Emetine enhances the tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis of pancreatic cancer cells by downregulation of myeloid cell leukemia sequence-1 protein

Although the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising cancer therapeutic agent, it shows limited efficacy in human pancreatic cancer cells. Protein synthesis inhibition has been reported to sensitize cancer cells to apoptosis-inducing agents, but the detailed mechanism by which protein synthesis inhibition sensitize cells to TRAIL has not been determined. To investigate the mechanism underlying pancreatic cancer cell resistance to TRAIL, we performed a small scale high-throughput compound screening in AsPC-1 pancreatic cancer cells using a bioactive small molecule library. We identified 8 compounds that reproducibly sensitize AsPC-1 cells to TRAIL-induced apoptosis. One of these compounds, emetine hydrochloride, when combined with subtoxic concentrations of TRAIL, induced massive apoptosis in AsPC-1 and BxPC-3 pancreatic cancer cells. Cell death analysis revealed that the sensitizing effects of emetine were specific to TRAIL. Emetine downregulated the expression of the TRAIL-related anti-apoptotic protein Mcl-1 in a dose- and time-dependent manner. Furthermore, specific knockdown of Mcl-1 using small interfering RNA without emetine treatment sensitized pancreatic cancer cells to TRAIL. Emetine sensitization of pancreatic cancer cells to TRAIL via Mcl-1 was confirmed under hypoxic conditions. Taken together, these findings strongly suggest that Mcl-1 is involved in pancreatic cancer cell resistance to TRAIL, and emetine facilitates the apoptosis of TRAIL-tolerant pancreatic cancer cells by specifically inhibiting Mcl-1 function.

p34 is a novel regulator of the oncogenic behavior of NEDD4-1 and PTEN

PTEN is one of the most frequently mutated or deleted tumor suppressors in human cancers. NEDD4-1 was recently identified as the E3 ubiquitin ligase for PTEN; however, a number of important questions remain regarding the role of ubiquitination in regulating PTEN function and the mechanisms by which PTEN ubiquitination is regulated. In the present study, we demonstrated that p34, which was identified as a binding partner of NEDD4-1, controls PTEN ubiquitination by regulating NEDD4-1 protein stability. p34 interacts with the WW1 domain of NEDD4-1, an interaction that enhances NEDD4-1 stability. Expression of p34 promotes PTEN poly-ubiquitination, leading to PTEN protein degradation, whereas p34 knockdown results in PTEN mono-ubiquitination. Notably, an inverse correlation between PTEN and p34/NEDD4-1 levels was confirmed in tumor samples from colon cancer patients. Thus, p34 acts as a key regulator of the oncogenic behavior of NEDD4-1 and PTEN.

Down-Regulation of Survivin by Nemadipine-A Sensitizes Cancer Cells to TRAIL-Induced Apoptosis

The tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family of cytokines. TRAIL selectively induces apoptotic cell death in various tumors and cancer cells, but it has little or no toxicity in normal cells. Agonism of TRAIL receptors has been considered to be a valuable cancer-therapeutic strategy. However, more than 85% of primary tumors are resistant to TRAIL, emphasizing the importance of investigating how to overcome TRAIL resistance. In this report, we have found that nemadipine-A, a cell-permeable L-type calcium channel inhibitor, sensitizes TRAIL-resistant cancer cells to this ligand. Combination treatments using TRAIL with nemadipine-A synergistically induced both the caspase cascade and apoptotic cell death, which were blocked by a pan caspase inhibitor (zVAD) but not by autophagy or a necrosis inhibitor. We further found that nemadipine-A, either alone or in combination with TRAIL, notably reduced the expression of survivin, an inhibitor of the apoptosis protein (IAP) family of proteins. Depletion of survivin by small RNA interference (siRNA) resulted in increased cell death and caspase activation by TRAIL treatment. These results suggest that nemadipine-A potentiates TRAIL-induced apoptosis by down-regulation of survivin expression in TRAIL resistant cells. Thus, combination of TRAIL with nemadipine-A may serve a new therapeutic scheme for the treatment of TRAIL resistant cancer cells, suggesting that a detailed study of this combination would be useful.

SU-E-J-68: An Optical Image Guidance System: To Detect Arbitrarily Attached Markers Behind a Full Facemask

PURPOSE

We developed an optical image guidance system to manage patient's inter-fractional set-up errors by tracking external markers at the specific positions (e.g., nose tip) behind a full facemask. However, a problem associated with the reproducibility of the marker positions during the entire course of treatments still remains. In order to remove this disadvantage, we applied the arbitrary-point-to-plane registration method to our existing system.

