Decreased level of cyclin A2 in rat cochlea development and cochlear stem cell differentiation

Telomerase reverse transcriptase induced thyroid carcinoma cell proliferation through PTEN/AKT signaling pathway

Thyroid carcinoma is the most common endocrine malignant tumor in the world, and so, there is a requirement to develop novel molecular targets for thyroid cancer diagnosis and treatment. Telomerase reverse transcriptase (TERT) was revealed to promote cell proliferation in a number of types of cell. To evaluate whether and how TERT functioned on papillary thyroid cancer (PTC) cell proliferation, the present study constructed TERT over‑expression [recombined (r)TERT plasmid group] and interference [small interfering RNA (si)‑TERT group] models by liposome transfection respectively to study the molecular mechanisms. The transfection efficiency was first detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting to analyze TERT levels compared with the negative control (NC) and control groups. Then MTT and carboxyfluorescein diacetate succinimidyl ester assays were performed to determine living cell proliferation and total cell proliferation respectively. Propidium iodide assay was used to detect alterations in cell cycle progression. RT‑qPCR and western blotting were performed to detect associated factor variation. The results demonstrated that, following the generation of TERT overexpression or silencing PTC cells, the living cells and also total cell proliferation increased significantly in the rTERT group, and decreased significantly in siTERT group, when compared with the NC and control groups. The cell cycle was accelerated in the rTERT group, and blocked in the G1/S transition in the siTERT group. The mRNA and protein levels of P27, P53 and phosphatase and tensin homolog (PTEN) decreased significantly in the rTERP group and increased in the siTERP group, while cyclin dependent kinase 2 and Cyclin D1 increased significantly in the rTERP group and decreased in the siTERP group. The expression of cell division cycle 25A did not alter significantly. The protein levels of β‑catenin and retinoblastoma were also unaltered. Protein kinase B (AKT) was detected once activated by TERT, and there were increased phosphorylated (p)‑AKT protein levels in the rTERT group, and decreased p‑AKT protein levels in the siTERT group. In conclusion, TERT could induce thyroid carcinoma cell proliferation mainly through the PTEN/AKT signaling pathway.

Publications about hearing in otorhinolaryngology journals from chinese authors: a 11-year survey of the literature

Hearing loss is a leading cause of disability in China. However, the research status in the field of hearing among Chinese individuals in the three major regions of China: Mainland (ML), Hong Kong (HK) and Taiwan (TW), are unknown. The output of hearing articles published in international otorhinolaryngology journals from these three regions were compared in this study. Articles published in 31 international otorhinolaryngology journals related to hearing originating from the ML, TW and HK from 2000 to 2011 were retrieved from the PubMed database search. The number of total articles, clinical trials, randomized controlled trials, case reports, and articles published in the top 5 international otorhinolaryngology journals were assessed in terms of quantity and quality comparisons. The total number of articles from the three regions increased significantly from 2000 to 2011. There were 379 articles from ML (143), TW (180) and HK (56) in the past 10 years. The number of articles published per year from the ML has exceeded those from TW in 2009 and HK in 2003. TW had the most articles (46) published in the top 5 international otorhinolaryngology journals among the three regions. The total number of articles from the three major regions of China increased significantly from 2000 to 2011. The numbers of articles published per year from the ML have exceeded those from TW and HK. However, the quality of articles from TW is better than that from ML.

Dynamic changes in microRNA expression during differentiation of rat cochlear progenitor cells in vitro

OBJECTIVE

Cochlear progenitor cells could be used to explore the cochlea developmental mechanism and for cell replacement therapy in deafness. MicroRNAs are small, noncoding RNAs that could regulate the cell fate of stem cells, as well as cellular proliferation, differentiation and maturation. An expression profile analysis of microRNAs is necessary to understand their complex roles in differentiating cochlear progenitor cells.

METHODS

The microRNAs microarray was used to analyze microRNA expression changes while differentiating cochlear progenitor cells. Quantitative real-time polymerase chain reaction was used to confirm and compare the results of the microarray and to detect the expression pattern of several microRNAs during the differentiation of neural stem cells.

RESULTS

Nearly 100 microRNAs were identified from the microarray. Most showed changes in expression levels as cochlear progenitor cell differentiation progressed. The quantitative real-time polymerase chain reaction result demonstrated that the miR-183 family exhibits cell-specific expression in cochlear progenitor cells compared with neural stem cells.

CONCLUSIONS

The temporal regulation of these microRNAs indicated that they might play different roles in differentiating cochlear progenitor cells, and that specific microRNAs might influence the cell fate determination of cochlear progenitor cells.

TRRAP and the maintenance of stemness in gliomas

Resistance of brain tumors to therapy and their eventual recurrence is attributed to stem-like cells. In this issue of Cell Stem Cell, a high-throughput kinome-wide screen (Wurdak et al., 2010) has identified TRRAP, a kinase-related protein, as being required for stem cell character in gliomas.

A comparison of the proliferative capacity and ultrastructure of proliferative cells from the cochleae of newborn rats of different ages

OBJECTIVE

Recent reports have shown that multipotent stem cells/progenitor cells that are capable of proliferation and regeneration are present in mammalian cochleae. However, progenitor cells have not been isolated from the adult cochlea. We examined the proliferative potential of cells derived from neonatal rats of various ages. The determination of the differences between the proliferative cells from rats of different ages may provide clues to the mechanisms controlling the destiny of these cells.

METHODS

Proliferative cells were isolated from the cochleae of 1-, 7-, and 14-day-old rats, and the proliferative capacity and ultrastructure of the cells from each age group were assessed using flow cytometry and transmission electron microscopy, respectively.

RESULTS

During the first two postnatal weeks, the number of proliferative cells gradually fell to zero. This decrease occurred in parallel with the impairment of the proliferative capacity of the cells and the accumulation of proliferative cells in G0/G1. In addition, some of the cells exited the cell cycle by means of gradual maturity and apoptosis.

CONCLUSIONS

Our study suggests that cochlear proliferative cells are remnants of the progenitor cells that originally gave rise to the sensory epithelium. The disappearance of the cochlear proliferative cells in adult mammalian cochleae may result from their differentiation and/or apoptosis.