Pharmacological induction of chromatin remodeling drives chemosensitization in triple-negative breast cancer.

Targeted therapies have improved outcomes for certain cancer subtypes, but cytotoxic chemotherapy remains a mainstay for triple-negative breast cancer (TNBC). The epithelial-to-mesenchymal transition (EMT) is a developmental program co-opted by cancer cells that promotes metastasis and chemoresistance. There are no therapeutic strategies specifically targeting mesenchymal-like cancer cells. We report that the US Food and Drug Administration (FDA)-approved chemotherapeutic eribulin induces ZEB1-SWI/SNF-directed chromatin remodeling to reverse EMT that curtails the metastatic propensity of TNBC preclinical models. Eribulin induces mesenchymal-to-epithelial transition (MET) in primary TNBC in patients, but conventional chemotherapy does not. In the treatment-naive setting, but not after acquired resistance to other agents, eribulin sensitizes TNBC cells to subsequent treatment with other chemotherapeutics. These findings provide an epigenetic mechanism of action of eribulin, supporting its use early in the disease process for MET induction to prevent metastatic progression and chemoresistance. These findings warrant prospective clinical evaluation of the chemosensitizing effects of eribulin in the treatment-naive setting.

TRIM33 Is a Co-Regulator of Estrogen Receptor Alpha.

Estrogen receptor alpha (ER)-positive breast cancer is responsible for over 60% of breast cancer cases in the U.S. Among patients diagnosed with early-stage ER+ disease, 1/3 will experience recurrence despite treatment with adjuvant endocrine therapy. ER is a nuclear hormone receptor responsible for estrogen-driven tumor growth. ER transcriptional activity is modulated by interactions with coregulators. Dysregulation of the levels of these coregulators is involved in the development of endocrine resistance. To identify ER interactors that modulate transcriptional activity in breast cancer, we utilized biotin ligase proximity profiling of ER interactomes. Mass spectrometry analysis revealed tripartite motif containing 33 (TRIM33) as an estrogen-dependent interactor of ER. shRNA knockdown showed that TRIM33 promoted ER transcriptional activity and estrogen-induced cell growth. Despite its known role as an E3 ubiquitin ligase, TRIM33 increased the stability of endogenous ER in breast cancer cells. TRIM33 offers a novel target for inhibiting estrogen-induced cancer cell growth, particularly in cases of endocrine resistance driven by ER (ESR1) gene amplification or overexpression.

SARS-CoV-2 Vaccine-Elicited Immunity after B Cell Depletion in Multiple Sclerosis.

The impact of B cell deficiency on the humoral and cellular responses to SARS-CoV2 mRNA vaccination remains a challenging and significant clinical management question. We evaluated vaccine-elicited serological and cellular responses in 1) healthy individuals who were pre-exposed to SARS-CoV-2 (n = 21), 2) healthy individuals who received a homologous booster (mRNA, n = 19; or Novavax, n = 19), and 3) persons with multiple sclerosis on B cell depletion therapy (MS-αCD20) receiving mRNA homologous boosting (n = 36). Pre-exposure increased humoral and CD4 T cellular responses in immunocompetent individuals. Novavax homologous boosting induced a significantly more robust serological response than mRNA boosting. MS-α CD20 had an intact IgA mucosal response and an enhanced CD8 T cell response to mRNA boosting compared with immunocompetent individuals. This enhanced cellular response was characterized by the expansion of only effector, not memory, T cells. The enhancement of CD8 T cells in the setting of B cell depletion suggests a regulatory mechanism between B and CD8 T cell vaccine responses.

Design of Abrasion-Resistant, Long-Lasting Antifog Coatings.

