Non-neoplastic Mammary Tissues Research Articles

Advancing canine mammary tumor diagnostics: Unraveling the diagnostic potential of Cytokeratin 19 through droplet digital PCR analysis

Cytokeratin 19 (CK19) is a complex intracytoplasmic cytoskeletal protein primarily localized in the ducts of the mammary gland and skin epithelial cells. In humans, the expression of CK19 gene within circulating tumor cells (CTCs) extracted from blood samples of breast cancer patients reflects tumor cell activity, offering valuable insights for predicting early metastatic relapse or monitoring treatment effectiveness. However, knowledge of serum tumor markers is limited in veterinary oncology. Recently, droplet digital PCR (ddPCR), has been employed to explore rare target genes due to its heightened sensitivity and accuracy as a novel molecular diagnostic tool. The objectives of this study were to investigate the expression of the CK19 mRNA in CTCs, non-neoplastic mammary tissues, and both benign and malignant canine mammary tumors (CMTs) through ddPCR analysis. In Study I, we optimized the discard volume for blood samples to reduce CK19 contamination from skin epithelial cells post-venipuncture. The results revealed that discarding the initial 3mL of blood was adequate and effective in eliminating CK19 mRNA contamination. In Study II, after the removal of the initial 3mL of blood, we investigated CK19 mRNA-positive CTCs in the peripheral blood of normal healthy dogs, including those with benign and malignant CMTs. Intriguingly, CK19 mRNA was undetectable in all blood samples. The expression of CK19 mRNA in mammary tissues was investigated in Study III. The copy number (CN) ratios of the CK19 gene in non-neoplastic mammary tissues (14.77±14.65) were significantly higher (P<0.05) than those in benign (4.23±3.35) and malignant groups (6.56±5.64). Notably, no difference was observed between the benign and malignant groups. In conclusion, CK19 mRNA appeared unlikely to be a suitable candidate as a biomarker in the peripheral blood of CMTs, while the CN ratio in mammary tissues could serve as a potential discriminator between non-neoplastic and CMT groups, complementing the gold standard of histopathological examination.

Validation of droplet digital PCR for cytokeratin 19 mRNA detection in canine peripheral blood and mammary gland

In humans, peripheral blood cytokeratin 19 (CK19) mRNA-positive circulating tumor cells (CTCs) was utilized to identify early-stage breast cancer patients with micrometastatic disease who are at risk for disease progression and monitor treatment response in patients with advanced disease. To our knowledge, there has been little research regarding CK19 in canine mammary tumors (CMTs) using molecular methods. A droplet digital PCR (ddPCR) is proposed as a precise and sensitive quantification of nucleic acid targets. Hence, this study aimed to validate a newly designed assay for CK19 detection in canine blood and mammary tissue, along with the reference gene HPRT, by ddPCR. All primers and probes showed a precise match with the exon region of target genes. The assay exhibited PCR efficacy of 90.4% and 91.0% for CK19 and HPRT amplifications with linearity, respectively. The annealing temperature (Ta) for duplex ddPCR was 55 °C, providing the highest concentrations of both genes tested by the synthetic plasmid DNA. The limit of detection (LOD) of CK19 and HPRT were 2.16 ± 1.27 and 2.44 ± 1.31 copies/µL, respectively. Finally, the ddPCR assay was validated with canine peripheral blood, non-neoplastic mammary tissues and spiked samples. Our findings provide a new platform for CK19 studies in CMT diagnosis through blood and mammary tissues.

Immunohistochemical Expression of p62 in Feline Mammary Carcinoma and Non-Neoplastic Mammary Tissue.

