Environmental exposure to arsenic is known to cause various cancers. There are some potential relationships between cell malignant transformation and C-X-C chemokine receptor type 4 (CXCR4) expressions. Metastasis, one of the major characteristics of malignantly transformed cells, contributes to the high mortality of cells. CXCR4 and its natural chemokine ligand C-X-C motif ligand 12 (CXCL12) play a critical role in metastasis. Therefore, identification of nutritional factors which are able to inhibit CXCR4 is important for protection from environmental arsenic-induced carcinogenesis and for abolishing metastasis of malignantly transformed cells. The present study demonstrates that apigenin (4,5,7-trihydroxyflavone), a natural dietary flavonoid, suppressed CXCR4 expression in arsenic-transformed Beas-2B cells (B-AsT) and several other types of transformed/cancer cells in a dose- and time-dependent manner. Neither proteasome nor lysosome inhibitor had any effect in reducing the apigenin-induced down-regulation of CXCR4, indicating that apigenin-induced down-regulation of CXCR4 is not due to proteolytic degradation. The down-regulation of CXCR4 is mainly due to the inhibition of nuclear factor ?B (NF-?B) transcriptional activity. Apigenin also abolished migration and invasion of transformed cells induced by CXCL12. In a xenograft mouse model, apigenin down-regulated CXCR4 expression and suppressed tumor growth. Taken together, our results show that apigenin is a novel inhibitor of CXCR4 expression. This dietary flavonoid has the potential to suppress migration and invasion of transformed cells and prevent environmental arsenic-induced carcinogenesis.
Cudratricusxanthone G (CTXG), a natural bioactive cudratricusxanthone extracted from C. tricuspidata, has shown anti-cancer properties. However, the function and mechanism of CTXG in tumor invasion have not been elucidated to date. In this study, we investigated the inhibitory effect of CTXG on the proliferation, migration and invasion of SW620 cells. We found that MMP-2, a pivotal factor in tumor invasion, was suppressed in both expression and activation by CTXG in a dose-dependent manner. The suppression of MMP-2 expression by CTXG led to an inhibition of SW620 cells invasion and migration by inactivating Rac1 and Cdc42 but not RhoA GTPase. Furthermore, CTXG also inhibited the transcriptional activity of AP-1 (activator protein-1). In conclusion, our data demonstrate that CTXG exerted anti-invasion action in SW620 cells by targeting MMP-2 though regulating the activities of Rac1, Cdc42 and their downstream transcriptional factor AP-1. These results are the first to reveal the novel functions of CTXG in cancer cell invasion and its molecular basis for the anti-cancer action.
Hepatocellular carcinoma is one of the deadliest cancers in the world. In this study, a hepatocarcinoma-specific binding peptide, which could be used for drug delivery in targeting therapy, was obtained by in vivo phage display technology. After three rounds of panning, only the potential motif Pro-Ser was found in 80 sequenced phage clones. Phage A54 (sequence AGKGTPSLETTP) was shown to be the most effective and specific to the liver cancer cells by cell-based ELISA in all 130 tested clones. After phage A54 was injected i.v. into the xenograft-bearing mice for in vivo distribution, phage enrichment was found in tumor tissues compared with control phage C10 and normal liver tissues through phage titering and immunohistochemical staining. Next, the specific binding ability of synthesized peptide A54 was further confirmed by fluorescence microscopy, competition binding, and fluorescence-activated cell sorting assay. A54 and A54M (sequence AGKGTAALETTP) were synthesized and coupled to doxorubicin (DOX) to do the preliminary targeting therapy. After the treatment, the proliferation of liver cancer cells treated with A54-DOX was restrained significantly in vitro when compared with A54M-DOX-treated group. Reduction in tumor size and prolongation of long-term survival were also found in xenograft-bearing models compared with free DOX-treated group. In conclusion, the specific binding peptide A54, which was screened from phage display library, represents a promising approach for the development of novel target therapy strategies against hepatocellular carcinoma.
Two different classes of small nematode specific lipid-binding proteins, the nematode polyprotein allergens/antigens (NPAs) and the fatty acid- and retinol-binding (FAR) proteins, are secreted by helminth parasites. Until now, there was no evidence of the expression or secretion of these two families of proteins in Haemonchus contortus. In this study, we applied proteomic and bioinformatic tools in an iterative manner to reveal the expression and complexity of these proteins in the excretory/secretory products (ESP) of adult H. contortus at the protein and gene levels. Initial examination of the mass spectra of ESP fractions against standard databases returned nine peptides mapping to Ostertagia ostertagi NPA and FAR sequences. Searches of the H. contortus EST and genomic contig databases with the O. ostertagi and Caenorhabditis elegans homologues retrieved diverse sequences encoding H. contortus NPA and FAR proteins. H. contortus sequences were then integrated into a customized database and a new search of the mass spectra achieved a 10-fold improvement in coverage of the predicted H. contortus NPAs. The final analyses of the mass spectra achieved 49-60% coverage of H. contortus NPAs and 7-47% coverage of H. contortus FARs. Moreover, the diversity in structures of the encoding genes was revealed by assembling the genomic sequence data with predicted protein sequences confirmed by the peptide evidence. We predict there are at least one Hc-NPA gene and six Hc-FAR genes in H. contortus, and life stage gene expression of Hc-FAR-1 to -6 revealed unique transcription patterns for each of these genes.
DNA damage tolerance consisting of template switching and translesion synthesis is a major cellular mechanism in response to unrepaired DNA lesions during replication. The Rev1 pathway constitutes the major mechanism of translesion synthesis and base damage-induced mutagenesis in model cell systems. Rev1 is a dCMP transferase, but additionally plays non-catalytic functions in translesion synthesis. Using the yeast model system, we attempted to gain further insights into the non-catalytic functions of Rev1. Rev1 stably interacts with Rad5 (a central component of the template switching pathway) via the C-terminal region of Rev1 and the N-terminal region of Rad5. Supporting functional significance of this interaction, both the Rev1 pathway and Rad5 are required for translesion synthesis and mutagenesis of 1,N(6)-ethenoadenine. Furthermore, disrupting the Rev1-Rad5 interaction by mutating Rev1 did not affect its dCMP transferase, but led to inactivation of the Rev1 non-catalytic function in translesion synthesis of UV-induced DNA damage. Deletion analysis revealed that the C-terminal 21-amino acid sequence of Rev1 is uniquely required for its interaction with Rad5 and is essential for its non-catalytic function. Deletion analysis additionally implicated a C-terminal region of Rev1 in its negative regulation. These results show that a non-catalytic function of Rev1 in translesion synthesis and mutagenesis is mediated by its interaction with Rad5.
Related JoVE Video
Journal of Visualized Experiments
What is Visualize?
JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.
How does it work?
We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.
Video X seems to be unrelated to Abstract Y...
In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.