Research progress on radio-resistance mechanism of nasopharyngeal carcinoma / 中华放射肿瘤学杂志

Nasopharyngeal carcinoma is one of the most common malignant head and neck tumors, and radiotherapy is the main treatment. However, radio-resistance is a key cause of local recurrence of nasopharyngeal carcinoma. Therefore, overcoming the radio-resistance of nasopharyngeal carcinoma and enhancing the radiosensitivity have become urgent problems in the treatment of nasopharyngeal carcinoma, which also play a key role in improving the overall survival rate of patients. In this article, recent studies on DNA, non-coding RNA (ncRNA), protein and cell behaviors related to radio-resistance of nasopharyngeal carcinoma were reviewed, aiming to provide valuable ideas for clinical treatment of nasopharyngeal carcinoma.

Elevated miR-27b-3p enhances the radioresistance by targeting PLK2 in breast cancer / 中华放射医学与防护杂志

Objective:To investigate the effect of miR-27b-3p on radiation resistance of breast cancer cells.Methods:The relative expression levels of miR-27b-3p in normal tissues and breast cancer tissues were analyzed through GEO database and verified by the qRT-PCR assay. Cloning formation, immunofluorescence, and EDU assay were used to assess the functions of miR-27b-3p on radioresistance of breast cancer cells. The luciferase reporter assay was used to verify whether miR-27b-3p directly targeted PLK2 mRNA. A rescue experiment was performed to identify the influence of PLK2 overexpression on miR-27b-3p regulated radioresistance.Results:The expression level of miR-27b-3p in both breast cancer tissues ( t=2.99, P<0.01) and breast cancer cells ( t=21.21, 32.88, P<0.05) was significantly higher than those in normal breast tissues and cells, especially, it was elevated in radioresistant MCF-7R cells ( t=25.63, P<0.05). Overexpression of miR-27b-3p enhanced the cloning efficiency of MCF-7 cells ( t=10.32, P<0.05), and had a protective effect on the proliferation of irradiated MCF-7 cells ( t=8.77, 8.26, 8.03, P<0.05). But interference of miR-27b-3p reduced the cloning efficiency and proliferation of MCF-7R cells ( t=40.00, P<0.05) after irradiation with different doses( t=8.54, 8.32, 8.23, P<0.05). Moreover, PLK2 was verified to be a direct target of miR-27b-3p, and overexpression of PLK2 inhibited miR-27b-3p-mediated radioresistance of breast cancer cells (MCF-7: t=9.66, P<0.05; MCF-7R: t=6.42, P<0.05). Conclusions:miR-27b-3p contributes to the radioresistance of breast cancer cells by targeting PLK2.

Emerging roles of Aurora-A kinase in cancer therapy resistance

Aurora kinase A (Aurora-A), a serine/threonine kinase, plays a pivotal role in various cellular processes, including mitotic entry, centrosome maturation and spindle formation. Overexpression or gene-amplification/mutation of Aurora-A kinase occurs in different types of cancer, including lung cancer, colorectal cancer, and breast cancer. Alteration of Aurora-A impacts multiple cancer hallmarks, especially, immortalization, energy metabolism, immune escape and cell death resistance which are involved in cancer progression and resistance. This review highlights the most recent advances in the oncogenic roles and related multiple cancer hallmarks of Aurora-A kinase-driving cancer therapy resistance, including chemoresistance (taxanes, cisplatin, cyclophosphamide), targeted therapy resistance (osimertinib, imatinib, sorafenib, etc.), endocrine therapy resistance (tamoxifen, fulvestrant) and radioresistance. Specifically, the mechanisms of Aurora-A kinase promote acquired resistance through modulating DNA damage repair, feedback activation bypass pathways, resistance to apoptosis, necroptosis and autophagy, metastasis, and stemness. Noticeably, our review also summarizes the promising synthetic lethality strategy for Aurora-A inhibitors in RB1, ARID1A and MYC gene mutation tumors, and potential synergistic strategy for mTOR, PAK1, MDM2, MEK inhibitors or PD-L1 antibodies combined with targeting Aurora-A kinase. In addition, we discuss the design and development of the novel class of Aurora-A inhibitors in precision medicine for cancer treatment.