Simple SummaryThe p62 protein, also called sequestosome 1 (SQSTM1), is a ubiquitin-binding scaffold protein. The expression of p62 was statistically higher in carcinoma compared to non-neoplastic mammary glands. Our results, although preliminary, are similar to the results of breast cancer, therefore, also in the cat, p62 could be considered a possible oncotarget.The p62 protein, also called sequestosome 1 (SQSTM1), is a ubiquitin-binding scaffold protein. In human oncology, although the interest in the function of this protein is recent, the knowledge is now numerous, but its role in tumorigenesis is not yet clear. This preliminary study aims to evaluate the immunohistochemical expression of p62 in 38 cases of feline mammary carcinoma with different grades of differentiation and in 12 non-neoplastic mammary gland tissues, to assess the expression level and a possible correlation with malignancy. The expression of p62 was statistically higher in carcinoma compared to non-neoplastic mammary glands: 28 feline mammary carcinomas (73.7%) had a high p62 expression score, three (7.9%) had a moderate expression, while seven cases (18.4%) had a low expression. The grade of the differentiation of the carcinoma was not correlated with the p62 expression. This study represents the first approach in feline oncology that correlates p62 expression in feline mammary carcinoma. Our results, although preliminary, are similar to the results of human breast cancer, therefore, also in the cat, p62 could be considered a possible oncotarget.

Collagen molecular phenotypic switch between non-neoplastic and neoplastic canine mammary tissues

In spite of major advances over the past several decades in diagnosis and treatment, breast cancer remains a global cause of morbidity and premature death for both human and veterinary patients. Due to multiple shared clinicopathological features, dogs provide an excellent model of human breast cancer, thus, a comparative oncology approach may advance our understanding of breast cancer biology and improve patient outcomes. Despite an increasing awareness of the critical role of fibrillar collagens in breast cancer biology, tumor-permissive collagen features are still ill-defined. Here, we characterize the molecular and morphological phenotypes of type I collagen in canine mammary gland tumors. Canine mammary carcinoma samples contained longer collagen fibers as well as a greater population of wider fibers compared to non-neoplastic and adenoma samples. Furthermore, the total number of collagen cross-links enriched in the stable hydroxylysine-aldehyde derived cross-links was significantly increased in neoplastic mammary gland samples compared to non-neoplastic mammary gland tissue. The mass spectrometric analyses of type I collagen revealed that in malignant mammary tumor samples, lysine residues, in particular those in the telopeptides, were markedly over-hydroxylated in comparison to non-neoplastic mammary tissue. The extent of glycosylation of hydroxylysine residues was comparable among the groups. Consistent with these data, expression levels of genes encoding lysyl hydroxylase 2 (LH2) and its molecular chaperone FK506-binding protein 65 were both significantly increased in neoplastic samples. These alterations likely lead to an increase in the LH2-mediated stable collagen cross-links in mammary carcinoma that may promote tumor cell metastasis in these patients.

Quantitative analysis of HER2 mRNA expression by RNA in situ hybridization in canine mammary gland tumors: Comparison with immunohistochemistry analysis.

Spontaneously occurring canine mammary gland tumors share many features with human breast cancer, including biological behavior and histologic features. Compared to transgenic murine model, canine models have advantages including naturally occurring models of human diseases and cancer. In humans, breast cancer is divided into molecular subtypes based on ER, PR, and HER2 expression. In contrast with humans, few studies have evaluated these subtypes in canine mammary gland tumors, including expression of HER2. HER2 expression in canine mammary tissues has been further complicated by controversy regarding the antibody’s specificity. This study aimed to investigate c-erbB2 mRNA expression in retrospective formalin-fixed paraffin embedded samples, using RNA in situ hybridization with a novel quantitative assay and to compare this method with immunohistochemistry. Using 48 canine mammary tumor samples and 14 non-neoplastic canine mammary tissues, RNA in situ hybridization was performed with RNAscope® using a canine-specific target gene probe (ERBB2), and quantitative measurement was performed using the housekeeping gene (POLR2A) to calculate the target gene/housekeeping gene ratio. The ratio of ERBB2/POLR2A was quantified using open-source image analysis programs and compared with the immunohistochemistry results. A significant correlation was observed between the HER2 immunohistochemistry score and ERBB2/POLR2A RNA in situ hybridization (P < 0.001). When the HER2 immunohistochemistry score was 3+, significantly higher expression of HER2 mRNA was observed by RNA in situ hybridization. Interestingly, HER2 mRNA was also observed in non-neoplastic mammary tissues by RNA in situ hybridization. This assay potentially facilitates the reliable quantification of mRNA expression levels in retrospective formalin-fixed paraffin-embedded samples. Further studies are required to elucidate the role of HER2 in canine mammary gland tumors and to implement clinical trials in dogs.

