Decreased sirtuin 4 levels promote cellular proliferation and invasion in papillary thyroid carcinoma.

Objective: This study examined the effect of sirtuin 4 (SIRT4), a NAD+-dependent deacetylase, on the proliferation and progression of papillary thyroid carcinoma (PTC). Methods: Data from The Cancer Genome Atlas (TCGA) were analyzed to identify SIRT4 expression in thyroid cancer. Subsequently, the correlation between SIRT4 expression and clinical characteristics was examined in 205 PTC tissue samples. In vitro assays using three human thyroid cancer cell lines (B-CPAP, TPC-1, and SNU-790) were conducted to assess the effects of regulated SIRT4 expression on cell growth, apoptosis, invasion, and migration. Furthermore, in vivo experiments were performed in a xenograft mouse model. Results: Gene Expression Omnibus (GEO) and TCGA data indicated that SIRT4 expression is lower in thyroid cancer and SIRT4 downregulation is associated with poor overall survival. In PTC tissues, positive SIRT4 expression was associated with decreased extracapsular extension. In in vitro experiments using three human thyroid cancer cell lines, overexpression of SIRT4 decreased cell survival, clonogenic potential, and invasion and migratory capabilities, as well as inducing apoptosis and increasing reactive oxygen species levels. SIRT4 overexpression upregulated E-cadherin and downregulated N-cadherin, suggesting its potential involvement in the regulation of epithelial-mesenchymal transition. These findings were confirmed in vivo using a xenograft mouse model. Conclusion: This study provides novel insight into the potential contribution of SIRT4 to the regulation of the pathological progression of PTC. The data suggest that SIRT4 plays a tumor-suppressive role in PTC by inhibiting growth, survival, and invasive potential. Future research should investigate the molecular mechanisms underlying these effects of SIRT4.

Sirt6-Mediated Cell Death Associated with Sirt1 Suppression in Gastric Cancer.

BACKGROUND: Gastric cancer, one of the leading causes of cancer-related death, is strongly associated with H. pylori infection, although other risk factors have been identified. The sirtuin (Sirt) family is involved in the tumorigenesis of gastric cancer, and sirtuins can have pro- or anti-tumorigenic effects. METHODS: After determining the overall survival rate of gastric cancer patients with or without Sirt6 expression, the effect of Sirt6 upregulation was also tested using a xenograft mouse model. The regulation of Sirt6 and Sirt1, leading to the induction of mouse double minute 2 homolog (MDM2) and reactive oxygen species (ROS), was mainly analyzed using Western blotting and immunofluorescence staining, and gastric cancer cell (SNU-638) death associated with these proteins was measured using flow cytometric analysis. RESULTS: Sirt6 overexpression led to Sirt1 suppression in gastric cancer cells, resulting in a higher level of gastric cancer cell death in vitro and a reduced tumor volume. ROS and MDM2 expression levels were upregulated by Sirt6 overexpression and/or Sirt1 suppression according to Western blot analysis. The upregulated ROS ultimately led to gastric cancer cell death as determined via Western blot and flow cytometric analysis. CONCLUSION: We found that the upregulation of Sirt6 suppressed Sirt1, and Sirt6- and Sirt1-induced gastric cancer cell death was mediated by ROS production. These findings highlight the potential of Sirt6 and Sirt1 as therapeutic targets for treating gastric cancer.

Exploring the role of copine 1 in human colorectal cancer: investigating its association with tumorigenesis and metastasis.

Purpose: This study aimed to investigate the potential role of copine-1 (CPNE1), a calcium-dependent membrane-binding protein encoded by the CPNE1 gene, in colorectal cancer (CRC). Despite previous research on the involvement of copine family members in various solid tumors, the specific role of CPNE1 in CRC remains poorly understood. Methods: We conducted clinicopathological analysis and functional studies to explore the impact of CPNE1 in human CRC. We examined the expression levels of CPNE1 in CRC patients and correlated it with invasive depth, lymph node metastasis, distant metastasis, lymphatic invasion, and TNM stage. Additionally, we performed experiments to assess the functional consequences of CPNE1 knockdown in CRC cells, including proliferation, colony formation, migration, invasion, and the expression of key regulators involved in the cell cycle and epithelial-mesenchymal transition (EMT). Furthermore, we evaluated the effects of CPNE1 knockdown on tumor growth using a xenograft mouse model. Results: High expression of CPNE1 was significantly associated with advanced tumor features in CRC patients. CPNE1 knockdown in CRC cells led to impaired abilities in proliferation, colony formation, migration, and invasion. Furthermore, CPNE1 silencing resulted in the suppression of protein expression related to the cell cycle and EMT. In the xenograft mouse model, CPNE1 knockdown inhibited tumor growth. Conclusion: CPNE1 plays a crucial role in promoting tumorigenesis and metastasis in human CRC. By regulating the cell cycle and EMT, CPNE1 influences critical cellular processes at the membrane-cytoplasm interface. These results provide valuable insights into the potential development of novel therapeutic strategies for CRC targeting CPNE1.

