bluuebunny/crossref_metadata_2025 huggingface dataset:
Janus kinase inhibitor INCB20 has antiproliferative and apoptotic effects on human myeloma cellsin vitroandin vivo
Authors: Burger Renate , Le Gouill Steven , Tai Yu-Tzu , Shringarpure Reshma , Tassone Pierfrancesco , Neri Paola , Podar Klaus , Catley Laurence , Hideshima Teru , Chauhan Dharminder , Caulder Eian , Neilan Claire L. , Vaddi Kris , Li Jun , Gramatzki Martin , Fridman Jordan S. , Anderson Kenneth C.
Published: January 2009

Protein tyrosine kinases of the Janus kinase (JAK) family are associated with many cytokine receptors, which, on ligand binding, regulate important cellular functions such as proliferation, survival, and differentiation. In multiple myeloma, JAKs may be persistently activated due to a constant stimulation by interleukin (IL)-6, which is produced in the bone marrow environment. INCB20 is a synthetic molecule that potently inhibits all members of the JAK family with a 100- to 1,000-fold selectivity for JAKs over >70 other kinases. Treatment of multiple myeloma cell lines and patient tumor cells with INCB20 resulted in a significant and dose-dependent inhibition of spontaneous as well as IL-6-induced cell growth. Importantly, multiple myeloma cell growth was inhibited in the presence of bone marrow stromal cells. The IL-6 dependent cell line INA-6 was particularly sensitive to the drug (IC50 < 1 μmol/L). Growth suppression of INA-6 correlated with an increase in the percentage of apoptotic cells and inhibition of signal transducer and activator of transcription 3 phosphorylation. INCB20 also abrogated the protective effect of IL-6 against dexamethasone by blocking phosphorylation of SHP-2 and AKT. In contrast, AKT phosphorylation induced by insulin-like growth factor-I remained unchanged, showing selectivity of the compound. In a s.c. severe combined immunodeficient mouse model with INA-6, INCB20 significantly delayed INA-6 tumor growth. Our studies show that disruption of JAKs and downstream signaling pathways may both inhibit multiple myeloma cell growth and survival and overcome cytokine-mediated drug resistance, thereby providing the preclinical rationale for the use of JAK inhibitors as a novel therapeutic approach in multiple myeloma. [Mol Cancer Ther 2009;8(1):26–35]
Regulation of D-cyclin translation inhibition in myeloma cells treated with mammalian target of rapamycin inhibitors: rationale for combined treatment with extracellular signal–regulated kinase inhibitors and rapamycin
Authors: Frost Patrick , Shi Yijiang , Hoang Bao , Gera Joseph , Lichtenstein Alan
Published: January 2009

We have shown that heightened AKT activity sensitized multiple myeloma cells to the antitumor effects of the mammalian target of rapamycin inhibitor CCI-779. To test the mechanism of the AKT regulatory role, we stably transfected U266 multiple myeloma cell lines with an activated AKT allele or empty vector. The AKT-transfected cells were more sensitive to cytostasis induced in vitro by rapamycin or in vivo by its analogue, CCI-779, whereas cells with quiescent AKT were resistant. The ability of mammalian target of rapamycin inhibitors to down-regulate D-cyclin expression was significantly greater in AKT-transfected multiple myeloma cells due, in part, to the ability of AKT to curtail cap-independent translation and internal ribosome entry site (IRES) activity of D-cyclin transcripts. Similar AKT-dependent regulation of rapamycin responsiveness was shown in a second myeloma model: the PTEN-null OPM-2 cell line transfected with wild-type PTEN. Because extracellular signal–regulated kinase (ERK)/p38 activity facilitates IRES-mediated translation of some transcripts, we investigated ERK/p38 as regulators of AKT-dependent effects on rapamycin sensitivity. AKT-transfected U266 cells showed significantly decreased ERK and p38 activity. However, only an ERK inhibitor prevented D-cyclin IRES activity in resistant “low-AKT” myeloma cells. Furthermore, the ERK inhibitor successfully sensitized myeloma cells to rapamycin in terms of down-regulated D-cyclin protein expression and G1 arrest. However, ectopic overexpression of an activated MEK gene did not increase cap-independent translation of D-cyclin in “high-AKT” myeloma cells, indicating that mitogen-activated protein kinase/ERK kinase/ERK activity was required, but not sufficient, for activation of the IRES. These data support a scenario where heightened AKT activity down-regulates D-cyclin IRES function in multiple myeloma cells and ERK facilitates activity. [Mol Cancer Ther 2009;8(1):83–93]
Regression of human pancreatic tumor xenografts in mice after a single systemic injection of recombinant vaccinia virus GLV-1h68
Authors: Yu Yong A. , Galanis Charles , Woo Yanghee , Chen Nanhai , Zhang Qian , Fong Yuman , Szalay Aladar A.
Published: January 2009

Oncolytic virotherapy of tumors has shown promising results in both preclinical and clinical studies. Here, we investigated the therapeutic efficacy of a replication-competent vaccinia virus, GLV-1h68, against human pancreatic carcinomas in cell cultures and in nude mice. We found that GLV-1h68 was able to infect, replicate in, and lyse tumor cells in vitro. Virus-mediated marker gene expressions were readily detected. Moreover, s.c. PANC-1 pancreatic tumor xenografts were effectively treated by a single i.v. dose of GLV-1h68. Cancer killing was achieved with minimal toxicity. Viral titer analyses in homogenized organs and PANC-1 tumors showed that the mutant virus resides almost exclusively in the tumors and not in healthy organs. Except mild spleen enlargements, no histopathology changes were observed in any other organs 2 months after virus injection. Surprisingly, s.c. MIA PaCa-2 pancreatic tumors were treated with similar efficiency as PANC-1 tumors, although they differ significantly in sensitivity to viral lysis in cell cultures. When GLV-1h68 oncolytic viral therapy was used together with cisplatin or gemcitabine to treat PANC-1 tumors, the combination therapy resulted in enhanced and accelerated therapeutic results compared with the virus treatment alone. Profiling of proteins related to immune response revealed a significant proinflammatory immune response and marked activation of innate immunity in virus-colonized tumors. In conclusion, the GLV-1h68 strain showed outstanding therapeutic effects and a documented safety profile in mice, with great promise for future clinical development. [Mol Cancer Ther 2009;8(1):141–51]
Arsenic trioxide is highly cytotoxic to small cell lung carcinoma cells
Authors: Pettersson Helen M. , Pietras Alexander , Munksgaard Persson Matilda , Karlsson Jenny , Johansson Leif , Shoshan Maria C. , Påhlman Sven
Published: January 2009

