ZDHHC1 Trapping Of The Epidermal Growth Factor Receptor In Lipid Rafts: Potential Means By Which To Sensitize Breast Cancer Cells To Tyrosine Kinase Inhibition

OBJECTIVE: Members of the epidermal growth factor receptor(EGFR)/Erb B family are the most significant cancer molecular treatment targets.Although Erb B receptor tyrosine kinase inhibitors(TKIs)have been widely used in clinical,their breast cancer treatment efficacy is disappointing.As we all know,EGFR is located in lipid rafts on the cell surface.Its biological function is profoundly affected by cell membrane lipid metabolism and modulated by S-palmitoylation.ZDHHC1 belongs to DHHC palmitoyl-transferase family,and has been found closely related to lipid metabolism in multiple tumors.Purpose of this study is to improve the sensitivity of TKIs in breast cancer through illuminating the mechanism of ZDHHC1 mediated localization and degradation of EGFR in lipid raft.METHODS: Databases such as TCGA and UALCAN were used to analyze the expressions of STARD10 and ZDHHC1.RT-PCR and q PCR were used to verify the m RNA expressions.Biological function assays were carried out including colony formation,CCK8,flow cytometry assays,and Transwell assays.Metabolomics were evaluated by isobaric tags for relative and absolute quantitation(i TRAQ)and gas chromatography-mass spectrometry.ZDHHC1 conditional knockout mice were used to verify the effects of ZDHHC1 on STARD10 and EGFR in vivo.Immunofluorescence,Western blot,Co-immunoprecipitation,GST Pull-down,acyl-biotin exchange palmitoylation assay were performed to investigate underlying molecular mechanisms.RESULTS: We found the palmitoyl-transferase,ZDHHC1,downregulated by promotor methylation.Furthermore,ZDHHC1 was demonstrated to inhibit the malignant biological phenotype of breast cancer cells in vitro and in vivo.By i TRAQ,ZDHHC1 was shown to downregulate the lipid-associated protein,STARD10,via S-palmitoylation.As a consequence,cell membrane fluidity was reduced,trapping EGFR in lipid rafts,dimerizating EGFR and reducing autophosphorylation,which hindered downstream signaling pathway.In ZDHHC1 conditional knockout mice,ZDHHC1 deletion significantly promoted carcinogen induced breast cancer development,accompanied by upregulation of STARD10 and increased EGFR activity.In addition,we for the first time found ZDHHC1 capable of sensitizing breast cancer cells to tyrosine kinase inhibition.CONCLUSION: This study is novel for revealing ZDHHC1 is able to trap EGFR in lipid rafts,forcing ubiquitination,endocytosis,and degradation of the receptor,in a manner of downregulating STARD10.These findings provide insights into a possible new approach to breast cancer treatment.