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ABSTRACT: Combination therapy is considered a promising therapeutic modality in enhancing treatment efficacy. The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is almost universally dysregulated in breast cancer, with specific occurrence of PTEN mutations; thus, it has become an attractive target for cancer treatment. However, the use of single targeted therapeutics against the PI3K/AKT pathway has demonstrated only modest clinical benefits. In this study, recombinant adenovirus-mediated gene transfer of PTEN (AD-PTEN) combined with treatment with LY294002 was utilized to evaluate the effects of suppression of breast cancer cell proliferation. Herein, we show that AD-PTEN significantly enhanced the sensitization of breast cancer cells to LY294002. The 50% inhibitory concentration (IC50) values of LY294002 were significantly decreased to a greater extent in cells transfected with combination therapy. In addition, treatment of AD-PTEN-transfected cells with LY294002 resulted in significantly reduced cell viability and invasion ability compared to single LY294002 treatment. Using western blotting, we found that combination treatment resulted in lower levels of phosphorylated AKTSer473 and GSK-3βSer9 than single treatment with LY294002. Furthermore, we showed a significant decrease in nuclear β-catenin, Fra-1, Tcf-4 and c-Myc by combination treatment. Our results indicate that AD-PTEN sensitization of breast cancer to LY294002 is achieved by increased GSK-3β activity, thus resulting in inhibition of the β-catenin signaling pathway.
Oncology Reports 06/2012; 28(3):943-8. · 1.84 Impact Factor
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ABSTRACT: Activation of the AKT (serine-threonine kinase) pathway is a common feature in glioblastoma cells. Downstream factors of the AKT pathway are involved in cell proliferation, apoptosis, cellular migration and angiogenesis. Micro-RNAs (miRNAs) are highly conserved small non-coding RNAs that block targeted mRNA expression at the post-transcriptional level. The aim of this study was to investigate the role of the AKT pathway in regulating miRNA. The changes of miRNA expression profile in human glioblastome U251 cells after AKT small interfering RNA transfection were examined by a microarray, and confirmed by Northern blotting. Down-regulation of AKT expression by siRNA decreased the activity of AKT pathway in U251 cells. Interruption of AKT pathway suppressed the expression of NF-kappaB and c-Myc, furthermore, the expression of a set of miRNAs was also changed after AKT siRNA transfection. There are putative binding sites of NF-kappaB and c-Myc in the promoters of several up-regulated miRNAs, indicating these transcription factors may also be involved in the regulation of miRNA expression, thus affecting the activity of AKT pathway in tumorigenesis. We provide new components of the regulatory function of AKT pathway to better understand the regulatory network mediated by downstream transcription factors. The understanding of the regulatory function of AKT pathway is crucial in tailored therapy of gliomas.
International Journal of Oncology 03/2010; 36(3):665-72. · 2.40 Impact Factor
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Xuan Zhou,
Yu Ren,
Lynette Moore, Mei Mei,
Yongping You,
Peng Xu,
Baoli Wang,
Guangxiu Wang,
Zhifan Jia,
Peiyu Pu,
Wei Zhang,
Chunsheng Kang
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ABSTRACT: 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 wild-type) 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.
Laboratory Investigation 02/2010; 90(2):144-55. · 3.64 Impact Factor
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ABSTRACT: The successful of anti-cancer treatment are often limited by the development of drug resistance. Recent work has highlighted the involvement of non-coding RNAs, microRNAs(miRNAs) in cancer development, and their possible involvement in the evolution of drug resistance has been proposed. In this study, we combine taxol chemotherapy and miR-21 inhibitor treatment via polyamidoamine (PAMAM) dendrimers vector to evaluate the effects of combination therapy on suppression of breast cancer cells. The 50% inhibitory concentration (IC50) values for taxol were significantly decreased to a greater extent in the cells transfected with miR-21 inhibitor compared with cells treated with taxol alone. Taxol treatment also increased the percentage of apoptotic breast cancer cells in miR-21 inhibitor transfected cells compared with control cells. Furthermore, treatment of the miR-21 inhibitor-transfected cells with the anti-cancer drugs taxol resulted in significantly reduced cell viability and invasiveness compared with control cells. These results indicated that the miR-21 plays an important role in the resistance of breast carcinoma cells to chemotherapeutic drugs. Therefore, miR-21 inhibitor gene therapy combined with taxol chemotherapy might represent a promising novel therapeutic approach for the treatment of breast malignancies.
Technology in cancer research & treatment 02/2010; 9(1):77-86. · 2.02 Impact Factor
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ABSTRACT: Substantial data indicate that the oncogene microRNA 21 (miR-21) is significantly elevated in glioblastoma multiforme (GBM) and regulates multiple genes associated with cancer cell proliferation, apoptosis, and invasiveness. Thus, miR-21 can theoretically become a target to enhance the chemotherapeutic effect in cancer therapy. So far, the effect of downregulating miR-21 to enhance the chemotherapeutic effect to taxol has not been studied in human GBM.
