A Preliminary Examination of the Role of Avoidance in Behavioral Activation Treatment Among Latinx Individuals.

Background: The current study examined the role of avoidance in behavioral activation treatment compared to a supportive counseling condition targeting depressive symptoms in a sample comprised of Latinx individuals. Method: Depressed Latinx individuals with Spanish-speaking preference (LSSP; N = 46) were randomized to receive 10-weekly sessions of Brief Behavioral Activation Treatment for Depression (BATD) or supportive counseling. Participants completed weekly self-report measures of depressive symptoms and avoidance. Results: Avoidance levels decreased over the course of both treatments. However, decreases in depressive symptoms were associated with decreases in avoidance over time only for individuals who were randomized to BATD. Greater change in avoidance levels was related to post-treatment depression score, only for those who received BATD. Finally, greater avoidance prior to commencing treatment predicted lower depressive symptom change over the course of both treatments. Conclusions: This study provides preliminary evidence that avoidance may be a specific proposed mechanism of depression change in BATD among LSSP with depression. Pretreatment avoidance appears to be a useful construct to identify the trajectories of depressive symptoms over the course of psychotherapy among LSSP.

Inhibition of METTL3 Results in a Cell-Intrinsic Interferon Response That Enhances Antitumor Immunity.

Therapies that enhance antitumor immunity have altered the natural history of many cancers. Consequently, leveraging nonoverlapping mechanisms to increase immunogenicity of cancer cells remains a priority. Using a novel enzymatic inhibitor of the RNA methyl-transferase METTL3, we demonstrate a global decrease in N6-methyladenosine (m6A) results in double-stranded RNA (dsRNA) formation and a profound cell-intrinsic interferon response. Through unbiased CRISPR screens, we establish dsRNA-sensing and interferon signaling are primary mediators that potentiate T-cell killing of cancer cells following METTL3 inhibition. We show in a range of immunocompetent mouse models that although METTL3 inhibition is equally efficacious to anti-PD-1 therapy, the combination has far greater preclinical activity. Using SPLINTR barcoding, we demonstrate that anti-PD-1 therapy and METTL3 inhibition target distinct malignant clones, and the combination of these therapies overcomes clones insensitive to the single agents. These data provide the mole-cular and preclinical rationale for employing METTL3 inhibitors to promote antitumor immunity in the clinic. SIGNIFICANCE: This work demonstrates that METTL3 inhibition stimulates a cell-intrinsic interferon response through dsRNA formation. This immunomodulatory mechanism is distinct from current immunotherapeutic agents and provides the molecular rationale for combination with anti-PD-1 immune-checkpoint blockade to augment antitumor immunity. This article is featured in Selected Articles from This Issue, p. 2109.

Discovery of a highly potent, selective, orally bioavailable inhibitor of KAT6A/B histone acetyltransferases with efficacy against KAT6A-high ER+ breast cancer.

KAT6A, and its paralog KAT6B, are histone lysine acetyltransferases (HAT) that acetylate histone H3K23 and exert an oncogenic role in several tumor types including breast cancer where KAT6A is frequently amplified/overexpressed. However, pharmacologic targeting of KAT6A to achieve therapeutic benefit has been a challenge. Here we describe identification of a highly potent, selective, and orally bioavailable KAT6A/KAT6B inhibitor CTx-648 (PF-9363), derived from a benzisoxazole series, which demonstrates anti-tumor activity in correlation with H3K23Ac inhibition in KAT6A over-expressing breast cancer. Transcriptional and epigenetic profiling studies show reduced RNA Pol II binding and downregulation of genes involved in estrogen signaling, cell cycle, Myc and stem cell pathways associated with CTx-648 anti-tumor activity in ER-positive (ER+) breast cancer. CTx-648 treatment leads to potent tumor growth inhibition in ER+ breast cancer in vivo models, including models refractory to endocrine therapy, highlighting the potential for targeting KAT6A in ER+ breast cancer.

Stressor-response functions as a generalizable model for context dependence.

Defining the context dependence of ecological states or processes is a fundamental goal of ecology. Stressor-response functions are the quantitative representation of context dependence, where the context (environmental contingency) is defined by location on the stressor (x) axis, and represents a unifying concept in biological science.

