Akt2 and nucleophosmin/B23 function as an oncogenic unit in human lung cancer cells.
ABSTRACT The signaling network of protein kinase B(PKB)/Akt has been implicated in survival of lung cancer cells. However, understanding the relative contribution of the different isoform of Akt network is nontrival. Here, we report that Akt2 is highly expressed in human lung adenocarcinoma cell line A549 cells. Suppression of Akt2 expression in A549 cells results in notable inhibition of cell poliferation, soft agar growth, and invasion, accompanying by a decrease of nucleophosmin/B23 protein. Overexpression of Akt1 restores cancerous growth of A549 cells in B23-knockdown (KD) cells while Akt2 overexpression did not restore proliferating potential in cells with downregulated B23, thus suggesting Akt2 requires B23 to drive proliferation of lung cancer cell. Loss of functional Akt2 and B23 has similar defects on cell proliferation, apoptotic resistance and cell cycle regulation, while loss of Akt1 has less defects on cell proliferation, survival and cell cycle progression in A549 cells. Moreover, overexpression of B23 rescues the proliferative block induced as a consequence of loss of Akt2. Thus our data suggest that Akt2/B23 functions as an oncogenic unit to drive tumorigenesis of A549 lung cancer cells.
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ABSTRACT: Drug resistance and recurrence are the major obstacles to bladder cancer chemotherapy. Our laboratory had reported that nucleophosmin1 was one of the differentially expressed proteins between bladder cancer cell lines PUMC-91 and PUMC-91/1.0ADM based on 2D-PAGE proteomics approaches. In this study, we want to explore the relationship among nucleophosmin1, drug resistance, and recurrence of bladder cancer, using normal bladder epithelia cell line SV-HUC-1, bladder cancer cell lines PUMC-91, PUMC-91 against gradient doses of adriamycin (0.3, 0.6, and 1.0 μg/ml), and bladder cancer tissue samples. The bladder cancer tissue samples were divided into two groups according to the interval of recurrence (<6 months and >2 years). The differences were detected by Western blotting and immunohistochemistry. The protein of nucleophosmin1 was differentially expressed with each other in SV-HUC-1, PUMC-91, PUMC-91/0.3ADM, and PUMC-91/1.0ADM (p < 0.05). Nucleophosmin1 was less expressed in later recurring (>2 years) bladder cancer tissue samples compared with samples that recurred <6 months (p = 0.035). The expression of nucleophosmin1 was independently associated with gradient drug resistance and recurrent frequency of bladder cancer. Nucleophosmin1 was a key regulator in either a drug-resistant bladder cancer or bladder cancer recurrence model. It may be possible to think nucleophosmin1 can provide more helpful information for clinical drug treatment of bladder cancer patients and frequently recurred ones.Clinical and experimental medicine. 06/2014;
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ABSTRACT: To characterize the phenotype of Akt2/low-density-lipoprotein receptor double knockout (Akt2/LDLr dKO) mice with respect to insulin resistance and features of atherosclerotic plaque progression. Metabolic profile and atherosclerotic plaque progression were compared between LDLr KO mice and Akt2/LDLr dKO mice. Total cholesterol, glucose and insulin levels were significantly higher and oral glucose tolerance test was more impaired in Akt2/LDLr dKO mice than in LDLr KO mice. Although atherosclerotic plaques at both the carotid artery and the aortic root of Akt2/LDLr dKO mice were significantly smaller (p<0.05) compared with LDLr KO controls, plaque composition in these mice was more complex, showing 34-50% reduced collagen content (p<0.01), 1.4-fold larger necrotic cores (p<0.05) and 6-fold more TUNEL positive cells (p<0.01). In situ zymography revealed a more than two-fold higher gelatinolytic activity in Akt2/LDLr dKO mice (p<0.05). In vitro analyses showed that deletion of Akt2 caused decreased migration, proliferation and collagen content of vascular smooth muscle cells (VSMCs) and disturbed the balance of metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase (TIMP) mRNA expression in macrophages and VSMCs. Akt2/LDLr dKO mice develop insulin resistance and complex atherosclerotic lesions. These phenotypic characteristics make Akt2/LDLr dKO mice an interesting mouse model to study the effects of insulin resistance on the development and progression of atherosclerosis.Cardiovascular Research 11/2013; · 5.81 Impact Factor
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ABSTRACT: Nucleophosmin (NPM) is a nucleolar phosphoprotein that is involved in many cellular processes and has both oncogenic and growth suppressing activities. NPM is localized primarily in nucleoli but shuttles between the nucleus and the cytoplasm, and sustained cytoplasmic distribution contributes to its tumor promoting activities. Plakoglobin (PG, γ-catenin) is a homolog of β-catenin with dual adhesive and signaling functions. These proteins interact with cadherins and mediate adhesion, while their signaling activities are regulated by association with various intracellular partners. Despite these similarities, β-catenin has a well-defined oncogenic activity, whereas PG acts as a tumor/metastasis suppressor through unknown mechanisms. Comparison of the proteomic profiles of carcinoma cell lines with low- or no PG expression with their PG-expressing transfectants has identified NPM as being upregulated upon PG expression. Here, we examined NPM subcellular distribution and in vitro tumorigenesis/metastasis in the highly invasive and very low PG expressing MDA-MB-231 (MDA-231) breast cancer cells and their transfectants expressing increased PG (MDA-231-PG) or NPM shRNA (MDA-231-NPM-KD) or both (MDA-231-NPM-KD+PG). Increased PG expression increased the levels of nucleolar NPM and coimmunoprecipitation studies showed that NPM interacts with PG. PG expression or NPM knockdown decreased the growth rate of MDA-231 cells substantially and this reduction was decreased further in MDA-231-NPM-KD+PG cells. In in vitro tumorigenesis/metastasis assays, MDA-231-PG cells showed substantially lower and MDA-231-NPM-KD cells substantially higher invasiveness relative to the MDA-231 parental cells, and the co-expression of PG and NPM shRNA led to even further reduction of the invasiveness of MDA-231-PG cells. Furthermore, examination of the levels and localization of PG and NPM in primary biopsies of metastatic infiltrating ductal carcinomas revealed coordinated expression of PG and NPM. Together, the data suggest that PG may regulate NPM subcellular distribution, which may potentially change the function of the NPM protein from oncogenic to tumor suppression.Oncogenesis. 01/2012; 1:e4.