Persistence of Drug-Resistant Leukemic Stem Cells and Impaired NK Cell Immunity in CML Patients Depend on MIR300 Antiproliferative and PP2A-Activating Functions

Persistence of drug-resistant quiescent leukemic stem cells (LSC) and impaired natural killer (NK) cell immune response account for relapse of chronic myelogenous leukemia (CML). Inactivation of protein phosphatase 2A (PP2A) is essential for CML-quiescent LSC survival and NK cell antitumor activity. Here we show that MIR300 has antiproliferative and PP2A-activating functions that are dose dependently differentially induced by CCND2/CDK6 and SET inhibition, respectively. MIR300 is upregulated in CML LSCs and NK cells by bone marrow microenvironment (BMM) signals to induce quiescence and impair immune response, respectively. Conversely, BCR-ABL1 downregulates MIR300 in CML progenitors to prevent growth arrest and PP2A-mediated apoptosis. Quiescent LSCs escape apoptosis by upregulating TUG1 long noncoding RNA that uncouples and limits MIR300 function to cytostasis. Genetic and pharmacologic MIR300 modulation and/or PP2A-activating drug treatment restore NK cell activity, inhibit BMM-induced growth arrest, and selectively trigger LSC apoptosis in vitro and in patient-derived xenografts; hence, the importance of MIR300 and PP2A activity for CML development and therapy.

Abstract 951: Role of the MSC-derived exosomal and endogenous JAK2-SET/PP2A-β-catenin-modulator miR-300 in leukemic stem/progenitor proliferation and survival in CML

MiR-300 is a microRNA predicted to target multiple components of the BCR-ABL1/JAK2/hnRNPA1/SET/PP2A/β-catenin pathway, which is essential for survival/self-renewal of leukemic progenitors and quiescent TKI-resistant Ph+ hematopoietic stem cells (HSCs). Nanostring arrays analysis of bone marrow (BM) cells from healthy individuals (n = 5) and CML patients (n = 10) showed gradual inhibition of miR-300 expression (CML-CPmiR-300>CML-BCmiR-300).

MiR-300 transduction in CMLCD34+ cells and BCR-ABL1+ cell lines decreased JAK2, β-catenin, hnRNPA1 and SET expression and increased PP2A activity. Targets were confirmed by miR-300 expression in BCR-ABL1+ cells expressing Flag-tagged miR-300-targets lacking or carrying a wild-type or mutated 3’UTR. Restored miR-300 expression in CMLCD34+ cells and/or BCR-ABL1+ cell lines impaired proliferation and clonogenic potential, markedly reduced LTC-ICs, and increased TKI sensitivity. Notably, miR-300 expression was inhibited by BCR-ABL1 in proliferating cells. Accordingly, imatinib restored miR-300 expression in CD34+ dividing progenitors and BCR-ABL1+ cell lines without altering miR-300 levels in quiescent (CFSEMAX) CMLCD34+ cells (n = 3), consistent with the BCR-ABL1 kinase-dependent activation of the Jak2/SET/PP2A/β-catenin pathway in CML progenitors but not quiescent Ph+ HSCs. Surprisingly, miR-300 levels were increased in CD34+CD38- compared to CD34+CD38+ CML cells, and >20-fold higher in CFSEMAX compared to dividing CMLCD34+ cells (n = 4).

To determine whether enhanced miR-300 expression in quiescent cells depends on cell autonomous events or is induced by the BM microenvironment, we exposed BCR-ABL+ cells to conditioned medium (CM) of HS-5 or hTERT mesenchymal stem cells (MSC). CM strongly decreased proliferation, induced imatinib but not FTY720 (PP2A activator) resistance, increased miR-300 levels, decreased BCR-ABL1 activity and Jak2 expression but not its activity, and did not alter β-catenin levels or PP2A activity. Interestingly, miR-300 was found in MSC-derived exosomes, and its expression increased in BCR-ABL1+ cells exposed to exosomes. Accordingly, proliferation of CML-BCCD34+and LAMA-84 cells was strongly reduced upon exposure to MSC-derived exosomes. These effects were abolished when we used CM from MSCs transduced with a miR-300 antagomir.

Altogether our results indicate that downregulation of miR-300 appears necessary for the activation of JAK2/SET/PP2A/β-catenin survival signals in CML progenitors. Conversely, increased miR-300 levels (endogenous and MSC-derived) seem to be required for HSC quiescence.