Inhibition of the CtBP complex and FBXO11 enhances MHC class II expression and anti-cancer immune responses.

There is increasing recognition of the prognostic significance of tumor cell major histocompatibility complex (MHC) class II expression in anti-cancer immunity. Relapse of acute myeloid leukemia (AML) following allogeneic stem cell transplantation (alloSCT) has recently been linked to MHC class II silencing in leukemic blasts; however, the regulation of MHC class II expression remains incompletely understood. Utilizing unbiased CRISPR-Cas9 screens, we identify that the C-terminal binding protein (CtBP) complex transcriptionally represses MHC class II pathway genes, while the E3 ubiquitin ligase complex component FBXO11 mediates degradation of CIITA, the principal transcription factor regulating MHC class II expression. Targeting these repressive mechanisms selectively induces MHC class II upregulation across a range of AML cell lines. Functionally, MHC class II+ leukemic blasts stimulate antigen-dependent CD4+ T cell activation and potent anti-tumor immune responses, providing fundamental insights into the graft-versus-leukemia effect. These findings establish the rationale for therapeutic strategies aimed at restoring tumor-specific MHC class II expression to salvage AML relapse post-alloSCT and also potentially to enhance immunotherapy outcomes in non-myeloid malignancies.

Non-genetic determinants of malignant clonal fitness at single-cell resolution.

All cancers emerge after a period of clonal selection and subsequent clonal expansion. Although the evolutionary principles imparted by genetic intratumour heterogeneity are becoming increasingly clear1, little is known about the non-genetic mechanisms that contribute to intratumour heterogeneity and malignant clonal fitness2. Here, using single-cell profiling and lineage tracing (SPLINTR)-an expressed barcoding strategy-we trace isogenic clones in three clinically relevant mouse models of acute myeloid leukaemia. We find that malignant clonal dominance is a cell-intrinsic and heritable property that is facilitated by the repression of antigen presentation and increased expression of the secretory leukocyte peptidase inhibitor gene (Slpi), which we genetically validate as a regulator of acute myeloid leukaemia. Increased transcriptional heterogeneity is a feature that enables clonal fitness in diverse tissues and immune microenvironments and in the context of clonal competition between genetically distinct clones. Similar to haematopoietic stem cells3, leukaemia stem cells (LSCs) display heritable clone-intrinsic properties of high, and low clonal output that contribute to the overall tumour mass. We demonstrate that LSC clonal output dictates sensitivity to chemotherapy and, although high- and low-output clones adapt differently to therapeutic pressure, they coordinately emerge from minimal residual disease with increased expression of the LSC program. Together, these data provide fundamental insights into the non-genetic transcriptional processes that underpin malignant clonal fitness and may inform future therapeutic strategies.

Pharmacologic Reduction of Mitochondrial Iron Triggers a Noncanonical BAX/BAK-Dependent Cell Death.

Cancer cell metabolism is increasingly recognized as providing an exciting therapeutic opportunity. However, a drug that directly couples targeting of a metabolic dependency with the induction of cell death in cancer cells has largely remained elusive. Here we report that the drug-like small-molecule ironomycin reduces the mitochondrial iron load, resulting in the potent disruption of mitochondrial metabolism. Ironomycin promotes the recruitment and activation of BAX/BAK, but the resulting mitochondrial outer membrane permeabilization (MOMP) does not lead to potent activation of the apoptotic caspases, nor is the ensuing cell death prevented by inhibiting the previously established pathways of programmed cell death. Consistent with the fact that ironomycin and BH3 mimetics induce MOMP through independent nonredundant pathways, we find that ironomycin exhibits marked in vitro and in vivo synergy with venetoclax and overcomes venetoclax resistance in primary patient samples. SIGNIFICANCE: Ironomycin couples targeting of cellular metabolism with cell death by reducing mitochondrial iron, resulting in the alteration of mitochondrial metabolism and the activation of BAX/BAK. Ironomycin induces MOMP through a different mechanism to BH3 mimetics, and consequently combination therapy has marked synergy in cancers such as acute myeloid leukemia. This article is highlighted in the In This Issue feature, p. 587.

Clinical MDR1 inhibitors enhance Smac-mimetic bioavailability to kill murine LSCs and improve survival in AML models.

