Project description:Metabolic alterations that are critical for cancer cell growth and metastasis are one of the key hallmarks of cancer. Here, we show that thymidine kinase 1 (TK1) is significantly overexpressed in tumor samples from lung adenocarcinoma (LUAD) patients relative to normal controls, and this TK1 overexpression is associated with significantly reduced overall survival and cancer recurrence. Genetic knockdown of TK1 with short hairpin RNAs (shRNAs) inhibits both the growth and metastatic attributes of LUAD cells in culture and in mice. We further show that transcriptional overexpression of TK1 in LUAD cells is driven, in part, by MAP kinase pathway in a transcription factor MAZ dependent manner. Using targeted and gene expression profiling-based approaches, we then show that loss of TK1 in LUAD cells results in reduced Rho GTPase activity and reduced expression of growth and differentiation factor 15 (GDF15). Furthermore, ectopic expression of GDF15 can partially rescue TK1 knockdown-induced LUAD growth and metastasis inhibition, confirming its important role as a downstream mediator of TK1 function in LUAD. Collectively, our findings demonstrate that TK1 facilitates LUAD tumor and metastatic growth and represents a target for LUAD therapy.
Project description:Growth Differentiation Factor 15 (GDF15) is a divergent member of the TGF-β superfamily, and its expression increases under various stress conditions, including inflammation, hyperoxia, and senescence. GDF15 expression is increased in neonatal murine BPD models, and GDF15 loss exacerbates oxidative stress and decreases viability in vitro in pulmonary epithelial and endothelial cells. Our overall hypothesis is that the loss of GDF15 will exacerbate hyperoxic lung injury in the neonatal lung in vivo. We exposed neonatal Gdf15-/- mice and wild-type (WT) controls on a similar background to room air or hyperoxia (95% O2) for 5 days after birth. The mice were euthanized on PND 21. Gdf15 -/- mice had higher mortality and lower body weight than WT mice after exposure to hyperoxia. Upon exposure to hyperoxia, female mice had higher alveolar simplification in the Gdf15-/- group than the female WT group. Gdf15-/- and WT mice showed no difference in the degree of the arrest in angiogenesis upon exposure to hyperoxia. Gdf15-/- mice showed lower macrophage count in the lungs compared to WT mice. Our results suggest that Gdf15 deficiency decreases the tolerance to hyperoxic lung injury with evidence of sex-specific differences.
Project description:Rationale: Growth/differentiation factor 15 (GDF15) is a stress cytokine with numerous proposed roles including stress erythropoiesis. Higher circulating GDF15 levels are prognostic of mortality during acute respiratory distress syndrome, but the sources and downstream effects of GDF15 during pathogen-mediated injury remain unclear. Methods: We quantified GDF15 in plasma and lower respiratory tract (LRT) biospecimens from critically-ill humans with acute respiratory failure. Publicly available data from SARS-CoV-2 infection were re-analyzed. We utilized mouse models of acute lung injury mediated by P. aeruginosa exoproducts in wildtype mice and in mice genetically deficient for Gdf15 and its putative receptor, Gfral.Results: Plasma levels of GDF15 associated with worse outcomes and LRT GDF15 levels in critically-ill humans. Intra-tracheal P. aeruginosa Type 2 secretion system exoproducts (PA SN) were sufficient to induce airspace and plasma release of GDF15 in wildtype mice, which was attenuated during epithelial-specific Gdf15 deficiency. SARS-CoV-2 infection induced GDF15 expression in human lung epithelium. Mice with global Gdf15 deficiency had decreased airspace hemorrhage, an attenuated cytokine profile, and altered lung transcriptional profile during PA SN injury, which was not recapitulated in mice deficient for Gfral. Airspace GDF15 reconstitution did not significantly modulate key lung cytokine levels but did increase circulating erythrocyte counts.Conclusions: Lung epithelium releases GDF15 during pathogen injury, which associates with plasma levels in both humans and mice and can increase erythrocyte counts in mice. Potential local and other extra-pulmonary roles for GDF15 remain undefined.
