Distribution of virulence genes and biofilm characterization of human isolates of Streptococcus agalactiae: A pilot study

This study included 21 newly isolated clinical samples of Streptococcus agalactiae (Group B Streptococcus) screened in patients (six male, fifteen female) from various states of India with different infections (urinary tract infections, blood, pus and eye infections). All isolates were identified as Group B Streptococcus (GBS) using hemolytic properties, serogrouping and MALDI-TOF-MS analysis. Six virulence genes, cfb (100%), cylE (90.4%), lmp (85.7%), bca (71.4%), rib (38%) and bac (4.7%) were detected via polymerase chain reaction (PCR). Distribution studies of these six genes revealed five isolates containing five virulence genes (23.8%), followed by ten isolates containing four virulence genes (47.6%). The twenty GBS isolates selected on the glass surface included non-biofilm producers (n = 6, 30%), weak (n = 11, 55%) and moderate biofilm producers (n = 3, 15%). On the polystyrene surface, weak (n = 4, 20%), moderate (n = 2, 10%) and strong (n = 14, 70%) biofilm producers were detected. Live-dead cell staining revealed that more viable cells accumulated in the S. ag 7420 isolate than in the AH1 isolate. Scanning electron microscope (SEM) biofilm analysis showed S. ag AH1 cells appeared as chain-like structures, whereas the S. ag 7420 isolate biofilm cells appeared as fork-like structures on the glass surface. Biofilm elements were analyzed using Energy Dispersive X-Ray Analysis (EDAX) for both isolates and 13 elements with different orders of composition were found. Thus, virulence gene detection, distribution and biofilm formation by these new clinical isolates suggested the virulent nature of these pathogens, which might cause different levels of disease severity in humans.

Preparation of an Intelligent pH Film Based on Biodegradable Polymers for Monitoring the Food Quality and Reducing the Microbial Contaminants

Hydrogel refers to a three-dimensional cross-linked polymeric network made of synthetic or natural polymers that can hold water in its porous structure. The inclusion of hydrophilic groups in the polymer chains, such as amino, carboxyl, and hydroxyl groups, contributes to the hydrogel's water-holding ability. At physiological temperature and pH, these polymeric materials do not dissolve in water, but they do swell significantly in aqueous media. Hydrogel can be manufactured out of almost any water-soluble polymer, and it comes in a variety of chemical compositions and bulk physical properties. Hydrogel can also be made in a variety of ways. Hydrogel comes in a variety of physical shapes, including slabs, microparticles, nanoparticles, coatings, and films. Due to its ease of manufacture and self-application in clinical and fundamental applications, hydrogel has been widely exploited as a drug carrier. Contact lenses, artificial corneas, wound dressing, suture coating, catheters, and electrode sensors are some of the biomedical applications of hydrogels. The pigment color changes were observed from colorless to pale pink followed by dark reddish-pink. Anthocyanin was produced in large quantities and tested using a UV-visible spectrophotometer. At 450-550 nm, the largest peak (absorbance) was detected, indicating the presence of anthocyanin. The FTIR analysis of this study shows the different stretches of bonds at different peaks: 2918.309 (-C-H alkane stretch), 2812.12 (-C-H aldehyde weak intensity), 192320.37/cm (C-O bend), 21915.50, 2029.08/cm (-C=C arene group), 1906.94/cm (=C-H aromatics), 1797.78/cm (=C-H), 1707.94 (-C=O ketene), 1579.70, 1382.96 (C-H alkane strong bend), 889.18/cm (C-H aromatics plane bend), and 412.77/cm (-C-CI strong bond). The spectra of the PVA/chitosan film depict the peak's formation: 1571.88, 1529.55, 1500.62/cm (C-H alkene strong bend), 1492.90, 1483.26, 1467.83/cm (C-H alkene strong bond), 670.48, 443.63, 412.77/cm (-O-H carboxylic acids with great intensity), 1708.93 (-C=O ketone), and 1656.0/cm (alkenyl C=C stretch strong bond).

Discrimination experienced by sexual minority males in Australia: Associations with suicidal ideation and depressive symptoms

INTRODUCTION

Discrimination has been under-examined as a social determinant of the higher rates of poor mental health experienced by sexual minorities. The objectives of our study were to: 1) assess whether discrimination was independently associated with poor mental health among sexual minority males, and 2) assess the potential mediation role of discrimination in the associations between sexual minority status and poor mental health.

METHODS

We used cross-sectional data on 13,230 males aged 18-55 years from the Australian Longitudinal Study on Male Health; bisexual and homosexual males comprised 1.5% and 1.6% of the sample, respectively. We fit Poisson regression and zero-inflated negative binomial regression models to examine suicidality, depressive symptoms and perceived discrimination in the past two years as correlates of suicidality and depressive symptoms.

RESULTS

Statistically significant differences were observed in the prevalence of perceived discrimination by sexual orientation (p < 0.001), with the highest prevalence among bisexual (29.3%) and homosexual (40.4%) males, and the lowest prevalence among heterosexual males (18.6%). After adjusting for confounding, bisexual/homosexual males had higher rates of perceived discrimination (IRR = 1.88, p < 0.001), recent suicidal ideation (IRR = 1.51, p = 0.008), lifetime suicide attempt (IRR = 2.09, p < 0.001) and recent depressive symptoms (IRR = 1.34, p < 0.001) than heterosexual males. Analysis of β-coefficients suggested that discrimination may mediate a small to moderate proportion of the association between sexual minority status and poor mental health.

LIMITATIONS

Use of cross-sectional data.

CONCLUSION

Poor mental health is more common among sexual minority males, and discrimination may be a contributor to these mental health disparities. Reducing discrimination should be considered as part of a strategy to improve the mental wellbeing of sexual minority males.

Household air pollution and COPD: cause and effect or confounding by other aspects of poverty?

SETTING :

Household air pollution (HAP) and chronic obstructive pulmonary disease (COPD) are both major public health problems, reported to cause around 4 million and 3 million deaths every year, respectively. The great majority of these deaths, as well as the burden of disease during life is felt by people in low- and middle-income countries (LMICs).

OBJECTIVE AND DESIGN :

The extent to which HAP causes COPD is controversial; we therefore undertook this review to offer a viewpoint on this from the Global Initiative for COPD (GOLD).

RESULTS :

We find that while COPD is well-defined in many studies on COPD and HAP, there are major limitations to the definition and measurement of HAP. It is thus difficult to disentangle HAP from other features of poverty that are themselves associated with COPD. We identify other limitations to primary research studies, including the use of cross-sectional designs that limit causal inference.

CONCLUSION :

There is substantial preventable morbidity and mortality associated with HAP, COPD and poverty, separately and together. Although it may not be possible to define clear causal links between HAP and COPD, there is a clear urgency to reduce the avoidable burden of disease these inflict on the world’s poor.

