• Journal of Microbiology and Biotechnology
• /
• v.17 no.4
• /
• pp.579-585
• /
• 2007

Formation of inclusion bodies is usually observed when foreign proteins are overexpressed in E. coli. The formation of inclusion bodies might be prevented by lowering the rate of protein synthesis, and appropriate regulation of the protein expression rate may lead to the soluble expression. In this study, human growth hormone (rhGH) was expressed in a soluble form by slowing down the protein synthesis rate, which was controlled in the transcriptional and translational levels. The transcriptional level was controlled by the regulation of the amount of RNA polymerase specific to the promoter in front of the rhGH gene. For lowering the rate of translation, the T7 transcription terminator-deleted vector was used to synthesize the longer mRNA of the target gene because the longer mRNA is expected to reduce the availability of tree ribosomes. In both methods, the percentage of soluble expression increased when the expression rate slowed down, and more than 93% of rhGH expressed was a soluble form in the T7 transcription terminator-deleted expression system.

• Journal of Life Science
• /
• v.22 no.8
• /
• pp.1018-1023
• /
• 2012

Snail is a zinc finger transcription factor that induces epithelial-to-mesenchymal transition (EMT), which promotes tumor invasion and metastasis by repressing E-cadherin expression. In addition, Snail restricts the cellular apoptotic response to apoptotic stimuli or survival factor withdrawal; however, its molecular mechanism remains largely unknown. In this study, we have investigated the mechanism underlying Snail-mediated chemoresistance to 5-fluorouracil (5-FU), one of the most widely used anti-cancer drugs. When Snail was overexpressed by doxycycline (DOX) in MCF-7 #5 cells, it inhibited 5-FU-induced apoptotic cell death and switched the cell death mode to necrosis. Snail expression, either by DOX treatment in MCF-7 #5 cells or by the transfection of Snail expression vectors pCR3.1-Snail-Flg, phosphorylation-resistant pCR3.1-S104, and 107A Snail-Flg in MCF-7 cells specifically induced PTEN down-regulation/inactivation and Akt/PKB activation, without affecting ERK1/2 activity. In addition, Snail prominently suppressed 5-FU-induced increases in p53 levels. These findings demonstrate that Snail switches 5-FU-induced apoptosis to necrosis through the activation of Akt/PKB and the down-regulation of p53 levels.

• Biomedical Science Letters
• /
• v.13 no.3
• /
• pp.239-244
• /
• 2007

Hoxc8 is one of the homeotic developmental control genes regulating the expression of many downstream target genes, through which animal body pattern is established during embryonic development. In previous proteomics analysis, proliferating cell nuclear antigen (PCNA) which is also known as cyclin, has been implied to be regulated by Hoxc8 in F9 murine embryonic teratocarcinoma cell. When the 5' upstream region of PCNA was analyzed, it turned out to contain 20 Hox core binding sites (ATTA) in about 1.17 kbp (kilo base pairs) region ($-520{\sim}-1690$). In order to test whether this region is responsible for Hoxc8 regulation, the upstream 2.3 kbp fragment of PCNA was amplified through PCR and then cloned into the pGL3 basic vector containing a luciferase gene as a reporter. When the luciferase activity was measured in the presence of effector plasmid (pcDNA : c8) expressing murine Hoxc8, the PCNA promoter driven reporter activity was reduced. To confirm whether this reduction is due to the Hoxc8 protein, the siRNA against Hoxc8 (5'-GUA UCA GAC CUU GGA ACU A-3' and 5'-UAG UUC CAA GGU CUG AUA C-3') was prepared. Interestingly enough, siRNA treatment up regulated the luciferase activity which was down regulated by Hoxc8, indicating that Hoxc8 indeed regulates the expression of PCNA, in particular, down regulation in NIN3T3 cells. These results altogether indicate that Hoxc8 might orchestrate the pattern formation by regulating PCNA which is one of the important proteins involved in several processes such as DNA replication and methylation, chromatin remodeling, cell cycle regulation, differentiation, as well as programmed cell death.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.10
• /
• pp.4947-4951
• /
• 2012

