Aberrant SYK Kinase Signaling Is Essential for Tumorigenesis Induced by TSC2 Inactivation

Lymphangioleiomyomatosis: circulating levels of FGF23 and pulmonary diffusion

OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare, destructive disease of the lungs with a limited number of determinants of disease activity, which are a critical need for clinical trials. FGF23 has been implicated in several chronic pulmonary diseases. We aimed to determine the association between serum FGF23 levels and pulmonary function in a cohort of patients with LAM.

METHODS

This was a descriptive single-center study in which subjects with LAM and controls with unreported lung disease were recruited. Serum FGF23 levels were measured in all subjects. Clinical data, including pulmonary function testing, were retrospectively obtained from electronic medical records of LAM subjects. Associations between FGF23 levels and clinical features of LAM were explored via nonparametric hypothesis testing.

RESULTS

The sample comprised 37 subjects with LAM and 16 controls. FGF23 levels were higher in the LAM group than in the control group. In the LAM group, FGF23 levels above the optimal cutoff point distinguished 33% of the subjects who had nondiagnostic VEGF-D levels. Lower FGF23 levels were associated with impaired DLCO (p = 0.04), particularly for those with isolated diffusion impairment with no other spirometric abnormalities (p = 0.04).

CONCLUSIONS

Our results suggest that FGF23 is associated with pulmonary diffusion abnormalities in LAM patients and elicit novel mechanisms of LAM pathogenesis. FGF23 alone or in combination with other molecules needs to be validated as a biomarker of LAM activity in future clinical research.

Soluble Immune-Related Proteins as New Candidate Serum Biomarkers for the Diagnosis and Progression of Lymphangioleiomyomatosis

Background

The goal of this study was to analyze serum from lymphangioleiomyomatosis (LAM) patients and healthy controls to identify novel biomarkers that could shed light on disease diagnosis and pathogenesis.

Methods

From April 2017 to October 2019, qualified serum samples were obtained to explore differences in 59 immune proteins between 67 LAM patients and 49 healthy controls by the Luminex method.

Results

We characterized 22 serum immune proteins that were differentially expressed in LAM patients compared with healthy people. Fifty-nine proteins were then classified into eight categories according to their biological function, and the results showed that LAM patients displayed significantly higher levels of growth factors (p = 0.006) and lower levels of costimulatory molecules (p = 0.008). LAG-3 was not only likely to have better predictive value than VEGF-D but also showed a significant difference between patients without elevated VEGF-D and healthy people. IL-18 was positively correlated with lung function and six-minute walk test (6MWT) distance and negatively correlated with St. George’s Respiratory Questionnaire (SGRQ) score and pulmonary artery systolic pressure (PASP), which suggested that IL-18 was related to disease severity. PD-1 was significantly different between patients with pneumothorax and/or chylothorax and those without complications.

Conclusion

We performed a large-scale serum immune factor analysis of LAM. Our study provides evidence that LAG-3 may be a novel candidate serum biomarker for the diagnosis of LAM. Future independent validation in prospective studies is warranted.

ETV2 regulates PARP-1 binding protein to induce ER stress-mediated death in tuberin-deficient cells

Lymphangioleiomyomatosis (LAM) is a rare progressive disease, characterized by mutations in the tuberous sclerosis complex genes (TSC1 or TSC2) and hyperactivation of mechanistic target of rapamycin complex 1 (mTORC1). Here, we report that E26 transformation-specific (ETS) variant transcription factor 2 (ETV2) is a critical regulator of Tsc2-deficient cell survival. ETV2 nuclear localization in Tsc2-deficient cells is mTORC1-independent and is enhanced by spleen tyrosine kinase (Syk) inhibition. In the nucleus, ETV2 transcriptionally regulates poly(ADP-ribose) polymerase 1 binding protein (PARPBP) mRNA and protein expression, partially reversing the observed down-regulation of PARPBP expression induced by mTORC1 blockade during treatment with both Syk and mTORC1 inhibitors. In addition, silencing Etv2 or Parpbp in Tsc2-deficient cells induced ER stress and increased cell death in vitro and in vivo. We also found ETV2 expression in human cells with loss of heterozygosity for TSC2, lending support to the translational relevance of our findings. In conclusion, we report a novel ETV2 signaling axis unique to Syk inhibition that promotes a cytocidal response in Tsc2-deficient cells and therefore maybe a potential alternative therapeutic target in LAM.

The lung microbiome in end-stage Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a progressive cystic lung disease with mortality driven primarily by respiratory failure. Patients with LAM frequently have respiratory infections, suggestive of a dysregulated microbiome. Here we demonstrate that end-stage LAM patients have a distinct microbiome signature compared to patients with end-stage chronic obstructive pulmonary disease.