Fog formation is a common challenge for numerous applications, such as food packaging, mirrors, building windows, and freezer/refrigerator doors. Most notably, fog forms on the inner surfaces of prescription glasses and safety eyewear (particularly when used with a mask), face shields, and helmet lenses. Fogging is caused by the distortion of light from condensed water droplets present on a surface and can typically be prevented if the surface static water contact angle (θ) is less than ∼40°. Such a low contact angle can be readily achieved by either increasing the substrate surface energy or by engineering surface nanotexture. Unfortunately, such nanotexture can be readily damaged with use, while high surface energy substrates get covered with low surface energy foulants over time. Consequently, even with numerous ephemeral antifog coatings, currently there are no commercially available, durable, and permanent antifog coatings. Here we discuss the development of a new class of high-performance antifog coatings that are abrasion-resistant and long-lasting. These polyvinylpyrrolidone-based coatings, designed based on the classical Ratner-Lancaster wear model, dramatically outperform the base polymer, as well as all tested commercially available antifog coatings. Specifically, these coatings exhibit a > 400% increase in fogging time compared to base polymer, a > 50,000% increase in wear resistance, and excellent long-term antifog performance. The developed coatings also significantly outperformed all tested commercially available antifog coatings in terms of their antifog performance, wear resistance, and long-term cyclical performance. Additionally, the key design strategies employed here─incorporation of toughening agents and hydrophilic slip additives─offer a new approach to developing high-performance, durable antifog coatings based on other well-known antifog polymers.

Alteration of DNA methyltransferases by eribulin elicits broad DNA methylation changes with potential therapeutic implications for triple-negative breast cancer.

Background: Triple-negative breast cancer (TNBC) is an aggressive disease with limited treatment options. Eribulin, a chemotherapeutic drug, induces epigenetic changes in cancer cells, suggesting a unique mechanism of action. Materials & methods: MDA-MB 231 cells were treated with eribulin and paclitaxel, and the samples from 53 patients treated with neoadjuvant eribulin were compared with those from 14 patients who received the standard-of-care treatment using immunohistochemistry. Results: Eribulin treatment caused significant DNA methylation changes in drug-tolerant persister TNBC cells, and it also elicited changes in the expression levels of epigenetic modifiers (DNMT1, TET1, DNMT3A/B) in vitro and in primary TNBC tumors. Conclusion: These findings provide new insights into eribulin's mechanism of action and potential biomarkers for predicting TNBC treatment response.

The clinicopathological features of thrombosis with thrombocytopenia syndrome following ChAdOx1-S (AZD1222) vaccination and case outcomes in Australia: a population-based study.

Background: Thrombosis with thrombocytopenia syndrome (TTS) associated with viral vector COVID-19 vaccines, including ChAdOx1-S (AstraZeneca AZD1222) vaccine, can result in significant morbidity and mortality. We report the clinicopathological features of TTS following ChAdOx1-S vaccination and summarise the case outcomes in Australia. Methods: In this cohort study, patients diagnosed with TTS in Australia between 23 March and 31 December 2021 were identified according to predefined criteria. Cases were included if they met the Therapeutic Goods Administration (TGA) probable and confirmed case definitions and were reclassified using Centres for Disease Control and Prevention (CDC) definition for analysis. Data were collected on patient baseline characteristics, clinicopathological features, risk factors, treatment and outcomes. Findings: A total of 170 TTS cases were identified, with most occurring after the first dose (87%) of ChAdOx1-S. The median time to symptom onset after vaccination and symptom onset to admission was 11 and 2 days respectively. The median age of cases was 66 years (interquartile range 55-74). All except two patients received therapeutic anticoagulation and 66% received intravenous immunoglobulin. Overall, 85.3% of cases were discharged home after a median hospitalisation of 6 days, 9.4% required ongoing rehabilitation and 5.3% died. Eight deaths were related to TTS, with another dying from an unrelated condition while receiving treatment for TTS. Deaths occurred more commonly in those classified as Tier 1 according to the CDC definition and were associated with more severe thrombocytopenia and disease-related haemorrhage. Interpretation: TTS, while rare, can be severe and have catastrophic outcomes in some individuals. In Australia, the mortality rate was low compared to that reported in other high-income countries. Almost all received therapeutic anticoagulation with no bleeding complications and were successfully discharged. This emphasises the importance of community education and an established pathway for early recognition, diagnosis and treatment of TTS. Funding: Australian Commonwealth Department of Health and Aged Care. H.A Tran, N. Wood, J. Buttery, N.W. Crawford, S.D. Chunilal, V.M. Chen are supported by Medical Research Future Funds (MRFF) grant ID 2015305.

