bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 248: Control of prostate tumor growth and centriole amplification by antizyme and antizyme inhibitor
Authors: Olsen Rachelle R. , Chung Ivy , Zetter Bruce R.
Published: June 2012

The endogenous antizyme inhibitor (AZI) is best characterized for its role in regulating polyamine homeostasis. Polyamines are organic cations synthesized by the enzyme ornithine decarboxylase (ODC), a protein which is negatively regulated and targeted for proteasomal degradation by antizyme (AZ). AZI is a potential oncogene which promotes cell growth not only by inhibiting antizyme (AZ) activity, but also by releasing ODC from AZ-mediated degradation. High levels of ODC and polyamines are associated with numerous types of neoplastic transformation, and the genomic region including AZI is frequently amplified in tumors of the ovary and prostate. To determine whether AZI functionally promotes prostate tumor growth, we made PC3M-LN4 (human) and AT6.1 (rat) cancer cell lines stably expressing AZI shRNA. AZI knockdown was confirmed by western blot and RT-PCR. To examine the ability of these cells to form tumors in vivo, 1×106 cells were injected subcutaneously into nude mice either with (PC3M-LN4) or without (AT6.1) Matrigel. Tumor growth was measured two times per week by caliper. Cells in which AZI levels had been knocked down by shRNA formed significantly smaller tumors in vivo, and had significantly smaller end tumor weights. These results suggest that not only does AZI promote tumor growth, but also that AZI may be a novel and valid therapeutic target for cancer treatment.

In addition to their effects on cell proliferation, previous studies in our laboratory have shown that both AZI and AZ localize to centrosomes and are important for controlling centrosome duplication. Centrosome amplification is a frequent and early event in tumorigenesis. We found that overexpression of AZI and knockdown of AZ both result in cells with daughter centriole amplification due to abnormal centriole synthesis. To gain insight into the mechanism by which AZ and AZI modulate centriole synthesis, we are currently analyzing whether proteins that regulate centrosome duplication interact with either AZI or AZ. We are also using Tet-inducible overexpression vectors to monitor the effect of increased AZ or AZI levels on centriole amplification, and exploring how localization of these proteins to the centrosome contributes to the centrosome amplification phenotype. These studies provide a much greater understanding of AZI function, and suggest that high AZI levels may contribute to tumorigenesis both by promoting cell growth and inducing centrosome amplification.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 248. doi:10.1158/1538-7445.AM2011-248
Abstract 2493: Capsaicin, a novel radiosensitizer, acts via a TRPV6 mediated mechanism
Authors: Venier Natalie A. , Colquhoun Alexandra J. , Sasaki Hiroshi , Loblaw Andrew D. , Fleshner Neil E. , Klotz Laurence H. , Venkateswaran Vasundara
Published: June 2012

Radiosensitizing agents sensitize cells to the lethal effects of ionizing radiation (IR). This permits use of lower doses of radiation to achieve equivalent cancer control thereby minimizing adverse effects to normal tissues. Given their lack of toxicity compounds occurring naturally in the diet make ideal potential radiosensitizing agents.

Capsaicin, a compound found in the Capsicum sp. of plants, is a widely consumed food additive in areas with low PCa incidence. Traditionally capsaicin is used to treat chronic pain syndromes; however, recently evidence using in vitro PCa models describes its anti-carcinogenic potential. The transient receptor potential vanilloid-receptor (TRPV)-1 and TRPV6 cation selective channels are thought to be partly responsible for mediating these effects. TRPV-1 and TRPV-6 expression is up-regulated in PCa tissue correlating directly with increasing tumor grade. This suggests TRPV1 and/or TRPV6 may be potential therapeutic targets for capsaicin mediated interventions in PCa patients.

As IR and capsaicin both promote apoptosis and inhibit cell cycle progression in vitro we hypothesize an at least additive effect of combining these two therapies.

Using clonogenic assays we assessed the effect of ionizing radiation (1-8 Gy) and/or capsaicin (1-10μM) on colony formation rates in 4 human PCa cell lines (LNCaP, PC3, PC3AR2, DU145). Proliferative, apoptotic, TRPV-6 protein markers were assessed using Western blot analyses.

Exposure of cells to capsaicin (1-10μM) or IR (1-8Gy) caused significant dose-dependent inhibition of colony formation (p<0.001). Combining capsaicin with IR resulted in further significant inhibition of colony formation rates (P<0.001). Western blot analyses showed LNCaP cells treated with capsaicin and/or IR to have increased expression of pro-apoptotic proteins BAX and Bad, tumor-suppressor proteins p21 and p27 and reduced androgen-receptor. Additionally, capsaicin monotherapy caused a dramatic alteration in TRPV1 and TRPV6 expression.

