Related Experiment Videos
Natural killer cell as the effector which mediates in vivo apoptosis in AK-5 tumor cells
A Khar1, B V Pardhasaradhi, C Varalakshmi
1Centre for Cellular and Molecular Biology, Hyderabad, India.
Abstract:
AK-5 tumor cell death is mediated by natural killer cells through necrosis (perforin mediated) and apoptosis. Apoptosis is the mechanism which operates in immune animals in vivo. We have identified natural killer (NK) cell as the effector cell which induces apoptosis leading to tumor cell death in vivo. Naive NK cell which is unable to kill the AK-5 tumor cell can be activated with IL-2/IL-12 to make it capable of inducing apoptosis in tumor cells. NK cells from tumor-rejected animals show higher expression of Fas ligand and serine esterase granzyme B. In addition, NK cell-mediated apoptosis in AK-5 cells is totally abolished when effector cells are treated with anti-NKR-P1 mAb 3.2.3 and complement. NK cell-mediated apoptotic activity is inhibited in bcl-2 transfected tumor cells; however, the cytotoxic activity (perforin-mediated) remains unaffected. These observations suggest an important role for activated NK cells in inducing tumor cell death through necrosis (ADCC) and apoptosis leading to spontaneous regression of the AK-5 tumor in syngeneic animals.
Insights
Natural killer (NK) cells induce AK-5 tumor cell death via apoptosis and necrosis. Activated NK cells, enhanced by IL-2/IL-12, are crucial for tumor regression in vivo.
Area of Science:
- Immunology
- Cancer Biology
- Cell Death Mechanisms
Background:
- Natural killer (NK) cells play a role in tumor surveillance.
- Tumor cell death can occur through necrosis and apoptosis.
- Understanding NK cell effector mechanisms is vital for cancer immunotherapy.
Purpose of the Study:
- To identify the effector cells responsible for AK-5 tumor cell death in vivo.
- To elucidate the mechanisms of NK cell-mediated tumor cell death.
- To investigate the role of NK cell activation in tumor regression.
Main Methods:
- In vivo and in vitro studies using AK-5 tumor cells and natural killer (NK) cells.
- Cytokine activation of NK cells (IL-2/IL-12).
- Analysis of NK cell surface markers (Fas ligand, granzyme B) and functional assays (antibody-mediated complement lysis, bcl-2 transfection).
Main Results:
- NK cells were identified as the primary effector cells inducing apoptosis in AK-5 tumor cells in vivo.
- Activated NK cells (with IL-2/IL-12) demonstrated enhanced apoptotic activity.
- NK cells from tumor-rejected animals showed increased Fas ligand and granzyme B expression.
- NK cell-mediated apoptosis was inhibited by anti-NKR-P1 mAb and in bcl-2 transfected cells, while perforin-mediated cytotoxicity remained unaffected.
Conclusions:
- Activated NK cells are critical for inducing both apoptosis and necrosis in AK-5 tumor cells.
- NK cell-mediated apoptosis contributes significantly to spontaneous tumor regression.
- Targeting NK cell activation pathways may represent a viable cancer immunotherapy strategy.