An inflamed tumor cell subpopulation promotes chemotherapy resistance in triple negative breast cancer [scRNA-Seq]
Ontology highlight
ABSTRACT: Individual cancers are composed of heterogeneous tumor cells with distinct phenotypes and genotypes, with triple negative breast cancers (TNBC) demonstrating the most heterogeneity among breast cancer types. Variability in transcriptional phenotypes could meaningfully limit the efficacy of monotherapies and fuel drug resistance, although to an unknown extent. To determine if transcriptional differences between tumor cells lead to differential drug responses we performed single cell RNA-seq on cell line and PDX models of breast cancer revealing cell subpopulations in states associated with resistance to standard-of-care therapies. We found that TNBC models contained a subpopulation in an inflamed cellular state, often also present in human breast cancer samples. Inflamed cells display evidence of heightened cGAS/STING signaling which we demonstrate is sufficient to cause tumor cell resistance to chemotherapy. Accordingly, inflamed cells were enriched in human tumors taken after neoadjuvant chemotherapy and associated with early recurrence, highlighting the potential for diverse tumor cell states to promote drug resistance.
Project description:Individual cancers are composed of heterogeneous tumor cells with distinct phenotypes and genotypes, with triple negative breast cancers (TNBC) demonstrating the most heterogeneity among breast cancer types. Variability in transcriptional phenotypes could meaningfully limit the efficacy of monotherapies and fuel drug resistance, although to an unknown extent. To determine if transcriptional differences between tumor cells lead to differential drug responses we performed single cell RNA-seq on cell line and PDX models of breast cancer revealing cell subpopulations in states associated with resistance to standard-of-care therapies. We found that TNBC models contained a subpopulation in an inflamed cellular state, often also present in human breast cancer samples. Inflamed cells display evidence of heightened cGAS/STING signaling which we demonstrate is sufficient to cause tumor cell resistance to chemotherapy. Accordingly, inflamed cells were enriched in human tumors taken after neoadjuvant chemotherapy and associated with early recurrence, highlighting the potential for diverse tumor cell states to promote drug resistance.
Project description:<p>Overcoming resistance to chemotherapies remains a major unmet need for cancers such as triple negative breast cancer (TNBC). Therefore, mechanistic studies to provide insight for drug development are urgently needed to overcome TNBC therapy resistance. Recently, an important role of fatty acid β-Oxidation (FAO) in chemoresistance has been shown. But how FAO might mitigate tumor cell apoptosis by chemotherapy is unclear. Here, we show that elevated FAO activates STAT3 by acetylation via elevated acetyl-CoA. Acetylated STAT3 upregulates expression of long-chain acyl-CoA synthetase 4 (ACSL4), resulting in increased phospholipid synthesis. Elevating phospholipids in mitochondrial membranes leads to heightened mitochondrial integrity, which in turn overcomes chemotherapy-induced tumor cell apoptosis. Conversely, in both cultured tumor cells and xenograft tumors, enhanced cancer cell apoptosis by inhibiting ASCL4 or specifically targeting acetylated-STAT3 is associated with a reduction in phospholipids within mitochondrial membranes. This study demonstrates a critical mechanism underlying tumor cell chemoresistance.</p>
Project description:Chemotherapy is the mainstay treatment stragety for triple negative breast cancer (TNBC). However resistance to chemotherapy is common, leading to disease progression and death. Strategies that improve chemotherapy efficacy has the potential to reduce TNBC mortality. In this research, we demonstrated that the pan-PI3K inhibitor copanlisib, which is already in clinic to treat hematologic malignancies, enhanced the cytotoxicity of eribulin, a common chemotherapy used to treat taxane-resistant TNBC, in a panel of TNBC patient-derived xenograft (PDX) models. The improved tumor growth inhibition was irrespective of PI3K pathway alteration and was corroborated by the enhanced apoptotic induction observed in PDX tumors post combination therapy compared to each drug alone. The combination therapy inhibited eribulin-induced PI3K pathway activation, providing an underlying mechanism of action for its enhanced anti-tumor effect. Based on these results, a Phase I/II trial of this combination in patients with metastatic TNBC was initiated and is ongoing.
Project description:Overcoming resistance to chemotherapies remains a major unmet need for cancers such as triple negative breast cancer (TNBC). Therefore, mechanistic studies to provide insight for drug development are urgently needed to overcome TNBC therapy resistance. Recently, an important role of fatty acid β-Oxidation (FAO) in chemoresistance has been shown. But how FAO might mitigate tumor cell apoptosis by chemotherapy is unclearknown. Here, we show that elevated FAO activates STAT3 by acetylation via elevated acetyl-CoA. Acetylated STAT3 upregulates expression of long-chain acyl-CoA synthetase 4 (ACSL4), resulting in increased phospholipid synthesis. Elevating phospholipids in mitochondrial membranes leads to heightened mitochondrial integrity, which in turn overcomes chemotherapy-induced tumor cell apoptosis. Conversely, in both cultured tumor cells and xenograft tumors, enhanced cancer cell apoptosis by inhibiting ASCL4 or specifically targeting acetylated-STAT3 is associated with a reduction in phospholipids within mitochondrial membranes. This study demonstrates a critical mechanism underlying tumor cell chemoresistance.
