| BACKGROUND:Lung cancer is the major cause of malignancy-related death worldwide, and its incidence is rising in many countries[1]. In advanced lung cancer, metastatic deposits to bones are common. It is estimated that more than 35% of patients with advanced lung cancer manifest bone metastases, while, at autopsies, up to 50% of lung cancer patients have evidence of skeletal metastasis[2]. Bone metastasis is one of the most severe complications of lung cancer, which cause pain, pathologic fractures, spinal cord compression, and hypercalcemia[3]. Currently, clinical management is generally palliative. Therefore, it is obviously important to explore new methods to prevent and treat osteolytic bone metastasis. Several preclinical experiments showed thatβ3-integrin antagonists were able to block tumor growth in bone and to inhibit bone resorption with breast cancer cells[4-6], suggestingβ3-integrin as a therapeutic target for the prevention of skeletal metastases.OBJECTIVE : Although accumulating evidences have showed thatβ3-integrin is essential for tumor bone metastases, its role in human small cell lung cancer cells has not been elucidated. Based on the cell lines: SBC-5,SBC-3, we investigated the expression and role ofβ3-integrin, aiming to study the mechanism of bone metastasis in lung cancer.METHODS:We firstly compared the expression ofβ3-integrin between the two kinds of cells by RT-PCR, Western blotting and Immunofluoresence, and we found that the expression ofβ3-integrin was markedly increased in the high bone metastatic SBC-5 cells. Further study using siRNA technique, the expression ofβ3-integrin was suppressed in SBC-5 cells. Through MTT assay, colony formation assay, apoptotic assay, adherent assay, migration and invasion assay, we study the effect ofβ3-integrin in bone metastasic cell line.RESULTS:(1)the expression ofβ3-integrin in two cell lines The PCR and Western bloting results showed thatβ3-integrin was significantly overexpressed in SBC-5 cells as compared with SBC-3 cells. Through using Immunofluoresence, strong staining ofβ3-integrin was observed in both membrane and cytoplasm in SBC-5 cells. Conversely, only low staining was observed in SBC-3 cells. (2)the effect ofβ3-integrin in tumor cell proliferation and metastasis In MTT assay, the proliferation of siRNA transfected cells was significantly lower than control cells (P<0.01). In colony formation assay, the number of colonies was different in siRNA transfected SBC-5 and mock cells (P<0.05). The number of apoptotic cells of siRNA transfected SBC-5 was significantly higher compared to mock cells (P<0.001). As time extending, the number of adherent cells of two cell lines increased, and the number of adherent cells of siRNA transfected SBC-5 was significantly lower compared to mock cells. In uncoated transwells experiments, siRNA transfected SBC-5 cells decreased migration compared with mock cells (P<001). The invasion of siRNA transfected SBC-5 cells transfected cells also decreased compared with control-transfected cells by detecting with matrigel coated transwells (P<0.001).CONCLUSION:β3-integrin was expressed in highly bone metastatic SBC-5 cells at a significantly higher level than in none bone metastatic SBC-3 cells.β3-integrin maybe have positive correlation with bone metastasis of small cell lung cancer. Through affect cell proliferation, migration and invasive activity,β3-integrin maybe take part in the process in bone metastasis of small cell lung cancer, and maybe a potential therapeutic approach for the prevention of skeletal metastases of lung cancer. |
PDF Full Text Request