Coadaptation fostered by the SLIT2-ROBO1 axis facilitates liver metastasis of pancreatic ductal adenocarcinoma.

To explore the mechanism of coadaptation and the potential drivers of pancreatic ductal adenocarcinoma (PDAC) metastasis to the liver, we study key molecules involved in this process and their translational value. Premetastatic niche (PMN) and macrometastatic niche (MMN) formation in a mouse model is observed via CT combined with 3D organ reconstruction bioluminescence imaging, and then we screen slit guidance ligand 2 (SLIT2) and its receptor roundabout guidance receptor 1 (ROBO1) as important factors. After we confirm the expression and distribution of SLIT2 and ROBO1 in samples from PDAC patients and several mouse models, we discover that SLIT2-ROBO1-mediated coadaptation facilitated the implantation and outgrowth of PDAC disseminated tumour cells (DTCs) in the liver. We also demonstrate the dependence receptor (DR) characteristics of ROBO1 in a follow-up mechanistic study. A neutralizing antibody targeting ROBO1 significantly attenuate liver metastasis of PDAC by preventing the coadaptation effect. Thus, we demonstrate that coadaptation is supported by the DR characteristics in the PMN and MMN.

Systemic Regulation of Cancer Development by Neuro-Endocrine-Immune Signaling Network at Multiple Levels.

The overarching view of current tumor therapies simplifies cancer to a cell-biology problem in which neoplasms are caused solely by malignant cells and the exploration of carcinogenesis and tumor progression largely focuses on somatic mutations and other genetic abnormalities of cancer cells. The limited therapeutic response indicates that cancer is driven not only by endogenous oncogenic factors and reciprocal interactions within the tumor microenvironment, but also by complex systemic processes. Homeostasis is the fundamental premise of health, and is maintained by systemic regulation of neuro-endocrine-immune axis. Cancer is also a systemic disease that manifested by dysfunction of the nervous, endocrine, and immune systems. Multiple axes of regulation exist in cancer, including central-, organ-, and microenvironment-level manipulation. At each specific regulatory level, the tridirectional communication among the nervous, endocrine, and immune factors transmit flexible signaling to induce proliferation, invasion, reprogrammed metabolism, therapeutic resistance, and other malignant phenotypes of cancer cells, resulting in the extremely poor prognosis of this lethal disease. Understanding this coordinated signaling network will enable the development of new approaches for cancer treatment via behavioral and pharmacological interventions.

MPC1 Deficiency Promotes CRC Liver Metastasis via Facilitating Nuclear Translocation of ß-Catenin.

Accumulating evidence has pointed out that metastasis is the leading cause of death in several malignant tumor, including CRC. During CRC, metastatic capacity is closely correlated with reprogrammed energy metabolism. Mitochondrial Pyruvate Carrier 1 (MPC1), as the carrier of transporting pyruvate into mitochondria, linked the glycolysis and TCA cycle, which would affect the energy production. However, the specific role of MPC1 on tumor metastasis in CRC remains unexplored. Here, by data mining of genes involved in pyruvate metabolism using the TCGA dataset, we found that MPC1 was significantly downregulated in CRC compared to nontumor tissues. Similar MPC1 expression pattern was also found in multiple GEO datasets. IHC staining in both human sample and AOM/DSS induced mouse CRC model revealed significant downregulation of MPC1. What is more, we found that MPC1 expression was gradually decreased in normal tissue, primary CRC, and metastasis CRC. Additionally, poor prognosis emerged in the MPC1 low expression patients, especially in patients with metastasis. Following, functional tests showed that MPC1 overexpression inhibited the motility of CRC cells in vitro and MPC1 silencing enhanced liver metastases in vivo. Furthermore, we uncovered that decreased MPC1 activated the Wnt/ß-catenin pathway by promoting nuclear translocation of ß-catenin to mediate the expression of MMP7, E-cadherin, Snail1, and myc. Collectively, our data suggest that MPC1 has the potential to be served as a promising biomarker for diagnosis and a therapeutic target in CRC.

Lysyl oxidase promotes liver metastasis of gastric cancer via facilitating the reciprocal interactions between tumor cells and cancer associated fibroblasts.

