Haberlea rhodopensis Extract Tunes the Cellular Response to Stress by Modulating DNA Damage, Redox Components, and Gene Expression

Ionizing radiation (IR) and reactive oxygen species (ROS)-induced oxidative stress can cause damage to cellular biomolecules, including DNA, proteins, and lipids. These harmful effects can compromise essential cellular functions and significantly raise the risk of metabolic dysfunction, accumulation of harmful mutations, genome instability, cancer, accelerated cellular senescence, and even death. Here, we present an investigation of HeLa cancer cells' early response to gamma IR (γ-IR) and oxidative stress after preincubation of the cells with natural extracts of the resurrection plant Haberlea rhodopensis. In light of the superior protection offered by plant extracts against radiation and oxidative stress, we investigated the cellular defence mechanisms involved in such protection. Specifically, we sought to evaluate the molecular effects of H. rhodopensis extract (HRE) on cells subjected to genotoxic stress by examining the components of the redox pathway and quantifying the transcription levels of several critical genes associated with DNA repair, cell cycle regulation, and apoptosis. The influence of HRE on genome integrity and the cell cycle was also studied via comet assay and flow cytometry. Our findings demonstrate that HREs can effectively modulate the cellular response to genotoxic and oxidative stress within the first two hours following exposure, thereby reducing the severity of such stress. Furthermore, we observed the specificity of genoprotective HRE doses depending on the source of the applied genotoxic stress.

Identifying the Risk Factors for Malignant Mammary Tumors in Dogs: A Retrospective Study

Mammary cancer is one of the main causes of death in female dogs worldwide, considering that many risk factors are involved in its development. This study aimed to elucidate the relationship between epidemiological and clinical risk factors with the histopathological diagnosis of malignant mammary tumors in dogs treated at the Veterinary Hospital of the Federal University of Uberlândia, which has one of the first veterinary oncology services in Brazil. A retrospective matched case-control study was conducted to identify risk factors for the development of malignant mammary tumors in dogs. The variables analyzed were size dog, breed, housing, type of diet, and body score. Potential risk factors were selected by univariate analysis (p < 0.25) before multivariate forward binary logistic regression. The most frequent benign tumor was the benign mixed tumor (35.2%), and the most frequent malignant tumor was the mixed carcinoma (27.4%). Size dog, breed, housing, and overweight are predictors of malignant mammary tumors in dogs. The highest risk of developing malignant mammary tumors is associated with large female dogs, Yorkshire or Poodle breeds, living outside the home, or being overweight.

Studying the DNA damage response pathway in hematopoietic canine cancer cell lines, a necessary step for finding targets to generate new therapies to treat cancer in dogs

Background

Dogs present a significant opportunity for studies in comparative oncology. However, the study of cancer biology phenomena in canine cells is currently limited by restricted availability of validated antibody reagents and techniques. Here, we provide an initial characterization of the expression and activity of key components of the DNA Damage Response (DDR) in a panel of hematopoietic canine cancer cell lines, with the use of commercially available antibody reagents.

Materials and methods

The techniques used for this validation analysis were western blot, qPCR, and DNA combing assay.

Results

Substantial variations in both the basal expression (ATR, Claspin, Chk1, and Rad51) and agonist-induced activation (p-Chk1) of DDR components were observed in canine cancer cell lines. The expression was stronger in the CLBL-1 (B-cell lymphoma) and CLB70 (B-cell chronic lymphocytic leukemia) cell lines than in the GL-1 (B-cell leukemia) cell line, but the biological significance of these differences requires further investigation. We also validated methodologies for quantifying DNA replication dynamics in hematopoietic canine cancer cell lines, and found that the GL-1 cell line presented a higher replication fork speed than the CLBL-1 cell line, but that both showed a tendency to replication fork asymmetry.

Conclusion

These findings will inform future studies on cancer biology, which will facilitate progress in developing novel anticancer therapies for canine patients. They can also provide new knowledge in human oncology.

Canine Mammary Tumor Cell Lines Derived from Metastatic Foci Show Increased RAD51 Expression but Diminished Radioresistance via p21 Inhibition

Due to the high incidence of mammary tumors in dogs, it is important to elucidate the pathogenesis of these tumors in veterinary medicine. Radiation therapy is often used to treat mammary tumors that target DNA lesions. RAD51 is a key molecule that repairs DNA damage via homologous recombination. We examined the relationship between RAD51 expression and radiosensitivity in mammary tumor cell lines. CHMp and CHMm from the same individual were selected based on the differences in RAD51 expression. The radiosensitivity of both cell lines was examined using MTT and scratch assays; CHMm, which has high RAD51 expression, showed higher sensitivity to radiation than CHMp. However, the nuclear focus of RAD51 during DNA repair was formed normally in CHMp, but not in most of CHMm. Since irradiation resulted in the suppression of cell cycle progression in CHMp, the expression of p21, a cell cycle regulatory factor, was detected in CHMp after 15 Gy irradiation but not in CHMm. These results indicate that functional expression is more important than the quantitative expression of RAD51 in canine mammary tumor cells in response to DNA damage.

Canine models of human cancer: Bridging the gap to improve precision medicine

Dogs are remarkable, adaptable, and dependable creatures that have evolved alongside humans while contributing tremendously to our survival. Our canine companions share many similarities to human disease, particularly cancer. With the advancement of next-generation sequencing technology, we are beginning to unravel the complexity of cancer and the vast intra- and intertumoral heterogeneity that makes treatment difficult. Consequently, precision medicine has emerged as a therapeutic approach to improve patient survival by evaluating and classifying an individual tumor's molecular profile. Many canine and human cancers share striking similarities in terms of genotypic, phenotypic, clinical, and histological presentations. Dogs are superior to rodent models of cancer because they are a naturally heterogeneous population in which tumors occur spontaneously, are exposed to similar environmental conditions, and show more similarities in key modulators of tumorigenesis and clinical response, including the immune system, drug metabolism, and gut microbiome. In this chapter, we will explore various canine models of human cancers and emphasize the dog's critical role in advancing precision medicine and improving the survival of both man and man's best friend.

