bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 5095: Differential sensitivity to dietary restriction in xenograft models harboring PI3K pathway mutations in nude mice
Authors: Gulledge Travis , Blackwell Amber R. , Mullin Robert J. , Hollister Beth A. , Cheatham Lynn A.
Published: February 2011

The inhibitory effect of dietary restriction on the growth of human tumors has been well established. Recent evidence exploring the molecular mechanisms underlying this observation has been accumulating and supports a strong link with the PI3K/PTEN signaling pathway. Despite these recent advances, there remains a significant gap in our understanding of this observation. We have investigated the effects of dietary restriction on tumor growth in nude mouse xenografts of human tumor cell lines containing mutations in either PI3K or PTEN. In these experiments, dietary restriction was started after mean tumor size had reached between 60-100mg and continued until control groups reached endpoint (1000-2000mg). Diet restriction was achieved by feeding the experimental group a vitamin and nutrient enriched chow at a 20-40% reduction in overall amount relative to control groups. Our findings suggest that while activation of the PI3K/PTEN pathway may afford some resistance to dietary restriction, there may be other underlying mechanisms involved.

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 5095.
Abstract 5097: ITCH E3 ubiquitin ligase regulates LATS1 tumor suppressor stability
Authors: Ho King Ching , Yang Xiaolong
Published: February 2011

The Large Tumour Suppressor 1 (LATS1) is a serine/threonine kinase and tumour suppressor found downregulated in many human tumour types. Our lab and others previously revealed that LATS1 plays critical regulatory roles in various cancer development events, including cell proliferation, cell migration and apoptosis. However, despite such biological importance, relatively little is known regarding to how LATS1 is regulated at the molecular level. Through a recent binidng screen, we identified a HECT class E3 ubiqitin ligase ITCH (or API4) as a novel binding partner of LATS1. Further mapping showed that this interaction is particularly mediated through the PPxY (P, proline; x, any amino acids; Y, tyrosine) motifs of LATS1 and the WW domains of ITCH. Significantly, we found that ectopic expression of ITCH readily promotes downregulation of LATS1 proteins in a dose dependent manner and that this effect requries an intact ligase activity of ITCH. Further experiments also revealed that ITCH can promote in vivo polyubiquitination and subsequent degradation of LATS1 through the 26S proteasome pathway. Consistent with these results, stable shRNA knockdown of endogenous ITCH also causes upregulation of endogenous LATS1 in the MDA-MB-231 breast cancer cells, suggesting ITCH is a direct regulator of LATS1's protein stability. Together, our study provided convincing evidences demonstrating ITCH as the first negative regulator of the LATS1 tumour suppressor. Further elucidation of the effect of ITCH on LATS1's tumour suppressive activity may therefore shed light on our understanding of their roles in cancer development and therapy.

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 5097.
Abstract 5098: Targeting the cholesterol pathway gene SC4MOL sensitizes cancer to EGFR inhibitors
Authors: Sukhanova Anna L. , Bagnyukova Tetyana , Kratz Lisa E. , Kelley Richard I. , Serebriiskii Ilya G. , Weiner Louis M. , Golemis Erica A. , Astsaturov Igor A.
Published: February 2011

Epidermal growth factor receptor (EGFR) has been exploited as a target for blockade in cancer therapy, based on the known central role of EGFR signaling in promoting cancer cell growth. We have identified a novel mechanism for influencing EGFR activity that involves the sterol biosynthesis pathway enzyme sterol C4-methyl oxidase-like (SC4MOL). SC4MOL, in conjunction with other members of the ergosome complex (erg26/NSDHL; erg27/HSD17B7), catalyzes a non-redundant, irreversible step of demethylation at C4 of 14-demethylated lanosterol and dihydrolanosterol to produce zymosterol and 8(9)-cholestenol, respectively. Depletion of SC4MOL with siRNA caused accumulation of methylsterol intermediaries; inhibition of the key EGFR effectors, ERK and AKT; and a 3-fold increase in apoptosis specifically in the presence of EGFR antagonists. Metabolic block upstream of SC4MOL with ketoconazole or CYP51A1 siRNA eliminated methylsterols and completely reversed the effect of SC4MOL depletion, while added cholesterol did not rescue cancer cells from accelerated apoptosis upon concurrent SC4MOL and EGFR blockade. These results indicate that accumulation of specific cholesterol precursors enhances efficacy of anti-EGFR drugs. Further, we found that SC4MOL and the other ergosome components are transcriptionally regulated by EGFR signaling, suggesting involvement of C4 methylsterols in physiological activation of the EGFR signaling pathway.

A metabolic effect of sterol intermediaries on EGFR signaling has not been previously characterized. Such an effect could be exploited in cancer therapeutically by employing already existing drugs such as synthetic 4,4-dimethylsterols currently in use for in vitro fertilization.

