Human WDR5 promotes breast cancer growth and metastasis via KMT2-independent translation regulation

Metastatic breast cancer remains a major cause of cancer-related deaths in women, and there are few effective therapies against this advanced disease. Emerging evidence suggests that key steps of tumor progression and metastasis are controlled by reversible epigenetic mechanisms. Using an in vivo genetic screen, we identified WDR5 as an actionable epigenetic regulator that is required for metastatic progression in models of triple-negative breast cancer. We found that knockdown of WDR5 in breast cancer cells independently impaired their tumorigenic as well as metastatic capabilities. Mechanistically, WDR5 promotes cell growth by increasing ribosomal gene expression and translation efficiency in a KMT2-independent manner. Consistently, pharmacological inhibition or degradation of WDR5 impedes cellular translation rate and the clonogenic ability of breast cancer cells. Furthermore, a combination of WDR5 targeting with mTOR inhibitors leads to potent suppression of translation and proliferation of breast cancer cells. These results reveal novel therapeutic strategies to treat metastatic breast cancer.

Tumor DNA Mutations From Intraparenchymal Brain Metastases Are Detectable in CSF

Discordant responses between brain metastases and extracranial tumors can arise from branched tumor evolution, underscoring the importance of profiling mutations to optimize therapy. However, the morbidity of brain biopsies limits their use. We investigated whether cell-free DNA (cfDNA) in CSF could serve as an effective surrogate marker for genomic profiling of intraparenchymal (IP) brain metastases.

METHODS

CSF and blood were collected simultaneously from patients with progressive brain metastases undergoing a craniotomy or lumbar puncture. Mutations in both biofluids were measured using an error-suppressed deep sequencing method previously published by our group. Forty-three regions of 24 cancer-associated genes were assayed.

RESULTS

This study enrolled 14 patients with either IP brain metastases (n = 12) or cytology-positive leptomeningeal disease (LMD, n = 2) and two controls with normal pressure hydrocephalus. Primary cancer types were lung, melanoma, renal cell, and colorectal. cfDNA was measurable in all sixteen samples of CSF. Cancer-associated mutations were found in the CSF of ten patients (eight with IP [67%] and two with LMD [100%]) and plasma of five patients (five with IP [42%] and none with LMD). All patients with plasma cfDNA had extracranial tumors. Among the five patients in the cohort who also had mutation data from time-matched brain metastasis tissue, four patients (80%) had matching mutations detected in CSF and brain, whereas only one patient (20%) had matching mutations detected in plasma and brain.

CONCLUSION

The detection of mutational DNA in CSF is not restricted to LMD and was found in two thirds of patients with IP brain metastases in our cohort. Analysis of CSF can be a viable alternative to biopsy for detection of somatic mutations in brain metastases.

35. EVALUATING CSF CIRCULATING TUMOR DNA IN INTRAPARENCHYMAL BRAIN METASTASIS

INTRODUCTION

Discordant response between brain and systemic metastases occur in patients receiving targeted therapies and repeat tumor profiling of the progressing site could guide further therapy. We propose that circulating tumor DNA (ctDNA) might be detectable in the cerebrospinal fluid (CSF) and reflective of the genetic profile of intraparenchymal brain metastases.

METHODS

Patients with brain metastases undergoing a craniotomy or lumbar puncture were enrolled between July 2018 to April 2019 under an IRB-approved protocol. CSF and blood were collected simultaneously. Cell-free DNA (cfDNA) were extracted and ctDNA were identified and quantified using an Error-Suppressed Deep Sequencing method previously published by our group. Forty-three mutation-prone regions of 24 cancer-associated genes were assayed, and the allelic fractions were calculated against wild-type sequence counts.

