Prognostic value of tumor deposits and positive lymph node ratio in stage III colorectal cancer: a retrospective cohort study.

BACKGROUND: In colorectal cancer (CRC), tumor deposits (TD) have been used to guide the N staging only in node-negative patients. It remains unknown about the prognostic value of TD in combination with positive lymph node ratio (LNR) in stage III CRC. PATIENTS AND METHODS: The authors analyzed data from 31 139 eligible patients diagnosed with stage III CRC, including 30 230 from the Surveillance, Epidemiology, and End Results (SEER) database as a training set and 909 from two Chinese hospitals as a validation set. The associations of TD and LNR with cancer-specific survival (CSS) and overall survival (OS) were evaluated using the Kaplan-Meier method and Cox regression models. RESULTS: Both TD-positive and high LNR (value ≥0.4) were associated with worse CSS in the training [multivariable hazard ratio (HR), 1.50; 95% CI: 1.43-1.58 and HR, 1.74; 95% CI: 1.62-1.86, respectively] and validation sets (HR, 1.90; 95% CI: 1.41-2.54 and HR, 2.01; 95% CI: 1.29-3.15, respectively). Compared to patients with TD-negative and low LNR (value<0.4), those with TD-positive and high LNR had a 4.09-fold risk of CRC-specific death in the training set (HR, 4.09; 95% CI: 3.54-4.72) and 4.60-fold risk in the validation set (HR, 4.60; 95% CI: 2.88-7.35). Patients with TD-positive/H-LNR CRC on the right side had the worst prognosis ( P <0.001). The combined variable of TD and LNR contributed the most to CSS prediction in the training (24.26%) and validation (32.31%) sets. A nomogram including TD and LNR showed satisfactory discriminative ability, and calibration curves indicated favorable consistency in both the training and validation sets. CONCLUSIONS: TD and LNR represent independent prognostic predictors for stage III CRC. A combination of TD and LNR could be used to identify those at high-risk of CRC deaths.

Suggested mesiodistal distance for multiple implant placement based on the natural tooth crown dimension with digital design.

PURPOSE: The purpose of this investigation was to identify a mesiodistal algorithm for multiple posterior implant placement based upon an ideal prosthetically restoration design. METHODS: One hundred one cases of posterior free-end edentulous arches were selected for digital crown designs and measurements. Cone bean computed tomogram and digital fabricated crown were applied. DICOM files were exported to a viewer software (BlueSkyPlan4) to generate digital crown and measurement. The mesiodistal space between roots of adjacent teeth and center of the potential implant horizontally, from both cross-section and coronal plane were measured. Comparisons were performed using t-tests. RESULTS: No significant difference was found in the distances of the maxillary and mandibular posterior implants to adjacent natural teeth (p > 0.05). For interdental/implant distances, premolars are around 4.2 mm and molars are 5.4 mm, correspondently. The second premolar interimplant distance is around 7-7.4 mm. The distance of interimplant of the first molar is about 8-8.5 mm. For the maxillary second molar, the interimplant distance is 9.26 ± 0.29 mm and the mandibular second molar interimplant distance is 9.58 ± 0.19 mm, which is significantly different. No difference was found between the two different measurement methods. CONCLUSION: A mesiodistal algorithm of 4-4.6 (implant to adjacent canine tooth), 7-7.4, 8-8.5, and 9-9.5 mm was recommended for interimplant/tooth distance from first premolar to second molar when placing implants with or without case-specific prosthetic planning prior to surgery.

Fresh vegetable and fruit consumption and carotid atherosclerosis in high-cardiovascular-risk population: a cross-sectional study in Jiangsu, China / Consumo de frutas e verduras frescas e aterosclerose carotídea em uma população de alto risco cardiovascular: um estudo transversal em Jiangsu, China / Consumo de verduras frescas y fruta y la aterosclerosis carotídea en una población con alto riesgo cardiovascular: un estudio trasversal en Jiangsu, China

