CLINICAL IMPLICATIONS OF TNF FAMILY IN BLOOD DISORDERS DHEERAJ MOHANIA.

CLINICAL IMPLICATIONS OF TNF FAMILY IN BLOOD DISORDERS

DHEERAJ MOHANIA

HISTORY• Tumor necrosis factor (TNF),

originally identified as a factor produced in the serum of endotoxin-injected animals, is a cytokine that mediates tumor necrosis.

• To date, 20 different members of the TNF superfamily and 21 different receptors have been identified.

• All ligands of the TNF superfamily have been found to activate transcription factor NF-ĸB and c-Jun kinase.

• Members of this family have diverse biologic effects, including induction of apoptosis, promotion of cell survival, and regulation of the immune system.

• The CD30,CD40,RANK and TRAIL are the four members that play important roles in regulating hematopoietic cells and are involved in the pathogenesis of several hematologic malignancies.

TNF α •Also called cachectin•Produced by macrophages and Mast cells

•TNF alpha is a pleiotropic inflammatory cytokine

•Target tissue: tumour cells and Inflammatory cells•Has cytotoxic effects•Induce cytokine secretion•Responsible for extensive weight loss (cachexia) associated with chronic inflammation.

TNF β•Also called lymphotoxin•produced by TH1 and Tc cells

•Target tissue: tumour cells and macrophage and neutrophils

•Has cytotoxic activity and other effects similar to TNF α

• Enhances the phagocytic activity.

Structural changes of cells undergoing necrosis or apoptosis.

Self-digestionActive substances released

DEATH signals

TNF-alpha CD95 ligand / Fas ligand

Death receptors, e.g. CD95

Death domains

Binding to the receptor induces receptors to cluster and trimerize

After binding to ligand, receptors form trimers

Death domains

FADD (Fas associated death domain protein)

is recruited via its death domain

DED (death effector domain) of FADD recruits pro-caspase 8 via its DED

FADD-CASP8 complex brings multiple pro-caspase 8 molecules in close proximity

(‘induced proximity’ aggregation results in their cross-activation). 

This is the DISC -complex.

DISC complex

Activated caspase-8 (a heterotetramer) is released from DISC into the cytoplasm

caspase-8 cleaves pro-apoptotic BID protein.

BID interacts with the pro-apoptotic

BCL2 relatives BAX and BAK

This amplifies apoptosis induction

through the cell-extrinsic pathway

Nature Reviews Cancer 2; 420-430 (2002); TARGETING DEATH AND DECOY RECEPTORS OF THE TUMOUR-NECROSIS FACTOR SUPERFAMILY

TNF-alpha can signal to NF-kB transcription factors.

NF-kB factors are anti-apoptotic(mostly)

Activate pro-survival Bcl-Xl,IAPs Activate pro-apoptotic

FAS, FAS LigandP53

Tissue specific decision

inflammatory cytokines, chemokines,

immunoreceptors, and cell adhesion molecules

One of the `central mediators

of the immune response'.

1. The combinatorial response of promoter/enhancer regions, and2. The selective activation and binding of individual NF-kB proteins

TNF-alpha can signal to NF-kappaB transcription factors.

Binding of TNF-alpha to TNFR

TRADD recruited

IKK kinase recruited

IKK phosphorylate IkB

IkB degraded

P50/p65(NF-kappaB)Free to transactivate

NF-kappaB pathway

In the cytoplasm, NF-kB is inhibited by IkB (inhibiitor of NF-kappa B)

Upstream activating signal (e.g., binding of TNF to its receptor) may cause phosphorylation of IkB

by IKK (IkB kinase).

TNF-alpha can signal to NF-kappaB transcription factors.

IKB -- is one of the NF-kB target genes :

provide the regulatory loop

NF-kappa B is an anti-apoptotic factor

Via NF-kappaB TNF blocks its own cell death potential

chemotherapy activates NF-kB within tumor cells

NF-kB inhibitors augment chemotherapy

many common synthetic (e.g., aspirin), and traditional (e.g., green tea, curcumin)

remedies target, at least in part, the NF-kB signaling pathway

Tumor Necrosis Factor superfamily.

• Type II transmembrane proteins (N-terminal inside the cell, C-terminal outside the cell) that share sequence homology in the extracellular domain.

• The biologically active forms of these protein ligands are self-assembled protein trimers.

