Efficacy and safety of a 4-week course of repeated subcutaneous ketamine injections for treatment-resistant depression (KADS study): randomised double-blind active-controlled trial.

BACKGROUND: Prior trials suggest that intravenous racemic ketamine is a highly effective for treatment-resistant depression (TRD), but phase 3 trials of racemic ketamine are needed. AIMS: To assess the acute efficacy and safety of a 4-week course of subcutaneous racemic ketamine in participants with TRD. Trial registration: ACTRN12616001096448 at www.anzctr.org.au. METHOD: This phase 3, double-blind, randomised, active-controlled multicentre trial was conducted at seven mood disorders centres in Australia and New Zealand. Participants received twice-weekly subcutaneous racemic ketamine or midazolam for 4 weeks. Initially, the trial tested fixed-dose ketamine 0.5 mg/kg versus midazolam 0.025 mg/kg (cohort 1). Dosing was revised, after a Data Safety Monitoring Board recommendation, to flexible-dose ketamine 0.5-0.9 mg/kg or midazolam 0.025-0.045 mg/kg, with response-guided dosing increments (cohort 2). The primary outcome was remission (Montgomery-Åsberg Rating Scale for Depression score ≤10) at the end of week 4. RESULTS: The final analysis (those who received at least one treatment) comprised 68 in cohort 1 (fixed-dose), 106 in cohort 2 (flexible-dose). Ketamine was more efficacious than midazolam in cohort 2 (remission rate 19.6% v. 2.0%; OR = 12.1, 95% CI 2.1-69.2, P = 0.005), but not different in cohort 1 (remission rate 6.3% v. 8.8%; OR = 1.3, 95% CI 0.2-8.2, P = 0.76). Ketamine was well tolerated. Acute adverse effects (psychotomimetic, blood pressure increases) resolved within 2 h. CONCLUSIONS: Adequately dosed subcutaneous racemic ketamine was efficacious and safe in treating TRD over a 4-week treatment period. The subcutaneous route is practical and feasible.

Opinions Regarding Benzodiazepine Teaching and Prescribing Among Trainees in Psychiatry.

OBJECTIVES: Benzodiazepines are widely prescribed for a variety of symptoms and illnesses. There has been limited investigation on the training psychiatry residents receive regarding benzodiazepine prescribing. This study surveyed US psychiatric trainees about their didactic and clinical experience with benzodiazepines, investigating how experience with benzodiazepines may shape trainees' opinions and likelihood to prescribe. METHODS: The 14-question online survey was distributed to residents and fellows at US training programs through an invitation from their training directors. RESULTS: Of 466 programs contacted, with an estimated 1345 trainees, a total of 97 programs (20.8%) and 424 trainees (31.5%) responded. The analyses focused only on the 342 general psychiatry trainees who responded. Most trainees reported having formal didactics on benzodiazepines, and earlier training was correlated with higher trainee quality of instruction assessments (p < 0.01). Most trainees rated their instructors as Above or Well Above Average. Trainees cited the observation and opinion of supervisors as the two most important factors affecting likelihood of future benzodiazepine prescribing. Trainees commonly reported pressure from patients to prescribe benzodiazepines but were split on perceived pressure from supervisors about prescribing and whether a bias exists against prescribing at their program or in general. CONCLUSION: The survey indicated that psychiatry trainees generally feel adequately trained through didactic and clinical experience with benzodiazepines. Trainees perceived pressure by patients to prescribe benzodiazepines, but generally felt comfortable in managing benzodiazepine usage. Psychiatry attendings' opinions on benzodiazepines most impacted trainees. Influences on trainees' prescribing patterns are important variables that can impact future benzodiazepine prescribing.

Individual differences in the peripheral immune system promote resilience versus susceptibility to social stress.

