Kyung-A Hwang

Black rice (Oryza sativa L.) extract attenuates hepatic steatosis in C57BL/6 J mice fed a high-fat diet via fatty acid oxidation

BackgroundTwo major risk factors for the onset of fatty liver disease are excessive alcohol intake and obesity, the latter being associated with non-alcoholic fatty liver disease (NAFLD). The aim of this study was to examine the effects of black rice extract (BRE) on hepatic steatosis and insulin resistance in high-fat diet-fed mice, providing a model of NAFLD.MethodsTwenty-four mice were randomly divided into three groups (n = 8 in each group): normal fat diet (ND), high fat diet (HF), and high fat diet supplemented with 1% (w/w) BRE (HF +1% BRE). The experimental diets were fed for seven weeks.ResultsA HF induced hepatic steatosis with significant increases in the serum levels of free fatty acids (FFAs), triglyceride (TG), total cholesterol (TC), and insulin. By contrast, supplementary BRE (10 g/kg of diet) included in the HF alleviated hepatic steatosis and significantly decreased serum TG and TC levels (p < 0.01 for both). Dietary BRE also increased expression of fatty acid metabolism-related genes, including carnitine palmitoyltransferase (CPT1A), acyl-CoA oxidase (ACO), cytochrome P450 (CYP4A10), and peroxisome proliferator activated receptor (PPAR)-α (p < 0.05 for all).ConclusionsDietary BRE supplementation improved serum lipid profiles and significantly enhanced mRNA expression levels of fatty acid metabolism-related genes, primarily via β-oxidation and ω-oxidation in the liver. Taken together, these findings suggest that a BRE-supplemented diet could be useful in reducing the risks of hepatic steatosis and related disorders, including hyperlipidemia and hyperglycemia.

Intracellular reprogramming of expression, glycosylation, and function of a plant-derived antiviral therapeutic monoclonal antibody.

Plant genetic engineering, which has led to the production of plant-derived monoclonal antibodies (mAbPs), provides a safe and economically effective alternative to conventional antibody expression methods. In this study, the expression levels and biological properties of the anti-rabies virus mAbP SO57 with or without an endoplasmic reticulum (ER)-retention peptide signal (Lys-Asp-Glu-Leu; KDEL) in transgenic tobacco plants (Nicotiana tabacum) were analyzed. The expression levels of mAbP SO57 with KDEL (mAbPK) were significantly higher than those of mAbP SO57 without KDEL (mAbP) regardless of the transcription level. The Fc domains of both purified mAbP and mAbPK and hybridoma-derived mAb (mAbH) had similar levels of binding activity to the FcγRI receptor (CD64). The mAbPK had glycan profiles of both oligomannose (OM) type (91.7%) and Golgi type (8.3%), whereas the mAbP had mainly Golgi type glycans (96.8%) similar to those seen with mAbH. Confocal analysis showed that the mAbPK was co-localized to ER-tracker signal and cellular areas surrounding the nucleus indicating accumulation of the mAbP with KDEL in the ER. Both mAbP and mAbPK disappeared with similar trends to mAbH in BALB/c mice. In addition, mAbPK was as effective as mAbH at neutralizing the activity of the rabies virus CVS-11. These results suggest that the ER localization of the recombinant mAbP by KDEL reprograms OM glycosylation and enhances the production of the functional antivirus therapeutic antibody in the plant.

Expression of GA733-Fc fusion protein as a vaccine candidate for colorectal cancer in transgenic plants.

