Abstract P3-05-15: Divergent activation of AKT1 and AKT2 isoforms downstream of PI3K mutation impacts response of breast cancer cells to estradiol and PI3K inhibitors
Bibliographic record
Abstract
Abstract Background: PI3K mutations are observed in 30% of breast cancers, which are more common in estrogen receptor (ERα) positive breast cancers compared to ERα-negative breast cancers. AKT, a the major kinase downstream of PI3K, modulates ERα activity. It is unknown whether PI3K mutation leads to preferential activation of specific AKT isoform with ability to modulate ERα function. Results: We report elevated AKT1 but not AKT2 mRNA in breast cancers with PI3K mutation. Breast epithelial cells with targeted substitution of PI3K with PI3K-E545K or PI3K-H1047R demonstrated elevated AKT1_pS473 compared to AKT2_pS474, distinct AKT substrate phosphorylation, and enhanced Estrogen Receptor (ERα) activity. AKT1 had a dominant role in ERα:estradiol (E2)-dependent gene expression and proliferation. We have identified an unique gene expression signature in ERα-positive breast cancers that is dependent on ERα, estradiol (E2), AKT1, and the pioneer factor FOXA1. Elevated expression of this signature in ERα-positive tumor was associated with better response to endocrine therapy and outcome. In addition, AKT1 determined the sensitivity to PI3α-specific inhibitor BYL719 and pan-PI3K inhibitor BKM120. In contrast, AKT2 controlled global gene expression and elevated levels of an AKT2-directed protein signature predicted poor outcome in breast cancer patients. Conclusions: PI3K mutation favors AKT1 activation leading to imbalance in AKT isoform-specific kinome/proteome and an effect on specific signaling pathways, particularly ERα:E2 signaling network. Knowledge gained from this functional dissection of AKT isoform activity downstream of PI3K mutation can be exploited for therapeutic stratification, particularly for anti-estrogen and PI3K inhibitor-based therapies. Citation Format: Harikrishna Nakshatri, Chirayu Goswami, Sunil Badve, Luca Magnani, Mathieu Lupien, Poornima Bhat-Nakshatri. Divergent activation of AKT1 and AKT2 isoforms downstream of PI3K mutation impacts response of breast cancer cells to estradiol and PI3K inhibitors [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-05-15.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".