ERK Signaling Cascade Research Articles

MiR-720 is a downstream target of an ADAM8-induced ERK signaling cascade that promotes the migratory and invasive phenotype of triple-negative breast cancer cells.

BackgroundADAM8 (a disintegrin and metalloproteinase 8) protein promotes the invasive and metastatic phenotype of triple-negative breast cancer (TNBC) cells. High ADAM8 expression in breast cancer patients is an independent predictor of poor prognosis. Here, we investigated whether ADAM8 regulates specific miRNAs, their roles in aggressive phenotype, and potential use as biomarkers of disease.MethodsMicroarray analysis was performed on RNA from MDA-MB-231 cells after transient ADAM8 knockdown using TaqMan miRNA cards. Changes in miRNA levels were confirmed using two ADAM8 siRNAs in TNBC cell lines. Kinase inhibitors, β1-integrin antagonist antibody, and different forms of ADAM8 were employed to elucidate the signaling pathway required for miR-720 expression. miR-720 levels were modulated using a specific antagomiR or a mimic, and effects on aggressive phenotype of TNBC cells were determined using Boyden chamber and 3D-Matrigel outgrowth assays. Plasma was isolated from mice before and after implantation of MDA-MB-231 cells and analyzed for miR-720 levels. Serum samples of TNBC patients were evaluated for their ADAM8 and miR-720 levels.ResultsWe identified 68 miRNAs differentially regulated upon ADAM8 knockdown, including decreased levels of secreted miR-720. Ectopic overexpression of wild-type ADAM8 or forms that lack metalloproteinase activity similarly induced miR-720 levels. The disintegrin and cysteine-rich domains of ADAM8 were shown to induce miR-720 via activation of a β1-integrin to ERK signaling cascade. Knockdown of miR-720 led to a significant decrease in migratory and invasive abilities of TNBC cells. Conversely, miR-720 overexpression rescued these properties. A profound increase in plasma levels of miR-720 was detected 7 days after TNBC cell inoculation into mouse mammary fat pads when tumors were barely palpable. Concordantly, miR-720 levels were found to be significantly higher in serum samples of TNBC patients with high ADAM8 expression.ConclusionsWe have shown for the first time that miR-720 is induced by ADAM8 signaling via ERK and plays an essential role in promoting the aggressive phenotype of TNBCs. miR-720 is elevated in serum of patients with ADAM8-high TNBC and, in a group with other miRNAs downstream of ADAM8, holds promise as a biomarker for early detection of or treatment response of ADAM8-positive TNBCs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-016-0699-z) contains supplementary material, which is available to authorized users.

Combinatorial treatment with anacardic acid followed by TRAIL augments induction of apoptosis in TRAIL resistant cancer cells by the regulation of p53, MAPK and NFκβ pathways

TRAIL, an apoptosis inducing cytokine currently in phase II clinical trial, was investigated for its capability to induce apoptosis in six different human tumor cell lines out of which three cell lines showed resistance to TRAIL induced apoptosis. To investigate whether Anacardic acid (A1) an active component of Anacardium occidentale can sensitize the resistant cell lines to TRAIL induced apoptosis, we treated the resistant cells with suboptimal concentration of A1 and showed that it is a potent enhancer of TRAIL induced apoptosis which up-regulates the expression of both DR4 and DR5 receptors, which has been observed in the cellular, protein and mRNA levels. The death receptors upregulation consequent to A1 treatment was corroborated by the activation of p53 as well as phosphorylation of p38 and JNK MAP kinases and concomitant inactivation of NFκβ and ERK signaling cascades. Also, A1 modulated the expression of key apoptotic players like Bax, Bcl-2 and CAD along with the abatement of tumor angiogenesis in vivo in EAT mouse model. Thus, post A1 treatment the TRAIL resistant cells turned into TRAIL sensitive cells. Hence our results demonstrate that A1 can synergize TRAIL induced apoptosis through the upregulation of death receptors and downregulation of anti-apoptotic proteins in cancer context.

