Salidroside regulates tumor microenvironment of non-small cell lung cancer via Hsp70/Stub1/Foxp3 pathway in Tregs.

BACKGROUND: The treatment of non-small cell lung cancer (NSCLC) is challenging due to immune tolerance and evasion. Salidroside (SAL) is an extract in traditional Chinese medicine and has a potential antitumor effect. However, the mechanism of SAL in regulating the immunological microenvironment of NSCLC is yet to be clarified. METHODS: The mouse model with Lewis lung cancer cell line (3LL) in C57BL/6 mice was established. And then, the percentage of tumor-infiltrating T cell subsets including Treg was detected in tumor-bearing mice with or without SAL treatment. In vitro, the effect of SAL on the expression of IL-10, Foxp3 and Stub1 and the function of Treg were detected by flow cytometry. Network pharmacology prediction and molecular docking software were used to predict the target of SAL and intermolecular interaction. Furthermore, the effect of SAL on the expression of Hsp70 and the co-localization of Stub1-Foxp3 in Treg was confirmed by flow cytometry and confocal laser microscopy. Finally, Hsp70 inhibitor was used to verify the above molecular expression. RESULTS: We discovered that SAL treatment inhibits the growth of tumor cells by decreasing the percentage of tumor-infiltrated CD4+Foxp3+T cells. SAL treatment downregulates the expression of Foxp3 in Tregs, but increases the expression of Stub1, an E3 ubiquitination ligase upstream of Foxp3, and the expression of Hsp70. Inhibiting the expression of Hsp70 reverses the inhibition of SAL on Foxp3 and disrupts the colocalization of Stub1 and Foxp3 in the nucleus of Tregs. CONCLUSIONS: SAL inhibits tumor growth by regulating the Hsp70/stub1/Foxp3 pathway in Treg to suppress the function of Treg. It is a new mechanism of SAL for antitumor therapy.

Sanguinarine Represses the Growth and Metastasis of Non-small Cell Lung Cancer by Facilitating Ferroptosis.

OBJECTIVE: Ethnopharmacological relevance: Sanguinarine (SAG), a natural benzophenanthridine alkaloid derived from the root of Sanguinaria canadensis Linn. (Bloodroot), possesses a potential anticancer activity. Lung carcinoma is the chief cause of malignancy-related mortality in China. Non-small cell lung carcinoma (NSCLC) is the main subtype of lung carcinoma and accounts for about eighty-five percent of this disease. Current treatment in controlling and curing NSCLC remains deficient. AIM: The role and underlying mechanism of SAG in repressing the growth and metastasis of NSCLC were explored. MATERIALS AND METHODS: The role of SAG in regulating the proliferation and invasion of NSCLC cells was evaluated in vitro and in a xenograft model. After treatment with SAG, Fe2+ concentration, reactive oxygen species (ROS) levels, malondialdehyde (MDA), and glutathione (GSH) content in NSCLC cells were assessed to evaluate the effect of SAG on facilitating ferroptosis. RESULTS: SAG exhibited a dose- and time-dependent cytotoxicity in A549 and H3122 cells. SAG treatment effectively repressed the growth and metastasis of NSCLC in a xenograft model. We, for the first time, verified that SAG triggered ferroptosis of NSCLC cells, as evidenced by increased Fe2+ concentration, ROS level, and MDA content, and decreased GSH content. Mechanistically, SAG decreased the protein stability of glutathione peroxide 4 (GPX4) through E3 ligase STUB1-mediated ubiquitination and degradation of endogenous GPX4. GPX4 overexpression restored the proliferation and invasion of NSCLC cells treated with SAG through inhibiting ferroptosis. CONCLUSION: SAG inhibits the growth and metastasis of NSCLC by regulating STUB1/GPX4-dependent ferroptosis.