Loss of p27 expression in canine mammary tumors and their metastases

Histopathological Grading, Clinical Staging and CD 31 Expression of Canine Splenic Hemangiosarcoma

Canine hemangiosarcoma is a common, highly fatal tumor of older dogs, and predictors of survivability may provide clinically useful information. The objectives of this case series were to determine if a previously published tumor histological grading scheme, the level of tumor cellular atypia, clinical staging, or the level of CD 31 expression were useful for predicting the survival time in dogs with splenic hemangiosarcoma. Canine splenic hemangiosarcomas from 16 dogs were histologically graded, clinically staged, and assessed for CD 31 expression. Medical records were reviewed, the date of death was obtained, and survival data were analyzed statistically. Histopathological grading and clinical staging of canine splenic hemangiosarcomas, and the expression of CD 31 by the tumor cells were not significantly associated with the median survival time of the dogs in this study. However, strong expression of CD 31 by canine splenic hemangiosarcoma tumor cells was observed in dogs with short survival times, which warrants further studies to evaluate the potential prognostic value of CD 31 expression for the survival of dogs with splenic hemangiosarcoma.

Molecular phenotyping of malignant canine mammary tumours: Detection of high-risk group and its relationship with clinicomolecular characteristics

Canine mammary gland tumours (CMTs) constitute the most common cancer in female dogs and comprise approximately 50% of all canine cancers. With the advent of high-throughput technologies such as microarray and next-generation sequencing, the molecular phenotyping (classification) of various cancers has been extensively developed. The present study used a canine RNA-sequencing dataset, namely GSE119810, to classify 113 malignant CMTs and 64 matched normal samples via an unsupervised hierarchical algorithm with a view to evaluating the association between the resulting subtypes (clusters) (n = 4) and clinical and molecular characteristics. Finally, a molecular classifier was developed, and it detected 1 high-risk molecular subtype in the training dataset (GSE119810) and 2 independent validation datasets (GSE20718 and GSE22516). Our results revealed four molecular subtypes (C2-C5) in malignant CMTs. Furthermore, the normal samples constituted a distinct group in the clustering analysis. Marked significant associations were observed between the molecular subtypes (especially C5) and clinical/molecular features, including positive lymphatic invasion, high tumour grades, histopathology diagnoses, short survival and high TP53 mutation rates (ps <.05). The high-risk subtype (C5) was further characterized through the development of a cell cycle-based gene signature, which comprised 37 proliferation-related genes according to the support vector machine algorithm. This signature identified the high-risk group in both training and validation datasets (ps <.001). In the validation analysis, our potential classifier robustly predicted patients with positive lymphatic invasion, metastases and short survival.

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.

In vitro study to assess the efficacy of CDK4/6 inhibitor Palbociclib (PD-0332991) for treating canine mammary tumours

Therapy of canine mammary tumours (CMTs) with classical antitumour drugs is problematic, so better therapeutic options are needed. Palbociclib (PD-0332991) is an innovative and effective anticancer drug for the treatment of breast cancer in women. Palbociclib is an inhibitor of cyclin-dependent kinase 4 (CDK4) and CDK6, which are key regulators of the cell cycle machinery and thus cell proliferation. In the present in vitro study, we investigated whether Palbociclib also represents a candidate drug to combat CMT. For this purpose, the effect of Palbociclib was analysed in P114 and CF41 cells, two CMT cell lines with an endogenous CDK4/6 co-expression. Incubation of P114 and CF41 cells with Palbociclib resulted in a dose- and time-dependent loss of phosphorylated retinoblastoma protein (pRb), a classical CDK4/6 substrate within the cell cycle machinery. Moreover, treatment of CMT cells with Palbociclib-induced cell cycle arrest affected cell viability, prevented colony formation and impaired cell migration activity. Palbociclib also inhibited the growth of P114 and CF41 cell spheroids. Immunohistochemical analysis of canine patient samples revealed a consistent expression of CDK6 in different canine mammary carcinoma types, but an individual and tumour-specific expression pattern of phosphorylated pRb independent of the tumour grade. Together, our findings let us suggest that Palbociclib has antitumour effects on CMT cells and that canine patients may represent potential candidates for treatment with this CDK4/6 inhibitor.

Hypermethylated in cancer 1 (HIC1) suppresses bladder cancer progression by targeting yes-associated protein (YAP) pathway

OBJECTIVES

Bladder cancer (BCa) is the most common malignant tumor in the urinary system. Growing evidence suggests that as a tumor suppressor gene, hypermethylated in cancer 1 (HIC1) is correlated with various malignancies in the modulation of tumor progression. This study aims to investigate the effect of HIC1 on regulating the proliferation, migration, and invasion of BCa.

METHODS

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot (WB) were used to evaluate the expression of HIC1 messenger RNA and protein in human BCa tissues and cells. Proliferation, migration and invasion assays, and flow cytometry assay were performed to assess the biological functional role of HIC1 in BCa. Co-immunoprecipitation (Co-IP) examined the protein-protein interaction. The signaling pathways involved in the mode of action of HIC1 in BCa were also investigated.

RESULTS

HIC1 was found downregulated in tested samples. Cloning formation assay and cell-proliferation activity analysis showed that overexpression of HIC1 significantly inhibited the proliferation of BCa cells, while knockdown led to the opposite, namely the promotion of the proliferation. Flow cytometry assay confirmed the arrest of the cell cycle at the G1 phase with overexpression of HIC1 observed. Moreover, HIC1 inhibited migration and invasion of BCa. Co-IP showed the binding between YAP (yes-associated protein) and TEAD (TEA domain/transcription enhancer factor family members) as well as the cancerostatic activity of HIC1, partially manifested via its negative regulation of YAP signaling pathway.

