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Abstract. DNA methylation change is known to play a crucial role in early gastric carcinogenesis. The present study aimed to identify and validate the correlation between differentially methylated regions (DMRs) and the subtypes of early gastric cancers (EGCs). Illumina Infinium methylation assay (IIMA; 450K BeadChip kit) was performed on fresh tumor and non-tumor tissues of 12 EGCs to screen the methylation status of 450,000 CpG sites. To evaluate the significance of DNA methylation in each histologic subtype, pyrosequencing assay (PA) was performed on 38 EGCs (18 intestinal-, 12 mixed-and 8 diffuse-type) using 12 genes selected from the screening. Between tumors of the intestinal-type (n=6), and diffuse-(n=4) plus mixed-types (n=2), 169 regions showed significant differences (intensity >3,000, Δβ >0.2) in IIMA. Hierarchical clustering using the 169 DMRs revealed distinct separation between the two groups. In PA using 12 selected genes from the IIMA results, the aberrant methylation statuses of DVL2 (p=0.0186) and ETS1 (p=0.0222) were significantly related to diffuse-and mixed-types rather than the intestinal-type, while C19orf35 (p=0.019) and CNRIP1 (p=0.0473) were related to the diffuse-type rather than intestinal-type, and GAL3ST2 (p=0.0158) and ITGA3 (p=0.0273) were related to the mixedtype rather than the other two types. The methylation of other genes, CLIP4, XKR6, CCDC57, MAML3 and SDC2, was related with age, tumor location, or Helicobacter infection rather than the histologic subtype. Aberrant DNA methylation of certain genes may be independently involved in each histologic subtype of EGC. Furthermore, mixed-type EGCs may be a distinctive histologic subtype based on the different subset of DMRs compared to those of other subtypes. IntroductionDespite its decreasing trend, gastric cancer (GC) still remains one of the most troublesome malignant diseases worldwide. It is the fourth most common cancer and the second leading cause of cancer-related death worldwide (1-3). In Asian countries such as Japan and Korea, it has the highest incidence among all malignancies although its overall survival rate has improved during the last few decades due to extensive screening programs (3,4). Due to the poor prognosis and limited treatment options of advanced GC, it remains a challenging task to determine effective molecular-pathological markers for early diagnosis with appropriate histological classification (5).Lauren classification, which subgroups GCs mainly as two types, intestinal and diffuse, was first introduced in 1965 and has been generally accepted as a distinct and simple histological classification of GCs by most pathologists (6). Since the two major types show distinctively different phenotypic, epidemiologic and biologic characteristics, it is believed that different genetic alterations may be implicated in each histologic type of the classification (7). However, a considerable number of GCs accounting for 10-15% of cases, share the histologic features of these two types and are designated as mixed-type ...

PurposeBoth insulin and insulin-like growth factor (IGF)-1 signaling are key regulators of energy metabolism, cellular growth, proliferation, and survival. The IGF-1 receptor (IGF-1R) is overexpressed in most types of human cancers including renal cell carcinoma (RCC) with poor prognosis. Insulin receptor (IR) shares downstream effectors with IGF-1R; however, the expression and function of IR in the tumorigenesis of renal cancer remains elusive. Therefore, we examined the expression of IR and its prognostic significance in clear cell RCC (CCRCC).Materials and MethodsImmunohistochemical staining for IR was performed on 126 formalin-fixed paraffin-embedded CCRCC tissue samples. Eight of these cases were utilized for western blot analysis. The results were compared with various clinico-pathologic parameters of CCRCC and patient survival.ResultsIR was expressed in the nuclei of CCRCC tumor cells in 109 cases (87.9%). Higher IR expression was significantly correlated with the presence of cystic change, lower Fuhrman nuclear grade, lower pathologic T stage, and lower TNM stage, although it wasn't significantly related to diabetes status and patient survival. Western blot analyses supported the results of the immunohistochemistry studies.ConclusionIR expression in CCRCC may be associated with favorable prognostic factors.

Klotho functions as a tumor suppressor predominantly expressed in renal tubular cells, the origin of clear cell renal cell carcinoma (ccRCC). Altered expression and/or activity of growth factor receptor have been implicated in ccRCC development. Although Klotho suppresses a tumor progression through growth factor receptor signaling including insulin-like growth factor-1 receptor (IGF-1R), the role of Klotho acting on IGF-1R in ccRCC and its clinical relevance remains obscure. Here, we show that Klotho is favorable prognostic factor for ccRCC and exerts tumor suppressive role for ccRCC through inhibiting IGF-1R signaling. Our data shows the following key findings. First, in tumor tissues, the level of Klotho and IGF-1R expression are low or high, respectively, compared to that of adjacent non-neoplastic parenchyma. Second, the Klotho expression is clearly low in higher grade of ccRCC and is closely associated with clinical outcomes in tumor progression. Third, Klotho suppresses IGF-1-stimulated cell proliferation and migration by inhibiting PI3K/Akt pathway. These results provide compelling evidence supporting that Klotho acting on IGF-1R signaling functions as tumor suppressor in ccRCC and suggest that Klotho is a potential carcinostatis substance for ccRCC.

PurposeROS1 is an oncogene, expressed primarily in glioblastomas of the brain that has been hypothesized to mediate the effects of early stage tumor progression. In addition, it was reported that ROS1 expression was observed in diverse cancer tissue or cell lines and ROS1 is associated with the development of several tumors. However, ROS1 expression has not been studied in breast cancer to date. Therefore, we investigated ROS1 expression at the protein and gene level to compare expression patterns and to verify the association with prognostic factors in invasive ductal carcinoma (IDC) of the breast.Materials and MethodsTissue samples from 203 patients were used. Forty-six cases were available for fresh tissue. We performed immunohistochemical staining and real-time polymerase chain reaction (PCR).ResultsROS1 expression was significantly lower in proportion to higher histologic grade, higher mitotic counts, lower estrogen receptor expression, and a higher Ki-67 proliferation index, although ROS1 expression was not significantly associated with the survival rate. The result of real-time PCR revealed similar trends, however not statistically significant.ConclusionHigher ROS1 expression may be associated with favorable prognostic factors of IDC and its expression in IDC is related to the proliferation of tumor cells.