Regulation of BRAF protein stability by a negative feedback loop involving the MEK–ERK pathway but not the FBXW7 tumour suppressor

The V600EBRAF oncogenic mutation is detected in a wide range of human cancers and induces hyperactivation of the downstream MEK–ERK signalling cascade. Although output of the BRAF–MEK–ERK pathway is regulated by feed-forward RAF activity, feedback control also plays an important role. One such feedback pathway has been identified in Caenorhabditis elegans and involves ERK-mediated phosphorylation of BRAF within a CDC4 phosphodegron (CPD), targeting BRAF for degradation via CDC4 (also known as FBXW7), a component of the SKP1/CUL1/F-box (SCF) E3 ubiquitin ligase complex. Here we investigate this pathway in mammalian cells. Short-term expression of autochthonous V600EBRAF in mouse embryonic fibroblasts (MEFs) leads to down-regulation of BRAF protein levels in a proteasome-dependent manner and V600EBRAF has a reduced half-life compared to WTBRAF in HEK293T cells. These effects were reversed by treatment with the MEK inhibitor PD184352. We have identified the equivalent CPD at residues 400–405 in human BRAF and have found that mutation of ERK phosphorylation sites at residues T401 and S405 in V600EBRAF increases the half-life of the protein. While BRAF and FBXW7 co-immunoprecipitated, the overexpression of FBXW7 did not influence the half-life of either WTBRAF or V600EBRAF. Furthermore, disruption of the substrate-binding site of mouse FBXW7 using the R482Q mutation did not affect the interaction with BRAF and the expression levels of WTBRAF and V600EBRAF were not altered in MEFs derived from mice with the homozygous knockin R482QFBXW7 mutation. Overall these data confirm the existence of a negative feedback pathway by which BRAF protein stability is regulated by ERK. However, unlike the situation in C. elegans, FBXW7 does not play a unique role in mediating subsequent BRAF degradation.

Environmental enrichment improves learning and memory and long-term potentiation in young adult rats through a mechanism requiring mGluR5 signaling and sustained activation of p70s6k

Previous studies from our lab have demonstrated that mild cognitive impairments identified early in life are predictive of cognitive deficits that develop with age, suggesting that enhancements in cognition at an early age can provide a buffer against age-related cognitive decline. Environmental enrichment has been shown to improve learning and memory in the rodent, but the impact of enrichment on synaptic plasticity and the molecular mechanisms behind enrichment are not completely understood. To address these unresolved issues, we have housed 2-month old rats in environmentally enriched (EE), socially enriched (SE), or standard housing (SC) and conducted tests of learning and memory formation at various time intervals. Here we demonstrate that animals that have been exposed to one month of social or environmental enrichment demonstrate enhanced learning and memory relative to standard housed controls. However, we have found that after 4months EE animals perform better than both SE and SC groups and demonstrate an enhanced hippocampal LTP. Our results demonstrate that this LTP is dependent on mGluR5 signaling, activation of ERK and mTOR signaling cascades, and sustained phosphorylation of p70s6 kinase, thus providing a potential target mechanism for future studies of cognitive enhancement in the rodent.