The tumor-associated antigen GA733 is a cell-surface glycoprotein highly expressed in colorectal carcinomas. In this study, 3 recombinant genes were constructed as follows: GA733 tagged to the ER retention sequence KDEL (GA733K), GA733 fused to the immunoglobulin Fc fragment (GA733-Fc), and GA733-Fc fused to the ER retention sequence (GA733-FcK). Agrobacterium-mediated transformation was used to generate transgenic plants expressing recombinant genes. The presence of transgenes was confirmed by genomic PCR. Western blot, confocal immunofluorescence, and sandwich ELISA showed the expression of recombinant proteins. The stability, flexibility, and bioactivity of recombinant proteins were analyzed and demonstrated through N-glycosylation analysis, animal trials, and sera ELISA. Our results suggest that the KDEL retained proteins in ER with oligomannose glycan structure and enhanced protein accumulation level. The sera of mice immunized with GA733-FcK purified from plants contained immunoglobulins which were at least as efficient as the mammalian-derived GA733-Fc at recognizing human colorectal cancer cell lines. Thus, a plant system can be used to express the KDEL fusion protein with oligomannose glycosylation, and this protein induces an immune response which is comparable to non-KDEL-tagged, mammalian-derived proteins.

Relationship between ganglioside expression and anti-cancer effects of the monoclonal antibody against epithelial cell adhesion molecule in colon cancer

The human colorectal carcinoma-associated GA733 antigen epithelial cell adhesion molecule (EpCAM) was initially described as a cell surface protein selectively expressed in some myeloid cancers. Gangliosides are sialic acid-containing glycosphingolipids involved in inflammation and oncogenesis. We have demonstrated that treatment with anti-EpCAM mAb and RAW264.7 cells significant inhibited the cell growth in SW620 cancer cells, but neither anti-EpCAM mAb nor RAW264.7 cells alone induced cytotoxicity. The relationship between ganglioside expression and the anti-cancer effects of anti-EpCAM mAb and RAW264.7 was investigated by high-performance thin-layer chromatography. The results demonstrated that expression of GM1 and GD1a significantly increased in the ability of anti-EpCAM to inhibit cell growth in SW620 cells. Anti-EpCAM mAb treatment increased the expression of anti-apoptotic proteins such as Bcl-2, but the expression of pro-apoptotic proteins Bax, TNF-α, caspase-3, cleaved caspase-3, and cleaved caspase-8 were unaltered. We observed that anti-EpCAM mAb significantly inhibited the growth of colon tumors, as determined by a decrease in tumor volume and weight. The expression of anti-apoptotic protein was inhibited by treatment with anti-EpCAM mAb, whereas the expression of pro-apoptotic proteins was increased. These results suggest that GD1a and GM1 were closely related to anticancer effects of anti-EpCAM mAb. In light of these results, further clinical investigation should be conducted on anti-EpCAM mAb to determine its possible chemopreventive and/or therapeutic efficacy against human colon cancer.

Comparison of total soluble protein in various horticultural crops and evaluation of its quantification methods

Various horticultural crops have been considered as potential heterologous expression systems for plant-made recombinant pharmaceutical proteins. However, there is little information concerning the total soluble protein (TSP) levels of major horticultural crops. Ten major horticultural crops-Chinese cabbage, broccoli, garlic, onion, cabbage, bunching onion, cucumber, zucchini, radish, and carrot, along with tobacco and Arabidopsis, were selected to investigate the TSP levels in their individual tissues. In tobacco, SDS-PAGE assay showed that leaf tissues had stronger protein bands than stem tissues, and freshly harvested samples had slightly stronger band density than the −70°C frozen samples, suggesting that fresh leaf should be used to measure the total soluble proteins without any protein loss or degradation. Bicinchoninic acid (BCA) protein assay revealed that among various horticultural crops, garlic (41.4 mg·g−1 FW), broccoli (21.9 mg·g−1 FW), and Chinese cabbage (11.9 mg·g−1 FW) had the highest TSP levels suggesting that these horticultural crops could be good candidates for plant molecular biofarming to produce highly valuable recombinant proteins. The inner clove tissue in garlic, the flower tissue in broccoli, and the green leaf tissue in Chinese cabbage showed the strongest protein band density as compared to other tissues. The TSP of Arabidopsis tissues was quantified by SDS-PAGE, BCA, and Nano-drop methods. In general, the middle leaf tissue showed the highest TSP levels. To evaluate TSP levels of various horticultural crops, these three different methods were compared. The correlation and regression analyses between SDS-PAGE and BCA, and SDS-PAGE and Nano-drop suggested that there were significant correlations between SDS-PAGE and BCA protein assays as compared to SDS-PAGE and Nano-drop assays, indicating that BCA assay is reliable to quantify TSP levels. In conclusion, the TSP levels varied depending on the horticultural crops and their tissue types, and BCA assay could be applied to quantify the TSP.