This study aimed to investigate the association of vegetable and fruit consumption with carotid plaque (CP) and carotid intima-media thickness (CIMT), two predictors of carotid atherosclerosis, within urban and rural adults at high risk of developing cardiovascular diseases (CVDs) in regional China. A total of 11,392 adults at high CVD risk were identified from general population of 71,511 in this cross-sectional study, conducted between November of 2015 and May of 2016 in the Jiangsu Province. Among these 11,392 high risk participants, CP prevalence was 36.7%. The independent variables, vegetable and fruit intake frequency, were assessed by a food frequency questionnaire. The outcome variables, CIMT and CP, were measured by ultrasound examination. The ANCOVA analysis showed no association between CIMT values and vegetable and fruit intake frequencies. Multivariate logistic regression models were introduced to examine the association between vegetable and fruit intake and CP. After adjustment for potential confounders, the odds ratios (ORs) for participants who occasionally and daily consumed vegetable to experience any CP were 0.67 (95%CI: 0.58-0.78) and 0.70 (95%CI: 0.62-0.79), respectively, compared with those rarely consumed vegetable. While the adjusted ORs were 0.77 (95%CI: 0.64-0.92) and 0.80 (95%CI: 0.68-0.94), separately, for occasional and daily vegetable consumers to develop single CP relative to their counterparts who rarely consumed any vegetables. However, no significant association between fruit consumption and CP was observed. Among the Chinese population at high CVD risk, consumption of fresh vegetables was negatively associated with the risk of developing carotid plaque.

O estudo buscou investigar a associação entre consumo de frutas e verduras e placa carotídea (PC) e espessura íntima-média carotídea (EIMC), dois preditores de aterosclerose entre adultos das áreas urbana e rural com alto risco de desenvolver doenças cardiovasculares (DCVs) em uma região da China. Foram identificados 11.392 adultos com alto risco de DCV, entre 71.511 indivíduos da população geral, em um estudo transversal entre novembro de 2015 e maio de 2016 na Província de Jiangsu. Entre esses 11.392 participantes de alto risco, a prevalência de PC foi de 36,7%. As variáveis independentes, ou seja, frequências de consumo de frutas e verduras, foram avaliadas através de um questionário de frequência alimentar. As variáveis de desfecho, EIMC e PC, foram medidas por ultrassom. A análise ANCOVA não mostrou associação entre valores de EIMC e frequências de consumo de frutas e verduras. Foram introduzidos modelos de regressão logística multivariada para examinar a associação entre consumo de frutas e verduras e PC. Depois de ajustar para potenciais fatores de confusão, as ORs para participantes com consumo eventual e diário de verduras para qualquer PC foram 0,67 (IC95%: 0,58-0,78) e 0,70 (IC95%: 0,62-0,79), respectivamente, comparado com aqueles com consumo raro de verduras. Enquanto isso, as ORs ajustados foram 0,77 (IC95%: 0,64-0,92) e 0,80 (IC95%: 0,68-0,94), separadamente, para adultos com consumo eventual e diário de verduras para desenvolver uma PC única, comparado aos que relatavam consumo raro de verduras. Entretanto, não foi observada uma associação significativa entre consumo de frutas e PC. Entre a população chinesa com alto risco de DCV, o consumo de verduras frescas mostrou associação negativa com o risco de desenvolvimento de placa carotídea.

El objetivo de este estudio fue investigar la asociación del consumo de frutas y verduras con la placa carotídea (PC) y el grosor íntima-media carotídeo (GIMC), dos predictores de la aterosclerosis carotídea en adultos urbanos y rurales, con alto riesgo de desarrollar enfermedades cardiovasculares (ECV) en una región de China. Se identificaron, en este estudio transversal, a 11.392 adultos con alto riesgo de ECV dentro de una población general de 71.511, realizado entre noviembre de 2015 y mayo de 2016 en la provincia de Jiangsu. De estos 11.392 participantes en alto riesgo, la prevalencia de PC fue de un 36,7%. Las variables independientes, así como la frecuencia de consumo de verduras y fruta, se evaluaron mediante un cuestionario de frecuencia de comidas. Las variables de resultado, GIMC y PC, se midieron por un examen de ultrasonido. El análisis ANCOVA mostró que no existía asociación entre los valores GIMC y la frecuencia en el consumo de verduras y frutas. Los modelos de regresión logística multivariantes se introdujeron para examinar la asociación entre el consumo de verduras y frutas y la PC. Tras el ajuste para los factores potenciales de confusión, las ORs de haber tenido alguna PC para los participantes que ocasionalmente y diariamente consumían verduras fueron 0,67 (IC95%: 0,58-0,78) y 0,70 (IC95%: 0,62-0,79), respectivamente, comparadas con quienes raramente consumían verduras. Mientras que las ORs ajustadas fueron 0,77 (IC95%: 0,64-0,92) y 0,80 (IC95%: 0,68-0,94), separadamente, para los consumidores ocasionales y los consumidores diarios de verduras de desarrollar una única PC, en relación con sus contrapartes que raramente consumían verduras. No obstante, no se observó una asociación significativa entre el consumo de frutas y la PC. Entre la población con alto riesgo de ECV, el consumo de verdura fresca estuvo negativamente asociado con el riesgo de desarrollar PC.