Depression and anxiety disorders are associated with increased release of peripheral cytokines; however, their functional relevance remains unknown. Using a social stress model in mice, we find preexisting individual differences in the sensitivity of the peripheral immune system that predict and promote vulnerability to social stress. Cytokine profiles were obtained 20 min after the first social stress exposure. Of the cytokines regulated by stress, IL-6 was most highly up-regulated only in mice that ultimately developed a susceptible behavioral phenotype following a subsequent chronic stress, and levels remained elevated for at least 1 mo. We confirmed a similar elevation of serum IL-6 in two separate cohorts of patients with treatment-resistant major depressive disorder. Before any physical contact in mice, we observed individual differences in IL-6 levels from ex vivo stimulated leukocytes that predict susceptibility versus resilience to a subsequent stressor. To shift the sensitivity of the peripheral immune system to a pro- or antidepressant state, bone marrow (BM) chimeras were generated by transplanting hematopoietic progenitor cells from stress-susceptible mice releasing high IL-6 or from IL-6 knockout (IL-6(-/-)) mice. Stress-susceptible BM chimeras exhibited increased social avoidance behavior after exposure to either subthreshold repeated social defeat stress (RSDS) or a purely emotional stressor termed witness defeat. IL-6(-/-) BM chimeric and IL-6(-/-) mice, as well as those treated with a systemic IL-6 monoclonal antibody, were resilient to social stress. These data establish that preexisting differences in stress-responsive IL-6 release from BM-derived leukocytes functionally contribute to social stress-induced behavioral abnormalities.

Resting-state functional connectivity of the human habenula in healthy individuals: Associations with subclinical depression.

INTRODUCTION: The habenula (Hb) is postulated to play a critical role in reward and aversion processing across species, including humans, and has been increasingly implicated in depression. However, technical constraints have limited in vivo investigation of the human Hb, and its function remains poorly characterized. We sought to overcome these challenges by examining the whole-brain resting-state functional connectivity of the Hb and its possible relationship to depressive symptomatology using the high-resolution WU-Minn Human Connectome Project (HCP) dataset. METHODS: Anatomical and resting-state functional MRI data from 50 healthy subjects with low or high subclinical depression scores (n = 25 each) were analyzed. Using novel semi-automated segmentation and optimization techniques, we generated individual-specific Hb seeds and calculated whole-brain functional connectivity for the entire cohort and the contrast of high vs. low depression groups. RESULTS: In the entire cohort, the Hb exhibited significant connectivity with key brainstem structures (i.e., ventral tegmental area, substantia nigra, pons) as well as the anterior and posterior cingulate cortices, precuneus, thalamus, and sensorimotor cortex. Multiple regions showed differential Hb connectivity based on subclinical depression scores, including the amygdala, insula, and prefrontal, mid-cingulate, and entorhinal cortices. CONCLUSIONS: Hb connectivity findings converged on areas associated with salience processing, sensorimotor systems, and the default mode network. We also detected substantial Hb-brainstem connectivity, consistent with prior histological and animal research. High and low subclinical depression groups exhibited differences in Hb connectivity with multiple regions previously linked to depression, suggesting the relationship between these structures as a potential target for future research and treatment. Hum Brain Mapp 37:2369-2384, 2016. © 2016 Wiley Periodicals, Inc.

Effects of Low-Dose and Very Low-Dose Ketamine among Patients with Major Depression: a Systematic Review and Meta-Analysis.

BACKGROUND: Several recent trials indicate low-dose ketamine produces rapid antidepressant effects. However, uncertainty remains in several areas: dose response, consistency across patient groups, effects on suicidality, and possible biases arising from crossover trials. METHODS: A systematic search was conducted for relevant randomized trials in Medline, Embase, and PsycINFO databases up to August 2014. The primary endpoints were change in depression scale scores at days 1, 3 and 7, remission, response, suicidality, safety, and tolerability. Data were independently abstracted by 2 reviewers. Where possible, unpublished data were obtained on treatment effects in the first period of crossover trials. RESULTS: Nine trials were identified, including 201 patients (52% female, mean age 46 years). Six trials assessed low-dose ketamine (0.5 mg/kg i.v.) and 3 tested very low-dose ketamine (one trial assessed 50 mg intra-nasal spray, another assessed 0.1-0.4 mg/kg i.v., and another assessed 0.1-0.5 mg/kg i.v., intramuscular, or s.c.). At day 3, the reduction in depression severity score was less marked in the very low-dose trials (P homogeneity <.05) and among bipolar patients. In analyses excluding the second period of crossover trials, response rates at day 7 were increased with ketamine (relative risk 3.4, 95% CI 1.6-7.1, P=.001), as were remission rates (relative risk 2.6, CI 1.2-5.7, P=.02). The absolute benefits were large, with day 7 remission rates of 24% vs 6% (P=.02). Seven trials provided unpublished data on suicidality item scores, which were reduced on days 1 and 3 (both P<.01) but not day 7. CONCLUSION: Low-dose ketamine appears more effective than very low dose. There is substantial heterogeneity in clinical response, with remission among one-fifth of patients at 1 week but most others having benefits that are less durable. Larger, longer term parallel group trials are needed to determine if efficacy can be extended and to further assess safety.

