Wafik S El-Deiry

Publications of Wafik S El-Deiry

• High-resolution imaging and antitumor effects of GFP(+) bone marrow-derived cells homing to syngeneic mouse colon tumors.

  Authors: Niklas K Finnberg, Lori S Hart, Nathan G Dolloff, Zachary B Rodgers, David T Dicker, Wafik S El-Deiry

  The American journal of pathology. 11/2011; 179(5):2169-76.

  Bone marrow-derived cells (BMDCs) participate in the growth and spread of tumors of the breast, brain, lung, and stomach. To date, there are limited reports of bone marrow involvement in colon cancerBone marrow-derived cells (BMDCs) participate in the growth and spread of tumors of the breast, brain, lung, and stomach. To date, there are limited reports of bone marrow involvement in colon cancer pathogenesis, but such findings would have the potential to generate novel treatments for colon cancer patients. We have established a mouse model for imaging BMDCs from whole tumor to single-cell resolution, whereby the bone marrow of lethally irradiated host animals is reconstituted with EGFP-expressing bone marrow cells from matched TgActb(EGFP) donors. The BM transplants yield mice with fluorescently labeled bone marrow, and so BMDCs can subsequently be monitored within a tumor through optical imaging. Successful BM reconstitution was confirmed at 8 weeks after transplantation, when surviving BALB/c mice were injected with CT26 mouse colon cancer cells. We find that up to 45% of cells dissociated from the tumors are GFP(+) and approximately 50% of Lin(+), CD11b(+), and CD3(+) cells express high levels of GFP. Notably, tumor growth is reduced in BM transplanted animals, compared with untransplanted host mice or EGFP-expressing BM donor mice. A needed next step is to separate the molecular and cellular (eg, T cells, NK cells, macrophages) bases of the antitumor effect of the BMDCs from any protumorigenic effect that could be subverted for therapeutic gain.

• Preliminary observations indicate variable patterns of plasma 5-fluorouracil (5-FU) levels during dose optimization of infusional 5-FU in colorectal cancer patients.

  Authors: Christina Leah Kline, Hassan S Sheikh, Angelique Scicchitano, Rebecca Gingrich, Cheryl Beachler, Niklas K Finnberg, Jason Liao, Jeffrey Sivik, Wafik S El-Deiry

  Cancer biology & therapy. 10/2011; 12(7):557-68.

  Efforts to improve efficacy and minimize toxicity have led to pharmacokinetic monitoring of plasma 5-Fluorouracil (5-FU) levels in colorectal cancer patients undergoing chemotherapy. We observedEfforts to improve efficacy and minimize toxicity have led to pharmacokinetic monitoring of plasma 5-Fluorouracil (5-FU) levels in colorectal cancer patients undergoing chemotherapy. We observed variation in basal 5-FU levels in 21 patients and significant variation during subsequent dose optimization. Tumor KRAS, BRAF mutations and TS mRNA levels were determined. Regimens included FOLFOX6 + Avastin (N = 8), FOLFOX6 (N = 11), FOLFIRI (N = 1) and FOLFOX4 (N = 1). Mutations identified in tumors included G12V KRAS (N = 2), G12A KRAS (N = 1), and V600E BRAF (N = 3). Six-of-eleven patients with normalized tumor TS mRNA levels < 4.0 had a 5-FU AUC of 20 mg.h/L or greater, and 80% of patients (4 of 5) with TS levels > 4.0 had a plasma 5-FU AUC of less than or equal to 20 mg.h/L. Approximately 2/3 of patients achieved therapeutic 5-FU AUC levels with 0-2 dose adjustments while a sub-group of ~1/3 of patients slowly achieved therapeutic levels (> 3-4 dose increases leading to supra-therapeutic 5-FU and subsequent reductions to lesser than original doses). Liver metastases and tumor TS levels did not fully account for variable 5-FU AUC optimization patterns. The 5-FU level during continuous infusion was half-therapeutic in one patient who received FOLFOX4. The observed heterogeneous patterns at baseline and during dose optimization of 5-FU levels suggest variations in 5-FU metabolism among treated patients. Physiological and/or genetic differences underlying heterogeneity in 5-FU levels during dose optimization require further study of patient demographics, single nucleotide polymorphisms in Dihydropyrimidine Dehydrogenase (DPD), TS, or other genes that impact 5-FU metabolism and gene expression changes in liver after 5-FU therapy.

