bluuebunny/crossref_metadata_2025_split huggingface dataset:
Farnesyltransferase inhibitors reverse altered growth and distribution of actin filaments inTsc-deficient cells via inhibition of both rapamycin-sensitive and -insensitive pathways
Authors: Gau Chia-Ling , Kato-Stankiewicz Juran , Jiang Chen , Miyamoto Susie , Guo Lea , Tamanoi Fuyuhiko 
Published: September 2005

AbstractFarnesyltransferase inhibitors (FTI) have been developed as anticancer drugs and are currently being evaluated in clinical trials. In this study, we have examined the effects of FTIs on Tsc-null cells to gain insight into their effects on farnesylated Rheb GTPase. This protein is involved in the activation of mTOR/S6K signaling and is down-regulated by the Tsc1/Tsc2 complex. Both Tsc1−/− and Tsc2−/− mouse embryonic fibroblasts exhibit constitutive activation of S6K and grow in the absence of serum. Two different FTI compounds, the clinical compound BMS-214662 and the newly described BMS-225975, inhibit the constitutive activation of mTOR/S6K signaling and block serum-free growth of the Tsc-null mouse embryonic fibroblasts. We have also found that Tsc-null mouse embryonic fibroblasts grow under anchorage-independent conditions and that both FTI compounds inhibit this soft agar growth. These FTI effects are similar to those observed with rapamycin. Another interesting phenotype of Tsc-null mouse embryonic fibroblasts is that they are round and contain actin filaments predominantly at the cell periphery. The addition of FTIs, but not rapamycin, led to the reappearance of intracellular actin filaments and reduction of peripheral actin filaments. The ability of FTI to rearrange actin filaments seems to be largely mediated by the inhibition of Rheb protein, as induction of intracellular actin filaments by FTI was much less efficient in Tsc2-null cells expressing Rheb (M184L), a geranylgeranylated mutant Rheb that can bypass farnesylation. These results reveal that FTIs inhibit Rheb, causing two different effects in Tsc-deficient cells, one on growth and the other on actin filament distribution.
Validation of in vivo pharmacodynamic activity of a novel PDGF receptor tyrosine kinase inhibitor using immunohistochemistry and quantitative image analysis
Authors: D'Andrea Michael R. , Mei Jay M. , Tuman Robert W. , Galemmo Robert A. , Johnson Dana L. 
Published: September 2005

Abstract
With the advent of agents directed against specific molecular targets in drug discovery, it has become imperative to show a compound's cellular impact on the intended biomolecule in vivo. The objective of the present study was to determine if we could develop an assay to validate the in vivo effects of a compound. Hence, we investigated the in vivo pharmacodynamic activity of JNJ-10198409, a relatively selective inhibitor of platelet-derived growth factor receptor tyrosine kinase (PDGF-RTK), in tumor tissues after administering the compound orally in a nude mouse xenograft model of human LoVo colon cancer. We developed a novel assay to quantify the in vivo anti-PDGF-RTK activity of the inhibitor in tumor tissue by determining the phosphorylation status of phospholipase Cγ1 (PLCγ1), a key downstream cellular molecule in the PDGF-RTK signaling cascade. We used two antibodies, one specific for the total (phosphorylated and unphosphorylated forms) PLCγ1 (pan-PLCγ1) and the other, specific for phosphorylated form of PLCγ1 (ph-PLCγ1) to immunohistochemically detect their expression in tumor tissues. Computer-assisted image analysis was then used to directly compare the ratio of ph-PLCγ1 to pan-PLCγ1 immunolabeling intensities in serial sections (5 μm) of tumors obtained from vehicle- and JNJ-10198409-treated tumor-bearing mice. Our data showed statistically significant, dose-dependent differences in the ph-PLC/pan-PLC ratio among the four treatment groups (vehicle, 25, 50, and 100 mg/kg b.i.d.). These results confirmed this compound's ability to suppress PDGF-RTK downstream signaling in tumor tissues in vivo. In addition to this specific application of this in vivo validation approach to those targets that use PLCγ as a downstream signaling partner, these methods may also benefit other drug discovery targets.
Potent and selective inhibitors of Akt kinases slow the progress of tumors in vivo
Authors: Luo Yan , Shoemaker Alexander R. , Liu Xuesong , Woods Keith W. , Thomas Sheela A. , de Jong Ron , Han Edward K. , Li Tongmei , Stoll Vincent S. , Powlas Jessica A. , Oleksijew Anatol , Mitten Michael J. , Shi Yan , Guan Ran , McGonigal Thomas P. , Klinghofer Vered , Johnson Eric F. , Leverson Joel D. , Bouska Jennifer J. , Mamo Mulugeta , Smith Richard A. , Gramling-Evans Emily E. , Zinker Bradley A. , Mika Amanda K. , Nguyen Phong T. , Oltersdorf Tilman , Rosenberg Saul H. , Li Qun , Giranda Vincent L. 
Published: September 2005

