Expression Of LPAR4 In Breast Cancer And Effects Of RNAi Silencing LPAR4 On Tumor Invasion And Migration Of MDA-MB-231 Cells

Research background and aim:Breast cancer is the most common cancer in women worldwide,and has risen to the first cause of death in women in recent years.Since the late 1990 s,the treatment of breast cancer has gradually developed from traditional treatments to personalized comprehensive treatments,and made great clinical achievements.Among all treatments available,molecular targeted therapy has become a hot topic of cancer studies nowadays,and molecular targeted therapy of breast cancer has also been carried out and preliminarily achieved remarkable results.However,the 5-year survival rate of invasive breast cancer and metastatic breast cancer is still poor mainly due to its intensive tendency of invasion and metastasis.Therefore,understanding the biological mechanism of breast cancer invasion and metastasis is vital for finding new therapeutic targets to improve the therapeutic effect and prognosis of breast cancer.Lysophosphatidic acid(LPA)is a water soluble glycerophospholipid functioning as a signal molecule,which acts through six different G protein-coupled receptors(LPAR1-6)to regulate the body’s development and maintain normal physiological function,and is also involved in a number of pathological processes,such as nerve pain,cardiovascular disease,inflammation and tumors.In recent years,it has been found that LPA and its receptors are related to the occurrence and development of breast cancer and may be a new target for cancer therapy.In this study,we attempted to evaluate the differential expression and corresponding effects of LPAR4 in different subtypes of breast cancer,and studied the signaling pathways of LPAR4-induced breast cancer cell invasion and the mechanism of curcumin in inhibiting breast cancer cell invasion.Methods:Western blot was used to detect the expression of LPAR4 in MDA-MB-231,MCF-7,MCF-10 A cells.Using immunohistochemical technique to investigate the LPAR4 protein in human breast cancers and para-carcinoma tissue,and analyze the relationship between LPAR4 expression and clinical pathological features.RNA i was used to suppress the expression of LPAR4,Transwell migration assay used to test the ability of migration and invasion,then we used western blot to analyze the change of YAP after gene silencing.Results: 1.Two human BC cell lines(MDA-MB-231 and MCF-7)and normal epithelial cells(MCF-10A)were used to detected the expression of LPAR4.The results revealed that LPAR4 protein expression showed a significantly higher in BC cells than normal epithelial cel s.(P<0.05).2.Immunohistochemical was used to detected the expression of LPAR4 in 45 BC specimens and 40 corresponding non-tumor tissues.The results showed that LPAR4 was strongly detected in BC specimens,the positive rates are significantly higher than that in others(P<0.05)and LPAR4 expression correlated with differentiation and TNM stage(P<0.05),while showed no statistically significant among the association of age and lymph node metastasis.3.RNAi was used to suppress the expression of LPAR4,Western Blot assay showed the protein levels of LPAR4 was obvious decreased.Transwell migration assay showed that the migration and invasion ability of cells after transfected with RNAi-LPAR4 was obvious reduced than those trans fected with RNAi-controls(P<0.05).Meanwhile,we used western blot to test the expression of MMP2 与 MMP9 in MDA-MB-231 cells that transfected RNAi-LPAR4.The results showed that the leaves of MMP2 and MMP9 were all reduced.Conclusion: 1.LPAR4 is highly expressed in patients with BC,the higher positive expression of LPAR4 was correlation with TNM Stages and Histologic differentiation.2.Down-regulation of LPAR4 can suppress tumor invasion and migration and associate with MMP2 and MMP9 expression.This will provide a direction for studying the specific mechanism of LPAR4 in malignancy metastasis.