Liver cancer, one of the most common types of cancer in the world, is the second leading cause of death for cancer patients. For liver cancer, there is an urgent need for an effective treatment with no or less toxic side effects. Lactonic sophorolipids (LSL), as a potential anticancer drug, has attracted wide attention of pharmaceutical researchers with its good biological activities. The effects of LSL and cell death inhibitors were measured by MTT test on HepG2 cells. Meanwhile, the morphology of the cells was observed under a microscope. The apoptosis rate was detected by flow cytometry, and the expression levels of enzyme activity of Caspase-3 and Caspase-9 were measured by detection kits. Meanwhile, mRNA levels of Apaf-1, Caspase-3, Bax, and Bcl-2 were measured by quantitative real-time RT-PCR; protein levels of Caspase-3, Cleaved Caspase-3, Bax, and Bcl-2 were measured by western blot. LSL can inhibit the proliferation of cells, and it is possible to induce apoptosis in cells. The HepG2 cells with LSL co-culture exhibited typical apoptotic morphology, and the expression levels of enzyme activity of Caspase-3 and Caspase-9 increased (P< 0.05). We also found that LSL increases cell apoptosis rate and regulates the expression of genes and proteins associated with apoptosis through the Caspase-3 pathway. These results indicate that LSL may be one of the potential drug candidates to inhibit the proliferation and induce apoptosis in HepG2 cells.

Key points

• LSL, which is of good biological activities such as anti-bacterium, virus elimination, and inflammatory response elimination, has been firstly used to intervene in vitro to investigate its effect on HepG2 cell proliferation.

• LSL can inhibit the proliferation of cells, and it is possible to induce apoptosis in HepG2 cells through the Caspase-3 pathway.

• The mechanism of LSL action on HepG2 cell proliferation was firstly also discussed, which provides a certain experimental reference for the clinical treatment of liver cancer.

Graphical abstract

中文翻译：

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内酯槐糖脂通过Caspase-3途径诱导人HepG2细胞凋亡

肝癌是世界上最常见的癌症之一，是癌症患者第二大死亡原因。对于肝癌，迫切需要无毒副作用或少毒副作用的有效治疗方法。内酯槐糖脂（LSL）作为一种潜在的抗癌药物，以其良好的生物活性引起了药物研究者的广泛关注。通过MTT试验测量LSL和细胞死亡抑制剂对HepG2细胞的作用。同时，在显微镜下观察细胞的形态。流式细胞仪检测细胞凋亡率，检测试剂盒检测Caspase-3和Caspase-9酶活性的表达水平。同时，Apaf-1，Caspase-3，Bax和mRNA的mRNA水平Bcl-2通过实时定量RT-PCR测定；通过蛋白质印迹法测量Caspase-3，Cleaved Caspase-3，Bax和Bcl-2的蛋白水平。LSL可以抑制细胞的增殖，并有可能诱导细胞凋亡。LSL共培养的HepG2细胞表现出典型的凋亡形态，Caspase-3和Caspase-9的酶活性表达水平增加（P <0.05）。我们还发现，LSL通过Caspase-3途径提高细胞凋亡率并调节与凋亡相关的基因和蛋白质的表达。这些结果表明，LSL可能是抑制HepG2细胞增殖并诱导其凋亡的潜在候选药物之一。

关键点

•具有良好生物活性（如抗菌，消除病毒和消除炎症反应）的LSL被首先用于体外干预，以研究其对HepG2细胞增殖的影响。

• LSL可以抑制细胞增殖，并且有可能通过Caspase-3途径诱导HepG2细胞凋亡。

•首先讨论了LSL对HepG2细胞增殖的作用机制，为肝癌的临床治疗提供了一定的实验参考。

图形概要