The Small-Port Effect and the Small-Triangle Manipulation in Laparoendoscopic Single-Site Surgery: Concept from a Training Model to the Clinic.

Objectives: A small port could possibly minimize the collision of instruments and increase operability in laparoendoscopic single-site surgery (LESS) through the realization of small-triangle manipulation. In this study, we attempted to verify the small-port effect in an in vitro suture model and in vivo LESS hysterectomy with different-sized ports. Subjects and Methods: Two different-sized homemade glove ports were used and assessed in both in vitro and in vivo studies. The trocar head of port 1 was 36 mm in diameter and that of port 2 was 25 mm. Thirty sutures under LESS were conducted in a laparoscopic training box with each port. In LESS hysterectomy, 40 patients were recruited, of whom 20 underwent surgery under port 1 and the remaining 20 under port 2. One surgeon with experience in LESS conducted all sutures. The suture time of each stitch in the training box and for closing the vaginal cuff was videotaped and compared. Results: In the training model, the mean time for each suture with port 1 and port 2 was 18.6 ± 0.5 and 12.5 ± 0.3 seconds, respectively. In LESS hysterectomy, the mean suture time of the vaginal cuff with port 1 and port 2 was 15.2 ± 3.1 and 12.4 ± 2.6 minutes, respectively. Suture with port 2 was less time consuming than that with port 1 in both in vivo and in vitro studies, and the difference was statistically significant. Conclusions: A small port could save time in the suture process both in a training model and in operating room as a result of decrease in instrument collision and realization of small-triangle manipulation.

The Regulation of Trophoblastic p53 Homeostasis by the p38-Wip1 Feedback Loop is Disturbed in Placentas from Pregnancies Complicated by Preeclampsia.

BACKGROUND/AIMS: Excessive apoptosis of trophoblasts, induced by sustained hypoxia, leads to abnormal placentation and is strongly linked to pregnancy complications such as preeclampsia (PE). Wild-type p53-induced phosphatase (Wip1) positively regulates cellular survival in tumor cells through the p38 and p53 pathways, but its expression pattern and effects in trophoblasts have yet to be reported. This study clarified the effect of Wip1 on the regulatory mechanism of p53-dependent apoptosis in trophoblasts, and thus increases understanding of the etiology of PE. METHODS: In normal and PE placentas, Wip1 mRNA and protein levels were determined by RT-qPCR and Western blotting respectively, while localization of Wip1 in placental tissues and in HTR8/SVneo cells was determined by immunohistochemistry and immunofluorescence. Two in vitro trophoblastic PE models were established by subjecting HTR8/SVneo cells to either hypoxia intervention in incubator (HII) or simulated ischemic buffer (SIB). Wip1 was suppressed in the aforementioned PE models by specific inhibitor or shRNA, and apoptosis was then assessed by flow cytometry, while further validation was done by measurement of cleaved-caspase 9 expression by Western blotting. The p38 inhibitor SB202190, Mdm2 inhibitor NVP-CGM097, and proteasome inhibitor MG-132 were administered in PE models, either in combination or alone, to determine the regulatory order of the component signal molecules of the feedback loop. The impact of Wip1 on p53-Mdm2 interaction was examined by coimmunoprecipitation. Lastly, the upregulation of the p38-Wip1 loop was confirmed in human placentas from pregnancies complicated by PE, using Western blotting. RESULTS: Wip1 expression was significantly elevated in human PE placentas and in vitro trophoblastic PE models; this is opposite to the pattern observed in tumor cells. Inhibition of Wip1 rescued hypoxia-induced p38 activation, cleavage of caspase 9 and apoptosis but significantly compromised p53-Mdm2 binding, while p-p53Ser15 was increased. Inhibition of Mdm2 degradation resulted in p53 destabilization and p38-Wip1 loop down-regulation, while degradation of the p53-Mdm2 complex resulted in p53 accumulation and p38-Wip1 loop hyperactivation. However, the p53-Mdm2 interaction was found to be more important in the regulation of the p38-Wip1 loop than Mdm2 stability. CONCLUSION: Trophoblastic p53 homeostasis is maintained by the p38-Wip1 feedback regulatory loop in response to hypoxic stress, which is dysregulated in the placentas of pregnancies complicated by PE, and thereby leads to excessive apoptosis.

