Jeong Mo Bae

The CpG island methylator phenotype may confer a survival benefit in patients with stage II or III colorectal carcinomas receiving fluoropyrimidine-based adjuvant chemotherapy

BackgroundColorectal carcinoma (CRC) with CpG island methylator phenotype (CIMP) is recognized as a distinct subgroup of CRC, and CIMP status affects prognosis and response to chemotherapy. Identification of CIMP status in CRC is important for proper patient management. In Eastern countries, however, the clinicopathologic and molecular characteristics and prognosis of CRCs with CIMP are still unclear.MethodsA total of 245 patients who underwent their first surgical resection for sporadic CRC were enrolled and CIMP status of the CRCs was determined using the quantitative MethyLight assay. The clinicopathologic and molecular characteristics were reviewed and compared according to CIMP status. In addition, the three-year recurrence-free survival (RFS) of 124 patients with stage II or stage III CRC was analyzed in order to assess the effectiveness of fluoropyrimidine-based adjuvant chemotherapy with respect to CIMP status.ResultsCIMP-high CRCs were identified in 34 cases (13.9%), and were significantly associated with proximal tumor location, poorly differentiated carcinoma, mucinous histology, and high frequencies of BRAF mutation, MGMT methylation, and MSI-high compared to CIMP-low/negative carcinomas. For patients with stage II or III CIMP-low/negative CRCs, no significant difference was found in RFS between those undergoing surgery alone and those receiving surgery with fluoropyrimidine-based adjuvant chemotherapy. However, for patients with CIMP-high CRCs, patients undergoing surgery with fluoropyrimidine-based adjuvant chemotherapy (n = 17; three-year RFS: 100%) showed significantly better RFS than patients treated with surgery alone (n = 7; three-year RFS: 71.4%) (P = 0.022).ConclusionsOur results suggest that selected patients with CIMP-high CRC may benefit from fluoropyrimidine-based adjuvant chemotherapy with longer RFS. Further large scale-studies are required to confirm our results.

ALU and LINE‐1 hypomethylations in multistep gastric carcinogenesis and their prognostic implications

Focal CpG island hypermethylation and diffuse genomic hypomethylation signify the changes in the DNA methylation status in cancer cells. ALU and LINE‐1 repetitive DNA elements comprise ∼28% of the human genome. PCR‐based measurements of these repetitive DNA elements can be used as a surrogate marker of the genomewide methylation content. Our study aimed to identify the timing of ALU and LINE‐1 hypomethylations during multistep gastric carcinogenesis and their prognostic implications in gastric cancer (GC). In our study, we analyzed the methylation statuses of ALU and LINE‐1 in 249 cases of gastric biopsy samples and another independent set of 198 cases of advanced GC by pyrosequencing. Regardless of the Helicobacter pylori infection status, a significant decrease in the ALU methylation levels was noted during the transitions from chronic gastritis to intestinal metaplasia and from gastric adenoma to GC. LINE‐1 methylation decreased during the transition from intestinal metaplasia to gastric adenoma and no further decrease occurred during the transition from gastric adenoma to GC. A low LINE‐1 methylation status was strongly associated with poor prognosis in GC. A multivariate analysis revealed that LINE‐1 methylation status was an independent prognostic factor. Our findings suggest that ALU and LINE‐1 hypomethylations are early events during multistep gastric carcinogenesis. Furthermore, the LINE‐1 methylation status can be used as a molecular biomarker to define a subset of GC patients with poor prognosis.

Methylation and microsatellite status and recurrence following adjuvant FOLFOX in colorectal cancer

