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ABSTRACT: Post-translational modification of peptidyl cis/trans prolyl isomerase Pin1 is crucial in regulation of gene stability. Pin1 phosphorylation at Ser(16) has been regarded as a marker for Pin1 isomerase activity and introduction of phosphorylation on Ser/Thr-Pro of substrate proteins is prerequisite for its binding activity with Pin1 and subsequent isomerization. Here, we found that 90 kDa ribosomal protein S6 kinase 2 (RSK2) could form a physical complex with Pin1, leading to phosphorylation of Pin1 at Ser(16) ex vivo and in vitro respectively. Intriguingly, Pin1(+/+) mouse embryonic fibroblasts (MEFs) exhibited significantly an increase in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced RSK2 phosphorylation with a marginal Pin1 phosphorylation compared with Pin1(-/-) MEFs. Moreover, TPA-induced Ser(16) Pin1 phosphorylation as well as RSK2 phosphorylation was considerably profound in RSK(+/+) MEFs but not in RSK(-/-) MEFs. Consequently, knockdown of Pin1 using shRNA-Pin1 suppressed TPA-induced cell transformation in JB6 CI41 cells. Overall, these results indicate that Pin1 plays a critical role in TPA-induced tumorigenesis plausibly via physical interaction with RSK2 and reciprocal phosphorylation, therefore suggesting a potential therapeutic target for cancer treatment.
Molecular and Cellular Biochemistry 05/2012; 367(1-2):85-92. · 2.06 Impact Factor
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ABSTRACT: Juglone (5-hydroxy-1,4-naphthalenedione) from black walnut trees induces apoptosis and inhibits proliferation of various malignant cells. Here, we investigated whether juglone affects 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation through the phosphoinositol 3-kinase (PI3K) pathway. The results showed that TPA- and endothelial growth factor (EGF)-induced anchorage-independent colony formation were suppressed in a dose-dependent manner by treatment of JB6 CI41 mouse skin epidermal cells with juglone (2.5 and 5 µM). We demonstrated that juglone suppressed PI3K activity via direct binding to PI3K by sepharose 4B pull-down assay and western blot analysis. Juglone significantly suppressed TPA-induced protein kinase B (AKT) and c-Jun phosphorylation and c-fos activation, but not mitogen-activated protein-kinase kinase (MEK), extracellular signaling-regulated kinase (ERK) or 90 kDa ribosomal protein S6 kinase (RSK) phosphorylation. Juglone significantly blocked activator protein-1 (AP-1) and cyclooxygenase-2 (COX-2) activation more than the PI3K inhibitors LY294002 and wortmannin. Overall, these results showed the anticancer efficacy of juglone targeting PI3K to prevent TPA-induced tumorigenesis.
International Journal of Molecular Medicine 04/2012; 30(1):8-14. · 1.98 Impact Factor
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ABSTRACT: To examine whether exogenous pulmonary surfactants (exPS) substitute for or merely supplement endogenous pulmonary surfactants (enPS) by looking at sequential changes in the surfactant proteins (SP) SP-A and SP-D in alveolar pools.
Fourteen preterm infants with RDS treated with an artificial surfactant were compared to five normal-term infants without RDS who were treated with artificial ventilation at birth.
Immediately after birth, SP-A and SP-D were essentially absent in the alveolar pools of the RDS group, but were present at normal levels in the controls. Treatment with exPS apparently stimulated enPS production.
In infants who responded well to exPS therapy, the SP concentration reached essentially normal levels within 48-72 h after birth.
Journal of Perinatal Medicine 07/2009; 37(5):561-4. · 1.70 Impact Factor
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ABSTRACT: Pulmonary damage resulting from lipid peroxidation is a principal effect of paraquat intoxication. The host-defense functions of surfactant are known to be mediated by the surfactant proteins A and D (SP-A and SP-D, respectively). The primary objective of this study was to evaluate the variations over time in levels of surfactant protein and lipid peroxidation (LPO) in lung tissue following free-radical-induced injury.