Establishment of Human Lung Adenocarcinoma Radioresistant Cell Lines and the Mechanism of Radioresistance / 中国肺癌杂志

BACKGROUND@#Radiotherapy is one of the most common treatments for lung cancer, and about 40%-50% of patients after radiotherapy will appear uncontrolled or recurrence in the case of local tumors. Radioresistance is the predominant cause of local therapeutic failure. Nevertheless, the lack of in vitro radioresistance models is an influential factor obstructing the study of its mechanism. Therefore, the establishment of radioresistant cell lines, H1975DR and H1299DR, was beneficial to explore the mechanism of radioresistance in lung adenocarcinoma.@*METHODS@#The radioresistant cell lines of H1975DR and H1299DR were obtained from H1975 and H1299 cells irradiated with equal doses of X-rays; Clonogenic assays were performed to compare the clone-forming ability of H1975 vs H1975DR cells, H1299 vs H1299DR cells, then fitting cell survival curve by linear quadratic model; The comet assay was employed to examine DNA damage repair and calculate the percentage of DNA tails; The optical microscopy, CCK-8, flow cytometry, Transwell invasion assays were used to compare biological characteristics such as cell morphology, cell proliferation, apoptosis level, cycle distribution, cell migration and invasion; Western blot was carried out to measure the protein expression of DNA damage repair factors, such as DNA-PKcs, 53BP1, RAD51, and p-ATM.@*RESULTS@#After five months of continuous irradiation and stable culture, radioresistant cell lines H1975DR and H1299DR were obtained. The cell proliferation activity, clone formation ability and DNA damage repair ability of the two radioresistant cell lines were significantly improved under X-ray irradiation. The proportion of the G2/M phase was markedly decreased and the proportion of the G0/G1 phase was increased. Cell migration and invasion ability were significantly enhanced. Relative expression levels of p-DNA-PKcs (Ser2056), 53BP1 in the nonhomologous end-joining (NHEJ) repair pathway and p-ATM (Ser1981), RAD51 in the homologous recombination (HR) repair pathway were higher than those in H1975 and H1299.@*CONCLUSIONS@#H1975 and H1299 cell lines can be able to differentiate into lung adenocarcinoma radioresistant cell lines H1975DR and H1299DR by equal dose fractional irradiation, which provided an in vitro cytological model for the study of radiotherapy resistance mechanism of lung cancer patients.

Preliminary research on breast cancer organoids as a radiobiological model / 中华放射肿瘤学杂志

Objective:To construct breast cancer organoid culture system and conduct histological characterization and preliminary radiobiological characteristics study.Methods:Different molecular types of breast cancer cell lines and patient-derived tumor cells were cultured in vitro to form breast cancer organoids and characterize their tissue structure. In addition, Ki-67, ER, PR and Her2 markers were evaluated by immunohistochemical staining. Breast cancer organoids were irradiated with 4 Gy and 8 Gy. The numbe and diameter changes of breast cancer organoids at 0, 24, 48 and 96 h after irradiation were observed to evaluate the irradiation-induced damage to the organoids. Results:Breast cancer cell lines and patient-derived tissues formed organoid structures at 6 d. HE staining showed the microstructures, and the expression profile of markers was spatially heterogeneous. The expression patterns of markers were similar between patient-derived organoids and original tumor tissues. Irradiation of MCF-7 breast cancer organoids led to growth arrested, and some of the formed organoids collapsed and the proliferating trend gradually recovered from 48 h to 96 h. MDA-MB-231 breast tumor organoids showed radioresistance, growth arrested, but the structures remained intact, the recovery trend was still not observed at 96 h. The tissue-derived organoids from triple-negative patients also showed radiation tolerance. After irradiation, the organoids continued to grow without significant structural changes, whereas the growth trend was significantly smaller than that in the non-irradiated group.Conclusions:Breast cancer organoids formed by in vitro culture of breast cancer cells from different sources and different molecular types have microstructure and heterogeneity, which can reflect the expression of source tissue markers and show different radioresistance. Organoids derived from triple-negative breast cancer are more resistant to irradiation.

