Controversy over the role of antioxidants in cancer has persisted for decades. Here, we demonstrate that synthesis of the antioxidant glutathione (GSH), driven by GCLM, is required for cancer ...initiation. Genetic loss of Gclm prevents a tumor’s ability to drive malignant transformation. Intriguingly, these findings can be replicated using an inhibitor of GSH synthesis, but only if delivered prior to cancer onset, suggesting that at later stages of tumor progression GSH becomes dispensable potentially due to compensation from alternative antioxidant pathways. Remarkably, combined inhibition of GSH and thioredoxin antioxidant pathways leads to a synergistic cancer cell death in vitro and in vivo, demonstrating the importance of these two antioxidants to tumor progression and as potential targets for therapeutic intervention.
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•The GSH antioxidant pathway is required for cancer initiation•After cancer initiation, GSH is dispensable due to alternative antioxidant pathways•The TXN antioxidant pathway is upregulated in tumors•Inhibition of both GSH and TXN pathways causes synergistic cancer cell death
Harris et al. show that the antioxidant glutathione (GSH) is required for cancer initiation but not for established tumors partly due to upregulation of the thioredoxin (TXN) antioxidant pathway in the latter. Consequently, blocking both GSH and TXN pathways synergistically inhibits tumor growth.
Triple negative breast cancer (TNBC) is a deadly form of breast cancer due to the development of resistance to chemotherapy affecting over 30% of patients. New therapeutics and companion biomarkers ...are urgently needed. Recognizing the elevated expression of glucose transporter 1 (GLUT1, encoded by SLC2A1) and associated metabolic dependencies in TNBC, we investigated the vulnerability of TNBC cell lines and patient-derived samples to GLUT1 inhibition. We report that genetic or pharmacological inhibition of GLUT1 with BAY-876 impairs the growth of a subset of TNBC cells displaying high glycolytic and lower oxidative phosphorylation (OXPHOS) rates. Pathway enrichment analysis of gene expression data suggests that the functionality of the E2F pathway may reflect to some extent OXPHOS activity. Furthermore, the protein levels of retinoblastoma tumor suppressor (RB1) strongly correlate with the degree of sensitivity to GLUT1 inhibition in TNBC, where RB1-negative cells are insensitive to GLUT1 inhibition. Collectively, our results highlight a strong and targetable RB1-GLUT1 metabolic axis in TNBC and warrant clinical evaluation of GLUT1 inhibition in TNBC patients stratified according to RB1 protein expression levels.
Triple-negative breast cancer (TNBC) is a breast cancer subtype that lacks targeted treatment options. The activation of the Notch developmental signaling pathway, which is a feature of TNBC, results ...in the secretion of proinflammatory cytokines and the recruitment of protumoral macrophages to the tumor microenvironment. While the Notch pathway is an obvious therapeutic target, its activity is ubiquitous, and predictably, anti-Notch therapies are burdened with significant on-target side effects. Previously, we discovered that, under conditions of cellular stress commonly found in the tumor microenvironment, the deubiquitinase USP9x forms a multiprotein complex with the pseudokinase tribbles homolog 3 (TRB3) that together activate the Notch pathway. Herein, we provide preclinical studies that support the potential of therapeutic USP9x inhibition to deactivate Notch. Using a murine TNBC model, we show that USP9x knockdown abrogates Notch activation, reducing the production of the proinflammatory cytokines, C-C motif chemokine ligand 2 (CCL2) and interleukin-1 beta (IL-1β). Concomitant with these molecular changes, a reduction in tumor inflammation, the augmentation of antitumor immune response, and the suppression of tumor growth were observed. The pharmacological inhibition of USP9x using G9, a partially selective, small-molecule USP9x inhibitor, reduced Notch activity, remodeled the tumor immune landscape, and reduced tumor growth without associated toxicity. Proving the role of Notch, the ectopic expression of the activated Notch1 intracellular domain rescued G9-induced effects. This work supports the potential of USP9x inhibition to target Notch in metabolically vulnerable tissues like TNBC, while sparing normal Notch-dependent tissues.
Abstract
Background
The Ontario Breast Screening Program expanded in July 2011 to screen high-risk women age 30–69 years with annual magnetic resonance imaging (MRI) and digital mammography. This ...study examined the benefits of screening with mammography and MRI by age and risk criteria.
Methods
This prospective cohort study included 8782 women age 30–69 years referred to the High Risk Ontario Breast Screening Program from July 2011 to June 2015, with final results to December 2016. Cancer detection rates, sensitivity, and specificity of MRI and mammography combined were compared with each modality individually within risk groups stratified by age using generalized estimating equation models. Prognostic features of screen-detected breast cancers were compared by modality using Fisher exact test. All P values are two-sided.
