Targeting ROS production through inhibition of NADPH oxidases.

NADPH oxidases (NOXs) are transmembrane enzymes that are devoted to the production of reactive oxygen species (ROS). In cancers, dysregulation of NOX enzymes affects ROS production, leading to redox unbalance and tumor progression. Consequently, NOXs are a drug target for cancer therapeutics, although current therapies have off-target effects: there is a need for isoenzyme-selective inhibitors. Here, we describe fully validated human NOX inhibitors, obtained from an in silico screen, targeting the active site of Cylindrospermum stagnale NOX5 (csNOX5). The hits are validated by in vitro and in cellulo enzymatic and binding assays, and their binding modes to the dehydrogenase domain of csNOX5 studied via high-resolution crystal structures. A high-throughput screen in a panel of cancer cells shows activity in selected cancer cell lines and synergistic effects with KRAS modulators. Our work lays the foundation for the development of inhibitor-based methods for controlling the tightly regulated and highly localized ROS sources.

Allosteric Regulation of Switch-II Domain Controls KRAS Oncogenicity.

RAS proteins are GTPases that regulate a wide range of cellular processes. RAS activity is dependent on its nucleotide-binding status, which is modulated by guanine nucleotide exchange factors (GEF) and GTPase-activating proteins (GAP). KRAS can be acetylated at lysine 104 (K104), and an acetylation-mimetic mutation of K104 to glutamine (K104Q) attenuates the in vitro-transforming capacity of oncogenic KRAS by interrupting GEF-induced nucleotide exchange. To assess the effect of this mutation in vivo, we used CRISPR-Cas9 to generate mouse models carrying the K104Q point mutation in wild-type and conditional KrasLSL-G12D alleles. Homozygous animals for K104Q were viable, fertile, and arose at the expected Mendelian frequency, indicating that K104Q is not a complete loss-of-function mutation. Consistent with our previous findings from in vitro studies, however, the oncogenic activity of KRASG12D was significantly attenuated by mutation at K104. Biochemical and structural analysis indicated that the G12D and K104Q mutations cooperate to suppress GEF-mediated nucleotide exchange, explaining the preferential effect of K104Q on oncogenic KRAS. Furthermore, K104 functioned in an allosteric network with M72, R73, and G75 on the α2 helix of the switch-II region. Intriguingly, point mutation of glycine 75 to alanine (G75A) also showed a strong negative regulatory effect on KRASG12D. These data demonstrate that lysine at position 104 is critical for the full oncogenic activity of mutant KRAS and suggest that modulating the sites in its allosteric network may provide a unique therapeutic approach in cancers expressing mutant KRAS. SIGNIFICANCE: An allosteric network formed by interaction between lysine 104 and residues in the switch-II domain is required for KRAS oncogenicity, which could be exploited for developing inhibitors of the activated oncoprotein.

Regulation of GTPase function by autophosphorylation.

A unifying feature of the RAS superfamily is a conserved GTPase cycle by which these proteins transition between active and inactive states. We demonstrate that autophosphorylation of some GTPases is an intrinsic regulatory mechanism that reduces nucleotide hydrolysis and enhances nucleotide exchange, altering the on/off switch that forms the basis for their signaling functions. Using X-ray crystallography, nuclear magnetic resonance spectroscopy, binding assays, and molecular dynamics on autophosphorylated mutants of H-RAS and K-RAS, we show that phosphoryl transfer from GTP requires dynamic movement of the switch II region and that autophosphorylation promotes nucleotide exchange by opening the active site and extracting the stabilizing Mg2+. Finally, we demonstrate that autophosphorylated K-RAS exhibits altered effector interactions, including a reduced affinity for RAF proteins in mammalian cells. Thus, autophosphorylation leads to altered active site dynamics and effector interaction properties, creating a pool of GTPases that are functionally distinct from their non-phosphorylated counterparts.

Notch3 signaling-mediated melanoma-endothelial crosstalk regulates melanoma stem-like cell homeostasis and niche morphogenesis.

