Canine mammary tumor risk is associated with polymorphisms in RAD51 and STK11 genes

Genetic analysis of PALB2 gene WD40 domain in canine mammary tumour patients

BACKGROUND

DNA repair mechanisms are essential for tumorigenesis and disruption of HR mechanism is an important predisposing factor of human breast cancers (BC). PALB2 is an important part of the HR. There are similarities between canine mammary tumours (CMT) and BCs. As its human counterpart, PALB2 mutations could be a predisposing factor of CMT.

OBJECTIVES

In this study, we aimed to investigate the impacts of PALB2 variants on tumorigenesis and canine mammary tumor (CMT) malignancy.

METHODS

We performed Sanger sequencing to detect germline mutations in the WD40 domain of the canine PALB2 gene in CMT patients. We conducted in silico analysis to investigate the variants, and compared the germline PALB2 mutations in humans that cause breast cancer (BC) with the variants detected in dogs with CMT.

RESULTS

We identified an intronic (c.3096+8C>G) variant, two exonic (p.A1050V and p.R1354R) variants, and a 3' UTR variant (c.4071T>C). Of these, p.R1354R and c.4071T>C novel variants were identified for the first time in this study. We found that the p.A1050V mutation had a significant effect. However, we could not determine sufficient similarity due to the differences in nucleotide/amino acid sequences between two species. Nonetheless, possible variants of human sequences in the exact location as their dog counterparts are associated with several cancer types, implying that the variants could be crucial for tumorigenesis in dogs. Our results did not show any effect of the variants on tumor malignancy.

CONCLUSIONS

The current project is the first study investigating the relationship between the PALB2 gene WD40 domain and CMTs. Our findings will contribute to a better understanding of the pathogenic mechanism of the PALB2 gene in CMTs. In humans, variant positions in canines have been linked to cancer-related phenotypes such as familial BC, endometrial tumor, and hereditary cancer predisposition syndrome. The results of bioinformatics analyses should be investigated through functional tests or case-control studies.

Profiling canine mammary tumors: A potential model for studying human breast cancer

Despite all clinical progress recorded in the last decades, human breast cancer (HBC) remains a major challenge worldwide both in terms of its incidence and its management. Canine mammary tumors (CMTs) share similarities with HBC and represent an alternative model for HBC. The utility of the canine model in studying HBC relies on their common features, include spontaneous development, subtype classification, mutational profile, alterations in gene expression profile, and incidence/prevalence. This review describes the similarities between CMTs and HBC regarding genomic landscape, microRNA expression alteration, methylation, and metabolomic changes occurring during mammary gland carcinogenesis. The primary purpose of this review is to highlight the advantages of using the canine model as a translational animal model for HBC research and to investigate the challenges and limitations of this approach.

Identification of SNP markers for canine mammary gland tumours in females based on a genome-wide association study - preliminary results

Introduction

The development of genetic research over recent decades has enabled the discovery of new genetic markers, such as single nucleotide polymorphisms (SNPs). This, as well as the full sequencing of the dog genome, has enabled genome-wide association studies (GWAS) to be used in the search for genetic causes of canine mammary tumours (CMTs).

Material and Methods

Genotypic data containing 175,000 SNPs, which had been obtained using the Illumina CanineHD BeadChip microarray technique, were available for analysis in this study. The data concerned 118 bitches, including 36 animals with CMT, representing various breeds and age groups. Statistical analysis was performed in two steps: quality control of genotyping data and genome-wide association analysis based on dominant, recessive, overdominant, codominant, and log-additive models with the single SNP effects.

Results

A total of 40 different SNPs significantly associated with CMT appearance were detected. Moreover, twelve SNPs showed statistical significance in more than one model. Of all the significant SNPs, two, namely BICF2G630136001 in the overdominant model and TIGRP2P107898_rs9044787 in the log-additive model, reached the 5-8 significance level. The other SNPs were significant to a 1-5 level.

Conclusion

In the group of SNPs indicated as significant in the GWAS analysis, several transpired to be localised within genes that may play an important role in CMT.

