Project description:A major contributor to cancer mortality is recurrence and subsequent metastatic transformation following therapeutic intervention. In order to develop new treatment modalities or improve the efficacy of current ones it is important to understand the molecular mechanisms that promote therapy-resistance to cancer cells. One pathway that has been demonstrated to therapy resistance is autophagy, a self-digestive process that can eliminate unnecessary or damaged organelles to protect cancer cells from necrosis. Effective targeting of this pathway could lead to the development of new therapies. In our studies, we found that the VEGF-C/NRP-2 axis is involved in the activation of autophagy, which is essential for the survival of cancer cells following chemotherapy treatment. Furthermore, we identified two VEGF-C/NRP-2-regulated genes, LAMP-2 and WDFY-1 that have previously been suggested to participate in autophagy and vesicular trafficking. The upregulation of WDFY-1 upon depleted level of VEGF-C contributed to cytotoxic drug-mediated cell death. Altogether, these data suggest a link between VEGF-C/neuropilin-2 axis and cancer cell survival despite the presence of chemotherapy-induced stress. Human prostate cancer cell lines PC3, Du145 and pancreatic cancer cell line CaPan1 were cultured at 37οC either in RPMI 1640 with L-glutamine or in DMEM media with 10% fetal bovine serum and supplemented with penicillin/streptomycin. PC3 stable transfected cell line was growing in presence of 1µg/ml puromycin selection pressure. Cells were transfected with SmartPool cocktail siRNA for NRP-2, VEGF-C, LAMP-2, and WDFY-1, using DharmaFECT 1-4. siRNA transfection was allowed to proceed 72 h before collection of whole-cell extract or total RNA.To identify potential pathways involved in this VEGF-C-mediated cell survival, we performed a microarray study comparing cells depleted in either VEGF-C or NRP-2 using SmartPool siRNA to PC-3 cells treated with scrambled siRNA. Upon comparison of the two data sets, we found 34 gene-tags that were commonly up- or down-regulated in both NRP-2- and VEGF-C-depleted cells.

Project description:Vascular endothelial growth factor C (VEGF-C) is an angiogenic and lymphangiogenic growth factor. Recent research has revealed the role for VEGF-C in regulating autophagy by interacting with a nontyrosine kinase receptor, neuropilin-2 (NRP-2). However, whether VEGF-C participates in regulating cell survival and autophagy in renal proximal tubular cells is unknown. To address this question, we employed a cell modal of serum deprivation to verify the role of VEGF-C and its receptor NRP-2 in regulating cell survival and autophagy in NRK52E cell lines. The results show that VEGF-C rescued the loss of cell viability induced by serum deprivation in a concentration-dependent manner. Furthermore, endogenous VEGF-C was knocked down in NRK52E cells by using specific small-interfering RNAs (siRNA), cells were more sensitive to serum deprivation-induced cell death. A similar increase in cell death rate was observed following NRP-2 depletion in serum-starved NRK52E cells. Autophagy activity in serum-starved NRK52E cells was confirmed by western blot analysis of microtubule-associated protein-1 chain 3 (LC3), immunofluorescence staining of endogenous LC3, and the formation of autophagosomes by electron microscopy. VEGF-C or NRP-2 depletion further increased LC3 expression induced by serum deprivation, suggesting that VEGF-C and NRP-2 were involved in controlling autophagy in NRK52E cells. We further performed autophagic flux experiments to identify that VEGF-C promotes the activation of autophagy in serum-starved NRK52E cells. Together, these results suggest for the first time that VEGF-C/NRP-2 axis promotes survival and autophagy in NRK52E cells under serum deprivation condition. SIGNIFICANCE OF THE STUDY: More researchers had focused on the regulation of autophagy in kidney disease. The effect of VEGF-C on cell death and autophagy in renal epithelial cells has not been examined. We first identified the VEGF-C as a regulator of cell survival and autophagy in NRK52E cell lines. And VEGF-C/NRP-2 may mediate autophagy by regulating the phosphorylation of 4EBP1 and P70S6K. VEGF-C treatment may be identified as a therapeutic target in renal injury repair due to its capacity to promote tubular cell survival in the future.