Melanoma is among the most virulent cancers, owing to its propensity to metastasize and its resistance to current therapies. The treatment failure is largely attributed to tumor heterogeneity, particularly subpopulations possessing stem cell-like properties, ie, melanoma stem-like cells (MSLCs). Evidence indicates that the MSLC phenotype is malleable and may be acquired by non-MSLCs through phenotypic switching upon appropriate stimuli, the so-called 'dynamic stemness'. Since the phenotypic characteristics and functional integrity of MSLCs depend on their vascular niche, using a two-dimensional (2D) melanoma-endothelium co-culture model, where the MSLC niche is recapitulated in vitro, we identified Notch3 signaling pathway as a micro-environmental cue governing MSLC phenotypic plasticity via pathway-specific gene expression arrays. Accordingly, lentiviral shRNA-mediated Notch3 knockdown (KD) in melanoma cell lines exhibiting high levels of endogenous Notch3 led to retarded/abolished tumorigenicity in vivo through both depleting MSLC fractions, evinced by MSLC marker downregulation (eg, CD133 and CD271); and impeding the MSLC niche, corroborated by the attenuated tumor angiogenesis as well as vasculogenic mimicry. In contrast, Notch3 KD affected neither tumor growth nor MSLC subsets in a melanoma cell line with relatively low endogenous Notch3 expression. Thus, Notch3 signaling may facilitate MSLC plasticity and niche morphogenesis in a cell context-dependent manner. Our findings illustrate Notch3 as a molecular switch driving melanoma heterogeneity, and provide the biological rationale for Notch inhibition as a promising therapeutic option.

The associations between apolipoprotein B, A1, and the B/A1 ratio and nonalcoholic fatty liver disease in both normal-weight and overweight Korean population.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is associated with a higher risk of cardiovascular disease, but the relationship has not been established in nonobese populations. Higher apolipoprotein B (apo B) levels and the apo B/A1 ratio and lower apo A1 levels are associated with an elevated risk of cardiovascular disease. We investigated the associations between apo B, apo A1, and the apo B/A1 ratio and the presence of metabolic syndrome and NAFLD in both normal-weight and overweight Koreans. METHODS: This cross-sectional study consisted of 8327 consecutive both normal-weight and overweight Koreans with NAFLD diagnosed by ultrasonography at the Samsung Medical Center in Korea from January 2008 to December 2010. RESULTS: The prevalence of NAFLD was 27.1% among the 8327 participants. Higher serum triglyceride levels and the apo B/A1 ratio and lower high-density lipoprotein cholesterol and apo A1 levels were significantly associated with higher prevalence of metabolic syndrome in both normal-weight group and overweight group. The multivariate-adjusted odds ratios (ORs) for NAFLD in normal-weight group after comparing the fourth vs the first quartiles of the triglyceride, HDL cholesterol, low-density lipoprotein (LDL) cholesterol, apo B, apo A1, and the apo B/A1 ratio data were 2.89 (95% confidence interval [CI], 2.19-3.83; P trend < .001), 0.60 (95% CI, 0.46-0.78; P trend < .001), 1.67 (95% CI, 1.33-2.11; P trend < .001), 1.88 (95% CI, 1.48-2.39; P trend < .001), 0.73 (95% CI, 0.58-0.93; P trend < .001), and 1.86 (95% CI, 1.45-2.38; P trend < .001), respectively. The corresponding adjusted ORs in the overweight group were 3.43 (95% CI, 2.60-4.54; P trend < .001), 0.89 (95% CI, 0.68-1.16; P trend = .221), 1.41 (95% CI, 1.11-1.78; P trend = .001), 1.58 (95% CI, 1.21-2.06; P trend < .001), 0.99 (95% CI, 0.77-1.27; P trend = .958), and 1.53 (1.16-2.01; P trend = .002), respectively. CONCLUSIONS: Higher serum triglyceride, LDL cholesterol, apo B1 levels, and the apo B/A1 ratio were significantly associated with NAFLD independent of metabolic syndrome in both normal-weight and overweight Koreans. Lower serum HDL cholesterol and apo A1 levels were related to NAFLD in normal-weight participants. Our results suggest that the presence of NAFLD may be associated with increased risk for coronary artery disease in both normal-weight and overweight Koreans.

