Colchicine sensitizes human hepatocellular carcinoma cells to damages caused by radiation

AIM： We studied the effect of colchicine combined with radiation on the survival of human hepatocellular carcinoma （HCC） HA22T/VGH cells.METHODS： Twenty-four hours after treatment with 0-8 ng/mL colchicine, HA22T/VGH cells were irradiated at various doses （0, 1, 2, 4, and 8 Gy）. Colony assay was performed to assess the surviving cell fraction. Survival curves were fitted by using a linear-quadratic model to estimate the sensitizer enhancement ratio （SER）. Flow cytometry was used for cell cycle analysis.RESULTS： Colchicine at lower concentrations （1 and 2 ng/mL） had obvious synergy with radiation to inhibit HCC cell growth, whereas higher concentrations （4 and 8 ng/mL） had only additive effect to radiation. Pretreatment with 1 and 2 ng/mL colchicine for 24-h enhanced cell killing by radiation with SERs of 1.21 and 1.53, respectively.G2/N arrest was only observed with higher colchicine doses （8 and 16 ng/mL） after 24-h treatment, this effect was neither seen with lower doses （1, 2, and 4 ng/mL）nor with any dose after only 1 h of treatment.CONCLUSION： Our results suggest that colchicine has potential as an adjunct to radiotherapy for HCC treatment.Lower doses of colchicine possess radiosensitizing effects via some mechanism other than G2/M arrest. Further study is necessary to elucidate the mechanism.

A Sensitivity Study of IAP AGCM to Radiation Changes: Climate Simulation of 125kyr and 115kyr before Present

The IAP AGCM was used to simulate the climate of 125kyr and 115kyr before present. We analysed the results and then studied the sensitivity of the model to the changes of radiation distribution induced by orbital parameter changes. The reasonability of the results was also discussed.

Observations and Modeling of Incoming Longwave Radiation to Snow Beneath Forest Canopies in the West Tianshan Mountains, China

Forest canopy reduces shortwave radiation and increases the incoming longwave radiation to snowpacks beneath forest canopies. Furthermore, the effect of forest canopy may be changed by complex topography. In this paper, we measured and simulated the incoming longwave radiation to snow beneath forest at different canopy openness in the west Tianshan Mountains, China(43°16'N, 84°24'E) during spring 2013. A sensitivity study was conducted to explore the way that terrain influenced the incoming longwave radiation to snow beneath forest canopies. In the simulation model, measurement datasets, including air temperature, incoming shortwave radiation above canopy, and longwave radiation enhanced by adjacent terrain, were applied to calculate the incoming longwave radiation to snow beneath forest canopy. The simulation results were consistent with the measurements on hourly scale and daily scale. The effect of longwave radiation enhanced by terrain was important than that of shortwave radiation above forest canopy with different openness except the 20% canopy openness. The longwave radiation enhanced due to adjacent terrain increases with the slope increase and temperature rise. When air temperature(or slope) is relatively low, thelongwave radiation enhanced by adjacent terrain is not sensitive to slope(or air temperature), but the sensitivity increases with the decrease of snow cover area on sunny slope. The effect of longwave radiation is especially sensitive when the snow cover on sunny slope melts completely. The effect of incoming shortwave radiation reflected by adjacent terrain on incoming longwave radiation to snow beneath forest canopies is more slight than that of the enhanced longwave radiation.

Apoptotic Sensitivity to Irradiation Increased after Transfection of chk1 Antisense Chain to HL-60 Cell Line

Summary： The HL-60 cells were transfected with chkl antisense and sense chain, and 24 h later subjected to irradiation. Twenty-four h after irradiation, the changes in the chk1 protein expression was assayed by Western blot, and the cell cycles and apoptosis rate detected by FCM. The irradiated apoptosis sensitivity was increased by antisense blocking of chk1 gene in HL-60 cell line with the apoptosis rate being 26.31 %, significantly higher than that by the sense blocking （10.34 %, 0. 025〈P〈0.05）. In HL-60 cells transfected with chkl antisense chain, the G2/M phase arrest was attenua：ted and the cells in G2/M phase were accounted for 38.42 %, significantly lower than those of the cells transfected with chkl sense chain （54.64 %, 0. 005〈P〈0.01）. It was concluded that antisense blocking of chk1 gene could increase the apoptosis sensitivity to irradiation.

