• From meiosis to mitosis: the sperm centrosome defines the kinetics of spindle assembly after fertilization.

      Cavazza, Tommaso; Peset, Martin; Vernos, I; Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Doctor Aiguader, 88, 08003 Barcelona (2016-05-13)
      Bipolar spindle assembly in the vertebrate oocyte relies on a self-organization chromosome-dependent pathway. Upon fertilization the male gamete provides a centrosome and the first and subsequent embryonic divisions occur in the presence of duplicated centrosomes that act as dominant microtubule organizing centres (MTOCs).The transition from meiosis to embryonic mitosis involves a necessary adaptation to integrate the dominant chromosome-dependent pathway with the centrosomes to form the bipolar spindle.Here we took advantage of the Xenopus laevis egg extract system to mimic in vitro the assembly of the first embryonic spindle and investigate the respective contribution of the centrosome and the chromosome-dependent pathway to the kinetics of the spindle bipolarization. We found that centrosomes control the transition from the meiotic to the mitotic spindle assembly mechanism. By defining the kinetics of spindle bipolarization, the centrosomes ensure their own positioning to each spindle pole and thereby their essential correct inheritance to the two first daughter cells of the embryo for the development of a healthy organism.
    • Frozen surface replicas of the underside and surface of cultured-cells.

      Britch, M; Allen, Terence D; Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester (1979)
    • A FTIR microspectroscopic study of the uptake and metabolism of isotopically labelled fatty acids by metastatic prostate cancer.

      Gazi, Ehsan; Harvey, Tim J; Brown, Michael D; Lockyer, Nicholas P; Gardner, Peter; Clarke, Noel W; Genito Urinary Cancer research Group, School of Cancer and Imaging Sciences, Paterson Institute for Cancer Research, University of Manchester, Wilmslow Road, Manchester M20 4BX, UK (2009)
    • FTIR-based spectroscopic analysis in the identification of clinically aggressive prostate cancer.

      Baker, Matthew J; Gazi, Ehsan; Brown, Michael D; Shanks, Jonathan H; Gardner, Peter; Clarke, Noel W; Manchester Interdisciplinary Biocentre, Centre for Instrumentation and Analytical Science, School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M1 7DN, UK. M.J.Baker@manchester.ac.uk (2008-12-02)
      Fourier transform infrared (FTIR) spectroscopy is a vibrational spectroscopic technique that uses infrared radiation to vibrate molecular bonds within the sample that absorbs it. As different samples contain different molecular bonds or different configurations of molecular bonds, FTIR allows us to obtain chemical information on molecules within the sample. Fourier transform infrared microspectroscopy in conjunction with a principal component-discriminant function analysis (PC-DFA) algorithm was applied to the grading of prostate cancer (CaP) tissue specimens. The PC-DFA algorithm is used alongside the established diagnostic measures of Gleason grading and the tumour/node/metastasis system. Principal component-discriminant function analysis improved the sensitivity and specificity of a three-band Gleason score criterion diagnosis previously reported by attaining an overall sensitivity of 92.3% and specificity of 99.4%. For the first time, we present the use of a two-band criterion showing an association of FTIR-based spectral characteristics with clinically aggressive behaviour in CaP manifest as local and/or distal spread. This paper shows the potential for the use of spectroscopic analysis for the evaluation of the biopotential of CaP in an accurate and reproducible manner.
    • Fulvestrant, an estrogen receptor downregulator, reduces cell turnover index more effectively than tamoxifen.

