Zipeng Lu

High expression of Galectin-1 in pancreatic stellate cells plays a role in the development and maintenance of an immunosuppressive microenvironment in pancreatic cancer

Galectin‐1 is implicated in making tumor cells immune privileged, in part by regulating the survival of infiltrating T cells. Galectin‐1 is strongly expressed in activated pancreatic stellate cells (PSCs); however, whether this is linked to tumor cell immune escape in pancreatic cancer is unknown. Galectin‐1 was knocked down in PSCs isolated from pancreatic tissues using small interfering RNA (siRNA), or overexpressed using recombinant lentiviruses, and the PSCs were cocultured with T cells. CD3+, CD4+ and CD8+ T cell apoptosis was detected by flow cytometry; T cell IL‐2, IL‐4, IL‐5 and INF‐γ production levels were quantified using ELISA. Immunohistochemical analysis showed increased numbers of PSCs expressed Galectin‐1 (p < 0.01) and pancreatic cancers had increased CD3+ T cell densities (p < 0.01) compared to normal pancreas or chronic pancreatitis samples. In coculture experiments, PSCs that overexpressed Galectin‐1 induced apoptosis of CD4+ T cells (p < 0.01) and CD8+ T cells (p < 0.05) significantly, compared to normal PSCs. Knockdown of Galectin‐1 in PSCs increased CD4+ T cell (p < 0.01) and CD8+ T cell viability (p < 0.05). Supernatants from T cells cocultured with PSCs that overexpressed Galectin‐1 contained significantly increased levels of Th2 cytokines (IL‐4 and IL‐5, p < 0.01) and decreased Th1 cytokines (IL‐2 and INF‐γ, p < 0.01). However, the knockdown of PSC Galectin‐1 had the opposite effect on Th1 and Th2 cytokine secretion. Our study suggests that the overexpression of Galectin‐1 in PSCs induced T cell apoptosis and Th2 cytokine secretion, which may regulate PSC‐dependent immunoprivilege in the pancreatic cancer microenvironment. Galectin‐1 may provide a novel candidate target for pancreatic cancer immunotherapy.

Persistent activation of pancreatic stellate cells creates a microenvironment favorable for the malignant behavior of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignant tumors with poor prognosis due to extremely high malignancy, low rate of eligibility for surgical resection and chemoradiation resistance. Increasing evidence indicate that the interaction between activated pancreatic stellate cells (PSCs) and PDAC cells plays an important role in the development of PDAC. By producing high levels of cytokines, chemotactic factors, growth factors and excessive extracellular matrix (ECM), PSCs create desmoplasia and a hypoxic microenvironment that promote the initiation, development, evasion of immune surveillance, invasion, metastasis and resistance to chemoradiation of PDAC. Therefore, targeting the interaction between PSCs and PDAC cells may represent a novel therapeutic approach to advanced PDAC, especially therapies that target PSCs of the pancreatic tumor microenvironment.

Galectin-1 secreted by activated stellate cells in pancreatic ductal adenocarcinoma stroma promotes proliferation and invasion of pancreatic cancer cells: an in vitro study on the microenvironment of pancreatic ductal adenocarcinoma.

Objectives: This study aimed to clarify that the activated pancreatic stellate cells (PaSCs) are the origin of the highly expressed galectin-1 in the stroma of pancreatic ductal adenocarcinoma (PDAC) tissue and to evaluate the effect of the secreted galectin-1 on proliferation and invasion ability of pancreatic cancer cell line CFPAC-1 in vitro. Methods: Different kinds of PaSCs were isolated from the normal or cancerous pancreatic tissues and cultured. Immunohistochemistry study, quantitative polymerase chain reaction, and Western blot were carried out to check the cellular origin of galectin-1 in PDAC tissue. By using modified Boyden chambers, in vitro coculture system of PaSCs was established with the pancreatic cancer cell line CFPAC-1 and based on which we assessed the proliferation and invasion ability of CFPAC-1 with or without galectin-1 antagonists. Results: We identified PaSCs as the primary source of the highly expressed galectin-1 in PDAC stroma. Galectin-1 secreted by PaSCs increased CFPAC-1 proliferative rate in the proliferation assay and facilitated CFPAC-1 infiltration in the invasion assay. Conclusions: Under malignant circumstances, PaSCs express and secret galectin-1, which could further promote the proliferation and invasion of cancer cells.

