The Antitumor Effect Of Xihuang Pill On Treg Cells Decreased In The Tumor Microenvironment Of 4T1 Breast Tumor-bearing Mouse By Regulating MEKK1/SEK1/JNK1/AP-1 Pathway

Objective: To determine the role of the MEKK1/SEK1/JNK1/AP-1 pathway in the action of Xihuang pill(XHP)in reducing regulatory T(Treg)cell numbers in the tumor microenvironment in a 4T1 mouse breast cancer model,and to clarify the anti-tumor mechanism of XHP in breast cancer.Methods: We established a mouse 4T1 breast cancer model.Model mice were divided into negative control group(equal volume of distilled water)and XHP low,medium,high dose groups(0.39,0.78,1.95 g/kg).After being administered XHP for 2 weeks,tumor tissues were then removed,weighed,sliced,and homogenized.Treg cells in the tumor microenvironment were isolated by magnetic cell sorting and analyzed by immunohistochemistry and flow cytometry.Treg cell apoptosis was detected by TdT-mediated dUTP nick end labeling.mRNA expression levels of MEKK1,SEK1,JNK1,and AP-1 in Treg cells in the tumor microenvironment were detected by quantitative real-time PCR and their protein expression levels were detected by immunofluorescence staining and western blot.Results: Tumor weights were significantly lower in the XHP medium and high dose groups compared with the negative control group.The overall number of Treg cells in the tumor microenvironment decreased while the number of apoptotic Treg cells increased with increasing doses of XHP.mRNA and protein expression levels of MEKK1,SEK1,JNK1,and AP-1 in Treg cells in the tumor microenvironment increased with increasing doses of XHP.Conclusion: XHP might reduce the number of Treg cell in the tumor microenvironment by promoting Treg cell apoptosis,therefore relieving the immune inhibition and recovering the body anti-tumor immunity function,further inhibiting the tumor growth of 4T1 mouse breast cancer;The mechanism of XHP may be related to upregulation of gene and protein expression of MEKK1,SEK1,JNK1,and AP-1 in Treg cells in the tumor microenvironment.