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McCullum L, Shin J, Xing S, Beekman C, Schuemann J, Hong T, Duda D, Mohan R, Lin SH, Correa-Alfonso CM, Domal S, Withrow J, Bolch W, Paganetti H, Grassberger C. Predicting Severity of Radiation Induced Lymphopenia in Individual Proton Therapy Patients for Varying Dose Rate and Fractionation Using Dynamic 4-Dimensional Blood Flow Simulations. Int J Radiat Oncol Biol Phys 2023; 116:1226-1233. [PMID: 36739919 PMCID: PMC10363211 DOI: 10.1016/j.ijrobp.2023.01.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 01/11/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023]
Abstract
PURPOSE Radiation-induced lymphopenia has gained attention recently as the result of its correlation with survival in a range of indications, particularly when combining radiation therapy (RT) with immunotherapy. The purpose of this study is to use a dynamic blood circulation model combined with observed lymphocyte depletion in patients to derive the in vivo radiosensitivity of circulating lymphocytes and study the effect of RT delivery parameters. METHODS AND MATERIALS We assembled a cohort of 17 patients with hepatocellular carcinoma treated with proton RT alone in 15 fractions (fx) using conventional dose rates (beam-on time [BOT], 120 seconds) for whom weekly absolute lymphocyte counts (ALCs) during RT and follow-up were available. We used HEDOS, a time-dependent, whole-body, blood flow computational framework, in combination with explicit liver blood flow modeling, to calculate the dose volume histograms for circulating lymphocytes for changing BOTs (1 second-300 seconds) and fractionations (5 fx, 15 fx). From this, we used the linear cell survival model and an exponential model to determine patient-specific lymphocyte radiation sensitivity, α, and recovery, σ, respectively. RESULTS The in vivo-derived patient-specific α had a median of 0.65 Gy-1 (range, 0.30-1.38). Decreasing BOT to 1 second led to an increased average end-of-treatment ALC of 27.5%, increasing to 60.3% when combined with the 5-fx regimen. Decreasing to 5 fx at the conventional dose rate led to an increase of 17.0% on average. The benefit of both increasing dose rate and reducing the number of fractions was patient specificࣧpatients with highly sensitive lymphocytes benefited most from decreasing BOT, whereas patients with slow lymphocyte recovery benefited most from the shorter fractionation regimen. CONCLUSIONS We observed that increasing dose rate at the same fractionation reduced ALC depletion more significantly than reducing the number of fractions. High-dose-rates led to an increased sparing of lymphocytes when shortening the fractionation regimen, particularly for patients with radiosensitive lymphocytes at elevated risk.
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Affiliation(s)
- Lucas McCullum
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
| | - Jungwook Shin
- Radiation Epidemiology Branch, National Cancer Institute, Rockville, Maryland
| | - Stella Xing
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Chris Beekman
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jan Schuemann
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Theodore Hong
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dan Duda
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Radhe Mohan
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Steven H Lin
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Camilo M Correa-Alfonso
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida
| | - Sean Domal
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida
| | - Julia Withrow
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida
| | - Wesley Bolch
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida
| | - Harald Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Clemens Grassberger
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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2
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Polgár S, Schofield PN, Madas BG. Datasets of in vitro clonogenic assays showing low dose hyper-radiosensitivity and induced radioresistance. Sci Data 2022; 9:555. [PMID: 36075916 PMCID: PMC9458642 DOI: 10.1038/s41597-022-01653-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 08/19/2022] [Indexed: 11/19/2022] Open
Abstract
Low dose hyper-radiosensitivity and induced radioresistance are primarily observed in surviving fractions of cell populations exposed to ionizing radiation, plotted as the function of absorbed dose. Several biophysical models have been developed to quantitatively describe these phenomena. However, there is a lack of raw, openly available experimental data to support the development and validation of quantitative models. The aim of this study was to set up a database of experimental data from the public literature. Using Google Scholar search, 46 publications with 101 datasets on the dose-dependence of surviving fractions, with clear evidence of low dose hyper-radiosensitivity, were identified. Surviving fractions, their uncertainties, and the corresponding absorbed doses were digitized from graphs of the publications. The characteristics of the cell line and the irradiation were also recorded, along with the parameters of the linear-quadratic model and/or the induced repair model if they were provided. The database is available in STOREDB, and can be used for meta-analysis, for comparison with new experiments, and for development and validation of biophysical models. Measurement(s) | surviving fraction of cells | Technology Type(s) | optical microscopy | Factor Type(s) | absorbed dose | Sample Characteristic - Organism | Homo sapiens • Chinese hamster • Rattus sp. | Sample Characteristic - Environment | cell culture |
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Affiliation(s)
- Szabolcs Polgár
- Doctoral School of Physics, ELTE Eötvös Loránd University, Budapest, Hungary.,Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Paul N Schofield
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary. .,Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest, Hungary.
