Seok Hyun Kim

Publications of Seok Hyun Kim

• Mcl-1: a gateway to TRAIL sensitization.

  Authors: Seok Hyun Kim, M Stacey Ricci, Wafik S El-Deiry

  Cancer research. 05/2008; 68(7):2062-4.

  The proapoptotic cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is being evaluated presently as a selective anticancer agent, but its limited effects against cancer cellThe proapoptotic cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is being evaluated presently as a selective anticancer agent, but its limited effects against cancer cell lines has raised some concerns about its ultimate clinical utility. Here, we review recent findings that cancer cell sensitivity to TRAIL is greatly increased when the Bcl-2 family protein Mcl-1 is down-regulated by the Raf/vascular endothelial growth factor kinase inhibitor sorafenib, a Food and Drug Administration-approved cancer drug. Using the TRAIL-sorafenib combination as a tactic to more effectively kill cancer cells may provide an effective tool to attack a variety of human cancers that are largely presently untreatable.

• Cell cycle dependent and schedule-dependent antitumor effects of sorafenib combined with radiation.

  Authors: John P Plastaras, Seok Hyun Kim, Yingqiu Y Liu, David T Dicker, Jay F Dorsey, James McDonough, George Cerniglia, Ramji R Rajendran, Anjali Gupta, Anil K Rustgi, J Alan Diehl, Charles D Smith, Keith T Flaherty, Wafik S El-Deiry

  Cancer research. 11/2007; 67(19):9443-54.

  The antineoplastic drug sorafenib (BAY 43-9006) is a multikinase inhibitor that targets the serine-threonine kinase B-Raf as well as several tyrosine kinases. Given the numerous molecular targets ofThe antineoplastic drug sorafenib (BAY 43-9006) is a multikinase inhibitor that targets the serine-threonine kinase B-Raf as well as several tyrosine kinases. Given the numerous molecular targets of sorafenib, there are several potential anticancer mechanisms of action, including induction of apoptosis, cytostasis, and antiangiogenesis. We observed that sorafenib has broad activity in viability assays in several human tumor cell lines but selectively induces apoptosis in only some lines. Sorafenib was found to decrease Mcl-1 levels in most cell lines tested, but this decrease did not correlate with apoptotic sensitivity. Sorafenib slows cell cycle progression and prevents irradiated cells from reaching and accumulating at G2-M. In synchronized cells, sorafenib causes a reversible G1 delay, which is associated with decreased levels of cyclin D1, Rb, and phosphorylation of Rb. Although sorafenib does not affect intrinsic radiosensitivity using in vitro colony formation assays, it significantly reduces colony size. In HCT116 xenograft tumor growth delay experiments in mice, sorafenib alters radiation response in a schedule-dependent manner. Radiation treatment followed sequentially by sorafenib was found to be associated with the greatest tumor growth delay. This study establishes a foundation for clinical testing of sequential fractionated radiation followed by sorafenib in gastrointestinal and other malignancies.

• Reduction of TRAIL-induced Mcl-1 and cIAP2 by c-Myc or sorafenib sensitizes resistant human cancer cells to TRAIL-induced death.

  Authors: M Stacey Ricci, Seok Hyun Kim, Kazuhiro Ogi, John P Plastaras, Jianhua Ling, Wenge Wang, Zhaoyu Jin, Yingqiu Y Liu, David T Dicker, Paul J Chiao, Keith T Flaherty, Charles D Smith, Wafik S El-Deiry

  Cancer cell. 08/2007; 12(1):66-80.

