mutations in lung adenocarcinoma.
Lab Invest. 2014; 94(2):129-37 [PubMed] Related Publications
Despite tremendous progress in the last decade, lung adenocarcinoma still represents a tumor with unfavorable prognosis when detected at advanced clinical stage. High-stage tumors are not amenable to surgical resection, and therefore systemic therapies are needed to control these tumors to prolong patient survival. In the era of molecular and personalized therapeutics, the discovery of mutations in epidermal growth factor receptor (EGFR) in 15-20% of lung adenocarcinomas and the associated response to EGFR-targeting tyrosine kinase (TK) inhibitors have provided a successful avenue of attack in high-stage adenocarcinomas. In this review, we will provide an overview of the EGFR pathway, review the significant somatic EGFR alterations in lung adenocarcinoma and highlight their implications for treatment. In addition, we will examine pathways by which tumors resist EGFR TK therapy, both as primary nonresponders and by acquired resistance. In doing so, we will examine other oncogenic pathways whose status in tumor samples may impact therapeutic responses despite presence of activating EGFR mutations.

Related: Lung Cancer Gefitinib (Iressa)

Rafiei S, Komarova SV
Molecular signaling pathways mediating osteoclastogenesis induced by prostate cancer cells.
BMC Cancer. 2013; 13:605 [PubMed] Article available free on PMC after 01/02/2015 Related Publications
BACKGROUND: Advanced prostate cancer commonly metastasizes to bone leading to osteoblastic and osteolytic lesions. Although an osteolytic component governed by activation of bone resorbing osteoclasts is prominent in prostate cancer metastasis, the molecular mechanisms of prostate cancer-induced osteoclastogenesis are not well-understood.
METHODS: We studied the effect of soluble mediators released from human prostate carcinoma cells on osteoclast formation from mouse bone marrow and RAW 264.7 monocytes.
RESULTS: Soluble factors released from human prostate carcinoma cells significantly increased viability of naïve bone marrow monocytes, as well as osteoclastogenesis from precursors primed with receptor activator of nuclear factor κ-B ligand (RANKL). The prostate cancer-induced osteoclastogenesis was not mediated by RANKL as it was not inhibited by osteoprotegerin (OPG). However inhibition of TGFβ receptor I (TβRI), or macrophage-colony stimulating factor (MCSF) resulted in attenuation of prostate cancer-induced osteoclastogenesis. We characterized the signaling pathways induced in osteoclast precursors by soluble mediators released from human prostate carcinoma cells. Prostate cancer factors increased basal calcium levels and calcium fluctuations, induced nuclear localization of nuclear factor of activated t-cells (NFAT)c1, and activated prolonged phosphorylation of ERK1/2 in RANKL-primed osteoclast precursors. Inhibition of calcium signaling, NFATc1 activation, and ERK1/2 phosphorylation significantly reduced the ability of prostate cancer mediators to stimulate osteoclastogenesis.
CONCLUSIONS: This study reveals the molecular mechanisms underlying the direct osteoclastogenic effect of prostate cancer derived factors, which may be beneficial in developing novel osteoclast-targeting therapeutic approaches.

Related: Prostate Cancer NFATC1

Rahal R, Frick M, Romero R, et al.
Pharmacological and genomic profiling identifies NF-κB-targeted treatment strategies for mantle cell lymphoma.
Nat Med. 2014; 20(1):87-92 [PubMed] Related Publications
Mantle cell lymphoma (MCL) is an aggressive malignancy that is characterized by poor prognosis. Large-scale pharmacological profiling across more than 100 hematological cell line models identified a subset of MCL cell lines that are highly sensitive to the B cell receptor (BCR) signaling inhibitors ibrutinib and sotrastaurin. Sensitive MCL models exhibited chronic activation of the BCR-driven classical nuclear factor-κB (NF-κB) pathway, whereas insensitive cell lines displayed activation of the alternative NF-κB pathway. Transcriptome sequencing revealed genetic lesions in alternative NF-κB pathway signaling components in ibrutinib-insensitive cell lines, and sequencing of 165 samples from patients with MCL identified recurrent mutations in TRAF2 or BIRC3 in 15% of these individuals. Although they are associated with insensitivity to ibrutinib, lesions in the alternative NF-κB pathway conferred dependence on the protein kinase NIK (also called mitogen-activated protein 3 kinase 14 or MAP3K14) both in vitro and in vivo. Thus, NIK is a new therapeutic target for MCL treatment, particularly for lymphomas that are refractory to BCR pathway inhibitors. Our findings reveal a pattern of mutually exclusive activation of the BCR-NF-κB or NIK-NF-κB pathways in MCL and provide critical insights into patient stratification strategies for NF-κB pathway-targeted agents.