      Bundred, Nigel J; Anderson, Elizabeth; Nicholson, Robert I; Dowsett, Mitch; Dixon, J Michael; Robertson, John F R; Department of Surgery, South Manchester University Hospital Education and Research Centre, UK. bundredn@man.ac.uk (2002)
      BACKGROUND: This study was performed to determine whether drug action on breast tumours could also be analysed using a cell turnover index (CTI), a composite measurement of both proliferation and apoptosis. MATERIALS AND METHODS: Data were obtained from a randomized, placebo-controlled trial comparing three single doses (50, 125 and 250 mg) of intramuscular fulvestrant (Faslodex, previously known as ICI 182,780) with oral tamoxifen 20 mg/day for 14-21 days in women with early, operable, ER-positive breast cancer. CTI was calculated as the ratio of the proliferation index to the apoptotic index. RESULTS: Fulvestrant 250 mg significantly reduced CTI compared with both placebo (p = 0.0003) and tamoxifen (p = 0.026). The effect on CTI with tamoxifen was not significantly different from that with placebo. CONCLUSION: This study suggests that CTI may be a useful indicator of drug action on breast tumour growth. A significant reduction in growth was found with fulvestrant 250 mg compared with tamoxifen.
    • Functional comparison of annexin V analogues labeled indirectly and directly with iodine-124.

      Dekker, Bronwen A; Keen, Heather G; Shaw, David M; Disley, Lynn; Hastings, David L; Hadfield, John A; Reader, Andrew J; Allan, Donald; Julyan, Peter J; Watson, Alastair; et al. (2005-05)
      We are interested in imaging cell death in vivo using annexin V radiolabeled with (124)I. In this study, [(124)I]4IB-annexin V and [(124)I]4IB-ovalbumin were made using [(124)I]N-hydroxysuccinimidyl-4-iodobenzoate prepared by iododestannylation of N-hydroxysuccinimidyl-4-(tributylstannyl)benzoate. [(124)I]4IB-annexin V binds to phosphatidylserine-coated microtiter plates and apoptotic Jurkat cells and accumulates in hepatic apoptotic lesions in mice treated with anti-Fas antibody, while [(124)I]4IB-ovalbumin does not. In comparison with (124)I-annexin V, [(124)I]4IB-annexin V has a higher rate of binding to phosphatidylserine in vitro, a higher kidney and urine uptake, a lower thyroid and stomach content uptake, greater plasma stability and a lower rate of plasma clearance. Binding of radioactivity to apoptotic cells relative to normal cells in vitro and in vivo appears to be lower for [(124)I]4IB-annexin V than for (124)I-annexin V.
    • Functional expression of secreted proteins from a bicistronic retroviral cassette based on foot-and-mouth disease virus 2A can be position dependent.

      Rothwell, Dominic G; Crossley, Rachel; Bridgeman, John S; Sheard, Victoria; Zhang, Y; Sharp, T; Hawkins, Robert E; Gilham, David E; McKay, Tristan R; Cancer Research UK Department of Medical Oncology, School of Cancer and Imaging Sciences, University of Manchester, Manchester Academic Health Science Centre, Christie NHS Trust, Manchester M20 4BX, United Kingdom. drothwell@picr.man.ac.uk (2010-11)
      The expression of two or more genes from a single viral vector has been widely used to label or select for cells containing the transgenic element. Identification of the foot-and-mouth disease virus (FMDV) 2A cleavage peptide as a polycistronic linker capable of producing equivalent levels of transgene expression has greatly improved this approach in the field of gene therapy. However, as a consequence of 2A posttranslational cleavage the upstream protein is left with a residual 19 amino acids from the 2A sequence on its carboxy terminus, and the downstream protein is left with an additional 2 to 5 amino acids on its amino terminus. Here we have assessed the functional consequences of the FMDV 2A cleavage motif on two secreted proteins (interleukin [IL]-2 and transforming growth factor [TGF]-β) when expressed from a retroviral bicistronic vector. Whereas IL-2 expression and function were found to be unaffected by the 2A motif in either orientation, functional expression of secreted TGF-β was significantly abrogated when the transgene was expressed upstream of the 2A sequence. We believe this is a consequence of aberrant cleavage and intracellular trafficking of the TGF-β polyprotein. These results highlight that to achieve functional expression of secreted proteins consideration must be taken of the transgenic protein's posttranslational modification and trafficking when using 2A-based bicistronic cassettes.
    • Functional heterogeneity among cytotoxic clones derived from natural killer cells.