  Cells expressing oncogenic c-Myc are sensitized to TNF superfamily proteins. c-Myc also is an important factor in determining whether a cell is sensitive to TRAIL-induced apoptosis, and it is wellCells expressing oncogenic c-Myc are sensitized to TNF superfamily proteins. c-Myc also is an important factor in determining whether a cell is sensitive to TRAIL-induced apoptosis, and it is well established that the mitochondrial pathway is essential for apoptosis induced by c-Myc. We investigated whether c-Myc action on the mitochondria is required for TRAIL sensitivity and found that Myc sensitized cells with defective intrinsic signaling to TRAIL. TRAIL induced expression of antiapoptotic Mcl-1 and cIAP2 through activation of NF-kappaB. Both Myc and the multikinase inhibitor sorafenib block NF-kappaB. Combining sorafenib with TRAIL in vivo showed dramatic efficacy in TRAIL-resistant tumor xenografts. We propose the combination of TRAIL with sorafenib holds promise for further development.

• IGFBP-3 regulates esophageal tumor growth through IGF-dependent and independent mechanisms.

  Authors: Munenori Takaoka, Seok Hyun Kim, Takaomi Okawa, Carmen Z Michaylira, Douglas B Stairs, Cameron N Johnstone, Claudia D Andl, Ben Rhoades, James J Lee, Andres J P Klein-Szanto, Wafik S El-Deiry, Hiroshi Nakagawa

  Cancer biology & therapy. 05/2007; 6(4):534-40.

  Insulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophagealInsulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophageal cancer. Yet, the role of IGFBP-3 in esophageal tumor biology remains elusive. To delineate the functional consequences of IGFBP-3 overexpression, we stably transduced Ha-Ras(V12)-transformed human esophageal cells with either wild-type or mutant IGFBP-3, the latter incapable of binding Insulin-like growth factor (IGFs) as a result of substitution of amino-terminal Ile56, Leu80, and Leu81 residues with Glycine residues. Wild-type, but not mutant, IGFBP-3 prevented IGF-1 from activating the IGF-1 receptor and AKT, and suppressed anchorage-independent cell growth. When xenografted in nude mice, in vivo bioluminescence imaging demonstrated that wild-type, but not mutant IGFBP-3, abrogated tumor formation by the Ras-transformed cells with concurrent induction of apoptosis, implying a prosurvival effect of IGF in cancer cell adaptation to the microenvironment. Moreover, there was more aggressive tumor growth by mutant IGFBP-3 overexpressing cells than control cell tumors, without detectable caspase-3 cleavage in tumor tissues, indicating an IGF-independent growth stimulatory effect of mutant IGFBP-3. In aggregate, these data suggest that IGFBP-3 contributes to esophageal tumor development and progression through IGF-dependent and independent mechanisms.

• Tumorigenic conversion of primary human esophageal epithelial cells using oncogene combinations in the absence of exogenous Ras.

  Authors: Seok Hyun Kim, Hiroshi Nakagawa, Arunasalam Navaraj, Yoshio Naomoto, Andres J P Klein-Szanto, Anil K Rustgi, Wafik S El-Deiry

  Cancer research. 12/2006; 66(21):10415-24.

  To investigate pathways of human esophageal squamous cell transformation, we generated esophageal tumor cells using human telomerase- and SV40-immortalized primary esophageal epithelial cells (EPC2)To investigate pathways of human esophageal squamous cell transformation, we generated esophageal tumor cells using human telomerase- and SV40-immortalized primary esophageal epithelial cells (EPC2) by overexpression of selected combinations of oncogenes. H-Ras, c-Myc, or Akt, but not epidermal growth factor receptor (EGFR), induced transformed colonies in soft agar. By contrast, bioluminescence imaging of genetically altered immortalized esophageal cells revealed that Akt, EGFR, or H-Ras, but not c-Myc, resulted in tumor formation in immunodeficient mice. H-Ras-driven tumors showed highly tumorigenic phenotypes with 2.6 +/- 0.6 days for doubling, whereas Akt and EGFR tumors doubled every 9.5 +/- 1.6 and 6.1 +/- 1.2 days, respectively. H-Ras-driven tumors expressed the hypoxia-inducible factor target Glut1, whereas Akt- or EGFR-driven tumors had evidence of angiogenesis and no detectable Glut1 expression. Proliferation rates among these tumors were similar, but there was reduced apoptosis in the more aggressive H-Ras-driven tumors that also developed aneuploidy and multiple centrosomes. c-Myc overexpression did not result in tumorigenic conversion but introduction of Bcl-XL into c-Myc-expressing cells generated tumors. Although cytokeratin expression was typical of squamous carcinoma, gene expression profiling was done to compare the four different types of engineered tumors with human esophageal squamous cell carcinomas and adenocarcinomas. Interestingly, c-Myc plus Bcl-XL transformants mimicked squamous carcinomas, whereas H-Ras-, EGFR-, and Akt-driven tumors were similar to adenocarcinomas in their molecular profiles. These genetically engineered models may provide new platforms for understanding human esophagus cancer and may assist in the evaluation of new therapies.

