ABSTRACT
The involvement of tumorassociated macrophages in tumor progression is an indisputable fact. However, whether the growthpromotion effects of macrophages towards tumors in the aggressive stage affect their own canceration remains unknown. In the present study, human glioma stem/progenitor cells transfected with red fluorescent protein gene (SU3RFP) were seeded inside the abdominal cavity of transgenic nude mice, of which all nucleated cells could express green fluorescent protein (GFP), forming a tumor model with a doublecolor RFP/GFP fluorescent tracer. Ascites and tumor nodules from tumorbearing mice were cultured, then the GFP+ cells were separated for clonal culture and further related phenotypic characterization and tumorigenicity tests. It was observed that the GFP+ cells isolated from ascites and solid tumors exhibited unlimited proliferative potential; the monoclonal cells were mouseoriginal, had a cancer cell phenotype and expressed the macrophage marker protein CD68. Thus, in the abdominal tumor model with doublecolor fluorescent tracer, macrophages recruited by tumor cells not only promoted tumor cell growth, but also exhibited their own canceration. This discovery is significant for the further study of tumor tissue remodeling and the tumor microenvironment.
Subject(s)
Glioma/metabolism , Glioma/pathology , Macrophages/metabolism , Neoplastic Stem Cells/metabolism , Animals , Cell Line, Tumor , Cell Proliferation , Disease Models, Animal , Disease Progression , Glioma/genetics , Heterografts , Humans , Mice , Transfection , Tumor BurdenABSTRACT
OBJECTIVE: During the process of tissue remodeling in human tumor transplantation models, the roles of the inoculated tumor cells and host tissue in tumor progression is still largely unknown. The aim of this study was to investigate the relationships and interactions between these two sides using GFP-RFP double fluorescence tracing technique. METHODS: Red fluorescence protein (RFP) gene was stably transfected into glioma stem cell line SU3, then SU3-RFP cells were transplanted into the brain of athymic nude mice with green fluorescence protein (GFP) expression. After the intracerebral tumors were formed, the relationship and interaction between GFP cells and RFP cells were analyzed. Highly proliferative GFP cells were screened out, and monocloned with micro-pipetting. DNA content assay, chromosome banding and carcinogenicity test of the GFP cells were performed to observe the GFP cells' cancerous phenotype in nude mice. RESULTS: In the transplantable tumor tissue, besides a great quantity of RFP cells, there were still a proportion of GFP cells and GFP/RFP fusion cells. The proportion of RFP cells, GFP cells and GFP/RFP cells were (88.99 ± 1.46)%, (5.59 ± 1.00)%, and (4.11 ± 1.020)%, respectively. Two monoclonal host GFP cells (H1 and H9) were cloned, which demonstrated the properties of immortality, loss of contact inhibition, and ultra-tetraploid when cultured in vitro. Both H1 and H9 cells expressed CNP, a specific marker of oligodendrocytes. The GFP cells also demonstrated 100% tumorigenic rate and high invasive properties in vivo. CONCLUSIONS: In this glioma transplantation model, the transplanted tumor tissues contained not only transplanted glioma stem cells but also cancerous host GFP cells. Our findings offer important clues to further research on the relationships among different members in the tumor microenvironment.
Subject(s)
Brain/cytology , Cell Transformation, Neoplastic , Glioma/pathology , Green Fluorescent Proteins/metabolism , Luminescent Proteins/metabolism , Neoplastic Stem Cells/cytology , Neuroglia/cytology , 2',3'-Cyclic Nucleotide 3'-Phosphodiesterase/metabolism , Animals , Brain/metabolism , Cell Communication , Cell Line, Tumor , Glioma/metabolism , Humans , Intermediate Filament Proteins/metabolism , Luminescent Proteins/genetics , Mice , Mice, Inbred C57BL , Mice, Nude , Neoplasm Transplantation , Neoplastic Stem Cells/metabolism , Nerve Tissue Proteins/metabolism , Nestin , Neuroglia/metabolism , Transfection , Tumor Microenvironment , Red Fluorescent ProteinABSTRACT
BACKGROUND: Currently, treatment of malignant gliomas with temozolomide in addition to surgical resection and radiotherapy remains the foundation of glioma therapy. In an effort to develop new therapeutic choices to treat malignant gliomas, we have designed slow-releasing microspheres that deliver temozolomide (P-TMZ). The local continuous release of temozolomide at the intracranial tumor site may overcome many obstacles associated with systemic delivery, which will help to further improving the therapeutic effects against malignant gliomas. METHODS: Slow-releasing microspheres containing 10 % temozolomide were prepared, the antitumor efficacy in vitro was evaluated with MTT assay, and the therapeutic efficacy in vivo against gliomas was assessed in human glioma (SGH44) nude mice s.c. and orthotopic xenograft models. RESULTS: A single local injection of P-TMZ led to significant reduction both in s.c. and orthotopic human SHG44 glioma xenografts. P-TMZ, BCNU and TMZ had significant antiglioma effect (P < 0.01), their IC50 value was all less than 10 µg/ml. Tumor inhibition ratio of P-TMZ, BCNU and TMZ in vivo was higher than empty microspheres P0 (P < 0.01); P-TMZ and BCNU showed higher antitumor efficacy than TMZ (P < 0.05). CONCLUSIONS: Our present results suggest that local delivery of slow-releasing temozolomide microspheres is effective for malignant gliomas. P-TMZ retained good antitumor activity and had better therapeutic effect against glioma both in vitro and in vivo, which provide a new choice for future clinical interstitial chemotherapy.
