Endocytosis Inhibition in Humans to Improve Responses to ADCC-Mediating Antibodies.

A safe and controlled manipulation of endocytosis in vivo may have disruptive therapeutic potential. Here, we demonstrate that the anti-emetic/anti-psychotic prochlorperazine can be repurposed to reversibly inhibit the in vivo endocytosis of membrane proteins targeted by therapeutic monoclonal antibodies, as directly demonstrated by our human tumor ex vivo assay. Temporary endocytosis inhibition results in enhanced target availability and improved efficiency of natural killer cell-mediated antibody-dependent cellular cytotoxicity (ADCC), a mediator of clinical responses induced by IgG1 antibodies, demonstrated here for cetuximab, trastuzumab, and avelumab. Extensive analysis of downstream signaling pathways ruled out on-target toxicities. By overcoming the heterogeneity of drug target availability that frequently characterizes poorly responsive or resistant tumors, clinical application of reversible endocytosis inhibition may considerably improve the clinical benefit of ADCC-mediating therapeutic antibodies.

Antimelanoma activity of perphenazine and prochlorperazine in human COLO829 and C32 cell lines.

Cutaneous melanoma is least common (only about 1% of skin cancers) but is the deadliest malignant tumor. Moreover, amelanotic types of melanoma are very difficult for clinical diagnosis. The standard therapy can cause a lot of side effects, e.g., nausea, vomiting, and headaches, which means that novel and effective strategies are required. Interestingly, phenothiazine derivatives possess sedative, antiemetic, and anticancer activity. Our goal was to determine the effect of perphenazine and prochlorperazine on cell viability, motility, microphthalmia-associated transcription factor (MITF) and tyrosinase content in melanotic and amelanotic melanoma cells. The viability of C32 and COLO829 melanoma cells was evaluated by the WST-1 colorimetric assay; impact on motility of human melanoma was performed by wound-healing assay, while tyrosinase and MITF content were determined by Western blot. In the present study, we explore the anticancer effect of perphenazine and prochlorperazine in human melanotic (COLO829) and amelanotic (C32) melanoma cells concluding that prochlorperazine inhibits cell viability in a concentration-dependent manner, impairs motility, and decreases tyrosinase and MITF amounts. Moreover, the analyzed drugs decrease/increase MITF amount depending on the type of melanoma. We demonstrated that the decrease of MITF and tyrosinase protein induces motility inhibition of C32 cells, which suggests the ability of those drugs to restore cancer cell sensitivity to treatment. The ability of prochlorperazine to contain the spread of the amelanotic melanoma in vivo may be helpful in the development of a new and effective antimelanoma therapies.

Perphenazine and prochlorperazine induce concentration-dependent loss in human glioblastoma cells viability.

Phenothiazine derivatives possess biological properties very useful for cancer therapy, such as antiemetic and sedative activity as well as good blood-brain barrier permeability. Our goal was to determine if perphenazine and prochlorperazine are possessing cytotoxic activity towards U87-MG cells. It has been shown that the analyzed drugs induce concentration-dependent loss in cell viability, what correlates with their chemical structure. The calculated EC50 values for perphenazine (0.98 µM) and prochlorperazine (0.97 µM) are related to their toxic concentrations in human plasma. The obtained results suggest that perphenazine and prochlorperazine may have a potential for the development of new and effective anticancer therapies.

Quantitative high throughput screening using a primary human three-dimensional organotypic culture predicts in vivo efficacy.

The tumour microenvironment contributes to cancer metastasis and drug resistance. However, most high throughput screening (HTS) assays for drug discovery use cancer cells grown in monolayers. Here we show that a multilayered culture containing primary human fibroblasts, mesothelial cells and extracellular matrix can be adapted into a reliable 384- and 1,536-multi-well HTS assay that reproduces the human ovarian cancer (OvCa) metastatic microenvironment. We validate the identified inhibitors in secondary in vitro and in vivo biological assays using three OvCa cell lines: HeyA8, SKOV3ip1 and Tyk-nu. The active compounds directly inhibit at least two of the three OvCa functions: adhesion, invasion and growth. In vivo, these compounds prevent OvCa adhesion, invasion and metastasis, and improve survival in mouse models. Collectively, these data indicate that a complex three-dimensional culture of the tumour microenvironment can be adapted for quantitative HTS and may improve the disease relevance of assays used for drug screening.