The prognostic impact of CpG island methylator phenotype (CIMP) and microsatellite instability (MSI) on the treatment outcome of colon cancer patients receiving adjuvant 5‐fluorouracil/leucovorin/oxaliplatin (FOLFOX) is unclear. We investigated CIMP and MSI status in colorectal cancer patients treated with adjuvant FOLFOX. Stages II and III sporadic colorectal cancer patients who underwent curative resection followed by adjuvant FOLFOX were included. Eight CpG island loci (CACNA1G, CRABP1, IGF2, MLH1, NEUROG1, CDKN2A (p16), RUNX3 and SOCS1) and five microsatellite markers were examined. Disease‐free survival (DFS) was analyzed according to CIMP and MSI status. A total of 322 patients were included: male/female 192/130, median age 61 years (range 30–78), proximal/distal location 118/204 and Stages II/III 43/279. CIMP status was high in 25 patients (7.8%) and 21 patients (6.5%) had MSI‐high tumor. CIMP/MSI status was not significantly associated with DFS: 3‐year DFS 100% in CIMP(−)/MSI(+), 84% in CIMP(−)/MSI(−), 82% in CIMP(+)/MSI(−) and 75% in CIMP(+)/MSI(+) (p = 0.33). Results of exploratory analysis showed that concurrent methylation at NEUROG1 and CDKN2A (p16) was associated with shorter DFS: 3‐year DFS 69% in NEUROG1(+)/CDKN2A (p16)(+) versus 87% in NEUROG1(−)/CDKN2A (p16)(−) (p = 0.006). In conclusion, concurrent methylation of NEUROG1 and CDKN2A (p16) is associated with recurrence following adjuvant FOLFOX in Stages II/III colorectal cancer.

Loss of CDX2/CK20 expression is associated with poorly differentiated carcinoma, the CpG island methylator phenotype, and adverse prognosis in microsatellite-unstable colorectal cancer.

Several previous studies have demonstrated that the CDX2-negative (CDX2−) and/or CK20-negative (CK20−) phenotypes of colorectal cancers (CRCs) might be associated with high levels of microsatellite instability (MSI-H). The aim of this study was to investigate the clinicopathologic and molecular features of MSI-H CRCs with different CDX2/CK20 expression statuses. The CDX2 and CK20 expression statuses were immunohistochemically evaluated in 109 MSI-H CRC tissue samples, and the correlations of these statuses with clinicopathologic, molecular, and survival data were statistically analyzed. Of the 109 MSI-H CRCs, 15 were CDX2− (13.8%), and 19 were CK20− (17.4%). The simultaneous loss of CDX2 and CK20 expression (CDX2−/CK20−) was observed in 9 cases (8.3%). CDX2 loss was correlated with lymph node metastasis, poor differentiation, MLH1 loss, the mutation of BRAF, and CpG island methylator phenotype-high (CIMP-H) status. Right-sided tumor location, nodal metastasis, poor differentiation, and CIMP-H status were significant characteristics of CK20− tumors. The CDX2−/CK20− phenotype was associated with older age (above 56 y), higher stage (stage III or IV), deep invasion (pT3 or pT4), lymph node metastasis (pN1 or pN2), poor differentiation (nonmedullary/non–signet ring cell type), the mutation of BRAF, and CIMP-H status among MSI-H CRCs. Patients with CDX2−/CK20− tumors exhibited worse overall and disease-free survival compared with the patients with CDX2+ and/or CK20+ tumors (P<0.001). In the multivariate analysis for disease-free survival, the CDX2−/CK20− phenotype was an independent prognostic factor for MSI-H CRC (P=0.030, hazard ratio=3.288). The CDX2−/CK20− phenotype defines a distinct subgroup of MSI-H CRCs with poor differentiation, CIMP-H status, and unfavorable prognosis.

Loss of CDX2 expression is associated with poor prognosis in colorectal cancer patients