The role of lncRNA H19 in prognostic evaluation and regulating the radioresistance in colon cancer / 中华放射肿瘤学杂志

Objective:To investigate the role of lncRNA H19 in evaluating prognosis and regulating radioresistance of colon cancer, aiming to provide a new potential target for the diagnosis and treatment of colon cancer.Methods:The value of lncRNA H19 in the clinicopathological parameters and prognosis of colon cancer was assessed based on bioinformatics technology. The expression of lncRNA H19 in HCT116 and SW620 cells was regulated through siRNA and overexpression plasmid transfection, respectively. The effect of regulating lncRNA H19 expression on the proliferation, DNA synthesis, radiosensitivity and cell cycle of colon cancer cells after X-ray irradiation were detected by CCK8, EdU, cell clonogenic survival assay and flow cytometry.Results:The expression of lncRNA H19 was significantly upregulated in colon cancer tissues and correlated with poor prognosis in colon cancer patients. LncRNA H19, as a high-risk gene for colon cancer, had a significant advantage for prognostic assessment of colon cancer (AUC=0.816). Furthermore, the expression of lncRNA H19 was upregulated after X-ray irradiation in colon cancer cells. Knockdown of lncRNA H19 (siRNA-H19) significantly increased the radiosensitivity in HCT116 cells, while overexpression of lncRNA H19 (H19-OE) enhanced the radioresistance in SW620 cells. Moreover, flow cytometry revealed that the G 2/M phase arrest induced by X-ray irradiation was obviously aggravated after siRNA-H19 treatment in colon cancer cells, which suggested that lncRNA H19 might regulate the radiosensitivity by inhibiting cell cycle progression. Conclusion:LncRNA H19 plays a key role in the prognostic assessment and regulating the radiosensitivity in colon cancer, which can be used as a potential target for improving radiosensitivity of colon cancer radiotherapy.

Expression of ITGAV in Non-small Cell Lung Cancer and Its Relationship with Radioresistance / 肿瘤防治研究

Objective To investigate the relationship between the expression of ITGAV and the radiosensitivity of NSCLC cells. Methods The expression of ITGAV in NSCLC and its relationship to the prognosis of patients who received radiotherapy were analyzed using bioinformatics methods. Differences in radiosensitivity between radio-resistant cells and parent cells were verified by clone formation experiment, and the protein expression of ITGAV was detected by Western blot. The transfection efficiency of si-ITGAV was determined by Western blot and qRT-PCR analyses. The best ITGAV interference sequence was selected to transfect A549R and H1299R cells. Clone formation experiment and flow cytometry were used to detect clone formation, apoptosis and cell cycle of A549R and H1299R cells. Results The expression of ITGAV in NSCLC tissues was significantly higher than that in normal tissues (P<0.05), and NSCLC patients with high ITGAV expression had poor prognosis. The clonogenic ability of the si-ITGAV group was significantly lower than that of the negative control group at 4, 6, 8Gy irradiation (all P<0.05). After 6 Gy irradiation, the apoptosis of the si-ITGAV group was increased (PH1299R<0.0001, PA549R=0.0002), the proportion of G2/M phase cells to A549-siITGAV and H1299R-siITGAV cells was higher than that in the negative control group (PH1299R<0.0001, PA549R=0.0007). Conclusion Interfering with ITGAV expression can increase the radiosensitivity of NSCLC.

miR-183 promotes radioresistance of lung adenocarcinoma H1299 cells via epithelial-mesenchymal transition

Lung adenocarcinomas are usually sensitive to radiation therapy, but some develop resistance. Radiation resistance can lead to poor patient prognosis. Studies have shown that lung adenocarcinoma cells (H1299 cells) can develop radioresistance through epithelial-mesenchymal transition (EMT), and this process is regulated by miRNAs. However, it is unclear which miRNAs are involved in the process of EMT. In our present study, we found that miR-183 expression was increased in a radioresistant lung adenocarcinoma cell line (H1299R cells). We then explored the regulatory mechanism of miR-183 and found that it may be involved in the regulation of zinc finger E-box-binding homeobox 1 (ZEB1) expression and mediate EMT in lung adenocarcinoma cells. qPCR results showed that miR-183, ZEB1, and vimentin were highly expressed in H1299R cells, whereas no difference was observed in E-cadherin expression. Western blot results showed that ZEB1 and vimentin were highly expressed in H1299R cells, while E-cadherin expression was decreased. When miR-183 expression was inhibited in H1299R cells, radiation resistance, proliferation, and cell migration were decreased. The expression of ZEB1 and vimentin in H1299R cells was decreased, while the expression of E-cadherin was increased. Moreover, miR-183 overexpression in H1299 cells enhanced radiation resistance, proliferative capacity, and cell migration ability. The expression of ZEB1 and vimentin in H1299 cells was increased, while that of E-cadherin was decreased. In conclusion, miR-183 may promote EMT and radioresistance in H1299 cells, and targeting the miR-183-ZEB1 signaling pathway may be a promising approach for lung cancer treatment.