Experimental Models as Refined Translational Tools for Breast Cancer Research

Breast cancer is one of the most common cancers worldwide, which makes it a very impactful malignancy in the society. Breast cancers can be classified through different systems based on the main tumor features and gene, protein, and cell receptors expression, which will determine the most advisable therapeutic course and expected outcomes. Multiple therapeutic options have already been proposed and implemented for breast cancer treatment. Nonetheless, their use and efficacy still greatly depend on the tumor classification, and treatments are commonly associated with invasiveness, pain, discomfort, severe side effects, and poor specificity. This has demanded an investment in the research of the mechanisms behind the disease progression, evolution, and associated risk factors, and on novel diagnostic and therapeutic techniques. However, advances in the understanding and assessment of breast cancer are dependent on the ability to mimic the properties and microenvironment of tumors in vivo, which can be achieved through experimentation on animal models. This review covers an overview of the main animal models used in breast cancer research, namely in vitro models, in vivo models, in silico models, and other models. For each model, the main characteristics, advantages, and challenges associated to their use are highlighted.

[Expressions of HELQ and RAD51C in endometrial stromal sarcoma and their clinical significance]

OBJECTIVE

To observe the expression of HELQ and RAD51C in normal endometrial and endometrial stromal sarcoma (ESS) and analyze their correlation with the clinical features of the patients.

METHODS

The expressions of HELQ and RAD51C proteins were detected by immunohistochemical staining in normal endometrial tissues (14 cases) and tumor tissues from patients with ESS (37 cases) treated in Hunan Provincial Cancer Hospital from January, 2013 to December, 2016. The correlations of the expressions of the two proteins with the patients'age, FIGO staging, tissue type, tumor size, and lymph node metastasis were analyzed.

RESULTS

Immunohistochemical staining showed that the expressions of HELQ and RAD51C were both decreased in ESS patients compared with the normal group, and there was a positive correlation between HELQ and RAD51C expression (P &lt; 0.05). HELQ expression in ESS was correlated with the tumor size and type. The expressions of HELQ and RAD51C were not correlated with the patients' age, FIGO stage and status of lymph node metastasis (P &gt; 0.05).

CONCLUSIONS

Homologous recombination- directed DNA repair involving HELQ and RAD51C may participate in the occurrence and progression of ESS.

Naturally-Occurring Canine Mammary Tumors as a Translational Model for Human Breast Cancer

Despite extensive research over many decades, human breast cancer remains a major worldwide health concern. Advances in pre-clinical and clinical research has led to significant improvements in recent years in how we manage breast cancer patients. Although survival rates of patients suffering from localized disease has improved significantly, the prognosis for patients diagnosed with metastatic disease remains poor with 5-year survival rates at only 25%. In vitro studies using immortalized cell lines and in vivo mouse models, typically using xenografted cell lines or patient derived material, are commonly used to study breast cancer. Although these techniques have undoubtedly increased our molecular understanding of breast cancer, these research models have significant limitations and have contributed to the high attrition rates seen in cancer drug discovery. It is estimated that only 3-6% of drugs that show promise in these pre-clinical models will reach clinical use. Models that can reproduce human breast cancer more accurately are needed if significant advances are to be achieved in improving cancer drug research, treatment outcomes, and prognosis. Canine mammary tumors are a naturally-occurring heterogenous group of cancers that have several features in common with human breast cancer. These similarities include etiology, signaling pathway activation and histological classification. In this review article we discuss the use of naturally-occurring canine mammary tumors as a translational animal model for human breast cancer research.

The canine RAD51 mutation leads to the attenuation of interaction with PALB2

RAD51 forms a complex with BRCA2 and plays a central role in the DNA damage response pathway that is associated with homologous recombination. The structures of RAD51 and its homologues are highly conserved from prokaryotes to higher eukaryotes. Although a large number of BRCA2 mutations have been reported, there are only a few reports on the mutations of RAD51, which have been shown in humans and dogs. However, several mutations of canine RAD51 were identified from mammary gland tumour tissues in a recent study. Some of these mutations seem to have an influence on the homo-oligomerization or interaction with "Partner and localizer of BRCA2" (PALB2). In this study, we cloned the canine PALB2 homologue and investigated the effect on its interaction with the RAD51 mutants to evaluate the alteration in the function of RAD51 mutants. The A209S and T225S mutants of RAD51 show an attenuation of the interaction between RAD51 and PALB2. These results indicate that the canine RAD51 mutations can potentially alter the homologous recombination pathways in response to DNA damage in dogs.

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

Cancer is a complex disease involving genetic and phenotypic changes. Several single nucleotide polymorphisms (SNPs) have been associated with the risk of breast cancer development in women; however, little is known regarding their influence on canine mammary tumor risk. We assessed the influence of SNPs in genes related to human breast cancer susceptibility, with respect to the risk of development of mammary tumors in dogs. Sixty-seven canine SNPs in proto-oncogenes, tumor suppressor genes, genes involved in DNA repair, and in hormonal metabolism were evaluated in 212 bitches with mammary tumors and in 161 bitches free of mammary neoplasia. A significant association with mammary neoplasia risk was identified for 2 SNPs in RAD51 ( rs23623251 and rs23642734) and one SNP in the STK11 gene ( rs22928814). None of the other SNPs were related to the risk of mammary tumor development. The identification of genetic profiles associated with risk of mammary neoplasia is of great importance, supporting the implementation of specific clinical management strategies in high-risk animals.

