Abstract 4736: Bone marrow microenvironment-induced miR-300 expression impairs natural killer cell proliferation and antitumor activity
Bibliographic record
Abstract
Abstract Natural killer (NK) cells mediate immune responses against cancer; however, NK cell quantitative and functional defects are features of cancers including chronic myelogenous leukemia (CML). As increased numbers of activated NK cells were found in CML patients in treatment-free remission, the understanding of the molecular events inhibiting NK proliferation and function may lead to the development of NK cell-based therapies against drug-resistant cancer stem cells. Because altered miRNA expression and inactivation of the protein phosphatase 2A (PP2A) tumor suppressor are also features of cancer, and SET-dependent PP2A inhibition is essential for NK cell function, we hypothesized that increased expression of miR-300, a miRNA with antiproliferative activity, found inhibited in CML and targeting the PP2A inhibitor SET, accounts for impaired NK cell proliferation/activity. An initial analysis revealed that miR-300 levels were significantly higher in peripheral blood (PB) CD56+CD3- NK cells from CML patients at diagnosis compared to healthy individuals. As NK cell activity is regulated by the bone marrow microenvironment (BMM), we evaluated whether hypoxic conditions and/or cell-to-cell interaction influence NK cell proliferation and cytotoxic activity by modulating miR-300 intracellular levels. A marked and significant increase in miR-300 expression was detected in NK-92 and primary CD56+CD3- NK cells exposed to low O2 levels or cultured in the presence of conditioned medium (CM) or exosomes isolated from BM-derived primary mesenchymal stromal (MSC) and HS-5 MSC cells. As expected, increased miR-300 levels correlated with decreased SET levels and markedly reduced NK cell number. Interestingly, miR-300-induced growth inhibition was rescued in NK cells treated with CM/exosomes from HS-5 cells expressing an anti-miR-300 lentivirus. Notably, qRT-PCR indicated that miR-300 was contained in MSC exosomes. Functionally, exposure to MSCs (CM or exosomes) inhibited NK cell IL-12/IL-18-induced IFN-γ production and cytotoxic activity against K562 CML-BC cells in a miR-300-dependent manner. Accordingly, miR-300 lentiviruses and/or CpG-miR-300 oligonucleotides inhibited SET expression, reduced proliferation and suppressed spontaneous cytotoxicity of NK-92 and/or primary NK cells, likely through reactivation of PP2A. Because BM hypoxic conditions and MSCs significantly contribute to decreased NK cell number and cytotoxic activity through upregulation of miR-300, its genetic or pharmacologic inhibition may result in reactivation of NK cell activity against leukemic stem/progenitor cells. This work is supported in part by NIH-NCI RO1CA163800. Citation Format: Rossana Trotta, Giovannino Silvestri, Lorenzo Stramucci, Martin Guimond, Guido Marcucci, Xiaoxuan Fan, Maria R. Baer, Danilo Perrotti. Bone marrow microenvironment-induced miR-300 expression impairs natural killer cell proliferation and antitumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4736.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".