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Słonina D, Kabat D, Biesaga B, Janecka-Widła A, Szatkowski W. Chemopotentiating effects of low-dose fractionated radiation on cisplatin and paclitaxel in cervix cancer cell lines and normal fibroblasts from patients with cervix cancer. DNA Repair (Amst) 2021; 103:103113. [PMID: 33839463 DOI: 10.1016/j.dnarep.2021.103113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 03/24/2021] [Accepted: 03/31/2021] [Indexed: 11/27/2022]
Abstract
The aim of the present study was to compare the effects (assessed by clonogenic survival and γH2AX foci assays) of low-dose fractionated radiation LDFR (4 × 0.125 Gy, 4 × 0.25 Gy and 4 × 0.5 Gy) versus single radiation doses (0.5 Gy, 1 Gy and 2 Gy) on cisplatin and paclitaxel in HRS-negative cervix cancer cell lines SiHa and CaSki to see if the effects of LDFR can emerge in cells that not present low-dose hyper-radiosensitivity (HRS) phenomenon. Additionally, we report the effects in normal fibroblasts (HRS-negative and HRS-positive) from two patients with cervix cancer to see if the chemopotentiating effects of LDFR also apply to normal cells. LDFR (4 × 0.125 Gy, 4 × 0.25 Gy and 4 × 0.5 Gy) as well as single doses (0.5 Gy, 1 Gy and 2 Gy) enhanced cytotoxicity of cisplatin and paclitaxel in all the cell lines. Cisplatin-potentiating effects were maximum with LDFR 4 × 0.5 Gy, and were two-fold greater than those with a single dose of 2 Gy in SiHa, CaSki and HFIB2 cells. Paclitaxel-enhancing effects were also maximum with LDFR 4 × 0.5 Gy, however only in HRS-positive HFIB2 fibroblasts were significantly greater than those with a single dose of 2 Gy. The results demonstrate that LDFR may enhance the effects of cisplatin and paclitaxel in SiHa and CaSki cells, although they lack HRS phenomenon, and show that the magnitude of the potentiating effects of LDFR depends on cytostatic type and the size of low doses. In normal fibroblasts the chemopotentiating effects of LDFR seem to depend on HRS status. In conclusion, the unique enhancing effects of LDFR on cisplatin in cervical cancer cell lines, even when HRS negative, suggest that all patients with cervical cancer may benefit from the addition of LDFR to adjuvant cisplatin-based chemotherapy.
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Affiliation(s)
- Dorota Słonina
- Center for Translational Research and Molecular Biology of Cancer, Maria Sklodowska-Curie National Research Institute of Oncology Gliwice Branch, Poland.