Rutin Prevents Dexamethasone-Induced Muscle Loss in C2C12 Myotube and Mouse Model by Controlling FOXO3-Dependent Signaling.

One of the causes of sarcopenia is that homeostasis between anabolism and catabolism breaks down due to muscle metabolism changes. Rutin has shown antioxidant and anti-inflammatory effects in various diseases, but there are few studies on the effect on muscle loss with aging. The effect of rutin on muscle loss was evaluated using dexamethasone-induced muscle loss C2C12 myoblast and mouse model. In the group treated with dexamethasone, the muscle weight of gastrocnemius (GA), tibialis anterior (TA), and extensor digitorum longus (EDL) in the mouse model were significantly decreased (p < 0.0001 in GA, p < 0.0001 in TA, and p < 0.001 in EDL) but recovered (p < 0.01 in GA, p < 0.0001 in TA, and p < 0.01 in EDL) when treated with rutin. MAFbx, MuRF1, and FOXO3 protein expression of C2C12 myoblast were significantly increased (p < 0.01 in MAFbx, p < 0.01 in MuRF1, and p < 0.01 in FOXO3) when treated with dexamethasone, but it was recovered (p < 0.01 in MAFbx, p < 0.01 in MuRF1, and p < 0.01 in FOXO3) when rutin was treated. In addition, MAFbx and FOXO3 protein expression in GA of mouse model was significantly increased (p < 0.0001 in MAFbx and p < 0.001 in FOXO3) when treated with dexamethasone, but it was also recovered (p < 0.01 in MAFbx and p < 0.001 in FOXO3) when rutin was treated. The present study shows that rutin blocks the FOXO3/MAFbx and FOXO3/MuRf1 pathways to prevent protein catabolism. Therefore, rutin could be a potential agent for muscle loss such as sarcopenia through the blocking ubiquitin-proteasome pathway associated with catabolic protein degradation.

Effects of lifelong spontaneous exercise on skeletal muscle and angiogenesis in super-aged mice.

There has been an increasing awareness of sarcopenia, which is characterized by a concomitant decrease in skeletal muscle mass and quality due to aging. Resistance exercise is considered more effective than aerobic exercise in terms of therapeutic exercise. To confirm the effect of long-term aerobic exercise in preventing sarcopenia, we evaluated the skeletal muscle mass, quality, and angiogenic capacity of super-aged mice that had undergone lifelong spontaneous exercise (LSE) through various experiments. Our findings show that LSE could maintain skeletal muscle mass, quality, and fitness levels in super-aged mice. In addition, ex vivo experiments showed that the angiogenic capacity was maintained at a high level. However, these results were not consistent with the related changes in the expression of genes and/or proteins involved in protein synthesis or angiogenesis. Based on the results of previous studies, it seems certain that the expression at the molecular level does not represent the phenotypes of skeletal muscle and angiogenesis. This is because aging and long-term exercise are variables that can affect both protein synthesis and the expression patterns of angiogenesis-related genes and proteins. Therefore, in aging and exercise-related research, various physical fitness and angiogenesis variables and phenotypes should be analyzed. In conclusion, LSE appears to maintain the potential of angiogenesis and slow the aging process to maintain skeletal muscle mass and quality. Aerobic exercise may thus be effective for the prevention of sarcopenia.

ß-Sitosterol Attenuates Dexamethasone-Induced Muscle Atrophy via Regulating FoxO1-Dependent Signaling in C2C12 Cell and Mice Model.