The specific targeting of inhibitor of apoptosis (IAP) proteins by Smac-mimetic (SM) drugs, such as birinapant, has been tested in clinical trials of acute myeloid leukemia (AML) and certain solid cancers. Despite their promising safety profile, SMs have had variable and limited success. Using a library of more than 5700 bioactive compounds, we screened for approaches that could sensitize AML cells to birinapant and identified multidrug resistance protein 1 inhibitors (MDR1i) as a class of clinically approved drugs that can enhance the efficacy of SM therapy. Genetic or pharmacological inhibition of MDR1 increased intracellular levels of birinapant and sensitized AML cells from leukemia murine models, human leukemia cell lines, and primary AML samples to killing by birinapant. The combination of clinical MDR1 and IAP inhibitors was well tolerated in vivo and more effective against leukemic cells, compared with normal hematopoietic progenitors. Importantly, birinapant combined with third-generation MDR1i effectively killed murine leukemic stem cells (LSCs) and prolonged survival of AML-burdened mice, suggesting a therapeutic opportunity for AML. This study identified a drug combination strategy that, by efficiently killing LSCs, may have the potential to improve outcomes in patients with AML.

HBO1 is required for the maintenance of leukaemia stem cells.

Acute myeloid leukaemia (AML) is a heterogeneous disease characterized by transcriptional dysregulation that results in a block in differentiation and increased malignant self-renewal. Various epigenetic therapies aimed at reversing these hallmarks of AML have progressed into clinical trials, but most show only modest efficacy owing to an inability to effectively eradicate leukaemia stem cells (LSCs)1. Here, to specifically identify novel dependencies in LSCs, we screened a bespoke library of small hairpin RNAs that target chromatin regulators in a unique ex vivo mouse model of LSCs. We identify the MYST acetyltransferase HBO1 (also known as KAT7 or MYST2) and several known members of the HBO1 protein complex as critical regulators of LSC maintenance. Using CRISPR domain screening and quantitative mass spectrometry, we identified the histone acetyltransferase domain of HBO1 as being essential in the acetylation of histone H3 at K14. H3 acetylated at K14 (H3K14ac) facilitates the processivity of RNA polymerase II to maintain the high expression of key genes (including Hoxa9 and Hoxa10) that help to sustain the functional properties of LSCs. To leverage this dependency therapeutically, we developed a highly potent small-molecule inhibitor of HBO1 and demonstrate its mode of activity as a competitive analogue of acetyl-CoA. Inhibition of HBO1 phenocopied our genetic data and showed efficacy in a broad range of human cell lines and primary AML cells from patients. These biological, structural and chemical insights into a therapeutic target in AML will enable the clinical translation of these findings.

A Behavioral Activation Mobile Health App for Smokers With Depression: Development and Pilot Evaluation in a Single-Arm Trial.

BACKGROUND: The integration of Behavioral Activation Treatment for Depression (BAT-D) into smoking cessation interventions is a promising approach to address depression as a barrier to quitting. However, this approach has only been tested as a face-to-face intervention, which has low reach. OBJECTIVE: The aims of the study were to develop a BAT-D mobile health app with high potential reach and determine its feasibility, acceptability, and preliminary effects on theory-based behavioral processes of behavioral activation, reduced depressive symptoms, and smoking cessation. METHODS: Following a user-centered design process consisting of competitive analysis, focus groups, and prototype testing, we conducted a single-arm pilot trial of Actify!, a BAT-D app for depressed smokers. Participants used SmokefreeTXT along with Actify! to provide cessation content that had not yet been built into the app for this initial phase of pilot testing. Participants in the trial were current, daily smokers with mild to moderate depressive symptoms. We examined use outcomes for all enrolled participants and process and cessation outcomes at 6 weeks postenrollment for study completers (16/17, 94% retention). RESULTS: Regarding acceptability, average number of log-ins per participant was 16.6 (SD 13.7), and 63% (10/16) reported being satisfied overall with the app. Posttreatment interviews identified some usability challenges (eg, high perceived burden of planning and scheduling values-based activities). There was a significant decrease in depressive symptoms from baseline to follow-up (mean change in Patient Health Questionnaire-9 scores was -4.5, 95% CI -7.7 to -1.3; P=.01). Additionally, carbon monoxide (CO)-confirmed, 7-day point prevalence abstinence (PPA) at 6-week follow-up was 31% (5/16), and the 30-day PPA was 19% (3/16). CONCLUSIONS: Results demonstrate promising engagement with Actify! and potential for impact on theory-based change processes and cessation outcomes. Preliminary quit rates compare favorably to previous trials of smoking cessation apps for the general population (ie, short-term, self-reported 30-day quit rates in the 8% to 18% range) and a previous trial of face-to-face BAT-D for depressed smokers (ie, CO-confirmed, 7-day PPA rate of 17% at end of treatment).