BACKGROUND: Liver is one of the most preferred destinations of distant metastasis in gastric cancer (GC). As effective treatment is still limited, the prognosis of GC patients bearing liver metastasis is poor. We filter out lysyl oxidase (LOX) to study its function in the tumor microenvironment (TME) and seek for potential therapeutic targets. METHODS: Transcription analysis on 6 cases of liver metastasis of GC patients with respective paired primary tumors and adjacent normal livers was performed. The filtration out of LOX was done using 5 datasets. 69 GC liver metastasis tissues were utilized to perform immunohistochemistry (IHC) and analyze prognosis. Computed Tomography (CT) combined 3D organ reconstruction bioluminescence imaging was performed to precisely evaluate the metastatic tumor burden on liver of intrasplenic injection mouse model. Human and mouse cancer associated fibroblasts (CAFs) in liver metastasis were separated to culture to study the interaction of LOX and TGF-ß1. Patients-derived xenograft (PDX) model was established using liver metastasis of patients to evaluate the therapeutic value of LOX inhibitor ß-aminopropionitrile (BAPN). RESULTS: CAFs-derived LOX at liver metastatic niche of GC promotes niche formation and outgrowth thus predicts poor prognosis. Meanwhile tumor cells in niche secrete TGF-ß1 to nourish CAFs and stimulate them to produce more LOX in turn. The mechanism involved in LOX-mediated proliferation facilitation is enhancement of Warburg effect. The inhibitor of LOX, BPAN could hamper the effect brought by LOX in vivo and in vitro. INTERPRETATION: Our study has unveiled a positive feedback loop between CAFs and tumor cells in liver metastasis niche of GC. The core molecule is LOX which facilitates Warburg effect. Targeting LOX with its inhibitor BAPN might serve as a potential therapeutic strategy. FUND: This research was supported by the National Natural Science Foundation of China (31872740), the 100-member plan of the Shanghai Municipal Commission of Health and Family Planning (2017BR043), Shanghai Science and Technology Commission Project(17ZR1416800), Renji Hospital Training Fund (PYMDT-003, PYIII-17-015), National Natural Science Foundation of China (81672358), the Shanghai Municipal Education Commission-Gao feng Clinical MedicineGrant Support (20181708), Program of Shanghai Academic/Technology Research Leader(19XD1403400), Science and Technology Commission of Shanghai Municipality (18410721000), Shanghai Municipal Health Bureau (2018BR32), China Postdoctoral Science Foundation (2018M640403), National Natural Science Foundation of China (81701945) and Youth project of Shanghai Municipal Health Commission(20164Y0045).

Alternative transcription start site selection in ACSS2 controls its nuclear localization and promotes ribosome biosynthesis in hepatocellular carcinoma.

Acetyl-CoA synthetase 2 (ACSS2) generates acetyl-CoA from acetate is important for histone acetylation and gene expression. ACSS2 fulfills distinct functions depending on its cellular location in tumor cells. The role and cellular localization of ACSS2 in hepatocellular carcinoma (HCC) remains to be studied. Herein, we identified that the alternative transcription start site selection of ACSS2 was significantly different between HCC and corresponding adjacent tissues. Alternative transcription start site selection produced two different ACSS2 transcripts, ACSS2-S1 and ACSS2-S2. The two isoforms of ACSS2 had different subcellular localization and different functions. Overexpression of ACSS2-S2 promoted cell proliferation and invasion, but ACSS2-S1 did not. The ACSS2-S1 was mainly present in cytoplasm, and ACSS2-S2 was distributed in both nucleus and cytoplasm. Finally, we demonstrated that alternative transcription start site selection of ACSS2 correlates ribosome biogenesis in HCC. Our findings reveal an oncogenic role of ACSS2-S2 in HCC progression via increase of ribosome biogenesis, and suggest ACSS2-S2 might be a potential therapeutic target against the HCC.

GABRP regulates chemokine signalling, macrophage recruitment and tumour progression in pancreatic cancer through tuning KCNN4-mediated Ca2+ signalling in a GABA-independent manner.

