The gut microbial metabolite formate exacerbates colorectal cancer progression

in Nature Metabolism (2022)

The gut microbiome is a key player in the immunomodulatory and protumorigenic microenvironment during colorectal cancer (CRC), as different gut-derived bacteria can induce tumour growth. However, the ... [more ▼]

The gut microbiome is a key player in the immunomodulatory and protumorigenic microenvironment during colorectal cancer (CRC), as different gut-derived bacteria can induce tumour growth. However, the crosstalk between the gut microbiome and the host in relation to tumour cell metabolism remains largely unexplored. Here we show that formate, a metabolite produced by the CRC-associated bacterium Fusobacterium nucleatum, promotes CRC development. We describe molecular signatures linking CRC phenotypes with Fusobacterium abundance. Cocultures of F. nucleatum with patient-derived CRC cells display protumorigenic effects, along with a metabolic shift towards increased formate secretion and cancer glutamine metabolism. We further show that microbiome-derived formate drives CRC tumour invasion by triggering AhR signalling, while increasing cancer stemness. Finally, F. nucleatum or formate treatment in mice leads to increased tumour incidence or size, and Th17 cell expansion, which can favour proinflammatory profiles. Moving beyond observational studies, we identify formate as a gut-derived oncometabolite that is relevant for CRC progression. [less ▲]

Stromal fibroblasts shape the myeloid phenotype in normal colon and colorectal cancer and induce CD163 and CCL2 expression in macrophages

in Cancer Letters (2021)

Colorectal cancer (CRC) accounts for about 10% of cancer deaths worldwide. Colon carcinogenesis is critically influenced by the tumor microenvironment. Cancer associated fibroblasts (CAFs) and tumor ... [more ▼]

Colorectal cancer (CRC) accounts for about 10% of cancer deaths worldwide. Colon carcinogenesis is critically influenced by the tumor microenvironment. Cancer associated fibroblasts (CAFs) and tumor associated macrophages (TAMs) represent the major components of the tumor microenvironment. TAMs promote tumor progression, angiogenesis and tissue remodeling. However, the impact of the molecular crosstalk of tumor cells (TCs) with CAFs and macrophages on monocyte recruitment and their phenotypic conversion is not known in detail so far. In a 3D human organotypic CRC model, we show that CAFs and normal colonic fibroblasts are critically involved in monocyte recruitment and for the establishment of a macrophage phenotype, characterized by high CD163 expression. This is in line with the steady recruitment and differentiation of monocytes to immunosuppressive macrophages in the normal colon. Cytokine profiling revealed that CAFs produce M-CSF, and IL6, IL8, HGF and CCL2 secretion was specifically induced by CAFs in co-cultures with macrophages. Moreover, macrophage/CAF/TCs co-cultures increased TC invasion. We demonstrate that CAFs and macrophages are the major producers of CCL2 and, upon co-culture, increase their CCL2 production twofold and 40-fold, respectively. CAFs and macrophages expressing high CCL2 were also found in vivo in CRC, strongly supporting our findings. CCL2, CCR2, CSF1R and CD163 expression in macrophages was dependent on active MCSFR signaling as shown by M-CSFR inhibition. These results indicate that colon fibroblasts and not TCs are the major cellular component, recruiting and dictating the fate of infiltrated monocytes towards a specific macrophage population, characterized by high CD163 expression and CCL2 production. [less ▲]

Hypoxia-Induced Adaptations of miRNomes and Proteomes in Melanoma Cells and Their Secreted Extracellular Vesicles

in Cancers (2020)

Reduced levels of intratumoural oxygen are associated with hypoxia-induced pro-oncogenic events such as invasion, metabolic reprogramming, epithelial–mesenchymal transition, metastasis and resistance to ... [more ▼]

Reduced levels of intratumoural oxygen are associated with hypoxia-induced pro-oncogenic events such as invasion, metabolic reprogramming, epithelial–mesenchymal transition, metastasis and resistance to therapy, all favouring cancer progression. Small extracellular vesicles (EV) shuttle various cargos (proteins, miRNAs, DNA and others). Tumour-derived EVs can be taken up by neighbouring or distant cells in the tumour microenvironment, thus facilitating intercellular communication. The quantity of extracellular vesicle secretion and their composition can vary with changing microenvironmental conditions and disease states. Here, we investigated in melanoma cells the influence of hypoxia on the content and number of secreted EVs. Whole miRNome and proteome profiling revealed distinct expression patterns in normoxic or hypoxic growth conditions. Apart from the well-known miR-210, we identified miR-1290 as a novel hypoxia-associated microRNA, which was highly abundant in hypoxic EVs. On the other hand, miR-23a-5p and -23b-5p were consistently downregulated in hypoxic conditions, while the protein levels of the miR-23a/b-5p-predicted targetIPO11were concomitantly upregulated. Furthermore, hypoxic melanoma EVs exhibit a signature consisting of six proteins (AKR7A2, DDX39B, EIF3C, FARSA, PRMT5, VARS), which were significantly associated with a poor prognosis for melanoma patients, indicating that proteins and/or miRNAs secreted by cancer cells may be exploited as biomarkers. [less ▲]

Human telomerase reverse transcriptase depletion potentiates the growth- T inhibitory activity of imatinib in chronic myeloid leukemia stem cells

in Cancer Letters (2020)

Although tyrosine kinase inhibitors (TKIs) revolutionized the management of chronic myeloid leukemia (CML), resistance against TKIs and leukemia stem cell (LSC) persistence remain a clinical concern ... [more ▼]