Sarcopenia refers to a decline in muscle mass and strength with age, causing significant impairment in the ability to carry out normal daily functions and increased risk of falls and fractures, eventually leading to loss of independence. Maintaining protein homeostasis is an important factor in preventing muscle loss, and the decrease in muscle mass is caused by an imbalance between anabolism and catabolism of muscle proteins. Although ß-sitosterol has various effects such as anti-inflammatory, protective effect against nonalcoholic fatty liver disease (NAFLD), antioxidant, and antidiabetic activity, the mechanism of ß-sitosterol effect on the catabolic pathway was not well known. ß-sitosterol was assessed in vitro and in vivo using a dexamethasone-induced muscle atrophy mice model and C2C12 myoblasts. ß-sitosterol protected mice from dexamethasone-induced muscle mass loss. The thickness of gastrocnemius muscle myofibers was increased in dexamethasone with the ß-sitosterol treatment group (DS). Grip strength and creatine kinase (CK) activity were also recovered when ß-sitosterol was treated. The muscle loss inhibitory efficacy of ß-sitosterol in dexamethasone-induced muscle atrophy in C2C12 myotube was also verified in C2C12 myoblast. ß-sitosterol also recovered the width of myotubes. The protein expression of muscle atrophy F-box (MAFbx) was increased in dexamethasone-treated animal models and C2C12 myoblast, but it was reduced when ß-sitosterol was treated. MuRF1 also showed similar results to MAFbx in the mRNA level of C2C12 myotubes. In addition, in the gastrocnemius and tibialis anterior muscles of mouse models, Forkhead Box O1 (FoxO1) protein was increased in the dexamethasone-treated group (Dexa) compared with the control group and reduced in the DS group. Therefore, ß-sitosterol would be a potential treatment agent for aging sarcopenia.

Draft genome of Semisulcospira libertina, a species of freshwater snail.

Semisulcospira libertina, a species of freshwater snail, is widespread in East Asia. It is important as a food source. Additionally, it is a vector of clonorchiasis, paragonimiasis, metagonimiasis, and other parasites. Although S. libertina has ecological, commercial, and clinical importance, its whole-genome has not been reported yet. Here, we revealed the genome of S. libertina through de novo assembly. We assembled the whole-genome of S. libertina and determined its transcriptome for the first time using Illumina NovaSeq 6000 platform. According to the k-mer analysis, the genome size of S. libertina was estimated to be 3.04 Gb. Using RepeatMasker, a total of 53.68% of repeats were identified in the genome assembly. Genome data of S. libertina reported in this study will be useful for identification and conservation of S. libertina in East Asia.

Two Types of Mouse Models for Sarcopenia Research: Senescence Acceleration and Genetic Modification Models.

Sarcopenia leads to loss of skeletal muscle mass, quality, and strength due to aging; it was recently given a disease code (International Classification of Diseases, Tenth Revision, Clinical Modification, M62.84). As a result, in recent years, sarcopenia-related research has increased. In addition, various studies seeking to prevent and treat sarcopenia by identifying the various mechanisms related to the reduction of skeletal muscle properties have been conducted. Previous studies have identified muscle synthesis and breakdown; investigating them has generated evidence for preventing and treating sarcopenia. Mouse models are still the most useful ones for determining mechanisms underlying sarcopenia through correlations and interventions involving specific genes and their phenotypes. Mouse models used to study sarcopenia often induce muscle atrophy by hindlimb unloading, denervation, or immobilization. Though it is less frequently used, the senescence-accelerated mouse can also be useful for sarcopenia research. Herein, we discuss cases where senescence-accelerated and genetically engineered mouse models were used in sarcopenia research and different perspectives to use them.

The Role of Nuclear Factor of Activated T Cells 5 in Hyperosmotic Stress-Exposed Human Lens Epithelial Cells.