Abstract 3094: Sprouty and cell proliferation in colorectal cancer

Abstract BACKGROUND & AIMS: Sprouty (SPRY) proteins are evolutionarily conserved modulators of mitogen-activated protein kinase pathway. SPRY2 appears to function as a tumor suppressor in other cancers, whereas we reported that SPRY2 functions as an oncogene in colorectal cancer (CRC). To further understand the oncogenic potential of SPRY1 and SPRY2 in CRC, we investigated the mechanisms by which these proteins regulate cell proliferation in CRC. MATERIALS & METHODS: Human CRC cDNA arrays were employed to assess mRNA levels of SPRY1, SPRY2 and p21. SPRY1 and SPRY2 were knocked-down in CaCo2 colon cancer cells by siRNA. Effects of SPRY were assessed by immunoblotting, real time PCR, luciferase reporter assay, and confocal microscopy. Mouse embryonic fibroblasts (MEFs) derived from SPRY mutant mice were utilized to dissect SPRY functions in mesenchymal cells. RESULTS: In this study, surprisingly, we present evidence to suggest that concomitant activation of ERK, p-38 and AKT signaling cascades is insufficient to drive cancer cell proliferation in SPRY modulated cells. Suppression of SPRY in colon cancer cells upregulates p21, a cell cycle inhibitor. SPRY2 dependent p21 promoter activation may account for upregulation of p21 expression and inhibition of cancer cell proliferation. Underscoring the biological relevance of these findings, recombination of floxed SPRY1 and SPRY2 alleles in mouse embryonic fibroblasts (MEFs) resulted in increased expression of p21. Finally, in a human CRC cDNA array we established an inverse correlation of SPRY1 and SPRY2 with p21 mRNA expression. CONCLUSIONS: Together, this study indicates that SPRY is a target of therapeutic intervention in CRC. Citation Format: Qiong Zhang, Katherine Shim, Kevin Wright, Alexander Jurkevich, Sharad Khare. Sprouty and cell proliferation in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3094. doi:10.1158/1538-7445.AM2015-3094

Suppression of IGF-I signals in neural stem cells enhances neurogenesis and olfactory function during aging.

Downregulation of insulin-like growth factor (IGF) pathways prolongs lifespan in various species, including mammals. Still, the cellular mechanisms by which IGF signaling controls the aging trajectory of individual organs are largely unknown. Here, we asked whether suppression of IGF-I receptor (IGF-1R) in adult stem cells preserves long-term cell replacement, and whether this may prevent age-related functional decline in a regenerating tissue. Using neurogenesis as a paradigm, we showed that conditional knockout of IGF-1R specifically in adult neural stem cells (NSC) maintained youthful characteristics of olfactory bulb neurogenesis within an aging brain. We found that blocking IGF-I signaling in neural precursors increased cumulative neuroblast production and enhanced neuronal integration into the olfactory bulb. This in turn resulted in neuro-anatomical changes that improved olfactory function. Interestingly, mutants also displayed long-term alterations in energy metabolism, possibly related to IGF-1R deletion in NSCs throughout lifespan. We explored Akt and ERK signaling cascades and revealed differential regulation downstream of IGF-1R, with Akt phosphorylation preferentially decreased in IGF-1R−/− NSCs within the niche, and ERK pathway downregulated in differentiated neurons of the OB. These challenging experimental results were sustained by data from mathematical modeling, predicting that diminished stimulation of growth is indeed optimal for tissue aging. Thus, inhibiting growth and longevity gene IGF-1R in adult NSCs induced a gain-of-function phenotype during aging, marked by optimized management of cell renewal, and enhanced olfactory sensory function.

Sulforaphane inhibits thyroid cancer cell growth and invasiveness through the reactive oxygen species-dependent pathway.

Sulforaphane (SFN), a natural compound derived from broccoli/broccoli sprouts, has been demonstrated to be used as an antitumor agent in different types of cancers. However, its antitumor effect in thyroid cancer remains largely unknown. The aim of the study was to investigate the therapeutic potential of SFN for thyroid cancer and explore the mechanisms underlying antitumor effects of SFN by in vitro and in vivo studies. Our data demonstrated that SFN significantly inhibited thyroid cancer cell proliferation in a dose- and time-dependent manner, induced G2/M phase cell cycle arrest and apoptosis, and inhibited thyroid cancer cell migration and invasion by suppressing epithelial-mesenchymal transition (EMT) process and expression of Slug, Twist, MMP-2 and -9. Mechanically, SFN inhibited thyroid cancer cell growth and invasiveness through repressing phosphorylation of Akt, enhancing p21 expression by the activation of Erk and p38 signaling cascades, and promoting mitochondrial-mediated apoptosis via reactive oxygen species (ROS)-dependent pathway. Growth of xenograft tumors derived from thyroid cancer cell line FTC133 in nude mice was also significantly inhibited by SFN. Importantly, we did not find significant effect of SFN on body weight and liver function of mice. Collectively, we for the first time demonstrate that SFN is a potentially effective antitumor agent for thyroid cancer.

