Fanconi Anemia: Exploration of DNA Repair Pathways from Genetic Diseases to Cancer and Prospects for Treatment / 肿瘤防治研究

Fanconi anemia (FA) is an inheritable disorder that presents with bone marrow failure, developmental anomalies, and an increased susceptibility to cancer. The etiology of this condition stems from a genetic mutation that disrupts the proper repair of interstrand DNA cross-links (ICLs). The resultant dysregulation of the DNA damage response mechanism can induce genomic instability, thereby elevating the mutation rates and the likelihood of developing cancer. The FA pathway assumes a pivotal role in safeguarding genome stability through its involvement in the repair of DNA cross-links and the maintenance of overall genomic integrity. A mutation in the germ line of any of the genes responsible for encoding the FA protein results in the development of FA. The prevalence of aberrant FA gene expression in somatic cancer, coupled with the identification of a connection between FA pathway activation and resistance to chemotherapy, has solidified the correlation between the FA pathway and cancer. Consequently, targeted therapies that exploit FA pathway gene abnormalities are being progressively developed and implemented. This review critically examines the involvement of the FA protein in the repair of ICLs, the regulation of the FA signaling network, and its implications in cancer pathogenesis and prognosis. Additionally, it explores the potential utility of small-molecule inhibitors that target the FA pathway.

Genetic analysis of novel pathogenic gene HROB in a family with primary ovarian insufficiency / 浙江大学学报·医学版

A 13-year and 6-month-old girl attended the Hunan Children's Hospital due to delayed menarche. The laboratory test results indicated increased follicle-stimulating hormone and luteinizing hormone, decreased anti-Mullerian hormone, and pelvic ultrasound showed a cord-like uterus and absence of bilateral ovaries. Her 11-year and 5-month-old younger sister had the same laboratory and imaging findings, and both girls were diagnosed with primary ovarian insufficiency. Whole exome sequencing and Sanger sequencing confirmed that the proband and her sister carried heterozygous variants of HROB gene c.718C>T (p.Arg240*) and c.1351C>T (p.Arg451*), which were inherited from their parents respectively and consistent with autosomal recessive inheritance. Oral estradiol valerate at an initial dose of 0.125 mg/d was given to the proband, and the secondary sexual characteristics began to develop after 6 months.

Deubiquitinating enzyme JOSD2 affects susceptibility of non-small cell lung carcinoma cells to anti-cancer drugs through DNA damage repair / 浙江大学学报·医学版

OBJECTIVES@#To investigate the effects and mechanisms of deubiquitinating enzyme Josephin domain containing 2 (JOSD2) on susceptibility of non-small cell lung carcinoma (NSCLC) cells to anti-cancer drugs.@*METHODS@#The transcriptome expression and clinical data of NSCLC were downloaded from the Gene Expression Omnibus. Principal component analysis and limma analysis were used to investigate the deubiquitinating enzymes up-regulated in NSCLC tissues. Kaplan-Meier analysis was used to investigate the relationship between the expression of deubiquitinating enzymes and overall survival of NSCLC patients. Gene ontology enrichment and gene set enrichment analysis (GSEA) were used to analyze the activation of signaling pathways in NSCLC patients with high expression of JOSD2. Gene set variation analysis and Pearson correlation were used to investigate the correlation between JOSD2 expression levels and DNA damage response (DDR) pathway. Western blotting was performed to examine the expression levels of JOSD2 and proteins associated with the DDR pathway. Immunofluorescence was used to detect the localization of JOSD2. Sulforhodamine B staining was used to examine the sensitivity of JOSD2-knock-down NSCLC cells to DNA damaging drugs.@*RESULTS@#Compared with adjacent tissues, the expression level of JOSD2 was significantly up-regulated in NSCLC tissues (P<0.05), and was significantly correlated with the prognosis in NSCLC patients (P<0.05). Compared with the tissues with low expression of JOSD2, the DDR-related pathways were significantly upregulated in NSCLC tissues with high expression of JOSD2 (all P<0.05). In addition, the expression of JOSD2 was positively correlated with the activation of DDR-related pathways (all P<0.01). Compared with the control group, overexpression of JOSD2 significantly promoted the DDR in NSCLC cells. In addition, DNA damaging agents significantly increase the nuclear localization of JOSD2, whereas depletion of JOSD2 significantly enhanced the sensitivity of NSCLC cells to DNA damaging agents (all P<0.05).@*CONCLUSIONS@#Deubiquitinating enzyme JOSD2 may regulate the malignant progression of NSCLC by promoting DNA damage repair pathway, and depletion of JOSD2 significantly enhances the sensitivity of NSCLC cells to DNA damaging agents.

