Certain secretory proteins are known to be critical for maintaining the stemness of stem cells through autocrine signaling. However, the processes underlying the biogenesis, maturation, and secretion of these proteins remain largely unknown. Here we demonstrate that many secretory proteins produced by hematopoietic stem cells (HSCs) undergo exosomal maturation and release that is controlled by vacuolar protein sorting protein 33b (VPS33B). Deletion of VPS33B in either mouse or human HSCs resulted in impaired exosome maturation and secretion as well as loss of stemness. Additionally, VPS33B deficiency led to a dramatic delay in leukemogenesis. Exosomes purified from either conditioned medium or human plasma could partially rescue the defects of HSCs and leukemia-initiating cells (LICs). VPS33B co-existed in exosomes with GDI2, VPS16B, FLOT1, and other known exosome markers. Mechanistically, VPS33B interacted with the GDI2/RAB11A/RAB27A pathway to regulate the trafficking of secretory proteins as exosomes. These findings reveal an essential role for VPS33B in exosome pathways in HSCs and LICs. Moreover, they shed light on the understanding of vesicle trafficking in other stem cells and on the development of improved strategies for cancer treatment.

Vacuolar protein sorting 33B (VPS33B) is important for intracellular vesicular trafficking process and protein interactions, which is closely associated with the arthrogryposis, renal dysfunction, and cholestasis syndrome. Our previous study has shown a crucial role of Vps33b in regulating metabolisms of bile acids and lipids in hepatic Vps33b deficiency mice with normal chow, but it remains unknown whether VPS33B could contribute to cholestatic liver injury. In this study we investigated the effects of hepatic Vps33b deficiency on bile acid metabolism and liver function in intrahepatic cholestatic mice. Cholestasis was induced in Vps33b hepatic knockout and wild-type male mice by feeding 1% CA chow diet for 5 consecutive days. We showed that compared with the wild-type mice, hepatic Vps33b deficiency greatly exacerbated CA-induced cholestatic liver injury as shown in markedly increased serum ALT, AST, and ALP activities, serum levels of total bilirubin, and total bile acid, as well as severe hepatocytes necrosis and inflammatory infiltration. Target metabolomics analysis revealed that hepatic Vps33b deficiency caused abnormal profiles of bile acids in cholestasis mice, evidenced by the upregulation of conjugated bile acids in serum, liver, and bile. We further demonstrated that the metabolomics alternation was accompanied by gene expression changes in bile acid metabolizing enzymes and transporters including Cyp3a11, Ugt1a1, Ntcp, Oatp1b1, Bsep, and Mrp2. Overall, these results suggest a crucial role of hepatic Vps33b deficiency in exacerbating cholestasis and liver injury, which is associated with the altered metabolism of bile acids.

Melanoma is a life-threatening cancer with limited treatments. Retinoic acid-inducible gene I (RIG-I) is a cytosolic pattern recognition receptor (PRR) crucial to RNA virus sensing, interferon production, and tumor suppression. Quercetin, a natural flavonoid, has particularly therapeutic interests to prevent and treat cancer, for its pharmacological effects against oxidant, inflammation, and angiogenesis. Quercetin was investigated for its anti-melanoma activity and potential mechanisms in this study. We found that quercetin inhibited mouse melanoma growth in vivo, and suppressed proliferation and promoted apoptosis of both B16 and A375 cells in vitro. Quercetin upregulated IFN-α and IFN-β expression through activating RIG-I promoter in B16 cells. The induction of IFN-α and IFN-β, which could be severely impaired by silencing RIG-I induced interferon stimulated genes (ISGs). Moreover, RIG-I likely amplifies antitumor effects by activating signal transduction and activator of transcription 1 (STAT1) in the IFN-JAK-STAT pathway in an autocrine and paracrine manner. Our study provided novel insights regarding biological and anti-proliferative activities of quercetin against melanoma, and we identified RIG-I as a potential target in anti-tumor therapies.

Vascular protein sorting-associated protein 33B (VPS33B) plays important roles in hepatic polarity, which directly maintains the functional structure of the liver. It has reported that VPS33B has close association with arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome. Unfortunately, no further studies were conducted to reveal the role of Vps33b in the homeostasis of bile acids. In the current study, hepatic Vps33b-depleted male mice were used to investigate the metabolomics and lipidomics profiles of hepatic Vps33b deficiency based on ultrahigh-performance liquid chromatography coupled with an electrospray ionization high-resolution mass spectrometry (UHPLC-ESI-HRMS) system. Hepatic Vps33b-depleted male mice displayed cholestasis and slight liver damage with increased serum levels of ALT, AST, ALP and T-Bili compared to wild-type mice. Targeted metabolomics analysis of bile acids revealed that increased taurine-conjugated bile acids accumulated in the serum of hepatic Vps33b-depleted mice, while unconjugated bile acids were prone to decrease, accompanied by the regulation of bile acid homeostasis-related genes. In addition, lipid profiles were significantly altered with the lack of Vps33b in the liver. A variety of lipids, such as triglycerides and sphingomyelins, were significantly decreased in the liver and increased in the serum of hepatic Vps33b-depleted mice compared to those in wild-type mice. Our study demonstrated that Vps33b influences the progress of liver metabolism both in bile acid circulation and lipid metabolism, which is involved in the progression of liver cholestasis in mice.

