Biology subjects

Colla, S.

Publications and source records attributed to Colla, S..

9 recordsLinked to original sources

bioRxiv2026

Aberrant oxidative metabolism selects for TET2-deficient hematopoietic stem and progenitor cells

The mechanism(s) driving selective expansion of mutant hematopoietic stem and progenitor cells (HSPC) in clonal hematopoiesis (CH) are incompletely understood. Here, we address the role of metabolism in selection for HSPC with loss of function mutations in TET2. Loss of Tet2 in murine HSPC triggers overexpression of glycolysis and oxidative phosphorylation genes and increased oxidative metabolism via an enlarged mitochondrial network. However, Tet2-deficient HSPC maintain a normal redox state. Strikingly, compound loss of the rate-limiting pentose phosphate pathway (PPP) enzyme glucose-6-phosphate dehydrogenase (G6PD) triggers increased reactive oxygen species and impairs the fitness of Tet2-deficient HSPC. We find that aberrant oxidative metabolism is also a feature of HSPC in human CH and clonal cytopenia of unknown significance (CCUS). Overall, our data point to aberrant metabolism as a critical and conserved driver of selection in TET2-deficient CH and identify the PPP as a crucial compensatory pathway needed to maintain their selective advantage. Statement of SignificanceThis study identifies oxidative metabolism as a critical driver of selection for TET2-deficient HSPC in clonal hematopoiesis (CH). It also demonstrates that cellular redox state is a vulnerability that impairs their fitness. These insights establish targetable metabolic pathway(s) that could be exploited in the setting of TET2 mutant CH.

cancer biology↗

bioRxiv2024

A STAT3 Degrader Demonstrates Pre-clinical Efficacy in Venetoclax resistant Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that continues to have poor prognosis despite recent therapeutic advances. Venetoclax (Ven), a BCL2-inhibitor has shown a high response rate in AML; however, relapse is invariable due to mitochondrial dysregulation that includes upregulation of the antiapoptotic protein MCL1, a central mechanism of Ven resistance (Ven-res). We have previously demonstrated that the transcription factor STAT3 is upregulated in AML hematopoietic stem and progenitor cells (HSPCs) and can be effectively targeted to induce apoptosis of these aberrant cells. We now show that overexpression of STAT3 alone is sufficient to initiate a strong AML phenotype in a transgenic murine model. Phospho-proteomic data from Ven treated AML patients show a strong correlation of high total STAT3 and phospho-STAT3 [both p-STAT3(Y705) and p-STAT3(S727)] expression with worse survival and reduced remission duration. Additionally, significant upregulation of STAT3 was observed in Ven-res cell lines, in vivo models and primary patient samples. A novel and specific degrader of STAT3 demonstrated targeted reduction of total STAT3 and resulting inhibition of its active p-STAT3(Y705) and p-STAT3(S727) forms. Treatment with the STAT3 degrader induced apoptosis in parental and Ven-res AML cell lines and decreased mitochondrial depolarisation, and thereby dependency on MCL1 in Ven-res AML cell line, as observed by BH3 profiling assay. STAT3 degrader treatment also enhanced differentiation of myeloid and erythroid colonies in Ven-res peripheral blood mononuclear cells (PBMNCs). Upregulation of p-STAT3(S727) was also associated with pronounced mitochondrial structural and functional dysfunction in Ven-res cell lines, that were restored by STAT3 degradation. Treatment with a clinical-stage STAT3 degrader, KT-333 resulted in a significant reduction in STAT3 and MCL1 protein levels within two weeks of treatment in a cell derived xenograft model of Ven-res AML. Additionally, this treatment significant improvement in the survival of a Ven-res patient-derived xenograft in-vivo study. Degradation of STAT3 resulting in downregulation of MCL1 and improvements in global mitochondrial dysfunction suggests a novel mechanism of overcoming Ven-res in AML. Statement of PurposeFive-year survival from AML is dismal at 30%. Our prior research demonstrated STAT3 over-expression in AML HSPCs to be associated with inferior survival. We now explore STAT3 over-expression in Ven-res AML, explain STAT3 mediated mitochondrial perturbations and describe a novel therapeutic strategy, STAT3 degradation to overcome Ven-res.