Human glioblastoma U251 (PTEN-mutant) and LN229 (PTEN wild-type) cells were treated with taxol and the miR-21 inhibitor (in a poly (amidoamine) (PAMAM) dendrimer), alone or in combination. The 50% inhibitory concentration and cell viability were determined by the MTT assay. The mechanism between the miR-21 inhibitor and the anticancer drug taxol was analyzed using the Zheng-Jun Jin method. Annexin V/PI staining was performed, and apoptosis and the cell cycle were evaluated by flow cytometry analysis. Expression of miR-21 was investigated by RT-PCR, and western blotting was performed to evaluate malignancy related protein alteration.
IC(50) values were dramatically decreased in cells treated with miR-21 inhibitor combine with taxol, to a greater extent than those treated with taxol alone. Furthermore, the miR-21 inhibitor significantly enhanced apoptosis in both U251 cells and LN229 cells, and cell invasiveness was obviously weakened. Interestingly, the above data suggested that in both the PTEN mutant and the wild-type GBM cells, miR-21 blockage increased the chemosensitivity to taxol. It is worth noting that the miR-21 inhibitor additively interacted with taxol on U251cells and synergistically on LN229 cells. Thus, the miR-21 inhibitor might interrupt the activity of EGFR pathways, independently of PTEN status. Meanwhile, the expression of STAT3 and p-STAT3 decreased to relatively low levels after miR-21 inhibitor and taxol treatment. The data strongly suggested that a regulatory loop between miR-21 and STAT3 might provide an insight into the mechanism of modulating EGFR/STAT3 signaling.
Taken together, the miR-21 inhibitor could enhance the chemo-sensitivity of human glioblastoma cells to taxol. A combination of miR-21 inhibitor and taxol could be an effective therapeutic strategy for controlling the growth of GBM by inhibiting STAT3 expression and phosphorylation.
BMC Cancer 01/2010; 10:27. · 3.01 Impact Factor
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ABSTRACT: Stromal smooth muscle cells (SMCs) play an important role in the pathogenesis and clinical symptom of benign prostatic hyperplasia. We had reported that estrogen enhances the phenotype of SMC in cultured prostate stromal cells (PRSCs). Here we further investigate the mechanism by which estrogen affects the differentiation of PRSCs.
Primary cultured PRSCs were stimulated with E2 or BSA-E2. The mRNA level of SMC-specific genes, smoothelin, and SM-MHC were measured by qRT-PCR. The SM-MHC protein was measured by Western blot. The mRNA and protein levels of TGF-beta1 were measured by qRT-PCR and ELISA. The MAPK inhibitor PD98059, the estrogen receptor antagonist ICI182,780 and neutralizing antibody to TGF-beta1 were used to reveal the mechanism of estrogen effect.
E2 and BSA-E2 significantly up-regulate the expression of SMC-specific genes in PRSCs. Both forms of estrogen could increase the expression of TGF-beta1, which can be blocked by pre-treating with PD98059. Moreover, PD98059 and TGF-beta1 neutralizing antibody could abrogate the effect of BSA-E2 on cell differentiation. However, they could only inhibit part of E2-induced SMC phenotype enhancement. ICI182,780 could partially suppress the pro-differentiation effect of E2 but had no influence on the effect of BSA-E2. Combined treatment with ICI182,780 and PD98059 can completely abrogate the effect of E2.
Estrogen could promote the expression of TGF-beta1 in PRSCs through nongenomic activation of MAPK pathway, and in turn enhance the SMC phenotype. Besides for this nongenomic effect, estrogen can also enhance the SMC phenotype through classical genomic action.
The Prostate 10/2009; 70(3):317-32. · 3.48 Impact Factor
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ABSTRACT: A specific micro-RNA (miRNA), micro-RNA 21 (miR-21), is strongly overexpressed in breast cancer cells. Antisense inhibition of miRNA function, an important tool for uncovering miRNA biology, which is often used to knockdown miRNA, can cause a notable inhibition of cell growth. In this study, 5-fluorouracil (5-FU) was conjugated to polyamidoamine dendrimers via direct encapsulation; this method was then combined with antisense micro-RNA 21 (as-miR-21) strategies to evaluate the effects of the growth suppression of breast cancer cells. Our results show that as-miR-21 strategies significantly improved the chemosensitivity of free 5-FU on breast cancer cells (MCF-7). In addition, not only could as-miR-21 effectively increase the apoptotic cell numbers but it could also bring down the migration ability of MCF-7 cells. Our results provide invaluable information for the future design of drug–polymer complexes for multimodal cancer treatments. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Journal of Applied Polymer Science 08/2009; 114(6):3760 - 3766. · 1.29 Impact Factor