• Identification and enumeration of circulating tumor cells in the cerebrospinal fluid of breast cancer patients with central nervous system metastases.

  Authors: Akshal S Patel, Joshua E Allen, David T Dicker, Kristi L Peters, Jonas M Sheehan, Michael J Glantz, Wafik S El-Deiry

  Oncotarget. 10/2011; 2(10):752-60.

  The number of circulating tumor cells (CTCs) in the peripheral blood of metastatic breast cancer patients is now an established prognostic marker. While the central nervous system is a common site ofThe number of circulating tumor cells (CTCs) in the peripheral blood of metastatic breast cancer patients is now an established prognostic marker. While the central nervous system is a common site of metastasis in breast cancer, the standard marker for disease progression in this setting is cerebrospinal fluid (CSF) cytology. However, the significance of CSF cytology is unclear, requires large sample size, is insensitive and subjective, and sometimes yields equivocal results. Here, we report the detection of breast cancer cells in CSF using molecular markers by adapting the CellSearch system (Veridex). We used this platform to isolate and enumerate breast cancer cells in CSF of breast cancer patients with central nervous system (CNS) metastases. The number of CSF tumor cells correlated with tumor response to chemotherapy and were dynamically associated with disease burden. This CSF tumor cell detection method provides a semi-automated molecular analysis that vastly improves the sensitivity, reliability, objectivity, and accuracy of detecting CSF tumor cells compared to CSF cytology. CSF tumor cells may serve as a marker of disease progression and early-stage brain metastasis in breast cancer and potentiate further molecular analysis to elucidate the biology and significance of tumor cells in the CSF.

• Hyperspectral imaging: a non-invasive method of imaging melanoma lesions in a patient with stage IV melanoma, being treated with a RAF inhibitor.

  Authors: David T Dicker, Nadia Kahn, Keith T Flaherty, Jeremy Lerner, Wafik S El-Deiry

  Cancer biology & therapy. 08/2011; 12(4):326-34.

  Utilizing a macroscopic Prism and Reflectance Imaging Spectroscopy System (MACRO-PARISS), spectral data are taken from human skin using a fiber optic light probe. The subject was an oncology patientUtilizing a macroscopic Prism and Reflectance Imaging Spectroscopy System (MACRO-PARISS), spectral data are taken from human skin using a fiber optic light probe. The subject was an oncology patient at the University of Pennsylvania, with biopsy proven melanoma, who underwent chemotherapy with a novel small molecule BRAF inhibitor as part of a Phase I clinical trial. The BRAF mutation had been previously identified in this patient. Cutaneous lesions were identified by a clinical oncologist, and lesions were imaged periodically over a 1 month period of time. Spectra are classified using a linearity-independent algorithm over a wavelength range of 450-920 nm. Spectral signatures, or characteristic features, of generated spectra correlate with gross features of lesions that are readily observable. Using PARISS we demonstrated differences between spectral signatures of treated lesions over a treatment course, indicating spectral data correlation with changes in disease. PARISS may be useful to better establish a noninvasive means of following disease progression, and ultimately establish characteristic spectral signatures to define disease presence in the future.

• Prediction of proapoptotic anticancer therapeutic response in vivo based on cell death visualization and TRAIL death ligand-receptor interaction.

  Authors: LanLan Zhou, Wenge Wang, David T Dicker, Robin C Humphreys, Wafik S El-Deiry

  Cancer biology & therapy. 08/2011; 12(4):335-48.