PO-388 Epigenetic silencing of ZNF177 by MIR-877–3 p could be involved in cervical cancer progression

IntroductionBreast cancer (BC) is the most frequent neoplasia among women and one of the leading causes of cancer-related death worldwide. It is a clinically heterogeneous disease, with the triple negative (TN) as the most aggressive subtype. Epigenetic alterations are common molecular abnormalities in cancer, including changes in DNA methylation, microRNA profiling and post-translational modifications of histones. Aberrant DNA methylation has been recognised as one of the most common epigenetic modifications in BC. Methylation of certain genes is associated with pathological features, differential response to therapy or metastases during follow-up, being also a predictor of survival in BC; but little is known about its involvement in TN BC. Our objective was to identify the methylome of TN BC compared to that of non-neoplastic mammary tissue.Material and methodsA 450k-methylation array was performed to identify differentially methylated genes in 8 TN BC samples (T) and 5 non-neoplastic (N) tissues from reduction mammoplasties. For that, DNA was extracted, bisulphite-converted, whole-genome amplified and hybridised to Infinium HumanMethylation450 BeadChip array. The level of DNA methylation at each CpG locus (β-value) was calculated as M/(M+U), ranging from 0 (100% unmethylated, U) to 1 (100% methylated, M). Differentially expressed probes were obtained by limma t-test (False Discovery Rate<0.05). Those probes with delta β-value (Δβ)>0.2 and located in CpG islands in the 5´UTR, 1500–200 bp upstream the transcription start site or in the first exon, were considered. ADAM12, VWCE and TSPAN9 genes were selected for further validation by pyrosequencing in a series of 30 T and 20 n, using a PyroMark Q24 after PCR amplification. Protein expression was explored by immunohistochemistry.Results and discussionsA total of 700 hypermethylated and 349 hypomethylated probes in T compared to N, corresponding to 15 and 7 hyper- and hypomethylated genes, respectively, were found to fulfil our criteria. ADAM12, VWCE and TSPAN9 genes showed lower methylation levels in T than in N (p<0.05). The increased protein expression in T compared to N was confirmed, highlighting the causal role of the hypomethylation in the regulation of the expression of these genes. No association was found between these alterations and clinicopathological variables.ConclusionThis is the first description of ADAM12, VWCE and TSPAN9 hypomethylation and overexpression in TN BC compared to non-neoplastic mammary tissues.

PO-387 Differential gene methylation in triple negative breast cancer and non-tumoral mammary tissue

Introduction Breast cancer (BC) is the most frequent neoplasia among women and one of the leading causes of cancer-related death worldwide. It is a clinically heterogeneous disease, with the triple negative (TN) as the most aggressive subtype. Epigenetic alterations are common molecular abnormalities in cancer, including changes in DNA methylation, microRNA profiling and post-translational modifications of histones. Aberrant DNA methylation has been recognised as one of the most common epigenetic modifications in BC. Methylation of certain genes is associated with pathological features, differential response to therapy or metastases during follow-up, being also a predictor of survival in BC; but little is known about its involvement in TN BC. Our objective was to identify the methylome of TN BC compared to that of non-neoplastic mammary tissue. Material and methods A 450k-methylation array was performed to identify differentially methylated genes in 8 TN BC samples (T) and 5 non-neoplastic (N) tissues from reduction mammoplasties. For that, DNA was extracted, bisulphite-converted, whole-genome amplified and hybridised to Infinium HumanMethylation450 BeadChip array. The level of DNA methylation at each CpG locus (β-value) was calculated as M/(M+U), ranging from 0 (100% unmethylated, U) to 1 (100% methylated, M). Differentially expressed probes were obtained by limma t-test (False Discovery Rate 0.2 and located in CpG islands in the 5´UTR, 1500–200 bp upstream the transcription start site or in the first exon, were considered. ADAM12, VWCE and TSPAN9 genes were selected for further validation by pyrosequencing in a series of 30 T and 20 n, using a PyroMark Q24 after PCR amplification. Protein expression was explored by immunohistochemistry. Results and discussions A total of 700 hypermethylated and 349 hypomethylated probes in T compared to N, corresponding to 15 and 7 hyper- and hypomethylated genes, respectively, were found to fulfil our criteria. ADAM12, VWCE and TSPAN9 genes showed lower methylation levels in T than in N (p Conclusion This is the first description of ADAM12, VWCE and TSPAN9 hypomethylation and overexpression in TN BC compared to non-neoplastic mammary tissues.

