NF-kB

NF-kB is a member of the Rel family proteins, which regulate cell cycle/proliferation and cytokine secretion. They include:
  - RelA (p65)
  - RelB
  - c-Rel
  - NF
kB1 (p50)
  - NF
kB2 (p52)
NF-
kB is a heterodimer composed of p50 and p65 subunits. It is inactivated by IkB in the cytoplasm. When TNF-a stimulates IkBa, this is phosphorylated and degraded in the proteasomes, allowing the translocation of NF-kB to the nucleus.

The role of nuclear factor-kappaB in the biology and treatment of multiple myeloma.
Semin Oncol. 2001 Dec;28(6):626-33.
Berenson JR, Ma HM, Vescio R.
[Review]
This review discusses several topics:
 - MM plasma cells show enhanced nuclear factor (NF)-kappa-B activity.
 - NF-kappaB is inhibited by I-kappa-B.
 - Increased levels of nuclear factor (NF)-kappa-B are associated with increased tumor cell survival in MM.
 - Chemoresistant myeloma cell-lines have increased NF-kappa-B activity compared to sensitive lines.
 - The proteasome inhibitor bortezomib inhibits NF-kappa-B activity.
 - Inhibition of NF-kappaB with bortezomib may overcome chemoresistance.

CD40 induces human multiple myeloma cell migration via phosphatidylinositol 3-kinase/AKT/NF-kappa B signaling.
Blood. 2003 Apr 1;101(7):2762-9.
Tai YT, Podar K, Mitsiades N, Lin B, Mitsiades C, Gupta D, Akiyama M, Catley L, Hideshima T, Munshi NC, Treon SP, Anderson KC.
CD40 activation is implicated in MM cell homing and migration. This study shows that  CD40-induced MM cell migration is primarily mediated by PI3K/AKT/NF-kappa-B signaling. Authors demonstrated that cross-linking CD40 (with either soluble CD40L or anti-CD40 monoclonal antibody) induces phosphatidyl-inositol 3-kinase (PI3K) activity and activates its downstream effector AKT in MM.1S cells. CD40 activation also activates the MAP kinase (MEK) pathway, but inhibition of ERK/MEK phosphorylation only partially (10%-15%) prevented migration, suggesting that MEK plays only a minor role in regulation of CD40-mediated MM migration. CD40 induced NF-kappa B activation as a downstream target of PI3K/AKT signaling.

 

PI3-K/AKT - mTOR

Role of the phosphatidylinositol 3-kinase/Akt and mTOR/P70S6-kinase pathways in the proliferation and apoptosis in multiple myeloma.
Oncogene. 2002 Sep 26;21(43):6587-97.
Pene F, Claessens YE, Muller O, Viguié F, Mayeux P, Dreyfus F, Lacombe C, Bouscary D.

Rapamycin sensitizes multiple myeloma cells to apoptosis induced by dexamethasone.
Blood. 2004 Apr 15;103(8):3138-47.
Strömberg T, Dimberg A, Hammarberg A, Carlson K, Osterborg A, Nilsson K, Jernberg-Wiklund H.

PI3-K/AKT/FKHR and MAPK signaling cascades are redundantly stimulated by a variety of cytokines and contribute independently to proliferation and survival of multiple myeloma cells.
Leukemia. 2004 Nov;18(11):1883-90.
Lentzsch S, Chatterjee M, Gries M, Bommert K, Gollasch H, Dörken B, Bargou RC.
Many different factors activate the growth and survival of MM cells. IL-6 and several bone marrow derived cytokines such as LIF, VEGF, bFGF, MIP-1alpha, SDF-1alpha, IL-1beta, SCF and IL-3 activated the MAPK pathway and induced proliferation of MM cells in vitro. These cytokines independently phosphorylated the PI3-K/AKT pathway and supported survival of primary human MM cells.

