Cancer is one of the major health problems and the second cause of death worldwide behind heart disease. The traditional soy diet containing isoflavones, consumed by the Asian population in China and ...Japan has been identified as a protective factor from hormone-related cancers. Over the years the research focus has shifted from emphasizing the preventive effect of isoflavones from cancer initiation and promotion to their efficacy against established tumors along with chemo- and radiopotentiating effects. Studies performed in mouse models and results of clinical trials emphasize that genistein or a mixture of isoflavones, containing in traditional soy diet, could be utilized to both potentiate the response of cancer cells to radiotherapy and reduce radiation-induced toxicity in normal tissues. Currently ongoing clinical research explores a potential of another significant isoflavone, idronoxil, also known as phenoxodiol, as radiation enhancing agent. In the light of the recent clinical findings, this article reviews the accumulated evidence which support the clinically desirable interactions of soy isoflavones with radiation therapy resulting in improved tumor treatment. This review discusses important aspects of the development of isoflavones as anticancer agents, and mechanisms potentially relevant to their activity in combination with radiation therapy of cancer. It gives a critical overview of studies characterizing isoflavone targets such as topoisomerases, ENOX2/PMET, tyrosine kinases and ER receptor signaling, and cellular effects on the cell cycle, DNA damage, cell death, and immune responses.
DNA repair is an essential cellular process required to maintain genomic stability. Every cell is subjected to thousands of DNA lesions daily under normal physiological conditions. Ionizing radiation ...(IR) is a major DNA damaging agent that can be produced by both natural and man-made sources. A common source of radiation exposure is through its use in medical diagnostics or treatments such as for cancer radiotherapy where relatively high doses are received by patients. To understand the detailed DNA repair gene transcription response to high dose IR, gene expression exon array studies have been performed and the response to radiation in two divergent cell types, lymphoblastoid cell lines and primary fibroblasts, has been examined. These exon arrays detect expression levels across the entire gene, and have the advantage of high sensitivity and the ability to identify alternative transcripts. We found a selection of DNA repair genes, including some not previously reported, that are modulated in response to radiation. Detailed dose and time course kinetics of DNA repair transcription was conducted and results have been validated utilizing PCR methods. Alternative transcription products in response to IR were identified in several DNA repair genes including RRM2B and XPC where alternative initiation sites were found. These investigations have advanced the knowledge about the transcriptional response of DNA repair.
The importance of nontargeted (systemic) effects of ionizing radiation is attracting increasing attention. Exploiting synchrotron radiation generated by the Imaging and Medical Beamline at the ...Australian Synchrotron, we studied radiation-induced nontargeted effects in C57BL/6 mice. Mice were locally irradiated with a synchrotron X-ray broad beam and a multiplanar microbeam radiotherapy beam. To assess the influence of the beam configurations and variations in peak dose and irradiated area in the response of normal tissues outside the irradiated field at 1 and 4 days after irradiation, we monitored oxidatively induced clustered DNA lesions (OCDL), DNA double-strand breaks (DSB), apoptosis, and the local and systemic immune responses. All radiation settings induced pronounced persistent systemic effects in mice, which resulted from even short exposures of a small irradiated area. OCDLs were elevated in a wide variety of unirradiated normal tissues. In out-of-field duodenum, there was a trend for elevated apoptotic cell death under most irradiation conditions; however, DSBs were elevated only after exposure to lower doses. These genotoxic events were accompanied by changes in plasma concentrations of macrophage-derived cytokine, eotaxin, IL10, TIMP1, VEGF, TGFβ1, and TGFβ2, along with changes in tissues in frequencies of macrophages, neutrophils, and T lymphocytes. Overall, our findings have implications for the planning of therapeutic and diagnostic radiation treatments to reduce the risk of radiation-related adverse systemic effects.
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To determine whether radiation therapy (RT) could mobilize viable tumor cells into the circulation of non-small cell lung cancer (NSCLC) patients.
We enumerated circulating tumor cells (CTCs) by ...fluorescence microscopy of blood samples immunostained with conventional CTC markers. We measured their DNA damage levels using γ-H2AX, a biomarker for radiation-induced DNA double-strand breaks, either by fluorescence-activated cell sorting or by immunofluorescence microscopy.