Elevated prefrontal cortex GABA in patients with major depressive disorder after TMS treatment measured with proton magnetic resonance spectroscopy.

BACKGROUND: GABAergic and glutamatergic neurotransmitter systems are central to the pathophysiology of depression and are potential targets of repetitive transcranial magnetic stimulation (rTMS). We assessed the effect of 10-Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) of patients with major depressive disorder on the levels of medial prefrontal cortex (MPFC) γ-aminobutyric acid (GABA) and the combined resonance of glutamate and glutamine (Glx) as assessed in vivo with proton magnetic resonance spectroscopy ((1)H MRS). METHODS: Currently depressed individuals between the ages of 23 and 68 years participated in a 5-week naturalistic, open-label treatment study of rTMS, with (1)H MRS measurements of MPFC GABA and Glx levels at baseline and following 5 weeks of the rTMS intervention. We applied rTMS pulses over the left DLPFC at 10 Hz and 80%-120% of motor threshold for 25 daily sessions, with each session consisting of 3000 pulses. We assessed therapeutic response using the 24-item Hamilton Rating Scale for Depression (HAMD24). The GABA and Glx levels are expressed as ratios of peak areas relative to the area of the synchronously acquired and similarly fitted unsuppressed voxel water signal (W). RESULTS: Twenty-three currently depressed individuals (7 men) participated in the study. GABA/W in the MPFC increased 13.8% (p = 0.013) in all depressed individuals. There were no significant effects of rTMS on Glx/W. GABA/W and Glx/W were highly correlated in severely depressed patients at baseline but not after TMS. LIMITATIONS: The primary study limitations are the open-label design and the inclusion of participants currently taking stable regimens of antidepressant medications. CONCLUSION: These results implicate GABAergic and glutamatergic systems in the mechanism of action of rTMS for major depression, warranting further investigation in larger samples.

The impact of simulated patient death on medical students' stress response and learning of ACLS.

INTRODUCTION: There is considerable controversy as to whether the simulator should die during high-fidelity simulation (HFS). We sought to describe the physiologic and biochemical stress response induced by simulated patient death as well as the impact on long-term retention of Advanced Cardiovascular Life Support (ACLS) knowledge and skills. METHODS: Twenty-six subjects received an American Heart Association (AHA) ACLS provider course. Following the course, subjects participated in HFS and were randomized to simulated death or survival. Heart rate and salivary cortisol (SC) and dihydroepiandrosterone (DHEA) were collected at this time. Subjects returned six months later for a follow-up simulation in which ACLS knowledge and skills were tested. RESULTS: For all participants, there was an increase in heart rate during simulation compared with baseline heart rate (+ 32 beats/minute), p < 0.0001. Similarly, SC and DHEA were higher compared with baseline levels (+ 0.115 µg/dL, p <0.01 and + 97 pg/mL, p < 0.001, respectively). However, the only statistically significant difference between groups was an increase in heart rate response at the end of the simulation compared with baseline in the death group (+ 29.2 beats/minute versus + 18.5 beats/minute), p < 0.05. There was no difference on long-term knowledge or skills. CONCLUSIONS: Learners experience stress during high-fidelity simulation; however, there does not appear to be a readily detectable difference or negative response to a simulated patient death compared with simulated survival.

The Significance of the Default Mode Network (DMN) in Neurological and Neuropsychiatric Disorders: A Review.

The relationship of cortical structure and specific neuronal circuitry to global brain function, particularly its perturbations related to the development and progression of neuropathology, is an area of great interest in neurobehavioral science. Disruption of these neural networks can be associated with a wide range of neurological and neuropsychiatric disorders. Herein we review activity of the Default Mode Network (DMN) in neurological and neuropsychiatric disorders, including Alzheimer's disease, Parkinson's disease, Epilepsy (Temporal Lobe Epilepsy - TLE), attention deficit hyperactivity disorder (ADHD), and mood disorders. We discuss the implications of DMN disruptions and their relationship to the neurocognitive model of each disease entity, the utility of DMN assessment in clinical evaluation, and the changes of the DMN following treatment.

Dosing and effectiveness of ketamine anesthesia for electroconvulsive therapy (ECT): a case series.