Citation Format: Rossana Trotta, Giovannino Silvestri, Lorenzo Stramucci, Justin J. Ellis, Justine Yu, Jason J. Harb, Paolo Neviani, Guido Marcucci, Klara Srutova, Polakova K. Machova, Denis-Claude Roy, Peter Hokland, Michael Deininger, Ravi Bhatia, Carlo Gambacorti-Passerini, Dragana Milojkovic, Alistair Reid, Jane Apperley, Ferenc Livak, Jianfei Qi, Maria R. Baer, Danilo Perrotti. Role of the MSC-derived exosomal and endogenous JAK2-SET/PP2A-β-catenin-modulator miR-300 in leukemic stem/progenitor proliferation and survival in CML. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 951.

Behavioural and faecal glucocorticoid metabolite responses of single caging in six cats over 30 days

OBJECTIVES

The aim was to characterize the behaviour and faecal glucocorticoid metabolite (FGM) responses of six cats (Felis catus) to single caging for 30 days.

DESIGN

In this observational study, changes in outcome measures were monitored with habituation to caging. Continuous focal observations of the activity, location in the cage, and posture were conducted from video recordings for one 24-hour period/week/cat. Cat-Stress-Scores were recorded daily. All faecal samples were collected for analysis of FGM.

RESULTS

The percentage time spent eating increased, while percentage time spent grooming decreased, from week 1 to week 2. Cat-Stress-Score declined significantly from week 1 to week 2. FGM concentrations were significantly greater in week 1 than in week 5. A posthabituation time budget of the behaviour of the cats in the single cages showed that inactivity dominated the time budget and the cats were located on the shelf almost half of the time.

CONCLUSIONS

Results suggests that a shelf was a resource of value to the cats, and that its inclusion in enclosure design is important. Quantitative and qualitative behavioural data indicated that there was an initial stress response to caging that stabilised after the first week, while FGM concentration took longer to stabilise.

Preclinical and clinical efficacy of XPO1/CRM1 inhibition by the karyopherin inhibitor KPT-330 in Ph+ leukemias

As tyrosine kinase inhibitors (TKIs) fail to induce long-term response in blast crisis chronic myelogenous leukemia (CML-BC) and Philadelphia chromosome-positive (Ph(+)) acute lymphoblastic leukemia (ALL), novel therapies targeting leukemia-dysregulated pathways are necessary. Exportin-1 (XPO1), also known as chromosome maintenance protein 1, regulates cell growth and differentiation by controlling the nucleocytoplasmic trafficking of proteins and RNAs, some of which are aberrantly modulated in BCR-ABL1(+) leukemias. Using CD34(+) progenitors from CML, B-ALL, and healthy individuals, we found that XPO1 expression was markedly increased, mostly in a TKI-sensitive manner, in CML-BC and Ph(+) B-ALL. Notably, XPO1 was also elevated in Ph(-) B-ALL. Moreover, the clinically relevant XPO1 inhibitor KPT-330 strongly triggered apoptosis and impaired the clonogenic potential of leukemic, but not normal, CD34(+) progenitors, and increased survival of BCR-ABL1(+) mice, 50% of which remained alive and, mostly, became BCR-ABL1 negative. Moreover, KPT-330 compassionate use in a patient with TKI-resistant CML undergoing disease progression significantly reduced white blood cell count, blast cells, splenomegaly, lactate dehydrogenase levels, and bone pain. Mechanistically, KPT-330 altered the subcellular localization of leukemia-regulated factors including RNA-binding heterogeneous nuclear ribonucleoprotein A1 and the oncogene SET, thereby inducing reactivation of protein phosphatase 2A tumor suppressor and inhibition of BCR-ABL1 in CML-BC cells. Because XPO1 is important for leukemic cell survival, KPT-330 may represent an alternative therapy for TKI-refractory Ph(+) leukemias.

