NAMPT regulates PKM2 nuclear location through 14-3-3ζ: Conferring resistance to tamoxifen in breast cancer.

The resistance against tamoxifen therapy has become one of the major obstacles in the clinical treatment of breast cancer. Nicotinamide phosphoribosyltransferase (NAMPT) is an essential enzyme catalyzing nicotinamide adenine dinucleotide biosynthesis and is important for tumor metabolism. The study here sought to explore the effect of NAMPT on breast cancer survival with tamoxifen conditioning. We found that NAMPT was highly expressed in breast cancer cells compared with normal mammary epithelial cells. Inhibition of NAMPT by FK866 inhibited cell viability and aggravated apoptosis in cancer cells treated with 4-hydroxytamoxifen. NAMPT overexpression upregulated 14-3-3ζ expression. Knockdown of 14-3-3ζ reduced cell survival and promoted apoptosis. Activation of Akt signaling, rather than ERK1/2 pathway, is responsible for 14-3-3ζ regulation by NAMPT overexpression. Furthermore, NAMPT overexpression led to PKM2 accumulation in the cell nucleus and could be dampened by 14-3-3ζ inhibition. In addition, NAMPT overexpression promoted xenografted tumor growth and apoptosis in nude mice, while 14-3-3ζ inhibition attenuated its effect. Collectively, our data demonstrate that NAMPT contributes to tamoxifen resistance through regulation of 14-3-3ζ expression and PKM2 translocation.

Long non-coding RNA FTH1P3 activates paclitaxel resistance in breast cancer through miR-206/ABCB1.

Emerging evidence has indicated the important function of long non-coding RNAs (lncRNAs) in tumour chemotherapy resistance. However, the underlying mechanism is still ambiguous. In this study, we investigate the physiopathologic role of lncRNA ferritin heavy chain 1 pseudogene 3 (FTH1P3) on the paclitaxel (PTX) resistance in breast cancer. Results showed that lncRNA FTH1P3 was up-regulated in paclitaxel-resistant breast cancer tissue and cells (MCF-7/PTX and MDA-MB-231/PTX cells) compared with paclitaxel-sensitive tissue and parental cell lines (MCF-7, MDA-MB-231). Gain- and loss-of-function experiments revealed that FTH1P3 silencing decreased the 50% inhibitory concentration (IC50) value of paclitaxel and induced cell cycle arrest at G2/M phase, while FTH1P3-enhanced expression exerted the opposite effects. In vivo, xenograft mice assay showed that FTH1P3 silencing suppressed the tumour growth of paclitaxel-resistant breast cancer cells and ABCB1 protein expression. Bioinformatics tools and luciferase reporter assay validated that FTH1P3 promoted ABCB1 protein expression through targeting miR-206, acting as a miRNA "sponge." In summary, our results reveal the potential regulatory mechanism of FTH1P3 on breast cancer paclitaxel resistance through miR-206/ABCB1, providing a novel insight for the breast cancer chemoresistance.

Inhibition of Mcl-1 enhances Pevonedistat-triggered apoptosis in osteosarcoma cells.

Neddylation inhibitor Pevonedistat (MLN4924) is a novel anticancer drug and has demonstrated broad-spectrum anticancer activity. Nevertheless, we found that Pevonedistat had only a modest apoptotic effect in osteosarcoma (OS) cells. Moreover, we noted that inhibition of neddylation by Pevonedistat led to accumulation of Mcl-1 protein in OS cells. Because Mcl-1 is an important anti-apoptotic protein and also because apoptosis has been shown to be a major cell death pathway, we hypothesized that Mcl-1 accumulation negatively impacted Pevonedistat-mediated anticancer activity in OS cells. In this regard, we employed genetic or pharmacological approaches to inhibit Mcl-1 expression and to examine the effect on Pevonedistat-induced apoptosis in OS cells. We found that inhibition of Mcl-1 expression by siRNA considerably enhanced Pevonedistat-triggered the activation of caspase-3, PARP cleavage and apoptosis, and also dramatically promoted the ability of Pevonedistat to inhibit colony formation of OS cells. Moreover, we observed that flavopiridol, a FDA approved drug, inhibited Mcl-1 expression and substantially enhanced Pevonedistat-mediated activation of apoptosis signaling and significantly augmented cell killing effect in OS cells. Altogether, our study shows that Mcl-1 is a critical resistance factor to Pevonedistat monotherapy, and suggests that Pevonedistat in combinations with flavopiridol may achieve better anticancer therapy.

EZH2 Contributes To Cisplatin Resistance In Breast Cancer By Epigenetically Suppressing miR-381 Expression.