• These trimers do not share any sequence homology at the receptor binding site, but they do share 25–30% sequence homology at trimerization sites.

• Many of the TNFSF members are cleaved in a biologically active soluble form. Although the majority of these ligands bind to one specific receptor, few bind to more than one receptor.

TNF RECEPTOR FAMILY

Tumor Necrosis Factor Receptor superfamily

• TNFRSF is a group of type I proteins that share sequence homology in their extracellular domains,

• Characterized by 40–amino acid cysteine-rich repeats.• The intracellular domains of these receptors are short and do not share any

sequence homology, indicating their diverse functions.• The cytoplasmic tails of these receptors signal by interacting with two major

groups of intracellular proteins: TNF receptor–associated factors (TRAFs) and Death domain (DD)-containing proteins.

• There are at least six human TRAFs that can interact with TRAF-binding sites on the cytoplasmic tail of some of these receptors to initiate several signaling pathways, including mitogen- activated protein (MAP) kinases, AKT, and NF-B.

• TNF-family receptors that have a DD sequence in their cytoplasmic tail are called death receptors. The DDs in these receptors interact with the DDs in adaptor proteins, such as Fas-associated DD (FADD) and TNF receptor–associated DD (TRADD).The adaptor proteins also contain a death effector domain (DED) that can interact with the DED in procaspase-8, leading to a cascade of apoptotic signals.

Interacting Proteins of the TNF/TNFR Superfamily

HSC

B

B B

B

B

B

B

B

apoptosis

apoptosis

Apoptosis failure leads to disease

Especially true for autoimmune diseases

that result from the persistence of autoreactive T/B-cells.

BLOOD DISORDERS

LYMPHOMA

LEUKEMIA

THROMBO- CYTOPENIA

LYMPHOCYTICT OR B CELL

LINEAGECLLALL

MYELOIDGranulocyteMonocyte

ErythrocyteplateletsAML

CML

Lymphoblastic lymphoma

Hodgkin’s and non-Hodgkin’sBurkitt’s and Burkitt’s-like

lymphoma/small noncleaved B cell

lymphoma

Diffuse large cell lymphoma (B/T/nul)

Anaplastic large cell lymphoma

Cellular Origins of Lymphomas / Leukemias

PLEURIPOTENT STEM CELL

PRECURSOR T - CELL PRECURSOR B - CELL

MATURE T - CELL MATURE B - CELL

LYMPHOID STEM CELL

ACUTE LEUKEMIAS

ACUTE LYMPHOBLASTIC LEUKEMIAS

LYMPHOBLASTIC LYMPHOMAS / LEUKEMIAS

NON-HODGKIN’S LYMPHOMAS

LYMPH NODES, EXTRANODAL TISSUES S. J. Schuster, 2003

Chronic lymphocytic leukemia • Is characterised by the

accumulation of non-proliferating mature-appearing lymphocytes in the blood, marrow, lymph nodes, and spleen

• Is the most common form of leukemia in North America and Europe, but is extremely rare in the Orient

• Commonest leukemia in adults

• Typically occurs in older patients, with the highest incidence being in those aged 50 to 55 years

• Affects men twice as often as women

• Does not affect children• Approximately 25% of all leukemias

•A Group of neoplastic diseases of the leukocyte•Cancer of leukocytes or their precursors.•Accumulation or proliferation of leukocytes in the bone marrow.•May or may not have increased leukocyte count in the bone marrow.

Normal Blood

Red cell

Platelets

Neutrophil

Lymphocyte

Monocyte

Reticulocyte

lymphocytes

Lymphocytes in normal case

WBC x 109/L 150.0 [4-11]Hb g/L 98 [120-160]MCV fl 87 [79-98]Platelets x 109/L 48 [150-450]

Neuts x 109/L 1.5 [2-7.5]Lymphs x 109/L 130.0 [1.5-4]Monos x 109/L 0.5 [0.2-0.8]Eos x 109/L - [0-0.7]Basos x 109/L - [0-0.1]

Smudge cells x 109/L 28.0 [0]

Film Comment: appearances suggest CLL

Lymphocytes in case of CLL

CLL - blood count

CML - pathology• Chronic Phase

– Accumulation of myeloid cells

• bone marrow• peripheral blood• spleen and liver

• Accelerated Phase– Further genetic

changes in the stem cell leading eventually to acute transformation (ie acute leukemia)

