The level of RCAS1 expression is inversely correlated with the number of vimentin-positive stromal cells in epithelial ovarian cancer

Molecular biology of gynecological cancer

Cancer is a pathological condition in which the balance between cell growth and death is disordered. Various molecules have been reported to be involved in the oncogenic process of invasion, metastasis and resistance to treatment. An exponential growth in the collection of genomic and proteomic data in the past 20 years has provided major advances in understanding the molecular mechanisms of human cancer, which has been applied to diagnostic and treatment strategies. Targeted therapies have been developed and adopted, particularly for advanced, refractory or recurrent cancers, depending on individual molecular profiles. The aim of the present review is to provide a report of the current literature regarding the molecular biology of gynecological cancers.

Analysis of the intensity of immune cell infiltration and immunoreactivity of RCAS1 in diffuse large B-cell lymphoma of the palatine tonsil and its microenvironment

Non-Hodgkin lymphoma of Waldeyer's ring constitutes a small percentage of cases of palatine tonsil malignancies and its precise etiology remains unknown. RCAS1 (receptor cancer-binding antigen expressed on SiSo cells) has been demonstrated to be associated with poor prognosis, the development of lymph node metastases and participation in tumor microenvironment remodeling. Our aim is to analyze the potential role of RCAS1 expression in the tumor and tumor microenvironment in the development of early-stage palatine tonsil B-cell lymphomas. We selected 20 patients and analyzed tissue samples from the lymphoma and tumor microenvironment of each patient and from a reference group of 20 patients with chronic tonsillitis. The presence of RCAS1 protein immunoreactivity was demonstrated in 65% of the examined tissue samples of diffuse large B-cell lymphoma and in 25% of the analyzed stromata in which it was exhibited by CD68-positive cells identified as macrophages and dispersed throughout the stroma. RCAS1 immunoreactivity in the lymphoma tissue samples remained at a level comparable with that of the reference and was significantly higher in these samples than in those from the stroma. Chronic inflammation of the palatine tonsils thus results in intensive infiltration by various types of immune system cells and in excessive RCAS1 immunoreactivity, both of which confirm the important regulatory role of RCAS1 in the immune response in the mucosa-associated lymphatic tissue of Waldeyer's ring. RCAS1 seems to be involved in creating tumor-induced inflammation in the tumor and its microenvironment.

Apoptotic function of tumor-associated antigen RCAS1 in oral squamous cell carcinoma

Background

Receptor-binding cancer antigen expressed on SiSo cell (RCAS1) is derived from uterine adenocarcinoma and can induce apoptosis in lymphocytes, allowing tumor cells to escape from immune surveillance. RCAS1 is reportedly expressed in a membranous pattern on tumor cell or soluble one in serum of patients. The aim of this study was to investigate expression patterns of RCAS1 and the effect on apoptosis in oral squamous cell carcinoma (OSCC) cell lines.

Methods

In four kinds of OSCC cell lines (HSC-2, HSC-3, SQUU-A, and SQUU-B), RCAS1 mRNAs and proteins were determined by RT-PCR and immunocytochemistry. Membranous RCAS1 was determined by flow cytometry. Culture supernatants were analyzed for detection of soluble RCAS1 by dot blotting and enzyme-linked immunosorbent assay. Apoptotic ability of RCAS1 on the erythroid leukemia cell line K562 with the putative receptor was evaluated by flow cytometry in co-culture with highly metastatic SQUU-B, with knocked-down RCAS1 cells or in a no-cell contact condition.

Results

RCAS1 mRNA and proteins were expressed in all of OSCC cell lines. Membranous pattern were expressed in all cell lines, while soluble pattern was detected in all supernatants. RCAS1 mRNA, membranous and soluble RCAS1 were significantly seen in SQUU-B more than the other 3 cell lines (P < 0.05). K562 apoptosis was induced in co-culture with each of all cell lines, particularly with SQUU-B. Apoptosis was markedly reduced in co-culture with RCAS1 knockdown cells, but was induced in co-culture without cell contract of SQUU-B.

Conlusions

Our study suggests that RCAS1 has an apoptotic function via membranous/soluble expression pattern in OSCC cells. RCAS1 may thus affect tumor escape from immune surveillance in OSCC by inducing apoptosis.

The analysis of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) immunoreactivity within the microenvironment of the ovarian cancer lesion relative to the applied therapeutic strategy

RCAS1 is involved in generating the suppressive profile of the tumor microenvironment that helps cancer cells evade immune surveillance. The status of the cells surrounding the cancer nest may affect both the progression of the cancer and the development of metastases. In cases of ovarian cancer, a large number of patients do not respond to the applied therapy. The patient’s response to the applied therapy is directly linked to the status of the tumor microenvironment and the intensity of its suppressive profile. We analyzed the immunoreactivity of RCAS1 on the cells present in the ovarian cancer microenvironment in patients with the disease; these cells included macrophages and carcinoma-associated fibroblasts. Later we analyzed the immunoreactivity levels within these cells, taking into consideration the clinical stage of the cancer and the therapeutic strategy applied, such as the number of chemotherapy regiments, primary cytoreductive surgery, or the presence of advanced ascites. In the patients who did not respond to the therapy we observed significantly higher immunoreactivity levels of RCAS1 within the cancer nest than in those patients who did respond; moreover, in the non-responsive patients we found RCAS1 within both macrophages and carcinoma-associated fibroblasts. RCAS1 staining may provide information about the intensity of the immuno-suppressive microenvironment profile found in cases of ovarian cancer and its intensity may directly relate to the clinical outcome of the disease.