Combined drug therapy in the management of granulomatous amoebic encephalitis due to Acanthamoeba spp., and Balamuthia mandrillaris.

Granulomatous amoebic encephalitis (GAE) is caused by two protist pathogens, Acanthamoeba spp., and Balamuthia mandrillaris. Although rare, it almost always results in death. In the present study, amoebae were treated with various combinations of clinically-approved drugs, targeting vital cellular receptors and biochemical pathways. The results revealed that among the seven different combinations tested, three proved highly effective against both Acanthamoeba castellanii as well as B. mandrillaris at a concentration of 100µM. These combinations included (i) prochlorperazine plus loperamide; (ii) prochlorperazine plus apomorphine; and (iii) procyclidine plus loperamide. In viability assays, none of the drug-treated amoebae emerged as viable trophozoites, suggesting irreversible amoebicidal effects. Four combinations of drugs tested showed varied potency against A. castellanii and B. mandrillaris at 100µM. The combination of haloperidol and loperamide was highly effective against A. castellanii at 100µM, but potent effects against B. mandrillaris were observed only at 250µM. Digoxin and amlodipine were effective against A. castellanii and B. mandrillaris at 100µM and 250µM, respectively. In contrast, the combination of apomorphine and haloperidol was effective against B. mandrillaris and A. castellanii at 100µM and 250µM, respectively. At 100µM, the combination of procyclidine and amiodarone was effective against neither A. castellanii nor B. mandrillaris. In this case, amoebicidal properties were observed at 750µM for A. castellanii, and 950µM for B. mandrillaris. As these drugs are used clinically against non-communicable diseases, the findings reported here have the potential to be tested in a clinical setting against amoebic encephalitis caused by A. castellanii and B. mandrillaris.

Impact of genetic and non-genetic factors on clinical responses to prochlorperazine in oxycodone-treated cancer patients.

BACKGROUND: The contributions of DRD2 and OPRM1 genetic variants to clinical responses to prochlorperazine remain to be clarified in opioid-treated patients. We evaluated the clinical responses to prochlorperazine based on non-genetic and genetic factors in oxycodone-treated patients. METHODS: Seventy Japanese cancer patients starting oral prochlorperazine together with oxycodone were enrolled. Predose plasma prochlorperazine concentrations and serum prolactin concentrations were determined. The incidences of oxycodone-induced nausea and vomiting were monitored for 2weeks. RESULTS: Plasma prochlorperazine concentration and oxycodone daily dose were not associated with the incidences of nausea and vomiting. The incidence of nausea was significantly higher in the DRD2 TaqIA A1A2+A1A1 group than in the A2A2 group. The incidence of vomiting was significantly higher in females than in males. Before and after the prochlorperazine administration, the serum prolactin concentration was significantly higher in female patients than in male patients. The serum prolactin concentration was weakly correlated with prochlorperazine concentration and was significantly higher in the OPRM1 118AA group than in the AG+GG group. CONCLUSIONS: DRD2 TaqIA and female gender altered the prophylactic antiemetic efficacy of prochlorperazine. OPRM1 A118G together with plasma exposure of prochlorperazine and gender affected prolactin secretion in oxycodone-treated patients.

The phenothiazine-class antipsychotic drugs prochlorperazine and trifluoperazine are potent allosteric modulators of the human P2X7 receptor.

P2X7, an ATP-gated cation channel, is involved in immune cell activation, hyperalgesia and neuropathic pain. By regulating cytokine release in the brain, P2X7 has been linked to the pathophysiology of mood disorders and schizophrenia. We here assess the impact of 123 drugs that act in the central nervous system on human P2X7. Most prominently, the tricyclic antipsychotics prochlorperazine (PCP) and trifluoperazine (TFP) potently inhibited P2X7-mediated Ca2+ entry, dye permeation and ionic currents. In divalent cation-containing bath solutions or after prolonged incubation, ATP-evoked P2X7 currents were inhibited by 10 µM PCP. This effect was not related to dopamine receptor antagonism. Surprisingly, PCP co-applied with ATP enhanced inward currents in bath solutions with low divalent cation concentrations. Intracellular perfusion with PCP did not substitute for the extracellularly applied drug, indicating that its binding sites are accessible from the extracellular space. Since P2X7 current potentiation by PCP was voltage-dependent, at least one site may be located within the electrical field of the membrane. While the channel opening and closure kinetic was altered by PCP, the apparent affinity of ATP remained unchanged (potentiation) or changed slightly (inhibition). Measurements in human monocyte-derived macrophages confirmed the PCP-induced inhibition of ATP-evoked Ca2+ influx, Yo-Pro-1 permeability, and whole cell currents. Interestingly, neither heterologously expressed rat or mouse P2X7 nor native P2X7 in rat astrocyte cultures or in mouse bone marrow-derived macrophages were inhibited by perazines with a similar potency. We conclude that perazine-type neuroleptics are potent, but species-selective allosteric modulators of human but not murine P2X7 receptors.

