Purpose: To study was to study the expression of CD40/CD40L in colon cancer and investigate the effects of CD40/CD40L overexpression on the proliferation and apoptosis of SW48 colon cancer cell line.
Methods: Immunohistochemistry was used to detect the expression of CD40 protein in colon cancer tissue samples from 70 patients, and 10 adjacent normal tissue samples. A CD40L gene-containing plasmid was transfected into SW48 colon cancer cells using lipofectamine 2000. Cell proliferation was measured by MTT assay. The expression of CD40/CD40L was measured by real-time PCR (RT-PCR). Protein expression of Bcl-2 and Bax was detected by Western blot.
Results: Immunohistochemical analysis showed that CD40 was mainly expressed in the cell membrane and scarcely in the cytoplasm. The expression of CD40 in colorectal cancer tissue was significantly higher than in normal adjacent tissue. RT-PCR showed that CD40 was highly expressed in SW48 cells. The expression of CD40L mRNA was significantly increased in SW40 cells transfected with the CD40L gene-containing plasmid (p<0.01). MTT assay showed that the activity of CD40L transfected cells was significantly inhibited compared with control cells transfected with empty plasmid (p<0.01). Western blot analysis demonstrated significantly decreased Bcl-2 expression, and significantly increased Bax expression in cells transfected with the CD40L gene-containing plasmid compared with the control cells (p<0.01).
Conclusion: In conclusion, CD40 protein expression was significantly higher in colon cancer tissue compared with normal tissue, and the apoptosis of SW48 colon cancer cells can be induced by CD40L gene transfection.