Twenty-seven RT-treated NSCLC patients had blood samples analyzed by 1 or more methods. We identified increased CTC numbers after commencement of RT in 7 of 9 patients treated with palliative RT, and in 4 of 8 patients treated with curative-intent RT. Circulating tumor cells were also identified, singly and in clumps in large numbers, during RT by cytopathologic examination (in all 5 cases studied). Elevated γ-H2AX signal in post-RT blood samples signified the presence of CTCs derived from irradiated tumors. Blood taken after the commencement of RT contained tumor cells that proliferated extensively in vitro (in all 6 cases studied). Circulating tumor cells formed γ-H2AX foci in response to ex vivo irradiation, providing further evidence of their viability.
Our findings provide a rationale for the development of strategies to reduce the concentration of viable CTCs by modulating RT fractionation or by coadministering systemic therapies.
Synchrotron radiation, especially microbeam radiotherapy (MRT), has a great potential to improve cancer radiotherapy, but non-targeted effects of synchrotron radiation have not yet been sufficiently ...explored. We have previously demonstrated that scattered synchrotron radiation induces measurable
γ
-H2AX foci, a biomarker of DNA double-strand breaks, at biologically relevant distances from the irradiated field that could contribute to the apparent accumulation of bystander DNA damage detected in cells and tissues outside of the irradiated area. Here, we quantified an impact of scattered radiation to DNA damage response in “naïve” cells sharing the medium with the cells that were exposed to synchrotron radiation. To understand the effect of genetic alterations in naïve cells, we utilised p53-null and p53-wild-type human colon cancer cells HCT116. The cells were grown in two-well chamber slides, with only one of nine zones (of equal area) of one well irradiated with broad beam or MRT.
γ
-H2AX foci per cell values induced by scattered radiation in selected zones of the unirradiated well were compared to the commensurate values from selected zones in the irradiated well, with matching distances from the irradiated zone. Scattered radiation highly impacted the DNA damage response in both wells and a pronounced distance-independent bystander DNA damage was generated by broad-beam irradiations, while MRT-generated bystander response was negligible. For p53-null cells, a trend for a reduced response to scattered irradiation was observed, but not to bystander signalling. These results will be taken into account for the assessment of genotoxic effects in surrounding non-targeted tissues in preclinical experiments designed to optimise conditions for clinical MRT and for cancer treatment in patients.
Follistatin is a potent regulator of the inflammatory response and binds to and inhibits activin A action. Activin A is a member of the TGFβ protein superfamily which has regulatory roles in the ...inflammatory response and in the fibrotic process. Fibrosis can occur following cell injury and cell death induced by agents such as ionizing radiation (IR). IR is used to treat cancer and marked fibrotic response is a normal tissue (non-tumour) consequence in a fraction of patients under the current dose regimes. The discovery and development of a therapeutic to abate fibrosis in these radiosensitive patients would be a major advance for cancer radiotherapy. Likewise, prediction of which patients are susceptible to fibrosis would enable individualization of treatment and provide an opportunity for pre-emptive fibrosis control and better tumour treatment outcomes. The levels of activin A and follistatin were measured in fibroblasts derived from patients who developed severe radiation-induced fibrosis following radiotherapy and compared to fibroblasts from patients who did not. Both follistatin and activin A gene expression levels were increased following IR and the follistatin gene expression level was lower in the fibroblasts from fibrosis patients compared to controls at both basal levels and after IR. The major follistatin transcript variants were found to have a similar response to IR and both were reduced in fibrosis patients. Levels of follistatin and activin A secreted in the fibroblast culture medium also increased in response to IR and the relative follistatin protein levels were significantly lower in the samples derived from fibrosis patients. The decrease in the follistatin levels can lead to an increased bioactivity of activin A and hence may provide a useful measurement to identify patients at risk of a severe fibrotic response to IR. Additionally, follistatin, by its ability to neutralise the actions of activin A may be of value as an anti-fibrotic for radiation induced fibrosis.
Formation of γ-H2AX in response to DNA double stranded breaks (DSBs) provides the basis for a sensitive assay of DNA damage in human biopsies. The review focuses on the application of γ-H2AX-based ...methods to translational studies to monitor the clinical response to DNA targeted therapies such as some forms of chemotherapy, external beam radiotherapy, radionuclide therapy or combinations thereof. The escalating attention on radiation biodosimetry has also highlighted the potential of the assay including renewed efforts to assess the radiosensitivity of prospective radiotherapy patients. Finally the γ-H2AX response has been suggested as a basis for an in vivo imaging modality.