Targeting enhancer switching overcomes non-genetic drug resistance in acute myeloid leukaemia.

Non-genetic drug resistance is increasingly recognised in various cancers. Molecular insights into this process are lacking and it is unknown whether stable non-genetic resistance can be overcome. Using single cell RNA-sequencing of paired drug naïve and resistant AML patient samples and cellular barcoding in a unique mouse model of non-genetic resistance, here we demonstrate that transcriptional plasticity drives stable epigenetic resistance. With a CRISPR-Cas9 screen we identify regulators of enhancer function as important modulators of the resistant cell state. We show that inhibition of Lsd1 (Kdm1a) is able to overcome stable epigenetic resistance by facilitating the binding of the pioneer factor, Pu.1 and cofactor, Irf8, to nucleate new enhancers that regulate the expression of key survival genes. This enhancer switching results in the re-distribution of transcriptional co-activators, including Brd4, and provides the opportunity to disable their activity and overcome epigenetic resistance. Together these findings highlight key principles to help counteract non-genetic drug resistance.

Mental health stigma in depressed Latinos over the course of therapy: Results from a randomized controlled trial.

OBJECTIVE: The current study examined the course, correlates, and predictors of mental health stigma among depressed, Spanish-speaking Latinos that were receiving treatment. This population faces significant disparities in mental health treatment and carries high levels of mental health stigma. METHOD: The study utilized data generated from a randomized clinical trial (N = 46) that evaluated the efficacy of Behavioral Activation and Supportive Counseling for depression among Latinos. RESULTS: Mental health stigma decreased over time; these decreases were more pronounced among individuals who were randomized to Supportive Counseling. Mental health stigma was positively associated with depressive symptoms and therapeutic alliance over time. Mental health stigma was not related to treatment attrition. CONCLUSIONS: These preliminary findings indicate that mental health stigma continues to be relevant among individuals who are actively participating in treatment. Receiving mental health treatment may be sufficient to dispel some of the stigmatizing views endorsed by underserved clinical populations.

Distress Tolerance Interacts With Negative Life Events to Predict Depressive Symptoms Across Adolescence.

Adolescence is a vulnerable period for the development of depressive disorders. Recent research has demonstrated the importance of distress tolerance in the onset and maintenance of depression during adulthood; however, little is known about its role in predicting depressive symptoms among adolescents. The current study examines the effect of distress tolerance and co-occurring negative life events on the developmental trajectory of depressive symptoms from middle to late adolescence. Our sample included 117 adolescent boys and girls (44.4% female, 54.6% White). Participants were, on average, 16 years old at baseline (SD = 0.90) and completed self-report inventories of negative life events and depressive symptoms; distress tolerance was assessed using a behavioral measure. Utilizing a latent growth curve approach, we found a significant interaction between distress tolerance and negative life events in predicting increases in depressive symptoms over time. Follow-up analyses suggest that negative life events were associated with greater increases in depressive symptoms over time for adolescents with lower levels of distress tolerance only. The study highlights the moderating role of distress intolerance in the relation between negative life events and depressive symptoms, and underscores the importance of targeting distress tolerance for treating depression among youth.

Early psychosocial deprivation and adolescent risk-taking: The role of motivation and executive control.