QSOX1 regulates trophoblastic apoptosis in preeclampsia through hydrogen peroxide production.

Objective: Oxidative stress plays a significant role in the pathogenesis of preeclampsia (PE), by inducing trophoblast cell death and consequent placental dysfunction. Quiescin sulfhydryl oxidase 1 (QSOX1) is upregulated in many types of cancer cells; it promotes disulfide bond formation as well as hydrogen peroxide (H2O2) production. The aims of present study are to investigate the expression pattern of QSOX1 in placentae of pregnancies complicated by PE and the role of QSOX1 in the regulation of trophoblastic function, thus providing in-depth understanding of the putative involvement of QSOX1 in the development of PE. Methods: Human term placenta from normal pregnancies and from pregnancies complicated by PE was collected to measure QSOX1 expression and H2O2 levels. Down-regulation of QSOX1 in HTR-8/SVneo cells was achieved by siRNA interference. An in vitro cellular PE model was generated by hypoxic incubation. Protein expression levels were assessed by Western blotting, and H2O2 levels were determined in the cell culture medium as well as in the cell lysate. Trophoblast apoptosis was evaluated by TUNEL staining. Results: QSOX1 was overexpressed in the PE placenta. Inhibition of QSOX1 expression in HTR-8/SVneo cells attenuated cell apoptosis and intracellular H2O2 levels. Hypoxia-induced QSOX1 expression in HTR-8/SVneo cells and led to apoptosis of HTR-8/SVneo cells, and knock-down of QSOX1 rescued hypoxia-induced trophoblast apoptosis. Conclusions: Hypoxia-induced upregulation of QSOX1 and a consequent elevation in intracellular H2O2 increased apoptosis in placentae of pregnancies complicated by PE.

Wall shear stress promotes intimal hyperplasia through the paracrine H2O2-mediated NOX-AKT-SVV axis.

AIMS: Oscillatory wall shear stress (WSS)-linked oxidative stress promotes intimal hyperplasia (IH) development, but the underlying mechanisms are not completely understood. MATERIALS AND METHODS: We used an in vivo rabbit carotid arterial stenosis model representing different levels of WSS and found that WSS was increased at 1 month with 50% stenosis and was accompanied by VSMCs proliferation and interstitial collagen accumulation. Increased WSS promoted the expression of NOX, AKT, and survivin (SVV) and the proliferation/migration of VSMCs and reduced apoptosis. KEY FINDINGS: Our in vitro study suggested that H2O2 promoted proliferation and migration while suppressing apoptosis in cultured human umbilical vascular endothelial cells. SIGNIFICANCE: We demonstrated that the elevation of WSS promotes VSMC proliferation and migration through the H2O2-mediated NOX-AKT-SVV axis, thereby accelerating IH development.

[Arginase inhibitor nor-NOHA induces apoptosis and inhibits invasion and migration of HepG2 cells].

Objective To investigate the cell inhibitory effect of arginase inhibitor nor-NOHA on HepG2 hepatocellular carcinoma cells and related mechanism. Methods CCK-8 assay was used to detect the cell proliferation and flow cytometry to detect the apoptosis of HepG2 cells treated with (0, 0.5, 1.0, 2.0, 3.0) ng/µL nor-NOHA. The protein levels of arginase 1 (Arg1), P53, matrix metalloproteinase-2 (MMP-2), E-cadherin (ECD) were determined by Western blotting. Real time quantitative PCR was employed to examine the changes in the mRNA level of inducible nitric oxide synthase (iNOS). Griess assay was used to measure the concentration of nitric oxide (NO) in HepG2 cells. TranswellTM assay and wound-healing assay were performed to evaluate the changes of the cell invasion and migration ability, respectively. Results nor-NOHA inhibited the proliferation and induced the apoptosis of HepG2 cells. It also decreased the expression levels of Arg1 and MMP-2, increased the expression levels of P53 and ECD as well as the production of NO; in addition, nor-NOHA inhibited the invasion and migration of HepG2 cells. Conclusion Nor-NOHA can induce cell apoptosis and inhibit the ability of invasion and migration of HepG2 cells by inhibiting Arg1, which is related with the increase of iNOS expression and the high concentration of NO.

