Targeting delivery of paclitaxel into tumor cells via somatostatin receptor endocytosis

AbstractBackground: The binding of somatostatin (SST) to endogenous G-protein-coupled receptors (SST receptors or SSTRs) is followed by internalization of SST, and, several reports have shown that a high density of SSTRs is present on most hormone-secreting tissue tumors. Facile synthesis of the long-acting SST analog, octreotide, has previously been described. Octreotide might be of practical value in developing tumor tracers and in serving as a carrier of cytotoxic antitumor drugs.Results: Fluorescein-labeled octreotide was internalized into the cytosol of human breast MCF-7 carcinoma cells via binding to SSTRs. Octreotide-conjugated paclitaxel (taxol) was created by coupling taxol–succinate to the amino-terminal end of octreotide. This conjugate retains the biological activity of taxol in inducing formation of tubulin bundles, eventually causing apoptosis of MCF-7 cells. Cytotoxicity of octreotide-conjugated taxol is mainly mediated by SSTR, as shown by the observation that octreotide pretreatment can rescue the induced cell death. In comparison with free taxol, this conjugate shows much less toxicity in Chinese hamster ovary cells.Conclusions: Octreotide-conjugated taxol exerts the same antitumor effect of free taxol on stabilizing microtubule formation and inducing cell death. This conjugate triggers tumor cell apoptosis mediated by SSTRs and is exclusively toxic to SSTR-expressing cells. Octreotide-conjugated taxol is less toxic to low-SSTR-expressing cells compared with free taxol. Our results strongly indicated that octreotide-conjugated taxol demonstrates cell selectivity and may be used as a targeting agent for cancer therapy

Coregulation of transcription factors and microRNAs in human transcriptional regulatory network

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression at the post-transcriptional level. Recent studies have suggested that miRNAs and transcription factors are primary metazoan gene regulators; however, the crosstalk between them still remains unclear.</p> <p>Methods</p> <p>We proposed a novel model utilizing functional annotation information to identify significant coregulation between transcriptional and post-transcriptional layers. Based on this model, function-enriched coregulation relationships were discovered and combined into different kinds of functional coregulation networks.</p> <p>Results</p> <p>We found that miRNAs may engage in a wider diversity of biological processes by coordinating with transcription factors, and this kind of cross-layer coregulation may have higher specificity than intra-layer coregulation. In addition, the coregulation networks reveal several types of network motifs, including feed-forward loops and massive upstream crosstalk. Finally, the expression patterns of these coregulation pairs in normal and tumour tissues were analyzed. Different coregulation types show unique expression correlation trends. More importantly, the disruption of coregulation may be associated with cancers.</p> <p>Conclusion</p> <p>Our findings elucidate the combinatorial and cooperative properties of transcription factors and miRNAs regulation, and we proposes that the coordinated regulation may play an important role in many biological processes.</p

Ganoderma lucidum Polysaccharides Induce Macrophage-Like Differentiation in Human Leukemia THP-1 Cells via Caspase and p53 Activation

Differentiation therapy by induction of tumor cells is an important method in the treatment of hematological cancers such as leukemia. Tumor cell differentiation ends cancer cells' immortality, thus stopping cell growth and proliferation. In our previous study, we found that fucose-containing polysaccharide fraction F3 extracted from Ganoderma lucidum can bring about cytokine secretion and cell death in human leukemia THP-1 cells. This prompted us to further investigate on how F3 induces the differentiation in human leukemia cells. We integrated time-course microarray analysis and network modeling to study the F3-induced effects on THP-1 cells. In addition, we determined the differentiation effect using Liu's staining, nitroblue tetrazolium (NBT) reduction assay, flow cytometer, western blotting and Q-PCR. We also examined the modulation and regulation by F3 during the differentiation process. Dynamic gene expression profiles showed that cell differentiation was induced in F3-treated THP-1 cells. Furthermore, F3-treated THP-1 cells exhibited enhanced macrophage differentiation, as demonstrated by changes in cell adherence, cell cycle arrest, NBT reduction and expression of differentiation markers including CD11b, CD14, CD68, matrix metalloproteinase-9 and myeloperoxidase. In addition, caspase cleavage and p53 activation were found to be significantly enhanced in F3-treated THP-1 cells. We unraveled the role of caspases and p53 in F3-induced THP-1 cells differentiation into macrophages. Our results provide a molecular explanation for the differentiation effect of F3 on human leukemia THP-1 cells and offer a prospect for a potential leukemia differentiation therapy

