Objective To investigate the regulatory effect of circular RNA ASAP1(circASAP1)targeting microRNA-4500(miR-4500)on the proliferation and apoptosis of osteosarcoma cells.Methods Human osteosarcoma cells(Saos-2)were selected as the experimental subjects and cul-tured in DMEM medium containing 10％fetal bovine serum while maintaining 5％CO2.The expres-sions of circASAP1 and miR-4500 in osteosarcoma tissues were detected using RT-qPCR.Saos-2 cells were transfected with si-NC(40 nmol/L),si-circASAP1(40 nmol/L),pcDNA(0.4 μg),pcDNA-circASAP1(0.4 μg),miR-NC(40 nmol/L),miR-4500 mimics(40 nmol/L),si-circASAP1+anti-miR-NC(40 nmol/L),and si-circASAP1+anti-miR-4500(40 nmol/L),respectively.Cell proliferation and apoptosis were assessed using CCK-8,colony formation assays,and flow cytometry.The interaction between circASAP1 and miR-4500 was analyzed using a dual-luciferase reporter assay.Results Compared with adjacent non-tumor tissues,the expression of circASAP1 was significantly upregulated,while that of miR-4500 was significantly downregulated in osteosarcoma tissues(P＜0.001).Compared with the si-NC group,the si-circASAP1 group exhibited significantly decreased circASAP1 expression,optical density(OD)values,and the number of cell colonies(P＜0.001).Compared with the si-NC group,the si-circASAP1 group showed significantly upregulated levels of cleaved-caspase3 protein,cleaved-caspase9 protein,and the apoptosis rate(P＜0.001).StarBase search revealed specific binding sequences between miR-4500 and circASAP1.Co-transfection of miR-4500 mimics and WT-circASAP1 significantly reduced the relative luciferase activity of the cells[(0.34±0.03)versus(0.95±0.06),t=27.280,P＜0.001].The expression of miR-4500 in the pcDNA-circASAP1 group was significantly lower than that in the pcDNA group,whereas the ex-pression of miR-4500 in the si-circASAP1 group was significantly higher than that in the si-NC group(P＜0.001).Compared with the miR-NC group,the miR-4500 group exhibited significantly in-creased miR-4500 expression,cleaved-caspase3 protein levels,cleaved-caspase9 protein levels,and the apoptosis rate,while the OD values and the number of colonies significantly decreased(P＜0.001).Compared with the si-circASAP1+anti-miR-NC group,the si-circASAP1+anti-miR-4500 group showed significantly decreased miR-4500 expression,cleaved-caspase3 protein levels,cleaved-caspase9 protein levels,and the apoptosis rate,while the OD values and the number of col-onies significantly increased(P＜0.001).Conclusion The expression of circASAP1 is increased,while that of miR-4500 is decreased in osteosarcoma tissues.Moreover,circASAP1 promotes the proliferation and inhibits the apoptosis of osteosarcoma cells by targeting miR-4500.

Objective To analyze the characteristics of MR amide proton transfer(APT)imaging and enhancement signals in benign and malignant muscular soft tissue tumors and to explore the value of MR APT imaging,contrast enhancement techniques,and their combined application in the differential diagnosis of benign and malignant muscular soft tissue tumors.Methods A retrospective analysis was conducted on 34 patients with muscular soft tissue tumors confirmed by pathology,including 13 malignant and 21 benign.All patients underwent both MR with contrast enhancement and APT imaging examinations before surgery.APT values were obtained through post-processing on an image workstation.The enhancement signal characteristics and APT values were compared between benign and malignant muscular soft tissue tumors.The receiver operating characteristic(ROC)curve was used to analyze the diagnostic efficacy of the two techniques alone and in combination for differentiating between benign and malignant muscular soft tissue tumors.Results There were significant differences in enhancement signal characteristics on MR and APT values between benign and malignant muscular soft tissue tumors(P<0.05).The enhancement signal of malignant tumors was more heterogeneous,with higher enhancement degree than benign tumors;the APT value of benign tumors was(2.20±0.93)%,and the APT value of malignant tumors was(3.52±0.83)%,the ROC curve analysis determined a cutoff APT value of 2.82%for malignant tumors,with a diagnostic specificity of 90.5%and sensitivity of 76.9%.The area under the curve(AUC)for MR with contrast enhancement,APT imaging,and the combination of the two techniques were 0.694,0.857 and 0.894,respectively.No significant differences were found in the diagnostic efficacy between MR with contrast enhancement and APT imaging(Z=1.587,P=0.112 6)or between APT imaging and the combination of the two tech-niques(Z=1.217,P=0.223 4),but there was significant difference between MR with contrast enhancement and the combination of the two techniques(Z=2.428,P=0.015 2).Moreover,the combination of the two techniques showed the overall highest diag-nostic efficacy.Conclusion The combined application of MR APT imaging and contrast enhancement techniques is more beneficial for the qualitative diagnosis of muscular soft tissue tumors.

Objective To analyze the characteristics of MR amide proton transfer(APT)imaging and enhancement signals in benign and malignant muscular soft tissue tumors and to explore the value of MR APT imaging,contrast enhancement techniques,and their combined application in the differential diagnosis of benign and malignant muscular soft tissue tumors.Methods A retrospective analysis was conducted on 34 patients with muscular soft tissue tumors confirmed by pathology,including 13 malignant and 21 benign.All patients underwent both MR with contrast enhancement and APT imaging examinations before surgery.APT values were obtained through post-processing on an image workstation.The enhancement signal characteristics and APT values were compared between benign and malignant muscular soft tissue tumors.The receiver operating characteristic(ROC)curve was used to analyze the diagnostic efficacy of the two techniques alone and in combination for differentiating between benign and malignant muscular soft tissue tumors.Results There were significant differences in enhancement signal characteristics on MR and APT values between benign and malignant muscular soft tissue tumors(P<0.05).The enhancement signal of malignant tumors was more heterogeneous,with higher enhancement degree than benign tumors;the APT value of benign tumors was(2.20±0.93)%,and the APT value of malignant tumors was(3.52±0.83)%,the ROC curve analysis determined a cutoff APT value of 2.82%for malignant tumors,with a diagnostic specificity of 90.5%and sensitivity of 76.9%.The area under the curve(AUC)for MR with contrast enhancement,APT imaging,and the combination of the two techniques were 0.694,0.857 and 0.894,respectively.No significant differences were found in the diagnostic efficacy between MR with contrast enhancement and APT imaging(Z=1.587,P=0.112 6)or between APT imaging and the combination of the two tech-niques(Z=1.217,P=0.223 4),but there was significant difference between MR with contrast enhancement and the combination of the two techniques(Z=2.428,P=0.015 2).Moreover,the combination of the two techniques showed the overall highest diag-nostic efficacy.Conclusion The combined application of MR APT imaging and contrast enhancement techniques is more beneficial for the qualitative diagnosis of muscular soft tissue tumors.