cancer biology↗

bioRxiv2024

Clonal evolution of hematopoietic stem cells after cancer chemotherapy

Normal hematopoietic stem and progenitor cells (HSPCs) inherently accumulate somatic mutations and lose clonal diversity with age, processes implicated in the development of myeloid malignancies1. The impact of exogenous stressors, such as cancer chemotherapies, on the genomic integrity and clonal dynamics of normal HSPCs is not well defined. We conducted whole-genome sequencing on 1,032 single-cell-derived HSPC colonies from 10 patients with multiple myeloma (MM), who had undergone various chemotherapy regimens. Our findings reveal that melphalan treatment distinctly increases mutational burden with a unique mutation signature, whereas other MM chemotherapies do not significantly affect the normal mutation rate of HSPCs. Among these therapy-induced mutations were several oncogenic drivers such as TET2 and PPM1D. Phylogenetic analysis showed a clonal architecture in post-treatment HSPCs characterized by extensive convergent evolution of mutations in genes such as TP53 and PPM1D. Consequently, the clonal diversity and structure of post-treatment HSPCs mirror those observed in normal elderly individuals, suggesting an accelerated clonal aging due to chemotherapy. Furthermore, analysis of matched therapy-related myeloid neoplasm (t-MN) samples, which occurred 1-8 years later, enabled us to trace the clonal origin of t-MNs to a single HSPC clone among a group of clones with competing malignant potential, indicating the critical role of secondary mutations in dictating clonal dominance and malignant transformation. Our findings suggest that cancer chemotherapy promotes an oligoclonal architecture with multiple HSPC clones possessing competing leukemic potentials, setting the stage for the selective emergence of a singular clone that evolves into t-MNs after acquiring secondary mutations. These results underscore the importance of further systematic research to elucidate the long-term hematological consequences of cancer chemotherapy.

cancer biology↗

bioRxiv2023

IL-1B-mediated inflammatory signaling drives ineffective erythropoiesis in early-stage myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of incurable hematopoietic stem cell (HSC) neoplasms characterized by peripheral blood cytopenias and a high risk of progression to acute myeloid leukemia. MDS represent the final stage in a continuum of HSCs genetic and functional alterations and are preceded by a premalignant phase, clonal cytopenia of undetermined significance (CCUS). Dissecting the mechanisms of CCUS maintenance may uncover therapeutic targets to delay or prevent malignant transformation. Here, we demonstrate that DNMT3A and TET2 mutations, the most frequent mutations in CCUS, induce aberrant HSCs differentiation towards the myeloid lineage at the expense of erythropoiesis by upregulating IL-1{beta}-mediated inflammatory signaling and that canakinumab rescues red blood cell transfusion dependence in early-stage MDS patients with driver mutations in DNMT3A and TET2. This study illuminates the biological landscape of CCUS and offers an unprecedented opportunity for MDS intervention during its initial phase, when expected survival is prolonged.

cancer biology↗

bioRxiv2023

Hematopoietic Stem Cells Undergo Differentiation State Reprogramming to Overcome Venetoclax Sensitivity in Patients with Myelodysplastic Syndromes

While the molecular mechanisms of acute myeloid leukemia failure to venetoclax-based therapy have been recently clarified, the mechanisms whereby patients with myelodysplastic syndromes (MDS) acquire secondary resistance to venetoclax after an initial response remain to be elucidated. Here, we show for the first time that MDS hematopoietic stem cells (HSCs) can undergo hierarchical differentiation reprogramming toward a granulo-monocytic-biased transcriptional state through the acquisition or expansion of clones with an isolated trisomy 8 cytogenetic aberration and STAG2 or RUNX1 mutations. This hierarchical rewiring changes HSCs survival dependence from BCL-2-mediated anti-apoptotic pathways to TNF-induced pro-survival NF-{kappa}B signaling and overcomes venetoclax-mediated cytotoxic effect. These findings underscore the importance of close molecular monitoring of patients with MDS enrolled in clinical trials of venetoclax to prevent HSC transcriptional reprogramming before the disease becomes resistant to this therapy.

cancer biology↗

bioRxiv2023

Targeting MCL1-driven anti-apoptotic pathways to overcome hypomethylating agent resistance in RAS-mutated chronic myelomonocytic leukemia

RAS pathway mutations, which are present in 30% of patients with chronic myelomonocytic leukemia (CMML) at diagnosis, confer a high risk of resistance to and progression after hypomethylating agent (HMA) therapy, the current standard of care for the disease. Using single-cell, multi-omics technologies, we sought to dissect the biological mechanisms underlying the initiation and progression of RAS pathway-mutated CMML. We found that RAS pathway mutations induced the transcriptional reprogramming of hematopoietic stem and progenitor cells (HSPCs), which underwent proliferation and monocytic differentiation in response to cell-intrinsic and -extrinsic inflammatory signaling that also impaired immune cells functions. HSPCs expanded at disease progression and relied on the NF-KB pathway effector MCL1 to maintain their survival, which explains why patients with RAS pathway- mutated CMML do not benefit from BCL2 inhibitors such as venetoclax. Our study has implications for developing therapies to improve the survival of patients with RAS pathway- mutated CMML.