Lengthening of 3&#x27;UTR Increases Morphological Complexity in Animal Evolution

By analyzing the structure of mRNA transcripts in multiple metazoan species, we observed a striking exponential correlation between the length of 3&#x27; untranslated regions (3&#x27;UTR) and morphological complexity as measured by the number of cell types in each organism. Cellular diversity was similarly associated with the accumulation of microRNA genes and their putative targets. We propose that the lengthening of 3&#x27;UTRs together with a commensurate expansion in post-transcriptional regulation can contribute to the emergence of new cell types during animal evolution

Ganoderma lucidum polysaccharides enhance CD14 endocytosis of LPS and promote TLR4 signal transduction of cytokine expression

We have previously reported that a well-characterized glycoprotein fraction containing fucose residues in an extract of Ganoderma lucidum polysaccharides (EORP) exerts certain immuno-modulation activity by stimulating the expression of inflammatory cytokines via TLR4. Continuing our studies, we have demonstrated that EORP increases the surface expression of CD14 and TLR4 within murine macrophages J774A.1 cells in vitro, and further promotes LPS binding and uptake by J774A.1 cells in a CD14-dependent fashion. Moreover, we observed the co-localization of internalized LPS with lysosome- and Golgi-apparatus markers within 5 min after J774A.1 cells stimulated with LPS. In addition, EORP pretreatment of J774A.1 cells and human blood-derived primary macrophages, followed by LPS stimulation, results in the super-induction of interleukin-1beta (IL-1) expression. Endocytosis inhibitors: such as cytochalasin D and colchicine effectively block EORP-enhanced LPS internalization by J774A.1 cells; yet they fail to decrease the LPS-induced phosphorylation of certain mitogen-activated protein kinases, and IL-1 mRNA and proIL-1 protein expression, indicating that LPS internalization by J774A.1 cells is not associated with LPS-dependent activation. Our current results could provide a potential EORP-associated protection mechanism for bacteria infection by enhancing IL-1 expression and the clearance of contaminated LPS by macrophages. J. Cell. Physiol. 212: 537–550, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56052/1/21050_ftp.pd

Ganoderma lucidum polysaccharides in human monocytic leukemia cells: from gene expression to network construction

<p>Abstract</p> <p>Background</p> <p><it>Ganoderma lucidum </it>has been widely used as a herbal medicine for promoting health and longevity in China and other Asian countries. Polysaccharide extracts from <it>Ganoderma lucidum </it>have been reported to exhibit immuno-modulating and anti-tumor activities. In previous studies, F3, the active component of the polysaccharide extract, was found to activate various cytokines such as IL-1, IL-6, IL-12, and TNF-<it>α</it>. This gave rise to our investigation on how F3 stimulates immuno-modulating or anti-tumor effects in human leukemia THP-1 cells.</p> <p>Results</p> <p>Here, we integrated time-course DNA microarray analysis, quantitative PCR assays, and bioinformatics methods to study the F3-induced effects in THP-1 cells. Significantly disturbed pathways induced by F3 were identified with statistical analysis on microarray data. The apoptosis induction through the DR3 and DR4/5 death receptors was found to be one of the most significant pathways and play a key role in THP-1 cells after F3 treatment. Based on time-course gene expression measurements of the identified pathway, we reconstructed a plausible regulatory network of the involved genes using reverse-engineering computational approach.</p> <p>Conclusion</p> <p>Our results showed that F3 may induce death receptor ligands to initiate signaling via receptor oligomerization, recruitment of specialized adaptor proteins and activation of caspase cascades.</p