Hailong Pei

MiR-663 inhibits radiation-induced bystander effects by targeting TGFB1 in a feedback mode.

The mechanisms of radiation-induced bystander effects (RIBE) have been investigated intensively over the past two decades. Although quite a few reports demonstrated that cytokines such as TGF-β1 are induced within the directly irradiated cells and play critical roles in mediating the bystander effects, little is known about the signaling pathways that occur in bystander cells. The crucial question as to why RIBE signals cannot be infinitely transmitted, therefore, remains unclear. In the present study, we showed that miR-663, a radiosensitive microRNA, participates in the regulation of biological effects in both directly irradiated and bystander cells via its targeting of TGF-β1. MiR-663 was downregulated, while TGFB1 was upregulated in directly irradiated cells. The regulation profile of miR-663 and TGFB1, on the other hand, was reversed in bystander cells, in which an elevated miR-663 expression was exhibited and led to downregulation of TGF-β1. Further studies revealed that miR-663 interacts with TGFB1 directly and that through its binding to the core regulation sequence, miR-663 suppresses the expression of TGFB1. Based on the results, we propose that miR-663 inhibits the propagation of RIBE in a feedback mode, in which the induction of TGF-β1 by reduced miR-663 in directly irradiated cells leads to increased level of miR-663 in bystander cells. The upregulation of miR-663 in turn suppresses the expression of TGF-β1 and limits further transmission of the bystander signals.

Effects of shielding on the induction of 53BP1 foci and micronuclei after Fe ion exposures

High atomic number and high-energy (HZE) particles in deep space are of low abundance but substantially contribute to the biological effects of space radiation. Shielding is so far the most effective way to partially protect astronauts from these highly penetrating particles. However, simulated calculations and measurements have predicted that secondary particles resulting from the shielding of cosmic rays produce a significant fraction of the total dose and dose equivalent. In this study, we investigated the biological effects of secondary radiation with two cell types, and with cells exposed in different phases of the cell cycle, by comparing the biological effects of a 200 MeV/u iron beam with a shielded beam in which the energy of the iron ion beam was decreased from 500 MeV/u to 200 MeV/u with PMMA, polyethylene (PE), or aluminum. We found that beam shielding resulted in increased induction of 53BP1 foci and micronuclei in a cell-type-dependent manner compared with the unshielded 200 MeV/u Fe ion beam. These findings provide experimental proof that the biological effects of secondary particles resulting from the interaction between HZE particles and shielding materials should be considered in shielding design.

GANRA-5 protects both cultured cells and mice from various radiation types by functioning as a free radical scavenger

Abstract The radio-protective effects of the oxazolone derivative chemical compound 4-(4-methoxy-3-methoxyphenyl-methyl)-2-phenyl- 5(4H)-oxazolone (GANRA-5) against different types of radiation including X-rays, carbon ion beams, microwaves and ultraviolet light (UV) were studied. Cell proliferation/cytotoxicity assay and colony-forming assay were conducted to evaluate the toxicity of GANRA-5. To test its influence on the induction of double-stranded break (DSB) formation and genomic instability, γH2AX focus-forming assay as well as cytokinesis-block micronucleus assay was utilized. Our results indicate that GANRA-5 exhibits low toxicity, while providing high radio-protective effects for MRC-5 cells against different types of radiation. We also found that GANRA-5 acts as a free radical scavenger. Our animal studies provided evidence that GANRA-5 significantly increases the survival rate of mice after X-ray irradiation. Analyses of hemogram, visceral index and detection of superoxide dismutase (SOD) and malondialdehyde (MDA) in the viscera indicate both low toxicity of GANRA-5, combined with its ability to shield radiation risk. In conclusion, our results suggest that GANRA-5 has the potential to be used as a safe and efficient radio-protectant.

