Breast Cancer Awareness Month

Accumulating evidence suggest that chemotherapy could paradoxically promote cancer metastasis. Here the authors report that, in preclinical breast cancer models, adjuvant treatment with doxorubicin induces the formation of an immunosuppressive metastatic niche that promotes relapse but that can be reverted with pharmacological blockade of complement signaling.

Tumor blood vessels contribute to cancer growth, invasion and metastasis. Here, by using single cell transcriptomics, the authors report an inventory of endothelial cell heterogeneity in patients with breast cancer, including a subtype that expresses genes involved in lipid processing and is regulated by PPAR-γ.

A substantial proportion of HER2+ breast cancer patients do not benefit from HER2-targeted therapy. Here, the authors identify a population of cancer-associated fibroblasts involved in the suppression of trastuzumab-induced ADCC that can be pharmacologically targeted to raise treatment effectiveness in unresponsive tumors.

CDK4/6 inhibitor resistance is common in breast cancer. Here, the authors show that p16 overexpression may be linked to reduced efficacy of CDK4/6 inhibition, and show that the combination with PI3K inhibitors may increase anti-tumour effects.

The study of tumour dormancy is limited by suitable in vivo models. Here the authors show that mammary intraductal breast cancer (BC) xenografts model estrogen receptor α-positive (ER+) BC dormancy and rapid metastatic progression characteristic of triple-negative (TN) BC. The dormant disseminated ER+ BC cells display characteristics of epithelial-mesenchymal plasticity and forced expression of E-cadherin allows them to overcome dormancy.

The distribution and organisation of matrix molecules in the tumour stroma help shape solid tumour progression. Here they perform temporal proteomic profiling of the matrisome during breast cancer progression and show that collagen XII secreted from CAFs provides a pro-invasive microenvironment.

Gene fitness and essentiality analyses using in vivo cancer models are challenging due to multiple confounders. Here, the authors develop a quantitative approach to study CRISPR-transduced patient-derived xenografts, which they use to analyse in vivo gene fitness in breast cancers and the biological features that influence uncertainty in fitness estimation.

Understanding the factors that hamper immune therapy in breast cancer may increase the range of patients who benefit. Here authors show that breast cancer cells produce and subsequently transfer active TGF-β type II receptors to CD8 + T cells to render them exhausted, thus paralyzing the anti-tumor immune response.

Kinases are important drug targets, but predicting their activities from phosphoproteomics data remains challenging. While many existing prediction tools rely on phosphosite-specific quantitative data, Crowl et al. develop a kinase activity prediction algorithm that requires no phosphosite quantification.

Cancer prognosis using multiregion sampling is costly and not completely reliable due to the required biomarker homogenisation step. Here, the authors develop an intratumor graph neural network for prognosis in multiregion cancer samples based on in situ biomarkers and gene expression that does not need homogenisation.

There is a need for potent and non-toxic estrogen receptor (ER) antagonists to overcome the limitations of existing endocrine therapies. Here the authors report the results from Arm 1 of the Phase 1/2 study (AMEERA-1) among postmenopausal women with ER+/HER2− advanced breast cancer, which evaluates the safety, antitumor activity, pharmacokinetics, and pharmacodynamics of amcenestrant administered as monotherapy.

Hypoxia can promote tumor escape from immune surveillance and immunotherapy. Here, the authors show that hypoxia induces T and NK cell dysfunction through HIF1α-mediated epigenetic suppression of effector gene expression, conferring resistance to anti-PD1 blockade in triple negative breast cancer models.

Platinum agents, such as carboplatin and cisplatin, have been recommended in combination with gemcitabine for the treatment of metastatic triple negative breast cancer (TNBC). Here the authors report the results of a randomized phase 3 trial to compare the efficacy of first-line nab-paclitaxel/cisplatin to gemcitabine/cisplatin in patients with TNBC.

DNA barcoding methods for the analysis of clonal heterogeneity in cancer have been limited in terms of throughput and practical requirements. Here, the authors develop SunCatcher, a rapid and sensitive barcoding approach for live single-cell clonal evolution analysis, and use this method to study breast cancer cell populations.

The oncoprotein c-Myc is often overexpressed in triple negative breast cancer and has a role in tumor progression and resistance to therapy. Here the authors show that elevated MYC expression is correlated with low immune infiltration, diminished MHC-I pathway expression and that CpG/aOX40 treatment could overcome resistance to PD-L1 blockade in MYC-high breast tumors.

Progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) remains poorly understood. Here, the authors analyse over 2700 micro-dissected samples using transcriptomics to identify genes that characterise different stages of DCIS to IDC progression, and identify IDC-associated markers within early-stage lesions.

FGFR-1 upregulation has been associated with endocrine therapy resistance in breast cancer patients. Here the authors report the results of a phase IIa study to assess the safety and efficacy of AZD454, an inhibitor of FGFR-1, 2 and 3 receptor tyrosine kinases, in combination with anastrozole or letrozole, in estrogen receptor positive breast cancer patients.

The role of progesterone receptor (PR) and its interplay with estrogen receptor (ER) in breast cancer is controversial. Here, the authors demonstrate that PR can have an ER-independent role in breast cancer growth and metastasis and that its effects are dependent on MYC and androgen receptor signatures.

Recent studies have reported that oncoprotein YAP can function as tumour suppressor in certain contexts. Here the authors show that inhibition of Hippo signalling or YAP activation blocks ERα transcriptional program and ER + breast cancer growth and mechanistically this is through YAP interfering with TEAD-ERα signalling axis.

Neddylation inhibition has been reported as a therapy for cancer. Here, the authors show that neddylation inhibition increases glutamine metabolism by stabilizing glutamine transporter ASCT2, therefore targeting ASCT2 improves the anti-cancer effect of neddylation inhibitors.

PARP inhibitor (PARPi) therapy has demonstrated only modest efficacy in advanced breast cancer with BRCA mutations. Here the authors show that, by suppressing PARPi-triggered DNA damage and reducing dsDNA production in BRCA1-deficient breast tumor cells, tumor associated macrophages contribute to PARPi resistance, that can be overcome by STING agonism.

Therapeutic options for patients with triple-negative breast cancer (TNBC) in later-line setting are limited. Here the authors report the results of a phase 2 clinical trial to evaluate efficacy and safety of the combination of camrelizumab (anti-PD1), apatinib (VEGFR2 inhibitor), and eribulin in patients with heavily pre-treated advanced TNBC.

Anti-HER2 resistance causes treatment failure in HER2-positive breast cancers. Here the authors identify FGFR4 as one of the vulnerabilities of anti-HER2 resistant breast cancer and show that FGRR4 inhibition enhances sensitivity to anti-HER2 treatment in these resistant cells by triggering ferroptosis.

Finding biomarkers for targeted therapy is a promising approach to treat cancer. Here, the authors show that in breast cancer preclinical models and patients, CDK12 promotes tumourigenesis but induces selective vulnerability to therapies that target folate one-carbon metabolism.

Breast cancer cells are known to metastasize to the bone but why the cells should migrate and metastasize to this particular organ is not clearly understood. Here, the authors show that EZH2 activates an integrin B1 and FAK signaling pathway in breast cancer cells, which activates TGFB signaling to drive metastasis in the bone.

The spatial context of epitranscriptomic features in the tumour microenvironment remains poorly understood. Here, a method for transcriptomic and epitranscriptomic analysis of immunofluorescence-stained tissue, Select-seq, is applied to stem cell-like microniches in triple negative breast cancer.

IRE1α cleaves several mRNAs upon accumulation of misfolded proteins. Here the authors show that active IRE1α cleaves DGAT2 mRNA encoding the rate-limiting enzyme in the synthesis of triacylglycerols, suggesting a role of IRE1α in reprogramming lipid metabolism in cancer cells.

SNIP1 methylation initiates its oncogenic functions. Here, the authors show that SNIP1 is methylated by KMT5A and this leads to downstream signalling that activates the YAP pathway, resulting in tumorigenesis and metastasis.

The epithelial mesenchymal transition (EMT) is important in the metastatic spread of cancer cells. Here, the authors show that the EMT transcription factor, ZEB1, can modify estrogen receptor α during EMT and facilitate the migration of breast cancer cells to the bone

Mutations of ESR1, the gene encoding the estrogen receptor alpha, are associated with acquired resistance to therapy in luminalbreast cancer. Here the authors show that ESR1 mutant tumors gain basal-like features with increased expression of basal cytokeratines and immune activation.

The effect of hyaluronan-mediated motility receptor (HMMR) expression in BRCA1-associated breast cancer risk remains unknown. Here, HMMR overexpression induces the activation of cGAS-STING and non-canonical NF-κB signalling, instigating an immune permissive environment for breast cancer development.