We investigated the role of nuclear factor of activated T cells 5 (NFAT5) under hyperosmotic conditions in human lens epithelial cells (HLECs). Hyperosmotic stress decreased the viability of human lens epithelial B-3 cells and significantly increased NFAT5 expression. Hyperosmotic stress-induced cell death occurred to a greater extent in NFAT5-knockout (KO) cells than in NFAT5 wild-type (NFAT5 WT) cells. Bcl-2 and Bcl-xl expression was down-regulated in NFAT5 WT cells and NFAT5 KO cells under hyperosmotic stress. Pre-treatment with a necroptosis inhibitor (necrostatin-1) significantly blocked hyperosmotic stress-induced death of NFAT5 KO cells, but not of NFAT5 WT cells. The phosphorylation levels of receptor-interacting protein kinase 1 (RIP1) and RIP3, which indicate the occurrence of necroptosis, were up-regulated in NFAT5 KO cells, suggesting that death of these cells is predominantly related to the necroptosis pathway. This finding is the first to report that necroptosis occurs when lens epithelial cells are exposed to hyperosmolar conditions, and that NFAT5 is involved in this process.

Serum hepatocyte growth factor as a predictor of disease severity and future exacerbations in patients with non-cystic fibrosis bronchiectasis.

BACKGROUND: Serum biomarkers associated with the severity of non-cystic fibrosis (CF) bronchiectasis are insufficient. This study determined the association of serum hepatocyte growth factor (HGF), osteopontin, and pentraxin-3 levels with disease severity and exacerbation in patients with non-CF bronchiectasis. METHODS: Serum levels of HGF, osteopontin, and pentraxin-3 were measured in patients with clinically stable non-CF bronchiectasis (n = 61). The correlation between the biomarkers and bronchiectasis severity index (BSI) and FACED score was assessed using univariate and multivariate linear regression analyses. Predictive variables associated with exacerbation were analyzed using a Cox proportional hazards model and the time to first exacerbation in high and low HGF groups during the observation period was compared using Kaplan-Meier survival curves. RESULTS: The BSI showed significant correlation with HGF (r = 0.423; p = 0.001) and pentraxin-3 (r = 0.316; p = 0.013). The FACED score was significantly correlated with HGF (r = 0.406; p = 0.001). Univariate and multivariate linear regression analysis revealed that serum level of HGF was independently associated with both scoring systems. The high HGF group showed a significantly shorter time to first exacerbation (Log-rank test, p = 0.014). Multivariate Cox proportional hazards regression analysis revealed that high serum HGF level and colonization with non-pseudomonas organisms were independent predictors of future exacerbations (HR 2.364; p = 0.024 and HR 2.438; p = 0.020, respectively). CONCLUSION: Serum level of HGF is a potential biomarker that is closely associated with disease severity and future risk of exacerbations in patients with non-CF bronchiectasis.

MDM2-dependent Sirt1 degradation is a prerequisite for Sirt6-mediated cell death in head and neck cancers.

Sirt6 is involved in multiple biological processes, including aging, metabolism, and tumor suppression. Sirt1, another member of the sirtuin family, functionally overlaps with Sirt6, but its role in tumorigenesis is controversial. In this study, we focused on cell death in association with Sirt6/Sirt1 and reactive oxygen species (ROS) in head and neck squamous cell carcinomas (HNSCCs). Sirt6 induced cell death, as widely reported, but Sirt1 contributed to cell death only when it was suppressed by Sirt6 via regulation of MDM2. Sirt6 and Sirt6-mediated suppression of Sirt1 upregulated ROS, which further led to HNSCC cell death. These results provide insight into the molecular roles of Sirt6 and Sirt1 in tumorigenesis and could therefore contribute to the development of novel strategies to treat HNSCC.

Upregulation of TRESK Channels Contributes to Motor and Sensory Recovery after Spinal Cord Injury.

TWIK (tandem-pore domain weak inward rectifying K+)-related spinal cord K+ channel (TRESK), a member of the two-pore domain K+ channel family, is abundantly expressed in dorsal root ganglion (DRG) neurons. It is well documented that TRESK expression is changed in several models of peripheral nerve injury, resulting in a shift in sensory neuron excitability. However, the role of TRESK in the model of spinal cord injury (SCI) has not been fully understood. This study investigates the role of TRESK in a thoracic spinal cord contusion model, and in transgenic mice overexpressed with the TRESK gene (TGTRESK). Immunostaining analysis showed that TRESK was expressed in the dorsal and ventral neurons of the spinal cord. The TRESK expression was increased by SCI in both dorsal and ventral neurons. TRESK mRNA expression was upregulated in the spinal cord and DRG isolated from the ninth thoracic (T9) spinal cord contusion rats. The expression was significantly upregulated in the spinal cord below the injury site at acute time points (6, 24, and 48 h) after SCI (p < 0.05). In addition, TRESK expression was markedly increased in DRGs below and adjacent to the injury site. TRESK was expressed in inflammatory cells. In addition, the number and fluorescence intensity of TRESK-positive neurons increased in the dorsal and ventral horns of the spinal cord after SCI. TGTRESK SCI mice showed faster paralysis recovery and higher mechanical threshold compared to wild-type (WT)-SCI mice. TGTRESK mice showed lower TNF-α concentrations in the blood than WT mice. In addition, IL-1ß concentration and apoptotic signals in the caudal spinal cord and DRG were significantly decreased in TGTRESK SCI mice compared to WT-SCI mice (p < 0.05). These results indicate that TRESK upregulated following SCI contributes to the recovery of paralysis and mechanical pain threshold by suppressing the excitability of motor and sensory neurons and inflammatory and apoptotic processes.