Small cell lung carcinoma (SCLC) is an extremely aggressive form of cancer and current treatment protocols are insufficient. SCLC have neuroendocrine characteristics and show phenotypical similarities to the childhood tumor neuroblastoma. As multidrug-resistant neuroblastoma cells are highly sensitive to arsenic trioxide (As2O3) in vitro and in vivo, we here studied the cytotoxic effects of As2O3 on SCLC cells. As2O3 induced pronounced cell death in SCLC cells at clinically relevant concentrations, and also at hypoxia. SCLC cells were more sensitive than non–SCLC cells to As2O3. Cell death was mainly due to necrosis, although apoptotic responses were also seen. A significant in vivo effect of As2O3 on SCLC growth was shown in a nude mice-xenograft model, although a fraction of the treated tumor-bearing animals did not respond. The nonresponding SCLC tumors differed in morphology and cell organization compared with treatment-responsive tumors, which in turn, showed decreased vascularization and higher expression of neuroendocrine markers compared with control tumors. Our results suggest a potential clinical application of As2O3 in SCLC therapy. In addition to cell death induction, antiangiogenic induction of differentiation may also be part of the in vivo effect of As2O3 on SCLC growth, as suggested by an increase in neuroendocrine markers in cultured cells. [Mol Cancer Ther 2009;8(1):160–70]
In vivoactivity of novel capecitabine regimens alone and with bevacizumab and oxaliplatin in colorectal cancer xenograft models
Authors: Kolinsky Kenneth , Shen Ben-Quan , Zhang Yu-E , Kohles Joseph , Dugan Ute , Zioncheck Thomas F. , Heimbrook David , Packman Kathryn , Higgins Brian
Published: January 2009

Modifying the capecitabine dosing schedule from 14 days on, 7 days off (14/7) to 7 days on, 7 days off (7/7) may enable higher doses and improved antitumor efficacy in colorectal cancer xenografts. Capecitabine 14/7 (267 or 400 mg/kg) and 7/7 (467 or 700 mg/kg) schedules in doublet and triplet combinations with optimally dosed bevacizumab (5 mg/kg) and oxaliplatin (6.7 mg/kg) were studied in female athymic nude mice bearing HT29 colorectal xenografts. Additional studies of suboptimally dosed bevacizumab (2.5 mg/kg) and capecitabine 7/7 (360 mg/kg) were done in a similar Colo205 tumor xenograft model. Monotherapy and combination regimens were administered to groups of 10 animals and compared with vehicle controls. In the HT29 model, tumor growth inhibition and increase in life span (ILS) were significantly greater with capecitabine 7/7 than with 14/7 (P < 0.05). The additional benefit of capecitabine 7/7 versus 14/7 was biologically significant according to National Cancer Institute criteria (>25% ILS). Adding bevacizumab to capecitabine 7/7 resulted in significantly greater survival relative to either agent alone (P < 0.0001). When oxaliplatin was added, efficacy was significantly better with the triplet combination including capecitabine 7/7 (tumor growth inhibition >100% and ILS 234%) compared with 14/7 (95% and 81%, respectively). In the Colo205 model, combination therapy with capecitabine 7/7 plus bevacizumab resulted in significantly greater survival relative to either agent alone (P < 0.0001). In conclusion, in athymic nude mice bearing moderately thymidine phosphorylase–expressing HT29 or Colo205 colorectal xenografts, a capecitabine 7/7 schedule permits increased drug delivery compared with traditional 14/7 regimens, greatly improving monotherapy activity without major toxicity. [Mol Cancer Ther 2009;8(1):75–82]
Genomics screen in transformed stem cells reveals RNASEH2A, PPAP2C, and ADARB1 as putative anticancer drug targets
Authors: Flanagan James M. , Funes Juan M. , Henderson Stephen , Wild Laurence , Carey Nessa , Boshoff Chris
Published: January 2009

Since the sequencing of the human genome, recent efforts in cancer drug target discovery have focused more on the identification of novel functions of known genes and the development of more appropriate tumor models. In the present study, we investigated in vitro transformed human adult mesenchymal stem cells (MSC) to identify novel candidate cancer drug targets by analyzing the transcriptional profile of known enzymes compared with non-transformed MSC. The identified enzymes were compared with published cancer gene expression data sets. Surprisingly, the majority of up-regulated enzymes are already known cancer drug targets or act within known druggable pathways. Only three enzymes (RNASEH2A, ADARB1, and PPAP2C) are potentially novel targets that are up-regulated in transformed MSC and expressed in numerous carcinomas and sarcomas. We confirmed the overexpression of RNASEH2A, PPAP2C, and ADARB1 in transformed MSC, transformed fibroblasts, and cancer cell lines MCF7, SK-LMS1, MG63, and U2OS. In functional assays, we show that small interfering RNA knockdown of RNASEH2A inhibits anchorage-independent growth but does not alter in vitro proliferation of cancer cell lines, normal MSC, or normal fibroblasts. Knockdown of PPAP2C impaired anchorage-dependent in vitro growth of cancer cell lines and impaired the in vitro growth of primary MSC but not differentiated human fibroblasts. We show that the knockdown of PPAP2C decreases cell proliferation by delaying entry into S phase of the cell cycle and is transcriptionally regulated by p53. These in vitro data validate PPAP2C and RNASEH2A as putative cancer targets and endorse this in silico approach for identifying novel candidates. [Mol Cancer Ther 2009;8(1):249–60]
CXCR4-gp120-IIIB interactions induce caspase-mediated apoptosis of prostate cancer cells and inhibit tumor growth
Authors: Singh Shailesh , Bond Vincent C. , Powell Michael , Singh Udai P. , Bumpers Harvey L. , Grizzle William E. , Lillard James W.
Published: January 2009

