Sora Han

Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A) Protein Is Involved in Centrosome Separation through the Regulation of NIMA (Never In Mitosis Gene A)-related Kinase 2 (NEK2) Protein Activity

Background: Cancerous inhibitor of protein phosphatase 2A (CIP2A) is overexpressed in most types of human cancer. Results: Depletion of CIP2A prolongs cell division time and CIP2A interacts with NIMA-related kinase 2 (NEK2) during G2/M phase to facilitate centrosome separation. Conclusion: CIP2A is involved in cell cycle progression through centrosome separation and mitotic spindle dynamics. Significance: This provides a novel role for CIP2A in cell cycle progression. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is overexpressed in most human cancers and has been described as being involved in the progression of several human malignancies via the inhibition of protein phosphatase 2A (PP2A) activity toward c-Myc. However, with the exception of this role, the cellular function of CIP2A remains poorly understood. On the basis of yeast two-hybrid and coimmunoprecipitation assays, we demonstrate here that NIMA (never in mitosis gene A)-related kinase 2 (NEK2) is a binding partner for CIP2A. CIP2A exhibited dynamic changes in distribution, including the cytoplasm and centrosome, depending on the cell cycle stage. When CIP2A was depleted, centrosome separation and the mitotic spindle dynamics were impaired, resulting in the activation of spindle assembly checkpoint signaling and, ultimately, extension of the cell division time. Our data imply that CIP2A strongly interacts with NEK2 during G2/M phase, thereby enhancing NEK2 kinase activity to facilitate centrosome separation in a PP1- and PP2A-independent manner. In conclusion, CIP2A is involved in cell cycle progression through centrosome separation and mitotic spindle dynamics.

Interleukin-32β stimulates migration of MDA-MB-231 and MCF-7cells via the VEGF-STAT3 signaling pathway

BackgroundIL-32 is known to play an important role in inflammatory and autoimmune disease responses. In addition to its role in these responses, IL-32 and its different isoforms have in recent years been implicated in the development of various cancers. As of yet, the role of IL-32 in breast cancer has remained largely unknown.ResultsBy performing immunohistochemical assays on primary breast cancer samples, we found that the level of IL-32β expression was positively correlated with tumor size, number of lymph node metastases and tumor stage. In addition, we found that breast cancer-derived MDA-MB-231 cells exogenously expressing IL-32β exhibited increased migration and invasion capacities. These increased capacities were found to be associated with an increased expression of the epithelial mesenchymal transition (EMT) markers vimentin and Slug, the latter of which is responsible for the increase in vimentin transcription. To next investigate whether IL-32β enhances migration and invasion through a soluble factor, we determined the levels of several migration-stimulating ligands, and found that the production of VEGF was increased by IL-32β. In addition, we found that IL-32β-induced VEGF increased migration and invasion through STAT3 activation.ConclusionThe IL-32β-VEGF-STAT3 pathway represents an additional pathway that mediates the migration and invasion of breast cancer cells under the conditions of normoxia and hypoxia.

Hypoxia-induced IL-32β increases glycolysis in breast cancer cells

IL-32β is highly expressed and increases the migration and invasion of gastric, lung, and breast cancer cells. Since IL-32 enhances VEGF production under hypoxic conditions, whether IL-32β is regulated by hypoxia was examined. Hypoxic conditions and a mimetic chemical CoCl2 enhanced IL-32β production. When cells were treated with various inhibitors of ROS generation to prevent hypoxia-induced ROS function, IL-32β production was suppressed by both NADPH oxidase and mitochondrial ROS inhibitors. IL-32β translocated to the mitochondria under hypoxic conditions, where it was associated with mitochondrial biogenesis. Thus, whether hypoxia-induced IL-32β is associated with oxidative phosphorylation (OXPHOS) or glycolysis was examined. Glycolysis under aerobic and anaerobic conditions is impaired in IL-32β-depleted cells, and the hypoxia-induced IL-32β increased glycolysis through activation of lactate dehydrogenase. Src is also known to increase lactate dehydrogenase activity, and the hypoxia-induced IL-32β was found to stimulate Src activation by inhibiting the dephosphorylation of Src. These findings revealed that a hypoxia-ROS-IL-32β-Src-glycolysis pathway is associated with the regulation of cancer cell metabolism.

