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High Energy Particle Radiation-associated Oncogenic Transformation in Normal Mice: Insight into the Connection between Activation of Oncotargets and Oncogene Addiction

View Article: PubMed Central - PubMed

ABSTRACT

Concerns on high-energy particle radiation-induced tumorigenic transformation of normal tissue in astronauts, and in cancer patients undergoing radiotherapy, emphasizes the significance of elucidating the mechanisms involved in radiogenic transformation processes. Mostly used genetically modified or tumor-prone models are less reliable in determining human health risk in space or protracted post-treatment normal tissue toxicity. Here, in wild type C57BL/6 mice, we related the deregulation of distinctive set of tissue-specific oncotargets in major organs upon 56Fe (600 MeV/amu; 0.5 Gy/min; 0.8 Gy) particle radiation and compared the response with low LET γ-radiation (137Cs; 0.5 Gy/min; 2 Gy). One of the novel findings is the ‘tissue-independent’ activation of TAL2 upon high-energy radiation, and thus qualifies TAL2 as a potential biomarker for particle and other qualities of radiation. Heightened expression of TAL2 gene transcript, which sustained over four weeks post-irradiation foster the concept of oncogene addiction signaling in radiogenic transformation. The positive/negative expression of other selected oncotargets that expresses tissue-dependent manner indicated their role as a secondary driving force that addresses the diversity of tissue-dependent characteristics of tumorigenesis. This study, while reporting novel findings on radiogenic transformation of normal tissue when exposed to particle radiation, it also provides a platform for further investigation into different radiation quality, LET and dose/dose rate effect in healthy organs.

No MeSH data available.


TUNEL staining analysis showing apoptotic modulations in mouse tissues exposed to HZE particle radiation.(A) Microphotograph of the TUNEL-stained TMA. A tissue microarray was constructed with the brain, liver, kidney, lugs, spleen, and gut tissues from the mock-irradiated mice or the mice exposed to HZE particle radiation. (B) Representative microphotographs of corresponding tissue TUNEL-positive controls. For induced TUNEL positivity DNA strand breaks were induced with recombinant DNAse I treatment. (C) Representative microphotographs showing comparative regions of TUNEL-positive cells in brain, liver, kidney, lugs, spleen, and gut tissues in mice exposed to mock-IR or HZE particle radiation. (D) Representative microphotographs of the corresponding TUNEL-negative tissue controls. For negative controls, TUNEL staining was performed without Tdt enzyme labeling. (E) Histograms obtained from TUNEL assay showing HZE-associated apoptotic alterations in HZE-exposed mouse tissues compared with mock-IR controls. TUNEL positivity was quantified using Aperio TMA analysis. Group-wise comparisons were performed using GraphPad Prism.
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f5: TUNEL staining analysis showing apoptotic modulations in mouse tissues exposed to HZE particle radiation.(A) Microphotograph of the TUNEL-stained TMA. A tissue microarray was constructed with the brain, liver, kidney, lugs, spleen, and gut tissues from the mock-irradiated mice or the mice exposed to HZE particle radiation. (B) Representative microphotographs of corresponding tissue TUNEL-positive controls. For induced TUNEL positivity DNA strand breaks were induced with recombinant DNAse I treatment. (C) Representative microphotographs showing comparative regions of TUNEL-positive cells in brain, liver, kidney, lugs, spleen, and gut tissues in mice exposed to mock-IR or HZE particle radiation. (D) Representative microphotographs of the corresponding TUNEL-negative tissue controls. For negative controls, TUNEL staining was performed without Tdt enzyme labeling. (E) Histograms obtained from TUNEL assay showing HZE-associated apoptotic alterations in HZE-exposed mouse tissues compared with mock-IR controls. TUNEL positivity was quantified using Aperio TMA analysis. Group-wise comparisons were performed using GraphPad Prism.

Mentions: We first investigated the levels of induced apoptosis in healthy tissues after HZE particle radiation. A customized TMA constructed with brain, liver, kidney, lung, spleen, and gut tissues from mock-irradiated and irradiated animals was assessed for cell death using TUNEL assay (Fig. 5A). Corresponding individual tissue sections treated with DNase exhibited high levels of TUNEL-positive cells, and served as internal positive controls (Fig. 5B). Overall, we observed minimal baseline cell death in untreated mock-IR controls; visually, HZE particle radiation resulted in increased cell death to a certain degree (Fig. 5C). Terminal deoxynucleotidal transferase (Tdt) enzyme controls exhibited zero TUNEL-positive cells and served as the internal negative control (Fig. 5D). Quantification of the TUNEL-positive cells in tissues from mock-irradiated animals revealed minimal (brain, liver, gut), marginal (kidney, lungs), and relatively high (spleen) baseline apoptosis (Fig. 5E). HZE particle exposure resulted in insignificant cell death changes in mouse brain, liver and gut tissues. Although this finding was not statistically significant, we observed an elevated level of apoptosis in kidney, lung, and spleen tissues after high-LET radiation (Fig. 5E).


