The Effect Of 4-hydroxytamoxifen On Gene Expression Profile Of Breast Cancer Cell And Mechanism Of 4-hydroxytamoxifen Inhibiting Breast Cancer Progression

Breast cancer is the second most common cause of cancer-related death among women in the world.Endocrine therapy represented by tamoxifen(TAM)is one of the most effective treatments for estrogen receptor-positive(ER+)breast cancer.However anti-breast cancer mechanisms of TAM are not completely elucidated.Based on the fact that C-X-C motif chemokine ligand eight(CXCL8)plays an important role in the formation and development of tumor,this study assessed the m RNA level of CXCL8 in breast cancer tissues and analyzed relationship between its level and the clinicopathological characteristics with patients/the overall survival(OS)for 10 years.We found that CXCL8 level was higher in ER-negative(ER?)breast cancer tissues and higher CXCL8 m RNA level(?3.095)together with ER? was associated with significantly shorter OS.In order to know whether TAM affects CXCL8 expression and the possible mechanism of TAM inhibiting breast cancer progress,the effect of 4-hydroxy-tamoxifen(4-OH-TAM)on gene expression profile was performed in breast cancer cell.The results showed the CXCL8 expression was not affected by 4-OH-TAM treatment in ER+ breast cancer cells(MCF-7)and ER?breast cancer cells(MDA-MB-468 and MDA-MB-231).Further study indicated that 652 genes,including 332 genes up-regulated and 320 genes down-regulated were influenced significantly by 4-OH-TAM in MCF-7 cells.The m RNA levels of up-regulated genes including STAT1,STAT2,EIF2AK2,TGM2,DDX58,PARP9,SASH1,RBL2 and USP18 as well as down-regulated genes including CCDN1,S100A9,S100A8,ANXA1,PGR,KNL1,SGK494,DBF4 B,DSCC1,FAM102 B,GINS3,KLHL7,KNSTRN,MRPL1,MRPS28,MRTO4,MTFR2,MYO19,NCAPH,POLA2,PPIH,RPS14,SPDL1,TIFA and TESC were confirmed by quantitative real-time PCR(q RT-PCR).Total genes mentioned above are involved in regulation of cell proliferation,apoptosis,cell cycles,and estrogen and interferon signal pathways.In subsequent studies,high content screening(HCS)was used to investigate the effect of 20 genes silenced by RNA interference(RNAi)on the proliferation rates of MCF-7 cells.The results showed that RPS14 gene has the most obvious effect on proliferation inhibition.After RNAi of RPS14 in MCF-7 cell,cell proliferation decreased and apoptotic cells increased significantly,accompanied by cell numbers decreased in S phase,increased in G1 and G2/M phase,which suggested RPS14 might be associated with cell cycle of MCF-7.In summary,CXCL8 is negative correlated with overall survival of breast cancer patients,but it is not a direct target gene of 4-OH-TAM.Genes affected by TAM in breast cancer cells were involved in regulation of cell proliferation,apoptosis,cell cycle,and estrogen and interferon signal pathways.TAM may inhibit the proliferation of breast cancer cells by down-regulating the RPS14 gene.This study has paved a foundation for elucidating TAM anti-breast cancer mechanisms in E2/ER-dependent and independent pathways.