Background/Objectives: Antimicrobial resistance (AMR) is an escalating global threat driven by antibiotic misuse and bacterial adaptation. Efflux pumps are major contributors to multidrug resistance in Escherichia coli, as they expel antibiotics and reduce their intracellular activity. This study examined efflux-mediated resistance in extended-spectrum beta-lactamase (ESBL)-producing E. coli and evaluated the potential of several efflux pump inhibitors (EPIs)-promethazine (PMZ), thioridazine (TZ), carbonyl cyanide m-chlorophenyl hydrazine (CCCP), reserpine (RES), and phenyl-arginine-β-naphthylamide (PAβN)-as therapeutic adjuncts. Methods: Antibacterial and anti-biofilm activities of EPIs were tested using broth microdilution, real-time fluorimetry, and crystal violet assays, while ceftriaxone-PMZ interactions were assessed by checkerboard analysis. Results: TZ and CCCP showed strain-specific antibacterial activity, whereas PMZ, RES, and PAβN did not exert any effect. PMZ, TZ, and especially CCCP effectively inhibited efflux pump function, while RES and PAβN were less active. Biofilm inhibition varied between strains, with PMZ and TZ producing moderate reductions. We observed a quite weak synergism between ciprofloxacin, ceftriaxone, and PMZ; however, the result was not significant. Conclusions: Overall, the results highlight the central role of efflux pumps in ESBL-producing E. coli and indicate that EPIs can reverse resistance (e.g., PMZ) and exhibit potent anti-biofilm activity and show additive interactions with antibiotics. However, further studies are needed to optimize their safety, pharmacokinetics, and antibiotic pairing for potential clinical use.

BRAF-targeted therapy is a promising strategy for thyroid cancer. However, its efficacy is limited by drug resistance. This study elucidates the role of fatty acid oxidation (FAO) in mediating adaptive resistance to BRAF[V600E] inhibition (BRAFi) in thyroid cancer. Through integrated transcriptomic and metabolomic analyses, we demonstrate that BRAFi by vemurafenib (PLX4032) significantly enhances FAO in thyroid cancer cells. The pharmacological inhibition of FAO via thioridazine (Thio) synergizes with BRAFi to suppress tumor growth in vitro, in vivo and in a patient-derived organoid. Mechanistically, this metabolic shift is driven by the upregulation of PGC1α, which enhances FAO. The consequent increase in intracellular acetyl-CoA reprograms the histone H3K9 acetylation (H3K9ac) landscape, thereby epigenetically activating pro-survival genes such as RUNX1. In addition, higher expression of RUNX1 correlates with poorer prognosis in thyroid cancer. Consistently, functional studies confirm RUNX1's oncogenic role, as its knockdown reduces cell proliferation, migration, and invasion. In conclusion, our work reveals a metabolic-epigenetic axis underlying adaptive response to BRAFi and identifies RUNX1 as a novel oncogene in thyroid cancer.

Thioridazine is an antipsychotic used in the treatment of schizophrenia and psychosis. Its use is reserved for patients who have failed to respond to or cannot tolerate other antipsychotics. Thioridazine has been shown to prolong the QT interval (the time taken for the heart ventricles to depolarize and repolarize) in a dose related manner. Drugs with this potential have been associated with the life-threatening ventricular tachycardia, “torsades de pointes”. The CYP2D6 enzyme is involved in metabolizing thioridazine. About 7% of the population has reduced enzyme activity because of variants in the CYP2D6 gene. In individuals with low CYP2D6 activity, standard doses of thioridazine may lead to higher drug levels in the plasma, and increase the risk of cardiac arrhythmias. The FDA-approved drug label for thioridazine states that thioridazine is contraindicated in individuals who are known to have reduced levels of CYP2D6 activity. The label also states it is contraindicated to coadminister thioridazine with drugs that inhibit CYP2D6 (e.g., fluoxetine, paroxetine) or inhibit the metabolism of thioridazine (e.g., fluvoxamine, propranolol, and pindolol) (1).

To develop an LC-MS/MS method for simultaneous quantification of thioridazine and its metabolites in rat plasma, samples were prepared by protein precipitation and filtration using thioridazine-d3 as an internal standard. Chromatographic separation was achieved on a reversed-phase C18 UPLC column with 0.1% formic acid in acetonitrile and 10-mM ammonium acetate in water at 0.7 mL/min. Quantification was performed using multiple reaction monitoring in positive ion mode with the following precursor-product ion transitions: m/z 371.1 → 126.1 (thioridazine), m/z 387.1 → 126.1 (mesoridazine), m/z 403.1 → 126.1 (thioridazine-2-sulfone), m/z 387.2 → 126.1 (thioridazine-5-sulfoxide), and 374.1 → 129.1 (thioridazine-d3). This method showed good linearity: 0.1-1000 ng/mL for thioridazine (r2 = 0.9980) and 0.5-1000 ng/mL for mesoridazine (r2 = 0.9981), thioridazine-2-sulfone (r2 = 0.9976), and thioridazine-5-sulfoxide (r2 = 0.9967). The accuracy of the LLOQ and QC samples for thioridazine and its metabolites was within 85%-115%, with intrabatch and interbatch precisions (CV%) below 15%. The average recovery ranged from 98% to 109%, and no significant matrix effect was observed, with values ranging from 93% to 110%. All analytes were stable under the conditions used in this study. This method was applied in a pharmacokinetic study following the intravenous administration of thioridazine to rats.