Correlation between classic Wnt signaling pathway and radioresistance of esophageal cancer cells / 中华放射肿瘤学杂志

Objective:To clarify the role of classic Wnt signaling pathway in the radioresistance of esophageal cancer cells (ECC), and investigate the underlying mechanism, aiming to identify critical molecular targets for clinically enhancing the radiosensitivity of esophageal cancer.Methods:The radiosensitivity of four types of ECCs (EC9706, ECA109, KYSE70 and KYSE150) were assessed by colony formation assay. Western blot and RT-PCR were used to detect the activation of classical Wnt signaling pathway after irradiation. Classic Wnt signaling pathway activator (AZD2858) and inhibitor (XAV-939) were utilized to comprehensively evaluate the effect of classic Wnt signaling pathway on the radiosensitivity of ECCs. Cellular immunofluorescence staining was performed to detect the production and repair of DNA double-strand breaks (DSB), as well as the foci formation of DSB repair proteins after irradiation.Results:The results of colony formation assay showed that the radiosensitivity of four types of ECCs from high to low was EC9706, ECA109, KYSE70 and KYSE150. In KYSE150, a radioresistant cell type, the level of nuclear β-catenin and the transcription of c-Myc gene were significantly increased after irradiation (both P<0.05). However, in EC9706, a radiosensitive cell type, the level of nuclear β-catenin and c-Myc gene transcription were not affected by irradiation (both P>0.05). Moreover, EC9706 cells showed enhanced radioresistance in the presence of AZD2858( P<0.05), whereas XAV-939 treatment decreased the radioresistance in KYSE150 cells ( P<0.05). AZD2858 accelerated the DSB repair in EC9706 cells ( P<0.05), whereas XAV-939 delayed the DSB repair in KYSE150 cells ( P<0.05). Furthermore, the results of immunofluorescence staining showed that XAV-939 reduced the DSB repair capacity by inhibiting homologous recombination repair-related proteins (BRCA1 and RAD51) rather than non-homologous end junction repair-related proteins (Ku80 and XRCC4). Conclusions:The classic Wnt signaling pathway participates in the regulation of radiosensitivity in ECCs by regulating the homologous recombination repair of DSB after irradiation. Inhibition of the classic Wnt signaling pathway can counteract the radioresistance of ECCs and enhance the killing effect of irradiation on ECCs.

Promotion of OIP5-AS1 expression by H3K27ac-induced radioresistance in esophageal squamous carcinoma / 西安交通大学学报(医学版)

Objective: Our study aims to investigate the radiation associated H3 modification in regulating OIP5-AS1 to lay foundation for developing therapeutic targets on reversing radiation resistance of esophageal squamous carcinoma. Methods: We recruited 137 ESCC patients from The First Affiliated Hospital of Xi'an Medical College. qRT-PCR and Western blotting were used for detecting the expressions of target genes. Wound healing assay and CCK8 assay were used to detect the migration and proliferation abilities. ChIP assay was used to detect the interaction between OIP5-AS1 and H3K27ac. Results: OIP5-AS1 was highly expressed in ESCC radiation resistant patients and promoted the migration and proliferation abilities of ESCC radiation resistant cells. H3K27ac was activated in ESCC radiation resistant cells and was enriched in the promoter region of OIP5-AS1. CBP was upregulated in ESCC radiation resistant cells; its inhibitor, C646, could suppress the enrichment of H3K27ac in the promoter region of OIP5-AS1. Results: OIP5-AS1 regulated radioresistance in ESCC. CBP promoted the interaction between H3K27ac and OIP5-AS1, thereby activating the expression of OIP5-AS1 and resulting in radioresistance.