Related: Mantle Cell Lymphoma

Jin XT, Song L, Zhao JY, et al.
Dichlorodiphenyltrichloroethane exposure induces the growth of hepatocellular carcinoma via Wnt/β-catenin pathway.
Toxicol Lett. 2014; 225(1):158-66 [PubMed] Related Publications
Dichlorodiphenyltrichloroethane (DDT) is a persistent organic pollutant, involved in the progression of many cancers, including liver cancer. However, the underlying mechanism(s) of DDT, especially how low doses DDT cause liver cancer, is poorly understood. In this study, we evaluated the impact of p,p'-DDT on the growth of hepatocellular carcinoma using both in vitro and in vivo models. The present data indicated that the proliferation of HepG2 cells was strikingly promoted after exposed to p,p'-DDT for 4 days. In addition, reactive oxygen species (ROS) content was significantly elevated, accompanied with inhibitions of γ-glutamylcysteine synthetase (γ-GCS) and superoxide dismutase (SOD) activities. Interestingly, the levels of β-catenin and its downstream target genes (c-Myc and CyclinD1) were significantly up-regulated, and co-treatment of NAC, the ROS inhibitor, inhibited these over-expressed proteins. Moreover, the p,p'-DDT-stimulated proliferation of HepG2 cells could be reversed after NAC or β-catenin siRNA co-treatment. Likewise, p,p'-DDT treatment increased the growth of tumor in nude mice, stimulated oxidative stress and Wnt/β-catenin pathway. Our study indicates that low doses p,p'-DDT exposure promote the growth of hepatocellular carcinoma via Wnt/β-catenin pathway which is activated by oxidative stress. The finding suggests an association between low dose DDT exposure and liver cancer growth.

Related: Liver Cancer BCL1 Gene (CCND1)

Koval AV, Vlasov P, Shichkova P, et al.
Anti-leprosy drug clofazimine inhibits growth of triple-negative breast cancer cells via inhibition of canonical Wnt signaling.
Biochem Pharmacol. 2014; 87(4):571-8 [PubMed] Related Publications
Research on existing drugs often discovers novel mechanisms of their action and leads to the expansion of their therapeutic scope and subsequent remarketing. The Wnt signaling pathway is of the immediate therapeutic relevance, as it plays critical roles in cancer development and progression. However, drugs which disrupt this pathway are unavailable despite the high demand. Here we report an attempt to identify antagonists of the Wnt-FZD interaction among the library of the FDA-approved drugs. We performed an in silico screening which brought up several potential antagonists of the ligand-receptor interaction. 14 of these substances were tested using the TopFlash luciferase reporter assay and four of them identified as active and specific inhibitors of the Wnt3a-induced signaling. However, further analysis through GTP-binding and β-catenin stabilization assays showed that the compounds do not target the Wnt-FZD pair, but inhibit the signaling at downstream levels. We further describe the previously unknown inhibitory activity of an anti-leprosy drug clofazimine in the Wnt pathway and provide data demonstrating its efficiency in suppressing growth of Wnt-dependent triple-negative breast cancer cells. These data provide a basis for further investigations of the efficiency of clofazimine in treatment of Wnt-dependent cancers.

Voorham QJ, Janssen J, Tijssen M, et al.
Promoter methylation of Wnt-antagonists in polypoid and nonpolypoid colorectal adenomas.
BMC Cancer. 2013; 13:603 [PubMed] Article available free on PMC after 01/02/2015 Related Publications
BACKGROUND: Nonpolypoid adenomas are a subgroup of colorectal adenomas that have been associated with a more aggressive clinical behaviour compared to their polypoid counterparts. A substantial proportion of nonpolypoid and polypoid adenomas lack APC mutations, APC methylation or chromosomal loss of the APC locus on chromosome 5q, suggesting the involvement of other Wnt-pathway genes. The present study investigated promoter methylation of several Wnt-pathway antagonists in both nonpolypoid and polypoid adenomas.
METHODS: Quantitative methylation-specific PCR (qMSP) was used to evaluate methylation of four Wnt-antagonists, SFRP2, WIF-1, DKK3 and SOX17 in 18 normal colorectal mucosa samples, 9 colorectal cancer cell lines, 18 carcinomas, 44 nonpolypoid and 44 polypoid adenomas. Results were integrated with previously obtained data on APC mutation, methylation and chromosome 5q status from the same samples.
RESULTS: Increased methylation of all genes was found in the majority of cell lines, adenomas and carcinomas compared to normal controls. WIF-1 and DKK3 showed a significantly lower level of methylation in nonpolypoid compared to polypoid adenomas (p < 0.01). Combining both adenoma types, a positive trend between APC mutation and both WIF-1 and DKK3 methylation was observed (p < 0.05).
CONCLUSIONS: Methylation of Wnt-pathway antagonists represents an additional mechanism of constitutive Wnt-pathway activation in colorectal adenomas. Current results further substantiate the existence of partially alternative Wnt-pathway disruption mechanisms in nonpolypoid compared to polypoid adenomas, in line with previous observations.

