Project description:Small cell lung cancer (SCLC) is a neuroendocrine tumor treated clinically as a single disease with poor outcomes. Distinct SCLC molecular subtypes have been defined based on expression of lineage-related transcription factors: ASCL1, NEUROD1, POU2F3 or YAP1, but their origins remain unknown. We developed an in vitro model of MYC-driven SCLC tumor cell progression, and performed a time-series analysis of single-cell transcriptome profiling to reveal that MYC drives the dynamic evolution of SCLC subtypes. Analyses of these single-cell RNA seq data reveal that MYC promotes a temporal shift from an ASCL1-to-NEUROD1-to-YAP1+ state from a neuroendocrine cell of origin. MYC activates Notch signaling to dedifferentiate tumor cells to non-neuroendocrine fates. Additional single-cell RNA sequencing of 4RPM tumors reveal individual tumors to consist of cells at nearly every stage of RPM tumor evolution modeled in vitro. With the single-cell RNA sequencing of this human SCLC liver biopsy, along with IHC on a panel of 21 human biopsies, we show that human SCLC exhibits intratumoral SCLC subtype heterogeneity, suggesting this dynamic evolution occurs in patient tumors. Together, these single-cell RNA sequencing data support our conclusions that genetics, cell of origin, and tumor cell plasticity determine SCLC subtype.
Project description:Distinct SCLC molecular subtypes have been defined based on expression of lineage-related transcription factors: ASCL1, NEUROD1, POU2F3 or YAP1, but their origins remain unknown. We perform bulk RNA-sequencing on SCLC tumors from RPM and Rb1/Trp53/Rbl2 (RPR2) GEMMs, initiated by CGRP-Cre, to complement time-series analysis of single-cell transcriptome profiling and reveal that MYC drives the dynamic evolution of SCLC subtypes. MYC promotes a temporal shift from an ASCL1-to-NEUROD1-to-YAP1+ state from a neuroendocrine cell of origin. MYC activates Notch signaling to dedifferentiate tumor cells to non-neuroendocrine fates. Sequenced RPM tumors driven by MycT58A, in comparison to RPR2 tumors associated with high Mycl, have increased intratumoral subtype heterogeneity by bulk-seq, single-cell RNA seq, and IHC compared to RPR2 tumors. In RPM tumors with high MYC, tumors are able to proceed to non-NE subtypes resembling the NEUROD1+ and YAP1+ human SCLC subtypes. These findings support our overall conclusions that genetics, cell of origin, and tumor cell plasticity determine SCLC subtype.
Project description:Distinct SCLC molecular subtypes have been defined based on expression of lineage-related transcription factors: ASCL1, NEUROD1, POU2F3 or YAP1, but their origins remain unknown. To study transcriptional dynamics of MYC-driven tumor evolution and compare transcriptional states to human SCLC tumors, we performed bulk and single-cell RNA-sequencing on various timepoints of Rb1/Trp53/MycT58A (RPM) tumor cells (from Ad-Cgrp-Cre infected mice) as they progress in culture, and on RPM bulk tumors. Here, to complement these analyses we performed ~30X whole-genome sequencing (WGS) of early (day 4) and late (day 23) time-point RPM tumor cells from culture, along with a matching normal blood control to confirm complete loss of expected regions of Rb1 and Trp53. WGS analyses revealed no detectable copy number variations (CNVs), and SNV analysis suggests that minimal clonal and subclonal evolution occurs in vitro. Together, these data ultimately reveal that MYC drives the dynamic evolution of SCLC subtypes. We find that MYC promotes a temporal shift from an ASCL1-to-NEUROD1-to-YAP1+ state from a neuroendocrine cell of origin. MYC activates Notch signaling to dedifferentiate tumor cells to non-neuroendocrine fates. These findings support our overall conclusions that genetics, cell of origin, and tumor cell plasticity determine SCLC subtype.
