Caspase-dependent generation of reactive oxygen species in human astrocytoma cells contributes to resistance to TRAIL-mediated apoptosis

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF family of cytokines, causes apoptosis by caspase activation in various cell types, particularly in transformed cells. Numerous types of tumors are relatively resistant to TRAIL-induced cytotoxicity; however, the reasons for this are not yet fully understood. We report here a new signal transduction pathway involving protein kinase Cdelta (PKCdelta), NADPH oxidase 4 (NOX4) and reactive oxygen species (ROS), that inhibits caspase-dependent cell death induced by TRAIL ligation in human malignant astrocytoma cells. In our experiments, TRAIL ligation-induced generation of intracellular ROS through caspase-dependent proteolytic activation of PKCdelta and subsequent activation of the NOX4 complex. Suppression of intracellular ROS induction using various pharmacological inhibitors or PKCdelta- or NOX4-specific RNA interference enhanced the enzymatic activity of caspase-3 by blocking the oxidative modification of its catalytic cysteine residue, resulting in marked augmentation of TRAIL-mediated cell death. These results collectively indicate that TRAIL-induced activation of PKCdelta and NOX4 can modulate TRAIL-mediated apoptosis by promoting oxidative modification of active caspase-3 in a negative-feedback manner.

Geographic variation in organ availability is responsible for disparities in liver transplantation between Hispanics and Caucasians

The aims of this study were to determine whether disparities in waiting list outcomes exist for Hispanics and African Americans during the post-MELD era, and to investigate interactions between disparities and geography. Scientific Registry of Transplant Recipients data were used to compare Hispanics and African Americans to Caucasians listed between 2003 and 2008. Endpoints included (i) receipt of a liver transplant and (ii) death or removal from the waiting list for being too sick or medically unsuitable. Adjustment for possible confounders was performed using multivariate Cox regression, with adjustment for geographic variation using a fixed-effects multilevel model. In multivariate analysis, African Americans have similar hazard of transplantation and death/removal as Caucasians during the post-MELD era. However, Hispanics are less likely to receive a transplant than Caucasians despite adjustment for potential confounders (HR 0.80, 95% CI 0.77-0.83), while having a similar hazard of death/removal. This effect disappeared after adjusting for unequal regional distribution of Hispanics, who represent 8% of patients in donation service areas (DSAs) having median waiting times of < or = 155 days versus 19% in DSAs with median waiting times of >155 days. In conclusion, disparities in liver transplantation exist for Hispanics during the post-MELD era, caused by geographic variation in organ availability.

Reporting 678 putative cSNPs from full-length enriched cDNA sequences of the Korean native pig

Sequences from the clones of full-length enriched cDNA libraries serve as valuable resources for functional genomic studies. We have analysed 1970 high-quality chromatograms (Phred value >or= 30) that were obtained from sequencing the 5' ends of brainstem, liver, neocortex and spleen clones derived from full-length enriched cDNA libraries from Korean native pigs. In addition, 50,000 pig expressed sequence tag (EST) sequence trace files were obtained from Genbank and combined with our sequencing information to facilitate SNP identification in silico. The process generated 8118 contigs, of which 239 included minimum one sequence from Korean native pig and contained 678 putative coding single nucleotide polymorphisms (cSNPs). Of these, 33 putative cSNPs were randomly selected for confirmatory analysis and validated using 20 pigs from four different breeds (Duroc, Landrace, Yorkshire, Korean native pig). Of the 33 putative cSNPs, 20 were confirmed (61%), which was similar to the frequency reported in other studies. We also identified 15 new cSNPs from the validation process, which were not detected by our in silico analysis. Our study shows that analysing genetically diverse pig breeds including the Korean native pig could serve as a useful strategy for generating a large number of cSNPs.

A randomized phase II study of perifosine (P) plus imatinib for patients with imatinib-resistant gastrointestinal stromal tumor (GIST)