CXC chemokine receptor 4 (CXCR4) has been implicated in prostate cancer metastasis and this receptor also acts as a coreceptor for HIV-1 120-kDa glycoprotein variant IIIB (gp120-IIIB). The interaction between CXCR4 and gp120-IIIB has been shown to mediate apoptosis of both immune and endothelial cells. In this study, we have examined the effects of gp120-IIIB on hormone-refractory prostate cancer cells (PC3 and DU145) in vitro and tumor growth in vivo. Normal prostatic epithelial (PrEC) and prostate cancer cell lines were treated with gp120-IIIB with or without anti-CXCR4 antibody. Caspase expression was evaluated by real-time PCR and active caspase assays. Apoptosis was determined by flow cytometry. gp120-IIIB treatment correlated with active caspase-3 and -9 expression and apoptosis of prostate cancer cells but not PrEC cells. This effect was significantly inhibited after CXCR4 blockade. PC3 and DU145 tumor-bearing mice received intraperitoneal injections of gp120-IIIB and controls received bovine serum albumin in PBS. PC3 and DU145 tumor sizes were measured over time and excised tumors were evaluated for CD44, CD34, lymphatic endothelial cell marker LYVE-1, active caspase-3, and active caspase-9 expression by immunohistochemistry. The tumor size in mice receiving gp120-IIIB was significantly smaller than compared with tumors in control mice. This regression was associated with significant decreases in CD44, CD34, and LYVE-1 and increases in active caspase-3 and -9 expression. These results suggest that gp120-IIIB induced apoptosis in prostate cancer cells and reduced tumor-associated lymphoendothelial cells. [Mol Cancer Ther 2009;8(1):OF178–7
Humanized ADEPT comprised of an engineered human purine nucleoside phosphorylase and a tumor targeting peptide for treatment of cancer
Authors: Afshar Sepideh , Asai Tsuneaki , Morrison Sherie L.
Published: January 2009

Immunogenicity caused by the use of nonhuman enzymes in antibody-directed enzyme prodrug therapy has limited its clinical application. To overcome this problem, we have developed a mutant human purine nucleoside phosphorylase, which, unlike the wild-type enzyme, accepts (deoxy)adenosine-based prodrugs as substrates. Among the different mutants of human purine nucleoside phosphorylase tested, a double mutant with amino acid substitutions E201Q:N243D (hDM) is the most efficient in cleaving (deoxy)adenosine-based prodrugs. Although hDM is capable of using multiple prodrugs as substrates, it is most effective at cleaving 2-fluoro-2′-deoxyadenosine to a cytotoxic drug. To target hDM to the tumor site, the enzyme was fused to an anti-HER-2/neu peptide mimetic (AHNP). Treatment of HER-2/neu-expressing tumor cells with hDM-AHNP results in cellular localization of enzyme activity. As a consequence, harmless prodrug is converted to a cytotoxic drug in the vicinity of the tumor cells, resulting in tumor cell apoptosis. Unlike the nonhuman enzymes, the hDM should have minimal immunogenicity when used in antibody-directed enzyme prodrug therapy, thus providing a novel promising therapeutic agent for the treatment of tumors. [Mol Cancer Ther 2009;8(1):185–93]
Pharmacogenomic approach for the identification of novel determinants of acquired resistance to oxaliplatin in colorectal cancer
Authors: Martinez-Cardús Anna , Martinez-Balibrea Eva , Bandrés Eva , Malumbres Raquel , Ginés Alba , Manzano José Luís , Taron Miquel , Garcia-Foncillas Jesús , Abad Albert
Published: January 2009

Oxaliplatin is a third-generation platinum agent used in colorectal cancer treatment. Oxaliplatin resistance acquisition is a complex process mainly based on alteration of genes and pathways involved in its mechanism of action. Therefore, our purpose was to perform a gene expression screening in an in vitro model to identify genes that could play a role in oxaliplatin resistance acquisition processes. Four colorectal cancer cell lines and their oxaliplatin-resistant derived sublines were compared. Microarray analysis was done using Human 19K Oligo Array Slides. RNA from cells were hybridized with a commercial RNA reference sample and labeled with both fluorochromes Cy3 and Cy5. Data were analyzed by hierarchical clustering method. Subsequently, quantitative real-time PCR (qRT-PCR) was used to corroborate microarray data, considering as positively validated those genes that showed significant differences in expression levels between groups and a correlation between microarray and qRT-PCR data. By microarray analysis, 32 candidate genes were identified. After validation process by qRT-PCR, the genes AKT1, CDK5, TRIP, GARP, RGS11, and UGCGL1 were positively validated. The 3 first genes proved to be involved in regulation of nuclear factor-κβ antiapoptotic transcription factor previously related to drug resistance, and the other 3 genes are novel finds. We have identified 6 genes related to oxaliplatin resistance acquisition. These findings are of paramount importance to understand these processes better and open new lines of study to elucidate the relevance of this pharmacogenomic approach into the clinic. [Mol Cancer Ther 2009;8(1):194–202]
Gemcitabine sensitization by checkpoint kinase 1 inhibition correlates with inhibition of a Rad51 DNA damage response in pancreatic cancer cells
Authors: Parsels Leslie A. , Morgan Meredith A. , Tanska Daria M. , Parsels Joshua D. , Palmer Brian D. , Booth R. John , Denny William A. , Canman Christine E. , Kraker Alan J. , Lawrence Theodore S. , Maybaum Jonathan
Published: January 2009