AIM To investigate the clinicopathologic characteristics and prognostic implications associated with loss of CDX2 expression in colorectal cancers (CRCs). METHODS We immunohistochemically evaluated CDX2 expression in 713 CRCs and paired our findings to clinicopathologic and molecular characteristics of each individual. Endpoints included cytokeratin 7 and CK20 expression, microsatellite instability, CpG island methylator phenotype, and KRAS and BRAF mutation statuses. Univariate and multivariate survival analysis was performed to reveal the prognostic value of CDX2 downregulation. RESULTS CDX2 expression was lost in 42 (5.9%) patients. Moreover, loss of CDX2 expression was associated with proximal location, infiltrative growth, advanced T, N, M and overall stage. On microscopic examination, loss of CDX2 expression was associated with poor differentiation, increased number of tumor-infiltrating lymphocytes, luminal serration and mucin production. Loss of CDX2 expression was also associated with increased CK7 expression, decreased CK20 expression, CpG island methylator phenotype, microsatellite instability and BRAF mutation. In a univariate survival analysis, patients with loss of CDX2 expression showed worse overall survival (P < 0.001) and progression-free survival (P < 0.001). In a multivariate survival analysis, loss of CDX2 expression was an independent poor prognostic factor of overall survival [hazard ratio (HR) = 1.72, 95%CI: 1.04-2.85, P = 0.034] and progression-free survival (HR = 1.94, 95%CI: 1.22-3.07, P = 0.005). CONCLUSION Loss of CDX2 expression is associated with aggressive clinical behavior and can be used as a prognostic marker in CRCs.

Differential clinicopathological features in microsatellite instability-positive colorectal cancers depending on CIMP status

Microsatellite instability-positive (MSI+) colorectal cancers (CRCs) are divided into CpG island methylator phenotype-positive (CIMP+) and CpG island methylator phenotype-negative (CIMP−) tumors. The repertoire of inactivated genes in CIMP+/MSI+ CRCs overlaps with but is likely to differ from that of CIMP−/MSI+ CRCs. Because epigenotypic differences are likely to be manifested as phenotypic differences, CIMP+/MSI+ CRCs are expected to differ from CIMP−/MSI+ CRCs in some clinicopathological features. This study aimed to characterize both common and different features between the two subtypes. A total of 72 MSI+ CRCs were analyzed for their methylation status in eight CIMP panel markers using MethyLight assay. CIMP+/MSI+ and CIMP−/MSI+ CRCs were compared regarding clinicopathologic features and mutation in KRAS/BRAF. An independent set of MSI+ CRCs (n = 97) was analyzed for their relationship of CIMP+ status with clinical outcome. Eighteen cases (25%) were CIMP+, and this CIMP+ subtype was highly correlated with older age (P < 0.001). Polypoid gross appearance without ulceration was observed only in CIMP−/MSI+ CRCs (18.5%, P = 0.057). CIMP+/MSI+ CRCs were closely associated with poor differentiation, medullary appearance, signet ring cell appearance, and acinar-form appearance, whereas the CIMP−/MSI+ subtype was closely associated with intraglandular eosinophilic mucin and stratified nuclei (all P values <0.05). Patients with CIMP+/MSI+ CRCs showed worse overall survival than patients with CIMP−/MSI+ CRCs. Our results demonstrate heterogeneity in the clinicopathological features of MSI+ CRCs depending on CIMP status. The observation that CIMP+ and CIMP− subtypes showed different clinical behaviors may provide a clue for establishing subtype-specific therapeutic strategies for these two subtypes.

The role of hand-assisted laparoscopic distal gastrectomy for distal gastric cancer

BackgroundThe aim of this study was to evaluate the role of hand-assisted distal gastrectomy (HALDG) for gastric cancer.MethodsThis study prospectively enrolled 16 patients who underwent HALDG for early gastric cancer and matched them individually by sex, age, and body mass index to patients who underwent laparoscopically assisted distal gastrectomy (LADG) or open distal gastrectomy (ODG). Surgical outcomes were compared among the surgical methods.ResultsThe mean operating time was the longest for the HALDG group, whereas wound size of the HALDG group was intermediate between that of the LADG and the ODG groups. The other surgical outcomes, such as the number of harvested lymph nodes, were not different among the groups.ConclusionsAccording to the findings, HALDG may not be as beneficial for patients with early gastric cancer as has been previously suggested. However, because of easier hand–eye coordination, HALDG may be an excellent bridge learning technique as a surgeon gains experience in laparoscopic gastrectomy.

