MicroRNA-9 enhanced radiosensitivity and its mechanism of DNA methylation in non-small cell lung cancer.

In order to improve the therapeutic effect of non-small cell lung cancer (NSCLC), it is critical to combine radiation and gene therapy. Our study found that the activation of microRNA-9 (miR-9) conferred ionizing radiation (IR) sensitivity in cancer cells. Furthermore, increased microRNA-9 promoter methylation level was observed after IR. Our study combined the IR and microRNA-9 overexpression treatment which leads to a significant enhancement in the therapeutic efficiency in lung cancer both in vitro and in vivo. Therefore, it is plausible that microRNA-9 can be used as a novel therapeutic strategy of NSCLC. MTT assay was performed to detect the effect of microRNA-9 on the survival and growth of NSCLC cells. Flow cytometry results showed that microRNA-9 enhanced the apoptosis of NSCLC cells. Wound healing assay found that microRNA-9 can inhibit the migration of NSCLC cells and enhance the effect of radiation on the migration of NSCLC cells. In addition, bisulfate sequencing PCR was performed to analyze the methylation status of the microRNA-9 promoter. In order to determine the effect of microRNA-9 and its promoter methylation status on proliferation and radio-sensitivity in vivo, a subcutaneous tumor formation assay in nude mice was performed. Results have shown that microRNA-9 overexpression increased the radiosensitivity of A549 cells by inhibiting cell activity and migration, and by increasing apoptosis. In addition, the promoter methylation status of the microRNA-9 gene increased in response to ionizing radiation. Our study demonstrated that microRNA-9 enhanced radiosensitivity in NSCLC and this effect is highly regulated by its promoter methylation status. These results will help to clarify regulatory mechanisms of radiation resistance thus stimulate new methods for improving radiotherapy for NSCLC.

Mechanism of MEN1 gene in radiation-induced pulmonary fibrosis in mice.

OBJECTIVE: To investigate the regulatory mechanism of MEN1 gene in radiation-induced lung fibrosis in mice and provide a new theoretical basis for the clinical treatment of radiation pulmonary fibrosis. METHODS: First, 80 C57BL/6 mice aged 8 weeks and weighing 18-22 g were selected, half of them were male and the other half were female. The mice were divided into control group and irradiation group (40 mice in each group) according to the method of the random number table. A radiation-induced lung fibrosis mouse model was established in which a single X-ray irradiation of 20 Gy was applied to the right lung in the irradiation group; H&E and Masson staining were used to verify whether the model was successful at 4, 8, 16 and 24 weeks after irradiation. The expression of MEN1, smooth muscle actin (α-SMA), Collagen-1 and transforming growth factor (TGF-ß) in lung tissue were detected by Western blot and qPCR. Secondly, in the mouse embryonic fibroblast cell line (MEF) and mouse lung epithelial cell line (MLE-12), we constructed cell models of MEN1 knockout and interference separately with the irradiation of 10 Gy X-rays. The expression of α-SMA, Collagen-1, and TGF-ß/Smads signaling pathway molecules was detected by qPCR. Finally, using the immunoprecipitation (IP) method, we can detect the interaction between Smad2 and the protein menin encoded by the MEN1 gene. RESULTS: The results of the radiation pulmonary fibrosis model in mice showed that compared with the control group, the alveolar septum widens, the alveolar integrity decreases, the lung tissue slightly thickens, and a small amount of collagen deposits appear after 4-8 weeks in the model group. At twenty-fourth weeks, a large number of cells in the interstitial space of the lung tissue and a localized focal fibrosis area were observed. Further study found that radiation induced fibrogenic inflammatory cytokines TGF-ß up-regulation, down-regulation of MEN1 gene expression, and then enhanced the expression of α-SMA and promotes the transformation of fibroblasts to myofibroblasts; At the same time, the expression of Collagen-1 was enhanced, which suggested that the extracellular matrix was overconcentrated and eventually promoted the formation of pulmonary fibrosis. In vitro, we found that knockout and interference of MEN1 gene can significantly enhance radiation-induced fibrosis, and up-regulate the expression of downstream molecules Smad2 and Smad3 of TGF-ß signaling pathway, and down-regulate the expression of Smad7. Furthermore, it played an important role in regulating the process of radionuclide fibrosis. CONCLUSION: MEN1 plays a key role in the formation of pulmonary fibrosis by regulating the secretion of TGF-ß and the activation of TGF-ß/Smads signaling pathway.

MicroRNA-9 functions as a tumor suppressor and enhances radio-sensitivity in radio-resistant A549 cells by targeting neuropilin 1.

