Low-dose all-trans retinoic acid enhances cytotoxicity of cisplatin and 5-fluorouracil on CD44+ cancer stem cells

Cis-diamminedichloridoplatinum(II)(CDDP)-based combination chemotherapy is frequently used in gastrointestinal cancer. The synergistic mechanism of all-trans retinoic acid (ATRA), cisplatin (CDDP) and 5-fluorouracil (5-FU) in combination remains unclear. Despite their potent antitumor properties, resistance to CDDP and 5-FU develops frequently in tumors. To clarify this mechanism, we determined the sensitivity to each drug and their combination in two gastrointestinal cancer stem cells (CSCs) subpopulation.Here, we report the identification and separation of CD44⁺ cells from human gastric carcinoma (AGS) and human esophageal squamous cell carcinoma (KYSE-30) cancer cell lines by magnetic activated cell sorting (MACS). We allowed the CD44^± cells to grow 6 days at a subtoxic concentration of ATRA and then treated with different concentration of CDDP and 5-FU for 24 h. The cytotoxicity was examined by cell proliferation MTT assay. Additionally, AO/EB staining was used for detection of apoptotic cells. In order to determine whether the growth inhibition was also associated with changes in cell cycle distribution, cell cycle analysis was performed using flow cytometry.Low concentration of ATRA (1 μM, 6days) followed by 5-FU and CDDP was found to be more effective than either drugs alone, thus resulting in synergistic cytotoxicity in Kyse-30 and AGSCD44^± cells. Furthermore, there was an indication that the combination of ATRA with 5FU and CDDP caused an increase in cell cycle arrest in G2/M and G0/G1.We conclude that low concentration of ATRA enhances the cytotoxicity of CDDP and 5FU by facilitating apoptosis and cell cycle arrest in gastrointestinal CSCs and provide a rational basis for the design of novel, well-tolerated CDDP- and 5FU-based chemotherapy in human gastrointestinal carcinoma.     

结核特异性抗原与CD4+T细胞计数比值对AIDS合并肺结核的辅助诊断价值

目的:评价结核特异性抗原(TBAg)与CD4⁺T淋巴细胞(简称“CD4”)计数的比值(TBAg/CD4)对AIDS合并活动性肺结核(PTB)的辅助诊断价值。方法:采用前瞻性研究的方法,参照入组标准纳入2018年1月至2020年12月苏州市第五人民医院收治的262例疑似活动性PTB的AIDS患者,并将患者分为AIDS+PTB组(152例)和AIDS组(110例)。采集患者入院次日清晨静脉血进行干扰素体外释放酶联免疫法(TB-IGRA)、血常规、CD4检测,比较两组间TBAg水平和TBAg/CD4比值的差异。以临床诊断为参考标准,评价TB-IGRA检测AIDS合并PTB的效能,并以受试者工作特征曲线(ROC曲线)下面积(AUC)确定诊断效能最佳的检测指标。结果:以临床诊断为参考标准,TB-IGRA检测AIDS合并活动性PTB的敏感度和特异度分别为53.95%(82/152)和75.45%(83/110)。TB-IGRA检测AIDS+PTB组的TBAg、TBAg/CD4水平[分别为92.51(-68.20,906.10)pg/ml和1.01(0.00,10.12)]均明显高于AIDS组[分别为85.20(-33.80,801.30)pg/ml和0.11(0.00,2.07)],对照培养管抗原浓度[529.50(12.50,1160.50)pg/ml]明显低于AIDS组[694.50(29.90,990.00)pg/ml],差异均有统计学意义(Z=-3.481、-9.557、3.289,P值均<0.001)。ROC曲线分析显示,对照培养管抗原浓度、TBAg、TBAg/CD4对诊断AIDS合并活动性PTB的AUC值分别为0.718、0.637和0.842;当TBAg/CD4的临界值为0.592时,约登指数最大,其敏感度为88.10%,特异度为77.10%。结论:相较于AIDS患者,AIDS合并PTB患者的TBAg和TBAg/CD4水平均明显升高,尤以TBAg/CD4诊断价值高,结合患者免疫状态的影响,认为TBAg/CD4对AIDS合并PTB患者具有一定辅助诊断价值。