Objective: Lung cancer is a deadly cancer, whose kills more people worldwide than any other malignancy. SLUG (SNAI2, Snail2) is involved in the epithelial mesenchymal transition in physiological and in pathological contexts and is implicated in the development and progression of lung cancer. Methods: We constructed a lentivirus vector with SLUG shRNA (LV-shSLUG). LV-shSLUG and a control lentivirus were infected into the non-small cell lung cancer cell A549 and real-time PCR, Western blot and IHC were applied to assess expression of the SLUG gene. Cell proliferation and migration were detected using MTT and clony formation methods. Results: Real-time PCR, Western Blot and IHC results confirmed down-regulation of SLUG expression by its shRNA by about 80%~90% at both the mRNA and protein levels. Knockdown of SLUG significantly suppressed lung cancer cell proliferation. Furthermore, knockdown of SLUG significantly inhibited lung cancer cell invasion and metastasis. Finally, knockdown of SLUG induced the down-regulation of Bcl-2 and up-regulation of E-cadherin. Conclusion: These results indicate that SLUG is a newly identified gene associated with lung cancer growth and metastasis. SLUG may serve as a new therapeutic target for the treatment of lung cancer in the future.

• Korean Journal of Microbiology
• /
• v.51 no.4
• /
• pp.319-328
• /
• 2015

The $sdu1^+$ gene encodes Sdu1, a PPPDE superfamily member of deubiquitinating enzymes (DUBs) in Schizosaccharomyces pombe. Sdu1 was previously shown to contain an actual ubiquitin C-terminal hydrolase (UCH) activity using the recombinant plasmid pYSTP which harbors the $sdu1^+$ gene. This work was designed to assess a thermotolerant role of Sdu1 against high incubation temperatures. In the temperature-shift experiments, the S. pombe cells harboring pYSTP grew much better after the shifts to $37^{\circ}C$ and $42^{\circ}C$, when compared with the vector control cells. After being shifted to $37^{\circ}C$ and $42^{\circ}C$ for 6 h, the S. pombe cells harboring pYSTP contained lower reactive oxygen species (ROS) levels, compared with the vector control cells. The nitric oxide (NO) levels of the S. pombe cells harboring pYSTP were slightly lower than those of the vector control cells in the absence or presence of the temperature shifting. The total glutathione (GSH) levels of the S. pombe cells harboring pYSTP were significantly higher than those of the vector control cells. Total superoxide dismutase (SOD) and GSH peroxidase activities were also higher in the S. pombe cells harboring pYSTP after the temperature shifts than in the vector control cells. In brief, the S. pombe Sdu1 plays a thermotolerant role against high incubation temperature through the down-regulation of ROS and NO and the up-regulation of total GSH content, total SOD and GSH peroxidase activities.

• Journal of Life Science
• /
• v.17 no.4 s.84
• /
• pp.552-560
• /
• 2007

Histone deacetylase (HDAC) is overexpressed in a variety of cancers and is closely correlated with oncogenic factors. HDAC inhibitors such as trichostatin A(TSA) and sodium butyrate (Na-B) have been shown to induce apoptosis in vitro and in vivo in many cancer cells. The anti-apoptotic Bcl-2 protein has the remarkable ability to prevent cell death and Bcl-2 overexpression has been reported to protect against cell death. We previously reported that the apoptotic cell death of human leukemic U937 cells by TSA and Na-B treatment was associated with the down-regulation of Bcl-2 expression and activation of caspases. In the present study, we investigated the effects of Bcl-2 overexpression on the growth inhibition, cell cycle arrest and apoptosis induced by TSA and Na-B in U937 cells. TSA-induced growth inhibition, cell cycle arrest and apoptosis were significantly attenuated in Bcl-2 overexpressing U937/Bcl-2 cells however Na-B did not affected. Induction of apoptosis by TSA was accompanied by down-regulation of Bcl-2 expression, activation of caspase-3, -8 and -9, and degradation of DNA fragmentation factor/inhibitor of caspase-activated DNase, which was blocked by the overexpression of Bcl-2. Collectively, these findings suggest that ectopic expression of Bcl-2 appeared to inhibit TSA-induced apoptosis by interfering with inhibition of Bcl-2 and caspase activation.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.4
• /
• pp.1425-1430
• /
• 2012

Cyclin L2 is a novel member of the cyclin family, recently implicated in the regulation of cell cycle progression and/or transcriptional regulation. The present study was undertaken to investigate the effects of overexpression on tumor cell growth and chemosensitivity in human gastric cells in vitro. Cyclin L2 was transfected into human gastric cancer cell line BCG823 and expressed with a mammalian expression vector pcDNA3.1. The effects and mechanisms of cyclin L2 on cell growth, cell cycling and apoptosis were studied. Compared to control vectors, overexpression of cyclin L2 inhibited the growth of BCG823 cells and enhance their chemosensitivity to fluorouracil, docetaxel and cisplatin. The anti-proliferative effects of cyclin L2 could be due to G0/G1 arrest and apoptosis. Cyclin L2 induced G0/G1 arrest and apoptosis involved upregulation of caspase-3 and down regulation Bcl-2 and survivin. The results indicated that overexpression of cyclin L2 protein may promote efficient growth inhibition and enhance chemosensitivity to chemotherapeutic agents in human gastric cancer cells by inducing G0/G1 cell cycle arrest and apoptosis.

