The expression of β‑catenin in the Wnt signaling pathway was lower in SK‑BR‑3 cells compared with in MDA‑MB‑231 cells, which may be used as a prognostic indicator for breast cancer.
Furthermore, we demonstrate that breast cancer cells that harbor activated beta-catenin activity exhibit enhanced sensitivity to pharmacological blockade of Wnt/beta-catenin signaling.
Here we identify β-catenin and Rad6B interacting regions, identify potential Rad6B ubiquitination sites in β-catenin, and characterize their breast cancer tissue expression.
Potential role of this gene was studied in a radiation- and estrogen breast cancer model by analyzing differential expression of associated genes of β-catenin as E-cadherin and catenins.
Given the low frequency of mutation-induced activation of beta-catenin in prostate and breast cancers, proteolytic cleavage of beta-catenin by calpain may represent a novel mechanism by which the protein is activated during tumorigenesis.
Furthermore, we show that Ron overexpression leads to receptor phosphorylation and is associated with elevated levels of tyrosine phosphorylated beta-catenin and the up-regulation of genes, including cyclin D1 and c-myc, which are associated with poor prognosis in patients with human breast cancers.
Importantly, in a series of breast cancer specimens, we found strong correlation among E-cadherin expression, β-catenin expression, and the lymph node metastatic potential of breast cancer.
These findings show for the first time that adriamycin can induce E-cadherin-mediated cell-cell adhesion by increasing expression of E-cadherin and beta-catenin and decreasing expression of MUC1 during breast cancer cell apoptosis induced by this drug.
To conclude, our results support the concept that STAT3 upregulates the protein expression and transcriptional activity of β-catenin in breast cancer, and these two proteins may cooperate with each other in exerting their oncogenic effects in these tumors.
However, the overexpression of XCR1 in human breast cancer cell line MDA-MB-231 in vitro can promote the migration and invasion partially due to decreasing the protein level of β-catenin.
It also protects against neural and breast cancers by suppressing the expression of matrix metalloproteinase (MMP)-9 and MMP-7 and inhibiting enzymatic activity, metastatic potential, and activation of the β-catenin pathway.
It was also demonstrated that DACT2 is a tumor suppressor in breast cancer and inhibits the proliferation and invasion of breast cancer cells by repressing the expression of β-catenin target genes associated with tumor growth and metastasis.
Based on the statistical analyses, we speculated that reduced expression of APC leads to overexpression of beta-catenin, and aberrant expression of cyclin D1 and c-myc mainly depends on alterations in the Wnt signaling pathway in breast cancer.
Up-regulation of WNT2 mRNA by estrogen might play a key role in some cases of human breast cancer through activation of the beta-catenin - TCF signaling pathway.
In addition, the expression of β-catenin activated targets including c-Jun, c-Myc, Cyclin D1 and CD44 were also decreased by panobinostat treatment in breast cancer cells.
Finally, miR-107 could further reduce the decreased expression of TPD52, Wnt1, β-catenin and cyclin D1 that was induced by PTX in both mRNA and protein levels, which were rescued by pcDNA3.1-TPD52 indicating that miR-107 regulated breast cancer cell sensitivity to PTX may be targeting TPD52 through Wnt/β-catenin signaling pathway.
These observations argue that the balance of junctional and nuclear β-catenin activity has a profound impact on tumor progression in this basal model of ErbB2-positive breast cancer.
The results of qPCR showed that baicalin increase the expression of E-cadherin mRNA, and decrease the expression of vimentin, β-catenin, c-Myc and MMP-7 mRNA in LPS-induced breast cancer MDA-MB-231 cells (P < 0.05).
Thus, Pin1 is a novel regulator of beta-catenin signalling and its overexpression might contribute to the upregulation of beta-catenin in tumours such as breast cancer, in which APC or beta-catenin mutations are not common.