      Christmas, Stephen E; Moore, Michael; Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester, UK. (1987)
      Clones were obtained from highly purified populations of human peripheral blood natural killer (NK) cells propagated in the presence of interleukin-2 and phytohaemagglutinin. Almost all clones were cytotoxic against standard NK targets and many were also able to kill the B lymphoblastoid cell line BSM. This latter property was not necessarily a result of the incorporation of this cell line into the feeder mixture used to derive the clones. In most cloning experiments there was a high degree of concordance between the killing of the NK targets K562 and Molt 4 by panels of clones. In some cases this extended to the killing of BSM targets but in other instances there was no relationship or even an inverse correlation between killing of BSM and other targets. In a single cloning experiment there was no relationship between killing of BSM and Raji targets. In some cases a panel of clones could be divided into two or more distinct groups based on their differential activity towards BSM and K562. Such differences were not solely due to inter-donor variation. These findings were extended by cold target inhibition experiments in which at least three types of clone were identified. In one group of clones, which was nonreactive towards BSM, cold BSM significantly enhanced the killing of K562 in a dose-dependent fashion. These experiments provide evidence for a limited degree of functional heterogeneity among clones derived from human peripheral blood NK cells.
    • Functional proteomic identification of DNA replication proteins by induced proteolysis in vivo.

      Kanemaki, Masato; Sanchez-Diaz, Alberto; Gambus, Agnieszka; Labib, Karim; Cancer Research UK, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Wilmslow Road, Manchester, M20 4BX, UK. (2003-06-12)
      Evolutionarily diverse eukaryotic cells share many conserved proteins of unknown function. Some are essential for cell viability, emphasising their importance for fundamental processes of cell biology but complicating their analysis. We have developed an approach to the large-scale characterization of such proteins, based on conditional and rapid degradation of the target protein in vivo, so that the immediate consequences of bulk protein depletion can be examined. Budding yeast strains have been constructed in which essential proteins of unknown function have been fused to a 'heat-inducible-degron' cassette that targets the protein for proteolysis at 37 degrees C (ref. 4). By screening the collection for defects in cell-cycle progression, here we identify three DNA replication factors that interact with each other and that have uncharacterized homologues in human cells. We have used the degron strains to show that these proteins are required for the establishment and normal progression of DNA replication forks. The degron collection could also be used to identify other, essential, proteins with roles in many other processes of eukaryotic cell biology.
    • Further characterization of monoclonal antibody indicates specificity for (6-4)-dipyrimidine photoproducts.

      Strickland, P T; Nikaido, O; Matsunaga, T; Boyle, John M; Johns Hopkins School of Hygiene and Public Health, Baltimore, MD 21205. (1992-05)
      Monoclonal antibody aUVssDNA-1 is produced by hybridoma cell line 25JF.C3B6 originally selected from cell fusions using spleen cells from mice immunized with UV-irradiated polydeoxynucleotides (Strickland and Boyle, Photochem. Photobiol. 34, 595-601, 1981). Original and subsequent studies of the binding characteristics of aUVssDNA-1 indicated that it was specific for cyclobuta-dithymidine photoproducts. Those investigations examined action spectrum, short-wavelength photo-reversal, nucleotide sequence effects, and photoreactivation using E. coli photolyase and incandescent light. However, the more recent studies reported here examined acetophenone-UV-B photosensitization, UV-B photoisomerization, and photoreactivation using cloned E. coli photolyase and filtered incandescent light. The results indicate that aUVssDNA-1 recognizes photoproducts with characteristics of (6-4)-dipyrimidines. Thus, previous studies in which relatively rapid repair of cyclobuta-dithymidine photoproducts was inferred using this antibody, require re-interpretation in light of these new findings.
    • Further observations on the late labelling associated with stimulus-responsive cells in skin.