Targeting the canonical Wnt/β-catenin pathway in cancer radioresistance: Updates on the molecular mechanisms

Radiation resistance is an important factor that affects the efficacy of radiotherapy; it could even lead to its failure. In recent years, the relationship between the classical Wnt signaling pathway and radiation resistance has gradually attracted attention from scholars. Although most of the findings are comprehensive, they are fragmented and disorganized. This review explores the relationship between classical Wnt signaling pathways and cancer radiation resistance. Previous literature regarding the classical Wnt signaling pathways and cancer radiation resistance from the past decades had been summarized in this article. Moreover, the molecular mechanisms and functions of the canonical Wnt signaling pathway involved in the formation of radioresistance were systemically analyzed and sorted out. Certain rules and internal relationships among different pathways have been further clarified; this is expected to provide valuable clues for further research. The Wnt/β-catenin pathway is closely associated with the formation of cancer radioresistance, which may be a target for improving the effects of radiotherapy

Research progress on radioresistance and sensitization of tumor cells in three-dimensional culture system / 中华放射肿瘤学杂志

Three-dimensional cell culture is a novel type of in vitro culture method.This system can mimic the microenvironment of cell growth in vivo,where cells exhibit similar state and function to that in the in vivo environment.Currently,three-dimensional culture system has been widely applied in tissue engineering and tumor cell biology fields,etc.Radiotherapy is an important treatment of cancer.Radioresistance of tumor cells is the main cause of treatment failure,tumor recurrence and metastasis.Tumor cells can exhibit the resistant characteristics in the three-dimensional culture system,similar to those of tumor cells in vivo.Therefore,three-dimensional culture system can be adopted to investigate the radioresistance and underlying mechanism of tumor cells and identify the key factors regulating the radioresistance of tumor cells,which plays a pivotal role in enhancing the radioresistance and improving the effect of radiotherapy.This article will review recent research progress in the radioresistance and sensitization of tumor cells under three-dimensional culture system,aiming to provide reference for relevant investigations.

Differential expression profiles of mRNA in radioresistant non-small cell lung cancer cell line A549 model using gene expression microarray / 解剖学报

Objective To investigate the radioresistance factors in non-small cell lung cancer (NSCLC)cell line A549, and provide new targets for radiotherapy sensitization drugs development. Methods Establish the stable model of radioresistant NSCLC cell line A549 under irradiation; investigate the whole-transcriptome alteration of radioresistance cell line and radiosensitive cell line using gene expression microarray; perform bioinformatic approaches gene ontology (GO) analysis and Pathway analysis. Results The expression profile microarray showed that 1410 differentially expressed genes (733 up-regulated and 677 down-regulated) were detected in resistant and sensitive strains; GO analysis showed that it was mainly related to cell cycle and DNA replication; Pathway significant enrichment analysis showed that mitogen-activated protein kiase(MAPK) signaling pathway, phosphatidylinositol 3-kinase/protein kinase B(PI3K/Akt) signaling pathway, were mainly associated with radioresistance. Conclusion Multiple genes and signaling pathways are involved in radioresistance, further studies are needed to investigate the radioresistance factors, which could provide new targets for radiotherapy sensitization drugs development.

CCR6 Is a Predicting Biomarker of Radiosensitivity and Potential Target of Radiosensitization in Rectal Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: This study aimed to explore the functions and mechanisms of C-C motif chemokine receptor 6 (CCR6), a gene associated with progression and metastasis of colorectal cancer (CRC), in radiosensitivity of rectal cancer (RC). MATERIALS AND METHODS: RNA sequencing and immunohistochemical analysis on CCR6 expression were performed in pretreatment tissues of RC patients exhibiting different therapeutic effects of radiotherapy. Colonogenic survival assay was conducted in different CRC cell lines to assess their radiosensitivity. And the impact of CCR6 expression on radiosensitivity was validated through RNA interference. The DNA damage repair (DDR) abilities of cell lines with different CCR6 expression were evaluated through immunofluorescence-based γH2AX quantification. RESULTS: The CCR6 mRNA level was higher in patients without pathologic complete remission (pCR) than in those with pCR (fold changed, 2.11; p=0.004). High-level expression of CCR6 protein was more common in the bad responders than in the good responders (76.3% vs. 37.5%, p < 0.001). The CRC cell lines with higher CCR6 expression (LoVo and sw480) appeared to be more radioresistant, compared with the sw620 cell line which had lower CCR6 expression. CCR6 knockdown made the LoVo cells more sensitive to ionizing radiation (sensitization enhancement ratio, 1.738; p < 0.001), and decreased their DDR efficiency. CONCLUSION: CCR6 might affect the RC radiosensitivity through DDR process. These findings supported CCR6 as a predicting biomarker of radiosensitivity and a potential target of radiosensitization for RC patients.

