bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 5065: Phosphorylation of Peptidyl prolyl isomerase 1 by Mixed Lineage Kinase 3 promotes breast cancer pathogenesis
Authors: Mishra Rajakishore , Sondarva Gautam , Kanthasamy Anumantha , Rana Basabi , Rana Ajay 
Published: February 2011

Abstract
MLK3 is a member of MLK sub-family that belongs to the family of MAP kinase kinase kinase (MAP3K). The MLK family members are characterized by the presence of signature sequences of Ser/Thr and Tyr kinases within their catalytic domain. The detailed physiological function of MLK3 is yet to be deciphered fully, however the available data suggest that in neuronal cells, MLK3 plays role of a pro-apoptotic kinase. The function of MLK3 in any type of cancer is not known. Interestingly the C-terminal tail of MLK3 contains consensus sequences for various protein-protein interactions and phosphorylation sites for numerous kinases. The C-terminal tail also contains Ser/Thr-Pro sequence, a consensus sequence for prolyl isomerase (Pin1), which has been reported to be over-expressed in cancer cells, including in breast cancer cells and primary tumors.
Our initial hypothesis was that probably Pin1 binds to MLK3 and regulates MLK3's kinase activity. Our in vivo binding indeed suggested that Pin1 binds to MLK3 via PPI domain robustly and to certain extent through WW domain. The binding of Pin1 did not alter the kinase activity of MLK3. Interestingly, counterintuitive to our initial hypothesis, we observed that MLK3 was able to phosphorylate Pin1 and alter Pin1's isomerase activity. We also identified S138 as a phosphorylation site on Pin1 and raised p-S138 antibody. Since, Pin1 is known to drive G2-M-cell cycle transition, we examined whether phosphorylation of Pin1 promotes cell cycle progression. Our data indicated that phospho-S138 Pin1 increased the G2-M transition of cell cycle. Pin1 is reported to be a nuclear protein; however it is not known whether this translocation of Pin1is regulated by any protein. We observed that Pin1 was translocated to nucleus upon phosphorylation by MLK3 at S138 site and the phospho-S138 Pin1 was highly expressed in breast cancer cell lines and tumors, compared to non-transformed breast epithelial cell line and normal breast tissues respectively. The breast cancer tissue arrays analyzed also showed that phospho-S138 was highly expressed in tumors compared to normal breast tissue and the intensity of staining was significantly higher in tumors as well.
Taken together, our data suggest that phosphorylation of Pin1 by MLK3 drives G2-M transition and promote breast cancer pathogenesis. Thus targeting MLK3 or Pin1 may prove beneficial to control breast cancer tumorigenesis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5065.
Abstract 5074: Identification of Ras compartment-specific interacting proteins
Authors: Zheng Ze-Yi , Cheng Chiang-min , Fu Xin-Rong , Songyang Zhou , Chang Eric C. 
