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ABSTRACT: A delicate balance between cell death and survival pathways maintains normal physiology, which is altered in many cancers, shifting the balance toward increased survival. Several studies have established a close connection between the Wnt/beta-catenin pathway and tumorigenesis, aberrant activation of which might contribute toward increased cancer cell growth and survival. Extensive research is underway to identify therapeutic agents that can induce apoptosis specifically in cancer cells with minimal collateral damage to normal cells. Although tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis specifically in tumor cells, many cancer cells develop resistance, which can be overcome by combinatorial treatment with other agents: for example, peroxisome proliferator-activated receptor gamma (PPARgamma) ligands. To identify the molecular target mediating combinatorial drug-induced apoptosis, we focused on beta-catenin, a protein implicated in oncogenesis. Our results show that co-treatment of TRAIL-resistant cancer cells with TRAIL and the PPARgamma ligand troglitazone leads to a reduction of beta-catenin expression, coinciding with maximal apoptosis. Modulation of beta-catenin levels via ectopic overexpression or small interference RNA-mediated gene silencing modulates drug-induced apoptosis, indicating involvement of beta-catenin in regulating this pathway. More in-depth studies indicated a post-translational mechanism, independent of glycogen synthase kinase-3beta activity regulating beta-catenin expression following combinatorial drug treatment. Furthermore, TRAIL- and troglitazone-induced apoptosis was preceded by a cleavage of beta-catenin, which was complete in a fully apoptotic population, and was mediated by caspases-3 and -8. These results demonstrate beta-catenin as a promising new target of drug-induced apoptosis, which can be targeted to sensitize apoptosis-resistant cancer cells.
Journal of Biological Chemistry 04/2009; 284(20):13577-88. · 4.77 Impact Factor
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ABSTRACT: Mixed lineage kinase 3 (MLK3) is a mitogen-activated protein kinase kinase kinase member that activates the c-Jun N-terminal kinase (JNK) pathway. Aberrant activation of MLK3 has been implicated in neurodegenerative diseases. Similarly, glycogen synthase kinase (GSK)-3beta has also been shown to activate JNK and contribute to neuronal apoptosis. Here, we show a functional interaction between MLK3 and GSK-3beta during nerve growth factor (NGF) withdrawal-induced cell death in PC-12 cells. The protein kinase activities of GSK-3beta, MLK3, and JNK were increased upon NGF withdrawal, which paralleled increased cell death in NGF-deprived PC-12 cells. NGF withdrawal-induced cell death and MLK3 activation were blocked by a GSK-3beta-selective inhibitor, kenpaullone. However, the MLK family inhibitor, CEP-11004, although preventing PC-12 cell death, failed to inhibit GSK-3beta activation, indicating that induction of GSK-3beta lies upstream of MLK3. In GSK-3beta-deficient murine embryonic fibroblasts, ultraviolet light was unable to activate MLK3 kinase activity, a defect that was restored upon ectopic expression of GSK-3beta. The activation of MLK3 by GSK-3beta occurred via phosphorylation of MLK3 on two amino acid residues, Ser(789) and Ser(793), that are located within the C-terminal regulatory domain of MLK3. Furthermore, the cell death induced by GSK-3beta was mediated by MLK3 in a manner dependent on its phosphorylation of the specific residues within the C-terminal domain by GSK-3beta. Taken together, our data provide a direct link between GSK-3beta and MLK3 activation in a neuronal cell death pathway and identify MLK3 as a direct downstream target of GSK-3beta. Inhibition of GSK-3 is thus a potential therapeutic strategy for neurodegenerative diseases caused by trophic factor deprivation.
Journal of Biological Chemistry 11/2007; 282(42):30393-405. · 4.77 Impact Factor
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ABSTRACT: Tumor lysis syndrome (TLS) is a manifestation of metabolic disturbances that can lead to severe treatment complications and ultimately life-threatening events. This syndrome has been reported in solid tumors but is more common in bulky, hyperproliferative malignancies. Tumor lysis syndrome in plasma cell malignancies is less common due to the low turnover rate of the malignant B cells. Bortezomib is the first proteasome inhibitor approved by the United States Food and Drug Administration as second- and third-line therapy for patients with relapsed multiple myeloma. We describe the case of a patient with plasma cell leukemia treated with bortezomib who developed TLS. Bortezomib was begun as single-agent therapy that resulted in the development of TLS after the third dose of the first cycle. Evaluation with the Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship between TLS and bortezomib in this patient. Patients receiving bortezomib may be at risk for TLS, especially if they have high tumor burden, rapidly proliferative disease, and unfavorable cytogenetics.
