Jin-Ju Park

Secretory leukocyte protease inhibitor is associated with MMP-2 and MMP-9 to promote migration and invasion in SNU638 gastric cancer cells.

Secretory leukocyte protease inhibitor (SLPI) protects tissue from proteases, and promotes cell proliferation and healing during inflammatory response. SLPI is also overexpressed in gastric, lung and ovarian cancers, which accelerates the metastasis of cancer cells. Matrix metalloproteinases-2, -9 (MMP-2 and MMP-9) are overexpressed in high metastatic cancers, and promote the migration of cancer cells through collagen degradation. SLPI and MMP-2, -9 are critical factors in stimulating the metastatic processes but there are no reports of a direct correlation between these molecules. Therefore, this study examined the role of SLPI related to MMP-2 and MMP-9 using two gastric cancer cell lines, such as characterized non-metastatic SNU484 and highly metastatic SNU638 cells. SLPI, MMP-2 and MMP-9 mRNA and protein expression were higher in SNU638 cells than in SNU484 cells. In addition, the rate of cell migration and invasion was higher in the SNU638 cells than in SNU484 cells. Interestingly, after treatment with SLPI, the rate of migration and invasion was higher in the SNU484 cells than in the positive control (PC) SNU484 cells. The rate of migration was also higher in the SNU638 cells after SLPI treatment than in the SNU638 cells (PC) but the invasion rate was not changed. The expression and secretion of MMP-2 and MMP-9 as well the rate of cell migration and invasion were significantly lower in SLPI-siRNA transfected SNU638 cells (si-SLPI/SNU638) but higher in SLPI-treated SNU484 cells (SNU484 + SLPI). Strong Elk-1 phosphorylation was detected in SNU484 + SLPI and SNU638 cells but was barely detectable in SNU484 and si-SLPI/SNU638 cells. These results show that SLPI promotes the metastasis of SNU638 gastric cancer cells by increasing MMP-2 and MMP-9 expression through Elk-1 signaling, indicating its role as a signaling molecule not a protease inhibitor.

Effect of secretory leukocyte protease inhibitor on migration and invasion of human KB oral carcinoma cells

Secretory leukocyte protease inhibitor (SLPI) plays an important role in promoting the invasion and metastasis of a range of cancer cells. However, there are no reports of the expression and function of SLPI in oral carcinoma cells. In this study, the oral carcinoma cell line KB was used to determine whether SLPI affects the proliferation, migration and invasion of oral carcinoma cells. RT-PCR and Western blotting revealed high levels of endogenous SLPI expression in KB cells as well as a strong increase in SLPI secretion after wounding compared to immortalized normal oral keratinocytes (INOK). The wound healing assay revealed more migration of KB cells than INOK cells, and the SLPI treatment increased the migration of KB cells. KB cell proliferation was increased significantly by the SLPI protein but decreased by SLPI-siRNA. SLPI strongly increased the migration and invasion of KB cells. On the other hand, SLPI-siRNA decreased the migration and invasion of KB cells. This suggests that SLPI plays an important role in the metastasis of oral carcinoma cells.

Aging-resistant nanofluids containing covalent functionalized boron nitride nanosheets

Developing a thermally stable nanofluid that can maintain good thermo-conductive and flow performance at moderate or elevated temperatures for prolonged periods of time is a great challenge in heat transfer applications. Here, the thermal conductivity and rheological properties as well as their thermal stability characteristics of a nanofluid containing two-dimensional (2D) hexagonal boron nitride nanosheets (h-BNNSs) in ethylene glycol (EG) are presented, in comparison with those for a graphene oxide (GO) nanofluid as a counterpart. In place of a surfactant, hydroxyl functional groups covalently bound to the BNNS surface provided excellent compatibility and stable dispersion of the particles within EG at temperatures up to 90 °C. Owing to the percolation effect of the 2D sheets, the thermal conductivity of the EG base fluid was significantly enhanced by 80% at 5 vol% of BNNS, superior to that of the GO fluid. Moreover, the BNNS fluids exhibited excellent long-term stability at 90 °C for 5 d without loss of their high thermal conductivity, low viscosity and electrical insulating property, whereas the GO fluids underwent thermal degradation with irreversible particle aggregation and increasing viscosity due to the selective chemical reduction of the surface functional groups (i.e., C-O groups) of the GO.

