Alsayed, Yazan

Abstract Prior studies have demonstrated that MM cells with PTEN mutation and high AKT activity are more sensitive to inhibitors of the PI3K/Akt/mTOR pathway. However, the molecular mechanisms that regulate the differential response to these agents are not well characterized. The objective of this study was to determine proteins that are different between MM cell lines with higher AKT activity (OPM2) and lower AKT activity (MM.1S) in response to the AKT inhibitor, perifosine. Methods: MM cell lines (MM.1S and OPM2) were treated with serial concentration of perifosine (KRX-0401, Keryx, NY, NY, provided by the NCI). Proteomic analysis using the nanoscale BD Clontech antibody-based protein microarray technique was performed using cells treated with perifosine (10uM for 16 hrs) or vehicle (sterile water) as control. Apoptosis was determined using Annexin V/PI FACS analysis at 24 and 48 hrs. The treatment time and concentration were chosen so that it did not induce more than 25% apoptosis to ensure adequate analysis of changes in signaling pathways. The antibody microarray is a technique that detects differences in protein abundance between the treated and control sample with each experiment by hybridizing fluorescently labeled (Cy3 and Cy5) protein mixtures onto slides spotted with 512 human monoclonal antibodies. Two microarray slides were used for each experiment. The slides were scanned using the Axon GenePix 4000B scanner. Two ratios were generated from the spot images for each protein target. The mean of the ratios of Cy5/Cy3 of both slides were analyzed using Clontech software and used to calculate an Internally Normalized Ratio (INR = (Ratio1/Ratio2, ratios 1 and 2 correspond to slides 1 and 2) for each spot on the array. The INR values were input into GeneSpring 6.0 software (Silicon Genetics, CA). The data was normalized to the mean INR of the two cell lines. Proteins whose expression level changed relative to control greater than 1.3 fold were determined. Unsupervised clustering demonstrated a different protein signature between MM.1S and OPM2 in response to perifosine. There were 144 proteins differentially expressed by 1.3 fold between MM.1S and OPM2. Proteins that were downregulated in OPM2 as compared to MM.1S included those in the PI3K pathway and cell cycle regulation such as PTEN, p70S6Kinase, the AKT substrate GSK-3, eEF-2 kinase, eIF-4g, Ku-80, cyclin A, E2F-2, CDK2, CDK7, and c-myc; proteins involved in apoptosis such as p21WAF, caspase 4 and 8, FADD, and PARP; kinases such as PKAc, PKA RI, ERK2, and JNK1; and other proteins regulating apoptosis and proliferation including p53, the NF-kB inhibitor IkB, and the heat shock protein HSP70. The nanoscale protein array is a useful and rapid technique that may be used to identify differences between resistant and sensitive cells to novel therapeutic agents. We identified proteins that are differentially expressed between MM cells sensitive and relatively resistant to the AKT inhibitor perifosine. Further analysis of the role of these proteins in the mechanism of resistance/sensitivity to perifosine is being performed. Future use of inhibitors of NF-kB (bortezomib) or heat shock protein inhibitors in conjunction with perifosine may overcome resistance induced by these proteins in MM cells with low AKT activity. Supported in part by an ASH scholar award and an MMRF grant.