Ataxia-telangiectasia mutated interacts with Parkin and induces mitophagy independent of kinase activity. Evidence from mantle cell lymphoma

Ataxia telangiectasia mutated (ATM), a critical DNA damage sensor with protein kinase activity, is frequently altered in human cancers including mantle cell lymphoma. Loss of ATM protein is linked to accumulation of nonfunctional mitochondria and defective mitophagy in both murine thymocytes and in ataxia-telangiectasia cells. However, the mechanistic role of ATM kinase in cancer cell mitophagy is unknown. Here, we provide evidence that FCCP-induced mitophagy in mantle cell lymphoma and other cancer cell lines is dependent on ATM but independent of its kinase function. While Granta-519 mantle cell lymphoma cells possess single copy kinase-dead ATM and are resistant to FCCP-induced mitophagy, both Jeko-1 and Mino cells are ATMproficient and induce mitophagy. Stable knockdown of ATM in Jeko-1 and Mino cells conferred resistance to mitophagy and was associated with reduced ATP production, oxygen consumption, and increased mitochondrial reactive oxygen species. ATM interacts with the E3 ubiquitin ligase Parkin in a kinase-independent manner. Knockdown of ATM in HeLa cells resulted in proteasomal degradation of GFP-Parkin which was rescued by the proteasome inhibitor, MG132, suggesting that the ATMParkin interaction is important for Parkin stability. Neither loss of ATM kinase activity in primary B-cell lymphomas nor inhibition of ATM kinase in mantle cell lymphoma, ataxia-telangiectasia and HeLa cell lines mitigated FCCP- or CCCP-induced mitophagy suggesting that ATM kinase activity is dispensable for mitophagy. Malignant B-cell lymphomas without detectable ATM, Parkin, Pink1, and Parkin-Ub^Ser65 phosphorylation were resistant to mitophagy, providing the first molecular evidence of the role of ATM in mitophagy in mantle cell lymphoma and other B-cell lymphomas.

CXCR5+CD8+ T cells are a distinct functional subset with an antitumor activity

CXCR5 mediates homing of both B and follicular helper T (TFH) cells into follicles of secondary lymphoid organs. We found that CXCR5+CD8+ T cells are present in human tonsils and follicular lymphoma, inhibit TFH-mediated B cell differentiation, and exhibit strong cytotoxic activity. Consistent with these findings, adoptive transfer of CXCR5+CD8+ T cells into an animal model of lymphoma resulted in significantly greater antitumor activity than CXCR5-CD8+ T cells. Furthermore, RNA-Seq-based transcriptional profiling revealed 77 differentially expressed genes unique to CXCR5+CD8+ T cells. Among these, a signature comprised of 33 upregulated genes correlated with improved survival in follicular lymphoma patients. We also showed that CXCR5+CD8+ T cells could be induced and expanded ex vivo using IL-23 plus TGF-β, suggesting a possible strategy to generate these cells for clinical application. In summary, our study identified CXCR5+CD8+ T cells as a distinct T cell subset with ability to suppress TFH-mediated B cell differentiation, exert strong antitumor activity, and confer favorable prognosis in follicular lymphoma patients.

Discovery and Optimization of Novel Hydrogen Peroxide Activated Aromatic Nitrogen Mustard Derivatives as Highly Potent Anticancer Agents

We describe several new aromatic nitrogen mustards with various aromatic substituents and boronic esters that can be activated with H₂O₂ to efficiently cross-link DNA. In vitro studies demonstrated the anticancer potential of these compounds at lower concentrations than those of other clinically used chemotherapeutics, such as melphalan and chlorambucil. In particular, compound 10, bearing an amino acid ester chain, is selectively cytotoxic toward breast cancer and leukemia cells that have inherently high levels of reactive oxygen species. Importantly, 10 was 10-14-fold more efficacious than melphalan and chlorambucil for triple-negative breast-cancer (TNBC) cells. Similarly, 10 is more toxic toward primary chronic-lymphocytic-leukemia cells than either chlorambucil or the lead compound, 9. The introduction of an amino acid side chain improved the solubility and permeability of 10. Furthermore, 10 inhibited the growth of TNBC tumors in xenografted mice without obvious signs of general toxicity, making this compound an ideal drug candidate for clinical development.

Comparative Study of Structural, Morphological, Magneto-Optical and Photo-Catalytic Properties of Magnetically Reusable Spinel MnFe₂O₄ Nano-Catalysts

Spinel MnFe2O4 nanostructures were synthesized by simple, economical and eco-friendly microwave combustion (MCM) and conventional combustion (CCM) methods using metal nitrates and glycine used as the fuel, instead of toxic inorganic/organic catalyst, template and surfactant. Powder XRD and FT-IR, EDX and SAED results were confirmed the products have a cubic phase spinel structure. EDX and SAED results confirmed purity and high crystallinity without any other secondary phase impurities. HR-SEM and HR-TEM analysis indicate that the MCM and CCM products consist of nano- and microstructures, respectively. The optical band gap (Eg) was measured using Kubelka-Munk model and it shows higher value (2.37 eV) for MnFe2O4-MCM than MnFe2O4-CCM (2.15 eV), due to the smaller particle size of MnFe2O4-MCM. VSM results showed a superparamagnetic behavior and the magnetization (Ms) value of MnFe2O4-MCM is higher i.e., 39.68 emu/g than MnFe2O4-CCM (33.59 emu/g). It was found that the sample MnFe2O4-MCM have higher surface area than MnFe2O4-CCM, which in turn leads to the improved performance towards the photocatalytic degradation (PCD) of methylene blue (MB) and it was found that the sample MnFe2O4-MCM show higher PCD efficiency (96.48%) than MnFe2O4-CCM (84.95%). Also, MnFe2O4 show higher activity with good reusability, and eco-friendly materials for industrial and technological applications.

Pharmacodynamics and proteomic analysis of acalabrutinib therapy: similarity of on-target effects to ibrutinib and rationale for combination therapy

Acalabrutinib, a highly selective Bruton's tyrosine kinase inhibitor, is associated with high overall response rates and durable remission in previously treated chronic lymphocytic leukemia (CLL); however, complete remissions were limited. To elucidate on-target and pharmacodynamic effects of acalabrutinib, we evaluated several laboratory endpoints, including proteomic changes, chemokine modulation and impact on cell migration. Pharmacological profiling of samples from acalabrutinib-treated CLL patients was used to identify strategies for achieving deeper responses, and to identify additive/synergistic combination regimens. Peripheral blood samples from 21 patients with relapsed/refractory CLL in acalabrutinib phase I (100-400 mg/day) and II (100 mg BID) clinical trials were collected prior to and on days 8 and 28 after treatment initiation and evaluated for plasma chemokines, reverse phase protein array, immunoblotting and pseudoemperipolesis. The on-target pharmacodynamic profile of acalabrutinib in CLL lymphocytes was comparable to ibrutinib in measures of acalabrutinib-mediated changes in CCL3/CCL4 chemokine production, migration assays and changes in B-cell receptor signaling pathway proteins and other downstream survival proteins. Among several CLL-targeted agents, venetoclax, when combined with acalabrutinib, showed optimal complementary activity in vitro, ex vivo and in vivo in TCL-1 adoptive transfer mouse model system of CLL. These findings support selective targeting and combinatorial potential of acalabrutinib.

Reactivation of Smac-mediated apoptosis in chronic lymphocytic leukemia cells: mechanistic studies of Smac mimetic

Dysfunctional apoptotic machinery is a hallmark feature of chronic lymphocytic leukemia (CLL). Accordingly, targeting apoptosis regulators has been proven a rational approach for CLL treatment. We show that CLL lymphocytes express high levels of XIAP, cIAP1, and cIAP2 compared to normal lymphocytes. Smac mimetic, Smac066, designed to bind to BIR3-domain of IAPs, induce apoptosis in primary CLL cells (n=71; p<0.0001), irrespective of prognostic markers. Apoptosis was mediated by diminished levels of IAPs (XIAP-p=0.02; cIAP-p<0.0001) and increased activation of caspases-8,-9,-3. The caspase-cleavage was in direct association with the levels of apoptosis (r2=0.8 for caspases-8,-9,-3). Correlative analysis revealed a direct relationship between reduction in IAPs and degree of apoptosis (r2=0.6 (XIAP); 0.5 (cIAP2)). There was a strong association between apoptosis, IAP-degradation, and concurrent caspase-activation. Pan-caspase inhibitor Z-Vad-fmk reversed the degradation of Mcl-1, but not IAPs suggesting that smac066 is selective to IAPs, however, Mcl-1 degradation is through caspase-mediated cleavage. Immunoprecipitation experiments revealed physical interaction between caspase-3 and XIAP that was disrupted by smac066. Importantly, XIAP and cIAP2 were markedly induced in bone-marrow and lymph-node microenvironments, providing a basis for IAP antagonists as anti-tumor agents in CLL. Smac066 synergized with ABT-737, revealing a mechanistic rationale to jointly target BH3 and BIR3 domains.

