Hypoxia-induced autophagy as an additional mechanism in human osteosarcoma radioresistance

AbstractOsteosarcoma (OS) responds poorly to radiotherapy, but the mechanism is unclear. We found OS tumor tissues expressed high level of protein HIF-1α, a common biological marker indicative of hypoxia. It is known that hypoxic cells are generally radioresistant because of reduced production of irradiation-induced DNA-damaging reactive oxygen species (ROS) in the anaerobic condition. Here we report another mechanism how hypoxia induces radioresistance. In MG-63 human osteosarcoma cells, hypoxic pretreatment increased the cellular survival in irradiation. These hypoxia-exposed cells displayed compartmental recruitment of GFP-tagged LC3 and expression of protein LC3-II, and restored the radiosensitivity upon autophagy inhibition. The following immunohistochemistry of OS tumor tissue sections revealed upregulated LC3 expression in a correlation with HIF-1α protein level, implying the possibly causative link between hypoxia and autophagy. Further studies in MG-63 cells demonstrated hypoxic pretreatment reduced cellular and mitochondrial ROS production during irradiation, while inhibition of autophagy re-elicited them. Taken together, our study suggests hypoxia can confer cells resistance to irradiation through activated autophagy to accelerate the clearance of cellular ROS products. This might exist in human osteosarcoma as an additional mechanism for radioresistance

Urban-Rural Disparity in Helicobacter Pylori Infection–Related Upper Gastrointestinal Cancer in China and the Decreasing Trend in Parallel with Socioeconomic Development and Urbanization in an Endemic Area

Background: Globally China has the largest urban-rural disparity in socioeconomic development, and the urban-rural difference in upper gastrointestinal cancer (UGIC) is similar to the difference between developed and developing countries. Objectives: To describe urban-rural disparity in UGIC and to emphasize prevention by socioeconomic development and urbanization in China. Methods: Age-standardized incidence rates (ASRs) of cancers in 2012 were compared between urban Shijiazhuang city and rural Shexian County, and trends from 2000-2015 in Shexian County were analyzed. Findings: Compared with urban Shijiazhuang city, the ASR of gastroesophageal cancers in rural Shexian County was 5.3 times higher in men (234.1 vs 44.2/100,000, 'P' 'Helicobacter pylori' infection prevalence of 75% vs 50%. From 2000-2015, the GDP per capita in Shexian County increased from US$860 to US$3000, urbanization rate increased from 22.4% to 54.8%, and prevalence of 'H pylori' infection among 3- to 10-year-old children decreased from 60% to 46.1% ('P' 'gallbladder cancers and leukemia in both sexes and breast, ovary, thyroid, and kidney cancer in women increased significantly. Despite this offset, ASR of all cancers combined decreased 25% in men (from 378.2 to 283.0/100,000, 'P' '=' '.'00) and 19% in women (from 238.5 to 193.6/100,000, 'P' '=' '.'00). ConclusionsUrban-rural disparity in UGIC is related to inequity in socioeconomic development. Economic growth and urbanization is effective for prevention in endemic regions in China and should be a policy priority

Overexpression of p65 attenuates celecoxib-induced cell death in MDA-MB-231 human breast cancer cell line

Abstract Background Celecoxib is a selective cyclooxygenase (COX)-2 inhibitor that has been reported to reduce the risk of breast cancer. In our previous study, celecoxib induced apoptosis and caused cell cycle arrest at the G0/G1 phase in the breast cancer cell line MDA-MB-231, and its effects were mediated by downregulation of NF-κB signaling. The NF-κB p65/RelA subunit may play a role in cell death through the activation of anti-apoptotic target genes including the inhibitor of apoptosis (IAP) and Bcl-2 families, and inhibition of protein kinase B/Akt. The aim of the present study was to investigate p65 as the potential target of celecoxib treatment and determine whether p65 overexpression can override the inhibitory effect of celecoxib on NF-κB activity and affect cell survival. Methods The effects of p65 overexpression on celecoxib-inhibited NF-κB transcriptional activity were examined by western blotting, electrophoretic mobility shift assay (EMSA) and luciferase reporter gene assay. Cell viability and cell death were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay, and the levels of cleaved poly(ADP-ribose) polymerase (PARP) and caspase. Anti-apoptotic NF-κB target genes and cell cycle regulators were examined by western blotting to screen for the expression of target genes under direct regulation by p65. Results Overexpression of p65 increased NF-κB transcriptional activity and interfered with celecoxib-mediated apoptosis as assessed by MTT assay and caspase-3, caspase-9, and PARP expressions. Exogenously overexpressed p65 upregulated NF-κB-responsive genes, including anti-apoptotic genes such as survivin and XIAP, and the cell cycle regulatory gene cyclin D1. However, p65 overexpression did not affect celecoxib-induced p-Akt inactivation, suggesting that celecoxib might have separate molecular mechanisms for regulating Akt signaling independently of its inhibition of NF-κB transcriptional activity. Conclusions p65 is a pivotal anti-apoptotic factor that can reverse celecoxib-induced growth inhibition in MDA-MB-231 cells.</p