The protein kinase checkpoint kinase 1 (Chk1) has been implicated as a key regulator of cell cycle progression and DNA repair, and inhibitors of Chk1 (e.g., UCN-01 and EXEL-9844) potentiate the cytotoxic actions of chemotherapeutic drugs in tumor cells. We have examined the ability of PD-321852, a small-molecule Chk1 inhibitor, to potentiate gemcitabine-induced clonogenic death in a panel of pancreatic cancer cell lines and evaluated the relationship between endpoints associated with Chk1 inhibition and chemosensitization. Gemcitabine chemosensitization by minimally toxic concentrations of PD-321852 ranged from minimal (<3-fold change in survival) in Panc1 cells to >30-fold in MiaPaCa2 cells. PD-321852 inhibited Chk1 in all cell lines as evidenced by stabilization of Cdc25A; in combination with gemcitabine, a synergistic loss of Chk1 protein was observed in the more sensitized cell lines. Gemcitabine chemosensitization, however, did not correlate with abrogation of the S-M or G2-M checkpoint; PD-321852 did not induce premature mitotic entry in gemcitabine-treated BxPC3 or M-Panc96 cells, which were sensitized to gemcitabine 6.2- and 4.6-fold, respectively. In the more sensitized cells lines, PD-321852 not only inhibited gemcitabine-induced Rad51 focus formation and the recovery from gemcitabine-induced replication stress, as evidenced by persistence of γ-H2AX, but also depleted these cells of Rad51 protein. Our data suggest the inhibition of this Chk1-mediated Rad51 response to gemcitabine-induced replication stress is an important factor in determining gemcitabine chemosensitization by Chk1 inhibition in pancreatic cancer cells. [Mol Cancer Ther 2009;8(1):45–54]
Peroxisome proliferator-activated receptor γ agonist pioglitazone prevents the hyperglycemia caused by phosphatidylinositol 3-kinase pathway inhibition by PX-866 without affecting antitumor activity
Authors: Ihle Nathan T. , Lemos Robert , Schwartz David , Oh Junghwan , Halter Robert J. , Wipf Peter , Kirkpatrick Lynn , Powis Garth
Published: January 2009

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling cascade is an important component of the insulin signaling in normal tissues leading to glucose uptake and homeostasis and for cell survival signaling in cancer cells. Hyperglycemia is an on-target side effect of many inhibitors of PI3K/Akt signaling including the specific PI3K inhibitor PX-866. The peroxisome proliferator-activated receptor γ agonist pioglitazone, used to treat type 2 diabetes, prevents a decrease in glucose tolerance caused by acute administration of PX-866. Our studies have shown that pioglitazone does not inhibit the antitumor activity of PX-866 in A-549 non-small cell lung cancer and HT-29 colon cancer xenografts. In vitro studies also showed that pioglitazone increases 2-[1-14C]deoxy-d-glucose uptake in L-6 muscle cells and prevents inhibition of 2-deoxyglucose uptake by PX-866. Neither pioglitazone nor PX-866 had an effect on 2-deoxyglucose uptake in A-549 lung cancer cells. In vivo imaging studies using [18F]2-deoxyglucose (FDG) positron emission tomography showed that pioglitazone increases FDG accumulation by normal tissue but does not significantly alter FDG uptake by A-549 xenografts. Thus, peroxisome proliferator-activated receptor γ agonists may be useful in overcoming the increase in blood glucose caused by inhibitors of PI3K signaling by preventing the inhibition of normal tissue insulin-mediated glucose uptake without affecting antitumor activity. [Mol Cancer Ther 2009;8(1):94–100]
Rosiglitazone inhibits α4 nicotinic acetylcholine receptor expression in human lung carcinoma cells through peroxisome proliferator-activated receptor γ-independent signals
Authors: Sun Xiaojuan , Ritzenthaler Jeffrey D. , Zheng Ying , Roman Jesse , Han ShouWei
Published: January 2009

We and others have shown previously that nicotine, a major component of tobacco, stimulates non-small cell lung carcinoma (NSCLC) proliferation through nicotinic acetylcholine receptor (nAChR)-mediated signals. Activation of peroxisome proliferator-activated receptor γ (PPARγ) has been shown to inhibit NSCLC cell growth, but the exact mechanisms responsible for this effect remain incompletely defined. Herein, we show that nicotine induces NSCLC cell proliferation in part through α4 nAChR, prompting us to explore the effects of rosiglitazone, a synthetic PPARγ ligand, on the expression of this receptor. Rosiglitazone inhibited the expression of α4 nAChR, but this effect was through a PPARγ-independent pathway, because GW9662, an antagonist of PPARγ, and the transfection of cells with PPARγ small interfering RNA failed to abolish the response. The inhibitory effect of rosiglitazone on α4 nAChR expression was accompanied by phosphorylation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinase 1/2 and down-regulation of Akt phosphorylation. These signals mediated the inhibitory effects of rosiglitazone on α4 nAChR expression because chemical inhibitors prevented the effect. Rosiglitazone was also found to stimulate p53, a tumor suppressor known to mediate some of the effects of nicotine. Interestingly, p53 up-regulation was needed for rosiglitazone-induced inhibition of α4 nAChR. Thus, rosiglitazone inhibits α4 nAChR expression in NSCLC cells through activation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase, which triggers induction of p53. Finally, like others, we found that nicotine stimulated the expression of α4 nAChR. This process was also inhibited by rosiglitazone through similar pathways. [Mol Cancer Ther 2009;8(1):110–8]
Inhibition of fatty acid synthase by luteolin post-transcriptionally down-regulates c-Met expression independent of proteosomal/lysosomal degradation
Authors: Coleman David T. , Bigelow Rebecca , Cardelli James A.
Published: January 2009

