Characterization of Bortezomib (Velcade ™) Resistance in a New Set of Human Cell Lines Obtained by Stepwise Selection.
Bibliographic record
Abstract
Abstract Abstract 2741 Poster Board II-717 Bortezomib (Velcade ™, PS-341, BTZ) is a boronate dipeptide that reversibly inhibits the 26S proteasome, which is essential for the breakdown of ubiquitinated proteins and the regulation of normal cellular homeostasis. The activity of BTZ in treatment of newly diagnosed and refractory/relapsed multiple myeloma may be limited by the development of chemoresistance, the mechanisms of which are poorly understood. To investigate the molecular basis of Bortezomib resistance, BTZ-resistant (BTZr) cell lines were generated by stepwise selection procedures from HeLa, CCRF-CEM, and 4 multiple myeloma cells lines (8226S, U266, H929, and MM.1S), respectively. These BTZ-selected cell lines displayed varying degrees of elevated resistance (2 to 50 fold) to clinically relevant concentrations of BTZ. In addition, while most of the BTZr cells showed cross resistance to several other proteasome inhibitors (PIs), including MG-132 and Epoxomicin, they remained as sensitive to other chemotherapeutic drugs, such as anthracyclines, vinkalkaloids and etoposide, as their parental cells. The proteasome activity profiles are distinct among the cell lines. All parental cell lines displayed varying levels of chymotrypsin-like (CT-L) activity, which is the primary target of BTZ. Most BTZr lines showed markedly decreased CT-L activity, with a few exceptions. Moreover, the observed CT-L activity in all cell lines can be inhibited directly by BTZ and other PIs. In contrast, very low levels of caspase-like or post-glutamyl peptide hydrolyzing (PGPH) proteasome activity were detected in all cell lines. BTZ resistance in HeLa/BTZ cells was closely associated with increased resistance to PI-induced apoptosis, as shown by reduced number of Annexin V-stained cells and by delayed activation/cleavage of apoptosis proteins, such as Caspase-3 and Poly(ADP-ribose) Polymerase (PARP). Furthermore, the resistance to BTZ affected the mechanisms of cell stress responses. As for the parental HeLa cells, HeLa/BTZr cells retained the ability to form, in response to PI treatment, pro-survival foci in the cytoplasm known as stress granules (SGs). However, the drug concentrations required to induce SG formation in HeLa/BTZr cells are much higher (∼4 fold) than those for the parental HeLa, suggesting the development of stress-coping mechanisms in these BTZr cells. Gene expression profiling studies are in progress to identify transcriptomes individually or generally associated with BTZ resistance in these cell lines. Further characterization of these phenotypically similar, yet mechanistically distinct BTZr cell lines may elucidate diverse mechanisms of drug resistance to Bortezomib and other proteasome inhibitors. Disclosures: No relevant conflicts of interest to declare.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".