The Prevalence of Toxocariasis and Diagnostic Value of Serologic Tests in Asymptomatic Korean Adults.

PURPOSE: Toxocariasis is the most common cause of peripheral blood eosinophilia in Korea and produces eosinophilic infiltration in various organs, including the lung. However, the prevalence of toxocariasis in the general population is rarely reported. METHODS: We investigated the seroprevalence of Toxocara larval antibody among asymptomatic people who attended Samsung Medical Center for a health checkup, including low-dose chest computed tomography (CT) between March 2012 and December 2013. A total of 633 people (400 men and 233 women) were prospectively recruited. RESULTS: The Toxocara-seropositive rate was 51.2% using the current cutoff value based on Toxocara enzyme-linked immunosorbent assay (ELISA) (67.0% for men and 24.0% for women). In the multivariate-adjusted model, age (odds ratio [OR], 1.08; 95% confidence intervals [CI], 1.04-1.11), male sex (OR, 3.47; 95% CI, 2.26-5.33), rural residence (OR, 1.55; 95% CI, 1.05-2.30), and history of raw liver intake (OR, 8.52; 95% CI, 3.61-20.11) were significantly associated with Toxocara seropositivity. When subjects were divided into 3 groups using cutoff values base on weak positive and strong positive control optical densities (ODs), the ORs for peripheral blood eosinophilia and serum hyperIgEaemia were 0.31 (95% CI, 0.02-2.89) in the weakpositive group and 36.64 (95% CI, 11.73-111.42) in the strong positive group compared to the seronegative group. Similarly, ORs for the solid nodule with surrounding halo were 2.54 (95% CI, 0.60-10.84) in the weak positive group and 15.08 (95 CI 4.09-55.56) in the strong positive group compared to the seronegative group. CONCLUSIONS: The study indicated that the Toxocara-seropositive rate obtained by using the current cutoff value based on ELISA was high in the asymptomatic population in Korea. The results of this study suggest that active toxocariasis may be more frequently seen in the Toxocara-strong positive group than in the Toxocara-weak positive group.

Induction of Vasculogenic Mimicry Overrides VEGF-A Silencing and Enriches Stem-like Cancer Cells in Melanoma.

The basis for resistance to VEGF inhibition is not fully understood despite its clinical importance. In this study, we examined the adaptive response to VEGF-A inhibition by a loss-of-function analysis using plasmid-based shRNA. Tumor xenografts that initially responded to VEGF-A inhibition underwent an adaptation in vivo, leading to acquired resistance. VEGF-A blockade in tumors was associated with HIF1α expression and an increase in CD144(+) vasculogenic mimicry (VM), leading to formation of channels displaying Tie-1 and MMP-2 upregulation. CD133(+) and CD271(+) melanoma stem-like cells (MSLC) accumulated in the perivascular niche. Tumor xenografts of melanoma cell populations that were intrinsically resistant to VEGF-A blockade did not exhibit any of these features, compared with nontarget control counterparts. Thus, melanomas that are initially sensitive to VEGF-A blockade acquire adaptive resistance by adopting VM as an alternate angiogenic strategy, thereby enriching for deposition of MSLC in the perivascular niche through an HIF1α-dependent process. Conversely, melanomas that are intrinsically resistant to VEGF-A blockade do not show any evidence of compensatory survival mechanisms that promote MSLC accumulation. Our work highlights the potential risk of anti-VEGF treatments owing to a selective pressure for an adaptive resistance mechanism that empowers the development of stem-like cancer cells, with implications for how to design combination therapies that can improve outcomes in patients.

KML001 enhances anticancer activity of gemcitabine against pancreatic cancer cells.