A phase Ib study of investigational pan-RAF kinase inhibitor MLN2480 plus investigational TORC1/2 inhibitor MLN0128, investigational Aurora A kinase inhibitor alisertib (MLN8237), or paclitaxel in patients (pts) with advanced solid tumors.

TPS2609 Background: Signaling hyperactivation secondary to MAPK pathway aberrations are common. RAF kinases play key roles in the RAS/RAF/MEK/ERK signaling cascade, representing potentially valid t...

Intraarticular gene transfer of SPRY2 suppresses adjuvant-induced arthritis in rats.

AKT and ERK pathways have been implicated as therapeutic targets for human rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) inhibition, and thus RA treatment. Sprouty2 (SPRY2) has been known as a tumor suppressor by blocking both ERK and AKT signaling cascades. Whether SPRY2 can function as a suppressor of tumor-like inflammatory FLS and RA through negatively regulating AKT and ERK activation has not been reported. The purpose of this study was to determine whether SPRY2 might have antiarthritic effects in experimental animal model of RA. We first determined that expression of SPRY2 mRNA was decreased in FLS from patients with RA compared with patients with osteoarthritis (OA). Further studies demonstrated that intraarticular gene transfer with AdSPRY2, the recombinant adenovirus containing SPRY2 complementary DNA, resulted in a significant suppression of rat adjuvant-induced arthritis (AIA) compared with the control AdGFP, the adenoviral vector encoding green fluorescent protein, as reflected in both clinical and histological observations. AdSPRY2 suppressed the production of proinflammatory cytokines and matrix metalloproteinases (MMPs), and the activation of ERK and AKT signals in AIA ankle joints. These results suggest that using SPRY2 to block the AKT and ERK pathways effectively reduces the inflammatory responses and arthritic progression in AIA. Thus, the development of an immunoregulatory strategy based on SPRY2 may therefore have therapeutic potential in the treatment of RA.

Leptin Induces a Novel Form of NMDA Receptor-Dependent LTP at Hippocampal Temporoammonic-CA1 Synapses

It is well documented that the hormone leptin regulates many central functions and that hippocampal CA1 pyramidal neurons are a key target for leptin action. Indeed, leptin modulates excitatory synaptic transmission and synaptic plasticity at the Schaffer-collateral input to CA1 neurons. However the impact of leptin on the direct temporoammonic (TA) input to CA1 neurons is not known. Here we show that leptin evokes a long-lasting increase [long-term potentiation (LTP)] in excitatory synaptic transmission at TA-CA1 synapses in rat juvenile hippocampus. Leptin-induced LTP was NMDA receptor-dependent and specifically involved the activation of GluN2B subunits. The signaling pathways underlying leptin-induced LTP involve the activation of phosphoinositide 3-kinase, but were independent of the ERK signaling cascade. Moreover, insertion of GluA2-lacking AMPA receptors was required for leptin-induced LTP as prior application of philanthotoxin prevented the effects of leptin. In addition, synaptic-induced LTP occluded the persistent increase in synaptic efficacy induced by leptin. In conclusion, these data indicate that leptin induces a novel form of NMDA receptor-dependent LTP at juvenile TA-CA1 synapses, which has important implications for the role of leptin in modulating hippocampal synaptic function in health and disease.

