Combination of peroxisome proliferator-activated receptor gamma and retinoid X receptor agonists induces sodium/iodide symporter expression and inhibits cell growth of human thyroid cancer cells.

BACKGROUND: Thyroid tumors are the most frequent neoplasm of the endocrine system. The major treatment is surgical intervention followed by radioiodine therapy. The sodium/iodide symporter (NIS) has positive expression in thyroid carcinomas with good prognoses and plays a critical role in radioiodine therapy response. Low expression of NIS always leads to tumor recurrence or treatment failure. Redifferentiation therapy is more tumor specific than chemotherapy. Peroxisome proliferator-activated receptor gamma (PPARγ) agonists and retinoids are two types of redifferentiating agents. In this study, we examined whether the PPARγ agonist rosiglitazone and retinoid X receptor (RXR) agonist bexarotene could increase NIS expression and exhibit anticancer activity in human thyroid cancer cells. METHODS: Using a TCGA data set, we analyzed the expression of NIS (SLC5A5), PPARγ, and RXR in clinical thyroid tumors and assessed their correlations with the relapse-free survival (RFS) of thyroid tumor patients. Moreover, two human thyroid cancer cell lines, differentiated thyroid papillary BCPAP cells and follicular follicular thyroid cancer-131 cells, were treated with different concentrations of the PPARγ agonist rosiglitazone alone or in combination with the RXR agonist bexarotene. Cell growth was analyzed by the MTT assay. NIS protein expression was determined by Western blotting. RESULTS: From analysis of the TCGA data set, we found that thyroid tumors have lower expression of both NIS (SLC5A5) and PPARγ than nontumor controls. Higher expression levels of NIS, PPARγ, and RXR are associated with higher RFS in patients with thyroid tumors. Moreover, rosiglitazone treatment reduced cell growth and increased NIS protein expression in thyroid cancer cells under normoxic or hypoxic conditions. In addition, bexarotene potentiated the effects of rosiglitazone on cell growth and NIS protein expression. CONCLUSION: Our results suggest that the combination of PPARγ and RXR agonists has potential as a chemotherapeutic strategy for thyroid cancer.

Printing a Three-Dimensional Patient-Specific Safety Device for Reducing the Potential Risk of Mental Nerve Injury During Transoral Thyroidectomy.

BACKGROUND: Thyroidectomy transoral endoscopic thyroidectomy vestibular approach (TOETVA) is a safe and cosmetically appealing alternative for well-selected patients undergoing thyroidectomy. However, during TOETVA, placement of the two lateral trocars and/or manipulation of the surgical instruments through the trocars may potentially injure and/or compress the mental nerve (MN) because the actual location of the nerve foramen may vary among individuals. The MN injury rate was reported to be as high as 75% in the initial period of robotic-assisted TOETVA. To reduce the potential risk of MN injury, we implemented a three-dimensional printing technology to develop a safety device for TOETVA. METHODS: The patient-specific safety device (PSSD) was a brace with an exact fit to the lower teeth and two safety markers on each side to indicate the location of the mental foramen. For patient in whom the brace would not be applicable, a 3D mandibular model was printed as a PSSD instead. We analyzed 66 patients undergoing TOETVA at our institution from March 2017 to March 2019. The preoperative details and complication profiles were also analyzed. RESULTS: With incorporation of the PSSD into our TOETVA procedure, there have been no cases of MN injury. CONCLUSIONS: Our own TOETVA series has demonstrated that the implementation of the PSSD has been successful in preoperatively identifying and preventing the potential risk of MN injury. Although the additional requirements of preoperative CT and time for fabricating the device impose limitations, the influence of the PSSD in TOETVA is positive.

MicroRNA-23a/27a/24-2 cluster promotes gastric cancer cell proliferation synergistically.