Project description:Overcoming resistance to chemotherapies remains a major unmet need for cancers such as triple negative breast cancer (TNBC). Therefore, mechanistic studies to provide insight for drug development are urgently needed to overcome TNBC therapy resistance. Recently, an important role of fatty acid β-Oxidation (FAO) in chemoresistance has been shown. But how FAO might mitigate tumor cell apoptosis by chemotherapy is unclearknown. Here, we show that elevated FAO activates STAT3 by acetylation via elevated acetyl-CoA. Acetylated STAT3 upregulates expression of long-chain acyl-CoA synthetase 4 (ACSL4), resulting in increased phospholipid synthesis. Elevating phospholipids in mitochondrial membranes leads to heightened mitochondrial integrity, which in turn overcomes chemotherapy-induced tumor cell apoptosis. Conversely, in both cultured tumor cells and xenograft tumors, enhanced cancer cell apoptosis by inhibiting ASCL4 or specifically targeting acetylated-STAT3 is associated with a reduction in phospholipids within mitochondrial membranes. This study demonstrates a critical mechanism underlying tumor cell chemoresistance.
Project description:Triple negative breast cancer (TNBC) is a heterogeneous and clinically aggressive disease for which there is no targeted therapy. Here we report the preferential and high sensitivity of TNBCs to BET bromodomain inhibitors such as JQ1 manifested by cell cycle arrest in early G1, apoptosis, and induction of markers of luminal epithelial differentiation in vitro and in vivo. The sensitivity of TNBC and other tumor types to BET inhibition establishes a rationale for clinical investigation, and a motivation to understand mechanisms of resistance. After engendering acquired resistance to BET inhibition in previously sensitive TNBCs, we utilized integrative approaches to identify a unique mechanism of epigenomic resistance to this epigenetic therapy. Resistant cells remain dependent on BRD4, confirmed by RNA interference. However, TNBC cells adapt to BET bromodomain inhibition by re-recruitment of unmutated BRD4 to super-enhancers, now in a bromodomain-independent manner. Proteomic studies of resistant TNBC identify hyper-phosphorylation of BRD4 and strong association with MED1. Together, these studies provide a rationale for BET inhibition in TNBC and argue for combination strategies to anticipate clinical drug resistance. ChIP-seq in parental and JQ1 resistant triple negative breast cancer (TNBC) in response to DMSO or JQ1 treatment
Project description:Triple negative breast cancer (TNBC) is a heterogeneous and clinically aggressive disease for which there is no targeted therapy. Here we report the preferential and high sensitivity of TNBCs to BET bromodomain inhibitors such as JQ1 manifested by cell cycle arrest in early G1, apoptosis, and induction of markers of luminal epithelial differentiation in vitro and in vivo. The sensitivity of TNBC and other tumor types to BET inhibition establishes a rationale for clinical investigation, and a motivation to understand mechanisms of resistance. After engendering acquired resistance to BET inhibition in previously sensitive TNBCs, we utilized integrative approaches to identify a unique mechanism of epigenomic resistance to this epigenetic therapy. Resistant cells remain dependent on BRD4, confirmed by RNA interference. However, TNBC cells adapt to BET bromodomain inhibition by re-recruitment of unmutated BRD4 to super-enhancers, now in a bromodomain-independent manner. Proteomic studies of resistant TNBC identify hyper-phosphorylation of BRD4 and strong association with MED1. Together, these studies provide a rationale for BET inhibition in TNBC and argue for combination strategies to anticipate clinical drug resistance. Chem-Seq in parental and JQ1 resistant triple negative breast cancer (TNBC)
Project description:Triple negative breast cancer (TNBC) is a heterogeneous and clinically aggressive disease for which there is no targeted therapy. Here we report the preferential and high sensitivity of TNBCs to BET bromodomain inhibitors such as JQ1 manifested by cell cycle arrest in early G1, apoptosis, and induction of markers of luminal epithelial differentiation in vitro and in vivo. The sensitivity of TNBC and other tumor types to BET inhibition establishes a rationale for clinical investigation, and a motivation to understand mechanisms of resistance. After engendering acquired resistance to BET inhibition in previously sensitive TNBCs, we utilized integrative approaches to identify a unique mechanism of epigenomic resistance to this epigenetic therapy. Resistant cells remain dependent on BRD4, confirmed by RNA interference. However, TNBC cells adapt to BET bromodomain inhibition by re-recruitment of unmutated BRD4 to super-enhancers, now in a bromodomain-independent manner. Proteomic studies of resistant TNBC identify hyper-phosphorylation of BRD4 and strong association with MED1. Together, these studies provide a rationale for BET inhibition in TNBC and argue for combination strategies to anticipate clinical drug resistance. RNA-Seq in parental and JQ1 resistant triple negative breast cancer (TNBC) in response to DMSO or JQ1 treatment over time
Project description:By coupling PDX and cell surface marker screening technologies, we have identified distinct tumor cell sub-populations that are associated with tumor resistance to chemotherapy. In the majority of relapsed tumors, the percentage of the marker-positive cells shifted back to pretreatment levels. SSEA4 is one of the cell surface molecules tested that could distinguish enriched residual tumor cells in all the different TNBC PDX models analyzed. The expression of SSEA4 is associated with tumor resistance to chemotherapy and SSEA4+ cells show increased gene expression of genes involved in response to toxins, cellular import/export, cell migration and EMT. The dataset comprises four different sample groups including SSEA4- and SSEA4+ cell fractions isolated from mouse xenografts of human breast cancer cells. Two technical replicates were generated for each cell fraction. Microarray analysis was performed on the Agilent Whole Human Genome Oligo Microarray 8x60K (v2) platform.