BackgroundTo investigate the prevalence of depressive symptoms among left-behind children (LBC) in junior and senior secondary schools and examine the significant predictors of depressive symptoms, which might provide practical intervention measures for the schools.MethodsBy using stratified random sampling, 1076 (LBC) in junior and senior secondary schools were investigated in the study. Depressive symptoms were assessed using the depression self-rating scale (SDS). SDS raw scores 40 or higher were categorised as depressive symptoms.ResultsThe total prevalence of depressive symptoms was 54.74% for LBC in junior and senior secondary schools, with 73.08% for grade 12 students. The multivariate logistic regression analysis showed that grades, family income, parental relationship, parent-child relationship and teacher-student relationship were significantly associated with depressive symptoms.ConclusionsDepressive symptoms are acommon health problem among LBC in junior and senior secondary schools, and LBC in grade 12 may be at high risk of depressive symptoms. The parents, teachers and schools should pay more attention to LBC, particularly those in grade 12, and provide prevention and early intervention programs such as individual counsel service to prevent depressive symptoms.Electronic supplementary materialThe online version of this article (10.1186/s12889-018-5963-y) contains supplementary material, which is available to authorized users.

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Abstract. The mechanisms underlying lung cancer radioresistance remain to be fully elucidated. The DNA repair pathway is a predominant target of radiotherapy, which is considered to be involved in the acquired radioresistance of cancer cells. The present study aimed to establish a radioresistant cell model using the A549 human lung cancer cell line, and to further investigate the potential mechanisms underlying the radioresistance. The A549R radioresistant lung cancer cell variant was established by exposing the parental A549 cells to repeated γ-ray irradiation at a total dose of 60 Gy. Colony formation assays were then used to determine cell survival following γ-ray exposure. The established radioresistant cells were subsequently treated with or without the NU7026 DNA-PKcs inhibitor. The levels of DNA damage were determined by counting the number of fluorescent γ-H2AX foci in the cells. The cellular capacity for DNA repair was assessed using antibodies for the detection of various DNA repair pathway proteins. The radioresistant sub-clones exhibited significantly decreased survival following NU7026 treatment, compared with the parental cells, as determined by colony formation assays (P<0.05), and this finding was found to be dose-dependent. Treatment with the DNA-dependent protein kinase (DNA-PK) inhibitor significantly reduced γ-H2AX foci formation (P<0.05) following acute radiation exposure in the radioresistant sub-clones, compared with the parental control cells. The decreased levels of γ-H2AX were accompanied by an increase in the percentage of apoptotic cells in the radioresistant cell line following post-radiation treatment with the DNA-PKcs inhibitor. The expression levels of proteins associated with the DNA repair pathway were altered markedly in the cells treated with NU7026. The results of the present study suggested that radioresistance may be associated with enhanced DNA repair following exposure to radiation, resulting in reduced apoptosis. Therefore, the quantity of γ-H2AX determines the radioresistance of cells. The DNA repair pathway is important in mediating radioresistance, and treatment with the DNA-PKcs inhibitor, NU7026 restored the acquired radiation resistance.

Lung cancer is one of the main threats to human health. Survival of patients with lung cancer depends on timely detection and diagnosis. Among the genetic irregularities that control cancer development and progression, there are microRNAs (miRNAs/miRs). The present study aimed to investigate the expression patterns of miR-200a-3p and transcription factor GATA-6 (GATA6) in peripheral blood of patients with non-small cell lung cancer (NSCLC) and their clinical significance. The expression patterns of miR-200a-3p and GATA6 in the peripheral blood of patients with NSCLC and healthy subjects were measured via reverse transcription-quantitative PCR. The correlation between GATA6/miR-200a-3p expression and their diagnostic efficacy were analyzed by receiver operating characteristic curve analysis. The association between miR-200a-3p/GATA6 expression with the patient clinicopathological characteristics, and their correlation with carcinoembryonic antigen (CEA), neuron specific enolase (NSE) and squamous cell carcinoma antigen (SCCAg) were evaluated. The cumulative survival rate was examined, and whether miR-200a-3p and GATA6 expression levels were independently correlated with the prognosis of NSCLC was analyzed using multivariate logistic regression model. The results demonstrated that the expression of miR-200a-3p was high and that of GATA6 was low in the peripheral blood of patients with NSCLC, and both exhibited high clinical diagnostic efficacy. miR-200a-3p was revealed to target GATA6 by dual-luciferase assay. miR-200a-3p in the peripheral blood was correlated with TNM stage, lymph node metastasis and distal metastasis, while GATA6 in the peripheral blood was correlated with TNM stage and lymph node metastasis. miR-200a-3p and GATA6 were positively correlated with CEA and SCCAg, but not with NSE. High expression of miR-200a-3p and low expression of GATA6 predicted poor prognosis in patients with NSCLC. After adjusting for TNM stage, lymph node metastasis, distance metastasis, GATA6, CEA, NSE and SCCAg in the logistic regression model, it was indicated that the high expression of miR-200a-3p increased the risk of death in patients with NSCLC. Collectively, it was revealed that miR-200a-3p and GATA6 were abnormally expressed in the peripheral blood of patients with NSCLC. Serum levels of miR-200a-3p >1.475 and GATA6 <1.195 may assist the early diagnosis of NSCLC. GATA6 may function in NSCLC as a miR-200a-3p target, which may provide a future reference for NSCLC early diagnosis and treatment.

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