Inhibition of a new AXL isoform, AXL3, induces apoptosis of mantle cell lymphoma cells

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma having a poor overall survival that is in need for the development of new therapeutics. In this study, we report the identification and expression of a new isoform splice variant of the tyrosine kinase receptor AXL in MCL cells. This new AXL isoform, called AXL3, lacks the ligand-binding domain of the commonly described AXL splice variants and is constitutively activated in MCL cells. Interestingly, functional characterization of AXL3, using CRISPR inhibition, revealed that only the knock down of this isoform leads to apoptosis of MCL cells. Importantly, pharmacological inhibition of AXL activity resulted in a significant decrease in the activation of well-known proproliferative and survival pathways activated in MCL cells (ie, β-catenin, Ak strain transforming, and NF-κB). Therapeutically, preclinical studies using a xenograft mouse model of MCL indicated that bemcentinib is more effective than ibrutinib in reducing the tumor burden and to increase the overall survival. Our study highlights the importance of a previously unidentified AXL splice variant in cancer and the potential of bemcentinib as a targeted therapy for MCL.

Vacuolar ATPase Is a Possible Therapeutic Target in Acute Myeloid Leukemia: Focus on Patient Heterogeneity and Treatment Toxicity

Vacuolar ATPase (V-ATPase) is regarded as a possible target in cancer treatment. It is expressed in primary acute myeloid leukemia cells (AML), but the expression varies between patients and is highest for patients with a favorable prognosis after intensive chemotherapy. We therefore investigated the functional effects of two V-ATPase inhibitors (bafilomycin A1, concanamycin A) for primary AML cells derived from 80 consecutive patients. The V-ATPase inhibitors showed dose-dependent antiproliferative and proapoptotic effects that varied considerably between patients. A proteomic comparison of primary AML cells showing weak versus strong antiproliferative effects of V-ATPase inhibition showed a differential expression of proteins involved in intracellular transport/cytoskeleton functions, and an equivalent phosphoproteomic comparison showed a differential expression of proteins that regulate RNA processing/function together with increased activity of casein kinase 2. Patients with secondary AML, i.e., a heterogeneous subset with generally adverse prognosis and previous cytotoxic therapy, myeloproliferative neoplasia or myelodysplastic syndrome, were characterized by a strong antiproliferative effect of V-ATPase inhibition and also by a specific mRNA expression profile of V-ATPase interactome proteins. Furthermore, the V-ATPase inhibition altered the constitutive extracellular release of several soluble mediators (e.g., chemokines, interleukins, proteases, protease inhibitors), and increased mediator levels in the presence of AML-supporting bone marrow mesenchymal stem cells was then observed, especially for patients with secondary AML. Finally, animal studies suggested that the V-ATPase inhibitor bafilomycin had limited toxicity, even when combined with cytarabine. To conclude, V-ATPase inhibition has antileukemic effects in AML, but this effect varies between patients.

Repurposing chlorpromazine for anti-leukaemic therapy by nanoparticle encapsulation

Treatment of acute myeloid leukaemia (AML) relies on decades-old drugs, and while recent years have seen some breakthroughs, AML is still characterised by poor prognosis and survival rate. Drug repurposing can expedite the preclinical development of new therapies, and by nanocarrier encapsulation, the number of potentially viable drug candidates can be further expanded. The anti-psychotic drug chlorpromazine (CPZ) has been identified as a candidate for repurposing for AML therapy. Nanoencapsulation may improve the suitability of CPZ for the treatment of AML by reducing its effect on the central nervous system. Using the emulsion-evaporation technique, we have developed PEGylated PLGA nanoparticles loaded with CPZ for AML therapy. The nanoparticles were characterised to be between 150 and 300 nm by DLS, of spherical morphology by TEM, with a drug loading of at least 6.0% (w/w). After an initial burst release of adsorbed drug, the remaining 80% of the drug was retained in the PLGA nanoparticles for at least 24 h. The CPZ-loaded nanoparticles had equal cytotoxic potential towards AML cells to free CPZ, but acted more slowly, in line with the protracted drug release. Crucially, nanoparticles injected intravenously into zebrafish larvae did not accumulate in the brain, and nanoencapsulation also prevented CPZ from crossing an artificial membrane model. This demonstrates that the purpose for nanoencapsulation of CPZ is fulfilled, namely avoiding effects on the central nervous system while retaining the anti-AML activity of the drug.

