Hongyan Li

Curcumin ameliorates cognitive deficits heavy ion irradiation-induced learning and memory deficits through enhancing of Nrf2 antioxidant signaling pathways.

Oxidative stress is one of the major mechanisms implicated in carbon ion irradiation. Curcumin is a natural phenolic compound with impressive antioxidant properties. Whats more, curcumin is recently proved to exert its effects partly radioprotection. In vivo, we investigated the protective effects of curcumin against (12)C(6+)radiation-induced cerebral injury. Our results showed that 4Gy heavy ion radiation-induced spatial strategy and memory decline and reduction of brain superoxide dismutase (SOD) activity levels were all consistently improved by curcumin, and the augmentation of cerebral malonaldehyde (MDA) was lowered by curcumin. Furthermore, both the cerebral cells nuclear erythroid 2-related factor 2 (Nrf2) protein and three typically recognized Nrf2 downstream genes, NAD(P)H quinine oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), and γ-glutamyl cysteine synthetase (γ-GCS) were consistently up-regulated in curcumin-pretreated mice. Our study confirmed the antagonistic roles of curcumin to counteract radiation-induced cerebral injury in vivo and suggested that the potent Nrf2 activation capability might be valuable for the protective effects of curcumin against radiation. This provides a potential useful radioprotection dietary component for human populations.

Proteome analysis for profiling infertility markers in male mouse sperm after carbon ion radiation

Ion radiation or radiotherapy is used to treat male patients with oligozoospermia, azoospermia, temporarily infertility, or even permanent infertility. The present study aims to investigate the potential infertility mechanism of sperm in mice after carbon ion radiation (CIR). The caudal epididymal sperm of male mice whole-body irradiated with carbon ion beam (0.5Gy and 4Gy) were used 7 days after irradiation. A two-dimensional gel electrophoresis approach was employed to investigate the changes in protein expression in the caudal edididymal sperm. Spot detection and matching were performed using the PDQuest 8.0 software. The criteria used to select spots for the analysis were more than a threefold difference in protein quantities (normalized spot volume), which allowed the detection of six differentially expressed proteins. Protein identification was performed using MALDI-TOF-TOF. Six specific proteins were identified by searching the NCBI protein sequence database. Among these proteins, HSP 70-2, PLC, GPX4, β-tubulin, and GAPDHS were associated with sperm motility, which can affect fertility. β-tubulin is important in axoneme migration flagellar movement and regulation, and GAPDHS is related to sperm energy supply. We analyzed their expressions using immunoblotting and immunofluorescence. The changes in sperm protein expression after CIR are mainly associated with motility. These proteins are potential markers for the mechanisms of infertility in space or radiotherapy.

Carbon Ion Beams Induce Hepatoma Cell Death by NADPH Oxidase‐Mediated Mitochondrial Damage

Mitochondria are a major source of reactive oxygen species (ROS) and are also the target of cellular ROS. ROS damage to mitochondria leads to dysfunction that further enhances the production of mitochondrial ROS. This feed‐forward vicious cycle between mitochondria and ROS induces cell death. Within a few minutes of radiation exposure, NADPH oxidase is activated to elevate the ROS level. Activated NADPH oxidase might induce the feed‐forward cycle of mitochondria and this is a possible mechanism for cancer cell death induced by heavy ion irradiation. We found that after 4 Gy of 12C6+ ion radiation of HepG2 cells, the NADPH oxidase membrane subunit gp91phox was not involved in enzyme activation through increased expression; however, the subunit p47phox was involved in activation by being translocated to the membrane. 12C6+ ion radiation clearly decreased the ΔΨm of HepG2 cells, increasing mitochondrial DNA damage and inducing cell death. Pretreatment with apocynin (APO, an NADPH oxidase inhibitor) effectively prevented the ΔΨm decrease, mitochondrial DNA damage, and cell death induced by radiation. However, these protective effects were not observed with APO treatment after irradiation exposure. These data demonstrated that NADPH oxidase activation was an initiator in mitochondrial damage. Once mitochondria entered the feed‐forward cycle, cell fate was no longer controlled by NADPH oxidase. Only antioxidants that targeted mitochondria such as MitoQ could break the cycle and release cells from death. J. Cell. Physiol. 229: 100–107, 2014.

