Transient but not stable ZEB1 knockdown dramatically inhibits growth of malignant pleural mesothelioma cells.

BACKGROUND: The role of ZEB1, a master epithelial-to-mesenchymal transition gene, in malignant pleural mesothelioma (MPM) is unclear. METHODS: The expression of ZEB1, E-cadherin, vimentin, and epithelial cell adhesion molecule (EpCAM) in 18 MPM cell lines and a normal pleural mesothelial cell line MeT-5A was determined by quantitative real-time polymerase chain reaction and Western blot testing. RNA interference-mediated transient and/or stable knockdown of ZEB1 and EpCAM was performed. Microarray expression analysis was performed with a TORAY-3D gene chip. Growth was evaluated by colorimetric proliferation and colony formation assays. Luciferase reporter assay was performed to access the effects of ZEB1 knockdown on EpCAM promoter activity. RESULTS: Most MPM cell lines exhibited mesenchymal phenotype and expressed ZEB1. Transient ZEB1 knockdown suppressed growth in all four cell lines studied (ACC-MESO-1, H2052, Y-MESO-8A, Y-MESO-29) while stable ZEB1 knockdown suppressed growth only in Y-MESO-29. Genome-wide gene expression analysis revealed that EpCAM was the most prominently up-regulated gene by both transient and stable ZEB1 knockdown in ACC-MESO-1, with more marked up-regulation in stable knockdown. We hypothesized that EpCAM up-regulation counteracts the stable ZEB1 knockdown-induced growth inhibition in ACC-MESO-1. Transient EpCAM knockdown suppressed growth dramatically in ACC-MESO-1 cells expressing shZEB1 but only modestly in those expressing shGFP, supporting our hypothesis. Luciferase reporter assay showed that ZEB1 knockdown resulted in increased EpCAM promoter activity. EpCAM was also up-regulated in Y-MESO-29 expressing shZEB1, but this EpCAM up-regulation did not counteract ZEB1knockdown-induced growth suppression, suggesting that the counteracting effects of EpCAM may be cellular context dependent. CONCLUSIONS: RNA interference-mediated ZEB1 knockdown may be a promising therapeutic strategy for MPM, but one has to consider the possibility of diminished growth inhibitory effects of long-term ZEB1 knockdown, possibly as a result of EpCAM up-regulation and/or other gene expression changes resulting from ZEB1 knockdown.

Genetic polymorphisms of the adenosine triphosphate-binding cassette transporters (ABCG2, ABCB1) and gefitinib toxicity.

The purpose of this study is to investigate associations between allelic variations of ABCG2 and ABCB1 with skin toxicity, diarrhea, liver injury and interstitial lung disease (ILD) in gefitinib-treated patients. A prospective clinical study of 83 Japanese patients with non-small-cell lung cancer was performed. Polymorphic loci in ABCG2 and ABCB1 were genotyped, and their effects on gefitinib toxicities were evaluated. ABCG2 34G>A was statistically associated with occurrence of skin rash; 13 (42%) of the 32 patients with at least one variant ABCG2 34G>A allele (G/A and A/A) developed grade 2 or worse skin rash, whereas only 10 (19%) of 51 patients homozygous for the reference allele (G/G) for the wild-type sequence for both alleles did so (P=0.046). There was no significant association between severe toxicities and polymorphisms of ABCG2 421C>A nor ABCB1 3435C>T. The results suggested that ABCG2 34G>A would be useful for predicting grade 2 or worse skin rash.

Pivotal role of epithelial cell adhesion molecule in the survival of lung cancer cells.

Epithelial cell adhesion molecule (EpCAM) is overexpressed in a wide variety of human cancers including lung cancer, and its contribution to increased proliferation through upregulation of cell cycle accelerators such as cyclins A and E has been well established in breast and gastric cancers. Nevertheless, very little is known about its role in supporting the survival of cancer cells. In addition, the functional role of EpCAM in the pathogenesis of lung cancer remains to be explored. In this study, we show that RNAi-mediated knockdown of EpCAM suppresses proliferation and clonogenic growth of three EpCAM-expressing lung cancer cell lines (H3255, H358, and HCC827), but does not induce cell cycle arrest in any of these. In addition, EpCAM knockdown inhibits invasion in the highly invasive H358 but not in less invasive H3255 cells in a Transwell assay. Of note, the EpCAM knockdown induces massive apoptosis in the three cell lines as well as in another EpCAM-expressing lung cancer cell line, HCC2279, but to a much lesser extent in a cdk4/hTERT immortalized normal human bronchial epithelial cell line, HBEC4, suggesting that EpCAM could be a therapeutic target for lung cancer. Finally, EpCAM knockdown partially restores contact inhibition in HCC827, in association with p27(Kip1) upregulation. These results indicate that EpCAM could contribute substantially to the pathogenesis of lung cancer, especially cancer cell survival, and suggest that EpCAM targeted therapy for lung cancer may have potential.

[Preparation of standard protocol for cancer pain control and evaluation of its clinical effectiveness].

In order to promote the appropriate control of cancer pain by opioids, we distributed a pocket-sized protocol pamphlet on cancer pain control and opioid prescription to the medical staff of Nagoya University Hospital. In this study, we examined whether the prescription rate of opioids for rescue use, antiemetics for preventing adverse effects, and the rate of increase of regular opioid dosage were increased after distribution to evaluate its utility. Rescue opioid prescriptions, increase of regular opioid dosage and antiemetic prescription rate after distribution were all significantly increased, compared with before distribution. Furthermore, the frequency of nausea and vomiting was reduced by the use of prophylactic antiemetics. These results suggest that distribution of this protocol for cancer pain control may contribute to appropriate pain management.

Knockdown of ZEB1, a master epithelial-to-mesenchymal transition (EMT) gene, suppresses anchorage-independent cell growth of lung cancer cells.

We found that among four master epithelial-to-mesenchymal transition (EMT)-inducing genes (ZEB1, SIP1, Snail, and Slug) ZEB1expression was most significantly correlated with the mesenchymal phenotype (high Vimentin and low E-cadherin expression) in non-small cell lung cancer (NSCLC) cell lines and tumors. Furthermore, ZEB1 knockdown with RNA interference in three NSCLC cell lines with high ZEB1 expression suppressed to varying degrees mass culture growth and liquid colony formation but in all cases dramatically suppressed soft agar colony formation. In addition, ZEB1 knockdown induced apoptosis in one of the three lines, indicating that the growth inhibitory effects of ZEB1 knockdown occurs in part through the activation of the apoptosis pathway. These results suggest that inhibiting ZEB1 function may be an attractive target for NSCLC therapeutic development.