MiR200-upregulated Vasohibin 2 promotes the malignant transformation of tumors by inducing epithelial-mesenchymal transition in hepatocellular carcinoma

BackgroundHepatocellular carcinoma (HCC) typically relies on tumor transformation and angiogenesis for its malignant behavior, including growth and metastasis. Previously, we reported that Vasohibin2 (VASH2) is preferentially expressed in hepatocellular carcinoma (HCC) tumor tissues and promotes angiogenesis. Here, we further investigated the role of VASH2 in HCC tumor progression.ResultsBioinformatics analyses and luciferase reporter gene assays confirmed the post-transcriptional regulation of VASH2 by miR-200a/b/c. We then used HepG2 and Hep3B cells, two representative hepatic cancer cell lines, to examine the role of VASH2 in tumors. VASH2 knockdown in HepG2 cells inhibited epithelial-mesenchymal transition (EMT), but VASH2 overexpression in Hep3B cells promoted EMT. Western blot analyses showed that VASH2 promoted EMT through the ZEB1/2 pathway.ConclusionVASH2 promoted invasion, reduced apoptosis and increased the proportion of stem cells in vitro and in vivo. These results indicated that VASH2 expression in HCC cells promotes the malignant transformation of tumors by inducing EMT.

Elevation of MMP-9 and IDO induced by pancreatic cancer cells mediates natural killer cell dysfunction

BackgroundNatural killer (NK) cells play a key role in non-specific immune response in different cancers, including pancreatic cancer. However the anti-tumor effect of NK cells decreases during pancreatic cancer progression. The regulatory pathways by which NK cells facilitate tumor immune escape are unclear, therefore our purpose was to investigate the roles of the contributory factors.MethodsNK cells isolated from fresh healthy peripheral blood were co-cultured with normal human pancreatic ductal cells hTERT-HPNE and human pancreatic cancer cell lines SW1990 and BxPc-3 in vitro. Then NK cell function was determined by Flow cytometric analysis of surface receptors and cytotoxic granules in NK cells, NK cell apoptosis and cytotoxicity, and Enzyme-linked immunosorbent assay of cytokines. Expression level of MMP-9, IDO and COX-2 in hTERT-HPNE and SW1990 cells were detected by quantitative RT-PCR. Statistical differences between data groups were determined by independent t-tests using SPSS 19.0 software.ResultsOur results showed that NK cell function was significantly downregulated following exposure to pancreatic cancer cells compared to normal pancreatic cells, as demonstrated by lower expressions of activating surface receptors (NKG2D, DNAM-1, NKp30 and NKp46) and cytotoxic granules (Perforin and Granzyme B); decreased secretion of cytokines (TNF-α and IFN-γ); and reduced cytotoxicity against myelogenous leukemia K562 cells. Further investigations revealed that MMP-9 and IDO may be implicated in SW1990 cell-induced NK cell dysfunction by facilitating tumor immune evasion. Blockade by TIMP-1 and/or 1-MT could partially restore NK function.ConclusionsTaken together, elevation of MMP-9 and IDO induced by pancreatic cancer cells mediates NK cell dysfunction. Our findings could contribute to the development of NK cell-based immunotherapy in patients with pancreatic cancer.

Vasohibin‑2 promotes proliferation in human breast cancer cells via upregulation of fibroblast growth factor‑2 and growth/differentiation factor‑15 expression

Vasohibin-2 (VASH2) is an angiogenic factor, and has been previously reported to be a cancer-related gene, with cytoplasmic and karyotypic forms. In the current study VASH2 expression in human breast cancer tissue and adjacent non-cancerous tissue was investigated with immunohistochemistry. MCF-7 and BT474 human breast cancer cells were transfected with lentiviral constructs to generate in vitro VASH2 overexpression and knockdown models. In addition, BALB/cA nude mice were inoculated subcutaneously with transfected cells to generate in vivo models of VASH2 overexpression and knockdown. The effect of VASH2 on cell proliferation was investigated using a bromodeoxyuridine assay in vitro and immunohistochemistry of Ki67 in xenograft tumors. Growth factors were investigated using a human growth factor array, and certain factors were further confirmed by an immunoblot. The results indicated that the expression level of cytoplasmic VASH2 was higher in breast cancer tissues with a Ki67 (a proliferation marker) level of ≥14%, compared with tissues with a Ki67 level of <14%. VASH2 induced proliferation in vitro and in vivo. Four growth factors activated by VASH2 were identified as follows: Fibroblast growth factor 2 (FGF2), growth/differentiation factor-15 (GDF15), insulin-like growth factor-binding protein (IGFBP)3 and IGFBP6. FGF2 and GDF15 may contribute to VASH2-induced proliferation. The current study identified a novel role for VASH2 in human breast cancer, and this knowledge suggests that VASH2 may be a novel target in breast cancer treatment.