GANRA-5 protects mice from X-ray irradiation-induced dysfunction of the immune system

Abstract Ionizing radiation produces reactive oxygen species (ROS), which cause damage to cells. We have synthesized a class of ROS scavengers and found that one of them, named GANRA-5, exhibits high radio-protective effects against both heavy ion irradiation and X-rays, while at the same time displaying low levels of toxicity. Pre-administration with an effective dose of GANRA-5 reduces radiation-induced damage to tissues and increases the survival rate of exposed mice. In this study, we evaluated the changes to the immune system via X-ray irradiation, and investigated how pre-administration of GANRA-5 exhibited preventative characteristics. Compared to the irradiated control groups, GANRA-5 treatment significantly reduced the radiation-induced spleen shrinkage and pathological changes. Moreover, pretreatment with GANRA-5 significantly (p < 0.01) enhanced the cellular immune response, which was characterized by higher peritoneal macrophage as well as splenocyte survival, and a higher ratio of CD4+/CD8+ T lymphocytes. In addition, GANRA-5 treatment before whole body irradiation significantly improved the humoral response (p < 0.01) as indicated by the higher antibody titers of IgG, IgA, and IgM. Furthermore, GANRA-5 treatment significantly (p < 0.01) countered radiation-induced decreases in the titers of serum IL-2 and IL-4 when compared to irradiated but untreated control groups. In summary, these findings indicate that GANRA-5 provides effective protection to the immune system against X-ray-induced immunosuppression.

Ecto-5′-nucleotidase (CD73) is a biomarker for clear cell renal carcinoma stem-like cells

Identification of a specific biomarker for cancer stem cells (CSCs) is of potential applications in the development of effective therapeutic strategies for renal cell carcinoma (RCC). In this study, both the RCC cell line 786-O and surgically removed clear cell RCC (ccRCC) tissues were implemented to grew as spheroids in serum-free medium supplemented with mitogens. This subpopulation possessed key characteristics defining CSCs. We also identified that surgically removed ccRCC tissues were heterogenic and there was a subpopulation of cells that was highly stained with rhodamine-123. Based on membrane-proteomic analyses, CD73 was identified as a candidate biomarker. We further found that CD73high cells were highly tumorigenic. As few as 100 CD73high cells were capable of forming xenograft tumors in non obese diabetic/severe combined immunodeficiency disease mice, whereas 1 × 105 CD73low cells did not initiate tumor formation. During successive culture, the CD73high population regenerated both CD73high and CD73low cells, whereas the CD73low population remained low expression level of CD73. Furthermore, the CD73high cells were more resistant to radiation and DNA-damaging agents than the CD73low cells, and expressed a panel of ‘stemness’ genes at a higher level than the CD73low cells. These findings suggest that a high level of CD73 expression is a bona fide biomarker of ccRCC stem-like cells. Future research will aim at the elucidation of the underlying mechanisms of CD73 in RCC development and the distinct aspects of ccRCC stem-like cells from other tumor types.

Risk assessment of space radiation during manned space flights

During a long-term exploration in space, astronauts will be constantly exposed to space radiation which contains various types of low dose-rate heavy particles. Although the fluxes of these heavy ions are very small, the heavy ions can cause severe biological effects including early effects and late effects. This short review will discuss the biological effects induced by space radiation and introduce a new anti-radiation agent we have developed. We synthesized a class of reactive oxygen species scavengers called GANRA-5 with lowly toxic but high radio-protective effect to both heavy ions and X-rays. GANRA-5 can protect cells from X-rays and carbon ions induced cell killing by significantly reducing the amount of free radical production therefor reduce double-strand breaks and genomic instability. In vivo, GANRA-5 can effectively protect the mice from the damage induced by X-rays irradiation by enhancing superoxide dismutase activities. In brief, GANRA-5 is potentially applicable in space flight.

Long non-coding RNA CRYBG3 regulates glycolysis of lung cancer cells by interacting with lactate dehydrogenase A

Cancer cells usually utilize glucose as a carbon source for aerobic glycolysis, a phenomenon known as the Warburg effect. And a high rate of glycolysis has been observed in lung cancer cells. The growing evidence indicates that long non-coding RNAs (lncRNAs) are important players in lung cancer initiation and progression. However, the correlation between lncRNAs and glycolysis remains unclear. In this study, we recognized a lncRNA, LNC CRYBG3, which can interact with lactate dehydrogenase A (LDHA), a vital enzyme of glycolysis, is highly upregulated in both clinical lung cancer tissues and in vitro cultured lung cancer cell lines. A positive correlation between the expression level of LNC CRYBG3 and LDHA expression levels is observed. In another hand, LNC CRYBG3 is a regulator of glycolysis and its overexpression promoted the uptake of glucose and the production of lactate whereas the knockdown of LNC CRYBG3 led to opposite results and suppressed cell proliferation. These results indicated that LNC CRYBG3 might be a novel target for lung cancer treatment.

