Human Epidermal Growth Factor Receptor 2-positive (HER2⁺) breast cancer (BC) is a highly aggressive disease commonly treated with chemotherapy and anti-HER2 drugs, including trastuzumab. There is ...currently no way to predict which HER2⁺ BC patients will benefit from these treatments. Previous prognostic signatures for HER2⁺ BC were developed irrespective of the subtype or the hierarchical organization of cancer in which only a fraction of cells, tumor-initiating cells (TICs), can sustain tumor growth. Here, we used serial dilution and single-cell transplantation assays to identify MMTV-Her2/Neu mouse mammary TICs as CD24⁺:JAG1⁻ at a frequency of 2-4.5%. A 17-gene Her2-TIC-enriched signature (HTICS), generated on the basis of differentially expressed genes in TIC versus non-TIC fractions and trained on one HER2⁺ BC cohort, predicted clinical outcome on multiple independent HER2⁺ cohorts. HTICS included up-regulated genes involved in S/G2/M transition and down-regulated genes involved in immune response. Its prognostic power was independent of other predictors, stratified lymph node⁺ HER2⁺ into low and high-risk subgroups, and was specific for HER2⁺:estrogen receptor alpha-negative (ERα⁻) patients (10-y overall survival of 83.6% for HTICS⁻ and 24.0% for HTICS⁺ tumors; hazard ratio = 5.57; P = 0.002). Whereas HTICS was specific to HER2⁺:ERα⁻ tumors, a previously reported stroma-derived signature was predictive for HER2⁺ERα⁻ BC Retrospective analyses revealed that patients with HTICS⁻ HER2⁻:ERα⁻ tumors resisted chemotherapy but responded to chemotherapy plus trastuzumab. HTICS is, therefore, a powerful prognostic signature for HER2⁻:ERα⁻ BC that can be used to identify high risk patients that would benefit from anti-HER2 therapy.
Abstract
Background
SMAD1, a central mediator in TGF-β signaling, is involved in a broad range of biological activities including cell growth, apoptosis, development and immune response, and is ...implicated in diverse type of malignancies. Whether SMAD1 plays an important role in multiple myeloma (MM) pathogenesis and can serve as a therapeutic target are largely unknown.
Methods
Myeloma cell lines and primary MM samples were used. Cell culture, cytotoxicity and apoptosis assay, siRNA transfection, Western blot, RT-PCR, Soft-agar colony formation, and migration assay, Chromatin immunoprecipitation (Chip), animal xenograft model studies and statistical analysis were applied in this study.
Results
We demonstrate that SMAD1 is highly expressed in myeloma cells of MM patients with advanced stages or relapsed disease, and is associated with significantly shorter progression-free and overall survivals. Mechanistically, we show that SMAD1 is required for TGFβ-mediated proliferation in MM via an ID1/p21/p27 pathway. TGF-β also enhanced TNFα-Induced protein 8 (TNFAIP8) expression and inhibited apoptosis through SMAD1-mediated induction of NF-κB1. Accordingly, depletion of SMAD1 led to downregulation of NF-κB1 and TNFAIP8, resulting in caspase-8-induced apoptosis. In turn, inhibition of NF-κB1 suppressed SMAD1 and ID1 expression uncovering an autoregulatory loop. Dorsomorphin (DM), a SMAD1 inhibitor, exerted a dose-dependent cytotoxic effect on drug-resistant MM cells with minimal cytotoxicity to normal hematopoietic cells, and further synergized with the proteasomal-inhibitor bortezomib to effectively kill drug-resistant MM cells in vitro and in a myeloma xenograft model.
Conclusions
This study identifies SMAD1 regulation of NF-κB1/TNFAIP8 and ID1-p21/p27 as critical axes of MM drug resistance and provides a potentially new therapeutic strategy to treat drug resistance MM through targeted inhibition of SMAD1.
Triple-negative breast cancer (TNBC) is a heterogeneous disease that includes Basal-like and Claudin-low tumors. The Claudin-low tumors are enriched for features associated with ...epithelial-to-mesenchymal transition (EMT) and possibly for tumor initiating cells. Primary TNBCs respond relatively well to conventional chemotherapy; however, metastatic disease is virtually incurable. Thus, there is a great interest in identifying specific therapeutic targets for TNBC. The tumor suppressor RB1 is frequently lost in Basal-like breast cancer. To test for a causative role of RB1 gene loss in BC and for its effect on specific subtypes, we deleted mouse Rb in mammary stem/bipotent progenitor cells. This led to diverse mammary tumors including TNBC, with a subset of the latter containing p53 mutations and exhibiting features of Basal-like BC or EMT. Combined mutation of Rb and p53 in mammary stem/bipotent progenitors induced EMT type tumors. Here, we review our findings and those of others, which connect Rb and p53 to EMT in TNBC. Furthermore, we discuss how by understanding this circuit and its vulnerabilities, we may identify novel therapy for TNBC.
Abstract
The most common events in breast cancer (BC) involve chromosome arm losses and gains. Here we describe identification of 1089 gene-centric common insertion sites (gCIS) from transposon-based ...screens in 8 mouse models of BC. Some gCIS are driver-specific, others driver non-specific, and still others associated with tumor histology. Processes affected by driver-specific and histology-specific mutations include well-known cancer pathways. Driver non-specific gCIS target the Mediator complex, Ca
++
signaling, Cyclin D turnover, RNA-metabolism among other processes. Most gCIS show single allele disruption and many map to genomic regions showing high-frequency hemizygous loss in human BC. Two gCIS,
Nf1
and
Trps1
, show synthetic haploinsufficient tumor suppressor activity. Many gCIS act on the same pathway responsible for tumor initiation, thereby selecting and sculpting just enough and just right signaling. These data highlight ~1000 genes with predicted conditional haploinsufficient tumor suppressor function and the potential to promote chromosome arm loss in BC.