CONCLUSIONS

Our data unprecedently showed that HIC1 was responsible for the inhibition of proliferation, migration, and invasion of BCa via the YAP signaling pathway. These findings suggested that therapeutic strategies regulating HIC1 expression might provide effective treatments for BCa.

Expression of cell cycle inhibitors in canine prostate with proliferative inflammatory atrophy and carcinoma

ABSTRACT Gene expression of CDKN1A, CDKN1B, and TP53, and immunostaining of p21, p27 and p53 were evaluated to verify the role of these cell cycle inhibitors in canine prostates with proliferative inflammatory atrophy-PIA and prostatic carcinoma-PC. Seventy samples, 15 normal, 30PIA and 25PC. Regarding number of p27 and p53 labeled cells, difference between normal and PIA and PC was observed, as well as between PIA and PC for p53. Immunostaining intensities of p21, p27 and p53 were different when comparing normal tissues to PIA and PC. Sixteen cDNA of canine prostatic FFPE tissue were subjected to RT-PCR and RT-qPCR, four normal, three PIA, and nine PC. CDKN1A mRNA was detected in four PC by RT-PCR, and it was overexpressed when compared to normal by RT-qPCR, in one PIA and six PC. CDKN1B mRNA was detected in three PC by RT-PCR and it was overexpressed in three PC and decreased in one PC. TP53 mRNA was overexpressed in one PIA and three PC. In conclusion, when overexpressed in canine prostate with premalignant and malignant, p21 and p27 play a role controlling cell proliferation, working as a protective factor in the evolution of PIA to PC, and in the PC development, even in the presence of altered p53.

Anti-tumour effect of metformin in canine mammary gland tumour cells

Metformin is an oral hypoglycaemic drug used in type 2 diabetes. Its pharmacological activity reportedly involves mitochondrial respiratory complex I, and mitochondrial respiratory complex inhibitors have a strong inhibitory effect on the growth of metastatic canine mammary gland tumour (CMGT) cell lines. It is hypothesised that metformin has selective anti-tumour effects on metastatic CMGT cells. The aim of this study was to investigate the in vitro effect of metformin on cell growth, production of ATP and reactive oxygen species (ROS), and the AMP-activated protein kinase (AMPK) mammalian target of rapamycin (mTOR) pathway in two CMGT clonal cell lines with different metastatic potential. In addition, transcriptome analysis was used to determine cellular processes disrupted by metformin and in vivo anti-tumour effects were examined in a mouse xenograft model. Metformin inhibited CMGT cell growth in vitro, with the metastatic clone (CHMp-5b) displaying greater sensitivity. ATP depletion and ROS elevation were observed to a similar extent in the metastatic and non-metastatic (CHMp-13a) cell lines after metformin exposure. However, subsequent AMPK activation and mTOR pathway inhibition were prominent only in metformin-insensitive non-metastatic cells. Microarray analysis revealed inhibition of cell cycle progression by metformin treatment in CHMp-5b cells, which was further confirmed by Western blotting and cell cycle analysis. Additionally, metformin significantly suppressed tumour growth in xenografted metastatic CMGT cells. In conclusion, metformin exhibited an anti-tumour effect in metastatic CMGT cells through AMPK-independent cell cycle arrest. Its mechanism of action differed in the non-metastatic clone, where AMPK activation and mTOR inhibition were observed.

Overview of calpain-mediated regulation of bone and fat mass in osteoblasts

The receptor for parathyroid hormone (PTH) and PTH-related peptide (PTH1R) belongs to the class II G protein-coupled receptor superfamily. The calpain small subunit encoded by the gene Capns1 is the second protein and the first enzyme identified by a yeast two-hybrid screen using the intracellular C-terminal tail of the rat PTH1R. The calpain regulatory small subunit forms a heterodimer with the calpain large catalytic subunit and modulates various cellular functions as a cysteine protease. To investigate a physiological role of the calpain small subunit in cells of the osteoblast lineage, we generated osteoblast-specific Capns1 knockout mouse models and characterized their bone phenotype. Molecular mechanisms by which calpain modulates cell proliferation of the osteoblast lineage were further examined in vitro. Moreover, we utilized the mutant mice as a disease model of osteoporosis accompanied with impaired bone resorptive function and suggested a possible clinical translation of our basic research finding.

Identification of six potential markers for the detection of circulating canine mammary tumour cells in the peripheral blood identified by microarray analysis

The presence of circulating tumour cells (CTCs) in the peripheral blood is a prognostic factor for survival of human breast cancer patients. CTCs in the peripheral blood of dogs with mammary tumours have not been reported definitively. The present pilot study identifies mRNA markers for CTCs by comparing the transcriptome of canine mammary carcinoma cell lines CMM26 and CMM115 and peripheral blood leucocytes (PBLs). Genes with a 200-fold or higher mRNA expression in carcinoma cell lines were tested for specificity and sensitivity to detect CTCs using reverse transcriptase polymerase chain reaction (PCR). Six mRNA markers, AGR2, ATP8B1, CRYAB, F3 IRX3 and SLC1A1 were expressed in cell lines, but not PBL. All PCRs were able to detect one carcinoma cell admixed in 10(6) or more PBLs. The six mRNA markers may be suitable for detection of canine mammary CTCs and allow the analysis of their spatiotemporal distribution in dogs with mammary tumours.

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.