Expression of A1 and A3 adenosine receptors in human breast tumors.

Adenosine receptors (A1, A2A, A2B, A3) play an important role in the regulation of growth, proliferation and death of cancer and normal cells. We recently showed the expression profile of A2A and A2B receptors in normal and tumor breast tissues. In the present study, we used semiquantitative RT-PCR to measure the A1 and A3 gene expression levels in normal and tumor breast tissues. Breast tumors (n = 18) and non-neoplastic mammary tissues (n = 10) were collected and histologically confirmed to be neoplastic or non-neoplastic, respectively. Total RNA was extracted and reverse transcribed into cDNA, and PCR was performed under optimized condition for each receptor subtype. Amplification of beta-actin mRNA served as control for RT-PCR. The PCR products were separated on 1.7% agarose gels. The intensity of the bands was quantitated with ImageJ software after normalization against beta-actin expression. All breast tumor and normal tissue specimens expressed A1 and A3 adenosine receptor transcripts. However, we observed that the expression level of the A3 receptor in tumor tissues was 1.27-fold that of normal tissues, whereas there was no significant difference between the expression levels of A1 in normal and tumor tissues. Interestingly, the results of the present study indicate that breast tumors exhibit a higher level of A3 transcripts (than normal tissues) and support the possible key role of A3 adenosine receptor in tumor development. However, further studies based on real-time quantitative RT-PCR are needed to identify the exact gene expression levels.

CDH22 hypermethylation is an independent prognostic biomarker in breast cancer

BackgroundCadherin-like protein 22 (CDH22) is a transmembrane glycoprotein involved in cell-cell adhesion and metastasis. Its role in cancer is controversial because it has been described as being upregulated in colorectal cancer, whereas it is downregulated in metastatic melanoma. However, its status in breast cancer (BC) is unknown. The purpose of our study was to determine the molecular status and clinical value of CDH22 in BC.ResultsWe observed by immunohistochemistry that the level of CDH22 expression was lower in BC tissues than in their matched adjacent-to-tumour and non-neoplastic tissues from reduction mammoplasties. Since epigenetic alteration is one of the main causes of gene silencing, we analysed the hypermethylation of 3 CpG sites in the CDH22 promoter by pyrosequencing in a series of 142 infiltrating duct BC cases. CDH22 was found to be hypermethylated in tumoral tissues relative to non-neoplastic mammary tissues. Importantly, this epigenetic alteration was already present in adjacent-to-tumour tissues, although to a lesser extent than in tumoral samples. Furthermore, CDH22 gene regulation was dynamically modulated in vitro by epigenetic drugs. Interestingly, CDH22 hypermethylation in all 3 CpG sites simultaneously, but not expression, was significantly associated with shorter progression-free survival (p = 0.015) and overall survival (p = 0.021) in our patient series. Importantly, CDH22 hypermethylation was an independent factor that predicts poor progression-free survival regardless of age and stage (p = 0.006).ConclusionsOur results are the first evidence that CDH22 is hypermethylated in BC and that this alteration is an independent prognostic factor in BC. Thus, CDH22 hypermethylation could be a potential biomarker of poor prognosis in BC.

Prevalence of the Prefoldin Subunit 5 Gene Deletion in Canine Mammary Tumors.

