Midkine expression by stem-like tumor cells drives persistence to mTOR inhibition and rewires the microenvironment toward an immune-suppressive state
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ABSTRACT: mTORC1 regulates cell metabolism to enable cell proliferation, and is hyperactive in multiple cancer types1,2. Here, we performed integrative analysis of single cell transcriptomic profiling, paired T cell receptor (TCR) sequencing, and spatial transcriptomic profiling on Tuberous Sclerosis Complex (TSC) associated tumors with mTORC1 hyperactivity, and identified a stem-like tumor cell state (SLS) linked to T cell dysfunction via tumor-modulated immunosuppressive macrophages. Rapamycin and its derivatives (rapalogs) are the primary treatments for TSC tumors, and the stem-like tumor cells showed rapamycin resistance in vitro, reminiscent of the cytostatic effects of these drugs in patients. The pro-angiogenic factor midkine (MDK) was highly expressed by the SLS population, and associated with enrichment of endothelial cells in SLS-dominant samples. Inhibition of MDK showed synergistic benefit with rapamycin in reducing the growth of TSC cell lines in vitro and in vivo. In aggregate, this study suggests an autocrine rapamycin resistance mechanism and a paracrine tumor survival mechanism via immune suppression adopted by the stem-like state tumor cells with mTORC1 hyperactivity. We also provide a comprehensive resource to advance the understanding of TSC and potentially other mTORC1-hyperactive tumors.
Project description:mTORC1 regulates cell metabolism to enable cell proliferation, and is hyperactive in multiple cancer types. Here, we performed integrative analysis of single cell transcriptomic profiling, paired T cell receptor (TCR) sequencing, and spatial transcriptomic profiling on Tuberous Sclerosis Complex (TSC) associated tumors with mTORC1 hyperactivity, and identified a stem-like tumor cell state (SLS) linked to T cell dysfunction via tumor-modulated immunosuppressive macrophages. Rapamycin and its derivatives (rapalogs) are the primary treatments for TSC tumors, and the stem-like tumor cells showed rapamycin resistance in vitro, reminiscent of the cytostatic effects of these drugs in patients. The pro-angiogenic factor midkine (MDK) was highly expressed by the SLS population, and associated with enrichment of endothelial cells in SLS-dominant samples. Inhibition of MDK showed synergistic benefit with rapamycin in reducing the growth of TSC cell lines in vitro and in vivo. In aggregate, this study suggests an autocrine rapamycin resistance mechanism and a paracrine tumor survival mechanism via immune suppression adopted by the stem-like state tumor cells with mTORC1 hyperactivity. We also provide a comprehensive resource to advance the understanding of TSC and potentially other mTORC1-hyperactive tumors.
Project description:Immune checkpoints are often expressed on tumor cells; it remains a prevailing need to identify the mechanisms underlying their regulation and therapeutic benefit. The immune checkpoint molecule B7-H3 is upregulated in many human tumors, including those with high mechanistic/mammalian target of rapamycin complex (mTORC1) activity. Still, its role in tumor immunity and the impact of B7-H3-targeted therapy on the tumor immune microenvironment are largely uncharacterized in mTORC1-hyperactive tumors. Here, we used a syngeneic murine model of tuberous sclerosis complex (TSC), a model of mTORC1 hyperactivity, to assess the mechanisms by which B7-H3 remodels the tumor microenvironment. We performed gene expression profiling analysis using data generated from RNA-seq of bulk tumors from subcutaneous B7-H3 knockdown and control TSC2-deficient 105K cells or sorted tumor cells isolated by MACS mouse tumor cell isolation kit (Miltenyi Biotec).
Project description:Immune checkpoints are often expressed on tumor cells; it remains a prevailing need to identify the mechanisms underlying their regulation and therapeutic benefit. The immune checkpoint molecule B7-H3 is upregulated in many human tumors, including those with high mechanistic/mammalian target of rapamycin complex (mTORC1) activity. However, its role in tumor immunity and the impact of B7-H3-targeted therapy on the tumor immune microenvironment are largely uncharacterized. Here, we used a syngeneic murine model of tuberous sclerosis complex (TSC), a model of mTORC1 hyperactivity, to assess the mechanisms by which B7-H3 remodels the tumor microenvironment. We performed gene and protein expression profiling analysis using data generated from CITE-seq of infiltrating CD3+ T cells isolated by FACS from subcutaneous B7-H3 knockdown and control TSC2-deficient 105K tumors.
