The gene expression profiles of canine mammary cancer cells grown with carcinoma-associated fibroblasts (CAFs) as a co-culture in vitro

Biological features of canine cancer-associated fibroblasts and their influence on cancer cell invasion

Cancer-associated fibroblasts (CAFs) play an essential role in tumor invasion and metastasis. In dogs, the biological features of CAFs have not been well characterized. The purpose of this study was to investigate differences in the biological activities of canine CAFs and normal fibroblasts (NFs), and their influence on the migration and invasion of cancer cells. Canine CAFs and NFs were harvested from surgically-resected malignant epithelial tumor tissues and skin tissues of dogs. A wound-healing assay was conducted to compare the migratory and invasive abilities of canine CAFs and NFs. The results of this study showed that canine CAFs have a greater migratory and invasive ability than NFs. To observe the indirect and direct interactions between fibroblasts and cancer cells, Boyden chamber assay and 3D co-culture with collagen gel were conducted. The number of migrated and infiltrated cancer cells co-cultured with canine CAFs was greater than that with NFs. In the 3D co-culture, cancer cells showed noteworthy proliferation on the surface of gels containing canine CAFs and invasion into the gel. On the other hand, no infiltration of cancer cells into the gel containing NFs was observed. It was suggested that canine CAFs activate migration and invasion of cancer cells and promote the infiltration of cancer cells into collagen gels.

The Dog as a Model to Study the Tumor Microenvironment

Cancer is a complex and dynamic disease with an outcome that depends on a strict crosstalk between tumor cells and other components in tumor microenvironment, namely, tumor-infiltrating immune cells, fibroblasts, cancer stem cells, adipocytes, and endothelial cells. Within the tumor microenvironment, macrophages and T-lymphocytes appear to be key effectors during the several steps of tumor initiation and progression. Tumor cells, through the release of a plethora of signaling molecules, can induce immune tolerance, by avoiding immune surveillance, and inhibit immune cells cytotoxic functions. Furthermore, as the tumor grows, tumor microenvironment reveals a series of dysfunctional conditions that potentiate a polarization of harmful humoral Th2 and Th17, an upregulation of Treg cells, and a differentiation of macrophages into the M2 subtype, which contribute to the activation of several signaling pathways involving important tissue biomarkers (COX-2, EGFR, VEGF) implicated in cancer aggressiveness and poor clinical outcomes. In order to maintain the tumor growth, cancer cells acquire several adaptations such as neovascularization and metabolic reprogramming. An extensive intracellular production of lactate and protons is observed in tumor cells as a result of their high glycolytic metabolism. This contributes not only for the microenvironment pH alteration but also to shape the immune response that ultimately impairs immune cells capabilities and effector functions.In this chapter, the complexity of tumor microenvironment, with special focus on macrophages, T-lymphocytes, and the impact of lactate efflux, was reviewed, always trying to demonstrate the strong similarities between data from studies of humans and dogs, a widely proposed model for comparative oncology studies.

Interleukin-33-Enhanced CXCR4 Signaling Circuit Mediated by Carcinoma-Associated Fibroblasts Promotes Invasiveness of Head and Neck Cancer

Despite recent advances, treatment for head and neck squamous cell carcinoma (HNSCC) has limited efficacy in preventing tumor progression. We confirmed previously that carcinoma-associated fibroblasts (CAF)-induced interleukin-33 (IL-33) contributed to cancer progression. However, the molecular mechanisms underlying the complex communication network of the tumor microenvironment merited further evaluation. To simulate the IL-33-induced autocrine signaling, stable clones of IL-33-overexpressing HNSCC cells were established. Besides well-established IL-33/ST2 and SDF1/CXCR4 (stromal-derived factor 1/C-X-C motif chemokine receptor 4) signaling, the CAF-induced IL-33 upregulated CXCR4 via cancer cell induction of IL-33 self-production. The IL-33-enhanced-CXCR4 regulatory circuit involves SDF1/CXCR4 signaling activation and modulates tumor behavior. An in vivo study confirmed the functional role of IL-33/CXCR4 in tumor initiation and metastasis. The CXCR4 and/or IL-33 blockade reduced HNSCC cell aggressiveness, with attenuated invasions and metastases. Immunohistochemistry confirmed that IL-33 and CXCR4 expression correlated significantly with disease-free survival and IL-33-CXCR4 co-expression predicted a poor outcome. Besides paracrine signaling, the CAF-induced IL-33 reciprocally enhanced the autocrine cancer-cell self-production of IL-33 and the corresponding CXCR4 upregulation, leading to the activation of SDF1/CXCR4 signaling subsequent to cancer progression. Thus, targeting the IL-33-enhanced-CXCR4 regulatory circuit attenuates tumor aggressiveness and provides a potential therapeutic option for improving the prognosis in HNSCC patients.

