Functions Of TGFBI In The Bone Metastasis Of Breast Cancer In Mice

Breast cancer is the most common cancer and the leading cause of cancer death in women.Of all the causes in cancer death,metastasis is the biggest one.As we know,lung metastases,brain metastases and bone metastases are the three most common metastases of breast cancer.Increased expression of TGFBI was observed in bone metastasis models of prostate cancer and kidney cancer;however,the specific function and related mechanism of TGFBI in the bone metastasis of breast cancer remain unclear.In this study,we focused on functions of TGFBI in bone metastasis of mouse breast cancer.The model that breast cancer cells were injected into the left ventricle of female Balb/c mice and the model that breast cancer cells were directly injected into the tibias were used to simulate the bone metastasis of mouse breast cancer in our study.We injected mouse breast cancer cell line 4T1 into the left ventricle of female Balb/c mice,and found that the expression of TGFBI in bone matastases of mice was significantly higher than that of control mice.In the second model that TGFBI-overexpressing 4T1 cells were directly injected into the tibias,we found that overexpression of TGFBI could induce 4T1 cells to outgrow in the primary site,promote 4T1 cells to metastasize from tibia to femur and aggravate the femur injury.Moreover,overexpression of TGFBI could effectively promote proliferation,adhesion,invasion and migration of 4T1 cells,and increase the differenciation of osteoclasts.Therefore,our results showed that the expression of TGFBI is high in bone metastases of mouse breast cancer,and that overexpression of TGFBI can not only promote adhesion,invasion and proliferation of breast cancer cells,but also promote bone metastasis of breast cancer cells.This study will help us to further elucidate the mechanisms of TGFBI in bone metastasis of mouse breast cancer.