Previous studies have indicated that certain microRNAs (miRNAs/miRs) function as either tumor suppressors or oncogenes in human cancer. The present study identified the miR-23a/27a/24-2 cluster, containing miR-23, miR-27a and miR-24, as an oncogene in gastric cancer. The expression of the miR-23a/27a/24-2 cluster was upregulated in clinical gastric cancer tissues. Transfection with inhibitors of miR-23a, miR-27a, or miR-24, either independently or together, repressed in vitro colony formation and in vivo tumor formation. The miR23a/27a/24-2 cluster inhibitors repressed the growth of gastric cancer cells in a synergistic manner. In addition, treatment with lower doses of the miRNA inhibitor mixture induced the formation of apoptotic bodies. According to computational predictions using TargetScan, suppressor of cytokine-induced signaling 6 (SOCS6) was identified as one of the downstream target genes of the miR-23a/27a/24-2 cluster. The expression of SOCS6 was significantly lower in tumor tissues than in matched normal tissues (P<0.01) and was associated with poor survival (P<0.00001). Taken together, these results strongly suggested that the miR-23a/27a/24-2 cluster may mediate the progression of gastric cancer through the suppression of SOCS6 expression. The present study also provides a novel molecular target for the development of an anti-gastric cancer agent.

Correlation between HGF/c-Met and Notch1 signaling pathways in human gastric cancer cells.

In recent decades, research concerning gastric carcinogenesis has rapidly progressed. It is evident that hepatocyte growth factor (HGF) is clinically related to gastric cancer progression and metastasis. In addition, previous studies have found that expression of Notch ligand Jagged1 is correlated with the poor prognosis of gastric cancer. However, the interaction between the HGF/c-Met and Notch1 signaling pathways remains unknown. In the present study, we found that gastric cancer patients with positive c-Met expression exhibited poorer overall survival than patients without c-Met expression (P=0.043) and that Jagged1 expression was significantly correlated with c-Met expression (r=0.301; P=0.004) in human gastric cancer specimens. In addition, Jagged1 activity increased after HGF stimulation, which in turn increased the downstream expression of cyclooxygenase 2 (COX-2) in a time-dependent manner. After knockdown of Notch1 intracellular domain (N1IC), HGF was found to increase the proliferation and migration ability in human gastric cancer cells. However, overexpression of N1IC still had no effect after HGF stimulation. Our study found a feedback loop between HGF/c-Met and Jagged1/Notch1 signaling. Furthermore, both HGF/c-Met and Notch1 signaling triggered COX-2 activity. These results suggest that gastric cancer progression is not associated with a unique signaling pathway and that a feedback loop may exist between the HGF/c-Met and Notch1 signaling pathways, which may result in therapeutic resistance. Therefore, multi-modality therapies should be considered for treating gastric cancer.

Intracerebroventricular urocortin 3 counteracts central acyl ghrelin-induced hyperphagic and gastroprokinetic effects via CRF receptor 2 in rats.

PURPOSE: Urocortin 3 is a key neuromodulator in the regulation of stress, anxiety, food intake, gut motility, and energy homeostasis, while ghrelin elicits feeding behavior and enhances gastric emptying, adiposity, and positive energy balance. However, the interplays between urocortin 3 and ghrelin on food intake and gastric emptying remain uninvestigated. METHODS: We examined the differential effects of central O-n-octanoylated ghrelin, des-Gln14-ghrelin, and urocortin 3 on food intake, as well as on charcoal nonnutrient semiliquid gastric emptying in conscious rats that were chronically implanted with intracerebroventricular (ICV) catheters. The functional importance of corticotropin-releasing factor (CRF) receptor 2 in urocortin 3-induced responses was examined by ICV injection of the selective CRF receptor 2 antagonist, astressin2-B. RESULTS: ICV infusion of urocortin 3 opposed central acyl ghrelin-elicited hyperphagia via CRF receptor 2 in satiated rats. ICV injection of O-n-octanoylated ghrelin and des-Gln14-ghrelin were equally potent in accelerating gastric emptying in fasted rats, whereas ICV administration of urocortin 3 delayed gastric emptying. In addition, ICV infusion of urocortin 3 counteracted central acyl ghrelin-induced gastroprokinetic effects via CRF receptor 2 pathway. CONCLUSION: ICV-infused urocortin 3 counteracts central acyl ghrelin-induced hyperphagic and gastroprokinetic effects via CRF receptor 2 in rats. Our results clearly showed that enhancing ghrelin and blocking CRF receptor 2 signaling in the brain accelerated gastric emptying, which provided important clues for a new therapeutic avenue in ameliorating anorexia and gastric ileus found in various chronic wasting disorders.