Risk-taking in adolescence has been often associated with early life adversities. However, the impact of such macrolevel factors on risk behavior has been rarely studied in humans. To address these gaps we recruited a sample of young adolescents who were part of a randomized control trial of foster care. Children institutionalized at or soon after birth were randomly assigned either to be removed from institutions and placed into a family or foster care intervention or to remain in institutions receiving care as usual. These children were subsequently followed up through 12 years of age and compared with a sample of children who had never been institutionalized. Using this sample, we examined the impact of early childhood deprivation on risk-taking behavior and explored the role of motivation (i.e., sensation seeking) and executive control (i.e., planning). Early psychosocial deprivation decreased engagement in risk-taking among young adolescents by reducing sensation seeking, a motivation often associated with risk-taking in adolescence. The impact of early psychosocial deprivation on sensation seeking and consequently on engagement in risk-taking was further reduced by its deleterious effects on executive control. These findings challenge the traditional view according to which risk behavior is a maladaptive response to adversities and suggest that it may represent adolescents' attempts to fulfill important motivations. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

An experimental paradigm examining the influence of frustration on risk-taking behavior.

The present study examined the impact of frustration on risk-taking in college students with low and high ADHD symptomatology (L-ADHD and H-ADHD). Participants completed the Balloon Analogue Risk Task (BART) following induced frustration from a mood manipulation task (experimental session) and following no mood manipulation (control session). A manipulation check revealed a significant three-way interaction where the H-ADHD group reported higher frustration levels compared to the L-ADHD group, particularly in response to the frustration induction in the experimental condition. Primary results revealed that the L-ADHD group exploded significantly fewer balloons in the experimental condition compared to the control condition; there was a nonsignificant difference of balloon explosions across conditions for the H-ADHD group. The study provides initial laboratory-based support for the impact of frustration on the risk behavior of those with low and high levels of ADHD, with potential implications for future studies and ultimately for intervention.

Characterization of TCDD-inducible poly-ADP-ribose polymerase (TIPARP/ARTD14) catalytic activity.

Here, we report the biochemical characterization of the mono-ADP-ribosyltransferase 2,3,7,8-tetrachlorodibenzo-p-dioxin poly-ADP-ribose polymerase (TIPARP/ARTD14/PARP7), which is known to repress aryl hydrocarbon receptor (AHR)-dependent transcription. We found that the nuclear localization of TIPARP was dependent on a short N-terminal sequence and its zinc finger domain. Deletion and in vitro ADP-ribosylation studies identified amino acids 400-657 as the minimum catalytically active region, which retained its ability to mono-ADP-ribosylate AHR. However, the ability of TIPARP to ADP-ribosylate and repress AHR in cells was dependent on both its catalytic activity and zinc finger domain. The catalytic activity of TIPARP was resistant to meta-iodobenzylguanidine but sensitive to iodoacetamide and hydroxylamine, implicating cysteines and acidic side chains as ADP-ribosylated target residues. Mass spectrometry identified multiple ADP-ribosylated peptides in TIPARP and AHR. Electron transfer dissociation analysis of the TIPARP peptide 33ITPLKTCFK41 revealed cysteine 39 as a site for mono-ADP-ribosylation. Mutation of cysteine 39 to alanine resulted in a small, but significant, reduction in TIPARP autoribosylation activity, suggesting that additional amino acid residues are modified, but loss of cysteine 39 did not prevent its ability to repress AHR. Our findings characterize the subcellular localization and mono-ADP-ribosyltransferase activity of TIPARP, identify cysteine as a mono-ADP-ribosylated residue targeted by this enzyme, and confirm the TIPARP-dependent mono-ADP-ribosylation of other protein targets, such as AHR.

Sex Differences in the Association between Heavy Drinking and Behavioral Distress Tolerance and Emotional Reactivity Among Non-Depressed College Students.

