In vitro cytokine expression in in situ-like areas of malignant neoplasia

Two sides of the same coin: Insights into the myoepithelial cells in carcinoma ex pleomorphic adenoma development

The myoepithelial cell seems to play an important role as a tumor suppressor in the development of carcinoma ex pleomorphic adenoma. Nevertheless, interesting aspects concerning the other side of the coin, i.e., the contribution of the myoepithelial cell to cell proliferation, were brought to light. Here we highlighted the studies in which myoepithelial cells were presented as tumor suppressors and promoters in the context of PA malignant transformation. In conclusion, even if in a paracrine way, divergent signals can alter the suppressor role of the myoepithelial cell and induce it to compose a microenvironment propitious to the tumor progression of the malignant cells. This would cause myoepithelial cells to succumb and malignant epithelial cells to initiate progression beyond the basal membrane.

Interleukin-6-mediated epigenetic control of the VEGFR2 gene induces disorganized angiogenesis in human breast tumors

Disorganized vessels in the tumor vasculature lead to impaired perfusion, resulting in reduced accessibility to immune cells and chemotherapeutic drugs. In the breast tumor-stroma interplay, paracrine factors such as interleukin-6 (IL-6) often facilitate disordered angiogenesis. We show here that epigenetic mechanisms regulate the crosstalk between IL-6 and vascular endothelial growth factor receptor 2 (VEGFR2) signaling pathways in myoepithelial (CD10+) and endothelial (CD31+, CD105+, CD146+, and CD133-) cells isolated from malignant and nonmalignant tissues of clinically characterized human breast tumors. Tumor endothelial (Endo-T) cells in 3D cultures exhibited higher VEGFR2 expression levels, accelerated migration, invasion, and disorganized sprout formation in response to elevated IL-6 levels secreted by tumor myoepithelial (Epi-T) cells. Constitutively, compared with normal endothelial (Endo-N) cells, Endo-T cells differentially expressed DNA methyltransferase isoforms and had increased levels of IL-6 signaling intermediates such as IL-6R and signal transducer and activator of transcription 3 (STAT3). Upon IL-6 treatment, Endo-N and Endo-T cells displayed altered expression of the DNA methyltransferase 1 (DNMT1) isoform. Mechanistic studies revealed that IL-6 induced proteasomal degradation of DNMT1, but not of DNMT3A and DNMT3B and subsequently led to promoter hypomethylation and expression/activation of VEGFR2. IL-6-induced VEGFR2 up-regulation was inhibited by overexpression of DNMT1. Transfection of a dominant-negative STAT3 mutant, but not of STAT1, abrogated VEGFR2 expression. Our results indicate that in the breast tumor microenvironment, IL-6 secreted from myoepithelial cells influences DNMT1 stability, induces the expression of VEGFR2 in endothelial cells via a promoter methylation-dependent mechanism, and leads to disordered angiogenesis.

TGF-β1 stimulates epithelial-mesenchymal transition and cancer-associated myoepithelial cell during the progression from in situ to invasive breast cancer

Background

The progression of ductal carcinoma in situ (DCIS) into invasive ductal carcinoma (IDC) is prevented by normal breast myoepithelial cells. Studies have suggested that EMT-associated genes were enriched in IDC in contrast to DCIS. This paper explored the relationship and potential mechanism between myoepithelial cells and EMT-associated genes in facilitating the transformation from DCIS to breast cancer.

Methods

EMT markers and myoepithelial phenotypic markers in IDC, DCIS, and healthy breast tissue were characterized using immunohistochemical assay. Both in vivo and in vitro models were created to mimic the various cell–cell interactions in the development of invasive breast cancer.

Results

We found that EMT markers were more abundant in invasive carcinomas than DCIS and adjacent normal breast tissue. Meanwhile, TGF-β1 regulated the morphology of MCF-7 (epithelial cells substitute) migration and EMT markers during the transformation from DCIS to invasive breast cancer. Additionally, TGF-β1 also regulated invasion, migration and cytokines secretion of MDA-MB-231 (myoepithelial cells substitute) and epithelial cells when co-cultured with MCF-7 both in vitro and in vivo.

Conclusions

In conclusion, these findings demonstrated that both EMT phenotypes and cancer-associated myoepithelial cells may have an impact on the development of invasive breast cancer.