Project description:Tuberous Sclerosis Complex (TSC) is caused by germline TSC1 or TSC2 mutations, leading to hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1) and tumors in multiple organs including the brain, heart, lung (lymphangioleiomyomatosis), and kidney (angiomyolipoma and renal cell carcinoma). Previously, we found that TFEB is constitutively active in models of TSC. To determine the impact of TFEB in vivo, we generated two novel mouse models of TSC, resulting in premature death, in which kidney pathology was the primary phenotype. RNA sequencing revealed that lysosomal and proteasomal gene pathways were the most highly upregulated in the TSC2-deficient kidneys. Knockout of TFEB rescued both kidney pathology and overall survival in both models, indicating that TFEB is the primary driver of renal disease in TSC. Importantly, mTORC1 activity, which was elevated in the TSC2 knockout kidneys, was normalized by TFEB knockout. Knockdown of Rheb or treatment of TSC2-deficient cells with Rapamycin paradoxically increases TFEB phosphorylation at the mTORC1-site (S211) and relocalizes TFEB from the nucleus to the cytoplasm via a Rag-dependent mechanism. Accordingly, treatment of TSC2 knockout mice with Rapamycin normalized lysosomal gene expression, similar to TFEB knockout, suggesting that the beneficial effects of Rapamycin in TSC are TFEB-dependent. These results change the view of the mechanisms leading to mTORC1 hyperactivation in TSC and may lead to novel therapeutic avenues for the treatment of TSC.
Project description:Lymphangioleiomyomatosis (LAM) is a rare, debilitating lung disease that predominantly affects women of reproductive age. LAM cells carry deleterious mutations of tuberous sclerosis complex (TSC1/TSC2) genes, resulting in hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) and ultimately dysregulated cell growth. The integrative single cell omics data identified the activation of uterine specific HOX-PBX transcriptional programming in pulmonary LAMCORE cells. Network analysis predicted homeobox transcription factors including PBX1 and HOXD11 as key regulators controlling LAMCORE cell fate. Targeting the HOX-PBX network may have therapeutic value in LAM and TSC-related diseases, and possibly in other mTORC1-hyperactive neoplasms.
Project description:Lymphangioleiomyomatosis (LAM) is a rare, debilitating lung disease that predominantly affects women of reproductive age. LAM cells carry deleterious mutations of tuberous sclerosis complex (TSC1/TSC2) genes, resulting in hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) and ultimately dysregulated cell growth. The integrative single cell omics data identified the activation of uterine specific HOX-PBX transcriptional programming in pulmonary LAMCORE cells. Network analysis predicted homeobox transcription factors including PBX1 and HOXD11 as key regulators controlling LAMCORE cell fate. Targeting the HOX-PBX network may have therapeutic value in LAM and TSC-related diseases, and possibly in other mTORC1-hyperactive neoplasms.
Project description:Aberrant activation of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a common molecular event in a large variety of pathological settings, including genetic tumor syndromes, cancer, and obesity. However, the cell intrinsic consequences of mTORC1 activation remain poorly defined. Here, we identify global trancriptional changes in TSC1 and TSC2 null MEFs, which exhibit constitutive activation of mTORC1, compared to wild-type littermate control lines. A rapamycin time course is included to determine those changes that are dependent on mTORC1 signaling, revealing mTORC1 induced and repressed transcripts. In order to identify mTORC1-dependent transcriptional changes, we compared wild-type MEFs to both Tsc1-/- and Tsc2-/- MEFs following serum starvation, where mTORC1 signaling is off in wild-type cells and fully active in TSC-deficient cells. All cell lines were serum-starved for 24 h, and the Tsc1-/- and Tsc2-/- cells were treated with a time course of rapamycin prior to the isolation of mRNA for microarray analysis. Immortalized wild-type (Tsc2+/+ p53-/-), Tsc1-/- (p53+/+, 3T3-immortalized), and Tsc2-/- (p53-/-, derived from a littermate of the wild-type cell line) MEFs are the three cell lines used in this study and were derived in the laboratory of David J. Kwiatkowski (Brigham and Women's Hospital, Harvard Medical School, Boston, MA). Wild-type and null MEFs were grown to 70% confluence in 10 cm plates and were serum starved for 24 h in the presence of vehicle (DMSO) for 24 h or rapamycin (20 nM) for 2, 6, 12, or 24 h. All vehicle-treated samples (0 h time points) were plated in triplicate and all rapamycin time course samples were plated in duplicate. For each replicate, expression analysis was performed by hybridization to an Affymetrix Mouse 430_2 oligonucleotide microarray chip.