The impact of tumour heterogeneity on drug response in breast cancer is not fully understood. Here, the authors characterise cell lines from all main breast cancer subtypes using single-cell RNA-seq and train a deconvolution algorithm to predict drug responses in heterogeneous tumour cell populations.

Notch signalling is reported to be hyperactivated in oestrogen receptor-negative (ER-) breast cancer. Here the authors show that G protein-coupled receptor kinase-interacting protein 1 (GIT1) negatively regulates Notch signalling and tumour growth in ER- breast cancer by blocking Notch ICD nuclear translocation.

Patient-derived tumour organoids are important preclinical models but suffer from variability from the use of basement-membrane extract and cell contamination. Here, the authors report on the development of mimetic nanofibrilar hydrogel which supports tumour organoid growth with reduced batch variability and cell contamination.

Defects in BRCA1, a gene involved in homologous recombination DNA repair, are common in triple negative breast cancer. Here the authors show that Brca1 deficiency in preclinical breast cancer models is associated with the accumulation of myeloid derived suppressive cells and resistance to immune checkpoint blockade, that could be overcome by targeting S100A9 and CXCL12.

HER2+ breast cancer often develop brain metastases (BCBMs) that are difficult to treat. Here, the authors show that p16^INK4A loss in BCBMs from HER2+ breast tumors results in resistance to the HER2 inhibitor Tucatinib, and that CDK4/6 inhibition can restore sensitivity to this drug.

Gpr125 has emerged as a specific marker of mammary stem cells and basal progenitors. Here they show that Gpr125 cells congregate at ductal tips during morphogenesis and amass at tumor margins, and that high Gpr125 predicts early tumor onset and poor outcome in basal breast cancer.

The contribution of breast cancer stem cells (BCSCs) to metastasis needs further elucidation. Here, the authors show that BCSCs secrete DKK1 to protect metastasizing cancer cells from ferroptosis via upregulation of SLC7A11, and further show that the combination of a ferroptosis inducer with a DKK1 inhibitor reduces metastasis.

Hippo signalling is reported to be required for proper ESR1 expression. Here the authors reveal that the transcriptional repression of ESR1 is via LATS-YAP-TEAD-VGLL3 axis and the epigenetic regulation of ESR1 super enhancer in ER + breast cancer.

The establishment of a pre-metastatic niche is a key step preceding metastasis formation. Here the authors show that tumor-intrinsic Lin28B, a RNA-binding protein, has an essential role in the formation of an immune-suppressive pre-metastatic niche, promoting lung metastasis of breast cancer.

Hexokinase 2 expression is markedly induced in cancer cells and contributes to cancer cell metabolism. Here, the authors show that hexokinase 2 can contribute to the metastatic spread of cancer cells independently of its glycolytic function via inhibiting the activity of GSK3β, which in turn elevates the protein levels of the EMT transcription factor SNAIL.

Protein level information enables the identification of potential biomarkers and therapeutic targets for breast cancer. Here, the authors perform proteomic analysis of 2 cohorts of breast cancer surgical specimens and identify distinct subtypes, immune features and survival outcomes.

Copy number alterations are pivotal genetic events in triple-negative breast cancer. Here the authors show the amplification of ENSA at the 1q21.3 region promotes the progression of TNBC via up-regulation of cholesterol biosynthesis.

Breast cancer is most commonly diagnosed via a needle biopsy. In this study, the authors show that cervical samples from women with breast cancer have a methylation signature different to that of healthy controls.

The molecular landscape of breast cancer brain metastases (BCBM) is still understudied, especially for different breast cancer subtypes. Here, the authors characterise subtype-specific BCBMs using genomics and transcriptomics and identify homologous recombination deficiency as a key therapeutic vulnerability.

Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that modulates target gene expression in response to changes in oxygen availability. Here the authors show that HIF-1 forms a complex with TRIM28 and DNA-dependent protein kinase (DNA-PK) that phosphorylates TRIM28. This leads to CDK9 recruitment, which stimulates RNA polymerase II (RNAPII) pause release and transcriptional elongation.

PI3K inhibitors have limited efficacy in triple negative breast cancer (TNBC). Here, the authors show that MAPK4 activates AKT independent of PI3K and thus promotes tumour growth in a subset of TNBC and that MAPK4 inhibition sensitizes to PI3K blockade in these tumours.’

Invasive micropapillary carcinoma (IMPC) is a highly metastatic rare form of breast cancer but its genomic alterations are largely unknown. Here, the authors show that monoclonal metastatic ancestors share copy-number loss of PRDM16 and IGSF9 and gain of ALDH2 in primary samples from IMPC patients.