Related: Colorectal (Bowel) Cancer

Pan J, Zhang Q, Xiong D, et al.
Transcriptomic analysis by RNA-seq reveals AP-1 pathway as key regulator that green tea may rely on to inhibit lung tumorigenesis.
Mol Carcinog. 2014; 53(1):19-29 [PubMed] Related Publications
Green tea is a promising chemopreventive agent for lung cancer. Multiple signaling events have been reported, however, the relative importance of these mechanisms in mediating the chemopreventive function of green tea is unclear. In the present study, to examine the involvement of AP-1 in green tea polyphenols induced tumor inhibition, human NSCLC cell line H1299 and mouse SPON 10 cells were identified as AP-1 dependent, as these two lines exhibit high constitutive AP-1 activity, and when TAM67 expression was induced with doxycycline, cell growth was inhibited and correlated with suppressed AP-1 activity. RNA-seq was used to determine the global transcriptional effects of AP-1 inhibition and also uncover the possible involvement of AP-1 in tea polyphenols induced chemoprevention. TAM67 mediated changes in gene expression were identified, and within down-regulated genes, AP-1 was identified as a key transcription regulator. RNA-seq analysis revealed that Polyphenon E-treated cells shared 293 commonly down-regulated genes within TAM67 expressing H1299 cells, and by analysis of limited Chip-seq data, over 10% of the down-regulated genes contain a direct AP-1 binding site, indicating that Polyphenon E elicits chemopreventive activity by regulating AP-1 target genes. Conditional TAM67 expressing transgenic mice and NSCLC cell lines were used to further confirm that the chemopreventive activity of green tea is AP-1 dependent. Polyphenon E lost its chempreventive function both in vitro and in vivo when AP-1 was inhibited, indicating that AP-1 inhibition is a major pathway through which green tea exhibits chemopreventive effects.

Related: Lung Cancer

Hahm ER, Karlsson AI, Bonner MY, et al.
Honokiol inhibits androgen receptor activity in prostate cancer cells.
Prostate. 2014; 74(4):408-20 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
BACKGROUND: We have shown previously that honokiol (HNK), a bioactive component of the medicinal plant Magnolia officinalis, inhibits growth of human prostate cancer cells in vitro and in vivo. However, the effect of HNK on androgen receptor (AR) signaling has not been studied.
METHODS: LNCaP, C4-2, and TRAMP-C1 cells were used for various assays. Trypan blue dye exclusion assay or clonogenic assay was performed for determination of cell viability. The effects of HNK and/or its analogs on protein levels of AR and its target gene product prostate specific antigen (PSA) were determined by western blotting. RNA interference of p53 was achieved by transient transfection. Reverse transcription-polymerase chain reaction was performed for mRNA expression of AR. Nuclear level of AR was visualized by microscopy. Apoptosis was quantified by DNA fragmentation assay or flow cytometry after Annexin V-propidium iodide staining.
RESULTS: HNK and its dichloroacetate analog (HDCA) were relatively more effective in suppressing cell viability and AR protein level than honokiol epoxide or biseugenol. Nuclear translocation of AR stimulated by a synthetic androgen (R1881) was markedly suppressed in the presence of HNK. Downregulation of AR protein resulting from HNK exposure was attributable to transcriptional repression as well as proteasomal degradation. HNK-mediated suppression of AR protein was maintained in LNCaP cells after knockdown of p53 protein. HNK-induced apoptosis was not affected by R1881 treatment.
CONCLUSIONS: The present study demonstrates, for the first time, that HNK inhibits activity of AR in prostate cancer cells regardless of the p53 status.