Project description:Tuberous Sclerosis Complex (TSC) is a disease caused by autosomal dominant mutations in the TSC1 or TSC2 genes, and is characterized by tumor susceptibility, brain lesions, seizures and behavioral impairments. The TSC1 and TSC2 genes encode proteins forming a complex (TSC), which is a major regulator and suppressor of mammalian target of rapamycin (mTOR) in complex 1 (mTORC1), a signaling complex that promotes cell growth and proliferation. TSC1/2 loss of heterozygosity (LOH) and the subsequent complete loss of TSC regulatory activity in null cells causes mTORC1 dysregulation and TSC-associated brain lesions or other tissue tumors. However, it is not clear whether TSC1/2 heterozygous brain cells are abnormal and contribute to TSC neuropathology. To investigate this issue, we generated induced pluripotent stem cells (iPSCs) from TSC patients and unaffected controls, and utilized these to obtain neural progenitor cells (NPCs) and differentiated neurons in vitro. These patient-derived TSC2 heterozygous NPCs were delayed in their ability to differentiate into neurons. Patient-derived progenitor cells also exhibited a modest activation of mTORC1 signaling downstream of TSC, and a marked attenuation of upstream PI3K/AKT signaling. We further show that pharmacologic AKT inhibition, but not mTORC1 inhibition, causes a neuronal differentiation delay, mimicking the patient phenotype. Together these data suggest that heterozygous TSC2 mutations disrupt neuronal development, potentially contributing to the disease neuropathology, and that this defect may result from dysregulated AKT signaling in neural progenitor cells.
Project description:Tuberous Sclerosis Complex (TSC) and Lymphangioleiomyomatosis (LAM) are caused by inactivating mutations in TSC1 or TSC2, leading to mTORC1 hyperactivation. The mTORC1 inhibitors rapamycin and analogs (rapalogs) are approved for treating of TSC and LAM. Due to their cytostatic and not cytocidal action, discontinuation of treatment leads to tumor regrowth and decline in pulmonary function. Therefore, life-long rapalog treatment is proposed for the control of TSC and LAM lesions, which increases the chances for the development of acquired drug resistance. Understanding the signaling perturbations leading to rapalog resistance is critical for the development of better therapeutic strategies. We developed the first Tsc2-null rapamycin-resistant cell line, ELT3-245, which is highly tumorigenic in mice, and refractory to rapamycin treatment. In vitro ELT3-245 cells exhibit enhanced anchorage-independent cell survival, resistance to anoikis, and loss of epithelial markers. A key alteration in ELT3-245 is increased β-catenin signaling. We propose that a subset of cells in TSC and LAM lesions have additional signaling aberrations, thus possess the potential to become resistant to rapalogs. Alternatively, when challenged with rapalogs TSC-null cells are reprogrammed to express mesenchymal-like markers. These signaling changes could be further exploited to induce clinically-relevant long-term remissions.
Project description:Aberrant activation of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a common molecular event in a large variety of pathological settings, including genetic tumor syndromes, cancer, and obesity. However, the cell intrinsic consequences of mTORC1 activation remain poorly defined. Here, we identify global trancriptional changes in TSC1 and TSC2 null MEFs, which exhibit constitutive activation of mTORC1, compared to wild-type littermate control lines. A rapamycin time course is included to determine those changes that are dependent on mTORC1 signaling, revealing mTORC1 induced and repressed transcripts. In order to identify mTORC1-dependent transcriptional changes, we compared wild-type MEFs to both Tsc1-/- and Tsc2-/- MEFs following serum starvation, where mTORC1 signaling is off in wild-type cells and fully active in TSC-deficient cells. All cell lines were serum-starved for 24 h, and the Tsc1-/- and Tsc2-/- cells were treated with a time course of rapamycin prior to the isolation of mRNA for microarray analysis.