BACKGROUND: Emerging evidence reveals the vital role of enhancer of zeste homolog 2 (EZH2) in cancer chemoresistance. However, its function and molecular mechanisms in breast cancer chemoresistance remain largely unknown. METHODS: Gene expression was evaluated using quantitative real-time PCR (qRT-PCR) and Western blot analysis. The functional roles of EZH2 and miR-381 in breast cancer were explored using cell MTT assay and flow cytometry analysis. The effect of EZH2 on miR-381 expression in transcriptional level was determined using Chromatin immunoprecipitation (ChIP) assay and Luciferase reporter assay. RESULTS: In this study, we found that EZH2 was up-regulated in CDDP-resistant breast cancer tissues and cell lines. Breast cancer patients with high EZH2 expression had a poor prognosis. EZH2 silencing improved the sensitivity of MCF-7/CDDP and MDA-MB-231/CDDP cells towards CDDP. Moreover, EZH2 could epigenetically silence miR-381. miR-381 overexpression could overcome CDDP resistance in CDDP-resistant breast cancer cells. miR-381 knockdown weakened the inductive effect of EZH2 silencing on CDDP sensitivity of MCF-7/CDDP and MDA-MB-231/CDDP cells. Furthermore, EZH2 knockdown facilitated CDDP sensitivity of CDDP-resistant breast cancer cells in vivo. CONCLUSIONS: Collectively, EZH2 depletion overcame CDDP resistance of breast cancer through epigenetically silencing miR-381, providing a novel therapeutic target for breast cancer chemoresistance.

lncRNA GHET1 knockdown suppresses breast cancer activity in vitro and in vivo.

Long non-coding RNA gastric carcinoma high-expressed transcript 1 (lncRNA GHET1) is highly expressed in many tumors. The aim of the present study was to determine whether GHET1 inhibition decreases growth and metastasis of MCF-7 breast cancer cells by modulating epidermal growth factor receptor (EGFR) expression. In vitro, lncRNA GHET1 knockdown suppressed cell proliferation, migration, and invasion and enhanced cell apoptosis by maintaining MCF-7 cells in the G1 phase of the cell cycle. Furthermore, lncRNA GHET1 knockdown reduced the expression of EGFR and related proteins. Treatment of mice with a GHET1 inhibitor prevented tumor growth in vivo. The results indicate that lncRNA GHET1 inhibition directly suppresses EGFR expression, significantly inhibiting the downstream PI3K/AKT/Cyclin D1/MMP2/9 pathway. This mechanism may underlie the suppression of breast cancer cell activities including proliferation, migration, and invasion. In conclusion, lncRNA GHET1 knockdown suppresses tumor growth and metastasis by suppressing the activity of EGFR and downstream pathways.

Oncosis in human esophageal squamous cell carcinoma and its relationship with apoptosis and microvessel density.

BACKGROUND: Previous studies have shown that oncosis in malignant tumors might be related to cellular energy supply. The aim of this study was to detect oncosis in human esophageal squamous cell carcinoma (ESCC), and to investigate its relationship with apoptosis and microvessel density (MVD). METHODS: ESCC specimens were obtained from 30 patients with ESCC after surgery. Transmission electron microscopy, TUNEL, and immunohistochemistry were used to detect oncosis, apoptosis, and MVD. The relation of oncosis to apoptosis and MVD was analyzed by ANOVA, t test, and q test using SPSS 10.0. RESULTS: Transmission electron microscopy revealed both oncosis and apoptosis in the ECSS tissues. About 10% of the TUNEL-positive cells, which were considered apoptotic cells, showed the characteristics of oncosis. In the areas, where oncotic cells accumulated, apoptotic cells were rare; contrarily, where apoptotic cells gathered, oncotic cells were sparse. Compared with the tissues with a high MVD, the number of oncotic cells was increased and that of apoptotic cells was decreased in the tissues with a low MVD. CONCLUSIONS: Cellular oncosis can be detected in human ESCC tissues. The distribution of oncotic cells presents a close relationship with cellular apoptosis and MVD. Oncosis might be induced by poor blood supply.

Suppression of BRD4 inhibits human hepatocellular carcinoma by repressing MYC and enhancing BIM expression.

Bromodomain 4 (BRD4) is an epigenetic regulator that, when inhibited, has anti-cancer effects. In this study, we investigated whether BRD4 could be a target for treatment of human hepatocellular carcinoma (HCC). We show that BRD4 is over-expressed in HCC tissues. Suppression of BRD4, either by siRNA or using JQ1, a pharmaceutical BRD4 inhibitor, reduced cell growth and induced apoptosis in HCC cell lines while also slowing HCC xenograft tumor growth in mice. JQ1 treatment induced G1 cell cycle arrest by repressing MYC expression, which led to the up-regulation of CDKN1B (P27). JQ1 also de-repressed expression of the pro-apoptotic BCL2L11 (BIM). Moreover, siRNA knockdown of BIM attenuated JQ1-triggered apoptosis in HCC cells, suggesting an essential role for BIM in mediating JQ1 anti-HCC activity.

Effects of oxidized low density lipoprotein on the growth of human artery smooth muscle cells.