Pleiotropic effects of survivin in vascular endothelial cells.

OBJECTIVE: To assess the effects of survivin (SVV)in vascular endothelial cells. METHODS: In this study, we applied a gain-of-function approach and ectopically expressed SVV in rat aortic endothelial cells (RAECs) using a SVV-expressing adenovirus. The resulting SVV expression on the steady-state mRNA and protein level in RAECs was determined by reverse transcription quantitative PCR and Western blot, respectively. Cell viability, apoptosis, and migration were assessed in vitro by CCK-8 assay, flow cytometry, and transwell assay, respectively. The effect of SVV on in vivo angiogenesis was evaluated by immunohistochemistry in nude mice. Non-infected RAECs and those infected with GFP-expressing control adenovirus were used as controls. RESULTS: Compared to non-infected or control adenovirus-infected RAECs in vitro, SVV-expressing cells had increased viability and migratory capability, but reduced apoptosis. In vivo, SVV-expressing RAECs were associated with a higher level of angiogenesis. CONCLUSION: SVV is a positive regulator of endothelial cell survival and migration, and thus, stabilizes endothelial cells and stimulates angiogenesis.

Tumor-associated macrophage or chemokine ligand CCL17 positively regulates the tumorigenesis of hepatocellular carcinoma.

Alternatively activated macrophages (M2) can secrete chemokines, such as chemokine ligand 17 (CCL17), and are associated with promoting tumorigenesis of hepatocellular carcinoma (HCC). This study aimed at investigating the potential role of M2 and CCL17 in progression of HCC. The levels of CCL17 expression in 90 HCC samples were characterized by tissue microarray and stratified for the postsurgical survival. MHCC97L cells were co-cultured with classically activated M1, M2 or CCL17-silencing M2(ccl17mute) or treated with conditional medium (CM) from these cells or CCL17 in vitro. The wound healing, invasion, viability and apoptosis of MHCC97L cells in vitro and tumor growth in vivo were determined. The stemness of MHCC97L cells was examined by sphere formation, flow cytometry and Western blot. The relative expression levels of epithelial-mesenchymal transition (EMT) factors and the Wnt/ß-catenin signaling were determined. Higher levels of intratumoral CCL17 expression were significantly associated with clinical pathological characteristics of HCC and with poorer overall survival rates in HCC patients (P < 0.05). High levels of CCR4 were detected in MHCC97L cells. Treatment with the CM from M2 or with CCL17 significantly enhanced the wound healing process, invasion and proliferation of MHCC97L cells in vitro. Co-implantation MHCC97L cells with M2 significantly promoted the growth of MHCC97L tumors in vivo. Co-culture with M2 or treatment with CCL17 enhanced the stemness, EMT process, the TGF-ß1 and Wnt/ß-catenin signaling in MHCC97L cells. CCL17 promotes the tumorigenesis of HCC and may be a potential biomarker and target for HCC prognosis and therapy.

GdCl3 suppresses the malignant potential of hepatocellular carcinoma by inhibiting the expression of CD206 in tumor­associated macrophages.

In the present study, we aimed to ascertain whether there is a correlation between CD206 expression in tumor associated-macrophages (TAMs) and the prognosis of primary hepatocellular carcinomas (HCC) and we investigated the effect of GdCl3 on HCC. The expression of CD206 in HCC tumor tissues and peri-carcinoma tissues was measured using an array for liver tissues. The effects of GdCl3 on CD206 expression were examined in stimulated RAW264.7 cells. Target gene expression was evaluated by RT-PCR, western blotting and immunohistochemistry. The transwell system was used to assess the invasiveness of HCC cells. Finally, we established a mouse model for HCC using N-nitrosodiethylamine (DEN) to determine the effect of GdCl3 on HCC. Liver tissue array analysis revealed that CD206 was highly expressed in the HCC tissues compared to the level in peri-carcinoma tissue. We found that GdCl3 suppressed the expression of CD206 in the M2 macrophage phenotype of stimulated RAW264.7 cells with an IC10 value of 0.07 µg/µl. In addition, GdCl3 also induced cell apoptosis in the RAW264.7 cells. Addition of GdCl3 into the culture medium of RAW264.7 cells markedly reduced the invasive ability of Hepa1-6 cells compared to the control cells. Accordingly, GdCl3 treatment increased the expression of the epithelial-mesenchymal transition (EMT)-related protein E-cadherin while expression of N-cadherin, TWIST and Snail was reduced in IL-4-stimulated cells. Moreover, GdCl3 treatment inhibited HCC progression in DEN-induced HCC mice, possibly by downregulating CD206. Our findings indicate that CD206 is a potential biomarker for predicting HCC prognosis and that GdCl3 suppresses HCC progression by downregulating the expression of CD206 in TAMs.