Formononetin inhibits enterovirus 71 replication by regulating COX- 2/PGE2 expression

BackgroundThe activation of ERK, p38 and JNK signal cascade in host cells has been demonstrated to up-regulate of enterovirus 71 (EV71)-induced cyclooxygenase-2 (COX-2)/ prostaglandins E2 (PGE2) expression which is essential for viral replication. So, we want to know whether a compound can inhibit EV71 infection by suppressing COX-2/PGE2 expression.MethodsThe antiviral effect of formononetin was determined by cytopathic effect (CPE) assay and the time course assays. The influence of formononetin for EV71 replication was determined by immunofluorescence assay, western blotting assay and qRT-PCR assay. The mechanism of the antiviral activity of formononetin was determined by western blotting assay and ELISA assay.ResultsFormononetin could reduce EV71 RNA and protein synthesis in a dose-dependent manner. The time course assays showed that formononetin displayed significant antiviral activity both before (24 or 12 h) and after (0–6 h) EV71 inoculation in SK-N-SH cells. Formononetin was also able to prevent EV71-induced cytopathic effect (CPE) and suppress the activation of ERK, p38 and JNK signal pathways. Furthermore, formononetin could suppress the EV71-induced COX-2/PGE2 expression. Also, formononetin exhibited similar antiviral activities against other members of Picornaviridae including coxsackievirus B2 (CVB2), coxsackievirus B3 (CVB3) and coxsackievirus B6 (CVB6).ConclusionsFormononetin could inhibit EV71-induced COX-2 expression and PGE2 production via MAPKs pathway including ERK, p38 and JNK. Formononetin exhibited antiviral activities against some members of Picornaviridae. These findings suggest that formononetin could be a potential lead or supplement for the development of new anti-EV71 agents in the future.

Cadmium induced apoptosis in mouse primary hepatocytes: the role of oxidative stress-mediated ERK pathway activation and the involvement of histone H3 phosphorylation

Time-delayed apoptosis induced by cadmium in primary hepatocytes through DNA damage, histone modification and ERK signaling cascade, which are all mediated by oxidative stress.

Constitutively active Ras negatively regulates Erk MAP kinase through induction of MAP kinase phosphatase 3 (MKP3) in NIH3T3 cells

The Ras/Raf/MEK/Erk signaling pathway is important for regulation of cell growth, proliferation, differentiation, survival, and apoptosis in response to a variety of extracellular stimuli. Lack of Erk MAPK activation is observed in several cancer cells despite active activation of Ras. However, little is known about the modulation of Erk1/2 activity by active Ras. Here, we show that overexpression of active H-Ras (H-RasG12R) in NIH3T3 fibroblasts impaired FGF2-induced Erk1/2 phosphorylation, as compared to wild-type cells. Northern blot analysis revealed that prolonged expression of active Ras increased MAP kinase phosphatase 3 (MKP3) mRNA expression, a negative regulator of Erk MAPK. Inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway abrogated active Ras-induced up-regulation of MKP3 expression, leading to the rescue of Erk1/2 phosphorylation. Our results demonstrated that the Ras/Raf/MEK/Erk signaling cascade is negatively regulated by the PI3K/Aktdependent transcriptional activation of the MKP3 gene. [BMB Reports 2014; 47(12): 685-690]

Differential effects of the Toll-like receptor 2 agonists, PGN and Pam3CSK4 on anti-IgE induced human mast cell activation.

Mast cells are pivotal in the pathogenesis of allergy and inflammation. In addition to the classical IgE-dependent mechanism involving crosslinking of the high-affinity receptor for IgE (FcεRI), mast cells are also activated by Toll-like receptors (TLRs) which are at the center of innate immunity. In this study, we demonstrated that the response of LAD2 cells (a human mast cell line) to anti-IgE was altered in the presence of the TLR2 agonists peptidoglycan (PGN) and tripalmitoyl-S-glycero-Cys-(Lys)4 (Pam3CSK4). Pretreatment of PGN and Pam3CSK4 inhibited anti-IgE induced calcium mobilization and degranulation without down-regulation of FcεRI expression. Pam3CSK4 but not PGN acted in synergy with anti-IgE for IL-8 release when the TLR2 agonist was added simultaneously with anti-IgE. Studies with inhibitors of key enzymes implicated in mast cell signaling revealed that the synergistic release of IL-8 induced by Pam3CSK4 and anti-IgE involved ERK and calcineurin signaling cascades. The differential modulations of anti-IgE induced mast cell activation by PGN and Pam3CSK4 suggest that dimerization of TLR2 with TLR1 or TLR6 produced different modulating actions on FcεRI mediated human mast cell activation.