Glycomodification and characterization of anti-colorectal cancer immunotherapeutic monoclonal antibodies in transgenic tobacco

Anti-colorectal cancer mAb CO17-1A (IgG2a) recognizes the antigen GA733, which is highly expressed on the surface membrane of human colorectal carcinoma cells. In this study, a transgenic tobacco system for the production of mAb CO17-1A was developed. The mAb construct included a KDEL sequence, an endoplasmic reticulum (ER) retention signal attached to the C-terminus of the heavy chain, to target accumulation of mAb into ER. An immunoblot showed significantly enhanced levels of expression of the plant-derived mAbK (mAbPK) CO17-1A compared to mAbP CO17-1A mAb without the KDEL sequence. An ELISA assay using human colorectal carcinoma cells confirmed that expression of mAbPK was also significantly higher than that of mAbP. Glycosylation analysis revealed that mAbP had plant-specific glycans; whereas, mAbPK primarily had oligomannose glycans. FACS showed that the Fc domains of both mAbPK and mammalian-derived mAb (mAbM) had similar binding activity to the FcγRI receptor (CD64). However, the Fc domains of the mAbP had slightly lower binding activity to the FcγRI receptor than both mAbPK and mAbM. The antibody-dependent cell cytotoxicity of mAbPK, against human colorectal cancer cells, was as efficient as mAbM; whereas mAbP was very low. These results suggest that KDEL localized and accumulated mAbP in the ER and eventually enhanced the expression of mAbP with oligomannose glycan and similar anti-cancer biological activity to the parental mAbM.

Chimerism of multiple monoclonal antibodies expressed in a single plant

Transgenic plants offer a source for the sustainable, safe, and large-scale production of therapeutic recombinant proteins. In this study, both murine anti-colorectal cancer mAb (mAbMC) and human anti-rabies mAb 57 (mAbHR), expressed in a single plant were investigated for their cancer cell binding activity and rabies virus neutralization activity, respectively. Transgenic plants, expressing murine anti-colorectal cancer mAb CO17-1A (mAbMC) and human anti-rabies mAb 57 (mAbHR), respectively, were crossed to reproduce F1 transgenic plant, expressing both mAbs. PCR and immunoblot analyses demonstrated that heavy (HC) and light chain (LC) genes of mAbMC and mAbHR were present, and that both mAbs were expressed in F1 transgenic lines, respectively. Quantitative immunoblot for purified mAb also showed the presence of both mAbs in F1 transgenic lines. However, Cell ELISA analysis showed that in mAbPC and mAbPR purified from the F1 transgenic lines (mAbPC×R), the binding activity to SW948 human colorectal carcinoma cells was lower than mAbMC, and in vitro mAbMC, mixed with mAbHR (mAbMHC+R). The in vitro rabies virus neutralization assay demonstrated that the mAbPC×R, from the F1 transgenic plants, had lower bioactivity against rabies virus than mAbH57, and mAbMHC+R. N-glycan structure analysis revealed that mAbMC and mAbHR had Golgi type (94 and 14%) and ER type (6 and 86%), respectively, and the purified mAbs from the F1 transgenic plants had Golgi type (75%) and ER type (25%). These results indicate that the F1 transgenic plant produced both mAbPC and mAbPR; however, the HC and LC proteins of each anti-rabies virus and anti-colorectal cancer mAbs were assembled randomly, resulting in chimerism in HC and LC assembly for mAb.

