Overexpression and Mutation of p53 Exons 4-8 in Canine Intestinal Adenocarcinoma

Transcriptome analysis of the adenoma-carcinoma sequences identifies novel biomarkers associated with development of canine colorectal cancer

The concept of adenoma-to-cancer transformation in human colorectal cancer (CRC) is widely accepted. However, the relationship between transcriptome features and adenoma to carcinoma transformation in canines is not clear. We collected transcriptome data from 8 normal colon tissues, 4 adenoma tissues, and 15 cancer tissues. Differential analysis was unable to determine the dynamic changes of genes but revealed that PFKFB3 may play a key role in this process. Enrichment analysis explained metabolic dysregulation, immunosuppression, and typical cancer pathways in canine colorectal tumors. MFuzz generated specific dynamic expression patterns of five differentially expressed genes (DEGs). Weighted correlation network analysis showed that DEGs in cluster 3 were associated with malignant tissues, revealing the key role of inflammatory and immune pathways in canine CRC, and the S100A protein family was also found to be involved in the malignant transformation of canine colorectal tumors. By comparing strategies between humans and dogs, we found five novel markers that may be drivers of CRC. Among them, GTBP4 showed excellent diagnostic and prognostic ability. This study was the first systematic exploration of transformation in canine CRC, complemented the molecular characteristics of the development and progression of canine CRC, and provided new potential biomarkers and comparative oncologic evidence for biomarker studies in human colorectal cancer.

Recurrence and survival in dogs with excised colorectal polyps: A retrospective study of 58 cases

BACKGROUND

Compared to humans, colorectal polyps are relatively rare in dogs. Epidemiological and prognostic data remain accordingly sparse, although they could help veterinary clinicians in the management of these cases.

OBJECTIVES

To report the epidemiological data of dogs with colorectal polyps and identify factors associated with recurrence and survival.

ANIMALS

Fifty-eight client-owned dogs with colorectal polyps admitted to 7 veterinary hospitals (53 dogs from France, 5 dogs from Spain, and 4 dogs from Portugal) were included.

METHODS

Retrospective multicentric cohort study. Medical records and long-term outcome of the dogs were reviewed. When available, histological samples were reassessed by 2 board-certified pathologists according to the revised Vienna classification (RVC).

RESULTS

The West Highland White Terrier (WHWT) breed was significantly associated with the presence of colorectal polyps (OR: 20; 95% CI: 7.5-52; P < .001). The overall median time to recurrence was not reached after 2000 days. The overall estimated median survival time was 1640 days. WHWT breed and larger polyps were significantly associated with a shorter time of polyp recurrence after surgical removal (respectively, P = .05 and P = .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

The probability of recurrence of colorectal polyps in dogs is low, but increased in WHWTs and larger polyps, which might benefit from routine screening after removal. No effective predictors of polyp recurrence and survival were identified using the RVC.

Analysis of cell-free DNA concentration, fragmentation patterns and TP53 gene expression in mammary tumor-bearing dogs: A pilot study

Introduction

Liquid biopsy based on the analysis of circulating cell-free DNA (cfDNA), as well as on detection of point mutations by digital droplet PCR (ddPCR), has revolutionized the research in oncology. In recent years, this technique has been pioneering in veterinary medicine since it is a minimally invasive approach with very promising results for characterization of tumors.

Methods

The aim of this study was, firstly, to analyze the concentration and the fragmentation pattern of cfDNA of dogs with mammary tumors (n = 36) and healthy dogs (n = 5) and its correlation with clinicopathological data. Secondly, analysis of TP53 gene expression and the point mutation in the codon 245 were performed in cfDNA and in tumor tissues to assess their potential as plasma biomarkers.

Results and discussion

Our results highlighted that those dogs with worse clinicopathological characteristics (simple or undifferentiated carcinomas, higher histological grade and presence of peritumoral inflammation) shown higher cfDNA concentration and higher concentrations of short-fragments (&lt;190 bp) than healthy dogs. In addition, although no detection of the point mutation in codon 245 of TP53 gene could be detected neither in plasma nor tumor tissue, an increased TP53 expression was detected in animals with tumors bearing malignant characteristics. Finally, a high concordance with TP53 gene expression in plasma and tumor tissue and cfDNA concentration was also found. The results derived from this work confirm the valuable potential of cfDNA and its fragments, as well as the analysis of TP53 expression in plasma as useful liquid biomarkers for clinical application in veterinary oncology.