OBJECTIVE: To provide additional data about the clinical efficacy and dosing range for ketamine used as the induction agent in electroconvulsive therapy (ECT). METHOD: We reviewed the clinical data in our academic hospital ECT service over the last four years for patients who had received ketamine as the sole, or adjunctive, anesthesia induction agent. We extracted clinical data about antidepressant response as well as absolute and weight-based dosing for ketamine. RESULTS: We found nine patients who were treated with ketamine as the anesthetic at some point during the course of their treatment (eight as the sole agent, one as adjunctive). The median induction dose for ketamine was 1.1 mg/kg. For most patients, there was demonstrable clinical benefit. CONCLUSIONS: Ketamine has a role as an alternative induction anesthetic agent in ECT. Our case series adds to the literature on the concomitant use of ECT and ketamine.

A Fully Remote Randomized Trial of Transcranial Alternating Current Stimulation for the Acute Treatment of Major Depressive Disorder.

Objective: Major depressive disorder (MDD) is common, but current treatment options have significant limitations in terms of access and efficacy. This study examined the effectiveness of transcranial alternating current stimulation (tACS) for the acute treatment of MDD.Methods: We performed a triple-blind, fully remote, randomized controlled trial comparing tACS with sham treatment. Adults aged 21-65 years meeting DSM 5 criteria for MDD and having a score on the Beck Depression Inventory, Second Edition (BDI-II), between 20 and 63 were eligible to participate. Participants utilized tACS or sham treatment for two 20-minute treatment sessions daily for 4 weeks. The primary outcome was change in BDI-II score from baseline to the week 2 time point in an intent-to treat analysis, followed by analyses of treatment-adherent participants. Secondary analyses examined change at the week 1 and 4 time points, responder rates, subgroup analyses, other self-report mood measures, and safety. The study was conducted from April to October 2022.Results: A total of 255 participants were randomized to active or sham treatment. Improvement in intent-to-treat analysis was not statistically significant at week 2 (P= .056), but there were significant effects in participants with high adherence (P= .005). Significantly greater improvement at week 1 (P= .020) and greater response at week 4 (P= .028) occurred following tACS. Improvements were significantly larger for female participants. There were no significant effects on secondary mood measures. Side effects were minimal and mild.Conclusions: Rapid, clinically significant improvement in depression in adults with MDD was associated with tACS, particularly for women. Compared to other depression therapies, tACS has 3 key advantages: rapid, clinically significant treatment effect, the ability of patients to use the treatment on their own at home, and the rarity and low impact of adverse events.Trial Registration: ClinicalTrials.gov identifier: NCT05384041.

Low-dose right unilateral electroconvulsive therapy (ECT): effectiveness of the first treatment.

BACKGROUND: Electroconvulsive therapy (ECT) is a widely used, highly effective antidepressant treatment. Except for the most severely ill patients, right unilateral (RUL) electrode placement is the most frequent initial treatment choice. In current practice, RUL ECT is administered at several multiples of seizure threshold (ST) based on reports that lower stimulus intensity results in lower response/remission rates. Many patients, as part of an initial dose titration to determine ST, will receive a single treatment with low-dose RUL ECT and subsequent treatments with a stimulus at a multiple of ST. OBJECTIVE: To assess response to the first ECT. METHODS: A retrospective analysis of charts from clinical practice at Mount Sinai Medical Center was performed. RESULTS: A single treatment with low-dose (presumably near ST) RUL ECT had a significant and immediate antidepressant effect in our sample of patients with major depression. We determined that this response is similar to that of patients receiving a single initial treatment with high-dose RUL ECT (at a multiple of ST). CONCLUSIONS: These data suggest, contrary to commonly held belief, that RUL ECT may be effective at a low stimulus dose. This argues against restimulating at 6 times ST in the initial session, based on the belief that the near-threshold seizure has no antidepressant efficacy. Our findings suggest a need for further investigation of cases in which low-dose RUL ECT may be an effective antidepressant treatment. Further prospective studies, including larger numbers of patients who receive randomized treatment with low- or high-dose RUL with longer follow-up, are indicated.

Transgenic expression of ZBP1 in neurons suppresses cocaine-associated conditioning.

