Using our data set (GSE50760) previously established by
RNA sequencing, the present study aimed to identify upregulated genes associated with
colorectal cancer (CRC) liver
metastasis (CLM) and verify their biological behavior. The potential roles of candidate genes in
tumors were assessed using cell proliferation and invasion assays. Tissue samples were collected from 18 CRC patients with synchronous CLM and two CRC cell lines (SW480 and SW620) were used for transfection and cloning. The roles of the genes identified in CLM were verified using immunohistochemistry in 48 nude mice after intrasplenic
transplantation of CRC cells.
mRNA and
protein expression was determined by quantitative real-time reverse transcription polymerase chain reaction and western blot, respectively. Nine genes were initially selected according to the relevance of their molecular function and biological process and, finally, ALDH1A1 and IGFBP1 were chosen based on differential
mRNA expression and a positive correlation with
protein expression. The overexpression of ALDH1A1 and IGFBP1 significantly and time-dependently decreased cell proliferation (p ≤ 0.001-0.003) and suppressed invasiveness by ≥3-fold over control cells (p < 0.001) in the SW480 cell line, whereas they had a slight effect on reducing SW620 cell proliferation. The
protein expression levels of
E-cadherin,
N-cadherin,
claudin-1, and
vimentin were significantly higher in CLM than in primary
tumor tissues (p < 0.05). However, the
cadherin switch, namely,
N-cadherin overexpression with reduced
E-cadherin expression, was not observed in CLM tissues and transfected CRC cells. Irrespective of reduced proliferation and invasion found on in vitro cell assays, persistent overexpression of β-
catenin,
vimentin, and ZO-1 in IGFBP1-overexpressing SW480 cells possibly contributed to CLM development in mice implanted with IGFBP1-overexpressing SW480 cells (CLM occurrences: SW480/IGFBP1-transfected mice vs. SW480/vector- and SW480/ALDH1A1-transfected mice, 4/8 vs. 0/10, p = 0.023). In conclusion, ALDH1A1 and IGFBP1 are differentially overexpressed in CLM and may play a dual role, functioning as both
tumor suppressors and
metastasis promoters in CRC.