These studies confirm the radiosensitizing capacity of capsaicin in PCa cells in vitro. Ongoing studies using are further delineating the mechanism of interaction of these treatment modalities.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2493. doi:10.1158/1538-7445.AM2011-2493
Abstract 2495: The autophagy inducing drug carbamazepine is a radiation protector and mitigator
Authors: Kim Hyun , Bernard Mark , Flickinger John , Epperly Michael W. , Wang Hong , Dixon Tracy M. , Shields Donna , Houghton Frank , Greenberger Joel S.
Published: June 2012

The role of autophagy in cellular response to radiation is controversial. Some investigators report that induction of autophagy increases radiosensitivity whereas others report that it confers radioresistance. Carbamazepine, traditionally used to treat mood disorders, epilepsy and trigeminal neuralgia, has recently been shown to induce autophagy. We hypothesized that carbamazepine would be radioprotective in vitro and in vivo by upregulating autophagy in cells and tissue after irradiation. In clonogenic assays of murine hematopoietic progenitor cells (32Dcl3), carbamazepine at 1, 10 and 100 uM for 1 hour prior to irradiation (0 – 8 Gy) increased the Do from 1.5 ± 0.1 to 2.1 ± 0.1 (p = 0.011), 2.3 ± 0.1 (p = 0.010), and 3.6 ± 0.7 (p = 0.003), respectively. Carbamazepine after irradiation increased the shoulder (ñ) on the survival curve from 1.4 ± 0.3 to 10.1 ± 4.2 (p = 0.011), 5.5 ± 1.7 (p = 0.018), or 3.6 ± 0.8 (p = 0.014), respectively. C57BL/6NHsd mice with intraperitoneal injection of carbamazepine (20 mg/kg) immediately before or after 9.25 Gy irradiation demonstrated increased survival (p = 0.008 and 0.005, respectively). JC1 stain and TUNEL assay revealed that carbamazepine had no effect on changes in mitochondria potential or apoptosis, respectively, following 5 or 10 Gy. Immunoblot for LC3 in 32Dcl3 cells 24 hours after irradiation revealed a 3.3x (5 Gy) and 6.2x (10 Gy) increase in LC3II/LC3I when cells were incubated in 50 uM carbamazepine. Cells irradiated in the absence of carbamazepine exhibited a 1.3x (5 Gy) and 1.8x (10 Gy) LC3II/LC3I increase, respectively. This data suggest that carbamazepine may be a valuable radiation mitigator by upregulating autophagy in irradiated cells.

Supported by 2U19A1068021-06

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2495. doi:10.1158/1538-7445.AM2011-2495
Abstract 250: The critical requirement of ATM function in PTEN null cell lines
Authors: McCabe Nuala , Walker Steven M. , Greenan Caroline , Wikstrom Katarina , McLean Estelle , Delaney Thomas , McCarthy Michelle , James Iain , Harrison Timothy , Mullan Paul , Harkin Paul , Kennedy Richard
Published: June 2012

Introduction: The tumour suppressor PTEN is frequently lost in multiple cancer types, loss of PTEN function has been linked to activation of the AKT signalling pathway. The regulation of the AKT signalling has long been attributed as the key tumour suppressing function of PTEN. However, it has recently been demonstrated that PTEN null cells demonstrate genomic instability and require base excision repair (BER) for survival. One of the critical functions of BER is the repair of oxidative DNA damage; we postulated that PTEN might have a role in the maintenance of this form of damage. Additionally, we investigated which molecular pathways were involved in the response of this form of DNA damage in PTEN null cells.

Results: Using isogenic cell lines we found an increased in baseline ROS levels according to PTEN status. Specifically the increase in ROS levels was correlated to an increase in the levels of double strand breaks as measured by levels of activated γH2AX, formation of γH2AX foci and activation of the DNA damage response kinase ATM. Furthermore, inhibition of ATM function both via siRNA knockdown and small molecule inhibition in PTEN null cells resulted in cell cycle arrest followed by apoptosis. Strikingly this dependence on ATM activity was independent of AKT activity, suggesting that the oxidative DNA damage was the result of a loss in PTEN function independent of its role in the regulation of the AKT activation.

Conclusions: These observations suggest that PTEN may play a role in the maintenance of the repair of ROS DNA damage; furthermore it maybe postulated that inhibition of ATM maybe a suitable therapeutic intervention for PTEN null tumours.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 250. doi:10.1158/1538-7445.AM2011-250
Abstract 2502: Swallowed small molecule GS-nitroxide, JP-4-039, protects the irradiated esophagus
Authors: Epperly Michael W. , Greenberger Joel S. , Kim Hyun , Bernard Mark , Dixon Tracy , Franicola Darcy , Wipf Peter , Li Song , Gao Xiang , Kagan Valerian , Amoscato Andrew , Shen Hongmei
Published: June 2012

Irradiation induced esophagitis is a dose limiting factor in the treatment of lung cancer, and limits irradiation dose escalation. Intraesophageal manganese superoxide dismutase plasmid liposomes has been shown to protect against irradiation esophagitis (Tarhini, et.al. Human Gene Therapy, in press). A new small molecule drug recently has shown irradiation protection and mitigation in vitro. The new drug (JP4-039) is a nitroxide attached to a mitochondrial targeting sequence. Drug was delivered to the top of the esophagus and the mouse swallowed the F15 formulation, consisting of soy PC: Tween-80: L-glutamyl dioleylamide (4:1:1 w/w) and 8 mg/ml of JP4-039 in PBS. C57BL/6NHsd mice swallowed 100 µl water followed by 100 µl F15-JP4-039 (0.4 mg/mouse) ten minutes before 28 Gy to the upper body. F15-JP4-039 resulted in a significant increase in survival compared to irradiated controls. F15-JP4-039 produced a 30 day survival of 75% compared to 30% for irradiation control (p = 0.0315). The JP4-039 nitroxide signal, detected by EPR, allowed demonstration that drug was in whole esophagus and in the esophageal stem cells. F15-JP4-039 intraorally treated mice were sacrificed at 10 min, 30 min, 1 hr or 5 hr after swallowing the F15-JP4-039, esophagus removed, single cell suspensions made, frozen, and analyzed by EPR. At 10 min, 2971.3 fmoles of JP4-039/million cells were detected, and still detected out to 5 hours, 1081 fmoles/million cells, after irradiation. Sorted side population cells (SP), enriched for stem cells, and nonside population cells (NSP) isolated by flow cytometer were analyzed at 10 min after swallow, by EPR for JP4-039 uptake. The SP cells had 3666.7 fmoles per million cells and the NSP cells had 73.7 fmoles nitroxide per million cells demonstrating that drug had reached stem cells. Thus, intraesophageal administration of small molecule antioxidant GS-nitroxide reduces murine radiation esophagitis, and may be a valuable translational radiation protector to ameliorate clinical esophagitis in lung cancer patients.