In vitro efficacies of clinically available drugs against growth and viability of an Acanthamoeba castellanii keratitis isolate belonging to the T4 genotype.

The effects of clinically available drugs targeting muscarinic cholinergic, adrenergic, dopaminergic, and serotonergic receptors; intracellular calcium levels and/or the function of calcium-dependent biochemical pathways; ion channels; and cellular pumps were tested against a keratitis isolate of Acanthamoeba castellanii belonging to the T4 genotype. In vitro growth inhibition (amoebistatic) assays were performed by incubating A. castellanii with various concentrations of drugs in the growth medium for 48 h at 30°C. To determine amoebicidal effects, amoebae were incubated with drugs in phosphate-buffered saline for 24 h, and viability was determined using trypan blue exclusion staining. For controls, amoebae were incubated with the solvent alone. Of the eight drugs tested, amlodipine, prochlorperazine, and loperamide showed potent amoebicidal effects, as no viable trophozoites were observed (>95% kill rate), while amiodarone, procyclidine, digoxin, and apomorphine exhibited up to 50% amoebicidal effects. In contrast, haloperidol did not affect viability, but all the drugs tested inhibited A. castellanii growth. Importantly, amlodipine, prochlorperazine, and loperamide showed compelling cysticidal effects. The cysticidal effects were irreversible, as cysts treated with the aforementioned drugs did not reemerge as viable amoebae upon inoculation in the growth medium. Except for apomorphine and haloperidol, all the tested drugs blocked trophozoite differentiation into cysts in encystation assays. Given the limited availability of effective drugs to treat amoebal infections, the clinically available drugs tested in this study represent potential agents for managing keratitis and granulomatous amoebic encephalitis caused by Acanthamoeba spp. and possibly against other meningoencephalitis-causing amoebae, such as Balamuthia mandrillaris and Naegleria fowleri.

Integration of chemical and RNAi multiparametric profiles identifies triggers of intracellular mycobacterial killing.

Pharmacological modulators of host-microbial interactions can in principle be identified using high-content screens. However, a severe limitation of this approach is the lack of insights into the mode of action of compounds selected during the primary screen. To overcome this problem, we developed a combined experimental and computational approach. We designed a quantitative multiparametric image-based assay to measure intracellular mycobacteria in primary human macrophages, screened a chemical library containing FDA-approved drugs, and validated three compounds for intracellular killing of M. tuberculosis. By integrating the multiparametric profiles of the chemicals with those of siRNAs from a genome-wide survey on endocytosis, we predicted and experimentally verified that two compounds modulate autophagy, whereas the third accelerates endosomal progression. Our findings demonstrate the value of integrating small molecules and genetic screens for identifying cellular mechanisms modulated by chemicals. Furthermore, selective pharmacological modulation of host trafficking pathways can be applied to intracellular pathogens beyond mycobacteria.

An integrated bioinformatics approach identifies elevated cyclin E2 expression and E2F activity as distinct features of tamoxifen resistant breast tumors.