Genomic Medicine in Canine Periodontal Disease: A Systematic Review

Genomic medicine has become a growing reality; however, it is still taking its first steps in veterinary medicine. Through this approach, it will be possible to trace the genetic profile of a given individual and thus know their susceptibility to certain diseases, namely periodontal disease. This condition is one of the most frequently diagnosed in companion animal clinics, especially in dogs. Due to the limited existing information and the lack of comprehensive studies, the objective of the present study was to systematically review the existing scientific literature regarding genomic medicine in canine periodontal disease and determine which genes have already been studied and their probable potential. This study followed the recommendations of the PRISMA 2020 methodology. Canine periodontal disease allied to genomic medicine were the subjects of this systematic review. Only six articles met all of the inclusion criteria, and these were analyzed in detail. These studies described genetic variations in the following genes: interleukin-6, interleukin-10, interleukin-1, lactotransferrin, toll-like receptor 9, and receptor activator of nuclear factor-kappa B. Only in two of them, namely interleukin-1 and toll-like receptor 9 genes, may the identified genetic variations explain the susceptibility that certain individuals have to the development of periodontal disease. It is necessary to expand the studies on the existing polymorphic variations in genes and their relationship with the development of periodontal disease. Only then will it be possible to fully understand the biological mechanisms that are involved in this disease and that determine the susceptibility to its development.

Protective Effect of HER2 Gene Polymorphism rs24537331 in the Outcome of Canine Mammary Tumors

The role of HER2 in canine mammary tumors is not completely elucidated, and the contradictory results published so far may be, in part, explained by the genetic variability recognized in the canine HER2 gene. Single nucleotide polymorphism (SNPs) in HER2 were recently associated with less aggressive canine mammary tumor histotypes. This study assesses the relationship between SNPs rs24537329 and rs24537331 in canine HER2 gene and clinicopathological characteristics and outcome of mammary tumors in a group of 206 female dogs. Allelic variants were observed in 69.8% and 52.7% of the dogs for SNP rs24537329 and rs24537331, respectively. Our results demonstrated that SNP rs24537331 was associated with decreased tumoral necrosis (HR: 3.09; p = 0.012) and with longer disease-specific overall survival (HR: 2.59; p = 0.013). However, no statistically significant associations were found between SNP rs24537329 and the tumors' clinicopathological characteristics or survival. Our data suggest that SNP rs24537331 may have a protective effect in canine mammary tumors, allowing the identification of a subgroup of animals prone to develop less aggressive forms of the disease. This study emphasizes the importance of the genetic tests associated with clinical images and histological examinations when assessing CMT outcomes.

Molecular Characterization of CF33 Canine Cell Line and Evaluation of Its Ability to Respond against Infective Stressors in Sight of Anticancer Approaches

Simple Summary

Canine mammary cancer is very common and has many similarities with human breast cancer. Risk factors, physiological and pathological behaviors, and the clinical course in dogs are very similar to humans. Several molecular similarities have also been reported, such as overexpression of EGF, proliferation markers, metalloproteinase and cyclooxygenase, TP53 mutations, and CXCR4/SDF1 axis activation. These common characteristics make these breast tumors resistant to conventional therapies. It is therefore necessary to study therapeutic alternatives. Cell lines could be helpful to test in vitro immunomodulant anti-cancer therapies, allowing a reduction of laboratory animals’ involvement in the preliminary tests and achieving results in a shorter time. Although the canine mammary carcinoma cell line CF33 has been widely used in many studies on dog mammary cancer, characterization of its gene expression profile and of the influence of infective stressors of this cell line is poor. Our study shows the interaction of CF33 and Salmonella Typhimurium (ST) as an infective stressor, indicating that these cells may represent an in vitro model for assessing novel therapeutic approaches using bacteria.

Abstract

Spontaneous mammary tumors are the most frequent neoplasms in bitches and show similarities with human breast cancer in risk factors, clinical course, and histopathology. The poor prognosis of some cancer subtypes, both in human and dog, demands more effective therapeutic approaches. A possible strategy is the new anticancer therapy based on immune response modulation through bacteria or their derivatives on canine mammary carcinoma cell lines. The aim of the present study was to analyze the CF33 cell line in terms of basal expression of immune innate genes, CXCR4 expression, and interaction with infectious stressors. Our results highlight that CF33 maintains gene expression parameters typical of mammary cancer, and provides the basal gene expression of CF33, which is characterized by overexpression of CXCR4, CD44, RAD51, LY96, and a non-continuous expression of TP53 and PTEN. No mutations appeared in the CXCR4 gene until the 58th passage; this may represent important information for studying the CXCR4 pathway as a therapeutic target. Moreover, the CF33 cell line was shown to be able to interact with Salmonella Typhimurium (ST) (an infective stressor), indicating that these cells could be used as an in vitro model for developing innovative therapeutic approaches involving bacteria.

