Development of a Serum-Free Culture Method for Endothelial Cells of the Stria Vascularis and Their Pro-Inflammatory Secretome Changes Induced by Oxidative Stress.

OBJECTIVES: Reactive oxygen species in the stria vascularis (SV) of the cochlea may be involved in the pathogenesis of sensorineural hearing loss. However, the effects of oxidative stress on SV endothelial cells (SV-ECs) remain largely unknown, and no feasible in vitro cell culture model exists for the functional study of SV-ECs. METHODS: We isolated primary SV-ECs from the SV of neonatal mice. The apoptosis-reducing effects of fibronectin in SV-ECs cultured with serum-free medium were determined using ß-galactosidase staining and flow cytometry. SV-ECs incubated in serum-free medium were treated with various H2O2 concentrations to evaluate the effects of H2O2 on their viability. The secretome of SV-ECs treated with or without H2O2 (100 µM or 500 µM) was analyzed using high-resolution mass spectrometry. The function of the SV-EC secretome was evaluated by a macrophage assay. RESULTS: We successfully isolated and characterized the SV-ECs. Treatment with H2O2 at concentrations up to 500 µM for 2 hours and further incubation with serum-free medium in plates precoated with fibronectin showed no significant effect on apoptosis. Compared to the control SV-ECs, the amount of differential proteins in the secretome of SV-ECs stimulated with 500 µM H2O2 was much higher than in those treated with 100 µM H2O2. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses suggested that the proteins differentially expressed in SV-ECs treated with 500 µM H2O2 were involved in the regulation of multiple signaling pathways and cellular processes. The secretome of H2O2-stimulated SV-ECs exhibited significant pro-inflammatory effects on macrophages. CONCLUSION: We successfully established an in vitro serum-free culture method, identified the differential proteins released by oxidative stress-induced ECs and their functions, and revealed the pro-inflammatory effects of the secretome of H2O2-stimulated SV-ECs. Therefore, SV-ECs might elicit immunoregulatory effects on bystander cells in the microenvironment of oxidative stress-induced cochlea, especially cochlear macrophages.

MicroRNA-182 regulates otocyst-derived cell differentiation and targets T-box1 gene.

BACKGROUND: Recently, in vitro and in vivo models have identified that microRNAs (miRNAs), which are extensively expressed in the inner ear, play important roles in inner ear development and function. However, the function of miRNA in vertebrate tissue is not well understood. RESULTS: The current study used an in vitro model of embryonic mouse inner ear in a stem/progenitor cell culture to demonstrate that: 1) miR-182 is expressed during differentiation of inner ear stem/progenitor cell into a hair cell-like fate, 2) ectopic miR-182 promotes inner ear stem/progenitor cell differentiation into a hair cell-like fate, and 3) the function of miR-182 may be associated with its putative target Tbx1, a transcription factors that have been implicated in inner ear development and hair cell fate. CONCLUSIONS: Our findings suggest that miR-182 could regulate inner ear progenitor cell differentiation and that miRNAs are important regulators of hair cell differentiation, providing new targets for hair cell repair.

[DJ-1 expression in laryngeal squamous cell carcinoma and its relationship with tumor recurrence and metastasis].

OBJECTIVE: To detect the expression of DJ-1 in laryngeal squamous cell carcinoma (LSCC) and to study the relationship between DJ-1 expression and clinical indexes of LSCC. METHODS: The expressions of DJ-1 protein in 71 LSCC samples and 9 cases control samples from laryngeal mucosa tissues of non-LSCC patients were detected using streptavidin peroxidase immunohistochemistry staining and the relationships between DJ-1 protein expression and clinicopathologic characteristics were analyzed. RESULTS: (1) The positive expression rate of DJ-1 protein in LSCC was 85.9%(61/71), which was significantly higher than the rate (55.5%, 5/9) in control laryngeal mucosa tissues (P < 0.05). (2) DJ-1 expression was related to tumor recurrence (P < 0.05), but not to sex, age, primary cancer position, T stage, clinical stage, lymph node metastasis and tumor differentiation. Tumor recurrence rate (53.3%) in the patients with higher expression of DJ-1 protein was higher than the rate (26.8%) in the patients with lower expression of DJ-1 protein (χ(2) = 5.164, P < 0.05). (3) With Kaplan-Meier curves and Cox regression analysis, the cumulative 5-year survival rates were correlated with DJ-1 expression levels in laryngeal cancer tissues or cervical lymph node metastasis (all P < 0.05), but not to sex, age, primary cancer position, T stage, clinical stage and tumor differentiation. CONCLUSIONS: The expression of DJ-1 protein in LSCC is higher than that in control laryngeal mucous tissues. Overexpression of DJ-1 is associated with poor overall survival in LSCC patients.