BACKGROUND AND AIMS: Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related death worldwide. Neurotransmitter-initiated signalling pathway is profoundly implicated in tumour initiation and progression. Here, we investigated whether dysregulated neurotransmitter receptors play a role during pancreatic tumourigenesis. METHODS: The Cancer Genome Atlas and Gene Expression Omnibus datasets were used to identify differentially expressed neurotransmitter receptors. The expression pattern of gamma-aminobutyric acid type A receptor pi subunit (GABRP) in human and mouse PDAC tissues and cells was studied by immunohistochemistry and western blot analysis. The in vivo implications of GABRP in PDAC were tested by subcutaneous xenograft model and lung metastasis model. Bioinformatics analysis, transwell experiment and orthotopic xenograft model were used to identify the in vitro and in vivo effects of GABRP on macrophages in PDAC. ELISA, co-immunoprecipitation, proximity ligation assay, electrophysiology, promoter luciferase activity and quantitative real-time PCR analyses were used to identify molecular mechanism. RESULTS: GABRP expression was remarkably increased in PDAC tissues and associated with poor prognosis, contributed to tumour growth and metastasis. GABRP was correlated with macrophage infiltration in PDAC and pharmacological deletion of macrophages largely abrogated the oncogenic functions of GABRP in PDAC. Mechanistically, GABRP interacted with KCNN4 to induce Ca2+ entry, which leads to activation of nuclear factor κB signalling and ultimately facilitates macrophage infiltration by inducing CXCL5 and CCL20 expression. CONCLUSIONS: Overexpressed GABRP exhibits an immunomodulatory role in PDAC in a neurotransmitter-independent manner. Targeting GABRP or its interaction partner KCNN4 may be an effective therapeutic strategy for PDAC.

Increased Serotonin Signaling Contributes to the Warburg Effect in Pancreatic Tumor Cells Under Metabolic Stress and Promotes Growth of Pancreatic Tumors in Mice.

BACKGROUND & AIMS: Desmoplasia and poor vascularity cause severe metabolic stress in pancreatic ductal adenocarcinomas (PDACs). Serotonin (5-HT) is a neuromodulator with neurotransmitter and neuroendocrine functions that contributes to tumorigenesis. We investigated the role of 5-HT signaling in the growth of pancreatic tumors. METHODS: We measured the levels of proteins that regulate 5-HT synthesis, packaging, and degradation in pancreata from KrasG12D/+/Trp53R172H/+/Pdx1-Cre (KPC) mice, which develop pancreatic tumors, as well as in PDAC cell lines and a tissue microarray containing 81 human PDAC samples. We also analyzed expression levels of proteins involved in 5-HT synthesis and degradation by immunohistochemical analysis of a tissue microarray containing 311 PDAC specimens, and associated expression levels with patient survival times. 5-HT level in 14 matched PDAC tumor and non-tumor tissues were analyzed by ELISA. PDAC cell lines were incubated with 5-HT and cell survival and apoptosis were measured. We analyzed expression of the 5-HT receptor HTR2B in PDAC cells and effects of receptor agonists and antagonists, as well as HTR2B knockdown with small hairpin RNAs. We determined the effects of 5-HT stimulation on gene expression profiles of BxPC-3 cells. Regulation of glycolysis by 5-HT signaling via HTR2B was assessed by immunofluorescence and immunoprecipitation analyses, as well as by determination of the extracellular acid ratio, glucose consumption, and lactate production. Primary PDACs, with or without exposure to SB204741 (a selective antagonist of HTR2B), were grown as xenograft tumors in mice, and SB204741 was administered to tumor-bearing KPC mice; tumor growth and metabolism were measured by imaging analyses. RESULTS: In immunohistochemical analysis of a tissue microarray of PDAC specimens, increased levels of TPH1 and decreased level of MAOA, which regulate 5-HT synthesis and degradation, correlated with stage and size of PDACs and shorter patient survival time. We found levels of 5-HT to be increased in human PDAC tissues compared with non-tumor pancreatic tissues, and PDAC cell lines compared with non-transformed pancreatic cells. Incubation of PDAC cell lines with 5-HT increased proliferation and prevented apoptosis. Agonists of HTR2B, but not other 5-HT receptors, promoted proliferation and prevented apoptosis of PDAC cells. Knockdown of HTR2B in PDAC cells, or incubation of cells with HTR2B inhibitors, reduced their growth as xenograft tumors in mice. We observed a correlation between 5-HT and glycolytic flux in PDAC cells; levels of metabolic enzymes involved in glycolysis, the phosphate pentose pathway, and hexosamine biosynthesis pathway increased significantly in PDAC cells following 5-HT stimulation. 5-HT stimulation led to formation of the HTR2B-LYN-p85 complex, which increased PI3K-Akt-mTOR signaling and the Warburg effect by increasing protein levels of MYC and HIF1A. Administration of SB204741 to KPC mice slowed growth and metabolism of established pancreatic tumors and prolonged survival of the mice. CONCLUSIONS: Human PDACs have increased levels of 5-HT, and PDAC cells increase expression of its receptor, HTR2B. These increases allow for tumor glycolysis under metabolic stress and promote growth of pancreatic tumors and PDAC xenograft tumors in mice.