Radiotherapy is commonly used to treat lung cancer but may not kill all cancer cells, which may be attributed to the radiotherapy resistance that often occurs in non-small cell lung cancer (NSCLC). At present, the molecular mechanism of radio-resistance remains unclear. Neuropilin 1 (NRP1), a co-receptor for vascular endothelial growth factor (VEGF), was demonstrated to be associated with radio-resistance of NSCLC cells via the VEGF-phosphoinositide 3-kinase-nuclear factor-κB pathway in our previous study. It was hypothesized that certain microRNAs (miRs) may serve crucial functions in radio-sensitivity by regulating NRP1. Bioinformatics predicted that NRP1 was a potential target of miR-9, and this was validated by luciferase reporter assays. Functionally, miR-9-transfected A549 cells exhibited a decreased proliferation rate, increased apoptosis rate and attenuated migratory and invasive abilities. Additionally, a high expression of miR-9 also significantly enhanced the radio-sensitivity of A549 cells in vitro and in vivo. These data improve understanding of the mechanisms of cell radio-resistance, and suggest that miR-9 may be a molecular target for the prediction of radio-sensitivity in NSCLC.

Neuropilin 1 expression correlates with the Radio-resistance of human non-small-cell lung cancer cells.

The purpose of this study was to determine the correlation between over-expression of the neuropilin 1 (NRP1) gene and growth, survival, and radio-sensitivity of non-small cell lung carcinoma (NSCLC) cells. 3-[4,5-dimethylthylthiazol-2-yl]-2,5 diphenyltetrazolium broide (MTT) and colony assays were then performed to determine the effect of NRP1 inhibition on the in vitro growth of NSCLC cells. The Annexin V-Fluorescein Isothiocyanate (FITC) apoptosis detection assay was performed to analyse the effect of NRP1 enhancement on apoptosis of NSCLC cells. Transwell invasion and migration assays were employed to examine the metastatic ability of A549 cells post X-ray irradiation. In addition, Western blot assays were carried out to detect the protein level of VEGFR2, PI3K and NF-κB. Finally, to examine the effect of shNRP1 on proliferation and radio-sensitivity in vivo, a subcutaneous tumour formation assay in nude mice was performed. Microvessel density in tumour tissues was assessed by immunohistochemistry. The stable transfected cell line (shNRP1-A549) showed a significant reduction in colony-forming ability and proliferation not only in vitro, but also in vivo. Moreover, shRNA-mediated NRP1 inhibition also significantly enhanced the radio-sensitivity of NSCLC cells both in vitro and in vivo. The over-expression of NRP1 was correlated with growth, survival and radio-resistance of NSCLC cells via the VEGF-PI3K- NF-κB pathway, and NRP1 may be a molecular therapeutic target for gene therapy or radio-sensitization of NSCLC.

Role of PLC-PIP2 and cAMP-PKA signal pathways in radiation-induced immune-suppressing effect.

OBJECTIVE: The purpose of the present study was to observe the changes in CD4+CD25+Nrp1+Treg cells after irradiation with different doses and explore the possible molecular mechanisms involved. METHODS: ICR mice and mouse lymphoma cell line (EL-4 cells) was used. The expressions of CD4, CD25, Nrp1, calcineurin and PKC-α were detected by flow cytometry. The expressions of TGF-ß1, IL-10, PKA and cAMP were estimated with ELISA. RESULTS: At 12 h after irradiation, the expression of Nrp1 increased significantly in 4.0 Gy group, compared with sham-irradiation group (P<0.05) in the spleen and thymus, respectively, when ICR mice received whole-body irradiation (WBI). Meanwhile the synthesis of Interleukin 10 (IL-10) and transforming growth factor-ß1 (TGF-ß1) increased significantly after high dose irradiation (HDR) (> or = 1.0 Gy). In addition, the expression of cAMP and PKA protein increased, while PKC-α, calcineurin decreased at 12h in thymus cells after 4.0 Gy X-irradiation. While TGF-ß1 was clearly inhibited when the PLC-PIP2 signal pathway was stimulated or the cAMP-PKA signal pathway was blocked after 4.0 Gy X-irradiation, this did not limit the up-regulation of CD4+CD25+Nrp1+Treg cells after ionizing radiation. CONCLUSION: These results indicated that HDR might induce CD4+CD25+Nrp1+Treg cells production and stimulate TGF-ß1 secretion by regulating signal molecules in mice.

A study of circulating gliadin antibodies in schizophrenia among a Chinese population.

