Glycoprotein 90K, downregulated in advanced colorectal cancer tissues, interacts with CD9/CD82 and suppresses the Wnt/beta-catenin signal via ISGylation of beta-catenin

Flexible spectral imaging color enhancement and indigo carmine in neoplasia diagnosis during colonoscopy: a large prospective UK series

OBJECTIVES

At present, all colonic polyps are removed and sent for histopathological evaluation, resulting in laboratory and reporting costs. Recent American Society for Gastrointestinal Endoscopy (ASGE) guidelines have set standards for in-vivo diagnosis in place of conventional histopathology, and all future technologies will have to be tested against these standards. Data on flexible spectral imaging color enhancement (FICE) were very limited. This study aims to evaluate the accuracy of FICE and indigo carmine (IC) for in-vivo histology prediction for polyps of less than 10 mm in size and to assess the economic impact of this strategy.

METHODS

In a screening population, polyps of less than 10 mm were assessed using white light (WLI) by FICE, by IC, and the predicted diagnosis was recorded. Polyps were then removed and sent for histological analysis. Accuracy of the predicted rescope interval was calculated using British Society of Gastroenterology and ASGE guidelines. Two models for using in-vivo diagnosis were proposed and savings in terms of histopathology costs calculated.

RESULTS

A total of 232 polyps of less than 10 mm were examined. FICE improved the accuracy of in-vivo diagnosis of adenoma to 88% compared with 75% with WLI (P<0.0001). IC after FICE improved this further to 94%. Rescope interval could be set correctly using FICE or IC in 97% of cases by British Society of Gastroenterology guidelines or 97% with FICE and 99% with IC using ASGE guidelines. A saving of £678,253 (€762767) per annum could be made within the UK national screening population.

CONCLUSION

FICE and IC significantly improves the in-vivo diagnosis of colonic polyps over WLI and can lead to significant cost savings.

Absent in Melanoma 2 (AIM2) is an important mediator of interferon-dependent and -independent HLA-DRA and HLA-DRB gene expression in colorectal cancers

Absent in Melanoma 2 (AIM2) is a member of the HIN-200 family of hematopoietic, IFN-inducible, nuclear proteins, associated with both, infection defense and tumor pathology. Recently, AIM2 was found to act as a DNA sensor in innate immunity. In addition, we and others have previously demonstrated a high frequency of AIM2-alterations in microsatellite unstable (MSI-H) tumors. To further elucidate AIM2 function in colorectal tumors, we here addressed AIM2-responsive target genes by microarray based gene expression profiling of 22 244 human genes. A total of 111 transcripts were significantly upregulated, whereas 80 transcripts turned out to be significantly downregulated in HCT116 cells, constitutively expressing AIM2, compared with AIM2-negative cells. Among the upregulated genes that were validated by quantitative PCR and western blotting we recognized several interferon-stimulated genes (ISGs: IFIT1, IFIT2, IFIT3, IFI6, IRF7, ISG15, HLA-DRA, HLA-DRB, TLR3 and CIITA), as well as genes involved in intercellular adhesion and matrix remodeling. Expression of ISGs correlated with expression of AIM2 in 10 different IFN-γ treated colorectal cancer cell lines. Moreover, small interfering RNA-mediated knock-down of AIM2 resulted in reduced expression of HLA-DRA, HLA-DRB and CIITA in IFN-γ-treated cells. IFN-γ independent induction of HLA-DR genes and their encoded proteins was also demonstrated upon doxycyclin-regulated transient induction of AIM2. Luciferase reporter assays revealed induction of the HLA-DR promoter upon AIM2 transfection in different cell lines. STAT-signaling was not involved in IFN-γ independent induction of ISGs, arguing against participation of cytokines released in an autostimulating manner. Our data indicate that AIM2 mediates both IFN-γ dependent and independent induction of several ISGs, including genes encoding the major histocompatibility complex (MHC) class II antigens HLA-DR-α and -β. This suggests a novel role of the IFN/AIM2/ISG cascade likewise in cancer cells.

Repression of KIAA1199 attenuates Wnt-signalling and decreases the proliferation of colon cancer cells

BACKGROUND

The KIAA1199 transcript is upregulated in colon adenomas and downregulated upon β-catenin knockdown.

METHODS

Transcript profiling was performed on >500 colon biopsies, methylation profiling data were compared with transcript data. Immunohistochemistry assessed KIAA1199 protein expression in 270 stage II/III tumours (>3 years follow-up). The effects of stable KIAA1199 knockdown in SW480 cells (three different constructs) were studied using transcriptional profiling, proliferation and protein analysis.

RESULTS

The KIAA1199 transcript was strongly upregulated in 95% of adenocarcinomas. Absent expression in normal mucosa correlated with KIAA1199 promotor methylation. Nuclear and cytoplasmic KIAA1199 protein expression was identified in colon adenocarcinomas and other types of cancers. A subpopulation of patients with tumours strongly expressing KIAA1199 in the nucleus showed a better outcome with regard to recurrence as lung or liver metastases. The KIAA1199 knockdown affected the cell cycle and the Wnt-signalling pathway. Reduced cellular proliferation and decreased KI67, phosphorylated retinoblastoma, β-catenin and ASCL2 protein expression supported these findings. Eighteen Wnt-signalling genes differentially expressed upon KIAA1199 knockdown correlated with the KIAA1199 expression profile in clinical specimens.

CONCLUSION

The KIAA1199 knockdown attenuates the effects of the Wnt/β-catenin signalling and it may thus be regarded as a regulatory part of this pathway.