The Effect Of HA-CD44st-TGF-? Signaling Pathway On The Invasion Capability Of MCF-7 Cells

Background and Objective Breast cancer is the most common in female malignant tumors,and its high invasiveness and high metastasis have always attracted people's attention.CD44 st is a member of the CD44 family of Hyaluronan(HA)receptor,which is expressed on surface of many tumor cells.CD44 st can regulate a variety of biological processes when it bind to its ligand HA.Studies have found that HA-CD44 st plays an important role in the invasion and metastasis of breast cancer,but the specific mechanism still needs to be further explored.Transforming growth factor-?(TGF-?)is a newly discovered TGF-? superfamily,which plays an important role in regulating cell proliferation,differentiation and metastasis.Because of its extensive and important biological functions,its signaling pathway has become one of the research hotspots in many fields.PI3K/AKT is an important signaling pathway downstream of TGF-? and plays an important role in promoting the invasion and metastasis of tumor cells.Meanwhile,studies have reported that TGF-? is one of the target proteins in the HA-CD44 signaling pathway.Therefore,it is necessary to study the effect of the HA-CD44 st on the expression of TGF-?,as well as how the HA-CD44 st affects the activity of the downstream PI3K/AKT pathway,and to explore the effect of the above process on tumor cell invasiveness,which aims to provide a theoretical basis for the development of molecular therapy targeting CD44 st and TGF-?.Method The eukaryotic expression vector pc DNA3.1-CD44 st was transfected into MCF-7 cells by Lipofectamine 2000,which was used to explored the effect of HA-CD44st?TGF-??PI3K signaling pathway on the invasion capability of MCF-7cells.The expression of CD44 st m RNA and TGF-? m RNA were detected with the method of Reverse Transcriptase Polymerase(RT-PCR),while the expression of CD44?TGF-??AKT and p-AKT proteins were detected with the method of Western blot and Flow cytometry.The activity of transcription factor AP-1 binding to DNA and the effect of pathway activation on the invasion of MCF-7 cells were tested with electrophoretic mobility shift assays and transwell assay,respectively.Result The CD44 st m RNA and CD44 protein were detected expression highly in MCF-7 cells transfected with pc DNA3.1-CD44 st.After treatment with HA,the expression of TGF-? in MCF-7 /CD44 st cells was significantly increased,along with the expression of downstream signaling molecule p-AKT.EMSA showed that MCF-7/CD44 st cells with HA treatment could significantly enhance the activity of transcription factor AP-1 binding to DNA,which could be effectively inhibited by CD44 blocking monoclonal antibody and PI3 K signaling pathway inhibitors.Transwell invasion assay showed that HA could up-regulate the invasion ability of MCF-7/CD44 st cells by activating the CD44st?TGF-??PI3K signaling pathway.Conclusion Binding of HA to the CD44 st receptor may regulate the invasiveness of MCF-7 cells through the CD44st?TGF??PI3K?AP-1 signaling pathway.