      Potten, Christopher S; Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester (1973-11)
    • Further studies on the differences in cytotoxicity of human peripheral blood monocytes and bronchoalveolar macrophages for cultured human lung cells

      Swinburne, S; Moore, Michael; Cole, Peter; Host Defence Unit, Department of Medicine, Cardiothoracic Institute, Brompton Hospital, London, England (1985)
    • Fusion of metabolic function and morphology: sequential [18F]fluorodeoxyglucose positron-emission tomography/computed tomography studies yield new insights into the natural history of bone metastases in breast cancer.

      Du, Yong; Cullum, Ian; Illidge, Timothy M; Ell, Peter J; Institute of Nuclear Medicine, 5th Floor, University College Hospital, London, United Kingdom. yong.du@uclh.nhs.uk (2007-08-10)
      PURPOSE: By monitoring bone metastases with sequential [(18)F]fluorodeoxyglucose positron-emission tomography/computed tomography ([(18)F]FDG-PET/CT) imaging, this study investigates the clinical relevance of [(18)F]FDG uptake features of bone metastases with various radiographic appearances. PATIENTS AND METHODS: Bone metastases were found in 67 of 408 consecutive patients with known/suspected recurrent breast cancer on [(18)F]FDG-PET/CT, characterized by CT morphology changes and/or bony [(18)F]FDG uptake. Twenty-five of the patients had sequential [(18)F]FDG-PET/CT examinations (86 studies) over an average follow-up period of 23 months. The temporal changes in [(18)F]FDG uptake and corresponding CT morphology features of 146 bone lesions identified in these 25 patients were followed up and correlated with therapeutic outcome retrospectively. RESULTS: The 146 lesions were classified as osteolytic (77), osteoblastic (41), mixed-pattern (11), or no change/negative (17) on CT. The majority of the osteolytic (72; 93.5%) and mixed-pattern lesions (nine; 81.8%), but fewer of the osteoblastic lesions (25; 61%), showed increased [(18)F]FDG uptake. After treatment, 58 osteolytic lesions (80.5%) became [(18)F]FDG negative and osteoblastic on CT and only 14 relatively large lesions (19.5%) remained [(18)F]FDG avid. Of the 25 [(18)F]FDG-avid osteoblastic lesions, 13 (52%) became [(18)F]FDG negative, but 12 (48%) remained [(18)F]FDG avid and increased in size on CT. Five of the mixed-pattern lesions remained [(18)F]FDG avid after treatment. All 17 CT-negative lesions became [(18)F]FDG negative; however, nine of them became osteoblastic. None of the initially [(18)F]FDG-negative lesions showed [(18)F]FDG avidity during follow-up. CONCLUSION: [(18)F]FDG uptake reflects the immediate tumor activity of bone metastases, whereas the radiographic morphology changes vary greatly with time among patients.
    • Future perspectives in melanoma research. Meeting report from the "Melanoma research: a bridge from Naples to the World. Napoli, December 5th-6th 2011".

      Ascierto, P; Grimaldi, A; Curti, B; Faries, M; Ferrone, S; Flaherty, K; Fox, B; Gajewski, T; Gershenwald, J; Gogas, H; et al. (2012)
      After more than 30 years, landmark progress has been made in the treatment of cancer, and melanoma in particular, with the success of new molecules such as ipilimumab, vemurafenib and active specific immunization.After the first congress in December 2010, the second edition of "Melanoma Research: a bridge from Naples to the World" meeting, organized by Paolo A. Ascierto (INT, Naples, Italy), Francesco M. Marincola (NIH, Bethesda, USA), and Nicola Mozzillo (INT, Naples, Italy) took place in Naples, on 5-6 December 2011. We have identified four new topics of discussion: Innovative Approaches in Prevention, Diagnosis and Surgical Treatment, New Pathways and Targets in Melanoma: An Update about Immunotherapy, and Combination Strategies. This international congress gathered more than 30 international faculty members and was focused on recent advances in melanoma molecular biology, immunology and therapy, and created an interactive atmosphere which stimulated discussion of new approaches and strategies in the field of melanoma.
    • Future perspectives in melanoma research: meeting report from the 'Melanoma Bridge', Napoli, December 5th-8th 2013.