Characteristics of the Epithelial-Mesenchymal Transition in Primary and Paired Metastatic Canine Mammary Carcinomas

The epithelial-mesenchymal transition (EMT) is a dynamic process linked to metastasis in many tumor types, including mammary tumors. In this study, we evaluated E-cadherin and vimentin immunolocalization in primary canine mammary carcinomas (20 cases) and their respective metastases, as well as their relationship with the core regulators SNAIL/SLUG. To assess the number of cells undergoing the process of EMT, we quantitated double-positive (E-cadherin⁺/vimentin⁺) cells using immunofluorescence, via cell counting and image analysis. In addition, SNAIL/SLUG expression was evaluated by established immunohistochemical methods. Primary tumors had significantly more E-cadherin⁺/vimentin⁺ co-expression than their paired respective lymph node or distant metastasis, respectively. Furthermore, the percentage of E-cadherin⁺/vimentin⁺ cells in grade II and III carcinomas was significantly higher than in grade I tumors. Primary tumors had significantly higher SNAIL/SLUG expression when analyzed based on the percentage of positive cells compared with their respective distant metastases in pairwise comparisons. An inverse correlation was noted between SNAIL/SLUG immunoreactivity and percentage of E-cadherin⁺/vimentin⁺ immunopositive cells in primary tumor samples when SNAIL/SLUG immunoreactivity was grouped into 2 categories (high versus low) based on percentage-positive staining. These results show a positive correlation between E-cadherin⁺/vimentin⁺ cells and higher tumor grade, establish differences between primary tumor and their respective metastases, and provide further support that EMT plays a critical role in the metastasis of canine mammary carcinoma. Furthermore, these data suggest that modulation of this process could provide greater therapeutic control and provide support for further research to determine if E-cadherin⁺/vimentin⁺ co-immunoreactivity imparts predictive value in the clinical outcome of patients with canine mammary carcinomas.

Canine mammary tumors as a model for human disease

Animal models for examining human breast cancer (HBC) carcinogenesis have been extensively studied and proposed. With the recent advent of immunotherapy, significant attention has been focused on the dog as a model for human cancer. Dogs develop mammary tumors and other cancer types spontaneously with an intact immune system, which exhibit a number of clinical and molecular similarities to HBC. In addition to the spontaneous tumor presentation, the clinical similarities between human and canine mammary tumors (CMT) include the age at onset, hormonal etiology and course of the diseases. Furthermore, factors that affect the disease outcome, including tumor size, stage and lymph node invasion, are similar in HBC and CMT. Similarly, the molecular characteristics of steroid receptor, epidermal growth factor, proliferation marker, metalloproteinase and cyclooxygenase expression, and the mutation of the p53 tumor suppressor gene in CMT, mimic HBC. Furthermore, ductal carcinomas in situ in human and canine mammary glands are particularly similar in their pathological, molecular and visual characteristics. These CMT characteristics and their similarities to HBC indicate that the dog could be an excellent model for the study of human disease. These similarities are discussed in detail in the present review, and are compared with the in vitro and other in vivo animal models available.

Multiplex Gene Expression Profiling of 16 Target Genes in Neoplastic and Non-Neoplastic Canine Mammary Tissues Using Branched-DNA Assay

Mammary gland tumors are one of the most common neoplasms in female dogs, and certain breeds are prone to develop the disease. The use of biomarkers in canines is still restricted to research purposes. Therefore, the necessity to analyze gene profiles in different mammary entities in large sample sets is evident in order to evaluate the strength of potential markers serving as future prognostic factors. The aim of the present study was to analyze the gene expression of 16 target genes (BRCA1, BRCA2, FOXO3, GATA4, HER2, HMGA1, HMGA2, HMGB1, MAPK1, MAPK3, MCL1, MYC, PFDN5, PIK3CA, PTEN, and TP53) known to be involved in human and canine mammary neoplasm development. Expression was analyzed in 111 fresh frozen (FF) and in 170 formalin-fixed, paraffin-embedded (FFPE) specimens of neoplastic and non-neoplastic canine mammary tissues using a multiplexed branched-DNA (b-DNA) assay. TP53, FOXO3, PTEN, and PFDN5 expression revealed consistent results with significant low expression in malignant tumors. The possibility of utilizing them as predictive factors as well as for assisting in the choice of an adequate gene therapy may help in the development of new and improved approaches in canine mammary tumors.

Downregulation of ATM Gene and Protein Expression in Canine Mammary Tumors

The ataxia telangiectasia mutated ( ATM) gene encodes a protein associated with DNA damage repair and maintenance of genomic integrity. In women, ATM transcript and protein downregulation have been reported in sporadic breast carcinomas, and the absence of ATM protein expression has been associated with poor prognosis. The aim of this study was to evaluate ATM gene and protein expression in canine mammary tumors and their association with clinical outcome. ATM gene and protein expression was evaluated by reverse transcription-quantitative polymerase chain reaction and immunohistochemistry, respectively, in normal mammary gland samples (n = 10), benign mammary tumors (n = 11), nonmetastatic mammary carcinomas (n = 19), and metastatic mammary carcinomas (n = 11). Lower ATM transcript levels were detected in benign mammary tumors and carcinomas compared with normal mammary glands ( P = .011). Similarly, lower ATM protein expression was observed in benign tumors ( P = .0003), nonmetastatic mammary carcinomas ( P < .0001), and the primary sites of metastatic carcinomas ( P < .0001) compared with normal mammary glands. No significant differences in ATM gene or protein levels were detected among benign tumors and nonmetastatic and metastatic mammary carcinomas ( P > .05). The levels of ATM gene or protein expression were not significantly associated with clinical and pathological features or with survival. Similar to human breast cancer, the data in this study suggest that ATM gene and protein downregulation is involved in canine mammary gland tumorigenesis.