Obesity is linked to cancer risk in post-menopausal breast cancer. At the molecular level this is governed by cellular adaption to palmitic acid through epigenetic activation of a C/EBPB-dependent transcriptional network that drives tumor formation.

Copper depletion has been reported to improve survival in patients with triple negative breast cancer (TNBC) but the underlying mechanisms are not completely understood. Here, the authors show that copper chelation reduces mitochondrial oxidative phosphorylation leading to decreased TNBC metastasis.

Intravital imaging reveals macrophage-driven de novo induction of cancer stem cells in vivo, and their dramatic enrichment on dissemination through TMEM doorways. These findings provide a mechanism for the validated ability of TMEM doorway density to be prognostic for distant recurrence of metastatic tumors in breast cancer patients.

The involvement of nuclear pore proteins in cellular mechanosensing and metastasis is unclear. Here the authors identify that nuclear pore protein NUP210 promotes metastasis through the interaction with mechanotransducer LINC complex protein and chromatin to regulate mechanosensitive genes.

Reliable luminal estrogen receptor (ERα+) breast cancer models are limited. Here, the authors use patient derived breast epithelial and breast cancer explant cultures grown in several extracellular matrix scaffolds and show that ERα expression is regulated by matrix stiffness via stress-mediated p38 activation and H3K27me3-mediated epigenetic regulation.

The visualisation of the bone metastasis process in a spatial temporal manner is lacking. Here, the authors use three-dimensional quantitative imaging and show that mouse mammary tumour cells preferentially home to endothelial subtype type H vessels within the bone marrow and remodel this vasculature by producing granulocyte-colony stimulating factor.

Breast cancer heterogeneity and tumour evolutionary trajectories remain largely unknown among women of African ancestry. Here, the authors perform whole genome and transcriptome sequencing of Nigerian breast cancer patients and identify unique evolutionary phenomena.

Inflammatory breast cancer (IBC) is an aggressive form of breast cancer with a poor prognosis. Here the authors report the characterization of a human IBC cell line recapitulating the clinical and histopathological features of the human disease, and implicating its high level of CCL2 in macrophage infiltration and tumor progression.

Resistance to HER2 inhibition in HER2- amplified breast cancer is common in the metastatic setting and the underlying molecular mechanisms remain unknown. Here, the authors, perform genomic profiling of 733 HER2-amplified breast cancers and propose genetic activation of MAPK as a resistance mechanism.

BRCA1 dysfunction sensitizes cancer cells to PARP inhibitors (PARPi) but the underlying mechanism is unclear. Here, the authors identify RNF19A as a determinant of PARPi sensitivity, showing that RNF19A ubiquitinates BARD1, negatively regulates the BRCA1-BARD1 complex, and inhibits homologous recombination.

HER2-targeted therapy improves patient’s outcome in early breast cancer. Here, the authors present the efficacy and biomarker analysis of two HER2-targeted combinations (ado-trastuzumab emtansine plus pertuzumab and paclitaxel, trastuzumab and pertuzumab) in the context of the neoadjuvant I-SPY2 phase 2 adaptive platform trial for early breast cancer at high risk of recurrence.

Antibody Drug Conjugates (ADCs) are emerging in the field of precision cancer medicine. Here, the authors suggest using endocytosis as a predictive biomarker for response

The molecular differences between postpartum (PPBC) and nulliparous (NPBC) young women breast cancer (YWBC) patients remain unknown. Here the authors perform RNA sequencing and multiplex immunohistochemistry on an FFPE breast cancer cohort and suggest that PPBC is a unique entity within YWBC with poor prognosis.

Triple negative breast cancer can be divided into additional subtypes. Here, using omics analyses, the authors show that in the mesenchymal subtype expression of MHC-1 is repressed and that this can be restored by using drugs that target subunits of the epigenetic modifier PRC2.

TGFβ is secreted in an inactive form in the tumor microenvironment. Authors here show that although TGFβ is produced mainly by cancer cells, regulatory T cells are necessary for its activation via expression of the b8 chain of avb8 integrin. Thus, both cell types contribute to TGFβ dependent tumor growth.

Caloric restriction (CR) has been shown as an effective intervention to reduce tumorigenesis, but alternative less stringent dietary interventions have also been considered. Here, the authors show that in a murine model of breast cancer CR has a larger effect on preventing tumorigenesis and metastasis compared to periodic caloric cycling.