INTRODUCTION:Specific oncogenotypes can produce distinct metabolic changes in cancer. Recently it is considered that metabolic reprograming contributes heavily to drug resistance. Aldehyde dehydrogenase 1A1 (ALDH1A1), is overexpressed in drug resistant lung adenocarcinomas and may be the cause of acquired drug resistance. However, how ALDH1A1 affects metabolic profiling in lung adenocarcinoma cells remains elusive.OBJECTIVE:We sought to investigate metabolic alterations induced by ALDH1A1 in lung adenocarcinoma in order to better understand the reprogramming and metabolic mechanism of resistance induced by ALDH1A1.METHODS:Metabolic alterations in lung adenocarcinoma HCC827-ALDH1A1 cells were analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). HCC827-ALDH1A1 metabolic signatures were extracted by univariate and multivariate statistical analysis. Furthermore, metabolite enrichment analysis and pathway analysis were performed using MetaboAnalyst 4.0 software.RESULTS:Twenty-two metabolites were positively identified using authentic standards, including uridine monophosphate (UMP), uridine diphosphate (UDP), adenosine diphosphate (ADP), malic acid, malonyl-coenzyme A, nicotinamide adenine dinucleotide (NAD), coenzyme A and so on. Furthermore, metabolic pathway analysis revealed several dysregulated pathways in HCC827-ALDH1A1 cells, including nucleotide metabolism, urea cycle, tricarboxylic acid (TCA) cycle, and glycerol phospholipid metabolism etc. CONCLUSION: Lung cancer is the most frequent cause of cancer-related deaths worldwide. Nearly all patients eventually undergo disease progression due to acquired resistance. Mechanisms of biological acquired resistance need to be identified. Our study identified altered metabolites in HCC827-ALDH1A1 cells, enhancing our knowledge of lung adenocarcinoma metabolic alterations induced by ALDH1A1, creating a novel therapeutic pathway. These metabolic signatures of ALDH1A1 overexpression may shed light on molecular mechanisms in drug-resistant tumors, and on candidate drug targets. Furthermore, new molecular targets may provide the foundation for potential anticancer strategies for lung cancer therapy.

Background: Acquired resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) such as erlotinib is a major challenge to achieve an overall clinical benefit of the targeted therapy. Recently, aldehyde dehydrogenase 1 (ALDH1) induction has been found to render lung adenocarcinomas resistant to EGFR-TKIs, and targeting ALDH1A1 becomes a novel strategy to overcome resistance. However, the molecular mechanism underlying such effect remains poorly understood. Methods: Comprehensive assays were performed in a panel of lung adenocarcinoma cell lines and xenografts that acquired resistance to erlotinib. Cancer phenotype was evaluated by cell viability, apoptosis, migration, and epithelial-mesenchymal transition analysis in vitro, tumorsphere formation analysis ex vivo, and tumor growth and dissemination analysis in vivo. Reactive oxygen species (ROS) and reactive carbonyl species (RCS) were detected based on fluorescent oxidation indicator and liquid chromatography coupled to mass spectrometry, respectively. Protein target was suppressed by RNA interference and pharmacological inhibition or ecto-overexpressed by lentivirus-based cloning. Gene promoter activity was measured by dual-luciferase reporting assay. Results: Knockdown or pharmacological inhibition of ALDH1A1 overcame erlotinib resistance in vitro and in vivo. ALDH1A1 overexpression was sufficient to induce erlotinib resistance. Metabolomic analysis demonstrated lower ROS-RCS levels in ALDH1A1-addicted, erlotinib-resistant cells; in line with this, key enzymes for metabolizing ROS and RCS, SOD2 and GPX4, respectively, were upregulated in these cells. Knockdown of SOD2 or GPX4 re-sensitized the resistant cells to erlotinib and the effect was abrogated by ROS-RCS scavenging and mimicked by ROS-RCS induction. The ALDH1A1 overexpressed cells, though resisted erlotinib, were more sensitive to SOD2 or GPX4 knockdown. The ALDH1A1 effect on erlotinib resistance was abrogated by ROS-RCS induction and mimicked by ROS-RCS scavenging. Detection of GPX4 and SOD2 expression and analysis of promoter activities of GPX4 and SOD2 under the condition of suppression or overexpression of ALDH1A1 demonstrated that the RCS-ROS-metabolic pathway was controlled by the ALDH1A1-GPX4-SOD2 axis. The ROS-RCS metabolic dependence mechanism in ALDH1A1-induced resistance was confirmed in vivo. Analysis of public databases showed that in patients undergoing chemotherapy, those with high co-expression of ALDH1A1, GPX4, and SOD2 had a lower probability of survival. Conclusions: ALDH1A1 confers erlotinib resistance by facilitating the ROS-RCS metabolic pathway. ALDH1A1-induced upregulation of SOD2 and GPX4, as well as ALDH1A1 itself, mitigated erlotinib-induced oxidative and carbonyl stress, and imparted the TKI resistance. The elucidation of previously unrecognized metabolic mechanism underlying erlotinib resistance provides new insight into the biology of molecular targeted therapies and help to design improved pharmacological strategies to overcome the drug resistance.