Exemestane Attenuates Hepatic Fibrosis in Rats by Inhibiting Activation of Hepatic Stellate Cells and Promoting the Secretion of Interleukin 10.

Exemestane (EXE) is an irreversible steroidal aromatase inhibitor mainly used as an adjuvant endocrine therapy for postmenopausal women suffering from breast cancer. Besides inhibiting aromatase activity, EXE has multiple biological functions, such as antiproliferation, anti-inflammatory, and antioxidant activities which are all involved in hepatic fibrosis. Therefore, we investigated the role of EXE during the progress of hepatic fibrosis. The effect of EXE on liver injury and fibrosis were assessed in two hepatic fibrosis rat models, which were induced by either carbon tetrachloride (CCl4) or bile duct ligation (BDL). The influence of EXE treatment on activation and proliferation of primary rat hepatic stellate cells (HSCs) was observed in vitro. The results showed that EXE attenuated the liver fibrosis by decreasing the collagen deposition and α-SMA expression in vivo and inhibited the activation and proliferation of primary rat HSCs in vitro. Additionally, EXE promoted the secretion of antifibrotic and anti-inflammatory cytokine IL-10 in vivo and in HSC-T6 culture media. In conclusion, our findings reveal a new function of EXE on hepatic fibrosis and prompted its latent application in liver fibrotic-related disease.

Overexpressed EDIL3 predicts poor prognosis and promotes anchorage-independent tumor growth in human pancreatic cancer.

Epidermal Growth Factor-like repeats and Discoidin I-Like Domains 3 (EDIL3), an extracellular matrix (ECM) protein associated with vascular morphogenesis and remodeling, is commonly upregulated in multiple types of human cancers and correlates with tumor progression. However, its expression pattern and underlying cellular functions in pancreatic ductal adenocarcinoma (PDAC) remain largely unexplored. In current study, we observed that expression of EDIL3 was significantly up-regulated in PDAC compared with normal controls in both cell lines and clinical specimens. In addition, elevated EDIL3 expression was positively correlated with patients' TNM stage and T classification. Kaplan-Meier analysis indicated that high EDIL3 expression was significantly associated with shorter overall survival times in PDAC patients. Multivariate Cox regression analysis confirmed EDIL3 expression, age, lymph node metastasis and histological differentiation as independent prognostic factors in PDAC. Knockdown of EDIL3 showed no significant influence on cell viability, migration, invasion and starvation-induced apoptosis, but compromised anoikis resistance and anchorage independent tumor growth of PDAC cells. Meanwhile, treatment with recombinant EDIL3 protein markedly promoted anoikis resistance and anchorage independent tumor growth. Mechanistically, we demonstrated that altered protein expression of Bcl-2 family might contribute to the oncogenic activities of EDIL3. In conclusion, this study provides evidences that EDIL3 is a potential predictor and plays an important role in anchorage independent tumor growth of PDAC and EDIL3-related pathways might represent a novel therapeutic strategy for treatment of pancreatic cancer.

Elevated autocrine EDIL3 protects hepatocellular carcinoma from anoikis through RGD-mediated integrin activation.

