Eylem Aydogdu

RNA viruses have recently been detected in association with house dust mites, including laboratory cultures, dust samples, and mite-derived pharmaceuticals used for allergy diagnosis. This study aimed to assess the incidence of viral infection on Dermatophagoides pteronyssinus physiology and on the allergenic performance of extracts derived from its culture. Transcriptional changes between genetically identical control and virus-infected mite colonies were analysed by RNAseq with the support of a new D. pteronyssinus high-quality annotated genome (56.8 Mb, 108 scaffolds, N50 = 2.73 Mb, 96.7% BUSCO-completeness). Extracts of cultures and bodies from both colonies were compared by inspecting major allergen accumulation by enzyme-linked immunosorbent assay (ELISA), allergen-related enzymatic activities by specific assays, airway inflammation in a mouse model of allergic asthma, and binding to allergic patient's sera IgE by ImmunoCAP. Viral infection induced a significant transcriptional response, including several immunity and stress-response genes, and affected the expression of seven allergens, putative isoallergens and allergen orthologs. Major allergens were unaffected except for Der p 23 that was upregulated, increasing ELISA titers up to 29% in infected-mite extracts. By contrast, serine protease allergens Der p 3, 6 and 9 were downregulated, being trypsin and chymotrypsin enzymatic activities reduced up to 21% in extracts. None of the parameters analysed in our mouse model, nor binding to human IgE were significantly different when comparing control and infected-mite extracts. Despite the described physiological impact of viral infection on the mites, no significant consequences for the allergenicity of derived extracts or their practical use in allergy diagnosis have been detected.

MiR‐206 is known to suppress breast cancer. However, while it is expressed in mammary stem cells, its function in such nontumor cells is not well understood. Here, we explore the role of miR‐206 in undifferentiated, stem‐like mammary cells using the murine mammary differentiation model HC11, genome‐wide gene expression analysis, and functional assays. We describe the miR‐206‐regulated gene landscape and propose a network whereby miR‐206 suppresses tumor development. We functionally demonstrate that miR‐206 in nontumor stem‐like cells induces a G1–S cell cycle arrest, and reduces colony formation and epithelial‐to‐mesenchymal transition markers. Finally, we show that addition of miR‐206 accelerates the mammary differentiation process along with related accumulation of lipids. We conclude that miR‐206 impacts a network of signaling pathways, and acts as a regulator of proliferation, stemness, and mammary cell differentiation in nontumor stem‐like mammary cells. Our study provides a broad insight into the breast cancer suppressive functions of miR‐206.

Triple-negative breast cancer (TNBC) is characterized by aggressiveness and affects 10–20% of breast cancer patients. Since TNBC lacks expression of ERα, PR and HER2, existing targeted treatments are not effective and the survival is poor. In this study, we demonstrate that the tumor suppressor microRNA miR-200a directly regulates the oncogene EPH receptor A2 (EPHA2) and modulates TNBC migration. We show that EPHA2 expression is correlated with poor survival specifically in basal-like breast cancer and that its expression is repressed by miR-200a through direct interaction with the 3′UTR of EPHA2. This regulation subsequently affects the downstream activation of AMP-activated protein kinase (AMPK) and results in decreased cell migration of TNBC. We establish that miR-200a directs cell migration in a dual manner; in addition to regulating the well-characterized E-cadherin pathway it also regulates a EPHA2 pathway. The miR-200a-EPHA2 axis is a novel mechanism highlighting the possibility of utilizing miR-200a delivery to target TNBC metastases.

Patients with triple‐negative breast cancer (TNBC) have an overall poor prognosis, which is primarily due to a high metastatic capacity of these tumors. Novel therapeutic approaches to target the signaling pathways that promote metastasis are desirable, in order to improve the outcome for these patients. A loss of function of a microRNA, miR‐206, is related to increased metastasis potential in breast cancers but the mechanism is not known. In this study, we show that miR‐206 was decreased in TNBC clinical tumor samples and cell lines whereas one of its predicted targets, actin‐binding protein CORO1C, was increased. Expression of miR‐206 significantly reduced proliferation and migration while repressing CORO1C mRNA and protein levels. We demonstrate that miR‐206 interacts with the 3'‐untranslated region (3'‐UTR) of CORO1C and regulates this gene post‐transcriptionally. This post‐transcriptional regulation was dependent on two miR‐206‐binding sites within the 3'‐UTR of CORO1C and was relieved by mutations of corresponding sites. Further, silencing of CORO1C reduced tumor cell migration and affected the actin skeleton and cell morphology, similar to miR‐206 expression, but did not reduce proliferation. In accordance with this, overexpression of CORO1C rescued the inhibitory effect of miR‐206 on cell migration. Our findings suggest that miR‐206 represses tumor cell migration through direct targeting of CORO1C in TNBC cells which modulates the actin filaments. This pathway is a novel mechanism that offers a mechanistic basis through which the metastatic potential of TNBC tumors could be targeted.

MicroRNAs (miRNAs) play pivotal roles in stem cell biology, differentiation and oncogenesis and are of high interest as potential breast cancer therapeutics. However, their expression and function during normal mammary differentiation and in breast cancer remain to be elucidated. In order to identify which miRNAs are involved in mammary differentiation, we thoroughly investigated miRNA expression during functional differentiation of undifferentiated, stem cell-like, murine mammary cells using two different large-scale approaches followed by qPCR. Significant changes in expression of 21 miRNAs were observed in repeated rounds of mammary cell differentiation. The majority, including the miR-200 family and known tumor suppressor miRNAs, was upregulated during differentiation. Only four miRNAs, including oncomiR miR-17, were downregulated. Pathway analysis indicated complex interactions between regulated miRNA clusters and major pathways involved in differentiation, proliferation and stem cell maintenance. Comparisons with human breast cancer tumors showed the gene profile from the undifferentiated, stem-like stage clustered with that of poor-prognosis breast cancer. A common nominator in these groups was the E2F pathway, which was overrepresented among genes targeted by the differentiation-induced miRNAs. A subset of miRNAs could further discriminate between human non-cancer and breast cancer cell lines, and miR-200a/miR-200b, miR-146b and miR-148a were specifically downregulated in triple-negative breast cancer cells. We show that miR-200a/miR-200b can inhibit epithelial–mesenchymal transition (EMT)-characteristic morphological changes in undifferentiated, non-tumorigenic mammary cells. Our studies propose EphA2 as a novel and important target gene for miR-200a. In conclusion, we present evidentiary data on how miRNAs are involved in mammary cell differentiation and indicate their related roles in breast cancer.