Mesothelioma cell lines with and without β-catenin gene expression were transfected with Dvl-3 siRNA and were cultured with gefitinib, and cell viability, colony formation and cell cycle analyses were performed.
Furthermore, overexpression of let 7b using let-7b mimics enhanced the antitumor effect of ursolic acid to attenuate the expression of procaspases 3, pro-PARP, pAKT, β-catenin and Twist and increase sub-G1 accumulation in H2452 mesothelioma cells.
We studied 109 malignant mesotheliomas (58 epithelioid, 26 sarcomatoid, and 25 biphasic) by immunohistochemistry and qRT-PCR analysis, and demonstrated a substantial switch from epithelial markers (E-cadherin, β-catenin, and cytokeratins 5/6) to mesenchymal markers (N-cadherin, vimentin, α-smooth muscle actin, Snail, Slug, Twist, ZEB1, ZEB2, S100A4, MMP2, and MMP9) through epithelioid to biphasic and sarcomatoid histotypes.
Our results suggest that methylation silencing of SFRP4 may play an important role in aberrant Wnt activation in mesothelioma even in the absence of beta-catenin.
In conclusion, our data indicate that inactivation of beta-catenin by a 3p21.3 homozygous deletion might be a crucial event in the development of the mesothelioma NCI-H28 cells.
Furthermore, Northern blot analysis of 26 lung cancer and eight mesothelioma cell line RNAs detected ubiquitous expression of the beta-catenin messages except NCI-H28, although Western blot analysis showed that relatively less amounts of protein products were expressed in some of lung cancer cell lines.
Deletion of most beta-catenin coding exons was confirmed in line NCI-H28 (lung mesothelioma) and a silent mutation at codon 214 in exon 5 was found in HeLa (cervical adenocarcinoma).
Furthermore, we identified a homozygous deletion of beta-catenin in the mesothelioma, NCI-H28, associated with reduced WNT7a and the lowest overall cell line expression of HOXA1, HOXA7, HOXA9, and HOXA10, whereas HOXB9 levels were unaffected.