Abstract
The Akt kinases are central nodes in signal transduction pathways that are important for cellular transformation and tumor progression. We report the development of a series of potent and selective indazole-pyridine based Akt inhibitors. These compounds, exemplified by A-443654 (Ki = 160 pmol/L versus Akt1), inhibit Akt-dependent signal transduction in cells and in vivo in a dose-responsive manner. In vivo, the Akt inhibitors slow the progression of tumors when used as monotherapy or in combination with paclitaxel or rapamycin. Tumor growth inhibition was observed during the dosing interval, and the tumors regrew when compound administration was ceased. The therapeutic window for these compounds is narrow. Efficacy is achieved at doses ∼2-fold lower than the maximally tolerated doses. Consistent with data from knockout animals, the Akt inhibitors induce an increase in insulin secretion. They also induce a reactive increase in Akt phosphorylation. Other toxicities observed, including malaise and weight loss, are consistent with abnormalities in glucose metabolism. These data show that direct Akt inhibition may be useful in cancer therapy, but significant metabolic toxicities are likely dose limiting.
Selective and irreversible cell cycle inhibition by diphenyleneiodonium
Authors: Scaife Robin M. 
Published: September 2005

Abstract
Because cell proliferation is subject to checkpoint-mediated regulation of the cell cycle, pharmacophores that target cell cycle checkpoints have been used clinically to treat human hyperproliferative disorders. It is shown here that the flavoprotein inhibitor diphenyleneiodionium can block cell proliferation by targeting of cell cycle checkpoints. Brief exposure of mitotically arrested cells to diphenyleneiodonium induces a loss of the mitotic cell morphology, and this corresponds with a decrease in the levels of the mitotic markers MPM2 and phospho-histone H3, as well as a loss of centrosome maturation, spindle disassembly, and redistribution of the chromatin remodeling helicase ATRX. Surprisingly, this mitotic exit resulted in a tetraploidization that persisted long after drug release. Analogously, brief exposure to diphenyleneiodonium also caused prolonged arrest in G1 phase. By contrast, diphenyleneiodonium exposure did not abrogate S phase, although it did result in a subsequent block of G2 cell cycle progression. This indicates that diphenyleneiodonium selectively targets components of the cell cycle, thereby either causing cell cycle arrest, or checkpoint override followed by cell cycle arrest. These irreversible effects of diphenyleneiodonium on the cell cycle may underlie its potent antiproliferative activity.
The selective retinoid X receptor agonist bexarotene (LGD1069, Targretin) prevents and overcomes multidrug resistance in advanced breast carcinoma
Authors: Yen Wan-Ching , Lamph William W. 
Published: September 2005

Abstract
Acquired drug resistance represents a major challenge in the therapeutic management of breast cancer patients. We reported previously that the retinoid X receptor–selective agonist bexarotene (LGD1069, Targretin) was efficacious in treating animal models of tamoxifen-resistant breast cancer. The goal of this study was to evaluate the effect of bexarotene on development of acquired drug resistance and its role in overcoming acquired drug resistance in advanced breast cancer. Paclitaxel, doxorubicin, and cisplatin were chosen as model compounds to determine the effect of bexarotene on the development of acquired drug resistance. Human breast cancer cells MDA-MB-231 were repeatedly treated in culture with a given therapeutic agent with or without bexarotene for 3 months. Thereafter, cells were isolated and characterized for their drug sensitivity. Compared with parental cells, cells treated with a single therapeutic agent became resistant to the therapeutic agent, whereas cells treated with the bexarotene combination remained chemosensitive. Cells with acquired drug resistance, when treated with the combination, showed increased sensitivity to the cytotoxic agent. Furthermore, cells treated with the combination regimen had reduced invasiveness and angiogenic potential than their resistant counterparts. These in vitro findings were further confirmed in an in vivo MDA-MB-231 xenograft model. Our results suggest a role for bexarotene in combination with chemotherapeutic agents in prevention and overcoming acquired drug resistance in advanced breast carcinoma.
Overexpression of hRFI (human ring finger homologous to inhibitor of apoptosis protein type) inhibits death receptor–mediated apoptosis in colorectal cancer cells
Authors: Konishi Tsuyoshi , Sasaki Shin , Watanabe Toshiaki , Kitayama Joji , Nagawa Hirokazu 
Published: September 2005