Peroxisome Proliferator-Activated Receptor γ Expression Is Inversely Associated with Macroscopic Vascular Invasion in Human Hepatocellular Carcinoma.

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated nuclear receptor that regulates cellular lipid and glucose metabolism and also plays an inhibitory role in various cancers. However, the role of PPARγ in hepatocellular carcinoma (HCC) remains controversial. This study aimed to investigate the prognostic value of PPARγ in HCC and its role in inhibiting tumor progression, namely, HCC cell growth, migration, and angiogenesis. Immunohistochemical PPARγ staining was examined in 83 HCC specimens to investigate the clinicopathological correlations between PPARγ expression and various parameters. The functional role of PPARγ was determined via PPARγ overexpression and knockdown in HCC cells. Patients with low HCC tissue PPARγ expression were significantly younger (p = 0.006), and exhibited more tumor numbers (p = 0.038), more macroscopic vascular invasion (MVI) (p = 0.008), and more advanced TNM (size of primary tumor, number of regional lymph nodes, and distant metastasis) stages at diagnosis (p = 0.013) than patients with high HCC tissue PPARγ expression. PPARγ knockdown increased HCC cell growth, migration, and angiogenesis, while PPARγ overexpression reduced HCC cell growth, migration, and angiogenesis. These results suggest that low PPARγ expression is an independent predictor of more MVI in HCC patients. PPARγ contributes to the suppression of HCC cell growth, migration, and angiogenesis. Therefore, PPARγ may be a therapeutic target in HCC patients.

Notch1 pathway-mediated microRNA-151-5p promotes gastric cancer progression.

Gastric carcinoma is the third leading cause of lethal cancer worldwide. Previous studies showed that Notch1 receptor intracellular domain (N1IC), the activated form of Notch1 receptor, promotes gastric cancer progression. It has been demonstrated that a significant cross-talk interplays between Notch pathways and microRNAs (miRNAs) in controlling tumorigenesis. This study identified an intronic microRNA-151 (miR-151), which consists of two mature miRNAs, miR-151-3p and miR-151-5p, as a Notch1 receptor-induced miRNA in gastric cancer cells. Activation of Notch1 pathway enhanced expressions of miR-151 and its host gene, focal adhesion kinase (FAK), in gastric cancer cells. The levels of miR-151 in gastric cancer samples were higher than those of adjacent non-tumor samples. Activated Notch1 pathway induced CBF1-dependent FAK promoter activity. The ectopic expression of miR-151 promoted growth and progression of SC-M1 gastric cancer cells including cell viability and colony formation, migration, and invasion abilities. Activated Notch1 pathway could augment progression of gastric cancer cells through miR-151-5p and FAK. The mRNA levels of pluripotency genes, Nanog and SOX-2, tumorsphere formation ability, tumor growth, and lung metastasis of SC-M1 cells were elevated by activated Notch1 pathway through miR-151-5p. Furthermore, miR-151-5p could target 3'-untranslated region (3'-UTR) of p53 mRNA and down-regulate p53 level in SC-M1 cells. Mechanistically, Notch1/miR-151-5p axis contributed to progression of SC-M1 cells through down-regulation of p53 which in turn repressed FAK promoter activity. Taken together, these results suggest that Notch1 pathway and miR-151-5p interplay with p53 in a reciprocal regulation loop in controlling gastric carcinogenesis.

Combined effect of honokiol and rosiglitazone on cell growth inhibition through enhanced G0/G1 phase arrest in hepatoma cells.