Generation and characterization of rabbit polyclonal antibodies against Vasohibin-2 for determination of its intracellular localization

Vasohibin-2 was recently identified as an important pro-angiogenesis factor in solid tumor and intracellular localization of its variants is important for elucidating the downstream mechanism(s) of its effects. Currently there are no reported antibodies affordable for intracellular localization. The aim of this study was to generate and characterize polyclonal antibodies against Vasohibin-2 and to determine the intracellular localization of Vasohibin-2. In this study, two polypeptides were synthesized and one prokaryotic Vasohibin-2 recombinant protein was custom-made. New Zealand rabbits were immunized with the polypeptide mixture and prokaryotic recombinant protein, respectively. The purified antibodies from the antiserum were validated by ELISA, western blotting (WB), immunofluorescence (IF), immunohistochemistry (IHC) and immunoprecipitation (IP). In order to determine intracellular localization, the cytoplasmic and nuclear proteins of the human liver cancer cell line HepG2 were isolated for the detection of Vasohibin-2 by western blotting. Vasohibin-2 cDNA, coding for 311 and 355 amino acid residues, fused with or without a DDK/V5 tag at the c-terminus, respectively, was cloned into the Lv-CMV-EGFP vector. Lentiviruses were successfully packaged. Vasohibin-2-overexpressing HepG2-VASH2 (355 amino acid residues) and HepG2-VASH2-V5 (311 amino acid residues fused with V5 tag at the c-terminus) human liver cancer cell lines were established. Approximately 1-2x106 HepG2, HepG2-VASH2 and HepG2-VASH2-V5 cells were injected subcutaneously into the flanks of BALB/c nude mice. Xenograft tumors were harvested for immunohistochemistry. HepG2 cells were transiently transfected with the Lv-CMV-EGFP vectors containing Vasohibin-2 cDNA (coding for 311/355 amino acid residues with a DDK tag at the c-terminal), followed by anti-DDK immunofluorescence. The antibodies obtained were able to detect human VASH2 successfully as applied in western blotting, IF, IHC and IP. Results from IF, IHC and WB (post cytoplasmic/nuclear protein isolation) showed a quite different intracellular localization of VASH2 protein. The VASH2 (with 355 amino acid residues) was located in the cytoplasm while VASH2 (with 311 amino acid residues) was located in the nucleus. The former was found to be a relatively low abundance protein. We successfully generated three rabbit anti-human Vasohibin-2 polyclonal antibodies which can be used for western blotting, IF, IP and IHC. These antibodies will provide a convenient tool for further studies on Vasohibin-2. This is the first study to report differences in the intracellular localization of the VASH2 protein and, hence, a new research direction on the study of VASH2.

Activation of pancreatic stellate cells involves an EMT-like process

Pancreatic adenocarcinoma (PDAC) and chronic pancreatitis (CP) are characterized by a desmoplastic reaction involving activated pancreatic stellate cells (PSCs). However, the mechanisms of PSC activation remain poorly understood. We examined whether the epithelial-mesenchymal transition (EMT) process might play a role in PSC activation. PSCs were isolated from a rat pancreas and characterized using immunofluorescence and immunocytochemistry. We evaluated changes in cell motility and in the expression levels of a panel of EMT-related genes during the PSC activation process. Activation of PSCs occurred after 48 h of in vitro culture, as indicated by a morphological change to a myofibroblastic shape and a decrease in the number of cytoplasmic lipid droplets. After activation, PSCs showed enhanced cell migration ability compared to quiescent cells. In addition, the expression of epithelial markers (E-cadherin, BMP7 and desmoplakin) decreased, while expression of mesenchymal markers (N-cadherin, vimentin, fibronectin1, collagen1α1 and S100A4) increased in activated PSCs. EMT-related transcription factors (Snail and Slug) were also upregulated after PSC activation. The concurrent increase in cell migration ability and alterations in EMT-related gene expression suggests that the activation of PSCs involves an EMT-like process. The knowledge that PSC activation involves an EMT‑like process may help to identify potential new therapeutic targets to alleviate pancreatic fibrosis in diseases like CP and PDAC.