Project description:Distinct SCLC molecular subtypes have been defined based on expression of lineage-related transcription factors: ASCL1, NEUROD1, POU2F3 or YAP1, but their origins remain unknown. To study transcriptional dynamics of MYC-driven tumor evolution and compare transcriptional states to human SCLC tumors, we performed bulk RNA-sequencing on various timepoints of Rb1/Trp53/MycT58A (RPM) tumor cells (from Ad-Cgrp-Cre infected mice) as they progress in culture. These bulk RNA-seq data of the RPM time-series cells complement time-series analysis of single-cell transcriptome profiling of similar timepoints and ultimately reveal that MYC drives the dynamic evolution of SCLC subtypes. We find that MYC promotes a temporal shift from an ASCL1-to-NEUROD1-to-YAP1+ state from a neuroendocrine cell of origin. MYC activates Notch signaling to dedifferentiate tumor cells to non-neuroendocrine fates. These findings support our overall conclusions that genetics, cell of origin, and tumor cell plasticity determine SCLC subtype.
Project description:Small cell lung cancer (SCLC) is a neuroendocrine tumor treated clinically as a single disease with poor outcomes. Distinct SCLC molecular subtypes have been defined based on expression of lineage-related transcription factors: ASCL1, NEUROD1, POU2F3 or YAP1, but their origins remain unknown. Here, we develop an in vitro model of MYC-driven SCLC tumor cell progression and perform a time-series analysis of single-cell transcriptome profiling to reveal that MYC drives the dynamic evolution of SCLC subtypes. Analyses of these single-cell RNA seq data reveal that MYC promotes a temporal shift from an Ascl1-to-Neurod1-to-Yap1+ state from a neuroendocrine cell of origin. They also support our findings that MYC activates Notch signaling to dedifferentiate tumor cells to non-neuroendocrine fates. Additional single-cell RNA sequencing of 4 bulk Rb1/Trp53/MycT58A (RPM) tumors reveal individual tumors to consist of cells at nearly every stage of RPM tumor evolution modeled in vitro. Together, these single-cell RNA sequencing data place 3 of 4 SCLC subtypes on a defined trajectory and suggest that genetics, cell of origin, and tumor cell plasticity determine SCLC subtype.
Project description:Small cell lung cancer (SCLC) is an aggressive subtype of lung cancer whose biology is still poorly understood. Using a multiplexed inhibitor beads assay, we identified active kinases in SCLC. Among those, we found that PKA is critical for the expansion of SCLC in culture and in vivo. PKA promotes the neuroendocrine epithelial state associated with SCLC tumor-initiating cells. Phosphoproteomics analyses identify ~200 PKA substrates and show that PKA controls multiple facets of SCLC growth. Notably, the PP2A phosphatase counteracts the oncogenic effects of PKA, and PP2A activators inhibit SCLC as single agents and with chemotherapy. Our data uncover key signaling networks in SCLC and indicate that targeting the PKA/PP2A pathway may help inhibit this lethal neuroendocrine cancer.
Project description:Small Cell Lung Cancer (SCLC) is an aggressive neuroendocrine malignancy with a poor prognosis. Here, we focus on the neuroendocrine SCLC subtypes SCLC-A and SCLC-N, whose transcription addiction was driven by ASCL1 and NEUROD1 transcription factors which target E-box motifs to activate up to 40% of total genes, the promoters of which are maintained in a steadily open chromatin environment according to ATAC and H3K27Ac signatures. This leverage is used by the marine agent lurbinectedin, which preferentially targets the CpG islands located downstream of the transcription start site, thus arresting elongating RNAPII and promoting its degradation. This abrogates the expression of ASCL1 and NEUROD1 and of their dependent genes such as BCL2, INSM1, MYC and AURKA, which are responsible for relevant SCLC tumorigenic properties such as inhibition of apoptosis and cell survival, as well as for a part of its neuroendocrine features. In summary, we show how the transcription addiction of these cells becomes their Achilles' heel, and how this is effectively exploited by lurbinectedin as a novel and highly specific SCLC therapeutic endeavor.
