Biomedical subjects

Wei-Sing Chu

Publications and source records attributed to Wei-Sing Chu.

7 recordsLinked to original sources

PubMed2006

Phenotypic characterization of telomerase-immortalized primary non-malignant and malignant tumor-derived human prostate epithelial cell lines.

In vitro human prostate cell culture models are critical for clarifying the mechanism of prostate cancer progression and for testing preventive and therapeutic agents. Cell lines ideal for the study of human primary prostate tumors would be those derived from spontaneously immortalized tumor cells; unfortunately, explanted primary prostate cells survive only short-term in culture, and rarely immortalize spontaneously. Therefore, we recently have generated five immortal human prostate epithelial cell cultures derived from both the benign and malignant tissues of prostate cancer patients with telomerase, a gene that prevents cellular senescence. Examination of these cell lines for their morphologies and proliferative capacities, their abilities to grow in low serum, to respond to androgen stimulation, to grow above the agar layer, to form tumors in SCID mice, suggests that they may serve as valid, useful tools for the elucidation of early events in prostate tumorigenesis. Furthermore, the chromosome alterations observed in these immortalized cell lines expressing aspects of the malignant phenotypes imply that these cell lines accurately recapitulate the genetic composition of primary tumors. These novel in vitro models may offer unique models for the study of prostate carcinogenesis and also provide the means for testing both chemopreventive and chemotherapeutic agents.

Adult↗

PubMed2005

Ultrasound-accelerated tissue fixation/processing achieves superior morphology and macromolecule integrity with storage stability.

We demonstrate that high-frequency and high-intensity ultrasound (US) can be applied to both tissue fixation and tissue processing to complete the conventional overnight formalin-fixation and paraffin-embedding (FFPE) procedures within 1 hr. US-facilitated FFPE retains superior tissue morphology and long-term room temperature storage stability than conventional FFPE. There is less alteration of protein antigenicity after US-FFPE preservation so that rapid immunohistochemical reactions occur with higher sensitivity and intensity, reducing the need for antigen retrieval pretreatment. US-FFPE tissues present storage stability so that room temperature storage up to 7 years does not significantly affect tissue morphology, protein antigenic properties, RNA distribution, localization, and quantitation. In addition, during fixation, tissue displays physical changes that can be monitored and reflected as changes in transmission US signals. As far as we know, this is the first effort to monitor tissue physical changes during fixation. Further study of this phenomenon may provide a method to control and to monitor the level of fixation for quality controls. The mechanism of less alteration of protein antigenicity by US-FFPE was discussed.

Autopsy↗

PubMed2005

A nondestructive molecule extraction method allowing morphological and molecular analyses using a single tissue section.

In clinical practice, molecular analysis of tumor specimens is often restricted by available technology for sample preparation. Virtually all current methods require homogenization of tissues for molecule extraction. We have developed a simple, rapid, nondestructive molecule extraction (NDME) method to extract proteins and nucleic acids directly from a single fixed or frozen tissue section without destroying the tissue morphology. The NDME method is based upon exposure of micron-thick tissue section to extraction buffer with the help of heating and/or intact physical forces (ultrasound and microwave) to facilitate release of macromolecules into the buffer. The extracted proteins and nucleic acids can be used directly without further purification for downstream SDS-PAGE analysis, immunoblotting, protein array, mass spectra protein profiling, PCR, and RT-PCR reactions. Most importantly, the NDME procedure also serves as an antigen retrieval treatment, so that after NDME, the same tissue section can be used for histopathological analyses, such as H&E staining, immunohistochemistry, and in situ hybridization. Thus, the NDME method allows, for the first time, both histological diagnosis and molecular analysis on a single tissue section, whether it is from frozen or fixed tissue specimens.

Animals↗

PubMed2005

Ultrasound-accelerated formalin fixation of tissue improves morphology, antigen and mRNA preservation.

Formalin fixation and paraffin embedding are conventional tissue preservation and processing methods used for histologic diagnosis in over 90% of cases. However, formalin fixation has three disadvantages: (1) slow fixation (16-24 h) hinders intraoperative decision making, (2) slow quenching of enzymatic activity causes RNA degradation, and (3) extensive molecule modification affects protein antigenicity. Applying high-frequency, high-intensity ultrasound to the formalin fixative cuts fixation time to 5-15 min. Fixation of various tissues such as lymph node, brain, breast, and prostate suggests that, compared to the conventional method, implementation of ultrasound retains superior and more uniform tissue morphology preservation. Less protein antigenicity is altered so that rapid immunohistochemical reactions occur with higher sensitivity and intensity, reducing the need for antigen retrieval pretreatment. Better RNA preservation results in stronger signals in in situ hybridization and longer RNA fragments extracted from fixed tissues, probably due to rapid inhibition of endogenous RNase activity. Molecules extracted from ultrasound-fixed tissues are of greater integrity and quantity compared to conventionally fixed tissues, and thus better support downstream molecular analyses. Overall, ultrasound-facilitated tissue preservation can provide rapid and improved morphological and molecular preservation to better accommodate both traditional and molecular diagnoses.

Antigens↗

PubMed2003

The P16/cyclin D1/Rb pathway in neuroendocrine tumors of the lung.