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.

FARSB stratifies prognosis and cold tumor microenvironment across different cancer types: an integrated single cell and bulk RNA sequencing analysis / 南方医科大学学报

OBJECTIVE@#Immunotherapy has brought significant clinical benefits to a subset of patients, but has thus far been disappointing in the treatment of immunologically "cold" tumors. Existing biomarkers that can precisely identify these populations are insufficient. In this context, a potential cold tumor microenvironment (TME) marker FARSB was investigated to reveal its impact on TME and patients' response to immunotherapy across pan-cancer.@*METHODS@#The expression levels and mutational landscape of FARSB in pan-cancer were investigated. Kaplan-Meier and univariate Cox regression analyses were applied to analyze the prognostic significance of FARSB. Pathways affected by FARSB were investigated by gene set enrichment and variation analysis. The relationship between FARSB expression and immune infiltration was examined using the TIMER2 and R packages. Single-cell RNA sequencing (scRNA-seq) data of several cancer types from GSE72056, GSE131907, GSE132465, GSE125449 and PMID32561858 were analyzed to validate the impact of FARSB on the TME. The predictive effect of FARSB on immunotherapy efficacy was explored in 3 immune checkpoint inhibitors (ICIs)- treated cohorts (PMID32472114, GSE176307, and Riaz2017).@*RESULTS@#FARSB expression was significantly higher in 25 tumor tissues than in normal tissues and was associated with poor prognosis in almost all tumor types. FARSB expression exhibited a strong association with several DNA damage repair pathways and was significantly associated with TP53 mutation in lung adenocarcinoma (P < 0.0001, OR=2.25). FARSB characterized a typical immune desert TME and correlated with impaired expression of chemokines and chemokines receptors. Large-scale scRNA-seq analysis confirmed the immunosuppressive role of FARSB and revealed that FARSB potentially shapes the cold TME by impeding intercellular interactions. In 3 ICI-treated cohorts, FARSB demonstrated predictive value for immunotherapy.@*CONCLUSION@#This study provides a pan-cancer landscape of the FARSB gene by integrated single-cell and bulk DNA sequencing analysis and elucidates its biological function to promote DNA damage repair and construct the immune desert TME, suggesting the potential value of FARSB as a novel marker for stratifying patients with poor immunotherapeutic benefits and "cold" TME.

Effects of niraparib on the radiosensitivity of human esophageal cancer cells and its mechanism / 中华放射肿瘤学杂志

Objective:To evaluate the effect of niraparib, the poly (ADP-ribose) polymerase (PARP) inhibitor, on the radiosensitivity of esophageal squamous cell carcinoma (ESCC) and to preliminarily investigate its mechanism.Methods:Human esophageal squamous cell carcinoma cells ECA-109 and KYSE-150 were divided into the control, niraparib, single irradiation, combined (niraparib+irradiation) groups. Cell proliferation was measured by CCK-8 assay. The changes of cell survival rate were detected by colony formation assay. The changes of cell cycle and apoptosis were analyzed by flow cytometry. The number of γH2AX foci was detected by immunofluorescence, and the expression levels of PARP-1, cleaved-PARP, RAD51, mitogen-activated protein kinase (MAPK) [extracellular signal-regulated kinase 1 and 2 (ERK1/2) ] and p-MAPK (ERK1/2) proteins were determined by Western blot. All data were expressed as Mean±SD. Data between two groups conforming to normal distribution through the normality test were subject to independent sample t-test and multiple groups were analyzed using one-way ANOVA. Results:In human ESCC cells ECA-109 and KYSE-150, the proliferation of ESCC cells was significantly inhibited by niraparib combined with irradiation, and the values of average lethal dose (D 0), quasi-threshould dose(D q), survival fraction after 2 Gy irradiation (SF 2) in the combined group were decreased compared with those in the single irradiation group. The effect of irradiation alone on apoptosis of ECA-109 and KYSE-150 cells was limited. Compared to single irradiation group, irradiation combined with niraparib further increased the apoptosis rate in ESCC cells ( P=0.015, P=0.006). In ECA-109 cells, G 2/M phase arrest was significantly increased in combined group compared with irradiation alone group ( P<0.001). In ECA-109 cells, the number of γH2AX foci in combined group was higher than that in the single irradiation group after 2 h, and showed a significantly slower decay of γH2AX foci ( P<0.001). Moreover, niraparib combined with irradiation enhanced the radiation-induced cleavage of PARP-1 and down-regulated the expression of Rad51 and p-MAPK(ERK1/2). Conclusion:Niraparib can increase the radiosensitivity of esophageal cancer cells by inhibiting cell proliferation, promoting cell apoptosis, inhibiting the repair of DNA damage and regulating the MARK-ERK signaling pathway.