BACKGROUND: A remolded microenvironment in hepatocellular carcinoma (HCC) caused by abnormally expressed matricellular proteins could promote HCC progression. The cell-matrix interactions mediated by integrins play an important role in tumor microenvironment. Epidermal Growth Factor-like repeats and Discoidin I-Like Domains 3 (EDIL3), an extracellular matrix (ECM) protein with angiogenic and anti-inflammatory effects, is abnormally highly expressed in HCC. Here we aim to analyze its expression in liver and HCC tissues, investigate the underlined mechanisms accounted for HCC progression. METHODS: EDIL3 expression level is examined in normal liver, cirrhotic liver and HCC at both mRNA and protein level. The association between EDIL3 and clinical outcomes is analyzed. The pattern of EDIL3 expression and location is examined using Immunofluorescence and ELISA. Overexpression or knock-down of EDIL3 in a panel of cell lines are subjected to assays related to proliferation, invasion, and anoikis to investigate the mechanisms of this matrix protein in HCC progression. Recombinant EDIL3 treatment is applied to confirm the results. RESULTS: Compared with normal liver and cirrhotic liver, EDIL3 is elevated in HCC. High level of EDIL3 protein is much more commonly in patients with larger tumor or portal vein tumor thrombus (PVTT) formation, associated with poor prognosis. EDIL3 is abundantly expressed in HCC cells and secreted by cancer cells. In vitro and in vivo studies indicate that EDIL3, probably in an autocrine manner, inhibits anoikis and promotes anchorage-independent growth of HCC cells. Further mechanistic studies suggest integrin ligation by EDIL3 and thus that the sustained activation of the FAK-Src-AKT signal is responsible for the anoikis resistance and anchorage independence. Both the administration of cilengitide, a RGD-containing integrin antagonist, and silencing of integrin αV, an important RGD-binding integrin, results in the blockade of anoikis-resistance induced by EDIL3. CONCLUSION: Our study suggests that high levels of autocrine EDIL3 may contribute to a receptive microenvironment for the survival of detached HCC cells and may involve in cancer cell spreading. We also highlight the importance of interaction between EDIL3 and integrin αV and suggest disrupting the ligation of EDIL3 to integrins via RGD-blocking in selected patients may bear potential therapeutic value.

Monoamine oxidase A suppresses hepatocellular carcinoma metastasis by inhibiting the adrenergic system and its transactivation of EGFR signaling.

BACKGROUND & AIMS: Monoamine oxidase A (MAOA), a catecholamine neurotransmitter degrading enzyme, is closely associated with neurological and psychiatric disorders. However, its role in cancer progression remains unknown. METHODS: Hepatocellular carcinoma (HCC) tissue arrays (n=254) were used to investigate the correlation between MAOA expression and clinicopathological findings. In vitro invasion and anoikis assays, and in vivo intrahepatic and lung metastasis models were used to determine the role of MAOA in HCC metastasis. Quantitative real-time PCR, western blotting, immunohistochemical staining and HPLC analysis were performed to uncover the mechanism of MAOA in HCC. RESULTS: We found that MAOA expression was significantly downregulated in 254 clinical HCC samples and was closely correlated with cancer vasoinvasion, metastasis, and poor prognoses. We then demonstrated that MAOA suppressed norepinephrine/epinephrine (NE/E)-induced HCC invasion and anoikis inhibition, and uncovered that the effects of NE/E on HCC behaviors were primarily mediated through alpha 1A (ADRA1A) and beta 2 adrenergic receptors (ADRB2). In addition to the canonical signaling pathway, which is mediated via adrenergic receptors (ADRs), we found that ADR-mediated EGFR transactivation was also involved in NE-induced HCC invasion and anoikis inhibition. Notably, we found that MAOA could synergize with EGFR inhibitors or ADR antagonists to abrogate NE-induced HCC behaviors. CONCLUSIONS: Taken together, the results of our study may provide insights into the application of MAOA as a novel predictor of clinical outcomes and indicate that increasing MAOA expression or enzyme activity may be a new approach that can be used for HCC treatment.

[Therapeutic effect of ovarian intra-arterial infusion of GE7-delivery system-mediated HSVl-tk/ganciclovir gene therapy in a rat model of malignant ovarian tumor].

