The ability of a cell to move requires the asymmetrical organization of cellular activities. To investigate polarized cellular activity in moving endothelial cells, human endothelial cells were incubated in a Dunn chamber to allow migration toward vascular endothelial growth factor. Immunofluorescent staining with a specific antibody against caveolin-1 revealed that caveolin-1 was concentrated at the rear of moving cells. Similarly, monolayer scraping to induce random cell walk resulted in relocation of caveolin-1 to the cell rear. These results suggest that posterior polarization of caveolin-1 is a common feature both for chemotaxis and chemokinesis. Dual immunofluorescent labeling showed that, during cell spreading, caveolin-1 was compacted in the cell center and excluded from nascent focal contacts along the circular lamellipodium, as revealed by integrin ␤ 1 and FAK staining. When cells were migrating, integrin ␤ 1 and FAK appeared at polarized lamellipodia, whereas caveolin-1 was found at the posterior of moving cells. Notably, wherever caveolin-1 was polarized, there was a conspicuous absence of lamellipod protrusion. Transmission electron microscopy showed that caveolae, similar to their marker caveolin-1, were located at the cell center during cell spreading or at the cell rear during cell migration. In contrast to its unphosphorylated form, tyrosine-phosphorylated caveolin-1, upon fibronectin stimulation, was associated with the focal complex molecule phosphopaxillin along the lamellipodia of moving cells. Thus, unphosphorylated and phosphorylated caveolin-1 were located at opposite poles during cell migration. Importantly, loss of caveolin-1 polarity by targeted down-regulation of the protein prevented cell polarization and directional movement. Our present results suggest a potential role of caveolin polarity in lamellipod extension and cell migration.

These results revealed that circRNAs may play a role in breast cancer chemoresistance and that hsa_circ_0006528 might be a promising candidate for further functional analysis.

Dextran sodium sulfate (DSS)-induced colitis is widely used to study pathological mechanisms and potential treatments of inflammatory bowel disease. Because temporal changes in genome expression profiles remain unknown in this model, we performed whole genome expression profile analysis during the development of DSS colitis in comparison with ulcerative colitis (UC) specimens to identify novel and common responses during disease. Colon tissue from DSS-treated mice was collected at days 0, 2, 4, and 6. Half of each specimen was used for histopathological analysis and half for Affymetrix whole genome expression profiling and qRT-PCR validation. Genesifter and Ingenuity software analysis was used to identify differentially expressed genes and perform interactive network analysis. Identified DSS-associated genes in mice were also compared with UC patient data. We identified 1,609 genes that were significantly altered during DSS colitis; the majority were functionally related to inflammation, angiogenesis, metabolism, biological adhesion, cellular growth and proliferation, and cell-to-cell signaling responses. Five hundred and one genes were progressively upregulated, while one hundred seventy-three genes were progressively downregulated. Changes in gene expression were validated in a subset of 33 genes by qRT-PCR, with r(2) = 0.925. Ingenuity gene interaction network analysis revealed novel relationships among antigen presentation, cell morphology, and other biological functions in the DSS mouse. Finally, DSS colitis gene array data were compared with UC patient array data: 152 genes were similarly upregulated, and 22 genes were downregulated. Temporal genomewide expression profile analysis of DSS-induced colitis revealed novel associations with various immune responses and tissue remodeling events such as angiogenesis similar to those in UC patients. This study provides a comprehensive view of DSS colitis changes in colon gene expression and identifies common molecules with clinical specimens that are interesting targets for further investigation.

Emerging research has indicated that circular RNAs (circRNAs), a novel class of noncoding RNAs, play a vital role in human tumorigenesis and progression. Our previous results suggested that hsa_circ_0006528 (circ_0006528), a circRNA with an unknown function, mediates adriamycin resistance in human breast cancer cells. However, the role of circ_0006528 in breast cancer progression remains unknown. Here, we investigated the probable involvement of circ_0006528 in breast cancer. We analyzed a cohort of 97 patients and found that circ_0006528 expression was significantly upregulated in human breast cancer tissues compared with that in adjacent nontumorous tissues and was significantly associated with advanced tumor-nodemetastasis (TNM) stage and poor prognosis. In addition, we found that in breast cancer cells, circ_0006528 could promote DNA synthesis and cell proliferation, invasion, and migration. Downregulating circ_0006528 induced G2 phase arrest and cell apoptosis. Further mechanistic studies revealed that circ_0006528 could sponge endogenous miR-7-5p and inhibit its activity. We also identified Raf1, which activates the MAPK/ERK signaling pathway, as a target of miR-7-5p and determined that circ_0006528 promotes breast cancer growth, invasion, and migration by promoting the expression of Raf1 and activates the MAPK/ERK pathway. Thus, this study provides the first evidence of the circ_0006528/miR-7-5p/Raf1/MEK/ERK regulatory network in the development of breast cancer and suggests that circ_0006528 is a potential therapeutic target and prognostic predictor for breast cancer.breast cancer, hsa_circ_0006528, invasion, migration, miR-7-5p, proliferation | INTRODUCTIONBreast cancer is the most prevalent cancer in women worldwide and represents a serious public health problem. One complication in the clinical management of breast cancer is the tendency of malignant cells to shed into the circulation during the early stages of tumor development, 1,2 causing the formation of metastatic foci, a phenomenon that directly contributes to approximately 90% of breast cancerrelated mortality. 3,4 The precise genetic and epigenetic mechanisms that regulate the formation and malignant progression of tumors remain unclear and require further study. Therefore, it is essential to Danfeng Gao, Xiaowei Qi, and Xiufen Zhang contributed equally to this work. |