Mismatch repair gene germline mutations in patients with prostate cancer / 浙江大学学报·医学版

OBJECTIVES@#To investigate the prevalence of pathogenic germline mutations of mismatch repair (MMR) genes in prostate cancer patients and its relationship with clinicopathological characteristics.@*METHODS@#Germline sequencing data of 855 prostate cancer patients admitted in Fudan University Shanghai Cancer Center from 2018 to 2022 were retrospectively analyzed. The pathogenicity of mutations was assessed according to the American College of Medical Genetics and Genomics (ACMG) standard guideline, Clinvar and Intervar databases. The clinicopathological characteristics and responses to castration treatment were compared among patients with MMR gene mutation (MMR+ group), patients with DNA damage repair (DDR) gene germline pathogenic mutation without MMR gene (DDR+MMR－ group) and patients without DDR gene germline pathogenic mutation (DDR－ group).@*RESULTS@#Thirteen (1.52%) MMR+ patients were identified in 855 prostate cancer patients, including 1 case with MLH1 gene mutation, 6 cases with MSH2 gene mutation, 4 cases with MSH6 gene mutation and 2 cases with PMS2 gene mutation. 105 (11.9%) patients were identified as DDR gene positive (except MMR gene), and 737 (86.2%) patients were DDR gene negative. Compared with DDR－ group, MMR+ group had lower age of onset (P<0.05) and initial prostate-specific antigen (PSA) (P<0.01), while no significant differences were found between the two groups in Gleason score and TMN staging (both P>0.05). The median time to castration resistance was 8 months (95%CI: 6 months-not achieved), 16 months (95%CI: 12-32 months) and 24 months (95%CI: 21-27 months) for MMR+ group, DDR+MMR－ group and DDR－ group, respectively. The time to castration resistance in MMR+ group was significantly shorter than that in DDR+MMR－ group and DDR－ group (both P<0.01), while there was no significant difference between DDR+MMR－ group and DDR－ group (P>0.05).@*CONCLUSIONS@#MMR gene mutation testing is recommended for prostate cancer patients with early onset, low initial PSA, metastasis or early resistance to castration therapy.

Nuclear cGAS: sequestration and beyond

The cyclic GMP-AMP (cGAMP) synthase (cGAS) has been identified as a cytosolic double stranded DNA sensor that plays a pivotal role in the type I interferon and inflammation responses via the STING-dependent signaling pathway. In the past several years, a growing body of evidence has revealed that cGAS is also localized in the nucleus where it is associated with distinct nuclear substructures such as nucleosomes, DNA replication forks, the double-stranded breaks, and centromeres, suggesting that cGAS may have other functions in addition to its role in DNA sensing. However, while the innate immune function of cGAS is well established, the non-canonical nuclear function of cGAS remains poorly understood. Here, we review our current understanding of the complex nature of nuclear cGAS and point to open questions on the novel roles and the mechanisms of action of this protein as a key regulator of cell nuclear function, beyond its well-established role in dsDNA sensing and innate immune response.

The prospects of DNA damage repair variants guiding platinum compounds in the treatment of triple negative breast cancer / 中华肿瘤杂志

Triple negative breast cancer (TNBC) is prone to recurrence and metastasis, which is the subtype of poorest prognosis. Chemotherapy is the main treatment, although there is lack of effective adjuvant chemotherapy regimens. The unsatisfactory efficacy of chemotherapy has been a bottleneck in improving the outcome of TNBC. Platinum compounds act directly on DNA to kill tumor cells, and they have a stronger killing effect on tumor cells carrying DNA damage repair (DDR) defects, which is an important entry point to improve the efficacy of TNBC. Biomarkers for predicting the efficacy of platinum drugs in TNBC treatment have always been a hot topic. The DDR pathway contains a large number of related genes, and recent studies have shown that deficiencies in the DDR pathway may be associated with the efficacy of platinum drugs, which is expected to be a biomarker for predicting the efficacy of platinum drugs in breast cancer treatment.