Objective: To explore the role and mechanism of ALDH1A1 in the chemotherapy resistance of lung adenocarcinoma cells, and provide experimental basis for clinical treatment of lung cancer and development of new drugs. Methods: Lentivirus was used to establish a lung adenocarcinoma cell model with ALDH1A1 overexpression, which was verified by flow cytometry and western blot.CCK8 was then used to detect the resistance of ALDH1A1 overexpressed lung adenocarcinoma cells to common anti-lung cancer drugs such as cisplatin (DDP), paclitaxel, erlotinib and gefitinib. The effect of ALDH1A1 overexpression on the stemness and EMT characteristics of lung adenocarcinoma cells were investigated by detecting the CSC and EMT markers and cell migration. Disulfiram (DSF) is an inhibitor of ALDH. We investigated the effects of DSF on the growth and migration of LACs in vitro by CCK8 cell viability assay and transwell migration assay. Inhibitory effect of DSF combined with erlotinib was detected on the subcutaneous xenografts of HCC827-ALDH1A1 cells in vivo. Results: Overexpression of ALDH1A1 induced different degrees of resistance in lung adenocarcinoma cells to erlotinib, gefitinib, paclitaxel and cisplatin. Stem cell markers CD44, CD133 and EMT mesenchymal marker vimentin were upregulated. Transwell results showed that the migration of lung adenocarcinoma cells with ALDH1A1 overexpression was enhanced. DSF, a targeting inhibitor of ALDH, selectively inhibits the increased migration of lung adenocarcinoma cells overexpressing ALDH1A1, overcomes the growth of subcutaneous xenografts of HCC827-ALDH1A1 cells and delays drug resistance in vivo. Conclusions: ALDH1A1 can induce lung adenocarcinoma cells to develop resistance to various anti-lung cancer drugs and endue cells with stemness. Targeted inhibition of ALDH enzyme activity can overcome the drug resistance caused by the overexpression of ALDH1A1, providing a new idea for clinical treatment of lung cancer.

Polarity defects are frequently involved in liver diseases, such as chronic hepatitis and hepatocellular carcinoma (HCC). It was reported that vacuolar protein sorting 33B (Vps33b) plays critical roles in the maintenance of hepatocyte polarity; however, the functional roles and mechanisms of Vps33b in HCC occurrence and progression remain unknown. First of all, we showed that Vps33b is down‐regulated in human and mouse liver cancer samples, and the low expression levels of Vps33b correlate with the poor prognosis of many HCC patients. Liver‐specific Vps33b deficiency induces liver damage, progressive hepatitis, fibrosis, and HCC in male mice, indicating that Vps33b is a crucial contributory factor to hepatocarcinogenesis. Vps33b deficiency–caused liver damage was primarily due to the disorders of structural and functional hepatocyte polarity, which were reflected by the decreased protein levels of E‐cadherin because of inaccurate location to lysosomes and polarity defects at both apical and lateral plasma membrane proteins. The results of a mechanism study revealed that Vps33b interacts with VPS33B‐interacting protein, which is involved in polarity and apical protein restriction; vesicle‐trafficking protein Sec22b; and Flotillin‐1 in hepatocytes and is in charge of the normal distribution of polarity‐determined proteins. Expression levels of Vps33b negatively correlated with the degree of inflammatory cell infiltration in livers from diethylnitrosamine‐induced or transgenic HCC mouse models, and the inflammatory stimuli suppressed the expression of Vps33b in vitro . Conclusion: Down‐regulation of Vps33b expression is a critical step for inflammation‐driven HCC, and Vps33b serves as an important tumor suppressor in hepatocarcinogenesis.

