Bridging the Species Gap: Morphological and Molecular Comparison of Feline and Human Intestinal Carcinomas

Limited availability of in vivo experimental models for invasive colorectal cancer (CRC) including metastasis and high tumor budding activity is a major problem in colorectal cancer research. In order to compare feline and human intestinal carcinomas, tumors of 49 cats were histologically subtyped, graded and further characterized according to the human WHO classification. Subsequently, feline tumors were compared to a cohort of 1004 human CRC cases. Feline intestinal tumors closely resembled the human phenotype on a histomorphological level. In both species, adenocarcinoma not otherwise specified (ANOS) was the most common WHO subtype. In cats, the second most common subtype of the colon (36.4%), serrated adenocarcinoma (SAC), was overrepresented compared to human CRC (8.7%). Mucinous adenocarcinoma (MAC) was the second most common subtype of the small intestine (12.5%). Intriguingly, feline carcinomas, particularly small intestinal, were generally of high tumor budding (Bd) status (Bd3), which is designated an independent prognostic key factor in human CRC. We also investigated the relevance of feline CTNNB1 exon 2 alterations by Sanger sequencing. In four cases of feline colonic malignancies (3 ANOS, 1 SAC), somatic missense mutations of feline CTNNB1 (p.D32G, p.D32N, p.G34R, and p.S37F) were detected, indicating that mutational alterations of the WNT/β-catenin signaling pathway potentially play an essential role in feline intestinal tumorigenesis comparable to humans and dogs. These results indicate that spontaneous intestinal tumors of cats constitute a useful but so far underutilized model for human CRC. Our study provides a solid foundation for advanced comparative oncology studies and emphasizes the need for further (molecular) characterization of feline intestinal carcinomas.

Biology and Therapeutic Targets of Colorectal Serrated Adenocarcinoma; Clues for a Histologically Based Treatment against an Aggressive Tumor

Serrated adenocarcinoma (SAC) is a tumor recognized by the WHO as a histological subtype accounting for around 9% of colorectal carcinomas. Compared to conventional carcinomas, SACs are characterized by a worse prognosis, weak development of the immune response, an active invasive front and a frequent resistance to targeted therapy due to a high occurrence of KRAS or BRAF mutation. Nonetheless, several high-throughput studies have recently been carried out unveiling the biology of this cancer and identifying potential molecular targets, favoring a future histologically based treatment. This review revises the current evidence, aiming to propose potential molecular targets and specific treatments for this aggressive tumor.

miR-181a-2* expression is different amongst carcinomas from the colorectal serrated route

Serrated adenocarcinoma (SAC) and colorectal carcinomas showing histological and molecular features of high-level of microsatellite instability (hmMSI-H) are both end points of the serrated pathway of colorectal carcinogenesis. Despite common features (right-sided location, CpG island methylation phenotype and BRAF mutation) there are no studies comparing the microRNA (miRNA) expression profiles in SACs and hmMSI-H. The microtranscriptome from 12 SACs and 8 hmMSI-H were analysed using Affymetrix GeneChip miRNA 3.0 arrays and differentially enriched functions involving immune response were observed from this comparison. miR-181a-2* was found significantly more expressed in hmMSI-H than in SAC and higher expression of this miRNA in microsatellite unstable colorectal cancer were corroborated by Real-Time PCR in an extended series (61 SAC, 21 hmMSI-H). An analysis of genes possibly regulated by miR-181a-2* was carried out and, amongst these, an inverse correlation of NAMPT with miR-181a-2* expression was observed, whereas, for TRAF1 and SALL1, additional regulation mechanisms involving CpG island methylation were observed. miR-181a-2* is associated with particular histological and molecular features of colorectal carcinomas within the serrated pathological pathway and might play a role in the immune responses of microsatellite instability carcinomas.

The low prevalence of colonic serrated adenocarcinoma with high KRAS mutational status at Cipto Mangunkusumo Hospital, Indonesia

Background: Serrated adenocarcinoma (SA), a subtype of colorectal carcinoma, and the KRAS mutation, a strong marker for the patient’s response to anti-epidermal growth factor receptor therapy, have a clinical importance because of its progressive nature and tendency for chemoresistance. The purposes of this study were to (1) determine the prevalence of SA, (2) evaluate the histomorphological characteristics of SA and classical adenocarcinoma based on its prognostic factors, (3) determine the prevalence of the KRAS mutation in SA cases, and (4) identify the main characteristics of SA cases and classical adenocarcinoma with a KRAS mutation.Methods: This study was conducted by reviewing hematoxylin-eosin-stained slides of colorectal carcinoma (CRC) cases from January 2013 to July 2015 at the Department of Anatomical Pathology Cipto Mangunkusumo General Hospital. The final diagnosis of SA was based on the Tuppurainen et al criteria and the KRAS mutation was evaluated using real-time polymerase chain reaction.Results: Among the 117 adenocarcinoma cases, there were 41 unequivocal SA, 11 equivocal SA, and 65 classical adenocarcinoma. The prevalence rates of unequivocal and equivocal SA among all CRC cases were 7.7% and 2.1%, respectively. There were 11 (28.2%) cases of wild-type KRAS and 28 (71.7%) cases of mutated KRAS among all unequivocal SA cases. Tumor budding (TB) was the predominant prognostic factor.Conclusion: The prevalence of SA among all CRC cases was 7.7%. The KRAS mutation was found in almost three-quarters of all SA cases.