| | - Damian Kabat
- Department of Medical Physics, Maria Sklodowska-Curie National Research Institute of Oncology Cracow Branch, Cracow, Poland
| | - Beata Biesaga
- Center for Translational Research and Molecular Biology of Cancer, Maria Sklodowska-Curie National Research Institute of Oncology Gliwice Branch, Poland; Department of Tumour Pathology, Maria Sklodowska-Curie National Research Institute of Oncology Cracow Branch, Cracow, Poland
| | - Anna Janecka-Widła
- Department of Tumour Pathology, Maria Sklodowska-Curie National Research Institute of Oncology Cracow Branch, Cracow, Poland
| | - Wiktor Szatkowski
- Department of Gynecologic Oncology, Maria Sklodowska-Curie National Research Institute of Oncology Cracow Branch, Cracow, Poland
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Mathur A, Kumar A, Babu B, Chandna S. In vitro mesenchymal-epithelial transition in NIH3T3 fibroblasts results in onset of low-dose radiation hypersensitivity coupled with attenuated connexin-43 response. Biochim Biophys Acta Gen Subj 2017; 1862:414-426. [PMID: 29154903 DOI: 10.1016/j.bbagen.2017.11.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/21/2017] [Accepted: 11/13/2017] [Indexed: 12/13/2022]
Abstract
BACKGROUND Mesenchymal-to-epithelial transition (MET) is associated with altered cell adhesion patterns. Independent studies showed that cellular adhesion regulates low-dose hyper-radiosensitivity (HRS), a phenomenon reported widely in tumour cells. Therefore, present study aimed to investigate whether MET and associated cellular adhesion alterations affect cellular radiosensitivity. METHODS We established multiple stages of MET by in vitro transformation of NIH3T3 mouse embryonic fibroblasts. Nutritional deprivation followed by repetitive treatment cycles of 3-methylcholanthrene and phorbol-12-myristate-13-acetate with frequent isolation of foci established three progressive strains (NIH3T3.1, NIH3T3x3, NIH3T3x8x3) depicting MET, and one strain (NIH3T3x12) with partial reversion. Alterations in morphology, cell adhesion properties, expression/intracellular localization of cell adhesion proteins, microRNA expression and cellular radiosensitivity were studied in these stably transformed cell strains. RESULTS All four transformants had increased proliferation rate, saturation density, bipolarity, E-cadherin expression; coupled with reduced cell size/spreading, pseudopodia/migration, and fibroblast marker protein and vimentin. The most aggressive trans-differentiated (phenotypically epithelial) cell strain, NIH3T3x8x3 acquired ~30% higher growth potential associated with more than two-fold reduction in cell size and migration. These phenotypic changes accompanied ~40% reduction in endogenous or radiation-induced connexin-43 expression/mitochondrial translocation. Incidentally, all three progressive strains displayed prominent HRS (αs/αr: 7.95-37.29) whereas parental (NIH3T3) and reverting (NIH3T3x12) strains lacked HRS and had distinct radiation-induced Cx43 translocation into mitochondria. CONCLUSION Our study shows that trans-differentiating fibroblasts progressively acquiring epithelial features during MET process, display low-dose hyper-radiosensitivity associated with altered Cx43 behaviour. GENERAL SIGNIFICANCE This study demonstrates that MET progression triggers low-dose hyper-radiosensitivity in trans-differentiating cells, which has significant therapeutic implications.
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Affiliation(s)
- Ankit Mathur
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Brig. S.K. Mazumdar Road,Timarpur, Delhi 110054, India
| | - Ashish Kumar
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Brig. S.K. Mazumdar Road,Timarpur, Delhi 110054, India
| | - Bincy Babu
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Brig. S.K. Mazumdar Road,Timarpur, Delhi 110054, India
| | - Sudhir Chandna
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Brig. S.K. Mazumdar Road,Timarpur, Delhi 110054, India.