Selecting the optimal parameters for sonoporation of pancreatic cancer in a pre-clinical model

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers in the modern world, in part due to poor delivery of chemotherapeutics. Sonoporation can be used to enhance the efficacy of standard of care therapies for PDAC. Using xenograft models of PDAC we investigate sonoporation using four ifferent ultrasound contrast agents (UCAs) and two ultrasound regimens to identify the ideal parameters to increase therapeutic efficacy. MIA-PaCa2 xenografts in over 175 immunodeficient mice were treated with gemcitabine and paclitaxel and subjected to low or high power ultrasound (60 and 200 mW/cm² respectively) in conjunction with one of four different UCAs. The UCAs investigated were Definity®, SonoVue®, Optison™ or Sonazoid™. Tumor volumes, vascularity, hemoglobin, and oxygenation were measured and compared to controls. High power treatment in conjunction with Sonazoid sonoporation led to significantly smaller tumors when started early (tumors ~50mm³; p = .0105), while no UCAs significantly increased efficacy in the low power cohort. This trend was also found in larger tumors (~250mm³) where all four UCA agents significantly increased therapeutic efficacy in the high power group (p < .01), while only Definity and SonoVue increased efficacy in the low power cohort (p < .03). Overall, the higher power ultrasound treatment modality was more consistently effective at decreasing tumor volume and increasing vascularity characteristics. In conclusion, Sonazoid was the most consistently effective UCA at decreasing tumor volume and increasing vascularity. Thus, we are pursuing a larger phase II clinical trial to validate the increased efficacy of sonoporation in conjunction with chemotherapy in PDAC patients.

8-chloro-adenosine activity in FLT3-ITD acute myeloid leukemia

Nucleoside analogs represent the backbone of several distinct chemotherapy regimens for acute myeloid leukemia (AML) and combination with tyrosine kinase inhibitors has improved survival of AML patients, including those harboring the poor-risk FLT3-ITD mutation. Although these compounds are effective in killing proliferating blasts, they lack activity against quiescent leukemia stem cells (LSCs), which contributes to initial treatment refractoriness or subsequent disease relapse. The reagent 8-chloro-adenosine (8-Cl-Ado) is a ribose-containing, RNA-directed nucleoside analog that is incorporated into newly transcribed RNA rather than in DNA, causing inhibition of RNA transcription. In this report, we demonstrate antileukemic activities of 8-Cl-Ado in vitro and in vivo and provide mechanistic insight into the mode of action of 8-Cl-Ado in AML. 8-Cl-Ado markedly induced apoptosis in LSC, with negligible effects on normal stem cells. 8-Cl-Ado was particularly effective against AML cell lines and primary AML blast cells harboring the FLT3-ITD mutation. FLT3-ITD is associated with high expression of miR-155. Furthermore, we demonstrate that 8-Cl-Ado inhibits miR-155 expression levels accompanied by induction of DNA-damage and suppression of cell proliferation, through regulation of miR-155/ErbB3 binding protein 1(Ebp1)/p53/PCNA signaling. Finally, we determined that combined treatment of NSG mice engrafted with FLT3-ITD + MV4-11 AML cells with 8-Cl-Ado and the FLT3 inhibitor AC220 (quizartinib) synergistically enhanced survival, compared with that of mice treated with the individual drugs, suggesting a potentially effective approach for FLT3-ITD AML patients.