Autophagy, an intracellular degradation pathway involved in cell survival or demise, is tightly controlled by complex regulatory mechanisms. A link between the Rb tumor suppressor and autophagy is ...now emerging. pRb plays a critical role in cell cycle progression and survival as well as the differentiation of certain cell types. Recently, we have reported that during skeletal myogenesis, Rb-deficient myoblasts fuse to form short myotubes that quickly degenerate. Myotube degeneration was associated with increased autophagic flux and inhibition of autophagy rescued the defect leading to long, twitching myotubes. We propose that Rb-loss sensitizes cells to autophagy via direct and indirect mechanisms and we discuss how these might affect cancer progression and response to chemotherapy.
Aerobic glycolysis is an important metabolic adaptation of cancer cells. However, there is growing evidence that reprogrammed mitochondria also play an important metabolic role in metastatic ...dissemination. Two constituents of the reprogrammed mitochondria of cancer cells are the intracellular tyrosine kinase Fer and its cancer- and sperm-specific variant, FerT. Here, we show that Fer and FerT control mitochondrial susceptibility to therapeutic and hypoxic stress in metastatic colon (SW620) and non-small cell lung cancer (NSCLC-H1299) cells. Fer- and FerT-deficient SW620 and H1299 cells (SW∆Fer/FerT and H∆Fer/FerT cells, respectively) become highly sensitive to metformin treatment and to hypoxia under glucose-restrictive conditions. Metformin impaired mitochondrial functioning that was accompanied by ATP deficiency and robust death in SW∆Fer/FerT and H∆Fer/FerT cells compared to the parental SW620 and H1299 cells. Notably, selective knockout of the
gene without affecting FerT expression reduced sensitivity to metformin and hypoxia seen in SW∆Fer/FerT cells. Thus, Fer and FerT modulate the mitochondrial susceptibility of metastatic cancer cells to hypoxia and metformin. Targeting Fer/FerT may therefore provide a novel anticancer treatment by efficient, selective, and more versatile disruption of mitochondrial function in malignant cells.
Methylation profiling is widely used to study tumor biology and perform cluster analysis, particularly in brain cancer research where tissue biopsies are scarce. We have recently reported on the ...development of novel mouse models for germ line mutations in pineoblastoma (Nature Communications, 2020). Here, we present unpublished methylation profiling of 8 Rb-deleted/p53-deleted pineoblastoma from our mouse model as well as 3 normal cerebellum tissues as control. The primary dataset can be accessed via SRA (PRJNA638504). These methylation data can be used to perform inter- and intra-species comparisons with other brain cancers as well as with specific subtypes of pineoblastoma, and to investigate potential epigenetic mechanisms and pathways underlying Rb-deficient pineoblastoma-genesis..
Precursors of cochlear and vestibular hair cells of the inner ear exit the cell cycle at midgestation. Hair cells are mitotically quiescent during late-embryonic differentiation stages and ...postnatally. We show here that the retinoblastoma gene Rb and the encoded protein pRb are expressed in differentiating and mature hair cells. In addition to Rb, the cyclin dependent kinase inhibitor (CKI) p21 is expressed in developing hair cells, suggesting that p21 is an upstream effector of pRb activity. p21 apparently cooperates with other CKIs, as p21-null mice exhibited an unaltered inner ear phenotype. By contrast, Rb inactivation led to aberrant hair cell proliferation, as analysed at birth in a loss-of-function/transgenic mouse model. Supernumerary hair cells expressed various cell type-specific differentiation markers, including components of stereocilia. The extent of alterations in stereociliary bundle morphology ranged from near-normal to severe disorganization. Apoptosis contributed to the mutant phenotype, but did not compensate for the production of supernumerary hair cells, resulting in hyperplastic sensory epithelia. The Rb-null-mediated proliferation led to a distinct pathological phenotype, including multinucleated and enlarged hair cells, and infiltration of hair cells into the mesenchyme. Our findings demonstrate that the pRb pathway is required for hair cell quiescence and that manipulation of the cell cycle machinery disrupts the coordinated development within the inner ear sensory epithelia.
Polycomb Repressive Complex 2 (PRC2) is an epigenetic regulator induced in many cancers. It is thought to drive tumorigenesis by repressing division, stemness, and/or developmental regulators. ...Cancers evade immune detection, and diverse immune regulators are perturbed in different tumors. It is unclear how such cell-specific effects are coordinated. Here, we show a profound and cancer-selective role for PRC2 in repressing multiple cytokine pathways. We find that PRC2 represses hundreds of IFNγ stimulated genes (ISGs), cytokines and cytokine receptors. This target repertoire is significantly broadened in cancer vs non-cancer cells, and is distinct in different cancer types. PRC2 is therefore a higher order regulator of the immune program in cancer cells. Inhibiting PRC2 with either RNAi or EZH2 inhibitors activates cytokine/cytokine receptor promoters marked with bivalent H3K27me3/H3K4me3 chromatin, and augments responsiveness to diverse immune signals. PRC2 inhibition rescues immune gene induction even in the absence of SWI/SNF, a tumor suppressor defective in ~20% of human cancers. This novel PRC2 function in tumor cells could profoundly impact the mechanism of action and efficacy of EZH2 inhibitors in cancer treatment.
PDF