Mechanisms of Drug Resistance in Veterinary Oncology- A Review with an Emphasis on Canine Lymphoma

Drug resistance (DR) is the major limiting factor in the successful treatment of systemic neoplasia with cytotoxic chemotherapy. DR can be either intrinsic or acquired, and although the development and clinical implications are different, the underlying mechanisms are likely to be similar. Most causes for DR are pharmacodynamic in nature, result from adaptations within the tumor cell and include reduced drug uptake, increased drug efflux, changes in drug metabolism or drug target, increased capacity to repair drug-induced DNA damage or increased resistance to apoptosis. The role of active drug efflux transporters, and those of the ABC-transporter family in particular, have been studied extensively in human oncology and to a lesser extent in veterinary medicine. Methods reported to assess ABC-transporter status include detection of the actual protein (Western blot, immunohistochemistry), mRNA or ABC-transporter function. The three major ABC-transporters associated with DR in human oncology are ABCB1 or P-gp, ABCC1 or MRP1, and ABCG2 or BCRP, and have been demonstrated in canine cell lines, healthy dogs and dogs with cancer. Although this supports a causative role for these ABC-transporters in DR cytotoxic agents in the dog, the relative contribution to the clinical phenotype of DR in canine cancer remains an area of debate and requires further prospective studies.

Mechanisms of tumour resistance against chemotherapeutic agents in veterinary oncology

Several classes of chemotherapy drugs are used as first line or adjuvant treatment of the majority of tumour types in veterinary oncology. However, some types of tumour are intrinsically resistant to several anti-cancer drugs, and others, while initially sensitive, acquire resistance during treatment. Chemotherapy often significantly prolongs survival or disease free interval, but is not curative. The exact mechanisms behind intrinsic and acquired chemotherapy resistance are unknown for most animal tumours, but there is increasing knowledge on the mechanisms of drug resistance in humans and a few reports on molecular changes in resistant canine tumours have emerged. In addition, approaches to overcome or prevent chemotherapy resistance are becoming available in humans and, given the overlaps in molecular alterations between human and animal tumours, these may also be relevant in veterinary oncology. This review provides an overview of the current state of research on general chemotherapy resistance mechanisms, including drug efflux, DNA repair, apoptosis evasion and tumour stem cells. The known resistance mechanisms in animal tumours and the potential of these findings for improving treatment efficacy in veterinary oncology are also explored.

Properties of cellular and serum forms of thymidine kinase 1 (TK1) in dogs with acute lymphocytic leukemia (ALL) and canine mammary tumors (CMTs): implications for TK1 as a proliferation biomarker

BACKGROUND

Thymidine kinase 1 (TK1) is a deoxyribonucleic acid (DNA) precursor enzyme and a proliferation biomarker used for prognosis and treatment monitoring of breast cancer in humans. The aim was to determine if serum thymidine kinase 1 (sTK1) activity and sTK1 protein levels in dogs with mammary tumors could be useful in veterinary medicine.

RESULTS

Serum samples from 20 healthy dogs and 27 dogs with mammary tumors were analyzed for sTK1 activity, using an [(3)H]-deoxythymidine (dThd) phosphorylation assay, and for sTK1 protein levels by immune affinity/Western blot assay. The molecular forms of sTK1 in acute lymphocytic leukemia (ALL), canine mammary tumor (CMT), and healthy sera were determined by size exclusion chromatography. Mean sTK1 activities in CMT were 1.0 ± 0.36 pmol/min/mL, differing significantly from healthy dogs (mean ± SD = 0.73 ± 0.26 pmol/min/mL). Serum TK1 protein (26 kDa polypeptide) levels were also significantly higher in CMTs compared to healthy dogs (mean ± SD = 28.5 ± 11.4, and 8.5 ± 4 ng/mL, respectively). Cellular TK1 isolated from ALL tumor cells was predominantly a dimer, while the serum TK1 activity eluted as a high molecular weight (MW) oligomer. In analyses of CMT tissue extracts, TK1 activity eluted in two peaks, a minor peak with a high MW oligomer and a major tetramer peak. Western blot analysis of chromatographic fractions showed that cellular TK1 protein in both ALL and CMT dogs, and to some extent serum TK1 from ALL dogs, correlated with activity profiles, but a large fraction of inactive TK1 protein was detected in CMT.

CONCLUSIONS

Serum TK1 protein and activity levels were significantly higher in CMT than in healthy dogs. Size exclusion chromatography demonstrated major differences in the molecular forms of sTK1 in ALL, healthy, and CMT dogs, with a large fraction of inactive TK1 protein in CMT. Our results showed that the sTK1 protein assay can differentiate benign tumors (early stage tumors) from healthy more efficiently than sTK1 activity assay. This preliminary data supports that sTK1 protein assay is clinically useful. Further studies are needed to evaluate the diagnostic or prognostic role of serum TK1 protein in CMTs.

Global gene expression analysis of canine cutaneous mast cell tumor: could molecular profiling be useful for subtype classification and prognostication?

Prognosis and therapeutic management of dogs with cutaneous mast cell tumors (MCTs) depend on clinical stage and histological grade. However, the prognostic value of this latter is still questionable. In the present study, MCT transcriptome was analyzed to identify a set of candidate genes potentially useful for predicting the biological behavior of MCTs. Fifty-one canine MCT biopsies were analyzed. Isolated and purified total RNAs were individually hybridized to the Agilent Canine V2 4x44k DNA microarray. The comparison of reference differentiated and undifferentiated MCT transcriptome revealed a total of 597 differentially expressed genes (147 down-regulated and 450 up-regulated). The functional analysis of this set of genes provided evidence that they were mainly involved in cell cycle, DNA replication, p53 signaling pathway, nucleotide excision repair and pyrimidine metabolism. Class prediction analysis identified 13 transcripts providing the greatest accuracy of class prediction and divided samples into two categories (differentiated and undifferentiated), harboring a different prognosis. The Principal Component Analysis of all samples, made by using the selected 13 markers, confirmed MCT classification. The first three components accounted for 99.924% of the total variance. This molecular classification significantly correlated with survival time (p = 0.0026). Furthermore, among all marker genes, a significant association was found between mRNA expression and MCT-related mortality for FOXM1, GSN, FEN1 and KPNA2 (p<0.05). Finally, marker genes mRNA expression was evaluated in a cohort of 22 independent samples. Data obtained enabled to identify MCT cases with different prognosis. Overall, the molecular characterization of canine MCT transcriptome allowed the identification of a set of 13 transcripts that clearly separated differentiated from undifferentiated MCTs, thus predicting outcome regardless of the histological grade. These results may have clinical relevance and warrant future validation in a prospective study.