42 adult, male, Sprague-Dawley rats were administered intraperitoneal injections of paraquat (35 mg/kg body weight). SP-A and SP-D levels were determined via Western blot. LPO in the left lung homogenate was measured via analyses of the levels of thiobarbituric acid-reactive substances.
LPO levels peaked at 6 hours, with no associated histological changes. SP-D levels increased until hour 12 and declined until hour 48; SP-D levels subsequently began to increase again, peaking at hour 72. SP-A levels peaked at hour 6, declining thereafter.
We suggest that in the early phase of paraquat injury, SP-D levels reflect alveolar damage and that de novo synthesis of SP-D takes 72 hours. Levels of SP-A, on the other hand, reflect abnormalities in the surfactant system in the late stage of paraquat intoxication. Surfactant proteins may play a role in protecting the lungs from reactive oxygen injury. A time-dependent variation has been observed in the levels of surfactant proteins A and D following paraquat injury, and it has been suggested that these proteins play a role in the protection of lung tissue against ROS-induced injuries.
The Korean Journal of Internal Medicine 07/2007; 22(2):67-72.
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Sang-Han Lee,
Tae-Jung Kim,
Ho-Young Kim,
Jin-Gook Kim,
Mi-Kyoung Park, Kee-Min Woo,
Sung-Ho Kim,
Kyu-Yoon Hwang,
Hae-Seon Nam,
Young-Ki Min,
Man-Hee Cho
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ABSTRACT: The fragile histidine triad (FHIT) gene located in human chromosome 3p14.2 is a candidate tumor suppressor gene that has a diadenosine triphosphate (Ap3A) hydrolase activity, but its role in carcinogenesis remains uncertain. To investigate the role of FHIT in normal cells, specific polyclonal antibodies to recombinant rat FHIT protein were generated. Immunoblot analysis revealed the 17-kd FHIT protein was most abundantly expressed in kidney and liver, whereas heart, skeletal muscle, and adrenal gland expressed trace amounts. In kidney, immunohistochemical staining was strongly observed in distal convoluted tubule and collecting duct during postnatal growth period. By a nested reverse transcription-PCR analysis of FHIT from 2 human kidney cancer cell lines, four abnormal-sized FHIT transcripts, with deletion and/or insertion, were detected. These were derived from the results of exon skipping, and/or insertion of FHIT intron 5 sequence, or selection of cryptic splice site within the FHIT cDNA sequence 179-180. Taken together, our data indicate that FHIT expression is frequently altered in human kidney cancer cell lines by alternative splicing, and suggest that the FHIT protein may play a pivotal role in regulating intracellular metabolism of the distal convoluted tubule and collecting duct in maturity.
Research communications in molecular pathology and pharmacology 02/2002; 112(1-4):145-57.
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ABSTRACT: Alterations of the FHIT gene occur as frequent events in several human cancers. Replacement of exogenous wild-type FHIT gene has been shown to induce suppression of tumorigenicity of human FHIT-negative cells in nude mice and aberrant FHIT transcripts have been observed in a variety of human solid tumors. In the presence study, we performed a nested reverse transcription-polymerase chain reaction (RT-PCR) analysis to identify aberrant FHIT transcripts in 6 gastric cancer cell lines. In addition to the wild-type FHIT transcript, small-sized transcripts with various number and lengths were observed in all of the cell lines examined. Sequence analysis confirmed that different types of truncated transcripts included exonic deletions, insertions of intron 5 sequences between exons, and combinations of both. Most of these transcripts lacked exon 5 in which translation initiation codon is located. Aberrant transcripts with partial exonic deletions, resulting from activation of cryptic splice sites, were also observed in 5 cell lines. Additionally, multi-step splice patterns, indicative of additional downstream processing, were observed in several cancer lines. Our results suggest that the aberrant FHIT transcripts in gastric cancer cell lines resulted from faulty splicing, including exon skipping, selection of cryptic splice site and additional downstream splice processing.
Research communications in molecular pathology and pharmacology 02/2002; 112(1-4):39-49.