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Słonina D, Kowalczyk A, Janecka-Widła A, Kabat D, Szatkowski W, Biesaga B. Low-Dose Hypersensitive Response for Residual pATM and γH2AX Foci in Normal Fibroblasts of Cancer Patients. Int J Radiat Oncol Biol Phys 2017; 100:756-766. [PMID: 29248168 DOI: 10.1016/j.ijrobp.2017.10.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/10/2017] [Accepted: 10/30/2017] [Indexed: 01/04/2023]
Abstract
PURPOSE To define the dose-response relationship for initial and residual pATM and γH2AX foci and temporal response of pATM foci in fibroblasts of 4 hyper-radiosensitivity (HRS)-positive cancer patients and 8 HRS-negative cancer patients and answer the question regarding the role of DNA double-strand break (DSB) recognition and repair in the mechanism of HRS. METHODS AND MATERIALS The cells were irradiated with single doses (0.1-4 Gy) of 6-MV X rays. The number of initial and residual pATM and γH2AX foci was assessed 1 hour and 24 hours after irradiation, respectively. Kinetics of DSB recognition and repair was estimated by pATM foci assay after irradiation with 0.2 and 2 Gy. RESULTS Hyper-radiosensitivity response (confirmed by the induced-repair model) was clearly evident for residual pATM and γH2AX foci in fibroblasts of HRS-positive patients but not in fibroblasts of HRS-negative patients. Significantly less DSB was recognized by pATM early (10-30 minutes) after irradiation with 0.2 Gy in HRS-positive compared with HRS-negative fibroblasts. CONCLUSIONS The present results provide evidence for the role of DSB recognition by pATM and repair in the mechanism of HRS and seem to support the idea of nucleo-shuttling of the pATM protein to be involved in HRS response.
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Affiliation(s)
- Dorota Słonina
- Department of Applied Radiobiology, Maria Sklodowska-Curie Institute - Oncology Center, Cracow Branch, Cracow, Poland.
| | - Aleksandra Kowalczyk
- Department of Applied Radiobiology, Maria Sklodowska-Curie Institute - Oncology Center, Cracow Branch, Cracow, Poland
| | - Anna Janecka-Widła
- Department of Applied Radiobiology, Maria Sklodowska-Curie Institute - Oncology Center, Cracow Branch, Cracow, Poland
| | - Damian Kabat
- Department of Medical Physics, Maria Sklodowska-Curie Institute - Oncology Center, Cracow Branch, Cracow, Poland
| | - Wiktor Szatkowski
- Department of Gynecologic Oncology, Maria Sklodowska-Curie Institute - Oncology Center, Cracow Branch, Cracow, Poland
| | - Beata Biesaga
- Department of Applied Radiobiology, Maria Sklodowska-Curie Institute - Oncology Center, Cracow Branch, Cracow, Poland
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Terashima S, Hosokawa Y, Tsuruga E, Mariya Y, Nakamura T. Impact of time interval and dose rate on cell survival following low-dose fractionated exposures. JOURNAL OF RADIATION RESEARCH 2017; 58:782-790. [PMID: 28595296 PMCID: PMC5710595 DOI: 10.1093/jrr/rrx025] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/08/2017] [Indexed: 05/23/2023]
Abstract
Enhanced cell lethality, also known as hyper-radiosensitivity, has been reported at low doses of radiation (≤0.5 Gy) in various cell lines, and is expected to be an effective cancer therapy. We conducted this study to examine the impact of time interval and dose rate of low-dose fractionated exposures with a short time interval. We evaluated the cell-survival rates of V79 and A549 cells using clonogenic assays. We performed fractionated exposures in unit doses of 0.25, 0.5, 1.0 and 2.0 Gy. We exposed the cells to 2 Gy of X-rays (i) at dose-rates of 1.0, 1.5 and 2.0 Gy/min at 1-min intervals and (ii) at a dose-rate of 2.0 Gy/min at 10-s, 1-min and 3-min intervals by fractionated exposures. Apoptosis and cell cycle analyses were also evaluated in the fractionated exposures (unit dose 0.25 Gy) and compared with single exposures by using flow cytometry. Both cell-type survival rates with fractionated exposures (unit dose 0.25 Gy) with short time intervals were markedly lower than those for single exposures delivering the same dose. When the dose rates were lower, the cytotoxic effect decreased compared with exposure to a dose-rate of 2.0 Gy/min. On the other hand, levels of apoptosis and cell cycle distribution were not significantly different between low-dose fractionated exposures and single exposures in either cell line. These results indicate that a stronger cytotoxic effect was induced with low-dose fractionated exposures with a short time interval for a given dose due to the hyper-radiosensitivity phenomenon, suggesting that dose rates are important for effective low-dose fractionated exposures.
