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Published on: November 2, 2014
Ovarian Cancer Ascites Inhibits Transcriptional Activation of NK Cells Partly through CA125
Christopher C Fraser1, Bin Jia1, Guangan Hu1
1Koch Institute for Integrative Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts.
Abstract:
Malignant ascites is a common clinical problem in ovarian cancer. NK cells are present in the ascites, but their antitumor activity is inhibited. The underlying mechanisms of the inhibition have yet to be fully elucidated. Using an Fcγ receptor-mediated NK cell activation assay, we show that ascites from ovarian cancer patients potently inhibits NK cell activation. Part of the inhibitory activity is mediated by CA125, a mucin 16 fragment shed from ovarian cancer tumors. Moreover, transcriptional analyses by RNA sequencing reveal upregulation of genes involved in multiple metabolic pathways but downregulation of genes involved in cytotoxicity and signaling pathways in NK cells purified from ovarian cancer patient ascites. Transcription of genes involved in cytotoxicity pathways are also downregulated in NK cells from healthy donors after in vitro treatment with ascites or with a CA125-enriched protein fraction. These results show that ascites and CA125 inhibit antitumor activity of NK cells at transcriptional levels by suppressing expression of genes involved in NK cell activation and cytotoxicity. Our findings shed light on the molecular mechanisms by which ascites inhibits the activity of NK cells and suggest possible approaches to reactivate NK cells for ovarian cancer immunotherapy.
Insights
Ovarian cancer ascites and CA125 inhibit natural killer (NK) cell antitumor activity by suppressing gene expression. This study reveals mechanisms for NK cell dysfunction in ovarian cancer, suggesting new immunotherapy strategies.
Area of Science:
- Immunology
- Oncology
- Molecular Biology
Background:
- Malignant ascites is a frequent complication in ovarian cancer patients.
- Natural Killer (NK) cells, crucial for antitumor immunity, are found in ascites but exhibit suppressed activity.
- The precise mechanisms behind NK cell inhibition in the ovarian cancer ascites microenvironment remain unclear.
Purpose of the Study:
- To investigate the inhibitory mechanisms of ovarian cancer ascites on NK cell antitumor activity.
- To identify specific factors within ascites responsible for NK cell dysfunction.
- To elucidate the molecular pathways affected by ascites in NK cells.
Main Methods:
- NK cell activation assays using Fcγ receptor-mediated stimulation.
- Purification of NK cells from ovarian cancer patient ascites.
- Transcriptional analysis via RNA sequencing of NK cells.
- In vitro treatment of NK cells with ascites and CA125-enriched fractions.
Main Results:
- Ovarian cancer ascites significantly inhibits NK cell activation.
- CA125, a fragment of mucin 16, contributes to the inhibitory activity of ascites.
- RNA sequencing revealed downregulated genes related to cytotoxicity and signaling, and upregulated metabolic pathway genes in NK cells from ascites.
- In vitro exposure to ascites or CA125 downregulated cytotoxicity-related gene expression in healthy donor NK cells.
Conclusions:
- Ovarian cancer ascites and CA125 suppress NK cell antitumor functions at the transcriptional level.
- The findings highlight the role of gene expression changes in NK cell inhibition within the ascites microenvironment.
- This research provides insights into potential therapeutic strategies for reactivating NK cells in ovarian cancer immunotherapy.
