A correlation of TCF12 mRNA overexpression with colorectal cancer (CRC) metastasis was suggested by microarray data and validated by the survey of 120 patients. Thirty-three (27.5%) of the 120 patients showed tumor TCF12 mRNA overexpression and had a higher rate of metastatic occurrence (p ‫؍‬ 0.020) and a poorer survival outcome (p ‫؍‬ 0.014). Abundant TCF12 levels were also observed in human CRC cell lines such as SW620 and LoVo, but a relatively low level was detected in SW480 cells. Knockdown of TCF12 expression in SW620 and LoVo cells drastically reduced their activities of migration, invasion, and metastasis. Tight cell-cell contact and an increase in E-cadherin but a concomitant decrease in fibronectin were observed in TCF12-knockdown cells. Connexin 26, connexin 43, and gapjunction activity were also increased upon TCF12-knockdown. In contrast, ectopic TCF12 overexpression in SW480 cells facilitated fibronectin expression and cell migration and invasion activities but diminished cellular levels of E-cadherin, connexin 26, connexin 43, and gap junction. A physical association of TCF12 with the E-cadherin promoter was evidenced by chromatin immunoprecipitation assay. TCF12 was tightly correlated with cellular expression of Bmi1 and EZH2 and was co-immunoprecipitable with Bmi1 and EZH2, suggesting that TCF12 transcriptionally suppressed E-cadherin expression via polycomb group-repressive complexes. Clinically, TCF12 mRNA overexpression was also correlated with E-cadherin mRNA down-regulation in the tumor tissues of our 120 patients (p ‫؍‬ 0.013). These studies suggested that TCF12 functioned as a transcriptional repressor of E-cadherin and its overexpression was significantly correlated with the occurrence of CRC metastasis.Metastasis is the major cause of colorectal cancer (CRC) 3 mortality. Identification of metastasis-associated genes is essential for understanding the underlying mechanisms, developing new markers for early detection, and ultimately discovering new therapeutic targets. Development of new techniques in proteomic analysis has greatly helped identify molecules involved in the pathogenesis of metastasis (1-3). The advent of microarray technologies has also enhanced the search for genetic factors related to metastasis (4 -6). To identify novel metastasis-associated gene candidates in CRC, this study used microarray technology to determine the gene expression profiles of four CRC patients (two diagnosed with tumors confined in the primary sites and two diagnosed with metastasis). Elevated mRNA expression of the TCF12 gene was observed in the tumor tissues of both patients with metastasis.The product of TCF12 gene (TCF12, also called HTF4 or HEB) is a member of helix-loop-helix (HLH) protein family (7,8). HLH proteins have been divided into seven classes according to their tissue distribution, dimerization abilities, and DNA binding specificities (9). The class I proteins, encoded by TCF3 (E12, E47), TCF4 (E2-2), and TCF12 (HTF4) genes, are also known as E proteins because of their direct DNA (...

Background: Both secreted HSP90␣ and overexpressed TCF12 enhance colorectal cancer (CRC) cell migration/invasion. Results: Secreted HSP90␣ induces the CD91/IB kinase/NF-B/TCF12 cascade to down-regulate E-cadherin and to enhance CRC cell migration/invasion. Conclusion: Secreted HSP90␣ acts through TCF12 expression to enhance CRC cell spreading. Significance: Secreted HSP90␣ contributes to tumor TCF12 overexpression and can be a therapeutic target of CRC.

No abstract

Osteopontin (OPN) is a multi-functional phospho-glycoprotein that can stimulate angiogenesis through acting on endothelial cells. As angiogenic sprouting involves endothelial-to-mesenchymal transition (EndoMT), we are intrigued to know whether OPN exerts an effect on EndoMT. Clinically, we indeed detected EndoMT-derived cells next to OPN-expressing cells in colorectal cancer tissues. Furthermore, we treated OPN to primary cultures of endothelial cells to investigate the EndoMT-inducing activity and the underlying mechanisms. Integrin αVβ3 rather than CD44 is involved in OPN-induced EndoMT. OPN-integrin αVβ3 engagement induces HIF-1α expression through a PI3K/Akt/TSC2-mediated and mTORC1-dependent protein synthesis pathway, which in turn trans-activates TCF12 gene expression. TCF12 further interacts with EZH2 and histone deacetylases to transcriptionally repress VE-cadherin gene and thus facilitates EndoMT. Like cancer-associated fibroblasts, EndoMT-derived cells promote tumor growth and metastasis by secreting certain proteins. Secreted HSP90α is a candidate suggested by microwestern array assay, and is herein verified to induce stemness properties in colorectal cancer cells. As OPN is overexpressed in human cancers, OPN-induced EndoMT and EndoMT-derived cells can be potentially taken as cancer therapeutic targets.

The mycotoxin citrinin (CTN), a natural contaminant in foodstuffs and animal feeds, exerts cytotoxic and genotoxic effects on various mammalian cells. CTN causes cell injury, including apoptosis, but its precise regulatory mechanisms of action are currently unclear. Resveratrol, a member of the phytoalexin family found in grapes and other dietary plants, possesses antioxidant and anti-tumor properties. In the present study, we examined the effects of resveratrol on apoptotic biochemical events in Hep G2 cells induced by CTN. Resveratrol inhibited CTN-induced ROS generation, activation of JNK, loss of mitochondrial membrane potential (MMP), as well as activation of caspase-9, caspase-3 and PAK2. Moreover, resveratrol and the ROS scavengers, NAC and α-tocopherol, abolished CTN-stimulated intracellular oxidative stress and apoptosis. Active JNK was required for CTN-induced mitochondria-dependent apoptotic biochemical changes, including loss of MMP, and activation of caspases and PAK2. Activation of PAK2 was essential for apoptosis triggered by CTN. These results collectively demonstrate that CTN stimulates ROS generation and JNK activation for mitochondria-dependent apoptotic signaling in Hep G2 cells, and these apoptotic biochemical events are blocked by pretreatment with resveratrol, which exerts antioxidant effects.