Effects of γ-synuclein on the tumorigenicity and metastasis of colon cancer SW1116 cells in vitro and in vivo

Abstract

Recent evidence suggests the involvement of γ-synuclein in tumorigenesis and tumor progression. The present study was designed to further clarify the effects of γ-synuclein on the biological features of colon cancer cells in vitro and in vivo. We constructed the eukaryotic expression vector and siRNA vector and selected stable transfectants to respectively upregulate and downregulate γ-synuclein expression in SW1116 cells. We found that silencing of γ-synuclein significantly attenuated SW1116 cell growth and colony formation in vitro (P<0.05), and overexpression of γ-synuclein moderately enhanced cell growth and colony formation, but not significantly when compared with the parental SW1116 cells and empty vector-transfected cells (P>0.05). Meanwhile, overexpression of γ-synuclein significantly facilitated SW1116 cell migration, invasion and adhesion to human liver sinusoidal endothelial cells (HLSECs) in vitro (P<0.05), and the effects were less attenuated by γ-synuclein knockdown (P>0.05). Furthermore, γ-synuclein promoted these malignant phenotypes in a γ-synuclein expression quantity-dependent manner not only in vitro but also in the in vivo expression. Stable cells were injected subcutaneously into the right flank, and injected intrasplenically in nude mice. γ-synuclein knockdown suppressed the tumorigenicity of SW1116 cells in mice, which presented significantly smaller tumor masses on day 6 over a 30-day period, compared with empty vector cells (P<0.05). Meanwhile, overexpression of γ-synuclein led to a profound augmentation of liver metastasis in nude mice, not only in macroscopic appearance but also in the size and weight of livers (P<0.05). These results provide strong evidence that suggests γ-synuclein plays a positive role in the progression of colorectal cancer.