ZEB2 and ZEB1 expression in a spontaneous canine model of invasive micropapillary carcinoma of the mammary gland

Characterization of neoplastic cells outlining the cystic space of invasive micropapillary carcinoma of the canine mammary gland

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare malignant breast tumor and a variant form of invasive ductal carcinoma that is an aggressive neoplasm of the human breast and canine mammary gland. The importance of the tumor microenvironment in cancer development has gradually been recognized, but little is known about the cell types outlining the cystic space of canine IMPC. This study aimed to characterize the neoplastic cells outlining the cystic space of IMPC.

RESULTS

Immunohistochemistry (IHC), immunofluorescence (IF), superresolution and transmission electron microscopy (TEM) were used to assess the cell types in the cystic areas of IMPCs. Cells expressing the mesenchymal markers alpha-smooth muscle actin (αSMA), Vimentin, and S100A4 outlined the cystic space of IMPC. Furthermore, loss of epithelial cell polarity in IMPC was shown by the localization of MUC1 at the stroma-facing surface. This protein modulates lumen formation and inhibits the cell-stroma interaction. Immunohistochemical and IF staining for the myoepithelial cell marker p63 were negative in IMPC samples. Furthermore, associated with peculiar morphology, such as thin cytoplasmic extensions outlining cystic spaces, was observed under TEM. These observations suggested cells with characteristics of myoepithelial-like cells.

CONCLUSIONS

The cells outlining the cystic space of IMPC in the canine mammary gland were characterized using IHC, IF and TEM. The presence of cells expressing αSMA, Vimentin, and S100A4 in the IMPC stroma suggested a role for tumor-associated fibroblasts in the IMPC microenvironment. The reversal of cell polarity revealed by the limited basal localization of MUC1 may be an important factor contributing to the invasiveness of IMPC. For the first time, the cystic space of canine mammary gland IMPC was shown to be delimited by myoepithelial-like cells that had lost p63 expression. These findings may enhance our understanding of the cellular microenvironment of invasive tumors to improve cancer diagnosis and treatment.

ZEB and Snail expression indicates epithelial-mesenchymal transition in canine melanoma

Melanoma progression is associated with the epithelial-mesenchymal transition (EMT) when tumor cells reduce E-cadherin and increase N-cadherin expression resulting in an escape from the microenvironment via loss of cellular adhesion and gain of motility. Transcription factor proteins Snail and ZEB trigger EMT by repression of epithelial markers and activation of mesenchymal properties. This study evaluated E-cadherin, N-cadherin, Snail, ZEB1 and ZEB2 expression by IHC and investigated their relationship with morphological characteristics in cutaneous and oral canine melanoma. Results from melanoma cases demonstrated E-cadherin expression in 45% (9/20) of oral and 58% (22/38) of cutaneous tumors, while N-cadherin expression was observed in 95% (18/19) of oral and 92% (34/37) of cutaneous melanoma. Cytoplasmic and nuclear N-cadherin expression was positively correlated with ZEB1 expression, while the cell membrane N-cadherin expression was positively correlated with ZEB2. In addition, an increase in nuclear N-cadherin expression was associated with reduced Snail expression in cutaneous melanoma and an increase in Snail expression in oral melanoma, indicating that the correlation between N-cadherin and Snail expression is coincident with tumor location. Our data suggest that ZEB family protein is associated with N-cadherin translocation from cell membrane to the cytoplasm and nuclei, and may act as important transcription factors of EMT regulation in canine melanoma.

The investigation of transcriptional repression mediated by ZEB2 in canine invasive micropapillary carcinoma in mammary gland

The E-cadherin loss has frequently been associated with transcriptional repression mediated by transcription factors, such as the Zinc Finger E-Box Binding Homeobox-2 (ZEB2). Invasive micropapillary carcinomas (IMPCs) of the breast are aggressive neoplasms frequently related to lymph node metastasis and poor overall survival. In the canine mammary gland, IMPCs has just been reported and, based on its behavioral similarity with the human IMPCs, appears to be a good spontaneous model to this human entity. This study aimed to evaluate the relationship between E-cadherin and ZEB2 in a spontaneous canine model of invasive micropapillary carcinoma of the mammary gland. The correlation among gene expression (ZEB2 and CDH1) and clinicopathological findings was also explored. Nineteen cases of IMPC of the canine mammary gland were obtained, protein and mRNA expression were investigated through immunohistochemistry and RNA In Situ Hybridization, respectively. To better understand the relationship between E-cadherin and ZEB2, immunofluorescence was performed in canine IMPCs. Immunohistochemically, most of IMPCs showed 1+ (14/19, 73.7%) for E-cadherin; and positivity for ZEB2 was diagnosed in 47.4% of the IMPCs. Regarding the RNA In Situ Hybridization (ISH), most of IMPCs showed 4+ and 0+ for E-cadherin (CDH1) and ZEB2 respectively. Through immunofluorescence, the first and second more frequent combinatorial group were E-cadherin⁺ZEB2^- and E-cadherin⁺ZEB2⁺; neoplastic cells showing concomitantly weak expression for E-cadherin and positivity for ZEB2 were frequently observed. A negative correlation was observed between E-cadherin and progesterone receptor expression in IMPCs. Based on these results, canine mammary IMPCs show E-cadherin lost and, at times reveals nuclear positivity for the transcription factor ZEB2 that seems to exert transcriptional repression of the CDH1.