Approximately half of estrogen receptor (ER) positive breast tumors will fail to respond to endocrine therapy. Here we used an integrative bioinformatics approach to analyze three gene expression profiling data sets from breast tumors in an attempt to uncover underlying mechanisms contributing to the development of resistance and potential therapeutic strategies to counteract these mechanisms. Genes that are differentially expressed in tamoxifen resistant vs. sensitive breast tumors were identified from three different publically available microarray datasets. These differentially expressed (DE) genes were analyzed using gene function and gene set enrichment and examined in intrinsic subtypes of breast tumors. The Connectivity Map analysis was utilized to link gene expression profiles of tamoxifen resistant tumors to small molecules and validation studies were carried out in a tamoxifen resistant cell line. Despite little overlap in genes that are differentially expressed in tamoxifen resistant vs. sensitive tumors, a high degree of functional similarity was observed among the three datasets. Tamoxifen resistant tumors displayed enriched expression of genes related to cell cycle and proliferation, as well as elevated activity of E2F transcription factors, and were highly correlated with a Luminal intrinsic subtype. A number of small molecules, including phenothiazines, were found that induced a gene signature in breast cancer cell lines opposite to that found in tamoxifen resistant vs. sensitive tumors and the ability of phenothiazines to down-regulate cyclin E2 and inhibit proliferation of tamoxifen resistant breast cancer cells was validated. Our findings demonstrate that an integrated bioinformatics approach to analyze gene expression profiles from multiple breast tumor datasets can identify important biological pathways and potentially novel therapeutic options for tamoxifen-resistant breast cancers.

Phenothiazines inhibit S100A4 function by inducing protein oligomerization.

S100A4, a member of the S100 family of Ca(2+)-binding proteins, regulates carcinoma cell motility via interactions with myosin-IIA. Numerous studies indicate that S100A4 is not simply a marker for metastatic disease, but rather has a direct role in metastatic progression. These observations suggest that S100A4 is an excellent target for therapeutic intervention. Using a unique biosensor-based assay, trifluoperazine (TFP) was identified as an inhibitor that disrupts the S100A4/myosin-IIA interaction. To examine the interaction of S100A4 with TFP, we determined the 2.3 A crystal structure of human Ca(2+)-S100A4 bound to TFP. Two TFP molecules bind within the hydrophobic target binding pocket of Ca(2+)-S100A4 with no significant conformational changes observed in the protein upon complex formation. NMR chemical shift perturbations are consistent with the crystal structure and demonstrate that TFP binds to the target binding cleft of S100A4 in solution. Remarkably, TFP binding results in the assembly of five Ca(2+)-S100A4/TFP dimers into a tightly packed pentameric ring. Within each pentamer most of the contacts between S100A4 dimers occurs through the TFP moieties. The Ca(2+)-S100A4/prochlorperazine (PCP) complex exhibits a similar pentameric assembly. Equilibrium sedimentation and cross-linking studies demonstrate the cooperative formation of a similarly sized S100A4/TFP oligomer in solution. Assays examining the ability of TFP to block S100A4-mediated disassembly of myosin-IIA filaments demonstrate that significant inhibition of S100A4 function occurs only at TFP concentrations that promote S100A4 oligomerization. Together these studies support a unique mode of inhibition in which phenothiazines disrupt the S100A4/myosin-IIA interaction by sequestering S100A4 via small molecule-induced oligomerization.

Psychotropic drugs interfere with the tight coupling of polyphosphoinositide cycle metabolites in human platelets: a result of receptor-independent drug intercalation in the plasma membrane?

Incubation of platelets with increasing concentrations of thrombin produced large amounts of phosphatidic acid (PA) and distinct changes in phosphatidylinositol-4-phosphate (PIP) and phosphatidylinositol-4,5-bisphosphate (PIP2), prominent metabolites in the polyphosphoinositide (PPI) cycle. The relation between normalized PA and PIP or PIP2 levels in such thrombin-treated platelets from 22 normal donors gave a very similar pattern, suggesting tight control of the metabolites in the polyphosphoinositide (PPI) cycle. Prochlorperazine (PCP), trifluoperazine (TFP), haloperidol (HPD), quetiapine (QTP), pimozide (PMZ) and clozapine (CLO) interfered with this tight coupling produced by treating platelets with increasing thrombin concentrations. All drugs decreased the formation of PA at a given thrombin concentration, a decrease that varied greatly among platelets from different donors. This made it difficult to treat the PIP/PA and PIP2/PA relationships with ordinary, descriptive statistics. The data were therefore subjected to regression analysis using polynomials of second or first degree and gave the interference ranking order: PCP>TFP>>PMZ = HPD>CLO>QTP. All six drugs increased the mean molecular area of monolayers of dipalmitoyl phosphatidylserine on pure water at 37 degrees C by 20-50%, while they had little effect on monolayers of dipalmitoyl phosphatidylcholine. These results suggest that the drugs are membrane-active and may intercalate in biomembranes containing negatively charged phospholipids. Since human platelets do not contain D2 receptors, the interference with the tight coupling of PPI cycle metabolites was not receptor-mediated. We suggest that the drugs are intercalated in the plasma membrane and alter the relative, spatial positioning of phospholipid-consuming enzymes and thereby alter the velocities of the enzyme-catalyzed reactions. Such intercalation could be part of the side effects of the drugs and may explain their psychotropic action(s).