BACKGROUND/AIM: Gemcitabine is a drug commonly used to treat pancreatic cancer but chemoresistance to it is a common clinical issue. KML001 (sodium meta-arsenite) has demonstrated certain antitumor activity. The objective of the study was to evaluate the influence of KML001 on the anticancer activity of gemcitabine against pancreatic cancer cells. MATERIALS AND METHODS: Cell proliferation, migration, and invasion were assessed, as well as the expression of nuclear factor-kappa B (NF-κB) p65, epidermal growth factor receptor (EGFR), matrix metalloproteinase-2 (MMP2), and vascular endothelial growth factor-C (VEGFC) in pancreatic cancer cells. RESULTS: Treatment with a combination of KML001 and gemcitabine resulted in significant inhibition of cell proliferation, migration, and invasion, and significantly reduced EGFR and MMP2 expression compared to gemcitabine treatment-alone. CONCLUSION: Combination treatment of gemcitabine and KML001 could be an effective chemotherapeutic treatment for pancreatic cancer.

KML001 inhibits cell proliferation and invasion in pancreatic cancer cells through suppression of NF-κB and VEGF-C.

Pancreatic cancer is an aggressive malignancy with poor prognosis and the efficacy of chemotherapy is limited. KML001 (sodium meta-arsenite) has been demonstrated to have anticancer activity against some solid cancer cells. The aim of the present study was to determine the effect of KML001 on cell proliferation, migration, and invasion of pancreatic cancer cells. The Dojindo Cell Counting Kit-8 assay was used to determine the inhibition of pancreatic cancer cell proliferation by drugs. Cell migration and invasion were examined using 24-well inserts and Matrigel™-coated invasion chambers. The activity of nuclear factor-kappa B (NF-κB) p65, vascular endothelial growth factor-C (VEGF-C), and matrix metalloproteinase-9 (MMP-9) were measured by enzyme-linked immunosorbent assay (ELISA). KML001 inhibited the proliferation of pancreatic cancer cells in a dose- and time-dependent manner. KML001 also inhibited the migration and invasion of pancreatic cancer cells in a dose-dependent manner. KML001 significantly decreased NF-κB p65 and VEGF-C activities in the pancreatic cancer cells. KML001 inhibited cell proliferation, migration, and invasion in pancreatic cancer cells. Suppression of NF-κB and VEGF-C activation may partly be associated with the anticancer activity of KML001. These results suggest that KML001 could be a novel potential therapeutic agent for treatment of pancreatic cancer.

CD133-targeted niche-dependent therapy in cancer: a multipronged approach.

Cancer treatment continues to be challenged by the development of therapeutic resistances and relapses in the clinical setting, which are largely attributed to tumor heterogeneity, particularly the existence of cancer stem cells (CSCs). Thus, targeting the CSC subpopulation may represent an effective therapeutic strategy. However, despite advances in identifying and characterizing CD133(+) CSCs in various human cancers, efforts to translate these experimental findings to clinical modalities have been slow in the making, especially in light of the growing awareness of CSC plasticity and the foreseeable pitfall of therapeutically targeting CSC base sorely on a surface marker. We, and others, have demonstrated that the CD133(+) CSCs reside in complex vascular niches, where reciprocal signaling between the CD133(+) CSCs and their microenvironment may govern niche morphogenesis and homeostasis. Herein, we discuss the multifaceted functional role of the CD133(+) cells in the context of their niche, and the potential of targeting CD133 as a niche-dependent approach in effective therapy.

Association between markers of glucose metabolism and risk of colorectal adenoma.