Downregulation of Nrf2 promotes radiation-induced apoptosis through Nrf2 mediated Notch signaling in non-small cell lung cancer cells

The nuclear factor erythroid-2-related factor 2 (Nrf2) is a crucial regulator of the cellular antioxidant system. Nrf2 is often constitutively activated in non-small cell lung cancer (NSCLC) cell lines, which promotes cytoprotection against oxidative stress and xenobiotics. Notch1 signaling is critically implicated in cell fate determination. It has been reported that Nf2 strongly regulates Notch1 activity. However, the role of Nrf2 mediated Notch1 signaling in response to ionizing radiation (IR) remains elusive. We report that knockdown of Nrf2 promotes radiation-induced apoptosis through Nrf2 mediated Notch1 signaling in NSCLC cells. IR activated Nrf2 in a dose-dependent manner and the expression of Nrf2 was significantly elevated at 4 h after exposure. RNAi-mediated reduction of Nrf2 significantly increased endogenous ROS levels, and decreased the expression of glutamate cysteine ligase catalytic subunit (GCLC), heme oxygenase-1 (HO-1) and NAD (P) H quinine oxidoreductase-1 (NQO1) in irradiated cells. Furthermore, decrease in Nrf2 expression significantly dampened Notch1 expression following ionizing radiation exposure, and potentiated IR-induced cellular apoptosis. These results demonstrated that Nrf2 could be activated by ionizing radiation, knockdown of Nrf2 could promote radiation induced apoptosis and Nrf2-mediated Notch signaling is an important determinant in radioresistance of lung cancer cells.

Mechanisms, function and clinical applications of DNp73

p73, has two distinct promoters, which allow the formation of two protein isoforms: full-length transactivating (TA) p73 and an N-terminally truncated p73 species (referred to as DNp73) that lacks the N-terminal transactivating domain. Although the exact cellular function of DNp73 is unclear, the high expression levels of the genes have been observed in a variety of human cancers and cancer cell lines and have been connected to pro-tumor activities. Hence the aim of this review is to summarize DNp73 expression status in cancer in the current literature. Furthermore, we also focused on recent findings of DNp73 related to the biological functions from apoptosis, chemosensitivity, radiosensitibity, differentiation, development, etc. Thus this review highlights the significance of DNp73 as a marker for disease severity in patients and as target for cancer therapy.

Simulated Microgravity Conditions and Carbon Ion Irradiation Induce Spermatogenic Cell Apoptosis and Sperm DNA Damage

OBJECTIVE To investigate the effect of simulated microgravity and carbon ion irradiation (CIR) on spermatogenic cell apoptosis and sperm DNA damage to the testis of male Swiss Webster mice, and assess the risk associated with space environment. METHODS Sperm DNA damage indicated by DNA fragmentation index (DFI) and high DNA stainability (HDS) was measured by sperm chromatin structure assay (SCSA). Apoptosis of spermatogenic cells was detected by annexin V-propidium iodide assay. Bax (the expression levels of p53) and proliferating cell nuclear antigen (PCNA) were measured by immunoblotting; p53 and PCNA were located by immunohistology. RESULTS HDS, DFI, apoptosis index, and the expression levels of p53 and Bax were detected to be significantly higher in the experimental groups (P<0.05) compared with those in the control group; however, the PCNA expression varied to a certain degree. p53- and PCNA- positive expression were detected in each group, mainly in relation to the spermatogonic cells and spermatocytes. CONCLUSION The findings of the present study demonstrated that simulated microgravity and CIR can induce spermatogenic cell apoptosis and sperm DNA damage. Sperm DNA damage may be one of the underlying mechanisms behind male fertility decline under space environment. These findings may provide a scientific basis for protecting astronauts and space travelers health and safety.

Proteomic analysis for testis of mice exposed to carbon ion radiation.

This paper investigates the mechanism of action of heavy ion radiation (HIR) on mouse testes. The testes of male mice subjected to whole body irradiation with carbon ion beam (0.5 and 4Gy) were analyzed at 7days after irradiation. A two-dimensional gel electrophoresis approach was employed to investigate the alteration of protein expression in the testes. Spot detection and matching were performed using the PDQuest 8.0 software. A difference of more than threefold in protein quantity (normalized spot volume) is the standard for detecting differentially expressed protein spots. A total of 11 differentially expressed proteins were found. Protein identification was performed using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-TOF). Nine specific proteins were identified by searching the protein sequence database of the National Center for Biotechnology Information. These proteins were found involved in molecular chaperones, metabolic enzymes, oxidative stress, sperm function, and spermatogenic cell proliferation. HIR decreased glutathione activity and increased malondialdehyde content in the testes. Given that Pin1 is related to the cell cycle and that proliferation is affected by spermatogenesis, we analyzed testicular histological changes and Pin1 protein expression through immunoblotting and immunofluorescence. Alterations of multiple pathways may be associated with HIR toxicity to the testes. Our findings are essential for studies on the development, biology, and pathology of mouse testes after HIR in space or radiotherapy.