Blockade of HERG human K+ channel and IKr of guinea pig cardiomyocytes by prochlorperazine.

Prochlorperazine, a drug for the symptomatic control of nausea, vomiting and psychiatric disorders, can induce prolonged QT, torsades de pointes and sudden death. We studied the effects of prochlorperazine on human ether-a-go-go-related gene (HERG) channels expressed in Xenopus oocytes and also in the delayed rectifier K+ current of guinea pig cardiomyocytes. Prochlorperazine induced a concentration-dependent decrease in current amplitudes at the end of the voltage steps and tail currents of HERG. The IC50 for a prochlorperazine block of HERG current in Xenopus oocytes progressively decreased relative to the degree of depolarization, from 42.1 microM at -40 mV to 37.4 microM at 0 mV to 22.6 microM at +40 mV. The block of HERG by prochlorperazine was use-dependent, exhibiting a more rapid onset and a greater steady-state block at higher frequencies of activation, while there was partial relief of the block with reduced frequencies. In guinea pig ventricular myocytes, bath applications of 0.5 and 1 muM prochlorperazine at 36 degrees C blocked rapidly activating delayed rectifier K+ current by 38.9% and 76.5%, respectively, but did not significantly block slowly activating delayed rectifier K+ current. Our findings suggest that the arrhythmogenic side effects of prochlorperazine are caused by a blockade of HERG and the rapid component of the delayed rectifier K+ current rather than by a blockade of the slow component.

Preliminary studies on phenothiazine-mediated reversal of multidrug resistance in mouse lymphoma and COLO 320 cells.

The ability of phenothiazine derivatives to inhibit the transport activity of P-glycoprotein in resistant mouse lymphoma and MDR/COLO 320 cells was studied. A rhodamine 123 efflux from the above-mentioned neoplastic cells in the presence of tested compounds was examined by flow cytometry. Two of the phenothiazine derivatives, namely perphenazine and prochlorperazine dimaleate, proved to be effective inhibitors of the rhodamine efflux. Other tested phenothiazine derivatives (promethazine hydrochloride, oxomemazine, methotrimeprazine maleate, trifluoropromazine hydrochloride, trimeprazine) also modulated the intracellular drug accumulation in both resistant cell lines, however, they exerted additional cytotoxic effects. The differences observed between the effects of the test compounds on intracellular drug accumulation could be the outcome of differences in phenothiazine's chemical structure, which is crucial for drug-cell membrane interactions. The results of this study provide information about a new group of compounds that offer promise in multidrug resistance reversal in tumor cells.

Synergistic effect of prochlorperazine and dipyridamole on the cellular retention and cytotoxicity of doxorubicin.

Incubation of drug-resistant human tumor cells with a combination of prochlorperazine and dipyridamole has additive/synergistic effect on the cellular retention and cytotoxicity of doxorubicin. In patients administered a fixed dose of doxorubicin and prochlorperazine with escalating doses of dipyridamole, mean plasma levels of dipyridamole and prochlorperazine achieved were as high as 3.01 +/- 0.41 microm and 0.94 +/- 0.09 microm, respectively. Plasma samples from patients were analyzed in an in vitro assay to monitor the effect on the cellular retention of tritium-labeled daunorubicin in MDR1-transfected P388 cells. In 22 of 49 of the plasma samples analyzed, the daunorubicin in efflux blocking activity was one-half or greater than that of cells incubated with 12.5 microM verapamil, a well-known efflux blocker. These observations suggest that a combination of prochlorperazine and dipyridamole may enhance cellular doxorubicin retention by blocking efflux while reducing normal tissue toxicity and unwanted side effects in vivo.