The present work measured circulating antibodies against native gliadins, deamidated gliadin-derived epitopes, and transglutaminase 2 (TGM2) in 473 patients with schizophrenia and 478 control subjects among a Chinese population. The results showed that 27.1% of patients with schizophrenia were positive for the IgA antibody against native gliadins compared with 17.8% of control subjects (χ(2) = 11.52, P = .0007, OR = 1.72, 95% CI 1.25-2.35), although this significant difference appeared to be due mainly to low IgA gliadin antibody levels in female controls. A total of 27.6% of female patients were positive for IgA gliadin antibodies compared with 13.9% of female controls (χ(2) = 10.46, P = .0012, OR = 2.36, 95% CI 1.39-4.01), and 26.4% of male patients were positive for IgA antibodies compared with 19.8% of male controls (χ(2) = 3.26, P = .071, OR = 1.46, 95% CI 0.97-2.19). Of 128 patients who were positive for the IgA antibody against native gliadins, 8 were positive for the IgA antibody against deamidated gliadin epitopes and 1 was positive for IgA anti-TGM2 antibody. However, quantitative analysis demonstrated that the mean levels of IgA antibodies against deamidated gliadin epitopes and TGM2 were significantly lower in patients with schizophrenia than the control subjects (P < .001 and P = .008, respectively). The prevalence of IgG antibodies against native gliadins was not significantly different between the patient group and the control group (χ(2) = 2.25, P = .134, OR = 1.32, 95% CI 0.92-1.88). This study suggests that specific gliadin-derived epitopes may be involved in schizophrenia.

Genetic and functional study of the IPO5 gene in schizophrenia.

The present work reported on a weak association of the importin 5 (IPO5) gene with schizophrenia in combined family and case-control samples and also investigated a possible mechanism by which the IPO5 gene may contribute to the development of the disease in a Chinese population. Our results suggest that abnormal expression and alternative splicing of the IPO5 gene may be involved in the pathophysiology of schizophrenia.

Increase in efficacy of cancer radiotherapy by combination with whole-body low dose irradiation.

PURPOSE: Design of cancer radiotherapy protocol to reduce radiation dose and increase treatment efficacy in Lewis lung cancer (LLC) model. METHODS: C57BL/6J mice subcutaneously implanted with LLC were treated by conventional radiotherapy (2Gy x 6) combined with LDWBI (low dose whole-body irradiation; the second, third, fifth and sixth local doses of 2Gy each substituted by LDWBI with 0.075Gy) and/or gene therapy (intratumor injection of pEgr-IL-18-B7.1 plasmid 24 h before the first and fourth local doses). Immunologic mechanisms were explored. RESULTS: Cancer control was most significantly improved in the group receiving local radiotherapy combined with LDWBI and gene therapy as shown by prolongation of mean survival time by 60.4%, reduction in average tumor weight by 70.8%, decrease in pulmonary metastasis by 66.9% and decrease in intratumor angiogenesis by 64.8% as compared to local radiotherapy alone (p < 0.05). These changes in tumor growth and progression were accompanied with up-regulation of host immunity manifested by stimulated NK (natural killer) and CTL (cytotoxic T lymphocyte) activity, IFN (interferon)-gamma and TNF (tumor necrosis factor)-alpha secretion, PKC (protein kinase C)-theta activation and LAMP (lysosomal associated membrane protein)-1 expression. CONCLUSION: Combination of conventional radiotherapy with LDWBI and gene transfer could reduce total radiation dose by 2/3 and at the same time improve treatment efficacy of cancer accompanied with up-regulated host anticancer immunity.

Combination of human plasminogen kringle 5 with ionizing radiation significantly enhances the efficacy of antitumor effect.

Antiangiogenic therapy could destroy tumor vasculature and inhibit tumor growth. It might inhibit tumor growth significantly when used as a single treatment modality and its therapeutic benefit may even be greater when used in combination with established treatment modalities such as radiation therapy (RT). In the present report, we investigated the effect of recombinant human plasminogen kringle 5 domain (rhK5) in combination with ionizing radiation on angiogenesis, tumor growth and survival in a murine Lewis lung carcinoma (LLC) tumor model. Combined treatment using rhK5 and radiotherapy displayed obvious suppressive effect on LLC tumor growth as compared with single treatment with either modality (p < 0.05), and resulted in a more additive effect on tumor growth delay in this model. In addition, combined treatment significantly enhanced the survival of mice and no toxic effect, such as weight loss, was observed. The significant antitumor effect of rhK5 plus radiation was associated with a direct suppression effect on early neoangiogenesis and tumor cell apoptosis. Furthermore, the expression of VEGF and HIF-1alpha in tumor tissue correlated well with decreased vessel density. The results suggest that rhK5 significantly enhances the antitumor activity of RT and could be a potent adjuvant therapeutic approach to improve the efficacy of radiotherapy for lung cancer.

UVB induced oxidative stress in human keratinocytes and protective effect of antioxidant agents.

