A Soluble Fibroblast Growth Factor Receptor is Released from HL-60 Promyelocytic Leukemia Cells: Implications for Paracrine Growth Control
Bibliographic record
Abstract
The biological activities of fibroblast growth factors (FGF) are mediated by specific cell membrane receptors (FGFR), which have three immunoglobulin-like IgG domains in the extracellular region. The carboxy-terminal segment of the third IgG domain of FGFR1 could be encoded by different exons, designated IIIa, IIIb, or IIIc. While exons IIIb or IIIc encode receptor forms with both intracellular and extracellular domains, the FGF receptor becomes potentially a secreted form lacking the intracellular domain and the transmembrane region when exon IIIa is expressed. Using reverse transcription polymerase chain reaction, we have found that mRNAs encoding the nucleotide sequences of FGFR1-IIIa and FGFR1-IIIc are expressed in HL-60 cells. FGFR1-IIIa fragment was synthesized by a glutathione S-transferase gene fusion system. The purified 33 kDa FGFR1-IIIa fragment fusion protein could bind [125I]-labelled FGF-2 in Western ligand blot analysis. Three species of proteins with the molecular weights of 82, 60, and 50 kDa were identified in serum-free, conditioned medium from HL-60 cells by Western blot using an antiserum against purified FGFR1-IIIa fragment fusion protein. Exposure to FGF-2 caused an increase in [3H]-thymidine incorporation into DNA of HL-60 cells and increased cell proliferation, but the addition of FGFR1-IIIa fragment fusion protein inhibited FGF-2-stimulated DNA synthesis and caused a dose-dependent inhibition of FGF-2-stimulated cell proliferation. The effects on DNA synthesis were partly reversed by antibody against the FGFR1-IIIa fragment. These results indicate that both cell membrane spanning and secreted FGF receptors are expressed in HL-60 cells, and that the actions of FGFs as paracrine growth factors could be modulated by secreted FGF receptor forms.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 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".