Rodent Model of Muscular Atrophy for Sarcopenia Study.

The hallmark symptom of sarcopenia is the loss of muscle mass and strength without the loss of overall body weight. Sarcopenia patients are likely to have worse clinical outcomes and higher mortality than do healthy individuals. The sarcopenia population shows an annual increase of ~0.8% in the population after age 50, and the prevalence rate is rapidly increasing with the recent worldwide aging trend. Based on International Classification of Diseases, Tenth Revision, a global classification of disease published by the World Health Organization, issued the disease code (M62.84) given to sarcopenia in 2016. Therefore, it is expected that the study of sarcopenia will be further activated based on the classification of disease codes in the aging society. Several epidemiological studies and meta-analyses have looked at the correlation between the prevalence of sarcopenia and several environmental factors. In addition, studies using cell lines and rodents have been done to understand the biological mechanism of sarcopenia. Laboratory rodent models are widely applicable in sarcopenia studies because of the advantages of time savings, cost saving, and various analytical applications that could not be used for human subjects. The rodent models that can be applied to the sarcopenia research are diverse, but a simple and fast method that can cause atrophy or aging is preferred. Therefore, we will introduce various methods of inducing muscular atrophy in rodent models to be applied to the study of sarcopenia.

Periostin Plays a Key Role in Radioresistance of Head and Neck Cancer Cells Via Epithelial-to-Mesenchymal Transition.

BACKGROUND/AIM: Head and neck squamous cell carcinoma (HNSCC) is an aggressive head and neck malignancy. The aim of this study was to elucidate the role of periostin (POSTN) in the epithelial-to-mesenchymal transition (EMT) process mediating the acquisition of radioresistance in HNSCC. MATERIALS AND METHODS: The expression levels of EMT hallmark genes including POSTN and Erk/Akt signaling pathways were compared between radiosensitive and radioresistant HNSCC cells. RESULTS: POSTN mRNA expression was higher in radioresistant HNSCC cells, and silencing POSTN significantly impaired their invasiveness under the effect of EMT process represented by up-regulation of mesenchymal markers and down-regulation of an epithelial marker. Expression levels of Erk and Akt were higher in radioresistant cells. CONCLUSION: POSTN in association with the Erk and Akt signaling pathways was up-regulated during the EMT process, leading to the conversion of radiosensitive to radioresistant HNSCC cells. POSTN may be a key marker for predicting the radioresistance and therapeutic target of HNSCC.

In vitro effects of alendronate on fibroblasts of the human rotator cuff tendon.