  Tumor growth is often associated with insufficient apoptosis. The Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) and its proapoptotic receptors death receptor 4 (DR4) and DR5Tumor growth is often associated with insufficient apoptosis. The Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) and its proapoptotic receptors death receptor 4 (DR4) and DR5 agonistic monoclonal antibodies are being developed as targeted therapeutics because they kill cancer cells while sparing normal cells. A challenge to targeted therapeutics is the selection of patients who are most likely to benefit from targeted drugs because of the heterogeneity of cancer. Molecular imaging may be useful in targeted drug development by assessing the target expression and drug-target interaction, and for predicting therapeutic response. We hypothesized that the cell surface expression level of DR4/5 may predict the proapoptotic targeted therapeutic response if the signaling pathway downstream is intact. The goal of this proof-of-concept study was to develop a molecular imaging strategy to predict proapoptotic anti-cancer therapy response at an early stage of treatment. TRAIL and the DR5 agonistic monoclonal antibody HGS-ETR2 (Lexatumumab, TRM-2) were labeled with a near-infrared dye and these were used to image the TRAIL receptors on cultured TRAIL sensitive and TRAIL resistant human tumor cells as well as tumor xenografts. Imaging of cells and tumor-bearing animals was conducted with near infrared fluorescence imagers and apoptosis in cells was assessed by western blots of PARP-cleavage and flow cytometry of sub-G1 content. Apoptosis in tumors was evaluated by imaging near-infrared dye-labeled Annexin V and tumor tissue activated caspase-3 staining. Both in vitro and in vivo studies showed that imaging of death inducing ligand-receptor interaction was consistent with the apoptosis readout. Thus TRAIL sensitive tumors that express TRAIL receptors underwent cell death following treatment whereas tumors lacking TRAIL receptor expression were shown to be TRAIL resistant. In vivo molecular imaging of TRAIL receptor expression correlated with response to TRAIL therapy and an apoptotic response in vivo.

• Spectral imaging-based methods for quantifying autophagy and apoptosis.

  Authors: Nathan G Dolloff, Xiahong Ma, David T Dicker, Robin C Humphreys, Lin Z Li, Wafik S El-Deiry

  Cancer biology & therapy. 08/2011; 12(4):349-56.

  Spectral imaging systems are capable of detecting and quantifying subtle differences in light quality. In this study we coupled spectral imaging with fluorescence and white light microscopy toSpectral imaging systems are capable of detecting and quantifying subtle differences in light quality. In this study we coupled spectral imaging with fluorescence and white light microscopy to develop new methods for quantifying autophagy and apoptosis. For autophagy, we employed multispectral imaging to examine spectral changes in the fluorescence of LC3-GFP, a chimeric protein commonly used to track autophagosome formation. We found that punctate autophagosome-associated LC3-GFP exhibited a spectral profile that was distinctly different from diffuse cytosolic LC3-GFP. We then exploited this shift in spectral quality to quantify the amount of autophagosome-associated signal in single cells. Hydroxychloroquine (CQ), an anti-malarial agent that increases autophagosomal number, significantly increased the punctate LC3-GFP spectral signature, providing proof-of-principle for this approach. For studying apoptosis, we employed the Prism and Reflector Imaging Spectroscopy System (PARISS) hyperspectral imaging system to identify a spectral signature for active caspase-8 immunostaining in ex vivo tumor samples. This system was then used to rapidly quantify apoptosis induced by lexatumumab, an agonistic TRAIL-R2/DR5 antibody, in histological sections from a preclinical mouse model. We further found that the PARISS could accurately distinguish apoptotic tumor regions in hematoxylin and eosin-stained sections, which allowed us to quantify death receptor-mediated apoptosis in the absence of an apoptotic marker. These spectral imaging systems provide unbiased, quantitative and fast means for studying autophagy and apoptosis and complement the existing methods in their respective fields.

• Quinacrine synergizes with 5-fluorouracil and other therapies in colorectal cancer.

  Authors: Jean-Nicolas Gallant, Joshua E Allen, Charles D Smith, David T Dicker, Wenge Wang, Nathan G Dolloff, Arunasalam Navaraj, Wafik S El-Deiry

  Cancer biology & therapy. 08/2011; 12(3):239-51.

  Although treatments have improved patient prognosis in surgically resectable colorectal cancer, new effective drugs with improved safety profiles are needed to improve the currently poor outcomes ofAlthough treatments have improved patient prognosis in surgically resectable colorectal cancer, new effective drugs with improved safety profiles are needed to improve the currently poor outcomes of patients with recurrent or metastatic colorectal cancer. Quinacrine, a small molecule anti-malarial agent that has activity in giardiasis, lupus, prion disease, and used as a means of non-surgical sterilization, has shown cytotoxic activity across a broad range of cancers. Here, we evaluate the potential of adding quinacrine to anticancer chemotherapeutics and targeted agents as a potential novel combinatorial therapy for advanced colon cancer. We show that quinacrine synergizes with 5-fluorouracil and significantly enhances the cytotoxicity of sorafenib in a panel of 10 human colorectal cancer cell lines, including those with KRAS mutations protein gel blot analysis confirmed that quinacrine's anticancer activity partially arises from its ability to stabilize p53 and lower anti-apoptotic protein levels. In a series of in vivo studies, quinacrine monotherapy lowered the tumor load of nu/nu mice bearing human colorectal cancer xenografts. In combination, quinacrine and 5-Fluorouracil significantly delayed tumor growth of a variety of different xenografts, as compared to each agent administered alone. Our results suggest that the administration of quinacrine in combination with chemotherapeutic agents and targeted agents should be further explored in patients with recurrent, locally advanced, or metastatic colorectal cancer.

• Quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapeutic agents.

  Authors: Wenge Wang, Jean-Nicolas Gallant, Sharyn I Katz, Nathan G Dolloff, Charles D Smith, Junaid Abdulghani, Joshua E Allen, David T Dicker, Bo Hong, Arunasalam Navaraj, Wafik S El-Deiry

  Cancer biology & therapy. 08/2011; 12(3):229-38.

  Quinacrine has been widely explored in treatment of malaria, giardiasis, and rheumatic diseases. We find that quinacrine stabilizes p53 and induces p53-dependent and independent cell death. TreatmentQuinacrine has been widely explored in treatment of malaria, giardiasis, and rheumatic diseases. We find that quinacrine stabilizes p53 and induces p53-dependent and independent cell death. Treatment by quinacrine alone at concentrations of 10-20 mM for 1-2 d cannot kill hepatocellular carcinoma cells, such as HepG2, Hep3B, Huh7, which are also resistant to TRAIL. However, quinacrine renders these cells sensitive to treatment by TRAIL. Co-treatment of these cells with quinacrine and TRAIL induces overwhelming cell death within 3-4 h. Levels of DR5, a pro-apoptotic death receptor of TRAIL, are increased upon treatment with quinacrine, while levels of Mcl-1, an anti-apoptotic member of the Bcl-2 family, are decreased. While the synergistic effect of quinacrine with TRAIL appears to be in part independent of p53, knockdown of p53 in HepG2 cells by siRNA results in more cell death after treatment by quinacrine and TRAIL. The mechanism by which quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapies, and the potential for clinical application currently are being further explored. Lastly, quinacrine synergizes with chemotherapeutics, such as adriamycin, 5-FU, etoposide, CPT11, sorafenib, and gemcitabine, in killing hepatocellular carcinoma cells in vitro and the drug enhances the activity of sorafenib to delay tumor growth in vivo.

• Human colon cancer stem cells are enriched by insulin-like growth factor-1 and are sensitive to figitumumab.

  Authors: Lori S Hart, Nathan G Dolloff, David T Dicker, Constantinos Koumenis, James G Christensen, Adda Grimberg, Wafik S El-Deiry

  Cell cycle (Georgetown, Tex.). 07/2011; 10(14):2331-8.

  Cancer stem cells (CSCs) are recognized as contributors to cancer progression and therapeutic resistance in liquid and solid malignancies. We analyzed a panel of human colon cancer cell lines for CSCCancer stem cells (CSCs) are recognized as contributors to cancer progression and therapeutic resistance in liquid and solid malignancies. We analyzed a panel of human colon cancer cell lines for CSC populations by side population and aldehyde dehydrogenase activity. IGF-1 enriches these putative colon CSC populations in a β-catenin-dependent manner. Chemical inhibition of Akt depletes SP cells, and conversely, the overexpression of a constitutively active mutant version of Akt is sufficient to enrich CSC populations. CP-751,871, a fully human antibody with specificity to the IGF-1 receptor, is currently being tested in clinical trials for a variety of solid tumors. CP-751,871 reduces CSC populations in colon cancer cell lines in vitro and reduces tumor growth in vivo. We have identified a novel role for IGF-1 in the enrichment of chemo-resistant CSC populations. Our results suggest that CP-751,871 has preferential activity against putative CSC populations and, therefore, may complement current standard chemotherapeutic regimens that target cycling cells.

• The relative contribution of pro-apoptotic p53-target genes in the triggering of apoptosis following DNA damage in vitro and in vivo.

  Authors: Kageaki Kuribayashi, Niklas Finnberg, John R Jeffers, Gerard P Zambetti, Wafik S El-Deiry

  Cell cycle (Georgetown, Tex.). 07/2011; 10(14):2380-9.

