miR614 Expression Enhances Breast Cancer Cell Motility

Using a data driven analysis of a high-content screen, we have uncovered new regulators of epithelial-to-mesenchymal transition (EMT) induced cell migration. Our results suggest that increased expression of miR614 can alter cell intrinsic gene expression to enhance single cell and collective migration in multiple contexts. Interestingly, miR614 specifically increased the expression of the EMT transcription factor Slug while not altering existing epithelial character or inducing other canonical EMT regulatory factors. Analysis of two different cell lines identified a set of genes whose expression is altered by the miR614 through direct and indirect mechanisms. Prioritization driven by functional testing of 25 of the miR614 suppressed genes uncovered the mitochondrial small GTPase Miro1 and the transmembrane protein TAPT1 as miR614 suppressed genes that inhibit migration. Notably, the suppression of either Miro1 or TAPT1 was sufficient to increase Slug expression and the rate of cell migration. Importantly, reduced TAPT1 expression correlated with an increased risk of relapse in breast cancer patients. Together, our results reveal how increased miR614 expression and the suppression of TAPT1 and Miro1 modulate the EMT state and migratory properties of breast cancer cells.

Machine learning predicts stem cell transplant response in severe scleroderma

ObjectiveThe Scleroderma: Cyclophosphamide or Transplantation (SCOT) trial demonstrated clinical benefit of haematopoietic stem cell transplant (HSCT) compared with cyclophosphamide (CYC). We mapped PBC (peripheral blood cell) samples from the SCOT clinical trial to scleroderma intrinsic subsets and tested the hypothesis that they predict long-term response to HSCT.MethodsWe analysed gene expression from PBCs of SCOT participants to identify differential treatment response. PBC gene expression data were generated from 63 SCOT participants at baseline and follow-up timepoints. Participants who completed treatment protocol were stratified by intrinsic gene expression subsets at baseline, evaluated for event-free survival (EFS) and analysed for differentially expressed genes (DEGs).ResultsParticipants from the fibroproliferative subset on HSCT experienced significant improvement in EFS compared with fibroproliferative participants on CYC (p=0.0091). In contrast, EFS did not significantly differ between CYC and HSCT arms for the participants from the normal-like subset (p=0.77) or the inflammatory subset (p=0.1). At each timepoint, we observed considerably more DEGs in HSCT arm compared with CYC arm with HSCT arm showing significant changes in immune response pathways.ConclusionsParticipants from the fibroproliferative subset showed the most significant long-term benefit from HSCT compared with CYC. This study suggests that intrinsic subset stratification of patients may be used to identify patients with SSc who receive significant benefit from HSCT.

Immune- and tumor-intrinsic gene expression profiles of response or resistance to tislelizumab as monotherapy or in combination with chemotherapy in non-small cell lung cancer (NSCLC).

e15258 Background: Tislelizumab, an anti-PD-1 monoclonal antibody, showed clinical benefit for patients (pts) with NSCLC alone (NCT02407990, CTR20160872) and in combination with chemotherapy (NCT03432598). Gene expression profiles (GEP) associated with response and resistance to tislelizumab in these studies were assessed. Methods: The GEP of baseline tumor samples from 59 nonsquamous (NSQ) and 42 squamous (SQ) NSCLC pts treated with tislelizumab monotherapy (mono) as ≥1L treatment, and 16 NSQ and 21 SQ pts treated with tislelizumab plus chemotherapy (combo) as 1L treatment were assessed using the 1392-gene HTG GEP EdgeSeq panel. NSQ and SQ cohorts were analyzed separately due to distinct GEP features shown by PCA and t-SNE clustering. Results: Tislelizumab mono and combo showed antitumor activity in NSCLC (Table). In 80 biomarker-evaluable samples, inflamed tumor signatures (inflammatory GEP; antigen presentation GEP) were associated with longer overall survival (log-rank test, NSQ mono: P=0.04, 0.003; NSQ combo: P=0.05, 0.02; SQ combo: P=0.06, 0.06). Monotherapy non-responders (NRs) were clustered into 2 subgroups (NR1, NR2) with distinct GEPs. Compared with responders, NR1 had proliferation signatures (elevated cell cycle [CC] and DNA repair) in both NSQ ( P=0.2, 0.02) and SQ ( P=0.03, 0.4) cohorts, trending toward low inflamed tumor signatures. In NR pts receiving combo, CC and DNA repair signatures were not enriched, and high CC and DNA repair scores were observed in some SQ combo responders versus NRs ( P=0.2, 0.02). NR2 had higher M2 macrophage and Treg cell signatures versus responders in both NSQ and SQ mono, despite high inflamed tumor and low proliferation signatures. NR2 also had increased expression of genes related to immune regulation and angiogenesis, including PIK3CD, CCR2, CD244, IRAK3, and MAP4K1 ( P<0.05) in NSQ, and PIK3CD, CCR2, CD40, CD163, MMP12, VEGFC, and TEK ( P<0.05) in SQ. Conclusions: Clinical benefit in pts with NSCLC receiving tislelizumab (mono or combo) was associated with high inflamed tumor signatures, while elevated immune suppressive cell signatures may indicate resistance. High proliferation signatures were associated with resistance to monotherapy, but not to combination therapy. Both immune- and tumor-intrinsic factors may be considered for validation in future clinical trials. [Table: see text]

Imprinted Cdkn1c genomic locus cell-autonomously promotes cell survival in cerebral cortex development