      Ascierto, P; Grimaldi, A; Anderson, A; Bifulco, C; Cochran, A; Garbe, C; Eggermont, A; Faries, M; Ferrone, S; Gershenwald, J; et al. (2014-10-28)
      The fourth ¿Melanoma Bridge Meeting¿ took place in Naples, December 5 to 8th, 2013. The four topics discussed at this meeting were: Diagnosis and New Procedures, Molecular Advances and Combination Therapies, News in Immunotherapy, and Tumor Microenvironment and Biomarkers.Until recently systemic therapy for metastatic melanoma patients was ineffective, but recent research in tumor biology and immunology has led to the development of new targeted and immunotherapeutic agents that prolong progression-free survival (PFS) and overall survival (OS). New therapies, such as mitogen-activated protein kinase (MAPK) pathway inhibitors, like BRAF and MEK inhibitors, as well as other signaling pathways inhibitors, are being tested in metastatic melanoma either as monotherapy or in combination, and have yielded promising results.Improved survival rates have also been observed with immune therapy for patients with metastatic melanoma. Immune-modulating antibodies came to the forefront with anti-CTLA-4, programmed cell death-1 (PD-1) and PD-1 ligand 1 (PD-L1) pathway blocking antibodies that result in durable responses in a subset of melanoma patients. Agents targeting other immune inhibitory (e.g., Tim-3) or immune stimulating (e.g., CD137) receptors and other approaches such as adoptive cell transfer demonstrate clinical benefit in melanoma as well.This meeting¿s specific focus was on advances in targeted therapy and immunotherapy. Both combination targeted therapy approaches and different immunotherapies were discussed. Similarly to the previous meetings, the importance of biomarkers for clinical application as markers for diagnosis, prognosis and prediction of treatment response was an integral part of the meeting. Significant consideration was given to issues surrounding the development of novel therapeutic targets as further study of patterns of resistance to both immunologic and targeted drugs are paramount to future drug development to guide existing and future therapies. The overall emphasis on biomarkers supports novel concepts toward integrating biomarkers into contemporary clinical management of patients with melanoma across the entire spectrum of disease stage. Translation of the knowledge gained from the biology of tumor microenvironment across different tumors represents a bridge to impact on prognosis and response to therapy in melanoma.
    • G protein-coupled receptors at the crossroad between physiologic and pathologic angiogenesis: old paradigms and emerging concepts.

      De Francesco, Ernestina M; Sotgia, Federica; Clarke, Robert B; Lisanti, Michael P; Maggiolini, M; Department of Pharmacy, Health and Nutrition Sciences, University of Calabria via Savinio, 87036 Rende, Italy. (2017-12-14)
      G protein-coupled receptors (GPCRs) have been implicated in transmitting signals across the extra- and intra-cellular compartments, thus allowing environmental stimuli to elicit critical biological responses. As GPCRs can be activated by an extensive range of factors including hormones, neurotransmitters, phospholipids and other stimuli, their involvement in a plethora of physiological functions is not surprising. Aberrant GPCR signaling has been regarded as a major contributor to diverse pathologic conditions, such as inflammatory, cardiovascular and neoplastic diseases. In this regard, solid tumors have been demonstrated to activate an angiogenic program that relies on GPCR action to support cancer growth and metastatic dissemination. Therefore, the manipulation of aberrant GPCR signaling could represent a promising target in anticancer therapy. Here, we highlight the GPCR-mediated angiogenic function focusing on the molecular mechanisms and transduction effectors driving the patho-physiological vasculogenesis. Specifically, we describe evidence for the role of heptahelic receptors and associated G proteins in promoting angiogenic responses in pathologic conditions, especially tumor angiogenesis and progression. Likewise, we discuss opportunities to manipulate aberrant GPCR-mediated angiogenic signaling for therapeutic benefit using innovative GPCR-targeted and patient-tailored pharmacological strategies.
    • G1 control gene status is frequently altered in resectable non-small cell lung cancer.