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 5098.
Abstract 51: Blood pressure lowering medications disrupt fatty acid metabolism in pancreatic cancer
Authors: Sivarajah Maheshwaran , Lim SuhYueh , Chipitsyna Galina , Gong Qiaoke , Aziz Tamer , Witkiewicz Agnes , Yeo Charles J. , Arafat Hwyda A.
Published: February 2011

Despite the routine use of chemotherapy and radiotherapy, survival has not significantly improved in patients with pancreatic ductal adenocarcinoma (PDA), a situation that signifies the urgent need for novel therapeutic approaches. Angiotensin II (AngII), the principal hormone of the renin angiotensin system, is actively generated in the pancreas and has been suggested as a key mediator of PDA cell survival. Fatty acid synthase (FAS) is a key enzyme involved in synthesis of fatty acids and its high levels have been correlated with poor prognosis in many cancers. In this study, we investigated the potential molecular basis for the role of AngII in pancreatic carcinogenesis through studying its effect on FAS. AngII significantly increased the expression of FAS mRNA and protein in Panc-1 and PK9 PDA cells lines and induced FAS promoter activity. AngII-FAS mRNA induction was inhibited by an AngII type 1 receptor (AT1R) antagonist, losartan, and to a lesser extent by an AT2R antagonist. AngII activated the phosphorylation of ERK1/2, but not p38 or c-Jun NH2-terminal MAP kinases. Inhibition of ERK1/2 activation reduced the AngII-induced FAS synthesis. AngII activated the phosphorylation of AKT. Inhibition of AKT activation prevented the AngII-mediated increase of FAS. In human premalignant (n=6) and invasive PDA lesions (n=25), high expression levels of FAS correlated well with tumor stage and invasion status, and with high expression levels of angiotensin converting enzyme (ACE). Immunohistochemical staining of PDA serial sections show co localization of ACE with FAS in the malignant ducts and stromal cells. Oral administration of losartan significantly (p< 0.05) decreased the growth of PANC-1 and PK-9 cells xenografted on the flank of nude mice and significantly (p<0.05) reduced the expression of FAS mRNA and protein in the xenografts. Our data suggest a positive autocrine/paracrine action for the local pancreatic AngII generating system during pancreatic carcinogenesis, and provide the first insight into an AngII-initiated signal transduction pathway that regulates fatty acid metabolism and modulate lipogenesis in PDA. These results raise the possibility that AngII blockade therapies could be potential candidates in novel treatment strategies of PDA.

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 51.
Abstract 510: Intermittent hypoxia confers resistance to radiation in human neuroblastoma cells
Authors: Ezhilarasan Rave Sanker , Mohanam Indra , Rao Jasti S. , Mohanam Sanjeeva
Published: February 2011

Neuroblastoma, the most common extracranial solid tumor of children, arises from the sympathetic nervous system, is characterized by extensive genetic, morphologic, and clinical heterogeneity and presents as benign to highly aggressive forms in various stages. Hypoxia has been linked to tumor progression and increased malignancy. Like the most common malignant solid tumors, neuroblastomas contain zones of chronic or acute hypoxia reflecting poor oxygenation. Transient hypoxia and subsequent reoxygenation are common phenomena in solid tumors that greatly influence the outcome of therapies. Radiotherapy is commonly applied in higher stage neuroblastoma patients with MYCN oncogene amplification and metastases. The present study focuses how intermittent hypoxia modulates the effects of radiation treatment in human neuroblastoma cells. Intermittent hypoxia-conditioned cells were derived from human neuroblastoma cells that were exposed to 10 cycles of hypoxia and reoxygenation. Intermittent hypoxia stabilized the expression of HIF-l α in neuroblastoma cells. Cell survival to radiation treatment was assessed by the colony formation assay. The hypoxia-conditioned neuroblastoma cells exhibit increased survival to irradiation treatment compared with parental cells suggesting alterations in apoptotic pathways. The expression of selected genes associated with DNA damage as well as genes of BCL-2 family and caspase family were studied in parental and hypoxia-conditioned neuroblastoma cells in response to radiation treatment. Radiation caused an increase in the levels of proapoptotic proteins Bax, Bad, Bid and cleaved products of caspase-3 and −9 in parental tumor cells. Similar observations were not obtained in hypoxia-conditioned neuroblastoma cells upon radiation treatment demonstrating their increased radioresistance characteristics. We also assessed how hypoxia modulates radiation-induced in vitro angiogenesis. Human microvascular endothelial cells were exposed to conditioned medium from irradiated parental and irradiated hypoxia-conditioned tumor cells and capillary-like structure formation was studied. Further, tumor cell conditioned medium was also evaluated in chorioallantoic membrane assay for its angiogenic capabilities. These results suggest that intermittent hypoxia-conditioned neuroblastoma cells demonstrate increased survival, resistance to induction of apoptosis and angiogenic capabilities to radiation treatment.