The Novel Diagnostic Techniques and Biomarkers of Canine Mammary Tumors

Canine mammary tumors (CMTs) are considered a serious clinical problem in older bitches. Due to the high malignancy rate and poor prognosis, an early diagnosis is essential. This article is a summary of novel diagnostic techniques as well as the main biomarkers of CMTs. So far, CMTs are detected only when changes in mammary glands are clinically visible and surgical removal of the mass is the only recommended treatment. Proper diagnostics of CMT is especially important as they represent a very diverse group of tumors and therefore different treatment approaches may be required. Recently, new diagnostic options appeared, like a new cytological grading system of CMTs or B-mode ultrasound, the Doppler technique, contrast-enhanced ultrasound, and real-time elastography, which may be useful in pre-surgical evaluation. However, in order to detect malignancies before macroscopic changes are visible, evaluation of serum and tissue biomarkers should be considered. Among them, we distinguish markers of the cell cycle, proliferation, apoptosis, metastatic potential and prognosis, hormone receptors, inflammatory and more recent: metabolomic, gene expression, miRNA, and transcriptome sequencing markers. The use of a couple of the above-mentioned markers together seems to be the most useful for the early diagnosis of neoplastic diseases as well as to evaluate response to treatment, presence of tumor progression, or further prognosis. Molecular aspects of tumors seem to be crucial for proper understanding of tumorigenesis and the application of individual treatment options.

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.

Single Nucleotide Polymorphism in Prolactin Gene Is Associated With Clinical Aggressiveness and Outcome of Canine Mammary Malignant Tumors

Prolactin (PRL) is a key hormone involved in canine mammary development and tumorigenesis. In this study, the influence of a single nucleotide polymorphism (SNP) in the PRL gene (rs23932236) on the clinicopathological parameters and survival of dogs with canine mammary tumors (CMTs) was investigated. A total of 206 female dogs with spontaneous mammary tumors were enrolled in this study and circulating blood cells were genotyped. This specific SNP was associated with larger size (>3 cm diameter) for malignant tumors (P = .036), tumors with infiltrative/invasive growth pattern (P = .010), vascular invasion (P = .006), and lymph node metastasis (P = .004). Carriers of the variant allele had a shorter overall survival compared to the wild-type population with an overall survival of 18.7 months and 22.7 months, respectively (P = .004). These findings suggest that SNP rs23932236 of canine PRL gene may be used as an indicator for the development of clinically aggressive forms of CMTs.

Translational oncotargets for immunotherapy: From pet dogs to humans

Preclinical studies in rodent models have been a pivotal role in human clinical research, but many of them fail in the translational process. Spontaneous tumors in pet dogs have the potential to bridge the gap between preclinical models and human clinical trials. Their natural occurrence in an immunocompetent system overcome the limitations of preclinical rodent models. Due to its reasonable cellular, molecular, and genetic homology to humans, the pet dog represents a valuable model to accelerate the translation of preclinical studies to clinical trials in humans, actually with benefits for both species. Moreover, their unique genetic features of breeding and breed-related mutations have contributed to assess and optimize therapeutics in individuals with different genetic backgrounds. This review aims to outline four main immunotherapy approaches - cancer vaccines, adaptive T-cell transfer, antibodies, and cytokines -, under research in veterinary medicine and how they can serve the clinical application crosstalk with humans.

Comprehensive live-cell imaging analysis of cryptotanshinone and synergistic drug-screening effects in various human and canine cancer cell lines

Background

Several studies have highlighted both the extreme anticancer effects of Cryptotanshinone (CT), a Stat3 crippling component from Salvia miltiorrhiza, as well as other STAT3 inhibitors to fight cancer.

Methods

Data presented in this experiment incorporates 2 years of in vitro studies applying a comprehensive live-cell drug-screening analysis of human and canine cancer cells exposed to CT at 20 μM concentration, as well as to other drug combinations. As previously observed in other studies, dogs are natural cancer models, given to their similarity in cancer genetics, epidemiology and disease progression compared to humans.

Results

Results obtained from several types of human and canine cancer cells exposed to CT and varied drug combinations, verified CT efficacy at combating cancer by achieving an extremely high percentage of apoptosis within 24 hours of drug exposure.

Conclusions

CT anticancer efficacy in various human and canine cancer cell lines denotes its ability to interact across different biological processes and cancer regulatory cell networks, driving inhibition of cancer cell survival.