Thiazolidine-2,4-diones as multi-targeted scaffold in medicinal chemistry: Potential anticancer agents.

A variety of substituents on the thiazolidine-2,4-dione(TZD) nucleus have provided a wide spectrum of biological activities by the using of different mechanism on various target sites. PPARγ ligands have recently been demonstrated to affect cell proliferation, differentiation and apoptosis of different cell types. Currently, some of the TZDs are designed for the treatment of human cancers expressing high levels of PPARγ because it is assumed that activation of PPARγ mediates their anticancer activity. Another site for TZDs is survival signaling pathways under growth factor loops have been implicated in cancer development, progression, and metastasis. The Raf/MEK/ERK, Wnt and PI3K/Akt signalling cascades are the most commonly up-regulated in human cancers. In the present review, various derivatives of thiazolidine-2,4-diones its SAR and different signaling pathways involved to produce anticancer activity been highlighted.

Identification of PAQR3 as a new candidate tumor suppressor in hepatocellular carcinoma.

Progestin and adipoQ receptor family member III (PAQR3) is a regulator that negatively modulates the Ras/Raf/MEK/ERK signaling cascade and the GPCR Gβγ subunit signaling pathway. The role of PAQR3 in hepatocellular carcinoma (HCC) has not been elucidated. The present study investigated the expression of PAQR3 and its prognostic value in primary HCC patients. Furthermore, the functional aspects of PAQR3 were also studied using an in vitro cell model. PAQR3 expression was examined in paired HCC and adjacent noncancerous tissues using real-time quantitative RT-PCR (62 pairs) and western blotting (26 pairs). We also analyzed PAQR3 expression in 132 additional HCC samples by immunohistochemistry. The functional impact of PAQR3 on the proliferation and colony formation of an HCC cell line was analyzed by transfecting cells with a full-length PAQR3 expression vector or siRNA targeting PAQR3. The expression of PAQR3 was significantly decreased in the cancer tissues. Clinicopathological analyses showed that the expression of PAQR3 was significantly correlated with expression of serum α-fetoprotein (AFP), mitotic count, tumor size, histological grade and recurrence. Notably, Kaplan-Meier survival curves revealed a correlation between decreased expression of PAQR3 and the poor prognosis of HCC patients. Multivariate analyses showed that PAQR3 expression is an independent prognostic marker for overall and disease-free survival of HCC patients. Furthermore, restoring PAQR3 expression in HCC cells significantly diminished Hep3B cell proliferation and colony formation. Silencing PAQR3 expression in hepatic normal cell line LO2 significantly enhanced cell growth. PAQR3 may play an important role in the progression of HCC and serve as a potential candidate for the targeted therapy of HCC.

Abstract 740: Phenotypic profiling and selectivity optimization of ERK inhibitors using a high-throughput imaged-based cell cycle assay

Abstract The extracellular-signal-regulated kinases (ERK-1 and ERK-2) represent an essential node within the RAS/RAF/MEK/ERK signaling cascade that is commonly activated due to oncogenic mutations in RAF or RAS or due to upstream oncogenic signaling, such as through receptor tyrosine kinase (RTK) signaling. We have discovered and developed potent and selective small molecule inhibitors of both ERK-1 and 2. Optimization of kinase selectivity was a critical goal in order for ATP-competitive ERK inhibitors to maintain parity with the safety profile of highly selective allosteric MEK inhibitors. As a complement to enzymatic kinase panel profiling, we employed an imaged-based cell cycle assay, based on the expected on-target phenotype of cytostatic G1 arrest in B-Raf-mutant cell lines. We were thus able to simultaneously measure on-target and off-target activities. Inhibition of Cdk2, one of the primary off-targets, was associated with a distinct G2 cell cycle arrest, which enabled us to quantify the functional selectivity margin between ERK and Cdk2 in a single assay, and select ERK inhibitors with acceptable selectivity margins for further development. Note: This abstract was not presented at the meeting. Citation Format: Grace Ka-Yan Chan, Tracy Kleinheinz, Matthew Martinson, Hok-Sum Cheung, John G. Moffat. Phenotypic profiling and selectivity optimization of ERK inhibitors using a high-throughput imaged-based cell cycle assay. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 740. doi:10.1158/1538-7445.AM2014-740

