ARNT/HIF-1β: An AML Biomarker?
Bibliographic record
Abstract
Abstract Abstract 2903 Background: Despite improvements in chemotherapy protocols and bone marrow transplantation techniques, AML remains a lethal disease. Although patients with AML typically respond well to initial therapy, the majority relapse and eventually succumb to the disease. This relapse is thought to be the result of the resistance of leukaemic stem cells to the effects of chemotherapy. Some mechanisms have been discovered which contribute to resistance, but this phenomenon remains incompletely understood and is a significant barrier to improving patient outcomes. TEL is a member of the ETS transcription factor gene family and is essential for developmental processes such as haematopoiesis. TEL is frequently targeted by chromosomal translocations in human malignancies, resulting in the expression of oncogenic TEL gene fusions. A TEL-ARNT gene fusion was reported in a single case of AML, FAB subtype M2, in a patient whose leukaemic cells contained the balanced translocation t(1;12)(q21;p13). ARNT (also known as HIF-1β) is a nuclear protein and functions as part of a heterodimer, whose partners include HIF-1α and the aryl hydrocarbon receptor (AhR). HIF-1 expression is commonly deregulated in cancer and AhR signalling has been linked to leukaemogenesis. Materials and Results: Immunoblot analysis of patient bone marrow mononuclear cell lysates revealed that 5 of 29 AML specimens (∼17%) had elevated levels of ARNT protein, whereas 0 of 19 MDS specimens showed ARNT expression. In addition, AML specimens that had elevated ARNT protein levels also had elevated levels of phosphorylated Akt, while AML specimens that did not have elevated ARNT protein expression did not have activation of Akt signaling. Intriguingly, ARNT expression was noted in one patient who had progressed from MDS to AML. We then studied the expression of ARNT in HL60 cells, which are highly sensitive to induction of apoptosis by troglitazone (TG), and in U937 cells, which are TG resistant. In HL60 cells, ARNT mRNA levels remained constant following TG treatment and ARNT protein levels markedly decreased, while in U937 cells, ARNT mRNA levels increased and ARNT protein levels remained constant. We then tested the effect of exogenous expression of ARNT on the sensitivity of HL-60 cells to apoptosis induced by TG, daunorubin and hydrogen peroxide. HL-60 cells transduced with a retrovirus expressing ARNT became resistant to the induction of apoptosis by all these agents. These cells also had constitutive activation of Akt signaling, and treatment of these cells with a specific inhibitor of Akt signaling reversed their resistance to TG-induced apoptosis. Conclusions: The expression of ARNT confers resistance to apoptosis in AML cell lines and activates Akt signalling. In addition, ARNT is overexpressed in a significant subset of AML patients, in whom it activated Akt signaling, and ARNT expression correlates with progression of MDS to AML. ARNT may play an important role in chemoresistance and may be useful as a predictive or prognostic biomarker. Disclosures: No relevant conflicts of interest to declare.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".