The progress on sensitivity of PARPi and platinum in mCRPC with DNA damage repair gene mutation / 中华泌尿外科杂志

DNA damage repair (DDR) defects occurred in 8%-16% of metastatic castration resistant prostate cancer (mCRPC). DDR gene mutation was related to poorer prognosis. Patients with DDR gene mutation, especially BRCA1/2 mutation, showed high sensitivity to poly ADP-ribose polymerase inhibitor (PARPi) and platinum.

ZNF451 promotes DNA damage repair by recruiting 53BP1/MDC1 in A549 and HeLa cells / 中华放射医学与防护杂志

Objective:To investigate the role of SUMO E3 ligase ZNF451 in DNA damage repair and explore the underlying mechanism in non-small cell lung cancer A549 cells and cervical cancer HeLa cells.Methods:A549 cells and HeLa cells were irradiated with γ-ray irradiation or treated with etoposide. Cell proliferation viability was detected by the cell counting kit-8 assay. Protein expression was detected by Western blot assay. DNA damage repair level was detected by DR-GFP plasmid system, and the spatial positioning was detected by immunofluorescence.Results:Etoposide decreased the expression level of ZNF451 in a dose- and time- dependent manner. After treatment with 30, 50, 80 μmol/L etoposide, the cell viability were reduced after the knockdown of ZNF451 in A549 and HeLa cells(A549: t = 27.62, 25.61, 5.32, P<0.01; HeLa: t = 30.77, 21.28, 4.18, P<0.01). Furthermore, ZNF451 was recruited at DNA damage sites. A co-localization and endogenous interaction were found between ZNF451 and γ-H2AX after the treatment of irradiation or etoposide. Moreover, the expression level of γ-H2AX was significantly increased after treatment with 30, 50, 80 μmol/L etoposide(A549: t = 6.12, 10.67, 4.68, P<0.01; HeLa: t = 7.94, 9.81, 15.12, P<0.01)and the repair efficiency of NHEJ was reduced in ZNF451 knockdown cells( t = 18.60, P<0.05). Finally, the immunofluorescence assay showed that ZNF451 was co-localizated with 53BP1 and MDC1 after irradiation or etoposide treatment. Conclusions:Knockdown of ZNF451 inhibits cell proliferation and increases the level of DNA damage in A549 and HeLa cells. ZNF451 was recruited to DNA damage sites after DSBs and participated in NHEJ repair by co-localizing with DNA damage repair factor 53BP1/MDC1.

Expression and functional SNP loci screen of ATM from coal worker's pneumoconiosis / 中华劳动卫生职业病杂志

Objective: To detect of gene expression and genotype of the ataxia telangiectasia mutated (ATM) from coal workers' pneumoconiosis (CWP) , It is explored whether CWP is related to ATM gene. Methods: In October 2020, the relevant information of 264 subjects who received physical examination or medical treatment in the Department of occupational diseases of Guiyang public health treatment center from January 2019 to September 2020 was collected. Through the occupational health examination, 67 healthy people with no history of exposure to occupational hazards were selected as the healthy control group; The coal miners with more than 10 years of coal dust exposure history and small shadow in the lung but not up to the diagnostic criteria were the dust exposure control group, a total of 66 people; The patients with the same history of coal dust exposure and confirmed stage I were coal worker's pneumoconiosis stage I group, a total of 131 people. The expression of ATM was detected by QRT PCR. ATM rs189037 and rs1801516 were genotyped by massarray. Results: There was significant difference in the expression of ATM among the groups (P<0.05) ; Compared with the healthy control group, the expression of ATM in the dust exposed control group was significantly increased (P<0.05) . With the occurrence and development of CWP, the GG of rs189037 wild type decreased, the GA of mutant heterozygote and AA of homozygote increased, but the difference was not statistically significant (P>0.05) ; Rs1801516 wild type GG and mutant heterozygote GA had no significant changes (P>0.05) . There were significant differences in age, neutrophils and basophils among rs189037 groups (all P<0.05) . There were no significant differences in blood pressure, eosinophils, lymphocytes, monocytes, smoking and drinking history among rs189037 groups (all P>0.05) . Compared with wild-type GG, the or of mutant heterozygotes and homozygotes increased, but the differences were not statistically significant (P>0.05) . Conclusion: ATM gene may be one of the early activation genes of CWP and rs189037 may be the functional loci which affects gene expression. ATM gene is related to inflammatory response, Neutrophils and basophils have an impact on the development of CWP.