Expression of Periostin in Cancer-associated Fibroblasts in Mammary Cancer in Female Dogs

BACKGROUND/AIM

Mammary neoplasms, like breast neoplasms in women, are one of the most common tumours in female dogs. Cancer-associated fibroblasts (CAFs) found in the tumour stroma play a role in angiogenesis and increase cell migration, contributing to tumour growth and progression, as well as metastasis. The aim of our work was to determine the level of periostin (POSTN) expression in CAFs in mammary tumours of female dogs.

MATERIALS AND METHODS

The research material consisted of 77 carcinomas and 24 adenomas of the mammary ridge in female dogs. Immunohistochemistry tests were performed using antibodies directed against the antigens POSTN, Ki-67, ERB-B2 receptor tyrosine kinase 2 (HER2), vimentin, and alpha smooth muscle actin (αSMA). Expression of POSTN at the mRNA level was determined using real-time polymerase chain reaction methods in 20 cases of mammary neoplasms.

RESULTS

Expression of POSTN in CAFs was observed in 92% of mammary cancer samples and in 25% of mammary adenoma samples in female dogs. A statistically significant increase in POSNT expression in CAFs was found in the carcinomas compared with mammary adenomas in female dogs. Expression of POSTN in CAFs in mammary carcinomas in female dogs positively correlated with the histological malignancy grade of tumours and the expression of Ki-67 proliferative antigen.

CONCLUSION

Our results suggest a role of POSTN on the pathogenesis of mammary tumours in female dogs. Moreover, POSTN may prove to be a useful marker in the evaluation of cancerous stroma of mammary tumours in female dogs, and may have prognostic significance.

Expression of Podoplanin in Mammary Cancers in Female Dogs

BACKGROUND/AIM

Mammary neoplasms are very common tumours in female dogs. Cancer-associated fibroblasts (CAFs) play an important role in the oncogenesis process. One of the useful proteins used in the diagnostics of CAFs cells is podoplanin (PDPN). The aim of our study was to assess the expression of PDPN in mammary cancer in female dogs.

MATERIALS AND METHODS

Our study cohort included 61 cancers and 21 adenomas of the mammary tumour in bitches. Expression of podoplanin, Ki-67 and HER2 was determined using the Immunohistochemical (IHC) method. PDPN expression at the mRNA level was determined using real-time PCR.

RESULTS

Expression of PDPN in CAFs was observed in 22.9% of cases of mammary cancers in bitches, with no PDPN expression in adenomas. A positive correlation was found between the expression of PDPN in CAFs and the grade of histological malignancy and expression of Ki-67.

CONCLUSION

PDPN plays a significant role during the process of carcinogenesis of mammary tumours in female dogs.

Comparative Approach to the Temporo-Spatial Organization of the Tumor Microenvironment

The complex ecosystem in which tumor cells reside and interact, termed the tumor microenvironment (TME), encompasses all cells and components associated with a neoplasm that are not transformed cells. Interactions between tumor cells and the TME are complex and fluid, with each facet coercing the other, largely, into promoting tumor progression. While the TME in humans is relatively well-described, a compilation and comparison of the TME in our canine counterparts has not yet been described. As is the case in humans, dog tumors exhibit greater heterogeneity than what is appreciated in laboratory animal models, although the current level of knowledge on similarities and differences in the TME between dogs and humans, and the practical implications of that information, require further investigation. This review summarizes some of the complexities of the human and mouse TME and interjects with what is known in the dog, relaying the information in the context of the temporo-spatial organization of the TME. To the authors' knowledge, the development of the TME over space and time has not been widely discussed, and a comprehensive review of the canine TME has not been done. The specific topics covered in this review include cellular invasion and interactions within the TME, metabolic derangements in the TME and vascular invasion, and the involvement of the TME in tumor spread and metastasis.

