Effects of melatonin receptor expression on prognosis and survival in oral squamous cell carcinoma patients.

Melatonin receptors can inhibit breast and prostate cancers; however, little is known regarding their effects on oral squamous cell carcinoma. In this study, we collected specimens from 81 patients with oral squamous cell carcinoma and analysed clinicopathological data retrospectively. In addition, the expression of the melatonin receptor was analysed immunohistochemically. Survival rates were calculated using the Kaplan-Meier method and log-rank test. Multivariate analysis was performed based on the Cox proportional-hazards model. Further, an in vitro study was performed using YD15 cells. The cells were transfected with siRNA targeting melatonin receptor 1A and 1B for evaluating the malignancy of melatonin receptors by western blotting, trypan blue-exclusion, colony-forming, wound-healing, and invasion assays. Survival decreased as melatonin receptor expression and clinical and pathological tumour-node-metastasis stages increased. A Cox proportional-hazard model showed that melatonin receptor 1A may serve as a significant predictor of the survival rate of patients with oral squamous cell carcinoma [hazard ratio = 1.423, 95% confidence interval (CI) = 1.019-1.988, p = 0.038]. Melatonin receptor 1A and 1B knockdown significantly suppressed proliferation, migration ability, and invasion ability of YD15 cells in vitro. Our findings reveal that inhibiting melatonin receptor expression may suppress oral squamous cell carcinoma development.

Comparison of two new generation influenza rapid diagnostic tests with instrument-based digital readout systems for influenza virus detection.

INTRODUCTION: Influenza rapid diagnostic tests (RDTs) have been developed to supply scientists with more sensitive and specific techniques. Newly developed digital reader-based techniques require test evaluations before their clinical application. METHODS: Two types of digital influenza RDTs using a digital readout system and one conventional RDT were compared using 314 nasopharyngeal swabs of influenza. The swabs originated from symptomatic individuals suspected of influenza infection, and the presence of influenza was confirmed with influenza real-time polymerase chain reaction (PCR) testing and influenza subtyping. Methods were the Sofia® Influenza A + B Fluorescence Immunoassay (FIA), which uses a portable fluorescence analyser, the BD Veritor™ System Flu A + B, which uses a colorimetric immunochromatographic method with a reflectance-based measurement digital device, and the SD Bioline assay, which is based on a traditional immunochromatographic method. RESULTS: The Sofia® Influenza A + B system, the BD Veritor™ System Flu A + B and the SD Bioline assay showed sensitivities in relative real-time PCR results of 74.2, 73.0 and 53.9%, respectively, for influenza A, and 82.5, 72.8 and 71.0%, respectively, for influenza B. All three RDTs showed 100% specificities for influenza A and influenza B. The Sofia® Influenza A + B Fluorescence Immunoassay showed sensitive and specific results for the detection of influenza B in contrast to the BD Veritor™ System Flu A + B. The two digital RDTs showed higher sensitivity and specificity than the conventional RDT in the detection of the influenza H3 subtype. CONCLUSIONS: Digital-based readout systems for the detection of the influenza virus can be applied for more sensitive diagnosis in clinical settings than conventional RDTs.

Arsenic trioxide induces G2/M growth arrest and apoptosis after caspase-3 activation and bcl-2 phosphorylation in promonocytic U937 cells.

Arsenic trioxide has recently been shown to inhibit growth and induce apoptosis in acute promyelocytic leukemia (APL), but little is known about the molecular mechanisms mediating these effects. Here we demonstrate that treatment of promonocytic U937 cells with arsenic trioxide leads to G2/M arrest which was associated with a dramatic increase in the levels of cyclin B and cyclin B-dependent kinase and apoptosis. We further show that apoptosis occurs after bcl-2 phosphorylation and caspase-3 activation followed by cleavage of PARP and PLC-gamma1 degradation and DNA fragmentation. The arsenic trioxide-induced apoptosis could be blocked by the protein synthesis inhibitor cycloheximide. In addition, pretreatment of U937 cells with the DNA polymerase inhibitor aphidicolin also blocked apoptosis, but did not cause the arrest of cells in the G2/M phase. The findings suggest that arsenic trioxide exerts its growth-inhibitory effects by modulating expression and/or activity of several key G2/M regulatory proteins. Furthermore, arsenic trioxide-mediated G2/M arrest correlates with the onset of apoptosis.

Chemopreventive agent resveratrol, a natural product derived from grapes, reversibly inhibits progression through S and G2 phases of the cell cycle in U937 cells.

Resveratrol, a natural product derived from grapes, has been shown to prevent carcinogenesis in murine models. We report here that resveratrol induces antiproliferation and arrests the S phase in human histiocytic lymphoma U937 cells. Resveratrol induces arrest in the S phase at low concentrations (30-60 microM), but high concentrations do not induce S phase accumulation in U937 cells. Removal of resveratrol from the culture medium stimulates U937 cells to reenter the cell cycle synchronously, as judged by the expression patterns of cyclin E, A and by fluorescent activated cell sorting analysis. These data demonstrate that resveratrol causes S phase arrest and reversible cell cycle arrest. Thus, resveratrol provides an important new cell cycle blocker as well as a cancer chemopreventive agent.

p53-independent elevation of p21 expression by PMA results from PKC-mediated mRNA stabilization.

The p21 (cip1/waf1) protein induces cell cycle arrest through inhibition of the activity of cdk (cyclin dependent kinase)/cyclin complexes. Expression of p21 is induced in a p53-dependent manner by DNA damage. p21 can also be induced independently of p53 by phorbol ester or okadaic acid. In this study, we have addressed the role of the PKC (protein kinase C) signaling pathway in the induction of p21 in response to PMA (phorbol myristate acetate) and okadaic acid. Levels of p21 (protein and mRNA) rapidly increased (within approximately 4 h) in U937 cells treated with PMA. The PKC-specific inhibitors RO 31-8220 and GF109203X down-regulated PMA or okadaic acid-induced p21 expression. Following persistent PKC activation, p21 mRNA levels remained elevated, indicating an enhanced stability of the mRNA. Using actinomycin D to measure mRNA stability and p21 promoter luciferase assays to measure activity, we provide evidence to support a role for the PKC signaling pathway in p21 mRNA stability. Thus, PKC regulates the amount of p21 in U937 cells at the level of mRNA accumulation and translation.