BackgroundA somatic deletion at the proximal end of canine chromosome 27 (CFA27) was recently reported in 50% of malignant mammary tumors. This region harbours the tumor suppressor gene prefoldin subunit 5 (PFDN5) and the deletion correlated with a higher Ki-67 score. PFDN5 has been described to repress c-MYC and is, therefore, a candidate tumor-suppressor and cancer-driver gene in canine mammary cancer. Aim of this study was to confirm the recurrent deletion in a larger number of tumors.MethodsDroplet digital PCR for PFDN5 was performed in DNA from 102 malignant, 40 benign mammary tumors/dysplasias, 11 non-neoplastic mammary tissues and each corresponding genomic DNA from leukocytes. The copy number of PFDN5 was normalized to a reference amplicon on canine chromosome 32 (CFA32). Z-scores were calculated, based on Gaussian distributed normalized PFDN5 copy numbers of the leukocyte DNA. Z-scores ≤ -3.0 in tissue were considered as being indicative of the PFDN5 deletion and called as such. The Ki-67 proliferation index was assessed in a subset of 79 tissue samples by immunohistochemistry.ResultsThe deletion was confirmed in 24% of all malignant tumors, detected in only 7.5% of the benign tumors and was not present in any normal mammary tissue sample. The subgroup of solid carcinomas (n = 9) showed the highest frequency of the deletion (67%) and those malignomas without microscopical high fraction of benign tissue (n = 71) had a 32% frequency (p<0.01 vs. benign samples). The Ki-67 score was found to be significantly higher (p<0.05) in the PFDN5-deleted group compared to malignant tumors without the deletion.ConclusionsA somatic deletion of the PFDN5 gene is recurrently present in canine mammary cancer, supporting a potential role in carcinogenesis. The association of this deletion with higher Ki-67 indicates an increased proliferation rate and thus a link to tumor aggressiveness can be hypothesized. The confirmation of earlier results warrants further studies on PFDN5 as cancer-driver gene.

HER-2 expression in canine morphologically normal, hyperplastic and neoplastic mammary tissues and its correlation with the clinical outcome

The proto-oncogene HER-2/neu (c-erbB-2) encodes a transmembrane receptor protein with tyrosine-kinase activity. Previous studies have shown that HER-2 protein over-expression is present in canine mammary tumours, however, possible prognostic and predictive analogies between protein over-expression patterns in canine and human species are still controversial. Thirty-five canine mammary carcinomas, 11 mammary adenomas, and normal, hyperplastic or dysplastic tissues taken at the marginal area of the tumours were evaluated by immunohistochemistry (IHC) for HER-2 expression, using the Hercept Test® system scoring guidelines. HER-2 over-expression was detected in 3/11 adenomas and 10/35 carcinomas. Normal, hyperplastic and dysplastic mammary tissues were also found to be positive. The correlations between HER-2 expression and tumour histological grading, mitotic index, the presence of lymphatic invasion, and overall survival (OS) were evaluated. In carcinomas, HER-2 positive status only correlated with the mitotic index. A positive correlation was also found between HER-2 positive status and the presence of HER-2 over-expression in normal, hyperplastic or/and dysplastic mammary tissues surrounding the tumours. The percentage of HER-2 over-expressing tumours was similar to the percentage previously observed in canine benign and malignant mammary tumours. However an investigation regarding morphologically normal and hyperplastic or dysplastic tissues surrounding neoplastic lesions also showed HER-2 over-expression. In contrast with human mammary tumours, this study confirmed that in canine species, HER-2 over-expression does not identify a subgroup of tumours with a poor prognosis. In fact, we found HER-2 over-expression in morphologically non-neoplastic mammary tissues, surrounding hyperplastic and neoplastic lesions.

Expression of A1 and A3 Adenosine Receptors in Human Breast Tumors

Adenosine receptors (A1, A2A, A2B, A3) play an important role in the regulation of growth, proliferation and death of cancer and normal cells. We recently showed the expression profile of A2A and A2B receptors in normal and tumor breast tissues. In the present study, we used semiquantitative RT-PCR to measure the A1 and A3 gene expression levels in normal and tumor breast tissues. Breast tumors (n = 18) and non-neoplastic mammary tissues (n = 10) were collected and histologically confirmed to be neoplastic or non-neoplastic, respectively. Total RNA was extracted and reverse transcribed into cDNA, and PCR was performed under optimized condition for each receptor subtype. Amplification of beta-actin mRNA served as control for RT-PCR. The PCR products were separated on 1.7% agarose gels. The intensity of the bands was quantitated with ImageJ software after normalization against beta-actin expression. All breast tumor and normal tissue specimens expressed A1 and A3 adenosine receptor transcripts. However, we observed that the expression level of the A3 receptor in tumor tissues was 1.27-fold that of normal tissues, whereas there was no significant difference between the expression levels of A1 in normal and tumor tissues. Interestingly, the results of the present study indicate that breast tumors exhibit a higher level of A3 transcripts (than normal tissues) and support the possible key role of A3 adenosine receptor in tumor development. However, further studies based on real-time quantitative RT-PCR are needed to identify the exact gene expression levels.