Pharmacotherapy 01/2006; 25(12):1820-5. · 2.90 Impact Factor
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ABSTRACT: Standard approaches to the treatment of malignancies include surgery, chemotherapy, and radiation. More recently, with understanding of these processes in molecular detail, biologics have become another important aspect of treatment. Conjugate toxins are biologics that combine a potent toxin with a peptide that will target cancer cells with minimal damage to normal tissues. This review will detail examples of these conjugate toxins and their targeted malignancies.
Seminars in Oncology 01/2006; 32(6):591-5. · 3.50 Impact Factor
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ABSTRACT: Our study evaluated the effectiveness of neoadjuvant chemotherapy and concomitant chemotherapy with radiotherapy compared to standard surgery and radiation therapy in patients with resectable stage III/IV head and neck squamous cell carcinoma. Forty-two eligible patients received neoadjuvant chemotherapy (cisplatin 100 mg/m2 intravenously day 1, and 5-fluorouracil 1 g/m2 /day continuous infusion days 1-5 every 3 weeks for 3 courses) followed by radiotherapy (65-70 Gy in 32-39 fractions to the primary site and lymph nodes; 50 Gy in 25-28 fractions to areas at risk) and concomitant chemotherapy (cisplatin 80 mg/m 2 intravenously every 3 weeks starting on day 1 of radiotherapy). Neoadjuvant therapy induced grade 4 cytopenias (12/42 patients) and grade 4 gastrointestinal toxicities (7/42 patients). Concomitant radiochemotherapy-induced grade 4 toxicities (6 patients). Neoadjuvant chemotherapy biopsy-proven complete responses were 15 of 42 patients (36%), partial responses in 23 of 42 patients (55%), and an overall response rate of 91%. Thirty-seven of 38 responders received concomitant radiochemotherapy. Complete responses in 35 of 42 patients (83%), partial response in 7 of 42 patients (7%), and overall response in 90%. The 3-year disease-free and overall survival for chemotherapy plus radiotherapy versus surgery plus radiotherapy: 61% versus 43% (P = 0.17) and 71% versus 43% (P = 0.02). These data suggest that a randomized trial of concomitant radiochemotherapy versus neoadjuvant plus concomitant radiochemotherapy should be considered. EBM rating: B-2.
Otolaryngology Head and Neck Surgery 02/2005; 132(1):69-74. · 1.72 Impact Factor
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ABSTRACT: Monoclonal antibody-directed therapy has been used as an effective treatment for some cancers that overexpress HER2/neu and vascular endothelial growth factor (VEGF). Overexpression of the HER2/neu oncogene and VEGF has been reported to occur in adenocarcinomas of the colon. Assessing whether HER2/neu and VEGF overexpression could serve as prognostic indicators for stage II colon cancer may provide insight into optimal treatment following surgery. Demographic and tumor characteristics from 109 patients diagnosed with stage II colon cancer between 1991 and 1996 were assessed for HER2/neu and VEGF expression using immunohistochemical staining techniques. Of the 109 cases, 107 (98%) were histologically classified as adenocarcinomas, 105 (96%) were grades 2/3, and 105 (96%) were stage T3. Only 12 cases (11%) exhibited HER2/neu overexpression and 72 cases (66%) exhibited VEGF expression. There was no significant difference in overall survival or in time to recurrence between the groups with and without HER2/neu overexpression. There was a trend toward decreased overall survival with VEGF expression (P = 0.07), but no difference in time to recurrence (P = 0.63). There were 18 patients who received adjuvant chemotherapy, but removal of these patients from the analysis did not change the results. There was no association between HER2/neu and VEGF expression and patient demographics or tumor characteristics, with the exception of VEGF expression and mucinous histology (P < 0.01). Our results do not support an association between HER2/neu or VEGF expression and overall survival or time to recurrence in stage II colon cancer. With further investigation, a significant correlation may be found between VEGF expression and prognosis, and thus direct therapy with a monoclonal antibody.
