In conclusion, targeting CBP/β-catenin, combined with PD-1/PD-L1 immune checkpoint blockade, shows potential as a new therapeutic strategy for treating liver metastasis during colon cancer.
A discordant pattern of β-catenin and E-cadherin expression between pPDC and cPDC, between main tumor and cPDC, and between primary CRC and LM, confirms that EMT is a dynamic and reversible process in CRC.
In both Groups, we found a common "basal" condition with a higher level of nuclear TWIST1 (<i>p</i><0.0001 and cytoplasmic β-catenin (<i>p</i><0.0001) in tumors than in paired liver metastases.
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 tumor tissues, β-catenin was predominantly associated with NHERF1 in a dynamic context, while interestingly in liver metastases, we noted an increase of its oncogenic function through RASSF1A inactivation.
Previously, we identified the neural immunoglobulin-like adhesion receptor L1 as a Wnt/β-catenin target gene localized in cells at the invasive front of CRC tissue and showed that L1 expression in CRC cells confers enhanced motility and liver metastasis.
Here we show that, in HT29 colon carcinoma cells, silencing of c-Yes, but not of c-Src, selectively leads to an increase of cell clustering associated with a localisation of β-catenin at cell membranes and a reduction of expression of β-catenin target genes. c-Yes silencing induced an increase in apoptosis, inhibition of growth in soft-agar and in mouse xenografts, inhibition of cell migration and loss of the capacity to generate liver metastases in mice.
When we considered the expression of both genes, the combination of negative beta-catenin and positive p53 nuclear staining (21%) was strongly related to a higher frequency of liver metastases.
The seven cases with nuclear accumulation of beta-catenin were large tumours (mean size 44 (standard deviation (SD) 18.5) mm) with metastases, including liver metastases in five cases, high Ki-67 index (mean 34% (SD 16.5%)) and cyclin D1 overexpression; p53 accumulation was detected in six cases.
The concomitant increase in beta-catenin expression and the amount of uPAR was confirmed in primary colon carcinomas and their liver metastases at both the mRNA and the protein levels.
The expression of alpha- and beta-catenin in comparison with E-cadherin was therefore examined in colorectal adenomas and carcinomas and in lymph node and liver metastases.