Duvelisib treatment is associated with altered expression of apoptotic regulators that helps in sensitization of chronic lymphocytic leukemia cells to venetoclax (ABT-199)

Duvelisib, an oral dual inhibitor of PI3K-δ and PI3K-γ, is in phase III trials for the treatment of chronic lymphocytic leukemia (CLL) and indolent non-Hodgkin's lymphoma. In CLL, duvelisib monotherapy is associated with high iwCLL (International Workshop on Chronic Lymphocytic Leukemia) and nodal response rates, but complete remissions are rare. To characterize the molecular effect of duvelisib, we obtained samples from CLL patients on the duvelisib phase I trial. Gene expression studies (RNAseq, Nanostring, Affymetrix array and real-time RT-PCR) demonstrated increased expression of BCL2 along with several BH3-only pro-apoptotic genes. In concert with induction of transcript levels, reverse phase protein arrays and immunoblots confirmed increase at the protein level. The BCL2 inhibitor venetoclax induced greater apoptosis in ex vivo-cultured CLL cells obtained from patients on duvelisib compared with pre-treatment CLL cells from the same patients. In vitro combination of duvelisib and venetoclax resulted in enhanced apoptosis even in CLL cells cultured under conditions that simulate the tumor microenvironment. These data provide a mechanistic rationale for testing the combination of duvelisib and venetoclax in the clinic. Such combination regimen (NCT02640833) is being evaluated for patients with B-cell malignancies including CLL.

The Stromal Microenvironment Modulates Mitochondrial Oxidative Phosphorylation in Chronic Lymphocytic Leukemia Cells

Peripheral blood chronic lymphocytic leukemia (CLL) cells are replicationally quiescent mature B-cells. In short-term cultures, supporting stromal cells provide a survival advantage to CLL cells by inducing transcription and translation without promoting proliferation. We hypothesized that the stromal microenvironment augments malignant B cells' metabolism to enable the cells to cope with their energy demands for transcription and translation. We used extracellular flux analysis to assess the two major energy-generating pathways, mitochondrial oxidative phosphorylation (OxPhos) and glycolysis, in primary CLL cells in the presence of three different stromal cell lines. OxPhos, measured as the basal oxygen consumption rate (OCR) and maximum respiration capacity, was significantly higher in 28 patients' CLL cells cocultured with bone marrow-derived NK.Tert stromal cells than in CLL cells cultured alone (P = .004 and <.0001, respectively). Similar OCR induction was observed in CLL cells cocultured with M2-10B4 and HS-5 stromal lines. In contrast, heterogeneous changes in the extracellular acidification rate (a measure of glycolysis) were observed in CLL cells cocultured with stromal cells. Ingenuity Pathway Analysis of CLL cells' metabolomics profile indicated stroma-mediated stimulation of nucleotide synthesis. Quantitation of ribonucleotide pools showed a significant two-fold increase in CLL cells cocultured with stromal cells, indicating that the stroma may induce CLL cellular bioenergy and the RNA building blocks necessary for the transcriptional requirement of a prosurvival phenotype. The stroma did not impact the proliferation index (Ki-67 staining) of CLL cells. Collectively, these data suggest that short-term interaction (≤24 hours) with stroma increases OxPhos and bioenergy in replicationally quiescent CLL cells.

B-cell Receptor Signaling Regulates Metabolism in Chronic Lymphocytic Leukemia

Peripheral blood chronic lymphocytic leukemia (CLL) cells are quiescent but have active transcription and translation processes, suggesting that these lymphocytes are metabolically active. Based on this premise, the metabolic phenotype of CLL lymphocytes was investigated by evaluating the two intracellular ATP-generating pathways. Metabolic flux was assessed by measuring glycolysis as extracellular acidification rate (ECAR) and mitochondrial oxidative phosphorylation as oxygen consumption rate (OCR) and then correlated with prognostic factors. Further, the impact of B-cell receptor signaling (BCR) on metabolism was determined by genetic ablation and pharmacological inhibitors. Compared with proliferative B-cell lines, metabolic fluxes of oxygen and lactate were low in CLL cells. ECAR was consistently low, but OCR varied considerably in human patient samples (n = 45). Higher OCR was associated with poor prognostic factors such as ZAP 70 positivity, unmutated IGHV, high β2M levels, and higher Rai stage. Consistent with the association of ZAP 70 and IGHV unmutated status with active BCR signaling, genetic ablation of BCR mitigated OCR in malignant B cells. Similarly, knocking out PI3Kδ, a critical component of the BCR pathway, decreased OCR and ECAR. In concert, PI3K pathway inhibitors dramatically reduced OCR and ECAR. In harmony with a decline in metabolic activity, the ribonucleotide pools in CLL cells were reduced with duvelisib treatment. Collectively, these data demonstrate that CLL metabolism, especially OCR, is linked to prognostic factors and is curbed by BCR and PI3K pathway inhibition.Implications: This study identifies a relationship between oxidative phosphorylation in CLL and prognostic factors providing a rationale to therapeutically target these processes. Mol Cancer Res; 15(12); 1692-703. ©2017 AACR.

Comparison of Acalabrutinib, A Selective Bruton Tyrosine Kinase Inhibitor, with Ibrutinib in Chronic Lymphocytic Leukemia Cells

Purpose: Ibrutinib inhibits Bruton tyrosine kinase (BTK) by irreversibly binding to the Cys-481 residue in the enzyme. However, ibrutinib also inhibits several other enzymes that contain cysteine residues homologous to Cys-481 in BTK. Patients with relapsed/refractory or previously untreated chronic lymphocytic leukemia (CLL) demonstrate a high overall response rate to ibrutinib with prolonged survival. Acalabrutinib, a selective BTK inhibitor developed to minimize off-target activity, has shown promising overall response rates in patients with relapsed/refractory CLL. A head-to-head comparison of ibrutinib and acalabrutinib in CLL cell cultures and healthy T cells is needed to understand preclinical biologic and molecular effects.Experimental Design: Using samples from patients with CLL, we compared the effects of both BTK inhibitors on biologic activity, chemokine production, cell migration, BTK phosphorylation, and downstream signaling in primary CLL lymphocytes and on normal T-cell signaling to determine the effects on other kinases.Results: Both BTK inhibitors induced modest cell death accompanied by cleavage of PARP and caspase-3. Production of CCL3 and CCL4 chemokines and pseudoemperipolesis were inhibited by both drugs to a similar degree. These drugs also showed similar inhibitory effects on the phosphorylation of BTK and downstream S6 and ERK kinases. In contrast, off-target effects on SRC-family kinases were more pronounced with ibrutinib than acalabrutinib in healthy T lymphocytes.Conclusions: Both BTK inhibitors show similar biological and molecular profile in primary CLL cells but appear different on their effect on normal T cells. Clin Cancer Res; 23(14); 3734-43. ©2016 AACR.