• Small-molecule modulators of p53 family signaling and antitumor effects in p53-deficient human colon tumor xenografts.

  Authors: Wenge Wang, Seok Hyun Kim, Wafik S El-Deiry

  Proceedings of the National Academy of Sciences of the United States of America. 08/2006; 103(29):11003-8.

  p53 deficiency is common in almost all human tumors and contributes to an aggressive chemo- or radiotherapy-resistant phenotype, therefore providing a target for drug development. Molecular targetingp53 deficiency is common in almost all human tumors and contributes to an aggressive chemo- or radiotherapy-resistant phenotype, therefore providing a target for drug development. Molecular targeting to restore wild-type p53 activity has been attempted in drug development and has led to the identification of CP-31398, PRIMA1, and the Nutlins. However, strategies targeting p53-activated transcriptional responses or p53 family member expression in p53-deficient tumors have yet to be explored. Here we demonstrate the use of noninvasive bioluminescence imaging in a high-throughput cell-based screen of small molecules that activate p53 responses and cell death in human tumor cells carrying a mutant p53. We isolated a number of small molecules that activate p53 reporter activity, increase expression of p53 target genes such as p21(WAF1) or death receptor 5 (KILLER/DR5) of TNF-related apoptosis-inducing ligand (TRAIL), and induce apoptosis in p53-deficient cells. Some of the compounds activate a p53 response by increasing p73 expression, and knockdown of transactivating isoforms of p73 by small interfering RNA reduces their induction of p53-responsive transcriptional activity. Some compounds do not induce significant p73 expression but induce a high p53-responsive transcriptional activity in the absence of p53. In vivo experiments demonstrate potent antitumor effects of selected compounds, using either HCT116/p53(-/-) or DLD1 human colon tumor xenografts. The results establish the feasibility of a cell-based drug screening strategy targeting the p53 transcription factor family of importance in human cancer and provide lead compounds for further development in cancer therapy.

• Non-invasive fluorescence imaging of cell death in fresh human colon epithelia treated with 5-Fluorouracil, CPT-11 and/or TRAIL.

  Authors: Niklas Finnberg, Seok Hyun Kim, Emma E Furth, Jue Judy Liu, Pierre Russo, David A Piccoli, Adda Grimberg, Wafik S El-Deiry

  Cancer biology & therapy. 10/2005; 4(9):937-42.