  The p53 pathway displays a large degree of redundancy in the expression of a number of pro-apoptotic mechanisms following DNA damage that, among others, involves increased expression of severalThe p53 pathway displays a large degree of redundancy in the expression of a number of pro-apoptotic mechanisms following DNA damage that, among others, involves increased expression of several pro-apoptotic genes through transactivation. Spatial and temporal cellular contexts contribute to the complexity of the regulation of apoptosis, hence different genes may show a cell- and tissue-dependent specificity with regard to the regulation of cell death and act in concert or show redundancy with one and another. We used siRNA technology to assess the effect of multiple ablations of documented pro-apoptotic p53 target genes (PPG) in the colorectal cancer cell line HCT116 and generated mice deficient in both of the extrinsic and intrinsic PPGs genes Dr5 and Puma following treatment with chemotherapeutics and ionizing radiation. DR5, Fas, Bax, Bad, Puma and Bnip3L were induced by 5-FU and adriamycin (ADR) in HCT116 cells in a p53-dependent manner. The resulting caspase 3/7 activity in HCT116 cells following treatment were suppressed by ablated expression of the PPGs in the extrinsic as well as the intrinsic pathway. To our surprise, knocking-down any of the PPGs concomitantly with DR5 did not further inhibit caspase 3/7 activity whereas inhibiting DR5-expression in HCT116Bax knockdown (kd) and HCT116Fas kd did, suggesting that these genes act downstream or in synergy with DR5. This was supported by our in vivo observations, since Puma and Dr5 were equally efficient in protecting cells of the spleen from sub-lethal radiation-induced apoptosis but less effective compared with irradiated p53-/- mice. To our surprise, Dr5-/-; Puma-/- mice did not show additive protection from radiation-induced apoptosis in any of the investigated organs. Our data indicates that the intrinsic pathway may rely on extrinsic signals to promote cell death in a cell- and tissue-dependent manner following DNA damage. Furthermore, p53 must rely on mechanisms independent of DR5 and PUMA to initiate apoptosis following γ-radiation in the spleen and thymus in vivo.

• FLT-PET may not be a reliable indicator of therapeutic response in p53-null malignancy.

  Authors: Sharyn I Katz, Lanlan Zhou, Thomas A Ferrara, Wenge Wang, Patrick A Mayes, Charles D Smith, Wafik S El-Deiry

  International journal of oncology. 07/2011; 39(1):91-100.

  FDG (18F-deoxy-glucose) is the current gold standard for PET imaging. FLT (3'-deoxy-3'-(18F-fluorothymidine), a PET imaging marker of proliferation, has been proposed as an alternative to FDG for theFDG (18F-deoxy-glucose) is the current gold standard for PET imaging. FLT (3'-deoxy-3'-(18F-fluorothymidine), a PET imaging marker of proliferation, has been proposed as an alternative to FDG for the assessment of therapeutic response. We examined the therapeutic predictive value of FLT-PET and FDG-PET using CALU-6, a human, p53-null, non-small cell lung cancer cell line with comparison of combined targeted therapy, TRAIL and sorafenib, versus combined conventional chemotherapy, docetaxel and cisplatin. CALU-6 tumor-bearing nu/nu mice (n=46) were evaluated in 3 therapeutic trials measuring FLT and FDG prediction of tumor response at 72 h following initiation of daily combination therapy with targeted agents, TRAIL (200 µg i.v.) and sorafenib (30 mg/kg i.p.) and compared to conventional chemotherapeutics cisplatin (3 mg/kg i.p.) and docetaxel (7.5 mg/kg i.p.). PET imaging response was compared to morphological and histological indicators of therapeutic response, including decreased vascularity (in vivo AngioSense imaging and anti-CD31 staining), slowed tumor growth (caliper measurements), decreased cellular proliferation (Ki-67 staining) and increased apoptosis (TUNEL staining). Decreases in tumor accumulation of FLT (FLTMAX -30%, p=0.03) at 72 h post treatment were observed in response to TRAIL and sorafenib combination therapy resulting in smaller, less vascular, more apoptotic tumors. No similar reduction in tumor accumulation of FLT (FLTMAX -2%, p=0.67) was observed 72 h following initiation of cisplatin and docetaxel combination therapy, despite histological and morphological evidence of drug response. In contrast, tumor imaging with FDG did demonstrate a decrease in accumulation in both treatment groups, -21% (p=0.30) in response to cisplatin/docetaxel and -8% (p=0.59) in response to TRAIL/sorafenib, but did not reach statistical significance. FLT, but not FDG, is predictive of therapeutic response to the targeted regimen TRAIL/sorafenib. However, FLT-PET may not predict therapeutic response to DNA damaging agents in p53-null tumors, likely due to loss of cell cycle control of thymidine kinase 1 (TK1). Thus, tumor imaging response by FLT may be limited in human tumors without functional p53.