OBJECTIVE: To observe the gene expression of herpes simplex virus type 1 thymidine kinase (HSVl-tk) in rat malignant ovarian tumor tissues and the therapeutic effect of ganciclovior (GCV) after intra-arterial infusion of HSVl-tk gene therapy mediated by GE7-delivery system. METHODS: A GE7-polylysine/pCMV-HSV1-tk/polylysine-HA20 4-element complex was constructed. Eighteen rats with DMBA-induced ovarian tumor were divided into 3 groups as Atk, ANS and Vtk groups. The 4-element complex GE7-polylysine/pCMV-HSV1-tk/polylysine-HA20 was injected via the ovarian artery into the rats of Atk group, saline buffer was injected in the ANS groups, and the 4-element complex was injected via the tail vein into the rats of Vtk group. All rats received intraperitoneal injection of GCV in a dose of 50 mg/kg daily for 10 days. The rats were sacrificed 3 days after the final dose of GCV, and the tumor weight was measured and tumor growth inhibition rate was calculated. Flow cytometry was used to assess the cell cycle and apoptosis. RESULTS: The tumor weight in the rats of Atk group was (4.77 ± 2.31) g, significantly lower than that of ANS group [(14.66 ± 6.26) g, P < 0.01] and Vtk group [(17.53 ± 7.19) g, P < 0.01]. The tumor growth inhibition rate of the Atk group was 67.5%, while that of Vtk group was -19.6%. The flow cytometry showed that S-phase tumor cells in the Atk group were (54.32 ± 9.65)%, significantly higher than that in the ANS (27.43 ± 9.22)% and (30.16 ± 11.57)% in the Vtk group (both P < 0.01). The tumor cell apoptosis rate in the Atk group was (39.15 ± 12.16)%, significantly higher than that in the ANS group [(11.86 ± 5.28)%, P < 0.01] and Vtk group [(14.32 ± 6.43)%, P < 0.01]. CONCLUSION: HSV1-tk/GCV gene therapy system mediated by GE7 non-viral delivery system via ovarian arterial infusion effectively causes cell cycle arrest at S phase and enhances cell apoptosis, therefore, exerts an inhibitory effect on tumor growth.

[Evaluation of GE7-transferring system-mediated HSV(1)-tk gene transfer in a rat model of ovarian tumor via intra-arterial route].

OBJECTIVE: To observe the gene and protein expression of herpes simplex virus type I-thymidine kinase (HSV(1)-tk) in the ovarian tumor tissues and other organs after arterial infusion of HSV(1)-tk gene mediated by GE7 delivery system. METHODS: GE7-polylysine/pCMV-HSV(1)-tk/polylysine-HA20 complexes were constructed. Nine rats with induced ovarian tumor were divided into 3 groups, injecting the 4-element complexes or saline buffer through the ovarian artery and complexes through the tail vein, respectively. The ovarian tumors, hearts, livers, spleens, lungs and kidneys were obtained at 72 hours after injection. RT-PCR and Western Blot were preceeded to determine the expression of HSV(1)-tk gene and protein in the tumor tissues and other organs. RESULTS: In the group of arterial injection with 4-element complexes, the HSV(1)-tk gene and protein were expressed strongly in the tumor tissues, while little or none was detected in other organs. In the group of arterial injection with saline buffer, no HSV(1)-tk gene and protein was detected in both tumor tissues and other organs. In the group of tail vein injection, none was detected in tumor tissues and only little was found in the livers, spleens, lungs and kidneys. CONCLUSION: High target and gene transfer rates can be obtained when HSV(1)-tk gene is transferred via the artery route mediated by GE7 delivery system. HSV(1)-tk protein can be expressed after the gene transfer. The results may provide a new strategy for target killing of HSV(1)-tk/GCV system in ovarian tumors.

Nicotine stimulated dendritic cells could achieve anti-tumor effects in mouse lung and liver cancer.

INTRODUCTION: Our previous studies have revealed that nicotine-treated immature dendritic cells (imDCs) have anti-tumor effects in murine lymphoma models. The present study is to explore the preventive and therapeutic anti-tumor effects of nicotine-treated imDCs in murine lung and liver cancer. MATERIALS AND METHODS: To address this objection, bone marrow-derived imDCs were firstly stimulated by nicotine in vitro and the expressions of CD80, CD86, CD40, CD11b, MHC class I and II were determined by flow cytometry. Then, DCs-dependent tumor-lysate-specific T cell proliferation, IL-12(p40+p70) secretion were determined by BrdU cell proliferation assay and enzyme-linked immunosorbent assay, respectively. The anti-tumor effects of such imDCs were further explored by intraperitoneal transfer against tumor challenge or implantation. By using kinase inhibitors, the mechanism of nicotine upregulating CD80 was finally explored by flow cytometry. RESULTS: The results showed that: firstly, nicotine could upregulate the expressions of CD80, CD86, CD40,CD11b, MHC class I and II molecules in imDCs. Secondly, nicotine could promote imDCs-dependent T cell priming and IL-12 secretion. Most importantly, systemic transfer of ex vivo nicotine-stimulated imDCs, which enhanced CD80 expression through PI3K activation, could reveal preventive and effectively therapeutic effects on tumor development. CONCLUSIONS: Ex vivo nicotine stimulation can significantly improve imDCs efficacy for adaptive therapy of cancer. Nicotine-treated imDCs might be considered as a potential candidate for therapeutic tumor immunotherapy for lung and liver cancer.

