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Kim J.,Research Center for Womens Diseases | Lee S.-D.,Research Center for Womens Diseases | Chang B.,Research Center for Womens Diseases | Jin D.-H.,Institute of Innovative Cancer Research | And 8 more authors.
Free Radical Biology and Medicine | Year: 2012

Ascorbate is an important natural antioxidant that can selectively kill cancer cells at pharmacological concentrations. Despite its benefit, it is quite difficult to predict the antitumor effects of ascorbate, because the relative cytotoxicity of ascorbate differs between cancer cell lines. Therefore, it is essential to examine the basis for this fundamental disagreement. Because p53 is activated by DNA-damaging stress and then regulates various cellular conditions, we hypothesized that p53 can sensitize cancer cells to ascorbate. Using isogenic cancer cells, we observed that the presence of p53 can affect ascorbate cytotoxicity, and also reactivation of p53 can make cancer cells sensitive to ascorbate. p53-dependent enhancement of ascorbate cytotoxicity is caused by increased reactive oxygen species generation via a differentially regulated p53 transcriptional network. We also found that transcriptionally activated p53 was derived from MDM2 ubiquitination by ascorbate and subsequently its signaling network renders cancer cells more susceptible to oxidative stress. Similar to the p53 effect on in vitro ascorbate cytotoxicity, inhibition of tumor growth is also stronger in p53-expressing tumors than in p53-deficient ones in vivo. This is the first observation that ascorbate cytotoxicity is positively related to p53 expression, activating its transcriptional network to worsen intracellular oxidative stress and consequently enhancing its cytotoxicity. Based on our study, reactivation of p53 may help to achieve more consistent cytotoxic effects of ascorbate in cancer therapies. © 2012 Elsevier Inc.

Kim J.C.,Asan Medical Center | Kim J.C.,Institute of Innovative Cancer Research | Choi J.S.,Asan Medical Center | Choi J.S.,Institute of Innovative Cancer Research | And 8 more authors.
Annals of Surgical Oncology | Year: 2010

Background. Promoter methylation of colorectal cancerrelated genes were examined with respect to phenotype and tumor progression. Materials and Methods. We assayed promoter methylation of 11 genes including established CpG island methylator phenotype (CIMP) markers (MLH1, MINT1, MINT2, MINT31, p16 INK4a, p14ARF, and CACNA1G) and four genes (COX2, DAPK, MGMT, and APC) frequently methylated in colorectal cancer in 285 patients with sporadic colorectal cancer. Results. CIMP+ tumors were more than two times more frequent among high-frequency microsatellite instability tumors (MSI-H) than in tumors without MSI (P ≤.0001-.002). COX2 and DAPK methylation were significantly associated with CIMP+ and MSI. KRAS showed tendency toward more frequent codon 12-13 mutations identified in tumors with APC and p16 INK4a methylation than in those with unmethylation (P =.033 and.05, respectively). Additionally, tumors with synchronous adenoma were associated with p16INK4a methylation (P =.004). The p16INK4a methylation was significantly associated with poor overall and disease-free survival in 131 rectal cancer patients who underwent curative operation, according to multivariate analyses (relative risk [RR] = 0.317 and 0.349; P =.033 and.024, respectively). Specifically, in 175 stage II and III patients receiving adjuvant-based fluoropyrimidine chemotherapy, p16INK4a methylation and MINT31 unmethylation showed a significant or tendency toward an association with recurrence and DFS (P =.007-.032). Conclusions. The study suggests that specific CIMP markers, such as p16INK4a and MINT31, should be further verified as potential epigenetic targets for the design of efficient chemotherapy regimens. We also identified a subset of colorectal cancer, possibly comprising APC methylation-KRAS mutation-p16INK4a methylation. © Society of Surgical Oncology 2010.

Kim J.C.,University of Ulsan | Kim J.C.,Institute of Innovative Cancer Research | Yu J.H.,University of Ulsan | Yu J.H.,Institute of Innovative Cancer Research | And 10 more authors.
Breast Cancer Research and Treatment | Year: 2012