Estrogen Therapy Induces Receptor-Dependent DNA Damage Enhanced by PARP Inhibition in ER+ Breast Cancer.

PURPOSE: Clinical evidence indicates that treatment with estrogens elicits anticancer effects in ∼30% of patients with advanced endocrine-resistant estrogen receptor α (ER)-positive breast cancer. Despite the proven efficacy of estrogen therapy, its mechanism of action is unclear and this treatment remains underused. Mechanistic understanding may offer strategies to enhance therapeutic efficacy. EXPERIMENTAL DESIGN: We performed genome-wide CRISPR/Cas9 screening and transcriptomic profiling in long-term estrogen-deprived ER+ breast cancer cells to identify pathways required for therapeutic response to the estrogen 17ß-estradiol (E2). We validated findings in cell lines, patient-derived xenografts (PDX), and patient samples, and developed a novel combination treatment through testing in cell lines and PDX models. RESULTS: Cells treated with E2 exhibited replication-dependent markers of DNA damage and the DNA damage response prior to apoptosis. Such DNA damage was partially driven by the formation of DNA:RNA hybrids (R-loops). Pharmacologic suppression of the DNA damage response via PARP inhibition with olaparib enhanced E2-induced DNA damage. PARP inhibition synergized with E2 to suppress growth and prevent tumor recurrence in BRCA1/2-mutant and BRCA1/2-wild-type cell line and PDX models. CONCLUSIONS: E2-induced ER activity drives DNA damage and growth inhibition in endocrine-resistant breast cancer cells. Inhibition of the DNA damage response using drugs such as PARP inhibitors can enhance therapeutic response to E2. These findings warrant clinical exploration of the combination of E2 with DNA damage response inhibitors in advanced ER+ breast cancer, and suggest that PARP inhibitors may synergize with therapeutics that exacerbate transcriptional stress.

Alternating 17ß-Estradiol and Aromatase Inhibitor Therapies Is Efficacious in Postmenopausal Women with Advanced Endocrine-Resistant ER+ Breast Cancer.

PURPOSE: Strategies to implement estrogen therapy for advanced estrogen receptor-positive (ER+) breast cancer are underdeveloped. Preclinical data suggest that cycling treatment with 17ß-estradiol followed by estrogen deprivation can control tumor growth long-term. PATIENTS AND METHODS: Postmenopausal women with advanced ER+/HER2- breast cancer with recurrence or progression on ≥ 1 antiestrogen or aromatase inhibitor (AI)-based therapy were eligible. Patients received 17ß-estradiol (2 mg orally, three times a day) for 8 weeks followed by AI (physician's choice) for 16 weeks, alternating treatments on an 8-week/16-week schedule until disease progression. Patients then optionally received continuous single-agent treatment until a second instance of disease progression. Endpoints included 24-week clinical benefit and objective response per RECIST, and tumor genetic alterations. RESULTS: Of 19 evaluable patients, clinical benefit rate was 42.1% [95% confidence interval (CI), 23.1%-63.9%] and objective response rate (ORR) was 15.8% (95% CI, 5.7%-37.9%). One patient experienced a grade 3 adverse event related to 17ß-estradiol. Among patients who received continuous single-agent treatment until a second instance of disease progression, clinical benefit was observed in 5 of 12 (41.7%) cases. Tumor ER (ESR1) mutations were found by whole-exome profiling in 4 of 7 (57.1%) versus 2 of 9 (22.2%) patients who did versus did not experience clinical benefit from alternating 17ß-estradiol/AI therapy. The only two patients to experience objective responses to initial 17ß-estradiol had tumor ESR1 mutations. CONCLUSIONS: Alternating 17ß-estradiol/AI therapy may be a promising treatment for endocrine-refractory ER+ breast cancer, including following progression on CDK4/6 inhibitors or everolimus. Further study is warranted to determine whether the antitumor activity of 17ß-estradiol differs according to ESR1 mutation status.