Supported by 2U19A1068021-06 and RO1-CA83876-06

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2502. doi:10.1158/1538-7445.AM2011-2502
Abstract 2507: Triple agent therapy combining radiation with AMG479 (IGF1R antibody) and panitumumab (EGFR antibody) in a head and neck tumor model
Authors: Matsumoto Fumihiko , Raju Uma , Valdecanas David , Milas Luka , Ang K Kian
Published: June 2012

PURPOSE: The combination of radiation with concurrent chemotherapy improves local-regional control and overall survival in patients with locally advanced head and neck squamous cell carcinoma (HNSCC). However, its acute and chronic toxicity have raised concerns and thereby prompted the search for more biologically sound therapeutic strategy, e.g., targeting receptor tyrosine kinases (RTKs) that are differentially expressed between tumors and normal tissues. The current study tested the therapeutic benefits of co-targeting two RTKs, namely, epidermal growth factor receptor (EGFR) by panitumumab (Pmab) and insulin-like growth factor receptor-1 (IGF-1R) by AMG479 to enhance tumor response to radiation.

METHODS AND MATERIALS: A HNSCC model, FaDu, was used for assessing the effects of AMG479, and Pmab to improve tumor response to radiation by in vitro clonogenic cell survival assay and in vivo tumor growth delay assay. Various doses and administration scheduling of these agents relevant to radiation were tested.

RESULTS: In vitro study showed that Pmab significantly enhanced the radiosensitivity of FaDu with an enhancement factor (EF) of 1.4 at 0.5 survival fraction. AMG479 given alone or concurrently with Pmab had no affects in normal (10% serum) culture media. In vivo xenograft studies showed that Pmab or AMG479 given as single agent enhanced the tumor response to fractionated radiation (2 Gy twice a day for 6 d) in a dose and schedule dependent manner. The maximum EF was 1.1 for AMG479 and 1.7 for Pmab. The effects of combining Pmab and AMG479 with radiation depended markedly on the scheduling. The best effects were achieved when (1) Pmab and AMG479 were given concurrently daily starting 4 d before radiation for a total of 15 days resulting in an EF of 3.0 or (2) Pmab and AMG479 were given sequentially commencing Pmab 4 d before radiation for 15 d and AMG479 after completion of radiation also for 15 d yielding an EF of 2.9. However, administering AMG479 before radiation followed by Pmab was much less effective (EF: 2.0).

CONCLUSIONS: Our results showed Pmab enhanced FaDu response to radiation. AMG479 markedly increased tumor response when given together or following Pmab, in conjunction with radiation. These findings provide the rationale for clinical testing of the combination of Pmab and AMG479 for the treatment of HNSCC along with the most promising regimen of administration.

Supported by Amgen Inc., Thousand Oaks, CA

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2507. doi:10.1158/1538-7445.AM2011-2507
Abstract 2508: Identification of potential relevant pathways and genes for resistance to chemoradiotherapy in colorectal cancer cells
Authors: Grade Marian , Spitzner Melanie , Emons Georg , Kramer Frank , Gaedcke Jochen , Rave-Fränk Margret , Scharf Jens-Gerd , Burfeind Peter , Becker Heinz , Beissbarth Tim , Ghadimi B. Michael , Ried Thomas
Published: June 2012

The standard treatment of patients with locally advanced rectal cancers comprises preoperative 5-fluorouracil-based chemoradiotherapy followed by standardized surgery. However, the tumor response to multimodal treatment has varied greatly and ranging from complete resistance to complete pathologic regression. The prediction and treatment of these observed heterogeneous response to therapy in patients is, therefore, an important clinical need.

A strategy for studying the molecular basis of this heterogeneous tumor response is to establish the clinical parameters as an in vitro model. For this purpose we used 12 colorectal cancer cell lines and exposed them to 3 µM of 5-fluorouracil and 2 Gy of radiation, which reflect the parameters used in clinical patient treatment. The sensitivity differences of the cell lines to chemoradiotherapy, measured as surviving fractions by a standard colony formation assay, were then correlated with the pretherapeutic gene expression profiles of these cell lines. The microarray measurements were independently validated for a subset of these genes using real-time polymerase chain reactions.