Soluble c-Met Is a Reliable and Sensitive Marker to Detect c-Met Expression Level in Lung Cancer

c-Met has been demonstrated as an attractive target in lung cancer therapy. Current studies showed that detection of c-Met status in tumor is critical in Met-targeted therapy. However not all patients are suitable for tissue sample collection. It is important to discover novel surrogate markers to detect c-Met status. In the study, soluble c-Met (s-Met) in plasma from 146 Chinese lung cancer patients and 40 disease-free volunteers was measured by enzyme-linked immunosorbent. In parallel, expression of c-Met in those tumors was also assessed by immunohistochemistry. Results showed that, in 146 lung cancer patients, 93 were c-Met expression positive and 74 of 93 were overexpressed. In c-Met-overexpressed patients, plasma s-Met was significantly increased. And further studies showed that plasma s-Met linearly correlated with c-Met expression in tumor. After tumor was removed in Met-overexpressed patients via resection, plasma s-Met significantly decreased to basal level. In addition, plasma s-Met showed to be poorly correlated with tumor size in Met-overexpressed patients. These results demonstrated that plasma s-Met is a sensitive and reliable marker to detect c-Met overexpression in lung cancers, and it is independent of tumor volume

circCYP24A1 facilitates esophageal squamous cell carcinoma progression through binding PKM2 to regulate NF-κB-induced CCL5 secretion

Abstract Background Esophageal squamous cell carcinoma (ESCC) is a common gastrointestinal malignant tumor, while the molecular mechanisms have not been fully elucidated. Multiple circular RNAs have been reported to involve in the onset and progression of malignant tumors through various molecular mechanisms. However, the clinical significance and functional mechanism of most circRNAs involved in the progression of ESCC remains obscure. Methods RNA-Seq was used to explore potential circRNAs in participated in 5 pairs of ESCC and their corresponding normal esophageal tissues. The up-regulated circCYP24A1 was selected. Fluorescence in situ hybridization was cunducted to verificated the expression and intracellular localization of circCYP24A1 by using the tissue microarray. The Kaplan–Meier method and Cox proportional hazards model was used to examine the potential prognostic value of circCYP24A1 on overall survival of ESCC patients. The biological function were confirmed by gain- and loss-of-function approaches in vivo. mRNA expression profile microarray was proformed to investigate the downstream signaling pathways involved in circCYP24A1. RNA pull-down assay and mass spectrometry were performed to identify the proteins associated with circCYP24A1. Rescue experiments were carried out to identified hypothetical regulatory role of circCYP24A1 on ESCC progression in vivo and in virto. Results In this study, we identified circCYP24A1 in ESCC tissues by RNA sequencing, which is up-regulated in 114 cases of ESCC tissues and acts as a novel prognosis-related factor. Moreover, circCYP24A1 promoted the ability of proliferation, migration, invasion and clone formation in vitro, as well as tumor growth in vivo. Mechanistically, chemokine (C-Cmotif) ligand 5 (CCL5) is functional downstream mediator for circCYP24A1, which is screened by mRNA microarray. Moreover, circCYP24A1 physically interacts with M2 isoform of pyruvate kinase (PKM2). Rescue experiments showed that PKM2 knockdown partly reverses the promotional effects of circCYP24A1. It was revealed that circCYP24A1 increases secretion of CCL5 through the mechanism mainly by interacting with PKM2, an activator of NF-κB pathway, and thereby accelerate malignant progression of ESCC. Conclusions Up-regulated circCYP24A1 could activate NF-κB pathway by binding PKM2, which promotes the secretion of CCL5 and accelerate malignant progression of ESCC. Our fndings recommended a novel function for circCYP24A1 as a potential effective biomarker for judging prognosis and a therapeutic target in ESCC