Alteration of DNMT1/DNMT3A by eribulin elicits global DNA methylation changes with potential therapeutic implications for triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is an aggressive disease subtype with limited treatment options. Eribulin is a chemotherapeutic approved for the treatment of advanced breast cancer that has been shown to elicit epigenetic changes. We investigated the effect of eribulin treatment on genome-scale DNA methylation patterns in TNBC cells. Following repeated treatment, The results showed that eribulin-induced changes in DNA methylation patterns evident in persister cells. Eribulin also affected the binding of transcription factors to genomic ZEB1 binding sites and regulated several cellular pathways, including ERBB and VEGF signaling and cell adhesion. Eribulin also altered the expression of epigenetic modifiers including DNMT1, TET1, and DNMT3A/B in persister cells. Data from primary human TNBC tumors supported these findings: DNMT1 and DNMT3A levels were altered by eribulin treatment in human primary TNBC tumors. Our results suggest that eribulin modulates DNA methylation patterns in TNBC cells by altering the expression of epigenetic modifiers. These findings have clinical implications for using eribulin as a therapeutic agent.

Pharmacological Induction of mesenchymal-epithelial transition chemosensitizes breast cancer cells and prevents metastatic progression.

The epithelial-mesenchymal transition (EMT) is a developmental program co-opted by tumor cells that aids the initiation of the metastatic cascade. Tumor cells that undergo EMT are relatively chemoresistant, and there are currently no therapeutic avenues specifically targeting cells that have acquired mesenchymal traits. We show that treatment of mesenchymal-like triple-negative breast cancer (TNBC) cells with the microtubule-destabilizing chemotherapeutic eribulin, which is FDA-approved for the treatment of advanced breast cancer, leads to a mesenchymal-epithelial transition (MET). This MET is accompanied by loss of metastatic propensity and sensitization to subsequent treatment with other FDA-approved chemotherapeutics. We uncover a novel epigenetic mechanism of action that supports eribulin pretreatment as a path to MET induction that curtails metastatic progression and the evolution of therapy resistance.

Species invasions shift microbial phenology in a two-decade freshwater time series.

Invasive species impart abrupt changes on ecosystems, but their impacts on microbial communities are often overlooked. We paired a 20 y freshwater microbial community time series with zooplankton and phytoplankton counts, rich environmental data, and a 6 y cyanotoxin time series. We observed strong microbial phenological patterns that were disrupted by the invasions of spiny water flea (Bythotrephes cederströmii) and zebra mussels (Dreissena polymorpha). First, we detected shifts in Cyanobacteria phenology. After the spiny water flea invasion, Cyanobacteria dominance crept earlier into clearwater; and after the zebra mussel invasion, Cyanobacteria abundance crept even earlier into the diatom-dominated spring. During summer, the spiny water flea invasion sparked a cascade of shifting diversity where zooplankton diversity decreased and Cyanobacteria diversity increased. Second, we detected shifts in cyanotoxin phenology. After the zebra mussel invasion, microcystin increased in early summer and the duration of toxin production increased by over a month. Third, we observed shifts in heterotrophic bacteria phenology. The Bacteroidota phylum and members of the acI Nanopelagicales lineage were differentially more abundant. The proportion of the bacterial community that changed differed by season; spring and clearwater communities changed most following the spiny water flea invasion that lessened clearwater intensity, while summer communities changed least following the zebra mussel invasion despite the shifts in Cyanobacteria diversity and toxicity. A modeling framework identified the invasions as primary drivers of the observed phenological changes. These long-term invasion-mediated shifts in microbial phenology demonstrate the interconnectedness of microbes with the broader food web and their susceptibility to long-term environmental change.