Effectiveness of localized ultrasound-targeted microbubble destruction with doxorubicin liposomes in H22 mouse hepatocellular carcinoma model.

OBJECTIVE: In order to increase local drug concentration and reduce systemic side effects of liver cancer chemotherapy, it is desirable to develop novel non-invasive technologies for drug targeting, such as ultrasound-targeted microbubble destruction (UTMD). METHODS: H22 hepatocellular carcinoma (HCC) xenograft transplantation model was generated in UTMD study. BALB/c mice were randomly divided into six groups: doxorubicin HCl liposomal injection (DOX), DOX + US, UTMD, DOX + UTMD, H22 liver tumor control (CH control) and blank control group. The therapeutic schedule started on day 4 after tumor inoculation. RESULTS: Average survival time of the animal model was approximately 18 d. The UTMD therapy parameters were optimized in the H22 mouse model to be: microbubble (MB) diameter, 2.30 ± 0.25 µm; MB density, 4.0 × 10(9) bubbles/ml; treatment dose, 0.2 ml per 20 g mouse body weight; sonication frequency, 1.3 MHz; and sonication power, 2.06 W/cm(2). Mice treated with DOX + UTMD had the smallest tumor volume and weight (p < 0.001), and the highest tumor inhibition rate (p < 0.01), intratumoral DOX concentration (p < 0.001) and survival rate among all tumor-burden groups (p < 0.001). Cell viability in different treatment groups was also assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. CONCLUSION: An improved antitumor effect was observed with the combination therapy of DOX and UTMD, as compared with treatment with DOX, DOX + US or UTMD, which implicates a novel approach for HCC treatment.

si-DNMT1 restore tumor suppressor genes expression through the reversal of DNA hypermethylation in cholangiocarcinoma.

OBJECTIVE: The aim of our study was to evaluate the effect of shorthairpin RNA plasmid vector knockdown of human DNA methyltransferase 1 on proliferation and the methylation status and expression of tumor suppressor genes in hilar cholangiocarcinoma. METHODS: The hilar cholangiocarcinoma cell line QBC939 was utilized for this study. QBC939 cells were transfected with a shorthairpin RNA plasmid vector targeting human DNA methyltransferase 1. Control and human DNA methyltransferase 1 shorthairpin RNA plasmid vector-transfected cells were collected at different time points, and the expression levels of human DNA methyltransferase 1 and tumor suppressor genes (cyclin-dependent kinase inhibitor 2B, cyclin-dependent kinase inhibitor 2A, RAS association domain family 1, and cadherin-1) were detected by reverse transcription-polymerase chain reaction. Furthermore, interfering efficiency was confirmed by Western blotting. The methylation status of tumor suppressor genes was detected using methylation-specific polymerase chain reaction. Furthermore, the effect of human DNA methyltransferase 1 knockdown on proliferation was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. RESULTS: Targeted gene knockout of human DNA methyltransferase 1 restored the expression levels of tumor suppressor genes cyclin-dependent kinase inhibitor 2B, cyclin-dependent kinase inhibitor 2A, RAS association domain family 1, and cadherin-1, indicating that the silencing of these tumor suppressor genes is associated with promoter hypermethylation. In addition, knockdown of human DNA methyltransferase 1 expression significantly inhibited the proliferation of QBC939 cells. CONCLUSIONS: Targeted knockdown of human DNA methyltransferase 1 expression restores the expression levels of tumor suppressor genes, thus inhibiting the proliferation of QBC939 cells. These results may provide insight for the development of novel therapies for cholangiocarcinoma.