PP2A-activating drugs selectively eradicate TKI-resistant chronic myeloid leukemic stem cells

The success of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) depends on the requirement for BCR-ABL1 kinase activity in CML progenitors. However, CML quiescent HSCs are TKI resistant and represent a BCR-ABL1 kinase-independent disease reservoir. Here we have shown that persistence of leukemic HSCs in BM requires inhibition of the tumor suppressor protein phosphatase 2A (PP2A) and expression--but not activity--of the BCR-ABL1 oncogene. Examination of HSCs from CML patients and healthy individuals revealed that PP2A activity was suppressed in CML compared with normal HSCs. TKI-resistant CML quiescent HSCs showed increased levels of BCR-ABL1, but very low kinase activity. BCR-ABL1 expression, but not kinase function, was required for recruitment of JAK2, activation of a JAK2/β-catenin survival/self-renewal pathway, and inhibition of PP2A. PP2A-activating drugs (PADs) markedly reduced survival and self-renewal of CML quiescent HSCs, but not normal quiescent HSCs, through BCR-ABL1 kinase-independent and PP2A-mediated inhibition of JAK2 and β-catenin. This led to suppression of human leukemic, but not normal, HSC/progenitor survival in BM xenografts and interference with long-term maintenance of BCR-ABL1-positive HSCs in serial transplantation assays. Targeting the JAK2/PP2A/β-catenin network in quiescent HSCs with PADs (e.g., FTY720) has the potential to treat TKI-refractory CML and relieve lifelong patient dependence on TKIs.

Bcl-xL anti-apoptotic network is dispensable for development and maintenance of CML but is required for disease progression where it represents a new therapeutic target

The dismal outcome of blast crisis chronic myelogenous leukemia (CML-BC) patients underscores the need for a better understanding of the mechanisms responsible for the development of drug resistance. Altered expression of the anti-apoptoticBcl-xL has been correlated with BCR-ABL leukemogenesis; however, its involvement in the pathogenesis and evolution of CML has not been formally demonstrated yet. Thus, we generated an inducible mouse model in which simultaneous expression of p210-BCR-ABL1 and deletion of bcl-x occurs within hematopoietic stem and progenitor cells. Absence of Bcl-xL did not affect development of the chronic phase-like myeloproliferative disease, but none of the deficient mice progressed to an advanced phenotype, suggesting the importance of Bcl-xL in survival of progressing early progenitor cells. Indeed, pharmacological antagonism of Bcl-xL, with ABT-263, combined with PP242-induced activation of BAD markedly augmented apoptosis of CML-BC cell lines and primary CD34(+) progenitors but not those from healthy donors, regardless of drug resistance induced by bone marrow stromal cell-generated signals. Moreover, studies in which BAD or Bcl-xL expression was molecularly altered strongly support their involvement in ABT-263/PP242-induced apoptosis of CML-BC progenitors. Thus, suppression of the antiapoptotic potential of Bcl-xL together with BAD activation represents an effective pharmacological approach for patients undergoing blastic transformation.

A multidisciplinary approach to the evaluation and treatment of temporomandibular joint and cervical spine dysfunction

This article presents a multidisciplinary approach to the management of temporomandibular joint (TMJ) and cervical spine dysfunction in a heterogeneous population of patients. A methodology for the systematic evaluation and treatment of patients is outlined; case histories are used to illustrate the workings of the model. A study to assess the efficacy of treatment was performed on 27 female and three male adult patients. Results indicated that patients achieved an 87% recovery rate at discharge with an 83% success rate six months after discharge. A control study was undertaken using 16 female and three male adults to establish indications for TMJ occlusal splint therapy in patients who present with questionable TM dysfunction. The multidisciplinary model presented in this article provides a system of patient evaluation and treatment that can be easily adopted by clinicians involved in a team approach to TMJ and cervical spine dysfunction.

Psychotherapy with physicians' families: when attributes in medical practice become liabilities in family life

Personality attributes typically found in successful physicians can lead to difficulties in family life. This paper identifies physicians' positive characteristics and demonstrates with case-history material how these characteristics can contribute to interactional problems with family members. Ways of engaging physicians in treatment and avoiding some of the common pitfalls in working with this group are discussed.