• Identifying circulating tumor stem cells that matter: the key to prognostication and therapeutic targeting.

  Authors: Bishoy Faltas, Amer Zeidan, Kristi Peters, Avisnata Das, Jamal Joudeh, Arunasalam Navaraj, Nathan G Dolloff, Harold A Harvey, Yixing Jiang, Joshua E Allen, David T Dicker, Wafik S El Deiry

  Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 06/2011; 29(21):2946-7; author reply 2947-8.

• Oxaliplatin uses JNK to restore TRAIL sensitivity in cancer cells through Bcl-xL inactivation.

  Authors: Joshua E Allen, Wafik S El-Deiry

  Gastroenterology. 06/2011; 141(2):430-4.

• Off-target lapatinib activity sensitizes colon cancer cells through TRAIL death receptor up-regulation.

  Authors: Nathan G Dolloff, Patrick A Mayes, Lori S Hart, David T Dicker, Robin Humphreys, Wafik S El-Deiry

  Science translational medicine. 06/2011; 3(86):86ra50.

  Lapatinib, a dual HER2/EGFR (human epidermal growth factor receptor 2/epidermal growth factor receptor) inhibitor, is a recently approved targeted therapy for metastatic breast cancer. BecauseLapatinib, a dual HER2/EGFR (human epidermal growth factor receptor 2/epidermal growth factor receptor) inhibitor, is a recently approved targeted therapy for metastatic breast cancer. Because lapatinib enhances the efficacy of the chemotherapeutic agent capecitabine in breast cancer patients, we tested whether lapatinib also enhances the activity of anticancer agents in colorectal cancer. We found that lapatinib improved the proapoptotic effects of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and two TRAIL receptor agonists, the antibodies mapatumumab and lexatumumab. Tumors from mice treated with a combination of lapatinib and TRAIL exhibited more immunostaining for cleaved caspase-8, a marker of the extrinsic cell death pathway, than did tumors from mice treated with lapatinib or TRAIL alone. Furthermore, combination therapy suppressed tumor growth more effectively than either agent alone. Lapatinib up-regulated the proapoptotic TRAIL death receptors DR4 and DR5, leading to more efficient induction of apoptosis in the presence of TRAIL receptor agonists. This activity of lapatinib was independent of EGFR and HER2. The off-target induction of DR5 by lapatinib resulted from activation of the c-Jun amino-terminal kinase (JNK)/c-Jun signaling axis. This activity of lapatinib on TRAIL death receptor expression and signaling may confer therapeutic benefit when increased doses of lapatinib are used in combination with TRAIL receptor-activating agents.

• Overcoming hypoxia-induced apoptotic resistance through combinatorial inhibition of GSK-3β and CDK1.

  Authors: Patrick A Mayes, Nathan G Dolloff, Colin J Daniel, J Judy Liu, Lori S Hart, Kageaki Kuribayashi, Joshua E Allen, David I H Jee, Jay F Dorsey, Yingqiu Y Liu, David T Dicker, J Martin Brown, Emma E Furth, Peter S Klein, Rosalie C Sears, Wafik S El-Deiry

  Cancer research. 06/2011; 71(15):5265-75.

  Tumor hypoxia is an inherent impediment to cancer treatment that is both clinically significant and problematic. In this study, we conducted a cell-based screen to identify small molecules that couldTumor hypoxia is an inherent impediment to cancer treatment that is both clinically significant and problematic. In this study, we conducted a cell-based screen to identify small molecules that could reverse the apoptotic resistance of hypoxic cancer cells. Among the compounds, we identified were a structurally related group that sensitized hypoxic cancer cells to apoptosis by inhibiting the kinases GSK-3β and cyclin-dependent kinase (CDK) 1. Combinatorial inhibition of these proteins in hypoxic cancer cells and tumors increased levels of c-Myc and decreased expression of c-IAP2 and the central hypoxia response regulator hypoxia-inducible factor (HIF) 1α. In mice, these compounds augmented the hypoxic tumor cell death induced by cytotoxic chemotherapy, blocking angiogenesis and tumor growth. Taken together, our findings suggest that combinatorial inhibition of GSK-3β and CDK1 augment the apoptotic sensitivity of hypoxic tumors, and they offer preclinical validation of a novel and readily translatable strategy to improve cancer therapy.

