PTEN (phosphatase and tensin homologue deleted on chromosome 10) gain-of-function analysis in LNCaP prostate cancer cells
Bibliographic record
Abstract
983 PTEN expression is frequently lost in advanced prostate cancer (PrCa). Mouse models with prostate specific loss of PTEN develop metastatic, androgen independent PrCa. However, ∼50% of lethal human PrCa continues to express PTEN indicating that prosurvival mechanisms are functional despite the presence of a major PI3K/Akt antagonist. In LNCaP PrCa cells, induction of apoptosis by PTEN is strongly opposed by androgens. However, androgen mediated genes that protect cells from PI3K/Akt antagonism are poorly understood. We have employed gain-of-function, stable LNCaP clones that inducibly express PTEN to assess: (1) alterations in PI3K/Akt signalling due to PTEN phosphatase activity and (2) the capacity for androgens to counteract an acute, PTEN mediated apoptotic response. Clones contained Tet-inducible expression constructs for PTEN WT or a catalytic mutant (C124S) and a VP16-Tet activator. LNCaP-PTEN and LNCaP-C124S cell stables were also made by lenti viral delivery of pLenti6/Tet repressor (TR) and a pDEST/TO/Lenti vector (Invitrogen). In charcoal-stripped serum (CSS) conditions, Doxycyclin (Dox; 2 ug/ml) efficiently induced WT PTEN and C124S PTEN expression, however, only WT PTEN effectively antagonized P-AktSer473/Thr308 and activated PARP cleavage. In CSS plus 1 nM R1881, WT PTEN diminished P-Akt, but did not activate PARP. Proliferation of LNCaP-WT PTEN cells cultured in CSS/Dox/1 nM R1881 for 7 days was 85% of growth in full serum conditions while growth of cells cultured in CSS/dox was 45% of control cultures. Soft agar assays confirmed that PTEN expressing LNCaP cells were tumourigenic in the presence of androgen. Nude mice harbouring subcutaneous LNCaP-PTEN/Matrigel xenografts with serum PSA levels of >50 ng/ml were administered Dox in drinking water ad libitum for 7 days. IHC analysis indicated PTEN expression in up to ∼70% of xenograft epithelium. Cells with high PTEN expression were also observed to have lower androgen receptor (AR) expression, suggesting an antagonistic interaction between androgens and PTEN. Gene expression was evaluated using an oligo microarray (14,000 spotted 70-mers) and Cy3 or Cy5 labelled cDNA generated from Dox treated (48 hours; 2 ug/ml) LNCaP-PTEN and LNCaP-C124S cells. Using GeneSpring 6.1 software our analysis considered: (1) the presence of serum; (2) the PTEN phosphatase function and (3) the presence of androgens. In addition to antagonizing PI3K, WT PTEN (but not C124S) induced apoptotic markers and decreased metabolic markers. Identification and characterization of genes associated with androgen mediated protection of PTEN expressing cells are presented and suggest how: (1) Stable, inducible integration has allowed evaluation of prolonged expression of PTEN expression in AR, PSA secreting PrCa cells and (2) how androgens prevent apoptosis and permit cell proliferation in the presence of PTEN for at least 7 days.
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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 | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".