Project description:Drug tolerant persister (DTP) cells enter into a reversible slow-cycling state after cancer drug treatment. These cells are the living proof of response to a drug, and an interesting experimental subject for biomarker discovery. Here, we performed proteomic characterization of the breast cancer (BC) DTP cell secretome after eribulin treatment. First, we showed that eribulin induces a specific secretome in DTP cells as compared to other microtubule targeting agents. Then, we selected and functionally validated growth differentiation factor 15 (GDF15) as a protein significantly over-secreted upon eribulin treatment. Interestingly, GDF15 expression is low/absent in cells that are sensitive to eribulin, strongly upregulated during the response to the drug, and downregulated when stable resistance is ultimately established. Proteomic results were confirmed in 3D-cell culture models using BC cells lines and PDXs, as well as in a TNBC in vivo model. Unexpectedly, despite its biomarker potential for eribulin response, we found that GDF15 is also paradoxically required for survival of DTP cells, although once full resistance to eribulin is established, GDF15 expression largely disappears. Direct participation of GDF15 and its receptor GFRAL in eribulin-induction of DTPs was established by the enhanced cell killing of DTPs by eribulin seen under GDF15 and GFRAL loss of function conditions. These results pointed to a potential benefit of simultaneous targeting of GDF15/GFRAL and eribulin, and indeed we showed that combination therapy of eribulin plus an anti-GDF15 antibody kills BC-DTP cells. Our results suggest that targeting GDF15 may help eradicate DTP cells and block the onset of acquired eribulin resistance, and possibly other cytotoxic drugs. Overall, the combination of cytotoxic agents with targeted agents aimed specifically at DTP cells could be an effective therapeutic approach for metastatic breast cancer patients.
Project description:ERK- and USP9X-coupled regulation of thymidine kinase 1 promotes both its enzyme activity-dependent and enzyme activity-independent functions for tumor growth
Project description:Heart failure and associated cachexia is an unresolved and important problem. We report a new model of severe heart failure that consistently results in cachexia. Mice lacking the integrated stress response (ISR) induced eIF2α phosphatase, PPP1R15A, exhibit a dilated cardiomyopathy and severe weight loss following irradiation, whilst wildtype mice are unaffected. This is associated with increased expression of Gdf15 in the heart and increased levels of GDF15 in the circulation. We provide evidence that blockade of GDF15 activity prevents cachexia and slows the progression of heart failure. Our data suggests that cardiac stress mediates a GDF15 dependent pathway that drives weight loss and worsens cardiac function. We show relevance of GDF15 to lean mass and protein intake with patients with heart failure. Blockade of GDF15 could constitute a novel therapeutic option to limit cardiac cachexia and improve clinical outcomes in patients with severe systolic heart failure.
Project description:Cytokines constitute a family of proteins that are secreted by a broad variety of cells and modulate the immune response. CXCL12, along with its receptor CXCR4, are essential players in numerous biological processes. Dysregulation of their function can underlie the mechanisms(s) of several pathologies, including malignancies. Here, we demonstrate a rather unexpected effect of the cytokine and its receptor: in both cells and animal models, CXCL12 restricts tumorigenicity of the glioblastoma cells U87-MG and U-118, and of the breast cancer cell PyMT. Overexpression of CXCL12 inhibits activation of the proto-oncogene Ras which results in downregulation of its proliferative signals, such as reduced phosphorylation of the extracellular signal-regulated kinase 1/2 (ERK1/2), inhibition of c-Myc expression, and subsequent inhibition of cell cycle. Furthermore, CXCL12 induces downregulation of the growth differentiation factor 15 (GDF15), insulin-like growth factor-binding protein 6 (IGFBP6), and matrix metalloproteinase-3 (MMP3), which are implicated in the metastatic process. Indeed, monitoring cell migration in vitro and generation of metastases in mice demonstrate that CXCL12 slows the migration of U87-MG and PyMT cells. Remarkably, overexpression of CXCL12 also downregulates the cell surface immune checkpoint protein programmed cell death-ligand 1 (PDL1), as is evidence by enhanced recruitment of cytotoxic CD8 T cells. Overall, CXCL12 inhibits tumor growth through several distinct mechanisms: inhibition of cell cycle and migration, as well as impairment of immune checkpoint, thereby stimulating a strong host’s immune response. The mechanism(s) that renders CXCL12 a tumor promoting agent in certain cells, and a tumor suppressor in others has remained elusive.
Project description:Recent research has identified growth differentiation factor 15 (GDF15) as a crucial factor in various physiological and pathological processes, particularly in energy balance regulation. We here investigated the role of GDF15 in adipose tissue physiology and metabolism by performing an RNA-Seq analysis of subcutaneous adipose tissue (sWAT) of 20 week old male and female Gdf15-KO mice compared to their WT littermates. Our study revealed a broad downregulation of genes involved in lipid metabolism and furthermore, it uncovered sex-specific effects, with females being more affected by GDF15 loss than males. These insights enhance our understanding of GDF15's functions in adipose tissue physiology and underscore its potential as a therapeutic target for metabolic disorders.