Whole genome sequencing for the investigation of canine mammary tumor inheritance - an initial assessment of high-risk breast cancer genes reveal BRCA2 and STK11 variants potentially associated with risk in purebred dogs

Background

Although, in general, cancer is considered a multifactorial disease, clustering of particular cancers in pedigrees suggests a genetic predisposition and could explain why some dog breeds appear to have an increased risk of certain cancers. To our knowledge, there have been no published reports of whole genome sequencing to investigate inherited canine mammary tumor (CMT) risk, and with little known about CMT genetic susceptibility, we carried out whole genome sequencing on 14 purebred dogs diagnosed with mammary tumors from four breed-specific pedigrees. Following sequencing, each dog’s data was processed through a bioinformatics pipeline. This initial report highlights variants in orthologs of human breast cancer susceptibility genes.

Results

The overall whole genome and exome coverage averages were 26.0X and 25.6X, respectively, with 96.1% of the genome and 96.7% of the exome covered at least 10X. Of the average 7.9 million variants per dog, initial analyses involved surveying variants in orthologs of human breast cancer susceptibility genes, BRCA1, BRCA2, CDH1, PTEN, STK11, and TP53, and identified 19 unique coding variants that were validated through PCR and Sanger sequencing. Statistical analyses identified variants in BRCA2 and STK11 that appear to be associated with CMT, and breed-specific analyses revealed the breeds at the highest risk. Several additional BRCA2 variants showed trends toward significance, but have conflicting interpretations of pathogenicity, and correspond to variants of unknown significance in humans, which require further investigation. Variants in other genes were noted but did not appear to be associated with disease.

Conclusions

Whole genome sequencing proves to be an effective method to elucidate risk of CMT. Risk variants in orthologs of human breast cancer susceptibility genes have been identified. Ultimately, these whole genome sequencing efforts have provided a plethora of data that can also be assessed for novel discovery and have the potential to lead to breakthroughs in canine and human research through comparative analyses.

Estrogen receptors genotypes and canine mammary neoplasia

BACKGROUND

Estrogens are essential for the development and proper function of several hormone-dependent organs. There are, however, several lines of evidence associating estrogens with mammary carcinogenesis. A marked individual genetic variability concerning estrogens biosynthesis, metabolism and mechanism of action was recognized and associated with human breast cancer susceptibility, clinical features and progression. Although some genetic variations in canine ESR1 gene were reported, their influence in clinicopathological features and progression of canine mammary tumors has not been fully evaluated. This study aims to assess the influence of SNPs in ESR1 gene (rs397512133, rs397510462, rs851327560, rs397510612, rs852887655, rs852684753 and rs852398698) in canine mammary tumors characteristics and progression. A group of 155 non-neutered bitches with mammary tumors was included in the study. Follow-up information was assessed 24 months after surgery.

RESULTS

Genetic profiles associated with a later onset of mammary tumors and less aggressive clinicopathological features, namely smaller tumor size (≤ 3 cm) with extensive tubular differentiation and low canine-adapted prognostic index (vet-NPI), were identified in this study.

CONCLUSIONS

Our data suggest that the ESR1 genetic profile may help on the decision regarding the selection of individual tailored preventive measures against canine mammary tumors development, such as early neutering.

Influence of E-cadherin genetic variation in canine mammary tumour risk, clinicopathological features and prognosis

E-cadherin is a cell adhesion molecule that participates in several cellular processes that guarantee the maintenance of structural and functional integrity of epithelial tissues. E-cadherin plays an important role in mammary carcinogenesis, and various studies have demonstrated the effect of CDH1 genetic variation in risk, progression and biological behaviour of human breast cancer. Although there are some recognized genetic variations in canine CDH1 gene, their influence in canine mammary tumour development and progression has not been previously evaluated. In this study, we aim to assess the influence of CDH1 SNPs rs850805755, rs852280880 and rs852639930 in the risk, clinicopathological features and clinical outcome of canine mammary tumours. A case-control study was conducted involving 206 bitches with mammary tumours and 161 bitches free of mammary neoplasia. CDH1 SNPs rs850805755 and rs852280880 were associated with a decreased risk and a later onset of mammary tumour development. Furthermore, these SNPs were related to the development of small size carcinomas, of low histological grade and low nuclear pleomorphism. SNP rs852639930 was associated with the development of small size tumours with a non-infiltrative, non-invasive growth pattern. Data from the present investigation demonstrate that these CDH1 genetic variants could have a protective role in canine mammary tumours, by being associated with low risk of tumour development, delayed onset of the disease and less aggressive clinicopathological features.