Published: February 2011

Abstract
Ras proteins are powerful molecular switches that control a wide range of functions, including cell growth, differentiation, apoptosis, cytoskeleton remodeling, etc. In humans, there are three RAS genes encode structurally highly similar Ras proteins that appear to have different functions in the cell. We have previously reported that a given Ras protein can signal from different cell compartments to control distinct functions in yeast. This present project aims to identify proteins that bind Ras in a cell compartment-specific manner in human cells to define how compartmentalized Ras signaling impacts tumor formation. We used the biomolecular fluorescence complementation (BiFC) method to screen a human cDNA library. Sixty two proteins were thus identified that bound the constitutively activated H-Ras (H-RasG12V), but not the GST control. These proteins also bound weakly to H-RasG12V whose effector binding motif has been mutated. To determine if these proteins can alter Ras functions, we first overexpressed them and then tested for their impacts on Ras-induced cell transformation and transcription. Only 25 of the isolated proteins could alter Ras signaling in these assays. Many of these 25 proteins are known to either associate with cellular membrane and/or regulate protein transportation, suggesting that as a group they highlight the importance of regulating Ras trafficking in the control of cell transformation. In particular, a number of isolated proteins may regulate endosome sorting, and we thus focused on two such proteins, CHMP6/VPS20 and VPS4A, for further investigation. We first validated the Ras binding by co-immunoprecipitation; furthermore the microscopy data showed that the binding is readily detectable in endosomes. Moreover, up- or down-regulating of level of either CHMP6/VPS20 or VPS4A dramatically inhibited Ras-induced transformation of NIH-3T3 cells. To determine how these molecules regulate Ras activities, we first examined whether they modulate Ras protein intracellular transport. Cell fractionation using sucrose gradients has shown that VPS4A knock-down could alter both wide-type and constitutively activated Ras membrane localization. In summary, we indentified Ras compartment-specific binding proteins by a cell-based approach. Many of the proteins are trafficking regulating proteins. In particular, two endosome sorting proteins CHMP6/VPS20 and VPS4A have been shown to regulate the oncogenic effects of Ras, possibly by localizing Ras proteins into proper cell compartments. We believe that the study of compartment-specific Ras interacting proteins is indispensable for better understanding the complex roles of Ras in oncogenesis of breast cancer as well as many other cancers.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5074.
Abstract 5076: Dissection of RAS downstream pathways in melanomagenesis
Authors: Mishra Prasun J. , Ha Linan , Rieker Jennifer , Sviderskaya Elena , Bennett Dorothy , Oberst Michael D. , Kelly Kathleen , Merlino Glenn 
Published: February 2011

Abstract
Cutaneous malignant melanoma is considered one of the most deadly human cancers, based upon both its penchant for metastatic spread and its typical resistance to currently available therapy. Long known to harbor oncogenic NRAS mutations, melanomas were more recently reported to be frequent bearers of activating mutations in BRAF, one of the effectors situated downstream of wildtype NRAS. RAS gene products (HRas, KRas and NRas) are 21kd G-proteins that serve as molecular switches converting cell-surface kinase activation events to nuclear events, thus influencing cell behavior. The major downstream effectors of Ras are the Rafs (ARaf, BRaf and CRaf), phosphatidylinositol 3-kinase (PI3K) and the Ral guanine exchange factors (RalGEF). NRAS and BRAF mutations are rarely found in the same melanoma, suggesting that they may possess important overlapping oncogenic activities. Here we compare and contrast the oncogenic roles of the three major NRas downstream effectors, Raf, PI3K and RalGEF, using genetically engineered Arf-deficient immortalized mouse melanocytes as a model system. Activation of each of the three major downstream pathways of NRas has overt phenotypic effects on immortalized mouse melanocytes, many distinct. Our data indicate a prominent role for BRaf and PI3K in melanocyte senescence and invasiveness, respectively. More surprisingly, we found that constitutively activated RalGEF stimulated melanocyte invasiveness and anchorage-independent growth almost as impressively as NRasQ61K. The suppressive effects of expression of a dominant negative Ral corroborated the role of the RalGEF-Ral pathway in anchorage-independent growth. Although no single downstream pathway could recapitulate all of the consequences of oncogenic NRas expression, melanocytes expressing constitutively activated mutants of all three NRas downstream factors (RLF-CAAX plus p110α-CAAX plus BRafV600E) achieved soft agar colony forming efficiency that was fully comparable to those expressing NRasQ61K alone. In conclusion, our data suggested a distinct function for all three NRas downstream pathways - Raf, PI3K and Ral in melanocyte senescence, invasiveness and transformation, respectively. Importantly, our finding that constitutive RalGEF activation confers malignant phenotypes in melanocytes, particularly anchorage-independent growth, indicates that this often overlooked pathway should be more carefully evaluated as a possible therapeutic target.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5076.
