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Tseng J.-Y.,National Yang Ming University | Yang C.-Y.,National Yang Ming University | Yang C.-Y.,Taipei Medical University Hospital | Liang S.-C.,National Yang Ming University | And 15 more authors.
Clinical Cancer Research

Purpose: Metastasis is the major cause of death in patients with colorectal cancer (CRC). Circulating tumor cells (CTC) are believed to cause metastasis and serve as a prognostic marker for mortality in clinical stage IV patients. However, most studies are conducted in late-stage cases when distant metastases have already occurred; thus, such results provide limited clinical use. This study focused on whether CTCs can predict the risk of metastasis after treatment of the primary tumor in early-stage patients with CRC. Experimental Design: CTCs were quantified using EpCAM-positive/CD45-negative immunoselection and flow cytometry in patients with CRC. A mouse model was used to investigate the mechanistic roles of CTCs and interleukin (IL)-17A in metastasis. Results: The number of mesenteric CTCs obtained from stage II patients was higher than that obtained from patients in stages I, III, and IV. In addition, following invasion of orthotopically implanted tumors in our mouse model, we found that CTCs exhibited an increase-then-decrease pattern, accompanied by corresponding changes in serum IL-17A levels and opposing changes in serum granulocyte macrophage colony-stimulating factor (GM-CSF) levels. Ablation of IL-17A and administration of rGM-CSF effectively suppressed the increase in CTCs and prevented metastasis in mice. Moreover, IL-17A promoted cancer cell motility, matrix digestion, and angiogenesis, whereas GM-CSF stimulated the elimination of CTCs by boosting host immunity. Notably, serum levels of IL-17A were also correlated with disease-free survival in patients with CRC. Conclusions: Our results showed that CTCs and IL-17A could serve as prognostic markers and therapeutic targets for CRC metastasis. ©2014 AACR. Source

Hsu C.-S.,National Yang Ming University | Tung C.-Y.,National Yang Ming University | Yang C.-Y.,National Yang Ming University | Yang C.-Y.,Taipei Medical University Hospital | And 3 more authors.

According to the cancer stem cell (CSC) model, higher CD133 expression in tumor tissue is associated with metastasis and poor prognosis in colon cancer. As such, the CD133-positive (CD133+) subpopulation of cancer cells is believed to play a central role in tumor development and metastatic progression. Although CD133+ cells are believed to display more CSC-like behavior and be solely responsible for tumor colonization, recent research indicates that CD133- cells from metastatic colon tumors not only also possess colonization capacity but also promote the growth of larger tumors in a mouse model than CD133+ cells, suggesting that an alternative mechanism of metastasis exists. This study investigated this possibility by examining the cell viability, tumorigenicity, and proliferation and growth capacity of the CD133+ and CD133- subpopulations of the SW620 cell line, a human metastatic colon cancer cell line, in both an in vitro cell model and an in vivo mouse model. While both SW620 CD133- and SW620CD133+ cells were found to engage in bidirectional cell-type switching in reaction to exposure to environmental stressors, including hypoxia, a cell adhesion-free environment, and extracellular matrix stimulation, both in vitro and in vivo, CD133- cells were found to have a growth advantage during early colonization due to their greater resistance to proliferation inhibition. Based on these findings, a hypothetical model in which colon cancer cells engage in cell-type switching in reaction to exposure to environmental stressors is proposed. Such switching may provide a survival advantage during early colonization, as well as that explain previous conflicting observations. © 2013 Hsu et al. Source

Wang C.-Y.,Academia Sinica, Taiwan | Hua C.-Y.,Academia Sinica, Taiwan | Hsu H.-E.,Academia Sinica, Taiwan | Hsu C.-L.,Academia Sinica, Taiwan | And 10 more authors.

Telomeric heterochromatin assembly in budding yeast propagates through the association of Silent Information Regulator (SIR) proteins with nucleosomes, and the nucleosome array has been assumed to fold into a compacted structure. It is believed that the level of compaction and gene repression within heterochromatic regions can be modulated by histone modifications, such as acetylation of H3 lysine 56 and H4 lysine 16, and monoubiquitylation of H2B lysine 123. However, it remains unclear as to whether or not gene silencing is a direct consequence of the compaction of chromatin. Here, by investigating the role of the carboxy-terminus of histone H2B in heterochromatin formation, we identify that the disorderly compaction of chromatin induced by a mutation at H2B T122 specifically hinders telomeric heterochromatin formation. H2B T122 is positioned within the highly conserved AVTKY motif of the αC helix of H2B. Heterochromatin containing the T122E substitution in H2B remains inaccessible to ectopic dam methylase with dramatically increased mobility in sucrose gradients, indicating a compacted chromatin structure. Genetic studies indicate that this unique phenotype is independent of H2B K123 ubiquitylation and Sir4. In addition, using ChIP analysis, we demonstrate that telomere structure in the mutant is further disrupted by a defect in Sir2/Sir3 binding and the resulting invasion of euchromatic histone marks. Thus, we have revealed that the compaction of chromatin per se is not sufficient for heterochromatin formation. Instead, these results suggest that an appropriately arrayed chromatin mediated by H2B C-terminus is required for SIR binding and the subsequent formation of telomeric chromatin in yeast, thereby identifying an intrinsic property of the nucleosome that is required for the establishment of telomeric heterochromatin. This requirement is also likely to exist in higher eukaryotes, as the AVTKY motif of H2B is evolutionarily conserved. © 2011 Wang et al. Source

Tseng J.-Y.,National Yang Ming University | Yang C.-Y.,Taipei Medical University Hospital | Liang S.-C.,National Yang Ming University | Liu R.-S.,Molecular and Genetic Imaging Core Taiwan Mouse Clinic | And 5 more authors.

Circulating tumor cells (CTCs) can be detected in the blood of different types of early or advanced cancer using immunology-based assays or nucleic acid methods. The detection and quantification of CTCs has significant clinical utility in the prognosis of metastatic breast, prostate, and colorectal cancers. CTCs are a heterogeneous population of cells and often different from those of their respective primary tumor. Understanding the biology of CTCs may provide useful predictive information for the selection of the most appropriate treatment. Therefore, CTC detection and characterization could become a valuable tool to refine prognosis and serve as a “real-time biopsy” and has the potential to guide precision cancer therapies, monitor cancer treatment, and investigate the process of metastasis. © 2014 by the authors; licensee MDPI, Basel, Switzerland. Source

Lin W.-J.,National Yang Ming University | Lin W.-J.,Yang Ming Genome Research Center | Yang C.-Y.,National Yang Ming University | Li L.-L.,National Yang Ming University | And 7 more authors.
Biochemical and Biophysical Research Communications

Autophagy orchestrates programmed cell death via crossroads of complex vesicle trafficking including autophagosome and lysosome interaction. Phafin1, an endosome proteins composed of Pleckstrin homology (PH) and Fab1-YotB-Vac1p-EEA1 (FYVE) domain membrane-binding domains, is involved in caspase-independent apoptosis. We report here that the increased expression of phafin1 and its FYVE domain caused the formation of enlarged endosomes. Phafin1 also modulates the membrane density of certain receptors and participates in endocytosis and autophagy processes. The PH-domain of phafin1 is dispensable for lysosomal targeting. Moreover, the tail-domain of phafin1 provides lysosomal targeting signature and the ability to induce autophagy that is mediated by Rab7 signaling. The results suggest that in addition to its role in endosome transport, phafin1 is also involved in lysosomal targeting and autophagosome formation. © 2011. Source

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