Abstract 4844: A novel mechanism of immune escape in cancer and its regulation by nitric oxide
Bibliographic record
Abstract
Abstract One key to malignant progression is the acquired ability of tumor cells to escape immune-mediated lysis. Whereas tumor hypoxia is known to play a causal role in cancer metastasis and resistance to therapy, the link between hypoxia and immune escape in cancer remains poorly understood. Previously, we showed that hypoxia induces resistance to natural killer (NK) cell-mediated lysis in tumour cells through a mechanism that involves the shedding of the NK cell-activating ligand, MHC Class I Chain Related molecule A (MICA), from the cell surface. Additionally, we reported that activation of NO signalling in the tumour cells was able to block this hypoxia-induced shedding of MICA, as well as resistance to NK-mediated lysis. Here, we show that hypoxia-induced tumor resistance to lysis is mediated by a HIF-1-dependent increased expression of the metalloproteinase ADAM10, which is required for the hypoxia-induced shedding of MICA. Our findings demonstrate that HIF-1α knock down attenuated the hypoxia-induced expression of ADAM10 and MICA in tumour cells. Also, siRNA-mediated knockdown of HIF-1α or ADAM10 prevented the hypoxia-induced resistance of DU145 cells to innate immune effector cell-mediated lysis. Treatment with nitric oxide mimetic agents interfered with the hypoxia-induced accumulation of HIF-1α, and with the hypoxia-induced up-regulation of ADAM10 expression required for decreased surface MICA expression and resistance to lysis. To validate the in vitro results, we adopted a model in which human DU145 cells were injected subcutaneously into Swiss nude mice (T and B cell-deficient). Continuous transdermal delivery of nitroglycerine (1.8 µg/h for up to 62 days) significantly attenuated attenuated the tumor growth (P < 0.05). This tumor growth-inhibitory effect of nitroglycerine was absent in mice depleted of innate immune effector cells. Within the tumours, areas of hypoxia co-localized with the metalloproteinase ADAM10 expression. Our results demonstrate a novel mechanism by which hypoxia contributes to immune escape in tumor cells and provide evidence that activation of nitric oxide signalling interferes with this mechanism. The findings described here are important because they indicate that nitric oxide mimetics could potentially be used as immunosensitizers in the treatment and/or prevention of cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4844. doi:1538-7445.AM2012-4844
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".