Calpain-1 and Calpain-2 Promote Breast Cancer Metastasis
Bibliographic record
Abstract
In breast cancer, progression from localized stage I to distant metastatic stage IV disease is associated with a reduction of 5-year survival from nearly 100% to 23.2%. Expression of the calcium-activated protease isoforms calpain-1 and calpain-2 has been correlated with cell migration and invasion in vitro, metastatic potential in preclinical mouse models of cancer, and breast cancer prognosis in patients. It is unclear which of these two calpain isoforms is responsible for the apparent metastatic potential of cancer cells. Here, we demonstrate that while individual CRISPR-Cas9 knockouts of either CAPN1 or CAPN2 genes (encoding the catalytic subunits of calpain-1 and -2, respectively) reduce in vitro migration and marginally suppress in vivo metastasis, genetic disruption of both calpain-1 and calpain-2 through knockout of the CAPNS1 gene (encoding the common regulatory subunit of calpain-1 and -2) diminishes metastasis by 83.4 ± 13.6% in a mouse xenograft model of human triple-negative breast cancer. The effect of calpain-1/2 deficiency was replicated in vitro with a modified cell-permeable calpastatin (CAST)-based peptide inhibitor (cell migration reduced to 53.5 ± 11.0% of vehicle control). However, this peptide inhibitor was not effective in vivo at reducing metastasis under the conditions used (vehicle vs. CAST, 1.12 ± 1.35 lung metastases per mm2 vs. 0.34 ± 0.20 metastases per mm2), likely due to rapid clearance, as indicated by the short serum half-life. This work demonstrates that calpain-1/2 disruption effectively abrogates metastasis and provides rationale for development of effective calpain inhibitors.
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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) | 0.000 | 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".