In the 12 colorectal cancer cell lines we observed a heterogeneous response, with surviving fractions ranging from 0.28 to 0.81, closely recapitulating clinical reality. Using a linear model analysis, we identified 4,796 features whose expression levels correlated significantly with the sensitivity to chemoradiotherapy (Q < 0.05), including many genes involved in the mitogen-activated protein kinase signaling pathway or cell cycle genes. These data have suggested a potential relevance of the insulin and Wnt signaling pathways for the treatment response, and we identified STAT3, RASSF1, DOK3, and ERBB2 as potential therapeutic targets.

We anticipate that this analysis of a gene expression signature for the in vitro chemoradiosensitivity of colorectal cancer cells will unveil molecular biomarkers predictive of the response of rectal cancers to chemoradiotherapy and enable the identification of genes that could serve as targets to sensitize a priori resistant primary tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2508. doi:10.1158/1538-7445.AM2011-2508
Abstract 251: Kinome-wide RNAi screen identification of synthetic lethal interactions in BRAF-mutant melanoma
Authors: Zejnullahu Kreshnik , Wagenaar Tim , Green Michael R.
Published: June 2012

BACKGROUND. Mutations in the BRAF oncogene are prevalent in many types of solid cancers, where they promote cell proliferation and transformation by constitutively activating the RAF-MEK-ERK signaling pathway. Inhibitors of BRAF have been developed as potential cancer therapies but unfortunately many have performed poorly in clinical trials. As an alternative approach, we performed RNA interference (RNAi) screening to identify genes that are synthetically lethal with the BRAF-mutant oncogene in malignant melanoma cell lines. Recent advances in RNAi and deep sequencing technologies have made it possible to systematically interrogate the genome for synthetic lethal interactions.

METHODS. Two BRAF-mutant melanoma cell lines (SKMEL28 and Malme3M) and one wild-type BRAF cell line (MeWo) were infected with a subset of The RNAi Consortium (TRC) shRNA library comprising all the kinases in the human genome as well as the genes involved in the tyrosine kinase>RAS>RAF>MEK>ERK pathway. Cells were collected at 4 and 19 days post-infection, genomic DNA was isolated, shRNAs were PCR amplified and subjected to massively parallel sequencing. Statistical analysis identified ∼200 shRNAs that were selectively depleted in BRAF-mutant but not wild-type BRAF cell lines; individual canidate shRNA were tested in a panel of 6 melanoma cell lines 3 BRAF-mutant (UACC62, UACC257, Malme3M) and 3 wild-type BRAF (WM3912, WM3918, MeWo).

SUMMARY. The screen identified a diverse number of genes that are synthetically lethal with the BRAF-mutant oncogene in human malignant melanoma. Not surprisingly, a number of the identified synthetic lethal genes are known downstream effectors of BRAF or known scaffold proteins involved in MAPK signaling. Paradoxically, epiregulin (EPGN), a known ligand of the epidermal growth factor receptor (EGFR) and EGFR itself, which are upstream of the BRAF oncogene were also identified in the screen as synthetically lethal with mutant BRAF.

CONCLUSIONS. The BRAF oncogene is synthetically lethal with genes involved in diverse cellular processes such as kinase signaling, cell division, nuclear shuttling and cell metabolism. Many of the genes identified in the RNAi screen are known effectors of the MAPK cascade. Paradoxically, two members of the MAPK cascade, EGFR and its ligand EPGN, both of which are upstream of BRAF, were identified in the screen and validated to be synthetically lethal with mutant BRAF.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 251. doi:10.1158/1538-7445.AM2011-251
Abstract 2512: Combining radiation or carboplatin with targeted inhibition of survivin increases treatment induced apoptosis in retinoblastoma cells
Authors: Luna Marian , Ferrario Angela , Rucker Natalie , Wong Sam , Gomer Charles J.
Published: June 2012

The overarching goal of this project is to evaluate clinically relevant protocols to improve treatment responses for retinoblastoma (Rb). Procedures to treat Rb vary depending on the size and location of the intraocular lesions and can include carboplatin or radiation therapy. We have preliminary data documenting over expression of survivin, a member of the inhibitor of apoptosis family of proteins, following treatment of Rb cells with either carboplatin or ionizing radiation. The specific aim of the current study is to determine if targeted inhibition of survivin expression using the clinically relevant small molecule imidazolium inhibitor, YM155, can increase selective cytotoxicity in Rb cells. Experimental procedures used Y79 retinoblastoma and RPE normal retinal pigmented epithelial cell lines. Protein expression following either single or combined treatment protocols is examined by Western immunoblot. Levels of apoptosis and cytotoxicity are determined by flow cytometry following Annexin V and propidium iodide staining. We document that both radiation (5 Gy) and carboplatin (5 uM) induce significant over expression of survivin in Y79 cells, but not in RPE cells. Over expression of survivin following radiation or carboplatin is blocked in Y79 cells exposed to YM155 (2 nM). Combining radiation or carboplatin with YM155 resulted in significantly increased levels of apoptosis and cell killing in Y79 cells but not in RPE cells. These results indicate that targeted inhibition of survivin may provide a therapeutic gain when combined with radiation or carboplatin.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2512. doi:10.1158/1538-7445.AM2011-2512
Abstract 2515: Inverse relationship between PSA and IL-8 in prostate cancer: An insight into the mechanisms of NF-κB-mediated radioresistance
Authors: Xu Yong , Fang Fang , Clair Daret K. St. , Clair William H. St.
Published: June 2012

