Effect And Mechanism Of Phytosterol On The Occurrence And Progression Of Lung Cancer

Background: Lung cancer is one of the most common cancers in the world,and it is also an important disease threatening the health of Chinese residents.Its morbidity and mortality rank first among all cancers.The main treatments for lung cancer include surgery,chemotherapy and targeted drugs.As patients with non-small cell lung cancer are difficult to detect at an early stage and are usually diagnosed after metastasis occurs,seeking new methods to prevent and treat lung cancer is the current research focus.Phytosterols are plant compounds found in grains and nuts.Phytosterols have been proven to have cholesterol-lowering,anti-inflammatory activities,and have certain preventive and therapeutic effects on colon cancer,breast cancer,gastric cancer and other diseases.However,there are few studies on the effect of phytosterols on lung cancer,and the mechanism of action on lung cancer is not clear.This article will discuss the effects and mechanisms of phytosterols on the occurrence and progression of lung cancer,and provide new ideas for the application of dietary ingredients in the prevention and treatment of lung cancer.Objective:(1)Observe the effect of 2% phytosterol diet or control diet feeding on the occurrence and development of urethane induced lung cancer in C57BL/6J mice;(2)Use high-throughput transcriptome sequencing methods to find genes and signal pathways that are differentially expressed with 2%phytosterol diet or control diet feeding;(3)To explore the effect of phytosterols on lung cancer and its underlying mechanism though in vitro and in vivo experiments.Methods: Through continuous intraperitoneal injection of 1g/kg﹒bw 10%urethane for 10 weeks,the C57BL/6J mouse induced lung cancer model was successfully established after the subsequent 15-week latency period.The mice in the treatment group were given 2% phytosterol diet,and the mice in the control group were given normal diet.After the experiment,the number and size of tumor nodules in mice were observed and counted,and the effect of 2% phytosterol diet on the number of tumors in mice was judged.Using high-throughput transcriptome sequencing methods to analyze the lung tissues of mice,looking for differential genes and signal pathways altered by phytosterol diet.RT-qPCR and Western blot(WB)were used to further verify the effect of phytosterols on lung cancer and its potential mechanism.At the cellular level,the effects of phytosterols on the proliferation and migration of two lung adenocarcinoma cell lines A549 and H1975 were tested,and the mechanism of action was discussed.Results:(1)Compared with the control mice,there was no significant difference in the body weight of the mice in the 2% phytosterol feeding group.The number of tumor nodules in the lung tissue of the two groups of mice was counted,and no statistical difference was found,but it was observed that the number of tumor nodules larger than 1.0mm in the lung tissue of the control group was more than that of the phytosterol group.(2)After high-throughput transcriptome sequencing analysis of mouse lung tissue,530 up-regulated differential genes and 258 down-regulated differential genes were screened between the two groups of mice.KEGG analysis of these differential genes found that the up-regulated differential genes are mainly enriched in pathways such as thermogenesis,oxidative phosphorylation,and ribosome;down-regulated differential genes are in the mTOR signaling pathway,Hippo signaling pathway,MAPK signaling pathway,PI3K-Akt signaling pathway etc.are affected by phytosterols.(3)Using RT-qPCR,Western blot and other methods to verify that in animal models,phytosterols inhibit the expression of Akt/mTOR/S6 K pathway.(4)Phytosterols reduced the cell viability of A549 and H1975 lung adenocarcinoma cell lines in a dose-effect relationship.After treating A549 and H1975 cells with 50 μM β-sitosterol for 48 hours,the number of cell clones was less than that in the control group,indicating that β-sitosterol can inhibit the proliferation of lung adenocarcinoma cells.(5)A549 and H1975 cells were treated with 50μM β-sitosterol for 48 h,which can slow down the healing rate of scratches compared with the control group,and reduce the number of cells passing through the transwell chamber.It can inhibit cell migration.Then detecting the expression of E-cadherin and Vimentin by Western blot.The expression of E-cadherin has increased,and the expression of Vimentin has decreased significantly,indicating that β-sitosterol may inhibit cell migration by inhibiting the occurrence of EMT in lung adenocarcinoma cells.(6)Detecting the expression of Akt/mTOR/S6 K pathway in A549 cells treated with 50μM β-sitosterol for 48 hours,the results showed thatβ-sitosterol significantly inhibited the activation of Akt/mTOR/S6 K pathway,indicating that phytosterols may act on this pathway to inhibit lung cancer.Conclusions:(1)2% phytosterol diet can inhibit the development of a C57BL/6J mouse lung cancer model induced by urethane by inhibiting the activation of the Akt/mTOR/S6 K pathway;(2)Phytosterols can reduce the viability of lung adenocarcinoma cells by inhibiting the activation of Akt/mTOR/S6 K pathway,and inhibit the proliferation and cell migration of lung adenocarcinoma cells.