DNA damage response and DNA repair - dog as a model?

Background

Companion animals like dogs frequently develop tumors with age and similarly to human malignancies, display interpatient tumoral heterogeneity. Tumors are frequently characterized with regard to their mutation spectra, changes in gene expression or protein levels. Among others, these changes affect proteins involved in the DNA damage response (DDR), which served as a basis for the development of numerous clinically relevant cancer therapies. Even though the effects of different DNA damaging agents, as well as DDR kinetics, have been well characterized in mammalian cells in vitro, very little is so far known about the kinetics of DDR in tumor and normal tissues in vivo.

Discussion

Due to (i) the similarities between human and canine genomes, (ii) the course of spontaneous tumor development, as well as (iii) common exposure to environmental agents, canine tumors are potentially an excellent model to study DDR in vivo. This is further supported by the fact that dogs show approximately the same rate of tumor development with age as humans. Though similarities between human and dog osteosarcoma, as well as mammary tumors have been well established, only few studies using canine tumor samples addressed the importance of affected DDR pathways in tumor progression, thus leaving many questions unanswered.

Summary

Studies in humans showed that misregulated DDR pathways play an important role during tumor development, as well as in treatment response. Since dogs are proposed to be a good tumor model in many aspects of cancer research, we herein critically investigate the current knowledge of canine DDR and discuss (i) its future potential for studies on the in vivo level, as well as (ii) its possible translation to veterinary and human medicine.

Rad51 expression is a useful predictive factor for the efficacy of neoadjuvant chemoradiotherapy in squamous cell carcinoma of the esophagus

BACKGROUND

Neoadjuvant chemoradiotherapy (NACRT) for esophageal squamous cell carcinoma (ESCC) is beneficial in the setting of a complete pathological response. Rad51 expression affects both chemo- and radiosensitivity in many cancers; however, its role in ESCC is unclear.

METHODS

Rad51 expression was investigated by immunohistochemical staining with resected specimens in 89 ESCC patients who underwent surgery without preoperative therapy. The association with Rad51 and clinicopathological factors was assessed. The expression of Rad51 was also investigated in pretreatment biopsy specimens in 39 ESCC patients who underwent surgery after NACRT and compared with the pathological response to NACRT.

RESULTS

Lymph node metastasis was more frequently observed in Rad51-positive cases than negative cases (58.5 vs. 30.6%, P = 0.0168) in patients treated with surgery alone. Disease-specific survival was decreased in Rad51-positive cases compared to Rad51-negative cases (5 year survival: 79.6 vs. 59.3%, P = 0.0324). In NACRT patients, completed pathological responses were more frequently observed in Rad51-negative cases than in Rad51-positive cases (68.8 vs. 46.5%, P = 0.0171).

CONCLUSIONS

Rad51 expression in ESCC was associated with lymph node metastasis and poor survival. Additionally, Rad51 expression in pretreatment biopsy specimens was a predictive factor for the response to NACRT.

Molecular quantification of canine specific microRNA species

MicroRNAs (miRNAs) belong to the heterogeneous group of non-coding, regulatory RNA molecules. They play an important role in physiological functions, especially during tissue development. Moreover, their cell-type specific expression levels are also thought to be altered in association with different pathological conditions, including metabolic disorders and cancer. However, the vast majority of molecular assays for their quantification have been established for humans and mice, with no reports on specific research tools for dogs. Here canine-specific SYBRGreen based quantitative, real-time PCR assays are introduced for the quantification of 21 miRNAs and five small nucleolar RNA (snoRNA). The assay includes a time-saving and economical universal one-tube cDNA synthesis approach which allows for a more robust relative quantification than the commonly used multiple specific reverse transcriptions. GeNorm and NormFinder analysis were used for the evaluation of potential housekeeping genes and identified miRNAs to be more stable housekeeping genes by trend.

Trace elements and carcinogenicity: a subject in review

Cancer is known to be a multi-step process, which involves different stages including initiation, promotion, progression and metastasis. Chemical carcinogens including most trace elements can change any of these processes to induce their carcinogenic effects. Various studies confirm that cancer arises from the accumulation of irreversible DNA damage, which results from multiple mutations in critical genes in the body organ. Chemical carcinogens most often directly or after xenobiotic metabolism, act as genotoxic causes to induce DNA damage. Genotoxic carcinogen refers to a group of chemicals capable of producing cancer by directly altering the genetic material of target cells. Other carcinogens are however classified as non-genotoxic, which represents chemicals that are capable of producing cancer by some secondary mechanism not related to direct gene damage. They act as tumor promoters, endocrine-modifiers, receptor mediators, immunosuppressant, or inducers of tissue-specific toxicity and inflammatory responses. The diversity of modes of action, of non-genotoxic carcinogens, the tissue and species specificity and the absence of genotoxicity makes it extremely hard to predict their carcinogenic potential. The roles of trace metals (some of which are either genotoxic or non-genotoxic) in cancer development and inhibition have a complex character and have raised many questions because of their essential and toxic effects on people's health. Trace metals such as cadmium, nickel, arsenic, beryllium and chromium (VI) have been recognized as human or animal carcinogens by International Agency for Research on Cancer (IARC). The Carcinogenic capability of these metals depends mainly on factors such as oxidation states and chemical structures. The oxidative concept in metal carcinogenesis proposes that complexes formed by these metals, in vivo, in the vicinity of DNA, catalyze redox reactions, which in turn oxidize DNA. The most significant effect of reactive oxygen species in the carcinogenesis progression is DNA damage, which results in DNA lesions like strand breaks and the sister-chromatid exchange. This article reviews the carcinogenicity of various trace elements.