Research progress in microRNAs associated with radioresistance of nasopharyngeal carcinoma / 中华放射肿瘤学杂志

Nasopharyngeal carcinoma ( NPC) is a squamous cell carcinoma originating from the nasopharyngeal epithelial tissues with a high incidence in Southeast Asia and South China. At present, radiotherapy has become the primary therapeutic modality to treat NPC. Resistance to radiotherapy poses a serious obstacle to successful therapy for NPC. It is of great importance to identify the biomarkers related to the NPC radioresistance and unravel the mechanism of radioresistance for the diagnosis and treatment of NPC patients. MicroRNAs induce translational repression or degradation of targeted mRNAs by binding to their 3’ UTRs and regulate the expression of protein. MicroRNAs are involved in the regulation of all important cellular processes associated with response to the radiotherapy, such as DNA damage response and repair, cellular apoptosis, proliferation and angiogenesis. In recent years, the study of miRNAs associated with radioresistance of NPC has captivated widespread attention from researchers. In this review, relevant microRNAs and their potential mechanisms were summarized.

The characteristics of CD44 +/CD24 + cervical cancer cells and radioresistant cervical cancer cells / 中华放射医学与防护杂志

Objective To investigate the characteristics of radiation resistance of cervical cancer cells,and to explore the mechanism of tumor recurrence and migration.Methods Cervical cancer cells (Siha) were fractionally irradiated to get radioresistant subpopulation.CD44 +/CD24 + Siha cells were sorted with a flow cytometry.Colony-formation tests and tumor xenografts tests were used to evaluate the " stemness" of resistant cells.Stem cell markers were studied using fluorescence-activated cell sorting analyses.Migration and invasiveness were assessed by a Transwell test.Gene and protein expressions were determined by RT-PCR and immunoblotting assay,respectively.Results Radiation-resistant Siha cells and CD44 +/CD24 + Siha cells expressed more antiapoptotic protein Bcl-2(t =205.26,198.17,P ＜0.05),apoptosis-inhibitory protein Survivin (t =896.62,765.34,P ＜ 0.05) and stem cell markers of OCT-4 and ABCG2 (t =92.13,81.26,220.45,216.32,P ＜0.05).They were more tumorigenic in vitro and in vivo,showed phenotypic and molecular changes of EMT,and had higher abilities of invasion and migration.Conclusions The radioresistant cervical cancer cells and CD44 +/CD24 + cervical cancer cells are similar to CSCs and undergo EMT,suggesting that radiation resistance-induced EMT is linked to the generation of CSCs.

Research progress of microRNAs in precise radiotherapy for prostate cancer / 国际生物医学工程杂志

Radiotherapy is a very important treatment for early or advanced stage of prostate cancer (CaP).Radioresistance is the most important challenge for current radiotherapy.It is of great importance to study the mechanisms of radioresistance and to develop new treatment strategies that can overcome radioresistance.In CaP patients,microRNAs (miRNAs) are usually abnormally expressed,and radiotherapy can significantly alter the expression levels of miRNAs.There are increasing evidences that miRNAs are closely related to tumor radioresistance.The mechanism of action of miRNAs in regulating radioresistance is very complex.The possible mechanisms include DNA damage response,cell cycle checkpoint activation,apoptosis,autophagy,tumor stem cells,hypoxia,etc.The previous studies showed that miRNAs hold potential as prognostic biomarkers and therapeutic targets for CaP radiotherapy.New technologies targeting miRNAs combined with radiotherapy are expected to overcome CaP radioresistance,which will help to achieve precise radiotherapy,and bring hope to patients.