High Energy Particle Radiation-associated Oncogenic Transformation in Normal Mice: Insight into the Connection between Activation of Oncotargets and Oncogene Addiction
TUNEL staining analysis showing apoptotic modulations in mouse tissues exposed to HZE particle radiation.(A) Microphotograph of the TUNEL-stained TMA. A tissue microarray was constructed with the brain, liver, kidney, lugs, spleen, and gut tissues from the mock-irradiated mice or the mice exposed to HZE particle radiation. (B) Representative microphotographs of corresponding tissue TUNEL-positive controls. For induced TUNEL positivity DNA strand breaks were induced with recombinant DNAse I treatment. (C) Representative microphotographs showing comparative regions of TUNEL-positive cells in brain, liver, kidney, lugs, spleen, and gut tissues in mice exposed to mock-IR or HZE particle radiation. (D) Representative microphotographs of the corresponding TUNEL-negative tissue controls. For negative controls, TUNEL staining was performed without Tdt enzyme labeling. (E) Histograms obtained from TUNEL assay showing HZE-associated apoptotic alterations in HZE-exposed mouse tissues compared with mock-IR controls. TUNEL positivity was quantified using Aperio TMA analysis. Group-wise comparisons were performed using GraphPad Prism.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120307&req=5

f5: TUNEL staining analysis showing apoptotic modulations in mouse tissues exposed to HZE particle radiation.(A) Microphotograph of the TUNEL-stained TMA. A tissue microarray was constructed with the brain, liver, kidney, lugs, spleen, and gut tissues from the mock-irradiated mice or the mice exposed to HZE particle radiation. (B) Representative microphotographs of corresponding tissue TUNEL-positive controls. For induced TUNEL positivity DNA strand breaks were induced with recombinant DNAse I treatment. (C) Representative microphotographs showing comparative regions of TUNEL-positive cells in brain, liver, kidney, lugs, spleen, and gut tissues in mice exposed to mock-IR or HZE particle radiation. (D) Representative microphotographs of the corresponding TUNEL-negative tissue controls. For negative controls, TUNEL staining was performed without Tdt enzyme labeling. (E) Histograms obtained from TUNEL assay showing HZE-associated apoptotic alterations in HZE-exposed mouse tissues compared with mock-IR controls. TUNEL positivity was quantified using Aperio TMA analysis. Group-wise comparisons were performed using GraphPad Prism.
Mentions: We first investigated the levels of induced apoptosis in healthy tissues after HZE particle radiation. A customized TMA constructed with brain, liver, kidney, lung, spleen, and gut tissues from mock-irradiated and irradiated animals was assessed for cell death using TUNEL assay (Fig. 5A). Corresponding individual tissue sections treated with DNase exhibited high levels of TUNEL-positive cells, and served as internal positive controls (Fig. 5B). Overall, we observed minimal baseline cell death in untreated mock-IR controls; visually, HZE particle radiation resulted in increased cell death to a certain degree (Fig. 5C). Terminal deoxynucleotidal transferase (Tdt) enzyme controls exhibited zero TUNEL-positive cells and served as the internal negative control (Fig. 5D). Quantification of the TUNEL-positive cells in tissues from mock-irradiated animals revealed minimal (brain, liver, gut), marginal (kidney, lungs), and relatively high (spleen) baseline apoptosis (Fig. 5E). HZE particle exposure resulted in insignificant cell death changes in mouse brain, liver and gut tissues. Although this finding was not statistically significant, we observed an elevated level of apoptosis in kidney, lung, and spleen tissues after high-LET radiation (Fig. 5E).

View Article: PubMed Central - PubMed

ABSTRACT

Concerns on high-energy particle radiation-induced tumorigenic transformation of normal tissue in astronauts, and in cancer patients undergoing radiotherapy, emphasizes the significance of elucidating the mechanisms involved in radiogenic transformation processes. Mostly used genetically modified or tumor-prone models are less reliable in determining human health risk in space or protracted post-treatment normal tissue toxicity. Here, in wild type C57BL/6 mice, we related the deregulation of distinctive set of tissue-specific oncotargets in major organs upon 56Fe (600 MeV/amu; 0.5 Gy/min; 0.8 Gy) particle radiation and compared the response with low LET γ-radiation (137Cs; 0.5 Gy/min; 2 Gy). One of the novel findings is the ‘tissue-independent’ activation of TAL2 upon high-energy radiation, and thus qualifies TAL2 as a potential biomarker for particle and other qualities of radiation. Heightened expression of TAL2 gene transcript, which sustained over four weeks post-irradiation foster the concept of oncogene addiction signaling in radiogenic transformation. The positive/negative expression of other selected oncotargets that expresses tissue-dependent manner indicated their role as a secondary driving force that addresses the diversity of tissue-dependent characteristics of tumorigenesis. This study, while reporting novel findings on radiogenic transformation of normal tissue when exposed to particle radiation, it also provides a platform for further investigation into different radiation quality, LET and dose/dose rate effect in healthy organs.

No MeSH data available.