Project description:A major contributor to cancer mortality is recurrence and subsequent metastatic transformation following therapeutic intervention. In order to develop new treatment modalities or improve the efficacy of current ones it is important to understand the molecular mechanisms that promote therapy-resistance to cancer cells. One pathway that has been demonstrated to therapy resistance is autophagy, a self-digestive process that can eliminate unnecessary or damaged organelles to protect cancer cells from necrosis. Effective targeting of this pathway could lead to the development of new therapies. In our studies, we found that the VEGF-C/NRP-2 axis is involved in the activation of autophagy, which is essential for the survival of cancer cells following chemotherapy treatment. Furthermore, we identified two VEGF-C/NRP-2-regulated genes, LAMP-2 and WDFY-1 that have previously been suggested to participate in autophagy and vesicular trafficking. The upregulation of WDFY-1 upon depleted level of VEGF-C contributed to cytotoxic drug-mediated cell death. Altogether, these data suggest a link between VEGF-C/neuropilin-2 axis and cancer cell survival despite the presence of chemotherapy-induced stress. Human prostate cancer cell lines PC3, Du145 and pancreatic cancer cell line CaPan1 were cultured at 37οC either in RPMI 1640 with L-glutamine or in DMEM media with 10% fetal bovine serum and supplemented with penicillin/streptomycin. PC3 stable transfected cell line was growing in presence of 1µg/ml puromycin selection pressure. Cells were transfected with SmartPool cocktail siRNA for NRP-2, VEGF-C, LAMP-2, and WDFY-1, using DharmaFECT 1-4. siRNA transfection was allowed to proceed 72 h before collection of whole-cell extract or total RNA.To identify potential pathways involved in this VEGF-C-mediated cell survival, we performed a microarray study comparing cells depleted in either VEGF-C or NRP-2 using SmartPool siRNA to PC-3 cells treated with scrambled siRNA. Upon comparison of the two data sets, we found 34 gene-tags that were commonly up- or down-regulated in both NRP-2- and VEGF-C-depleted cells.

Project description:Notwithstanding the numerous drugs available for liver cancer, emerging evidence suggests that chemotherapeutic resistance is a significant issue. HGF and its receptor MET play critical roles in liver carcinogenesis and metastasis, mainly dependent on the activity of receptor tyrosine kinase. However, for unknown reasons, all HGF-MET kinase activity-targeted drugs have failed or have been suspended in clinical trials thus far. Macroautophagy/autophagy is a protective 'self-eating' process for resisting metabolic stress by recycling obsolete components, whereas the impact of autophagy-mediated reprogrammed metabolism on therapeutic resistance is largely unclear, especially in liver cancer. In the present study, we first observed that HGF stimulus facilitated the Warburg effect and glutaminolysis to promote biogenesis in multiple liver cancer cells. We then identified the pyruvate dehydrogenase complex (PDHC) and GLS/GLS1 as crucial substrates of HGF-activated MET kinase; MET-mediated phosphorylation inhibits PDHC activity but activates GLS to promote cancer cell metabolism and biogenesis. We further found that the key residues of kinase activity in MET (Y1234/1235) also constitute a conserved LC3-interacting region motif (Y1234-Y1235-x-V1237). Therefore, on inhibiting HGF-mediated MET kinase activation, Y1234/1235-dephosphorylated MET induced autophagy to maintain biogenesis for cancer cell survival. Moreover, we verified that Y1234/1235-dephosphorylated MET correlated with autophagy in clinical liver cancer. Finally, a combination of MET inhibitor and autophagy suppressor significantly improved the therapeutic efficiency of liver cancer in vitro and in mice. Together, our findings reveal an HGF-MET axis-coordinated functional interaction between tyrosine kinase signaling and autophagy, and establish a MET-autophagy double-targeted strategy to overcome chemotherapeutic resistance in liver cancer. Abbreviations: ALDO: aldolase, fructose-bisphosphate; CQ: chloroquine; DLAT/PDCE2: dihydrolipoamide S-acetyltransferase; EMT: epithelial-mesenchymal transition; ENO: enolase; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GLS/GLS1: glutaminase; GLUL/GS: glutamine-ammonia ligase; GPI/PGI: glucose-6-phosphate isomerase; HCC: hepatocellular carcinoma; HGF: hepatocyte growth factor; HK: hexokinase; LDH: lactate dehydrogenase; LIHC: liver hepatocellular carcinoma; LIR: LC3-interacting region; PDH: pyruvate dehydrogenase; PDHA1: pyruvate dehydrogenase E1 alpha 1 subunit; PDHX: pyruvate dehydrogenase complex component X; PFK: phosphofructokinase; PK: pyruvate kinase; RTK: receptor tyrosine kinase; TCGA: The Cancer Genome Atlas.

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Autophagy control by the VEGF-C/NRP-2 axis in cancer and its implication for treatment resistance.

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Autophagy control by the VEGF-C/NRP-2 axis in cancer and its implication for treatment resistance.

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