Prognostic significance of the epithelial-mesenchymal transition factor zinc finger E-box-binding homeobox 2 in esophageal squamous cell carcinoma

Zinc finger E-box-binding homeobox 2 (ZEB2) has been reported to mediate epithelial-mesenchymal transition (EMT) and disease progression in several cancer types. However, the expression of ZEB2 in esophageal squamous cell carcinoma (OSCC) and its association with prognosis remains unclear. In the present study, a tissue microarray and immunohistochemistry were used to investigate ZEB2 and epithelial (E-)cadherin expression in OSCC tissues (n=218) and peritumoral esophageal tissues (POT; n=60). There was a significantly increased incidence of positive ZEB2 expression in OSCC tissues compared with the expression in POTs (P<0.012). By contrast, the incidence of positive E-cadherin expression in OSCC tissues was significantly decreased compared with the expression in POTs (P<0.004). ZEB2 expression in OSCC was associated with a number of clinicopathological factors, and it was also an independent predictive factor for shorter overall survival time (P<0.001). Overall, ZEB2 may promote OSCC metastasis and is a potential prognostic marker for malignancy.

Axon guidance molecule semaphorin3A is a novel tumor suppressor in head and neck squamous cell carcinoma

Semaphorin3A (SEMA3A), an axon guidance molecule in the nervous system, plays an inhibitory role in oncogenesis. Here, we investigated the expression pattern and biological roles of SEMA3A in head and neck squamous cell carcinoma (HNSCC) by gain-of-function assays using adenovirus transfection and recombinant human SEMA3A protein. In addition, we explored the therapeutic efficacy of SEMA3A against HNSCC in vivo. We found that lower expression of SEMA3A correlated with shorter overall survival and had independent prognostic importance in patients with HNSCC. Both genetic and recombinant SEMA3A protein inhibited cell proliferation and colony formation and induced apoptosis, accompanied by decreased cyclin E, cyclin D, CDK2, CDK4 and CDK6 and increased P21, P27, activated caspase-5 and caspase-7. Moreover, over-expression of SEMA3A suppressed migration, invasion and epithelial-to-mesenchymal transition due in part to the inhibition of NF-κB and SNAI2 in HNSCC cell lines. Furthermore, intratumoral SEMA3A delivery significantly stagnated tumor growth in a xenograft model. Taken together, our results indicate that SEMA3A serves as a tumor suppressor during HNSCC tumorigenesis and a new target for the treatment of HNSCC.

Lymphocyte Subsets in the Adrenal Glands of Dogs With Primary Hypoadrenocorticism

Primary hypoadrenocorticism, or Addison's disease, is an autoimmune condition common in certain dog breeds that leads to the destruction of the adrenal cortex and a clinical syndrome involving anorexia, gastrointestinal upset, and electrolyte imbalances. Previous studies have demonstrated that this destruction is strongly associated with lymphocytic-plasmacytic inflammation and that the lymphocytes are primarily T cells. In this study, we used both immunohistochemistry and in situ hybridization to characterize the T-cell subtypes involved. We collected postmortem specimens of 5 dogs with primary hypoadrenocorticism and 2 control dogs and, using the aforementioned techniques, showed that the lymphocytes are primarily CD4+ rather than CD8+. These findings have important implications for improving our understanding of the pathogenesis and in searching for the underlying causative genetic polymorphisms.

Biomarkers for EMT and MET in breast cancer: An update

Metastasis and recurrence are the leading cause of mortality due to breast cancer, but the underlying mechanisms are still poorly understood. Understanding the breast cancer metastasis mechanism is important for early diagnosis and treatment of breast cancer. The seeding and growth of breast cancer cells at sites distinct from the primary tumor is a complex and multistage process. Recently, it has been reported that the epithelial-mesenchymal transition (EMT) and the mesenchymal-epithelial transition (MET) are the main mechanisms for breast cancer metastasis. During EMT, carcinoma cells shed their differentiated epithelial characteristics, including cell-cell adhesion, polarity and lack of motility, and acquire mesenchymal traits, including motility and invasiveness. This review has summarized the studies of known EMT biomarkers in the context of breast cancer progression. These biomarkers include EMT-related genes, proteins, microRNAs and kinases. In general, the findings of these studies suggest that EMT markers are associated with the invasion and metastasis of breast cancer. Further studies on the link between EMT markers and breast cancer will contribute to identify biomarkers for predicting early breast cancer metastasis as well as to provide new ideas for the treatment of breast cancer.