cancer biology↗

bioRxiv2023

Targeting DNA2 Overcomes Metabolic Reprogramming in Multiple Myeloma

DNA damage resistance is a major barrier to effective DNA-damaging therapy in multiple myeloma (MM). To discover novel mechanisms through which MM cells overcome DNA damage, we investigated how MM cells become resistant to antisense oligonucleotide (ASO) therapy targeting ILF2, a DNA damage regulator that is overexpressed in 70% of MM patients whose disease has progressed after standard therapies have failed. Here, we show that MM cells undergo an adaptive metabolic rewiring and rely on oxidative phosphorylation to restore energy balance and promote survival in response to DNA damage activation. Using a CRISPR/Cas9 screening strategy, we identified the mitochondrial DNA repair protein DNA2, whose loss of function suppresses MM cells ability to overcome ILF2 ASO-induced DNA damage, as being essential to counteracting oxidative DNA damage and maintaining mitochondrial respiration. Our study revealed a novel vulnerability of MM cells that have an increased demand for mitochondrial metabolism upon DNA damage activation. STATEMENT OF SIGNIFICANCEMetabolic reprogramming is a mechanism through which cancer cells maintain survival and become resistant to DNA-damaging therapy. Here, we show that targeting DNA2 is synthetically lethal in myeloma cells that undergo metabolic adaptation and rely on oxidative phosphorylation to maintain survival after DNA damage activation.

cancer biology↗

bioRxiv2023

STAT3 protects HSCs from intrinsic interferon signaling and loss of long-term blood-forming activity

STAT3 function in hematopoietic stem and progenitor cells (HSPCs) has been difficult to discern as Stat3 deficiency in the hematopoietic system induces systemic inflammation, which can impact HSPC activity. To address this, we established mixed bone marrow (BM) chimeric mice with CreER-mediated Stat3 deletion in 20% of the hematopoietic compartment. Stat3-deficient HSPCs had impaired hematopoietic activity and failed to undergo expansion in BM in contrast to Stat3-sufficient (CreER) controls. Single-cell RNA sequencing of Lin-ckit+Sca1+ BM cells revealed altered transcriptional responses in Stat3-deficient hematopoietic stem cells (HSCs) and multipotent progenitors, including intrinsic activation of cell cycle, stress response, and interferon signaling pathways. Consistent with their deregulation, Stat3-deficient Lin-ckit+Sca1+ cells accumulated {gamma}H2AX over time. Following secondary BM transplantation, Stat3-deficient HSPCs failed to reconstitute peripheral blood effectively, indicating a severe functional defect in the HSC compartment. Our results reveal essential roles for STAT3 in HSCs and suggest the potential for using targeted synthetic lethal approaches with STAT3 inhibition to remove defective or diseased HSPCs. Key PointsO_LISTAT3 is critical for hematopoietic activity and hematopoietic stem cell maintenance in non-inflammatory conditions C_LIO_LISTAT3 has a cell-intrinsic role in the suppression of interferon signaling and myeloid-skewed transcription in hematopoietic stem cells C_LI

immunology↗

bioRxiv2022

Telomere dysfunction impairs intestinal differentiation andpredisposes to diet-induced colitis

Intestinal epithelium dysfunction causes barrier defects, malabsorption and dysbiosis, predicting local and systemic disease, morbidity and mortality in humans. However, the underlying causes are not well understood. Here we show that telomere shortening is a host intrinsic factor that impairs enterocyte differentiation. The presence of such undifferentiated enterocytes is associated with barrier disruption and malabsorption of nutrients, such as fructose. A fructose-rich diet causes increased fructose spillover to the colon and induces colitis in a microbiome-dependent manner. The microbiome uses fructose to synthesize essential metabolites, including NAD precursors, that complement the hosts low NAD pool in the inflamed colon. Thus, telomere shortening drives enterocyte dysfunction and predisposes to diet-induced colitis through barrier disruption, increased nutrient flux to the colon and modulation of the microbiome. This differerentiation defect expands the canonical stem cell failure-centered view of how telomere shortening impacts the intestine and predisposes to intestinal disease in conditions associated with short telomeres.

cell biology↗