Hogeun Kim

RORα Attenuates Wnt/β-Catenin Signaling by PKCα-Dependent Phosphorylation in Colon Cancer

Wnt family members play diverse roles in development and disease. Noncanonical Wnt ligands can inhibit canonical Wnt signaling depending on the cellular context; however, the underlying mechanism of this antagonism remains poorly understood. Here we identify a specific mechanism of orphan nuclear receptor RORalpha-mediated inhibition of canonical Wnt signaling in colon cancer. Wnt5a/PKCalpha-dependent phosphorylation on serine residue 35 of RORalpha is crucial to link RORalpha to Wnt/beta-catenin signaling, which exerts inhibitory function of the expression of Wnt/beta-catenin target genes. Intriguingly, there is a significant correlation of reduction of RORalpha phosphorylation in colorectal tumor cases compared to their normal counterpart, providing the clinical relevance of the findings. Our data provide evidence for a role of RORalpha, functioning at the crossroads between the canonical and the noncanonical Wnt signaling pathways, in mediating transrepression of the Wnt/beta-catenin target genes, thereby providing new approaches for the development of therapeutic agents for human cancers.

Tumor Volume Changes Assessed by Three-Dimensional Magnetic Resonance Volumetry in Rectal Cancer Patients After Preoperative Chemoradiation: The Impact of the Volume Reduction Ratio on the Prediction of Pathologic Complete Response

PURPOSE The aim of this study was to determine the correlation between tumor volume changes assessed by three-dimensional (3D) magnetic resonance (MR) volumetry and the histopathologic tumor response in rectal cancer patients undergoing preoperative chemoradiation therapy (CRT). METHODS AND MATERIALS A total of 84 patients who underwent preoperative CRT followed by radical surgery were prospectively enrolled in the study. The post-treatment tumor volume and tumor volume reduction ratio (% decrease ratio), as shown by 3D MR volumetry, were compared with the histopathologic response, as shown by T and N downstaging and the tumor regression grade (TRG). RESULTS There were no significant differences in the post-treatment tumor volume and the volume reduction ratio shown by 3D MR volumetry with respect to T and N downstaging and the tumor regression grade. In a multivariate analysis, the tumor volume reduction ratio was not significantly associated with T and N downstaging. The volume reduction ratio (>75%, p = 0.01) and the pretreatment carcinoembryonic antigen level (< or =3 ng/ml, p = 0.01), but not the post-treatment volume shown by 3D MR (< or = 5 ml), were, however, significantly associated with an increased pathologic complete response rate. CONCLUSION More than 75% of the tumor volume reduction ratios were significantly associated with a high pathologic complete response rate. Therefore, limited treatment options such as local excision or simple observation might be considered after preoperative CRT in this patient population.

Cetuximab in combination with 5-fluorouracil, leucovorin and irinotecan as a neoadjuvant chemotherapy in patients with initially unresectable colorectal liver metastases

Background: The efficacy and safety of a combination of cetuximab, irinotecan, and 5-fluorouracil/leucovorin (FOLFIRI) in downsizing unresectable colorectal liver metastases was investigated. Patients and Methods: Patients with unresectable colorectal liver metastases with or without resectable extrahepatic metastasis were enrolled. 23 patients initially received 400 mg/m2 of cetuximab, followed by a weekly infusion of 250 mg/m2 and a biweekly dose of irinotecan (180 mg/m2), with 5-fluorouracil both by bolus (400 mg/m2) and by a 46-h infusion (total of 2,400 mg/m2) with leucovorin (400 mg/m2). Results: The overall response rate was 39.1% (n = 9; 95% confidence interval (CI): 17.6-60.7%). The most common grade 3-4 toxicities were skin reactions (30.4%) and diarrhea (26.1%). The rate of conversion to resectable liver metastases was 30.4% (n = 7; 95% CI: 10.1-50.8%). The factors found to be significantly associated with R0 resection were lower serum carcinoembryonic antigen levels after chemotherapy (p = 0.039), being chemonaive (p = 0.002), and showing a higher incidence of grade 3-4 skin toxicity (p = 0.011). Conclusions: Cetuximab with FOLFIRI may be an effective and safe treatment option for downsizing unresectable colorectal liver metastases.

Current trends in the epidemiological and pathological characteristics of gastrointestinal stromal tumors in Korea, 2003-2004.