Differential proteome and gene expression reveal response to carbon ion irradiation in pubertal mice testes.

Heavy ion radiation, a high linear energy transfer (LET) radiation, has been shown to have adverse effects on reproduction in male mice. The aim of this study was to profile and investigate the differentially expressed proteins in pubertal male mice testes following carbon ion radiation (CIR). Male mice underwent whole-body irradiation with CIR (1 and 4 Gy), and MALDI-TOF/TOF analysis was used to investigate the alteration in protein expression in 2-DE (two-dimensional gel electrophoresis) gels of testes caused by irradiation after 14 days. 8 differentially expressed proteins were identified and these proteins were mainly involved in energy supply, the endoplasmic reticulum, cell proliferation, cell cycle, antioxidant capacity and mitochondrial respiration, which play important roles in the inhibition of testicular function in response to CIR. Furthermore, we confirmed the relationship between transcription of mRNA and the abundance of proteins. Our results indicated that these proteins may lead to new insights into the molecular mechanism of CIR toxicity, and suggested that the gene expression response to CIR involves diverse regulatory mechanisms from transcription of mRNA to the formation of functional proteins.

Diallyl disulfide attenuated carbon ion irradiation-induced apoptosis in mouse testis through changing the ratio of Tap73/ΔNp73 via mitochondrial pathway

Diallyl disulfide (DADS), a major organosulfur compound derived from garlic, has various biological properties, including anti-cancer effects. However, the protective mechanism of DADS against radiation-induced mouse testis cell apoptosis has not been elucidated. In this study, the magnitude of radiation effects evoked by carbon ion irradiation was marked by morphology changes, significant rise in apoptotic cells, activation expression of p53, up regulation the ratio of pro-apoptotic Tap73/anti-apoptotic ΔNp73, as well as alterations of crucial mediator of the mitochondrial pathway. Interestingly, pretreatment with DADS attenuated carbon ion irradiation-induced morphology damages and apoptotic cells. Additionally, DADS elevated radiation-induced p53 and p21 expression, suggesting that p53 might be involved in the inhibition of cell cycle progression through up regulation of p21. Furthermore, administration with DADS prevented radiation-induced Tap73/ΔNp73 expression and consequently down regulated Bax/Bcl-2 ratio, cytochrome c release and caspase-3 expression, indicating that the balance between Tap73 and ΔNp73 had potential to activate p53 responsive genes. Thus, our results showed that radio protection effect of DADS on mouse testis is mediated by blocking apoptosis through changing the ratio of Tap73/ΔNp73 via mitochondrial pathway, suggesting that DADS could be used as a potential radio protection agent for the testis against heavy-ion radiation.

Diallyl disulfide enhances carbon ion beams–induced apoptotic cell death in cervical cancer cells through regulating Tap73 /ΔNp73

Diallyl disulfide (DADS), extracted from crushed garlic by steam-distillation, has been reported to provide the anticancer activity in several cancer types. However, the effect of DADS on high-LET carbon beams - induced cell death remains unknown. Therefore, we used human cervical cancer cells to elucidate the molecular effects of this dallyl sulfide. Radiotherapy remains the mainstay of treatment, especially in advanced cervical cancer and there is still space to improve the radiosensitivity to reduce radiation dosage. In this study, we found that radiation effects evoked by high-LET carbon beam was marked by inhibition of cell viability, cell cycle arrest, significant rise of apoptotic cells, regulation of transcription factor, such as p73, as well as alterations of crucial mediator of the apoptosis pathway. We further demonstrated that pretreatment of 10 µM DADS in HeLa cells exposed to radiation resulted in decrease in cell viability and increased radiosensitivity. Additionally, cells pretreated with DADS obviously inhibited the radiation-induced G2/M phase arrest, but promoted radiation-induced apoptosis. Moreover, combination DADS and the radiation exacerbated the activation of apoptosis pathways through up-regulated ration of pro-apoptotic Tap73 to anti-apoptotic ΔNp73, and its downstream proteins, such as FASLG, and APAF1. Taken together, these results suggest that DADS is a potential candidate as radio sensitive agent for cervical cancer.