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ABSTRACT: PurposeStat6 signaling is active in cancer cells and IL-4-induced Stat6 activities or Stat6 activational phenotypes vary among cancer
cells. This study aimed at investigating possible mechanism(s) involved in the formation of varying Stat6 activities/phenotypes.
MethodsStat6 regulatory genes, SOCS-1 and SHP-1, were examined for mRNA expression using RT-PCR, and their promoter DNA methylation
was assayed by methylation-specific PCR in Stat6-phenotyped colon cancer cell lines. DNA methylation was then verified by
sequencing. RT-PCR assay and Western blotting were used to detect the expression of SOCS-1 and SHP-1 after demethylation using
5-aza-2′-deoxycytidine.
ResultsCompared with Stat6null Caco-2 cells, Stat6high HT-29 cells showed decreased constitutive expression of SOCS-1 and SHP-1, which correlated with DNA hypermethylation in these
genes’ promoters. Interestingly, demethylation in HT-29 cells recovered the constitutive expression of SOCS-1 and SHP-1.
ConclusionsThese findings suggest that DNA methylation controls the constitutive expression of negative Stat6 regulatory genes, which
may affect Stat6 activities.
Journal of Cancer Research and Clinical Oncology 04/2012; 135(12):1791-1798. · 2.56 Impact Factor
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ABSTRACT: Interleukin-4 (IL-4)-induced Stat6 activities (phenotypes) vary among human cancer cells, of which the HT-29 cell line carries an active Stat6(high) phenotype, while Caco-2 carries a defective Stat6(null) phenotype, respectively. Cancer cells with Stat6(high) show resistance to apoptosis and exaggerated metastasis, suggesting the clinical significance of Stat6 phenotypes. We previously showed that Stat6(high) HT-29 cells exhibited low constitutive expression of Stat6-negative regulators SOCS-1 and SHP-1 because of gene hypermethylation. This study further examined the constitutive expression of other closely related SOCS family numbers including SOCS-3, SOCS-5, SOCS-7, and CISH using RT-PCR. Similar to SOCS-1 and SHP-1, Stat6(high) HT-29 cells expressed low constitutive mRNA of SOCS-3, SOCS-7, and CISH than Stat6(null) Caco-2 cells. Interestingly, DNA demethylation using 5-aza-2'-deoxycytidine in HT-29 cells up-regulated mRNA expression of the above genes, indicating a hypermethylation status, which was confirmed by methylation-specific sequencing in selected SOCS-3 gene. Furthermore, defective Stat6(null) Caco-2 exhibited impaired phosphorylation of Stat6 after IL-4 stimulation by flow cytometry, in keeping with the notion of an over-performed negative regulation. The findings that IL-4/Stat6 phenotypes show differential expression of multiple negative regulators suggest a model that a collective force of powerful negative regulators, directly and indirectly, acts on Stat6 activation, which may result in differential Stat6 phenotypes.
Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 11/2009; 29(12):809-16. · 1.63 Impact Factor
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ABSTRACT: PurposeTo investigate potential differences in the expression of Stat6 regulatory genes that may influence IL-4/Stat6 activities
(phenotypes) in colon cancer cells.
MethodsRT-PCR method was employed to examine the constitutive mRNA expression of Stat6 negative regulators SOCS-1 and SHP-1, and positive regulator PP2A in colon cancer cell lines HT-29 and Caco-2. Stat6 protein expression and nuclear phosphorylation were detected using Western
blotting.
ResultsCaco-2 cells carrying inactive Stat6null phenotype showed normal constitutive expression of Stat6 but decreased phosphorylation of nuclear Stat6 compared with HT-29
cells carrying active Stat6high phenotype. Stat6null Caco-2 cells expressed increased levels of mRNA and protein of SOCS-1 and SHP-1, and decreased mRNA expression of PPP2CA and PPP2CB, encoding two critical subunits of PP2A.
ConclusionsConstitutively increased expression of Stat6 negative regulators SOCS-1 and SHP-1, together with decreased expression of positive regulator PP2A, may play a role in forming the inactive Stat6null phenotype in colon cancer cells.