Cancer risk of high-charge and -energy ions and the biological effects of the induced secondary particles in space

Space exploration represents great challenge to astronauts’ health because of the uncertain risk of carcinogenesis caused by space radiation, in which high-charge and -energy (HZE) particles should be the most harmful components. Although there are a number of researches confirming that HZE particles have more severe biological effects including tumorigenesis than low-LET radiations, it is still very hard to accurately estimate the cancer risk of space HZE radiation due to the lack of suitable epidemiological data on exposures to low-dose HZE particle irradiation. Ground-based experiments on high-energy heavy ion accelerators might be appropriate complement for understanding the risk of space radiation. On the other hand, effective countermeasures to reduce the radiation damage are essential to manned space exploration. Up to now, shielding is still the most practical way to attenuate biological responses of space radiation. However, the knowledge on the biological effects of secondary particles produced by the interaction of HZE particles with shielding materials is required for space shielding design. This review will discuss the issues of space HZE particles and the biological effects of secondary particles produced by the interaction of space radiation and shielding materials.

A microRNA network functioning in the regulation of radiobiological effects

MicroRNA (miRNA), a small non-coding RNA molecule, is vital in genetic regulation, and miRNA pathway, which regulates gene expression through degradation or translational suppression of their target transcripts, is highly conservative in evolution. Although profiles of miRNAs are different in various cell types and tissues, miRNAs have been considered as a crucial class of regulators in cellular response to ionizing radiation (IR). By carrying out a series of experiments, we have found that altered transcriptional regulation network composed of radiation-mediated miRNAs regulates the expression of their downstream target genes in most biological processes to control cell growth, cell cycle and apoptosis. For example, the newly identified miR-3928 negatively regulates the expression of Dicer, which has been validated by the luciferase assay and western blotting. Dicer is not only a key participant in responding to radiation, but also a critical factor for the maturation of miRNAs, suggesting that miR-3928 affects on the expression of other miRNAs through regulating Dicer. Among the miRNAs controlled by the Dicer, we reveal that miR-185 and miR-663 can efficiently suppress ATR and TGF-β1 expression, which are both important responders in the process of radiobiological effects. Further experiments reveal that the expression of Dicer is suppressed by miR-3928 induced by IR and consequently, the maturation of other miRNAs including miR-185 and miR-663 is inhibited, resulting in the abundantly enhanced expression of ATR and TGF-β1 respectively. This mechanism to hammer at fixing DNA damage or promote cells to apoptosis caused by IR has important implications in the decision of cell fates. Moreover, it has been shown that the expression of BTG1 is characterized in response to factors that induce growth arrest and subsequent differentiation both in vivo and in vitro, affecting cellular physiological progresses of angiogenesis, follicular development and myoblast and B cell differentiation, through regulating cell growth, migration, cell cycle, apoptosis and differentiation. BTG1 gene is phylogenetically highly conserved in its coding and 3′-untranslated region (UTR), which is considered as a decisive element involved in regulation of BTG1 expression. We present evidence that BTG1 can be induced by IR and confirm that miR-454-3p, whose gene locates in the intron of Ska2 gene, can regulate BTG1 expression through directly binding to the 3′-UTR of BTG1 mRNA. These results point out that increased expression of BTG1 caused by the down-regulation of miR-454-3p in case that IR modulates endogenous activity of PRMT1, a BTG1-binding partner, which can methylate endogenous transcription factors to change gene expression pattern and reply radiostilumation. An inverse relationship between the levels of expression of BTG1 and miR-454-3p reveals that there exists a new pathway in response to IR stimulation. Furthermore, cell growth will be transiently increased by the knockdown of BTG1 by transfecting BTG1 siRNA or miR-454-3p mimic. However, the apoptotic state of cells can be tested after 2 days. Down-regulation of BTG1 by miR-454-3p increases the sensitivity of human renal cell carcinoma 786-O cells to IR-induced apoptosis, suggesting that BTG1 could serve as a terget for sensitizing renal carcinoma to standard radiotherapy. Taken together, all these data indicate that alteration of miRNA expression is evident in the cellular response to IR. MiR-3928, miR-185, miR-663 and miR-454-3p may constitute a complex network contributing to the regulation of radiobiological effects. It is apparent that the study of radiation-related miRNAs is beneficial to qualitatively and quantitatively modulating radiobiological effects, and also in favor of the advanced research of miRNA functions.