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    Clinicopathological significance of nuclear PTEN expression in colorectal adenocarcinoma
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    Abstract:
    Jang K‐S, Song Y S, Jang S‐H, Min K‐W, Na W, Jang S M, Jun Y J, Lee K H, Choi D & Paik S S (2010) Histopathology 56, 229–239 Clinicopathological significance of nuclear PTEN expression in colorectal adenocarcinoma Aims: Tumour suppressor phosphatase and tensin homologue ( PTEN ) is an important negative regulator for the PIP3/Akt signalling pathway that promotes cell proliferation and inhibits apoptosis. Inactivation of PTEN by mutation, deletion and promoter hypermethylation has been demonstrated in a range of cancers. The aim was to investigate whether the loss of nuclear PTEN protein expression correlates with conventional clinicopathological parameters and patient survival. Methods and results: Immunohistochemistry staining for PTEN was performed on a tissue microarray of 19 samples of normal colonic mucosa, 14 adenomatous polyps, 482 adenocarcinomas and 56 metastatic lymph nodes. All 19 normal colonic mucosa samples (100%) were positive and 12 (85.7%) out of 14 adenomatous polyps were positive for PTEN. However, only 241 (50.0%) of the 482 colorectal adenocarcinomas and 26 (46.4%) of the 56 metastatic lymph nodes were positive for PTEN. Loss of PTEN expression was related to defective mismatch repair protein expression and colonic localization rather than rectal localization. On univariate survival analysis, patients with PTEN− adenocarcinoma revealed a poor overall and disease‐free survival ( P = 0.030 and P = 0.046, respectively). On multivariate analysis, a significant difference was observed in patients with stage II cancer that was not observed in other stages. Conclusions: Nuclear PTEN expression gradually decrease during the normal–adenoma–adenocarcinoma–metastasis sequence, which suggests an important role for PTEN in carcinogenesis. Moreover, loss of nuclear PTEN expression was a marker of poor clinical outcome in patients with stage II colorectal cancer.
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    Tissue microarray
    Gastric cancer (GC) is the leading cause of death worldwide and the prognosis remains poor. Proliferation and apoptosis of cancer cells are regulated by microRNAs (miRNAs). We herein intended to explore the interaction of miR-21 and PTEN in GC. miR-21 inhibitor or negative control was transfected into GC cells MGC-803 followed by analysis of miR-21 and PTEN level by RT-qPCR, PTEN protein level by western blot and cell growth by MTT and Hoechest-33342 staining. Treatment with miR-21 inhibitor reduced miR-21 expression and increased PTEN protein expression. miR-21 was negatively associated with PTEN level. Moreover, downregulation of miR-21 decreased cell proliferation and promoted apoptosis. In conclusion, miR-21 stimulates the malignant phenotypes of GC cells by negatively regulating PTEN expression, providing novel insight into the pathogenesis of gastric cancer.
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    Phosphatase and tensin homolog deleted on chromosome ten(PTEN),one of the mostly investigated tumor suppressor genes,has a close correlation with tumorigenesis.The activation of PI3K-AKT pathway caused by abnormal PTEN is one of the major mechanisms underlying tumor occurrence.Therefore,PTEN regulation is important for uncovering new mechanisms of tumor occurrence and establishing novel therapeutic strategies.The cellular PTEN regulations including transcriptional regulation,post-transcriptional modulation,post-translation modification and protein-protein interaction are reviewed in this paper.
    Tensin
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    The expression pattern of tumor suppressor gene phosphatase and tensin homolog deleted on chromosome ten (PTEN) and phosphatase and tensin homolog deleted on chromosome ten/phosphatidylinositol3-kinase/protein kinase B (PTEN/PI3K/AKT) cell signaling pathway in renal cell carcinoma (RCC) were investigated in children. A total of 5 cases of RCC (observation group) in children and 10 cases of benign kidney tumor (control group) diagnosed by pathological examinations were included to obtain tumor samples. Expression of PTEN mRNA was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The protein expression of PTEN, PI3K and AKT was detected by western blotting; relationships between the expression level of PTEN mRNA and the clinical features of RCC were analyzed. It turned out that expression level of PTEN mRNA in the observation group was significantly lower than that in the control group. The protein expression levels of PTEN, PI3K and AKT were significantly lower in the observation group than in the control group (P<0.05). The expression level of PTEN mRNA decreased with the increased clinical stage of RCC (P<0.05), and was not related to sex, age and maximum tumor diame-ter (P>0.05). The results showed that downregulation of the tumor suppressor gene PTEN expression and the inhibition of PTEN/PI3K/AKT cell signaling pathway may be involved in the occurrence and development of RCC in children.
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    PTEN(Phosphatase and Tensin Homology deleted from Chromosome ten),a putative antioncogene,encodes a PTEN protein that has a dual specificity phosphatase activity with both protein phosphatase and lipid phosphatase,which regulates a variety of molecules through inhibiting the PI3K/Akt signaling pathway.Recently,some scholars dedicate to the modulation of PTEN,which demonstrates that PTEN can be regulated by multiple factors at the level of gene and protein.This review briefly summarizes up-to-date information about the modulation of PTEN and its mechanisms.
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    AbstractThe purpose of this study was to investigate the potential of the blood levels of MIR-21 and PTEN as novel biomarkers for oral squamous cell carcinoma (OSCC). We initially detected MIR-21 and PTEN using real-time RT-PCR from 90 blood samples and then compared their results with expression in cancer tissues from 10 OSCC patients. Finally, we examined the relationship between these markers and clinical parameters. Blood MIR-21 and PTEN had significant diagnostic value for OSCC and, to an extent, correlated with the expression level of tumour MIR-21 and PTEN. In addition, they were associated with differentiation and nodal status. Thus circulating MIR-21 and PTEN might represent new complementary tumour markers for OSCC.KeywordsCirculating biomarkersMIR-21OSCCPTEN
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    Objective To investigate whether the expression of phosphatase and tensin homolog deleted on chromosome ten( PTEN) is involved in the initiation and progression of non-smallcell lung carcinoma( NSCLC). Methods The expression of PTEN was detected in 45 paired NSCLC tumor and adjacent normal tissues by immunohistochemistry. Results The positive expression rates of PTEN in NSCLC tumor and normal tissues were 31. 1% and 66. 7% respectively,the difference was statistically significant( P = 0. 001). PTEN expressions correlated with the differentiation of the tumor( P = 0. 000). Conclusion Lack of PTEN expression may be involved in the initiation and progression of NSCLC.
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