Related: Apoptosis Prostate Cancer

Johnson R, Halder G
The two faces of Hippo: targeting the Hippo pathway for regenerative medicine and cancer treatment.
Nat Rev Drug Discov. 2014; 13(1):63-79 [PubMed] Related Publications
The Hippo signalling pathway is an emerging growth control and tumour suppressor pathway that regulates cell proliferation and stem cell functions. Defects in Hippo signalling and hyperactivation of its downstream effectors Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) contribute to the development of cancer, which suggests that pharmacological inhibition of YAP and TAZ activity may be an effective anticancer strategy. Conversely, YAP and TAZ can also have beneficial roles in stimulating tissue repair and regeneration following injury, so their activation may be therapeutically useful in these contexts. A complex network of intracellular and extracellular signalling pathways that modulate YAP and TAZ activities have recently been identified. Here, we review the regulation of the Hippo signalling pathway, its functions in normal homeostasis and disease, and recent progress in the identification of small-molecule pathway modulators.

Related: Cancer Prevention and Risk Reduction

Wu D, Zhang Y, Huang J, et al.
Salinomycin inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cell in vitro and suppresses tumor growth in vivo.
Biochem Biophys Res Commun. 2014; 443(2):712-7 [PubMed] Related Publications
Salinomycin (Sal) is a polyether ionophore antibiotic that has recently been shown to induce cell death in various human cancer cells. However, whether salinomycin plays a functional role in nasopharyngeal carcinoma (NPC) has not been determined to date. The present study investigated the chemotherapeutic efficacy of salinomycin and its molecular mechanisms of action in NPC cells. Salinomycin efficiently inhibited proliferation and invasion of 3 NPC cell lines (CNE-1, CNE-2, and CNE-2/DDP) and activated a extensive apoptotic process that is accompanied by activation of caspase-3 and caspase-9, and decreased mitochondrial membrane potential. Meanwhile, the protein expression level of the Wnt coreceptor lipoprotein receptor related protein 6 (LRP6) and β-catenin was down-regulated, which showed that the Wnt/β-catenin signaling was involved in salinomycin-induced apoptosis of NPC cells. In a nude mouse NPC xenograft model, the anti-tumor effect of salinomycin was associated with the downregulation of β-catenin expression. The present study demonstrated that salinomycin can effectively inhibit proliferation and invasion, and induce apoptosis of NPC cells in vitro and inhibit tumor growth in vivo, probably via the inhibition of Wnt/β-catenin signaling, suggesting salinomycin as a potential candidate for the chemotherapy of NPC.

Related: Apoptosis Nasopharyngeal Cancer

Sui X, Kong N, Ye L, et al.
p38 and JNK MAPK pathways control the balance of apoptosis and autophagy in response to chemotherapeutic agents.
Cancer Lett. 2014; 344(2):174-9 [PubMed] Related Publications
The Mitogen Activated Protein Kinase (MAPK) signaling plays a critical role in the outcome and the sensitivity to anticancer therapies. Activated MAPK can transmit extracellular signals to regulate cell growth, proliferation, differentiation, migration, apoptosis and so on. Apoptosis as well as macroautophagy (hereafter referred to as autophagy) can be induced by extracellular stimuli such the treatment of chemotherapeutic agents, resulting in different cell response to these drugs. However, the molecular mechanisms mediating these two cellular processes remain largely unknown. Recently, several studies provide new insights into p38 and JNK MAPK pathways function in the control of the balance of autophagy and apoptosis in response to genotoxic stress. Our increased understanding of the role of p38 and JNK MAPK pathways in regulating the balance of autophagy and apoptosis will hopefully provide prospective strategies for cancer therapy.

Related: Apoptosis Cancer Prevention and Risk Reduction

Liu M, Wang F, Wen Z, et al.
Blockage of STAT3 signaling pathway with a decoy oligodeoxynucleotide inhibits growth of human ovarian cancer cells.
Cancer Invest. 2014; 32(1):8-12 [PubMed] Related Publications
Transcription factor decoy oligodeoxynucleotides (ODN) represent a novel tool for targeted inhibition of the STAT3 signaling pathway. To investigate its therapeutic potential in ovarian cancer, a double-stranded decoy ODN mimicking STAT3-specific cis-elements was transfected into two ovarian cancer cell lines OVCAR3 and SKOV3. The STAT3 decoy ODN treatment specifically blocked STAT3 signaling, and inhibited cell proliferation by inducing apoptosis and cell cycle arrest. These results suggest that targeted blockade of the STAT3 signaling pathway with a decoy ODN may represent a potential therapeutic approach in the treatment of ovarian cancer.