Project description:Elevation of growth differentiation factor 15 (GDF15) has recently emerged as a key driver of cancer cachexia, a syndrome of extreme weight loss that affects patients with various types of cancer. Chemotherapy, as well as the tumour itself have been reported to contribute to increased GDF15 secretion in both cancer and host tissues. Bromodomain and extraterminal (BET) domain proteins have been shown to regulate GDF15 expression in pancreatic cancer cells. With currently neither preventive strategies nor specific therapeutic options for cachexia available, antibodies targeting GDF15 or its receptor are being developed. However, the mechanism of chemotherapy-induced GDF15 upregulation in tumour and host cells is still unknown, leaving uncertainty about safety and efficacy of therapies targeting retrospective reduction of GDF15 in cancer cachexia. We tested various cardiotoxic drugs for their effect on GDF15 regulation in cardiomyocyte cell culture and analysed gene expression, mutational status, and pathway activities of the NCI-60 cancer cell line panels to get further insights into the regulation of GDF15 expression in both cancer and host cells upon treatment with anticancer drugs. To investigate the regulatory effect of BET inhibition on GDF expression more extensively, we screened BET inhibitors in doxorubicin treated human cardiomyocyte cell culture as well as in 21 cancer cell lines and performed differential analysis of gene expression, metabolites, and pathway activities. Our results reveal that DNA interacting compounds induce GDF15 expression in human cardiomyocytes up to 20-fold, whereas cardiotoxic drugs with other modes of action led, if at all, to less than 3-fold induction. We discovered that BET inhibitors suppress doxorubicin-induced GDF15 overexpression in human cardiomyocytes up to 7.4-fold (p=0.0051). In cancer cell lines, we identified compound-specific gene signatures that correlate with the extent of GDF15 induction upon treatment in the espective cell line. BET inhibition also reduces GDF15 expression in a defined subset of cancer cell lines that differentiate from the other tested cell lines in a less active PI3K/Akt axis and significantly higher extracellular pantothenate concentration (p=0.00095). We identified compound- and cell-line-specific gene signatures that predict GDF15 upregulation upon treatment, providing indication that the risk for drug-induced GDF15 overexpression and concomitant cachexia can be reduced by a biomarker-driven selection of patient-specific anticancer agents. Our results suggest that BET inhibitors could counteract cachexia at the transcriptional level in tumour and host tissues by reducing GDF15 expression. We identified characteristic gene and metabolite expressions of responsive cancer cell lines that can serve as biomarkers for patient selection.
Project description:Elevation of growth differentiation factor 15 (GDF15) has recently emerged as a key driver of cancer cachexia, a syndrome of extreme weight loss that affects patients with various types of cancer. Chemotherapy, as well as the tumour itself have been reported to contribute to increased GDF15 secretion in both cancer and host tissues. Bromodomain and extraterminal (BET) domain proteins have been shown to regulate GDF15 expression in pancreatic cancer cells. With currently neither preventive strategies nor specific therapeutic options for cachexia available, antibodies targeting GDF15 or its receptor are being developed. However, the mechanism of chemotherapy-induced GDF15 upregulation in tumour and host cells is still unknown, leaving uncertainty about safety and efficacy of therapies targeting retrospective reduction of GDF15 in cancer cachexia. We tested various cardiotoxic drugs for their effect on GDF15 regulation in cardiomyocyte cell culture and analysed gene expression, mutational status, and pathway activities of the NCI-60 cancer cell line panels to get further insights into the regulation of GDF15 expression in both cancer and host cells upon treatment with anticancer drugs. To investigate the regulatory effect of BET inhibition on GDF expression more extensively, we screened BET inhibitors in doxorubicin treated human cardiomyocyte cell culture as well as in 21 cancer cell lines and performed differential analysis of gene expression, metabolites, and pathway activities. Our results reveal that DNA interacting compounds induce GDF15 expression in human cardiomyocytes up to 20-fold, whereas cardiotoxic drugs with other modes of action led, if at all, to less than 3-fold induction. We discovered that BET inhibitors suppress doxorubicin-induced GDF15 overexpression in human cardiomyocytes up to 7.4-fold (p=0.0051). In cancer cell lines, we identified compound-specific gene signatures that correlate with the extent of GDF15 induction upon treatment in the espective cell line. BET inhibition also reduces GDF15 expression in a defined subset of cancer cell lines that differentiate from the other tested cell lines in a less active PI3K/Akt axis and significantly higher extracellular pantothenate concentration (p=0.00095). We identified compound- and cell-line-specific gene signatures that predict GDF15 upregulation upon treatment, providing indication that the risk for drug-induced GDF15 overexpression and concomitant cachexia can be reduced by a biomarker-driven selection of patient-specific anticancer agents. Our results suggest that BET inhibitors could counteract cachexia at the transcriptional level in tumour and host tissues by reducing GDF15 expression. We identified characteristic gene and metabolite expressions of responsive cancer cell lines that can serve as biomarkers for patient selection.