Expression of prolactin receptors in normal canine mammary tissue, canine mammary adenomas and mammary adenocarcinomas

BackgroundMammary tumors represent the most common neoplastic disease in female dogs. Recently, the promoting role of prolactin (PRL) in the development of human breast carcinoma has been shown. Possible proliferative, anti-apoptotic, migratory and angiogenic effects of PRL on human mammary cancer cells in vitro and in vivo were suggested. The effects of PRL are mediated by its receptor, and alterations in receptor expression are likely to play a role in tumor development. Currently, not much data is available about prolactin receptor (PRLR) expression in canine mammary tumors. To set the basis for investigations on the role of PRL in mammary tumorigenesis in this species, prolactin receptor expression was evaluated by semi-quantitative real time PCR and immunohistochemistry on 10 formalin-fixed, paraffin-embedded samples each of canine non-neoplastic mammary tissue, mammary adenomas and adenocarcinomas.ResultsThe highest PRLR expression levels were found in normal mammary tissue, while adenomas, and to an even higher degree adenocarcinomas, showed a significant decrease in prolactin receptor expression. Compared to normal tissue, PRLR mRNA was reduced 2.4 fold (p = 0.0261) in adenomas and 4.8 fold (p = 0.008) in adenocarcinomas. PRLR mRNA expression was significantly lower in malignant than in benign lesions (p = 0.0165). Immunohistochemistry demonstrated PRLR expression in all three tissue types with signals mostly limited to epithelial cells.ConclusionsMalignant transformation of mammary tissue was associated with a decline in prolactin receptor expression. Further studies are warranted to address the functional significance of this finding.

Transforming Acidic Coiled-Coil-Containing Protein 2 (TACC2) in Human Breast Cancer, Expression Pattern and Clinical/Prognostic Relevance.

Abstract BACKGROUND: TACC2 is a member of the transforming acidic coiled-coil-containing protein family and is associated with the centrosome-spindle apparatus during cell cycling. In vivo, the TACC2 gene is expressed in various splice forms predominantly in postmitotic tissues, including heart, muscle, kidney, and brain. Recent work has shown that members of this family, including TACC2, may be involved in the progression of certain solid tumours. The aim of the current study was to identify the role of TACC2 in breast cancer and to establish if a prognostic relevance exists.MATERIALS AND METHODS: Fresh frozen primary human breast cancer tissues (n = 120) and non-neoplastic mammary tissues (n = 32) were used. The distribution and location of TACC2 was assessed using immunohistochemical staining (IHC) and imaging analysis tools. The transcript levels of TACC2 were determined using quantitative real time-PCR. The results were analyzed against the clinical, pathological and follow-up (10 years) data. Statistical analysis was by Mann-Whitney U test and Kaplan-Meier method. Shown are median transcript level.RESULTS: TACC2 protein staining was seen in both normal epithelial cells and cancer cells in mammary tissues. Increased staining of TACC2 was seen in most of the breast tumours examined when compared with normal breast tissues. Quantitative analysis of the TACC2 transcript also revealed a higher level expression in tumours compared with normal tissues (p=0.027, tumours vs normal). TACC2 expression was significantly increased in higher grade tumours compared to those in lower grade tumours (grade-3 vs grade-1, p=0.046). Using the Nottingham Prognostic Index (NPI), TACC2 transcript was significantly higher in tumours from patients with a moderate prognosis than from those with a good prognosis (p = 0.019). The expression in samples from patients with poor clinical outcome (with metastasis, recurrence and breast cancer related death) was significantly higher than that from patients who remained disease free (median (IQR) 33.8 (3.0-110.2) copies vs 6 (1.6-28.9) copies, p=0.038). This was reflected by the shorter disease-free survival for patients with high TACC2 (107 (91-122.8, 95% CI) months compared with 137 (125-150.6) months for patients with low TACC2 transcripts (p=0.019).CONCLUSION: This study shows that increased expression of TACC2 correlates with poor prognosis in patients with breast cancer. This suggests that TACC2 mediates an oncogenic effect on breast cancer cells. The findings also suggest that TACC2 may be a potential therapeutic target. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3159.