Idelalisib and bendamustine combination is synergistic and increases DNA damage response in chronic lymphocytic leukemia cells

Idelalisib is a targeted agent that potently inhibits PI3Kδ which is exclusively expressed in hematological cells. Bendamustine is a well-tolerated cytotoxic alkylating agent which has been extensively used for treatment of chronic lymphocytic leukemia (CLL). Both these agents are FDA-approved for CLL. To increase the potency of idelalisib and bendamustine, we tested their combination in primary CLL lymphocytes. While each compound alone produced a moderate response, combination at several concentrations resulted in synergistic cytotoxicity. Idelalisib enhanced the bendamustine-mediated DNA damage/repair response, indicated by the phosphorylation of ATM, Chk2, and p53. Each drug alone activated γH2AX but combination treatment further increased the expression of this DNA damage marker. Compared with the control, idelalisib treatment decreased global RNA synthesis, resulting in a decline of early-response and short-lived MCL1 transcripts. In concert, there was a decline in total Mcl-1 protein in CLL lymphocytes. Isogenic mouse embryonic fibroblasts lacking MCL1 had higher sensitivity to bendamustine alone or in combination compared to MCL1 proficient cells. Collectively, these data indicate that bendamustine and idelalisib combination therapy should be investigated for treating patients with CLL.

Wilms' tumour 1 gene mutations in south Indian children with steroid-resistant nephrotic syndrome

Background & objectives:

Clinically, nephrotic syndrome (NS) is a diverse group of symptoms; about 20 per cent of NS cases are resistant to steroid treatment, and within ten years they progress to end-stage renal disease. The present study was undertaken to identify the mutations of Wilms’ tumour 1 (WT1) gene in steroid-resistant NS (SRNS) children.

Methods:

A total of 173 children with SRNS and 100 children in the control group were enrolled in the study. DNA extraction was done, screened for WT1 (exons 8 and 9) gene amplified by polymerase chain reaction and direct sequencing. Karyotype analyses were done for WT1 mutation cases.

Results:

WT1 mutations were found in three of 173 SRNS cases (2 girls, 1 boy). All of them had intron 9 (IVS 9 + 4 C>T, 2; IVS + 5 G>A, 1) mutation. Of these three cases, one had familial and another two had sporadic history. Renal histology analysis showed two cases with focal segmental glomerulosclerosis (FSGS) and they had external female genitalia but 46, XY karyotype. Both of them had streak gonads. Of the three cases, one expired.

Interpretation & conclusions:

The findings of the present study indicate that all females with SRNS-FSGS should be screened for WT1 gene mutation to diagnose whether they have FS for possible gonadectomy.

Hide and Seek: The Game Between Chronic Lymphocytic Leukaemia Cells and B Cell Receptor Signalling Inhibitors

The emergence of B cell receptor (BCR) kinase inhibitors has recently changed the treatment landscape in chronic lymphocytic leukaemia (CLL). The inhibitors that selectively target potential kinases downstream from BCR (particularly Bruton’s tyrosine kinase [BTK] and phosphoinositide 3-kinase [PI3K]) have replaced conventional chemotherapy for high-risk CLL. Ibrutinib and idelalisib are the respective first-in-class BTK and PI3K-δ inhibitors that are US Food and Drug Administration (FDA) approved for CLL treatment, with promising second-generation molecules under development. Differing from idelalisib, duvelisib (IPI-145) inhibits both delta and gamma isoforms of PI3K. Kinase inhibitors have gained popularity in the clinic primarily due to their ability to induce remissions in the vast majority of patients, even in patients with high-risk disease features, without causing haematotoxicity. In particular, they interfere with the homing capabilities of CLL cells residing in their respective microenvironments and cause lymphocytosis via redistribution of tissue-resident CLL cells into the peripheral blood. Thereby, BCR inhibitors can seek out and target hiding CLL cells in the lymph node and marrow niches. In this review, we discuss laboratory and clinical aspects of the BCR inhibitors that have recently advanced the treatment of B cell malignancies, with a particular emphasis on CLL. Despite the excitement about this new class of compounds targeting BCR signalling, single agent therapy with kinase inhibitors has limitations, requiring continuous kinase suppression to maintain remissions, which generally are partial remissions, indicating that combination strategies will become important for moving the field forward.

Molecular evidence of Zn chelation of the procaspase activating compound B-PAC-1 in B cell lymphoma

The resistance of apoptosis in cancer cells is pivotal for their survival and is typically ruled by mutations or dysregulation of core apoptotic cascade. Mantle cell lymphoma (MCL) is a non-Hodgkin's B-cell malignancy expressing higher anti-apoptotic proteins providing survival advantage. B-PAC-1, a procaspase activating compound, induces apoptosis by sequestering Zn bound to procaspase-3, but the amino acids holding Zn in Caspase-3 is not known. Here we show that reintroduction of WT caspase-3 or 7 in Caspase3-7 double knock-out (DKO) mouse embryonic fibroblasts (MEF) promoted B-PAC-1 to induce apoptosis (27-43%), but not in DKO MEFs or MEFs expressing respective Casp3-7 catalytic mutants (12-13%). Using caspase-6 and -9 exosite analysis, we identified and mutated predicted Zn-ligands in caspase-3 (H108A, C148S and E272A) and overexpressed into DKO MEFs. Mutants carrying E272A abrogated Zn-reversal of apoptosis induced by B-PAC-1 via higher XIAP and smac expressions but not in H108A or C148S mutants. Co-immunoprecipitation analysis revealed stronger XIAP-caspase-3 interaction suggesting a novel mechanism of impulsive apoptosis resistance by disrupting predicted Zn-ligands in caspase-3. B-PAC-1 sponsored apoptosis in MCL cell lines (30-73%) via caspase-3 and PARP cleavages accompanied by loss of Mcl-1 and IAPs including XIAP while Zn substantially abrogated B-PAC-1-driven apoptosis (18-36%). In contrary, Zn is dispensable to inhibit staurosporin, bendamustine, ABT199 or MK206-induced apoptosis. Consistent to cell lines, B-PAC-1 stimulated cell death in primary B-lymphoma cells via caspase-3 cleavage with decline in both Mcl-1 and XIAP. This study underscores the first genetic evidence that B-PAC-1 driven apoptosis is mediated via Zn chelation.

Susceptible and protective associations of HLA DRB1*/DQB1* alleles and haplotypes with ischaemic stroke

Stroke has emerged as the second commonest cause of mortality worldwide and is a major public health problem. For the first time, we present here the association of human leucocyte antigen (HLA)-DRB1*/DQB1* alleles and haplotypes with ischaemic stroke in South Indian patients. Ischaemic stroke (IS) cases and controls were genotyped for HLA-DRB1*/DQB1* alleles by polymerase chain reaction sequence-specific primers (PCR-SSP) method. The frequencies of HLA class II alleles such as DRB1*04, DRB1*07, DRB1*11, DRB1*12, DRB1*13, DQB1*02 and DQB1*07 were high in IS patients than in the age- and gender-matched controls, suggesting that the individuals with these alleles are susceptible to ischaemic stroke in South India. The frequencies of alleles such as DRB1*03, DRB1*10, DRB1*14, DQB1*04 and DQB1*05 were less in IS cases than in the controls, suggesting a protective association. Haplotypes DRB1*04-DQB1*0301, DRB1*07-DQB1*02, DRB1*07-DQB1*0301, DRB1*11-DQB1*0301 and DRB1*13-DQB1*06 were found to be high in IS patients conferring susceptibility. The frequency of haplotype DRB1*10-DQB1*05 was high in controls conferring protection. IS-LVD and gender-stratified analysis too confirmed these susceptible and protective associations. Thus, HLA-DRB1*/DQB1* alleles and haplotypes strongly predispose South Indian population to ischaemic stroke. Further studies in different populations with large sample size or the meta-analysis are needed to explain the exact mechanism of associations of HLA gene(s) with IS.