RESULTS

Sixteen patients were enrolled in this study - 12 patients with intraparenchymal brain metastases, two patients with CSF cytology-positive leptomeningeal disease (LMD) and 2 patients with normal pressure hydrocephalus (NPH) as controls. Primary cancer types were lung (n=10), melanoma (n=2), renal cell (n=1) and colorectal (n=1) cancers. cfDNA was found in all sixteen samples of CSF. CSF ctDNA were found in eight patients (67%) and plasma ctDNA were only found in five patients (42%) with intraparenchymal tumors. In six patients with additional time-matched brain metastasis tissue, four were found to have congruent mutations in the CSF, while only one harbored such mutation in the plasma.

DISCUSSION

Analysis of CSF can be a viable alternative to obtaining brain metastasis tissue for DNA profiling in the detection of novel and resistance mutations. The presence CSF ctDNA is not restricted to LMD and were isolated from two-thirds of patients with intraparenchymal disease in our cohort. Furthermore, CSF remains a better source than plasma for the detection of ctDNA across multiple brain metastases tumor subtypes.

Abstract 4552: BMX-Seq as a new resource for deciphering the transcriptomic hallmarks of tumor plasticity and stromal interactions in brain metastasis

Purpose: Brain metastasis remains a major site of relapse for several cancer types. However, the molecular mechanisms of brain metastasis are largely unknown given the complex relationship between tumor cells and the surrounding brain tumor microenvironment (TME). To better characterize the tumor-stromal relationship in the context of brain metastasis, we have developed a Brain Metastatic RNA-Sequencing (BMX-Seq) approach, which leverages xenograft models and can distinguish between the transcriptomes of human tumor and mouse stroma gene expression in vivo. This resource provides an extensive molecular portrait of the co-adaptation of brain metastasis with the brain TME.

Methods: Following intra-arterial injection of the human, lung adenocarcinoma (LUAD), H2030-BrM3 cell model into athymic mice, metastatic brain tumors were macrodisasected, flash frozen and RNA extracted. Healthy brain regions, subcutaneous tumors and H2030-BrM3 cells grown in monolayer were harvested in parallel. Our BMX-Seq pipeline was engineered to analyze bulk xenograft tissue, which includes tumor lesions as well as surrounding stromal tissue. Species-specific Taqman primers and immunofluorescent (IF) staining were used to validate our BMX-Seq results. Models of melanoma and breast cancer brain metastasis were also included in this study.

Summary: In comparing the transcriptomic profiles of tumors grown in the brain as compared to other sites, we identify shifts in epithelial and neuronal-like gene expression programs in malignant cells and show such trends are reversible once tumor cells are removed from the brain TME. Genes involved in WNT signaling and cell projection were also upregulated across melanoma, lung and breast cancer types when cells were grown in the brain versus other sites. In describing the neuroinflammatory response of stromal regions directly surrounding brain lesions, our BMX-Seq analysis revealed increased expression of astrocyte and microglial enriched transcripts. We then utilized IF to confirm the elevated density of both of these cell types in areas directly surrounding and infiltrating tumor regions. We also detect significantly induced expression of stromal TIM3 in areas surrounding tumor lesions and in a model system devoid of T-Cells. Follow-up work revealed TIM3 is largely expressed and induced on tumor-associated macrophages (including microglia) within the tumor region, and we further validate such results in a syngeneic model system as well as in human, brain tissue.

Conclusions: We have developed a highly sensitive RNA-sequencing based approach that can accurately map the transcriptomic adaptation of brain metastatic tumor cells and the surrounding brain TME. We believe these data may serve as an invaluable resource to guide future discovery in CNS metastases.

Citation Format: Emily Wingrove, Zongzhi Z. Liu, Don X. Nguyen, Anna Arnal-Estape, Kiran D. Patel, Mary-Ann Melnick, Katerina Politi, Manuel Valiente, Harriet M. Kluger, Veronica L. Chiang. BMX-Seq as a new resource for deciphering the transcriptomic hallmarks of tumor plasticity and stromal interactions in brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4552.