Nuclear factor κB (NF-κB), an inflammatory responsive transcription factor, is involved in tumorigenesis and resistance of cancer cells to therapy-induced cytotoxicity. Our previous studies demonstrated that activation of RelB-mediated NF-κB alternative pathway contributes to tumorigenicity of prostate cancer, decreased the circulating levels of prostate specific antigen (PSA), and enhanced the level of interleukin-8 (IL-8). The present study extends to directly test the role of RelB on radioresistance of prostate cancer in vivo, investigate the relationship between IL8 and PSA expression, and determine their role in the response of prostate cancer to radiation. We found that expression of RelB in prostate cancer cells with a low basal level of RelB (LNCaP) reduced their radiosensitivity and suppression of RelB in prostate cancer cells with a high basal level of RelB (PC3) enhanced their radiosensitivity in vitro and in xenograft tumors. The RelB-mediated inverse relationship between PSA and IL-8 expression was verified through direct modulation of RelB levels by transfection of RelB cDNA and RNAi in multiple prostate cancer cell lines. Interestingly, when the cellular levels of PSA and IL-8 were manipulated, by treating cultural cells with pure compounds or genetic manipulations, we found that up-regulation of IL-8 with concurrent down-regulation of PSA reduced radiosensitivity of prostate cancer cells. In contrast, up-regulation of PSA with concurrence down-regulation of IL-8 resulted in an increase in radiosensitivity. Together, the results reveal a previously unrecognized role of IL-8 on PSA expression, identify an inverse relationship between PSA and IL-8 as an indicator of radiosensitivity and implicate inhibition of the NF-κB alterative pathway as a promising approach for prostate cancer treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2515. doi:10.1158/1538-7445.AM2011-2515
Abstract 2518: Structure-activity relationships of folate-vinca alkaloid conjugates
Authors: Leamon Christopher P. , Vlahov Iontcho R. , Reddy Joseph A. , Vetzel Marilynn , Santhapuram Hari K. , You Fei , Bloomfield Alicia , Dorton Ryan , Nelson Melissa , Kleindl Paul , Vaughn Jeremy , Westrick Elaine
Published: June 2012

EC145 is a potent folate-targeted vinca alkaloid conjugate that has been evaluated in 2 single agent phase 2 trials (ovarian and non small cell lung cancers) and 1 randomized open labeled phase 2 study in combination with DOXIL® in women with platinum-resistant ovarian cancer. Results from all of these trials have looked promising, and they support the continued evaluation of EC145 in a planned phase 3 trial that's expected to begin in early 2011. Structurally, EC145 consists of 4 essential modules: 1) folic acid, 2) a hydrophilic peptide spacer, 3) a disulfide-containing, self-immolative linker, and 4) the microtubule destabilizer, desacetylvinblastine hydrazide (DAVLBH). Due to EC145's potential for success, recent effort was given to determine the impact of i) substituting the DAVLBH vinca alkaloid unit in EC145 with analogs of vincristine, vindesine or vinorelbine, ii) substituting the naturally (S)-configured Asp-Arg-Asp-Asp-Cys peptide spacer in EC145 with (R)-configured amino acids placed in selective locations, and iii) varying the composition of the linker module to evaluate the impact of having a readily releasable, self-immolative linker system (e.g. disulfide-based as found in EC145) versus a more stable linker system (e.g. a thioether). New conjugates were screened in vitro against folate receptor-positive cells, and their cytotoxic activities were directly compared to that produced by EC145. Our data show that only DAVLBH-containing folate conjugates were active; thus, conjugates built with vincristine, vindesine or vinorelbine failed to produce activity when cells were exposed to concentrations as high as 1 µM. Within the DAVLBH series, having a bio-releasable, self-immolative linker system was found to be critical for activity since multiple analogs constructed with thioether-based linkers failed to produce meaningful activity both in vitro and in vivo. Substitutions of some or all of the natural amino acids within EC145's hydrophilic spacer module was not found to significantly change the in vitro potency of the conjugate; however, some enhancement in anti-tumor activity was measurable when tested in vivo against well-established subcutaneous folate receptor-positive tumor xenografts. Despite these modest improvements, EC145 remains as one of the more potent folate-vinca alkaloid conjugates produced to date, and continued clinical development is therefore warranted.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2518. doi:10.1158/1538-7445.AM2011-2518
Abstract 2530: The anticancer kinase inhibitor dovitinib (TKI258/CHIR258) may have multiple modes of action because it also binds DNA and inhibits topoisomerase I and topoisomerase IIα
Authors: Wu Xing , Yalowich Jack C. , Hasinoff Brian
Published: June 2012