Chronic Myeloid Leukemia

A neoplasm of hematopoietic stem cellsA neoplasm of hematopoietic stem cellsA two-phase diseaseA two-phase disease

CML - clinical features of chronic phasePeak age 20 to 40 years ,Weight loss, night sweats ,Big

spleen ,Gout ,Often found by chance

neutrophil

basophil

metamyelocyte

myelocytes

CML - blood count

WBC x 109/L 122.0 [4-11]Hb g/L 98.5 [120-160]MCV fl 87 [79-98]Platelets x 109/L 843 [150-450]

Neuts x 109/L 80.0 [2-7.5]Lymphs x 109/L 2.0 [1.5-4]Monos x 109/L 2.0 [0.2-0.8]Eos x 109/L 1.0 [0-0.7]Basos x 109/L 5.0 [0-0.1]

Blasts x 109/L 2.0 [0]Promyelocytes x 109/L 4.0 [0]Myelocytes x 109/L 20.0 [0]Metamyelocytes x 109/L 4.0 [0]

Nucleated RBC x 109/L 2.0 [0]

Film Comment: appearances suggest CML

• Lymphoma (Hodgkin’s and non-Hodgkin’s) is the third most common childhood malignancy.

• Non-Hodgkin’s lymphoma (NHL) accounts for approximately 7% of cancers in children less than 20 years of age.

• In the United States, there are about 800 new cases of NHL diagnosed each year.

• Incidence is approximately 10 per 1,000,000.

• Although there is no sharp age peak, occurs most commonly in the second decade of life, and occurs less frequently in children less than 3 years of age.

• NHL is the most frequent malignancy in children with AIDS, and it often occurs before the age of 4 years in those who have vertical transmission of the virus.

• Screening for HIV should be considered for all children with NHL.

Any Malignant tumour, or condition allied to a tumour , arising fromSome or all of the cells of lymphoid tissue.

Cellular Classification• In children, non-

Hodgkin’s lymphomas (NHLs) are distinct from the more common forms of lymphomas in adults.

• While lymphomas in adults are more commonly of low or intermediate grade, almost all that occur in children are high grade.

• NHL in children can be classified into 1 of 4 categories:– Burkitt’s and Burkitt’s-like

lymphoma/small noncleaved B cell lymphoma

– Lymphoblastic lymphoma– Diffuse large cell

lymphoma.– Anaplastic large cell

lymphoma

Category WHO

Classification/

Updated REAL

Category

(working formulation)

Immuno-phenotype

Clinical

Presentation

Chromosome

Translocation

Genes

Affected

Burkitts and

Burkitt’s-like

Lymphomas

ML small non-

cleaved cell

Mature B

cell

Intra-abdominal

(sporadic)-jaw

(endemic)-head and neck (non-jaw) (sporadic)

t(8;14)(q24q32), t(2;8)(p11;q24), t(8;22)(q24;q11)

c-myc, IgH, Igk, Ig1.

Lymphoblastic lymphoma, precursor T/ leukemia

Lymphoblastic convoluted and nonconvoluted

T cell

Pre-B-cell

Mediastinal, BM

Skin, bone

Diffuse large B-cell lymphoma

ML large cell Mature B cell cell; may be CD 30+

Nodal, abdomen, bone, primary CNS, mediastinal

Not well characterized in children

Anaplastic large cell lymphoma, systemic

ML immunoblastic ML large

CD30+(Ki-1+)

T cell or null

Variable, but systemic symptoms often prominent

t(2;5)(p23;q35) ALK, NMP

Anaplastic large cell lymphoma, cutaneous

ML large CD30+(Ki-usually)

T cell

Skin only; single or multiple lesions

Lacks t(2;5)

• Involvement of the bone marrow may lead to confusion as to whether the patient has lymphoma or leukemia.

• Traditionally, patients with greater than 25% marrow blasts are considered to have leukemia, and those with less than 25% marrow blasts are considered to have lymphoma.

• Lymphoblastic lymphomas are usually positive for the enzyme terminal deoxynucleotidyl transferase (TDT) and have a T-cell immunophenotype.

• About 10% to 15% of lymphoblastic lymphomas have non-T immunologic characteristics (for example, common acute lymphocytic leukemia antigen [CD10]-positive precursor B-cell phenotype).

• Chromosomal abnormalities are not well characterized in patients with lymphoblastic lymphoma.

• Makes up approximately 30% of childhood NHL.

• Predominantly tumors of thymocyte (T-cell) origin.