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Affiliation(s)
- Shingo Terashima
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
| | - Yoichiro Hosokawa
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
| | - Eichi Tsuruga
- Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
| | - Yasushi Mariya
- Department of Radiology, Mutsu General Hospital, 1-2-8 Kogawa-cho, Mutsu, Aomori 035-8601, Japan
| | - Toshiya Nakamura
- Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan
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Khorramizadeh M, Saberi A, Tahmasebi-Birgani M, Shokrani P, Amouhedari A. Effect of Temporal Pattern of Radiation in Intensity Modulated Radiotherapy on Cell Cycle Progression and Apoptosis of ACHN Renal Cell Carcinoma Cell Line. Pak J Biol Sci 2016; 19:315-322. [PMID: 29023017 DOI: 10.3923/pjbs.2016.315.322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND AND OBJECTIVE The existence of a hypersensitive radiation response to doses below 1 Gy is well established for many normal and tumor cell lines. The aim of this study was to ascertain the impact of temporal pattern modeling IMRT on survival, cell cycle and apoptosis of human RCC cell line ACHN, so as to provide radiobiological basis for optimizing IMRT plans for this disease. MATERIALS AND METHODS The ACHN renal cell carcinoma cell line was used in this study. Impact of the triangle, V, small-large or large-small temporal patterns in the presence and absence of threshold dose of hyper-radiosensitivity at the beginning of patterns were studied using soft agarclonogenic assays. Cell cycle and apoptosis analysis were performed after irradiation with the temporal patterns. RESULTS For triangle and small-large dose sequences, survival fraction was significantly reduced after irradiation with or without threshold dose of hyper-radiosensitivity at the beginning of the patterns. In all of the dose patterns, cell cycle distributions and the percentage of apoptotic cells at 24 h after irradiation with or without priming dose of hyper-radiosensitivity showed no significant difference. However, apoptotic cells were increased when beams with the smallest dose applied at the beginning of dose pattern like triangle and small-large dose sequence. CONCLUSION These data show that the biologic effects of single fraction may differ in clinical settings depending on the size and sequence of the partial fractions. Doses at the beginning but not at the end of sequences may change cytotoxicity effects of radiation.
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Affiliation(s)
- Maryam Khorramizadeh
- Department of Medical Physics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Alihossein Saberi
- Department of Medical Genetics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | | | - Parvaneh Shokrani
- Department of Medical Physics and Medical Engineering, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
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Słonina D, Gasińska A, Biesaga B, Janecka A, Kabat D. An association between low-dose hyper-radiosensitivity and the early G2-phase checkpoint in normal fibroblasts of cancer patients. DNA Repair (Amst) 2015; 39:41-5. [PMID: 26725161 DOI: 10.1016/j.dnarep.2015.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 12/11/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
In our previous study, low-dose hyper-radiosensitivity (HRS) effect was demonstrated for normal fibroblasts (asynchronous and G2-phase enriched) of 4 of the 25 cancer patients investigated. For the rest of patients, HRS was not defined in either of the 2 fibroblast populations. Thus, the study indicated that G2-phase enrichment had no influence on HRS identification. The conclusion contradicts that reported for human tumor cells, and suggests different mechanism of HRS in normal human cells. In the present paper we report, for the first time, the activity of early G2-phase checkpoint after low-dose irradiation in normal fibroblasts of these 4 HRS-positive patients and 4 HRS-negative patients and answer the question regarding the role of this checkpoint in normal human cells. The response of the early G2-phase checkpoint was determined by assessment of the progression of irradiated cells into mitosis using the mitotic marker, phosphorylated histone H3. We found evident differences in the activity of the early G2-phase checkpoint between HRS-positive and HRS-negative fibroblasts. In HRS-positive fibroblasts the checkpoint was not triggered and DNA damage was not recognized after doses lower than 0.2Gy resulting in HRS response. On the contrary, in HRS-negative fibroblasts the early G2-phase checkpoint was activated regardless of the dose in the range 0.1-2Gy. In conclusion, although cell cycle phase has no effect on the presence of HRS effect in normal human fibroblasts, the data reported here indicate that HRS response in these cells is associated with the functioning of early G2-phase checkpoint in a threshold-dose dependent manner, similarly as it takes place in most of human tumor and other cells.
