Overexpression of regenerating islet-derived 1 alpha and 3 alpha genes in human primary liver tumors with β-catenin mutations

Abstract

The Wnt/b-catenin signaling pathway is activated in many human hepatocellular carcinomas (HCC). We tried to identify the genes involved in carcinogenesis and progression of HCC with b-catenin mutations. We used PCRbased subtractive hybridization to compare gene expression between malignant and benign components of a human HCC occurring in pre-existing adenoma activated for b-catenin. Two of the genes identified belong to the Regenerating gene (REG) family. They encode the Regenerating islet-derived 3 alpha (REG3A/HIP/PAP/ REG-III) and 1 alpha (REG1A) proteins, both involved in liver and pancreatic regeneration and proliferation. Using siRNA directed against b-catenin, we demonstrated that REG3A is a target of b-catenin signaling in Huh7 hepatoma cells. The upregulation of REG3A and REG1A expression is significantly correlated to the b-catenin status in 42 HCC and 28 hepatoblastomas characterized for their b-catenin status. Thus, we report strong evidence that both genes are downstream targets of the Wnt pathway during liver tumorigenesis.

TP63 P2 promoter functional analysis identifies β-catenin as a key regulator of ΔNp63 expression

“…Plasmids and mutagenesis DNp63a, DN89 b-catenin mutant and DNTCF4-expression vectors have been previously described Cavard et al, 2006;Petitjean et al, 2008). pCMV-p53-expression vector was from Clontech (Mountain View, CA, USA).…”

Expression of Reg Family Proteins in Embryonic Stem Cells and Its Modulation by Wnt/β-Catenin Signaling

“…Enhanced levels of the human Reg3A (also known as pancreatitis-associated protein (PAP)) and Reg1α were discovered in primary liver tumors with β-catenin mutations suggesting a possible regulation of these Reg genes by the canonical Wnt/β-catenin signaling pathway [ 17 ]. A strong association between β-catenin mutations and changes in the expression of Reg genes was also documented in a recent clinical study involving biopsy samples from patients with liver cancer [ 18 ].…”

“…Previous studies indicated a possible link between Wnt/ β-catenin signal transduction and the expression of Reg proteins in cancer cells [ 17,18 ]. Before examining if such a link exists in mESCs, we defi ned conditions under which the canonical Wnt pathway can be activated in our mESC lines.…”

“…We hypothesized that a link exists between the expression of Reg proteins and Wnt/β-catenin signaling in mESCs as suggested for other cell types [ 17,18 ]. To test our hypothesis, we implemented the experimental conditions described in the previous paragraph for the activation of the canonical Wnt pathway in mESCs.…”

“…Reverse transcription was performed using the ImProm-II reverse transcriptase (Promega, Madison, WI) with 1 μg of total RNA and 250 ng random primers or oligo(dT) [12][13][14][15][16][17][18] primers at 42°C for 60 min. PCR runs were carried out with the resulting cDNA for 30-35 cycles at an annealing temperature of 58°C-60°C depending on the primer set.…”