Clinical Colorectal Cancer 11/2004; 4(4):262-7. · 1.68 Impact Factor
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ABSTRACT: The transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) belongs to the family of nuclear hormone receptors and consists of two isotypes, PPARgamma1 and PPARgamma2. Our earlier studies have shown that troglitazone (TZD)-mediated activation of PPARgamma2 in hepatocytes inhibits growth and attenuates cyclin D1 transcription via modulating CREB levels. Because this process of growth inhibition was also associated with an inhibition of beta-catenin expression at a post-translational level, our aim was to elucidate the mechanism involved. beta-Catenin is a multifunctional protein, which can regulate cell-cell adhesion by interacting with E-cadherin and other cellular processes via regulating target gene transcription in association with TCF/LEF transcription factors. Two adenomatous polyposis coli (APC)-dependent proteasomal degradation pathways, one involving glycogen synthase kinase 3beta (GSK3beta) and the other involving p53-Siah-1, degrade excess beta-catenin in normal cells. Our immunofluorescence and Western blot studies indicated a TZD-dependent decrease in cytoplasmic and membrane-bound beta-catenin, indicating no increase in its membrane translocation. This was associated with a reduction in E-cadherin expression. PPARgamma2 activation inhibited GSK3beta kinase activity, and pharmacological inhibition of GSK3beta activity was unable to restore beta-catenin expression following PPARgamma2 activation. Additionally, this beta-catenin degradation pathway was operative in cells, with inactivating mutations of both APC and p53. Inhibition of the proteasomal pathway inhibited PPARgamma2-mediated degradation of beta-catenin, and incubation with TZD increased ubiquitination of beta-catenin. We conclude that PPARgamma2-mediated suppression of beta-catenin levels involves a novel APC/GSK3beta/p53-independent ubiquitination-mediated proteasomal degradation pathway.
Journal of Biological Chemistry 09/2004; 279(34):35583-94. · 4.77 Impact Factor
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Journal of Biological Chemistry. 06/2004;
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ABSTRACT: Based on preclinical studies, the authors undertook a pilot study to determine the hematologic and biologic effects of pretreatment with dexamethasone (Dex) or granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients receiving carboplatin and ifosfamide. Patients (n = 28) with metastatic solid tumors were randomized to receive pretreatment with Dex or GM-CSF or no pretreatment prior to courses 1 or 2 of carboplatin and ifosfamide. No alteration in dose of chemotherapy was allowed between course 1 and 2. Alterations of hematologic and nonhematologic toxicity and selected biologic parameters were compared between courses 1 and 2. Patients without any pretreatment demonstrated worsening hematologic toxicity in course 2 compared to course 1. In contrast, Dex pretreatment reduced hematopoietic toxicity and improved the absolute granulocyte count (AGC) and platelet count recovery times. For example, course 1 versus course 2 (with Dex pretreatment): AGC nadir (mm3) 153 versus 549 (p = 0.07), days AGC <500/mm3 7.8 versus 4.0 (p = 0.10), days to AGC recovery >1,500/mm3, 26 versus 22 (p = 0.034). Overall comparison between all five cohorts by analyses of variance demonstrated that intervention with Dex improved multiple hematopoietic toxicities, including AGC nadir (p = 0.015), and recovery times to AGC >1,500/mm3 (p = 0.07) and platelet count to >100,000/mm3 (p = 0.05). GM-CSF pretreatment did not worsen hematopoietic parameters after course 2 compared to course 1. Expected biologic effects of Dex and GM-CSF treatment were observed. Patients demonstrated an overall response rate of 32%, 1 complete response, and 8 partial responses. In patients with cancer, pretreatment with Dex or GM-CSF may significantly decrease the hematopoietic toxicity of chemotherapeutic agents.