Research of radiation resistance delivery through paracrine effects on non-small cell lung cancer / 国际生物医学工程杂志

Objective To investigate the role and possible mechanisms of paracrine in radiation tolerance of non-small cell lung cancer (NSCLC) by observing the effects of radiation-resistant NSCLC H460R cell secretion on the radiosensitivity of parental H460 cells. Methods H460 cells were inoculated and cultured, and then divided into control group, conditional culturing group, irradiation group and irradiation combined conditional culturing group. One-time irradiation with 137Cs γ-rays was conducted with a dose rate of 1.02 Gy/min. Effect of H460R conditioned media on the radiation sensitivity of H460 cells was observed by clonogenic assay. The percentage of phospho-histone histone H2AX (γH2AX) positive cells was detected by immunofluorescence staining. The cyclical changes of the cells were detected by flow cytometry. The expression of DNA damage-associated proteinsγH2AX and Rad51 were detected by Western Blot. Results The results showed that compared with the singleγ-rays irradiation, the number of cell clones was significantly increased in the H460R cells after γ-rays irradiation combined with conditional culturing treatment at different doses of 2, 4, and 6 Gy, and the differences were statistically significant (2,4 Gy:all P<0.05;6 Gy:P<0.01). The results of immunofluorescence staining showed that the percentage ofγH2AX positive cells in the conditional culturing group was higher than that in the control group [(39.40±2.51)％vs. (25.21± 2.05)％], and the difference was statistically significant (P<0.01). This value in the irradiation combined conditional culturing group was lower than that in irradiated group [(60.48±2.79)％vs. (80.65±2.05)％], and the difference was statistically significant (P<0.001). The flow cytometry analysis showed that the percentage of cells in G2/M phase for the irradiation (4 Gy) combined conditional culturing group was higher than that of irradiated group [(26.83± 1.42)％ vs. (15.73±1.29)％], and the difference was statistically significant (P<0.001). The Western Blot results showed that γH2AX and Rad51 protein expression in the irradiation (4 Gy) combined conditional culturing group respectively was lower and higher than that in irradiated group. Conclusion In the tumor microenvironment, radiation-resistant H460R cells can enhance the radioresistance of H460 cells by paracrine, which may be related to the promotion of DNA repair ability after irradiation

Effect of up-regulation of Shh-Gli1 signaling pathway on radioresistance and cell cycle in human esophageal cancer cell line Eca109 / 中国病理生理杂志

AIM:To investigate the relationship between Sonic Hedgehog(Shh)signaling pathway and cell cycle and radioresistance of esophageal cancer by up-regulating Gli1,a key factor in Shh signaling pathway.METHODS:The human esophageal cancer cell line Eca 109 was transfected with plasmid to induce Gli 1 over-expression,which served as Eca109-ox-Gli1 group.In addition, Eca109 cells transfected with empty plasmid served as negative control group and the untreated Eca109 cells were used as normal control group.The expression of Gli1 was confirmed by real-time PCR and Western blot.The radiosensitivity of the cells in the 3 groups was determined by colony formation assay.The effect of irra-diation on the cell cycle was analyzed by flow cytometry.RESULTS:The expression of Gli1 in Eca109-ox-Gli1 group was higher than that in the other 2 groups(P<0.05).The survival fraction at dose of 2 Gy in Eca109-ox-Gli1 group was high-er than that in normal control group, indicating that the radioresistance of the Eca 109 cells transfected with Gli1 plasmid was increased.The cells in Eca109-ox-Gli1 group showed higher S phase proportion than that in normal control group and negative control group(P<0.01).After irradiation at dose of 6 Gy,all cells in the 3 groups found that the cell cycle was arrested at G2/M phase,while the cells in normal control group showed higher G 2/M phase proportion than that in Eca109-ox-Gli1 group(P<0.01).CONCLUSION: The up-regulation of Gli1 may enhance the radioresistance of esophageal cancer by regulating the cell cycle.

Advance of establishing radioresistant tumor cell lines / 中华放射医学与防护杂志

Radiotherapy is necessary for 70％ of malignant tumor patients. Local recurrence and metastasis are primary failure models, where radioresistance is one of important factors. It is critical to establish radioresistant tumor cell lines for understanding the mechanism of radioresistance. According to single radiation, fractioned radiation and the compound radiation method, four representative radiation models are classified: conventional radiation, repeated radiation, gradient radiation and other radiation. These different radiation models have difference in total dose and radiation model as well as the biological characteristics. Superior to other three models, the gradient fractioned irradiation model increase fractioned doses gradually along with the enhancement of radioresistance, which favorably balances the fractioned doses and the time of irradiated cells approaching to exponential growth phase. Clinically relevant radioresistant cell line ( CRR) with a genotype in consistent with its parental cells is an important research direction on tumor radioresistance.