Abstract The objective of this study was to determine the molecular alterations that occur at the protein level in patients with PTLD in order to identify novel targets of therapy, determine new markers of prognosis, and begin to delineate the pathogenesis of PTLD. Six tumor samples were obtained after informed consent from adult patients with PTLD post solid organ transplant. Four benign lymph nodes were obtained from age-matched controls. Three of the samples and their two controls were obtained from frozen tissue and the other three with two matching controls were obtained form paraffin embedded tissue. Immunohistochemistry using anti-CD19+ antibodies was performed and laser microdissection or slide scraping was used to obtain the tissue. Deparaffinization was performed using xylene and ethanol serial dilutions. Protein quantification was performed and 1ug of protein was obtained for each sample and its control. The nanoscale protein micorarray technique (BD Clontech, CA) was used to measure changes in the patterns of protein expression between PTLD samples and control lymphocytes. This is a new technique that detects differences in protein abundance between the disease and control samples by hybridizing fluorescently labeled (Cy3 and Cy5) protein mixtures onto slides spotted with 512 human monoclonal antibodies. It requires minute amounts of proteins. Two microarray slides were used for each experiment and a control experiment of control versus control was performed for normalization of the data. The slides were scanned using the Axon GenePix 4000B scanner. Two ratios were generated from the spot images for each protein target. The mean of the ratios of Cy5/Cy3 of both slides were analyzed using Clontech software and used to calculate an Internally Normalized Ratio (INR = Ratio1/Ratio2) for each spot on the array. The INR values were input into GeneSpring 6.0 software (Silicon Genetics, Redwood City CA). The data were normalized to the mean INR of the control samples. Proteins whose expression fold change relative to control was greater than 1.3 fold were determined. All cases represented monomorphic PTLD. Five were confirmed EBV positive (EBNA positive). The tissues were obtained from multiple organs including liver, gastric, cerebral, renal and lymph nodes. There were 22 proteins upregulated in the frozen sections as compared to the control and 157 proteins upregulated by 1.3 fold in the paraffin embedded sections as compared to control. Most of these proteins were common between the paraffin embedded and frozen sections. Proteins that were dysregulated included: proteins in the PI3K pathway and cell cycle regulation such as p70S6K, VHR, the AKT substrate GSK-3, cyclin C, MCM6, eIF-4E, CDK1, CDK7, eE-F-2 kinase; kinases such as JNKK1, PKC-lambda, RhoA kinase ROKalpha, ERK1, PKAc, PKArIIa and PKCbeta; apoptosis related proteins such as caspase 8, NF-kB, and MDM2; TGF signaling protein p300, and the heat shock protein HSP90. These results provide insight into pathways that are dysregulated in PTLD and can be targeted in future clinical trials with specific inhibitors such as PI3K, PKC, NF-kB or HSP90 inhibitors.

Abstract The bone marrow microenvironment in MM is characterized by the presence of upregulated osteoclast activity (OCL) and increased angiogenesis. We have recently demonstrated that the HSP90 inhibitor 17-AAG (provided by the NCI) and the mTOR inhibitor rapamycin (LC Laboratories, MA) have synergistic inhibitory activity on MM cells. The objective of this study was to determine the effect of rapamycin, 17-AAG and the combination on OCL formation and angiogenesis. Rapamycin (0.01–100nM), 17-AAG (10–1000nM) and the combination was tested using an in vitro human OCL formation assay and a human angiogenesis assay (AngioKit, TCS Cellworks, UK). Nonadherent human marrow mononuclear cells (1 x 105/100 μL) were plated in 96-well plates in the presence or absence of DMSO, rapamycin, 17-AAG or the combination. RANKL (100ng/ml) and MCSF (20ng/ml) were added to all wells except control media and MCSF. After 3 weeks, cells were fixed, and the number of OCL-like multinucleated cells were scored. To test the effect of the agents on early OCL precursors, we added the inhibitory agents on days 1, 7 or 14 of the culture. The AngioKit is comprised of human endothelial cells in a 24 well plate. The endothelial cells proliferate and then migrate through the matrix to form tubular structures and anastomosing tubules by 2 weeks. Two control wells were treated with VEGF (+ve control) and two with suramin (−ve control). The optimized medium and test samples were replaced on days 4, 7, and 9 after initial treatment. On day 11, cultures were fixed and stained with antibodies to CD31 to detect vessel formation. The degree of tubule formation was quantitated using computerized image analysis (Angiosys, TCS Cellworks, UK). Single agent rapamycin (20–100nM) inhibited OCL formation by 35% as compared to control in all tested doses indicating that PI3K/mTOR is an important regulator of OCL formation. The effect was similar on day 7 and day 14 indicating that this pathway is important for early and late OCL formation. 