• Circulating Tumor Cells and Colorectal Cancer.

  Authors: Joshua E Allen, Wafik S El-Deiry

  Current colorectal cancer reports. 10/2010; 6(4):212-220.

  The significance of circulating tumor cells (CTCs) has been discussed for more than a century. The advent of modern technology has allowed for more reliable detection of CTCs, and recent studies haveThe significance of circulating tumor cells (CTCs) has been discussed for more than a century. The advent of modern technology has allowed for more reliable detection of CTCs, and recent studies have provided compelling evidence that CTCs predict clinical response in metastatic colorectal cancer (mCRC). Combination of CTC analysis with independent prognostic factors has demonstrated powerful synergy in some studies. The ability of CTCs to predict metastasis and therapy-specific response has high potential clinical utility, with early studies showing promising results in colorectal cancer (CRC). Reliable CTC detection has also allowed for examination of tumor cell dissemination during surgery, and there appears to be a heavy dependence on the approach chosen. This review discusses the evidence for CTC significance, with particular focus on detection methods, novel markers, and clinical outcomes in CRC. Numerous opportunities exist for preclinical, clinical, and translational studies to explore molecular determinants within CTCs, as well as the value of CTCs in directing targeted therapeutics.

• TRAIL receptor signaling and therapeutics.

  Authors: Junaid Abdulghani, Wafik S El-Deiry

  Expert opinion on therapeutic targets. 10/2010; 14(10):1091-108.

  TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines, which can induce apoptotic cell death in a variety of tumor cells by engaging specific death receptors,TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines, which can induce apoptotic cell death in a variety of tumor cells by engaging specific death receptors, TRAIL-R1 and TRAIL-R2, while having low toxicity towards normal cells. There is interest in cancer therapy inducing cell death by activation of the death-receptor-mediated apoptotic pathway while avoiding decoy-receptor-mediated neutralization of the signal. This has led to the development of a number of receptor-specific TRAIL-variants and agonistic antibodies. Some of these soluble recombinant TRAIL and agonist antibodies targeting TRAIL-R1 and/or TRAIL-R2 are progressing in clinical trials. In addition, TRAIL-resistant tumors can be sensitized to TRAIL by a combination of TRAIL or agonistic antibodies with chemotherapeutic agents, targeted small molecules or irradiation. Recent advances in developing TRAIL or its agonist receptor antibodies in cancer therapy. We also discuss combination therapies in overcoming TRAIL resistance in cancer cells. Knowledge of current clinical trials, the promise and obstacles in the future development of therapies affecting TRAIL signaling pathways. Cancer therapeutics targeting the TRAIL/TRAIL receptor signaling pathway hold great promise for molecularly targeted pro-apoptotic anti-cancer therapy.

• Current strategies to target p53 in cancer.

  Authors: Fang Chen, Wenge Wang, Wafik S El-Deiry

  Biochemical pharmacology. 05/2010; 80(5):724-30.

  Tumor suppressor p53 is a transcription factor that guards the genome stability and normal cell growth. Stresses like DNA damage, oncogenic assault will turn on p53 function which leads to cell cycleTumor suppressor p53 is a transcription factor that guards the genome stability and normal cell growth. Stresses like DNA damage, oncogenic assault will turn on p53 function which leads to cell cycle arrest for DNA repair, senescence for permanent growth arrest or apoptosis for programmed cell death. At the late stage of cancer progression, p53 is hijacked in all forms of tumors either trapped in the negative regulator such as MDM2/viral proteins or directly mutated/deleted. Re-introduction of a functional p53 alone has been proven to induce tumor regression robustly. Also, an active p53 pathway is essential for effective chemo- or radio-therapy. The emerging cyclotherapy in which p53 acts as a chemoprotectant of normal tissues further expands the utility of p53 activators. Functionally, it is unquestionable that drugging p53 will render tumor-specific intervention. One direct method is to deliver the functional wild-type (wt) p53 to tumors via gene therapy. The small molecule strategies consist of activation of p53 family member such as p73, manipulating p53 posttranslational modulators to increase wt p53 protein levels, protein-protein interaction inhibitors to free wt p53 from MDM2 or viral protein, and restoring p53 function to mutant p53 by direct modulation of its conformation. Although most of the current pre-clinical leads are in microM range and need further optimization, the success in proving that small molecules can reactivate p53 marks the beginning of the clinical development of p53-based cancer therapy.

