p63 attenuates epithelial to mesenchymal potential in an experimental prostate cell model.

The transcription factor p63 is central for epithelial homeostasis and development. In our model of epithelial to mesenchymal transition (EMT) in human prostate cells, p63 was one of the most down-regulated transcription factors during EMT. We therefore investigated the role of p63 in EMT. Over-expression of the predominant epithelial isoform ΔNp63α in mesenchymal type cells of the model led to gain of several epithelial characteristics without resulting in a complete mesenchymal to epithelial transition (MET). This was corroborated by a reciprocal effect when p63 was knocked down in epithelial EP156T cells. Global gene expression analyses showed that ΔNp63α induced gene modules involved in both cell-to-cell and cell-to-extracellular-matrix junctions in mesenchymal type cells. Genome-wide analysis of p63 binding sites using ChIP-seq analyses confirmed binding of p63 to regulatory areas of genes associated with cell adhesion in prostate epithelial cells. DH1 and ZEB1 are two elemental factors in the control of EMT. Over-expression and knock-down of these factors, respectively, were not sufficient alone or in combination with ΔNp63α to reverse completely the mesenchymal phenotype. The partial reversion of epithelial to mesenchymal transition might reflect the ability of ΔNp63α, as a key co-ordinator of several epithelial gene expression modules, to reduce epithelial to mesenchymal plasticity (EMP). The utility of ΔNp63α expression and the potential of reduced EMP in order to counteract metastasis warrant further investigation.

S100A14 regulates the invasive potential of oral squamous cell carcinoma derived cell-lines in vitro by modulating expression of matrix metalloproteinases, MMP1 and MMP9.

Despite the differential expression of S100A14 (a newly identified S100 member) in various human cancers including oral squamous cell carcinomas (OSCCs), its biological role in tumour invasion has not been characterised. The aim of this study was thus to investigate the possible role of S100A14 in OSCC cell invasion. Using immunohistochemistry in normal (n=13), dysplastic (n=10) and OSCC (n=16) archival tissues, S100A14 protein was found to be down-regulated/lost with concomitant membrane to cytoplasmic translocation in OSCCs, especially in the invading tumour islands. These expression data were corroborated by profiling S100A14 mRNA expression using quantitative RT-PCR (qRT-PCR) in an in vitro human OSCC progression model consisting of cell-lines derived from normal (n=3), dysplastic (n=3) and OSCC (n=8) tissues. Employing in vitro Matrigel invasion assay, we demonstrated that retroviral vector mediated over-expression of S100A14 resulted in significant decrease in the invasive potential of OSCC derived CaLH3 and H357 cell-lines whereas siRNA mediated knockdown resulted in significant increase in the invasive potential of CaLH3 cell-line. Pathway focused PCR array and validation using qRT-PCR revealed that S100A14 over-expression was associated with down-regulation of MMP1 and MMP9 mRNAs in both CaLH3 and H357 cell-lines. Further, S100A14 over-expression was found to be associated with suppression of MMP9 gelatinolytic activity in CaLH3 cell-line. Additionally, an inverse correlation between mRNA expression levels of MMP1 and MMP9 with S100A14 was found in 19 cases of OSCCs. Collectively, these data provide the first evidence for a role of S100A14 protein in regulation of OSCC cell invasion by modulating expression of MMP1 and MMP9.

Axl is an essential epithelial-to-mesenchymal transition-induced regulator of breast cancer metastasis and patient survival.

Metastasis underlies the majority of cancer-related deaths. Thus, furthering our understanding of the molecular mechanisms that enable tumor cell dissemination is a vital health issue. Epithelial-to-mesenchymal transitions (EMTs) endow carcinoma cells with enhanced migratory and survival attributes that facilitate malignant progression. Characterization of EMT effectors is likely to yield new insights into metastasis and novel avenues for treatment. We show that the presence of the receptor tyrosine kinase Axl in primary breast cancers independently predicts strongly reduced overall patient survival, and that matched patient metastatic lesions show enhanced Axl expression. We demonstrate that Axl is strongly induced by EMT in immortalized mammary epithelial cells that establishes an autocrine signaling loop with its ligand, Gas6. Epiallelic RNA interference analysis in metastatic breast cancer cells delineated a distinct threshold of Axl expression for mesenchymal-like in vitro cell invasiveness and formation of tumors in foreign and tissue-engineered microenvironments in vivo. Importantly, in two different optical imaging-based experimental breast cancer models, Axl knockdown completely prevented the spread of highly metastatic breast carcinoma cells from the mammary gland to lymph nodes and several major organs and increased overall survival. These findings suggest that Axl represents a downstream effector of the tumor cell EMT that is required for breast cancer metastasis. Thus, the detection and targeted treatment of Axl-expressing tumors represents an important new therapeutic strategy for breast cancer.