Mechanisms of 1,25-dihydroxyvitamin D resistance in tumor cells as they progress from the normal to the malignant phenotype
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Human retinoid X receptor alpha (hRXRalpha) plays a critical role in DNA binding and transcriptional activity through its heterodimeric association with several members of the nuclear receptor superfamily, including the vitamin D receptor (VDR). Several cancer cell lines derived from many tissues have been shown to be resistant to the growth inhibitory action of 1,25-dihydroxyvitamin D3, (1,25(OH)2D3), the biologically active metabolite of vitamin D3. In the malignant ras-transformed human keratinocyte cell line, HPK1Aras, 10--100 fold higher concentrations of 1,25(OH)2D3 are required than the non-malignant normal human epidermal keratinocytes to achieve comparable inhibition of cell growth. Here we show that in ras-transformed keratinocytes, ser260 of hRXRalpha is phosphorylated through the Ras-Raf-MAP kinase cascade. This phosphorylation event results in the inhibition of vitamin D signaling via VDR/hRXRalpha heterodimers. Strategies to reverse this resistance include the use of the MAP kinase inhibitor, PD098059, and a non-phosphorylatable hRXRalpha mutant, ala260, which completely abolishes RXR phosphorylation and restores the function of both 1,25(OH)2D3 and a specific RXR ligand, LG1069 (4-[1-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethyl-2-naphtalenyl)ethenyl]-benzoic acid). In addition, we show that a vitamin D analog with low calcemic activity (EB1089) is more potent than 1,25(OH)2D3 in inhibiting cancer cell growth in this system. Targeted therapy with selective analogs such as EB1089, in combination with the inhibition of phosphorylation of the RXR, could play a critical role in the therapeutic strategies of cancer biology. In addition, we also demonstrate that resistance to 1,25(OH)2D 3 can be acquired through genetic alterations in the VDR, implying that both components of the VDR/RXR heterodimer are potential targets for the induction of cellular resistance to 1,25(OH)2D3 and present two distinct mechanisms through which tumour cells can escape the growt
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.002 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 it