The biological research of clinical behavior of laryngeal cancer.
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Aneuploidy↗
Biomedical subjects
Li Xin
Publications and source records attributed to Li Xin.
[Feeding of mixed-carbon-resource during the expression phase in cultivation of recombinant Pichia pastoris expressing angiostatin].
A recombinant strain of Pichia pastoris with a phenotype of Muts was used to produce angiostatin in a 5-L fermentor. The methanol utilization ability of the present strain was weak, which resulted in extremely low growth rate and angiostatin productivity during the expression phase with methanol as the sole carbon source. To enhance the cell density and angiostatin expression level, mixed-carbon-source of glycerol-methanol was used in the expression phase. The methanol concentration was well controlled at 5 g/L by a methanol sensor and control system, and glycerol was continuously fed into the fermentor to achieve a higher cell density. 120 g/L of cells and 39 mg/L of angiostatin were reached at the end of fermentation which lasted 110 h. The mean specific cell growth rate in the expression phase was 0.01 h(-1), and the mean specific angiostatin productivity was 0.006 mg/(g x h). According to the data obtained in several runs of fermentation in which glycerol was fed at different rates, a higher mean specific angiostatin productivity was reached at the mean specific cell growth rate of 0.012 h(-1). To avoid the repression of angiostatin expression caused by residual glycerol and ethanol accumulation due to overfeeding of glycerol, glycerol addition was controlled to produce continuous oscillations in dissolved oxygen, because the change of dissolved oxygen concentration could deliver the information of available carbon source in the fermentation broth. Controlled glycerol feeding also avoided the problem of oxygen limitation brought by high cell density, and thus decreased the cooling requirement of the fermentor. Cell density reached 150 g/L at the end of fermentation, and angiostatin level reached 108 mg/L after an expression period of 96 h when the mean specific growth rate was maintained at 0.012 h(-1) by using the glycerol feeding strategy to result in the oscillations in dissolved oxygen. The mean specific angiostatin productivity was improved to 0.02 mg/(g x h). The apparent cell yield on glycerol and methanol were respectively 0.69 g/g and 0.93 g/g, higher than those in the fermentation without using the feeding strategy with dissolved oxygen as the indicator of metabolism.
Angiostatins↗
Expression of colony-stimulating factor 1 receptor during prostate development and prostate cancer progression.
Colony-stimulating factor-1 receptor (CSF-1R) is the major regulator of macrophage development and is associated with epithelial cancers of the breast and ovary. Immunohistochemistry analysis of murine prostate development demonstrated epithelial expression of CSF-1R during the protrusion of prostatic buds from the urogenital sinus, during the prepubertal and androgen-driven proliferative expansion and branching of the gland, with a decline in older animals. Models of murine prostate cancer showed CSF-1R expression in areas of carcinoma- and tumor-associated macrophages. Several human prostate cancer cell lines and primary cultures of human prostate epithelial cells had low but detectable levels of CSF-1R. Human prostatectomy samples showed low or undetectable levels of receptor in normal glands or benign prostatic hypertrophy specimens. Staining was strongest in areas of prostatic intraepithelial neoplasia or carcinoma of Gleason histological grade 3 or 4. The activated form of the receptor reactive with antibodies specific for phosphotyrosine modified peptide sequences was observed in samples of metastatic prostate cancer. Immunohistochemistry showed strong expression of CSF-1R by macrophage lineage cells, including villous macrophages and the syncytiotrophoblast layer of placenta, Kupper cells in the liver, and histiocytes infiltrating near prostate cancers. These observations correlate CSF-1R expression with changes in the growth and development of the normal and neoplastic prostate.
Animals↗
Heterologous desensitization of opioid receptors by chemokines inhibits chemotaxis and enhances the perception of pain.
The chemokines use G protein-coupled receptors to regulate the migratory and proadhesive responses of leukocytes. Based on observations that G protein-coupled receptors undergo heterologous desensitization, we have examined the ability of chemokines to also influence the perception of pain by cross-desensitizing opioid G protein-coupled receptors function in vitro and in vivo. We find that the chemotactic activities of both mu- and delta-opioid receptors are desensitized following activation of the chemokine receptors CCR5, CCR2, CCR7, and CXCR4 but not of the CXCR1 or CXCR2 receptors. Furthermore, we also find that pretreatment with RANTES/CCL5, the ligand for CCR1, and CCR5 or SDF-1alpha/CXCL12, the ligand for CXCR4, followed by opioid administration into the periaqueductal gray matter of the brain results in an increased rat tail flick response to a painful stimulus. Because chemokine administration into the periaqueductal gray matter inhibits opioid-induced analgesia, we propose that the activation of proinflammatory chemokine receptors down-regulates the analgesic functions of opioid receptors, and this enhances the perception of pain at inflammatory sites.
Analgesics, Opioid↗
Mouse restin inhibits bovine aortic endothelial cell proliferation and causes cell apoptosis.
Restin, a homologous protein of endostatin, was found by Ramchandran et al. It was the C-terminal fragment of type XV collagen. To analysis the inhibition activity of mouse restin on the proliferation of endothelial cells, the cDNA of restin was amplified from the total RNA of the mouse muscle and cloned into the prokaryotic expression plasmid pQE32. The recombinant protein was expressed in inclusion body with a yield about 60%--70% of total protein. After refolding, the purified recombinant protein specifically inhibits bovine aortic endothelial (BAE) cell proliferation stimulated by basic fibroblast growth factor (bFGF) in a dose-dependent manner, but the activity of restin was weaker than that of endostatin. Treatment of BAE cell with recombinant restin caused G(1) arrest and apoptosis in BAE cells.
Amino Acid Sequence↗
[Restin expressed in vivo suppresses the growth of tumors in nude mice].
Restin, a homologous protein of endostatin (62% homology), is the NC domain of collagen XV at C-terminal. The recombinant restin expressed in E. coli had the ability to suppress the proliferation of bovin aortic endothelial cells and cause apoptosis. In this report, mouse restin gene was fused with a sequence of human plasminogen signal peptide by PCR and cloned into eukaryotic expression vector pCDNA3. The plasmid containing restin gene was named pCDNAXV and was transfected into human hepatoma cell line Bel7404. Stable transfected clones were screened and expression of restin was confirmed by RT-PCR and Western blot. The proliferated cells were injected subcutaneusly into nude mice. The growth of tumors formed by cells transfected with restin gene was much slower than that of control group. These results indicated that the expressed restin in vivo could suppress the growth of tumor, and this suppression might be achieved by restraining angiogenesis since the restin had no effect on the proliferation of tumor cells. At the same time, this report provided a new method to investigate the effect of anti-angiogenetic proteins on the tumor growth.
Animals↗
Expression of Human Angiostatin in Pichia pastoris and the Detection of Its Anti-angiogenic Activity.
Human angiostatin cDNA was amplified from human hepatoma cell line HepG2 using RT-PCR and was cloned into pPIC9K vector. Recombinant Pichia pastoris strain with 4 copies of angiostatin gene was obtained. Recombinant protein was purified by lysine-affinity Sepharose column and the finally purified angiostatin was 25 mg/L, higher than previously reported 17 mg/L. Amino acid sequence analysis revealed the identity of our protein the same with that previously reported. Recombinant angiostatin inhibited specifically the proliferation of bovine aortic endothelial cell stimulated by bFGF, with ED(50) being about 3 mg/L.
Journal Article↗