Facilitation of mitochondrial outer and inner membrane permeabilization and cell death in oxidative stress by a novel Bcl-2 homology 3 domain protein.

We identified a sequence homologous to the Bcl-2 homology 3 (BH3) domain of Bcl-2 proteins in SOUL. Tissues expressed the protein to different extents. It was predominantly located in the cytoplasm, although a fraction of SOUL was associated with the mitochondria that increased upon oxidative stress. Recombinant SOUL protein facilitated mitochondrial permeability transition and collapse of mitochondrial membrane potential (MMP) and facilitated the release of proapoptotic mitochondrial intermembrane proteins (PMIP) at low calcium and phosphate concentrations in a cyclosporine A-dependent manner in vitro in isolated mitochondria. Suppression of endogenous SOUL by diced small interfering RNA in HeLa cells increased their viability in oxidative stress. Overexpression of SOUL in NIH3T3 cells promoted hydrogen peroxide-induced cell death and stimulated the release of PMIP but did not enhance caspase-3 activation. Despite the release of PMIP, SOUL facilitated predominantly necrotic cell death, as revealed by annexin V and propidium iodide staining. This necrotic death could be the result of SOUL-facilitated collapse of MMP demonstrated by JC-1 fluorescence. Deletion of the putative BH3 domain sequence prevented all of these effects of SOUL. Suppression of cyclophilin D prevented these effects too, indicating that SOUL facilitated mitochondrial permeability transition in vivo. Overexpression of Bcl-2 and Bcl-x(L), which can counteract the mitochondria-permeabilizing effect of BH3 domain proteins, also prevented SOUL-facilitated collapse of MMP and cell death. These data indicate that SOUL can be a novel member of the BH3 domain-only proteins that cannot induce cell death alone but can facilitate both outer and inner mitochondrial membrane permeabilization and predominantly necrotic cell death in oxidative stress.

[Neoadjuvant radiochemotherapy in the treatment of locally advanced rectal tumors]. / Neoadjuváns radiokemoterápia a lokoregionálisan elorehaladott rectumtumorok ellátásában.

We investigated the response rate and side effects of simultaneous, neoadjuvant radiochemotherapy (RCT) in locally advanced rectal cancer. Between 2005 and 2007, we treated 112 patients in stage II-III rectal carcinoma at the Institute of Oncotherapy, University of Pécs. For staging abdomino-pelvic CT (112) and transrectal US (49) or pelvic MR (10), or PET-CT (1) was performed. Radiation therapy was delivered with 3D CRT-based technique using belly-board with 18 MV photon energy, while patients in prone position. A total dose of 45 Gy (single dose 1.8 Gy) was delivered to the tumor and the pelvic lymph nodes. 5-FU and Ca-folinate was administered concomitantly in the 1st and 5th week of radiotherapy. Four weeks after delivering neoadjuvant RCT the patients' control CT was evaluated according to RECIST criteria. RCT was followed by surgery in 6-9 weeks. We graded the histology using the Mandard regression score system. Side effects were registered using CTCAE v 3.0. Grade 1, 2 or 3 acute gastrointestinal toxicity occurred in 12%, grade 3 hematological toxicity in 9.5% of the patients. The response rate determined by using control CT was 64.85%. According to the Mandard regression score, TRG1 occurred in 15%, TRG2 in 30.4%, TRG3 in 28%, TRG4 in 24% and TRG5 in 2.6% of the cases. Radical surgery was performed in 89 cases, 72 with R0 resection. By assessing the histological samples we found downstaging in 46% of the T and 34.5% of the N stage. We have no information on increased postoperative complications. We followed 86 patients after neoadjuvant therapy. Until March 2009 there was no progression in 48 of our patients. In 13 cases local relapse occurred, and in 25 cases the disease progressed because of distant metastasis, although local control was maintained. 10 patients had local relapse and distant metastases. 17 patients passed away. As a conclusion, neoadjuvant RCT of Stage II-III patients is an effective and well tolerated treatment, allowing for high R0 resection rate and bearing no higher risk for postoperative morbidity.