Effects Of FLT4 On Colorectal Cancer Cell Metastasis And Its Molecular Mechanism

Recent epidemiological studies indicate that the incidence and mortality rates of colorectal cancer in the world are rising,with the incidence rate of colorectal cancer in 2020 next to lung cancer,and the mortality rate ranked third.Cancer metastasis is the main cause of death,so it is urgent to study the molecular mechanism of colorectal cancer metastasis and explore new approaches to inhibit colorectal cancer metastasis.Our group’s previous study found that Genistein had anti-metastasis activity in colorectal cancer,and might play its role through inhibiting FLT4 and MMP2.Based on this,we focused on the role and molecular mechanism of FLT4 in regulating colorectal cancer metastasis.Four colorectal cancer cell lines,HCT116,HT29,SW620 and SW480,were used in our study.First,we constructed FLT4 stably knock down cell lines in four types of colorectal cancer.We then investigated whether knocking down FLT4 affects the biological function of colorectal cancer cells.Using CCK-8 assay,we found that after knocking-down FLT4 gene,the proliferation of four colorectal cancer cell lines decreased.We then used flow cytometry to detect apoptosis in colorectal cancer cell lines with FLT4 knock-down,the results indicated that FLT4 knock-down did not affect the apoptosis of colorectal cancer cells.Next,several functional assays were applied to study the effects of FLT4.By cell scratch assay,Transwell migration assay and Transwell invasion assay,we demonstrated that FLT4 gene knock-down inhibited the migration and invasion of colorectal cancer cells.Based on the results of our biological function experiments,we investigated the molecular mechanism of FLT4 gene in colorectal cancer cell lines.Western Blot was used to detect the expression of p-ERK,ERK,p-p38 and p38 in FLT4 knock-down colorectal cancer cells.We found that,though the ratio of p-ERK to ERK and of pp38 to p38 did not change significantly in FLT4 knock-down stable cells,the expression level of p-ERK and ERK decreased.Further studies are needed to test if FLT4 exerts its effects on colorectal cancer through ERK pathway directly or indirectly.In addition,the expression of Fibronectin and Vimentin in colorectal cancer cell lines with FLT4 knock-down was significantly decreased,indicating that FLT4 knock-down affected EMT process in colorectal cancer cells.