MAPKs play important roles in platelet activation. However, the molecular mechanisms by which MAPKs are regulated in platelets remain largely unknown. Real-time polymerase chain reaction and western blot data showed that MEKK3, a key MAP3K family member, was expressed in human and mouse platelets. Then, megakaryocyte/platelet-specific MEKK3-deletion (MEKK3-/- ) mice were developed to elucidate the platelet-related function(s) of MEKK3. We found that agonist-induced aggregation and degranulation were reduced in MEKK3-/- platelets in vitro. MEKK3 deficiency significantly impaired integrin αIIbβ3-mediated inside-out signaling but did not affect the outside-in signaling. At the molecular level, MEKK3 deficiency led to severely impaired activation of extracellular signal-regulated kinases 1/2 (ERK1/2) and c-Jun NH2-terminal kinase 2 but not p38 or ERK5. In vivo, MEKK3-/- mice showed delayed thrombus formation following FeCl3-induced carotid artery injury. Interestingly, the tail bleeding time was normal in MEKK3-/- mice. Moreover, MEKK3-/- mice had fewer microthrombi, reduced myocardial infarction (MI) size, and improved post-MI heart function in a mouse model of MI. These results suggest that MEKK3 plays important roles in platelet MAPK activation and may be used as a new effective target for antithrombosis and prevention of MI expansion.

Mutations of vacuolar protein sorting‐associated protein 33b (VPS33B) cause arthrogryposis, renal dysfunction, and cholestasis syndrome, and a lack of platelet α‐granules in the affected patients. Conditional Vps33b knockout mice were developed to investigate the function(s) of Vps33b in platelet α‐granule formation. We found that early embryonic deletion of Vps33b was lethal. PF4‐Cre‐driven megakaryocyte‐targeted Vps33b gene deletion greatly diminished Vps33b expression in platelets, but had no effect on platelet α‐granule formation and protein content. Tamoxifen‐induced, haematopoietic stem cell (HSC)‐specific Vps33b deletion completely depleted Vps33b in platelets, caused the absence of α‐granules, and increased the number of vacuoles in platelets and megakaryocytes. VPS33B association with VIPAS39, α‐tubulin, and SEC22B was identified by co‐immunoprecipitation, mass spectra, and immunoblotting in human embryonic kidney 293T (HEK293T) cells. Also, pull‐down experiments revealed that VIPAS39 bound to intact VPS33B; in contrast, α‐tubulin and SEC22B separately interacted with the sec1‐like domains of VPS33B. Vps33b deficiency in megakaryocytes disturbs the redistribution of Vipas39 and Sec22b to proplatelets, and interrupted the co‐localization of Sec22b with Vwf‐positive vesicles. The data presented in this study suggest that Vps33b is involved in α‐granule formation possibly by facilitating the Vwf‐positive vesicular trafficking to α‐granule‐related vacuoles in megakaryocytes. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Glutamate behaves as the principal excitatory neurotransmitter in the vertebrate central nervous system and recently demonstrates intercellular signaling activities in periphery cancer cells. How the glutamatergic transmission is organized and operated in cancer stem cells remains undefined. We have identified a glutamatergic transmission circuit in embryonal carcinoma stem cells. The circuit is organized and operated in an autocrine mechanism and suppresses the cell proliferation and motility. Biological analyses determined a repertoire of glutamatergic transmission components, glutaminase, vesicular glutamate transporter, glutamate NMDA receptor, and cell membrane excitatory amino-acid transporter, for glutamate biosynthesis, package for secretion, reaction, and reuptake in mouse and human embryonal carcinoma stem cells. The glutamatergic components were also identified in mouse transplanted teratocarcinoma and in human primary teratocarcinoma tissues. Released glutamate acting as the signal was directly quantified by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Genetic and pharmacological abolishment of the endogenously released glutamate-induced tonic activation of the NMDA receptors increased the cell proliferation and motility. The finding suggests that embryonal carcinoma stem cells can be actively regulated by establishing a glutamatergic autocrine/paracrine niche via releasing and responding to the transmitter.

目的 通过准确测定细胞培养液中酪氨酸含量,无损地动态监测肺癌细胞系相较于非肿瘤细胞系的异常酪氨酸代谢.方法 收集16HBE、PC9和HCC827各细胞系培养24、48和72 h后的细胞培养液样本,通过建立基于酪氨酸替代分析物的HILIC-MS/MS方法,定量检测不同时间点各细胞培养液中的酪氨酸含量.结果 该方法在1～ 40 μg/mL的范围内表现出良好的线性关系(R=0.999 9),相对回收率为93.02％～102.53％,重复性好(3.91％～8.69％).结论 该方法适用于细胞培养液中酪氨酸的测定,可用于观察肺癌细胞系的特异性酪氨酸代谢.