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 510.
Abstract 5100: Expression of the insulin signaling related genes by infection of hepatitis C virus
Authors: Matsumura Takuya , Makino Reiko , Ito Kazuo , Imawari Michio , Kato Takanobu
Published: February 2011

BACKGROUND: Hepatitis C virus (HCV) induces chronic liver diseases such as chronic hepatitis, cirrhosis, and eventually hepatocellular carcinoma (HCC). Either molecular or clinical studies support a correlation between HCV infection and insulin resistance. Patients with chronic HCV infection have a significantly increased prevalence of type 2 diabetes mellitus compared to controls or HBV-infected patients. The HCV core protein is known to contribute to insulin resistance related steatosis, fibrosis, and carcinogenesis of the liver. Although several hypotheses have been demonstrated, a mechanism of insulin resistance by HCV infection is complex and still unclear. AIM: The aim of this study is to investigate the molecular mechanisms of liver injury by HCV through insulin signaling pathway. MATERIALS AND METHODS: HCV infected cultured cells and transgenic mice expressing HCV core gene were used for this study. A HCV strain JFH-1 replicates efficiently in cultured cells with production of infectious HCV. A transgenic mouse was established by introducing the core gene derived from the HCV genome of genotype 1b. Total RNA was extracted from the cells with and without HCV infection, and the livers of transgenic mice and their littermate wild type mice. The cDNA was synthesized from the RNA then applied to the real-time PCR. The relative amount of the mRNAs of 84 genes related to the insulin receptor and target genes for insulin signaling were compared between the cells or tissues with or without HCV. RESULTS and DISCUSSION: The expression of one of the insulin receptor substrate (IRS) family mRNA was increased in cells infecting HCV, compared to uninfected cells. On the other hand, the Akt mRNA expressed at higher level in the liver of transgenic mouse than that of normal littermate. The IRS family proteins are key mediators in insulin signaling and have been reported to associate with glucose metabolism. The Akt protein kinase is a critical regulator of human physiology that controls an impressive array of diverse cellular functions, including the modulation of growth, survival, proliferation and metabolism. The activation of Akt signaling may induce not only the insulin resistance but also the development of HCCs in the patients with HCV chronic infection. CONCLUSIONS: Our results indicates that the alteration of IRS family and Akt expression by HCV could be predictive for insulin resistance. Since the insulin resistance promotes inflammation and fibrogenesis in the liver, HCV infection leads to the development of liver cirrhosis and HCC by activation of insulin signaling.

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 5100.
Abstract 5105: Cyclosporin A and Cannabinoids induce autophagy-associated cell death in malignant glioma cells through inhibition of mTOR/S6K1 pathway
Authors: Ciechomska Iwona , Ellert-Miklaszewska Aleksandra , Kaminska Bozena
Published: February 2011

Malignant gliomas, the most common and aggressive primary brain tumors, account for more than 40% of all central nervous system (CNS) neoplasms. Gliomas are highly resistant to available therapies (radiation, chemiotherapy) that induce apoptosis (type I programmed cell death). Autophagy is a self-digestion process important for cell survival during starvation but functioning also as an alternative death mechanism under certain conditions (type II programmed cell death). Autophagy is negatively regulated by mammalian target of rapamycin (mTOR) and can be induced by its inhibitor, rapamycin. Using a panel of glioma cell lines bearing mutations in TP53 or PTEN we have demonstrated that cyclosporin A (CsA, an immunophilins/calcineurin inhibitor) and synthetic cannabinoids (counterparts of marijuana active ingredient THC) inhibit growth of glioma cells in vitro and induce cell death with apoptotic features. However, CsA- and cannabinoids-induced death was accompanied by the appearance of numerous cytoplasmic vacuoles, therefore, we investigated whether and to what extent autophagy contributes to drug-induced cell death of human malignant glioma cells. Upon CsA and cannabinoids treatment several features characteristic of autophagy were observed: formation of the acidic vesicular organelles, increase in punctuate GFP-LC3 (microtubule-associated protein light-chain 3) and LC3-II accumulation. All of the drugs affected mTOR signaling pathway in glioma cells decreasing phosphorylation of 4E-BP1 (eukariotic initiation factor 4E binding protein 1), p70-S6 kinase 1 and its downstream target molecule S6 ribosomal protein. Our results demonstrate that CsA and synthetic cannabinoids induce some features of apoptosis and autophagy-associated cell death in malignant glioma cells via inhibition of mTOR/S6K1 pathway. We are currently investigating the role of autophagy in dying cells using pharmacological and genetic inhibition of autophagy.

Studies supported by grant N N301 092036 from The Polish Ministry of Science and Higher Education.

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 5105.
Abstract 5106: Autophagy in malignant melanoma and breast carcinoma
Authors: Lazova Rossitza , Klump Vincent , Siddiqui Summar , Camp Robert , Pawelek John
Published: February 2011

