Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao 266021, Shandong Province, China.
Sichuan Cancer Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610041, Sichuan Province, China.
Life Sci. 2019 Dec 15;239:117074. doi: 10.1016/j.lfs.2019.117074. Epub 2019 Nov 18.
FL118, a novel camptothecin analogue, has been extensively studied for its superior antitumor potency. The aim of this research study is to explore its potential mechanism of action in anti- colorectal cancer (CRC).
The effect of FL118 on CRC cell proliferation was assessed using CCK-8 assay, while apoptosis was detected using Hoechst staining and Flow cytometry assays. The expression levels of CIP2A were analyzed using qRT-PCR. The expression of CIP2A, PP2A-C, Bax, cleaved caspase-3 and PARP were analyzed using western blotting analysis. The expressions of related proteins in CRC tissues were detected using immunohistochemical staining. TUNEL assay was used to detect apoptosis of tissue. Toxicity of FL118 in primary organs were examined using H&E staining.
The results show that FL118 can inhibit the proliferation and clonogenic potential of CRC cells and increase the expression of pro-apoptosis proteins, Bax, cleaved caspase-3 and PARP. Microarray analyses found that FL118 treatment significantly decreases cancerous inhibition of protein phosphatase 2A (CIP2A). Further validation found that CIP2A is aberrantly upregulated in CRC tissues, and is positively correlated with the progression of CRC. In vitro findings confirm that FL118 mediates the downregulation of CIP2A, at both protein and mRNA levels. Co-treatment with Okadaic acid (OA) (a PP2A inhibitor) partially abolishes the anti-proliferative and pro-apoptotic effect of FL118. Consistently, in vivo experiment demonstrates that FL118 can effectively suppress tumorigenesis without any obvious toxic effects.
Collectively, these findings exhibit the anti-neoplastic effects of FL118 against CRC through the down regulation of CIP2A, which subsequently enhances the activity of PP2A.
FL118 是一种新型喜树碱类似物，因其优异的抗肿瘤活性而得到广泛研究。本研究旨在探索其在抗结直肠癌（CRC）中的潜在作用机制。
采用 CCK-8 法评估 FL118 对 CRC 细胞增殖的影响，采用 Hoechst 染色和流式细胞术检测细胞凋亡，采用 qRT-PCR 分析 CIP2A 的表达水平，采用 Western blot 分析检测 CIP2A、PP2A-C、Bax、cleaved caspase-3 和 PARP 的表达水平，采用免疫组化染色检测 CRC 组织中相关蛋白的表达，采用 TUNEL 检测组织细胞凋亡，采用 H&E 染色检测 FL118 对原发性器官的毒性。
结果表明，FL118 可抑制 CRC 细胞的增殖和克隆形成能力，并增加促凋亡蛋白 Bax、cleaved caspase-3 和 PARP 的表达。微阵列分析发现，FL118 处理可显著降低癌症抑制蛋白磷酸酶 2A（CIP2A）的表达。进一步验证发现，CIP2A 在 CRC 组织中异常上调，并与 CRC 的进展呈正相关。体外研究结果证实，FL118 可在蛋白和 mRNA 水平下调 CIP2A。用 Okadaic acid（OA）（一种 PP2A 抑制剂）共同处理可部分消除 FL118 的抗增殖和促凋亡作用。同样，体内实验表明，FL118 可有效抑制肿瘤发生，且无明显毒性作用。
综上所述，这些研究结果表明，FL118 通过下调 CIP2A 来抑制 CRC 的肿瘤发生，从而增强 PP2A 的活性。