Production of Deoxynivalenol and Zearalenone by Isolates of Fusarium graminearum Schw

Production of deoxynivalenol (DON) on rice, corn, wheat, and barley grains by Fusarium graminearum Schw. NRRL 5883 was investigated. Highest yields (91.9-202 ppm) were obtained on rice; yields on the other substrates were: corn (34.1-84.5 ppm), wheat (3.6-24.4 ppm), and barley (0-6.6 ppm). Fusarium isolates (49) from corn inoculated in the field with strains of F. graminearum , collected from corn plants infected with stalk rot, were tested for DON production on corn. Twenty of these were also tested for zearalenone production. One isolate produced more than 200 ppm DON, 13 produced 20-50 ppm, 17 produced 10-20 ppm, and the rest produced less than 10 ppm. All 20 isolates tested produced zearalenone; 18 produced higher levels of zearalenone (15.4-369 ppm) than of DON. The other 2 isolates formed essentially the same levels of zearalenone and DON-37 and 30 ppm, and 15 and 16 ppm, respectively.

Production of deoxynivalenol and zearalenone by isolates of Fusarium graminearum Schw

The production of deoxynivalenol (DONI) on rice, corn, wheat, and barley grains by Fusarium graminearum Schw. NRRL 5883 was investigated. Highest yields (91.9-202 ppm) were obtained on rice; yields on the other substrates were: corn (34.1-84.5 ppm), wheat (3.6-24.4 ppm), and barley (0-6.6 ppm). Fifty isolates of Fusarium from corn inoculated in the field in 1979 with a mixture of strains of F. graminearum, originally collected from corn plants infected with stalk rot, were tested for DONI production on corn. Twenty of these were also tested for zearalenone production. One isolate produced more than 200 ppm DONI, 13 produced 20-50 ppm, 17 produced 10-20 ppm, and the rest produced less than 10 ppm. The only isolate that did not produce DONI was not identified as F. graminearum. All 20 isolates tested produced zearalenone; 18 produced higher levels of zearalenone (15.4-369 ppm) than of DONI. The other 2 isolates formed essentially the same levels of zearalenone and DONI-37 and 30 ppm, and 15 and 16 ppm, respectively.

Group therapy with anorexic and bulimic patients: implications for therapeutic intervention

The incidence of anorexia nervosa and bulimia has increased markedly during the last decade. Although numerous studies have appeared regarding the dynamics of the eating-disordered patient, few have attempted to link the unique pathology of these patients to specific psychotherapeutic interventions. This paper is based on the authors' experience as co-therapists with a group of eating-disordered patients over an eight months' period. It addresses itself to therapeutic interventions related to the particular dynamics of bulimics and anorexics.

Computed tomography of bowel perforation

The authors present 2 cases of intestinal perforation which were not associated with free intraperitoneal air detectable on abdominal radiographs. Computed tomography demonstrated evidence of intraperitoneal leakage of orally administered contrast material and thereby provided the correct diagnosis.

Production of vomitoxin on corn by Fusarium graminearum NRRL 5883 and Fusarium roseum NRRL 6101

Two vomitoxin-producing isolates of Fusarium spp. were grown on cracked corn for 1 to 8 weeks at 15, 20, 25, 28, and 32 degrees C. Maximum production of vomitoxin by Fusarium graminearum Schw. NRRL 5883 occurred at 30 degrees C and 40 days, and that by Fusarium roseum Schw. NRRL 6101 occurred at 26 degrees C and 41 days. These optimum production points were determined from response surface contour graphs in relation to temperature and time. Only small amounts of vomitoxin were produced at 15 and 20 degrees C by each strain. A 133-microgram quantity of vomitoxin, with an indicated purity of 95%, was isolated per gram of corn fermented with F. graminearum NRRL 5883.

Experimental cerebral zygomycosis in alloxan-diabetic rabbits: variation in virulence among zygomycetes

We investigated the potential of 33 different zygomycete isolates to cause cerebral disease following the intranasal instillation of their spores into ketotic rabbits with alloxan induced diabetes. The isolates represented six thermotolerant species of Rhizopus (R. arrhizus, R. chinensis, R. microsporus, R. oligosporus, R. oryzae, and R. rhizopodiformis), Absidia corymbifera, Cunninghamella bertholletiae, and Rhizomucor pusillus. All 13 isolates of the thermotolerant Rhizopus species proved to be cerebral pathogens as confirmed by culture and histopathology. One isolate of R. oligosporus and one isolate of R. rhizopodiformis, however, were less pathogenic than isolates of other Rhizopus species tested. Cerebral pathogenicity was noted with 2 of 5 isolates of Rh. pusillus and only 1 of 13 A. corymbifera isolates. Two thermotolerant C. bertholletiae cultures, recovered from human lesions, did not cause either cerebral or pulmonary disease in ketotic rabbits. The incidence of pulmonary zygomycosis caused by the isolates of the species of the four genera under study was as follows: Rhizomucor 24%, Rhizopus 22%, Absidia 9%, and Cunninghamella 0%. This study confirms the pathogenic potential of the thermotolerant species of Rhizopus to cause cerebral zygomycosis in ketotic diabetic rabbits and also revealed the potential of Rh. pusillus and A. corymbifera occasionally to cause the same disease in animals and humans.