We show here for the first time that autophagy is a remarkably common characteristic of malignant melanomas and breast carcinomas and is highly associated with metastasis and poor patient outcome. Autophagy is a cytoplasmic degradative process that in cancer can provide an energy source in times of nutrient deprivation. Interest in autophagy and cancer progression has increased markedly in recent years with reports that autophagy can be both a positive and negative survival factor for cancer cells. PURPOSE. The purpose of this study was to evaluate the prevalence of autophagy in melanoma and breast carcinoma, cancers from tissues of dissimilar lineages and functions. METHODS. Standard biopsies and tumor tissue microarrays containing core samples of melanoma (n = 342 cases) or breast carcinoma (n = 611 cases) were stained by immunohistochemistry for the autophagosome marker LC3B (microtuble-associated protein light chain 3B, detected with anti-LC3B polyclonal antibody ab48394, Abcam, Inc., Santa Cruz, CA). Autophagy was verified by the LC3B granular staining pattern and, in melanoma, by electron microscopy. RESULTS. In standard biopsies of melanoma, autophagic tumor cells emerged sporadically within the in situ tumor and were apparently the source of invasive cells in the dermis. For melanoma microarrays, 82% (107/130) of primary invasive melanomas and 90% (189/212) of lymph node metastases showed nearly uniform expression of autophagy with metastases showing increased LC3B staining intensity compared to primary tumors (p < 0.0001). Similar results were obtained for breast carcinoma microarrays where 73% (447/611) of primary tumors showed high levels of autophagy and this correlated with poor patient outcome (p < 0.001). Thus autophagy appears to be a constitutive metabolic state for a majority of malignant melanomas and breast carcinomas. The diverse origins and functions of these cells suggests that autophagy may be prevalent in other malignancies as well. Thus therapies targeting autophagy should be considered as a means to deprive cancer cells of an important energy source.

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 5106.
Abstract 5107: HDL and sphingosine-1-phosphate activate signal transducer and activator of transcription 3 in prostate cancer DU145 cells via ERK1/2 and S1P receptors
Authors: Sekine Yoshitaka , Suzuki Kazuhiro , Remaley Alan T.
Published: February 2011

(a) Introduction and Objective: Signal transducer and activator of transcription 3 (Stat3) has been implicated in the promotion of migration, invasion and growth of prostate cancer cells. Recently, HDL, which transports the bioactive lipid sphingosine-1-phosphate (S1P), was reported to activate Stat3 in cardiomyocytes and is a known mitogen for several cell types. S1P acts by binding to several G protein-coupled receptors, namely S1P1, S1P2 and S1P3, which are expressed in prostate cancer cell lines. Androgen deprivation therapy in men with prostate cancer leads to a significant increase of HDL-C, but the effect of HDL on prostate cancer is unknown. In this study, we examined the effect of HDL and S1P on Stat3 activation in prostate cancer cells and the involvement of ERK1/2, Akt, and S1P receptors in this process in 3 prostate cancer cell lines (PC-3, LNCaP and DU145). (b) Methods: We used HDL isolated from health volunteer men. Discordial reconstituted(r) HDL containing POPC and apoA-1, (POPC/A-1)rHDL or POPC, S1P and A-1, (POPC/S1P/A-1)rHDL were prepared by the cholate dialysis method. The phosphorylations of Stat3, ERK1/2 and Akt were detected by Western blot analysis. mRNA expressions of PC cells were evaluated by quantitative real-time PCR. Cell viability, migration and invasion were determined by MTS assay, would healing assay and matrigel invasion chamber assay, respectively. (c) Results: HDL increased a dose and a time dependent Ser727 phosphorylation of Stat3, but not Tyr705 in DU145 cells but not in the other two cell lines. S1P and (POPC/S1P/A-1)rHDL also induced the phosphorylation, but not rHDL made without S1P (POPC/A-1). They also induced DU145 cells proliferation, migration, invasion and phosphorylations of ERK1/2 and Akt. PD98059, a MEK inhibitor, and pertussis toxin, a Gi inhibitor, attenuated HDL-, S1P- and (POPC/S1P/A-1)rHDL-induced Stat3 phosphorylation, whereas LY294002, a PI3K inhibitor, had no effect. Concerning S1P receptors, S1P1 expression was much lower than S1P2 and S1P3 in DU145 cells. Both JTE013, a S1P2 antagonist, and VPC23019, a S1P1/S1P3 antagonist, attenuated HDL-, S1P- and (POPC/S1P/A-1)rHDL-induced Stat3 phosphorylations and cell migrations. (d) Conclusions: HDL was shown to induce Ser727 phosphorylation of Stat3 via its S1P constituent and involved both S1P2 and S1P3 receptors in DU145 cells. Moreover, ERK1/2 activation is involved in cell activation by HDL. These results suggest that the change in HDL plasma levels by androgen deprivation therapy HDL may alter prostate cancer growth and metastasis.

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 5107.
Abstract 5110: Gallic acid induces apoptosis and autophagy in bladder cancer cell
Authors: Lee Huei-Jane , Ou Ting-Tsz , Lee Yung-Shu , Wang Chau-Jong
Published: February 2011

Flavonoid phytochemicals were studied on prevention or therapy in human malignancies including bladder cancer. Here we detected the effect of gallic acid (GA) in human bladder transitional cell carcinoma (TCC, TSGH-8301 cells). In MTT assay, TSGH-8301 cells treated with 30 or 40 μM of GA showed significant decrease of cell viability to about 40 or 20 %. To examine whether the cell death involving apoptosis, we used DAPI stain to observe nuclear condensation and agarose gel electrophoresis to detect DNA fragmentation. GA can cause bladder cell apoptosis. Additionally, the results from flow cytometric analysis showed that GA induced late stage of apoptosis and represented a dose-dependent manner, accompanied by the decrease of Bcl2 and increase of Bax. We also used acridine orange stain and evaluated the expression of LC3, microtubule-associated protein 1 light chain 3, a marker of autophagy, to detect whether GA can induce autophagy in bladder cancer cell. The results showed that GA possesses the ability to induce autophagy in bladder cancer cell in a dose-dependent manner. In conclusion, these results revealed that GA can induce apoptosis and autophagy in human bladder cancer cells. It also implies GA possesses the potential to treat bladder cancer.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