Estrogen therapy induces receptor-dependent DNA damage enhanced by PARP inhibition in ER+ breast cancer.

Purpose: Clinical evidence indicates that treatment with estrogens elicits anti-cancer effects in ∼30% of patients with advanced endocrine-resistant estrogen receptor alpha (ER)-positive breast cancer. Despite the proven efficacy of estrogen therapy, its mechanism of action is unclear and this treatment remains under-utilized. Mechanistic understanding may offer strategies to enhance therapeutic efficacy. Experimental Design: We performed genome-wide CRISPR/Cas9 screening and transcriptomic profiling in long-term estrogen-deprived (LTED) ER+ breast cancer cells to identify pathways required for therapeutic response to the estrogen 17ß-estradiol (E2). We validated findings in cell lines, patient-derived xenografts (PDXs), and patient samples, and developed a novel combination treatment through testing in cell lines and PDX models. Results: Cells treated with E2 exhibited replication-dependent markers of DNA damage and the DNA damage response prior to apoptosis. Such DNA damage was partially driven by the formation of DNA:RNA hybrids (R-loops). Pharmacological suppression of the DNA damage response via poly(ADP-ribose) polymerase (PARP) inhibition with olaparib enhanced E2-induced DNA damage. PARP inhibition synergized with E2 to suppress growth and prevent tumor recurrence in BRCA1/2 -mutant and BRCA1 /2-wild-type cell line and PDX models. Conclusions: E2-induced ER activity drives DNA damage and growth inhibition in endocrine-resistant breast cancer cells. Inhibition of the DNA damage response using drugs such as PARP inhibitors can enhance therapeutic response to E2. These findings warrant clinical exploration of the combination of E2 with DNA damage response inhibitors in advanced ER+ breast cancer, and suggest that PARP inhibitors may synergize with therapeutics that exacerbate transcriptional stress.

Alpelisib Efficacy without Cherry-PI3King Mutations.

The PI3K inhibitor alpelisib is clinically approved for the treatment of metastatic estrogen receptor-positive breast cancers harboring hotspot mutations in PIK3CA, which encodes a subunit of PI3K. Prospective clinical trial results demonstrated benefit from alpelisib for the treatment of advanced ER+ breast cancers harboring PIK3CA mutations in the hotspots of exons 7, 9, and 20. However, 20% of PIK3CA mutations occur in non-hotspot regions. A recent article demonstrated that patients with cancers bearing non-hotspot PIK3CA mutations also derived benefit from alpelisib, which will inform clinical decision-making moving forward. See related article by Rugo et al., p. 1056.

The role of cancer cell bioenergetics in dormancy and drug resistance.

While anti-cancer drug treatments are often effective for the clinical management of cancer, these treatments frequently leave behind drug-tolerant persister cancer cells that can ultimately give rise to recurrent disease. Such persistent cancer cells can lie dormant for extended periods of time, going undetected by conventional clinical means. Understanding the mechanisms that such dormant cancer cells use to survive, and the mechanisms that drive emergence from dormancy, is critical to the development of improved therapeutic strategies to prevent and manage disease recurrence. Cancer cells often exhibit metabolic alterations compared to their non-transformed counterparts. An emerging body of evidence supports the notion that dormant cancer cells also have unique metabolic adaptations that may offer therapeutically targetable vulnerabilities. Herein, we review mechanisms through which cancer cells metabolically adapt to persist during drug treatments and develop drug resistance. We also highlight emerging therapeutic strategies to target dormant cancer cells via their metabolic features.

Image-Guided Spine Interventions for Pain: Ongoing Controversies.