Interleukin-6 mediates PSAT1 expression and serine metabolism in TSC2-deficient cells

Tuberous sclerosis complex (TSC) and lymphangioleiomyomatosis (LAM) are caused by aberrant mechanistic Target of Rapamycin Complex 1 (mTORC1) activation due to loss of either TSC1 or TSC2 Cytokine profiling of TSC2-deficient LAM patient-derived cells revealed striking up-regulation of Interleukin-6 (IL-6). LAM patient plasma contained increased circulating IL-6 compared with healthy controls, and TSC2-deficient cells showed up-regulation of IL-6 transcription and secretion compared to wild-type cells. IL-6 blockade repressed the proliferation and migration of TSC2-deficient cells and reduced oxygen consumption and extracellular acidification. U-¹³C glucose tracing revealed that IL-6 knockout reduced 3-phosphoserine and serine production in TSC2-deficient cells, implicating IL-6 in de novo serine metabolism. IL-6 knockout reduced expression of phosphoserine aminotransferase 1 (PSAT1), an essential enzyme in serine biosynthesis. Importantly, recombinant IL-6 treatment rescued PSAT1 expression in the TSC2-deficient, IL-6 knockout clones selectively and had no effect on wild-type cells. Treatment with anti-IL-6 (αIL-6) antibody similarly reduced cell proliferation and migration and reduced renal tumors in Tsc2 ^+/- mice while reducing PSAT1 expression. These data reveal a mechanism through which IL-6 regulates serine biosynthesis, with potential relevance to the therapy of tumors with mTORC1 hyperactivity.

Possible Novel Therapeutic Targets in Lymphangioleiomyomatosis Treatment

Lymphangioleiomyomatosis (LAM) is a rare systemic neoplastic disease that exclusively happens in women. Studies focusing on LAM and tuberous sclerosis complex (TSC) have made great progress in understanding the pathogenesis and searching for treatment. The inactive mutation of TSC1 or TSC2 is found in patients with LAM to activate the crucial mammalian target of rapamycin (mTOR) signaling pathway and result in enhanced cell proliferation and migration. However, it does not explain every step of tumorigenesis in LAM. Because cessation of rapamycin would break the stabilization of lung function or improved quality of life and lead to disease recurrent, continued studies on the pathogenesis of LAM are necessary to identify novel targets and new treatment. Researchers have found several aberrant regulations that affect the mTOR pathway such as its upstream or downstream molecules and compensatory pathways in LAM. Some therapeutic targets have been under study in clinical trials. New methods like genome-wide association studies have located a novel gene related to LAM. Herein, we review the current knowledge regarding pathogenesis and treatment of LAM and summarize novel targets of therapeutic potential recently.

Imatinib-Induced Changes in Protein Expression and ATP-Binding Affinities of Kinases in Chronic Myelocytic Leukemia Cells

Kinases are crucial components in numerous cell signaling pathways. Aberrant expression and activation of protein kinases are known to be accompanied by many types of cancer, and more than 30 small-molecule kinase inhibitors have been approved by the Food and Drug Administration (FDA) for cancer chemotherapy. Biological and clinical applications of small-molecule kinase inhibitors require comprehensive characterizations about how these inhibitors modulate the protein expression and activities of kinases at the entire proteome scale. In this study, we developed a parallel-reaction monitoring (PRM)-based targeted proteomic method to monitor the alterations in protein expression of kinases in K-562 chronic myelocytic leukemia (CML) cells elicited by treatment with imatinib, an ABL kinase inhibitor approved by the FDA for CML treatment. By employing isotope-coded ATP affinity probes together with liquid chromatography-multiple-reaction monitoring (LC-MRM) analysis, we also examined the modulation of the ATP-binding affinities of kinases induced by imatinib treatment. The results revealed profound increases in protein expression levels of a large number of kinases in K-562 cells upon treatment with imatinib, which is accompanied by substantial decreases in ATP-binding capacities of many kinases. Apart from ABL kinases, we identified a number of other kinases whose ATP-binding affinities are markedly diminished upon imatinib treatment, including CHK1, a checkpoint kinase involved in DNA damage response signaling. Together, our targeted quantitative proteomic methods enabled, for the first time, dual assessments of small-molecule kinase inhibitor-induced changes in protein expression and ATP-binding affinities of kinases in live cells.

Lymphangioleiomyomatosis: a case report and review of diagnosis and treatment

Lymphangioleiomyomatosis (LAM) is a rare disease that generally affects young women and involves the abnormal proliferation of smooth muscle-like cells (LAM cells) in the lungs (pulmonary LAM) and extrapulmonary sites (extrapulmonary LAM). This disease is rare in males. It is hard to distinguish between lung cancer and pulmonary LAM, especially during early stages. Herein, we present a case of a 66-year-old man with a small nodule in the right upper lobe that was first diagnosed as a lung malignancy using a chest CT scan. After a wedge dissection, a pathologist performed a histologic and immunohistochemical examination, and a diagnosis of pulmonary LAM was made. We further performed a 518-gene panel analysis using next-generation sequencing, and only three genes, BARD1, BLM, and BRCA2, were found to have mutations. We also provide a summary of the diagnosis and treatment of this disease.