American journal of clinical oncology 10/2003; 26(5):448-58. · 2.21 Impact Factor
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ABSTRACT: Based on preclinical studies, the authors undertook a pilot study to determine the hematologic and biologic effects of pretreatment with dexamethasone (Dex) or granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients receiving carboplatin and ifosfamide. Patients (n = 28) with metastatic solid tumors were randomized to receive pretreatment with Dex or GM-CSF or no pretreatment prior to courses 1 or 2 of carboplatin and ifosfamide. No alteration in dose of chemotherapy was allowed between course 1 and 2. Alterations of hematologic and nonhematologic toxicity and selected biologic parameters were compared between courses 1 and 2. Patients without any pretreatment demonstrated worsening hematologic toxicity in course 2 compared to course 1. In contrast, Dex pretreatment reduced hematopoietic toxicity and improved the absolute granulocyte count (AGC) and platelet count recovery times. For example, course 1 versus course 2 (with Dex pretreatment): AGC nadir (mm3) 153 versus 549 (p = 0.07), days AGC <500/mm3 7.8 versus 4.0 (p = 0.10), days to AGC recovery >1,500/mm3, 26 versus 22 (p = 0.034). Overall comparison between all five cohorts by analyses of variance demonstrated that intervention with Dex improved multiple hematopoietic toxicities, including AGC nadir (p = 0.015), and recovery times to AGC >1,500/mm3 (p = 0.07) and platelet count to >100,000/mm3 (p = 0.05). GM-CSF pretreatment did not worsen hematopoietic parameters after course 2 compared to course 1. Expected biologic effects of Dex and GM-CSF treatment were observed. Patients demonstrated an overall response rate of 32%, 1 complete response, and 8 partial responses. In patients with cancer, pretreatment with Dex or GM-CSF may significantly decrease the hematopoietic toxicity of chemotherapeutic agents.
Hematopoietic suppression is a dose-limiting toxicity of many antineoplastic chemotherapeutic agents. 1,2 Post-chemotherapy administration of hematopoietic growth factors is a standard strategy aimed at enhancing the recovery of damaged bone marrow, but these treatments are expensive, frequently ineffective, and do not decrease genetic damage to hematopoietic precursors. Treatment of patients prior to chemotherapy with agents that protect the hematopoietic system may ameliorate damage to hematopoietic progenitor cells and reduce the cost associated with prolonged growth factor administration. The feasibility of this pretreatment strategy has been confirmed by studies that demonstrate the hematopoietic protective effects of amifostine. 3,4 Preclinical studies have suggested that pretreatment of patients with cancer with corticosteroids and hematopoietic growth factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) may decrease chemotherapy-induced hematopoietic toxicity. 5-17
Our murine in vivo studies demonstrated that pretreatment of animals with cortisone acetate prior to a lethal dose of carboplatin reduced the hematopoietic toxicity without reducing antitumor effects. 14-16 The hematoprotective effects of cortisone acetate were highly dose and schedule dependent. Postchemotherapy administration of cortisone acetate was completely ineffective in our murine model. Pharmacokinetic studies performed in mice demonstrated that corticosteroid blood levels producing the optimal hematoprotective effects could be achieved in patients with modest oral doses. Further studies indicated that corticosteroids induced hematopoietic stem cell resistance to carboplatin and decreased the fraction of hematopoietic precursors in S-phase. 16
GM-CSF pretreatment may also reduce hematopoietic toxicity of chemotherapeutic agents. The mechanism may involve increasing the number of hematopoietic precursors and decreasing the fraction of hematopoietic progenitor cells in S-phase below baseline. 5-9
To examine the hematoprotective, biologic, and toxic effects of corticosteroids or GM-CSF administered before carboplatin and ifosfamide, we undertook and report here a pilot study.
American Journal of Clinical Oncology 09/2003; 26(5):448-458. · 2.01 Impact Factor
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ABSTRACT: A 64-year-old woman receiving intravenous chemotherapy for stage IIIB non-small cell lung cancer experienced acute arterial thrombosis of the distal radial and entire ulnar arteries with subsequent arterial occlusion of the right popliteal artery. Two separate arterial occlusions occurred after administration of cisplatin and etoposide chemotherapy; the second occlusion occurred after rechallenge with the second cycle of chemotherapy. Although venous thrombosis is more common in patients with cancer than in the general population, chemotherapy-induced arterial thrombosis rarely has been reported. To our knowledge, peripheral arterial occlusion after the first and second cycles of platinum-based chemotherapy has not been reported in the literature.
Pharmacotherapy 10/2002; 22(9):1200-4. · 2.90 Impact Factor