Function of PARP1 and Mechanism of Action and Drug Resistance of PARP Inhibitors / 中国生物化学与分子生物学报

Poly ADP⁃ribose polymerase 1 (PARP1) is an important modification enzyme in cells. Its most well⁃known function is to recruit multiple DNA damage repair effector proteins through its own PARylation, such as XRCC1, to participate in DNA single and double strand damage repair. In addition, PARP1 can also provide favorable conditions for DNA damage repair and maintain genomic stability by promoting replication fork stall and nucleosome depolymerization. In recent years, in addition to the function of DNA damage repair, PARP1 has also been found to play an important role in cell apoptosis, autophagy and inflammatory pathways, which is closely related to the occurrence and development of neurodegenerative diseases. PARP inhibitor (PARPi) is an antitumor drug that targets PARP1 and works together with a homologous recombination (HR) deficient phenotype to produce a synthetic lethality. The drug can trap PARP1 and inhibit its activity. On the one hand, it directly interferes with the DNA damage repair pathway that PARP1 participates in; and on the other hand, it also inhibits the selection of PARP1⁃mediated DNA damage repair pathway and replication fork stall, making the cell genome instable. However, tumor cells are often found to be insensitive to PARPi in clinical treatment. Drug resistance of tumor cells to PARPi is highly correlated with mutations of their own genes, which respectively act on cell HR repair pathway, PARP1 circulation pathway, replication fork stability and active drug efflux, etc. Identifying specific mutation sites in drug⁃resistant tumor cells will provide help for clinical treatment. The purpose of this review is to give a description about the functions of PARP1, and focus on the mechanism of action of PARPi, the mutated genes related to drug resistance and their drug resistance mechanism, therefore to deepen the understanding of PARP1 mediated DNA damage repair pathway in cells, and provide new ideas for future clinical treatment.

Therapeutic targets of desmoplastic small round cell tumor and future direction / 中国肿瘤临床

Desmoplastic small round cell tumor (DSRCT) is a rare and highly malignant soft tissue sarcoma. Most patients are diagnosed at advanced stage unless DSRCT happens to be discovered accidentally. DSRCT mainly occurs in the abdomen and pelvis, spreading along the peritoneal surface. At the time of diagnosis, most patients have passed the operable stage. The diagnosis of DSRCT is based on the histological analysis of a biopsy. It typically manifests as small round blue cells in the nest, separated by a large number of fibroproliferative stroma. A stable cytogenetic feature of DSRCT is that the characteristic t(11; 22) (P13; Q12) chromosome produces the EWSWT1 fusion gene. The prognosis of patients with DSRCT is very poor, and the 5-year survival rate is about 15%. Despite the use of active treatment methods, such as chemotherapy, surgery, and total abdominal radiotherapy, about 60% 70% of patients with DSRCT die within 2- 3 years. Targeted therapy, immunotherapy, and other methods have been trialed recently in the treatment of DSRCT due to the development of DSRCT molecular genetics.

MRN complex is an essential effector of DNA damage repair / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Genome stability can be threatened by both endogenous and exogenous agents. Organisms have evolved numerous mechanisms to repair DNA damage, including homologous recombination (HR) and non-homologous end joining (NHEJ). Among the factors associated with DNA repair, the MRE11-RAD50-NBS1 (MRN) complex (MRE11-RAD50-XRS2 in

ADP-ribosylhydrolases: from DNA damage repair to COVID-19 / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Adenosine diphosphate (ADP)-ribosylation is a unique post-translational modification that regulates many biological processes, such as DNA damage repair. During DNA repair, ADP-ribosylation needs to be reversed by ADP-ribosylhydrolases. A group of ADP-ribosylhydrolases have a catalytic domain, namely the macrodomain, which is conserved in evolution from prokaryotes to humans. Not all macrodomains remove ADP-ribosylation. One set of macrodomains loses enzymatic activity and only binds to ADP-ribose (ADPR). Here, we summarize the biological functions of these macrodomains in DNA damage repair and compare the structure of enzymatically active and inactive macrodomains. Moreover, small molecular inhibitors have been developed that target macrodomains to suppress DNA damage repair and tumor growth. Macrodomain proteins are also expressed in pathogens, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, these domains may not be directly involved in DNA damage repair in the hosts or pathogens. Instead, they play key roles in pathogen replication. Thus, by targeting macrodomains it may be possible to treat pathogen-induced diseases, such as coronavirus disease 2019 (COVID-19).