17-AAG 100–600nM significantly inhibited OCL formation with 100nM 17-AAG inducing 12% OCL formation as compared to control, while 300 and 600nM completely abrogated OCLs (0% OCLs). This effect was similar at day 7. However, when 17-AAG was added on day 14, it only induced 50–60% reduction in OCL formation indicating that 17-AAG affects early OCL formation. The combination of the two agents completely inhibited OCL formation on day 1 and 7 and led to a 65% reduction in OCLs when added on day 14 of the culture. Rapamycin showed a marked decrease in angiogenesis (similar to the negative control suramin), even at the lowest level tested of 0.01nM. 17-AAG demonstrated some inhibition of angiogenesis at 10 nM, and completely abrogated angiogenesis at 500–1000nM. In summary, rapamycin and 17-AAG inhibit OCL formation and angiogenesis. The effect of 17-AAG was on early OCL formation while rapamycin was on both early and late OCL. These results are contradictory to previous data indicating that 17-AAG increases OCL activity in MM. Rapamycin had a significant inhibitory effect on angiogenesis even at low doses. These results demonstrate that the use of rapamycin analogues and 17-AAG in clinical trials may have a therapeutic effect, not only on MM cells, but also on the bone marrow microenvironment. Supported in part by an ASH Scholar Award and an MMRF grant.

Abstract We have previously demonstrated that the chemokine receptor CXCR4 and its ligand SDF-1 are important regulators of migration in MM. The objective of this study was to investigate the role of the CXCR4 inhibitor AMD3100 (Sigma, MO) on proliferation, survival, migration, adhesion and invasion in MM. MM cell lines (MM.1S, OPM2 and Kas6/1) were exposed to serial dilutions of SDF-1 (1–100nM) in the presence or absence of the CXCR4 inhibitor AMD3100 (20–100uM) incubated for 16 hrs or the CXCR4 inhibitory antibody MAB171 (RDSystems, MN) 10–800uM or its IgG2 isotype control. Inhibition of proliferation was measured using the MTT proliferation assay. Apoptosis was determined using Annexin V/PI FACS analysis. Migration was determined using a transwell migration assay (Costar, Corning, NY). Cells treated with serial concentrations of AMD3100 or vehicle (sterile water) were washed, placed in serum free medium for two hours, then placed in the migration chambers with 1% FCS medium in the presence of SDF–1 20nM (a concentration previously determined to induce maximum migration in MM cells). After 4 hours of incubation, cells that migrated to the lower chambers were counted. Similarly, adhesion was determined using an adhesion assay (EMD Biosciences, CA) with 96 well plated coated with fibronectin and using MM cells treated with serial dilutions of AMD3100 or vehicle in the presence or absence of serial concentrations of SDF-1 (10–30nM). Invasion was determined using the invasion assay (EMD Biosciences, CA). Serial concentrations of SDF-1 induced a bell-shaped migration curve in MM cells with 10–30nM inducing maximum migration (324% compared to untreated control) while higher doses of SDF-1 (100nM) did not induce migration in all MM cells tested. AMD3100 induced a dose dependent inhibition of migration in MM cells treated with 20nM SDF-1. The maximum effect was demonstrated at 25uM with 48% migration as compared to control. Higher doses of AMD3100 (50–100uM) did not further inhibit migration. The anti-CXCR4 antibody demonstrated a dose dependent inhibition of migration. Anti-CXCR4 10uM inhibited migration to 53% and 200uM to 35%. The effects of higher doses of anti-CXCR4 were not significantly different as compared to 200uM. Serial concentrations of SDF-1 (10–100) induced a dose-response increase in adhesion to fribronectin with 10nM increasing adhesion by 202% as compared to untreated cells and 100nM 462% indicating activation of alpha4 beta1 integrin on MM cells. AMD3100 100uM inhibited adhesion at all doses by 55% as compared to control. Using the invasion assay, SDF-1 100nM induced maximal invasion of MM cells. The effect of SDF-1 on invasion was not abrogated by AMD3100. AMD3100 did not induce significant apoptosis or inhibition of proliferation at all tested doses, in the presence or absence of 20–100nM SDF-1. In summary, AMD3100 inhibited migration and adhesion of MM cells, but not invasion indicating that invasion occurs through non-CXCR4 dependent mechanisms. AMD3100 did not induce apoptosis or inhibition of proliferation indicating that its effect is specific on migration and adhesion. Further experiments to test its role on homing of MM cells in vivo are underway. The future use of this novel agent as an inhibitor of homing of MM cells in clinical trials may be warranted. Supported in part by an ASH Scholar Award and an MMRF grant.