BACKGROUND & AIMS: Diabetes is a risk factor for colorectal cancer. We studied the association between markers of glucose metabolism and metabolic syndrome and the presence of colorectal adenomas in a large number of asymptomatic men and women attending a health screening program in South Korea. We also investigated whether these associations depend on adenoma location. METHODS: In a cross-sectional study, we measured fasting levels of glucose, insulin, hemoglobin A1c, and C-peptide and calculated homeostatic model assessment (HOMA) values (used to quantify insulin resistance) for 19,361 asymptomatic South Korean subjects who underwent colonoscopy examinations from January 2006 to June 2009. Participants completed a standardized self-administered health questionnaire and a validated semiquantitative food frequency questionnaire. Blood samples were collected on the day of the colonoscopy; fasting blood samples were also collected. Robust Poisson regression was used to model the associations of glucose markers with the prevalence of any adenoma. RESULTS: Using detailed multivariable-adjusted dose-response models, the prevalence ratios (aPR, 95% confidence interval [CI]) for any adenoma, comparing the 90th with the 10th percentile, were 1.08 (1.00-1.16; P = .04) for fasting glucose, 1.07 (0.99-1.15; P = .10) for insulin, 1.09 (1.02-1.18, P = .02) for HOMA, 1.09 (1.01-1.17; P = .02) for hemoglobin A1c, and 1.14 (1.05-1.24; P = .002) for C-peptide. The corresponding ratios for nonadvanced adenomas were 1.11 (0.99-1.25; P = .08), 1.10 (0.98-1.24; P = .12), 1.15 (1.02-1.29; P = .02), 1.14 (1.01-1.28; P = .03), and 1.20 (1.05-1.37; P = .007), respectively. The corresponding ratios for advanced adenomas were 1.32 (0.94-1.84; P = .11), 1.23 (0.87-1.75; P = .24), 1.30 (0.92-1.85; P = .14), 1.13 (0.79-1.61; P = .50), and 1.67 (1.15-2.42; P = .007), respectively. Metabolic syndrome was associated with the prevalence of any adenoma (aPR, 1.18; 95% CI, 1.13-1.24; P < .001), nonadvanced adenoma (aPR, 1.30; 95% CI, 1.20-1.40; P < .001), and advanced adenoma (aPR, 1.42; 95% CI, 1.14-1.78; P = .002). Associations were similar for adenomas located in the distal versus proximal colon. CONCLUSIONS: Increasing levels of glucose, HOMA values, levels of hemoglobin A1c and C-peptide, and metabolic syndrome are significantly associated with the prevalence of adenomas. Adenomas should be added to the list of consequences of altered glucose metabolism.

The prevalence of colorectal adenomas in asymptomatic Korean men and women.

BACKGROUND: Colorectal cancer incidence is rapidly rising in many Asian countries, with rates approaching those of Western countries. This study aimed to evaluate the prevalence and trends of colorectal adenomas by age, sex, and risk strata in asymptomatic Koreans. METHODS: Cross-sectional study of 19,372 consecutive participants aged 20 to 79 years undergoing screening colonoscopy at the Center for Health Promotion of the Samsung Medical Center in Korea from January 2006 to June 2009. RESULTS: Among participants at average risk, those without a history of colorectal polyps or a family history of colorectal cancer, the prevalence of colorectal adenomas and advanced adenomas were 34.5% and 3.1%, respectively, in men and 20.0% and 1.6%, respectively, in women. The prevalence of adenomas increased with age in both men and women, with a more marked increase for advanced adenoma. Participants with a family history of colorectal cancer or with a history of colorectal polyps had significantly higher prevalence of adenomas compared with participants of average risk (36.9% vs. 26.9%; age- and sex-adjusted prevalence ratio = 1.16; 95% confidence interval, 1.09-1.22). The prevalence of adenomas increased annually in both men and women. CONCLUSIONS: In this large study of asymptomatic Korean men and women participating in a colonoscopy screening program, the prevalence of colorectal adenomas was comparable and possibly higher than previously reported in Western countries. IMPACT: Cost-effectiveness studies investigating the optimal age for starting colonoscopy screening and etiological studies to identify the reasons for the increasing trend in colorectal adenomas in Koreans are needed.

The association between cecal insertion time and colorectal neoplasm detection.

