O'Leary, J. | bioRxiv Science

bioRxiv2024

A comparative study of circulating tumor cell isolation and enumeration technologies in lung cancer

Circulating tumor cells (CTCs) have potential as diagnostic, prognostic and predictive biomarkers in solid tumors. Despite FDA approval of CTC devices in various cancers, their rarity and limited comparison between analysis methods hinder their clinical integration for lung cancer. This study aimed to evaluate five CTC isolation technologies using a standardized spike-in protocol: the CellMag (EpCAM-based enrichment), EasySep and RosetteSep (blood cell depletion), and the Parsortix(R) PR1 and next generation Parsortix(R) Plus (PX+) (size-based enrichment). The Parsortix(R) systems were also evaluated for any difference in recovery rates between cell harvest versus in- cassette staining. Healthy donor blood (5 mL) was spiked with 100 fluorescently labeled H1975 lung adenocarcinoma cell line, processed through each system and the isolation efficiency was calculated. All tested systems yielded discordant recovery rates with the CellMag having the highest mean recovery (70 {+/-} 14%) followed by the PR1 (in-cassette staining) with a recovery of 49 {+/-} 2% while the EasySep had the lowest recovery (18 {+/-} 8%). The CellMag and Parsortix(R) PR1 may have potential clinical applications for lung cancer patients, albeit needing further optimization and validation.

cancer biology↗

bioRxiv2023

Adaptive Expression of Engrams by Retroactive Interference

Long-term memories are stored as stable configurations of neuronal ensembles, termed engrams. While investigation of engram cell properties and functionality in memory recall has been extensive, less is known about how engram cells are affected by forgetting. We describe a form of interference-based forgetting using an object memory behavioral paradigm. By using activity-dependent cell labelling, we show that although retroactive interference results in decreased engram cell reactivation during recall trials, optogenetic stimulation of the labelled engram cells is sufficient to induce memory retrieval. Forgotten engrams may also be reinstated via the presentation of similar or related environmental information. Furthermore, we demonstrate that engram activity is necessary for interference to occur. Taken together, these findings indicate that retroactive interference modulates engram expression in a manner that is both reversible and updatable. Retroactive inference may constitute a form of adaptive forgetting, where in everyday life new perceptual and environmental inputs modulate the natural forgetting process.

neuroscience↗