Results
Among 20 053 screening episodes, there were 280 screen-detected breast cancers (cancer detection rate = 14.0 per 1000, 95% confidence interval CI = 12.4 to 15.7). The sensitivity of mammography was statistically significantly lower than that of MRI plus mammography (40.8%, 95% CI = 29.3% to 53.5% vs 96.0%, 95% CI = 92.2% to 98.0%, P < .001). In mutation carriers age 30–39 years, sensitivity of the combination was comparable with MRI alone (100.0% vs 96.8%, 95% CI = 79.2% to 100.0%, P = .99) but with statistically significantly decreased specificity (78.0%, 95% CI = 74.7% to 80.9% vs 86.2%, 95% CI = 83.5% to 88.5%, P < .001). In women age 50–69 years, combining MRI and mammography statistically significantly increased sensitivity compared with MRI alone (96.3%, 95% CI = 90.6% to 98.6% vs 90.9%, 95% CI = 83.6% to 95.1%, P = .02), with a small but statistically significant decrease in specificity (84.2%, 95% CI = 83.1% to 85.2% vs 90.0%, 95% CI = 89.2% to 90.9%, P < .001).
Conclusions
Screening high risk women age 30–39 years with annual MRI only may be sufficient for cancer detection and should be evaluated further, particularly for mutation carriers. Among women age 50–69 years, detection is most effective when mammography is included with annual MRI.
Levels of circulating tumor cells (CTCs) in blood have prognostic value in early and metastatic breast cancer. CTCs also show varying degrees of concordance with molecular markers of primary tumors ...they originate from. It is expected that individual cells reflect the heterogeneity and evolution of tumor cells as they acquire new functions and differential responses to chemotherapy. However, a degree of commonality is also plausible, highlighting alterations that allow tumor cells to perform CTC‐defining activities such as invasion and intravasation. Using a matched tumor‐normal approach, we performed high‐resolution copy number profiling of CTCs from breast cancer to identify occult changes occurring during progression to metastasis. We identified a signature of recurrent gain in CTCs, consisting of 90 minimal common regions (MCRs) of copy number gain. These were predominantly found across chromosome 19 and were identified at low frequencies (3–4%) in 787 primary breast carcinomas examined. CTC genomic signatures clustered into two groups independent of subtype: a dormancy‐related signature with 16 MCRs (AKT2, PTEN, CADM2); and a tumor‐aggressiveness related signature with 358 MCRs (ANGPTL4, BSG, MIR‐373). There were two MCRs in common between the groups on 19q13 and 21q21, containing genes involved in resistance to anoikis, TGFβ‐signaling and metastasis (TFF3, LTBP4, NUMBL). Furthermore, a region harboring the ERBB2 gene was gained in a majority of patients. Regions 20q13 and 15q24 were associated with distant metastasis. The distinctiveness of CTC signatures highlights cell populations with different functional or metastatic potential. Such novel targets could help to specifically identify and block dissemination.
What's new?
People die of breast cancer not from the primary tumors, but because of uncontrolled metastasis, and circulating tumor cells (CTCs) could be the key to detecting it. In this paper, the authors examined the DNA of CTCs looking for identifying features that could help spot these harbingers of metastasis. They found certain copy number changes, predominantly on chromosome 19 that may indicate the cell's ability to travel. The changes fell into two categories: one associated with dormancy, the other with tumor aggressiveness. Detection of these genetic signatures could help target the most mobile cells and thwart metastasis.
Metformin may exert anti-cancer effects through indirect (insulin-mediated) or direct (insulin-independent) mechanisms. We report results of a neoadjuvant “window of opportunity” study of metformin ...in women with operable breast cancer. Newly diagnosed, untreated, non-diabetic breast cancer patients received metformin 500 mg tid after diagnostic core biopsy until definitive surgery. Clinical (weight, symptoms, and quality of life) and blood fasting serum insulin, glucose, homeostasis model assessment (HOMA), C-reactive protein (CRP), and leptin attributes were compared pre- and post-metformin as were terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and Ki67 scores (our primary endpoint) in tumor tissue. Thirty-nine patients completed the study. Mean age was 51 years, and metformin was administered for a median of 18 days (range 13–40) up to the evening prior to surgery. 51 % had T1 cancers, 38 % had positive nodes, 85 % had ER and/or PgR positive tumors, and 13 % had HER2 overexpressing or amplified tumors. Mild, self-limiting nausea, diarrhea, anorexia, and abdominal bloating were present in 50, 50, 41, and 32 % of patients, respectively, but no significant decreases were seen on the EORTC30-QLQ function scales. Body mass index (BMI) (−0.5 kg/m
2
,
p
< 0.0001), weight (−1.2 kg,
p
< 0.0001), and HOMA (−0.21,
p
= 0.047) decreased significantly while non-significant decreases were seen in insulin (−4.7 pmol/L,
p
= 0.07), leptin (−1.3 ng/mL,
p
= 0.15) and CRP (−0.2 mg/L,
p
= 0.35). Ki67 staining in invasive tumor tissue decreased (from 36.5 to 33.5 %,
p
= 0.016) and TUNEL staining increased (from 0.56 to 1.05,
p
= 0.004). Short-term preoperative metformin was well tolerated and resulted in clinical and cellular changes consistent with beneficial anti-cancer effects; evaluation of the clinical relevance of these findings in adequately powered clinical trials using clinical endpoints such as survival is needed.
