Dauricine induces apoptosis, inhibits proliferation and invasion through inhibiting NF-kappaB signaling pathway in colon cancer cells.

Dauricine, a bioactive component of Asiatic Moonseed Rhizome, has been widely used to treat a large number of inflammatory diseases in traditional Chinese medicine. In our study, we demonstrated that dauricine inhibited colon cancer cell proliferation and invasion, and induced apoptosis by suppressing nuclear factor-kappaB (NF-kappaB) activation in a dose- and time-dependent manner. Addition of dauricine inhibited the phosphorylation and degradation of IkappaBalpha, and the phosphorylation and translocation of p65. Moreover, dauricine down-regulated the expression of various NF-kappaB-regulated genes, including genes involved cell proliferation (cyclinD1, COX2, and c-Myc), anti-apoptosis (survivin, Bcl-2, XIAP, and IAP1), invasion (MMP-9 and ICAM-1), and angiogenesis (VEGF). In athymic nu/nu mouse model, we further demonstrated that dauricine significantly suppressed colonic tumor growth. Taken together, our results demonstrated that dauricine inhibited colon cancer cell proliferation, invasion, and induced cell apoptosis by suppressing NF-kappaB activity and the expression profile of its downstream genes. These findings provide evidence for a novel role of dauricine in preventing or treating colon cancer through modulation of NF-kappaB singling pathway.

ZNF325, a novel human zinc finger protein with a RBaK-like RB-binding domain, inhibits AP-1- and SRE-mediated transcriptional activity.

Mitogen-activated protein kinase (MAPK) signal transduction pathways are among the most widespread mechanisms of eukaryotic cell regulation. The zinc-finger-containing transcription factors have been previously revealed to be involved in the regulation of the MAPK signaling pathways. Here, we have identified a novel human zinc-finger transcriptional repressor, ZNF325, that contains a RBaK-like RB-binding domain and 15 tandem repeated C2H2 type zinc fingers. Northern blot analysis indicates that a 2.7 kb transcript specific for ZNF325 is widely expressed in all tissues examined at adult stage and in most of the embryonic tissues. Overexpression of ZNF325 in COS-7 cells inhibits the transcriptional activities of AP-1 and SRE. The deletion and RNAi analysis indicate that the C2H2 zinc finger motifs represent the basal transcriptional repressive activity. These results indicate that the ZNF325 protein may act as a novel transcription repressor in MAPK signaling pathway to mediate cellular functions.

ZNF328, a novel human zinc-finger protein, suppresses transcriptional activities of SRE and AP-1.

The zinc finger proteins containing the Kruppel-associated box domain (KRAB-ZFPs) are the single largest class of transcription factors in human genome. Many of the KRAB-ZFPs are involved in cardiac development or cardiovascular diseases. Here, we have identified a novel human KRAB zinc finger gene, named ZNF328, from the human fetal heart cDNA library. The complete sequence of ZNF328 cDNA contains a 2376-bp open reading frame (ORF) and encodes a 792 amino acid protein with an N-terminal KRAB domain and classical zinc finger C2H2 motifs in the C-terminus. Northern blot analysis indicates that the protein is expressed in most of the examined human adult and embryonic tissues. ZNF328 is a transcription suppressor when fused to Gal-4 DNA-binding domain and cotransfected with VP-16. Overexpression of ZNF328 in COS-7 cells inhibits the transcriptional activities of SRE and AP-1. Deletion analysis with a series of truncated fusion proteins indicates that the KRAB motif is a basal repression domain when cotransfected with VP-16. Similar results were obtained when the truncated fusion proteins were assayed for the transcriptional activities of SRE and AP-1. These results suggest that ZNF328 protein may act as a transcriptional repressor in mitogen-activated protein kinase (MAPK) signaling pathway to mediate cellular functions.