• The p53 target Plk2 interacts with TSC proteins impacting mTOR signaling, tumor growth and chemosensitivity under hypoxic conditions.

  Authors: Elizabeth M Matthew, Lori S Hart, Aristotelis Astrinidis, Arunasalam Navaraj, Nathan G Dolloff, David T Dicker, Elizabeth P Henske, Wafik S El-Deiry

  Cell cycle (Georgetown, Tex.). 12/2009; 8(24):4168-75.

  Tuberous sclerosis complex 1 (TSC1) inhibits mammalian target of rapamycin (mTOR), a central promotor of cell growth and proliferation. The protein product of the TSC1 gene, hamartin (referred to asTuberous sclerosis complex 1 (TSC1) inhibits mammalian target of rapamycin (mTOR), a central promotor of cell growth and proliferation. The protein product of the TSC1 gene, hamartin (referred to as TSC1) is known to interact with Polo-like kinase 1 (Plk1) in a cell cycle regulated, phosphorylation-dependent manner. We hypothesized that the p53 target gene, Plk2, is a tumor suppressor, mediating its tumor suppressor function through interactions with TSC1 that facilitate TSC1/2 restraint of mTOR under hypoxic stress. We found that human lung tumor cells deficient in Plk2 grew larger than control tumors, and that Plk2 interacts with endogenous TSC1 protein. Additionally, C-terminal Plk2-GST fusion protein bound both TSC1 and TSC2 proteins. TSC1 levels were elevated in response to Adriamycin and cells transiently overexpressing Plk2 demonstrated decreased phosphorylation of the downstream target of mTOR, ribosomal protein p70S6 kinase during hypoxia. Plk2 levels were inversely correlated with cytoplasmic p70S6K phosphorylation. Plk2 levels did not increase in response to DNA damage (Adriamycin, CPT -11) when HCT 116 and H460 cells were exposed to hypoxia. TSC1-deficient mouse embryonic fibroblasts with TSC1 added back demonstrated decreased S6K phosphorylation, which was further decreased when Plk2 was transiently overexpressed. Interestingly, under normoxia, Plk2 deficient tumor cells demonstrated increased apoptosis in response to various chemotherapeutic agents including CPT -11 but increased resistance to apoptotic death after CPT-11 treatment under hypoxia, and tumor xenografts comprised of these Plk2-deficient cells were resistant to CPT -11. Our results point to a novel Plk2-TSC1 interaction with effects on mTOR signaling during hypoxia, and tumor growth that may enable targeting Plk2 signaling in cancer therapy.

• Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and paclitaxel have cooperative in vivo effects against glioblastoma multiforme cells.

  Authors: Jay F Dorsey, Akiva Mintz, Xiaobing Tian, Melissa L Dowling, John P Plastaras, David T Dicker, Gary D Kao, Wafik S El-Deiry

  Molecular cancer therapeutics. 12/2009;

  Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in conjunction with microtubule-targeting agents may be a promising novel anticancer treatment strategy. In vitro studies haveTumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in conjunction with microtubule-targeting agents may be a promising novel anticancer treatment strategy. In vitro studies have suggested that relatively low concentrations of TRAIL enhance the lethality of paclitaxel (Taxol) against human cancer cells. The increased efficacy may be due to the triggering of caspase activation, resulting in mitotic checkpoint abrogation and catastrophe. We show here that wild-type p53 protects cells from caspase-dependent death induced by this therapeutic combination in vitro. We have now also developed an imaging-based model system to test the in vivo efficacy of combined TRAIL and Taxol, in which tumor growth and treatment response can be monitored noninvasively and in real-time. We further utilize bioluminescence, F(18)-fluorodeoxyglucose-positron emission tomography, and microscale computed tomography imaging to confirm the effects of combined treatment on tumors. These studies together provide the first in vivo confirmation that combined TRAIL plus paclitaxel results in better tumor control compared with either TRAIL or paclitaxel alone, and with no discernable increased normal tissue toxicity in the mouse. Interestingly, the in vivo antitumor response elicited by combined treatment was not affected by the p53 status of the tumor cells. These preclinical observations together suggest the therapeutic potential of combining TRAIL plus paclitaxel in cancer treatment, and support further preclinical and future clinical testing. [Mol Cancer Ther 2009;8(12):3285-95].