Seung Sam Paik

Bio: Seung Sam Paik is an academic researcher from Hanyang University. The author has contributed to research in topics: Cancer & Tissue microarray. The author has an hindex of 22, co-authored 163 publications receiving 1974 citations.

Cancer stem cell markers CD133 and CD24 correlate with invasiveness and differentiation in colorectal adenocarcinoma.

Abstract: AIM: To verify that CD markers are available for detecting cancer stem cell populations and to evaluate their clinical significance in colon cancer. METHODS: Immunohistochemistry for CD133, CD24 and CD44 was performed on the tissue microarray of 523 colorectal adenocarcinomas. Medical records were reviewed and clinicopathological analysis was performed. RESULTS: In colorectal adenocarcinoma, 128 of 523 cases (24.5%) were positive and 395 cases (75.5%) were negative for CD133 expression. Two hundred and sixty-four of 523 cases (50.5%) were positive and 259 cases (49.5%) were negative for CD24 expression. Five hundred and two of 523 cases (96%) were negative and 21 cases (4%) were positive for CD44 expression. Upon clinicopathological analysis, CD133 expression was present more in male patients (P = 0.002) and in advanced T stage cancer (P = 0.024). Correlation between CD24 expression and clinicopathological factors was seen in the degree of differentiation (P = 0.006). Correlation between CD44 expression and clinicopathological factors was seen in the tumor size (P = 0.001). Survival was not significantly related to CD133, CD24 and CD44 expression. CONCLUSION: CD markers were related to invasiveness and differentiation of colorectal adenocarcinoma. However, CD expression was not closely related to survival.

MTA1 overexpression correlates significantly with tumor grade and angiogenesis in human breast cancers.

Abstract: Metastasis associated antigen 1 (MTA1) is a recently identified candidate metastasis-associated gene that plays an important role in tumorigenesis and tumor aggressiveness, especially tumor invasiveness and metastasis. We analyzed the relationship between MTA1 expression and variable clinicopathological features and characterized its role in tumor angiogenesis in human breast cancers. Two hundred and sixty-three breast cancer cases that successfully underwent surgery at Hanyang University Hospital (Seoul, Korea) between January 1989 and December 1997 were enrolled. MTA1 expression was observed by immunohistochemical staining and correlated with intratumoral microvessel density (MVD) and other clinicopathological parameters. MTA1 overexpression correlated significantly with higher tumor grade (grades 1 and 2 vs grade 3, P = 0.009). However, MTA1 expression did not correlate with tumor stage, status of estrogen and progesterone receptors, or axillary lymph node metastasis. Interestingly, MTA1 expression was found to correlate significantly with tumor MVD (P = 0.002). Survival analysis did not show a significant difference between MTA1 overexpression and poorer survival. In conclusion, MTA1 overexpression was found to be closely associated with higher tumor grade and increased tumor angiogenesis. These findings suggest MTA1 as a predictor of aggressive phenotype and a possible target molecule for anti-angiogenic drugs in breast cancer treatment. (Cancer Sci 2006)

Clinicopathological significance of nuclear PTEN expression in colorectal adenocarcinoma.

Abstract: Jang K-S, Song Y S, Jang S-H, Min K-W, Na W, Jang S M, Jun Y J, Lee K H, Choi D & Paik S S (2010) Histopathology56, 229–239 Clinicopathological significance of nuclear PTEN expression in colorectal adenocarcinoma Aims: Tumour suppressor phosphatase and tensin homologue (PTEN) is an important negative regulator for the PIP3/Akt signalling pathway that promotes cell proliferation and inhibits apoptosis. Inactivation of PTEN by mutation, deletion and promoter hypermethylation has been demonstrated in a range of cancers. The aim was to investigate whether the loss of nuclear PTEN protein expression correlates with conventional clinicopathological parameters and patient survival. Methods and results: Immunohistochemistry staining for PTEN was performed on a tissue microarray of 19 samples of normal colonic mucosa, 14 adenomatous polyps, 482 adenocarcinomas and 56 metastatic lymph nodes. All 19 normal colonic mucosa samples (100%) were positive and 12 (85.7%) out of 14 adenomatous polyps were positive for PTEN. However, only 241 (50.0%) of the 482 colorectal adenocarcinomas and 26 (46.4%) of the 56 metastatic lymph nodes were positive for PTEN. Loss of PTEN expression was related to defective mismatch repair protein expression and colonic localization rather than rectal localization. On univariate survival analysis, patients with PTEN− adenocarcinoma revealed a poor overall and disease-free survival (P = 0.030 and P = 0.046, respectively). On multivariate analysis, a significant difference was observed in patients with stage II cancer that was not observed in other stages. Conclusions: Nuclear PTEN expression gradually decrease during the normal–adenoma–adenocarcinoma–metastasis sequence, which suggests an important role for PTEN in carcinogenesis. Moreover, loss of nuclear PTEN expression was a marker of poor clinical outcome in patients with stage II colorectal cancer.