      Betticher, Daniel C; White, Gavin R M; Vonlanthen, S; Liu, X; Kappeler, A; Altermatt, H J; Thatcher, Nick; Heighway, Jim; Institute of Medical Oncology, Inselspital, University of Bern, Switzerland. (1997-10-21)
      Progression through the mammalian cell cycle is controlled by a series of cyclins, cyclin-dependent kinases (cdks) and cdk inhibitors. Cyclin D1, cdk4 and the tumour suppressors p16 and retinoblastoma protein (pRb) are thought to comprise a linked system governing cell passage through the G1 phase of the cell cycle. Extending an earlier study on cyclin D1 expression, a series of resectable non-small cell lung carcinomas (NSCLCs) was examined for defects in other elements of this control system. Forty-six of fifty-one NSCLC specimens exhibited at least one alteration of these cell-cycle regulators. Immunohistochemical analysis revealed that 33% and 47% of the tumours failed to express pRb and p16, respectively. Failure to detect pRb did not correlate with loss of heterozygosity at the RB1 locus. Eleven of 12 tumours showing positive (normal) pRb staining over-expressed nuclear localised cyclin D1, including 8 with amplification of the cyclin D1 gene (CCNDI). However, in a number of lesions (n = 5) where cyclin D1 was over-expressed but localised to the cytoplasm, pRb expression was undetectable. Sequencing of exons 1 and 2 of the p16 gene (CDKN2) revealed 3/51 tumours with somatic mutations (in addition to 1 case with a germ-line alteration). All of these lesions were positive for p16 protein. No clear homozygous deletions of CDKN2 were observed by multiplex PCR. As assessed by immunostaining using a p16 monoclonal antibody, there was an inverse correlation of pRb and p16 down-regulation. Whilst patients with tumours over-expressing cyclin D1 had a significantly lower incidence of local relapse, the group whose tumours failed to express pRb had a significantly greater risk of local relapse and tended to have shortened event-free survival. Our data show that alteration of at least one cell cycle-regulator gene occurs in the majority of resectable NSCLCs.
    • G2 chromosomal radiosensitivity in fibroblasts of ataxia-telangiectasia heterozygotes and a Li-Fraumeni syndrome patient with radioresistant cells.

      Mitchell, Erika L D; Scott, David; CRC Department of Cancer Genetics, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Withington, Manchester, UK. (1997-10)
      PURPOSE: To investigate whether the good discrimination we previously observed between ataxia-telangiectasia (A-T) heterozygotes and normal donors for induction of chromosome aberrations by X-rays in G2 lymphocytes is also seen in G2 fibroblasts. Also to investigate the G2 radiosensitivity of a patient with the cancer-prone Li-Fraumeni syndrome (LFS) whose fibroblasts are resistant to the lethal effects of radiation. MATERIALS AND METHODS: Fibroblasts were exposed to 0.5 Gy X-rays and harvested for metaphase analysis 90 min later. RESULTS: Four A-T heterozygote cell strains were all more sensitive than seven normal controls. The LFS strain with a germline TP53 mutation was twice as sensitive as the mean control value. CONCLUSIONS: Although chromosomal, radiosensitivity is seen in A-T heterozygotes and LFS cells, the former are radiosensitive and the latter radioresistant to cell killing. Repair defects may predominate in A-T heterozygotes, inadequate genome surveillance in LFS cells.
    • Gamma irradiation of the fetus damages the developing hemopoietic microenvironment rather than the hemopoietic progenitor cells.

