Dexamethasone‐enhanced sodium absorption in the human mammary epithelial cell line, MCF‐7
Bibliographic record
Abstract
The mechanisms underlying fluid and electrolyte transport in mammary epithelial cells are not fully understood, despite their importance in the physiology of lactation and breast cyst formation. Using the human mammary epithelial cell line MCF‐7, we investigated the physiologic and molecular consequences of dexamethasone (DEX) treatment. Application of DEX (1μM, 24 hrs) induced a small, amiloride‐sensitive, short circuit current in MCF‐7 cells, absent from untreated cells, reflecting the development of an active transepithelial Na+ absorptive pathway. Using quantitative PCR to examine the molecular changes responsible for this current, we found a statistically significant increase in the expression of the β and γ (but not α) subunits of the epithelial sodium channel, ENaC. Immunocytochemistry performed on polarized monolayers localized ENaC protein and the Na+‐K+‐ATPase to the apical and basolateral membrane respectively. We postulated that the increased Na+ absorption seen following DEX treatment was due to increased trafficking of ENaC protein to the apical membrane. However, cell surface biotinylation assays and immunofluorescence experiments indicate there is no apparent increase in the amount of ENaC protein at the apical surface of MCF‐7 cells following DEX treatment. Finally, DEX treatment also significantly increased the expression of the serum glucocorticoid kinase, SGK1, raising the possibility that SGK‐1‐mediated effects lead to the increased Na+ absorption seen with DEX. These results suggest that human mammary epithelial cells are capable of Na+ absorption that is under hormonal control. Supported by the CBCF.
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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 | 0.000 |
| 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".