Experimental investigation of pre-irradiation effect on radiation sensitivity of temperature sensing fiber Bragg gratings

The effect of pre-irradiation on radiation sensitivity of fiber Bragg gratings （FBGs） is verified experimentally. FBGs are fabricated in photosensitive optical fibers and single mode fibers with Ce-concentration in a range from 3 mol% to 23.37 mol% in the core. In experiments, the FBGs are subjected to twice v-radiation exposures to a Co^60 source at a dose-rate of 0.1 Gy/s up to a total dose of 50 kGy. Pre-irradiation treatment can reduce the temperature sensitivity variation of FBGs by 18.12%-35.91%, as well as Bragg wavelength shift （BWS） by 8%-27.08 %. Our research demonstrates that pre-irradiation treatment is a feasible method to improve the radiation tolerance of FBGs.

DNA repair genes BRCA1 and DNA-PKcs have great potential in radiation therapy

Radiotherapy is a part of the front-line treatment regime for many cancers. The mechanisms of radiation-induced effects in cancers mainly involves double-strand breaks (DBS) which plays very important role in maintaining the stability of gene. As DNA repair gene breast cancer 1 (BRCA1) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) can act to maintain genetic stability though two distinct and complementary mechanisms for DNA DSB repair-homologous recombination (HR) and non-homologous end joining (NHEJ). Therefor, BRCA1 and DNA-PKcs are closely associated with radiation sensitivity, which means that they may be used as a useful tool to predict radio sensitivity in human tumour cells.

Injectable hydrogel-based drug delivery systems for enhancing the efficacy of radiation therapy:A review of recent advances

Radiotherapy(RT)is a crucial treatment for cancer;however,its effectiveness is limited by adverse effects on normal tissues,radioresistance,and tumor recurrence.To overcome these challenges,hydrogels have been employed for delivery of radiosensitizers and other therapeutic agents.This review summarizes recent advancements in the application of hydrogel-based local drug delivery systems for improving the therapeutic efficacy of RT in cancer treatment.Firstly,we introduce the classification and properties of hydrogels.Next,we detail hydrogel-based platforms designed to enhance both external beam radiation therapy and brachytherapy.We also discuss hydrogels used in combination therapy involving RT and immunotherapy.Lastly,we highlight the challenges that hydrogels face in RT.By surveying the latest developments in hydrogel applications for RT,this review aims to provide insights into the development of more effective and targeted cancer therapies.

YWHAZ gene contributes to the radioresistance of oral squamous cell carcinoma cells

Objective:To investigate the contribution of YWHAZ gene on the radioresistance and metastasis ability of oral squamous cell carcinoma(OSCC)cells.Mathods:The relationship between the expression level of YWHAZ gene and the survival of head and neck squamous cell carcinoma(HNSC)patients was analyzed using Gene Expression Profiling Interactive Analysis(GEPIA)database.A radioresistance cell line(CAL-27R)was constructed by irradiating CAL-27 cells with frac-tional doses.Cell survival was measured by colony formation assay.Cell migration and invasion were detected by transwell assay.The formation of yH2AX foci was detected by immunofluorescence assay,The protein expressions were detected by Westemn blot assay.In some experiments,CAL-27R cells were effectively transferred with siRNA YWHAZ(siYWHAZ).Results:GEPIA database showed that the expression level of YWHAZ in HNSC tumors was higher than that in adjacent normal tissues,and the HNSC patients with higher level of YWHAZ had a shorter survival.In vitro experiments demonstrated that the expression of YWHAZ protein in CAL-27 cells was lower than HSC-3 cells(t=18.89,P<0.01)and radioresistant CAL-27R cells(t=25.70,P<0.01).Knockdown of YWHAZ gene significantly increased radiation-induced cell killing effect,apoptosis induction,and yH2AX foci formation inCAL-27R and HSC-3 cells.Moreover,siRNA YWHAZ transfection also reduced the invasion and migration abilities of the irradiated CAL 27R[t=21.09,P<0.01(migration);t=6.16,P<0.05(invasion)]and HSC-3 cells[t=34.53,P<0.001(migration);t=4.92,P<0.05(invasion)]and attenuated radiation-induced expressions of metastasis-related proteins,Conclusion:YWHAZ contributes to the radioresistance of oral squamous cells and thus it may applicable to be a potential target for OSOC radiotherapy.