Abstract 1714: Erk inhibitor overcomes type II interleukin 1 receptor, a decoy receptor, associated Regorafenib resistance in colorectal carcinoma

Abstract We have previously demonstrated that type II interleukin 1 receptor (IL1R2), which is an IL-1 decoy receptor and inhibits exogenous IL-1 signaling, activates the expression of several proinflammatory cytokines. We also found that enhanced expression of IL1R2 promotes tumor growth and increases tumor angiogenesis through activated IL-6/VEGF-A signalings. Recently, we observed a close association of enhanced expression of IL1R2 and Regorafenib resistance in colorectal cancer (CRC) cell lines. Regorafenib is the newly approved multi-kinase inhibitor used for treatment of late-stage metastatic CRC by US FDA. To have a better use of Regorafenib against CRC, we conducted experiments to understand the mechanism underlying which IL1R2 is involved in Regorafenib resistance. In the present study, we demonstrated that silencing of IL1R2 in HT29 cell overcame its resistance to Regorafenib whereas ectopic expression of IL1R2 decreased the sensitivity of HCT116 cell to Regorafenib in in vitro and in vivo systems. IL1R2 silencing also enhanced the apoptotic proteins expression in Regorafenib-treated cells. In addition, we have established Regorafenib-resistant DLD-1 colon cancer cells by growing them in the presence of Regorafenib. Consistently, higher IL1R2 expression was found in Regorafenib-resistant cells than the parental cells. Mechanistically, we observed that Regorafenib treatment significantly resulted in enhanced expression of extracellular-signal-regulated kinase (Erk), which functions as a survival factor, in IL1R2-overexpressing cells. Therefore, pretreatment of IL1R2-overepressing CRC cells with Erk inhibitor, U0126, reversed their Regorafenib resistance, suggesting that Erk signaling cascade is crucial in Regorafenib resistance resulted from IL1R2 overexpression. Taken together, our present study suggested that combination of Regorafenib and Erk inhibitor is a rationale regime to overcome IL1R2 overexpression-induced Regorafenib resistance in CRC patients, but also IL1R2 is a potential biomarker for colon cancer therapy. Citation Format: Ai-Chung Mar, Chun-Ho Chu, Te-Chang Lee. Erk inhibitor overcomes type II interleukin 1 receptor, a decoy receptor, associated Regorafenib resistance in colorectal carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1714. doi:10.1158/1538-7445.AM2014-1714

Abstract DDT02-03: Discovery of GDC-0994, a potent and selective ERK1/2 inhibitor in early clinical development

