Expression Of Lactate Dehydrogenase C4 In Breast Cancer And Its Effect On The Biological Function Of Breast Cancer Cells

Objective: 1.To study the expression of lactate dehydrogenase C4(LDH-C4)protein in breast cancer tissues and its application value in breast cancer diagnosis and treatment;2.To investigate the biological role of LDHC gene overexpression in MCF-7 cells and to discuss the molecular mechanism.Methods: 1.Immunohistochemical staining was used to detect the expression of LDH-C4 protein in 158 cases of breast cancer.The correlation between LDH-C4 and the clinicopathological characteristics such as age,clinical stage,lymph node metastasis,molecular subtyping is analyzed.Based on the established follow-up data,kaplan-meier survival analysis was conducted,and Cox model was established to analyze the relationship between different levels of LDH-C4 protein expression and breast cancer prognosis.2.The exogenous LDHC gene was introduced into MCF-7 cells by lentiviral vector,and the monoclonal cell lines with LDH-C4 positive expression were obtained.The effects of LDH-C4 overexpression on invasion,migration and proliferation of MCF-7 cells were respectively assessed;the changes of AKT/mTOR signal pathway-related proteins were detected by Western blotting.Result: 1.LDH-C4 protein staining was concentrated in the cytoplasm and presented light brown to dark brown,with a positive rate of 91.8%(145/158),among which the low expression(-/+)and high expression(++/+++)were 41.8%(66/158)and 58.2%(92/158),respectively.The patients with high expression of LDH-C4 in breast cancer had late clinical stage and high rate of axillary lymph node metastasis,which was negatively correlated with age(all with P<0.05).Kaplan-meier survival analysis showed that patients with high LDH-C4 expression in breast cancer had poor prognosis(P=0.035).Cox regression analysis showed that clinical stage(P=0.000)and LDH-C4 expression level(P=0.002)were independent prognostic factors.2.The monoclonal MCF-7 cell line of breast cancer with LDH-C4 overexpression was successfully obtained by lentivirus infection.Through the cytological experiments such as plate cloning formation,CCK-8 proliferation coloration,scratch repair,matrix adhesive Transwell chamber,the preliminary results showed that the overexpression of LDH-C4 could enhance the invasion and migration of breast cancer MCF-7 cells,but has no significant effect on cell proliferation.The expression of AKT and mTOR are up-regulated in MCF-7 cells in response to overexpression of LDH-C4.Conclusions: 1.LDH-C4 is highly expressed and is associated with clinical staging,axillary lymph node metastasis in patients with breast cancer.High expression level of LDH-C4 predicts a poor prognosis.2.Overexpression of LDH-C4 can enhance the invasion,migration and proliferation of MCF-7 cells,and the mechanism may be related to the activation of AKT/mTOR signaling pathway.