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- Belka, C., et al.
(författare)
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The tyrosine kinase Lck is required for CD95-independent caspase-8 activation and apoptosis in response to ionizing radiation
- 1999
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Ingår i: Oncogene. - : Nature Publishing Group. - 0950-9232 .- 1476-5594. ; 18:35, s. 4983-4992
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Tidskriftsartikel (refereegranskat)abstract
- Induction of apoptosis is a hallmark of cytostatic drug and radiation-induced cell death in human lymphocytes and lymphoma cells. However, the mechanisms leading to apoptosis are not well understood. We provide evidence that ionizing radiation induces a rapid activation of caspase-8 (FLICE) followed by apoptosis independently of CD95 ligand/receptor interaction. The radiation induced cleavage pattern of procaspase-8 into mature caspase-8 resembled that following CD95 crosslinking and resulted in cleavage of the proapoptotic substrate BID. Overexpression of dominant-negative caspase-8 interfered with radiation-induced apoptosis, Caspase-8 activation by ionizing radiation was not observed in cells genetically defective for the Src-like tyrosine kinase Lck, Cells lacking Lck also displayed a marked resistance towards apoptosis induction upon ionizing radiation. After retransfection of Lck, caspase-8 activation and the capability to undergo apoptosis in response to ionizing radiation was restored. We conclude that radiation activates caspase-8 via an Lck-controlled pathway independently of CD95 ligand expression, This is a novel signaling event required for radiation induced apoptosis in T lymphoma cells.
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| 3. |
- Lacas, Benjamin, et al.
(författare)
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Role of radiotherapy fractionation in head and neck cancers (MARCH) : an updated meta-analysis
- 2017
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Ingår i: The Lancet Oncology. - 1470-2045 .- 1474-5488. ; 18:9, s. 1221-1237
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Tidskriftsartikel (refereegranskat)abstract
- Background The Meta-Analysis of Radiotherapy in squamous cell Carcinomas of Head and neck (MARCH) showed that altered fractionation radiotherapy is associated with improved overall and progression-free survival compared with conventional radiotherapy, with hyperfractionated radiotherapy showing the greatest benefit. This update aims to confirm and explain the superiority of hyperfractionated radiotherapy over other altered fractionation radiotherapy regimens and to assess the benefit of altered fractionation within the context of concomitant chemotherapy with the inclusion of new trials. Methods For this updated meta-analysis, we searched bibliography databases, trials registries, and meeting proceedings for published or unpublished randomised trials done between Jan 1, 2009, and July 15, 2015, comparing primary or postoperative conventional fractionation radiotherapy versus altered fractionation radiotherapy (comparison 1) or conventional fractionation radiotherapy plus concomitant chemotherapy versus altered fractionation radiotherapy alone (comparison 2). Eligible trials had to start randomisation on or after Jan 1, 1970, and completed accrual before Dec 31, 2010; had to have been randomised in a way that precluded prior knowledge of treatment assignment; and had to include patients with non-metastatic squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx undergoing first-line curative treatment. Trials including a non-conventional radiotherapy control group, investigating hypofractionated radiotherapy, or including mostly nasopharyngeal carcinomas were excluded. Trials were grouped in three types of altered fractionation: hyperfractionated, moderately accelerated, and very accelerated. Individual patient data were collected and combined with a fixed-effects model based on the intention-to-treat principle. The primary endpoint was overall survival. Findings Comparison 1 (conventional fractionation radiotherapy vs altered fractionation radiotherapy) included 33 trials and 11 423 patients. Altered fractionation radiotherapy was associated with a significant benefit on overall survival (hazard ratio [HR] 0·94, 95% CI 0·90–0·98; p=0·0033), with an absolute difference at 5 years of 3·1% (95% CI 1·3–4·9) and at 10 years of 1·2% (−0·8 to 3·2). We found a significant interaction (p=0·051) between type of fractionation and treatment effect, the overall survival benefit being restricted to the hyperfractionated group (HR 0·83, 0·74–0·92), with absolute differences at 5 years of 8·1% (3·4 to 12·8) and at 10 years of 3·9% (−0·6 to 8·4). Comparison 2 (conventional fractionation radiotherapy plus concomitant chemotherapy versus altered fractionation radiotherapy alone) included five trials and 986 patients. Overall survival was significantly worse with altered fractionation radiotherapy compared with concomitant chemoradiotherapy (HR 1·22, 1·05–1·42; p=0·0098), with absolute differences at 5 years of −5·8% (−11·9 to 0·3) and at 10 years of −5·1% (−13·0 to 2·8). Interpretation This update confirms, with more patients and a longer follow-up than the first version of MARCH, that hyperfractionated radiotherapy is, along with concomitant chemoradiotherapy, a standard of care for the treatment of locally advanced head and neck squamous cell cancers. The comparison between hyperfractionated radiotherapy and concomitant chemoradiotherapy remains to be specifically tested. Funding Institut National du Cancer; and Ligue Nationale Contre le Cancer.
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