• 75% of patients with lymphoblastic lymphoma have an anterior mediastinal mass, and may present with symptoms of dyspnea, wheezing, stridor, dysphygia, or swelling of the head and neck.

• Pleural effusions may be present.

• Involvement of lymph nodes, usually above the diaphragm, may be a prominent feature.

• There may also be involvement of bone, skin, bone marrow, central nervous system, abdominal organs (but rarely bowel), and occasionally other sites such as lymphoid tissue of testis.

• Abdominal involvement is rare; most patients with an abdominal mass have small noncleaved cell or large cell lymphoma.

• Localized lymphoblastic lymphoma may occur in lymph nodes, bone, subcutaneous tissue, etc.

• This is heterogeneous group of tumors accounting for approximately 20% to 25% of childhood NHL.

• While the pathological types of LCL as described in REAL and WHO classification are anaplastic large cell and diffuse large cell, treatment decisions in pediatric LCLs are based on immunophenotype.

• Biologically, B-cell LCL occasionally is similar to small noncleaved cell lymphoma both with respect to immunophenotyping and chromosomal abnormalities (e.g., presence of an (8;14)translocation).

• T-lineage LCL can be divided into CD30 (Ki-1)-positive anaplastic LCL and other peripheral T-cell lymphoma.

• While the predominant immunophenotype of the anaplastic LCLs is T-cell, null-cell types have also been described.

• More than 90% of anaplastic LCLs are CD30-positive and have the nonrandom translocation (2;5), (p23;q35) leading to the expression of the fusion protein NPM ALK.

• Clinically, anaplastic LCL has a broad range of presentations, including involvement of lymph nodes and a variety of extranodal sites, particularly skin, bone, and less often gastrointestinal tract, lung, pleura, and muscle.

• Involvement of the CNS and bone marrow is uncommon.

• These are often associated with systemic symptoms (e.g., fever, weight loss) and a prolonged waxing and waning course.

• Burkitt’s and Burkitt’s-like.• Accounts for 40 to 50% of

childhood NHL and exhibits consistent clinical behavior.

• Up to 90% of these tumors are intra-abdominal.

• Other sites: testis, nasal sinuses, bone, peripheral lymph nodes, skin, bone marrow, and CNS.

• Small noncleaved cell lymphoma are of B-cell origin; they usually express surface immunoglobulin M (IgM) of either Kappa or Lambda light chain subtype.

• These tumors also express a characteristic chromosomal translocation, usually t(8;14) and more rarely t(8;22) or t(2;8).

• Each of these translocations juxtaposes the c-myc gene to immunoglobulin locus regulatory elements, resulting in the inappropriate expression of c-myc, a gene involved in cellular proliferation.

• Indolent generally slow growing; untreated survival measured in

years. common types include: follicular, small lymphocytic,

marginal zone, cutaneous T-cell lymphoma, Waldenstrom’s.

• Aggressive grow quickly; untreated survival measured in months. common types include: diffuse large B-cell, mantle cell, and

peripheral T-cell lymphoma.

• Highly Aggressive extremely rapid growth; untreated survival measured in

weeks. common types include: Burkitt’s and lymphoblastic.

CLINICAL GROUPS

• 53,400 people in the US are expected to be newly diagnosed with NHL this year1

• Approximately 300,000 people are currently living with the disease2

• American Cancer Society, Cancer Facts and Figures 2003

• SEER Cancer Statistics 1973-1999

Possible causes• Individuals exposed to

chemicals (pesticides, fertilizers or solvents)

• Individuals with compromised immune systems

• Heredity• Certain individuals infected

with human T-lymphotropic virus type I or HIV (AIDS)

• Most patients have no clear risk factors

• Exact cause is unknown

• Risk of bleeding– platelet count– cause of thrombocytopenia– comorbid disease– drugs

• Clinical manifestations– petechiae– purpura, ecchymoses– mucosal bleeding– menorrhagia– intracranial bleeding

megakaryocyte

formation of demarcation membranes

platelets

(pro)platelets

An abnormal decrease or deficiency of leukocytes circulating in the blood

increasednormal

thrombocytopenia

[TPO] free

[TPO] total normal

normal

normal platelet count

platelet

TPOplasma

Leukocytes (x 109/L) 6.8 [4.0 - 11.0]Hemoglobin (g/L) 130 [120-160]MCV (fL) 87 [80 - 100]Platelet count (x 109/L) 11 [150 - 450]MPV (fL) 12.5 [7.4 -10.4]

MEMBERS OF

TNF SUPERFAMILY

CD40 receptor &

CD40 L (CD154)

RANK

&

RANKL

TRAIL (Apo2L)

&

its receptors

CD30 receptors

&

CD30 L(CD153)

CD30 RECEPTOR

• CD30 is a 120-kilodalton (kD), type I transmembrane protein that contains 6 cysteine-rich pseudorepeat motifs in its extracellular domain .