Abstract
The acquisition of antiapoptotic properties is one of the essential mechanistic steps in colorectal carcinogenesis and is closely correlated with a loss of chemosensitivity and radiosensitivity. Human ring finger homologous to inhibitor of apoptosis protein type (hRFI) is a newly discovered gene encoding a ring finger domain highly homologous to that of X chromosome–linked inhibitor of apoptosis protein. Immunohistochemistry has revealed that the expression of hRFI increased in transition from normal colorectal mucosas to adenomas and from adenomas to carcinomas, suggesting an essential role in the early stage of colorectal carcinogenesis. However, the function role of hRFI in colorectal carcinoma has not been elucidated. To determine whether hRFI possesses an antiapoptotic function in colorectal cancer cells, HCT116 colorectal cancer cells stably overexpressing hRFI were established. The hRFI transfectant exhibited significant resistance to apoptosis induced by tumor necrosis factor-α or tumor necrosis factor–related apoptosis-inducing ligand compared with control. This antiapoptotic response was associated with decreased activity of caspase-3, -8, and -9. We also established an antisense down-regulation of hRFI, which effectively reversed the antiapoptotic activity of the hRFI transfectant. This confirmed that the antiapoptotic property of the hRFI transfectant was not due to the clonal effect but in fact dependent on hRFI function. In conclusion, hRFI possesses an antiapoptotic function in HCT116 colorectal cancer cells. Considering the progressive increase of hRFI expression in the advance of the colorectal adenoma-carcinoma sequence, hRFI is one of the important players in colorectal carcinogenesis through its effect on apoptosis regulation.
A highly epothilone B–resistant A549 cell line with mutations in tubulin that confer drug dependence
Authors: Yang Chia-Ping Huang , Verdier-Pinard Pascal , Wang Fang , Lippaine-Horvath Eva , He Lifeng , Li Dansu , Höfle Gerhard , Ojima Iwao , Orr George A. , Horwitz Susan Band 
Published: September 2005

Abstract
A 95-fold epothilone B (EpoB)–resistant, but not dependent, A549 human lung carcinoma cell line, A549.EpoB40 (EpoB40), has a Gln to Glu mutation at residue 292 that is situated near the M-loop of βI-tubulin. Further selection of this cell line with higher concentrations of EpoB produced A549.EpoB480 (EpoB480), which is ∼900-fold resistant to EpoB. This cell line, like EpoB40, exhibits cross-resistance to Taxol and extreme sensitivity to vinblastine, but in contrast to EpoB40 it is unusually dependent on EpoB, requiring a minimum of 125 nmol/L EpoB to maintain normal growth. Sequence analysis of the β-tubulin and Kα1-tubulin genes in EpoB480 showed that, in addition to the β292 mutation, β60 was mutated from Val to Phe and α195 was mutated from Leu to Met. Mass spectrometry indicated that both the Val60Phe and Leu195Met mutations in βI- and Kα1-tubulin, respectively, were expressed at the protein level. Molecular modeling indicated that β60 is located at the end of the H1-S2 loop that has been implicated as a principal partner of the M-loop for contacts between protofilaments. A mutation at β60 could inhibit the lateral contacts between protofilaments, thereby destabilizing microtubules. α195 is located at the external surface of the microtubule that has been proposed as the domain that interacts with a variety of endogenous proteins, such as stathmin and microtubule-associated protein 4. A mutation at α195 could modulate the interactions between tubulin and regulatory proteins. We propose that the βVal60Phe mutation plays a critical role in the drug-dependent phenotype of EpoB480 cells.
Identification of novel targeting peptides for human ovarian cancer cells using “one-bead one-compound” combinatorial libraries
Authors: Aina Olulanu H. , Marik Jan , Liu Ruiwu , Lau Derick H. , Lam Kit S. 
Published: September 2005