BACKGROUND: Honokiol, a derivative extracted from the stem and bark of Magnolia officinalis, has been reported to have anticancer effects in hepatoma cells. Recently, it was found that honokiol acted as not only a retinoid X receptor (RXR) agonist but also as a peroxisome proliferator-activated receptor gamma (PPARγ) agonist. Additionally, honokiol is capable of activating PPARγ/RXR heterodimers synergistically in the presence of rosiglitazone in 3T3-L1 adipocyte and HLE human hepatoma cells. Furthermore, synthetic PPARγ agonist thiazolidinediones exhibited growth inhibition effects in hepatoma cells through PPARγ-dependent and PPARγ-independent pathways. However, the combined effects of treatment with honokiol and PPARγ agonist are unclear in hepatoma cells. METHODS: In this study, sulforhodamine B assay, flow cytometry, and Western blot analysis were used to examine the combined effects of honokiol and PPARγ agonist (rosiglitazone) treatment on growth inhibition in SK-Hep1 and Mahlavu hepatoma cells. RESULTS: Honokiol or rosiglitazone treatment in hepatoma cells induced growth inhibition at high dose by sulforhodamine B assay. Moreover, we found that combined treatment with honokiol and rosiglitazone showed more effective growth inhibition in hepatoma cells than treatment with honokiol or rosiglitazone alone. Also, treatment with honokiol and rosiglitazone induced cell cycle arrest in the G0/G1 phase; increased p21; and decreased cyclin D1, cyclin E1, and Rb expression in SK-Hep1 hepatoma cells. CONCLUSION: Honokiol combined with rosiglitazone showed more effective growth inhibition in hepatoma cells mediated through the regulation of G0/G1 phase-related proteins p21, cyclin D1, cyclin E1, and Rb and cell cycle progression.

Anticolorectal cancer effects and pharmacokinetic application of 2, 2-Bis [4-(4-amino-3-hydroxyphenoxy) phenyl] adamantane.

2, 2-Bis (4-(4-amino-3-hydroxyphenoxy) phenyl) adamantane (DPA) induced growth inhibition in human cancer cells using the national cancer institute (NCI) anticancer drug screen. In our previous study, we demonstrated that DPA exerted growth inhibitory activities in the three human colon cancer cell lines (Colo 205, HT-29, and HCT-15). To identify the detailed mechanism, we examined the functional importance of p21 and p53 in DPA-induced anticancer effect. We used three isogenic colon cancer cell lines, HCT-116, HCT-116 p53(-/-), and HCT-116 p21(-/-), to evaluate the roles of p21 and p53 in the in vitro anticancer effects of DPA. DPA dose-dependently inhibited cell growth, cell migration and increased cell cycle at the G0/G1 phase in HCT116 cells but not in p21(-/-) and p53(-/-) isogenic HCT-116 cells. Additionally, Western blot showed that DPA treatment induced the p21, p53, and cyclin-E protein expressions in HCT-116 cells. The p21 associated cell cycle regulatory protein such as cyclin D, CDK4, and pRb were decreased after DPA treatment in HCT-116 cells. DPA decreased cell migration in HCT-116 and HCT-116 p53(-/-) but not in HCT-116 p21(-/-) cells. We observed the up-regulation of E-cadherin, p-p38, and p-Erk in DPA-treated HCT-116 group but not in HCT-116 p21(-/-) and HCT-116 p53(-/-) groups. We assumed that p21 was required for DPA-induced anti-colon cancer effect through the Erk and p38 pathway leading to cell cycle arrest and inhibition of cell motility. Mean (± SE) pharmacokinetic parameters of the DPA were as follows: AUC = 64.44 ± 8.41, Cmax = 1.56 ± 0.48 and t1/2 = 113.92 ± 58.19. The pharmacokinetic data suggest DPA can be applied to further clinical study. This is the first pharmacokinetic study of DPA, and indicated that anti-proliferation and the cell mobility inhibition effects of DPA in HCT116 WT cells may result from the induction of p21 through activation of ERK and p38 pathway.

Energy metabolism determines the sensitivity of human hepatocellular carcinoma cells to mitochondrial inhibitors and biguanide drugs.