A covalent adduct of DFOB and DOTA separated by a l -lysine residue (DFOB- l -Lys- N 6 -DOTA) exhibited remarkable regioselective metal binding, with { 1 H}- 13 C NMR spectral shifts supporting Zr( ...iv ) coordinating to the DFOB unit, and Lu( iii ) coordinating to the DOTA unit. This first-in-class, dual-chelator theranostic design could enable the use of imaging-therapy radiometal pairs of different elements, such as 89 Zr for positron emission tomography (PET) imaging and 177 Lu for low-energy β − -particle radiation therapy. DFOB- l -Lys- N 6 -DOTA was elaborated with an amine-terminated polyethylene glycol extender unit (PEG4) to give DFOB- N 2 -(PEG4)- l -Lys- N 6 -DOTA (compound D2) to enable installation of a phenyl-isothiocyanate group (Ph-NCS) for subsequent monoclonal antibody (mAb) conjugation (mAb = HuJ591). D2-mAb was radiolabeled with 89 Zr or 177 Lu to produce 89 ZrZr-D2-mAb or 177 LuLu-D2-mAb, respectively, and in vivo PET/CT imaging and in vivo / ex vivo biodistribution properties measured with the matched controls 89 ZrZr-DFOB-mAb or 177 LuLu-DOTA-mAb in a murine LNCaP prostate tumour xenograft model. The 89 Zr-immuno-PET imaging function of 89 ZrZr-D2-mAb and 89 ZrZr-DFOB-mAb showed no significant difference in tumour accumulation at 48 or 120 h post injection. 89 ZrZr-D2-mAb and 177 LuLu-D2-mAb showed similar ex vivo biodistribution properties at 120 h post-injection. Tumour uptake of 177 LuLu-D2-mAb shown by SPECT/CT imaging at 48 h and 120 h post-injection supported the therapeutic function of D2, which was corroborated by similar therapeutic efficacy between 177 LuLu-D2-mAb and 177 LuLu-DOTA-mAb, both showing a sustained reduction in tumour volume (>80% over 65 d) compared to vehicle. The work identifies D2 as a trifunctional chelator that could expand capabilities in mixed-element radiometal theranostics to improve dosimetry and the clinical outcomes of molecularly targeted radiation.
Highlights • Non-targeted effects in response to radiation are well established in cell culture models and are now beginning to be understood in vivo. • The mechanism for non-targeted effects have ...been shown to involve direct cell to cell communication, secreted factors and immune responses. • Oxidative DNA damage has been shown to be a common endpoint for both irradiated tissue and inflammatory responses such as that induced by tumours. • Cytokines and reactive species are key molecules involved in these non-targeted effects.
A new spontaneous mouse mutant was characterized by closed eyelids at weaning and without apparent eyes (provisional gene name, eyeless; provisional gene symbol, eyl). The mutation follows a ...recessive pattern of inheritance and was mapped to the region of chromosome 19 containing Pitx3. Genetic complementation tests using Pitx3 ak/⁺ mice confirmed eyl as a new allele of Pitx3 (Pitx3 eyl ). Sequencing of the Pitx3 gene in eyl mutants identified an inserted G after cDNA position 416 (416insG; exon 4). The shifted open reading frame is predicted to result in a hybrid protein still containing the Pitx3 homeobox, but followed by 121 new amino acids. The novel Pitx3 eyl/eyl mutants expressed ophthalmological and brain defects similar to Pitx3 ak/ak mice: microphthalmia or anophthalmia and loss of dopamine neurons of the substantia nigra. In addition, we observed in the homozygous eyeless mutants increased extramedullary hematopoiesis in the spleen, frequently liver steatosis, and reduced body weight. There were also several behavioral changes in the homozygous mutants, including reduced forelimb grip strength and increased nociception. In addition to these alterations in both sexes, we observed in female Pitx3 eyl/eyl mice increased anxiety-related behavior, reduced locomotor activity, reduced object exploration, and increased social contacts; however, we observed decreased anxiety-related behavior and increased arousal in males. Most of these defects identified in the new Pitx3 mutation are observed in Parkinson patients, making the Pitx3 eyl mutant a valuable new model. It is the first mouse mutant carrying a point mutation within the coding region of Pitx3.
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