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 5110.
Abstract 5111: Metformin suppresses azoxymethane-induced colorectal carcinogenesis via activating AMP-activated protein kinase
Authors: Hosono Kunihiro , Endo Hiroki , Takahashi Hirokazu , Nakajima Atsushi
Published: February 2011

Metformin is widely used in the treatment of diabetes mellitus. Previous epidemiological reports suggest metformin reduce cancer incidence. Adenosine monophosphate-activated protein kinase (AMPK) is known to be activated by metformin, and inhibit the mammalian target of rapamycin (mTOR) pathway. The mTOR pathway plays an important role for protein translational machinery and cell proliferation. We examined the effect of metformin on the suppression of colorectal carcinogenesis in chemical carcinogen-induced models. Seven-week-old BALB/c mice i.p. injected with azoxymethane (AOM, 10 mg/kg) were treated with metformin (250 mg/kg/day) or without, for 6 weeks (for aberrant crypt foci (ACF) formation) or for 32 weeks (for polyp formation). We investigated colonic epithelial proliferation using the bromodeoxyuridine (BrdU) and proliferating cell nuclear antigen (PCNA) labeling indices. Western blot analysis was performed to elucidate the mechanism which affected colorectal carcinogenesis. Furthermore, to examine the indirect effect of metformin, the status of insulin resistance and serum lipid levels were assessed. Treatment with metformin significantly reduced the colon polyp and ACF formation, but there was no significant difference in body weight or glucose concentration. BrdU and PCNA indices decreased in mice treated with metformin. Western blot analysis revealed that phosphorylated mTOR, S6 kinase and S6 protein levels significantly decreased in mice treated with metformin. In conclusion, Metformin suppressed colonic epithelial proliferation via inhibition of the mTOR pathway by activation of AMPK. Metformin is already used daily as an antidiabetic drug, so it may be a safer and promising candidate for the chemoprevention of colorectal cancer.

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 5111.
Abstract 5113: Filopodial actin machinery cooperates with microtubules and vimentin intermediate filaments in the elongation of invadopodia
Authors: Schoumacher Marie , Louvard Daniel , Vignjevic Danijela
Published: February 2011

Invasive cancer cells breach the basement membrane (BM) using specialized protrusions, called invadopodia. Here, we found that the crossing of a native BM is a three-stage process: invadopodia form and perforate the BM; elongate into mature invadopodia; and then guide the cell towards the stromal compartment. We have studied the remodeling of cytoskeleton networks during invadopodia formation and elongation using ultrastructural analysis, spatial distribution of molecular markers and RNAi silencing of protein expression. We show that formation of invadopodia requires only the actin cytoskeleton, both filopodia- and lamellipodia-associated proteins. On contrary, using a novel in vitro assay, we demonstrate that elongation of invadopodia is mostly dependent on filopodial actin machinery, microtubules and vimentin intermediate filaments. These findings indicate that invadopodia form by assembly of dendritic/diagonal and bundled actin networks and then maturate by elongation of actin bundles together with the infiltration of microtubules and vimentin intermediate filaments.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

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 5113.
Abstract 5114: SRC-1 Up-regulates Integrin α5 Expression and Enhances Breast Cancer Metastasis
Authors: Qin Li , Toneff Michael Joseph , Chen Xian , Wu Yelin , Li Yi , Xu Jianming
Published: February 2011

Steroid receptor coactivator-1 (SRC-1) is a member of the p160 SRC family, which also contains SRC-2 (TIF2/GRIP1) and SRC-3 (AIB1, p/CIP, ACTR, RAC3, TRAM-1). These molecules can interact with nuclear hormone receptors and certain other transcription factors to promote gene expression. In breast cancer, SRC-1 expression positively correlates with HER2 expression, disease recurrence and resistance to endocrine therapy. Our previous work has demonstrated that genetic ablation of SRC-1 in mice significantly suppresses breast cancer metastasis without affecting primary tumor initiation and growth in the MMTV-PyMT (polyoma middle T) mouse model. However, the mechanisms by which SRC-1 promotes breast cancer metastasis are unclear. To address the role of SRC-1 overexpression in breast cancer metastasis and mechanism, we generated MMTV-hSRC1 transgenic mice and found that MMTV-hSRC1 virgin mice exhibited normal mammary gland development. To take an advantage of the avian virus-mediated oncogene expression system, we crossed MMTV-hSRC1 mice to MMTV-tva mice and generated MMTV-hSRC1;MMTV-tva bi-transgenic mice. Intraductal injection of RCAS-PyMT avian viruses induced more metastasis in these bi-transgenic mice than in MMTV-tva mono-transgenic mice, suggesting that SRC-1 overexpression promotes lung metastasis. We also performed studies using MMTV-PyMT;SRC1−/− (KO) and MMTV-PyMT;SRC1+/+ (WT) cell lines derived from primary mouse mammary tumors. KO cells showed much lower migration and invasion capabilities than WT cells. KO cells also adhered much slowly to fibronectin and had reduced levels of active FAK, c-Src and Rac1. Mechanistic analyses revealed that SRC-1 was associated with a promoter region of integrin α5 with C/EBP and AP-1 binding sites and the integrin α5 gene might be a direct target of SRC-1. Accordingly, knockdown of integrin α5 in WT cells reduced cell adhesion and migration. Therefore, one of the pathways for SRC-1 to promote breast cancer cell migration and metastasis is to up-regulate integrin α5, leading to super activation of FAK, c-Src and Rac1. Our study provides a possibility to inhibit SRC-1-promoted breast cancer metastasis by targeting the integrin α5 function.