Related: Apoptosis Ovarian Cancer

Weng W, Wu Q, Yu Y, et al.
A novel chemotherapeutic arene ruthenium(II) drug Rawq01 altered the effect of microRNA-21 on PTEN/AKT signaling pathway in esophageal cancer cells.
Anticancer Res. 2013; 33(12):5407-14 [PubMed] Related Publications
AIM: Organometallic arene Ru(II) complexes have long been considered as most promising substitutes for cisplatinum as an anti-tumor drug, with low toxicity towards human normal cells and high selectivity to tumor cells. In this study, we synthesized a novel arene Ru(II) drug named Rawq01. We evaluated its activity in an in vitro model of esophageal cancer (ESCC) and further explored the cellular signaling pathways altered by Rawq01.
MATERIALS AND METHODS: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphe nyltetrazolium bromide (MTT) assay, colony forming assay and apoptosis assays were used to evaluate the antitumor activity of Rawq01. We treated ESCC cells with Rawq01 alone or combined with microRNA-21(miR-21) and LY294002 to explore whether Rawq01 altered the effect of miR-21 on PTEN/AKT signaling pathway in ESCC cell.
RESULTS: ESCC cells were sensitive to RAWQ01. We also found that Rawq01 up-regulated the expression of PTEN through mir-21 inhibition and therefore inhibited the PI3K-AKT pathway. Furthermore, when we combined Rawq01 treatment with miR-21 inhibitor or LY294002, the inhibitory effect of Rawq01 was significantly enhanced.
CONCLUSION: The effect of miR-21 on PTEN/AKT signaling pathway is abrogated by the novel arene Ru(II) drug Rawq01. Our data may be useful for the future development of a chemosensitizing strategies through manipulating microRNA expression for tumor treatment.

Related: Cancer of the Esophagus Esophageal Cancer PTEN AKT1 miR-21

Tomiyasu H, Watanabe M, Sugita K, et al.
Regulations of ABCB1 and ABCG2 expression through MAPK pathways in acute lymphoblastic leukemia cell lines.
Anticancer Res. 2013; 33(12):5317-23 [PubMed] Related Publications
BACKGROUND: One of the major causes of failure in chemotherapy for patients with acute lymphoblastic leukemia (ALL) is the acquisition of multidrug resistance (MDR). Predominant mechanisms for MDR acquisition include the overexpression of efflux pumps. In the present study, the regulation of the expression of two genes that encode efflux pumps, ATP-binding cassette, sub-family B, member 1 (ABCB1) and ABCG2, through mitogen-activated protein kinase (MAPK) pathways was examined.
MATERIALS AND METHODS: ABCB1 and ABCG2 mRNAs were quantified in a T-ALL cell line, CCRF-HSB-2 and a B-ALL cell line, YAMN90 using real-time RT-PCR. Changes in the mRNA amounts of these genes were examined after activation or inhibition of MAPK/extracellular signal-regulated kinase (ERK) pathway and c-Jun NH2-terminal kinase (JNK) pathway.
RESULTS: Activation of MAPK/ERK pathway up-regulated ABCB1 expression but down-regulated ABCG2 expression. Activation of JNK pathway up-regulated ABCG2 gene expression.
CONCLUSION: The expressions of ABCB1 and ABCG2 genes were regulated through MAPK/ERK and JNK pathways in the human ALL cell lines.

Related: Acute Lymphocytic Leukemia (ALL) ABCG2

Ma F, Zhang J, Zhong L, et al.
Upregulated microRNA-301a in breast cancer promotes tumor metastasis by targeting PTEN and activating Wnt/β-catenin signaling.
Gene. 2014; 535(2):191-7 [PubMed] Related Publications
MicroRNAs (miRNAs) are strongly implicated in many cancers, including breast cancer. Recently, microRNA-301a (miR-301a) has been proved to play a substantial role in gastric cancer, but its functions in the context of breast cancer remain unknown. Here we report that miR-301a was markedly upregulated in primary tumor samples from patients with distant metastases and pro-metastatic breast cancer cell lines. Gain-of-function and loss-of-function studies showed that ectopic overexpression of miR-301a promoted breast cancer cell migration, invasion and metastasis both in vitro and in vivo. Notably, Wnt/β-catenin signaling was hyperactivated in metastatic breast cancer cells that express miR-301a, and mediated miR-301a-induced invasion and metastasis. Furthermore, miR-301a directly targeted and suppressed PTEN, one negative regulator of the Wnt/β-catenin signaling cascade. These results demonstrate that miR-301a maintains constitutively activated Wnt/β-catenin signaling by directly targeting PTEN, which promotes breast cancer invasion and metastasis. Taken together, our findings reveal a new regulatory mechanism of miR-301a and suggest that miR-301a might be a potential target in breast cancer therapy.

