Identification of Early Events in Serrated Pathway Colorectal Tumorigenesis by Using Digital Spatial Profiling.

INTRODUCTION: The colorectal serrated pathway involves precursor lesions known as sessile serrated lesions (SSL) and traditional serrated adenomas (TSA). Mutations in BRAF or KRAS are crucial early events in this pathway. Additional genetic and epigenetic changes contribute to the progression of these lesions into high-grade lesions and, eventually, invasive carcinoma. METHODS: We employed digital spatial profiling to investigate the transcriptional changes associated with SSL and TSA. The genes identified are confirmed by immunohistochemical (IHC) staining. Colorectal cancer (CRC) cell lines with CEACAM6 overexpression and knockdown were established to study the roles of CEACAM6 on tumorigenesis of CRC. RESULTS: Ten genes were upregulated in SSL and TSA, and seven were upregulated in both types of lesions. IHC staining confirmed overexpression of CEACAM6, LCN2, KRT19, and lysozyme in SSL and TSA. CEACAM6 expression is an early event in the serrated pathway but a late event in the conventional pathway. Using cell line models, we confirmed that CEACAM6 promotes CRC cells' proliferation, migration, and invasion abilities. CONCLUSION: These results highlight that the transcriptional changes in the early stages of tumorigenesis exhibit relative uniformity. Identifying these early events may hold significant promise in elucidating the mechanisms behind tumor initiation.

Expression of LEF1 is an independent prognostic factor for patients with oral squamous cell carcinoma.

BACKGROUND/PURPOSE: Lymphoid-enhancing factor 1 (LEF1) is a transcription factor mediating Wnt/ß-catenin signaling. In this study, we analyzed the clinicopathologic significance of LEF1 expression in oral squamous cell carcinoma (OSCC). METHODS: Expression levels of LEF1 in 135 cases of OSCC were determined by immunohistochemistry. The results were correlated with clinicopathologic parameters and patient outcome. RESULTS: LEF1 was only occasionally detected in basal and parabasal cells of nontumorous squamous epithelium. Overexpression of LEF1 was observed in 33 of 135 OSCCs (24%). LEF1 was more frequently expressed in moderately to poorly differentiated cancer (p = 0.0035) and was associated with lymphovascular invasion (p = 0.0252). Overexpression of LEF1 was significantly associated with poor prognosis (p = 0.0176, hazard ratio = 1.96, 95% CI = 1.02-3.75). Multivariate analysis revealed LEF1expression and margin status to be the significant independent predictors for overall survival. CONCLUSION: Our study suggests LEF1 expression in OSCC may play an important role in tumor progression and can be served as a predictor of poor prognosis for patients with OSCC.

Beta-catenin expression and mutation in adult and pediatric Wilms' tumors.

Wilms' tumor is the most common pediatric renal neoplasm, but its occurrence in adults is very rare. In contrast to pediatric Wilms' tumor (PWT), very little is known about the pathogenesis of adult Wilms' tumor (AWT). Despite there currently being no morphological difference between AWT and PWT, a cytogenetic study has suggested that the pathogenesis of AWT might be different from that of PWT. Although dysregulation of the Wnt pathway has been implicated in PWT, its role in AWT has never been investigated. To investigate the role of dysregulation of the Wnt pathway in AWT, tumor samples from 4 AWTs and 19 PWTs were surveyed for subcellular localization of beta-catenin by immunohistochemistry and potential mutation of the beta-catenin gene by sequencing. Nuclear translocation of beta-catenin was found in one out of four cases of AWT, but none of them carried mutation of the beta-catenin gene. By comparison, nuclear translocation for beta-catenin and mutation of the beta-catenin gene were present in 53% (10/19) and 15.8% (3/19) of PWTs, respectively. Of the three mutations identified, we found a novel mutation combining a silent mutation (TCT to TCC, Ser37Ser) and an in-frame six-base-pair deletion (del GGTGCC, del Gly38Ala39). This report suggests that dysregulation of the Wnt pathway might also play a role in the pathogenesis of AWT.

Cadherin-17 is a useful diagnostic marker for adenocarcinomas of the digestive system.

Cadherin-17, also called liver-intestine cadherin, is a calcium-dependent transmembrane glycoprotein that mediates cell-cell adhesion in intestinal epithelium. Expression of cadherin-17 was reported in gastric, pancreatic, and colorectal adenocarcinomas but not in other tumors. Whether cadherin-17 can be used as a marker for diagnosis of cancers is still unclear. In this study, we used immunohistochemical methods to stain cadherin-17 in tissue arrays containing most normal tissues and 518 carcinomas from many anatomic sites. Among normal tissues, the expression of cadherin-17 was limited to epithelial cells of small intestine and colon. Colorectal adenocarcinomas showed staining in 96% of cases and most of them had strong and diffuse staining. Gastric, pancreatic, and biliary adenocarcinomas showed diffuse or scattered staining in about 25-50% of cases. Fewer than 1% of carcinomas outside the digestive system were positive for cadherin-17. When a two-marker, Cadherin-17/cytokeratin 7, profile was used, 37 of 38 (97%) cadherin-17(+)/cytokeratin 7(-) tumors were colorectal adenocarcinomas; 49 of 56 (86%) cadherin-17(+)/cytokeratin 7(+) tumors were gastric, pancreatic, or biliary adenocarcinomas. Our results show that cadherin-17 is a useful immunohistochemical marker for diagnosis of adenocarcinomas of the digestive system.

