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Principal Investigator: Brianna Fernandez
Organization: UNIVERSITY OF COLORADO
Fiscal Year: 2024
Award: $40,782
Funding agency: National Cancer Institute
PROJECT SUMMARY
Cell-cycle exit can be either transient (quiescence) or permanent (senescence), and these different states
are thought to have distinct molecular characteristics. Further, quiescence itself is not a single homogeneous
state as cells that remain quiescent for longer durations of time move progressively “deeper” into quiescence,
taking longer to return to the cell cycle upon stimulation. While senescent cancer cells are tumor suppressive as
they limit the proliferation of damaged cells and recruit the immune system, quiescent cancer cells are a source
of drug resistance as they evade chemotherapeutic treatments targeted at cycling cells and retain their ability to
proliferate in the future. The mechanisms controlling quiescence depth and the relationship between deep
quiescence and senescence are still poorly understood due to the lack of robust biomarkers and necessity for
single-cell assays to study questions of reversibility. However, there is a critical need for such studies as
chemotherapeutic treatment results in a mix of these cell fates. By using a functional readout that gets at the
core of what it means to be senescent: the long-term total lack of cell-cycle entry or progression, we found that
a subset of cells pushed into deep quiescence fail to return to the cell cycle after release from treatment and that
cells induced to deep quiescence by four different treatments for 2-12 days showed increasing levels of SA-βgal,
the gold standard marker of senescence. Thus, we hypothesize that 1) senescence is a deep quiescence from
which cells will never reawaken and 2) the transition between deep quiescence and senescence is marked by a
decrease in the ratio between pro-proliferative signaling (Cyclin D) and anti-proliferative signaling (p21/p27),
mediating the progressive decrease in probability of cell-cycle re-entry. Experiments proposed in Aim 1 will use
time-lapse microscopy paired with post-hoc immunofluorescence imaging to measure canonical markers of
senescence in cells that remain permanently arrested after release from deep quiescence. In Aim 2 we will
perform RNA-sequencing on the subset of permanently arrested cells from Aim 1 and compare the
transcriptomes to existing gene signatures for senescent cells. Finally, we will use time-lapse microscopy of
biosensors for Cyclin D and p21/p27 to determine if the ratio of these signals predicts future cell-cycle re-entry.
Collectively, these aims will help define the relationship between quiescence and senescence and contribute to
a much needed quantitative and mechanistic understanding of how cells transition between transient, prolonged,
and permanent cell-cycle withdrawal. If successful, the proposed work will aid in the development of more
targeted and effective chemotherapy treatments and provide more accurate biomarkers to determine which cells
will and will not proliferate in the future.
Terms: <Address><Aging><Assay><Automobile Driving><Bioassay><Biological Assay><Biological Markers><Biosensor><CCND1 Protein><CRISPR><CRISPR/Cas system><Cancers><Cell Body><Cell Communication and Signaling><Cell Cycle><Cell Division Cycle><Cell Signaling><Cells><Cellular Assay><Cellular injury><Characteristics><Chemotherapy Protocol><Chemotherapy Regimen><Chemotherapy-Oncologic Procedure><Clustered Regularly Interspaced Short Palindromic Repeats><Combination Chemotherapy Regimen><Cyclin D1><Data><Development><Diagnosis><Disease><Disorder><Drug resistance><Equilibrium><Flow Cytofluorometries><Flow Cytofluorometry><Flow Cytometry><Flow Microfluorimetry><Flow Microfluorometry><Future><G1/S-Specific Cyclin D1><Image><Immune system><Immunofluorescence><Immunofluorescence Immunologic><Inflammatory><Intracellular Communication and Signaling><Knowledge><Malignant Cell><Malignant Neoplasms><Malignant Tumor><Measures><Mediating><Methods><Microscopy><Molecular><Outcome><PRAD1 Protein><Phenotype><Population><Probability><Proliferating><Proteins><Proto-Oncogene Proteins c-bcl-1><Publishing><Quimioterapia><RNA Seq><RNA sequencing><RNAseq><Reporter><Research><Side><Signal Transduction><Signal Transduction Systems><Signaling><Source><Staining method><Stains><Stress><Testing><Therapeutic><Time><Treatment Efficacy><Tumor Cell><Tumor Suppressor Proteins><Withdrawal><Work><acute stress><balance><balance function><bcl-1 Proto-Oncogene Products><bcl-1 Proto-Oncogene Proteins><bcl1 Proto-Oncogene Proteins><bio-markers><biologic marker><biological sensor><biological signal transduction><biomarker><c-bcl-1 Proteins><cancer cell><cancer chemotherapy><cell assay><cell damage><cell injury><cellular damage><chemotherapy><cyclin D><damage to cells><developmental><driving><drug resistant><experiment><experimental research><experimental study><experiments><flow cytophotometry><gene signatures><genetic signature><global gene expression><global transcription profile><imaging><injury to cells><intervention efficacy><knock-down><knockdown><malignancy><neoplasm/cancer><neoplastic cell><overexpress><overexpression><recruit><resistance to Drug><resistant to Drug><senescence><senescent><senescent cell><sensor><therapeutic efficacy><therapy efficacy><transcriptome><transcriptome sequencing><transcriptomic sequencing><tumor suppressor>