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 5114.
Abstract 5115: The role of Cdc42-interacting protein 4 (CIP4) in osteosarcoma tumorigenesis
Authors: Koshkina Nadezhda V. , Yang Ge , Kleinerman Eugenie S.
Published: February 2011

Osteosarcoma (OS) remains a devastating disease and requires better understanding of its biology for the development of novel therapeutic approaches. Tumor growth and metastases formation require an ability of cells to have a flexible cytoskeletal organization. Cdc42-interacting protein 4 (CIP4) is one of the scaffolding cytoskeleton-regulatory protein, whose role in tumors remains unknown. In the current study we investigated the role of CIP4 in OS tumorigenesis. We transfected highly aggressive mouse OS cells, DLM8 with the plasmid that downregulated expression of CIP4 protein (DLM8/shCIP4). We found that the growth rate of DLM8/shCIP4 clones was reduced by 30% when compared with non-transfected DLM8 cells or DLM8 cells transfected with control plasmid (DLM8/sh). When DLM8/shCIP4 cells were injected into mice subcutaneously they formed tumors that grew significantly slower than DLM8 or DLM8/sh control cells (p<0.02). We also found that inhibition of CIP4 expression in DLM8 cells decreased their motility and invasion properties in vitro, indicating on its ability to impair metastases growth. Fluorescent immunostaining for actin in DLM8/shCIP4 cells revealed lower perinuclear actin stress filaments formation and lower actin bridge to the lipid bilayer of the lipid cell membrane when compared with wild-type DLM8 or DLM8/sh. We also observed that downregulation of CIP4 changed cell membrane morphology in DLM8 cells - they had less protrusions and smoother cell surface than control cells. All these findings indicate that CIP4 may also play a role in metastatic behavior of OS cells and needs further investigation.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

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 5115.
Abstract 5116: p70 S6 kinase regulates the actin cytoskeleton in ovarian cancer cell motility by binding and cross-linking actin filaments
Authors: Ip Carman Ka Man , Wong Alice S. T.
Published: February 2011

p70 S6 kinase (p70S6K) is a downstream effector of phosphatidylinositol 3-kinase and is frequently activated in human ovarian cancer. Here we show for the first time that p70S6K functions in actin cytoskeleton reorganization responsible for the acquisition of invasiveness during tumor progression. Ectopic expression of active p70S6K in ovarian cancer cells induced dramatic reorganization of the actin cytoskeleton and promoted cell migration. Inhibition of p70S6K by siRNA or small molecule inhibitor resulted in diminished cell migration and actin cytoskeleton reorganization, confirming that these effects were p70S6K specific. By using cosedimentation and differential sedimentation assays, p70S6K was found to bind actin filaments, and was more effective in the presence than in the absence of phosphorylation. Importantly, purified p70S6K could be cosedimented with purified filamentous actin, indicating a direct association between p70S6K and actin. The response to p70S6K could be blocked with cytochalasin D, indicating that the binding of p70S6K to the cytoskeleton is mediated by actin. In addition, our results suggest that this is a functional interaction, because p70S6K was capable of generating specialized, actin-based cell morphologies via direct cross-linking activity. This bundling activity was confirmed by light scattering and electron microscopy. These results, in conjunction with our prior evidence that p70S6K regulates Rac and Cdc42 GTPases, suggest that p70S6K serves as an important regulator of the actin cytoskeleton, highlighting a role for p70S6K in the regulation of tumor progression and metastasis in ovarian cancer (This work is supported by Hong Kong Research Grants Council Grant HKU7599/05M to A.S.T.W.).