Adiponectin Deficiency Suppresses Lymphoma Growth in Mice by Modulating NK Cells, CD8 T Cells, and Myeloid-Derived Suppressor Cells

Previously, we found that adiponectin (APN) suppresses IL-2–induced NK cell activation by downregulating the expression of the IFN-γ–inducible TNF-related apoptosis-inducing ligand and Fas ligand. Although the antitumor function of APN has been reported in several types of solid tumors, with few controversial results, no lymphoma studies have been conducted. In this study, we assessed the role of APN in immune cell function, including NK cells, CTLs, and myeloid-derived suppressor cells, in EL4 and B16F10 tumor-bearing APN knockout (KO) mice. We observed attenuated EL4 growth in the APNKO mice. Increased numbers of splenic NK cells and splenic CTLs were identified under naive conditions and EL4-challenged conditions, respectively. In APNKO mice, splenic NK cells showed enhanced cytotoxicity with and without IL-2 stimulation. Additionally, there were decreased levels of myeloid-derived suppressor cell accumulation in the EL4-bearing APNKO mice. Enforced MHC class I expression on B16F10 cells led to attenuated growth of these tumors in APNKO mice. Thus, our results suggest that EL4 regression in APNKO mice is not only due to an enhanced antitumor immune response but also to a high level of MHC class I expression.

Herbal extract THI improves metabolic abnormality in mice fed a high-fat diet

Target herbal ingredient (THI) is an extract made from two herbs, Scutellariae Radix and Platycodi Radix. It has been developed as a treatment for metabolic diseases such as hyperlipidemia, atherosclerosis, and hypertension. One component of these two herbs has been reported to have anti-inflammatory, anti-hyperlipidemic, and anti-obesity activities. However, there have been no reports about the effects of the mixed extract of these two herbs on metabolic diseases. In this study, we investigated the metabolic effects of THI using a diet-induced obesity (DIO) mouse model. High-fat diet (HFD) mice were orally administered daily with 250 mg/kg of THI. After 10 weeks of treatment, the THI-administered HFD mice showed reduction of body weights and epididymal white adipose tissue weights as well as improved glucose tolerance. In addition, the level of total cholesterol in the serum was markedly reduced. To elucidate the molecular mechanism of the metabolic effects of THI in vitro, 3T3-L1 cells were treated with THI, after which the mRNA levels of adipogenic transcription factors, including C/EBPα and PPARγ, were measured. The results show that the expression of these two transcription factors was down regulated by THI in a dose-dependent manner. We also examined the combinatorial effects of THI and swimming exercise on metabolic status. THI administration simultaneously accompanied by swimming exercise had a synergistic effect on serum cholesterol levels. These findings suggest that THI could be developed as a supplement for improving metabolic status.

CTRP1 protects against diet-induced hyperglycemia by enhancing glycolysis and fatty acid oxidation.

Complement-C1q/tumor necrosis factor-α related protein 1 (CTRP1) is a 35-kDa glycoprotein that is secreted from various tissues. Although CTRP1 is highly increased in patients with type II diabetes and obesity, the metabolic roles of CTRP1 remain largely unknown. To unveil the physiological roles of CTRP1 in vivo, CTRP1 transgenic (TG) mice were challenged by a high-fat diet (HFD) and a high-sucrose drink (HS). Homeostatic model assessment-estimated insulin resistance values were decreased in HFD- or HS-fed CTRP1 TG mice compared with wild-type control mice. In this context, CTRP1 stimulated glucose uptake through the glucose transporter GLUT4 translocation to the plasma membrane and also increased glucose consumption by stimulating glycolysis. To analyze the roles of CTRP1 in lipid metabolism, acetyl-CoA carboxylase (ACC) and hormone-sensitive lipase levels were determined in CTRP1 TG mice, and the effect of CTRP1 on fatty acid oxidation was assessed in C2C12 myotubes. CTRP1 was found to inhibit ACC by phosphorylation and to stimulate fatty acid oxidation in C2C12 myotubes. Taken together, CTRP1 performs active catabolic roles in vivo. Therefore, CTRP1 seems to perform a defensive function against nutritional challenges.

Depletion of IK causes mitotic arrest through aberrant regulation of mitotic kinases and phosphatases

IK is known to inhibit the expression of major histocompatibility complex (MHC) class II antigen, but other cellular functions of IK remain to be uncovered. In this study, IK depletion caused misalignment of chromosomes through an increase in Aurora A and PLK1 phosphorylation, which was mediated by a decrease in PP1 and PP2A activities. On the other hand, the treatment of a dual inhibitor against CDK and Aurora kinases overrode IK depletion‐induced mitotic arrest through the activation of phosphatase activity. These findings imply that IK is an essential protein for achieving correct mitotic progress through the regulation of mitotic kinases and phosphatases.