The piggyBac transposon is an integrating non-viral gene transfer vector that enhances the efficiency of GDEPT.

Gene-directed enzyme prodrug therapy (GDEPT) is a strategy developed to selectively target cancer cells. However, the clinical benefit is limited due to its poor gene transfer efficiency. To overcome this obstacle, we took advantage of piggyBac (PB) transposon, a natural non-viral gene vector that can induce stable chromosomal integration and persistent gene expression in vertebrate cells, including human cells. To determine whether the vector can also mediate stable gene expression in ovarian cancer cells, we constructed a PB transposon system that simultaneously expresses the Herpes simplex virus thymidine kinase (HSV-tk) gene and the monomeric red fluorescent protein (mRFP1) reporter gene. The recombinant plasmid, pPB/TK, was transfected into ovarian adenocarcinoma cells SKOV3 with FuGENE HD reagent, and the efficiency was given by the percentage of mRFP1-positive cells detected by flow cytometry and confocal microscopy. The specific expression of HSV-tk in transfected cells was confirmed by RT-PCR and western blotting. The sensitivity of transfected cells to pro-drug ganciclovir (GCV) was determined by methylthiazoletetrazolium (MTT) assay. A total of 56.4 +/- 8.4% cells transfected with pPB/TK were mRFP1 positive, compared to no measurable mRFP1 expression in pORF-HSVtk-transfected cells. The expression level of HSV-tk in pPB/TK-transfected cells was 10 times higher than in pORF-HSVtk-transfected cells. The results show that pPB/TK transfection increases the sensitivity of cells to GCV in a dose-dependent manner. Our data indicate that the PB transposon system could enhance the anti-tumor efficiency of GDEPT in ovarian cancer.

Peptide ligand-mediated liposome distribution and targeting to EGFR expressing tumor in vivo.

Epidermal growth factor receptor (EGFR) is an important anti-cancer therapy target that is applicable to many cancer types. We had previously reported the screening and discovery of a novel peptide ligand against EGFR named GE11. It was shown to bind to EGFR competitively with EGF and mediate gene delivery to cancer cells with high-EGFR expression. In this study, we conjugated GE11 on to liposome surface and examined their binding and distribution to EGFR expressing cancer cells in vitro and in vivo using fluorescence imaging techniques. GE11 liposomes were found to bind specifically and efficiently to EGFR high-expressing cancer cells. In vivo in H1299 xenograft mouse model, GE11 liposomes also extravasated and accumulated into the tumor site preferentially, and demonstrated better targeting and drug delivery capacities.

Development of efficient RNA interference system using EGF-displaying phagemid particles.

AIM: To develop an efficient RNA interference system using phagemid particles displaying the epidermal growth factor (EGF) ligand. METHODS: pSilencer1.0-siEGFP and pSilencer4.1-siAkt plasmids were constructed by gene clone technology. The modified helper phage genome (plasmid) M13KO7EGFCT was used to package phagemids, such as pSilencer1.0-siEGFP and pSilencer4.1-siAkt. ELISA was used to quantify the titer of the progeny virus particles. Single-strand DNA was extracted and analyzed by agarose gel electrophoresis to evaluate the percentage of the phagemid particles. The expression level of the reporter gene enhanced green fluorescence protein (EGFP) was determined by transducing phagemid particles packaging pSilencer1.0-siEGFP into cells. The level of Akt gene expression in cells transduced phagemid particles packaging pSilencer4.1-siAkt was examined by Western blotting. Hydroxycamptothecin (HCPT) was used to enhance the gene transduction efficiency. RESULTS: RNAi vectors pSilencer1.0-siEGFP and pSilencer4.1-siAkt were successfully constructed. Phagemid-encoding siRNA can be packaged efficiently. After the cells were infected by EGF displaying phagemid particles in the presence of HCPT, the expression of the target gene EGFP or Akt was substantially downregulated. CONCLUSION: Cell-targeted phagemid particles are efficient siRNA delivery vectors in the presence of HCPT.