To directly address whether regulating mRNA localization can influence animal behavior, we created transgenic mice that conditionally express Zipcode Binding Protein 1 (ZBP1) in a subset of neurons in the brain. ZBP1 is an RNA-binding protein that regulates the localization, as well as translation and stability of target mRNAs in the cytoplasm. We took advantage of the absence of ZBP1 expression in the mature brain to examine the effect of expressing ZBP1 on animal behavior. We constructed a transgene conditionally expressing a GFP-ZBP1 fusion protein in a subset of forebrain neurons and compared cocaine-cued place conditioning in these mice versus noninduced littermates. Transgenic ZBP1 expression resulted in impaired place conditioning relative to nonexpressing littermates, and acutely repressing expression of the transgene restored normal cocaine conditioning. To gain insight into the molecular changes that accounted for this change in behavior, we identified mRNAs that specifically immunoprecipitated with transgenic ZBP1 protein from the brains of these mice. These data suggest that RNA-binding proteins can be used as a tool to identify the post-transcriptional regulation of gene expression in the establishment and function of neural circuits involved in addiction behaviors.

Efficacy and Safety of Deep Transcranial Magnetic Stimulation for Obsessive-Compulsive Disorder: A Prospective Multicenter Randomized Double-Blind Placebo-Controlled Trial.

(Appeared originally in American Journal of Psychiatry 2019; 176:931-938) Reprinted with permission from American Psychiatric Association Publishing.

Deep Transcranial Magnetic Stimulation Combined With Brief Exposure for Posttraumatic Stress Disorder: A Prospective Multisite Randomized Trial.

BACKGROUND: Posttraumatic stress disorder (PTSD) is both prevalent and debilitating. While deep transcranial magnetic stimulation (dTMS) has shown preliminary efficacy, exposure therapy remains the most efficacious, though limited, treatment in PTSD. The medial prefrontal cortex (mPFC) is implicated in extinction learning, suggesting that concurrent mPFC stimulation may enhance exposure therapy. In this randomized controlled multicenter trial, the efficacy and safety of mPFC dTMS combined with a brief exposure procedure were studied in patients with PTSD. METHODS: Immediately following exposure to their trauma narrative, 125 outpatients were randomly assigned to receive dTMS or sham. Twelve sessions were administered over 4 weeks, with a primary end point of change in 5-week Clinician-Administered PTSD Scale for DSM-5 score. This clinical study did not include biological markers. RESULTS: Clinician-Administered PTSD Scale for DSM-5 score improved significantly in both groups at 5 weeks, though the improvement was smaller in the dTMS group (16.32) compared with the sham group (20.52; p = .027). At 9 weeks, improvement continued in Clinician-Administered PTSD Scale for DSM-5 score in both groups but remained smaller in dTMS (19.0) versus sham (24.4; p = .024). CONCLUSIONS: Both groups showed significant PTSD symptom improvement, possibly from the brief script-driven imagery exposure. While our design was unable to rule out placebo effects, the magnitude and durability of improvement suggest that repeated ultrabrief exposure therapy alone may be an effective treatment for PTSD, warranting additional study. The surprising and unexpected effect in the dTMS group also suggests that repeated mPFC stimulation with the H7 coil may interfere with trauma memory-mediated extinction. Our results provide new insight for dTMS approaches for possible future avenues to treat PTSD.

Double blind randomized controlled trial of deep brain stimulation for obsessive-compulsive disorder: Clinical trial design.

Obsessive-compulsive disorder (OCD), a leading cause of disability, affects ~1-2% of the population, and can be distressing and disabling. About 1/3 of individuals demonstrate poor responsiveness to conventional treatments. A small proportion of these individuals may be deep brain stimulation (DBS) candidates. Candidacy is assessed through a multidisciplinary process including assessment of illness severity, chronicity, and functional impact. Optimization failure, despite multiple treatments, is critical during screening. Few patients nationwide are eligible for OCD DBS and thus a multi-center approach was necessary to obtain adequate sample size. The study was conducted over a six-year period and was a NIH-funded, eight-center sham-controlled trial of DBS targeting the ventral capsule/ventral striatum (VC/VS) region. There were 269 individuals who initially contacted the sites, in order to achieve 27 participants enrolled. Study enrollment required extensive review for eligibility, which was overseen by an independent advisory board. Disabling OCD had to be persistent for ≥5 years despite exhaustive medication and behavioral treatment. The final cohort was derived from a detailed consent process that included consent monitoring. Mean illness duration was 27.2 years. OCD symptom subtypes and psychiatric comorbidities varied, but all had severe disability with impaired quality of life and functioning. Participants were randomized to receive sham or active DBS for three months. Following this period, all participants received active DBS. Treatment assignment was masked to participants and raters and assessments were blinded. The final sample was consistent in demographic characteristics and clinical features when compared to other contemporary published prospective studies of OCD DBS. We report the clinical trial design, methods, and general demographics of this OCD DBS sample.