Nuclear translocation of beta-catenin protein but absence of beta-catenin and APC mutation in gastrointestinal carcinoid tumor.

BACKGROUND: Carcinoid tumors are a group of heterogeneous tumors with neuroendocrine differentiation and are mainly located in the gastrointestinal tract. A high frequency of cytoplasmic accumulation and/or nuclear translocation of beta-catenin with frequent mutations of exon 3 of beta-catenin gene in gastrointestinal carcinoid tumor has been previously described, but the role of Wnt/beta-catenin/APC pathway in the genesis of carcinoid tumor remains largely unknown. METHODS: To further characterize the role of Wnt/beta-catenin/APC pathway, we investigated 91 gastrointestinal carcinoid tumors and, for comparison, 26 extragastrointestinal carcinoid tumors by immunohistochemical detection of beta-catenin protein and direct sequencing of exon 3 of the beta-catenin gene and exon 15 of the APC gene. RESULTS: Cytoplasmic accumulation and/or nuclear translocation of beta-catenin were found in 27 gastrointestinal carcinoid tumors (29.7%) but not in any extragastrointestinal carcinoid tumors. Interestingly, neither beta-catenin nor APC gene mutation was detected in all of the cases with nuclear expression of beta-catenin. CONCLUSIONS: Our results indicate that the role beta-catenin plays in the genesis of gastrointestinal and extragastrointestinal carcinoid tumors is different. Nuclear expression of beta-catenin does not occur in extragastrointestinal carcinoid tumors, and mutation of exon 3 of beta-catenin gene and exon 15 of APC gene does not contribute to the activation of Wnt/beta-catenin/APC pathway in gastrointestinal carcinoid tumors.

Overexpression of pituitary tumor-transforming gene-1 in hepatocellular carcinoma.

BACKGROUND/AIMS: Pituitary tumor-transforming gene-1, a recently identified proto-oncogene, was reported to be highly expressed in various tumors, such as tumors of the pituitary gland, adrenal gland, colon, ovary, endometrium, uterus, and kidney. The purpose of this study was to investigate the clinicopathologic significance of PTTG1 expression in hepatocellular carcinoma. METHODOLOGY: Expression of PTTG1 mRNA was evaluated by RT-PCR in 147 HCCs and 103 paired nontumorous liver tissues. RESULTS: PTTG1 was found overexpressed in 80 of 147 (61%) HCCs. Overexpression of PTTG1 correlated with alpha-fetoprotein elevation (p<0.022) and higher tumor stage (stage IIIB-IV) tumors (p<0.009), but not with tumor grade, size, and survival. CONCLUSIONS: The results show that PTTG1 is overexpressed frequently in HCC, and correlated high stage tumors, indicating that overexpression of PTTG1 plays a role in the development and progression of HCC.

CD24 expression is a prognostic factor in intrahepatic cholangiocarcinoma.

CD24, a cell surface protein originally identified in hematological malignancy, were found to be expressed in a large variety of solid tumors. It can function as a ligand for P-selectin, an adhesion receptor on activated endothelial cells and platelets. Overexpression of CD24 enhances the metastatic potential of cancer cells. We examined the expression of CD24 in 70 intrahepatic cholangiocarcinomas by immunohistochemistry and correlated the expression with clinicopathological parameters. CD24 was expressed in 36 of 70 (51%) intrahepatic cholangiocarcinomas. The expression did not significantly correlate the tumor size, stage, lymph node and distant metastasis. Patients with CD24 positive tumors had significant shorter survival time. In a multivariant analysis, CD24 expression and tumor stage were independent prognostic factors. Our data suggest that CD24 expression in intrahepatic cholangiocarcinoma is a novel prognostic marker for intrahepatic cholangiocarcinoma.

Absence of epidermal growth factor receptor exon 18-21 mutation in hepatocellular carcinoma.

The epidermal growth factor receptor (EGFR) is overexpressed in many epithelial tumors and plays an important role in the tumorigenesis of these tumors. Inhibitors of EGFR reduce the proliferation rate of cancers and are promising therapeutic agents of cancers. Recently, two studies have identified somatic mutations in the exons 18-21 of EGFR that were strongly correlated with robust clinical response to gefitinib treatment in patients with non-small cell lung cancer. To investigate whether EGFR mutation is involved in the tumorigenesis of hepatocellular carcinoma (HCC), we performed direct sequencing of exons 18-21 on 89 HCCs. No mutations causing amino acid changes or deletions were identified. The results indicate mutation of the kinase domain of EGFR does not play a significant role in the tumorigenesis of HCC and gefitinib is unlikely to be used as single-drug therapy for HCC.

Desmoplastic small round cell tumor of the kidney.

Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive, malignant tumor usually present with widespread abdominal serosal involvement. Isolated cases occur in limbs, head and neck, and brain. We present a case of primary DSRCT of the kidney in a 41-year-old man. The tumor showed morphologic, immunohistochemical, and molecular characteristics similar to DSRCTs arising in other sites. Epithelial and mesenchymal markers were coexpressed in the tumor cells. RT-PCR analysis showed EWS-WT1 fusion transcripts resulting from the t(11;22)(p13;q12) reciprocal translocation. DSRCT should be considered in the differential diagnosis of small blue round cell tumors of the kidney.