Despite remarkable progress in understanding and treating gastrointestinal stromal tumors (GISTs) during the past two decades, the pathological characteristics of GISTs have not been made clear yet. Furthermore, concrete diagnostic criteria of malignant GISTs are still uncertain. We collected pathology reports of 1,227 GISTs from 38 hospitals in Korea between 2003 and 2004 and evaluated the efficacy of the NIH and AFIP classification schemes as well as the prognostic factors among pathologic findings. The incidence of GISTs in Korea is about 1.6 to 2.2 patients per 100,000. Extra-gastrointestinal GISTs (10.1%) are more common in Korea than in Western countries. In univariate analysis, gender, age, tumor location, size, mitosis, tumor necrosis, vascular and mucosal invasions, histologic type, CD34 and s-100 protein expression, and classifications by the NIH and AFIP criteria were found to be significantly correlated with patients survival. However, the primary tumor location, stage and classification of the AFIP criteria were prognostically significant in predicting patients survival in multivariate analysis. The GIST classification based on original tumor location, size, and mitosis is more efficient than the NIH criteria in predicting patients survival, but the mechanism still needs to be clarified through future studies.

RASSF1A hypermethylation and its inverse correlation with BRAF and/or KRAS mutations in MSI‐associated endometrial carcinoma

Both hypermethylation of the tumor suppressor gene RASSF1A and activating mutations of the KRAS and/or BRAF gene have been reported in a variety of human cancers. To investigate these epigenetic and genetic alterations in endometrial carcinoma (EC), we examined their frequency in 4 uterine EC cell lines and in 75 sporadic primary ECs. Using methylation specific PCR, we found RASSF1A methylation in 25 of 75 (33.3%) ECs. RASSF1A methylation was significantly associated with microsatellite instability (MSI, p < 0.001) and also with hMLH1 methylation (p < 0.001). KRAS mutations were detected in 14 of 75 (18.7%) ECs. BRAF mutations were identified in only 3 of 75 (4.0%) ECs and were not found in ECs with KRAS mutations or RASSF1A methylation. RASSF1A methylation was more frequent in KRAS mutation‐negative ECs than in KRAS mutation‐positive ECs (37.7% vs 14.3%), but this inverse correlation is not statistically significant (p = 0.122). However, we observed that RASSF1A methylation was inversely correlated with KRAS and/or BRAF mutations (p = 0.028) in MSI‐negative ECs, while this inverse correlation disappeared in MSI‐positive ECs. Furthermore, in MSI‐positive ECs, 2 cases of concomitant RASSF1A methylation and KRAS mutation were found. Taken together, these results provide strong evidence that, in EC tumorigenesis, RASSF1A promoter hypermethylation is as important as KRAS mutations in activating the RAS pathway.

Assessment of biomarkers in paired primary and recurrent colorectal adenocarcinomas

Abstract Purpose: Recurrent colorectal cancers respond poorly to anticancer treatment including radiotherapy. To better understand the biological characteristics of the recurrent colorectal tumor, we investigated various biomarkers regulating cell proliferation and cell loss in paired primary and recurrent colorectal tumor specimens within each individual. Methods and Materials: From a total of 11 colorectal adenocarcinoma patients, 22 specimens of paired primary and recurrent tumors were obtained for analysis. Apoptosis was evaluated by TUNEL labeling of apoptotic DNA fragmentation. Other biomarkers including proliferating cell nuclear antigen (PCNA), p53, WAF1, p34cdc2, and cyclins B1 and D1 were analyzed by immunohistochemical stains. Results: PCNA index (PCNAI) showed an increase in 6 and a decrease in 5 recurrent tumors compared to primary tumors. Median PCNAI in primary and recurrent tumors were 33.5 and 48.3, respectively ( p = 0.16). In contrast, the apoptotic index (AI) decreased in 9 of 11 recurrent tumors compared to primary tumors. Median AI decreased from 4.3 in primary tumors to 1.4 in recurrent tumors ( p = 0.04). The p53 expression increased in more than half of recurrent tumors compared to primary tumors. Mean staining score increased from 0.7 in primary tumors to 1.2 in recurrent tumors ( p = 0.059). WAF1 and cyclin B1 did not show significant change. In contrast, both cyclin D1 and p34cdc2 increased significantly in recurrent tumors. These two biomarkers showed increased expression in 8 (cyclin D1) and 7 (p34cdc2) recurrent tumors, respectively, compared to their primary counterparts. Mean staining scores of both biomarkers in recurrent tumors increased by more than twofold compared to those in primary tumors and these differences were statistically significant (cyclin D1, p = 0.007; p34cdc2, p = 0.008). Conclusion: This study showed significantly decreased apoptosis in recurrent colorectal tumors compared to their primary counterparts. The underlying regulatory mechanisms included increased expression of p53 and altered cell cycle regulators such as increased cyclin D1 and p34cdc2. With further study, it may be used for developing a new therapeutic strategy for the treatment of recurrent colorectal cancer.