  Apoptosis is instrumental in several physiological/pathophysiological processes and is a frequently used end-point in the development of anti-neoplastic compounds. Despite ample data on several colonApoptosis is instrumental in several physiological/pathophysiological processes and is a frequently used end-point in the development of anti-neoplastic compounds. Despite ample data on several colon cancer cell lines, little is known about the susceptibility of human colon to apoptosis following treatment with established chemotherapeutics. By treating fresh human colonic explants with 5-Fluorouracil (200 microg/ml), CPT-11 (100 microg/ml) and/or TRAIL (100 ng/ml) we readily detected a signal in situ using FITC-VAD-FMK at different time points, whereas labeling of colonic explants with EGFP-conjugated Annexin V proved less specific. Although TRAIL treatment alone appeared to cause little apoptosis in human colonic epithelia versus the control, we observed a greater number of cells undergoing apoptosis when a combination of CPT-11 and TRAIL was used as compared to either agent alone. This is the initial demonstration of TRAIL-induced apoptosis with or without a chemotherapeutic agent in fresh primary human colon epithelia explants. Thus, human colonic explants may provide a valuable reference point when candidate therapeutic compounds triggering apoptosis in colon cancer cell lines, xenografts or mouse models are developed. The results support the feasibility of developing non-invasive optical imaging strategies to detect apoptosis through direct visualization of injury to human colonic epithelia in vivo.

• Heterogeneity in non-invasive detection of apoptosis among human tumor cell lines using annexin-V tagged with EGFP or Qdot-705.

  Authors: David T Dicker, Seok Hyun Kim, Zhaoyu Jin, Wafik S El-Deiry

  Cancer biology & therapy. 10/2005; 4(9):1014-7.

  The ability to measure apoptosis in vivo and in vitro provides an invaluable tool to assess the effects of anti-cancer agents. The annexin-V binding assay has been used extensively, including in theThe ability to measure apoptosis in vivo and in vitro provides an invaluable tool to assess the effects of anti-cancer agents. The annexin-V binding assay has been used extensively, including in the clinic as a Technetium conjugate to assess response to chemo- or radio-therapy. Our results reveal that not all tumor cell lines are amenable to this assay. We investigated ten different human cancer cell lines for their staining patterns with annexin-V during apoptosis. In six human tumor cell lines (HCT116, Jurkat, FADU, PA1, SkBr3 and Saos2) annexin-V staining correlated well with another measurement of apoptosis (APOSTAIN). Four cell lines (SW480, H460, MCF7 and DLD1) showed annexin-V staining, which could not be interpreted, where APOSTAIN demonstrated a clear apoptotic population. The poor annexin-V staining of some tumor cells undergoing apoptosis was not correlated with detachment procedures or choice of apoptosis-inducing agent. Use of annexin-V tagged with EGFP or Qdot-705 can reliably detect apoptosis in some but not all human tumors undergoing apoptosis in response to chemotherapy or TRAIL.

• DR5 knockout mice are compromised in radiation-induced apoptosis.

  Authors: Niklas Finnberg, Joshua J Gruber, Peiwen Fei, Dorothea Rudolph, Anka Bric, Seok Hyun Kim, Timothy F Burns, Hope Ajuha, Robert Page, Gen Sheng Wu, Youhai Chen, W Gillies McKenna, Eric Bernhard, Scott Lowe, Tak Mak, Wafik S El-Deiry

  Molecular and cellular biology. 04/2005; 25(5):2000-13.

  DR5 (also called TRAIL receptor 2 and KILLER) is an apoptosis-inducing membrane receptor for tumor necrosis factor-related apoptosis-inducing ligand (also called TRAIL and Apo2 ligand). DR5 is aDR5 (also called TRAIL receptor 2 and KILLER) is an apoptosis-inducing membrane receptor for tumor necrosis factor-related apoptosis-inducing ligand (also called TRAIL and Apo2 ligand). DR5 is a transcriptional target of p53, and its overexpression induces cell death in vitro. However, the in vivo biology of DR5 has remained largely unexplored. To better understand the role of DR5 in development and in adult tissues, we have created a knockout mouse lacking DR5. This mouse is viable and develops normally with the exception of having an enlarged thymus. We show that DR5 is not expressed in developing embryos but is present in the decidua and chorion early in development. DR5-null mouse embryo fibroblasts expressing E1A are resistant to treatment with TRAIL, suggesting that DR5 may be the primary proapoptotic receptor for TRAIL in the mouse. When exposed to ionizing radiation, DR5-null tissues exhibit reduced amounts of apoptosis compared to wild-type thymus, spleen, Peyer's patches, and the white matter of the brain. In the ileum, colon, and stomach, DR5 deficiency was associated with a subtle phenotype of radiation-induced cell death. These results indicate that DR5 has a limited role during embryogenesis and early stages of development but plays an organ-specific role in the response to DNA-damaging stimuli.