The hepatocyte growth factor (HGF)/c-Met signaling pathway is involved in the progression of several cancers and associated with increased tumor invasion and metastatic potential. We determined previously that the polyphenol epigallocatechin-3-gallate inhibited HGF-induced c-Met phosphorylation in a variety of tumor cell lines in part by disrupting lipid rafts. Fatty acid synthase (FASN) is implicated in cancer progression and may regulate lipid raft function. We therefore examined the effects of luteolin, a potent FASN inhibitor, on c-Met signaling. Luteolin blocked HGF-induced c-Met phosphorylation and scattering of DU145 prostate cancer cells, but inhibition required at least a 4 h preincubation time. Western blot analysis indicated that inhibition of HGF-induced scattering by luteolin occurred coincident with reduction of total c-Met protein in DU145 cells. In addition, luteolin-induced c-Met down-regulation was mimicked by a pharmacologic inhibitor of FASN, C75, or short hairpin RNA knockdown of FASN. Consistent with a role for FASN, loss of c-Met in cells treated with C75 or luteolin was prevented by exogenous addition of palmitate. Luteolin-induced loss of c-Met primarily occurred at a post-transcriptional level and involved cell surface internalization but did not involve translation inhibition, nor was it dependent on the activity of the 26S proteosome or acidic lysosomes. Taken together, our study shows a novel connection between FASN activity and c-Met protein expression and suggests that luteolin could act as a novel HGF/c-Met inhibitor by reducing expression of this receptor. [Mol Cancer Ther 2009;8(1):214–24]
Human concentrative nucleoside transporter 1-mediated uptake of 5-azacytidine enhances DNA demethylation
Authors: Rius Maria , Stresemann Carlo , Keller Daniela , Brom Manuela , Schirrmacher Esther , Keppler Dietrich , Lyko Frank
Published: January 2009

The DNA methyltransferase inhibitors 5-azacytidine (5-azaCyd) and 5-aza-2′-deoxycytidine have found increasing use for the treatment of myeloid leukemias and solid tumors. Both nucleoside analogues must be transported into cells and phosphorylated before they can be incorporated into DNA and inactivate DNA methyltransferases. The members of the human equilibrative and concentrative nucleoside transporter families mediate transport of natural nucleosides and some nucleoside analogues into cells. However, the molecular identity of the transport proteins responsible for mediating the uptake of 5-azanucleosides has remained unknown. To this end, we have generated a stably transfected Madin-Darby canine kidney strain II cell line expressing recombinant hCNT1. An antiserum directed against hCNT1 specifically detected the protein in the apical membrane of hCNT1-expressing Madin-Darby canine kidney cells. Using [14C]5-azaCyd, we show here that hCNT1 mediated the Na+-dependent uptake of this drug with a Km value of 63 μmol/L. Na+-dependent transport of radiolabeled cytidine, uridine, and 5-fluoro-5′-deoxyuridine further showed the functionality of the transporter. hCNT1-expressing cells were significantly more sensitive to 5-azaCyd, and drug-dependent covalent trapping of DNA methyltransferase 1 was substantially more pronounced. Importantly, these results correlated with a significant sensitization of hCNT1-expressing cells toward the demethylating effects of 5-azaCyd and 5-aza-2′-deoxycytidine. In conclusion, our study identifies 5-azaCyd as a novel substrate for hCNT1 and provides direct evidence that hCNT1 is involved in the DNA-demethylating effects of this drug. [Mol Cancer Ther 2009;8(1):225–31]
UA62784, a novel inhibitor of centromere protein E kinesin-like protein
Authors: Henderson Meredith C. , Shaw Yeng-Jeng Y. , Wang Hong , Han Haiyong , Hurley Laurence H. , Flynn Gary , Dorr Robert T. , Von Hoff Daniel D.
Published: January 2009

Pancreatic carcinoma is the fourth leading cause of death from cancer. Novel targets and therapeutic options are needed to aid in the treatment of pancreatic cancer. The compound UA62784 is a novel fluorenone with inhibitory activity against the centromere protein E (CENP-E) kinesin-like protein. UA62784 was isolated due to its selectivity in isogenic pancreatic carcinoma cell lines with a deletion of the DPC4 gene. UA62784 causes mitotic arrest by inhibiting chromosome congression at the metaphase plate likely through inhibition of the microtubule-associated ATPase activity of CENP-E. Furthermore, CENP-E binding to kinetochores during mitosis is not affected by UA62784, suggesting that the target lies within the motor domain of CENP-E. UA62784 is a novel specific inhibitor of CENP-E and its activity suggests a potential role for antimitotic drugs in treating pancreatic carcinomas. [Mol Cancer Ther 2009;8(1):36–44]
Take your PIK: phosphatidylinositol 3-kinase inhibitors race through the clinic and toward cancer therapy
Authors: Ihle Nathan T. , Powis Garth
Published: January 2009

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is currently one of the most exciting drug targets in oncology. However, only a short time ago, the paradigm existed that drugs targeted to the four PI3K class I isoforms would be too toxic for use in cancer therapy due to effects on physiologic signaling. Since that time, studies have delineated the roles of these four isoforms in nonpathologic signaling as well as their roles in cancer. An extensive effort has gone into developing agents that inhibit one or more PI3K isoforms, as well as closely related proteins implicated in cancer. These agents have proved to be tolerable and therapeutically beneficial in animal studies, and a number are in clinical testing. The agents, their properties, and their molecular targets are discussed in this review. [Mol Cancer Ther 2009;8(1):1–9]
Platinum neurotoxicity pharmacogenetics
Authors: McWhinney Sarah R. , Goldberg Richard M. , McLeod Howard L.
Published: January 2009