METHODS

Infra-red (IR) reflecting markers were attached on arbitrary positions of the head phantom's face and then the phantom was immobilized by a full face thermoplastic mask. 3D coordinates of the IR markers behind the full facemask were reconstructed by the calibrated stereo camera system using the direct linear transform (DLT) algorithm. In order to match arbitrarily attached markers with a planning CT image, rough positions of three markers were manually defined (rough registration) and then the coordinates of all markers were determined through the point-to-plane registration using the contractive projection point (CPP) algorithm (fine registration). In addition, the marker registration error in 6 DOF was calculated. In order to validate accuracy of the system, the phantom was intentionally moved according to 10 sets of known translation parameters.

RESULTS

A mean target registration error (TRE) determined by the experiments for arbitrarily attached markers was 1.24 ± 0.32 mm. The fine registration following the rough registration allowed fast and robust registrations.

CONCLUSIONS

The proposed solution for arbitrarily attached markers behind a full facemask enables us to avoid any daily errors in attaching the external markers at the specific positions. This work was supported in part by the SNU interdisciplinary project (2009-2010) and the SNU Brain Fusion project (2010-2011).

Calibration of the neutron detectors for the cluster fusion experiment on the Texas Petawatt Laser

Three types of neutron detectors (plastic scintillation detectors, indium activation detectors, and CR-39 track detectors) were calibrated for the measurement of 2.45 MeV DD fusion neutron yields from the deuterium cluster fusion experiment on the Texas Petawatt Laser. A Cf-252 neutron source and 2.45 MeV fusion neutrons generated from laser-cluster interaction were used as neutron sources. The scintillation detectors were calibrated such that they can detect up to 10(8) DD fusion neutrons per shot in current mode under high electromagnetic pulse environments. Indium activation detectors successfully measured neutron yields as low as 10(4) per shot and up to 10(11) neutrons. The use of a Cf-252 neutron source allowed cross calibration of CR-39 and indium activation detectors at high neutron yields (∼10(11)). The CR-39 detectors provided consistent measurements of the total neutron yield of Cf-252 when a modified detection efficiency of 4.6×10(-4) was used. The combined use of all three detectors allowed for a detection range of 10(4) to 10(11) neutrons per shot.

Abstract 2879: Pre-clinical characterization of Dacomitinib, an irreversible pan-HER inhibitor, combined with radiation therapy in head and neck cancer models

Introduction: Head and neck cancer is the 5th most common cancer worldwide; the majority of cases (>90%) are squamous cell carcinomas (SCCHNs). Despite advances in treatment, the 5-year overall survival rate for SCCHN patients still remains at ∼40-50%, underscoring the need to develop novel therapeutic strategies. EGFR is over-expressed in ∼90% of SCCHN cases, and is associated with tumor progression and poor prognosis. Dacomitinib (D), an irreversible pan-HER inhibitor, has demonstrated clinical potential in patients with non-small cell lung cancer, leading us to explore its therapeutic efficacy in SCCHN pre-clinical models, in combination with radiation therapy (RT), a curative modality for HNC management. Methods: The basal expression of EGFR family members was assessed via qRT-PCR in three SCCHN models (FaDu (human hypopharyngeal), UTSCC-8 & -42a (both laryngeal) squamous cancer, and NOE (normal oral epithelial) cell lines. MTS-based cell viability and clonogenic assays were performed with various concentrations of D, both alone and in combination with irradiation (IR). Inhibition of EGFR signalling by D was confirmed via immunoblotting. Cell cycle analysis was performed to assess mode of cytotoxicity. In vivo therapeutic studies were performed using FaDu xenografts in SCID mice; tumors were extracted post-treatment and examined for TUNEL, CD31, Ki67, and pEGFR via IHC. Results: EGFR was over-expressed in all three SCCHN, compared to the NOE cells. PF (50 nM) reduced FaDu cell viability by ∼25%, with an additive interaction being observed when D was combined with 2 Gy IR (∼36%). Similar trends were observed in the other two cell lines and also in the clonogenic assays. Immunoblotting confirmed a dose-dependent inhibition of EGFR signalling in D-treated SCCHN cells, along with downstream reduction of p-Erk, p-Akt, and p-mTOR expression. Cell cycle analyses showed ∼20% increase in the G0/G1 cell population in D-treated FaDu cells, and ∼10% increase in the sub-G cell population when D and IR were combined. Mice treated with the combination of D + IR exhibited a maximum tumor growth delay of ∼21 days, as compared to the IR only group, determined by time to tumor-plus-leg diameter of 14mm. Preliminary histological analysis of the extracted tumor tissue show ∼40% reduction in Ki67 staining in the PF + IR treated mice. The addition of D to IR appeared to be well-tolerated, with no change in body weight, or extent of alopecia. Conclusion: Dacomitinib effectively inhibited EGFR signalling in SCCHN models, leading to a reduction in cell viability and clonogenic survival in vitro, along with tumor growth delay in vivo. When D was combined with IR, there was an additive interaction, both in vitro and in vivo. Thus, D combined with RT may have a therapeutic benefit for patients with SCCHN.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2879. doi:1538-7445.AM2012-2879