Abstract 1821: Sympathetic nerves regulate a metabolic switch promoting angiogenesis through adrenergic signaling in prostate cancer

Nerves pattern the vasculature during development and regeneration. Recent studies have shown that the sympathetic nervous system (SNS) is coopted to promote carcinogenesis, and that depletion of SNS β-adrenergic receptors (βARs) in the prostate stromal compartment inhibits tumor growth. As the vasculature is in direct contact with the SNS, and regulates tumor glucose and oxygen delivery, we aimed to identify the stromal populations that mediate SNS signaling and the mechanisms by which loss of βAR signaling inhibits prostate cancer progression. In vivo xenograft tumor growth was measured in Adrb2-/-; Adrb3-/- mice using an orthotopic PC3-luciferase model. Prostate cancer progression in the transgenic autochthonous HI-myc model was assessed after conditional Adrb2 deletion in stromal populations by intercrossing Adrb2fl/fl line to stromal Cre lines. Metabolism was measured ex vivo by flow quantification of the lipophilic cationic dye TMRE whose accumulation reflects mitochondrial membrane potential, and by NADH autofluorescence under UV excitation. In vitro oxidative phosphorylation and glycolytic flux were measured in primary prostate endothelial cells (VeraVec) using the Seahorse bioanalyzer and targeted gas chromatography-mass spectrometry (GC/MS). Deletion of the SNS βAR neural receptors in the microenvironment synergized to arrest exponential tumor growth. Imaging the tumor vasculature revealed a defect in vessel branching, a phenotype also observed after chemical sympathectomy, suggesting altered angiogenesis in the absence of βAR stimulation. Histology revealed an increase in vascular innervation and density during the transition from low to high grade pre-neoplastic PIN. Conditional Adrb2 deletion (Adrb2cKO) in endothelial cells (ECs), but not myeloid cells or pericytes, not only inhibited angiogenesis, but also reduced disease progression throughout all histopathological cancer stages. Transcriptome analysis of flow isolated Adrb2cKO ECs suggested an increase in oxidative metabolism and upregulation of mitochondrial Coa6. Ex vivo analysis of ECs revealed a metabolic switch during the low to high grade PIN transition, and this switch was inhibited by Adrb2cKO. Further in vitro characterization by Adrb2 knockdown revealed a metabolic shift in ECs to oxidative phosphorylation, which was mediated by Coa6 upregulation. As Coa6 cooperates with Cox10 in respiratory complex IV assembly, conditional co-deletion of Adrb2 and Cox10 in the HI-myc mouse rescued aerobic glycolysis, angiogenesis, and cancer progression. Our data thus demonstrates that the SNS mediates a pro-angiogenic switch during the early stages of prostate carcinogenesis. Moreover, we identified ECs as SNS stromal targets, and that abrogation of βAR signaling inhibits the angio-metabolic switch and delays prostate cancer progression, suggesting a novel therapeutic target for prostate cancer treatment.

Citation Format: Ali Zahalka, Anna Arnal-Estape, Maria Maryanovich, Fumio Nakahara, Cristian Cruz, Paul S. Frenette. Sympathetic nerves regulate a metabolic switch promoting angiogenesis through adrenergic signaling in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1821. doi:10.1158/1538-7445.AM2017-1821

Tumor-stroma interactions a trademark for metastasis

AIMS

We aimed to unravel genes that are significantly associated with metastasis in order to identify functions that support disseminated disease.

METHODS AND RESULTS

We identify genes associated with metastasis and verify its clinical correlations using publicly available primary tumor expression profile data sets. We used facilities in R and Bioconductor (GSEA). Specific data structures and functions were imported. Our results show that genes associated with metastasis in primary tumor enriched for pathways associated with immune infiltration or cytokine-cytokine receptor interaction. As an example, we focus on the enrichment of TGFBR2 and TGF|X A set of communication tools capital for tumor-stroma interactions that define metastasis to the lung and support bone colonization.

CONCLUSIONS

We showed that tumor-stroma communication through cytokine-cytokine receptor interaction pathway is selected in primary tumors with high risk of relapse. High levels of these factors support systemic instigation of the far metastatic nest as well as local metastatic-specific functions that provide solid ground for metastatic development.