MicroRNA expression in the embryonic mouse inner ear.

Although microRNA (miRNA) is expressed extensively in the postnatal mouse inner ear, its expression in the sensory epithelium during embryogenesis has not been well characterized. We investigated miRNA expression at E13.5 and E16.5 by microarray analysis, quantitative real-time-PCR, and in-situ hybridization. MiRNA-182, miRNA-140, miRNA-200c, and others showed distinct temporal and spatial expression patterns. MiRNA-194, whose expression in zebrafish seems to play an important role in the differentiation of the intestinal epithelium, was also expressed in the spiral ganglia of the mouse inner ear, where it may play a similar role in neuronal differentiation. Our results indicate that miRNAs are widely expressed in the developing inner ear, with more species recruited as hair cells differentiate, suggesting an important developmental role.

Inhibition of Aurora-A suppresses epithelial-mesenchymal transition and invasion by downregulating MAPK in nasopharyngeal carcinoma cells.

Mitotic serine/threonine kinase Aurora-A (Aur-A) plays a critical role in regulating centrosome segregation and spindle assemble. Aur-A overexpression causes excessive centrosome duplication and abnormal spindle structure, leading to tumor malignant progression. Here, we investigated Aur-A expression in nasopharyngeal carcinoma (NPC) and the association between Aur-A and NPC invasiveness. We showed that overexpression of Aur-A in tumor tissues was correlated with cranial bone invasion and clinical stage in NPC patients. Suppression of Aur-A by either selective Aurora inhibitory VX-680 or small-interfering RNA caused G(2)/M arrest and apoptotic cell death in NPC CNE-2 cells. Significantly, inhibition of Aur-A suppressed CNE-2 cell invasion and restored membrane expression of epithelial markers, E-cadherin and beta-catenin, suggesting a reversed epithelial-mesenchymal transition process in cancer cells. In addition, we found that Aur-A-regulated epithelial-mesenchymal transition and invasion were mediated by mitogen-activated protein kinase (MAPK) phosphorylation. Moreover, suppression of MAP kinase by small-interfering RNA or its upstream MEK1/2-selective inhibitor U0126 abrogated cell invasion enhanced by Aur-A overexpression. On the other hand, forced overexpression of constitutively active form of MEK1/2, MEK2DD, in CNE-2 cancer cells rescued cell invasive ability suppressed by VX-680-imposed Aur-A inhibition. Our results indicated that Aur-A acted through a downstream MAP kinase pathway to promote epithelial-mesenchymal transition and invasiveness in nasopharyngeal tumorigenesis. Small chemical inhibitor VX-680 may offer as a promising molecular targeting agent in human NPC.

ZM 447439 inhibition of aurora kinase induces Hep2 cancer cell apoptosis in three-dimensional culture.