Project description:Small-cell lung cancer (SCLC) is the most fatal form of lung cancer. Intra-tumoral heterogeneity, marked by neuroendocrine (NE) and non-neuroendocrine (non-NE) cell states, defines SCLC, but the drivers of SCLC plasticity are poorly understood. To map the landscape of SCLC tumor microenvironment (TME), we apply spatially resolved transcriptomics and quantitative mass spectrometry-based proteomics to metastatic SCLC tumors obtained via rapid autopsy. The phenotype and overall composition of non-malignant cells in the tumor microenvironment (TME) exhibits substantial variability, closely mirroring the tumor phenotype, suggesting TME-driven reprogramming of NE cell states. We identify cancer-associated fibroblasts (CAF) as a crucial element of SCLC TME heterogeneity, contributing to immune exclusion, and predicting exceptionally poor prognosis. Together, our work provides a comprehensive map of SCLC tumor and TME ecosystems, emphasizing their pivotal role in SCLCs adaptable nature, opening possibilities for re-programming the intercellular communications that shape SCLC tumor states.
Project description:Lineage transformation between lung cancer subtypes is a poorly understood phenomenon associated with resistance to treatment and poor patient outcomes. Here, we aimed to model this transition in order to define underlying biological mechanisms and identify potential avenues for therapeutic intervention. Small cell lung cancer (SCLC) is neuroendocrine in origin and, in contrast to non-SCLC (NSCLC), rarely contains mutations that drive the MAPK pathway. Likewise, NSCLCs that transform to SCLC concomitantly with development of therapy resistance downregulate MAPK signaling, suggesting an inverse relationship between pathway activation and lineage state. To test this, we activated MAPK in SCLC through conditional expression of mutant KRAS or EGFR, which revealed suppression of the neuroendocrine differentiation program via ERK. We found that ERK induces the expression of ETS factors, phenocopying ERK-mediated effects on transformation into the NSCLC-like phenotype. ATAC-seq demonstrated ERK-driven changes in chromatin accessibility at putative regulatory regions and global chromatin rewiring at neuroendocrine and ETS transcriptional targets. Further, induction of ETS factors as well as suppression of neuroendocrine differentiation were dependent on histone acetyltransferase activities of CBP/p300. Overall, we describe how the ERK-CBP/p300-ETS axis promotes a lineage shift between neuroendocrine and non-neuroendocrine lung cancer phenotypes and provide rationale for the disruption of this program during transformation-driven resistance to targeted therapy.
Project description:Small cell lung cancer (SCLC) tumors comprise heterogeneous mixtures of cell states, categorized into neuroendocrine (NE) and non-neuroendocrine (non-NE) transcriptional subtypes. NE to non-NE state transitions, fueled by plasticity, likely underlie adaptability to treatment and dismal survival rates. Here, we apply an archetypal analysis to model plasticity by recasting SCLC phenotypic heterogeneity through multi-task evolutionary theory. Cell line and tumor transcriptomics data fit well in a five-dimensional convex polytope whose vertices optimize tasks reminiscent of pulmonary NE cells, the SCLC normal counterparts. These tasks, supported by knowledge and experimental data, include proliferation, slithering, metabolism, secretion, and injury repair, reflecting cancer hallmarks. SCLC subtypes, either at the population or single-cell level, can be positioned in archetypal space by bulk or single-cell transcriptomics, respectively, and characterized as task specialists or multi-task generalists by the distance from archetype vertex signatures. In the archetype space, modeling single-cell plasticity as a Markovian process along an underlying state manifold indicates that task trade-offs, in response to microenvironmental perturbations or treatment, may drive cell plasticity. Stifling phenotypic transitions and plasticity may provide new targets for much-needed translational advances in SCLC.