AbstractUsing “one-bead one-compound” combinatorial chemistry technology, we generated random peptide libraries containing millions of 90 μm TentaGel beads, each with its own unique amino acid sequence. A cyclic random 8-mer library was screened with CAOV-3 (a human ovarian adenocarcinoma cell line) and beads with a unique ligand that bind to the cell surface receptors were coated by one or more layers of cells. These positive beads were isolated, stripped, and microsequenced. Several peptide motifs were identified from these screenings, some of which were novel and unique, e.g., cDGX4GX6X7c. Structure-activity relationship studies of this peptide revealed that the l-aspartate residue at position 2, the two glycines at positions 3 and 5, and the two d-cysteines at the amino and COOH terminus are critical for activity. In addition, a hydrophobic residue was preferred at position X4, whereas amino acids at positions X6 and X7 were more variable. Binding of this peptide to a number of different cancer cell lines and normal cells was also determined and we observed that peptides with this motif bound preferentially to three other human ovarian cancer cell lines (ES-2, SKOV-3, and OVCAR-3) as well as a human glioblastoma cancer cell line (A172). Structural analysis of the peptides using high-resolution nuclear magnetic resonance spectroscopy revealed strong conformational similarity among all peptides with cX1GX4GX6X7c motif. Blocking study with a panel of anti-integrin antibodies strongly suggests α3 integrin present on these ovarian adenocarcinoma cells is the target receptor for this peptide.
p37 induces tumor invasiveness
Authors: Ketcham Catherine M. , Anai Satoshi , Reutzel Robbie , Sheng Shijie , Schuster Sheldon M. , Brenes Ryan B. , Agbandje-McKenna Mavis , McKenna Robert , Rosser Charles J. , Boehlein Susan K. 
Published: September 2005

Abstract
Previous studies have shown a statistically significant correlation between human carcinomas and monoclonal antibody detection of a Mycoplasma hyorhinis–encoded protein known as p37. A potential mechanism of p37 is that it might promote invasion and metastasis. Recombinant p37 enhanced the invasiveness of two prostate carcinoma and two melanoma cell lines in a dose-dependent manner in vitro, but did not have a significant effect on tumor cell growth. Furthermore, the increased binding to cell surfaces and the enhanced invasive potential of cancer cells from exposure to p37 could be completely reversed by preincubation of the cancer cells with an anti-p37 monoclonal antibody. Sequence comparisons, followed by three-dimensional molecular modeling, revealed a region of similarity between p37 and influenza hemagglutinin A, a sialic acid–binding protein that plays a critical role in viral entry. Binding of p37 to prostate carcinoma cells was found to be at least partially sialic acid dependent because neuraminidase treatment decreased this binding. Taken together, these observations suggest that M. hyorhinis can infect humans and may facilitate tumor invasiveness via p37. These results further suggest that p37 may be a molecular target for cancer therapy.
Mitochondria are the primary target in isothiocyanate-induced apoptosis in human bladder cancer cells
Authors: Tang Li , Zhang Yuesheng 
Published: September 2005

Abstract
Many isothiocysanates (ITC) are promising cancer-preventive agents, and induction of apoptosis is one of their underlying mechanisms of action. We recently found that caspase-9 was preferentially activated over other initiator caspases in human bladder cancer UM-UC-3 cells. We report here that caspase-9 activation is the major step leading to ITC-induced apoptosis in this cell line. More importantly, our results show that caspase-9 activation by the ITCs may result primarily from mitochondrial damage. Four common naturally occurring ITCs were studied, including allyl ITC, benzyl ITC (BITC), phenethyl ITC (PEITC), and sulforaphane. BITC and PEITC showed more potent mitochondria-damaging ability than the other two ITCs, correlating well with their stronger apoptosis-inducing potentials. Furthermore, BITC and PEITC damaged both the outer and inner mitochondrial membranes. Use of isolated mitochondria allowed us to establish that ITCs, and more importantly their major intracellular derivatives (glutathione conjugates) at concentrations that are readily achievable in cells, damage mitochondria, leading to the collapse of mitochondrial trans-membrane potential and release of cytochrome c. The mitochondria-damaging potencies of the ITCs correlate well with their lipophilicities. Bcl-2 family members are known to influence the stability of mitochondrial membrane. Our results show that the ITCs caused phosphorylation of Bcl-2, induced mitochondrial translocation of Bak, and disrupted the association of Bcl-xl with both Bak and Bax in mitochondrial membrane, indicating that ITC-induced mitochondrial damage results at least in part from modulation of select Bcl-2 family members.
Multidrug-resistant neuroblastoma cells are responsive to arsenic trioxide at both normoxia and hypoxia
Authors: Karlsson Jenny , Edsjö Anders , Påhlman Sven , Pettersson Helen M. 
Published: September 2005