Abstract The objective of this study was to determine the molecular alterations that occur at the protein level in patients with WM in order to identify novel targets of therapy, determine new markers of prognosis, and begin to delineate the pathogenesis of WM. Five bone marrow samples were obtained after informed consent from patients with symptomatic WM. Two bone marrow samples were obtained from age-matched controls and were pooled. All samples were purified with anti-CD19+ beads with over 90% purity. Protein quantification was performed and 1ug of protein was obtained for each sample and control. The nanoscale protein micorarray technique (BD Clontech, CA) was used to measure changes in the patterns of protein expression between WM samples and control lymphocytes. This is a new technique that detects differences in protein abundance between the tumor and control samples by hybridizing fluorescently labeled (Cy3 and Cy5) protein mixtures onto slides spotted with 512 monoclonal antibodies against human polypeptides. It requires minimal amount of protein. Two microarray slides were used for each experiment and a control experiment of control versus control was performed for normalization of the data. The slides were scanned using the Axon GenePix 4000B scanner. Two ratios were generated from the spot images for each protein target. The mean of the ratios of Cy5/Cy3 of both slides were analyzed using Clontech software and used to calculate an Internally Normalized Ratio (INR = ÷Ratio1/Ratio2, ratios 1 and 2 correspond to slides 1 and 2) for each spot on the array. The INR values were input into GeneSpring 6.0 software (Silicon Genetics, Redwood City CA). The data was normalized to the mean INR of the control samples. Proteins whose expression fold change relative to control was greater than 1.3 fold were determined. All samples were of symptomatic WM. There were 3 females and 2 males. The median age was 61 years (range, 47–83). Four patients were newly diagnosed and one had received prior rituximab, CHOP ad thalidomide therapy. Clustering analysis did not demonstrate a difference between newly diagnosed and treated samples. There were 72 proteins up or downregulated by 1.3 fold in all WM samples as compared to control. These included proteins in the PI3K pathway such as VHR, PTP1B, PI3K (p110alpha) and Rb2. Protein kinases such as PKCi, PKCbeta, PKC gamma, PKC delta, PLCgamma were all upregulated in WM samples. Other proteins included the B-cell specific activator protein PAX-5, the ubiquitin protein UBCH6, the STAT kinase STAT4, the GTPase Rho A-binding kinase ROK alpha, and the apoptosis protein SMAC/DIABLO. We demonstrate that several isoforms of the PKC family of proteins are upregulated in WM. PKC proteins regulate apoptosis, proliferation and migration in many cancer cells. These proteins may be useful targets of therapy in future clinical trials in WM. Other inhibitors that may be useful in WM include ubiqutin/proteosome inhibitors such as bortezomib and PI3K pathway inhibitors such AKT or mTOR inhibitors. Our results also confirm the presence of PAX-5 in WM consistent with previous cytogenetic studies. Supported in part by an ASH scholar award and Research Fund for Waldenstrom.