Human hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide particularly in Asia. Deregulation of cellular energetics was recently included as one of the cancer hallmarks. Compounds that target the mitochondria in cancer cells were proposed to have therapeutic potential. Biguanide drugs which inhibit mitochondrial complex I and repress mTOR signaling are clinically used to treat type 2 diabetes mellitus patients (T2DM) and were recently found to reduce the risk of HCC in T2DM patients. However, whether alteration of energy metabolism is involved in regulating the sensitivity of HCC to biguanide drugs is still unclear. In the present study, we treated four HCC cell lines with mitochondrial inhibitors (rotenone and oligomycin) and biguanide drugs (metformin and phenformin), and found that the HCC cells which had a higher mitochondrial respiration rate were more sensitive to these treatments; whereas the HCC cells which exhibited higher glycolysis were more resistant. When glucose was replaced by galactose in the medium, the altered energy metabolism from glycolysis to mitochondrial respiration in the HCC cells enhanced the cellular sensitivity to mitochondrial inhibitors and biguanides. The energy metabolism change enhanced AMP-activated protein kinase (AMPK) activation, mTOR repression and downregulation of cyclin D1 and Mcl-1 in response to the mitochondrial inhibitors and biguanides. In conclusion, our results suggest that increased mitochondrial oxidative metabolism upregulates the sensitivity of HCC to biguanide drugs. Enhancing the mitochondrial oxidative metabolism in combination with biguanide drugs may be a therapeutic strategy for HCC.

The reciprocal regulation loop of Notch2 pathway and miR-23b in controlling gastric carcinogenesis.

Gastric carcinoma is one of the most common malignancies and the third highest cause of global cancer-related death. Notch2 receptor intracellular domain (N2IC), the activated form of Notch2 receptor, enhances gastric carcinogenesis. MicroRNAs (miRNAs) act as either oncogenes or tumor suppressors in tumorigenesis and cross-talk with Notch pathways. Herein, microRNA-23b (miR-23b) was identified as a Notch2 receptor-related miRNA and its role in gastric carcinogenesis was investigated. Levels of miR-23b in stomach adenocarcinoma samples were down-regulated, whereas those of Notch2 receptor, v-ets erythroblastosis virus E26 oncogene homolog 1 (Ets1), and E2F1 transcripts were up-regulated. Results also showed that N2IC down-regulated miR-23b expression in gastric cancer cells through up-regulating E2F1. The miR-23b inhibited gastric tumorigenesis including growth, viability, epithelial-mesenchymal transition, and abilities of colony formation, migration, invasion, and tumorsphere formation. Mechanistically, miR-23b suppressed tumor progression and pluripotency gene expression and affected tumorsphere ultra-structure in gastric cancer cells via targeting Notch2 receptor or Ets1. Furthermore, miR-23b diminished the xenografted tumor growth and lung metastasis of SC-M1 gastric cancer cells through Notch2 pathway. Our results suggest that Notch2 pathway and miR-23b interplay in a reciprocal regulation loop in gastric cancer cells and this axis plays an important role in gastric carcinogenesis.

Krüppel-like factor 4 modulates the migration and invasion of hepatoma cells by suppressing TIMP-1 and TIMP-2.

Krüppel-like factor 4 (KLF4) plays important roles in development, stemness and tumorigenesis; however limited information is available on the detailed function of KLF4 in hepatocellular carcinoma (HCC). The objective of the present study was to examine the functional roles of KLF4 in the metastasis of HCC cells. KLF4 was overexpressed and knocked down by lentiviral transduction method in highly metastatic HCC cells. KLF4 overexpression in HCC cells led to inhibition of cell migration and invasion. These inhibitory effects were associated with the upregulation of tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 by KLF4. Treatment with recombinant TIMP-1 decreased the migratory ability of HCC cells. Moreover, myeloperoxidase (MPO)-TIMP-1/TIMP-2 inactivator counteracted the KLF4-induced inhibition of cell migration/invasion. Consistently, KLF4 knockdown in HCC cells downregulated TIMP-1 and TIMP-2 expression, consequently promoting cell migration and invasion. Furthermore, we found that KLF4 regulated E-cadherin and epithelial-mesenchymal transition (EMT)-related proteins such as snail, vimentin and Bmi1 to modulate the cell migration ability. These results together demonstrated for the first time that KLF4 plays an important role in inhibiting the aggressiveness of HCC cells via upregulation of TIMP-1 and TIMP-2.

Differential modulation of endogenous cannabinoid CB1 and CB2 receptors in spontaneous and splice variants of ghrelin-induced food intake in conscious rats.