Regulation in the targeting of TRAIL receptor 1 to cell surface via GODZ for TRAIL sensitivity in tumor cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptors, TRAIL-R1 (DR4) and TRAIL-R2 (DR5), promote the selective clearing of various malignancies by inducing apoptosis, holding the promise as a potent therapeutic agent for anticancer. Though DR4 and DR5 have high sequence similarity, differential regulation of both receptors in human tumor cells remains largely unexplored. Here, we repot that golgi-specific Asp-His-His-Cys (DHHC) zinc finger protein (GODZ) regulates TRAIL/DR4-mediated apoptosis. Using the SOS protein recruitment-yeast two-hybrid screening, we isolated GODZ that interacted with the death domain of DR4. GODZ binds to DR4, but not to DR5, through the DHHC and the C-terminal transmembrane domain. Expression level of GODZ affects apoptosis of tumor cells triggered by TRAIL, but not that induced by TNF-α/cycloheximide (CHX) or DNA-damaging drugs. In parallel, GODZ functions to localize DR4 to the plasma membrane (PM) via DHHC motif. Also, introduction of mutation into the cysteine-rich motif of DR4 results in its mistargeting and attenuates TRAIL- or GODZ-mediated apoptosis. Interestingly, GODZ expression is highly downregulated in Hep-3B tumor cells, which show resistance to TRAIL. However, reconstitution of GODZ expression enhances the targeting of DR4 to cell surface and sensitizes Hep-3B cells to TRAIL. Taken together, these data establish that GODZ is a novel DR4-selective regulator responsible for targeting of DR4 to the PM, and thereby for TRAIL-induced apoptosis.

Iris Nertschinskia ethanol extract differentially induces cytotoxicity in human breast cancer cells depending on AKT1/2 activity

Recently, we reported that an ethanol extract of Iris nertschinskia induces p53-dependent apoptosis in the MCF7 human breast cancer cell line. However, the detailed mechanisms were not fully explored. Here, we demonstrate another aspect of the activity of I. nertschinskia in breast cancer cells. We compared the response to an ethanol extract of I. nertschinskia in two different human breast cancer cell lines, Hs578Tand MDA-MB231, respectively with relatively low and high AKT1/2 activity by trypan blue exclusion assay and FACS analysis. Knockdown of endogenous AKT1 or AKT2 in breast cancer cells by RNA interference determined the sensitivity to I. nertschinskia ethanol extract compared to control cells. The I. nertschinskia ethanol extract induced cell death in a manner that depended on the level of phosphorylated AKT1/2 protein and was associated with a significant increase in the sub-G1 cell population, indicative of apoptosis. Our results indicate that an ethanol extract of I. nertschinskia differentially induces cell death in breast cancer cells depending on their level of phosphorylated AKT1/2.

P4-11-20: Observational Study of Body Weight Changes and Metabolic Syndrome in Breast Cancer Patients Receiving Adjuvant Therapy: Characteristics of Dietary Pattern in Korean Breast Cancer Patients

Backgroud: Obesity, postdiagnosis weight gain, and presence of metabolic syndrome in breast cancer are reported to adversely affect survival among breast cancer survivors. Most of the studies on weight gain and metabolic syndrome in breast cancer are from Western countries and few information is available on Asian population. We designed this prospective observational study to characterize weight and metabolic changes during adjuvant treatment in women with early breast cancer and to identify factors associated with occurrence of metabolic syndrome, focusing on dietary pattern.