Small proline rich repeat protein 3 (SPRR3), a member of the SPRR family of cornified envelope precursor proteins, is a marker for terminal squamous cell differentiation. Previously, this laboratory showed that SPRR3 is strongly upregulated in colorectal tumors, and is involved in the tumorigenesis. The current study was performed to investigate the expression status and effect of SPRR3 in breast cancers (BCs). SPRR3 expression was examined by immunohistochemistry in 241 tumor samples from BC patients. SPRR3 was overexpressed in more than half of all BC samples. SPRR3 overexpression was significantly associated with less advanced stage (0-1 vs. II=III) and the absence of lymph node metastasis (P = 0.004 and 0.013, respectively). HER2/neu overexpression was closely correlated with SPRR3 overexpression in a multivariate analysis (OR, 3.23, P = 0.017). To assess the influence of SPRR3 on cell proliferation and related signaling pathways, SPRR3-transfected clones from the SPRR3-negative T-47D human BC cell line were generated. Among the total of six SPRR3-overexpressing clones, five showed marked proliferation compared with SPRR3-nonexpressing control cells from day 3 of culture (P < 0.001). The SPRR3-over-expressing BC clones showed increased phosphorylation of AKT and MDM2, p21 overexpression, and p53 downregu-lation. Furthermore, phosphorylation of MEK and M APK was markedly increased. This study demonstrates that SPRR3 promotes BC cell proliferation by enhancing p53 degradation via the AKT and MAPK pathways and is, therefore, a potential novel therapeutic target for less advanced stages of BC. © 2012 Springer Science+Business Media, LLC.

Xiao H.,University of Ulsan | Xiao H.,Beijing United Family Hospital | Yoon Y.S.,University of Ulsan | Yoon Y.S.,Beijing United Family Hospital | And 8 more authors.
American Journal of Clinical Pathology | Year: 2013

Objectives: To evaluate the association of microsatellite instability (MSI) with clinicopathologic features and oncologic outcomes in patients with poorly differentiated colorectal cancer (PD). Methods: Study patients were divided into well-differentiated colorectal cancer (WD) and PD, which were compared according to histologic differentiation and MSI status. Results: Among 1,941 patients, PD was more frequent among microsatellite-unstable tumors (23.6%) than among microsatellite-stable (MSS) tumors (4.2%, P < .001). Patients with PD had worse 4-year overall survival rates than patients with WD (78.6% vs 88.2%, P = 0.010). Compared with MSS-PD tumors, MSI-PD tumors were characterized by right-colon predilection, larger size, and infrequent lymph node metastasis (P < .001 to P = .007). Conclusions: The clinicopathologic characteristics of PD were closely associated with those of MSI. The outcomes of MSI-PD tumors were better than those of MSS-PD tumors, but this finding did not reach statistical significance. © American Society for Clinical Pathology.

Kim J.C.,University of Ulsan | Kim J.C.,Institute of Innovative Cancer Research | Ha Y.J.,University of Ulsan | Ha Y.J.,Institute of Innovative Cancer Research | And 14 more authors.
International Journal of Radiation Oncology Biology Physics | Year: 2013

Purpose: Studies aimed at predicting individual responsiveness to preoperative chemoradiation therapy (CRT) are urgently needed, especially considering the risks associated with poorly responsive patients. Methods and Materials: A 3-step strategy for the determination of CRT sensitivity is proposed based on (1) the screening of a human genome-wide single-nucleotide polymorphism (SNP) array in correlation with histopathologic tumor regression grade (TRG); (2) clinical association analysis of 113 patients treated with preoperative CRT; and (3) a cell-based functional assay for biological validation. Results: Genome-wide screening identified 9 SNPs associated with preoperative CRT responses. Positive responses (TRG 1-3) were obtained more frequently in patients carrying the reference allele (C) of the SNP CORO2A rs1985859 than in those with the substitution allele (T) (P=.01). Downregulation of CORO2A was significantly associated with reduced early apoptosis by 27% (P=.048) and 39% (P=.023) in RKO and COLO320DM colorectal cancer cells, respectively, as determined by flow cytometry. Reduced radiosensitivity was confirmed by colony-forming assays in the 2 colorectal cancer cells (P=.034 and.015, respectively). The SNP FAM101A rs7955740 was not associated with radiosensitivity in the clinical association analysis. However, downregulation of FAM101A significantly reduced early apoptosis by 29% in RKO cells (P=.047), and it enhanced colony formation in RKO cells (P=.001) and COLO320DM cells (P=.002). Conclusion: CRT-sensitive SNP markers were identified using a novel 3-step process. The candidate marker CORO2A rs1985859 and the putative marker FAM101A rs7955740 may be of value for the prediction of radiosensitivity to preoperative CRT, although further validation is needed in large cohorts. © 2013 Elsevier Inc. All rights reserved.

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