Dovitinib (TKI258/CHIR258) is a kinase inhibitor in phase II development for the treatment of renal cell carcinoma, advanced breast cancer, and relapsed multiple myeloma. Dovitinib is thought to exert anticancer effects through its binding to and kinase inhibition of fibroblast growth factor receptor 3 (FGFR3). It also strongly inhibits a number of other kinases that are members of the RTK superfamily, including the vascular endothelial growth factor receptor (VEGFR); fibroblast growth factor receptor 1 (FGFR1); platelet-derived growth factor receptor type 3; FMS-like tyrosine kinase 3 (FLT3); stem cell factor receptor (c-KIT) and colony-stimulating factor receptor 1 (CSF1R) all of which may also contribute to its anticancer activity. In terms of its chemical structure dovitinib is a benzimidazole-quinolinone compound. Thus, structurally it resembles the bisbenzimidazole minor groove binding dye Hoechst 33258. Molecular modeling studies of the docking of dovitinib into an X-ray structure of a Hoechst 33258-DNA complex showed that dovitinib could be reasonably accommodated in the minor groove. Dovitinib was shown to bind to DNA by its ability to increase the DNA melting temperature. Changes in the visible absorbance and fluorescence spectrum of dovitinib that occurred upon addition of DNA were also consistent with DNA binding. Because DNA binders are often topoisomerase I and topoisomerase II inhibitors, the ability of dovitinib to inhibit these DNA processing enzymes was also investigated. Dovitinib inhibited both the decatenation activity and the ATPase activity of topoisomerase IIα in the low micromolar concentration range. Dovitinib was also able to stabilize the topoisomerase IIα-cleavage complex and act as a topoisomerase IIα poison with activity comparable to etoposide as measured by its ability to induce formation of linear DNA. Dovitinib was also examined for its ability to increase phosphorylation of H2AX in K562 cells to determine if it could act as a cellular topoisomerase II poison and induce double strand DNA breaks. Dovitinib was also able to inhibit the topoisomerase I-catalyzed relaxation of DNA. In conclusion, the anticancer activity of dovitinib may result not only from its ability to inhibit multiple kinases, but also from its ability to target topoisomerase I and topoisomerase IIα. Support: CIHR and a Canada Research Chair in Drug Development to BBH and an NIH grant (CA090787) to JCY.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2530. doi:10.1158/1538-7445.AM2011-2530
Abstract 2535: PrevOnco® exhibits anti-tumor activity in in vitro and in vivo human tumor models: Combination therapy (PrevOnco® / Doxorubicin) demonstrates a better efficacy profile with enhanced survival rate in a liver cancer model
Authors: Incardona Francesca , Dines Kevin , Damaj Bassam , Martin Richard , Hachicha Mohamed
Published: June 2012

Background: The investigational anti-neoplastic agent PrevOnco® (know as Prevacid® /Lansoprazole®) is entering Phase II clinical trials in the US for hepatocellular carcinoma.

Objectives: This study examined the efficacy of PrevOnco® in both in vitro and in vivo human tumor models. The optimal oral formulation, pharmacokinetic parameters and its combination therapy with doxorubicin were evaluated.

Methods: Cytotoxicity was assessed in vitro by MTT analysis. In vivo efficacy was assessed in nude mice in 2 survival models of the pediatric kidney-derived G401 and SR leukemia, and one ectotopic HepG2 model.

Results: In MTT assays, PrevOnco® demonstrated a concentration-dependent cytotoxic effect against a number of cancer cell lines (MC116, HOP-62, MOLT4, HCT-15, JMI, RPMI6666, RS 1184, STA 486, SF539, U251, SF295, UACC-62). Synergistic activity was observed with doxorubicin but not with cisplatin. PrevOnco® was significantly more effective than Omeprezole or SCH-28080. Pharmacokinetic analysis in nude mice showed 10% PEG400 to be a better vehicle than carboxy-methyl cellulose. A mean maximum concentration (Cmax) of 20,242 ng/mL was detected at 0.5 hours (Tmax) with the mean dose adjusted area under the curve (AUC) determined to be 846.5 nM*hr/mg. The half life (T1/2) of the compound was 0.9 hours. PrevOnco® at 100 mg/kg given orally significantly prolonged the survival rate in the G401 kidney xenograft by 60% at day 70 whereas all mice in vehicle treaded group died. At study end (day 83) 26% of the mice remained alive in the treated group. SR leukemia xenograft treated with PrevOnco® survived through the end of the study with >80% of the mice remaining alive. PrevOnco® induced a dose-dependent reduction in tumor growth in hepG2 model. A synergestic antitumoral effect was obtained with the combination treatment of PrevOnco® at 30 mg/kg and doxorubicin at10 mg/kg. PrevOnco® levels in hepG2 tumors following 100 mg/Kg BID treatment for 3 consecutive days indicated accumulation of the drug into tumor tissue.

Conclusion: PrevOnco® exhibited anti-neoplastic activity in both in vitro and in vivo, enhancing survival and inhibiting tumor growth. Synergistic activity was obtained with doxorubicin in xenograft model of liver cancer, suggesting a potential new combination therapy for the treatment of liver cancer with less toxicological liability.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2535. doi:10.1158/1538-7445.AM2011-2535
Abstract 2539: Antitumor effects of oral paclitaxel DHP107 on gastric cancer xenografts
Authors: Na Young-Soon , Jung Kyung-Ah , Yang Soo-Jin , Kim Seung-Mi , Kim Hye Youn , Hong Yong Sang , Ryu Min-Hee , Lee Jae-Lyun , Son Woo-Chan , Jin Dong-Hoon , Kim Tae Won
Published: June 2012

