Biology subjects

Sanidas, I.

Publications and source records attributed to Sanidas, I..

3 recordsLinked to original sources

bioRxiv2026

A SIRT5-induced metabolic switch underlies chemoresistance and ATR checkpoint dependence in triple-negative breast cancer

Chemoresistance is the leading cause of poor prognosis in triple-negative breast cancer (TNBC), yet the underlying mechanisms remain unknown. To reveal metabolic drivers of de novo chemoresistance in TNBC, we analyzed pretreatment primary tumor biopsies, employing quantitative proteomics and metabolomics. Chemoresistant TNBCs exhibit hallmarks of oxidative phosphorylation (OXPHOS) and altered nucleotide metabolism linked to overexpression of the mitochondrial sirtuin, SIRT5. Through gain- and loss-of-function studies and stable isotope tracing, we demonstrate that SIRT5 induces a coordinated metabolic switch that redirects glycolysis to the pentose phosphate pathway, thereby augmenting nucleotide pools, while enhancing glutaminolysis to support OXPHOS. Mechanistically, SIRT5 enhances conversion of 6-phospho-D-gluconate to ribulose-5-phosphate through demalonylation of 6-phosphogluconate dehydrogenase (6-PGD), and coordinately activates oncogenic c-MYC to promote glutamine utilization and dependence. Concurrently, SIRT5-induced nucleotide deregulation induces replication stress and hypersensitivity to ATR checkpoint activation, and ATR inhibition synergistically reverses chemoresistance in TNBC. Thus, elevated SIRT5 orchestrates a coordinated metabolic switch to expand nucleotide pools and drive chemoresistance, while producing ATR checkpoint dependence that represents a metabolic vulnerability of SIRT5-overexpressing TNBC. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=182 HEIGHT=200 SRC="FIGDIR/small/716852v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@1c7a27corg.highwire.dtl.DTLVardef@17cb22borg.highwire.dtl.DTLVardef@1956670org.highwire.dtl.DTLVardef@1786dee_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2026

Identification and inhibition of the Cyclin D Rb-docking interface that drives cell division

The animal cell division cycle is initiated by the cyclin-dependent kinases CDK4 and CDK6 in complex with D-type cyclins. Cyclin D-CDK4/6 complex formation is promoted by the assembly factors p21 and p27, which bind both subunits. p27 binds the hydrophobic patch on cyclin D that is similar to the patch used by other cell cycle cyclins to dock their substrates. This raised the question as to how cyclin D could find its substrates if its hydrophobic patch were already occupied? Here, we show that D-type cyclins use their A2 helix to dock the retinoblastoma protein Rb, a key substrate regulating cell cycle progression. The specific interface of cyclin Ds A2 helix is unique among cyclins and its mutation slows proliferation. Taken together, our work identifies a cyclin D-substrate docking mechanism that can be targeted by novel cancer therapeutics.

biochemistry↗

bioRxiv2025

Cell size-dependent mRNA transcription drives proteome remodeling

Increasing cell size drives proteomic changes that impact cell physiology. However, the molecular basis of size-dependent proteome remodeling has remained unclear. Here, we develop an inducible Cyclin D1 expression system in human cells to generate populations of proliferating cells spanning over a two-fold size range. We use this genetic system to make comprehensive genome-wide measurements of mRNA and protein concentrations and stability. We find that protein and mRNA turnover rates are weakly related to cell size, but that mRNA concentrations are strongly size-dependent. This establishes that transcriptional regulation is the basis of proteome remodeling. Live-cell imaging of endogenous mRNAs using MS2 fluorescent protein binding motifs is used to measure how transcriptional dynamics change with cell size. Larger cells prolong transcriptional bursts and shorten inactive periods between bursts but maintain similar burst amplitudes to achieve transcriptional scaling. Taken together, our results show how transcription is modulated by cell size to remodel the proteome and alter cell physiology.

cell biology↗