BACKGROUND: Information on the impact of cecal insertion time on colorectal neoplasm detection is limited. Our objective was to determine the association between cecal insertion time and colorectal neoplasm detection rate in colonoscopy screening. METHODS: We performed a cross-sectional study of 12,679 consecutive subjects aged 40-79 years undergoing screening colonoscopy in routine health check-ups at the Center for Health Promotion of the Samsung Medical Center from December 2007 to June 2009. Fixed effects logistic regression conditioning on colonoscopist was used to eliminate confounding due to differences in technical ability and other characteristics across colonoscopists. RESULTS: The mean cecal insertion time was 5.9 (SD, 4.4 minutes). We identified 4,249 (33.5%) participants with colorectal neoplasms, of whom 1,956 had small single adenomas (<5 mm), 595 had medium single adenomas (5-9 mm), and 1,699 had multiple adenomas or advanced colorectal neoplasms. The overall rates of colorectal neoplasm detection by quartiles of cecal insertion time were 36.8%, 33.4%, 32.7%, and 31.0%, respectively (p trend <0.001).The odds for small single colorectal adenoma detection was 16% lower (adjusted OR 0.84; 95% CI 0.71 to 0.99) in the fourth compared to the first quartile of insertion time (p trend 0.005). Insertion time was not associated with the detection rate of single adenomas ≥5 mm, multiple adenomas or advanced colorectal neoplasms. CONCLUSION: Shorter insertion times were associated with increased rates of detection of small colorectal adenomas <5 mm. Cecal insertion time may be clinically relevant as missed small colorectal adenomas may progress to more advanced lesions.

HDAC6 and SIRT2 regulate the acetylation state and oncogenic activity of mutant K-RAS.

UNLABELLED: Activating point mutations in K-RAS are extremely common in cancers of the lung, colon, and pancreas and are highly predictive of poor therapeutic response. One potential strategy for overcoming the deleterious effects of mutant K-RAS is to alter its posttranslational modification. Although therapies targeting farnesylation have been explored, and have ultimately failed, the therapeutic potential of targeting other modifications remains to be seen. Recently, it was shown that acetylation of lysine 104 attenuates K-RAS transforming activity by interfering with GEF-induced nucleotide exchange. Here, the deacetylases HDAC6 and SIRT2 were shown to regulate the acetylation state of K-RAS in cancer cells. By extension, inhibition of either of these enzymes has a dramatic impact on the growth properties of cancer cells expressing activation mutants of K-RAS. These results suggest that therapeutic targeting of HDAC6 and/or SIRT2 may represent a new way to treat cancers expressing mutant forms of K-RAS. IMPLICATIONS: This study suggests that altering K-RAS acetylation is a feasible approach to limiting tumorigenic potential.

The association of serum lipids with colorectal adenomas.

OBJECTIVES: There is suggestive but sparse evidence that dyslipidemia is associated with colorectal neoplasms. We investigated the association of serum lipid and apolipoprotein concentrations with the prevalence of colorectal adenomas. METHODS: Cross-sectional study of 19,281 consecutive participants aged 40-79 years undergoing screening colonoscopy at the Center for Health Promotion of the Samsung Medical Center in Korea from January 2006 to June 2009. RESULTS: We identified 5,958 participants with colorectal adenomas (30.9%), including 5,504 (28.5%) with non-advanced adenomas and 454 (2.4%) with advanced adenomas. The adjusted relative prevalence ratios (aRPRs) comparing the fourth with the first quartiles of serum triglycerides were 1.35 (95% confidence interval (CI) 1.20-1.52; P trend<0.001) for non-advanced adenomas and 1.45 (95% CI 1.02-2.06; P trend=0.005) for advanced adenomas. Higher levels of high-density lipoprotein (HDL) cholesterol and apolipoprotein A-1 (ApoA-1) were significantly associated with 12% (Q4 vs. Q1 aRPR 1.12; 95% CI 1.00-1.26; P trend=0.049) and 17% (Q4 vs. Q1 aRPR 1.17; 95% CI 1.04-1.31; P trend=0.004) higher prevalence of non-advanced adenoma. There was also a non-significant association between higher levels of low-density lipoprotein (LDL) cholesterol (Q4 vs. Q1 aRPR 1.22; 95% CI 0.91-1.66; P trend= 0.12) and apolipoprotein B (ApoB) (Q4 vs. Q1 aRPR 1.32; 95% CI 0.94-1.83; P trend=0.07) with higher prevalence of advanced adenoma. There was no association between total cholesterol levels with colorectal adenoma. CONCLUSIONS: In this large cross-sectional study, higher levels of serum triglycerides were significantly associated with an increasing prevalence of both non-advanced and advanced colorectal adenomas, while higher levels of ApoA-1 and HDL cholesterol were significantly associated with an increasing prevalence of non-advanced adenomas.