An expanding array of image-guided spine interventions have the potential to provide immediate and effective pain relief. Innovations in spine intervention have proceeded rapidly, with clinical adoption of new techniques at times occurring before the development of bodies of evidence to establish efficacy. Although new spine interventions have been evaluated by clinical trials, acceptance of results has been hindered by controversies regarding trial methodology. This article explores controversial aspects of four categories of image-guided interventions for painful conditions: spine interventions for postdural puncture headache resulting from prior lumbar procedures, epidural steroid injections for cervical and lumbar radiculopathy, interventions for facet and sacroiliac joint pain, and vertebral augmentations for compression fractures. For each intervention, we summarize the available literature, with an emphasis on persistent controversies, and discuss how current areas of disagreement and challenge may shape future research and innovation. Despite the ongoing areas of debate regarding various aspects of these procedures, effective treatments continue to emerge and show promise for aiding relief of a range of debilitating conditions.

Tumour, whole-blood, plasma and tissue concentrations of metformin in lung cancer patients.

AIM: Metformin is used for the management of type 2 diabetes mellitus (T2DM) and is being tested clinically as an anticancer agent. Metformin concentrations safely achievable in human solid tissues including tumours are unknown. This study was designed to determine metformin concentration in tissue compartments as a function of dose to inform rational dosing in preclinical models and interpretation of clinical results." METHODS: Subjects with solid tumours to be treated by resection and either (A) willingness to take metformin for 7-10 days before surgery or (B) taking metformin for T2DM were eligible. Whole blood, plasma, tumour, tumour-adjacent uninvolved tissue and subcutaneous adipose tissue were obtained for liquid chromatography with tandem mass spectrometry to measure metformin concentrations. RESULTS: All subjects had primary lung tumours. Metformin dose was significantly correlated with drug concentrations in all tissues analysed. Intersubject metformin concentrations varied by over two orders of magnitude. Metformin concentrations were significantly higher in tumour tissues and lower in adipose tissues compared to other tissues. Concentrations in blood and plasma were significantly correlated with concentrations in solid tissues. CONCLUSION: Metformin accumulates in cellular compartments. Concentrations observed in plasma, blood, lung and tumour tissues in subjects treated with US Food and Drug Administration-approved doses for T2DM are lower than those typically used in tissue culture studies. However, such tissue concentrations are in line with those found within cultured cells treated with supra-pharmacological doses of metformin. Given the large intersubject variability in metformin concentrations, it is imperative to determine whether there is an association between tissue metformin concentration and anticancer activity in humans.

Ischemia With Nonobstructive Coronary Arteries: Insights From the ISCHEMIA Trial.

BACKGROUND: Ischemia with nonobstructive coronary arteries (INOCA) is common clinically, particularly among women, but its prevalence among patients with at least moderate ischemia and the relationship between ischemia severity and non-obstructive atherosclerosis severity are unknown. OBJECTIVES: The authors investigated predictors of INOCA in enrolled, nonrandomized participants in ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches), sex differences, and the relationship between ischemia and atherosclerosis in patients with INOCA. METHODS: Core laboratories independently reviewed screening noninvasive stress test results (nuclear imaging, echocardiography, magnetic resonance imaging or nonimaging exercise tolerance testing), and coronary computed tomography angiography (CCTA), blinded to results of the screening test. INOCA was defined as all stenoses <50% on CCTA in a patient with moderate or severe ischemia on stress testing. INOCA patients, who were excluded from randomization, were compared with randomized participants with ≥50% stenosis in ≥1 vessel and moderate or severe ischemia. RESULTS: Among 3,612 participants with core laboratory-confirmed moderate or severe ischemia and interpretable CCTA, 476 (13%) had INOCA. Patients with INOCA were younger, were predominantly female, and had fewer atherosclerosis risk factors. For each stress testing modality, the extent of ischemia tended to be less among patients with INOCA, particularly with nuclear imaging. There was no significant relationship between severity of ischemia and extent or severity of nonobstructive atherosclerosis on CCTA. On multivariable analysis, female sex was independently associated with INOCA (odds ratio: 4.2 [95% CI: 3.4-5.2]). CONCLUSIONS: Among participants enrolled in ISCHEMIA with core laboratory-confirmed moderate or severe ischemia, the prevalence of INOCA was 13%. Severity of ischemia was not associated with severity of nonobstructive atherosclerosis. (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches [ISCHEMIA]; NCT01471522).