Methods: Patients aged 18–75 who underwent curative surgery with stage I-III invasive breast cancer were enrolled from 2008 to 2010. We measured glucose (FBS), hemoglobin A1c (HbA1c), total cholesterol (TC), HDL cholesterol, and triglyceride (TG) level in fasting serum samples before starting adjuvant therapy, at 6 months and 12 months after enrollment. Body weight, body mass index (BMI), body fat mass, and percent body fat at baseline, 6 months, and 12 months were also measured. Dietary intake was assessed using valid semi-quantitative Food frequency questionnaire (FFQ).

Results: Total of 63 patients were enrolled. Median age of the enrolled patients were 48 (range, 25–68), with premenopausal/postmenopausal 40 (63.5%)/ 23 (36.5%). Fifty (82.0%) and 10 (16.4%) received adjuvant chemotherapy followed by hormone therapy and hormone therapy alone. Hormone receptor positive (ER+/PR+) and HER2 positive cancer accounted for 52 (83.9%) and 7 (12.1%). Mean FBS, HbA1c, TC, HDL, and TG level was 99.9 mg/dL (range, 83–159), 5.59 mg/dL (range, 4.8−7.5), 197.4 mg/dL (125-298), 51.9 mg/dL (range, 30–90), and 119.7 mg/dL (42-371). Mean height, weight, and BMI was 158 cm (range, 149–169), 61.7kg (range, 46.2−96.0), and 24.7 kg/m2 (range, 18.7−35.7), respectively. According to the WHO and NTH guidelines for Asian, normal (BMI 18.5−22.9), overweight (BMI 23–24.9), and obesity (BMI≥25) was 18 (28.6%), 13 (20.6%), and 32 (50.8%), respectively. Number of patients with metabolic syndrome was 18 (34%). Mean BMI (26.1 vs 24.0, p=0.021) and TG (180.6 vs 92.0, p<0.001) was higher, HDL cholesterol was lower (42.2 vs 57.3, p<0.001) in patients with metabolic syndrome. Composition of daily calorie intake consisted of 13.5% (range 10.7−21.8) of protein, 6.7% (range, 3.3−22.1) of fat, and 70.1% (range, 28.1−79.5) of carbohydrate. The presence of metabolic syndrome was associated with a higher carbohydrate intake (carbohydrate intake per ideal body weight>6.0) (p=0.071). The TG level of patients who indigested high carbohydrate was significantly higher (143.8 vs 102.9, p=0.023). The HDL level of patients who took high fat diet (>20% of total calorie) was lower (45.3 vs 53.5, p=0.045).

Conclusion: In our cohort of Korean breast cancer patients, 34% had metabolic syndrome at baseline. Those patients with metabolic syndrome consumed higher proportion of carbohydrate, which resulted in significantly higher level of TG. Our data suggest that composition of calorie intake is different in Asian population compared to Western countries, warranting for reappraisal on the recommendation on life style modification and diet.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-11-20.

Uroporphyrinogen decarboxylase is a radiosensitizing target for head and neck cancer

Head and neck cancer (HNC) is the eighth most common malignancy worldwide, comprising a diverse group of cancers affecting the head and neck region. Despite advances in therapeutic options over the last few decades, treatment toxicities and overall clinical outcomes have remained disappointing, thereby underscoring a need to develop novel therapeutic approaches in HNC treatment. Uroporphyrinogen decarboxylase (UROD), a key regulator of heme biosynthesis, was identified from an RNA interference-based high-throughput screen as a tumor-selective radiosensitizing target for HNC. UROD knockdown plus radiation induced caspase-mediated apoptosis and cell cycle arrest in HNC cells in vitro and suppressed the in vivo tumor-forming capacity of HNC cells, as well as delayed the growth of established tumor xenografts in mice. This radiosensitization appeared to be mediated by alterations in iron homeostasis and increased production of reactive oxygen species, resulting in enhanced tumor oxidative stress. Moreover, UROD was significantly overexpressed in HNC patient biopsies. Lower preradiation UROD mRNA expression correlated with improved disease-free survival, suggesting that UROD could potentially be used to predict radiation response. UROD down-regulation also radiosensitized several different models of human cancer, as well as sensitized tumors to chemotherapeutic agents, including 5-fluorouracil, cisplatin, and paclitaxel. Thus, our study has revealed UROD as a potent tumor-selective sensitizer for both radiation and chemotherapy, with potential relevance to many human malignancies.