Differential Expression of PKD2-Associated Genes in Autosomal Dominant Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by formation of multiple fluid-filled cysts that expand over time and destroy renal architecture. The proteins encoded by the PKD1 and PKD2 genes, mutations in which account for nearly all cases of ADPKD, may help guard against cystogenesis. Previously developed mouse models of PKD1 and PKD2 demonstrated an embryonic lethal phenotype and massive cyst formation in the kidney, indicating that PKD1 and PKD2 probably play important roles during normal renal tubular development. However, their precise role in development and the cellular mechanisms of cyst formation induced by PKD1 and PKD2 mutations are not fully understood. To address this question, we presently created Pkd2 knockout and PKD2 transgenic mouse embryo fibroblasts. We used a mouse oligonucleotide microarray to identify messenger RNAs whose expression was altered by the overexpression of the PKD2 or knockout of the Pkd2. The majority of identified mutations was involved in critical biological processes, such as metabolism, transcription, cell adhesion, cell cycle, and signal transduction. Herein, we confirmed differential expressions of several genes including aquaporin-1, according to different PKD2 expression levels in ADPKD mouse models, through microarray analysis. These data may be helpful in PKD2-related mechanisms of ADPKD pathogenesis.

Guggulsterone enhances antitumor activity of gemcitabine in gallbladder cancer cells through suppression of NF-κB.

PURPOSE: Patients with gallbladder cancer usually have a poor prognosis, and effective standard chemotherapeutic regimens have not been established. The anticancer activities of guggulsterone have been demonstrated in various cancer cells. The aims of the study were to determine the effect of guggulsterone on gallbladder cancer cells and to investigate whether treatment with guggulsterone influences the antitumor activities of gemcitabine. METHODS: The Dojindo Cell Counting Kit-8 assay was used to determine the inhibition of proliferation by drugs in TGBC1 and TGBC2 cells. Cell migration and invasion were examined using 24-well inserts and Matrigel™-coated invasion chambers. The activities of NF-κB p65, VEGF-C, and MMP-2 were measured by ELISA. RESULTS: Guggulsterone inhibited the proliferation and suppressed migration and invasion of gallbladder cancer cells in a dose-dependent manner. Guggulsterone significantly decreased NF-κB p65, VEGF-C, and MMP-2 activities in the gallbladder cancer cells examined. Gallbladder cancer cells treated with a combination of guggulsterone and gemcitabine demonstrated significant inhibition of cell proliferation and invasion when compared to treatment with gemcitabine alone. In addition, NF-κB p65 activation decreased significantly in cells treated with a combination of guggulsterone and gemcitabine when compared to treatment with gemcitabine alone. CONCLUSIONS: Guggulsterone exhibits anticancer activities and enhances the antitumor activities of gemcitabine through the suppression of NF-κB activation in gallbladder cancer cells. These results suggest that guggulsterone could be a potential therapeutic option for patients with gallbladder cancer.

Regulation of RAS oncogenicity by acetylation.

