MicroRNAs (miRNAs) are a class of endogenous small noncoding RNAs that regulate gene expression after transcription. Aberrant expression of miRNAs has been shown to be involved in tumorigenesis. We showed that miR-21 was one of the most frequently overexpressed miRNA in human glioblastoma (GBM) cell lines. To explore whether miR-21 can serve as a therapeutic target for glioblastoma, we downregulated miR-21 with a specific antisense oligonucleotide and found that apoptosis was induced and cell-cycle progression was inhibited in vitro in U251 (PTEN mutant) and LN229 (PTEN wildtype) GBM cells; xenograft tumors from antisense-treated U251 cells were suppressed in vivo. Antisense-miR-21-treated cells showed a decreased expression of EGFR, activated Akt, cyclin D, and Bcl-2. Although miR-21 is known to regulate PTEN and downregulation of miR-21 led to increased PTEN expression both endogenously and in a reporter gene assay, the GBM suppressor effect of antisense-miR-21 is most likely independent of PTEN regulation because U251 has mutant PTEN. Microarray analysis showed that the knockdown of miR-21 significantly altered expression of 169 genes involved in nine cell-cycle and signaling pathways. Taken together, our studies provide evidence that miR-21 may serve as a novel therapeutic target for malignant gliomas independent of PTEN status. Malignant gliomas are the most common primary brain tumors with high mortality and morbidity. The prognosis for malignant gliomas has not significantly improved in the last four decades. A recent meta-analysis of 12 randomized clinical trials showed that the overall survival rate of highgrade gliomas was 40% at 1 year after surgical removal and only slightly higher, 46%, after combined radiotherapy and chemotherapy. 1 To develop more optimized and effective treatment strategies for malignant gliomas, it is critical to gain deeper understanding of the molecular mechanisms underlying gliomagenesis and to identify targets for therapeutic intervention.The microRNAs (miRNAs) are a class of highly conserved small non-coding RNAs, approximately 22 nucleotides in length, that control gene expression through binding to the seed sequence at the 3 0 -UTR (untranslated region) of target mRNAs, resulting in translational repression or mRNA degradation. 2 This regulatory mechanism was first shown in the developmental processes in worms, flies, and plants. [3][4][5] Subsequently, miRNAs have been shown to have important roles in many physiological processes of mammalian systems by influencing cell apoptosis, proliferation, differentiation, development, and metabolism through regulation of critical signaling molecules including cytokines, growth factors, transcription factors, and pro-apoptotic and anti-apoptotic proteins. [6][7][8] Increasing number of miRNAs have been identified in the human genome and they are collectively called the miRNome. 9 Accumulating evidence shows the potential

BackgroundMicroRNAs (miRNAs) can function as either oncogenes or tumor suppressor genes via regulation of cell proliferation and/or apoptosis. MiR-221 and miR-222 were discovered to induce cell growth and cell cycle progression via direct targeting of p27 and p57 in various human malignancies. However, the roles of miR-221 and miR-222 have not been reported in human gastric cancer. In this study, we examined the impact of miR-221 and miR-222 on human gastric cancer cells, and identified target genes for miR-221 and miR-222 that might mediate their biology.MethodsThe human gastric cancer cell line SGC7901 was transfected with AS-miR-221/222 or transduced with pMSCV-miR-221/222 to knockdown or restore expression of miR-221 and miR-222, respectively. The effects of miR-221 and miR-222 were then assessed by cell viability, cell cycle analysis, apoptosis, transwell, and clonogenic assay. Potential target genes were identified by Western blot and luciferase reporter assay.ResultsUpregulation of miR-221 and miR-222 induced the malignant phenotype of SGC7901 cells, whereas knockdown of miR-221 and miR-222 reversed this phenotype via induction of PTEN expression. In addition, knockdonwn of miR-221 and miR-222 inhibited cell growth and invasion and increased the radiosensitivity of SGC7901 cells. Notably, the seed sequence of miR-221 and miR-222 matched the 3'UTR of PTEN, and introducing a PTEN cDNA without the 3'UTR into SGC7901 cells abrogated the miR-221 and miR-222-induced malignant phenotype. PTEN-3'UTR luciferase reporter assay confirmed PTEN as a direct target of miR-221 and miR-222.ConclusionThese results demonstrate that miR-221 and miR-222 regulate radiosensitivity, and cell growth and invasion of SGC7901 cells, possibly via direct modulation of PTEN expression. Our study suggests that inhibition of miR-221 and miR-222 might form a novel therapeutic strategy for human gastric cancer.