Isolation and analysis of natural compounds from silkworm pupae and effect of its extracts on alcohol detoxification

Silkworm pupae have much potential and many applications as a natural medicine to promote human health. However, their chemical components have not been fully characterized or understood. HPLC analysis was conducted to determine the content ratio (%) of individual amino acids in total protein of the pupae. It showed that glutamic acid (18.3%), histidine (14.6%) and alanine (10.2%) are the most common amino acids in silkworm pupae. Fatty acid composition of silkworm pupae oil was revealed by high‐pressure liquid chromatography and gas chromatography – mass spectroscopy analyses. They contain a high ratio of essential fatty acids, [α‐linolenic acid (ω‐3 fatty acid]+ linoleic acid) (49.0%), and also contain non‐essential fatty acids, oleic acid (19.9%), palmitoleic acid (2.5%), palmitic acid (19.7%), stearic acid (8.6%), and eicosapentaenoic acid (EPA) (0.3%). In addition, they also contain antioxidants, quercetin diglucoside and nutritionally important riboflavin (vitamin B2). This study suggests that silkworm pupae are a nutritionally valuable food product and are applicable as cosmetic components with essential amino acids, essential fatty acids, antioxidants and vitamins. The animal experiment showed that alcohol dehydrogenase (ADH) activity was significantly higher in the liver of mice orally administered with 0.5 mg/mL of silkworm extract and alcohol than with commercial Dawn808™ and alcohol, indicating that silkworm pupae extracts have alcohol detoxification activity.

Expression of recombinant anti‐breast cancer immunotherapeutic monoclonal antibody in baculovirus–insect cell system

The anti‐breast cancer monoclonal antibody (mAb) BR55 was expressed in the baculovirus–insect cell expression system, which is advantageous because of its high production capacity, cell culture flexibility and glycosylation capability. The baculovirus–insect cell expression system was successfully established for production of mAb BR55 and mAb BR55 fused with the KDEL (Lys–Asp–Glu–Leu) endoplasmic reticulum (ER) retention signal (mAb BR55K). The heavy chain (HC) and light chain (LC) genes of mAb BR55 were cloned under the control of the polyhedrin (PPH) and P10 promoters, respectively, in the pFastBacDual vector. The antibody gene‐expression cassettes carrying both the HC and LC genes were transferred into a bacmid in Escherichia coli (DH10Bac). The bacmid carrying the expression cassettes was transfected into Sf9 insect cells to generate baculovirus expressing mAb BR55 and BR55K. Western blot analysis confirmed the expression of mAb BR55 and BR55K in baculovirus‐infected insect cells. Cell direct enzyme linked immunosorbent assay (ELISA) showed that both mAbs from insect cell lysates or cell culture medium bound to MCF‐7 human breast cancer cells. Both mAb BR55 and BR55K were successfully purified using a Protein A affinity column. Collectively, these results suggest that the anti‐breast cancer mAb BR55 can be expressed, properly assembled and purified from the baculovirus expression system, which can serve as an alternative system for antibody production.

Oral administration of insulin-like growth factor-I from colostral whey reduces blood glucose in streptozotocin-induced diabetic mice

The aim of the present study was to investigate the effects of oral administration of the insulin-like growth factor-I-rich fraction (IGF-I-RF) from bovine colostral whey on the regulation of blood glucose levels in streptozotocin (STZ)-induced diabetic mice. We obtained a peptide fraction containing IGF-I (10 ng/mg protein) from Holstein colostrum within 24 h after parturition by using ultrafiltration. The blood glucose levels of STZ-induced diabetic mice fed with IGF-I-RF (50 μg/kg per d) were significantly reduced by 11 and 33 % at weeks 2 and 4, respectively (P < 0·05). The body weights of STZ-induced diabetic mice increased following the oral administration of the IGF-I-RF. The kidney weights of STZ-induced diabetic mice decreased significantly (P < 0·05) following the administration of the IGF-I-RF, and the liver weights of STZ-induced diabetic mice decreased significantly (P < 0·05) following the administration of 50 μg/kg per d of the IGF-I-RF. The present results indicate that the IGF-I-RF obtained from Holstein colostrum could be a useful component for an alternative therapeutic modality for the treatment of diabetes in insulin-resistant patients.