The Involvement of RCAS1 in Creating a Suppressive Tumor Microenvironment in Patients with Salivary Gland Adenocarcinoma

The tumor microenvironment is the tissue that determines the growth and progression of the tumor as well as its ability to initiate metastases. The aim of the present study has been to evaluate the role of RCAS1 in creating the suppressive tumor microenvironment in cases of parotid adenocarcinoma. The tissue samples of salivary gland adenocarcinomas and their stroma and the palatine tonsils which constituted the reference tissue sample group were obtained during routine surgical procedures. The immunoreactivity of RCAS1, CD3, CD25, CD68, CD69, and Foxp3 antigens was then evaluated by using the immunohistochemistry method. The patient’s consent was obtained in each case. A statistically significantly higher RCAS1 immunoreactivity level was found in the adenocarcinoma tissue samples in comparison to that found in the stromal tissue samples. A statistically significantly higher RCAS1 immunoreactivity was also identified in the adenocarcinoma tissue samples derived from patients who had lymph node metastases in comparison to patients without such metastases. Additionally, we observed the presence of RCAS1-positive macrophages in the stromal tissue samples. The infiltration of CD68-positive cells was significantly stronger in the adenocarcinoma and stromal tissue slides than in the reference group tissue slides; moreover, the infiltration was a good deal more prominent in the stromal tissue than in the adenocarcinoma tissue. The CD68 immunoreactivity levels in both the tumor and stromal tissue samples were found to be significantly higher in those patients who had lymph node metastases than in the patients without such metastases. Additionally, the infiltration of CD3- and CD25-positive cells was more prominent in the reference tissue slides than in the adenocarcinoma and stromal tissue slides, and was stronger in the adenocarcinoma tissue than in the stromal tissue. Furthermore, the infiltration of Foxp3-positive cells was seen exclusively in the stroma whereas it was not even detected in the adenocarcinoma tissue. Lastly, the Foxp3-positive cell infiltration was more prominent in the stromal tissue than in the reference group tissue. The present study demonstrates that RCAS1 expression by both tumor cells and tumor-associated macrophages may participate in creating the immunosuppressive microenvironment in parotid gland adenocarcinoma, thus promoting tumor development as well as metastases.

RCAS1, MT, and vimentin as potential markers of tumor microenvironment remodeling

A tumor stimulates the remodeling of its microenvironment for its own survival. To protect its own growth and induce angiogenesis, the tumor changes the structure of extracellular matrix and the function of existing cells; it thus chemo-attracts immune system cells altering their function. In our study, we discuss the potential markers of tumor microenvironment remodeling. For instance, RCAS1 is a protein responsible for tumor escape from host immunologic surveillance that additionally seems to be involved in the remodeling of the microenvironment. Another protein, metallothionein, which is both anti-apoptotic and pro-proliferative, is also responsible for modulating the response of immune system cells. Most likely, the expression of this protein by the fibroblasts of tumor microenvironment is related to the remodeled phenotype of these cells because of the tumor influence on cancer-associated fibroblasts. Lastly, vimentin is a protein that would appear to be the marker for the mesenchymal transition of cells from the epithelial phenotype. These cells seem to acquire the mesenchymal phenotype to migrate so that they can facilitate the development of metastases. Interestingly, the expression of vimentin has also been observed in the tumor microenvironment as well and may serve as a marker of a remodeled stroma in the process of facilitating tumor spread.

Receptor-binding cancer antigen expressed on SiSo cells induces apoptosis via ectodomain shedding

Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a secreted antigen that induces apoptosis in putative receptor-expressing cells, including peripheral lymphocytes and natural killer (NK) cells. RCAS1 expression is associated with aggressive characteristics and poor overall survival for 15 different human malignancies. The putative RCAS1 receptor has not been isolated and the mechanism of RCAS1 apoptosis induction remains unclear. This study explores how RCAS1 is involved in apoptosis initiation. The cell lines SiSo and MCF-7, human uterine carcinoma and breast adenocarcinoma, respectively, both express RCAS1, but RCAS1 secretion is undetectable in MCF-7 cells. SiSo and MCF-7 cells were stimulated to induce RCAS1 ectodomain shedding followed by assessment of RCAS1 expression and secretion. Additionally, the RCAS1 putative receptor-expressing human chronic myelogenous leukemia cell line K562 was co-cultured with SiSo, MCF-7, or soluble RCAS1 to follow RCAS1 secretion in apoptosis initiation. RCAS1 secretion was strongly suppressed by inhibitors of metalloproteases, protein kinase C (PKC)-delta, mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase kinase (MEK), epidermal growth factor (EGF), and G-protein-coupled receptor (GPCR). K562 apoptosis could be induced only by co-culturing with SiSo or soluble RCAS1. RCAS1 is thus secreted by ectodomain shedding, which may represent a pivotal step in RCAS1-induced apoptosis initiation.