4-Alkylated Silver-N-Heterocyclic Carbene (NHC) Complexes with Cytotoxic Effects in Leukemia Cells

Computational chemistry has shown that backbone-alkylated imidazoles ought to be efficient ligands for transition metal catalysts with improved carbene-to-metal donation. In this work, such alkylated imidazoles were synthesized and complexed with silver(I) by means of an eight/nine-step synthetic pathway we devised to access a new class of biologically active silver complexes. The synthesis involves selective iodination of the imidazole backbone, followed by Sonogashira coupling to replace the backbone iodine. The installed alkyne moiety is then subjected to reductive hydrogenation with Pearlman's catalyst. The imidazole N1 atom is arylated by the palladium-catalyzed Buchwald N-arylation method. The imidazole N3 position was then methylated with methyl iodine, whereupon the synthesis was terminated by complexation of the imidazolium salt with silver(I) oxide. The synthetic pathway provided an overall yield of ≈20 %. The resulting complexes were tested in vitro against HL60 and MOLM-13 leukemic cells, two human-derived cell lines that model acute myeloid leukemia. The most active compounds exhibiting low IC50 values of 14 and 27 μM, against HL60 and MOLM-13 cells, respectively. The imidazole side chain was found to be essential for high cytotoxicity, as the imidazole complex bearing a C7 side chain at the 4-position was four- to sixfold more potent than the corresponding imidazole elaborated with a methyl group.

Microbial colonization of soft contact lenses over time

PURPOSE

To compare the bacterial colonization of soft contact lenses in subjects for successively increasing periods, up to 13 nights of wear. The aim of this study was to determine whether increasing the length of lens wear predisposed subjects to high levels of microbial colonization of lenses.

METHODS

Subjects (N = 20) were divided into those with a prior history of adverse events (N = 6), gram-negative bacterial carriers (N = 6), and those with no previous history (N = 8).

RESULTS

There were no temporal changes in microbial colonization of lenses. Lenses from all wearers were colonized at least once during the study by gram-positive bacteria at low numbers (<10 cfu/ml). Gram-negative bacteria colonized lenses at least once in 80% of all wearers. Lenses from gram-negative bacterial carriers were more frequently colonized by Staphylococcus aureus and Pseudomonas sp. compared with subjects with no previous history and subjects with a prior history of adverse events, respectively. Lenses from gram-negative bacterial carriers were less frequently colonized by a range of gram-positive bacteria compared with subjects with a prior history of adverse events.

CONCLUSIONS

Increasing the length of lens wear up to 13 nights did not result in a predictable increase in bacterial colonization of contact lenses. Gram-positive bacteria were isolated frequently but in low numbers, whereas gram-negative bacteria were present sporadically.

Incidence of contamination of preserved saline solutions during normal use

PURPOSE

To ascertain the incidence of microbial contamination of preserved contact lens saline solutions with normal patient use.

METHODS

Eight different brands of preserved saline were dispensed to 40 patients attending optometric practices in the Sydney area. After specific periods of time (7 to 28 days), the samples were collected and the solution bottle nozzles and contents underwent microbial analysis.

RESULTS

The overall contamination rate was approximately 26% for contents only and 55% for nozzles of preserved saline solutions. This rate remained constant for all periods of use. Coagulase-negative Staphylococci were most frequently isolated. No Acanthamoebae were isolated. Saline preserved with ethylene-diamine-tetraacetic acid (EDTA) in conjunction with sorbic acid showed the highest percentage of sterility.

CONCLUSIONS

The results of this study show that preserved saline became contaminated with gram-positive bacteria. This is in contrast to our previously published paper using unpreserved saline, where contamination was predominantly with gram-negative bacteria. The overall contamination rates with preserved saline were lower than for unpreserved saline.

Potential sources of bacteria that are isolated from contact lenses during wear

PURPOSE

The aim of this paper was to determine the possible contamination sources of contact lenses during wear.

METHODS

Potential sources of the microbiota that colonized hydrogel contact lenses during wear were examined. The microorganisms that colonize contact lenses were grown, identified, and compared to those microorganisms that colonized the lower lid margins, upper bulbar conjunctiva, hands, and contact lens cases of contact lens wearers. In addition, the incidence of contamination of the domestic water supply in the Sydney area was obtained, and this was compared to the incidence of colonization of contact lenses by microorganisms in general and gram-negative bacteria in particular.