In vivo antitumor effects of the mTOR inhibitor CCI-779 against human multiple myeloma cells in a xenograft model.
Blood. 2004 Dec 15;104(13):4181-7.
Frost P, Moatamed F, Hoang B, Shi Y, Gera J, Yan H, Frost P, Gibbons J, Lichtenstein A.

Mammalian target of rapamycin inhibitors activate the AKT kinase in multiple myeloma cells by up-regulating the insulin-like growth factor receptor/insulin receptor substrate-1/phosphatidylinositol 3-kinase cascade.
Mol Cancer Ther. 2005 Oct;4(10):1533-40.
Shi Y, Yan H, Frost P, Gera J, Lichtenstein A.

Combined functional and molecular analysis of tumor cell signaling defines 2 distinct myeloma subgroups: Akt-dependent and Akt-independent multiple myeloma.
Blood. 2008 Oct 15;112(8):3403-11.
Zöllinger A, Stühmer T, Chatterjee M, Gattenlöhner S, Haralambieva E, Müller-Hermelink HK, Andrulis M, Greiner A, Wesemeier C, Rath JC, Einsele H, Bargou RC.
This study tried to assess the importance of Akt phosphatidylinositide 3-kinase (PI3K)/Akt pathway both in primary MM samples and MM cell lines. With various techniques of molecular biology, authors demonstrated that there are 2 MM subgroups: Akt-dependent and Akt-independent MM.

 

RAS

Possible roles for activating RAS mutations in the MGUS to MM transition and in the intramedullary to extramedullary transition in some plasma cell tumors.
Blood. 2005 Jan 1;105(1):317-23.
Rasmussen T, Kuehl M, Lodahl M, Johnsen HE, Dahl IM.
This study assessed the possible role of RAS mutations in tumor progression of MM. Authors evaluated the occurrence and type of K- and N-RAS mutations in plasma cells from patients with MGUS, MM, and extramedullary PC tumors. Only 1 RAS mutation was identified in 20 MGUS samples (5%), in contrast to 31% in MM. Surprisingly, RAS mutations were absent in bone marrow plasma cells from all patients with extramedullary disease. From 3 of 6 patients with both intramedullary and extramedullary PCs, RAS mutations were identified only in extramedullary PCs. These data suggest that RAS mutations may have a role in the transition from intramedullary to extramedullary disease.

 

TELOMERES

Telomerase and telomere length in multiple myeloma: correlations with disease heterogeneity, cytogenetic status, and overall survival.
Blood. 2003 Jun 15;101(12):4982-9.
Wu KD, Orme LM, Shaughnessy J Jr, Jacobson J, Barlogie B, Moore MA.
Authors investigated the significance of telomerase activity (TA) and telomere length (TL) in multiple myeloma (MM) in MM cells isolated from the bone marrow of 183 MM patients either at diagnosis or in relapse. Findings included:
 - Heterogeneity in telomerase expression. 36% of the patients had normal TA levels.
 - The TL of MM cells was shorter than that of the patients' own leukocytes.
 - 7 patients had unusually long telomeres, and 5/7 patients had low TA, indicating the presence of a TA-independent pathway of telomere stabilization.
 - Negative correlation between TA and TL or platelet count.
 - Negative correlation between TL and age, IL-6 levels, or beta2-microglobulin levels.
 - Cytogenetic abnormalities strongly correlated with TA and with short TL.
 - High TA and short TL were associated with poor prognosis.

Jumping translocations in multiple myeloma.
Cancer Genet Cytogenet. 2005 Sep;161(2):159-63.
Jamet D, Marzin Y, Douet-Guilbert N, Morel F, Le Bris MJ, Herry A, Banzakour S, Bourquard P, Morice P, Abgrall JF, Berthou C, De Braekeleer M.
Jumping translocations (JT) are nonreciprocal translocations which result in  extra copies of a same donor segment on different recipient chromosomes. Authors analyzed JT in 6 MM patients and reviewed the literature in other 24 patients. They found that breakpoints on the recipient chromosomes were pericentromeric in 46% of cases and telomeric in 40% of cases. Since telomeres consist of (TTAGGG)n tandem DNA repeats that are also present in the pericentromeric regions (interstitial telomeric sequences), they suggest that JT are the product of illegitimate recombination between telomeric and and interstitial repeat sequences.