Patient derived mutation W257G of PPP2R1A enhances cancer cell migration through SRC-JNK-c-Jun pathway

Mutation of PPP2R1A has been observed at high frequency in endometrial serous carcinomas but at low frequency in ovarian clear cell carcinoma. However, the biological role of mutation of PPP2R1A in ovarian and endometrial cancer progression remains unclear. In this study, we found that PPP2R1A expression is elevated in high-grade primary tumor patients with papillary serous tumors of the ovary. To determine whether increased levels or mutation of PPP2R1A might contribute to cancer progression, the effects of overexpression or mutation of PPP2R1A on cell proliferation, migration, and PP2A phosphatase activity were investigated using ovarian and endometrial cancer cell lines. Among the mutations, PPP2R1A-W257G enhanced cell migration in vitro through activating SRC-JNK-c-Jun pathway. Overexpression of wild type (WT) PPP2R1A increased its binding ability with B56 regulatory subunits, whereas PPP2R1A-mutations lost the ability to bind to most B56 subunits except B56δ. Total PP2A activity and PPP2R1A-associated PP2Ac activity were significantly increased in cells overexpressing PPP2R1A-WT. In addition, overexpression of PPP2R1A-WT increased cell proliferation in vitro and tumor growth in vivo.

Circulating CTRP1 Levels in Type 2 Diabetes and Their Association with FGF21.

The goal of this study was to investigate whether circulating C1q/TNF-α-related protein 1 (CTRP1) levels are associated with diabetes. In addition, relationships between CTRP1 and other diabetes-related cytokines were elucidated, including adiponectin and fibroblast growth factor 21 (FGF21). A total of 178 subjects (78 men and 100 women) aged 29–70 years (mean age, 46.1 years) were randomly selected. The sera from a normal glucose tolerance group (n = 68) and a prediabetes/type 2 diabetes group (n = 110) were collected; then, circulating levels of CTRP1, adiponectin, and FGF21 were determined via enzyme-linked immunosorbent assay in all sera. Subjects with either prediabetes or diabetes exhibited higher circulating CTRP1 levels than healthy subjects. Sera analysis revealed that CTRP1 was positively correlated with age, body mass index, fasting blood glucose, and circulating FGF21 levels. However, CTRP1 was negatively correlated with total cholesterol and total circulating adiponectin levels in univariate analysis. In addition, multivariate analysis found that CTRP1 was independently associated with age, fasting blood glucose, and circulating FGF21 levels. CTRP1 was correlated with homeostasis model assessment-β (HOMA-β), but no correlation was observed with HOMA-insulin resistance. In conclusion, circulating CTRP1 levels are increased in subjects with type 2 diabetes and are positively associated with circulating FGF21 levels.

Combined Treatment of Herbal Mixture Extract H9 with Trastuzumab Enhances Anti-tumor Growth Effect.

Extracts from Asian medicinal herbs are known to be successful therapeutic agents against cancer. In this study, the effects of three types of herbal extracts on anti-tumor growth were examined. Among the three types of herbal extracts, H9 showed stronger anti-tumor growth effects than H5 and H11 in vivo. To find the molecular mechanism by which H9 inhibited the proliferation of breast cancer cell lines, the levels of apoptotic markers were examined. Proapoptotic markers, including cleaved PARP and cleaved caspases 3 and 9, were increased, whereas the anti-apoptotic marker Bcl-2 was decreased by H9 treatment. Next, the combined effect of H9 with the chemotherapeutic drugs doxorubicin/cyclophosphamide (AC) on tumor growth was examined using 4T1-tumor-bearing mice. The combined treatment of H9 with AC did not show additive or synergetic anti-tumor growth effects. However, when tumor-bearing mice were co-treated with H9 and the targeted anti-tumor drug trastuzumab, a delay in tumor growth was observed. The combined treatment of H9 and trastuzumab caused an increase of natural killer (NK) cells and a decrease of myeloid-derived suppressor cells (MDSC). Taken together, H9 induces the apoptotic death of tumor cells while increasing anti-tumor immune activity through the enhancement of NK activity and diminishment of MDSC.