• Bnip3L is induced by p53 under hypoxia, and its knockdown promotes tumor growth.

  Authors: Peiwen Fei, Wenge Wang, Seok Hyun Kim, Shulin Wang, Timothy F Burns, Joanna K Sax, Monica Buzzai, David T Dicker, W Gillies McKenna, Eric J Bernhard, Wafik S El-Deiry

  Cancer cell. 01/2005; 6(6):597-609.

  p53-dependent apoptosis is a major determinant of its tumor suppressor activity and can be triggered by hypoxia. No p53 target is known to be induced by p53 or to mediate p53-dependent apoptosisp53-dependent apoptosis is a major determinant of its tumor suppressor activity and can be triggered by hypoxia. No p53 target is known to be induced by p53 or to mediate p53-dependent apoptosis during hypoxia. We report that p53 can directly upregulate expression of Bnip3L, a cell death inducer. During hypoxia, Bnip3L is highly induced in wild-type p53-expressing cells, in part due to increased recruitment of p53 and CBP to Bnip3L. Apoptosis is reduced in hypoxia-exposed cells with functional p53 following Bnip3L knockdown. In vivo, Bnip3L knockdown promotes tumorigenicity of wild-type versus mutant p53-expressing tumors. Thus, Bnip3L, capable of attenuating tumorigenicity, mediates p53-dependent apoptosis under hypoxia, which provides a novel understanding of p53 in tumor suppression.

• Death induction by recombinant native TRAIL and its prevention by a caspase 9 inhibitor in primary human esophageal epithelial cells.

  Authors: Seok Hyun Kim, Kunhong Kim, Jae G Kwagh, David T Dicker, Meenhard Herlyn, Anil K Rustgi, Youhai Chen, Wafik S El-Deiry

  The Journal of biological chemistry. 10/2004; 279(38):40044-52.

  The cytotoxic death ligand TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is a tumor-specific agent under development as a novel anticancer therapeutic agent. However, some reportsThe cytotoxic death ligand TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is a tumor-specific agent under development as a novel anticancer therapeutic agent. However, some reports have demonstrated toxicity of certain TRAIL preparations toward human hepatocytes and keratinocytes through a caspase-dependent mechanism that involves activation of the extrinsic death pathway and Type II signaling through the mitochondria. We have isolated and purified both His-tagged protein and three versions of native recombinant human TRAIL protein from Escherichia coli. We found that 5 mm dithiothreitol in the purification process enhanced oligomerization of TRAIL and resulted in the formation of hyper-oligomerized TRAILs, including hexamers and nonomers with an extremely high potency in apoptosis induction. Although death-inducing signaling complex formation was much more efficient in cells treated with hyper-oligomerized TRAILs, this did not convert TRAIL-sensitive Type II HCT116 colon tumor cells to a Type I death pattern as judged by their continued sensitivity to a caspase 9 inhibitor. Moreover, TRAIL-resistant Type II Bax-null colon carcinoma cells were not converted to a TRAIL-sensitive Type I state by hyper-oligomerized TRAIL. Primary human esophageal epithelial 2 cells were found to be sensitive to all TRAIL preparations used, including trimer TRAIL. TRAIL-induced death in esophageal epithelial 2 cells was prevented by caspase 9 inhibition for up to 4 h after TRAIL exposure. This result suggests a possible therapeutic application of caspase 9 inhibition as a strategy to reverse TRAIL toxicity. Hyper-oligomerized TRAIL may be considered as an alternative agent for testing in clinical trials.