Multiple RT-PCR markers for the detection of circulating tumour cells of metastatic canine mammary tumours

In humans, detection of circulating tumour cells (CTCs) using nucleic acid-based methods such as reverse transcription polymerase chain reaction (RT-PCR) has proven to be of prognostic relevance. However, similar procedures are still lacking in veterinary oncology. To assess the correlation of CTC markers with the metastatic potential of canine mammary tumours, 120 peripheral blood samples from bitches with mammary carcinomas with (group 1) and without (group 2) histological evidence of vascular invasion and/or presence of lymph node metastases and mammary adenomas (group 3) were analyzed. Blood samples were collected in EDTA tubes and RNA was extracted within 48 h. Subsequently, the samples were tested by RT-PCR for a panel of seven CTC mRNA markers. CRYAB was the most sensitive single marker with a sensitivity of 35% and also the most specific marker with a specificity of 100% to detect group 1 blood samples. A multimarker assay combining four genes enhanced the sensitivity up to 77.5%, but decreased the specificity to 80%. CRYAB appeared to be highly specific but only moderately sensitive at detecting blood samples from dogs with metastatic tumours and detection significantly correlated with vascular invasion of primary mammary tumours. However, a multimarker assay of four genes significantly enhanced the sensitivity of the assay and is therefore preferable for CTC detection.

Differences in the proteome of high-grade versus low-grade canine cutaneous mast cell tumours

Cutaneous mast cell tumours (MCTs) are the most common skin tumours in dogs. However, the molecular differences between benign tumours with a good prognosis and highly malignant, invasive and metastatic tumours with short survival times are for the most part unclear. In the present study the proteome of low-grade MCTs with a good prognosis was compared with that of poor-prognosis high-grade tumours independent of their mutational status of exon 11 of the KIT gene. Using two-dimensional difference gel electrophoresis and mass spectrometry, 13 proteins with a significant differential expression between the two groups were identified. Four stress response proteins (HSPA9, PDIA3, TCP1A and TCP1E) were significantly up-regulated in high-grade tumours, while proteins mainly associated with cell motility and metastasis had either increased (WDR1, ACTR3, ANXA6) or decreased (ANXA2, ACTB) expression levels. High-grade tumours also had a paradox down-regulation of transferrin, a protein that is usually up-regulated in neoplastic cells. The histologically observable dedifferentiation of high-grade tumours was reflected by decreased tryptase protein expression levels. Results of quantitative real-time RT-PCR analysis indicated that the differences in protein expression levels of most proteins were regulated at the transcript level. Based on these findings, it is hypothesized that high-grade MCT cells have a higher resistance to cellular stress and thus are able to better cope with the adverse environment in highly proliferating tumours independent of increased KIT signalling. It is noteworthy that some of the proteins identified have been proposed as therapeutic targets for human oncology and it will be interesting to evaluate their therapeutic and diagnostic potential for canine MCTs.

Weigners fixative-an alternative to formalin fixation for histology with improved preservation of nucleic acids

Formalin fixation and paraffin embedding (FFPE) is the standard method for tissue storage in histopathology. However, FFPE has disadvantages in terms of user health, environment, and nucleic acid integrity. Weigners fixative has been suggested as an alternative for embalming cadavers in human and veterinary anatomy. The present study tested the applicability of Weigners for histology and immunohistochemistry and the preservation of nucleic acids. To this end, a set of organs was fixed for 2 days and up to 6 months in Weigners (WFPE) or formalin. WFPE tissues from the skin, brain, lymphatic tissues, liver, and muscle had good morphologic preservation, comparable to formalin fixation. The quality of kidney and lung samples was inferior to FFPE material due to less accentuated nuclear staining and retention of proteinaceous interstitial fluids. Azan, Turnbull blue, toluidin, and immunohistochemical stainings for CD79a, cytokeratin, vimentin, and von Willebrand factor led to comparable results with both fixates. Of note, immunohistochemical detection of CD3 was possible after 6 months in WFPE but not in FFPE tissues. mRNA, miRNA, and DNA from WFPE tissues had superior quality and allowed for amplification of miRNA, 400-bp-long mRNA, and 1000-bp-long DNA fragments after 6 months of fixation in WFPE. In summary, Weigners fixative is a nonhazardous alternative to formalin, which provides a good morphologic preservation of most organs, a similar sensitivity for protein detection, and a superior preservation of nucleic acids. Weigners may therefore be a promising alternative to cryopreservation and may be embraced by people affected by formalin allergies.

CD25 Is Expressed by Canine Cutaneous Mast Cell Tumors but not by Cutaneous Connective Tissue Mast Cells

Canine cutaneous mast cell tumors (MCT) of different histological grades have distinct biological behaviors. However, little is known about underlying molecular mechanisms that lead to tumor development and increasing malignancy with higher tumor grade. Recent studies have identified the interleukin-2 receptor (IL-2R) subunits CD25 and CD2 as markers that distinguish nonneoplastic from neoplastic mast cells in human systemic mastocytosis. In this study, their potential as a marker for canine MCT and their possible impact on MCT carcinogenesis were evaluated. mRNA expression levels of both genes were compared between grade 1 ( n = 12) and grade 3 ( n = 8) MCT, and protein expression levels of CD25 were compared in 90 MCT of different tumor grades. mRNA expression levels of both CD25 and CD2 were upregulated in grade 3 MCT. In contrast, CD25 protein was expressed by fewer tumor cells and at decreased levels in grade 3 tumors, while most grade 1 MCT had strong CD25 protein expression. Moreover, CD25 was not expressed by nonneoplastic, resting cutaneous mast cells, while few presumably activated mast cells in tissue samples from dogs with allergic dermatitis had weak CD25 expression. Taken together, these findings suggest that CD25 may play a critical role in early MCT development and may be a stimulatory factor in grade 1 MCT, while grade 3 MCT seem to be less dependent on CD25. Because of the low number of CD25-positive tumor cells in high-grade tumors, the usefulness of CD25 as a tumor marker is, however, questionable.

