Donglei Liu

Effect of autophagy inhibition on chemotherapy‑induced apoptosis in A549 lung cancer cells

Chemotherapy is one of the main methods of cancer treatment and is known to induce autophagy in cancer cells. The main mechanism of chemotherapeutic agents is to promote apoptosis. In the process of chemotherapy, there is a unique association between autophagy and apoptosis. In this study, MDC staining, Hoechst 33342 staining and flow cytometry were used to explore the effects of autophagy on chemotherapy-induced apoptosis in A549 lung cancer cells and the association between autophagy and apoptosis was investigated via the addition of an autophagic inhibitor (3-methyladenine, 3-MA). This study demonstrated that cisplatin and paclitaxel were able to induce autophagy and apoptosis in A549 lung cancer cells and the inhibition of autophagy promoted cisplatin and paclitaxel-induced apoptosis. Furthermore, autophagy may play a protective role in the processes of cisplatin and paclitaxel-induced apoptosis.

Upregulation of long noncoding RNA SPRY4-IT1 promotes metastasis of esophageal squamous cell carcinoma via induction of epithelial–mesenchymal transition

Esophageal squamous cell carcinoma (ESCC) is one of the prevalent and deadly cancers worldwide, especially in Eastern Asia. Recent studies show that long noncoding RNAs (lncRNAs) have critical roles in diverse biological processes, including tumorigenesis. In the present study, we find that the expression of lncRNA SPRY4-IT1 is significantly upregulated in ESCC cell lines as compared with human esophageal epithelial cell line HEEC. Overexpression of SPRY4-IT1 can increase in vitro motility of ESCC cells via induction of epithelial–mesenchymal transition (EMT), which is characterized by increasing the expression of vimentin (Vim) and fibronectin (FN) with a concomitant decrease of E-cadherin (E-Cad) and ZO-1, while silencing of SPRY4-IT1 significantly inhibits the in vitro motility of ESCC cells. Further, the knockdown of SPRY4-IT1 also significantly attenuates TFG-β-induced EMT of ESCC cells. Further, lncRNA SPRY4-IT1 can directly increase the transcription, expression, and nuclear localization of Snail, one key transcription factor during the EMT processes of cancer cells, while siRNA-mediated specific knockdown of Snail can significantly attenuate SPRY4-IT1-induced EMT of ESCC cells. Our results suggest that lncRNA SPRY4-IT1 might be considered as a novel oncogene involved in ESCC progression.

MiR-454 promotes the progression of human non-small cell lung cancer and directly targets PTEN.

PURPOSE MicroRNA-454 has been proven dysregulated in some human malignancies and correlated with tumor progression. However, its expression and function in non-small cell lung cancer (NSCLC) is still unclear. Thus, the aim of this study was to explore the effects of miR-454 in NSCLC tumorigenesis and development. METHODS Using quantitative RT-PCR, we detected miR-454 expression in NSCLC cell lines and primary tumor tissues. The association of miR-454 expression with clinicopathological factors and prognosis was also analyzed. Then, the effects of miR-454 on the biological behavior of NSCLC cells were investigated. At last, the potential regulatory function of miR-454 on PTEN expression was confirmed. RESULTS miR-454 was found to be up-regulated in NSCLC tissues and cell lines. High miR-454 expression was closely correlated with lymph node metastasis, advanced TNM stage, and shorter overall survival. Multivariate regression analysis corroborated that miR-454 overexpression was an independent unfavourable prognostic factor for patients with NSCLC. Down-regulation of miR-454 could significantly reduce NSCLC cell proliferation, enhance cell apoptosis, and impair cell invasion and migration in vitro, while up-regulation of miR-454 showed opposite effects. Further, PTEN was confirmed as a direct target of miR-454 by using Luciferase Reporter Assay. CONCLUSIONS These findings indicate that miR-454 may act as an oncogene in NSCLC and would serve as a potential therapy target for this disease.