Increased Derlin-1 Expression in Metastases of Canine Mammary Adenocarcinomas

Derlin-1 (Derl-1) is a transporter protein for the export of misfolded proteins from the endoplasmic reticulum (ER) and an inhibitor of ER stress-induced apoptosis. There is greater expression of Derl-1 mRNA in laser microdissected lymph node metastases of mammary adenocarcinomas than in non-neoplastic mammary gland tissue from the same dog. The aim of the present study was to immunohistochemically assess Derl-1 protein expression in neoplastic and non-neoplastic canine mammary tissues. Samples of primary mammary adenocarcinomas were collected from 54 dogs in addition to the nodal metastases of these tumours and intralymphatic neoplastic cells. Non-neoplastic mammary gland tissue was taken from the same animals. Samples of mammary adenomas were collected from a further 44 dogs in addition to non-neoplastic mammary gland from the same animals. There were significant (P < or = 0.05) differences in Derl-1 expression between the different mammary tissues. Weak Derl-1 expression was found in non-neoplastic gland and mammary adenomas, moderate expression in adenocarcinomas, moderate to marked expression in lymph node metastases and marked expression in intralymphatic tumour cells. Neoplastic mammary gland cells therefore appear to have an increased stress-associated unfolded protein response, and this is highest in intralymphatic tumour cells. Weak Derl-1 protein expression was also found in vascular endothelial cells and fibrocytes and occasionally in lymphatic lining cells.

Expression of CD44 in Canine Mammary Tumours

CD44 is an important adhesion molecule for hyaluronan, a major component of the extracellular matrix (ECM). In human breast cancer, the interaction of tumour cells with the ECM via CD44 is favoured as a major candidate for tumour progression and metastasis. The present study was designed to investigate immunohistochemically the expression of the standard form of CD44 in normal, hyperplastic and neoplastic canine mammary tissue. CD44 was expressed in normal and hyperplastic mammary tissue predominantly by ductal and alveolar epithelial cells and to a minor extent by myoepithelial cells. Stromal cells and blood vessels displayed low to moderate CD44 expression. In simple and complex adenomas and benign mixed tumours there was significant up-regulation of CD44 expression in alveolar epithelial cells compared with adjacent non-neoplastic mammary tissue. Peripheral epithelial cells of simple and complex adenomas, benign mixed tumours and complex carcinomas expressed significantly more CD44 compared with adjacent non-neoplastic mammary tissue. Peripheral epithelial cells of simple adenomas revealed a significantly higher CD44 expression compared with simple carcinomas. A statistical trend to greater CD44 expression was found in peripheral epithelial cells of complex adenomas, benign mixed tumours and complex carcinomas compared with simple carcinomas. Up-regulation of CD44 therefore appears to be associated with benign or relatively benign biological behaviour of canine mammary tumours.

COX-2 Expression in Canine Normal and Neoplastic Mammary Gland

COX-2 expression was examined immunohistochemically in samples of normal canine mammary tissue (n=22) and benign (n=36) and malignant (n=45) mammary tumours including metastases (n=12). COX-2 was constitutively expressed in normal mammary tissue with membranous apical labelling of glandular epithelium, suggesting a role for this molecule in normal mammary physiology. By contrast, in neoplastic lesions and in adjacent non-neoplastic mammary tissue COX-2 was expressed in the cytoplasm of epithelial cells, suggesting that internalization of the molecule is associated with oncogenesis. Marked expression of COX-2 was observed in 8.3% of benign neoplasms and in 42.2% of malignant neoplasms, mainly in poorly differentiated areas. The majority of metastatic lesions (58.3%) exhibited strong COX-2 labelling and in almost all cases (83.3%) the labelling intensity was similar or stronger to that of the primary neoplasm. This finding is consistent with the hypothesis that COX-2 metabolites are important promoters of angiogenesis and invasiveness and therefore contribute to metastatic spread.