Cisplatin, carboplatin, and oxaliplatin anticancer drugs are commonly used to treat lung, colorectal, ovarian, breast, head and neck, and genitourinary cancers. However, the efficacy of platinum-based drugs is often compromised because of the substantial risk for severe toxicities, including neurotoxicity. Neurotoxicity can result in both acute and chronic debilitation. Moreover, colorectal cancer patients treated with oxaliplatin discontinue therapy more often because of peripheral neuropathy than tumor progression, potentially compromising patient benefit. Numerous methods to prevent neurotoxicity have thus far proven unsuccessful. To circumvent this life-altering side effect while taking advantage of the antitumor activities of the platinum agents, efforts to identify mechanism-based biomarkers are under way. In this review, we detail findings from the current literature for genetic markers associated with neurotoxicity induced by single-agent and combination platinum chemotherapy. These data have the potential for broad clinical implications if mechanistic associations lead to the development of toxicity modulators to minimize the noxious sequelae of platinum chemotherapy. [Mol Cancer Ther 2009;8(1):10–6]
ABT-510 induces tumor cell apoptosis and inhibits ovarian tumor growth in an orthotopic, syngeneic model of epithelial ovarian cancer
Authors: Greenaway James , Henkin Jack , Lawler Jack , Moorehead Roger , Petrik Jim
Published: January 2009

Epithelial ovarian cancer (EOC) is the fifth most common cancer in women and is characterized by a low 5-year survival rate. One strategy that can potentially improve the overall survival rate in ovarian cancer is the use of antitumor agents such as ABT-510. ABT-510 is a small mimetic peptide of the naturally occurring antiangiogenic compound thrombospondin-1 and has been shown to significantly reduce tumor growth and burden in preclinical mouse models and in naturally occurring tumors in dogs. This is the first evaluation of ABT-510 in a preclinical model of human EOC. Tumorigenic mouse surface epithelial cells were injected into the bursa of C57BL/6 mice that were treated with either 100 mg/kg ABT-510 or an equivalent amount of PBS. ABT-510 caused a significant reduction in tumor size, ascites fluid volume, and secondary lesion dissemination when compared with PBS controls. Analysis of the vasculature of ABT-510-treated mice revealed vascular remodeling with smaller diameter vessels and lower overall area, increased number of mature vessels, and decreased tissue hypoxia. Tumors of ABT-510-treated mice had a significantly higher proportion of apoptotic tumor cells compared with the PBS-treated controls. Immunoblot analysis of cell lysates revealed a reduction in vascular endothelial growth factor, vascular endothelial growth factor receptor-2, and proliferating cell nuclear antigen protein expression as well as expression of members of the phosphatidylinositol 3-kinase and mitogen-activated protein kinase survival pathways. In vitro, ABT-510 induced tumor cell apoptosis in mouse and human ovarian cancer cells. This study shows ABT-510 as a promising candidate for inhibiting tumor growth and ascites formation in human EOC. [Mol Cancer Ther 2009;8(1):64–74]
Intensification therapy with anti-parathyroid hormone-related protein antibody plus zoledronic acid for bone metastases of small cell lung cancer cells in severe combined immunodeficient mice
Authors: Yamada Tadaaki , Muguruma Hiroaki , Yano Seiji , Ikuta Kenji , Ogino Hirokazu , Kakiuchi Soji , Hanibuchi Masaki , Uehara Hisanori , Nishioka Yasuhiko , Sone Saburo
Published: January 2009

Bone metastases occur in more than one-third of patients with advanced lung cancer and are difficult to treat. We showed previously the therapeutic effect of a third-generation bisphosphonate, minodronate, and anti-parathyroid hormone-related protein (PTHrP) neutralizing antibody on bone metastases induced by the human small cell lung cancer cell line, SBC-5, in natural killer cell-depleted severe combined immunodeficient mice. The purpose of our current study was to examine the effect of the combination of PTHrP antibody and zoledronic acid, which has been approved to treat bone metastases, against bone metastases produced by SBC-5 cells expressing PTHrP. Treatment with PTHrP antibody and/or zoledronic acid did not affect the proliferation of SBC-5 cells in vitro. Repeated treatments with either PTHrP antibody or zoledronic acid inhibited the formation of osteolytic bone metastases of SBC-5 cells but had no effect on metastases to visceral organs. Importantly, combined treatment with PTHrP antibody and zoledronic acid further inhibited the formation of bone metastases. Histologic assays showed that, compared with either PTHrP antibody or zoledronic acid alone, their combination decreased the number of tumor-associated osteoclasts and increased the number of apoptotic tumor cells. These findings suggest that this novel dual-targeting therapy may be useful for controlling bone metastases in a subpopulation of small cell lung cancer patients. [Mol Cancer Ther 2009;8(1):119–26]
Identification of phosphotyrosine mimetic inhibitors of human tyrosyl-DNA phosphodiesterase I by a novel AlphaScreen high-throughput assay
Authors: Marchand Christophe , Lea Wendy A. , Jadhav Ajit , Dexheimer Thomas S. , Austin Christopher P. , Inglese James , Pommier Yves , Simeonov Anton
Published: January 2009