Abstract 5077: Signaling through the cytoplasmic tail of MUC1 directly activates transcription of the metastasis promoting growth factor CTGF in pancreatic adenocarcinoma
Authors: Behrens Michelle , Grandgenett Paul , Bailey Jennifer , Singh Pankaj , Yi Chun-Hui , Hollingsworth Michael 
Published: February 2011

Abstract
Transmembrane mucin MUC1 is highly expressed in pancreatic adenocarcinoma and contributes to tumor growth, invasion, and metastasis. Differential phosphorylation of the cytoplasmic tail of MUC1 (MUC1.CT) by growth factor receptor tyrosine kinases is associated with morphogenetic signal transduction, as it enables interactions with signal transducers and leads to nuclear accumulation of MUC1.CT. MUC1.CT contains no known DNA binding motif but localizes to promoters of genes implicated in tumorigenesis in complex with transcription factors, modulating their regulatory activity. Using microarray analysis, we identified genes differentially transcribed in S2013 pancreatic adenocarcinoma cells stably overexpressing MUC1. These data were correlated with transcriptional targets of MUC1.CT identified on a genome-wide scale in pancreatic adenocarcinoma cells using a combination of chromatin immunoprecipitation and promoter array methodologies (ChIP-on-chip). We further investigated the transcriptional regulation of one novel target, connective tissue growth factor (CTGF/CCN2), by MUC1.CT. CTGF is highly expressed in pancreatic cancer and is a known mediator of tumor growth, angiogenesis, and metastasis. Overexpression of MUC1 significantly increased CTGF expression in pancreatic tumor cells in response to EGF, PDGF-BB, or HGF stimulation. The MUC1.CT becomes phosphorylated by EGFR, PDGFR-beta, and c-Met and overexpression of MUC1 constructs harboring mutations within the target phosphorylation motifs for these receptor tyrosine kinases reduced CTGF expression. We determined that MUC1.CT directly regulated the CTGF gene transcription through co-occupancy with transcription factors at several regions within and surrounding the CTGF promoter. MUC1 overexpression promoted localization of mutant p53 (R273H) and beta-catenin to the CTGF promoter, while decreasing occupancy by a repressor of CTGF transcription, c-Jun. We propose that MUC1, when overexpressed in pancreatic adenocarcinoma, enables expression of CTGF in response to growth factor stimulations by promoting mutant p53 and beta-catenin transcriptional activity and alleviating CTGF transcriptional repression by c-Jun. Taken together, these results reveal a novel signaling pathway that selectively induces CTGF expression in MUC1-overexpressing pancreatic tumor cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5077.
Abstract 5086: Pemetrexed induces a strong activation of AMPK in human carcinoma cells, even in the absence of LKB1
Authors: Rothbart Scott B. , Racanelli Alexandra C. , Moran Richard G. 
Published: February 2011

Abstract
AMP-activated protein kinase (AMPK) is a major cellular energy sensor, functioning as a regulator of signaling cascades controlling protein, lipid, and carbohydrate metabolism. Because of the dependence of many tumors on the deregulation of the PI3K-AKT-mTOR signaling cascade, the discovery of AMPK activators is an attractive approach for cancer therapeutics, aimed at reinstating control over cellular metabolic functions altered during carcinogenesis rather than inhibiting cellular targets. The antifolate pemetrexed is FDA approved for first line treatment of mesothelioma and non-small cell lung cancer (NSCLC). While pemetrexed acts primarily as a thymidylate synthase inhibitor, we discovered that the drug is also an inhibitor of aminoimidazolecarboxamide ribonucleotide formyltransferase (AICART), the second folate-dependent enzyme of de novo purine synthesis. The inhibition of AICART by