Pre-clinical rationale for combination PI3K and BRD4 inhibition in advanced prostate cancer.
Bibliographic record
Abstract
234 Background: The PI3K/Akt pathway is frequently activated in aggressive and resistant prostate cancer. Here we detail our pre-clinical evaluation of AZD8186, a novel β and δ selective PI3K small molecule inhibitor. Further, we investigate how increased transcription of the myc oncogene may represent a mechanism of resistance to monotherapy PI3K/Akt inhibition. Therefore, we further evaluated co-targeting strategies against both the PI3K/Akt pathway and the epigenetic reader protein BRD4. Methods: Human prostate cancer cell lines LNCaP and 22RV1 were tested for sensitivity to AZD8186 in vitro. Caspase-3 activity and flow cytometry were used to assess apoptosis. Western blotting and RT-qPCR were used to measure AR and myc pathway genes and protein expression. Castrate resistant LNCaP xenografts were treated with 10mg/kg and 25mg/kg doses of AZD8186 given orally 4 days on, 3 off. Results: In vitro results demonstrated sensitivity to AZD8186 with decreases in cell proliferation and increases in apoptosis. In vivo results demonstrated a dose-dependent decrease in tumor growth velocity with AZD8186 with on-target decreases in pAkt was observed in xenograft tumour samples. Further, increases in myc protein and mRNA levels were seen in xenograft samples treated with AZD8186 compared to control. Downstream increases in EGFR and IGF-IR mRNA transcripts induced by AZD8186 were also seen in vitro and in vivo. Increases in myc, EGFR and IGF-IR was also seen in cells and tumours treated with an Akt inhibitor. Addition of the BDR4 inhibitor JQ1 decreased the increase of myc induced by AZD8186 and also partially abrogated the increases in EGFR, IGFR. Greater suppression of PSA expression was seen with the combination of AZD8186 and JQ1 compared to AZD8186 and enzalutamide. Similar results were seen in the 22RV1 cell line. Conclusions: Inhibition of PI3K with AZD8186 inhibits growth of PTEN-negative LNCaP cells. However, feedback activation of myc and AR pathways occurs. We demonstrate BRD4 inhibition using JQ1 which co-targets both myc and AR feedback pathways as a rationale combination strategy with PI3K inhibition. This strategy warrants further investigation in prostate cancers with an activated PI3K/Akt pathway.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.003 |
| Insufficient payload (model declined to judge) | 0.008 | 0.002 |
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".