Tyrosyl-DNA phosphodiesterase I (Tdp1) resolves topoisomerase I (Top1)-DNA adducts accumulated from natural DNA damage as well as from the action of certain anticancer drugs. Tdp1 catalyzes the hydrolysis of the phosphodiester bond between the catalytic tyrosine residue of topoisomerase I and the DNA 3′-phosphate. Only a limited number of weak inhibitors have been reported for Tdp1, and there is an unmet need to identify novel chemotypes through screening of chemical libraries. Herein, we present an easily configured, highly miniaturized, and robust Tdp1 assay using the AlphaScreen technology. Uninhibited enzyme reaction is associated with low signal, whereas inhibition leads to a gain of signal, making the present assay format especially attractive for automated large-collection high-throughput screening. We report the identification and initial characterization of four previously unreported inhibitors of Tdp1. Among them, suramin, NF449, and methyl-3,4-dephostatin are phosphotyrosine mimetics that may act as Tdp1 substrate decoys. We also report a novel biochemical assay using the SCAN1 Tdp1 mutant to study the mechanism of action of methyl-3,4-dephostatin. [Mol Cancer Ther 2009;8(1):240–8]
Inhibition of focal adhesion kinase as a potential therapeutic strategy for imatinib-resistant gastrointestinal stromal tumor
Authors: Sakurama Kazufumi , Noma Kazuhiro , Takaoka Munenori , Tomono Yasuko , Watanabe Nobuyuki , Hatakeyama Shinji , Ohmori Osamu , Hirota Seiichi , Motoki Takayuki , Shirakawa Yasuhiro , Yamatsuji Tomoki , Haisa Minoru , Matsuoka Junji , Tanaka Noriaki , Naomoto Yoshio
Published: January 2009

Focal adhesion kinase (FAK) is often up-regulated in a variety of malignancies, including gastrointestinal stromal tumor (GIST), and its overexpression seems to be associated with tumor progressiveness and poor prognosis. GIST is well known to have a mutation to c-KIT; thus, a specific c-KIT inhibitor (imatinib) is recognized as the first-line chemotherapy for GIST, although a certain type of c-KIT mutation reveals a resistance to imatinib due to as yet uncertain molecular mechanisms. To assess the c-KIT mutation-related variation of cellular responses to imatinib, murine lymphocyte-derived Ba/F3 cells, which are stably transduced with different types of c-KIT mutation, were treated with either imatinib or a FAK inhibitor (TAE226), and their antitumor effects were determined in vitro and in vivo. A mutation at exon 11 (KITdel559-560) displayed a high sensitivity to imatinib, whereas that at exon 17 (KIT820Tyr) showed a significant resistance to imatinib in vitro and in vivo. KIT820Tyr cells appeared to maintain the activities of FAK and AKT under the imatinib treatment, suggesting that FAK might play a role in cell survival in imatinib-resistant cells. When FAK activity in those cells was inhibited by TAE226, cell growth was equally suppressed and the cells underwent apoptosis regardless of the c-KIT mutation types. Oral administration of TAE226 significantly diminished tumor growth in nude mice bearing KIT820Tyr xenografts. In summary, c-KIT mutation at exon 17 displayed a resistance to imatinib with maintained activations of FAK and subsequent survival signals. Targeting FAK could be a potential therapeutic strategy for imatinib-resistant GISTs. [Mol Cancer Ther 2009;8(1):127–34]
Targeting homologous recombination using imatinib results in enhanced tumor cell chemosensitivity and radiosensitivity
Authors: Choudhury Ananya , Zhao Helen , Jalali Farid , AL Rashid Shahnaz , Ran Jane , Supiot Stephane , Kiltie Anne E. , Bristow Robert G.
Published: January 2009

RAD51 is a key protein in the homologous recombination (HR) pathway of DNA double-strand break repair, and HR represents a novel target for cancer therapy. Because imatinib (Gleevec) has been reported to reduce RAD51 protein levels, we tested the clonogenic survival for RT112, H1299, PANC1, and PC3 tumor cell lines of varying p53 status and normal GM05757 normal fibroblasts after exposure to single agent imatinib (0–20 μmol/L; 0–72 hours). We also combined imatinib with DNA damaging agents that are toxic to RAD51-deficient cells, including ionizing radiation, gemcitabine, and mitomycin C. We observed decreased nuclear expression and chromatin binding of RAD51 protein following imatinib treatment. Imatinib also resulted in decreased error-free HR as determined by a flow cytometry–based integrated direct repeat-green fusion protein reporter system; this correlated to reduced RAD51 expression. Clonogenic survival experiments revealed increased cell kill for imatinib-treated cells in combination with ionizing radiation, gemcitabine, and mitomycin C, due in part to mitotic catastrophe. In experiments using imatinib and gemcitabine, tumor cell lines were sensitized to a greater extent than normal fibroblasts. This preservation of the therapeutic ratio was confirmed in vivo using PC3 xenograft growth delay and intestinal crypt cell clonogenic assays. HR inhibition may be an additional mechanism of action for the chemosensitization and radiosensitization of solid tumors with imatinib with preservation of the therapeutic ratio. [Mol Cancer Ther 2009;8(1):203–13]
Synergy between phosphatidylinositol 3-kinase/Akt pathway and Bcl-xL in the control of apoptosis in adenocarcinoma cells of the lung
Authors: Qian Jun , Zou Yong , Rahman Jamshedur S.M. , Lu Bo , Massion Pierre P.
Published: January 2009

Adenocarcinomas of the lung commonly show an increase in the activity of phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, yet many are resistant to apoptosis induced by the inhibition of PI3K. We hypothesized that Bcl-xL would have a synergistic effect on the apoptotic response induced by inhibition of the PI3K/Akt pathway in lung adenocarcinoma. To test this, we examined the effect of the PI3K inhibitor (LY294002) on lung adenocarcinoma cell lines expressing varying levels of Bcl-xL. We found that cells that overexpress Bcl-xL are resistant to LY294002-induced apoptosis, whereas cells that express little Bcl-xL readily are not. Restoring Bcl-xL expression in cells that express low level of Bcl-xL conferred resistance to apoptosis in response to LY294002. The simultaneous inhibition of the PI3K/Akt pathway by LY294002 or Akt1 small interfering RNA and Bcl-xL function by ABT-737 or Bcl-xL small interfering RNA greatly enhanced the apoptotic response. Moreover, this response was associated with the induction of proapoptotic BH3-only Bcl-2 family member Bim. Our data suggest that PI3K/Akt and Bcl-xL pathways control cell death in lung adenocarcinoma cells in a synergistic manner. Modulation of Bcl-xL expression may represent one important strategy to optimize the efficacy of therapeutic agents targeting the PI3K/Akt pathway in adenocarcinoma of the lung. [Mol Cancer Ther 2009;8(1):101–9]
Ixabepilone: targeting βIII-tubulin expression in taxane-resistant malignancies
Authors: Dumontet Charles , Jordan Mary Ann , Lee Francis F.Y.
Published: January 2009