Toxins and Other Bioactive Metabolites in Deep Chlorophyll Layers Containing the Cyanobacteria Planktothrix cf. isothrix in Two Georgian Bay Embayments, Lake Huron.

The understanding of deep chlorophyll layers (DCLs) in the Great Lakes-largely reported as a mix of picoplankton and mixotrophic nanoflagellates-is predominantly based on studies of deep (>30 m), offshore locations. Here, we document and characterize nearshore DCLs from two meso-oligotrophic embayments, Twelve Mile Bay (TMB) and South Bay (SB), along eastern Georgian Bay, Lake Huron (Ontario, Canada) in 2014, 2015, and 2018. Both embayments showed the annual formation of DCLs, present as dense, thin, metalimnetic plates dominated by the large, potentially toxic, and bloom-forming cyanobacteria Planktothrix cf. isothrix. The contribution of P. cf. isothrix to the deep-living total biomass (TB) increased as thermal stratification progressed over the ice-free season, reaching 40% in TMB (0.6 mg/L at 9.5 m) and 65% in South Bay (3.5 mg/L at 7.5 m) in 2015. The euphotic zone in each embayment extended down past the mixed layer, into the nutrient-enriched hypoxic hypolimnia, consistent with other studies of similar systems with DCLs. The co-occurrence of the metal-oxidizing bacteria Leptothrix spp. and bactivorous flagellates within the metalimnetic DCLs suggests that the microbial loop plays an important role in recycling nutrients within these layers, particularly phosphate (PO4) and iron (Fe). Samples taken through the water column in both embayments showed measurable concentrations of the cyanobacterial toxins microcystins (max. 0.4 µg/L) and the other bioactive metabolites anabaenopeptins (max. ~7 µg/L) and cyanopeptolins (max. 1 ng/L), along with the corresponding genes (max. in 2018). These oligopeptides are known to act as metabolic inhibitors (e.g., in chemical defence against grazers, parasites) and allow a competitive advantage. In TMB, the 2018 peaks in these oligopeptides and genes coincided with the P. cf. isothrix DCLs, suggesting this species as the main source. Our data indicate that intersecting physicochemical gradients of light and nutrient-enriched hypoxic hypolimnia are key factors in supporting DCLs in TMB and SB. Microbial activity and allelopathy may also influence DCL community structure and function, and require further investigation, particularly related to the dominance of potentially toxigenic species such as P. cf. isothrix.

Pan-Cancer Transcriptional Models Predicting Chemosensitivity in Human Tumors.

MOTIVATION: Despite increasing understanding of the molecular characteristics of cancer, chemotherapy success rates remain low for many cancer types. Studies have attempted to identify patient and tumor characteristics that predict sensitivity or resistance to different types of conventional chemotherapies, yet a concise model that predicts chemosensitivity based on gene expression profiles across cancer types remains to be formulated. We attempted to generate pan-cancer models predictive of chemosensitivity and chemoresistance. Such models may increase the likelihood of identifying the type of chemotherapy most likely to be effective for a given patient based on the overall gene expression of their tumor. RESULTS: Gene expression and drug sensitivity data from solid tumor cell lines were used to build predictive models for 11 individual chemotherapy drugs. Models were validated using datasets from solid tumors from patients. For all drug models, accuracy ranged from 0.81 to 0.93 when applied to all relevant cancer types in the testing dataset. When considering how well the models predicted chemosensitivity or chemoresistance within individual cancer types in the testing dataset, accuracy was as high as 0.98. Cell line-derived pan-cancer models were able to statistically significantly predict sensitivity in human tumors in some instances; for example, a pan-cancer model predicting sensitivity in patients with bladder cancer treated with cisplatin was able to significantly segregate sensitive and resistant patients based on recurrence-free survival times (P = .048) and in patients with pancreatic cancer treated with gemcitabine (P = .038). These models can predict chemosensitivity and chemoresistance across cancer types with clinically useful levels of accuracy.