Induction of secretory leukocyte protease inhibitor (SLPI) in estradiol valerate (EV) induced polycystic ovary

The excessive administration of estradiol valerate induces polycystic ovary syndrome by formation of follicular cysts. Secretory leukocyte protease inhibitor (SLPI) promotes wound healing by decreasing the excessive inflammatory response, stimulating keratinocyte proliferation and increasing collagen deposition through the inhibition of protease activity. In this study, SLPI expression was high in the ovarian stroma, corpus luteum, unilaminar primary follicle, multilaminar primary follicle and granulose layer of the antral follicle in polycystic ovary (PCO) compared to the normal ovary. SLPI was expressed strongly in the theca around the cyst in PCO compared to the mature follicle in the normal ovary. The levels of SLPI mRNA and protein expression were higher in PCO than in the normal ovary, and the level of MMP-2 expression was lower in PCO. These results showed that the formation of a cyst was initiated from a multilaminar primary follicle and SLPI expression was increased depending on the morphological changes in the follicle and ovarian stroma. Therefore, an increase in SLPI may be related to the suppression of tissue disruption, and act as a protease inhibitor in PCO, suggesting that SLPI increases independently of the estrogen concentration in pathological tissues.

Fabrication of High Density Y2O3 Ceramics by Magnetic Pulsed Compaction

Highly dense Y2O3 ceramics have been fabricated by a magnetic pulsed compaction (MPC) which is capable of reaching a sufficiently high pressure (~1GPa) in a very short duration (a few microseconds), and a subsequent pressureless sintering at 1600°C. The Y2O3 green bodies with a relative density of about 68% were achieved by the application of the MPC process due to the effect of an enhanced rearrangement and a high speed movement of the particles, without the help of ceramic binder. Those compacts showed densities greater than 95%, which is very close to the theoretical density, after the subsequent pressureless sintering process at 1600 oC. The shrinkage rates of the diameter for the samples compacted by the MPC process were markedly reduced, when compared to those for the ones by the conventional compaction (CC) process.

In-situ temperature stability of a piezoelectric accelerometer based on (Bi, Na, K, Li)TiO3 ceramics

This work investigated the in-situ temperature stability of 0.76(Bi0.5Na0.5)TiO3-0.04(Bi0.5Li0.5)TiO3-0.2(Bi0.5K0.5)TiO3 piezoceramics and a compression-mode accelerometer composed of these materials. The temperature-dependent charge sensitivity of the accelerometer was governed by the small-signal piezoelectric coefficient d33 rather than by the large-signal piezoelectric coefficient d*33 of the (Bi,Na)TiO3-based ceramics. The significant decrease in the charge sensitivity in the vicinity of the depolarization temperature is closely related to the main intrinsic contribution to the piezoelectricity, i.e., the decrease in the crystal anisotropy associated with the temperature-induced polar ferroelectric-nonpolar relaxor phase transition.

Delayed healing and induction of secretory leukocyte protease inhibitor in polycystic ovary syndrome rat skin wounds.

Secretory leukocyte protease inhibitor (SLPI) and estrogen promote wound healing through a decrease in the excessive inflammatory response, accelerating re-epithelialization and increasing the amount of collagen deposition. The excessive administration of estradiol valerate (EV) using hormonal therapy decreases the concentration of estrogen abruptly and induces the polycystic ovary syndrome (PCOS). In this study, the PCOS rat skin wound area was wider than that of the normal groups and the rate of keratinocyte migration in PCOS was lower than the normal group. The numbers of inflammatory cells and macrophages recruited in the PCOS group were larger than that of the normal group. More collagen was deposited in the healing area of the normal group than in the PCOS group. The level of SLPI expression was higher in the PCOS group than the normal group after wounding, with the exception of the epithelium. On the other hand, mRNA and protein expression levels of transforming growth factor-β1 (TGF-β1) were lower in the PCOS group than in the normal group. Matrix metalloproteinase-2 (MMP-2) and MMP-9 levels in the PCOS group were significantly lower than that of the normal group. Therefore, increased SLPI in PCOS skin wounds may help prevent an excessive inflammatory response and aberrant collagen deposition but not are sufficient to accelerate PCOS skin wound healing, suggesting that SLPI may act as a local rather than a systemic modulating molecule in PCOS rat skin wounds.