Identification of a small-molecule ligand of β-arrestin1 as an inhibitor of stromal fibroblast cell migration accelerated by cancer cells

Stromal fibroblasts, which occupy a major portion of the tumor microenvironment, play an important role in cancer metastasis. Thus, targeting of these fibroblasts activated by cancer cells (carcinoma‐associated fibroblasts; CAFs) might aid in the improved treatment of cancer metastasis. NIH3T3 fibroblasts cocultured with MCF7 cells displayed enhanced migration compared to NIH3T3 fibroblasts cultured alone. We used this system to identify the small‐molecule inhibitors responsible for their enhanced migration, a characteristic of CAFs. We selected β‐arrestin1, which showed high expression in cocultured cells, as a molecular target for such inhibitors. Cofilin, a protein downstream of β‐arrestin1, is activated/dephosphorylated in this condition. The small‐molecule ligands of β‐arrestin1 obtained by chemical array were then examined using a wound healing coculture assay. RKN5755 was identified as a selective inhibitor of activated fibroblasts. RKN5755 inhibited the enhanced migration of fibroblasts cocultured with cancer cells by binding to β‐arrestin1 and interfering with β‐arrestin1‐mediated cofilin signaling pathways. Therefore, these results demonstrate the role of β‐arrestin1 in the activation of fibroblasts and inhibiting this protein by small molecule inhibitor might be a potential therapeutic target for the stromal fibroblast activation (cancer–stroma interaction).

Application of post-genomic techniques in dog cancer research

Omics techniques have been widely applied to veterinary science, although mostly on farm animal productions and infectious diseases. In canine oncology, on the contrary, the use of omics methodologies is still far behind. This review presents the most recent achievement in the application of postgenomic techniques, such as transcriptomics, proteomics, and metabolomics, to canine cancer research. The protocols to recover material suitable for omics analyses from formalin-fixed, paraffin-embedded tissues are presented, and omics applications for biomarker discovery and their potential for cancer diagnostics in veterinary medicine are highlighted.

Antiproliferative effect of berberine on canine mammary gland cancer cell culture

Canine mammary gland tumors are the most frequent cause of cancer in female dogs. Numerous studies using cancer cell lines and clinical trials have indicated that various natural products and antioxidants reduce or possibly prevent the development of cancer. Berberine (BBR), the most important alkaloid in the Berberidaceae, which exerts a wide range of pharmacological and biochemical effects, has drawn much attention due to its particularly high antitumor activity in vitro and in animal studies. The aim of the present study was to investigate the antiproliferative effect of BBR against a canine mammary gland carcinoma cell line (CF41.Mg) in vitro. CF41.Mg cells were cultured in RPMI-1640 medium containing 10% heat inactived fetal bovine serum (FBS) and 100 mg/ml peniciline-streptomycin. Subsequently the cells were treated with different concentrations of BBR chloride (10, 25, 50, 100 and 200 µM) at a density of 12,000 cells/well in 96-well plates. Following treatment, the MTT assay was used to detect cell viability after 24-, 48- and 72-h incubations at 37°C with 5% CO₂. The results indicated that BBR inhibited proliferation of canine mammary gland carcinoma cells, as treatment with 100 µM BBR for 24 h resulted in a significant decrease in cell viability (P<0.005). As the present study demonstrated that BBR (10-200 µM) induced cancer cell death, it is proposed that BBR may serve as a candidate agent against canine mammary tumor cells via its antiproliferative activity.

Screening and analysis of breast cancer genes regulated by the human mammary microenvironment in a humanized mouse model

Tumor microenvironments play critical regulatory roles in tumor growth. Although mouse cancer models have contributed to the understanding of human tumor biology, the effectiveness of mouse cancer models is limited by the inability of the models to accurately present humanized tumor microenvironments. Previously, a humanized breast cancer model in severe combined immunodeficiency mice was established, in which human breast cancer tissue was implanted subcutaneously, followed by injection of human breast cancer cells. It was demonstrated that breast cancer cells showed improved growth in the human mammary microenvironment compared with a conventional subcutaneous mouse model. In the present study, the novel mouse model and microarray technology was used to analyze changes in the expression of genes in breast cancer cells that are regulated by the human mammary microenvironment. Humanized breast and conventional subcutaneous mouse models were established, and orthotopic tumor cells were obtained from orthotopic tumor masses by primary culture. An expression microarray using Illumina HumanHT-12 v4 Expression BeadChip and database analyses were performed to investigate changes in gene expression between tumors from each microenvironment. A total of 94 genes were differentially expressed between the primary cells cultured from the humanized and conventional mouse models. Significant upregulation of genes that promote cell proliferation and metastasis or inhibit apoptosis, such as SH3-domain binding protein 5 (BTK-associated), sodium/chloride cotransporter 3 and periostin, osteoblast specific factor, and genes that promote angiogenesis, such as KIAA1618, was also noted. Other genes that restrain cell proliferation and accelerate cell apoptosis, including tripartite motif containing TRIM36 and NES1, were downregulated. The present results revealed differences in various aspects of tumor growth and metabolism between the two model groups and indicated the functional changes specific to the human mammary microenvironment.