Background/Objectives: Urinary tract infections (UTIs) represent a major healthcare challenge due to antimicrobial resistance and biofilm formation. Our aim was to evaluate whether repurposed drugs and efflux pump inhibitors (EPIs) could provide alternative strategies by investigating their antibacterial, anti-biofilm, and resistance-modifying properties against Gram-negative uropathogens under varying pH conditions. Methods: Clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis were tested. Minimum inhibitory concentrations (MICs) of thioridazine (TZ), promethazine (PMZ), fluoxetine (Fx), sertraline (Sr), phenylalanine arginine β-naphthylamide (PAβN), carbonyl cyanide m-chlorophenyl hydrazone (CCCP), and the glutamine uptake inhibitor V9302 were determined at pH 5-8. Biofilm inhibition was assessed by crystal violet staining, while MIC reduction assays tested antibiotic combinations. Efflux pump inhibition was examined using an ethidium bromide accumulation assay. Results: TZ reduced biofilm formation in sensitive K. pneumoniae at all pH levels and enhanced ciprofloxacin (CIP) activity, whereas PMZ showed a weaker effect, limited mainly to neutral pH. Fx and Sr exhibited pH-dependent anti-biofilm activity, with Fx particularly effective against P. mirabilis at alkaline pH. PAβN consistently decreased biofilm biomass in both sensitive and resistant K. pneumoniae and, at pH 7-8, potentiated CIP activity with a 16-fold MIC reduction in the sensitive strain. CCCP showed pH-dependent activity, with stronger effects under acidic conditions, notably in E. coli and P. mirabilis. V9302 was a potent biofilm inhibitor in K. pneumoniae and resistant E. coli and interfered with efflux activity, showing strong effects in acidic environments. Conclusions: Repurposed drugs and EPIs may be useful as antibiotic adjuvants or biofilm inhibitors in treating resistant UTIs.

Recent years have provided numerous reports on the mechanisms of action of psychiatric medications (antidepressants, antipsychotics, mood stabilizers, and antidementia drugs) that directly inhibit the growth of cancer cells, as well as on their indirect effects on the psyche and immune system, and their supportive effects on chemotherapeutic agents. The mechanisms of the anticancer activity of psychiatric drugs include inhibition of dopamine and N-methyl-D-aspartate receptors that work via signaling pathways (PI3K/AKT/mTOR/NF-κB, ERK, Wnt/β-catenin, and bcl2), metabolic pathways (ornithine decarboxylase, intracellular cholesterol transport, lysosomal enzymes, and glycolysis), autophagy, Ca2+-dependent signaling cascades, and various other proteins (actin-related protein complex, sirtuin 1, p21, p53, etc.). The anticancer potential of psychiatric drugs seems to be extremely broad, and the most extensive anticancer literature has been reported on antidepressants (fluoxetine, amitriptyline, imipramine, mirtazapine, and St John's Wort) and antipsychotics (chlorpromazine, pimozide, thioridazine, and trifluoperazine). Among mood stabilizers, lithium and valproates have the largest body of literature. Among antidementia drugs, memantine has documented anticancer effects, while there is limited evidence for galantamine. Of the new psychiatric substances, the antipsychotic drug brexpiprazole and the antidepressant vortioxetine have a very interesting body of literature regarding glioblastoma, based on in vitro and in vivo animal survival studies. Their use in brain tumors and metastases is particularly compelling, as these substances readily cross the blood-brain barrier (BBB). Moreover, the synergistic effect of psychiatric drugs with traditional cancer treatment seems to be extremely important in the fight against chemo- and radio-resistance of tumors. Although there are some studies describing the possible carcinogenic effects of psychiatric drugs in animals, the anticancer effect seems to be extremely significant, especially in combination treatment with radio/chemotherapy. The emerging evidence supporting the anticancer properties of psychiatric drugs presents an exciting frontier in oncology. The anticancer properties of psychiatric drugs may prove particularly useful in the period between chemotherapy and radiotherapy sessions to maintain the tumor-inhibitory effect. While further research is necessary to elucidate the mechanisms, clinical implications, dose-dependence of the effect, and clear guidelines for the use of psychiatric medications in cancer therapy, the potential for these commonly prescribed medications to contribute to cancer treatment enhances their value in the management of patients facing the dual challenges of mental health and cancer.

