Analysis of radiation-induced cell death in head and neck squamous cell carcinoma and rat liver maintained in microfluidic devices

Objective The aim of this study was to investigate how head and neck squamous cell carcinoma (HNSCC) tissue biopsies maintained in a pseudo in vivo environment within a bespoke microfluidic device respond to radiation treatment. Study Design Feasibility study. Setting Tertiary referral center. Subjects and Methods Thirty-five patients with HNSCC were recruited, and liver tissue from 5 Wistar rats was obtained. A microfluidic device was used to maintain the tissue biopsy samples in a viable state. Rat liver was used to optimize the methodology. HNSCC was obtained from patients with T1-T3 laryngeal or oropharyngeal SCC; N1-N2 metastatic cervical lymph nodes were also obtained. Irradiation consisted of single doses of between 2 Gy and 40 Gy and a fractionated course of 5×2 Gy. Cell death was assessed in the tissue effluent using the soluble markers lactate dehydrogenase (LDH) and cytochrome c and in the tissue by immunohistochemical detection of cleaved cytokeratin18 (M30 antibody). Results A significant surge in LDH release was demonstrated in the rat liver after a single dose of 20 Gy; in HNSCC, it was seen after 40 Gy compared with the control. There was no significant difference in cytochrome c release after 5 Gy or 10 Gy. M30 demonstrated a dose-dependent increase in apoptotic index for a given increase in single-dose radiotherapy. There was a significant increase in apoptotic index between 1×2 Gy and 5×2 Gy. Conclusion M30 is a superior method compared with soluble markers in detecting low-dose radiation-induced cell death. This microfluidic technique can be used to assess radiation-induced cell death in HNSCC and therefore has the potential to be used to predict radiation response

Disruption of the β1L Isoform of GABP Reverses Glioblastoma Replicative Immortality in a TERT Promoter Mutation-Dependent Manner

TERT promoter mutations reactivate telomerase, allowing for indefinite telomere maintenance and enabling cellular immortalization. These mutations specifically recruit the multimeric ETS factor GABP, which can form two functionally independent transcription factor species: a dimer or a tetramer. We show that genetic disruption of GABPβ1L (β1L), a tetramer-forming isoform of GABP that is dispensable for normal development, results in TERT silencing in a TERT promoter mutation-dependent manner. Reducing TERT expression by disrupting β1L culminates in telomere loss and cell death exclusively in TERT promoter mutant cells. Orthotopic xenografting of β1L-reduced, TERT promoter mutant glioblastoma cells rendered lower tumor burden and longer overall survival in mice. These results highlight the critical role of GABPβ1L in enabling immortality in TERT promoter mutant glioblastoma.This work was supported by a generous gift from the Dabbiere family (J.F.C.), the Hana Jabsheh Research Initiative (J.F.C.), NIH grant NCI P50CA097257 (J.F.C. and J.A.D.), NCI P01CA118816-06 (J.F.C.), T32 GM008568 and T32 CA151022 (A.M.), and NCI R01CA163336 (J.S.S.), and the Sontag Foundation Distinguished Scientist Award (J.S.S.). C.F. is supported by a US NIH K99/R00 Pathway to Independence Award (K99GM118909) from the National Institute of General Medical Sciences. Additional support was provided by Fundação para a Ciência e Tecnologia SFRH/BD/88220/2012 (A.X.-M.) and IF/00601/2012 (B.M.C.). J.A.D. is an investigator of the Howard Hughes Medical Institute.info:eu-repo/semantics/publishedVersio

X-ray diffractometry and calorimetry studies of structural modifications induced by irradiation on phosphatidylcholine multilamellar liposomes

Experimental results are reported on structural and thermodynamic modifications induced by γirradiation in model membranes. Differential scanning calorimetry (DSC) and X-ray diffraction were used to study the different phases and associated transitions of dipalmitoylphosphatidylcholine after 60Co γirradiation. Changes were observed in the shape of calorimetric peaks and in the corresponding enthalpy. The repetition distance of the layers increases while the distances related to the aliphatic chains decrease as a function of γirradiation time. Moreover, an increase in the hexagonal symmetry with increasing dose was detected. No disappearance of a pre-transition was detected even at high doses. © 1985 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Studies of structural modification induced by ã-irradiation in distearoyl- phosphatidyl- choline liposomes

An investigation of the structural and thermodynamical modifications induced by γirradiation in model membranes is reported. Differential scanning calorimetry and X-ray diffraction were used to study the different phases and associated transitions of distearoylphosphatidylcholine multilamellar liposomes after 60Co γirradiation. Changes were observed in the shape of the calorimetric peaks and in the corresponding phase transition temperatures. In particular a shoulder was observed at about 20 kGy. The three phases characteristic of lecithins with identical acyl chains were detected also for the highest radiation dose. The formation of lysolecithin and stearic acid upon phospholipid degradation was observed. The lysolecithin concentration increases as a function of irradiation dose, until a saturation value is reached at 40 kGy. These results correlate quite well with those obtained for interlayer and interchain distances and for the width of the main phase transition calorimetric peak. At the highest dose (≈80 kGy) cross-linked adjacent radicals and other molecular species are also formed. Appreciable differencies, and some similarities, in the behaviour of DSPC and DPPC liposomes under γirradiation were observed. © 1987 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Segregation of genomes in polyploid tumour cells following mitotic catastrophe

Following irradiation p53-function-deficient tumour cells undergo mitotic catastrophe and form endopolyploid cells. A small proportion of these segregates nuclei, and give rise to viable descendants. Here we studied this process in five tumour cell lines. After mitotic failure, tumour cells enter the endocycle and form mono-nucleated or multi-nucleated giant cells (MOGC and MNGC). MNGC arise from arrested anaphases, MOGC, from arrested metaphases. In both cases the individual genomes establish a radial pattern by links to a single microtubule organizing centre. Segregation of genomes is also ordered. MNGC present features of mitosis being resumed from late anaphase. In MOGC the sub-nuclei retain arrangement of stacked metaphase plates and are separated by folds of the nuclear envelope. Mitosis then resumes in sub-nuclei directly from metaphase. The data presented indicate that endopolyploid tumour cells preserve the integrity of individual genomes and can potentially re-initiate mitosis from the point at which it was interrupted