• In healthy individuals, CD30 expression is restricted to a small number of activated B and T lymphocytes.

• Like many of the TNF receptors, CD30 can be shed in a soluble form (sCD30). An 85 kD sCD30 can be detected in culture supernatants of CD30 cell lines and sera of patients having CD30 tumors.

• sCD30 is detected at low levels in the sera of healthy individuals and in individuals who are infected with one of several different viruses, including hepatitis B and C, HIV, and EBV, or have an autoimmune disorder.

• An elevated level of serum sCD30 expression in patients with anaplastic large-cell lymphoma or Hodgkin disease is correlated with a poor prognosis, perhaps because a high level of sCD30 reflects a high tumor burden or because sCD30L may block the biologic effects of CD30L.

lymphomatoid papulosis

•.

activa

ted B and T ly

mphocytes

anaplastic l

arge-cell l

ymphoma

multiple m

yeloma,

adult T-ce

ll lym

phoma leuke

mia

mycosis

fungoides

immunoblastic lymphoma

Hodgkin disease

infectious m

ononucleosis

• Resting B cell• activated B cells• activated T cells, • natural killer (NK) cells• Eosinophils• granulocytes, • monocytes, • mast cells.• epithelial cells • Hassall corpuscles in the

thymus medulla.

• chronic lymphocytic leukemia (CLL),

• follicular B-cell lymphoma,

• hairy cell leukemia, • T-cell lymphoblastic • lymphoma, and• adult T-cell

leukemia• lymphoma.• Cells infected with

•CD30L (CD153) is a type II transmembrane protein that belongs to the TNFSF.•The human CD30L gene has been mapped to chromosome 9q33

•Like many TNF receptors, CD30’s cytoplasmic tail contains several TRAF-binding sequences that can bind TRAF-1, -2, -3, and -5. Both TRAF-2 and TRAF-5 have been implicated in CD30 activation of NF-ĸB

PHYSIOLOGIC FUNCTIONS• Role in T-cell costimulation• Cytokine and chemokine secretion, • Regulation of class-switch DNA recombination,• Antibody production in subsets of human Bcells• CD30L has diverse biologic activity in different CD30

cancers, ranging from enhancement of survival to no induction of apoptosis and cell cycle arre

• These paradoxical effects are caused by a differential effect on NF-B activation..

• CD40 is a 50 kD,• Type I transmembrane protein• Extracellular segment

containing 4 cysteine-rich repeats

• Its intracellular tail has no DD or kinase activity

• It can activate several second messenger pathways, including MAP kinases (ERK, c-jun amino terminal kinase [JNK], and p38) and NF-B. This activation is mediated by interacting with several TRAFs, including TRAF-2,-3,-5, and -6.

• CD 30 EXPRESSION• Non hematopoietic cells: urinary

bladder, ovary, breast, and liver.• Hematopoietic cells: normal B

lymphocytes, monocytes, and dendritic cells and subset of T cells.

• Malignant cells: B- and T-cell lymphomas and H/RS cells in Hodgkin’s disease

• Endothelial cells and EBV-associated nasopharyngeal carcinoma. Expressed more frequently and intensely in mature B lymphocytes than in precursor lymphoblastic leukemia cells

• 32–33 kDa.• Type II transmembrane protein.• Also known as CD154 • The human CD40L gene is located on

chromosome X26.3–27.1. • It also can be shed into smaller

biologically active soluble forms, which can be detected in sera of patients with lymphoid malignancies, autoimmune disease, or essential thrombocythemia, but not in sera of healthy individuals.

• Physiologic functions: priming dendritic cells to activate CD8 cytotoxic T cells, activation, survival, proliferation, differentiation, and immunoglobulin isotype switching of B cells, enhancing antigen presentation by means of up-regulation of their CD80 (B7.1) and CD86 (B7.2) costimulatory molecules, and regulating cytokine and chemokine secretion

• CD 40 L EXPRESSION• Activated T lymphocytes (more

frequently in CD4 than in CD8 lymphocytes)

• Activated B lymphocytes, NK cells, monocytes, basophils, eosinophils, dendritic cells, and platelets

• Nonhematopoietic cells, including endothelial and smooth muscle cells.