Ex vivo nicotine stimulation augments the efficacy of therapeutic bone marrow-derived dendritic cell vaccination.

PURPOSE: To explore the preventive and therapeutic antitumor effects of nicotine-treated immature dendritic cells (imDC). EXPERIMENTAL DESIGN: First, bone marrow-derived imDCs were stimulated with nicotine in vitro, and nicotinic acetylcholine receptor, costimulator molecules, chemokine receptor, and endocytosis ability of imDCs were detected by flow cytometry. Second, the DC-dependent antigen-specific T-cell proliferation, CTL priming, and interleukin-12 secretion were determined by flow cytometry, enzyme-linked immunospot assay, and ELISA, respectively. Finally, preventive and therapeutic antitumor effects of such imDCs were determined by i.p. transfer against tumor challenge or implantation in mice. RESULTS: Nicotine could up-regulate expression of nicotinic acetylcholine receptor, costimulatory molecules, such as CD80, CD86, and CD40, adhesion molecule CD11b, and chemokine receptor CCR7 and enhance endocytosis ability of imDCs. In addition, nicotine could promote imDC-dependent CTL priming and interleukin-12 secretion in vitro. Most importantly, systemic transfer of ex vivo nicotine-stimulated imDCs could reveal preventive and therapeutic effect on tumor development. CONCLUSIONS: Ex vivo nicotine stimulation can significantly improve the efficacy of imDCs for adaptive therapy of cancer and nicotine-treated imDCs may be considered as a potential candidate for preventive and therapeutic tumor vaccination.

Application of EGFP-EGF fusions to explore mechanism of endocytosis of epidermal growth factor.

AIM: To develop a simple method for monitoring protein localization of epidermal growth factor (EGF) in living cells. METHODS: Enhanced green fluorescent protein (EGFP) was used as an autofluorescent tag to label EGF ligands. SDS-PAGE and Western blot analysis were used to detect the expression of the EGFP-tagged EGF (EGFP-EGF) protein. The cell-binding and internalization activity of EGFP-EGF were analyzed by fluorescence-activated cell sorting (FACS) and confocal microscopy. RESULTS: EGFP-EGF protein was expressed in Escherichia coli and purified. A cell-binding assay demonstrated that the EGFP-EGF protein could bind efficiently to the cells expressing EGFR. The binding and internalization of EGFP-EGF can be visualized even at a very low concentration under confocal microscopy. The FACS-based assay for internalization activity indicated the accumulation of internalized EGFP-EGF over time. Furthermore, the results of the competition assay indicated its EGFR binding specificity. Using such a method, it does not need to label EGF with chemicals and avoid light in the experimental process. CONCLUSION: The fusion protein EGFP-EGF has several characters including high sensitivity, stability and convenience for manipulation, and is a powerful tool for the study of EGF endocytosis.

[The effects of CT120B over-expression on growth suppression and changes of gene expression profiles in lung adenocarcinoma cells].

OBJECTIVE: CT120B gene is a splicing variant of CT120A, which deletes 96 nucleotides and leads to an in-frame loss of 32 amino acids between the codon 136 and 167 as compared with CT120A. This study was undertaken to assess the effects of CT120B expression on lung cancer cell growth and to explore the gene expression profiles. METHODS: CT120B cDNA was transfected into the human lung adenocarcinoma SPC-A-1 cells, and stable cell lines overexpressing CT120B were established. CCK-8 assay and tumorigenecity in a xenograft model were performed to analyze cell proliferation in vitro and in vivo. The differential gene expression induced by overexpressed CT120B was investigated using Atlas cDNA expression array. Flow cytometry was performed to analyze cell cycle and cell apoptosis. RESULTS: Overexpression of CT120B in SPC-A-1 cells resulted in a reduced cell growth rate in vitro, and decrease of the tumorigenicity in nude mice. A total of 38 genes were identified as differential expressions with more than a 2.0-fold change by Atlas cDNA expression array analysis, including downregulated cyclin E1, cdk 2, c-kit, CXCR4 and upregulated caspase 8 gene. Overexpression of CT120B also induced G1 phase arrest, but had no effect on cell apoptosis. CONCLUSION: The G1 cell cycle arrest, but not apoptosis, underlay the growth inhibitory activities of CT120B. The down-regulation of c-kit and CXCR4 expression might also contribute to the suppressive effects on cell growth of CT120B.