Related: Breast Cancer PTEN

Stewart DJ
Wnt signaling pathway in non-small cell lung cancer.
J Natl Cancer Inst. 2014; 106(1):djt356 [PubMed] Related Publications
Wnt/β-catenin alterations are prominent in human malignancies. In non-small cell lung cancer (NSCLC), β-catenin and APC mutations are uncommon, but Wnt signaling is important in NSCLC cell lines, and Wnt inhibition reduces proliferation. Overexpression of Wnt-1, -2, -3, and -5a and of Wnt-pathway components Frizzled-8, Dishevelled, Porcupine, and TCF-4 is common in resected NSCLC and is associated with poor prognosis. Conversely, noncanonical Wnt-7a suppresses NSCLC development and is often downregulated. Although β-catenin is often expressed in NSCLCs, it was paradoxically associated with improved prognosis in some series, possibly because of E-cadherin interactions. Downregulation of Wnt inhibitors (eg, by hypermethylation) is common in NSCLC tumor cell lines and resected samples; may be associated with high stage, dedifferentiation, and poor prognosis; and has been reported for AXIN, sFRPs 1-5, WIF-1, Dkk-1, Dkk-3, HDPR1, RUNX3, APC, CDX2, DACT2, TMEM88, Chibby, NKD1, EMX2, ING4, and miR-487b. AXIN is also destabilized by tankyrases, and GSK3β may be inactivated through phosphorylation by EGFR. Preclinically, restoration of Wnt inhibitor function is associated with reduced Wnt signaling, decreased cell proliferation, and increased apoptosis. Wnt signaling may also augment resistance to cisplatin, docetaxel, and radiotherapy, and Wnt inhibitors may restore sensitivity. Overall, available data indicate that Wnt signaling substantially impacts NSCLC tumorigenesis, prognosis, and resistance to therapy, with loss of Wnt signaling inhibitors by promoter hypermethylation or other mechanisms appearing to be particularly important. Wnt pathway antagonists warrant exploration clinically in NSCLC. Agents blocking selected specific β-catenin interactions and approaches to increase expression of downregulated Wnt inhibitors may be of particular interest.

Related: Apoptosis Non-Small Cell Lung Cancer Lung Cancer

Suresh S, McCallum L, Crawford LJ, et al.
The matricellular protein CCN3 regulates NOTCH1 signalling in chronic myeloid leukaemia.
J Pathol. 2013; 231(3):378-87 [PubMed] Related Publications
Deregulated NOTCH1 has been reported in lymphoid leukaemia, although its role in chronic myeloid leukaemia (CML) is not well established. We previously reported BCR-ABL down-regulation of a novel haematopoietic regulator, CCN3, in CML; CCN3 is a non-canonical NOTCH1 ligand. This study characterizes the NOTCH1–CCN3 signalling axis in CML. In K562 cells, BCR-ABL silencing reduced full-length NOTCH1 (NOTCH1-FL) and inhibited the cleavage of NOTCH1 intracellular domain (NOTCH1-ICD), resulting in decreased expression of the NOTCH1 targets c-MYC and HES1. K562 cells stably overexpressing CCN3 (K562/CCN3) or treated with recombinant CCN3(rCCN3) showed a significant reduction in NOTCH1 signalling (> 50% reduction in NOTCH1-ICD, p < 0.05).Gamma secretase inhibitor (GSI), which blocks NOTCH1 signalling, reduced K562/CCN3 colony formation but increased that of K562/control cells. GSI combined with either rCCN3 or imatinib reduced K562 colony formation with enhanced reduction of NOTCH1 signalling observed with combination treatments. We demonstrate an oncogenic role for NOTCH1 in CML and suggest that BCR-ABL disruption of NOTCH1–CCN3 signalling contributes to the pathogenesis of CML.