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 5116.
Abstract 5117: PKD1 suppresses filopodia formation and increases LIM Kinase 1 expression in prostate cancer cells
Authors: Biswas Md. Helal U. , Du Cheng , Zhang Chuanyou , Balaji K.C.
Published: February 2011

Introduction: We have previously demonstrated that transfection of PKD1 into highly metastatic C4-2 prostate cancer cells decreased cell motility. Filopodia are thin, actin-rich plasma-membrane protrusion that have an important role in cell motility and wound healing. Moreover, the initiation and elongation of filopodia depend on the precisely regulated polymerization, convergence and cross linking of actin filaments that are dynamically regulated by a variety of actin-binding proteins including Cofilin. However, Cofilin is inactivated by phosphorylation through the LIM kinase1 (LIMK1), a LIM-domain containing serine-threonine-tyrosine kinase, and activated by dephosphorylation through the Slingshot protein. In this study, we explored that PKD1 increased LIMK1 expression and suppressed filopodia formation with consequent effects on cell motility.

Methods: Phosphorylation of Cofilin as well as expression of GFP, PKD1-GFP and LIMK1 was confirmed by western blot analysis. Filopodia formation was detected by phalloidine staining. Wound healing assay was performed for evaluating the cell motility.

Results: To find out the role of PKD1 in LIMK1 regulation, we overexpressed PKD1 in PC3 cells followed by stimulation with phorbol 12-myristate 13-acetate (PMA) or Bryostatin-1, a PKD1 selective activator, and observed that the expression of LIMK1 was increased in dose dependent fashion compared to control. We also observed the phosphorylation of Cofilin was increased in PKD1 over expressing cells stimulated with PMA and Bryostatin-1 but not in control cells. Additionally, a number of filopodia were present in every GFP over expressing PC3 cells, whereas were completely absent in PKD1 over expressing PC3 cells. In addition, wound healing assay demonstrated that cell motility was suppressed by PKD1 over expression in PC cells compared to control.

Conclusions: Our data shows for first time that PKD1 modulates filopodia formation with increased expression of LIMK1 in PC cells. Additionally, we also found that PKD1 suppressed cell motility with regulation of Cofilin function that might play a role in suppression of metastasis. PKD1 suppressed filopodia formation by modulating LIMK1 expression a novel mechanism leading to altered motility in PC 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 5117.
Abstract 5119: Overexpression of EIF5A2 enhances cell motility and promotes HCC metastasis through Rho and Rac signaling pathways
Authors: Dong Sui-Sui , Tang Dong-Jiang , Ma Ning-Fang , Fu Li , Chen Leilei , Guan Xin-Yuan
Published: February 2011

Hepatocellular carcinoma is characterized by its high incidence of tumor recurrence and metastasis; however, the underlying molecular mechanisms are largely unknown. In the present study, a novel metastasis-related gene, EIF5A2, was characterized for its role in HCC metastasis and underlying molecular mechanism. Overexpression of EIF5A2 mRNA was detected in 50/81(61.7%) of HCCs, which was significantly higher than those in nontumorous liver tissues. Compared with matched primary HCC, higher expression of EIF5A2 protein was observed in 25/47 (53.2%) metastatic tumors. In vitro assays showed that ectopic expression of EIF5A2 could enhance cancer cell migration and invasion, and experimental mouse model demonstrated that over expression of EIF5A2 promoted tumor metastasis in vivo. Moreover, inhibition of EIF5A2 by siRNA or deoxyhypusine synthase (DHPS) inhibitor GC7, which inhibits EIF5A2 maturation, could effectively decrease cell motility. Further study found that EIF5A2 could activate RhoA/Rac1 to stimulate the formation of stress fiber and lamellipodia. The rearrangement of cytoskeleton further induced epithelial-mesenchymal transition (EMT), a key event in tumor invasion and metastasis, characterized by downregulation of epithelial markers (E-cadherin and β-catenin) and upregulation of mesenchymal markers (fibronectin, N-cadherin, α-SMA and vimentin). Moreover, the activation of Rho GPases by overexpression of EIF5A2 also influenced cell cycle progression. Conclusions: EIF5A2 promotes HCC invasion and metastasis by stimulating cytoskeleton rearrangement through activation of RhoA and Rac1.

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 5119.
Abstract 5123: 1,25D3 regulates cell-matrix and cell-cell adhesion and reduces experimental metastasis in a squamous cell carcinoma model system
Authors: Ma Yingyu , Su Bing , Yu Wei-Dong , Seshadri Mukund , Turowski Steven G. , Kong Rui-Xian , Gillard Bryan M. , Trump Donald L. , Johnson Candace S.
Published: February 2011

1,25D3, the most active vitamin D metabolite, has broad spectrum anti-tumor activity. We demonstrated that 1,25D3 affects squamous cell carcinoma (SCC) cell adhesion to extracellular matrix and inhibits cell motility, markers of metastasis. In this study, we extended these observations. In situ zymography assay revealed that 1,25D3 strongly suppressed the ability of SCC cells to degrade gelatin. 1,25D3 reduced the adhesion of SCC cells to laminin, and by flow cytometry, the expression of the laminin receptors integrin α6 and β4. 1,25D3 promoted the activation of focal adhesion kinase (FAK) and the formation of focal adhesion as shown by immunofluorescence. To study the effects of 1,25D3 on cell-cell adhesion, the expression level of cadherins were examined by flow cytometry. 1,25D3 enhanced the expression of E-cadherin and R-cadherin, but did not alter that of N-cadherin. Of note, a 1,25D3-resistant variant of SCC (SCC-DR) was developed and these findings were not observed in SCC-DR cells. To investigate the in vivo effect of 1,25D3, C3H/HeJ mice were injected i.v. into tail vein with 104 SCC cells, and then half of the mice received 0.625 μg of 1,25D3 i.p. daily for 3 days while the other half received saline. Treatment with 1,25D3 dramatically inhibited the development of pulmonary tumor formation, as assessed by MRI analysis and colony counts. Our study suggests that 1,25D3 suppresses SCC metastasis, possibly through the promotion of E-cadherin-mediated cell-cell adhesion and the inhibition of cell motility and invasion.

