Department of Neurotoxicology, Graduate School of Medical Sciences and Medical School, Nagoya City University, Nagoya, Aichi 467‑8601, Japan.
Laboratory of Pharmacognosy, Gifu Pharmaceutical University, Gifu 501‑1196, Japan.
Int J Oncol. 2021 Feb;58(2):251-265. doi: 10.3892/ijo.2020.5160. Epub 2020 Dec 14.
The present study, to the best of our knowledge, is the first systematic study of the inhibitory effects of palmitoyl piperidinopiperidine (PPI; Japan Patent no. 5597427), on colon carcinogenesis. PPI exhibited marked growth inhibitory activity in several human colon carcinoma cell lines, with IC50 values of approximately 0.5‑2.2 µM. In silico docking analysis indicated that PPI could bind to the SH2 domain of signal transducer and activator of transcription 3 (STAT3). PPI markedly inhibited the transcriptional activity of the SW837 cell line. Flowcytometric analysis demonstrated that PPI induced an increase in the number of cells in the G1 phase of the cell cycle, and induced sub‑G1 fractions of cells at a higher concentration level of PPI. In the HT29 and SW837 cells, western blot analyses exhibited that in whole cell lysates, PPI induced a marked decrease in the expression levels of p‑STAT3, but not in the levels of STAT3 in these cells. PPI also induced a marked decrease in the expression levels of both STAT3 and p‑STAT3 in the chromatin fraction. In addition, PPI affected the protein expression levels of cyclin D1, p53, Bcl‑2, Bcl‑xL and vascular endothelial growth factor (VEGF). In the HT29 cells, PPI induced a marked and dose‑dependent increase in the expression levels of Bax, cleaved caspase‑3, cleaved caspase‑7, cleaved caspase‑8, cleaved caspase‑9 and cleaved poly (ADP‑ribose) polymerase (PARP). In animal model systems, PPI inhibited the growth of implanted carcinoma cells, and also induced a significant decrease in the multiplicity of colonic aberrant crypt foci. In addition, a marked and dose‑dependent inhibition of angiogenesis of the chick chorioallantoic membrane was observed. As regards the possible molecular mechanisms, it is suggested that the inhibition of STAT3 by PPI may affect the function of molecules that are related to apoptosis, angiogenesis and cell cycle progression, eventually contributing to the PPI‑induced growth inhibitory effects.
本研究据我们所知是首次系统研究棕榈酰哌啶哌啶（PPI；日本专利号 5597427）对结肠癌发生的抑制作用。PPI 对几种人结肠癌细胞系表现出明显的生长抑制活性，IC50 值约为 0.5-2.2 μM。计算机对接分析表明，PPI 可以与信号转导和转录激活因子 3（STAT3）的 SH2 结构域结合。PPI 显著抑制了 SW837 细胞系的转录活性。流式细胞术分析表明，PPI 诱导细胞周期 G1 期细胞数量增加，并在更高浓度水平的 PPI 诱导细胞出现亚 G1 亚群。在 HT29 和 SW837 细胞中，western blot 分析表明，在全细胞裂解物中，PPI 诱导 p-STAT3 的表达水平明显降低，但在这些细胞中 STAT3 的水平没有降低。PPI 还诱导染色质部分中 STAT3 和 p-STAT3 的表达水平明显降低。此外，PPI 影响细胞周期蛋白 D1、p53、Bcl-2、Bcl-xL 和血管内皮生长因子（VEGF）的蛋白表达水平。在 HT29 细胞中，PPI 诱导 Bax、裂解的 caspase-3、裂解的 caspase-7、裂解的 caspase-8、裂解的 caspase-9 和裂解的多聚（ADP-核糖）聚合酶（PARP）的表达水平明显且呈剂量依赖性增加。在动物模型系统中，PPI 抑制植入癌细胞的生长，并显著降低结肠异常隐窝焦点的多发性。此外，还观察到鸡胚绒毛尿囊膜血管生成的明显和剂量依赖性抑制。关于可能的分子机制，据推测，PPI 对 STAT3 的抑制可能会影响与细胞凋亡、血管生成和细胞周期进展相关的分子的功能，最终导致 PPI 诱导的生长抑制作用。