Oral paclitaxel DHP107 (Daehwa, Seoul Korea), an antineoplastic agent, is effectively absorbed through the gastrointestinal tract via the lipid uptake mechanism, which is currently under clinical investigation. Oral capecitabine generates 5-fluorouracil (5-FU) by thymidine phosphorylase, preferentially in tumor tissue. Taxanes, such as paclitaxel and docetaxel, have the ability to up-regulate levels of thymidine phosphorylase which show the its increased activity in tumors compared with that of normal tissue. Accordingly, combination treatment using taxanes with capecitabine is effective in several tumors, especially in gastric cancer. In this study, we investigated the antitumor effect of DHP107 combined with capecitabine and compared the effects of DHP107 and Taxol in gastric cancer xenografts. DHP107 in combination with capecitabine dramatically inhibited tumor growth without additive toxicity compared with each agent used alone in gastric xenografts. The expression of the level of thymidine phosphorylase in tumor was markedly increased four hours after treatment with DHP107. The apoptotic effects, assessed using TUNEL and soft agar colony-formation assay on xenograft tumors, were greater with combined treatment than with either agent used alone. The antitumor effects of DHP107 were similar to those of Taxol in gastric cancer xenografts. These data indicate that DHP107 combined with capecitabine had enhanced antitumor effects in human gastric tumor xenografts and that DHP107 had antitumor effects in gastric cancer models, both of which provide support for future clinical trials of DHP107.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2539. doi:10.1158/1538-7445.AM2011-2539
Abstract 2545: Roles of BIM induction and survivin down-regulation in lapatinib-induced apoptosis in breast cancer cells with HER2 amplification
Authors: Tanizaki Junko , Okamoto Isamu , Fumita Soichi , Okamoto Wataru , Nakagawa Kazuhiko
Published: June 2012

Breast cancer is the leading cause of cancer death among women worldwide. Amplification of the human epidermal growth factor receptor 2 (HER2) gene occurs in 25 to 30% of breast cancers, and HER2 is thus an attractive target for the development of therapeutic drugs. Lapatinib, a dual tyrosine kinase inhibitor of HER2, is clinically active in patients with breast cancer positive for HER2 amplification. The mechanism of this antitumor action has remained unclear, however. Although lapatinib improved the overall outcome for such patients, not all patients benefited from the treatment. Characterization of the molecular basis of the response to lapatinib will thus be important to maximize the clinical efficacy of this drug. Mutations in PIK3CA, which encodes the p110α catalytic subunit of phosphatidylinositol 3-kinase (PI3K), have been identified in 8 to 40% of breast cancers. Although a positive correlation between HER2 overexpression and the presence of PIK3CA mutations has been described, the relation between the efficacy of lapatinib and such mutations has remained unclear. We have now investigated the effects of lapatinib in HER2 amplification-positive breast cancer cells with or without an activating PIK3CA mutation. By using immunoblot analysis and Annexin V assay, we found that lapatinib induced apoptosis in association with up-regulation of the proapoptotic protein BIM through inhibition of the MEK-ERK signaling pathway in breast cancer cells with HER2 amplification. RNA interference-mediated depletion of BIM inhibited lapatinib-induced apoptosis, implicating BIM induction in this process. The proapoptotic effect of lapatinib was less pronounced in cells with a PIK3CA mutation than in those without one. Lapatinib failed to inhibit AKT phosphorylation in PIK3CA mutant cells, likely because of hyperactivation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway by the mutation. Depletion of PIK3CA (a catalytic subunit of PI3K) by si-RNA revealed that survivin expression is regulated by the PI3K pathway in these cells, suggesting that insufficient inhibition of PI3K-survivin signaling is responsible for the limited proapoptotic effect of lapatinib in HER2 amplification-positive cells with a PIK3CA mutation. Consistent with this notion, depletion of survivin by RNA interference or treatment with a PI3K inhibitor markedly increased the level of apoptosis in PIK3CA mutant cells treated with lapatinib. Our results thus suggest that inhibition of both PI3K-survivin and MEK-ERK-BIM pathways is required for effective induction of apoptosis in breast cancer cells with HER2 amplification.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2545. doi:10.1158/1538-7445.AM2011-2545
Abstract 2549: Efficacy of the Chk1 inhibitor PF-00477736 and pemetrexed in human mesothelioma
Authors: Blasina Alessandra , Hallin Jill F. , Tan Wei , Los Gerrit , Jani Jitesh P.
Published: June 2012

Malignant pleural mesothelioma (MPM) is a highly aggressive malignancy with the median survival of less than 1 year from diagnosis. Pemetrexed (PTX), a multi-targeted antifolate drug in combination with cisplatin, has been used as front-line treatment. PTX-treatments causes S-phase cell cycle arrest allowing cancer cells to repair damaged DNA critical for cell survival and proliferation. The Chk1 kinase, a central regulator of cell cycle progression and a principal mediator of cell cycle checkpoints in response to genotoxic stress is overexpressed in mesothelioma. We evaluated the in-vitro activity of the Chk1 kinase inhibitor, PF-00477736, in combination with PTX in MPM. PF-00477736 treatments abrogated the PTX-induced S-phase cell cycle arrest and enhanced cytotoxicity of PTX in a dose-dependent manner (∼81% cell proliferation inhibition, vs. ∼13% with PTX alone). PTX and PF-00477736 treatments alone enhanced the levels of γH2AX (6% and 16%, respectively), however, their combination had significantly higher effect (∼60% increase) compared to control cells. These results suggest that when Chk1 is inhibited, PTX-induced replication stress is converted into additional DNA damage due to checkpoint abrogation and lack of DNA repair. The sensitization of mesothelioma cells to PTX by PF-00477736 was also associated with a marked increase in apoptosis (∼11-fold increase compared to PTX of PF-00477736 treatments alone). Collectively, these results show a therapeutic potential of combining Chk1 inhibitors and PTX for the treatment of mesothelioma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2549. doi:10.1158/1538-7445.AM2011-2549
Abstract 255: GRB7 – a novel target in triple-negative breast cancer
Authors: Giricz Orsi , Pero Stephanie C. , Krag David N. , Sparano Joseph A. , Kenny Paraic A.
Published: June 2012