Microtubule-targeting agents, such as taxanes and epothilones, block mitosis and cell proliferation by targeting the dynamics of the cytoskeleton. The taxanes are widely used for treatment of various malignancies, but primary and acquired resistance to chemotherapy remains a significant clinical concern. Class I, II, III, IV, and V β-tubulin isotypes are expressed in human tumors. Overexpression of the βIII-tubulin isotype is one mechanism that can render tumor cells resistant to taxanes. The relative expression of βIII-tubulin correlates with clinical outcomes in several tumor types, including breast cancer, non–small cell lung cancer, and ovarian cancer. A novel analogue of epothilone B, ixabepilone, has recently been approved in combination with capecitabine for the treatment of patients with anthracycline- and taxane-resistant locally advanced or metastatic breast cancer and as monotherapy in patients whose tumors are resistant or refractory to an anthracycline, a taxane, and capecitabine. The significant antitumor activity of ixabepilone in taxane-resistant tumors may be related to its preferential suppression of the dynamic instability of α/βIII-microtubules in cells expressing high levels of βIII-tubulin. [Mol Cancer Ther 2009;8(1):17–25]
Maximum Covariance Analysis of Typhoon Surface Wind and Rainfall Relationships in Taiwan
Authors: Tsai Hsiao-Chung , Lee Tim Hau
Published: January 2009

The multivariate relationships between hourly surface wind and rainfall observations during typhoons affecting Taiwan have been investigated with maximum covariance analysis (MCA). Historical surface observations from 1987 to 2004 are used when typhoon centers were located inside the domain of 19°–28°N, 117°–127°E. The three leading MCA modes explain 70%, 20.6%, and 7.6% of the squared covariance fraction, and the correlation coefficients are 0.59, 0.48, and 0.49, respectively. The wind directions of the three leading positive modes are 1) northwesterly flow perpendicular to the Snow Mountain Range (SMR), 2) southwesterly flow toward the river valleys of the southwestern Central Mountain Range (CMR) and the southern SMR, and 3) easterly flow toward the northeastern SMR and the northern CMR. The rainfall patterns of the three principal modes reveal the contrast between the windward and the leeward sides of the mountain ranges. Based on the MCA singular vectors, historical typhoon surface wind patterns are categorized into major types. The results show that the three major wind types consist of 53% of the data, with 25%, 9%, and 19%, respectively, for these wind types. Furthermore, the analyses of the corresponding surface air temperatures, relative humidities, and air pressures also reveal contrasting patterns between the windward and leeward sides.
On Robust Estimation of Low-Frequency Variability Trends in Discrete Markovian Sequences of Atmospheric Circulation Patterns
Authors: Horenko Illia
Published: January 2009

Identification and analysis of temporal trends and low-frequency variability in discrete time series is an important practical topic in the understanding and prediction of many atmospheric processes, for example, in analysis of climate change. Widely used numerical techniques of trend identification (like local Gaussian kernel smoothing) impose some strong mathematical assumptions on the analyzed data and are not robust to model sensitivity. The latter issue becomes crucial when analyzing historical observation data with a short record. Two global robust numerical methods for the trend estimation in discrete nonstationary Markovian data based on different sets of implicit mathematical assumptions are introduced and compared here. The methods are first compared on a simple model example; then the importance of mathematical assumptions on the data is explained and numerical problems of local Gaussian kernel smoothing are demonstrated. Presented methods are applied to analysis of the historical sequence of atmospheric circulation patterns over the United Kingdom between 1946 and 2007. It is demonstrated that the influence of the seasonal pattern variability on transition processes is dominated by the long-term effects revealed by the introduced methods. Despite the differences in the mathematical assumptions implied by both presented methods, almost identical symmetrical changes of the cyclonic and anticyclonic pattern probabilities are identified in the analyzed data, with the confidence intervals being smaller than in the case of the local Gaussian kernel smoothing algorithm. Analysis results are investigated with respect to model sensitivity and compared to a standard analysis technique based on a local Gaussian kernel smoothing. Finally, the implications of the discussed strategies on long-range predictability of the data-fitted Markovian models are discussed.
Analyzing the Climate Sensitivity of the HadSM3 Climate Model Using Ensembles from Different but Related Experiments
Authors: Rougier Jonathan , Sexton David M. H. , Murphy James M. , Stainforth David
Published: January 2009

Global climate models (GCMs) contain imprecisely defined parameters that account, approximately, for subgrid-scale physical processes. The response of a GCM to perturbations in its parameters, which is crucial for quantifying uncertainties in simulations of climate change, can—in principle—be assessed by simulating the GCM many times. In practice, however, such “perturbed physics” ensembles are small because GCMs are so expensive to simulate. Statistical tools can help in two ways. First, they can be used to combine ensembles from different but related experiments, increasing the effective number of simulations. Second, they can be used to describe the GCM’s response in ways that cannot be extracted directly from the ensemble(s). The authors combine two experiments to learn about the response of the Hadley Centre Slab Climate Model version 3 (HadSM3) climate sensitivity to 31 model parameters. A Bayesian statistical framework is used in which expert judgments are required to quantify the relationship between the two experiments; these judgments are validated by detailed diagnostics. The authors identify the entrainment rate coefficient of the convection scheme as the most important single parameter and find that this interacts strongly with three of the large-scale-cloud parameters.