Generation of Multilayered 3D Structures of HepG2 Cells Using a Bio-printing Technique

Abstract: Background/Aims Chronic liver disease is a major widespread cause of death, and whole liver transplantation is the only definitive treatment for patients with end-stage liver diseases. However, many problems, including donor shortage, surgical complications and cost, hinder their usage. Recently, tissue-engineering technology provided a potential breakthrough for solving these problems. Three-dimensional (3D) printing technology has been used to mimic tissues and organs suitable for transplantation, but applications for the liver have been rare. Methods A 3D bioprinting system was used to construct 3D printed hepatic structures using alginate. HepG2 cells were cultured on these 3D structures for 3 weeks and examined by fluorescence microscopy, histology and immunohistochemistry. The expression of liverspecific markers was quantified on days 1, 7, 14, and 21. Results The cells grew well on the alginate scaffold, and liver-specific gene expression increased. The cells grew more extensively in 3D culture than two-dimensional culture and exhibited better structural aspects of the liver, indicating that the 3D bioprinting method recapitulates the liver architecture. Conclusions The 3D bioprinting of hepatic structures appears feasible. This technology may become a major tool and provide a bridge between basic science and the clinical challenges for regenerative medicine of the liver.

In vitro differentiation of mouse embryonic stem cells: enrichment of endodermal cells in the embryoid body.

Abstract: Embryonic stem (ES) cells have the potential to differentiate into all three germ layers, providing new perspectives not only for embryonic development but also for the application in cell replacement therapies. Even though the formation of an embryoid body (EB) in a suspension culture has been the most popular method to differentiate ES cells into a wide range of cells, not much is known about the characteristics of EB cells. To this end, we investigated the process of EB formation in the suspension culture of ES cells at weekly intervals for up to 6 weeks. We observed that the central apoptotic area is most active in the first week of EB formation and that the cell adhesion molecules, except beta-catenin, are highly expressed throughout the examination period. The sequential expression of endodermal genes in EBs during the 6-week culture correlated closely with that of normal embryo development. The outer surface of EBs stained positive for alpha-fetoprotein and GATA-4. When isolated from the 2-week-old EB by trypsin treatment, these endodermal lineage cells matured in vitro into hepatocytes upon stimulation with various hepatotrophic factors. In conclusion, our results demonstrate that endodermal cells can be retrieved from EBs and matured into specific cell types, opening new therapeutic usage of these in vitro differentiated cells in the cell replacement therapy of various diseases.

Integrative Genomics Viewer

Abstract: Rapid improvements in sequencing and array-based platforms are resulting in a flood of diverse genome-wide data, including data from exome and whole-genome sequencing, epigenetic surveys, expression profiling of coding and noncoding RNAs, single nucleotide polymorphism (SNP) and copy number profiling, and functional assays. Analysis of these large, diverse data sets holds the promise of a more comprehensive understanding of the genome and its relation to human disease. Experienced and knowledgeable human review is an essential component of this process, complementing computational approaches. This calls for efficient and intuitive visualization tools able to scale to very large data sets and to flexibly integrate multiple data types, including clinical data. However, the sheer volume and scope of data pose a significant challenge to the development of such tools.

Sarcoidosis

Abstract: 结节病易误诊,据王洪武等~([1])收集国内18篇关于此病误诊的文献,误诊率高达63.2%,当然有误诊就会有误治,如孙永昌等~([2])报道26例结节病在影像学检查诊断的第一印象中拟诊结核5例,其中就有2例完成规范的抗结核治疗,为此应引起临床对本病诊治的重视。

Recent advances in three-dimensional multicellular spheroid culture for biomedical research

Abstract: Many types of mammalian cells can aggregate and differentiate into 3-D multicellular spheroids when cultured in suspension or a nonadhesive environment. Compared to conventional monolayer cultures, multicellular spheroids resemble real tissues better in terms of structural and functional properties. Multicellular spheroids formed by transformed cells are widely used as avascular tumor models for metastasis and invasion research and for therapeutic screening. Many primary or progenitor cells on the other hand, show significantly enhanced viability and functional performance when grown as spheroids. Multicellular spheroids in this aspect are ideal building units for tissue reconstruction. Here we review the current understanding of multicellular spheroid formation mechanisms, their biomedical applications, and recent advances in spheroid culture, manipulation, and analysis techniques.