BACKGROUND: Studies have shown that oxidized low density lipoprotein (ox-LDL) promotes the pathogenesis and development of atherosclerosis (AS), and that the proliferation, migration and phenotype alteration of vascular smooth muscle cells (vSMCs) into foam cells are critical changes in AS. It is proposed that ox-LDL might play a novel role in the pathologic process of vSMCs. The present study was performed ex vivo to investigate the effects of ox-LDL on the growth of cultured human vSMCs. METHODS: Using NaBr density gradient centrifugation, LDL from human plasma was isolated and purified. ox-LDL was produced from LDL after being incubated with CuSO4. ox-LDL was then added to the culture medium at different concentrations (25 microg/ml, 50 microg/ml, 75 microg/ml, 100 microg/ml, 125 microg/ml, and 150 microg/ml) for 7 days. The influence of ox-LDL on vSMC growth was observed from several aspects as growth curve, mitosis index, lipid staining, and in situ determination of apoptosis. The digital results were analyzed with SPSS 10.0. RESULTS: The ox-LDL produced ex vivo had a good purity and optimal oxidative degree, which was similar to the intrinsic ox-LDL in atherosclerotic plaque. ox-LDL at a concentration of 25 microg/ml demonstrated the strongest proliferation. At the concentration of 125 microg/ml, ox-LDL suppressed the growth of vSMCs. At concentrations of 25 microg/ml and 50 microg/ml, ox-LDL presented powerful mitotic trigger. When the concentration of ox-LDL increased, the mitotic index of vSMCs decreased gradually. ox-LDL induced more foam cells from vSMCs with rich intracellular lipid accumulation at concentrations of 25 microg/ml and 50 microg/ml. ox-LDL at higher concentrations induced more apoptotic vSMCs. CONCLUSIONS: ox-LDL at lower concentrations may trigger proliferation and phenotype alteration into foam cells of vSMCs, and at higher concentrations it may induce apoptosis in vSMCs. ox-LDL plays an important role in the pathogenesis and development of atherosclerosis by its effect on vSMCs proliferation, phenotype alteration and apoptosis.

Heparin reduces overcirculation-induced pulmonary artery remodeling through p38 MAPK in piglet.

BACKGROUND: Artery remodeling is the principal change of pulmonary artery hypertension. Heparin has been shown to inhibit vascular smooth muscle cell proliferation. We hypothesized that heparin may modulate vascular remodeling in pulmonary artery hypertension, and explored the mechanism. METHODS: A localized overcirculation-induced artery remodeling was created in piglets by anastomosing the left lower lobe pulmonary artery (LLLPA) to the thoracic aortic artery. Piglets were treated with heparin or saline for 4 weeks. Hemodynamic data were collected, and histology of the lung was assessed. We investigated the expressions of several candidate genes in lung and further observed the involvement of P38 mitogen-activated protein kinases (MAPK). The effects of heparin on the growth of cultured pulmonary arterial vascular smooth muscle cell and P38 MAPK expression were further determined under various conditions. RESULTS: Four weeks after the shunt setup, overcirculation caused significant LLLPA remodeling, pressure increase, and pulmonary vascular resistance increase, and LLLPA flow reduction compared with that immediately after the shunt setup. Heparin reduced the LLLPA remodeling, pressure, and pulmonary vascular resistance, and increased the LLLPA flow compared with that not heparin treated. Shunt and heparin treatment did not change the piglet's systemic hemodynamics. Shunt increased the expression of P38 MAPK and heparin decreased its expression in the shunted LLLPA. Both heparin and P38 MAPK inhibitor suppressed VSMC growth and P38 MAPK expression in the cultured VSMC, but they did not present additive effects when the two treatments were combined. CONCLUSIONS: Heparin reduces overcirculation-induced pulmonary artery remodeling through a P38 MAPK-dependent pathway.

Diagnosis and surgical treatment of ruptured aneurysm in sinus of Valsalva.

OBJECTIVE: To evaluate the methods used to diagnose and surgically treat ruptured aneurysm in sinus of Valsalva (RASV). METHODS: Thirty-seven hospitalized patients with ruptured aneurysms in the sinus of Valsalva from September 1981 to April 2001, including 21 cases (56.7%) of RASV associated with ventricular septal defects (VSD) and 11 (29.7%) with aortic valvular prolapse were given surgical interventions. Under hypothermia and extracorporeal circulation, we successfully performed the surgical correction of RASV for all 37 patients VSD repair in 21 patients, aortic valvuloplasty in 6 and aortic valvular replacement in 2. RESULTS: There was no hospital deaths among these patients, although residual shunting occurred in two patients and acute renal failure was found one. Follow-up study of one month to 20 years in the patients undergoing repair of RASV revealed that the mostly individuals treated with operation obtained satisfactory cardiac function. CONCLUSION: Correct diagnosis of ruptured aneurysm in sinus of Valsalva should be confirmed immediately and surgical correction should be carried out as soon as possible.