Triple-negative breast tumors lack expression of estrogen and progesterone receptors and HER2, rendering them non-responsive to the most effective targeted therapies in breast cancer. These tumors are typically more aggressive than other breast cancer subtypes and, consequently, have a poor prognosis. In a clinical trial of triple-negative breast cancer patients treated with anthracyclines and taxanes, we and others have recently determined that high levels of GRB7 are predictive of tumor recurrence. GRB7 is a cytoplasmic adaptor protein that interacts with receptor tyrosine kinases and integrins, transducing information to their downstream signaling cascades.

In this study, we have tested the hypothesis that triple-negative breast cancer cell lines are dependent on GRB7 for migration, invasion and colony formation in 3D culture. Using a highly specific peptide inhibitor (G7-18NATE), we found that the GRB7 inhibition significantly impaired each of these phenotypes in four triple-negative breast cancer cell lines: MDA-MB-468, MDA-MB-231, HCC70 and T4-2. In addition, we have tested whether GRB7 inhibition may sensitize these cell lines to the chemotherapies used in the initial clinical trial. Combination treatment with G7-18NATE and doxorubicin or docetaxel resulted in cooperative cell growth inhibition in each of the four cell lines. Co-treatment lowered the IC40 of both chemotherapeutic agents, and it proved to be synergistic in all cases (Combination Index values <1)

These data implicate GRB7 as a key mediator of migration, invasion, colony growth and chemoresistance of triple-negative breast cancer cells and suggest that GRB7 itself, or GRB7-dependent pathways, may prove to be important targets therapeutic.

This work was supported in part by Susan G. Komen for the Cure (KG091136).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 255. doi:10.1158/1538-7445.AM2011-255
Abstract 2560: The CK2 inhibitor CX-4945 enhances the antitumor activity of EGFR-targeted agents by attenuating signaling in the PI3K/AKT/mTOR pathway
Authors: Bliesath Josh , Drygin Denis , Streiner Nicole , Ho Caroline , Siddiqui-Jain Adam , Proffitt Chris , Omori May , Huser Nanni , O'Brien Sean , Anderes Kenna
Published: June 2012

The epidermal growth factor receptor (EGFR) regulates several oncogenic signaling pathways including PI3K/AKT/mTOR, MEK/ERK, and STAT. A number of EGFR antagonists have been approved for treatment of late-stage tumors of epithelial origin. Despite these advances, there are several limitations to these therapies, including primary and acquired resistance, prompting the need to combine EGFR antagonists with agents that target pathways downstream of EGFR. CK2 modulates multiple pro-proliferative and pro-survival signals through many of these same signaling pathways, and co-overexpression of EGFR and CK2 has been frequently observed in solid tumors. Here we present the combination of EGFR-targeted agents with CX-4945, a first-in-class selective CK2 inhibitor currently under evaluation in a Phase I clinical trial. CK2 phosphorylates several key proteins at multiple levels within the PI3K/AKT/mTOR signaling pathway including AKT, PTEN, and p70S6K1. CK2 also regulates the Hsp90/Cdc37 machinery, whose clients include EGFR, AKT, and Src. We proposed that top-down inhibition of EGFR, combined with lateral inhibition of the PI3K/ATK/mTOR pathway by CX-4945, would result in an improved cancer therapy compared to EGFR antagonism alone. This hypothesis was tested in vitro and in vivo in A431 squamous cell carcinoma (SCC) and non-small cell lung carcinoma (NSCLC) models of various genetic backgrounds. Signaling pathways and induction of apoptosis were analyzed by western blot and cell proliferation was measured in a 96-hour cell viability assay. The combination of CX-4945 and erlotinib resulted in enhanced reduction in phosphorylation of AKT (T308), AKT (S473), PRAS40 (S246), mTOR (S2481), mTOR (S2448), p70S6K1 (T389), S6 (S235/6), S6 (240/4), and 4E-BP1 (T37/46), and decreased Mcl-1 levels. These effects were accompanied by decreased cell proliferation and synergistic induction of apoptosis. CX-4945 plus erlotinib exhibited enhanced antitumor activity in A431 SCC and NCI-H2170 NSCLC xenograft models; moreover, in the erlotinib-resistant NCI-H1975 NSCLC xenograft model, CX-4945 plus cetuximab resulted in enhanced efficacy. These data suggest that CX-4945 in combination with EGFR-targeted agents may improve clinical outcomes in patients with EGFR and CK2-driven cancers by inhibiting multiple nodes of the EGFR signaling pathway.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2560. doi:10.1158/1538-7445.AM2011-2560