Vasohibin 2 reduces chemosensitivity to gemcitabine in pancreatic cancer cells via Jun proto-oncogene dependent transactivation of ribonucleotide reductase regulatory subunit M2.

BackgroundVasohibin 2 (VASH2) has previously been identified as an agiogenenic factor and a cancer related protein. Here we investigated the association of VASH2 expression and chemoresistance in pancreatic cancer.MethodsImmunohistochemical staining for VASH2 was performed on 102 human pancreatic cancer samples. Pancreatic cancer cell line models exhibiting overexpression or knockdown of VASH2 were generated. Gene expression analyses were carried out to determine genes differentially regulated by VASH2. Putative transcription factors that are downstream mediators of gene expression regulated by VASH2 were queried bioinformatically. Dual-luciferase reporter assays and ChIP assays were performed to confirm transactivation of target genes following VASH2 overexpression or knockdown.ResultsVASH2 protein expression was higher in human pancreatic cancer than in paired adjacent tissues and elevated VASH2 levels were associated with gemcitabine chemoresistance. In cell line models of pancreatic cancer, VASH2 expression induced gemcitabine chemoresistance in vitro and in vivo. It was discovered that expression of ribonucleotide reductase regulatory subunit M2 (RRM2) is regulated by VASH2; immunohistochemical analysis demonstrated a positive association of VASH2 expression and RRM2 expression in human pancreatic cancer tissues. Bioinformatics analyses revealed that induction of the Jun proto-oncogene (JUN) by VASH2 is responsible for upregulation of RRM2 expression; this JUN-dependent regulation of RRM2 by VASH2 was confirmed by chromatin immunoprecipitation and dual luciferase reporter assays, which demonstrated that JUN directly binds with the RRM2 promoter to activate transcription.ConclusionsThese data suggest that VASH2 reduces the chemosensitivity to gemcitabine in pancreatic cancer cells via JUN-dependent transactivation of RRM2.

Long non-coding RNA XLOC_000647 suppresses progression of pancreatic cancer and decreases epithelial-mesenchymal transition-induced cell invasion by down-regulating NLRP3

BackgroundLong non-coding RNAs (lncRNAs) play an important role in the development and progression of various tumors, including pancreatic cancer (PC). Recent studies have shown that lncRNAs can ‘act in cis’ to regulate the expression of its neighboring genes. Previously, we used lncRNAs microarray to identify a novel lncRNA termed XLOC_000647 that was down-regulated in PC tissues. However, the expression and function of XLOC_000647 in PC remain unclear.MethodsThe expression of XLOC_000647 and NLRP3 in PC specimens and cell lines were detected by quantitative real-time PCR. Transwell assays were used to determine migration and invasion of PC cells. Western blot was carried out for detection of epithelial-mesenchymal transition (EMT) markers in PC cells. The effect of XLOC_000647 on PC cells was assessed in vitro and in vivo. The function of NOD-like receptor family pyrin domain-containing 3 (NLRP3) in PC was investigated in vitro. In addition, the regulation of NLRP3 by XLOC_000647 in PC was examined in vitro.ResultsHere, XLOC_000647 expression was down-regulated in PC tissues and cell lines. The expression level of XLOC_000647 was significantly correlated to tumor stage, lymph node metastasis, and overall survival. Overexpression of XLOC_000647 attenuated cell proliferation, invasion, and EMT in vitro and impaired tumor growth in vivo. Further, a significantly negative correlation was observed between XLOC_000647 levels and its genomic nearby gene NLRP3 in vitro and in vivo. Moreover, XLOC_000647 decreased NLRP3 by inhibiting its promoter activity. Knockdown of NLRP3 decreased proliferation of cancer cells, invasion, and EMT in vitro. Importantly, after XLOC_000647 was overexpressed, the corresponding phenotypes of cells invasion and EMT were reversed by overexpression of NLRP3.ConclusionsTogether, these results indicate that XLOC_000647 functions as a novel tumor suppressor of lncRNA and acts as an important regulator of NLRP3, inhibiting cell proliferation, invasion, and EMT in PC.