Abstract Waldenstrom Macroglobulinemia (WM) is characterized by the presence of lymphoplasmacytic cells in the bone marrow, and often in the lymph nodes. The mechanisms by which cells migrate/home to the bone marrow are poorly understood. The chemokine receptor CXCR4 and its ligand SDF-1 have been implicated in the migration and homing of lymphocytes. The objective of this study was to begin to identify the role of CXCR4 in WM. Paraffin embedded tissues were obtained after informed consent from 10 bone marrow samples of asymptomatic WM/monoclonal gammopathy of undetermined significance (MGUS) (n=5) and symptomatic WM (n=5). Four normal bone marrow samples were obtained for control. CXCR4 expression was determined using anti-CXCR4 antibody (Affinity Bioreagents, Golden, CO) 1:200 dilution for 16hrs, and a scale of 0–3+ was used to determine relative expression in the lymphocytes. Anti-CD20 antibody was used to determine the presence of lymphocytes in the samples. To determine whether the receptor is functional, migration was performed with the WM cell line (WSU-WM, kind gift from Dr. Al-Khatib, Wayne State University) and using a transwell migration assay (Costar, Corning, NY) with serial dilutions of SDF-1 (10-100nM). Comparison between the asymptomatic and symptomatic WM groups was performed by c2 test, and Mann-Whitney test, as appropriate. The baseline patient characteristics are displayed in table 1. CXCR4 expression was present on the surface of scattered lymphocytes in the normal bone marrow (median expression 1+). The expression of CXCR4 was increased in the asymptomatic/MGUS cases of WM (median expression 2+). In contrast, CXCR4 expression was downregulated in 4/5 cases of symptomatic WM specifically all the ones with extensive involvement of the bone marrow with lymphoplasmacytic cells (median expression 0). SDF-1 induced a bell- shaped response of migration in the WM cells with the maximal migration occurring at 1-10nM SDF-1. SDF-1 1-10nM induced 340% increase in migration as compared to untreated cells. However, high doses of SDF-1 100nM did not induce any migration as compared to untreated cells indicating inhibition of migration in response to high doses of SDF-1. In summary, we demonstrate that the CXCR4 receptor is functional and induces migration indicating that it plays a role in the migration of WM cells to the bone marrow. In addition, we demonstrate that CXCR4 expression is downregulated in WM with high infiltration of cells in the bone marrow as compared to those with minimal infiltration. These results may be due to the high level of SDF-1 in the bone marrow that induce downregulation of CXCR4. High levels of SDF-1 may downregulate the receptor and inhibit migration in order to confine the cells within the bone marrow. Supported in part by an ASH scholar award and the RFW. Patient characteristics Asymptomatic WM/MGUS, (range), (N=5) Symptomatic WM, (range) (N=5) Median age at diagnosis 67.6 (55.8–78) 71.5 (61–77) Median IgM level (mg/dL) 997 (904–1490) 5410 (2000–7820) Median Hb (gm/dL) 12.6 (11.1–15.1) 10.8 (9.3–11.6) Organomegaly (liver or spleen) N 20% Lymphadenopathy N 40% Median involvement of tumor cells in the BM in % 5% 30(10–60)

Abstract To better understand the molecular changes that occur in Waldenstrom macroglobulinemia (WM), we employed antibody-based protein microarrays to compare patterns of protein expression between untreated WM and normal bone marrow controls. Protein expression was defined as a >2-fold or 1.3-fold change in at least 67% of the tumor samples. Proteins up-regulated by >2-fold included Ras family proteins, such as Rab-4 and p62DOK, and Rho family proteins, such as CDC42GAP and ROKα. Other proteins up-regulated by >1.3-fold included cyclin-dependent kinases, apoptosis regulators, and histone deacetylases (HDAC). We then compared the samples of patients with symptomatic and asymptomatic WM and showed similar protein expression signatures, indicating that the dysregulation of signaling pathways occurs early in the disease course. Three proteins were different by >2-fold in symptomatic versus asymptomatic, including the heat shock protein HSP90. Elevated protein expression was confirmed by immunohistochemistry and immunoblotting. Functional significance was validated by the induction of apoptosis and inhibition of proliferation using specific HDAC and HSP90 inhibitors. This study, therefore, identifies, for the first time, multiple novel proteins that are dysregulated in WM, which both enhance our understanding of disease pathogenesis and represent targets of novel therapeutics. [Cancer Res 2007;67(8):3777–8]