RESULTS

There was a wide diversity of bacteria that were isolated from each site sampled. Coagulase-negative staphylococci and Propionibacterium spp. were the most common isolates from all ocular sites examined, and constituted the normal ocular microbiota. Other bacteria, including members of the families Enterobacteriaceae and Pseudomonadaceae, were isolated infrequently from all sites, but most frequently from contact lens cases. Statistical analysis revealed that there was a correlation between the isolation of bacteria from the contact lens and the lower lid margin (p < 0.001). Analysis of this correlation revealed that this was true for the normal microbiota. A correlation was also noted between the colonization of contact lenses by gram-negative bacteria and contamination of the domestic water supply.

DISCUSSION

This study has demonstrated that the likely route for the normal ocular microbiota colonizing contact lenses is via the lid margins, whereas colonization by gram-negative bacteria, including potential agents of microbial keratitis, is likely to be from the domestic water supply.

Normal superoxide dismutase (SOD) gene in pregnancy-induced hypertension: is the decreased SOD activity a secondary phenomenon?

Reactive oxygen species (ROS) have been implicated in the pathogenesis of pregnancy-induced hypertension (PIH). A genetic factor is also thought to be associated with the disease. The aim of the present study was to investigate whether decreased superoxide dismutase (SOD) activity in PIH resulted from gene abnormalities. Fourteen patients with PIH were enrolled in the study. Normal pregnant women and normal nonpregnant women served as controls. Genomic DNA and mRNA were isolated from white cells and subjected to Southern and Northern blot analysis with a 600 bp CuZn-SOD probe. SOD activity was also determined in the white blood cells and red blood cells. The results showed that SOD activity was significantly reduced in patients with PIH compared to both control groups. There were no significant differences in the size of the CuZn-SOD gene and its expression between the patients with PIH and the controls. This study confirmed that there was a decreased SOD activity in PIH but revealed neither major structural changes in the genomic DNA nor mRNA size of CuZn-SOD. Our results suggest that the decreased SOD levels in PIH are not due to abnormalities in the CuZn-SOD gene and are an acquired phenomenon which occurs during the development of the disease.

Detection of bacteremia by Difco ESP blood culture system

In a multicenter study, the Difco ESP blood culture system (Difco Laboratories, Detroit, Mich.) was compared with the BACTEC NR660 system (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.). The ESP system monitors each blood culture bottle every 12 to 24 min to detect changes in oxygen consumption and gas production by microbes. Equal volumes of blood were inoculated into aerobic ESP-80A and BACTEC 6A, 16A, or PEDS Plus broths and anaerobic ESP-80N and BACTEC 7A or 17A broths and were incubated for up to 7 days. ESP bottles contain supplemented tryptic soy broth without antimicrobial agent-adsorbing resins. From 7,532 aerobic compliant sets, the ESP system detected 356 clinically significant positive cultures and the BACTEC NR660 system detected 329. From 6,007 anaerobic cultures, the ESP system detected 234 clinically significant positive cultures and the BACTEC NR660 system detected 198. In aerobic broths, 292 organisms were isolated from both systems and 78 organisms were isolated from the ESP system alone, whereas 54 organisms were isolated from the BACTEC NR660 system alone (P < 0.05). Among individual organisms, pneumococci were isolated significantly more often in ESP aerobic broths. In anaerobic broths, 180 organisms were isolated from both systems and 68 organisms were isolated from the ESP system alone, whereas 35 organisms were isolated from the BACTEC NR660 system alone (P < 0.05). Aerobic gram-positive organisms as a group and Candida spp. were isolated significantly more often in ESP anaerobic broths. Both systems detected 207 clinically significant bacteremic episodes and the ESP system alone detected 63, whereas the BACTEC NR660 system alone detected 32 (P < 0.05). Significantly more episodes of bacteremia caused by Staphylococcus epidermidis and anaerobes were detected by the ESP system. The differences in the numbers of organisms detected >6h earlier in ESP broths compared with BACTNEC NR660 broths were significant, as were earlier times to detection. Although the total number of organisms detected was not significantly different, the ESP system alone detected more organisms in a shorter time than did the BACTEC NR660 system alone. The continuous monitoring capability of the ESP system makes it an attractive alternative to the BACTEC NR660 system.