Regulation of Mcl-1 expression in context to bone marrow stromal microenvironment in chronic lymphocytic leukemia

A growing body of evidence suggests that the resistance of CLL cells to apoptosis is partly mediated through the interactions between leukemia cells and adjacent stromal cells residing in the lymphatic tissue or bone marrow microenvironment. Mcl-1, an anti-apoptotic protein that is associated with failure to treatment is up-regulated in CLL lymphocytes after interaction with microenvironment. However, the regulation of its expression in context to microenvironment is unclear. We evaluated and compared changes in Mcl-1 in CLL B-cells in suspension culture and when co-cultured on stromal cells. The blockade of apoptosis in co-cultured CLL cells is associated with diminution in caspase-3 and PARP cleavage and is not dependent on cytogenetic profile or prognostic factors of the disease. Stroma-derived resistance to apoptosis is associated with a cascade of transcriptional events such as increase in levels of total RNA Pol II and its phosphorylation at Ser2 and Ser5, increase in the rate of global RNA synthesis, and amplification of Mcl-1 transcript levels. The latter is associated with increase in Mcl-1 protein level without an impact on the levels of Bcl-2 and Bcl-xL. Post-translational modifications of protein kinases show increased phosphorylation of Akt at Ser473, Erk at Thr202/Tyr204 and Gsk-3β at Ser9 and augmentation of total Mcl-1 accumulation along with phosphorylation at Ser159/Thr163 sites. Collectively, stroma-induced apoptosis resistance is mediated through signaling proteins that regulate transcriptional and translational expression and post-translational modification of Mcl-1 in CLL cells in context to bone marrow stromal microenvironment.

Abstract 2658: Stromal microenvironment modulates mitochondrial metabolism in chronic lymphocytic leukemia cells and is abrogated by PI3K δ and γ inhibition

Chronic Lymphocytic Leukemia (CLL) is characterized by the accumulation of replicationally quiescent mature B cells, as they fail to undergo apoptosis. Supporting stromal cells in the microenvironment provide survival advantage to CLL cells. We hypothesized that stromal cells may have an active role in energy metabolism of malignant B-cells in order to cope with their energy demands and is driven by PI3K pathway. We assessed the two major energy generating pathways (glycolysis and mitochondrial Oxidative Phosphorylation (OXPHOS)), in primary CLL cells using Extracellular Flux Analyzer (Seahorse Bioscience), in presence of three different stromal cell lines. Glycolysis measured as ECAR did not show stroma-induced increase, which is commonly upregulated in most cancers. A decrease in glucose uptake in coculture experiments, further suggested that glycolysis was not upregulated in CLL cells (n = 7, p&lt;0.01). Surprisingly, OXPHOS measured as OCR in CLL cells from 29 patients showed a statistically significant increase, (p&lt;0.01) upon coculture and contact with NK-Tert stromal cells. Similar OCR induction was observed in presence of M2-10B4 and HS-5 stromal cell lines. However, no significant changes were observed in mitochondrial mass, membrane potential and ROS, upon co-culture. All four ribonucleotide triphosphate pools (ATP, CTP, GTP, and UTP), showed a 2-fold and statistically significant increase after interacting with stroma cell line for 48hr. Changes in metabolomics and NTP pools were not due to cell growth as stroma cocultures did not impact proliferation index (Ki-67 staining) of CLL cells. In parallel to these changes in metabolomics, stromal microenvironment increased AKT phosphorylation at Thr308 and Ser473 indicating upregulation of PI3K pathway. Consistently, inhibition of PI3K axis by IPI-145 (duvelisib), a PI3K δ and γ inhibitor, currently in phase III trials for CLL, decreased phospho-AKT in CLL samples (n = 6) and dramatically reduced OCR (n = 7) and ECAR in CLL cells in suspension cultures without causing cytotoxicity. Importantly, stroma-mediated increase in OCR in CLL cells was significantly compromised by IPI-145 treatment (n = 5; p&lt;0.05). In parallel, stroma-driven AKT phosphorylation in CLL samples (n = 6) was also reduced with IPI-145. Preliminary data also indicates a decline in NTP pools, upon drug treatment. Collectively, these data suggest that stroma impacts metabolomics in quiescent CLL cells which is in part driven by PI3K/AKT pathway.

Citation Format: Hima V. Vangapandu, Kumudha Balakrishnan, Mary L. Ayres, William G. Wierda, Michael J. Keating, Christine M. Stellrecht, Varsha Gandhi. Stromal microenvironment modulates mitochondrial metabolism in chronic lymphocytic leukemia cells and is abrogated by PI3K δ and γ inhibition. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2658. doi:10.1158/1538-7445.AM2015-2658

Abstract 2657: Elevated level of BCL-2 is the primary target for inhibition during duvelisib (IPI-145) therapy: ABT-199 neutralizes the resistance mechanism in chronic lymphocytic leukemia

Inhibition of BTK by ibrutinib, PI3K-delta with idelalisib, or PI3K-delta and gamma with duvelisib (IPI-145), all components of B-cell receptor (BCR) pathway, has significantly improved the treatment outcome in chronic lymphocytic leukemia (CLL) via disrupting the interactions with microenvironment. Though BCR network inhibitors induce durable remission in the majority of CLL patients, a proportion of patients that initially respond to treatment develop resistance or some show maintained lymphocytosis in the blood. Identifying and overcoming resistance mechanisms will be crucial for the most effective combinatorial use of these agents. Duvelisib is an orally bioavailable, highly potent small molecule inhibitor of p110δ and p110γ with KD values of 0.023 nM and 0.24 nM, respectively. Preclinical investigations with duvelisib overcame signals from PI3K/AKT/S6 pathway and promoted apoptosis in primary CLL cells (Balakrishnan et al, ASH 2013). Duvelisib is currently in a phase III trial in CLL. During first phase I study, we performed molecular investigations. PBMCs collected from CLL patients from Phase I study of duvelisib treatment (Pre/Day 0 and Post/Day 28) were subjected to RPPA analysis (n = 7). Interestingly, of the 141 proteins analyzed, Bcl-2 was maximally and significantly elevated in Day 28 samples (mean fold + SEM: 1.7 + 0.2; p = 0.015), suggesting that this could be in part the mechanism involved in resistance during therapy. Further analysis of protein expression by immunoblotting confirmed that Bcl-2 protein was elevated in post-treatment samples (1.3 + 0.1; p = 0.086; n = 7). This was in conjunction with elevated levels of Bcl-2 transcripts analyzed by mRNA array (TaqMan Human Apoptosis - 93 genes) assay (3.0 + 0.4; p = 0.002) and RT-PCR (1.9 + 0.2; p = 0.003), while other anti-apoptotic genes (Bfl-1, Mcl-1, Bcl-w Bcl-g, Bcl-b, Bcl-xL) were unchanged. Importantly, ex-vivo incubations of pre- and post- duvelisib samples with 3 nM ABT-199, a highly selective clinically promising Bcl-2 protein antagonist, induced significantly greater apoptosis in post-therapy samples (79%) in comparison to pre-treatment (58%) samples suggesting that Bcl-2 is the primary target for inhibition during duvelisib intake (n = 5; p = 0.041). In addition, duvelisib induced sensitivity on ex-vivo post- duvelisib clinical samples (n = 15) was specifically towards ABT-199 and produced significantly more apoptosis in the presence of ABT-199 (45%, p&lt;0.0001; 3 nM) compared to other clinically-relevant agents such as ibrutinib (1%, p = 0.10; 10 μM), idelalisib (4% p = 0.05; 10 μM) or ABT-737 (16%, p = 0.0002; 10 nM). We report that elevated Bcl-2 level is the primary target for inhibition during duvelisib therapy and thereby combination with ABT-199 could be a rational approach to overcome the resistance mechanism.