This study was supported by NIH/NCI grants CA067267, CA095045 and CA085142.

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 5123.
Abstract 5135: Breast cancer antiestrogen resistance-3 influences breast cancer cell migration by regulating Rac and Rho GTPase signaling
Authors: Schrecengost Randy S. , Wilson Ashley L. , Guerrero Michael S. , Bouton Amy H.
Published: February 2011

Breast Cancer Antiestrogen Resistance-3 (BCAR3) was initially identified as a gene whose expression confers resistance to endocrine therapy, such as the antiestrogen tamoxifen. However, work from our group as well as others implicate BCAR3 as a prominent regulator of cell migration and invasion. This is of interest because expression of BCAR3 is elevated in more aggressive breast cancer cell lines. In this study, we have taken both a gain-of-function and loss-of-function approach to determine the mechanism by which BCAR3 regulates cell migration and invasion. We found that overexpression of BCAR3 in less aggressive breast cancer cells resulted in enhanced cell migration and increased protrusive activity. Additionally, BCAR3 was co-localized at the cell membrane with an established scaffold protein, p130Cas (also known as BCAR1 or Cas). Conversely, siRNA-mediated depletion of BCAR3 in more aggressive breast cancer cells inhibited cell migration and decreased membrane protrusiveness, coincident with a significant reduction in Rac GTPase activity. This was accompanied by mislocalization of Cas and a decrease in Cas tyrosine phosphorylation. Loss of BCAR3 was also associated with stabilization of stress fibers, reduced adhesion turnover, and increased ROCK-dependent phosphorylation of myosin light chain, a major downstream target of Rho GTPase. Inhibition of ROCK in BCAR3-depleted cells disrupted stress fibers and restored membrane protrusions, confirming and indicating that the effect of BCAR3 depletion on stress fiber dynamics was dependent on ROCK. Furthermore, Cas localization to the cell periphery was restored and partial rescue of Cas tyrosine phosphorylation was observed. Taken together, these results suggest a model whereby BCAR3 expression influences cell migration and invasion by promoting Cas phosphorylation and Cas-mediated Rac activation, while negatively regulating Rho-mediated contractility. While the major mechanisms of BCAR3 as a critical regulator of breast cancer cell migration are addressed here, future studies will determine whether elevated BCAR3 expression promotes metastasis in animal models and is associated with clinical outcome in patients.

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 5135.
Abstract 5140: Rsu1 and the IPP adhesion complex can regulate adhesion and migration in glioma cell lines
Authors: Buckingham John , Gonzalez-Nieves Reyda , Cutler Mary L.
Published: February 2011

One hallmark of high grade glioblastoma is invasive growth that is dependent on ability of the tumor cells to migrate from the tumor into surrounding brain tissue thus preventing complete surgical resection. Rsu1, a member of the Integrin Linked Kinase-PINCH1-Parvin (IPP) cell adhesion complex, is encoded by a gene on human chromosome 10p13 in a region frequently deleted in high grade gliomas. Previous studies from our lab demonstrated that ectopic expression of Rsu1 in a human glioma cell line inhibited the tumorigenicity of the cells. The current study addresses the effect of Rsu1 on adhesion and migration in human glioma cell lines. The results with stable Rsu1 transfectants in the U87 glioma cell line indicate that Rsu1 expression results in enlarged cells with increased filapodial extensions and an increase in the number of focal adhesions. This phenotype correlates with increased cell adhesion and 30-50% decreased cell migration in Boyden chamber assays using PDGF, TPA or HGF as inducers of migration. siRNA-mediated depletion of Rsu1 concomitantly reduces the level of other IPP proteins, particularly the Rsu1 binding protein PINCH1. This loss of cell adhesion proteins reduces adhesion and enhances in vitro migration of highly oncogenic tumor cells. Infection of U87 and U251 glioma cell lines or immortalized human astrocytes and their Ras-transformed counterparts with adenovirus encoding Rsu1 decreased or eliminated phosphorylation of Akt on serine 473 compared to control vector. This finding and previous work demonstrating that signaling through the JNK pathway can be influenced by Rsu1 and PINCH11,2,3 suggest that both JNK and PI-3-kinase pathways are regulated by Rsu1 to limit cell migration. These studies identify deletion of Rsu1 as a mechanism that inhibits the IPP complex -induced adhesion as a potential mediator of the migratory behavior of high grade gliomas exhibiting chromosome 10 loss or 10p13 deletion.

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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 5140.