Activation of PPARγ suppresses proliferation and induces apoptosis of esophageal cancer cells by inhibiting TLR4-dependent MAPK pathway

Although substantial studies on peroxisome proliferator-activated receptor γ (PPARγ) have focused on the mechanisms by which PPARγ regulates glucose and lipid metabolism, recent reports have suggested that PPARγ shows tumorigenic or antitumorigenic effects. The roles and mechanisms of PPARγ activation in esophageal cancer remain unclarified. EC109 and TE10 esophageal cancer cells were treated with 0, 10, 20 and 40 mM of PPARγ agonist rosiglitazone (RGZ) for 24, 48, and 72 h, and the cell viability and apoptosis were detected using methyl thiazolyl tetrazolium (MTT) assay and Flow cytometric (FCM) analysis, respectively. Moreover, the effects of inhibition of PPARγ by antagonist or specific RNA interference on cell viability, apoptosis, the Toll-like receptor 4 (TLR4) and mitogen-activated protein kinase (MAPK) pathways were evaluated. Additionally, the effect of TLR4 signaling on the MAPK pathway, cell viability and apoptosis was assessed. The results showed that RGZ suppressed proliferation and induced apoptosis of esophageal cancer cells, which could be partly restored by inactivation of PPARγ. RGZ suppressed the MAPK and TLR4 pathways, and the inhibitory effect could be counteracted by PPARγ antagonist or specific RNA interference. We also suggested that MAPK activation was regulated by the TLR4 pathway and that blocking the TLR4 and MAPK pathways significantly suppressed proliferation and induced apoptosis of esophageal cancer cells. In conclusion, our data suggested that activation of PPARγ suppressed proliferation and induced apoptosis of esophageal cancer cells by inhibiting TLR4-dependent MAPK pathway.

Side population cells separated from A549 lung cancer cell line possess cancer stem cell-like properties and inhibition of autophagy potentiates the cytotoxic effect of cisplatin

Recent studies have suggested that cancer stem cells (CSCs) may be responsible for tumorigenesis and contribute to resistance to chemotherapy. Side population (SP) cells are thought to be enriched for CSCs in most types of human tumors. Therefore, the aim of the present study was to sort SP cells using an A549 lung cancer cell line, identify the cancer stem cell-like properties of SP and determine the role of autophagy in the survival of SP cells of lung cancer. SP cells were isolated by fluorescence-activated cell sorter (FACS) from A549 lung cancer cells, and the CSC-like properties were verified through confocal fluorescence imaging, sphere formation assays, cell proliferation and colony formation assay, gene expression in vitro and tumor formation in vivo. The role of autophagy in the survival of SP cells was assessed by western blotting and flow cytometric analysis. A549 lung cancer cells contained 1.10% SP cells. SP cells showed higher abilities of sphere and colony formation, cell proliferation and self-renewal. Moreover, compared to non-SP, SP cells demonstrated a higher mRNA expression of stem cell markers (MDR1, ABCG2 and OCT-4). The clone formation efficiency of SP cells was significantly higher than that non-SP cells under the same conditions. Expression of autophagosomes in SP cells was markedly lower than that in non-SP cells. However, the level of autophagy in SP cells was found to be markedly increased in the presence of cisplatin. In addition, inhibition of autophagy enhanced the effects of apoptosis induced by cisplatin. SP cells from the A549 lung cancer cell line possessed the properties of CSCs and were used to investigate the further characteristics of lung CSCs. SP cells were more resistant to chemotherapy and inhibition of autophagy enhanced the effects of apoptosis induced by the chemotherapeutic agent, cisplatin. These results may provide insight into novel therapeutic targets.

Proteasome inhibitor MG132 inhibits the proliferation and promotes the cisplatin-induced apoptosis of human esophageal squamous cell carcinoma cells

Comprehensive treatment based on chemotherapy is regarded as the first-line treatment for patients with unresectable or metastatic esophageal squamous cell carcinoma (ESCC). However, chemoresistance is common among patients with ESCC. Therefore, there is a need to explore new therapeutic strategies or adjuvant drugs. One promising possibility is to use dietary agents that can increase tumor cell sensitivity to drugs. In this study, we initially investigated the antitumor activity of proteasome inhibitor MG132 in vitro and in vivo. Effects of MG132 on the enhancment of the anticancer functions of cisplatin were then investigated in human esophageal cancer EC9706 cells in relation to apoptosis and cell signaling events. Exposure of cells to MG132 resulted in a marked decrease in cell viability in a dose- and time-dependent manner. Administration of MG132 markedly inhibited tumor growth in the EC9706 xenograft model. MG132 significantly enhanced cisplatin-induced apoptosis in association with the activation of caspase-3 and -8. These events were accompanied by the downregulation of NF-κB, which plays a key role in cell apoptosis. Taken together, these findings demonstrate a novel mechanism by which proteasome inhibitor MG132 potentiates cisplatin-induced apoptosis in human ESCC and inhibitory activity of tumor growth of the EC9706 xenograft model.