Canine tumors: a spontaneous animal model of human carcinogenesis

The enormous biologic complexity of human cancer has stimulated the development of more appropriate experimental models that could resemble in a natural and spontaneous manner the physiopathologic aspects of cancer biology. Companion animals have many desired characteristics that fill the gap between in vitro and in vivo studies, and these characteristics have proven to be important in understanding many complex molecular aspects of human cancer. Spontaneous tumors in dogs share a wide variety of epidemiologic, biologic, and clinical features with human cancer, which makes this animal model both attractive and underused in oncology research. In this review, we summarize the importance of naturally occurring canine tumors as valuable tools for studying numerous aspects of human cancer as well as the potential use of this animal model for the development of new cancer treatments. We address specifically the use of canine mammary tumors as an increasingly powerful model to study human breast cancer.

Transcriptome and proteome research in veterinary science: what is possible and what questions can be asked?

In recent years several technologies for the complete analysis of the transcriptome and proteome have reached a technological level which allows their routine application as scientific tools. The principle of these methods is the identification and quantification of up to ten thousands of RNA and proteins species in a tissue, in contrast to the sequential analysis of conventional methods such as PCR and Western blotting. Due to their technical progress transcriptome and proteome analyses are becoming increasingly relevant in all fields of biological research. They are mainly used for the explorative identification of disease associated complex gene expression patterns and thereby set the stage for hypothesis-driven studies. This review gives an overview on the methods currently available for transcriptome analysis, that is, microarrays, Ref-Seq, quantitative PCR arrays and discusses their potentials and limitations. Second, the most powerful current approaches to proteome analysis are introduced, that is, 2D-gel electrophoresis, shotgun proteomics, MudPIT and the diverse technological concepts are reviewed. Finally, experimental strategies for biomarker discovery, experimental settings for the identification of prognostic gene sets and explorative versus hypothesis driven approaches for the elucidation of diseases associated genes and molecular pathways are described and their potential for studies in veterinary research is highlighted.

The level of secretory leukocyte protease inhibitor is decreased in metastatic head and neck squamous cell carcinoma

Head and neck squamous cell carcinomas (HNSCC) represent the sixth largest group among all human malignancies. However, the exact molecular mechanisms inducing the genesis and the progression of metastasis in these tumors are poorly understood. The identification of molecular alterations involved in metastasis of HNSCC might influence the value of clinical diagnostics, impact therapy strategies and finally improve the prognosis of the patients. The purpose of this study was to identify clinically relevant alterations at the transcriptional and translational levels, when comparing metastatic (N+) and non-metastatic (N0) primary HNSCC. Three transcripts HERPUD1, SLPI and RAD51 were selected for further validation based on their association with carcinogenesis and metastasis. Quantitative real-time-PCR was performed to determine the mRNA expression levels. For subsequent confirmation of the results, immunohistochemistry was performed applying a monoclonal anti-SLPI antibody on 121 HNSCC tumor specimens (N0, n=40; N+, n=81). In metastatic primary cancer, SLPI mRNA showed 5.9-fold lower expression in comparison with non-metastatic primary cancer (p=0.0092). Immunohistochemical staining revealed a fold change of -1.79 between the N+ and the N0 group (p=0.0002). The results presented here clearly indicate the repression of SLPI, measurable on both, mRNA and protein levels in metastatic primary HNSCC as compared to non-metastatic HNSCC. Therefore, it can be assumed that SLPI might have a substantial protective effect on the metastasis process of HNSCC.

Molecular carcinogenesis of canine mammary tumors: news from an old disease

Studies focusing on the molecular basis of canine mammary tumors (CMT) have long been hampered by limited numbers of molecular tools specific to the canine species. The lack of molecular information for CMT has impeded the identification of clinically relevant tumor markers beyond histopathology and the introduction of new therapeutic concepts. Additionally, the potential use for the dog as a model for human breast cancer is debatable until questions are answered regarding cellular origin, mechanisms, and cellular pathways. During the past years, increasing numbers of canine molecular tools have been developed on the genomic, RNA, and protein levels, and an increasing number of studies have shed light on specific aspects of canine carcinogenesis, particularly of the mammary gland. This review summarizes current knowledge on the molecular carcinogenesis of CMT, including the role of specific oncogenes, tumor suppressors, regulators of apoptosis and DNA repair, proliferation indices, adhesion molecules, circulating tumor cells, and mediators of angiogenesis in CMT progression and clinical behavior. Whereas the data available are far from complete, knowledge of molecular pathways has a significant potential to complement and refine the current diagnostic and therapeutic approach to this tumor type. Furthermore, current data show that significant similarities and differences exist between canine and human mammary tumors at the molecular level. Clearly, this is only the beginning of an understanding of the molecular mechanisms of CMT and their application in clinical patient management.

The metastatic cascade is reflected in the transcriptome of metastatic canine mammary carcinomas

Proliferation, dedifferentiation and loss of cell-cell contacts are amongst the first steps of the metastatic cascade. The complex molecular pathways and gene expression changes associated with these events in canine mammary tumors are still largely undetermined. In this study, the transcriptome of 13 lymph node positive canine mammary carcinomas and corresponding non-neoplastic mammary glands were compared to identify the molecular pathways associated with metastatic progression. Differential gene expression was analyzed using gene set enrichment and pathway analysis and compared with gene expression data from human breast cancer. Metastatic canine carcinomas had 1312 significantly differentially expressed genes compared to normal mammary glands. This expression profile included a significant up-regulation of cell division and matrix invasion genes (MMP, SERPINE1, TIMP3). In contrast, genes associated with epithelial differentiation (EGF, EGFR, MAP2K6, STAT 5), cell adhesion (CLDN5, CTNNAL1, MUC1, PECAM1) and angiogenesis (ANGPT 2, ANGPTL1-4, FIGF, TIE1) were mostly down-regulated. Tumors had a significant decrease in membrane receptors and pathway gene expression (EGFR, FGFR1, GHR, PDGFR, TGFBR, TIE1) indicating a tendency towards independence from these proliferative stimuli. A number of the identified deregulated pathways overlapped with gene expression profiles of human breast cancer. Gene expression profiling of metastatic carcinomas, therefore, identified molecular pathways and functional gene families that are deregulated during malignant progression in canine mammary tumors.