OBJECTIVE: Dysregulation of the endocannabinoid system can lead to the development of obesity and metabolic disorders. Endogenous endocannabinoids act on two cannabinoid receptor subtypes, type 1 (CB1) and type 2 (CB2), to exert their biological actions. The aim of this study was to determine whether CB1 and CB2 receptors modulate feeding behavior. METHODS: We investigated the different roles of CB1 and CB2 receptors in spontaneous and centrally administered splice variants of ghrelin, O-n-octanoylated ghrelin and des-Gln(14)-ghrelin, stimulation of food intake in conscious rats. RESULTS: Intraperitoneal (IP) injection of different doses of selective CB2 receptor antagonist AM-630 (0.3, 1, and 3 mg/kg) enhanced cumulative food intake during the first 12 h with a dome-shaped dose-response relationship in freely fed rats, with the most effective dose being 1 mg/kg. In comparison, the selective CB1 receptor antagonist AM-251 (0.3, 1, and 3 mg/kg, IP) dose-dependently suppressed the cumulative food intake in 16-h food-deprived rats. Centrally administered O-n-octanoylated ghrelin and des-Gln(14)-ghrelin-induced hyperphagic effects were counteracted dose-dependently by IP AM-251, but not AM-630. CONCLUSIONS: We demonstrated that the endogenous CB2 receptor plays a role in inhibiting food intake in the satiated state, whereas the CB1 receptor promotes food intake in the fasted condition. The induction of feeding by central acyl ghrelin is a CB1 receptor-dependent mechanism. Differentially nibbling CB1 and CB2 receptor subtypes may provide a new avenue to treating eating and metabolic disorders.

Reduced circulating endothelial progenitor cells in reversible cerebral vasoconstriction syndrome.

BACKGROUND: The pathophysiology of reversible cerebral vasoconstriction syndrome (RCVS) remains elusive. Endothelial dysfunction might play a role, but direct evidence is lacking. This study aimed to explore whether patients with RCVS have a reduced level of circulating circulating endothelial progenitor cells (EPCs) to repair the dysfunctional endothelial vasomotor control. METHODS: We prospectively recruited 24 patients with RCVS within one month of disease onset and 24 healthy age- and sex-matched controls. Flow cytometry was used to quantify the numbers of circulating EPCs, defined as KDR+CD133+, CD34+CD133+, and CD34+KDR+ double-positive mononuclear cells. The Lindegaard index, an index of vasoconstriction, was calculated by measuring the mean flow velocity of middle cerebral arteries and distal extracranial internal carotid arteries via color-coded sonography on the same day as blood drawing. A Lindegaard index of 2 was chosen as the cutoff value for significant vasoconstriction of middle cerebral arteries based on our previous study. RESULTS: Patients with RCVS had a reduced number of CD34+KDR+ cells (0.009 ± 0.006% vs. 0.014 ± 0.010%, p = 0.031) but not KDR+CD133+ cells or CD34+CD133+ EPCs, in comparison with controls. The number of CD34+KDR+ cells was inversely correlated with the Lindegaard index (rs = -0.418, p = 0.047). Of note, compared to controls, patients with a Lindegaard index > 2 (n = 13) had a reduced number of CD34+KDR+ cells (0.007 ± 0.005% vs. 0.014 ± 0.010%, p = 0.010), but those with a Lindegaard index ≤ 2 did not. CONCLUSIONS: Patients with RCVS had reduced circulating CD34+KDR+ EPCs, which were correlated with the severity of vasoconstriction. Endothelial dysfunction might contribute to the pathogenesis of RCVS.

Yin Yang 1 is a target of microRNA-34 family and contributes to gastric carcinogenesis.