Efficacy and Safety of Deep Transcranial Magnetic Stimulation for Obsessive-Compulsive Disorder: A Prospective Multicenter Randomized Double-Blind Placebo-Controlled Trial.

OBJECTIVE: Obsessive-compulsive disorder (OCD) is a chronic and disabling condition that often responds unsatisfactorily to pharmacological and psychological treatments. Converging evidence suggests a dysfunction of the cortical-striatal-thalamic-cortical circuit in OCD, and a previous feasibility study indicated beneficial effects of deep transcranial magnetic stimulation (dTMS) targeting the medial prefrontal cortex and the anterior cingulate cortex. The authors examined the therapeutic effect of dTMS in a multicenter double-blind sham-controlled study. METHODS: At 11 centers, 99 OCD patients were randomly allocated to treatment with either high-frequency (20 Hz) or sham dTMS and received daily treatments following individualized symptom provocation, for 6 weeks. Clinical response to treatment was determined using the Yale-Brown Obsessive Compulsive Scale (YBOCS), and the primary efficacy endpoint was the change in score from baseline to posttreatment assessment. Additional measures were response rates (defined as a reduction of ≥30% in YBOCS score) at the posttreatment assessment and after another month of follow-up. RESULTS: Eighty-nine percent of the active treatment group and 96% of the sham treatment group completed the study. The reduction in YBOCS score among patients who received active dTMS treatment was significantly greater than among patients who received sham treatment (reductions of 6.0 points and 3.3 points, respectively), with response rates of 38.1% and 11.1%, respectively. At the 1-month follow-up, the response rates were 45.2% in the active treatment group and 17.8% in the sham treatment group. Significant differences between the groups were maintained at follow-up. CONCLUSIONS: High-frequency dTMS over the medial prefrontal cortex and anterior cingulate cortex significantly improved OCD symptoms and may be considered as a potential intervention for patients who do not respond adequately to pharmacological and psychological interventions.

Rap1 couples cAMP signaling to a distinct pool of p42/44MAPK regulating excitability, synaptic plasticity, learning, and memory.

Learning-induced synaptic plasticity commonly involves the interaction between cAMP and p42/44MAPK. To investigate the role of Rap1 as a potential signaling molecule coupling cAMP and p42/44MAPK, we expressed an interfering Rap1 mutant (iRap1) in the mouse forebrain. This expression selectively decreased basal phosphorylation of a membrane-associated pool of p42/44MAPK, impaired cAMP-dependent LTP in the hippocampal Schaffer collateral pathway induced by either forskolin or theta frequency stimulation, decreased complex spike firing, and reduced the p42/44MAPK-mediated phosphorylation of the A-type potassium channel Kv4.2. These changes correlated with impaired spatial memory and context discrimination. These results indicate that Rap1 couples cAMP signaling to a selective membrane-associated pool of p42/44MAPK to control excitability of pyramidal cells, the early and late phases of LTP, and the storage of spatial memory.

Identification and testing of a gene expression signature of invasive carcinoma cells within primary mammary tumors.

We subjected cells collected using an in vivo invasion assay to cDNA microarray analysis to identify the gene expression profile of invasive carcinoma cells in primary mammary tumors. Expression of genes involved in cell division, survival, and cell motility were most dramatically changed in invasive cells indicating a population that is neither dividing nor apoptotic but intensely motile. In particular, the genes coding for the minimum motility machine that regulates beta-actin polymerization at the leading edge and, therefore, the motility and chemotaxis of carcinoma cells, were dramatically up-regulated. However, ZBP1, which restricts the localization of beta-actin, the substrate for the minimum motility machine, was down-regulated. This pattern of expression implicated ZBP1 as a suppressor of invasion. Reexpression of ZBP1 in metastatic cells with otherwise low levels of ZBP1 reestablished normal patterns of beta-actin mRNA targeting and suppressed chemotaxis and invasion in primary tumors. ZBP1 reexpression also inhibited metastasis from tumors. These experiments support the involvement in metastasis of the pathways identified in invasive cells, which are regulated by ZBP1.