Abstract The extracellular-signal-regulated kinases (ERK1 and ERK2) represent an essential node within the RAS/RAF/MEK/ERK signaling cascade that commonly is activated by oncogenic mutations in BRAF or RAS or by upstream oncogenic signaling, such as receptor tyrosine kinase (RTK) activation. While targeting upstream nodes with RAF and MEK inhibitors has proven effective clinically, resistance frequently develops through reactivation of the pathway. Simultaneous targeting of multiple nodes in the pathway, such as MEK and ERK, offers the prospect of enhanced efficacy as well as reduced potential for acquired resistance. Here, we present the discovery and characterization of GDC-0994, an orally bioavailable, small molecule inhibitor of ERK kinase activity. GDC-0994 is highly selective for ERK1 and ERK2, with biochemical potency of 1.1 nM and 0.3 nM, respectively. Daily, oral dosing of GDC-0994 results in significant single-agent activity in multiple in vivo cancer models, including KRAS-mutant and BRAF-mutant human xenograft tumors in mice. PD biomarker inhibition of phospho-p90RSK in these tumors correlates with potency in vitro and in vivo. In contrast to other published ERK inhibitors, GDC-0994 neither increases nor decreases phospho-ERK, suggesting that different ERK inhibitors have alternative mechanisms of action with respect to feedback signaling. Furthermore, we demonstrate a novel approach for targeting the oncogenic signaling through the RAS pathway by combining ERK and MEK inhibitors. GDC-0994 is currently in Phase I clinical development. Citation Format: Kirk Robarge, Jacob Schwarz, Jim Blake, Michael Burkard, Jocelyn Chan, Huifen Chen, Kang-Jye Chou, Dolores Diaz, John Gaudino, Stephen Gould, Jonas Grina, Xin Linghu, Lichuan Liu, Matthew Martinson, David A. Moreno, Christine Orr, Patricia Pacheco, Ann Qin, Kevin Rasor, Li Ren, Sheerin Shahidi-Latham, Jeffrey Stults, Francis Sullivan, Weiru Wang, Peter Yin, Aihe Zhou, Marcia Belvin, Mark Merchant, John G. Moffat. Discovery of GDC-0994, a potent and selective ERK1/2 inhibitor in early clinical development. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr DDT02-03. doi:10.1158/1538-7445.AM2014-DDT02-03

Abstract 5128: Different effect of irinotecan induced apoptosis in k-Ras wild and mutant type colon cancer cell lines

Abstract Irinotecan(IRI) prevents DNA from unwinding by inhibition of topoisomerase I. Its main use is in colon cancer, in particular, in combination with other chemotherapy agents. Recent studies, those with Irinotecan treatment has a synergistic effect appears. However, there is no study on the effect of the Irinotecan mono-treatment. In addition their roles and the underlying mechanism in anti-tumorigenic function of solid tumor, especially kras wild and mutant type colon cancer, are not yet known. Bax protein is a key mediator of apoptosis and might be related to chemosensitivity. In this work, we evaluated the anti-tumorigenic action of these Irinotecan anti-cancer agent with especially k-ras wild and mutant type colon cancer cell lines, and investigated their apoptosis-inducing effects as the potential mechanism in this process. The results show that the growth inhibitory effects of 5-fuorouracil (5-FU), Oxaliplatin(OX) produced a dose- and time dependent fashion in k-ras wild(HT29, Colo205) and mutant type(HCT116, DLD-1) colon cancer cell lines. Otherwise, Irinotecan(IRI) produced a cell growth of k-ras wild type cell lines were resistant versus that shown in the sensitive k-ras mutant type cell lines. Cell cycle analysis by FACS indicated that IRI-treated cell lines showed an increase in the proportion of cells in sub-G1 phase, compared to untreated cells. Exposure of colon cancer cells to IRI also resulted in the increase in the percentage of annexin V- positive and PI-negative cells. The results by multiple in vitro experimental model, showed that IRI induce these k-ras mutant type colon cancer cells to undergo apoptosis with increased the Bax protein and a release of cytochrome C from mitochondria, the activation of caspase9, the cleavage of PARP. But Bax protein was inactivation in k-ras wild type colon cancer cell lines. Importantly, inhibition of ERK kinase activity demonstrated that IRI-induced apoptotic pathway was regulated by the ERK signaling cascade. These data indicate that Anti-cancer agent, Irinotecan, promotes Bax-mediate apoptosis of colon cancer cell lines by sequential activation of the ERK signaling pathway followed by the up-regulation of intrinsic pathway of caspase 9. Citation Format: Myoung Hee Kang, Jung Lim Kim, Bo Ram Kim, Yoo Jin Jang, Sun Il Lee, Jun Suk Kim, Sang cheul Oh. Different effect of irinotecan induced apoptosis in k-Ras wild and mutant type colon cancer cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5128. doi:10.1158/1538-7445.AM2014-5128