Circulating Biomarkers From the Phase 1 Trial of Sirolimus and Autophagy Inhibition for Patients With Lymphangioleiomyomatosis

BACKGROUND

We have previously conducted the Sirolimus and Autophagy Inhibition in LAM (SAIL) trial, a phase 1 dose-escalation study of the combination of sirolimus and hydroxychloroquine in patients with lymphangioleiomyomatosis (LAM). The goal of the present study was to analyze sera from the SAIL trial to identify novel biomarkers that could shed light into disease pathogenesis and response to therapy.

METHODS

We used the DiscoveryMAP platform from Rules Based Medicine to simultaneously measure 279 analytes in sera collected at each visit from subjects enrolled in the SAIL trial. We used longitudinal regression and pathway analysis to examine analyte rate of change and corresponding effect on lung function and to identify networks and potential nodes of interest.

RESULTS

A total of 222 analytes were included in the analysis. We identified 32 analytes that changed over the treatment period of the study. Pathway analysis revealed enrichment in cytokine-receptor interaction and mechanistic/mammalian target of rapamycin-related pathways, in addition to seemingly unrelated processes such as rheumatoid arthritis. Search Tool for the Retrieval of Interacting Genes/Proteins analysis identified two hubs centered around acetyl-CoA carboxylase alpha and beta and coagulation factor II. In addition, we identified vascular endothelial growth factor receptor-3 and CCL21 as molecules significantly associated with changes in FEV₁ during the study period.

CONCLUSIONS

We performed a large-scale analyte study in sera of women with LAM and identified potential markers that could be linked to disease pathogenesis, lung injury, and therapeutic response. These data will enable future investigation into the specific roles of these molecules in LAM.

TRIAL REGISTRY

ClinicalTrials.gov; No. NCT01687179; URL: www.clinicaltrials.gov).

The Lymphangioleiomyomatosis Lung Cell and Its Human Cell Models

Lymphangioleiomyomatosis (LAM) is a multisystem disease of women, affecting lungs, kidneys, and lymphatics. It is caused by the proliferation of abnormal smooth muscle-like LAM cells, with mutations and loss of heterozygosity in the TSC1 or, more frequently, TSC2 genes. Isolated pulmonary LAM cells have been difficult to maintain in culture, and most studies of LAM lung cells involve mixtures of TSC2 wild-type and TSC2-null cells. A clonal population of LAM lung cells has not been established, making analysis of the cells challenging. Cell lines have been established from angiomyolipomas, a common manifestation of LAM, and from tumors from patients with TSC. Circulating LAM cells have also been isolated from blood and other body fluids. LAM cells may also be identified in clusters apparently derived from lymphatic vessels. Genetics, patterns of antigen expression, and signaling pathways have been studied in LAM lung tissue and in LAM cell models, although rarely all in the same study. We show here that LAM cells manifest differences in these characteristics, depending on the source investigated, suggesting further studies.

Emerging biomarkers of lymphangioleiomyomatosis

INTRODUCTION

Lymphangioleiomyomatosis (LAM) is a destructive lung disease affecting primarily women. LAM is caused by inactivating mutations in the tuberous sclerosis complex (TSC) genes, resulting in hyperactivation of mechanistic/mammalian target of rapamycin complex 1 (mTORC1). Over the past five years, there have been remarkable advances in the diagnosis and therapy of LAM, including the identification of vascular endothelial growth factor D (VEGF-D) as a diagnostic biomarker and the US Food and Drug Administration approval of sirolimus as therapy for LAM. In appropriate clinical situations VEGF-D testing can make lung biopsy unnecessary to diagnose LAM. However, there remains an urgent unmet need for additional biomarkers of disease activity and/or response to therapy. Areas covered: This work reviews VEGF-D, an established LAM biomarker, and discusses emerging biomarkers, including circulating LAM cells, imaging, lipid, and metabolite biomarkers, focusing on those with the highest potential impact for LAM patients. Expert commentary: Ongoing research priorities include the development of validated biomarkers to 1) noninvasively diagnose LAM in women whose VEGF-D levels are not diagnostic, 2) accurately predict the likelihood of disease progression and 3) quantitatively measure disease activity and LAM cell burden. These biomarkers would enable personalized, precision clinical care and fast-track clinical trial implementation, with high clinical impact.

Lymphatic Changes in Respiratory Diseases: More than Just Remodeling of the Lung?

Advances in our ability to identify lymphatic endothelial cells and differentiate them from blood endothelial cells have led to important progress in the study of lymphatic biology. Over the past decade, preclinical and clinical studies have shown that there are changes to the lymphatic vasculature in nearly all lung diseases. Efforts to understand the contribution of lymphatics and their growth factors to disease initiation, progression, and resolution have led to seminal findings establishing critical roles for lymphatics in lung biology spanning from the first breath after birth to asthma, tuberculosis, and lung transplantation. However, in other diseases, it remains unclear if lymphatics are part of the overall lung remodeling process or real contributors to disease pathogenesis. The goal of this Translational Review is to highlight some of the advances in our understanding of the role(s) of lymphatics in lung disease and shed light on the critical needs and unanswered questions that might lead to novel translational applications.