BACKGROUND: Bone mineral density of the humeral head is an independent determining factor for postoperative rotator cuff tendon healing. Bisphosphonates, which are commonly used to treat osteoporosis, have raised concerns regarding their relationships to osteonecrosis of the jaw and to atypical fracture of the femur. In view of the prevalence of rotator cuff tear in osteoporotic elderly people, it is important to determine whether bisphosphonates affect rotator cuff tendon healing. However, no studies have investigated bisphosphonates' cytotoxicity to human rotator cuff tendon fibroblasts (HRFs) or bisphosphonates' effects on rotator cuff tendon healing. The purpose of this study was to evaluate the cytotoxicity of alendronate (Ald), a bisphosphonate, and its effects on HRF wound healing. METHODS: HRFs were obtained from human supraspinatus tendons, using primary cell cultures. The experimental groups were control, 0.1 µM Ald, 1 µM Ald, 10 µM Ald, and 100 µM Ald. Alendronate exposure was for 48 h, except during a cell viability analysis with durations from 1 day to 6 days. The experimental groups were evaluated for cell viability, cell cycle and cell proliferation, type of cell death, caspase activity, and wound-healing ability. RESULTS: The following findings regarding the 100 µM Ald group contrasted with those for all the other experimental groups: a significantly lower rate of live cells (p < 0.01), a higher rate of subG1 population, a lower rate of Ki-67 positive cells, higher rates of apoptosis and necrosis, a higher number of cells with DNA fragmentation, higher caspase-3/7 activity (p < 0.001), and a higher number of caspase-3 positive staining cells. In scratch-wound healing analyses of all the experimental groups, all the wounds healed within 48 h, except in the 100 µM Ald group (p < 0.001). CONCLUSIONS: Low concentrations of alendronate appear to have little effect on HRF viability, proliferation, migration, and wound healing. However, high concentrations are significantly cytotoxic, impairing cellular proliferation, cellular migration, and wound healing in vitro.

Reduced NGF Level Promotes Epithelial-Mesenchymal Transition in Human Lens Epithelial Cells Exposed to High Dexamethasone Concentrations.

Purpose: To investigate the protective effects of nerve growth factor (NGF) against steroid-induced cataract formation in dexamethasone (Dex)-treated human lens epithelial B-3 (HLE-B3) cells and the possible molecular mechanisms underlying this protection.Materials and Methods: HLE-B3 cells were treated with Dex, and cell viability was assessed using the Cell Counting Kit-8 (CCK-8) assay. The levels of expression of NGF, fibronectin, α-smooth muscle actin (α-SMA), and E-cadherin mRNAs were measured by real-time quantitative polymerase chain reaction (qPCR), and the levels of NGF, fibronectin, α-SMA, E-cadherin, tropomyosin receptor kinase A (TrkA), and Akt proteins were measured by Western blot analysis. Gene expression profiles of growth factors in Dex-treated HLE-B3 cells were determined by PCR arrays. In addition, anterior capsule tissue was obtained during cataract surgery, and the specimens were also examined expressions of NGF.Results: NGF was expressed in HLE-B3 cells and also in lens epithelial cells of anterior lens capsules. Dex treatment of HLE-B3 cells increased their expression of epithelial-mesenchymal transition (EMT) markers and migration activity, while markedly downregulating the expression of NGF. NGF treatment significantly reduced the expression of α-SMA and fibronectin, as well as cell proliferation. The decreased phosphorylation of p38 MAPK and Akt induced by Dex treatment was significantly reversed by treatment with NGF.Conclusion: NGF/TrkA may repress EMT by targeting the p38 MAPK and pAkt pathways in Dex-treated HLE-B3 cells. NGF may be a novel therapeutic target for patients with steroid-induced cataract.

ERH overexpression is associated with decreased cell migration and invasion and a good prognosis in gastric cancer.

BACKGROUND: The enhancer of rudimentary homolog (ERH) protein is implicated in transcriptional regulation, cell cycle progression, and malignancy. We previously conducted a proteomics analysis using gastric cancer (GC) tissues and identified ERH as a biomarker candidate. The aim of this study was to investigate whether ERH may be useful as a prognostic marker for GC. METHODS: Surgically resected GC tissue specimens were obtained from 327 patients who underwent gastrectomy at Gyeongsang National University Hospital. Immunohistochemistry (IHC) was used to validate ERH as a prognostic marker in these tissues. SNU601 and MKN74 cells with siRNA-mediated knockdown of ERH expression and ERH-overexpressing SNU601 and MKN74 knock-in cells were used for analysis of ERH function. RESULTS: ERH was overexpressed in stomach cancer tissues compared with normal tissues according to proteomics analysis (n=29, P<0.01) of patient samples. Based on IHC, patients with tumors overexpressing ERH had lower T stage and lower TNM stage classifications, lower cancer recurrence rates and longer survival times than did patients with tumors showing low expression of ERH (P=0.04). In vitro, forced expression of ERH significantly decreased GC cell migration and invasion, and depletion of ERH triggered GC cell migration and invasion but had no effect on proliferation in vitro. CONCLUSIONS: The findings from the present study show that ERH is associated with decreased cancer cell migration and invasion, suggesting that overexpression of ERH may serve as a marker of good prognosis for patients with GC.