• In humans, constitutive expression of CD40L has been observed in T cells of patients having autoimmune disorders and in malignant B and Tlymphocytes of patients with lymphoma or leukemia.

RANKL/OPGL/TRANCE/ODF

• RANKL, also known as osteoprotegerin (OPG) ligand, TRANCE, and osteoclast differentiation factor (ODF).

• 317–amino acid.• Type II transmembrane protein that belongs to the TNFSF.• Has highest sequence homology to CD40L and TRAIL .• In addition to the 40–45 kD transmembrane form, RANKL also

exists in a smaller, 31 kD soluble form.• RANKL has two receptors: a transmembrane protein, called RANK,

and a soluble protein dimer, called OPG. • RANK is expressed primarily in activated T cells and osteoblasts. .• Recent data have suggested that the RANKL/RANK system may be

involved in the pathogenesis of human hematologic disorders, including Hodgkin disease and multiple myeloma.

TRAIL (Apo2L)• TRAIL is a type II membrane protein that shares the highest

sequence homology in its extracellular domain with FasL (28%) and TNF- (23%).

• The human TRAIL gene has been mapped to chromosome 3q26 . . • TRAIL has four exclusive receptors: DR4, DR5, DcR1, and DcR2 .• The genes for these four receptors are clustered on the short arm of

chromosome 8 (8p21).• DR4 (TRAIL-R1)and DR5 (TRAIL-R2, Killer, TRICK2) are death

receptors that contain a DD in their intracellular tail. Both receptors recruit a Fas-associated DD adaptor protein and activate caspase-8 and caspase-10.

• In addition to activating death pathways, TRAIL can also activate NF-B and JNK93–96 and the nitric oxide pathway. The two remaining receptors are decoy receptors that do not transduce apoptotic signals. Specifically, DcR1 (TRAIL-R3, TRID, LIT) lacks an intracellular tail, whereas DcR2 (TRAIL-R4, TRUNDD) has an incomplete DD in its intracellular tail.

DECOYRECEPTOR

Death domain

Membrane

DEATHRECEPTOR Decoy receptors:

Bind ligand, but not able to signal

TRAIL is a ligand of particular importance

TRAIL kill a wide variety of tumor cells with minimal effects on normal cells.

TRAIL's death receptors (TRAIL-R1 and TRAIL-R2) are mainly expressed in transformed cells

TRAIL’s decoy receptors (TRAIL-R3, TRAIL-R4 and TRAIL-R5) are expressed in normal cells. 

Unfortunately, TRAIL is very toxic to human hepatocytes.

But harmless for mouse hepatocytes (mice is wrong model again)

Tat protein, released from HIV-infected cells, can induce production of TRAIL by macrophages, resulting in the apoptosis of bystander T cells 

TRAIL in AIDS

• TRAIL has protective antitumor function mediated by TRAIL expressed by NK cells.

• TRAIL may also play a role in regulating cytokine and chemokine expression.

• TRAIL has a wide range of activity against human primary tumor cells and cell lines.

• In tumors of hematologic origin, TRAIL’s strongest killing activity is observed in Jurkat (T-cell lymphoblastic lymphoma/ leukemia) and 8226 (multiple myeloma) cell lines, In these cell lines, the activity of TRAIL was comparable with that of FasL

• TRAIL induced a moderate cell proliferation rather than cell death in 8226 (multiple myeloma) cell lines.

• TRAIL has been shown to be effective in primary and cultured multiple myeloma cells, including those that are resistant to doxorubicin

• TRAIL activates both the death receptor pathway and mitochondria pathway, as evidenced by the rapid activation of caspase-8, -9, and -3.

• Primary CLL. • Chronic and acute

leukemia. • TRAIL induced cell death

in a variety of AML cell lines.

• Primary acute lymphoblastic leukemia, acute myeloid leukemia, CLL, multiple myeloma, and chronic myelogenous leukemia cells.

• Tumor cells expressed functional TRAIL that killed target Jurkat cells by means of a TRAIL-specific mechanism.

• In multiple myeloma cells implicated in the pathogenesis of anemia associated with multiple myeloma.