Abstract
Despite intensive treatment, the outcome of high-risk neuroblastoma patients is poor with acquired multidrug resistance as an important cause. Previously, our group has shown that arsenic trioxide (As2O3) kills multidrug-resistant neuroblastoma cells in vitro and in vivo at clinically tolerable doses. Regions of tissue hypoxia often arise in aggressive solid tumors, and hypoxic tumors exhibit augmented invasiveness and metastatic ability in several malignancies. Furthermore, hypoxia may impair the treatment efficiency; therefore, we have studied the cytotoxic effect of As2O3 on neuroblastoma cells grown under normoxic as well as hypoxic (1% oxygen) conditions. At both normoxia and hypoxia, 2 and 4 μmol/L As2O3 induced evident cell death in the drug-sensitive SH-SY5Y and IMR-32 cells as well as in the multidrug-resistant SK-N-BE(2)c (with a mutated p53) and SK-N-FI cells after 72 hours of exposure. In contrast, the conventional chemotherapeutic drug etoposide showed lowered efficiency in hypoxic IMR-32 cells. In accordance with our previously published results, although not to the same extent as in their normoxic counterparts, Bax is proteolytically cleaved also in neuroblastoma cells exposed to As2O3 at hypoxia. This suggests that similar molecular mechanisms are involved in As2O3-induced neuroblastoma cell death during hypoxia compared with normoxia. Together, our results support As2O3 as a potential candidate drug as a complement to conventional treatments for high-risk neuroblastoma patients and perhaps also for patients with other multidrug-resistant solid tumors.
Inhibition of insulin-like growth factor-I receptor (IGF-IR) signaling and tumor cell growth by a fully human neutralizing anti–IGF-IR antibody
Authors: Wang Yan , Hailey Judith , Williams Denise , Wang Yaolin , Lipari Philip , Malkowski Michael , Wang Xiaoying , Xie Lei , Li Guanghua , Saha Deba , Ling Wai Lam W. , Cannon-Carlson Susan , Greenberg Robert , Ramos Robert A. , Shields Robert , Presta Leonard , Brams Peter , Bishop W. Robert , Pachter Jonathan A. 
Published: September 2005

AbstractInsulin-like growth factor-I receptor (IGF-IR) plays an important role in tumor cell growth and survival. On ligand stimulation, IGF-IR, a receptor tyrosine kinase, phosphorylates tyrosine residues on two major substrates, IRS-1 and Shc, which subsequently signal through the Ras/mitogen-activated protein kinase and phosphatidylinositol 3-kinase/AKT pathways. Here, we describe the characterization of a fully human anti–IGF-IR monoclonal antibody 19D12 that inhibits IGF binding and autophosphorylation of both IGF-IR/IGF-IR homodimers and IGF-IR/insulin receptor heterodimers. 19D12 does not recognize insulin receptor homodimers. In addition to inhibiting IGF-IR autophosphorylation, 19D12 also inhibits IRS-1 phosphorylation and activation of the major downstream signaling molecules AKT and extracellular signal-regulated kinase 1/2. Furthermore, the antibody down-regulates the total IGF-IR protein level and can exhibit antibody-dependent cellular cytotoxicity activity against a non–small cell adenocarcinoma cell line in vitro in the presence of isolated human natural killer cells. 19D12 binds tightly to the receptor, with an affinity of 3.8 pmol/L as measured by KinExA. In cell culture, 19D12 inhibits proliferation and soft agar growth of various tumor cell lines. In vivo, 19D12 inhibits the tumor growth of a very aggressive human ovarian tumor xenograft model A2780. These data support the development of this anti–IGF-IR monoclonal antibody as a promising anticancer agent.
Low-dose cisplatin protects human neuroblastoma SH-SY5Y cells from paclitaxel-induced apoptosis
Authors: Villa Daniela , Miloso Mariarosaria , Nicolini Gabriella , Rigolio Roberta , Villa Antonello , Cavaletti Guido , Tredici Giovanni 
Published: September 2005

Abstract
Combined anticancer therapy using platinum compounds and antitubulins has increased the risk of neurotoxicity. However, the combination of low-dose cisplatin (CDDP) with toxic doses of paclitaxel significantly reduces cellular death in a human neuroblastoma SH-SY5Y cell line. To analyze the mechanisms of this protection, we evaluated various signaling molecules possibly involved in apoptosis and some relevant cell cycle regulatory proteins. CDDP does not interfere with the tubulin-stabilizing action of paclitaxel. The evaluation of molecular pathways involved in apoptosis indicates that the Bcl-2 but not the caspases may be involved in the CDDP protection of paclitaxel-induced apoptosis. The increase in p53 protein and its nuclear accumulation suggests a possible involvement of p53 in CDDP protection. The use of the chemical inhibitor of p53, pifithrin α, excluded this possibility. The study of cyclins and the flow cytometric analysis (fluorescence-activated cell sorting) suggest that CDDP exerts a protective action by blocking cells early in the cell cycle. The determination of the mitotic index indicates that CDDP prevents cells from reaching the mitosis. We concluded that low doses of CDDP are protective against toxic doses of paclitaxel and that the possible mechanism of this protection is that the CDDP prevents human neuroblastoma SH-SY5Y cells from achieving mitosis.