Objective The aims of the study were to investigate the effects of human islet amyloid polypeptide (hIAPP) on autophagy in INS-1 cells and its underlying mechanism,and to explore the role of autophagy in hIAPP-induced cytotoxicity and oxidative stress.Methods INS-1 cells were treated with hIAPP (10 μmol/L) for 24 h in the presence or absence of N-acetyl-L-cysteine (NAC),compound C,5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) and 3-methyladenine (3-MA),respectively.Transmission electron microscopy was used to observe the number of autophagosome in cells.Cell viability was determined by methyl thiazolyl tetrazolium (MTT) test.2',7'-dichlorofluorescin diacetate (DCFH-DA) assay was used to measure the relative levels of reactive oxygen species (ROS).Western blot was used to detect expression of adenosine monophosphate-activated protein kinase (AMPK) and autophagic markers p62 and microtubule associated protein 1 light chain3 (LC3).Results Treatment of INS-1 cells with hIAPP resulted in a significant increase in the number of autophagosomes and the expression of LC3-Ⅱ/LC3-Ⅰ (both P＜0.05).Meanwhile,treatment of INS-1 cells with hIAPP enhanced the level of ROS to 1.76 times of control cells (P＜0.01).Co-treatment with NAC,an antioxidant,inhibited hIAPP-induced ROS generation,and the expression of LC3-Ⅱ/LC3-Ⅰ and p-AMPK in the INS-1 cells (all P＜0.05).Pretreatment of INS-1 cells with AMPK inhibitor compound C suppressed hIAPP and AICAR,an activator of AMPK,induced expression of LC3-Ⅱ/LC3-Ⅰ and p-AMPK (all P＜0.05).Autophagic inhibitor 3-MA and compound C aggravated the hIAPP-induced cell death and ROS generation in INS-1 cells (All P＜0.05).The cytotoxic effects of hIAPP were significantly attenuated by co-treatment with AICAR (P＜0.05).Conclusion Autophagy may act as an adaptive mechanism to alleviate hIAPP-induced oxidative damage and toxicity in INS-1 cells.

Objective To investigate the relationship between the expression of long non-coding RNA C-terminal binding protein 1 antisense RNA2(LncRNA CTBP1-AS2)and microRNA-140-5p(miR-140-5p)levels in nasopharyngeal carcinoma tissues and the radiotherapeutic effect and prognosis.Methods A total of 222 nasopharyngeal carcinoma patients diagnosed in Nantong Cancer Hospital from March 2018 to March 2020 were collected as the nasopharyngeal carcinoma group.The clinical data of these patients were recorded,the radiotherapeutic effect and prognosis were evaluated,and they were grouped into the survival group(n=194)and the death group(n=28).Meanwhile,another 219 patients with nasopharyngeal inflammation were collected as the control group.Correlation between LncRNA CTBP1-AS2 and miR-140-5p expression levels in nasopharyngeal carcinoma patients was calculated using Pearson correlation analysis.Kaplan-Meier survival curve was applied to analyze the relationship between the expression levels of LncRNA CTBP1-AS2 and miR-140-5p in nasopharyngeal carcinoma tissue and prognosis.Multivariate analysis was conducted on the prognosis of nasopharyngeal carcinoma patients using Cox proportional risk regression model.Results The expression level of LncRNA CTBP1-AS2 in the tissues of patients in nasopharyngeal carcinoma group(2.25±0.46)was higher than that in the control group(1.02±0.22),while the expression level of miR-140-5p(0.67±0.19)was lower than that in the control group(1.01±0.23),and the differences were statistically significant(t=35.742,16.934,all P<0.001).There was a negative correlation between LncRNA CTBP1-AS2 and miR-140-5p expression levels in nasopharyngeal carcinoma patients(r=-0.624,P<0.001).The total effective rate(74.11%)and 3-year survival rate(77.68%)of nasopharyngeal carcinoma patients with high expression of LncRNA CTBP1-AS2 after radiotherapy were lower than those with low expression(93.64%,97.27%),and the differences were statistically significant(χ2=15.578,19.331,all P<0.001).The total effective rate(93.58%)and 3-year survival rate(96.33%)of patients with high expression of miR-140-5p after radiotherapy were higher than those of patients with low expression(74.34%,78.76%),and the differences were statistically significant(χ2=15.119,15.538,all P<0.001).The magnetic resonance amide proton transfer(APT)value(2.10±0.26),the proportion of patients with radiotherapy failure(85.71%),high expression of LncRNA CTBP1-AS2(89.29%),and low expression of miR-140-5p(85.71%)in the death group were higher than those in the survival group(1.82±0.31,6.19%,44.85%,45.88%),and the differences were statistically significant(t/χ2=4.551,108.127,19.331,15.538,all P<0.001).The level of LncRNA CTBP1-AS2 was a risk factor for mortality within 3 years in nasopharyngeal carcinoma patients(HR=2.762,95%CI:1.510～5.051,P=0.001),while the level of miR-140-5p was a protective factor for mortality within 3 years in nasopharyngeal carcinoma patients(HR=0.817,95%CI:0.718～0.930,P=0.002).Conclusion LncRNA CTBP1-AS2 was highly expressed,while miR-140-5p was lowly expressed in nasopharyngeal carcinoma tissue,indicating the two may be closely related to the radiotherapeutic effect and prognosis.