Stiffened Extracellular Matrix and Signaling from Stromal Fibroblasts via Osteoprotegerin Regulate Tumor Cell Invasion in a 3-D Tumor in Situ Model

Several changes have been described in the stroma surrounding a tumor, including changes in cellular composition, altered extracellular matrix composition and organization, and increases in stiffness. Tumor cells are influenced by the composition, organization, and mechanical properties of the microenvironment, and by signals from stromal cells. Here we sought to test whether signaling from stromal fibroblasts and/or the small change in stiffness observed in vivo surrounding epithelial tumors regulates tumor cell invasion from a model of a tumor in situ. We generated a novel tumor in situ model system in which a tumor spheroid is encased within a collagen-IV containing membrane and further encased within a collagen-I matrix of in vivo stiffness with or without fibroblasts. Effects of the matrix, fibroblasts or fibroblast signals were determined by observing the invasion of tumor cells into the matrix. Effects of reciprocal tumor cell signaling upon fibroblasts were determined by observing markers of fibroblast activation. We found that a stiffened matrix led to increased dissemination of MDA-MB-231 cells from tumor spheroids when no fibroblasts were present and that MCF10A cells maintained a more normal organization with a stiffened matrix. The presence of fibroblasts, or fibroblast conditioned media, attenuated the effect upon MDA-MB-231 cells. We also observed an attenuation of fibroblast activation associated gene expression in the presence of MDA-MB-231 cells, with a paradoxical increase in activation associated contractile activity. Furthermore, we identified osteoprotegerin as a soluble factor released by fibroblasts in the stiffened environment that is key to the inhibition of cell invasion.

Cancer as a changed tissue's way of life (when to treat, when to watch and when to think)

The profound scientific and commercial success of molecular biology, the progress of 'cancer gene' investigation technologies, together, pushed forward the postulate that genes explain 'everything'. Yet, during the last few years the microenvironments of solid tumors have emerged as key modulators of initiation, progression and metastasis and as essential to the therapeutic response. In the present review, we provide a synthetic examination of the main traits of cells embedded into the cancer stroma and emphasize several evidences that all components of the tumor tissue cooperate in space and time. Then we turn to discuss the epitheliocentric somatic mutational view and other new paradigms assuming that disturbed tissue interactions among cell populations are critical to cancer causation, growth and spread.

Expression of vimentin filaments in canine malignant mammary gland tumors: A simulation of clinicopathological features of human breast cancer

Canine malignant mammary gland tumors (CMMGTs) are the most common malignancies observed in females. Several biological similarities have been reported between CMMGTs and human breast cancer (HBC). The present study aimed to assess the correlation of vimentin filaments overexpression, as part of the process of epithelial-mesenchymal transition (EMT) and the clinicopathological characteristics in CMMGTs. The clinicopathological characteristics of 42 CMMGTs were collected. Paraffin-embedded blocks underwent immunohistochemistry staining, which was performed using vimentin (to assess the evolution of the EMT process), Ki-67 (for evaluation of tumor proliferation) and cluster of differentiation 34 (CD34) (for evaluation of angiogenesis) antibodies. The tumor stage, grade, vascular invasion, margin status, rate of expression of the vimentin filaments, microvessel density-CD34 and proliferation rate data were obtained. Finally, the association between the expression of the vimentin filaments and those parameters was resolved statistically. A significant association was shown between the overexpression of the vimentin filaments and tumor size (r=0.71, P=0.03), tumor grade (r=0.80, P=0.021), angiogenesis (r=0.57, P=0.043), proliferation coefficient (r=0.06, P=0.001) and vascular invasion (r=0.76, P=0.043). Vimentin overexpression did not statistically correlate with the tumor stage or the margin status. Similar to the findings of the present study, certain recent studies have indicated that vimentin filament expression in HBC and CMMGTs is associated with the severity of cancer. Thus, spontaneous canine mammary tumor models appear to be an appropriate animal model for breast cancer research, and the results of the present study could aid to reinforce the association.

