ABSTRACT
Cancer cells and the immune system are closely related and thus influence each other. Although immune cells can suppress cancer cell growth, cancer cells can evade immune cell attack via immune escape mechanisms. Natural killer (NK) cells kill cancer cells by secreting perforins and granzymes. Upon contact with cancer cells, NK cells form immune synapses to deliver the lethal hit. Mature NK cells are differentiated from hematopoietic stem cells in the bone marrow. They move to lymph nodes, where they are activated through interactions with dendritic cells. Interleukin-15 (IL-15) is a key molecule that activates mature NK cells. The adoptive transfer of NK cells to treat incurable cancer is an attractive approach. A certain number of activated NK cells are required for adoptive NK cell therapy. To prepare these NK cells, mature NK cells can be amplified to obtain sufficient numbers of NK cells. Alternatively, NK cells can be differentiated and amplified from hematopoietic stem cells. In addition, the selection of donors is important to achieve maximal efficacy. In this review, we discuss the overall procedures and strategies of NK cell therapy against cancer.
Subject(s)
Humans , Cell Differentiation , Cell- and Tissue-Based Therapy , Gene Expression Regulation , Hematopoietic Stem Cells/cytology , Immunotherapy, Adoptive , Killer Cells, Natural/cytology , Lymphocyte Activation/immunology , Signal TransductionABSTRACT
BACKGROUND: Molecular mechanisms of natural killer (NK) cell development from hematopoietic stem cells (HSCs) have not been clearly elucidated, although the roles of some genes in NK cell development have been reported previously. Thus, searching for molecules and genes related NK cell developmental stage is important to understand the molecular events of NK cell development. METHODS: From our previous SAGE data-base, Gpnmb (Glycoprotein non-metastatic melanoma protein B) was selected for further analysis. We confirmed the level of mRNA and protein of Gpnmb through RT-PCR, quantitative PCR, and FACS analysis. Then we performed cell-based ELISA and FACS analysis, to know whether there are some molecules which can bind to Gpnmb. Using neutralizing antibody, we blocked the interaction between NK cells and OP9 cells, and checked IFN-gamma production by ELISA kit. RESULTS: Gpnmb expression was elevated during in vitro developmental stage and bound to OP9 cells, but not to NK precursor cells. In addition, we confirmed that the levels of Gpnmb were increased at NK precursor stage in vivo. We confirmed syndecan4 as a candidate of Gpnmb's binding molecule. When the interaction between NK cells and OP9 cells were inhibited in vitro, IFN-gamma production from NK cells were reduced. CONCLUSION: Based on these observations, it is concluded that Gpnmb has a potential role in NK cell development from HSCs.
Subject(s)
Antibodies, Neutralizing , Enzyme-Linked Immunosorbent Assay , Hematopoietic Stem Cells , Killer Cells, Natural , Melanoma , Polymerase Chain Reaction , RNA, Messenger , Syndecan-4ABSTRACT
Although N-myc downstream regulated gene 2 (NDRG2) has been known to be a tumor suppressor gene, the function of this gene has not been elucidated. In the present study, we investigated the expression and function of NDRG2 in human gastric cancer. Among seven gastric cancer and two non-cancer cell lines, only two gastric cancer cell lines, SNU-16 and SNU-620, expressed NDRG2, which was detected in the cytoplasm. Interestingly, NDRG2 was highly expressed in normal gastric tissues, but gastric cancer patients were divided into NDRG2-positive and -negative groups. The survival rate of NDRG2-negative patients was lower than that of NDRG2-positive patients. We confirmed that the loss of NDRG2 expression was a significant and independent prognostic indicator in gastric carcinomas by multivariate analysis. To investigate the role of NDRG2 in gastric cancer cells, we generated a NDRG2-silenced gastric cancer cell line, which stably expresses NDRG2 siRNA. NDRG2-silenced SNU-620 cells exhibited slightly increased proliferation and cisplatin resistance. In addition, inhibition of NDRG2 decreased Fas expression and Fas-mediated cell death. Taken together, these data suggest that inactivation of NDRG2 may elicit resistance against anticancer drug and Fas-mediated cell death. Furthermore, case studies of gastric cancer patients indicate that NDRG2 expression may be involved in tumor progression and overall survival of the patients.
Subject(s)
Humans , Apoptosis/physiology , Cell Line, Tumor , Down-Regulation , Fas Ligand Protein/physiology , Gene Expression Regulation, Neoplastic , Stomach Neoplasms/metabolism , Biomarkers, Tumor/metabolism , Tumor Suppressor Proteins/biosynthesisABSTRACT
BACKGROUND: Hemopoietic cells require the constant presence of growth factors for survival in vitro and in vivo. Caspases have been known as central executors of apoptotic cell death. We have, therefore, investigated the pathways that regulate caspase activity and apoptosis using the CD34+ cell line, TF-1 which requires GM-CSF for survival. METHODS: Apoptosis was measured by annexin V staining and mitochondrial membrane potential was measured by DiOC6 labelling. Intracellular pH was measured using pH sensitive fluorochrome, BCECF or SNARF-1, followed by flow cytometry analysis. Caspase activation was analyzed by PARP cleavage using anti-PARP antibody. RESULTS: Removal of GM-CSF induceed PARP cleavage, a hallmark of caspase activity, concomitant with pHi acidification and a drop in mitochondrial potential. Treatment with ZVAD, a competitive inhibitor of caspases, partially rescued cell death without affecting pHi acidification and the reduction of mitochondrial potential, suggesting that both these events act upstream of caspases. Overexpression of Bcl-2 prevented cell death induced by GM-CSF deprivation as well as pHi acidification and the reduction in mitochondrial membrane potential. In parental cells maintained with GM-CSF, EIPA, a competitive inhibitor of Na+/H+ antiporter induced apoptosis, accompanied by a drastic reduction in mitochondrial potential. In contrast, EIPA induced apoptosis in Bcl-2 transfectants without causing mitochondrial membrane depolarization. CONCLUSION: Taken together, our results suggest that the regulation of H fluxes, either through a mitochondrion- dependent or independent pathway, is central to caspase activation and apoptosis.