DNA Damage Response (DDR) proteins in canine cancer as potential research targets in comparative oncology

The DNA damage response (DDR) is a complex signal transduction network that is activated when endogenous or exogenous genotoxins damage or interfere with the replication of genomic DNA. Under such conditions, the DDR promotes DNA repair and ensures accurate replication and division of the genome. High levels of genomic instability are frequently observed in cancers and can stem from germline loss‐of‐function mutations in certain DDR genes, such as BRCA1, BRCA2, and p53, that form the basis of human cancer predisposition syndromes. In addition, mutation and/or aberrant expression of multiple DDR genes are frequently observed in sporadic human cancers. As a result, the DDR is considered to represent a viable target for cancer therapy in humans and a variety of strategies are under investigation. Cancer is also a significant cause of mortality in dogs, a species that offers certain advantages for experimental oncology. Domestic dogs present numerous inbred lines, many of which display predisposition to specific forms of cancer and the study of which may provide insight into the biological basis of this susceptibility. In addition, clinical trials are possible in dogs and may lead to therapeutic insights that could ultimately be extended to humans. Here we review what is known specifically about the DDR in dogs and discuss how this knowledge could be extended and exploited to advance experimental oncology in this species.

EGFR Overexpression and Sequence Analysis of KRAS, BRAF, and EGFR Mutation Hot Spots in Canine Intestinal Adenocarcinoma

Epidermal growth factor receptor (EGFR) is overexpressed in many human colorectal cancers and anti-EGFR agents are employed as immunotherapies. However, KRAS, EGFR, and BRAF gene mutations can influence the activity of the anti-EGFR agents. We evaluated EGFR expression at protein and mRNA levels in canine intestinal adenocarcinomas using immunohistochemistry (IHC) and RNA in situ hybridization (RNA-ISH). We also investigated the mutation status of EGFR, KRAS, and BRAF to aid the development of anti-EGFR agents for canine intestinal adenocarcinoma. EGFR expression was highest in adenocarcinoma, followed by intramucosal neoplasia (adenoma and in situ carcinoma), and nonneoplastic canine intestinal tissue, at both protein (P = .000) and mRNA (P = .005) levels. The EGFR, KRAS, and BRAF genes showed wild-type sequences at the mutation hot spots in all 13 specimens. Thus, EGFR might serve as a promising diagnostic marker in canine intestinal adenocarcinoma, and further studies would be needed to develop EGFR-targeted anticancer therapies.

CDX-2 Protein and mRNA Expression in Canine Intestinal Adenocarcinoma

Caudal-related homeobox transcription factor 2 (CDX-2) is a specific cell marker employed in the diagnosis of human colorectal cancer. Reduced CDX-2 expression is associated with several indicators of poor prognosis in human colorectal cancer. In the present study, CDX-2 protein levels were evaluated and patterns of CDX-2 mRNA accumulation are described for the first time in canine intestinal adenocarcinoma (CIA). Canine intestinal epithelial biopsies from 21 CIAs and 14 non-neoplastic control tissues were retrospectively evaluated for CDX-2 expression and CDX-2 mRNA levels by immunohistochemistry and RNA in-situ hybridization (RNA-ISH), respectively. The mean percentage or intensity of expression was decreased in the CIA group (P = 0.000). RNA-ISH demonstrated a significant correlation between the decrease in CDX-2 mRNA levels and CDX-2 protein expression (P = 0.000). CDX-2 downregulation, in terms of protein as well as mRNA levels, may serve as a diagnostic marker in CIA.

p53 Gene Mutation in Blood of Zebu Cattle with Squamous Cell Carcinoma of the Horn

Horn cancer is one of the most important diseases in Zebu castrated male cattle. The objective of this study was to investigate the presence of p53 gene mutation in the blood of affected cattle and its value for early diagnosis and prognosis. The study was conducted on blood samples from 20 affected cattle and six healthy control cattle from Western India. Plasma samples were evaluated for the presence of p53 gene mutation using the polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) technique and the results were correlated with the stage of cancer. Five of the 20 cases had stage I neoplasms, nine stage II and six stage III, based on histopathological examination. PCR-SSCP analysis revealed an aberrant pattern of DNA migration on polyacrylamide gel electrophoresis of DNA extracts from blood samples of six animals with stage II and stage III cancer. No mutation was identified in blood from cattle with stage I cancer or from healthy control cattle. These results suggest that PCR-SSCP detection of p53 gene mutation in blood has potential diagnostic and prognostic value, and indicate the need for further large-scale investigation.