Phenothiazine derivatives have been used for decades as antipsychotic drugs in multiple mental health and physical conditions treatment (schizophrenia, mania in bipolar disorder, and psychosis). Epidemiological studies have shown that people with schizophrenia are less likely to suffer from cancer, which indicates the ability of antipsychotics to inhibit the development of cancer cells. It is our third review about the impact of phenothiazine derivatives on cell death. Here, we focused on apoptosis. We selected 92 papers that investigated the effect of phenothiazine derivatives on the apoptosis process in normal and cancer cell lines. Chlorpromazine, fluphenazine, levomepromazine, mepazine, perphenazine, promazine, promethazine, thioridazine, trifluoperazine, and trifluoperazine analog (3dc) more often induce apoptosis in cancer cell lines, human hepatocytes, and lymphocytes, and the final effect depends on the type and concentration of drug used, the type of cell line, and the methodology used. The obtained results allow for a better understanding of the biological action of phenothiazine derivatives and will help reposition this group of drugs to cancer treatment, resulting in faster, safer, easier, and cheaper therapy.

Craniofacial development is a complex, highly conserved process involving multiple tissue types and molecular pathways, with perturbations resulting in congenital defects that often require invasive surgical interventions to correct. Remarkably, some species, such as Xenopus laevis, can correct some craniofacial abnormalities during pre-metamorphic stages through thyroid hormone-independent mechanisms. However, the full scope of factors mediating remodeling initiation and coordination remain unclear. This study explores the differential remodeling responses of craniofacial defects by comparing the effects of two pharmacological agents, thioridazine-hydrochloride (thio) and ivermectin (IVM), on craniofacial morphology in X. laevis. Thio-exposure reliably induces a craniofacial defect that can remodel in pre-metamorphic animals, while IVM induces a permanent, non-correcting phenotype. We examined developmental changes from feeding stages to hindlimb bud stages and mapped the effects of each agent on the patterning of craniofacial tissue types including: cartilage, muscle, and nerves. Our findings reveal that thio-induced craniofacial defects exhibit significant consistent remodeling, particularly in muscle, with gene expression analysis revealing upregulation of key remodeling genes, matrix metalloproteinases 1 and 13, as well as their regulator, prolactin.2. In contrast, IVM-induced defects show no significant remodeling, highlighting the importance of specific molecular and cellular factors in pre-metamorphic craniofacial correction. Additionally, unique neuronal profiles suggest a previously underappreciated role for the nervous system in tissue remodeling. This study provides novel insights into the molecular and cellular mechanisms underlying craniofacial defect remodeling and lays the groundwork for future investigations into tissue repair in vertebrates.

Sexual dysfunctions are a challenging side effect associated with antipsychotic treatment. This protocol outlines a systematic review and meta-analysis to assess the prevalence of overall sexual dysfunction, as well as the specific phases of sexual function affected by antipsychotic medications. Additionally, the analysis will explore the relationship between prolactin levels and sexual dysfunction.

The development of acquired resistance to tamoxifen poses a significant clinical challenge in breast cancer treatment. Tumour heterogeneity has emerged as a primary reason for the clinical implications of resistance, yet we still lack actionable targets to address this issue. Repurposing existing drugs has become an emerging trend to tackle demanding medical indications. Therefore, we aim to study the efficacy of the antipsychotic drug Thioridazine against both parental and tamoxifen-resistant breast cancer cells. In this study, we have demonstrated that Thioridazine induces phospholipid accumulation, followed by necroptosis in both parental and tamoxifen-resistant breast cancer cell lines. We have shown thioridazine-mediated cytostatic effects through analyses of cell viability, cell count, caspase activation, cell cycle, and p21 expression levels. Moreover, employing a pharmacometabolomics approach, we identified that Thioridazine induces phospholipid accumulation in breast cancer cells. We established that Thioridazine promotes the accumulation of phospholipids rather than neutral lipids in cells via lipid-specific fluorescent quantification and imaging analysis. The phospholipid accumulation triggers necroptosis, which was evaluated through a propidium iodide uptake assay. Thioridazine activates RIP signalling, facilitating the subsequent translocation of pore-forming MLKL to the plasma membrane to initiate necroptosis. The formation of MLKL-induced membrane pores was confirmed using scanning electron microscopy for cell surface visualisation. Furthermore, thioridazine co-treatment enhances the efficacy of tamoxifen in resistant breast cancer cells, augmenting its potential for combinatorial treatment. Altogether, Thioridazine induces phospholipid accumulation followed by necroptosis in both parental and tamoxifen-resistant breast cancer cell lines, highlighting its potential application in breast cancer treatment.