This study aims at exploring the oxidative stress in keratinocytes induced by UVB irradiation and the protective effect of nutritional antioxidants. Cultured Colo-16 cells were exposed to UVB in vitro followed by measurement of reactive oxygen species (ROS), endogenous antioxidant enzyme activity, as well as cell death in the presence or absence of supplementation with vitamin C, vitamin E, or Ginsenoside Panoxatriol. Intracellular ROS content was found significantly reduced 1 h after exposure, but increased at later time points. After exposure to 150-600 J m(-2) UVB, reduction of ROS content was accompanied by increased activity of catalase and CuZn-superoxide dismutase at early time points. Vitamins C and E, and Ginsenoside Panoxatriol counteracted the increase of ROS in the Colo-16 cells induced by acute UVB irradiation. At the same time, Ginsenoside Panoxatriol protected the activity of CuZn-superoxide dismutase, while vitamin E showed only a moderate protective role. Vitamins C and E, and Ginsenoside Panoxatriol in combination protected the Colo-16 cells from UVB-induced apoptosis, but not necrosis. These findings suggest that vitamins C and E as well as Ginsenoside Panoxatriol are promising protective agents against UVB-induced damage in skin cells.

Ionizing radiation stimulates secretion of pro-inflammatory cytokines: dose-response relationship, mechanisms and implications.

In previous studies we showed a marked increase in secretion of inflammatory cytokines TNFalpha and interleukin (IL)-1beta by mouse macrophages in response to different doses of ionizing radiation (IR). Here we show the stimulation of IL-12 and IL-18 secretion by mouse peritoneal macrophages after whole-body irradiation with exploration of the possible mechanisms and implications in cancer radiotherapy. Both low (0.075 Gy) and high (2 Gy) doses of IR were found to cause sustained stimulation of IL-12 and IL-18 secretion by mouse macrophages; this paralleled the activation of NF-kappaB as well as up-regulated expression of CD14 and TLR4-MD2 on the macrophage surface and MyD88 in the cytoplasm. The expression of CD14, TLR4-MD2 and MyD88 increased in a dose-dependent manner from radiation doses between 0.05 and 2 Gy. The secretion of IL-12 and IL-18 showed a dose-dependent increase from doses between 0.05 and 4 Gy. It is concluded that IR can stimulate the secretion of IL-12 and IL-18 presumably via activation of the Toll signaling pathway in macrophages. The potential harmful effect of repeated doses of radiation used in radiotherapy for certain cancers is discussed.

Therapeutic effect of gene-therapy in combination with local X-irradiation in a mouse malignant melanoma model.

Plasmid containing mIL-18 and B7.1 genes downstream of Egr-1 promoter was constructed and used in gene-radiotherapy on malignant melanoma in C57BL/6J mice implanted with B16 cells followed by exploration of the immunologic mechanism of the therapeutic effect. The treatment with plasmid pEgr-IL-18-B7.1 plus local X-irradiation showed more effective suppression of tumor growth than the treatment with radiation alone, pEgr-IL-18-B7.1 alone, or single gene pEgr-IL-18 (or pEgr-B7.1) combined with local X-irradiation. Anticancer immunity was found to be significantly upregulated in tumor-bearing mice treated with pEgr-IL-18-B7.1 plus local X-irradiation. IL-18 showed no direct killing effect on malignant melanoma cells in vitro, and the mechanism of the combined therapy with pEgr-IL-18-B7.1 and local X-irradiation was apparently related with the stimulation of host anticancer immunity by increased secretion of IL-18 and upregulated immunogenicity of the tumor cells by increased expression of B7.1 on their surface in addition to the direct effect of local X-irradiation on the tumor cells.

Radiation-induced bystander effect in immune response.

OBJECTIVE: Since most reports on bystander effect have been only concerned with radiation-induced damage, the present paper aimed at disclosing whether low dose radiation could induce a stimulatory or beneficial bystander effect. METHODS: A co-culture system containing irradiated antigen presenting cells (J774A.1) and unirradiated T lymphocytes (EL-4) was established to observe the effect of J774A.1 cells exposed to both low and high doses of X-rays on the unirradiated EL-4 cells. Incorporation of 3H-TdR was used to assess the proliferation of the EL-4 cells, expression of CD80/86 and CD48 on J774A.1 cells was measured with immunohistochemistry and flow cytometry, respectively. NO release from J774A.1 cells was estimated with nitrate reduction method. RESULTS: Low dose-irradiated J774A.1 cells could stimulate the proliferation of the unirradiated EL-4 cells while the high dose-irradiated J774A.1 cells exerted an inhibitory effect on the proliferation of the unirradiated EL-4 cells. Preliminary mechanistic studies illustrated that the differential changes in CD48 expression and NO production by the irradiated J774A.1 cells after high and low dose radiation might be important factors underlying the differential bystander effect elicited by different doses of radiation. CONCLUSION: Stimulatory bystander effect can be induced in immune cells by low dose radiation.