Although tyrosine kinase inhibitors (TKIs) revolutionized the management of chronic myeloid leukemia (CML), resistance against TKIs and leukemia stem cell (LSC) persistence remain a clinical concern. Therefore, new therapeutic strategies combining conventional and novel therapies are urgently needed. Since telomerase is involved in oncogenesis and tumor progression but is silent in most human normal somatic cells, it may be an interesting target for CML therapy by selectively targeting cancer cells while minimizing effects on normal cells. Here, we report that hTERT expression is associated with CML disease progression. We also provide evidence that hTERT-deficient K-562 cells do not display telomere shortening and that telomere length is maintained through the ALT pathway. Furthermore, we show that hTERT depletion exerts a growth-inhibitory effect in K- 562 cells and potentiates imatinib through alteration of cell cycle progression leading to a senescence-like phenotype. Finally, we demonstrate that hTERT depletion potentiates the imatinib-induced reduction of the ALDH+-LSC population. Altogether, our results suggest that the combination of telomerase and TKI should be considered as an attractive strategy to treat CML patients to eradicate cancer cells and prevent relapse by tar- geting LSCs. [less ▲]

Sphingolipid-mediated inflammatory signaling leading to autophagy inhibition converts erythropoiesis to myelopoiesis in human hematopoietic stem/progenitor cells

in Cell Death and Differentiation (2019), 26(9), 17961812

Elevated levels of the pro-inflammatory cytokine tumor necrosis factor-α (TNFα) inhibit erythropoiesis and cause anemia in patients with cancer and chronic inflammatory diseases. TNFα is also a potent ... [more ▼]

Elevated levels of the pro-inflammatory cytokine tumor necrosis factor-α (TNFα) inhibit erythropoiesis and cause anemia in patients with cancer and chronic inflammatory diseases. TNFα is also a potent activator of the sphingomyelinase (SMase)/ceramide pathway leading to ceramide synthesis and regulating cell differentiation, proliferation, apoptosis, senescence, and autophagy. Here we evaluated the implication of the TNFα/SMase/ceramide pathway on inhibition of erythropoiesis in human CD34+ hematopoietic stem/progenitor cells (CD34/HSPCs) from healthy donors. Exogenous synthetic C2- and C6-ceramide as well as bacterial SMase inhibited erythroid differentiation in erythropoietin-induced (Epo)CD34/HSPCs shown by the analysis of various erythroid markers. The neutral SMase inhibitor GW4869 as well as the genetic inhibition of nSMase with small interfering RNA (siRNA) against sphingomyelin phosphodiesterase 3 (SMPD3) prevented the inhibition by TNFα, but not the acid SMase inhibitor desipramine. Moreover, sphingosine-1-phosphate (S1P), a ceramide metabolite, restored erythroid differentiation, whereas TNFα inhibited sphingosine kinase-1, required for S1P synthesis. Analysis of cell morphology and colony formation demonstrated that erythropoiesis impairment was concomitant with a granulomonocytic differentiation in TNFα- and ceramide-treated EpoCD34/HSPCs. Inhibition of erythropoiesis and induction of granulomonocytic differentiation were correlated to modulation of hematopoietic transcription factors (TFs) GATA-1, GATA-2, and PU.1. Moreover, the expression of microRNAs (miR)-144/451, miR-146a, miR-155, and miR-223 was also modulated by TNFα and ceramide treatments, in line with cellular observations. Autophagy plays an essential role during erythropoiesis and our results demonstrate that the TNFα/neutral SMase/ceramide pathway inhibits autophagy in EpoCD34/HSPCs. TNFα- and ceramide-induced phosphorylation of mTORS2448 and ULK1S758, inhibited Atg13S355 phosphorylation, and blocked autophagosome formation as shown by transmission electron microscopy and GFP-LC3 punctae formation. Moreover, rapamycin prevented the inhibitory effect of TNFα and ceramides on erythropoiesis while inhibiting induction of myelopoiesis. In contrast, bafilomycin A1, but not siRNA against Atg5, induced myeloid differentiation, while both impaired erythropoiesis. We demonstrate here that the TNFα/neutral SMase/ceramide pathway inhibits erythropoiesis to induce myelopoiesis via modulation of a hematopoietic TF/miR network and inhibition of late steps of autophagy. Altogether, our results reveal an essential role of autophagy in erythroid vs. myeloid differentiation. [less ▲]

Cytostatic hydroxycoumarin OT52 induces ER/Golgi stress and STAT3 inhibition triggering non-canonical cell death and synergy with BH3 mimetics in lung cancer.

in Cancer Letters (2018)

Coumarins are natural compounds with antioxidant, anti-inflammatory and anti-cancer potential known to modulate inflammatory pathways. Here, non-toxic biscoumarin OT52 strongly inhibited proliferation of ... [more ▼]

Coumarins are natural compounds with antioxidant, anti-inflammatory and anti-cancer potential known to modulate inflammatory pathways. Here, non-toxic biscoumarin OT52 strongly inhibited proliferation of non-small cell lung cancer cells with KRAS mutations, inhibited stem-like characteristics by reducing aldehyde dehydrogenase expression and abrogated spheroid formation capacity. This cytostatic effect was characterized by cell cycle arrest and onset of senescence concomitant with endoplasmic reticulum and Golgi stress, leading to metabolic alterations. Mechanistically, this cellular response was associated with the novel capacity of biscoumarin OT52 to inhibit STAT3 transactivation and expression of its target genes linked to proliferation. These results were validated by computational docking of OT52 to the STAT3 DNA-binding domain. Combination treatments of OT52 with subtoxic concentrations of Bcl-xL and Mcl-1-targeting BH3 protein inhibitors triggered synergistic immunogenic cell death validated in colony formation assays as well as in vivo by zebrafish xenografts. [less ▲]