Rb protein in its hypophosphorylated form acts as a cell cycle regulator for G1 arrest. Both cyclin D1 overexpression and P16(INK4) loss of protein produce persistent hyperphosphorylation of Rb with resultant evasion of cell cycle arrest. To better establish the mechanisms of loss of Rb function in neuroendocrine lung tumors, we performed an immunohistochemical analysis of the P16(INK4)/cyclin D1/Rb pathway in the spectrum of neuroendocrine tumors, including 34 typical carcinoids (TCs), 25 atypical carcinoids (ACs), 42 large cell neuroendocrine carcinomas (LCNECs), and 79 small cell lung carcinomas (SCLCs). Absence of Rb expression was not observed in TCs but was seen in 21% of ACs, 68% of LCNECs, and 87% of SCLCs. P16 was expressed in 91% of TCs, 77% of ACs, 78% of LCNECs, and 93% of SCLCs. Cyclin D1 was overexpressed in 6% of TCs, 20% of ACs, 9.5% of LCNECs, and 1.3% of SCLCs. There was an inverse relationship between Rb and P16 in high-grade tumors (P < 0.001) and a direct relationship between cyclin D1 and Rb (P < 0.001) in all tumors, demonstrating that P16 and cyclin D1 act exclusively on the Rb pathway for cell cycle regulation. Overall, the Rb pathway (Rb/P16(INK4)/cyclin D1) was altered more frequently in ACs than in TCs (P = 0.001) and more frequently in LCNECs than in ACs (P = 0.001). Although Rb-negative tumors had shorter survival in the overall group (P < 0.001) as a result of lack of Rb in most SCLCs, cyclin D1 overexpression and P16 loss did not influence survival in any individual category. We conclude that Rb pathway of G1 arrest is consistently compromised in high-grade neuroendocrine lung tumors (92%), primarily through loss of Rb protein, and is intact in low-grade TCs. In ACs an intermediate level of alterations (59%) is seen, consistent with their less-aggressive behavior compared with high-grade tumors. The specific profile of the Rb pathway parameters might provide specific therapeutic targets in neuroendocrine lung tumors.

Adult↗

PubMed2003

Latent membrane protein 1, tumor necrosis factor receptor-associated factor (TRAF) 1, TRAF-2, TRAF-3, and nuclear factor kappa B expression in posttransplantation lymphoproliferative disorders.

CONTEXT: Most posttransplantation lymphoproliferative disorders (PTLDs) are associated with Epstein-Barr virus (EBV) infection. The EBV latent membrane protein 1 (LMP-1) is important in the transformation of B lymphocytes through its interaction with intracellular tumor necrosis factor receptor-associated factors (TRAFs) that, in turn, can activate transcription factors such as nuclear factor kappa B (NFkappaB) and Jun-N-kinase. Of the 6 members of the TRAF family, TRAF-1, TRAF-2, and TRAF-3 are most commonly associated with LMP-1. Recently, it has been suggested that LMP-1-induced TRAF activation is important in the pathogenesis of PTLDs. OBJECTIVE: To characterize the expression patterns of these proteins in PTLDs, we studied a series of well-characterized cases for expression of LMP-1, TRAF-1, TRAF-2, TRAF-3, and NFkappaB by immunohistochemical analysis. METHODS: A total of 27 specimens from 25 patients were analyzed for LMP-1, TRAF-1, TRAF-2, TRAF-3, and NFkappaB (active form) by immunohistochemical analysis. Expression of EBV-encoded RNA (EBER) was evaluated by in situ hybridization. Correlation between the expression of the different markers was performed using the Mantel-Haenszel chi(2) test. Cox proportional hazards analysis and Kaplan-Meier analysis with log-rank testing were used to analyze antigen expression and clinical outcome. RESULTS: Ninety-six percent of PTLDs expressed NFkappaB, 74% to 84% expressed TRAFs, 78% expressed EBER, and 77% expressed LMP-1. TRAF-1, TRAF-2, and TRAF-3 expression did not correlate with either EBER or LMP-1 expression. TRAF-2, but not TRAF-1 or TRAF-3, expression correlated with NFkappaB expression (P =.02). CONCLUSIONS: These results suggest that TRAF molecules and active NFkappaB are expressed in PTLDs regardless of EBV positivity. Given the association of TRAF-2 and active NFkappaB expression, TRAF-2 may play an important role in regulating this transcription factor in PTLD.

Bone Marrow Transplantation↗

PubMed2002

Monocytic fasciitis: a newly recognized clinical feature of tumor necrosis factor receptor dysfunction.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is a dominantly inherited autoinflammatory syndrome that results from mutations in TNFRSF1A, the gene that encodes the 55-kd tumor necrosis factor receptor. Clinically, patients present with recurrent episodes of fever in conjunction with localized inflammation at various sites. Myalgia is one of the most characteristic features of this syndrome and is frequently associated with an overlying erythematous, macular rash that, together with the myalgia, displays centrifugal migration. This has previously been believed to occur as a result of myositis. We describe herein the case of a 60-year-old man with TRAPS, in whom magnetic resonance imaging of the left thigh demonstrated edematous changes in the muscle compartments and surrounding soft tissues. A full-thickness wedge biopsy was performed, and hematoxylin and eosin staining and immunohistochemistry analysis of the specimen demonstrated normal myofibrils but a severely destructive monocytic fasciitis. These results suggest that the myalgia experienced by individuals with TRAPS is due to a monocytic fasciitis and not to myositis.

Antigens, CD↗