Epigenetic alterations in colorectal cancer: the CpG island methylator phenotype

DNA methylation is one of the key mechanisms of epigenetic modification, and genome-wide hypomethylation and CpG island hypermethylation are characteristics of cancer cells. The CpG island methylator phenotype (CIMP) is a distinctive subtype of colorectal cancers (CRCs) that show concordant hypermethylation of numerous promoter CpG island loci. CIMP-positive CRCs are associated with a proximal location in the colon, microsatellite instability, BRAF mutation and a relatively poor clinical outcome. CIMP-positive CRCs have their own precursor lesions, serrated adenomas, distinct from conventional adenomas which progress and transform into CIMP-negative CRCs. Although the existence of CIMP-positive CRCs is generally accepted, there has been controversy over technical issues with gene markers, the methodology used to define CIMP, and the prognostic or predictive role of CIMP. This review addresses recent advances in the field of CIMP-related research.

DNA methylation changes in ex-adenoma carcinoma of the large intestine

Ex-adenoma carcinoma (EAC) is a carcinoma with contiguous adenoma element in its vicinity which provides a morphological evidence for adenoma–carcinoma sequence. During multistep colorectal carcinogenesis, promoter CpG island hypermethylation has been known to increase in a stepwise manner whereas diffuse genomic hypomethylation has been known to be an early event and not progress. However, some controversies exist. EAC is a good model to study the timing of hypermethylation and hypomethylation changes during multistep carcinogenesis, which this study aimed to elucidate. We analyzed 39 cases of EAC for their methylation status in eight DNA methylation markers of CpG island methylator phenotype (CIMP) panel, ten CIMP-nonrelated, cancer-specific markers, and three repetitive DNA elements (ALU, LINE-1, and SAT2) using MethyLight assay or combined bisulfite restriction analysis. Twenty-two cases of cancers had contiguous tubulovillous adenomas and 17 cases had contiguous tubular adenomas. Regardless of CIMP markers or nonrelated markers, a significant increase in the number of methylated genes was found from normal mucosa to adenoma, whereas no increase was found from adenoma to carcinoma. Both ALU and LINE-1 showed a significant decrease of methylation levels from normal mucosa to adenoma (p < 0.05), but there is no difference between adenoma and cancer. However, SAT2 methylation level exhibited a stepwise decrease from normal mucosa to adenoma to cancer. Our findings suggest that morphological progression from traditional adenoma to carcinoma does not appear to be accompanied by increases in promoter CpG island hypermethylation or repetitive DNA hypomethylation, except for SAT2 hypomethylation which showed continuous progression during multistep carcinogenesis.

Adverse prognostic impact of the CpG island methylator phenotype in metastatic colorectal cancer.

Background:The association between the CpG island methylator phenotype (CIMP) and clinical outcomes in metastatic colorectal cancer remains unclear. We investigated the prognostic impact of CIMP in patients with metastatic colorectal cancer treated with systemic chemotherapy.Methods:Eight CIMP-specific promoters (CACNA1G, IGF2, NEUROG1, RUNX3, SOCS1, CDKN2A, CRABP1, and MLH1) were examined. The CIMP status was determined by the number of methylated promoters as high (⩾5), low (1–4), and negative (0).Results:A total of 153 patients were included (men/women, 103/50; median age, 61 years; range, 22–80 years). The CIMP status was negative/low/high in 77/ 69/7 patients, respectively. Overall survival (OS) was significantly different among the three CIMP groups, with median values of 35.7, 22.2, and 9.77 months for the negative, low, and high groups, respectively (P<0.001). For patients treated with fluoropyrimidine and oxaliplatin first-line chemotherapy (N=128), OS and progression-free survival (PFS) were significantly different among the three CIMP groups; the median OS was 37.9, 23.8, and 6.77 months for the negative, low, and high groups, respectively (P<0.001), while the median PFS was 9.97, 7.87, and 1.83 months, respectively (P=0.002). Response rates were marginally different among the three CIMP groups (53.4% vs 45.1% vs 16.7%, respectively; P=0.107). For patients treated with fluoropyrimidine and irinotecan second-line chemotherapy (N=86), only OS showed a difference according to the CIMP status, with median values of 20.4, 13.4, and 2.90 months for the negative, low, and high groups, respectively (P<0.001).Conclusions:The CIMP status is a negative prognostic factor for patients with metastatic colorectal cancer treated with chemotherapy.