Abstract
The extracellular matrix (ECM) collagen undergoes major remodeling during tumorigenesis. However, alterations to the ECM are not widely considered in cancer diagnostics, due to mostly ...uniform appearance of collagen fibers in white light images of hematoxylin and eosin-stained (H&E) tissue sections. Polarimetric second-harmonic generation (P-SHG) microscopy enables label-free visualization and ultrastructural investigation of non-centrosymmetric molecules, which, when combined with texture analysis, provides multiparameter characterization of tissue collagen. This paper demonstrates whole slide imaging of breast tissue microarrays using high-throughput widefield P-SHG microscopy. The resulting P-SHG parameters are used in classification to differentiate tumor from normal tissue, resulting in 94.2% for both accuracy and F1-score, and 6.3% false discovery rate. Subsequently, the trained classifier is employed to predict tumor tissue with 91.3% accuracy, 90.7% F1-score, and 13.8% false omission rate. As such, we show that widefield P-SHG microscopy reveals collagen ultrastructure over large tissue regions and can be utilized as a sensitive biomarker for cancer diagnostics and prognostics studies.
Invasive lobular carcinoma (ILC) of the breast is a very common disease. Despite its prevalence, these tumors are relatively understudied. One reason for this is a relative lack of models for ILC. ...This challenge was addressed by Brisken and colleagues through development of an intraductal injection‐based xenograft system for the study of ERα+ breast cancers, including both ILC and more common invasive ductal carcinoma (IDC; Sflomos et al, 2016). In this issue of EMBO Molecular Medicine, the same group have applied intraductal injection‐based xenografts to identify novel tumor cell‐specific transcriptional signatures in ILC (Sflomos et al, 2021). In doing so they found overexpression of lysyl oxidase‐like 1 (LOXL1) to be both responsible for the frequently seen stiff collagen‐rich extracellular matrix of lobular breast cancer and essential for their robust growth and metastatic dissemination in vivo, thereby identifying a novel therapeutic target.
Despite its prevalence, invasive lobular carcinoma (ILC) is relatively understudied. In their recent study, Brisken and colleagues apply intraductal injection based xenografts to characterize tumor‐cell specific transcriptional signatures in ILC and identify a novel therapeutic target.
Concurrent cohorts of 644,932 women aged 50–74 screened annually due to family history, dense breasts or biennially in the Ontario Breast Screening Program (OBSP) from 2011–2014 were linked to ...provincial administrative datasets to determine health system resource utilization and costs. Age-adjusted mean and median total healthcare costs (2018 CAD) and incremental cost differences were calculated by screening outcome and compared by recommendation using regression models. Healthcare costs were compared overall and 1 year after a false positive (n = 46,081) screening mammogram and 2 years after a breast cancer diagnosis (n = 6011). Mean overall healthcare costs by age were highest for those 60–74, particularly with annual screening for family/personal history (CAD 5425; 95% CI: 5308 to 5557) compared to biennial. Although the mean incremental cost difference was higher (23.4%) by CAD 10,235 (95% CI: 6141 to 14,329) per breast cancer for women screened annually for density ≥ 75% compared to biennially, the cost difference was 12.0% lower (−CAD 461; 95% CI: −777 to −114) per false positive result. In contrast, for women screened annually for family/personal history, the mean cost difference per false positive was 19.7% higher than for biennially (CAD 758; 95% CI: 404 to 1118); however, the cost difference per breast cancer was only slightly higher (2.5%) by CAD 1093 (95% CI: −1337 to CAD 3760). Understanding that associated costs of annual compared to biennial screening may balance out by age and outcome can assist decision-making regarding the use of limited healthcare resources.
In this study, we have looked at enhancing tumor uptake and intracellular delivery of gold nanoparticles (AuNPs) while reducing the systemic exposure by systematic evaluation of the impact of ...targeting and route of administration on organ distribution. High-resolution microSPECT/CT imaging was used to track the in vivo fate of 111In-labeled nontargeted and human epidermal growth factor receptor-2 (HER-2) targeted AuNPs following intravenous (i.v.) or intratumoral (i.t.) injection. For i.v. injection, the effects of GdCl3 (for deactivation of macrophages) and nonspecific (anti-CD20) antibody rituximab (for blocking of Fc mediated liver and spleen uptake) were studied. It was found that HER-2 targeting via attachment of trastuzumab paradoxically decreased tumor uptake as a result of faster elimination of the targeted AuNPs from the blood while improving internalization in HER-2-positive tumor cells as compared to nontargeted AuNPs. I.T. injections with HER-2 targeted AuNPs resulted in high tumor retention with low systemic exposure and represents an attractive delivery strategy. Our results provide a strategy for optimizing tumor delivery and quantifying organ distribution of this widely studied class of nanomaterial.
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