BACKGROUND: Heavy episodic drinking (HED) is a common behavior among college students that is associated with severe negative consequences. Negative reinforcement processes have been applied to elucidate mechanisms underlying relationships between consumption of alcohol and the desire to alleviate negative feelings. Distress tolerance (DT) and emotional reactivity are two mechanisms that are consistent with the self-medication model that may contribute to HED. The current study investigated relationships between DT, emotional reactivity, defined as frustration reactivity and irritability reactivity, and HED in a non-depressed college population. Given differential patterns of consumption and motivation for drinking between males and females, sex differences were also examined. SHORT SUMMARY: The study examined two constructs consistent with negative reinforcement processes, behavioral distress tolerance (DT) and emotional reactivity (frustration reactivity and irritability reactivity), to explain heavy episodic drinking (HED) among non-depressed college students. Behavioral DT and frustration reactivity independently predicted HED. Higher HED was associated with higher frustration reactivity and lower behavioral DT in women, but nor in men. METHODS: One-hundred-ten college students without depressive symptoms completed alcohol use measures and the Paced Auditory Serial Attention Task (PASAT-C) to assess behavioral DT and emotional reactivity. RESULTS: DT and frustration reactivity independently predicted HED. The association between DT and HED was moderated by sex such that higher levels of DT predicted higher HED among females, but not among males. Higher frustration reactivity scores were associated with a greater number of HED. CONCLUSIONS: Results provide supporting evidence that DT and emotional reactivity are distinct factors, and that they predict HED independently. Results underscore the importance of examining sex differences when evaluating the association between HED and negative reinforcement processes in this population.

Risk-Taking Propensity in Older Adolescents: Internalizing Symptoms, Gender, and Negative Reinforcement.

OBJECTIVE: Engagement in risk behaviors, including substance use, risky sex, and violence, tends to increase throughout adolescence into young adulthood. One motivational process that may underlie risk behaviors during adolescence is negative reinforcement. Moreover, gender and internalizing symptoms (e.g., depression and anxiety) may both convey risk for negative reinforcement-based risk taking. Along these lines, the aims of the current study were to (a) examine gender differences in negative reinforcement-based risk-taking propensity and (b) examine internalizing symptoms as a moderator of the relationship between gender and negative reinforcement-based risk-taking propensity. METHOD: Participants included 103 youth between the ages of 18 and 21 (50.49% female, age M(SD) = 19.41(1.06)) who were recruited from a large Mid-Atlantic university between September 2013 and November 2014. Participants completed self-report assessments of internalizing symptomatology and a computerized behavioral analog assessment of negative reinforcement-based risk-taking propensity. RESULTS: Results indicated that, overall, female older adolescents were riskier under conditions of negative reinforcement than male older adolescents. In addition, internalizing symptoms significantly moderated the relationship between gender and negative reinforcement-based risk-taking propensity such that the relationship between gender and negative reinforcement-based risk-taking propensity was nonsignificant at high levels of internalizing symptoms, and female gender was significantly positively predictive of heightened negative reinforcement-based risk-taking propensity at low levels of internalizing symptoms. CONCLUSIONS: Thus, although female youth overall were riskier, the predictive utility of gender for negative reinforcement-based risk taking may be most relevant at low levels of internalizing symptoms. Results are discussed in terms of implications for future prevention and intervention.

Native freshwater species get out of the way: Prussian carp (Carassius gibelio) impacts both fish and benthic invertebrate communities in North America.

Prussian carp (Carassius gibelio) are one of the most noxious non-native species in Eurasia. Recently, Prussian carp, a non-native freshwater fish species, were genetically confirmed in Alberta, Canada and have been rapidly expanding their range in North America since establishment. Given their rapid range expansion, there is an increasing need to determine how Prussian carp may impact native species. We assessed the severity of the Prussian carp invasion by (i) determining their impact on fish communities, (ii) assessing their impact on benthic invertebrate communities, (iii) evaluating if Prussian carp alter abiotic conditions, and (iv) identifying where we find higher abundances of Prussian carp. When Prussian carp were established, we found significant changes to the fish community. Correspondingly, the degree of impact to benthic invertebrate communities was related to the stage of invasion (none, early or recent), where changes in fish communities were significantly concordant with changes in benthic invertebrate communities. Finally, we found that higher abundances of Prussian carp were significantly associated with lower abundances of a majority of native fish species. Altogether, using three lines of evidence, we determine that Prussian carp can have wide-ranging impacts on freshwater ecosystems in North America, pressing the need for management intervention.

Survival of the Fittest: Darwinian Selection Underpins Chemotherapy Resistance in AML.

Intratumor heterogeneity driving therapeutic resistance is a major challenge in cancer management. Recently in Nature, Shlush et al. (2017) provide a tour de force of genomics coupled to functional assays to demonstrate that resistance emerges from a pre-existing subpopulation of acute myeloid leukemia (AML) cells with a stem cell transcription program.