      Yang, F T; Lord, Brian I; Hendry, Jolyon H; CRC Department of Experimental Haematology, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester, England. (1995-03)
      Hemopoiesis is the product of two components: the hemopoietic tissue and the regulatory stromal microenvironment in which it resides. Plutonium-239, incorporated during fetal development, is known to cause deficient hemopoiesis. A predetermined equivalent gamma-ray dose has now been used in combination with cross-transplantation experiments to separate these two components and define where the damage arises. It was confirmed that 1.8 Gy gamma irradiation at midterm gestation caused a 40% reduction in the hemopoietic stem (spleen colony-forming) cell population of their offspring which persisted to at least 24 weeks of age. Spleen colony formation after sublethal doses of gamma rays reflected this reduced complement of endogenous stem cells. The regulatory hemopoietic microenvironment, measured as fibroblastoid colony-forming cells, was similarly depleted. Normal growth of the CFU-S population after transplantation into standard recipients showed that the quality of the stem cell population in the offspring of irradiated mothers was not affected. By contrast, when used as recipients of a bone marrow transplant from either normal or irradiated offspring, the offspring of irradiated mothers were unable to support normal growth: there was a twofold difference in the number of CFU-S per femur for at least 100 days after transplantation. There were 70% fewer CFU-F in the femur 1 month after bone marrow transplantation when the offspring of irradiated mothers were used as transplant recipients compared to when normal offspring were used. This not only confirmed their reduced capacity to host normal stem cells but also indicated that CFU-F in the transplant were unable to compensate for the poor microenvironment in the irradiated offspring hosts. It is concluded that irradiation at midterm gestation damages the developing regulatory microenvironment but not the hemopoietic stem cell population that it hosts.
    • Gamma-ray-induced cell killing and chromosome abnormalities in the bone marrow of p53-deficient mice.

      Wang, L; Cui, Y; Lord, Brian I; Roberts, Stephen A; Potten, Christopher S; Hendry, Jolyon H; Scott, David; Paterson Institute for Cancer Research, Christie CRC Research Centre, Manchester, United Kingdom. (1996-09)
      Resistance to the lethal effects of ionizing radiation has been demonstrated in a wide variety of cell types with defects in the p53 gene (thymocytes, splenic B and T cells, in vitro hemopoietic colony-forming cells and intestinal cells of the mouse, embryo cells of the rat, and human Burkitt's lymphoma cells). In contrast, Slichenmeyer et al. (Cancer Res. 53, 4164-4167, 1993) found no evidence of resistance in fibroblasts derived from p53 null mice. The aim of our study was to compare the radiation response of hemopoietic colony-forming cells (in vitro CFC) and of fibroblastoid colony-forming cells or units (CFU-F) within the same tissue (marrow) in p53 null mice (-/-), heterozygotes (+/-) and wild-type animals (+/+). We have also tested the hypothesis that, in proliferating cells, radiation-induced cell killing is mediated through chromosome damage by examining the relationship between these end points in hemopoietic cells of the three mouse types. Both in vitro CFC and CFU-F of -/- mice were resistant to cell killing compared with +/+ and +/- mice whose cellular sensitivities were indistinguishable. The resistance was characterized by a broader "shoulder" on the cell survival curve, i.e. a higher extrapolation number but similar D0 values using the multitarget model or a lower alpha coefficient using the linear-quadratic model. The frequency of chromosomally abnormal marrow cells after irradiation was similar for the three genotypes. However, marrow cells with aberrations carried more aberrations in -/- mice than in +/+ or +/- mice such that the total number of aberrations per 100 cells was higher in -/- mice. Since there were no differences in the yields of aberrations between genotypes in spleen lymphocytes or in CFU-F (both noncycling at the time of irradiation) and less mitotic inhibition in -/- marrow cells than in +/+ or +/- cells, the chromosomal radiosensitivity of -/- marrow hemopoietic cells might be related to reduced cell cycle delay allowing insufficient time for repair, but other explanations have been considered. We postulate that the radiation resistance of both hemopoietic CFC and CFU-F in -/- mice is a consequence of the failure of DNA/chromosome damage to trigger apoptosis or permanent cell cycle arrest to the same extent as in the +/+ or +/- mice: hence the lack of correlation between chromosome damage and cell death in the three mouse types.