ABSTRACT
<p><b>BACKGROUND AND OBJECTIVE</b>Intravesical administration of Bacillus Calmette-Guerin (BCG) after transurethral resection is by far the most effective local therapy for superficial bladder cancer, the fifth most common cancer in the world. However, approximately one-third of patients fail to respond and most patients eventually relapse. In addition, there are pronounced side effects of BCG therapy, such as BCG sepsis and a high frequency of BCG-induced cystitis. This study established a novel immunotherapy through immobilization of streptavidin-tagged human IL-2 (SA-hIL-2) on the biotinylated mucosal surface of bladder wall.</p><p><b>METHODS</b>A mouse orthotopic model of MB49 bladder cancer was established by perfusing MB49 cells into mouse bladders. The SA-hIL-2 fusion protein was immobilized on the biotinylated mucosal surface of the bladder wall. Treatment began on day 1 after MB49 implantation, once every 3 days for 6 times. Immunohistochemical assay was performed to assess the persistence of SA-hIL-2 immobilized on the biotinylated mucosal surface of the bladder wall. The mice were monitored for tumor growth and survival. On day 60 after MB49 implantation, the SA-hIL-2-cured mice, which were found to have no hematuria or palpable tumors, were challenged with wild-type MB49 cells implanted into the pretreated bladder and monitored for survival.</p><p><b>RESULTS</b>SA-hIL-2 could be immobilized efficiently and durably on the bladder mucosal surface as long as 7 days. On day 60 after MB49 implantation, 9 out of 20 SA-hIL-2-treated mice survived, but all mice in PBS control group died. More importantly, 5 out of 9 tumor-free mice in the SA-hIL-2 group were protected against a second intravesical wild-type MB49 tumor challenge.</p><p><b>CONCLUSIONS</b>SA-hIL-2 fusion protein could significantly inhibit tumor growth and extend the survival time in the orthotopic model of MB49 bladder cancer.</p>
Subject(s)
Animals , Female , Mice , Biotinylation , Cell Line, Tumor , Immobilized Proteins , Metabolism , Therapeutic Uses , Immunotherapy , Methods , Interleukin-2 , Metabolism , Therapeutic Uses , Mice, Inbred C57BL , Mucous Membrane , Metabolism , Neoplasm Transplantation , Receptors, Interleukin-2 , Metabolism , Recombinant Fusion Proteins , Metabolism , Therapeutic Uses , Streptavidin , Metabolism , Therapeutic Uses , Urinary Bladder , Pathology , Urinary Bladder Neoplasms , Allergy and Immunology , TherapeuticsABSTRACT
<p><b>OBJECTIVE</b>To obtain streptavidin-tagged human interleukin-15 (SA/hIL15) fusion protein and evaluate its bioactivity.</p><p><b>METHODS</b>pET24a-6His-SA-hIL-15 and pET32a-hIL-15-SA-6His plasmids were constructed and expressed in BL 21(DE3) host bacteria to generate the fusion protein. The recombinant fusion protein IL-15/SA was purified using Ni-NTA affinity chromatography and refolded, and the efficiency of surface modification of the fusion protein on biotinylated cells was examined by fluorescence-activated cell sorting. CCK-8 method was used to evaluate the effect of IL-15/SA fusion protein in inducing the proliferation of human peripheral-blood lymphocyte (PBL) cells stimulated by PHA.</p><p><b>RESULTS</b>The recombinant SA-hIL-15 and hIL15-SA fusion proteins were highly expressed in BL21(DE3) at about 20% of the total bacterial proteins. The purified hIL15-SA fusion protein exhibited a bifunctionality by promoting the proliferation of PBL cells activated by PHA and high-affinity binding to biotinylated cell surface mediated by SA, with a cell surface modification efficiency exceeding 95%. SA-hIL-15 showed a 4-fold higher hIL15 bioactivity than hIL15-SA.</p><p><b>CONCLUSION</b>SA/hIL-15 bifunctional fusion protein has been successfully obtained to facilitate the future development of hIL-15-surface-modified cancer cell vaccine.</p>
Subject(s)
Humans , Cancer Vaccines , Genetics , Allergy and Immunology , Escherichia coli , Genetics , Metabolism , Genetic Vectors , Interleukin-15 , Genetics , Lymphocyte Activation , Recombinant Fusion Proteins , Genetics , Allergy and Immunology , Streptavidin , GeneticsABSTRACT
<p><b>BACKGROUND</b>Activating on mammalian and human body LDR is thought to induce adaptive response, enhance immune function and increase anti-tumor ability. This study was designed to assess the effect of low-dose radiation on tumor growth and on erythrocyte immune function and superoxide dismutase (SOD) activity in tumor-bearing mice.</p><p><b>METHODS</b>Male Kunming mice were subcutaneously implanted with S180 sarcoma cells in the right inguen to create an experimental in situ animal model. Six hours before implantation, the mice were given 75 mGy X-ray radiation, over the body. Tumor size was observed 5 days later while tumor volume was calculated every other day, allowing for the creation of a graph depicting tumor growth. Fifteen days after implantation, the mice were killed to measure tumor weight and observe the necrotic areas and the location of tumor-infiltrating lymphocytes (TILs). Erythrocyte immune function and SOD activity were also determined.</p><p><b>RESULTS</b>Mice pre-exposed to low-dose radiation had a lower tumor formation rate than did those receiving no radiation (P < 0.05). Tumor growth was significantly lower in the mice pre-exposed to low-dose radiation; after 15 days, the average tumor weight in the mice pre-exposed to low-dose radiation was also lower (P < 0.05). Areas of tumor necrosis and infiltration of TILs were larger in the low-dose radiation group than in the non-radiation group. Erythrocyte immune function and SOD activity were higher in the low-dose radiation group than in the non-radiation group (P < 0.05).</p><p><b>CONCLUSION</b>Low-dose radiation can markedly increase the anti-tumor ability of an organism and improve erythrocyte immune function and red blood cell SOD activity as well, suggesting that low-dose radiation might be useful in the clinical treatment of cancer.</p>