Gastric cancer is the second leading cause of cancer-related death worldwide. Herein, we investigated the role of transcription factor Yin Yang 1 (YY1), a multi-functional protein, in tumorigenesis of gastric cancer cells. Results showed that YY1 contributed to gastric carcinogenesis of SC-M1 cells including growth, viability, and abilities of colony formation, migration, invasion, and tumorsphere formation. Levels of pluripotency genes CD44, Oct4, SOX-2, and Nanog were also up-regulated by YY1 in SC-M1 cells. Additionally, the 3'-untranslated region (3'-UTR) of YY1 mRNA was the target of microRNA-34 (miR-34) family consisting of miR-34a, miR-34b, and miR-34c. Overexpression of miR-34 family suppressed carcinogenesis through down-regulation of YY1 in NUGC-3 gastric cancer cells scarcely expressing miR-34 family. Alternatively, knockdown of miR-34 family promoted tumorigenesis via up-regulation of YY1 in SC-M1 and AZ521 gastric cancer cells with higher levels of miR-34 family. The miR-34 family also affected tumorsphere ultra-structure and inhibited the xenografted tumor growth as well as lung metastasis of SC-M1 cells through YY1. Expressions of miR-34a and miR-34c in gastric cancer tissues of patients were lower than those in normal tissues. Taken together, these results suggest that miR-34 family-YY1 axis plays an important role in the control of gastric carcinogenesis.

Somatic alterations in mitochondrial DNA and mitochondrial dysfunction in gastric cancer progression.

Energy metabolism reprogramming was recently identified as one of the cancer hallmarks. One of the underlying mechanisms of energy metabolism reprogramming is mitochondrial dysfunction caused by mutations in nuclear genes or mitochondrial DNA (mtDNA). In the past decades, several types of somatic mtDNA alterations have been identified in gastric cancer. However, the role of these mtDNA alterations in gastric cancer progression remains unclear. In this review, we summarize recently identified somatic mtDNA alterations in gastric cancers as well as the relationship between these alterations and the clinicopathological features of gastric cancer. The causative factors and potential roles of the somatic mtDNA alterations in cancer progression are also discussed. We suggest that point mutations and mtDNA copy number decreases are the two most common mtDNA alterations that result in mitochondrial dysfunction in gastric cancers. The two primary mutation types (transition mutations and mononucleotide or dinucleotide repeat instability) imply potential causative factors. Mitochondrial dysfunction-generated reactive oxygen species may be involved in the malignant changes of gastric cancer. The search for strategies to prevent mtDNA alterations and inhibit the mitochondrial retrograde signaling will benefit the development of novel treatments for gastric cancer and other malignancies.

SIRT3 expression as a biomarker for better prognosis in gastric cancer.

BACKGROUND: SIRT3-mitochondrial nicotinamide adenine dinucleotide-dependent deacetylase sirtuin-3-plays an important role in regulating cell metabolism and carcinogenesis. The role of SIRT3 in gastric cancer has not yet been investigated. METHODS: A total of 221 gastric cancer patients who underwent curative surgery were enrolled at the Department of Surgery, Taipei Veterans General Hospital. SIRT3 expression in gastric tissues and tumors were examined in these patients using immunohistochemical staining. Clinicopathologic characteristics and survival were analyzed and compared in gastric cancer patients with or without SIRT3 expression. RESULTS: The 5-year survival rates of patients with or without SIRT3 expression were 51.2 and 39.1 %, respectively (p = 0.005). The 5-year disease-free survival rates of patients with or without SIRT3 expression were 49.6 and 38.0 %, respectively (p = 0.010). Microscopic features showed that there are more poor cell differentiation (p = 0.001), more diffuse-type Lauren's histology (p = 0.018), and more scirrhous-type stromal reactions (p = 0.027) in gastric cancer without SIRT expression. Multivariate analysis with overall survival as an endpoint showed that age (p < 0.001), Lauren's histology (p = 0.007), stromal reaction (p = 0.035), TNM pathologic N category (p < 0.001), and SIRT3 expression (p < 0.001) were significantly correlated with gastric cancer. CONCLUSIONS: Gastric cancer patients with SIRT3 expression have a better prognosis than those without. SIRT3 expression is an independent prognostic marker for overall survival and may act as a tumor suppressor in gastric cancer.