BackgroundMiR-221 and miR-222 (miR-221/222) are frequently up-regulated in various types of human malignancy including glioblastoma. Recent studies have reported that miR-221/222 regulate cell growth and cell cycle progression by targeting p27 and p57. However the underlying mechanism involved in cell survival modulation of miR-221/222 remains elusive.ResultsHere we showed that miR-221/222 inhibited cell apoptosis by targeting pro-apoptotic gene PUMA in human glioma cells. Enforced expression of miR-22/222 induced cell survival whereas knockdown of miR-221/222 rendered cells to apoptosis. Further, miR-221/222 reduced PUMA protein levels by targeting PUMA-3'UTR. Introducing PUMA cDNA without 3'UTR abrogated miR-221/222-induced cell survival. Notably, knockdown of miR-221/222 induces PUMA expression and cell apoptosis and considerably decreases tumor growth in xenograft model. Finally, there was an inverse relationship between PUMA and miR-221/222 expression in glioma tissues.ConclusionTo our knowledge, these data indicate for the first time that miR-221/222 directly regulate apoptosis by targeting PUMA in glioblastoma and that miR-221/222 could be potential therapeutic targets for glioblastoma intervention.

Increasing evidence suggests that aberrant activation of Wnt signaling is involved in tumor development and progression. Our earlier study on gene expression profile in human gliomas by microarray found that some members of Wnt family were overexpressed. To further investigate the involvement of Wnt signaling in gliomas, the expression of core components of Wnt signaling cascade in 45 astrocytic glioma specimens with different tumor grades was examined by reverse transcription-PCR and immunohistochemistry. Wnt2, Wnt5a, frizzled2 and beta-catenin were overexpressed in gliomas. Knockdown of Wnt2 and its key mediator beta-catenin in the canonical Wnt pathway by siRNA in human U251 glioma cells inhibited cell proliferation and invasive ability, and induced apoptotic cell death. Furthermore, treating the nude mice carrying established subcutaneous U251 gliomas with siRNA targeting Wnt2 and beta-catenin intratumorally also delayed the tumor growth. In both in vitro and in vivo studies, downregulation of Wnt2 and beta-catenin was associated with the decrease of PI3K/p-AKT expression, indicating the interplay between Wnt/beta-catenin and PI3K/AKT signaling cascades. In conclusion, the canonical Wnt pathway is of critical importance in the gliomagenesis and intervention of this pathway may provide a new therapeutic approach for malignant gliomas.

The present survey aims to study the prevalence and clinical characteristics of non-carious cervical lesions (NCCLs) and cervical dentine hypersensitivity (CDH), as well as their possible risk factors in a general population in China. A total of 1023 subjects were included in the present study. Each subject completed a structured interview, and all teeth of each subject were examined by a practitioner to determine NCCLs and CDH. Teeth with NCCLs and CDH were diagnosed according to the tooth wear index and by a blast of air from a triple syringe, respectively. Binary logistic regression was completed by analysing the association of risk factors with the occurrence of NCCLs and CDH. Loss of attachment (LOA) and gingival recession (GR) of teeth with NCCLs and/or CDH were measured using Williams periodontal probe. The diagnoses of NCCLs and CDH established following a clinical assessment yielded an overall prevalence of 61·7% and 27·1%, respectively. The 60-69 age group had the greatest proportion of subjects with NCCLs or CDH. The pre-molars were the most commonly affected teeth type with NCCLs or CDH. The proportion of teeth with CDH associated with NCCLs increased significantly with age, but the proportion of teeth with CDH only associated with LOA or GR decreased slowly with age. The single variables and interactive effects of variables associated with the occurrence of NCCLs include the following: age group, occupation type, method of toothbrushing, frequency and method of toothbrushing, and method of toothbrushing and duration of a toothbrush used. Gender, age group, occupation type and frequency of toothbrushing were associated with the occurrence of CDH. The current study presented higher prevalence of NCCLs and CDH in a general Chinese population. Both diseases were closely associated with age and periodontal status. The portion of the population with NCCLs or CDH had different risk factors.