Elaboration of vomitoxin and zearalenone by Fusarium isolates and the biological activity of Fusarium-produced toxins

Sixteen Fusarium isolates belonging to F. graminearium Schw. and F. culmorum (W.G. Smith) Sacc. produced vomitoxin and zearalenone on cracked corn at 28 degrees C. Quantitation for vomitoxin was by gas-liquid chromatography. This toxin was produced in quantities of 5 to 236 microgram/g of fermented corn. Vomitoxin showed weak antibiotic activity against Penicillium digitatum Sacc., Mucor ramannianus Möller, and Saccharomyces bayanus Sacc., but did not inhibit gram-positive, gram-negative, or acid fast bacteria. The two molds and the yeast were inhibited by T-2 toxin at 5 micrograms, and diacetoxyscirpenol inhibited the molds at 5 micrograms and the yeast at 50 micrograms.

Swine refusal factors elaborated by Fusarium strains and identified as trichothecenes

Fusarium poae (Peck) Wollenw. NRRL 3287, F. nivale (Fr.) Ces. NRRL 3289, and F. moniliforme Sheldon NRRL 3197, each grown on cracked corn (13 days at 28 degrees C), produced refusal factors in pig bioassays. Substantial quantities of trichothecenes were detected in the refused corn: T-2 toxin (30 micrograms/g) was detected in corn fermented with the F. poae strain; the level of vomitoxin (1 microgram/g) in corn cultured with F. nivale did not account for the 48% refusal response in the pigs tested. The F. moniliforme concomitantly produced T-2 toxin (33 micrograms/g) and vomitoxin (1.5 micrograms/g). This strain's taxonomic position was reexamined, and it is shown to be a cultural variant of the species F. tricinctum (Cda.) Sacc.

Survey for fusaria that elaborate T-2 toxin

Of the 136 strains of Fusarium examined, T-2 toxin was confirmed by thinlayer chromatography in 13 of the 21 extracts that inhibited either Rhodotorula rubra or Pencillium digitatum.

Studies of the toxicity of Helminthosporium maydis

Isolates of Helminthosporium maydis from blighted corn were tested for toxicity in mice, rats, swine, rabbits, microorganisms, and tissue culture. Extracts of grains, mycelia, and culture supernatant fluids killed mice on intraperitoneal (ip) injection, but were nontoxic on administration by mouth to swine. The toxin was partially purified and appears to be a glycophospholipid. Histopathological examination revealed that the toxin acted as a severe irritant on ip injection, causing death in laboratory animals. In skin tests with rabbits, considerable exudation occurred, rather than necrosis.

Correlation of biological to chromatographic data for two mycotoxins elaborated by Fusarium

Thirty-seven identified strains of Fusarium, most of them isolated from fescue grass, were tested for their ability to elaborate mycotoxins in laboratory culture. The presence of the toxins was determined by infrared light, thin-layer chromatography, mouse toxicity, fungistatic effects, and phytotoxic properties. A good correlation was demonstrated between T-2 toxin detection by thin-layer chromatography and inhibition of Rhodotorula rubra by culture extracts. All of the strains producing either butenolide or T-2 toxin were toxic to mice with but one exception; those producing T-2 toxin inhibited growth of the yeast.

Survey of tall-fescue pasture: correlation of toxicity of Fusarium isolates to known toxins

Several aspects of fescue foot in cattle suggest that this disease is caused by fungi growing on fescue grass. Certain fungi isolated from winter pasture yield toxins when grown on synthetic medium. Most of these toxin producers belong to the genus Fusarium. All but 1 of the 21 toxic and 7 questionably toxic Fusarium isolates produce either 4-acetamido-4-hydroxy-2-butenoic acid gamma-lactone, or 4beta, 15-diacetoxy-8alpha-(3-methylbutyryloxy)-12, 13-epoxytrichothec-9-en-3alpha-ol, or both.