Characterization of genetically modified human embryonic kidney 293 cells lacking equilibrative nucleoside transporter subtype 2, or both subtypes 1 and 2, and the impact of their loss on sensitivity to chemotherapeutic purine/pyrimidine analogs
Bibliographic record
Abstract
Equilibrative nucleoside transporters (ENTs) 1 and 2 are considered critical to the cellular uptake of purine and pyrimidine analogs used to treat cancer and viral infections. However, a detailed understanding of the discrete and overlapping roles of these ENT subtypes in drug activity remains limited. A significant barrier to progress has been the absence of model systems that enable functional characterization of individual nucleoside transporters in the context of their native environment. To address this, we developed and characterized a panel of CRISPR/cas9-engineered human embryonic kidney 293 cell lines with selective deletion of ENT subtypes: ENT1 knockout, ENT2 knockout, and dual knockout. These models were used to dissect subtype-specific roles of ENT1 and ENT2 in nucleoside/nucleobase analog uptake and cytotoxicity. Our data show that ENT1 and ENT2 in their endogenous environment have a similar affinity for a range of both endogenous and chemotherapeutic nucleoside and nucleobase analogs. Deletion of ENT1 generally enhanced the sensitivity of cells to these drugs, particularly the nucleobase analogs, likely due to reduced nucleoside salvage by the cells via ENT1. Deletion of ENT2, on the other hand, dramatically reduced the ability of a number of the tested drugs to impact cell viability, by mechanisms beyond those related to reduced cellular uptake of the drugs. This study highlights distinctive roles of ENT1 and ENT2 in the actions of nucleoside/nucleobase analog drugs. SIGNIFICANCE STATEMENT: A panel of genetically modified human embryonic kidney 293 cells has been created as a model to screen novel nucleoside transporter inhibitors and substrates. Using these cell lines, it was revealed that ENT2 may play a more functionally significant role in nucleoside analog chemotherapeutic drug activity than previously appreciated.
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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".