The paracrine effect of cancer-associated fibroblast-induced interleukin-33 regulates the invasiveness of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the leading causes of cancer-related death worldwide. The prognosis of HNSCC is usually poor because of its propensity for extensive invasion, local recurrence and frequent regional lymph node metastasis, even at initial diagnosis. Carcinoma-associated fibroblasts (CAFs), a major type of tumour-surrounding stromal cell, generate mediators through which they interact with tumours and contribute to cancer progression. The orchestration between CAFs and cancer cells is complex. Despite recent studies demonstrating the paracrine effect of stromal cells in the tumour microenvironment on initiation and progression of cancer cells, the major mediator related to CAFs and its underlying mechanism remain unknown. In the present study, we used organotypic culture to investigate CAFs that promote aggressive behaviour of HNSCC cells. Using microarray analysis, we detected abundant expression of interleukin-33 (IL-33) in CAFs and identified IL-33 as a critical mediator in CAF-induced invasiveness. Counteracting IL-33 activity diminished the aggressive phenotype of cancer cells induced by CAFs. Administration of IL-33 promoted cancer cell migration and invasion through induction of epithelial-to-mesenchymal transdifferentiation and increased IL-33 gene expression in cancer cells. In 40 patients with HNSCC, IL-33 expression in CAFs correlated with IL-33 expression in cancer cells. Most cases with a low invasion pattern grading score (IPGS) showed low or no expression of IL-33, whereas most HNSCC cases with high IPGS displayed over-expression of IL-33 in CAFs and cancer cells. High IL-33 expression associated with poor prognosis in terms of nodal metastasis-free survival. These results indicate that CAFs promote cancer invasiveness via paracrine and autocrine effects on microenvironmental IL-33 signalling, and suggest that IL-33 is a potential prognostic biomarker that could be considered in therapeutic strategies for the treatment of patients with HNSCC.

Gene expression profiles in canine mammary carcinomas of various grades of malignancy

Background

The frequency of mammary malignancies in canine patients is even three times over than in human. In various types of cancer different intracellular signalling pathways are perturbed, thus the patients with pathologically the same type of cancer often have dissimilar genetic defects in their tumours and respond in a heterogeneous manner to anticancer treatment. That is why the objective of the hereby study was to assess the gene expression profiles in canine mammary carcinomas (in unsupervised manner) classified by pathologists as grade 1 (well differentiated), grade 2 (moderately differentiated) and grade 3 (poorly differentiated) and compare their molecular and pathological classifications.

Results

Our unsupervised analysis classified the examined tissues into three groups. The first one significantly differed from the others and consisted of four carcinomas of grade 3 and one carcinoma of grade 2. The second group consisted of four grade 1 carcinomas. The very heterogeneous (based on their pathological parameters) group was the last one which consisted of two grade 1 carcinomas, two grade 3 carcinomas and five grade 2 carcinomas. Hierarchical dendrogram showed that the most malignant tumour group had significantly distinct gene expression.

Conclusions

Molecular classification of canine mammary tumours is not identical with pathological classification. In our opinion molecular and pathological characterization of canine mammary malignancy can complement one another. However, furthers studies in this field are required.

A role of ghrelin in canine mammary carcinoma cells proliferation, apoptosis and migration

Background

Ghrelin is a natural ligand of the growth hormone secretagogue receptor (GHS-R). They are often co-expressed in multiple human tumors and related cancer cell lines what can indicate that the ghrelin/GHS-R axis may have an important role in tumor growth and progression. However, a role of ghrelin in canine tumors remains unknown. Thus, the aim of our study was two-fold: (1) to assess expression of ghrelin and its receptor in canine mammary cancer and (2) to examine the effect of ghrelin on carcinoma cells proliferation, apoptosis, migration and invasion. The expression of ghrelin and its receptor in canine mammary cancer tissues and cell lines (isolated from primary tumors and their metastases) was examined using Real-time qPCR and immunohistochemistry. For apoptosis analysis the Annexin V and propidium iodide dual staining was applied whereas cell proliferation was evaluated by MTT assay and BrdU incorporation test. The influence of ghrelin on cancer cells migration and invasion was assessed using Boyden chamber assays and wound healing assay.

Results

The highest expression of ghrelin was observed in metastatic cancers whereas the lowest expression of ghrelin receptor was detected in tumors of the 3^rd grade of malignancy. Higher expression of ghrelin and its receptor was detected in cancer cell lines isolated from metastases than in cell lines isolated from primary tumors. In vitro experiments demonstrated that exposure to low doses of ghrelin stimulates cellular proliferation, inhibits apoptosis and promotes motility and invasion of canine mammary cancer cells. Growth hormone secretagogue receptor inhibitor ([D-Lys³]-GHRP6) as well as RNA interference enhances early apoptosis.

Conclusion

The presence of ghrelin and GHS-R in all of the examined canine mammary tumors may indicate their biological role in cancer growth and development. Our experiments conducted in vitro confirmed that ghrelin promotes cancer development and metastasis.