Mitotic Aurora kinases are essential for accurate chromosome segregation during cell division. Forced overexpression of Aurora kinase results in centrosome amplification and multipolar spindles, causing aneuploidy, a hallmark of cancer. ZM447439 (ZM), an Aurora selective ATP-competitive inhibitor, interferes with the spindle integrity checkpoint and chromosome segregation. Here, we showed that inhibition of Aurora kinase by ZM reduced histone H3 phosphorylation at Ser10 in Hep2 carcinoma cells. Multipolar spindles were induced in these ZM-treated G(2)/M-arrested cells with accumulation of 4N/8N DNA, similar to cells with genetically suppressed Aurora-B. Cells subsequently underwent apoptosis, as assessed by cleavage of critical apoptotic associated protein PARP. Hep2 cells formed a tumor-like cell mass in 3-dimensional matrix culture; inhibition of Aurora kinase by ZM either destructed the preformed cell mass or prevented its formation, by inducing apoptotic cell death as stained for cleaved caspase-3. Lastly, ZM inhibition of Aurora kinase was potently in association with decrease of Akt phosphorylation at Ser473 and its substrates GSK3alpha/beta phosphorylation at Ser21 and Ser9. Together, we demonstrated that Aurora kinase served as a potential molecular target of ZM for more selective therapeutic cancer treatment.

Aurora kinase inhibitory VX-680 increases Bax/Bcl-2 ratio and induces apoptosis in Aurora-A-high acute myeloid leukemia.

Previously, we and others showed that mitotic Aurora-A kinase (Aur-A) was required for accurate mitotic entry and proper spindle assembly. In this study, we found that expression of Aur-A was markedly elevated in bone marrow mononuclear cells (BMMCs) obtained from a significant portion of de novo acute myeloid leukemia (AML) patients. Targeting human primary AML cells with Aur-A kinase inhibitory VX-680 led to apoptotic cell death in a dose-dependent manner. Importantly, VX-680-induced cell death was preferentially higher in Aur-A-high primary leukemic blasts compared with Aur-A-low AML (P < .001) or normal BMMCs (P < .001), suggesting the possible pharmacologic window in targeting Aurora kinase among Aur-A-high VX-680-sensitive leukemia patients. VX-680-induced cell death in AML cell lines was accompanied by formation of monopolar mitotic spindles, G(2)/M phase arrest, decreased phosphorylated(p)-Akt-1, and increased proteolytic cleavage of procaspase-3 and poly(ADP)ribose polymerase. Notably, VX-680 increased Bax/Bcl-2 expression ratio, a favorable proapoptotic predictor for drug response and survival in AML. Lastly, VX-680 enhanced the cytotoxic effect of the chemotherapeutic agent etoposide (VP16) on AML cells. Together, we concluded that Aurora kinases were potentially therapeutic targets for AML and that Aur-A-high expression may serve as a differential marker for selective treatment.

Aurora-A, a negative prognostic marker, increases migration and decreases radiosensitivity in cancer cells.

Centrosomal Aurora-A (Aur-A) kinase ensures proper spindle assembly and accurate chromosome segregation in mitosis. Overexpression of Aur-A leads to centrosome amplification, aberrant spindle, and consequent genetic instability. In the present study, Aur-A was found to be overexpressed in laryngeal squamous cell carcinoma (LSCC). Moreover, Aur-A expression was adversely correlated with median survival, and further identified as a potential independent factor for disease prognosis. Suppression of Aurora kinase activity chemically or genetically led to LSCC Hep2 cell cycle arrest and apoptotic cell death. Importantly, we found that Aur-A increases cell migration and this novel function was correlated with Akt1 activation. The enhanced cell migration induced by Aur-A overexpression could be abrogated by either small-molecule Akt1 inhibitor or short interfering RNA. VX-680, a selective Aurora kinase inhibitor, decreased Akt1 phosphorylation at Ser(473) and inhibited cell migration, but failed to do so in constitutive active Akt1 (myr-Akt1)-overexpressed cells. Moreover, our data suggested that overexpression of Aur-A kinase might also contribute to radioresistance of LSCC. Inhibiting Aur-A by VX-680 induced expression of p53 and potently sensitized cells to radiotherapy, leading to significant cell death. Ectopic overexpression of Aur-A, however, reduced p53 level and rendered cells more resistant to irradiation. Taken together, we showed that Aur-A kinase, a negative prognostic marker, promotes migration and reduces radiosensitivity in laryngeal cancer cells.