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The purpose of this study was to identify the roles of non-homologous end-joining (NHEJ) or homologous recombination (HR) pathways in repairing DNA double-strand breaks (DSBs) induced by exposure to high-energy protons and carbon ions (C ions) versus gamma rays in Chinese hamster cells. Two Chinese hamster cell lines, ovary AA8 and lung fibroblast V79, as well as various mutant sublines lacking DNA-PKcs (V3), X-ray repair cross-complementing protein-4 [XRCC4 (XR1), XRCC3 (irs1SF) and XRCC2 (irs1)] were exposed to gamma rays (137Cs), protons (200 MeV; 2.2 keV/μm) and C ions (290 MeV; 50 keV/μm). V3 and XR1 cells lack the NHEJ pathway, whereas irs1 and irs1SF cells lack the HR pathway. After each exposure, survival was measured using a clonogenic survival assay, in situ DSB induction was evaluated by immunocytochemical analysis of histone H2AX phosphorylation at serine 139 (γ-H2AX foci) and chromosome aberrations were examined using solid staining. The findings from this study showed that clonogenic survival clearly depended on the NHEJ and HR pathway statuses, and that the DNA-PKcs−/− cells (V3) were the most sensitive to all radiation types. While protons and γ rays yielded almost the same biological effects, C-ion exposure greatly enhanced the sensitivity of wild-type and HR-deficient cells. However, no significant enhancement of sensitivity in cell killing was seen after C-ion irradiation of NHEJ deficient cells. Decreases in the number of γ-H2AX foci after irradiation occurred more slowly in the NHEJ deficient cells. In particular, V3 cells had the highest number of residual γ-H2AX foci at 24 h after C-ion irradiation. Chromosomal aberrations were significantly higher in both the NHEJ- and HR-deficient cell lines than in wild-type cell lines in response to all radiation types. Protons and gamma rays induced the same aberration levels in each cell line, whereas C ions introduced higher but not significantly different aberration levels. Our results suggest that the NHEJ pathway plays an important role in repairing DSBs induced by both clinical proton and C-ion beams. Furthermore, in C ions the HR pathway appears to be involved in the repair of DSBs to a greater extent compared to gamma rays and protons.

The Bragg peak properties of PBT allow for improved conformality of the treatment field. As such, large tumor volumes can be irradiated to high doses without significant dose exposure to surrounding normal tissue. Proton beam therapy therefore represents a promising modality for the treatment of large-volume HCC. Our study shows that PBT is an effective and safe method for the treatment of patients with large HCC.

SummaryMatrix vesicle-mediated mineralization is an orchestrated sequence of ultrastructural and biochemical events that lead to crystal nucleation and growth. The influx of phosphate ions into the matrix vesicle is mediated by several proteins such as TNAP, ENPP1, Pit1, annexin and so forth. The catalytic activity of ENPP1 generates pyrophosphate (PPi) using extracellular ATPs as a substrate, and the resultant PPi prevents crystal overgrowth. However, TNAP hydrolyzes PPi into phosphate ion monomers, which are then transported into the matrix vesicle through Pit1. Accumulation of Ca2+ and PO43− inside matrix vesicles then induces crystalline nucleation, with calcium phosphate crystals budding off radially, puncturing the matrix vesicle’s membrane and finally growing out of it to form mineralized nodules.

BACKGROUND:The authors have published a series of studies evaluating the safety and efficacy of proton beam therapy for the treatment of hepatocellular carcinoma in a variety of clinical settings. In the current study, they retrospectively reviewed their entire experience treating hepatocellular carcinoma patients with proton beam therapy at their hospital-based facility at the University of Tsukuba. METHODS: From November 2001 to December 2007, 333 patients with hepatocellular carcinoma were treated with proton beam therapy at the University of Tsukuba. A total of 318 patients were included in this study. Total dose delivered and fractionation scheme were determined by protocols that varied based on location of tumor. Survival rates and prognostic factors were assessed. RESULTS: Overall actuarial survival rates at 1-year, 3-years, and 5-years were 89.5% (95% confidence interval [95% CI], 85.7-93.1%), 64.7% (95% CI, 56.6-72.9%), and 44.6% (95% CI, 29.7-59.5%), respectively. Child-Pugh liver function (hazards ratio [HR], 2.84; P < .01), T stage (HR, 1.94; P < .05), performance status (HR, 2.12; P < .01), and planning target volume (HR, 2.12; P < .05) significantly impacted survival. The 3-year and 5-year survival rates were 69.1% (95% CI, 59.9-78.3%) and 55.9% (95% CI, 41.5-70.3%), respectively, for patients with Child-Pugh A disease and 51.9% (95% CI, 32.3-71.5%) and 44.5% (95% CI, 23.1-65.8%), respectively, for patients with Child-Pugh B disease. The actuarial survival rates of patients with Child-Pugh class A were statistically different between groups of planned target volume 125 mL and >125 mL (P < .05). CONCLUSIONS: The authors have shown proton beam therapy to be both safe and effective for the treatment of patients with hepatocellular carcinoma. They strongly recommend the consideration of proton beam therapy in patients for whom other treatment options are risky or contraindicated.

BackgroundBrain radiation necrosis (BRN) can be a complication of radiotherapy for primary and secondary brain tumors, as well as head and neck tumors. Since vascular endothelial growth factor (VEGF) is also a vascular permeability factor in the brain, bevacizumab, a humanized antibody that inhibits VEGF, would be expected to reduce perilesional edema that often accompanies BRN.MethodsPatients with surgically untreatable, symptomatic BRN refractory to conventional medical treatments (eg, corticosteroid, anticoagulants, or hyperbaric oxygen therapy) were enrolled. We judged that a major cause of perilesional edema with a lesion-to-normal brain ratio ≤1.8 on 11C-methionine or ≤2.5 on 18F-boronophenylalanine PET was BRN, not tumor recurrence, and 6 cycles of biweekly bevacizumab (5 mg/kg) were administered. The primary endpoint was a ≥30% reduction from the patients' registration for perilesional edema continuing for ≥1 month.ResultsOf the 41 patients enrolled, 38 were fully eligible for the response assessment. The primary endpoint was achieved in 30 of the 38 (78.9%) patients at 3.0 months (median) after enrollment. Sixteen patients (42.1%) experienced improvement of their Karnofsy Performance Score. Corticosteroid use could be reduced in 29 patients (76.3%). Adverse events at grade ≥3 occurred in 10 patients (24.4%).ConclusionsBevacizumab treatment offers certain clinical benefits for patients with surgically untreatable, symptomatic BRN. The determination of BRN using amino-acid PET, not biopsy, is adequate and less invasive for determining eligibility to receive bevacizumab.

PBT improved local control and significantly prolonged survival in HCC patients with PVTT.