Cyclooxygenase-2 Expression in Pretreatment Biopsy as a Predictor of Tumor Responses After Preoperative Chemoradiation in Rectal Cancer

OBJECTIVE To determine whether cyclooxygenase-2 (COX-2) expression in pretreatment biopsy specimens is a useful predictive marker of tumor response to preoperative chemoradiation (CRT) in rectal cancer. DESIGN Case series. SETTING Colorectal cancer clinic. PATIENTS Thirty patients with locally advanced rectal cancer were given preoperative CRT of 5040 cGy for 6 weeks with concurrent administration of 5-fluorouracil and leucovorin. MAIN OUTCOME MEASURES Immunohistochemical staining for COX-2 and angiogenesis markers (vascular endothelial growth factor, thymidine phosphorylase, and CD34) were performed on biopsy specimens obtained before preoperative CRT. The responses to preoperative CRT were assessed by radiologic downsizing (measured using magnetic resonance imaging volumetry), histopathologic downstaging, and a 3-point tumor regression grade (TRG) evaluation, based on the ratio of residual cancer to fibrosis. RESULTS Tumor downstaging was seen in 15 patients (50.0%) and nodal downstaging was noted in 14 patients (46.7%). Tumor regression grade 1 (good response) was shown by 7 patients (23.3%); TRG2 (moderate response) in 15 patients (50.0%); and TRG3 (poor response) in 8 patients (26.7%). Patients with COX-2 overexpression were more likely to show a poor TRG (P = .003) and were less likely to achieve histopathologic nodal downstaging (P = .03) than those with normal COX-2 expression. Vascular endothelial growth factor overexpression was found to be associated with COX-2 overexpression (P = .02). CONCLUSIONS Overexpression of COX-2 in pretreatment biopsies might be predictive of poor tumor regression after preoperative CRT. Administration of COX-2 inhibitors to patients with COX-2 overexpression, in an attempt to improve response rate to preoperative CRT, warrants assessment in clinical trials.

Signet Ring Cell Carcinoma of the Extrahepatic Bile Duct

Most tumors affecting the extrahepatic bile duct are adenocarcinomas; the other histologic types occur only rarely. We herein report the extremely rare case of signet ring cell carcinoma (SRCC) originating from the extrahepatic bile duct. A 55-year-old man was hospitalized for jaundice and pruritus. Computed tomography and positron emission tomography suggested the presence of distal extrahepatic bile-duct cancer. He underwent a pylorus preserving pancreaticoduodenectomy. A histologic study confirmed a signet ring cell neoplasm of the distal common bile duct. Because the upper resection margin was invaded by the tumor, he received postoperative concurrent chemoradiotherapy and four cycles of chemotherapy. The patient has survived with no evidence of recurrence for 2 years. This is the second case of primary SRCC of the distal extrahepatic bile duct reported in the literature; further reports of cases are warranted to determine the nature of SRCC in the extrahepatic bile duct.

Adenosine triphosphate-based chemotherapy response assay-guided chemotherapy in unresectable colorectal liver metastasis

Background:This study aims to evaluate the effectiveness of adenosine triphosphate-based chemotherapy response assay (ATP-CRA)-guided neoadjuvant chemotherapy for increasing resectability in patients with unresectable colorectal liver metastasis.Patients and methods:Patients were randomised into two groups: Group A was treated by conventional chemotherapy regimen and Group B was treated by chemotherapy regimen according to the ATP-CRA. Three chemotherapeutic agents (5-fluorouracil, oxaliplatin and irinotecan) were tested by ATP-CRA and more sensitive agents were selected. Either FOLFOX or FOLFIRI was administered. Between Group A and B, treatment response and resectability were compared.Results:Between November 2008 and October 2010, a total 63 patients were randomised to Group A (N=32) or Group B (N=31). FOLFOX was more preferred in Group A than in Group B (26 out of 32 (81.3%) vs 20 out of 31 (64.5%)). Group B showed better treatment response than Group A (48.4% vs 21.9%, P=0.027). The resectability of hepatic lesion was higher in Group B (35.5% vs 12.5%, P=0.032). Mean duration from chemotherapy onset to the time of liver resection was 11 cycles (range 4–12) in Group A and 8 cycles (range 8–16) in Group B.Conclusion:This study showed that tailored-chemotherapy based on ATP-CRA could improve the treatment response and resectability in initially unresectable colorectal liver metastasis.

Colon perforation in hyperimmunoglobulin E syndrome

Colon perforation from hyperimmunoglobulin E syndrome is very rare, and only one case has been reported in the English-language literature. Herein, the authors report another case of colon perforation experienced in hyperimmunoglobulin E syndrome. The patient was an 8-year-old girl with frequent infection, eczematoid dermatitis, and an increased serum level of immunoglobulin E. During admission, panperitonitis developed caused by colon perforation. Treatment was resection of the perforated segment of the colon and a double-barrel colostomy. The patient has been doing well 18 months after treatment.