The cyclin-dependent kinase inhibitor p57KIP2 is encoded by the imprinted Cdkn1c locus, exhibits maternal expression, and is essential for cerebral cortex development. How Cdkn1c regulates corticogenesis is however not clear. To this end we employ Mosaic Analysis with Double Markers (MADM) technology to genetically dissect Cdkn1c gene function in corticogenesis at single cell resolution. We find that the previously described growth-inhibitory Cdkn1c function is a non-cell-autonomous one, acting on the whole organism. In contrast we reveal a growth-promoting cell-autonomous Cdkn1c function which at the mechanistic level mediates radial glial progenitor cell and nascent projection neuron survival. Strikingly, the growth-promoting function of Cdkn1c is highly dosage sensitive but not subject to genomic imprinting. Collectively, our results suggest that the Cdkn1c locus regulates cortical development through distinct cell-autonomous and non-cell-autonomous mechanisms. More generally, our study highlights the importance to probe the relative contributions of cell intrinsic gene function and tissue-wide mechanisms to the overall phenotype.

GENE-55. GENE EXPRESSION SIGNATURE ASSOCIATED WITH AGGRESSIVE GLIOBLASTOMA GROWTH IS ENRICHED IN CHROMATIN MODIFICATION AND STEMNESS TRANSCRIPTIONAL REGULATION PROGRAMS

Prognosis of patients diagnosed with IDHwt glioblastoma is influenced by known clinical and demographic factors, and likely by physiological characteristics. Our goal is to determine tumor-intrinsic gene expression signatures associated with aggressive tumor growth in patient-derived xenografts (PDXs). Cancer stem cell (CSC) lines established from 10 IDHwt glioblastoma tumors were implanted orthotopically in cohorts of 10 to 15 nude mice (3x10E5 viable cells/mouse), for development of PDX under uniform conditions. Mice were monitored and sacrificed when symptomatic. Five PDX lines, presenting median survival of 29 to 59 days were classified as short (S) survivors, and 5 lines with median survival between 111 and 134 days as long (L) survivors. RNA was isolated from terminal PDX tumors (n=3/line) and sequenced using Illumina HiSeq 2000. Differential gene expression analysis between tumors in S and L survival groups was conducted using the lmFit and eBayes, and genes were ranked by Benjamini-Hochberg adjusted P-values, set to adj.p< 0.05, resulting in 1663 genes upregulated and 1539 genes downregulated in the aggressive S group. Gene ontology analysis was performed using Metacore (Clarivate Analytics) and Metascape (http://metascape.org). Chromatin modification was significantly enriched in the aggressive tumor group (Metacore, p= 1x 10–12). Remarkably, 40% (654/1663) of the genes upregulated in the aggressive PDX tumors were co-expressed with an epigenetic master regulator in the TCGA glioblastoma RNAseq dataset (cBio Portal, q< 10E-15), and this subset was also highly enriched in chromatin modification, stemness transcriptional regulation and DNA repair (q=10E-45 to q=10E-13). These results indicate that novel host-independent prognostic gene expression signatures can be derived from the PDX models and underline the potential of epigenetic regulators as therapeutic target for aggressive glioblastomas. Our results further indicate that these models are suitable for testing a new generation of epigenetic drugs currently in pre-clinical and clinical development.

Spatiotemporally controlled genetic perturbation for efficient large-scale studies of cell non-autonomous effects

Studies in genetic model organisms have revealed much about the development and pathology of complex tissues. Most have focused on cell-intrinsic gene functions and mechanisms. Much less is known about how transformed, or otherwise functionally disrupted, cells interact with healthy ones toward a favorable or pathological outcome. This is largely due to technical limitations. We developed new genetic tools in Drosophila melanogaster that permit efficient multiplexed gain- and loss-of-function genetic perturbations with separable spatial and temporal control. Importantly, our novel tool-set is independent of the commonly used GAL4/UAS system, freeing the latter for additional, non-autonomous, genetic manipulations; and is built into a single strain, allowing one-generation interrogation of non-autonomous effects. Altogether, our design opens up efficient genome-wide screens on any deleterious phenotype, once plasmid or genome engineering is used to place the desired miRNA(s) or ORF(s) into our genotype. Specifically, we developed tools to study extrinsic effects on neural tumor growth but the strategy presented has endless applications within and beyond neurobiology, and in other model organisms.

Spatiotemporally controlled genetic perturbation for efficient large-scale studies of cell non-autonomous effects

Studies in genetic model organisms have revealed much about the development and pathology of complex tissues. Most have focused on cell-intrinsic gene functions and mechanisms. Much less is known about how transformed, or otherwise functionally disrupted, cells interact with healthy ones towards a favorable or pathological outcome. This is largely due to technical limitations. We developed new genetic tools in Drosophila melanogaster that permit efficient multiplexed gain- and loss-of-function genetic perturbations with separable spatial and temporal control. Importantly, our novel tool-set is independent of the commonly used GAL4/UAS system, freeing the latter for additional, non-autonomous, genetic manipulations; and is built into a single strain, allowing one-generation interrogation of non-autonomous effects. Altogether, our design opens up efficient genome-wide screens on any deleterious phenotype. Specifically, we developed tools to study extrinsic effects on neural tumor growth but the strategy presented has endless applications within and beyond neurobiology, and in other model organisms.Impact statementA novel genetic strategy for induction of reproducible neural tumors (or any other deleterious phenotype) in a single Drosophila stock (applicable to other organisms).