Citation Format: Viralkumar M. Patel, Kumudha Balakrishnan, Renato Guerrieri, William Wierda, Susan O'Brien, Varsha Gandhi. Elevated level of BCL-2 is the primary target for inhibition during duvelisib (IPI-145) therapy: ABT-199 neutralizes the resistance mechanism in chronic lymphocytic leukemia. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2657. doi:10.1158/1538-7445.AM2015-2657

Management of tripod fractures (zygomaticomaxillary complex) 1 point and 2 point fixations: A 5-year review

The zygomaticomaxillary complex (ZMC) plays a key role in the structure, function, and esthetic appearance of the facial skeleton. They can account for approximately 40% of mid-face fractures. They are the second most common facial bone fracture after nasal bone injuries. The fracture complex results from a direct blow to the malar eminence and results in three distinct fracture components that disrupt the anchoring of the zygoma. In addition, the fracture components may result in impingement of the temporalis muscle, trismus (difficulty with mastication) and may compromise the infraorbital foramen/nerve resulting in hypesthesia within its sensory distribution. A 4-year retrospective review of all patients treated with ZMC fractures at oral and maxillofacial surgery department, sree balaji dental college and hospital was performed. Computed tomography scans were reviewed. Demographics, treatment protocols, outcomes, complications, reoperations, and length of follow-up were identified. A total of 245 patients was identified by the Current Procedural Terminology codes for ZMC fractures. Closed or open reduction methods were performed with the goal of treatment being preservation of normal facial structure, sensory function, globe position, and mastication functionality. Unacceptably poor surgical outcomes are uncommon. Significant facial asymmetry requiring surgical revision occurs in 3-4% of patients. Postoperative infection rates are extremely low, and these infections nearly always resolve with oral antibiotics. In general, the long-term prognosis after repair of ZMC fractures is very good.

Bupivacaine versus lignocaine as the choice of locall anesthetic agent for impacted third molar surgery a review

One of the most important goal in minor surgical procedures is to achieve proper and sufficient anesthesia and analgesia preoperatively, intraoperatively and in the immediate postoperative period. Several local anesthetic agents have been cited in the literature and studied. Bupivacaine is one of the most common long-acting anesthetic agents being used for surgical removal of impacted third molars. Lignocaine is one of the commonest short-acting anesthetic agents being used for the same procedure. In this review article, the analgesic and anesthetic abilities of the bupivacaine versus lignocaine have been reviewed while surgical removal of impacted third molars.

Immediate placement of endosseous implants into the extraction sockets

Implant by definition "means any object or material, such as an alloplastic substance or other tissue, which is partial or completely inserted into the body for therapeutic, diagnostic, prosthetic, or experimental purpose." The placement of a dental implant in an extraction socket at the time of extraction or explantation is known as immediate implant placement whereas delayed placement of implant signifies the implant placement in edentulous areas where healing has completed with new bone formation after the loss of tooth/teeth. Recent idea goes by "why late when it can be done immediately." There are several advantages of immediate placement of implants, and lots of studies have been done. In this article, the advantages and disadvantages of immediate versus delayed placement of implants have been reviewed.

The phosphoinositide-3-kinase (PI3K)-delta and gamma inhibitor, IPI-145 (Duvelisib), overcomes signals from the PI3K/AKT/S6 pathway and promotes apoptosis in CLL

The functional relevance of the B-cell receptor (BCR) and the evolution of protein kinases as therapeutic targets have recently shifted the paradigm for treatment of B-cell malignancies. Inhibition of p110δ with idelalisib has shown clinical activity in chronic lymphocytic leukemia (CLL). The dynamic interplay of isoforms p110δ and p110γ in leukocytes support the hypothesis that dual blockade may provide a therapeutic benefit. IPI-145, an oral inhibitor of p110δ and p110γ isoforms, sensitizes BCR-stimulated and/or stromal co-cultured primary CLL cells to apoptosis (median 20%, n=57; P<0.0001) including samples with poor prognostic markers, unmutated IgVH (n=28) and prior treatment (n=15; P<0.0001). IPI-145 potently inhibits the CD40L/IL-2/IL-10 induced proliferation of CLL cells with an IC50 in sub-nanomolar range. A corresponding dose-responsive inhibition of pAKT(Ser473) is observed with an IC50 of 0.36 nM. IPI-145 diminishes the BCR-induced chemokines CCL3 and CCL4 secretion to 17% and 37%, respectively. Pre-treatment with 1 μM IPI-145 inhibits the chemotaxis toward CXCL12; reduces pseudoemperipolesis to median 50%, inferring its ability to interfere with homing capabilities of CLL cells. BCR-activated signaling proteins AKT(Ser473), BAD(Ser112), ERK(Thr202/Tyr204) and S6(Ser235/236) are mitigated by IPI-145. Importantly, for clinical development in hematological malignancies, IPI-145 is selective to CLL B cells, sparing normal B- and T-lymphocytes.

Pharmacological and Protein Profiling Suggests Venetoclax (ABT-199) as Optimal Partner with Ibrutinib in Chronic Lymphocytic Leukemia

PURPOSE

Bruton's tyrosine kinase (BTK) is a critical enzyme in the B-cell receptor pathway and is inhibited by ibrutinib due to covalent binding to the kinase domain. Though ibrutinib results in impressive clinical activity in chronic lymphocytic leukemia (CLL), most patients achieve only partial remission due to residual disease. We performed a pharmacologic profiling of residual circulating CLL cells from patients receiving ibrutinib to identify optimal agents that could induce cell death of these lymphocytes.

EXPERIMENTAL DESIGN

Ex vivo serial samples of CLL cells from patients on ibrutinib were obtained prior and after (weeks 2, 4, and 12) the start of treatment. These cells were incubated with PI3K inhibitors (idelalisib or IPI-145), bendamustine, additional ibrutinib, or BCL-2 antagonists (ABT-737 or ABT-199), and cell death was measured. In vitro investigations complemented ex vivo studies. Immunoblots for BTK signaling pathway and antiapoptotic proteins were performed.

RESULTS

The BCL-2 antagonists, especially ABT-199, induced high cell death during ex vivo incubations. In concert with the ex vivo data, in vitro combinations also resulted in high cytotoxicity. Serial samples of CLL cells obtained before and 2, 4, 12, or 36 weeks after the start of ibrutinib showed inhibition of BTK activity and sensitivity to ABTs. Among the three BCL-2 family antiapoptotic proteins that are overexpressed in CLL, levels of MCL-1 and BCL-XL were decreased after ibrutinib while ABT-199 selectively antagonizes BCL-2.

CONCLUSIONS

Our biologic and molecular results suggest that ibrutinib and ABT-199 combination should be tested clinically against CLL.