Members of the RAS small GTPase family regulate cellular responses to extracellular stimuli by mediating the flux through downstream signal transduction cascades. RAS activity is strongly dependent on its subcellular localization and its nucleotide-binding status, both of which are modulated by posttranslational modification. We have determined that RAS is posttranslationally acetylated on lysine 104. Molecular dynamics simulations suggested that this modification affects the conformational stability of the Switch II domain, which is critical for the ability of RAS to interact with guanine nucleotide exchange factors. Consistent with this model, an acetylation-mimetic mutation in K-RAS4B suppressed guanine nucleotide exchange factor-induced nucleotide exchange and inhibited in vitro transforming activity. These data suggest that lysine acetylation is a negative regulatory modification on RAS. Because mutations in RAS family members are extremely common in cancer, modulation of RAS acetylation may constitute a therapeutic approach.

Is gynecological cancer a new indication for surveillance colonoscopy in Korea?

BACKGROUND/AIMS: Previous studies regarding the risk for colorectal neoplasms in women with a prior diagnosis of gynecological cancer have revealed conflicting results. Therefore, we conducted a cross-sectional study to quantify the risk for colorectal neoplasms in patients with gynecological cancers. METHODOLOGY: A total of 4613 women (including 27, 51 and 92 women with a prior diagnosis of endometrial, ovarian and cervical cancers, respectively) >20 years of age were recruited prospectively from 9 tertiary medical centers in Korea between January 2008 and February 2009. All participants underwent complete colonoscopies for vague abdominal signs or symptoms or for colorectal cancer screening. Several risk factors for colorectal neoplasms and a prior history of gynecological cancer were compared between women with and without colorectal neoplasms. RESULTS: The risk for colorectal neoplasms was only elevated among women with previous endometrial cancer, but with ovarian or cervical cancer, particularly when diagnosed at <50 years of age (adjusted OR=3.7; 95% CI=1.0-13.3, p=0.016). CONCLUSIONS: This study demonstrated a higher risk for colorectal neoplasms in women with previous endometrial cancer, particularly when diagnosed at <50 years of age. Greater emphasis on colorectal cancer screening in this population may be necessary.

Do we need colonoscopy in patients with gastric adenomas? The risk of colorectal adenoma in patients with gastric adenomas.

BACKGROUND: Gastric polyps are found frequently in various colonic polyposis syndromes. Genetic alterations of several genes occur in gastric adenomas and colorectal adenomas. However, it is unknown whether patients with gastric adenomas are at higher risk for colorectal adenomas. OBJECTIVE: To investigate the prevalence rate of colorectal adenoma in patients with gastric adenomas and to determine the association between the presence of gastric adenomas and synchronous colorectal adenomas. DESIGN: A retrospective, cross-sectional, case-control study. SETTING: Single center: Center for Health Promotion of Samsung Medical Center. PATIENTS: This study involved 87 patients with gastric adenomas and 174 sex-matched and age-matched controls among 19,019 participants who underwent EGD and colonoscopy simultaneously or within 6 months of each other from January 2001 to December 2008 at the Center for Health Promotion of Samsung Medical Center. INTERVENTION: EGD and colonoscopy. MAIN OUTCOME MEASUREMENTS: The prevalence rate of colorectal adenoma in patients with gastric adenomas. RESULTS: The 87 gastric adenoma patients included 72 men and 15 women. Colorectal adenomas were identified in 42 (48.3%) of 87 cases and in 58 (33.3%) of 174 controls (P = .022). The prevalence of colorectal adenoma was significantly higher in the gastric adenoma group than in the control group. The mean size and number of colorectal adenomas were not significantly different between the two groups. The majority of colorectal adenomas were located in distal colonic segments in the gastric adenoma group in contrast with proximal colonic segments in the control group. Multivariate logistic regression analysis revealed that independent risk factors for colorectal adenoma were the presence of gastric adenomas (odds ratio [OR], .915; 95% confidence interval [CI], 1.044-3.513) and increasing age over 55 years (OR, 2.943; 95% CI, 1.558-5.560). LIMITATIONS: Lack of data on previous colorectal adenomas and possible confounding factors such as hyperlipidemia or diabetes mellitus. CONCLUSION: The risk of colorectal adenoma increases significantly in patients with gastric adenomas and in patients over age 55. A screening colonoscopy may be necessary for patients with gastric adenomas to detect colorectal adenomas.