RUNX2 Facilitates Aggressiveness And Chemoresistance Of Triple Negative Breast Cancer Cells Via Activating MMP1

Background and ObjectiveBreast cancer(BC)is a malignant tumor that seriously endangers human health.The latest cancer research survey shows that the incidence of breast cancer has surpassed lung cancer and become the first major cancer in the world.Breast cancer is highly heterogeneous,and the clinical treatment and prognosis of different patients vary greatly.BC can be divided into different molecular subtypes according to the different expression of surface receptors on breast cancer cells.Triple negative breast cancer(TNBC)is named because of the lack of three cell surface receptors,and has been widely concerned because of its clinical characteristics such as strong invasion,high metastatic potential and poor clinical prognosis.RUNX2 is a transcription factor that regulates osteocytes and chondrocytes,and normally contributes to bone tissue remodeling and chondrogenic differentiation.In recent years,a large number of studies have found that RUNX2 expression is closely related to the occurrence and development of a variety of cancers,such as osteosarcoma,gastric cancer,breast cancer,prostate cancer and so on.The high expression of RUNX2 is closely related to the bone metastasis of cancer.Our preliminary data found that the expression of RUNX2 in TNBC cells was higher than that in other types of breast cancer cells,which may be related to the high metastasis of TNBC.Then,we established a drug resistant cell line of TNBC cells and found that the drug resistant cells were more metastasis.However,the molecular mechanism of RUNX2 and TNBC metastasis and drug resistance is still unclear.Therefore,it is of great significance to explore the molecular mechanism of RUNX2 in promoting cell metastasis and drug resistance in TNBC,and to provide new targets for clinical treatment of TNBC.Research contents and methods1.Effect of knockdown of RUNX2 on drug resistant TNBC cells:(1)In vitro: Transwell assay was used to detect the migration and invasion ability of cells;q RT-PCR and Western blot were used to detect EMT-related markers;plate clone formation assay was used to detect cells clone formation ability;Soft agar colony formation assay was used to detect the non-anchored growth ability of cells;CCK-8 cytotoxicity assay was used to detect cells drug resistance.(2)In vivo: The cell metastasis in vivo was detected by caudal intravenous injection assay in BALB/c nude mice.The growth size,rate and chemoresistance of tumor in vivo were detect by subcutaneous tumor formation assay in BALB/c nude mice.2.The key genes were screened by RNA sequencing: RNA sequencing was used to explore the differentially expressed genes(DEGs)in drug resistant cells with differential expression of RUNX2,and the functions and signaling pathways of the DEGs were analyzed to screen the key genes.3.The key gene MMP1 was analyzed in the database: TCGA database and UALCAN database were used to analyze the expression of MMP1 in breast cancer and normal tissues,and its expression in different types of breast cancer;Kaplan-Meier Plotter database was used to analyze the relationship between MMP1 and overall survival(OS),relapse free survival(RFS)and distant metastasis free survival(DMFS)of breast cancer patients.4.Exploration of the molecular mechanism between RUNX2 and MMP1: The correlation between RUNX2 and MMP1 was detected by q RT-PCR,Western blot and immunohistochemistry;Whether RUNX2 directly targets MMP1 was determined by Ch IP-q RT-PCR.Results1.Knockdown of RUNX2 inhibited the migration,invasion,proliferation and drug resistance of drug resistant TNBC cells.2.Knockdown of RUNX2 inhibited the metastasis,growth size,rate and chemoresistance of drug resistant TNBC cells in vivo.3.MMP1 is highly expressed in TNBC and is associated with poor prognosis of patients.4.RUNX2 facilitates aggressiveness and chemoresistance of TNBC cells by directly targeting the MMP1 promoter region.ConclusionIn TNBC cells,RUNX2 facilitates aggressiveness and chemoresistance of drug resistant cells,which may play a tumor-promoting role by directly targeting the MMP1 promoter region.