Abstract 4328: Marrow stromal cells promote mitochondrial energy metabolism in primary CLL cells without impacting cellular proliferation

Chronic Lymphocytic Leukemia (CLL) is characterized by the accumulation of replicationally quiescent mature B cells, as they fail to undergo apoptosis. Studies show that supporting stromal cells in the microenvironment provide survival advantage to CLL cells by conferring resistance to spontaneous and drug-induced apoptosis. A recent transcriptome characterization showed that compared to normal lymphocytes, genes involved in metabolic pathways were upregulated in CLL cells (Ferreira et al., Genome Res 2013). We hypothesized that stromal cells may have an active role on energy metabolism of malignant B-cells in order to cope with their energy demands. We assessed the major energy generating pathways (glycolysis and mitochondrial OXPHOS), in primary CLL cells using Extracellular Flux Analyzer (Seahorse Bioscience). The oxygen consumption rate (OCR) in CLL cells is surprisingly high compared to the proliferating lymphoma cell lines. Whereas, the glycolytic flux, measured as extracellular acidification rate (ECAR) is significantly low, suggesting that OXPHOS measured as OCR is upregulated in CLL cells; hence we focused on OXPHOS. Increased OCR was not impacted by age, Rai stage, lymphocyte counts, β2M, IgVH mutation status or LDH levels. However, ZAP70 positive (a poor-prognosis marker) samples had higher OCRs (n=30, p =0.002). Compared to males, samples obtained from female patients had higher OCRs (n=33, p = 0.043). Co-culturing with stroma (NK.tert human cell line) for 18-24 hrs had an impact on OCR in CLL; out of 30 samples, 24 showed a significant (p - 0.0005) increase in basal OCR and/or spare respiratory capacity (SRC, biological parameter of mitochondrial respiration). In addition, 11 of 12 CLL samples showed a significant increase in basal OCR, when plated on stroma without prior incubation (p &lt; 0.0001), whereas the SRC did not statistically change (p - 0.9791). Moreover, the differences associated with gender and ZAP70 status were more pronounced when CLL cells were co-cultured on stroma (ZAP70 status, n= 30, p = 0.0013; Gender n=28, p =0.0173). In contrast to OCR, ECAR did not show stroma-induced statistical increase. Preliminary data with murine stroma line (M2-10B4) also showed upregulation of OCR in CLL cells. The stroma-mediated increase in OCR was not due to an increase in proliferation index; as CLL cells on stroma stained negative for Ki67 (marker for cell proliferation). Metabolite analysis by mass spectrometry of 5 CLL sample sets revealed that TCA cycle and gluconeogenesis were among the top 5 hits of pathways upregulated by stromal co-culture. At the molecular level, CLL cells in presence of stroma showed an increased p-AKT and p-ERK levels. Active AKT modulates GLUT4 protein levels, which was expressed in all 5 samples. Collectively, these data suggest that in CLL cells, OXPHOS (measured as OCR) is high and was further induced by stroma.

Citation Format: Hima Venkata Vangapandu, Kumudha Balakrishnan, William G. Wierda, Michael J. Keating, Christine M. Stellrecht, Varsha Gandhi. Marrow stromal cells promote mitochondrial energy metabolism in primary CLL cells without impacting cellular proliferation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4328. doi:10.1158/1538-7445.AM2014-4328

Abstract 4530: Mechanism-based combination therapy of PI3 kinase delta-specific inhibitor Idelalisib with Bendamustine in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy influenced by oncogenic mutations and the factors of the microenvironment such as BCR signaling that promote B-cell survival and proliferation. BCR signaling cascade activates multiple downstream effector kinases including Phosphatidylinositol 3-kinase (PI3K) pathway that is critically important in the clonal expansion of B-CLL cells. Of the four p110 catalytic subunit isoforms, p110 delta isoform is over-expressed in many B-cell malignancies, including CLL. Idelalisib (I) is a small molecule highly selective PI3K delta inhibitor. I promotes apoptosis in B-cell malignancies by disrupting the molecular pathways related to BCR signaling, leukemia cell migration and microenvironment. Importantly, I inhibits BCR derived PI3K signaling, which ultimately dampens AKT activation. Bendamustine (B), an alkylating agent that induces DNA damage and repair response, is recently approved for CLL therapy. Kinases that are important for CLL cell survival may also be activated during this DNA damage response. Based on this background, we hypothesize that the treatment of CLL cells with I and B may modulate the repair mechanisms and sensitize B-CLL cells to enhanced apoptosis. Our model system includes primary CLL patient samples with or without BCR activation. Our findings show that compared to time-matched DMSO control, treatment with I or B as a single agent resulted in 5-15% and 5-20% dose-dependent cell death, respectively. In contrast, combined treatment (I+B at 0.5+5, 1+10, 3+15, 5+20, 10+30 µM) of CLL cells for 24 h resulted in 10-40% of apoptosis as measured by annexin/PI (n=6). This was synergistic with a combination index of &lt;0.8 (Chou-Chou, CalcuSyn method). Moreover, at these five concentrations, I+B combination resulted in 20-60% decline in phospho-AKT (S473) but not total AKT. In contrast, B (up to 15 µM) resulted in 40-60% increase in phospho-AKT levels. Phosphorylation of H2Ax, a measure of DNA damage response, is induced with combination treatment in comparison to single agent treatments. We next investigated the molecular targets downstream of BCR signaling. Primary CLL cells treated with I, in assays with BCR (IgM) stimulation show a time-dependent decrease in phospho-AKT except at 24 h (n=4). For phospho-GSK3β, a downstream target of AKT, results were heterogeneous. In contrast, at 24 h, I treatment consistently resulted in a decrease in total Mcl-1; without any change in Bcl-2 protein levels. The decline in Mcl-1 protein level may be due to a decrease in transcription as total RNA synthesis was decreased by at least 30% after treatment with I. Transcript levels and post-translational modification of Mcl-1 will elucidate the mechanism of I+B cytotoxicity. The emerging role of kinase inhibitors in combination with chemotherapeutic agent provides a new modality of treatment for CLL patients.

Citation Format: Prexy Shah, Kumudha Balakrishnan, William Wierda, Varsha Gandhi. Mechanism-based combination therapy of PI3 kinase delta-specific inhibitor Idelalisib with Bendamustine in chronic lymphocytic leukemia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4530. doi:10.1158/1538-7445.AM2014-4530

Abstract 313: Essential role of ataxia telangiectasia in mitochondrial autophagy in mantle cell lymphoma

Ataxia telangiectasia mutated (ATM) is obligatory to initiate cellular responses to DNA double-strand breaks and DNA repair to preserve genomic integrity while loss of ATM leads to increased intracellular reactive oxygen species (ROS), accumulation of aberrant mitochondria, leading to abnormal mitochondrial homeostasis thereby exasperate cancer progression. ATM is frequently altered in several human cancers including 20-50% in mantle cell lymphoma (MCL). Despite ATM is known to induce global autophagy in certain cancer cells, the role of ATM in mitochondrial autophagy (mitophagy) in human cancer is imprecise. Here, we characterize a panel of MCL cell lines for their ability to trigger mitophagy induced by the mitochondrial uncoupler CCCP/FCCP. While Granta-519 lacks a functional ATM, both Jeko-1 and Mino cells exemplify as ATM proficient. Treatment with CCCP/FCCP (75µM for 4hr) elicits rapid up-regulation in ATM ser1981 phosphorylation in both Jeko-1 and Mino cells, while Granta-519 cells are mostly non-responsive. Cells were stained with TMRE (to detect mitochondrial membrane potential) or Mitotracker deep Red (to measure total mitochondrial mass) and analyzed by flow cytometry. Cells were also stained to detect both global and mitochondrial ROS (mROS) levels. CCCP/FCCP treatment resulted in rapid loss of (depolarized) membrane potential, total mitochondria mass, mROS and global ROS in both Jeko-1 and Mino cells while Granta-519 cells maintained intermediate to higher membrane potential with relatively higher total or mROS levels compared to controls. Cell fractionation analysis revealed that a fraction of resident ATM protein is located inside the mitochondrial fraction and phosphorylated upon CCCP/FCCP treatment in both Jeko-1 and Mino cells but not in Granta-519 leading to elimination of depolarized mitochondria as revealed by their basal COX4 protein levels. Immuno-precipitation analysis revealed that CCCP/FCCP treatment in both Jeko-1 and Mino cells resulted in ATM cleavage more specifically in the mitochondrial fraction. Interestingly, ATM status is unrelated to global autophagy as judged by their respective LC3I/II processing in these cell lines. Stable lentiviral knockdown of ATM in both Jeko-1 and Mino cells resulted in defective mitophagy with relatively higher COX4 expression and mROS levels. Neocarzinostatin induced DNA damage revealed loss of ATMser1981, Kap1ser824 and p53ser15 phosphorylation compared with control shRNA reconfirmed the loss of ATM function in these cells. Human primary MCL subjects with known ATM translocation [t(11;14) n=4] retain relatively higher mitochondrial mass and mROS, and are resistant to CCCP/FCCP induced mitophagy compared with ATM proficient primary MCL cells. These data underscore the possibility that ATM plays a decisive role in modulating mitophagy and contributes to the cancer-prone phenotype observed in MCL.