Novel interleukin-33 and its soluble ST2 receptor as potential serum biomarkers in parotid gland tumors

An increasing number of patients with parotid gland tumors have been observed in recent years. The relationship between the immune system and tumor formation is thoroughly investigated. However, newly discovered molecules offer a new insight into the pathophysiology of malignancies. It would be ideal to find an easily determinable biomarker of tumor existence, its malignant potential or a biomarker suggesting the probability of disease recurrence. Our study is the first to examine serum concentrations of IL-33 and its sST2 receptor in patients with various types of parotid gland tumors. Serum IL33, sST2, IL-4 and IL-10 concentrations were determined in patients with benign and malignant parotid gland tumors (pleomorphic adenoma, Warthin's tumor, myoepithelioma and acinic cell carcinoma). We observed for the first time that serum IL-33 level was significantly elevated in patients with various types of parotid gland tumors and sST2 levels were significantly higher in pleomorphic adenoma and acinic cell carcinoma patients compared to the controls. Our results demonstrate for the first time that serum IL-33 and its sST2 receptor may be important factors in the pathology of parotid gland tumors. Although our results are promising, further investigations are required to detect if serum concentrations of those molecules may be a biomarker in parotid gland tumors. Impact statement Parotid gland tumors seem to be an increasingly important medical challenge, mostly due to a noticeable increase in the incidence. It would be crucial to find an easily determinable biomarker of tumor existence, its recurrence or malignant potential. We observed for the first time that serum IL-33 level was significantly elevated in patients with various types of parotid gland tumors and its sST2 receptor levels were significantly higher in pleomorphic adenoma and acinic cell carcinoma patients compared to the controls. We believe that our study helps to understand the biology of the tumors and a potential role of a relatively newly identified cytokine IL-33 in the pathophysiology of the parotid gland tumors.

How do benign myoepithelial cells from in situ areas of carcinoma ex-pleomorphic adenoma favor tumor progression?

In this brief commentary, we have shown how the benign myoepithelial cells from in situ areas of carcinoma ex-pleomorphic adenoma from salivary gland can favor tumor progression, not only dying by autophagy/senescence phenomena, disrupting the physical barrier, but also providing fuel for tumor progression.

Cellular senescence and autophagy of myoepithelial cells are involved in the progression of in situ areas of carcinoma ex-pleomorphic adenoma to invasive carcinoma. An in vitro model

During tumor invasion, benign myoepithelial cells of carcinoma ex-pleomorphic adenoma (CXPA) surround malignant epithelial cells and disappear. The mechanisms involved in the death and disappearance of these myoepithelial cells were investigated via analysis of the expression of regulatory proteins for apoptosis, autophagy and cellular senescence in an in situ in vitro model. Protein expression relating to apoptosis (Bax, Bcl-2, Survivin), autophagy (Beclin-1, LC3B) and cellular senescence (p21, p16) was evaluated using indirect immunofluorescence. β-galactosidase expression was assessed via histochemistry. Biopsies of CXPA (ex vivo) allowed immunhistochemical evaluation of p21 and p16, whilst LC3B, p21 and p16 protein expression was analyzed by western blotting. In the in vitro model, the myoepithelial cells were positive for LC3B (cytoplasm) and p21 (nucleus), whilst in vivo positivity for p21 and p16 was observed. In vitro, β-galactosidase activity increased in the myoepithelial cells over time. Western blotting analysis revealed an increased LC3B, p16 and p21 expression in the myoepithelial cells with previous contact with the malignant cells when compared with those without contact. The investigation of behavior of benign myoepithelial cells in ductal areas of CXAP revealed that the myoepithelial cells are involved in the autophagy-senescence phenotype that subsequently leads to their disappearance.