Metoclopramide and prochlorperazine do not decrease propofol hypnotic requirements.

One hundred patients scheduled for minor surgery were given either saline, metoclopramide 0.1 mg.kg-1 or 0.2 mg.kg-1, or prochlorperazine 0.1 mg.kg-1 or 0.2 mg.kg-1 before induction of anaesthesia with a fixed rate infusion of propofol. Neither metoclopramide nor prochlorperazine reduced the induction dose of propofol. The possibility that these agents increased the induction dose could not be excluded.

Structure-activity relationships of phenothiazines in inhibiting lymphocyte motility as determined by a novel flow cytometric assay.

Lymphocyte motility is highly dependent on rapid changes in cell shape. The human T-lymphoma cell line, MOLT-4, is constitutively shape-changing and motile, and both of these properties can be inhibited by the phenothiazine, chlorpromazine, as assessed by video analysis and migration across polycarbonate filters. In this paper, the light-scattering facility of a flow cytometer has been used to establish a simpler and more quantitative means of measuring changes in shape. By this method, the structure activity relationship (SAR) of phenothiazines and related compounds has been determined. The most active compounds had the tricyclic phenothiazine nucleus with a constrained dialkylaminoalkyl substituent at the nitrogen. The SAR for inhibition of lymphocyte motility differs from those reported for neuroleptic effects and for inhibition of PKC or calmodulin. Phenothiazine concentrations that inhibited lymphocyte shape-changing resulted in reduced F-actin concentrations. This indicates that the probable mode of action is disruption of mechanisms regulating actin polymerisation.

Effect of prochlorperazine as a sensitizer of rat skin on radiation-induced AMP metabolism.

The role of AMP was investigated in radiosensitization by the use of prochlorperazine in normal rat skin. AMP metabolism was evaluated by estimating the level of activities of 5' nucleotidase vis-à-vis protein, DNA and RNA contents in prochlorperazine-treated plus irradiated skin. To study radiation-induced changes in the skin, the extent of lipid peroxidation was measured in terms of enzyme lipid peroxidase. After irradiation, lipid peroxidase activity was observed to increase in prochlorperazine-treated rat skin. Subsequently the level of 5' nucleotidase was found to decrease in drug-treated plus irradiation skin. Similarly, the suppression in the levels of DNA, RNA and protein contents increased when the rat skins was irradiated in the presence of sensitizer prochlorperazine. The cytological examination, which revealed the extent of the lesions occurring in the normal rat skin, and the biochemical examination demonstrated increased cellular lethality in prochlorperazine-sensitized skin after irradiation. The results suggest that prochlorperazine probably sensitizes the normal skin tissues to radiation by inhibiting AMP metabolism via hydroxy-radical-induced decrease in DNA, RNA and protein metabolism.

Development of a murine gastric distension model for testing the emetic potential of new drugs and efficacy of antiemetics.

A small animal model for emesis would allow preclinical testing of antiemetics and new drugs. Mice treated with cisplatinum develop stomachs distended with food. This effect is reduced by metoclopramide and parallels the gastric nausea experienced by patients receiving cisplatinum. To assess gastric distension as a more general model for paralleling the human emetic response, groups of five BALB/c mice were given intravenous nitrogen mustard, adriamycin, cyclophosphamide, 5-fluoruracil (5FU), vincristine and intraperitoneal DTIC at doses equivalent to those used clinically (mg/kg mouse = 12 X mg/kg per man). The mice were allowed free access to food pellets and water. At 48 h they were sacrificed and gastric distension quantitated as a ratio of average stomach to body weight. Significant gastric distension occurred with nitrogen mustard, DTIC, adriamycin and cyclophosphamide but not 5FU or vincristine. This parallels the emetic potential of these drugs in humans. Similarly cisplatinum was compared to its analogues, carboplatin and JM40 and produced gastric distension at lower doses than carboplatin. The model was then used to test the antiemetic efficacy of escalating doses of prochlorperazine against cisplatinum induced gastric distension in groups of 10 BALB/c mice. Doses ranged from 2.5 mg/kg. Only a high dose (19.2 mg/kg) significantly reduced the gastric distension. This parallels a clinical dose response relationship recently reported for prochlorperazine and suggests the further potential use of this model.