Metastatic canine mammary carcinomas can be identified by a gene expression profile that partly overlaps with human breast cancer profiles

Background

Similar to human breast cancer mammary tumors of the female dog are commonly associated with a fatal outcome due to the development of distant metastases. However, the molecular defects leading to metastasis are largely unknown and the value of canine mammary carcinoma as a model for human breast cancer is unclear. In this study, we analyzed the gene expression signatures associated with mammary tumor metastasis and asked for parallels with the human equivalent.

Methods

Messenger RNA expression profiles of twenty-seven lymph node metastasis positive or negative canine mammary carcinomas were established by microarray analysis. Differentially expressed genes were functionally characterized and associated with molecular pathways. The findings were also correlated with published data on human breast cancer.

Results

Metastatic canine mammary carcinomas had 1,011 significantly differentially expressed genes when compared to non-metastatic carcinomas. Metastatic carcinomas had a significant up-regulation of genes associated with cell cycle regulation, matrix modulation, protein folding and proteasomal degradation whereas cell differentiation genes, growth factor pathway genes and regulators of actin organization were significantly down-regulated. Interestingly, 265 of the 1,011 differentially expressed canine genes are also related to human breast cancer and, vice versa, parts of a human prognostic gene signature were identified in the expression profiles of the metastatic canine tumors.

Conclusions

Metastatic canine mammary carcinomas can be discriminated from non-metastatic carcinomas by their gene expression profiles. More than one third of the differentially expressed genes are also described of relevance for human breast cancer. Many of the differentially expressed genes are linked to functions and pathways which appear to be relevant for the induction and maintenance of metastatic progression and may represent new therapeutic targets. Furthermore, dogs are in some aspects suitable as a translational model for human breast tumors in order to identify prognostic molecular signatures and potential therapeutic targets.

The Combined Expression Pattern of BMP2, LTBP4, and DERL1 Discriminates Malignant From Benign Canine Mammary Tumors

Several markers of malignancy have been proposed for canine mammary tumors on the mRNA and protein levels. However, their association with tumor malignancy applies only for mean values of large groups of tumors, but no single marker identified to date can be used to reliably predict malignancy for individual tumors. A quantitative real-time reverse transcription polymerase chain reaction array was established to quantify the expression levels of 49 genes relevant to carcinogenesis in laser-microdissected tumor cells of 10 benign and 13 metastatic canine mammary tumors. Analysis of variance and discriminant analysis were used to identify relevant gene expression patterns that differentiate adenomas from metastatic carcinomas and their lymph node metastases. Seventeen genes with significant ( P < .05) differences in gene expression levels between benign and malignant tumors were identified—including ERBB1, SLIT2, progesterone receptor, MIG6, SATB1, and SMAD6—but correct classification of each tumor as benign or malignant was impossible on the basis of any of these genes alone. However, the combined expression patterns of BMP2, LTBP4, and DERL1 (Derlin-1) correctly classified each individual tumor as benign or malignant. This pilot study identified a complex mRNA expression pattern of 3 genes that was able to identify malignancy in laser-microdissected tumor cells for each individual tumor, instead of group means as used in previous studies.

HEPACAM1 and 2 are differentially regulated in canine mammary adenomas and carcinomas and its lymph node metastases

BACKGROUND

Cell adhesion is an important regulator of cell growth and motility. Recently the hepatocyte cell adhesion molecules 1 and 2 (HEPACAM1 and 2), members of the immunoglobulin family of adhesion genes, have been identified. HEPACAM1 is involved in negative cell cycle regulation via p53, p21 and p27 signalling but also mediates increased human breast cancer cell spread. The role and expression pattern of HEPACAM2 has not been analyzed so far. In the present study we quantified gene expression levels of HEPACAM1 and 2 to evaluate their possible role during the carcinogenesis of canine mammary tumours.

RESULTS

Adenomas displayed increased HEPACAM1 and 2 mRNA expression levels and decreased HEPACAM1 protein expression levels when compared to normal gland, carcinomas and lymph node metastases. In contrast, metastatic carcinomas, intravascular tumour cells and lymph node metastases had HEPACAM 1 protein and mRNA expression levels similar to normal gland but decreased HEPACAM2 mRNA expression when compared to normal gland of the same dog.

CONCLUSIONS

HEPACAM1 and 2 seem to be important for cell-cell adhesion of normal and neoplastic canine mammary cells. The loss of HEPACAM1 protein expression in adenomas but not in carcinomas questions its role as a tumour suppressor at late stages of malignant transformation and indicates that it might rather be involved in physiologic mammary cell adhesion and canine mammary tumour metastasis. Furthermore, it can be speculated, whether HEPACAM2 plays a different role in malignancy and metastasis of canine mammary tumours since its transcriptional levels are different in carcinomas and their lymph node metastases when compared to HEPACAM1.

RAD51 Protein Expression Is Increased in Canine Mammary Carcinomas

RAD51 is a key enzyme of homologous recombination and repair of DNA double-strand breaks. RAD51 mRNA expression levels are significantly increased in laser-microdissected mammary simple carcinomas and their lymph node metastases when compared to adenomas or nonneoplastic mammary gland of the same dog. Here, RAD51 protein expression was analyzed by immunohistochemistry in paraffin-embedded mammary carcinomas and their lymph node metastases of 40 dogs, adenomas of 48 dogs, and nonneoplastic mammary gland of 88 dogs. Number of cells with nuclear RAD51 expression was significantly ( P ≤ .05) increased in carcinomas when compared to adenomas and metastases. In contrast, no significant differences in the number of RAD51-expressing cells were detected when metastases were compared with adenomas and nonneoplastic gland. RAD51 expression in carcinomas was correlated with expression in metastases but not with histologic grade. In conclusion, the increased number of RAD51-expressing cells in carcinomas might indicate genomic instability in these cells. Nevertheless, the increased RAD51 mRNA expression in metastases could not be confirmed by immunohistochemistry.