HRI Confers Tamoxifen Resistance To HR+HER2-breast Cancer Cells By Activating EIF2A/OAS3/ERα Pathway

Objective: To explore Heme-Regulate inhibitor(HRI)predictive prognosis effects of hormone receptor positive,human epidermal growth factor receptor 2 negative(HR+ HER2-)breast cancer patients,and verifie its effect on cancer cell function,and to explore the effect of HRI to HR+ HER2-breast cancer cell tamoxifen resistance in vivo and in vitro and it’s mechanism.Methods: Explore the prognosis biomarker related to HR+ HER2-breast cancer patients with HR +HER2-breast cancer patients through The Cancer Genome Atlas,TCGA,Gene Expression Omnibus,GEO,Molecular Taxonomy of Breast Cancer International Consortium,METABRIC,and Kaplan-Meier Plotter.The expression of HR+ HER2-breast cancer cell was knocked by si RNA,and the cell proliferation was detected.The effects of cell tamoxifen sensitivity by adjusting HRI expression of HR+ HER2-breast cancer cells were detected in vivo and in vitro;Verify the different ISR activation level of integrated stress response(ISR),in MCF7 / TAMR and MCF7 cells,and verify whether HRI can regulate the MCF7 / TAMR cell ISR activation state.The protein spectrum detection was performed by Co-immunocandemption(Co-IP)experiment with EIF2 A,and protein OAS3(2’-5’-Oligoadenylate Synthetase 3)interacting with EIF2 A in MCF7 /TAMR cells was screened.Verify whether HRI can adjust the expression of OAS3.Verify the difference in phosphorylation of estrogen receptor alpha(ERα)in MCF7 / TAMR and MCF7 cells.Verify whether HRI adjust HR + HER2-breast cancer tamoxifen resistance by EIF2 A / OAS3 / ERα pathway.Results: Analysis of GEO,showing that HRI increased in the concentration of breast cancer tamoxifen resistance data;Analysis of TCGA,METABRIC,KAPLAN-Meier Plotter,showing that HRI’s expression of breast cancer is higher than normal breast tissue,and the increase in HR + HER2-subtypes is most obvious;HR+ HER2-breast cancer patients with high HRI expression have a poor prognosis.Cox multi-factor analysis suggest that HRI high expression is its independent prognosis.After knocked down the expression of HRI of MCF7,T47 D cells with si RNA,the cell clone formation capacity and cell proliferation capacity was reduced.Silent HRI can reduce HR + HER2-breast cancer cell nude mice graft formation capacity,and Ki67 expression is inhibited.HRI expression in MCF7 / TAMR was significantly increased in m RNA and protein levels than MCF7 cells.HRI expression of MCF7 / TAMR silented by sh RNA can reverse cell tamoxifen resistance both in vivo and in vitro;WB experiments confirmed that the ISR activation levels in MCF7 / TAMR cells were higher than MCF7 cells.Silent the expression of HRI in MCF7 / TAMR cells can inhibit its ISR activation level.ISRIB increased tamoxifen sensitivity of HR + HER2-breast cancer cells.Co-IP after the protein spectrum of MCF7 / TAMR cells of EIF2 A as a bait protein confirmed that OAS3 interact with EIF2 A.The WB experiment confirmed that the expression of OAS3 was regulated by HRI.Silent OAS3 expression reversed MCF7 / TAMR cell tamoxifen resistance.Compared to MCF7 cells,ERα phosphorylation levels in MCF7 / TAMR cells were significantly higher,and ERα phosphorylation level affects the sensitivity of cells on tamoxifen.Forward and rescue experiments confirmed OAS3 can regulate HR+ HER2-breast cancer tamoxifen sensitivity by adjusting the level of ERα phosphorylation.Forward and rescue experiments confirmed HRI can regulate HR+ HER2-breast cancer tamoxifen sensitivity by EIF2 A / OAS3 / ERα pathway.Conclusions: HRI is highly expressed in HR+ HER2-breast cancer,which is related to the premature prognosis and recurrence rate of patients,and is its independent prognostic factor.HRI participates in the proliferation,cycle and apoptosis of HR+ HER2-breast cancer cells.HRI expression in MCF7 /TAMR was significantly up-regulated,and tamoxifen sensitivity can be changed with the change of HRI expression levels;it was confirmed that silentened HRI expression can reverse HR + HER2-breast cancer tamoxifen resistance in vivo and in vitro.HRI confers HR+ HER2-breast cancer tamoxifen resistance by activating ISR,and ISRIB can reverse tamoxifen resistance;HRI regulates HR+ HER2-breast cancer tamoxifen resistance by EIF2 A / OAS3 / ERα pathway.