Related: Chronic Myeloid Leukemia (CML) CML - Molecular Biology NOTCH1 gene Imatinib (Glivec)

Louria-Hayon I, Frelin C, Ruston J, et al.
Lnk adaptor suppresses radiation resistance and radiation-induced B-cell malignancies by inhibiting IL-11 signaling.
Proc Natl Acad Sci U S A. 2013; 110(51):20599-604 [PubMed] Article available free on PMC after 17/06/2014 Related Publications
The Lnk (Sh2b3) adaptor protein dampens the response of hematopoietic stem cells and progenitors (HSPCs) to a variety of cytokines by inhibiting JAK2 signaling. As a consequence, Lnk(-/-) mice develop hematopoietic hyperplasia, which progresses to a phenotype resembling the nonacute phase of myeloproliferative neoplasm. In addition, Lnk mutations have been identified in human myeloproliferative neoplasms and acute leukemia. We find that Lnk suppresses the development of radiation-induced acute B-cell malignancies in mice. Lnk-deficient HSPCs recover more effectively from irradiation than their wild-type counterparts, and this resistance of Lnk(-/-) HSPCs to radiation underlies the subsequent emergence of leukemia. A search for the mechanism responsible for radiation resistance identified the cytokine IL-11 as being critical for the ability of Lnk(-/-) HSPCs to recover from irradiation and subsequently become leukemic. In IL-11 signaling, wild-type Lnk suppresses tyrosine phosphorylation of the Src homology region 2 domain-containing phosphatase-2/protein tyrosine phosphatase nonreceptor type 11 and its association with the growth factor receptor-bound protein 2, as well as activation of the Erk MAP kinase pathway. Indeed, Src homology region 2 domain-containing phosphatase-2 has a binding motif for the Lnk Src Homology 2 domain that is phosphorylated in response to IL-11 stimulation. IL-11 therefore drives a pathway that enhances HSPC radioresistance and radiation-induced B-cell malignancies, but is normally attenuated by the inhibitory adaptor Lnk.

Dicitore A, Caraglia M, Gaudenzi G, et al.
Type I interferon-mediated pathway interacts with peroxisome proliferator activated receptor-γ (PPAR-γ): at the cross-road of pancreatic cancer cell proliferation.
Biochim Biophys Acta. 2014; 1845(1):42-52 [PubMed] Related Publications
Pancreatic adenocarcinoma remains an unresolved therapeutic challenge because of its intrinsically refractoriness to both chemo- and radiotherapy due to the complexity of signaling and the activation of survival pathways in cancer cells. Recent studies have demonstrated that the combination of some drugs, targeting most of aberrant pathways crucial for the survival of pancreatic cancer cells may be a valid antitumor strategy for this cancer. Type I interferons (IFNs) may have a role in the pathogenesis and progression of pancreatic adenocarcinoma, but the limit of their clinical use is due to the activation of tumor resistance mechanisms, including JAK-2/STAT-3 pathway. Moreover, aberrant constitutive activation of STAT-3 proteins has been frequently detected in pancreatic adenocarcinoma. The selective targeting of these cell survival cascades could be a promising strategy in order to enhance the antitumor effects of type I IFNs. The activation of peroxisome proliferator-activated receptor γ (PPAR-γ), on the other hand, has a suppressive activity on STAT-3. In fact, PPAR-γ agonists negatively modulate STAT-3 through direct and/or indirect mechanisms in several normal and cancer models. This review provides an overview on the current knowledge about the molecular mechanisms and antitumor activity of these two promising classes of drugs for pancreatic cancer therapy. Finally, the synergistic antiproliferative activity of combined IFN-β and troglitazone treatment on pancreatic cancer cell lines, evaluated in vitro, and the consequent potential clinical applications will be discussed.