Inner nuclear membrane localization of epidermal growth factor receptor (EGFR) in spontaneous canine model of invasive micropapillary carcinoma of the mammary gland

The epidermal growth factor receptor (EGFR) has been described in the nucleus of primary tumors. Accumulation of EGFR at the nucleus is linked to DNA synthesis and cell proliferation, but the pathological significance of nuclear EGFR is not completely understood. The aim of this study was to investigate the nuclear localization of EGFR in invasive micropapillary carcinoma (IMPC) that is an aggressive neoplasm of canine mammary gland. Confocal immunofluorescence of formalin and paraffin-embedded tissue was used to access the subcellular localization of EGFR. Our results demonstrated that EGFR co-localizes with the inner nuclear envelope marker, Lamin B1 in IMPC. Furthermore, EGFR was not localized within the nucleus or at the inner nuclear envelope membrane in mammary carcinoma in mixed tumor (CMT) that is associated with a better prognosis than other malignant histological types. This finding could be useful as a predictive biomarker of therapeutic response for IMPC.

Epithelial-mesenchymal interconversions and the regulatory function of the ZEB family during the development and progression of ovarian cancer

This study assessed the role of epithelial-mesenchymal interconversions and the regulatory functions of the ZEB family during the development and progression of ovarian cancer. E-cadherin, vimentin, ZEB1 and ZEB2 were analyzed using immunohistochemistry in a series of ovarian tissues that included normal tissue, benign tumors, borderline tumors, malignant tumors and metastatic lesions. The correlation between E-cadherin and ZEB was analyzed. We also analyzed the association between the expression of the four factors and clinicopathological features in ovarian cancer. The results revealed that E-cadherin was weakly positive in normal ovarian epithelium. Cytoplasmic E-cadherin was significantly increased in benign tumors (P<0.01) and further increased in borderline tumors and ovarian cancers. However, cytoplasmic E-cadherin was markedly reduced in metastatic lesions (P<0.01). Membranous E-cadherin was increased in benign tumors, but decreased progressively in borderline, malignant and metastatic tumor tissues (P<0.05). The expression profile of vimentin was opposite to that of membranous E-cadherin. Membranous E-cadherin was negatively correlated with ZEB2 expression (r=-0.514). Additionally, cytoplasmic E-cadherin, ZEB1 and ZEB2 were associated with the FIGO stage of ovarian cancer. ZEB1 was also correlated with ascitic fluid volume. Our results suggest that epithelial-mesenchymal interconversions are dynamically regulated during the development and progression of ovarian tumors. ZEB2, but not ZEB1, may regulate the expression of membranous E-cadherin during these processes.

The Relationship Between E-Cadherin and its Transcriptional Repressors in Spontaneously Arising Canine Invasive Micropapillary Mammary Carcinoma

E-cadherin downregulation is related to metastatic behaviour and a poor prognosis in cancer. It might be induced by transcriptional repression mediated by the transcription factors SNAIL, ZEB1, ZEB2 and TWIST. Here, we investigated E-cadherin expression and its relationship to those transcriptional repressors (i.e. SNAIL, ZEB1, ZEB2 and TWIST) in the progression from carcinoma 'in situ' to invasion to lymph node metastasis in spontaneously arising canine invasive micropapillary carcinoma (IMPC). E-cadherin expression decreased from carcinoma in situ to invasive progression and was likely to increase with lymph node metastasis. Expression of SNAIL decreased from carcinoma in situ to invasive areas and from invasive areas to lymph nodes. Metastatic lymph nodes had higher expression of ZEB1 than carcinoma in situ and invasive areas. ZEB2 expression was observed in 52%, 38% and 33% of carcinoma in situ areas, invasive areas and lymph node metastases, respectively. TWIST expression was observed in 52%, 38% and 33% of carcinoma in situ areas, invasive areas and lymph node metastases, respectively. In invasive areas, E-cadherin downregulation correlated significantly with SNAIL and TWIST upregulation. Additionally, in infiltrating components of IMPCs, E-cadherin(-)SNAIL(+) neoplastic epithelial cells were observed by immunofluorescence. Taken together, canine mammary IMPCs had a loss of E-cadherin from carcinoma in situ to invasive areas, which appears to be induced by the transcription factor SNAIL. In lymph node metastasis, ZEB1 appears to not exert E-cadherin transcriptional repression activity.