Novel variations and loss of heterozygosity of BRCA2 identified in a dog with mammary tumors

To establish novel polymorphic markers for analysis of loss of heterozygosity (LOH), so as to study the possible involvement of BRCA2 in mammary tumors obtained from dogs. Blood samples, mammary gland specimens, or mammary tumors from 3 tumor-bearing dogs and 10 tumor-free dogs. Nucleotide sequence analysis was performed with a DNA autosequencer. Loss of heterozygosity analysis was performed for markers established in the present study. The expression level of canine BRCA2 was quantified by real-time PCR analysis. 3 novel microsatellite markers with high heterozygosity rates (> 50%) were established, and the previously reported marker for canine BRCA2 gene locus was improved. These markers were used for the analysis of DNA from formalin-fixed and paraffin-embedded samples. By use of these markers, LOH in canine BRCA2 was identified as a result of recombination. In mammary tumor DNA that corresponded to the LOH-positive dog, the level of canine BRCA2 expression was decreased compared with that of nonneoplastic mammary gland tissue; the open reading frame contained 4 missense variations, 1 insertion variation, and 1 silent variation, some of which were localized to functional domains. 3 novel polymorphic markers were developed for LOH analysis of canine BRCA2 and identified a dog with LOH with some variations in the functional domains. These markers could be useful for assessing the relevance of BRCA2 variation in mammary tumors of dogs.

Expression of the cell to cell adhesion molecule, ALCAM, in breast cancer patients and the potential link with skeletal metastasis

The activated leukocyte cell adhesion molecule (ALCAM) is involved in cell migration and adhesion. Decreased levels of ALCAM expression in breast cancer tissue are known to correlate with poor prognosis. The current study specifically investigated the ALCAM expression in tumours which developed skeletal metastasis. Fresh frozen primary breast cancer tissues (n=234) and non-neoplastic mammary tissue (n=34) were used. The distribution and location of ALCAM was assessed using immunohistochemical methods and the level of ALCAM was determined using quantitative RT-PCR. The results were analysed against the clinical and pathological data. ALCAM staining was largely membranous and cytoplasmic in normal epithelial cells and is significantly stronger than in cancer cells (p=0.023) and patients who develop skeletal metastasis (p=0.048). The ALCAM transcript levels were lowest in patients with skeletal metastasis (p=0.0048) but were also significantly lower in patients who developed local recurrence (p=0.040) and in those who died from breast cancer (p=0.0075). Patients with moderate and poor prognostic indices have a lower level than those with a good index (p=0.05 and p=0.0089 respectively) and ER-positive tumours show a lower level than ER-negative (p=0.043). Ductal carcinomas, 86% of the cohort, have a similar pattern of changes with skeletal metastasis patients having significantly lower levels (p=0.015). This study has, for the first time, shown that patients who develop skeletal metastasis tend to have the lowest levels of ALCAM transcripts in their breast cancers, a finding potentially useful for clinical practice.

Expression of transcription factor CREB1 in human breast cancer and its correlation with prognosis

It has been suggested that the cAMP responsive element-binding protein (CREB) may act as a transcription regulator of aromatase in breast cancer cells. However, there is little knowledge on the expression of CREB1 in human breast cancer and its clinical significance. The current study investigated the expression pattern of CREB1 in human breast cancer at the mRNA and protein level and correlated it with the clinical outcome. CREB1 staining was primarily seen in the nucleus of both normal and tumour cells. At the mRNA level, we found a significantly higher level of CREB1 in breast tumour tissues (n=120) as compared to non-neoplastic mammary tissues (n=33, p=0.0092). When compared between different histological types CREB1 expression was significantly higher in ductal carcinoma as compared to lobular and other breast carcinoma. Patients with a poor prognosis and with metastasis had a markedly raised level of CREB1 compared to patients who were disease free. In addition, node-positive tumours had higher levels of CREB1 than node-negative tumours (p=0.0018). Finally, patients with high levels of CREB1 had a significantly shorter disease-free survival [95.3 (68.4-122.3, 95% CI) months] compared with those with lower levels [133.9 (123.5-144.2) months, p=0.0193]. This study demonstrates that the level of CREB1 in breast cancer patients is elevated and is significantly raised in patients with a poor prognosis, metastatic disease and nodal involvement. We conclude that the level of CREB1 expression is aberrant in human breast cancer and is associated with disease progression in breast cancer patients.