AbstractWaldenström macroglobulinemia (WM) is an incurable lymphoplasmacytic lymphoma with limited options of therapy. Protein kinase Cβ (PKCβ) regulates cell survival and growth in many B-cell malignancies. In this study, we demonstrate up-regulation of PKCβ protein in WM using protein array techniques and immunohistochemistry. Enzastaurin, a PKCβ inhibitor, blocked PKCβ activity and induced a significant decrease of proliferation at 48 hours in WM cell lines (IC50, 2.5-10 μM). Similar effects were demonstrated in primary CD19+ WM cells, without cytotoxicity on peripheral blood mononuclear cells. In addition, enzastaurin overcame tumor cell growth induced by coculture of WM cells with bone marrow stromal cells. Enzastaurin induced dose-dependent apoptosis at 48 hours mediated via induction of caspase-3, caspase-8, caspase-9, and PARP cleavage. Enzastaurin inhibited Akt phosphorylation and Akt kinase activity, as well as downstream p-MARCKS and ribosomal p-S6. Furthermore, enzastaurin demonstrated additive cytotoxicity in combination with bortezomib, and synergistic cytotoxicity in combination with fludarabine. Finally, in an in vivo xenograft model of human WM, significant inhibition of tumor growth was observed in the enzastaurin-treated mice (P = .028). Our studies therefore show that enzastaurin has significant antitumor activity in WM both in vitro and in vivo, providing the framework for clinical trials to improve patient outcome in WM.

Abstract Purpose: The phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (mTOR) pathway and the heat shock protein family are up-regulated in multiple myeloma and are both regulators of the cyclin D/retinoblastoma pathway, a critical pathway in multiple myeloma. Inhibitors of mTOR and HSP90 protein have showed in vitro and in vivo single-agent activity in multiple myeloma. Our objective was to determine the effects of the mTOR inhibitor rapamycin and the HSP90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) on multiple myeloma cells. Experimental Design: Multiple myeloma cell lines were incubated with rapamycin (0.1-100 nmol/L) and 17-AAG (100-600 nmol/L) alone and in combination. Results: In this study, we showed that the combination of rapamycin and 17-AAG synergistically inhibited proliferation, induced apoptosis and cell cycle arrest, induced cleavage of poly(ADP-ribose) polymerase and caspase-8/caspase-9, and dysregulated signaling in the phosphatidylinositol 3-kinase/AKT/mTOR and cyclin D1/retinoblastoma pathways. In addition, we showed that both 17-AAG and rapamycin inhibited angiogenesis and osteoclast formation, indicating that these agents target not only multiple myeloma cells but also the bone marrow microenvironment. Conclusions: These studies provide the basis for potential clinical evaluation of this combination for multiple myeloma patients.

Abstract The mechanisms by which multiple myeloma (MM) cells migrate and home to the bone marrow are not well understood. In this study, we sought to determine the effect of the chemokine SDF-1 (CXCL12) and its receptor CXCR4 on the migration and homing of MM cells. We demonstrated that CXCR4 is differentially expressed at high levels in the peripheral blood and is down-regulated in the bone marrow in response to high levels of SDF-1. SDF-1 induced motility, internalization, and cytoskeletal rearrangement in MM cells evidenced by confocal microscopy. The specific CXCR4 inhibitor AMD3100 and the anti-CXCR4 antibody MAB171 inhibited the migration of MM cells in vitro. CXCR4 knockdown experiments demonstrated that SDF-1–dependent migration was regulated by the PI3K and ERK/MAPK pathways but not by p38 MAPK. In addition, we demonstrated that AMD3100 inhibited the homing of MM cells to the bone marrow niches using in vivo flow cytometry, in vivo confocal microscopy, and whole body bioluminescence imaging. This study, therefore, demonstrates that SDF-1/CXCR4 is a critical regulator of MM homing and that it provides the framework for inhibitors of this pathway to be used in future clinical trials to abrogate MM trafficking.