Involvement of mitochondrial biogenesis during the differentiation of human periosteum-derived mesenchymal stem cells into adipocytes, chondrocytes and osteocytes.

Due to a rapidly expanding aging population, the incidence of age-related or degenerative diseases has increased, and efforts to handle the issue with regenerative medicine via adult stem cells have become more important. And it is now clear that the mitochondrial energy metabolism is important for stem cell differentiation. When stem cells commit to differentiate, glycolytic metabolism is being shifted to mitochondrial oxidative phosphorylation (OXPHOS) to meet an increased cellular energy demand required for differentiated cells. However, the nature of cellular metabolisms during the differentiation process of periosteum-derived mesenchymal stem cells (POMSC) is still unclear. In the present study, we investigated mitochondrial biogenesis during the adipogenic, chondrogenic, and osteogenic differentiation of POMSCs. Both mitochondrial DNA (mtDNA) contents and mitochondrial proteins (VDAC and mitochondrial OXPHOS complex subunits) were increased during all of these mesenchymal lineage differentiations of POMSCs. Interestingly, glycolytic metabolism is reduced as POMSCs undergo osteogenic differentiation. Furthermore, reducing mtDNA contents by ethidium bromide treatments prevents osteogenic differentiation of POMSCs. In conclusion, these results indicate that mitochondrial biogenesis and OXPHOS metabolism play important roles in the differentiation of POMCS and suggest that pharmaceutical modulation of mitochondrial biogenesis and/or function can be a novel regulation for POMSC differentiation and regenerative medicine.

Nicotinamide N­methyltransferase induces the proliferation and invasion of squamous cell carcinoma cells.

Cutaneous squamous cell carcinoma (cSCC) is a common malignancy initiated by keratinocytes of the epidermis, which are able to invade the dermis and its periphery. Although most patients with cSCC present with curable localized tumors, recurrence, metastasis and mortality occasionally occur. In the present study, nicotinamide N­methyltransferase (NNMT) was identified as an upregulated protein in the SCC12 cell line, which has high invasive potential compared with the SCC13 cell line. The effects of NNMT knockdown on proliferation, migration and invasion were investigated using SCC cells. shRNA­mediated downregulation of NNMT expression levels inhibited the proliferation and density­dependent growth of SCC12 cells. In addition, the results of a cell motility assay showed that the migration and invasion of SCC cells were markedly decreased in NNMT­knockdown cells. The assessment of epithelial­mesenchymal transition (EMT)­associated gene expression using PCR array analysis revealed that high NNMT expression levels were accompanied by high expression levels of EMT­associated genes, and that NNMT knockdown effectively suppressed the expression of matrix metalloproteinase 9, osteopontin, versican core protein and zinc finger protein SNAI2 in SCC12 cells. These results revealed that the upregulation of NNMT induced cellular invasion via EMT­related gene expression in SCC cells.

p38 Stabilizes Snail by Suppressing DYRK2-Mediated Phosphorylation That Is Required for GSK3ß-ßTrCP-Induced Snail Degradation.

Snail is a key regulator of epithelial-mesenchymal transition (EMT), which is a major step in tumor metastasis. Although the induction of Snail transcription precedes EMT, posttranslational regulation, especially phosphorylation of Snail, is critical for determining Snail protein levels or stability, subcellular localization, and the ability to induce EMT. To date, several kinases are known that enhance the stability of Snail by preventing its ubiquitination; however, the molecular mechanism(s) underlying this are still unclear. Here, we identified p38 MAPK as a crucial posttranslational regulator that enhances the stability of Snail. p38 directly phosphorylated Snail at Ser107, and this effectively suppressed DYRK2-mediated Ser104 phosphorylation, which is critical for GSK3ß-dependent Snail phosphorylation and ßTrCP-mediated Snail ubiquitination and degradation. Importantly, functional studies and analysis of clinical samples established a crucial role for the p38-Snail axis in regulating ovarian cancer EMT and metastasis. These results indicate the potential therapeutic value of targeting the p38-Snail axis in ovarian cancer. SIGNIFICANCE: These findings identify p38 MAPK as a novel regulator of Snail protein stability and potential therapeutic target in ovarian cancer.