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Background: P inhibits activation of the Akt pathway which results in apoptosis and block cancer cell proliferation. Since AKT is a molecule downstream of Kit, its inhibition may overcome Kit-dependent imatinib resistance. We performed a phase II trial to assess antitumor activity of perifosine in patients with advanced GIST who were refractory to imatinib mesylate. Methods: Pts with Kit(+) advanced GIST who have PD on IM were eligible. Pts continued their current dose of IM and were randomized to one of two dosing schedules of P (Arm A: 100 mg p.o. qd x 28 + IM or Arm B: 900 mg [300 mg p.o tid] qweekly + qd IM). A Bayesian approach was utilized to assess a target response rate or 20% with an unacceptable toxicity rate of 15% or less. Response was measured at q8 wk intervals by RECIST and Choi criteria. The primary endpoint was to determine the efficacy of P with IM in pts with advanced GIST with PD while receiving IM. Results: From 8/2005 to 7/2008, 41 pts were accrued. After 1 pt exclusion and 2 cross-overs, 22 pts were in Arm A and 18 pts in Arm B. Median age was 58 (range, 32–82), 51% were male, and median ECOG PS was 1. The most common primary site of disease and metastasis was the stomach (29%) and liver (66%), respectively. KIT genotype was available for 22 pts(54%); 5(12%) WT, 13(32%) exon 11 mutations, and 4(10%) exon 9 mutations. The median number of cycles was 2 (range, 1–24). By Choi and RECIST, 30 pts(73%) and 36 pts(87%) were available for response, respectively. No CR was identified but the PR rate was 4/36 (11%) by Choi (4 PR, 9 SD) and 0/36 (0%) by RECIST (16 SD). 4/5 (80%) of pts with WT KIT appeared to benefit (Choi: 1 PR, 3 SD; RECIST: 4 SD). Median PFS and OS for 40 pts were 2.2 months and 18.3 months. No difference in PFS was noted for the 2 schedules. Toxicity was assessed in 39 pts; 46 grade 3 events and 4 grade 4 events (ALT elevation, blurred vision, fatigue, and mood alteration) were noted. The most common grade 3 event was fatigue (20%). Three pts (7%) were removed from the study for toxicity (Arm A:1 pt, Arm B:2 pts). Conclusions: The addition of P to IM has minimal activity in IM-refractory GIST although its activity in GIST with WT KIT may be further investigated.

No significant financial relationships to disclose.

Neoadjuvant therapy of gastric cancer with cetuximab added to both irinotecan and cisplatin, followed by surgical resection and adjuvant chemoradiation

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Background: We previously demonstrated the efficacy of irinotecan (CPT) and cisplatin (Cis) combination therapy as neoadjuvant therapy for locally advanced gastric cancer [Newman E et al. J Gastrointest Surg. 2002.]. This trial was designed to add cetuximab (C) to both induction treatment and adjuvant chemoradiation (CRT) with bolus 5-FU/LV. Methods: Pts with untreated locally advanced (T3, T4 or N+) gastric/GE cancers were eligible. Neoadjuvant therapy consisted of Cis 25mg/m2 + CPT 75mg/m2 on d1,8 q21d x 4, C 400mg/m2 on d1, then 250mg/m2 qwk. Curative (R0) resection was performed 4–6 wks later. Adjuvant CRT with 5-FU/LV (425/20/m2 qd x 5 on wks 1,14,19; 400/20/m2 qd x 4 on wk 5, x 3 on wk 9) was given with C 250mg/m2 qwk. Results: Since 11/05, 21 pts [median age 59 (32–82); 9 Caucasian, 11 Asian, 1 Hispanic; 15 male, 20 PS 0–1] received neoadjuvant therapy. The most common toxicities were gr 3 neutropenia (38%), gr 2 rash (33%), gr 2 fatigue (29%); gr 4 included 1 pt each of diarrhea, neutropenia, & hypomagnesemia. 3 did not complete neoadjuvant therapy, due to gr 3 rash, diarrhea and GI bleeding (2 had gastrectomy; 1 lost to f/u). All 18 pts who completed neoadjuvant therapy were surgically explored. 4 had occult metastases, and went off study. 14 underwent R0 gastrectomy (see table); 8 were downstaged, 2 had stable disease, 4 were upstaged compared to the preoperative EUS. There was no postoperative mortality. Of 14 resected pts, 2 did not receive adjuvant therapy (prolonged postoperative recovery), 1 too early to assess, and 11 remaining receiving CRT. The most common toxicities for CRT were gr 3 nausea, gr 3 emesis, gr 2 and 3 fatigue, 3 pts each and 1 each of gr 4 neutropenia and thrombocytopenia. Among the 18 pts who completed neoadjuvant therapy, 5 died of disease, 1 is alive with disease, 12 remain NED with median f/u of 11.6mos (4.1–27.7mos). Conclusions: The addition of C to CPT/Cis as neoadjuvant therapy and to postoperative adjuvant CRT is well tolerated. The regimen induces a favorable pathologic response on the primary tumor. Ongoing evaluation includes K-ras mutation status on outcome and survival benefit. [Supported in part by a grant from BMS.]

[Table: see text]