Citation Format: Aloke Kumar Sarkar, Kumudha Balakrishnan, Mary Ayres, Sattva S. Neelapu, Varsha Gandhi. Essential role of ataxia telangiectasia in mitochondrial autophagy in mantle cell lymphoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 313. doi:10.1158/1538-7445.AM2014-313

Abstract 4769: Ex-vivo and in-vitro combination strategies with ibrutinib in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) depends on the B-cell receptor (BCR) pathway. Bruton's tyrosine kinase (BTK) is an essential enzyme in BCR and is inhibited by ibrutinib. Though ibrutinib treatment resulted in impressive response rates, most patients only achieve partial remissions. In addition, treatment with ibrutinib elicits lymphocytosis (redistribution of tissue-resident CLL cells from lymph nodes into peripheral blood). We hypothesize that drugs that induce apoptosis in the mobilized CLL cells will provide combination strategy for future clinical trials. We obtained cells from blood of lymphocytosed CLL patients on ibrutinib trial and incubated ex-vivo for 24 h with different drugs currently in clinical trials including BH3 mimetics (ABT-199, ABT-737), PI3K inhibitors (GS-1101, IPI-145), alkylating agent (bendamustine), and BTK inhibitor (ibrutinib). Among these drugs, ABT-199 at 5 and 10 nM, elicited the highest cytotoxicity (35-80% range, median 53%; n = 12). ABT-737 at 5 and 10 nM resulted in a cytotoxic range of 10-67% with a median of 28% in the same 12 samples. ABT-199 and ABT-737-mediated ex-vivo cytotoxicity was compared in 5 patient samples pre- and post- (4 and 12 weeks after starting therapy) ibrutinib. Endogenous cell death prior to ibrutinib was a median 35% (range 5-57%), however after ibrutinib regimen endogenous apoptosis of lymphocytosed cells at week 4 was a median 13% (range 10-48%) and at week 12 was a median 12% (range 4-48%). This suggests that post-ibrutinib lymphocytosed CLL cells exhibit resistance compared to cells prior to ibrutinib therapy. Again, ABT-737 and specially ABT-199 showed maximum cell death; ABT-737 treatment induced a median 32% (range 13-57%) cell death in pre-ibrutinib sample and a median 29% (range 22-68%) in post-ibrutinib samples. ABT-199 treatment on the other hand resulted in 53% cell death in pre and post-ibrutinib samples with a range of 29-63% and 30-71%, respectively. This suggests that pre- and post-ibrutinib treated lymphocytes are similarly sensitive to ABT-mediated cytotoxicity. In-vitro drug combination studies in CLL samples (n = 11) suggested additive or synergistic combination of ibrutinib and ABT-199 or ABT-737 (0.5 and 1 nM) in CLL cells with or without BCR pathway stimulation by IgM. Similar to ex-vivo studies, ABT-199 was more effective than ABT-737. Immunoblots analyzing targets in the BTK signaling pathway and Bcl-2 protein family were performed in the pre- and post-ibrutinib samples after 24 h incubation with the 6 drugs. Preliminary immunoblots analysis suggests a decrease of antiapoptotic Mcl-1 and phospho-Akt Ser473 by weeks 4 and 12 after ibrutinib treatment compared to pre-ibruitinib samples. In contrast, Bcl-2, Bcl-XL, Bim, and total ERK1/2 levels remain stable in pre- and post-samples. Collectively, these data suggest that ABT-199 may be combined with ibrutinib to remove lymphocytosis and for better responses.

Citation Format: Fabiola Cervantes-Gomez, Kumudha Balakrishnan, William G. Wierda, Michael J. Keating, Varsha Gandhi. Ex-vivo and in-vitro combination strategies with ibrutinib in chronic lymphocytic leukemia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4769. doi:10.1158/1538-7445.AM2014-4769

Reactive oxygen species (ROS) inducible DNA cross-linking agents and their effect on cancer cells and normal lymphocytes

Reducing host toxicity is one of the main challenges of cancer chemotherapy. Many tumor cells contain high levels of ROS that make them distinctively different from normal cells. We report a series of ROS-activated aromatic nitrogen mustards that selectively kill chronic lymphocytic leukemia (CLL) over normal lymphocytes. These agents showed powerful DNA cross-linking abilities when coupled with H2O2, one of the most common ROS in cancer cells, whereas little DNA cross-linking was detected without H2O2. Consistent with chemistry observation, in vitro cytotoxicity assay demonstrated that these agents induced 40-80% apoptosis in primary leukemic lymphocytes isolated from CLL patients but less than 25% cell death to normal lymphocytes from healthy donors. The IC50 for the most potent compound (2) was ~5 μM in CLL cells, while the IC50 was not achieved in normal lymphocytes. Collectively, these data provide utility and selectivity of these agents that will inspire further and effective applications.

Targeting MET kinase with the small-molecule inhibitor amuvatinib induces cytotoxicity in primary myeloma cells and cell lines

BACKGROUND

MET is a receptor tyrosine kinase that is activated by the ligand HGF and this pathway promotes cell survival, migration, and motility. In accordance with its oncogenic role, MET is constitutively active, mutated, or over-expressed in many cancers. Corollary to its impact, inhibition of MET kinase activity causes reduction of the downstream signaling and demise of cells. In myeloma, a B-cell plasma malignancy, MET is neither mutated nor over-expressed, however, HGF is increased in plasma or serum obtained from myeloma patients and this was associated with poor prognosis. The small-molecule, amuvatinib, inhibits MET receptor tyrosine kinase. Based on this background, we hypothesized that targeting the HGF/MET signaling pathway is a rational approach to myeloma therapy and that myeloma cells would be sensitive to amuvatinib.

METHODS

Expression of MET and HGF mRNAs in normal versus malignant plasma cells was compared during disease progression. Cell death and growth as well as MET signaling pathway were assessed in amuvatinib treated primary myeloma cells and cell lines.

RESULTS

There was a progressive increase in the transcript levels of HGF (but not MET) from normal plasma cells to refractory malignant plasma cells. Amuvatinib readily inhibited MET phosphorylation in primary CD138+ cells from myeloma patients and in concordance, increased cell death. A 48-hr amuvatinib treatment in high HGF-expressing myeloma cell line, U266, resulted in growth inhibition. Levels of cytotoxicity were time-dependent; at 24, 48, and 72 h, amuvatinib (25 μM) resulted in 28%, 40%, and 55% cell death. Consistent with these data, there was an amuvatinib-mediated decrease in MET phosphorylation in the cell line. Amuvatinib at concentrations of 5, 10, or 25 μM readily inhibited HGF-dependent MET, AKT, ERK and GSK-3-beta phosphorylation. MET-mediated effects were not observed in myeloma cell line that has low MET and/or HGF expression.

CONCLUSIONS

These data suggest that at the cellular level MET/HGF pathway inclines with myeloma disease progression. Amuvatinib, a small molecule MET kinase inhibitor, is effective in inducing growth inhibition and cell death in myeloma cell lines as well as primary malignant plasma cells. These cytostatic and cytotoxic effects were associated with an impact on MET/HGF pathway.