• Journal of Life Science
• /
• v.25 no.2
• /
• pp.223-230
• /
• 2015

Regulator of calcineurin 1 (RCAN1) is an endogenous calcineurin inhibitor that plays an important role in the pathogenesis of diseases related to the calcineurin-NFATc1 signaling pathway. The RCAN1-4 isoform is subject to NFATc1-dependent regulation. During receptor activator of nuclear factor kappa-B ligand (RANKL)-stimulated osteoclastogenesis, the calcineurin-NFATc1 pathway is critical. Because there is little information available on the role of RCAN1 in osteoclast differentiation, this study investigated whether changes in RCAN1 expression are related to the calcineurin-NFATc1 pathway and osteoclast differentiation. Mouse bone marrow monocytes (BMMs) were treated with 50 ng/ml of RANKL and M-CSF. Expression levels of NFATc1, calcineurin, and RCAN1 isoforms were determined using RT-PCR and Western blotting. Osteoclast differentiation was examined using tartrate-resistent acid phosphatase (TRAP) staining. To evaluate the effect of RCAN1 overexpression on osteoclastogenesis, cells were transfected with a mouse RCAN1-4 cDNA plasmid. After RANKL stimulation of BMMs, expression of NFATc1 and RCAN1 was increased at the mRNA and protein level, while calcineurin expression was unchanged. When the RCAN1-4 gene construct was transfected, the expression of RCAN1 protein was not increased despite several-fold increases in RCAN1-4 mRNA expression. Regardless of RANKL stimulation, over-expression of RCAN1-4 tended to reduce NFATc1 expression and knock-down of RCAN1 increase it. While BMMs transfected with the RCAN1-4 vector were differentiated into distinct osteoclasts, their phenotypes did not vary from those of mock controls. These results suggest that RCAN1 has a limited effect on the calcineurin-NFATc1 pathway during RANKL-stimulated osteoclast differentiation.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.2
• /
• pp.795-799
• /
• 2013

Ku70/80 heterodimer is a central element in the nonhomologous end joining (NHEJ) DNA repair pathway, Ku80 playing a key role in regulating the multiple functions of Ku proteins. It has been found that the Ku80 protein located at telomeres is a major contributor to radiosensitivity in some telomerase positive human cancer cells. However, in ALT human osteosarcoma cells, the precise function in radiosensitivity and telomere maintenance is still unknown. The aim of this study was to investigate the effects of Ku80 depletion in the U2OS ALT cell line cell line. Suppression of Ku80 expression was performed using a vector-based shRNA and stable Ku80 knockdown in cells was verified by Western blotting. U2OS cells treated with shRNA-Ku80 showed lower radiobiological parameters (D0, Dq and SF2) in clonogenic assays. Furthermore, shRNA-Ku80 vector transfected cells displayed shortening of the telomere length and showed less expression of TRF2 protein. These results demonstrated that down-regulation of Ku80 can sensitize ALT cells U2OS to radiation, and this radiosensitization is related to telomere length shortening.

• The Plant Pathology Journal
• /
• v.36 no.3
• /
• pp.280-288
• /
• 2020

RNA interference (RNAi) has attracted attention as a promising approach to control plant viruses in their insect vectors. In the present study, to suppress replication of the rice stripe virus (RSV) in its vector, Laodelphax striatellus, using RNAi, dsRNAs against L. striatellus genes that are strongly upregulated upon RSV infection were delivered through a rice leaf-mediated method. RNAi-based silencing of peroxiredoxin, cathepsin B, and cytochrome P450 resulted in significant down regulation of the NS3 gene of RSV, achieving a transcriptional reduction greater than 73.6% at a concentration of 100 ng/μl and, possibly compromising viral replication. L. striatellus genes might play crucial roles in the transmission of RSV; transcriptional silencing of these genes could suppress viral replication in L. striatellus. These results suggest effective RNAi-based approaches for controlling RSV and provide insight into RSV-L. striatellus interactions.