pemetrexed resulted in a marked accumulation of the reaction substrate, ZMP, a known allosteric activator of AMPK in several human carcinoma cell lines. The mammalian target of rapamycin complex 1 (mTORC1) was inhibited following pemetrexed treatment, as determined by hypophosphorylation of S6K1 and 4EBP1, and this effect was dependent on AMPK activation. Co-administration of GSK690693, a pan AKT inhibitor prolonged mTORC1 inhibition following pemetrexed treatment and offset the consequences of negative feedback activation of mTORC1 through PI3-kinase and mTORC2 activity. Interestingly, cells insensitive to mTORC1 inhibition following AMPK activation retained sensitivity to the secondary effect of pemetrexed, apparently due to inhibition of lipid synthesis through phosphorylation of acetyl-CoA carboxylase by AMPK. We concluded that the growth inhibitory effect of pemetrexed following AMPK activation in human carcinoma cells was due to a combined effect of inhibition of mTORC1 signaling and lipogenesis, both of which were mediated by activation of AMPK. Somewhat surprisingly, several cell lines null for LKB1, the major upstream kinase of AMPK, retained sensitivity to the secondary effects of pemetrexed mediated through AMPK activation. This suggests that the effect of pemetrexed on AMPK activity will be preserved in tumors lacking LKB1, a common genotype of human NSCLC. Hence, pemetrexed exerts its effects on carcinoma cells by both inhibition of traditional antifolate targets and by a novel mechanism, activation of AMPK. (Supported in part by NIH Grant CA-27605)
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5086.
Abstract 5088: In vitro induction of a more aggressive prostate cancer phenotype by exposure to obese sera
Authors: Salcedo Ramona , Cavazos David , Hursting Stephen , Angel Rebecca De , deGraffenried Linda , Beeram Muralidhar 
Published: February 2011

Abstract
Prostate cancer continues to be the second-leading cause of cancer related deaths for men in the United States. Obesity is a known risk factor for the progression of prostate cancer. Studies have shown an association between obesity and chronic inflammation. Inflammation may contribute to prostate growth by promoting benign prostatic hyperplasia or inducing neoplastic changes. The mechanism(s) by which obesity promotes an aggressive prostate cancer is not fully understood. Investigating these mechanisms has been hampered by the lack of appropriate in vitro and in vivo model systems. Our main hypothesis is that obesity-induced chronic inflammation promotes metastatic prostate cancer through modulation of key signaling pathways, including NF-[[Unable to Display Character: &#312;]]B. Our first objective was to develop an appropriate in vitro model system to recapitulate the molecular events associated with obesity. In this current study, we obtained sera from obese and non-obese mice. Using an adipokine protein array 3 independent profiles were identified in obese mice sera that are consistent with metabolic obesity: metabolic syndrome, pro-metastatic and pro-inflammatory profile. We treated LNCaP prostate cancer cells with sera from obese and non-obese mice to determine physiological responses associated with an aggressive phenotype. We observed obese sera promoting invasion and increasing cell motility while having no effect on proliferation. In addition, obese mouse sera induced an EMT phenotype, evidenced by cytoplasmic dispersion of e-cadherin from cell-cell junctions and an increase in vimentin, which corresponded in greater tumor invasion. This study suggests that we can use an in vitro system to mimic the physiological changes in tumor biology induced by exposure to obese sera to investigate the molecular changes that induce a more aggressive phenotype.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5088.