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Affiliation(s)
- Dorota Słonina
- Department of Applied Radiobiology, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Cracow Branch, 11 Garncarska Street, Cracow 31-115, Poland.
| | - Anna Gasińska
- Department of Applied Radiobiology, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Cracow Branch, 11 Garncarska Street, Cracow 31-115, Poland
| | - Beata Biesaga
- Department of Applied Radiobiology, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Cracow Branch, 11 Garncarska Street, Cracow 31-115, Poland
| | - Anna Janecka
- Department of Applied Radiobiology, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Cracow Branch, 11 Garncarska Street, Cracow 31-115, Poland
| | - Damian Kabat
- Department of Medical Physics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Cracow Branch, 11 Garncarska Street, Cracow 31-115, Poland
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Ghosh S, Kumar A, Chandna S. Connexin-43 downregulation in G2/M phase enriched tumour cells causes extensive low-dose hyper-radiosensitivity (HRS) associated with mitochondrial apoptotic events. Cancer Lett 2015; 363:46-59. [PMID: 25843295 DOI: 10.1016/j.canlet.2015.03.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 03/13/2015] [Accepted: 03/29/2015] [Indexed: 12/31/2022]
Abstract
Enrichment of tumour cells in G2/M phases in vitro is known to be associated with low-dose hyper-radiosensitivity (HRS). These cell cycle phases also involve reduced expression of adhesion protein connexin-43 (Cx43). Therefore, we investigated the role of Cx43 in HRS. Asynchronous or G2/M enriched tumour cells (U87, BMG-1, HeLa) and normal primary fibroblasts (HDFn) were γ-irradiated at varying doses, with an asynchronous group separately subjected to Cx43-knockdown prior to irradiation. Cx43 level, gap junctional activity, clonogenic cell survival, cell growth/viability, mitochondrial alterations and other apoptosis-regulating events were studied. G2/M enrichment reduced Cx43 level by ~50% and caused considerable HRS at doses 10 cGy-30 cGy in all tumour cell lines. Cx43-knockdown to the same level (~60%) also elicited prominent HRS response in these cells. Quite important, radiosensitivity of primary HDFn cells remained unaltered by all these treatments. In Cx43-knockdown tumour cells, low-dose irradiation caused significant growth inhibition and apoptosis involving loss of MMP, cytochrome-c release and caspase-3 activation, thereby demonstrating the important cytoprotective role of Cx43. Therefore, this study significantly shows that Cx43 downregulation (a constitutive feature of G2/M phase) selectively renders tumour cells hypersensitive to low-dose radiation, and presents connexins as potential therapeutic targets.
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Affiliation(s)
- Soma Ghosh
- Natural Radiation Response Mechanisms Group, Division of Radiation Biosciences, Institute of Nuclear Medicine & Allied Sciences, Brig. Mazumdar Road, Delhi 110054, India
| | - Ashish Kumar
- Natural Radiation Response Mechanisms Group, Division of Radiation Biosciences, Institute of Nuclear Medicine & Allied Sciences, Brig. Mazumdar Road, Delhi 110054, India
| | - Sudhir Chandna
- Natural Radiation Response Mechanisms Group, Division of Radiation Biosciences, Institute of Nuclear Medicine & Allied Sciences, Brig. Mazumdar Road, Delhi 110054, India.
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10
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Seth I, Joiner MC, Tucker JD. Cytogenetic Low-Dose Hyperradiosensitivity Is Observed in Human Peripheral Blood Lymphocytes. Int J Radiat Oncol Biol Phys 2015; 91:82-90. [DOI: 10.1016/j.ijrobp.2014.09.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 09/11/2014] [Accepted: 09/13/2014] [Indexed: 10/24/2022]
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