Journal of Cancer Research and Clinical Oncology 12/2008; 135(1):131-140. · 2.56 Impact Factor
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ABSTRACT: IL-4-induced Stat6 signaling is active in a variety of cell types and plays a role in cell proliferation/growth and resistance to apoptosis. Using EMSA, we identified differential IL-4/Stat6 activities in colorectal cancer cell lines, HT-29 being active Stat6(high) phenotype and Caco-2 being defective Stat6(null) phenotype, respectively. Active Stat6(high) HT-29 cells exhibited resistance to apoptosis by flowcytometry and aggressive metastasis by Transwell assay compared with defective Stat6(null) Caco-2 cells. Comparing one another using RT-PCR, Stat6(high) HT-29 cells expressed more mRNA of anti-apoptotic and pro-metastatic genes Survivin, MDM2, and TMPRSS4, while Stat6(null) Caco-2 cells expressed more mRNA of pro-apoptotic and anti-metastatic genes BAX, CAV1, and P53, respectively. This is the first study describing correlations of IL-4/Stat6 activities with apoptosis and metastasis in colon cancer. These findings, together with the observation of constitutive Stat6 activation in many human malignancies, suggest that Stat6 activities could be a biomarker for cancer cell's invasive/metastatic capability.
Biochemical and Biophysical Research Communications 06/2008; 369(2):554-60. · 2.48 Impact Factor
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Wen Jie Zhang,
Ben Hui Li,
Xian Zi Yang,
Pin Dong Li,
Qin Yuan, Xiao Hong Liu,
Shuang Bing Xu,
Yan Zhang,
Jia Yuan,
Glenn S Gerhard,
Kathryn K Masker,
Cheng Dong,
Walter A Koltun,
Michael J Chorney
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ABSTRACT: IL-4-induced Stat6 signaling is active in a variety of cell types, including immune cells and cancer cells, and plays an important role in the regulation of gene expression. Using EMSA gel shift assay and an antibody to Stat6, we phenotyped two breast cancer cell lines, ZR-75-1 being active Stat6(high) phenotype and BT-20 being defective Stat6(null) phenotype, respectively. Breast cancer cells carrying Stat6(null) phenotype exhibited increased spontaneous apoptosis compared with those carrying Stat6(high) phenotype. Expression microarray analyses demonstrated that IL-4 upregulated CCL26, SOCS1, CISH, EGLN3, and SIDT1, and downregulated DUSP1, FOS, and FOSB, respectively, in these breast cancer cells. Among those genes, CCL26 and SOCS1 were known genes regulated by IL-4/Stat6 pathway, but CISH, EGLN3, SIDT1, DUSP1, FOS, and FOSB were novel genes demonstrated to be IL-4 responsive for the first time. IL-4 also upregulated 38 genes unique to Stat6(null) BT-20 cells and 23 genes unique to Stat6(high) ZR-75-1 cells, respectively. Furthermore, Stat6(high) and Stat6(null) cells showed very different profiles of constitutively expressed genes relevant to apoptosis and metastasis among others, which serve as a valuable expression database and warrant for detailed studies of IL-4/Stat6 pathway in breast cancer.
Cytokine 05/2008; 42(1):39-47. · 3.02 Impact Factor
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ABSTRACT: A mixed self-assembled monolayers (SAMs) of thioctic acid (T–COOH) and thioctic acid amide (T–NH2) were used to immobilize tyrosinase for fabricating biosensor. The results showed that the mixed SAMs prepared from solution at the ratio of 1:4 provided an excellent microenvironment for enzymatic reaction between tyrosinase and substrate. The biosensor exhibited a fast response and high sensitivity for sensing substrate.
Chinese Chemical Letters.
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ABSTRACT: Rechargeable aqueous lithium ion batteries have been developed by using olivine LiMn0.05Ni0.05Fe0.9PO4 as cathode material, Nasicon LiTi2(PO4)3 as anode material, and saturated Li2SO4 solution as electrolyte. The cycling performance and rate capability of these batteries have been investigated. At a current density of 0.2 mA/cm2, the initial discharge capacity of the battery was approximately 103.9 mAh/g, and the potential plateau was located at 0.92 V. The rate capability of aqueous electrolyte was found to be preferable to that of organic electrolyte. Such inexpensive, secure and high rate rechargeable lithium ion battery should have a potential for use in many applications.
Journal of Power Sources.