Myoepithelial cells from pleomorphic adenoma are not influenced by tumor conditioned media from breast ductal adenocarcinoma and melanoma cells: An in vitro study

Myoepithelial cells have been implicated in the regulation of the transition from in situ to invasive neoplasia in salivary gland tumors. Considering the importance of the microenvironment of the tumor, the present in vitro study therefore analyzed the morphological and phenotypic changes undergone by benign myoepithelial cells from pleomorphic adenoma (PA) stimulated by tumor-conditioned medium. The benign myoepithelial cells were obtained from PA and were cultured with fibronectin extracellular matrix protein, supplemented with tumor-conditioned medium, which was harvested from breast ductal adenocarcinoma AU-565 and melanoma Hs 852.T cells. The morphological alterations were assessed by immunofluorescence analysis using vimentin antibody. The α-smooth muscle actin (α-SMA) and fibroblast growth factor (FGF)-2 proteins were analyzed by indirect immunofluorescence and quantitative polymerase chain reaction (qPCR). No morphological changes were observed in the myoepithelial cells cultured in fibronectin protein under stimulation from either tumor-conditioned medium. The immunofluorescence results, which were supported by qPCR analysis, revealed that only α-SMA was upregulated in the fibronectin substratum, with or without tumor-conditioned medium obtained from breast ductal adenocarcinoma and melanoma cells. No significant difference in FGF-2 mRNA expression was detected when the cells were cultured either in the tumor-conditioned medium or in the fibronectin substratum. The tumor-conditioned medium harvested from breast ductal adenocarcinoma and melanoma did not affect myoepithelial cell differentiation and function, which was reflected by the fact that there was no observed increase in α-SMA and FGF-2 expression, respectively.

The EGF signaling pathway influences cell migration and the secretion of metalloproteinases by myoepithelial cells in pleomorphic adenoma

During tumor development, benign neoplastic cells are influenced by the expression of cytokines, growth factors, and proteases present in the tumor microenvironment. Epidermal growth factor (EGF) is the most studied growth factor and is considered important for cell proliferation and migration. Metalloproteinases (MMPs) are also involved in tumor progression. The present study aimed to analyze the proliferation, viability and migration index of pleomorphic adenoma myoepithelial cells, in addition to the secretion of MMPs with EGF supplementation. Benign myoepithelial cells were cultured with two different EGF doses (5 and 10 ng/ml), and the influence of EGF on cell proliferation and viability, using trypan blue and MTT assays, respectively, after 24, 48, and 72 h, was evaluated. To analyze cellular morphology, hematoxylin-eosin staining and indirect immunofluorescence using the anti-vimentin antibody, was performed. In vitro migration assays were performed in Transwell chambers with an 8-μm pore covered with Matrigel and supplemented with 5 or 10 ng/ml of EGF, after 96 h. After 4 days of cell culture, ELISA was performed to determine the MMP-2 and MMP-13 levels. One-way analysis of variance (ANOVA) with post hoc Tukey test was applied, with a significance level of 0.05. The results revealed that EGF influences myoepithelial cell morphology, without alteration of proliferation and viability. The migration assay showed that EGF increased the mean index from 16 % in the control group to 40 and 76 % for 5 and 10 ng/ml of EGF, respectively. ELISA revealed that when the cells were supplemented with either of the EGF doses, an increase in MMP-2 levels was observed when compared with the control group (C). This study concludes that EGF aids in the production of MMP-2, which favors the dissolution of the basement membrane, contributing to cell migration and tumor progression, hence permitting contact between the myoepithelial cells and stroma.

In-vitro analysis of rhBMP-2 effects in human osteogenic cells

This study evaluated the in vitro expression of bone-related proteins by osteoblasts in the presence of different concentrations of human recombinant bone morphogenetic protein-2 (rhBMP-2). Immortalized human fetal osteoblastic cell line 1.19 (hFOB) were exposed to different concentrations of rhBMP-2 (10, 50, or 100 ng/mL) for 72 h. Cell proliferation and viability (MTT assay), as well as the expression of fibronectin, osteonectin, and osteopontin were assessed by indirect immunofluorescence and Western blot. Neither of the 3 concentrations of rhBMP-2 caused statistically significant alterations in cell proliferation and viability, although the concentration of 100 ng/mL showed lower values for both assays after both 48 and 72 h of exposure. There was no alteration in the expression of noncollagenous proteins, as analyzed by immunofluorescence, when compared with the control group. Furthermore, in the Western blot assay we observed a statistically significant decrease in fibronectin and osteonectin at 100 ng rhBMP-2/mL (p < 0.05) by comparison with the medium alone. The expression of osteopontin decreased slightly in all 3 concentrations of rhBMP-2 tested; however, the change was not statistically significant (p > 0.05). In this in-vitro study, the tested concentrations of rhBMP-2 appeared to decrease the expression of important bone-related molecules in pre-osteoblast cells.