Emerging role of the peroxisome proliferator-activated receptor-gamma in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the major leading cause of cancer death worldwide. Hepatitis B virus, hepatitis C virus, alcohol consumption, non-alcoholic fatty liver disease, and diabetes are the major risks for developing HCC. Until now, recurrence and metastasis are the major cause of death in HCC patients. Therefore, identification of new effective molecular targets is an urgent need for treatment of HCC. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated nuclear receptor which could be activated by PPARγ agonists such as thiazolidinediones, and natural PPARγ ligand (such as 15-deoxy-Δ12,14-prostaglandin J2, 15d-PGJ2). Increasing in vitro and in vivo evidence has demonstrated that PPARγ agonists exhibit an inhibitory role on tumor cell growth, migration, and invasion, suggesting that PPARγ activation may play an important role in the regulation of growth of HCC. It has been reported that PPARγ activation by thiazolidinediones or overexpression of PPARγ by virus-mediated gene transfer has shown growth inhibitory effects in hepatoma cells, but the expression level of PPARγ in HCC tissues still remains conflicting. Notably, a novel PPARγ agonist, honokiol, has recently been found to activate the PPARγ/RXR heterodimer, and has also exhibited significant anti-cancer effects in hepatoma cells. In the present review, we summarized studies on the role and the molecular regulation of PPARγ in HCC development in vitro and in vivo. PPARγ has the potential to be a therapeutic target for future treatment of HCC.

Downregulation of tumor suppressor MBP-1 by microRNA-363 in gastric carcinogenesis.

Gastric carcinoma is one of the most common malignancies and the second most lethal cancer worldwide. The mechanisms underlying aggressiveness of gastric cancer still remain obscure. c-Myc promoter binding protein 1 (MBP-1) is a negative regulator of c-myc expression and ubiquitously expressed in normal human tissues. It is produced by alternative translation initiation of α-enolase gene. Both MBP-1 and α-enolase are involved in the control of tumorigenesis including gastric cancer. MicroRNAs (miRNAs) are involved in tumorigenesis and could have diagnostic, prognostic and therapeutic potential. In this study, whether miRNAs modulate tumorigenesis of gastric cancer cells through targeting MBP-1 was evaluated. We found that miR-363 targets 3'-untranslated region of human MBP-1/α-enolase messenger RNA. The exogenous miR-363 promotes growth, viability, progression, epithelial-mesenchymal transition and tumorsphere formation of SC-M1 gastric cancer cells through downregulation of MBP-1, whereas the knockdown of endogenous miR-363 suppresses tumorigenesis and progression of SC-M1 cells via upregulation of MBP-1. The miR-363/MBP-1 axis is also involved in the control of carcinogenesis in KATO III and SNU-16 gastric cancer cells. Furthermore, miR-363 induces the xenografted tumor growth and lung metastasis of SC-M1 cells through MBP-1 in vivo. Taken together, these results suggest that miR-363 plays an important role in the increment of gastric carcinogenesis via targeting MBP-1.

Andrographolide downregulates the v-Src and Bcr-Abl oncoproteins and induces Hsp90 cleavage in the ROS-dependent suppression of cancer malignancy.

Andrographolide is a diterpenoid compound isolated from Andrographis paniculata that exhibits anticancer activity. We previously reported that andrographolide suppressed v-Src-mediated cellular transformation by promoting the degradation of Src. In the present study, we demonstrated the involvement of Hsp90 in the andrographolide-mediated inhibition of Src oncogenic activity. Using a proteomics approach, a cleavage fragment of Hsp90α was identified in andrographolide-treated cells. The concentration- and time-dependent induction of Hsp90 cleavage that accompanied the reduction in Src was validated in RK3E cells transformed with either v-Src or a human truncated c-Src variant and treated with andrographolide. In cancer cells, the induction of Hsp90 cleavage by andrographolide and its structural derivatives correlated well with decreased Src levels, the suppression of transformation, and the induction of apoptosis. Moreover, the andrographolide-induced Hsp90 cleavage, Src degradation, inhibition of transformation, and induction of apoptosis were abolished by a ROS inhibitor, N-acetyl-cysteine. Notably, Hsp90 cleavage, decreased levels of Bcr-Abl (another known Hsp90 client protein), and the induction of apoptosis were also observed in human K562 leukemia cells treated with andrographolide or its active derivatives. Together, we demonstrated a novel mechanism by which andrographolide suppressed cancer malignancy that involved inhibiting Hsp90 function and reducing the levels of Hsp90 client proteins. Our results broaden the molecular basis of andrographolide-mediated anticancer activity.