Research progress on epigenetics in the repair of radiation-induced DNA damage in tumors / 中华放射肿瘤学杂志

Radiotherapy kills tumor cells by radiation-induced DNA double-strand breaks (DSB), however, abnormal DSB repair in tumor cells often leads to radioresistance, in which epigenetics plays an important role. Targeting aberrant epigenetic markers may be a potential means of cancer radiosensitization, but the clinical application of the combination of epigenetic drugs and radiotherapy requires further investigation. This article reviews the latest research progress the role of epigenetics in the repair of radiation-induced DNA damage in tumors.

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.

Expressions of HELQ and RAD51C in endometrial stromal sarcoma and their clinical significance / 南方医科大学学报

OBJECTIVE@#To observe the expression of HELQ and RAD51C in normal endometrial and endometrial stromal sarcoma (ESS) and analyze their correlation with the clinical features of the patients.@*METHODS@#The expressions of HELQ and RAD51C proteins were detected by immunohistochemical staining in normal endometrial tissues (14 cases) and tumor tissues from patients with ESS (37 cases) treated in Hunan Provincial Cancer Hospital from January, 2013 to December, 2016. The correlations of the expressions of the two proteins with the patients'age, FIGO staging, tissue type, tumor size, and lymph node metastasis were analyzed.@*RESULTS@#Immunohistochemical staining showed that the expressions of HELQ and RAD51C were both decreased in ESS patients compared with the normal group, and there was a positive correlation between HELQ and RAD51C expression ( < 0.05). HELQ expression in ESS was correlated with the tumor size and type. The expressions of HELQ and RAD51C were not correlated with the patients' age, FIGO stage and status of lymph node metastasis ( > 0.05).@*CONCLUSIONS@#Homologous recombination- directed DNA repair involving HELQ and RAD51C may participate in the occurrence and progression of ESS.

Disulfiram, a Re-positioned Aldehyde Dehydrogenase Inhibitor, Enhances Radiosensitivity of Human Glioblastoma Cells In Vitro / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Glioblastoma, the most common brain tumor in adults, has poor prognosis. The purpose of this study was to determine the effect of disulfiram (DSF), an aldehyde dehydrogenase inhibitor, on in vitro radiosensitivity of glioblastoma cells with different methylation status of O⁶-methylguanine-DNA methyltransferase (MGMT) promoter and the underlying mechanism of such effect. MATERIALS AND METHODS: Five human glioblastoma cells (U138MG, T98G, U251MG, U87MG, and U373MG) and one normal human astrocyte (NHA) cell were cultured and treated with DSF or 6MV X-rays (0, 2, 4, 6, and 8 Gy). For combined treatment, cells were treated with DSF before irradiation. Surviving fractions fit from cell survival based on colony forming ability. Apoptosis, DNA damage repair, and cell cycle distributionwere assayed bywestern blot for cleaved caspase-3, γH2AX staining, and flow cytometry, respectively. RESULTS: DSF induced radiosensitization in most of the glioblastoma cells, especially, in the cells with radioresistance as wildtype unmethylated promoter (MGMT-wt), but did not in normal NHA cell. DSF augmented or induced cleavage of caspase-3 in all cells after irradiation. DSF inhibited repair of radiation-induced DNA damage in MGMT-wt cells, but not in cells with methylated MGMT promoter. DSF abrogated radiation-induced G2/M arrest in T98G and U251MG cells. CONCLUSION: Radiosensitivity of glioblastoma cells were preferentially enhanced by pre-irradiation DSF treatment compared to normal cell, especially radioresistant cells such as MGMT-wt cells. Induction of apoptosis or inhibition of DNA damage repair may underlie DSF-induced radiosensitization. Clinical benefit of combining DSF with radiotherapy should be investigated in the future.