Effect of YAP1 silencing on esophageal cancer

Background YAP1, the nuclear effector of the Hippo pathway, has become an attractive target for treatment of malignancies and is a candidate oncogene in esophageal cancer (EC). We hypothesized that knockdown of YAP1 could suppress EC and could be used for targeted therapy. However, there are few reports of the effect of YAP1 knockdown in EC. Materials and methods Quantitative real-time polymerase chain reaction and Western blot assays were performed to determine the expression levels of YAP1 mRNA and protein in primary EC tissue samples, EC cell lines, and controls. Immunohistochemistry was also performed to detect YAP1 protein expression in primary EC tumor and matched nontumor control tissues. YAP1-knockdown cell lines were constructed using short-hairpin RNA, and MTT, flow cytometry, and transwell chamber assays were used to analyze the effect of YAP1 knockdown on EC cell proliferation, apoptosis, and invasion. In vivo tumor formation assays were used to investigate the antitumor effect of YAP1 knockdown. Results We found that YAP1 mRNA and protein were upregulated in EC and that YAP1 expression correlated significantly with metastasis and tumor stage. We also found that YAP1 knockdown repressed cell proliferation and invasion and promoted apoptosis of EC cell lines. In addition, animal experiments revealed that YAP1 knockdown suppressed the growth of esophageal tumors in vivo. Conclusion Collectively, these data confirm our hypothesis that YAP1 knockdown suppresses EC and suggest that YAP1 knockdown could be exploited in the targeted gene therapy of EC in the future.

Autophagy facilitates the EGFR-TKI acquired resistance of non-small-cell lung cancer cells

Lung cancer is the leading cause of cancer-related mortality worldwide, with approximately 1.6 million new cases and 1.4 million deaths each year. Non-small-cell lung cancer (NSCLC) accounts for nearly 85% of all cases of lung cancer. Once diagnosed, the 5-year survival rate of NSCLC patients hardly reaches 15% despite many different treatments including surgery, radiotherapy, and chemotherapy being widely used. However, the therapeutic effect of chemotherapy is still not satisfactory in patients with advanced NSCLC and the response rate is only 20e35% with a median survival of 10e12 months. Epidermal growth factor receptor (EGFR) is overexpressed in many solid tumors including NSCLC, and the overexpression of EGFR can affect the pathogenesis of cancer, such as cell proliferation, invasion, and metastasis. Activated EGFR can recruit a number of downstream signaling molecules such as phosphatidylinositol 3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) and Ras-Raf-MAPK-ERK kinase (MEK). Thus, EGFR has been the focus of molecular-targeted therapies. Drugs that inhibit the tyrosine kinase activity of EGFR, such as the tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib, have been developed for the treatment of NSCLC. Although both

Empty Nose Syndrome May Be the Chief Criminal Behind Many of the Worst Atrocities against Rhinologic Medical Staff in China

On Sep 3, 2012, several rhinology specialized medical staff members in Shenzhen Pengcheng Hospital were stabbed by a patient with blood-covered hands; on Oct 25, 2013, a chief physician of the otolaryngology department of the first Peoples Hospital of Wenling, was killed in his clinic while working on a patient.

Ischemic preconditioning may attenuate lung ischemia-reperfusion injury partly by stimulating autophagy

Lung transplantation has become an important therapeutic strategy for patients with many end-stage pulmonary diseases. However, the mortality rate is still high in the early phase of lung transplantation, and primary graft dysfunction is a major cause of morbidity and mortality that occurs early in the post-transplantation period due to ischemiareperfusion injury (IRI). Because primary graft dysfunction is presumed to be mainly caused by IRI, it is important to develop effective therapeutic prevention and treatment strategies for lung transplantation. Ischemic preconditioning (IPC), which consists of brief and repetitive periods of IR prior to a sustained organ ischemia, was first discovered in 1986 by Murry et al. Many studies have demonstrated that IPC may be the most powerful innate protective mechanism against IRI and can attenuate the sustained IRI in several organs such as the heart, kidney, liver, and brain. Despite a number of substances such as adenosine, prostaglandins, nitric oxide, and some cytokines being proven effective in both the treatment of IRI and the protection of IPC, the exact information about the mechanism by which this protection in lung IRI works is still limited and needs further discussion.