The formation of the pre-metastatic niche enables the colonisation of disseminated cancer cells in distant organs. Here, the authors show that Th2 cytokines induce Complement 3 production in lung mesenchymal stromal cells, which recruits neutrophils and promotes the formation neutrophil extracellular traps, facilitating breast cancer cell metastasis to the lungs.

While transcriptomics have enhanced our understanding for cancer, spatial transcriptomics enable the characterisation of cellular interactions. Here, the authors integrate single cell data with spatial information for HER2 + tumours and develop tools for the prediction of interactions between tumour-infiltrating cells.

A randomized phase 2 clinical trial has recently shown no benefit of the combination eribulin and pembrolizumab over pembrolizumab alone in HR + metastatic breast cancer patients (NCT03051659). Here, the authors are reporting the final OS data and biomarker analyses on a subset of samples to analyze molecular correlates

Acquisition of CDK4/6i resistance represents a major clinical challenge. Here, the authors report that inhibition of CK1ε can prevent acquisition of CDK4/6i resistance, potentiating the therapeutic efficacy of CDK4/6i in human breast cancer.

Disseminated tumor cells often become dormant before awakening for metastatic growth. Here, the authors report that the lncRNA, NR2F1-AS1, is upregulated in dormant mesenchymal-like breast cancer stem-like cells and promotes dissemination but inhibits proliferation, leading to metastatic dormancy.

Transposon based screens carried out in mice can identify genes critical for tumourigensis. Here, the authors describe transposon screens in mouse models of breast cancer and highlight a large group of tumour suppressors that could underlie selection for common chromosome arm losses in cancer.

Bone metastasis is a major complication of breast cancer (BC) and ER⁺ tumors have a higher incidence of bone metastasis than ER⁻ tumors. Here, the authors report that miR‐19a in exosomes and the bone matrix protein, IBSP, are upregulated and secreted by bone tropic ER⁺ BC cells, where they cooperatively induce osteoclastogenesis and promote bone colonization.

The classification of breast lesions as indolent or aggressive to tailor treatment is crucial. Here, the authors use single-cell transcriptomics and multiparametric imaging of a breast cancer mouse model, report distinct tumor-immune features for the two types of lesions, and suggest the role of IL-17 signaling in disease progression.

Germline mutations in BRCA1 or BRCA2 tumour suppressor genes predispose to different cancers, as does oncogene activation. Here the authors reveal that aberrant transcription of specific genes triggered by activation of the oncogene β-catenin causes replication failure and cell death in the context of BRCA1/2 deficiency.

Circulating tumor cell (CTC) clusters are more efficient at mediating metastasis as compared to single cells and are associated with poor prognosis in breast cancer. Here, the authors show that ICAM1 is enriched in CTC clusters and its loss suppresses cell-cell interaction and CTC cluster formation, and propose ICAM1 as a therapeutic target for treating breast cancer metastasis.

Finding therapeutic strategies for aggressive triple negative breast cancer (TNBC) is an important challenge in clinical practice. Here, the authors identify a multi-kinases inhibitor with antitumor activity and able overcome chemotherapy resistance of TNBC in vivo.

Vasculogenic mimicry (VM) contributes to the development of triple-negative breast cancer. In this study, the authors show that TEM8 is expressed in VM-forming breast cancer stem cells and it promotes stemness and VM differentiation capacity through a RhoC/ROCK1/SMAD5 axis

Bone metastases are associated with poor prognosis in patients with breast cancer and limited therapeutic options. Here the authors exploit near-infrared light responsive macrophages for the tumor-selective delivery of oxaliplatin prodrug for chemo-photodynamic therapy of primary and bone metastatic breast cancer.

The epithelial-mesenchymal transition (EMT) has been implicated in stem cell properties and therapeutic resistance in cancer. Here, the authors show organoids derived from mesenchymal breast cancers exhibit a spikey structure which can be reverted and exploited for screening drugs that reverse EMT.

GWAS have enhanced our understanding for the genetic basis of breast cancer, but the majority of them were performed for European ancestry populations. Here, the authors use a cross-ancestry approach and report seven new variants associated with breast cancer risk among women of African ancestry.

The cellular origin and oncogenic drivers promoting claudin-low breast cancer are undefined. Here, the authors report that the consistent activation of oncogenic RAS signaling, as well as regulators of EMT, play a crucial role in the cellular plasticity and maintenance of the mesenchymal and stem cell characteristics of claudin-low mammary cancer cells.