Enhanced Cancer Cell Apoptosis Research Articles

Abstract 1258: Bin1 enhances anoikis via p38 MAPK: A potential inhibitory role in neuroblastoma metastasis

Abstract Neuroblastoma (NB) is the most common extracranial solid tumor in children and approximately half of all children with NB are designated as high-risk patients. Most high-risk children experience metastatic recurrence despite aggressive treatment and nearly all children who relapse eventually die from disease progression. Clearly, there is a great demand for novel specific therapeutics against NB and the metastasis in particular. This relies on our understanding of the molecular mechanism that leads to metastasis. Unfortunately, this area is still largely unexplored. Based on the modern biological view of metastasis, cancer cells undergo multiple steps, including survival in circulation, to spread to distant organs. We have reported that Bin1 expression is frequently reduced in NB cell lines and forced Bin1 overexpression by transfer of an ectopic Bin1 gene into a NB cell line (SA-N-AS), designated SK-N-AS(pBin1), enhances cell death in suspension culture. This result implies that tumor cells with Bin1 loss may gain a survival advantage in blood or lymphatic system, thus allowing for distant metastasis. We therefore hypothesized that Bin1 can suppress NB metastasis via enhancing cancer cell apoptosis in circulation. Apoptosis induced by loss of cell adhesion to the extracellular matrix (ECM) is termed anoikis. The molecular mechanism by which Bin1 enhances cell death in suspension was investigated in this study. Flow cytometric analysis of floating SK-N-AS(pBin1) cells revealed that the nature of Bin1-enhanced cell death is anoikis. The anoikis was found to be mediated by a mitogen-activated protein kinase (MAPK), p38. By use of an antibody specific for p38 phosphorylated at threonine180 and tyrosine182, we show that p38 was phosphorylated (activated) in floating SK-N-AS(pBin1) cells but not in the vector control SK-N-AS(pcDNA3). Phosphorylation of p38 at these sites was undetectable in both cell lines under an adherent condition. These results indicate that (a) p38 acts as a stress kinase in NB cells; (b) Bin1 does not stimulate p38 phosphorylation without a stress induction; and (c) Bin1 enhances anoikis, at least partly, via the p38 MAPK pathway. We also show that the MEK-ERK MAPK survival pathway was inhibited by ECM-detachment, and the inhibition is, at least in part, mediated by p38 activation because pharmacological inhibition of p38 activity in floating SK-N-AS(pBin1) reactivated this pathway. Additionally, the MEK-ERK pathway was inhibited by a specific MEK inhibitor, which provides a potentially useful therapeutic target against metastasis. In conclusion, these results identify a novel link between Bin1 and MAPK pathways in NB anoikis and provide an insight into the molecular mechanism of metastasis. Further defining the involved pathways could offer multiple novel molecular targets that can be manipulated to control NB metastasis and improve the survival for this deadly disease in young children. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1258.

A Novel Peptide Enhances Therapeutic Efficacy of Liposomal Anti-Cancer Drugs in Mice Models of Human Lung Cancer

Lung cancer is the leading cause of cancer-related mortality worldwide. The lack of tumor specificity remains a major drawback for effective chemotherapies and results in dose-limiting toxicities. However, a ligand-mediated drug delivery system should be able to render chemotherapy more specific to tumor cells and less toxic to normal tissues. In this study, we isolated a novel peptide ligand from a phage-displayed peptide library that bound to non-small cell lung cancer (NSCLC) cell lines. The targeting phage bound to several NSCLC cell lines but not to normal cells. Both the targeting phage and the synthetic peptide recognized the surgical specimens of NSCLC with a positive rate of 75% (27 of 36 specimens). In severe combined immunodeficiency (SCID) mice bearing NSCLC xenografts, the targeting phage specifically bound to tumor masses. The tumor homing ability of the targeting phage was inhibited by the cognate synthetic peptide, but not by a control or a WTY-mutated peptide. When the targeting peptide was coupled to liposomes carrying doxorubicin or vinorelbine, the therapeutic index of the chemotherapeutic agents and the survival rates of mice with human lung cancer xenografts markedly increased. Furthermore, the targeting liposomes increased drug accumulation in tumor tissues by 5.7-fold compared with free drugs and enhanced cancer cell apoptosis resulting from a higher concentration of bioavailable doxorubicin. The current study suggests that this tumor-specific peptide may be used to create chemotherapies specifically targeting tumor cells in the treatment of NSCLC and to design targeted gene transfer vectors or it may be used one in the diagnosis of this malignancy.