Related: PPARG gene Cancer of the Pancreas Pancreatic Cancer

Carduner L, Picot CR, Leroy-Dudal J, et al.
Cell cycle arrest or survival signaling through αv integrins, activation of PKC and ERK1/2 lead to anoikis resistance of ovarian cancer spheroids.
Exp Cell Res. 2014; 320(2):329-42 [PubMed] Related Publications
Ovarian cancer is the most lethal gynecologic cancer mainly due to spheroids organization of cancer cells that disseminate within the peritoneal cavity. We have investigated the molecular mechanisms by which ovarian cancer spheroids resist anoikis, choosing as models the 2 well-characterized human ovarian cancer cell lines IGROV1 and SKOV3. These cell lines have the propensity to float as clusters, and were isolated from tumor tissue and ascites, respectively. To form spheroids, IGROV1 and SKOV3 ovarian adenocarcinoma cells were maintained under anchorage-independent culture conditions, in which both lines survive at least a week. A short apoptotic period prior to a survival signaling commitment was observed for IGROV1 cells whereas SKOV3 cells entered G0/G1 phase of the cell cycle. This difference in behavior was due to different signals. With regard to SKOV3 cells, activation of p38 and an increase in p130/Rb occurred once anchorage-independent culture was established. Analyses of the survival signaling pathway switched on by IGROV1 cells showed that activation of ERK1/2 was required to evade apoptosis, an effect partly dependent on PKC activation and αv integrins. αv-integrin expression is essential for survival through activation of ERK1/2 phosphorylation. The above data indicate that ovarian cancer cells can resist anoikis in the spheroid state by arrest in the cell cycle or through activation of αv-integrin-ERK-mediated survival signals. Such signaling might result in the selection of resistant cells within disseminating spheroids, favoring further relapse in ovarian cancers.

Related: Ovarian Cancer

Corda D, De Matteis MA
Lipid signalling in health and disease.
FEBS J. 2013; 280(24):6280 [PubMed] Related Publications
This series of reviews is based on the FEBS Advanced Course on 'Lipid Signaling and Cancer' (4-10 October 2012, Vico Equense, Italy). The course encompassed the relationships between studies of basic and more translational aspects on the prevalence of altered lipid metabolism in different cancer types with a particular focus on phosphoinositides and sphingolipids. The reviews highlight both the basic aspects of these lipid classes and their roles in cancer development, and their potential as drug targets in cancer treatment.

Related: Cancer Prevention and Risk Reduction

Okon IS, Coughlan KA, Zou MH
Liver kinase B1 expression promotes phosphatase activity and abrogation of receptor tyrosine kinase phosphorylation in human cancer cells.
J Biol Chem. 2014; 289(3):1639-48 [PubMed] Article available free on PMC after 17/01/2015 Related Publications
Aberrant receptor tyrosine kinase phosphorylation (pRTK) has been associated with diverse pathological conditions, including human neoplasms. In lung cancer, frequent liver kinase B1 (LKB1) mutations correlate with tumor progression, but potential links with pRTK remain unknown. Heightened and sustained receptor activation was demonstrated by LKB1-deficient A549 (lung) and HeLaS3 (cervical) cancer cell lines. Depletion (siRNA) of endogenous LKB1 expression in H1792 lung cancer cells also correlated with increased pRTK. However, ectopic LKB1 expression in A549 and HeLaS3 cell lines, as well as H1975 activating-EGF receptor mutant lung cancer cell resulted in dephosphorylation of several tumor-enhancing RTKs, including EGF receptor, ErbB2, hepatocyte growth factor receptor (c-Met), EphA2, rearranged during transfection (RET), and insulin-like growth factor I receptor. Receptor abrogation correlated with attenuation of phospho-Akt and increased apoptosis. Global phosphatase inhibition by orthovanadate or depletion of protein tyrosine phosphatases (PTPs) resulted in the recovery of receptor phosphorylation. Specifically, the activity of SHP-2, PTP-1β, and PTP-PEST was enhanced by LKB1-expressing cells. Our findings provide novel insight on how LKB1 loss of expression or function promotes aberrant RTK signaling and rapid growth of cancer cells.

Related: Cancer Prevention and Risk Reduction AKT1

Herold CI, Anders CK
New targets for triple-negative breast cancer.
Oncology (Williston Park). 2013; 27(9):846-54 [PubMed] Related Publications
Triple-negative breast cancer (TNBC) lacks the three most commonly targeted receptors in human breast cancer--the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2)/neu--and it is associated with an aggressive natural history. More recently, TNBC has been further dissected into smaller, distinct subsets with unique molecular alterations and response to therapy. Large-scale genomic projects have yielded new knowledge about the molecular characteristics of TNBC, including similarities with high-grade serous ovarian cancers, suggesting a possible coordinated treatment algorithm for these malignancies. Moreover, translation of preclinical findings has led to clinical trials testing a plethora of targets and pathways in TNBC, which will be reviewed here; these include epidermal growth factor receptor (EGFR), angiogenesis, DNA repair capacity, epigenetic regulation, androgen receptor (AR) and folate receptor (FR) signaling, cell-cycle control, and cell survival. Given the complexity of TNBC biology and the lack of "traditional" therapeutic targets, the advancement of care for women with TNBC will require a true partnership between clinicians, translational investigators, and basic scientists.

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