Abstract 5093: Pseudomonas aeruginosa azurin secretion is stimulated by aldolase A from human malignant melanoma cells
Authors: Choi Juliana K. , Gupta Tapas K. Das 
Published: February 2011

Abstract
Recent reports have shown that Pseudomonas aeruginosa secrete increased levels of a redox protein, azurin, when co-cultured with human cancer cells. Previous data have demonstrated that azurin preferentially enters and induces cytotoxicity in several cancer cell lines; this same entry and cytotoxicity were not observed with normal cells. In the present study, P. aeruginosa, human malignant melanoma cells (Mel-2), and non-malignant melanocytes (CMN) were used as a model system to determine how P. aeruginosa distinguishes a cancer cell from a normal cell. P. aeruginosa were directly co-incubated with Mel-2 and CMN, and Western blot analyses were used to analyze levels of azurin secretion. A dose-dependent increase in azurin secretion was demonstrated upon co-incubation of P. aeruginosa and Mel-2, and azurin secretion was increased greater than 10-fold in the presence of Mel-2 compared to CMN. Also, real-time PCR assessment of azurin transcription demonstrated a 2-fold increase in azurin transcripts when P. aeruginosa were co-incubated with Mel-2. Next, a Transwell system was used in which P. aeruginosa and Mel-2 were co-incubated to allow secretion exchange but prevent physical contact. Using this system, it was demonstrated that azurin release is stimulated by soluble extracellular factors secreted by Mel-2 but not CMN. Using Coomassie staining and mass spectrometry techniques, aldolase A, a glycolytic enzyme upregulated in many cancer cells, was identified as a stimulating factor for azurin secretion. Cancer and normal cell line pairs of varying histogenesis were examined for basal aldolase A levels, and aldolase A was generally found to be elevated in cancer cell lines compared to their normal counterparts. These same cell line pairs were co-incubated with P. aeruginosa and azurin secretion directly correlated with aldolase A levels. The results suggest that secretion of azurin is, at least in part, mediated by aldolase A. In close proximity, P. aeruginosa may detect aldolase A in cancer cells and secrete azurin as a defense mechanism to induce cytotoxicity in Mel-2. Using P. aeruginosa, Mel-2 cells, and CMN cells as a model system, it was demonstrated that inherent differences between cancer cells and normal cells can be detected by bacteria and subsequently lead to a preferential interaction.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5093.
Abstract 5118: Rho/ROCK pathway mediates plasticity of scirrhous gastric carcinoma cell motility
Authors: Tasuku Matsuoka , Yashiro Masakazu , Kato Yukihiro , Shinto Osamu , Onoda Naoyoshi , Sawada Tetsuji , Nakata Bunzo , Ohira Masaichi , Hirakawa Kosei 
Published: February 2011

Abstract
The small guanosine triphosphatase (GTPase) Rho and its downstream effector Rho-associated kinase (ROCK) is one of a key mediator involved in controlling focal adhesions and the dynamics of actin stress fibers. This pathway has been shown to play important roles in the regulation of various cellular processes, such as cell shape changes and adhesion dynamics that drive migration. The underlying molecular mechanisms for the function of Rho/ROCK pathway leading to the development and progression in scirrhous gastric carcinoma cells have not been defined. We investigated the role of the Rho/ROCK pathway in the adhesion and invasion of gastric carcinoma cells, using a human scirrhous gastric cancer cell line, OCUM-2MD3. ROCK inhibitor, Y27632 significantly increased the adhesion of OCUM-2MD3 cells to the extracellular metrix (ECM) protein matrigel, but had no effect on attachment to polylysine. Further examination using ECM components showed enhanced binding ability was obtained only in laminin, but not in fibronectin, Type I collagen, and Type IV collagen. Reverse transcriptional (RT)-PCR analysis revealed that integrin subunits α3-integrin was clearly up-regulated by treatment with Y-27632 in OCUM-2MD3 cells, reflecting the specificity of ECM protein showing high adhesiveness property of gastric carcinoma cells. ROCK inhibitor also enhanced the invasion of OCUM-2MD3 cells through matrigel. The fact that Y27632 up-regulated the expression of membrane-type 1 matrix metalloproteinase by RT-PCR suggested the possibility that increased invasion ability of OCUM-2MD3 cells was related to proteolytic activity of extracellular matrices. Time-lapse microscopy showed conversion of OCUM-2MD3 cells from elongated to more round morphology with bleb in the presence of Y27632, suggesting that inhibition of Rho/ROCK pathway undergo a so-called ‘amoeboid to mesenchymal’ transition. Taken together, these data suggests that Rho/ROCK regulate plasticity of metastatic gastric carcinoma via mesenchymal-amoeboid transition, leading to clarify the specific progression of scirrhous gastric carcinoma.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5118.