A phase I trial of AEG35156 (XIAP antisense) administered as 2-hour intravenous infusions in patients with advanced tumours

3541 Background: The X-linked inhibitor of apoptosis (XIAP) is a potent anti-apoptotic protein. AEG35156 is a 2nd generation antisense oligonucleotide to human XIAP that enhances cancer cell apoptosis preclinically as a single agent and in combination with chemotherapeutics. Methods: The primary objective was to establish the maximum tolerated dose of AEG35156 given as a 2-hour infusion once weekly following 3 daily loading doses in week 1. Other objectives were to evaluate AEG35156 pharmacokinetics, XIAP inhibition, circulating apoptosis biomarkers and document anti-tumour activity. Results: Twenty-nine adult patients (16 M; 13 F) have been registered. Twenty-three have completed at least one 3-week treatment cycle at doses ranging from 60 to 500mg AEG35156. Treatment has been generally well tolerated, the most common toxicities have been grade I chills/pyrexia, rapidly reversible increases in aPTT at the end of infusion and mild transaminitis. One patient at 240mg had a silent myocardial infarction probably related to prophylactic aspirin withdrawal prior to starting protocol therapy. Three DLTs were observed at AEG35156 350mg: Grade 3 chills/lethargy (mesothelioma), grade 3 transaminitis (colon), transient grade 3 chills/tumour lysis syndrome/transaminitis (small lymphocytic lymphoma). A less intensive dosing protocol was deemed appropriate for future NHL patients and a protocol amendment excluding NHL patients from this study and permitting resumption in patients with solid tumors and including premedication with dexamethasone / acetaminophen was implemented. Dosing at AEG35156 500mg has been completed with no DLTs and the study is ongoing at 650mg. Pharmacokinetics were dose-proportional and linear from 60 to 500mg AEG35156. Mean plasma Cmax at 500mg was 55μg/mL. Decreases in XIAP mRNA have been observed in PBMCs at dose levels ≥240mg and increased levels of circulating biomarkers of apoptosis have been observed in some patients. One patient with NHL who received only a single infusion had rapid clearance of circulating tumour cells and reduction in nodal disease. Conclusions: AEG35156 can be safely delivered by 2-hour infusions and preliminary evidence of XIAP mRNA knockdown and antitumour activity in lymphoma has been observed. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Aegera Therapeutics Inc. Aegera Therapeutics Inc. Aegera Therapeutics Inc. Aegera Therapeutics Inc.

CSE1L/CAS, a microtubule-associated protein, inhibits taxol (paclitaxel)-induced apoptosis but enhances cancer cell apoptosis induced by various chemotherapeutic drugs

CSE1L/CAS, a microtubule-associated, cellular apoptosis susceptibility protein, is highly expressed in various cancers. Microtubules are the target of paclitaxel-induced apoptosis. We studied the effects of increased or reduced CAS expression on cancer cell apoptosis induced by chemotherapeutic drugs including paclitaxel. Our results showed that CAS overexpression enhanced apoptosis induced by doxorubicin, 5-fluorouracil, cisplatin, and tamoxifen, but inhibited paclitaxel-induced apoptosis of cancer cells. Reductions in CAS produced opposite results. CAS overexpression enhanced p53 accumulation induced by doxorubicin, 5-fluorouracil, cisplatin, tamoxifen, and etoposide. CAS was associated with alpha-tubulin and beta-tubulin and enhanced the association between alpha-tubulin and beta-tubulin. Paclitaxel can induce G2/M phase cell cycle arrest and microtubule aster formation during apoptosis induction, but CAS overexpression reduced paclitaxel-induced G2/M phase cell cycle arrest and microtubule aster formation. Our results indicate that CAS may play an important role in regulating the cytotoxicities of chemotherapeutic drugs used in cancer chemotherapy against cancer cells.

A phase I trial of AEG35156 (XIAP antisense) administered as a continuous intravenous infusion in patients with advanced tumors

3059 Background: The X-linked inhibitor of apoptosis (XIAP) is a potent anti-apoptotic protein. AEG35156 is a synthetic 2nd generation antisense oligonucleotide to human XIAP that enhances cancer cell apoptosis preclinically as a single agent and in combination with chemotherapeutics. Methods: The primary objective was to establish the maximum tolerated dose (MTD) of AEG35156 given as a 7-day continuous infusion every 3 weeks. Other objectives were to determine AEG35156 pharmacokinetics, XIAP inhibition in peripheral blood mononuclear cells and in tumour cells where feasible and document anti-tumour activity. Results: Sixteen adult patients have completed at least one 7-day infusion. Two dose-limiting toxicities (DLT) were observed in five patients treated at 160 mg/m2/day: grade 3 thrombocytopenia for more than 7 days and grade 3 ALT and AST elevation. Seven patients have been treated at 125 mg/m2/day with one DLT of grade 3 transaminase elevation. An approximately 50% decrease in XIAP mRNA was seen in peripheral blood leucocytes three days after the start of infusions at 160mg/m2/day. One patient with small lymphocytic non-Hodgkin’s lymphoma had marked but short lived decreases in peripheral lymphoblasts during AEG35156 administration closely associated with XIAP mRNA knockdown. One patient with breast cancer had an unconfirmed partial response. The trial has now been amended to also determine the MTD of a 3-day continuous infusion every 3 weeks. Three patients have been treated with 3-day infusions at 160mg/m2/day every 3 weeks with no significant toxicities observed and patients are currently being accrued at 213mg/m2/day. Conclusions: AEG35156 can be safely delivered by continuous infusion and preliminary evidence of XIAP mRNA knockdown and antitumour activity has been observed. [Table: see text]