 

VEGF / ANGIOGENESIS

Expression of vascular endothelial growth factor and its receptors in multiple myeloma and other hematopoietic malignancies. [REVIEW]
Semin Oncol. 2001 Dec;28(6):551-9.
Bellamy WT
Authors analyzed the expression of VEGF and its receptors in bone marrow samples from MM patients. They detected production of VEGF protein in malignant plasma cells from 78% of MM patients. In vitro, the addition of recombinant human VEGF stimulated colony formation, while antibody neutralization of VEGF inhibited colony growth. Therefore, VEGF may play a role in the growth of MM, through mechanisms that may be paracrine and/or autocrine.

Angiogenesis in multiple myeloma.
Semin Oncol. 2001 Dec;28(6):560-4.
Rajkumar SV, Kyle RA.
[Review]
Authors review data supporting the importance of angiogenesis in multiple myeloma. Angiogenesis is greater in multiple myeloma compared to MGUS. Neoplastic plasma cells express the angiogenic cytokines VEGF and basic fibroblast growth factor (bFGF). Microvascular density is higher in myeloma compared to controls, MGUS, and primary amyloidosis. In a study involving 74 newly diagnosed MM patients at the Mayo Clinic, overall survival was significantly longer in patients with low-grade angiogenesis compared to those with high-grade angiogenesis.

Bone marrow angiogenesis in 400 patients with monoclonal gammopathy of undetermined significance, multiple myeloma, and primary amyloidosis.
Clin Cancer Res. 2002 Jul;8(7):2210-6.
Rajkumar SV, Mesa RA, Fonseca R, Schroeder G, Plevak MF, Dispenzieri A, Lacy MQ, Lust JA, Witzig TE, Gertz MA, Kyle RA, Russell SJ, Greipp PR.

Using immunohistochemical staining for CD34 to identify microvessels, these authors analyzed BM angiogenesis in 76 patients with MGUS, 112 with smoldering myeloma, 99 newly diagnosed MM, 26 with advanced MM, 87 with primary amyloidosis, and 42 normal control BM samples. They found that BM angiogenesis was associated with disease progression, because it progressively increased along the spectrum of plasma cell dyscrasias, from MGUS to advanced myeloma. The median microvessel density (MVD) was significantly higher in MGUS, smoldering myeloma, newly diagnosed MM, and advanced MM compared with controls and amyloidosis. MVD was not significantly different between controls and AL. High-grade angiogenesis was present in 0% of controls, 0% of AL, 1% of MGUS, 3% of smoldering myeloma, 29% of newly diagnosed MM, and 42% of advanced MM. MVD correlated with the BM plasma cell labeling index and BM plasma cell percentage. Survival was shorter in MM patients with high-grade angiogenesis, compared with those with low-grade angiogenesis.

Vascular endothelial growth factor and its receptors in multiple myeloma.
Leukemia. 2003 Oct;17(10):1961-6.
Ria R, Roccaro AM, Merchionne F, Vacca A, Dammacco F, Ribatti D.
[Review]

Expression of VEGF and its receptors by myeloma cells.
Leukemia. 2003 Oct;17(10):2025-31.
Kumar S, Witzig TE, Timm M, Haug J, Wellik L, Fonseca R, Greipp PR, Rajkumar SV.
These authors studied the expression of VEGF and its receptors (VEGFR1 or Flt-1 and VEGFR2 or Flk-1/KDR) in MM cell lines and plasma cells isolated from patients. By IHC, VEGF expression by plasma cells was found in 18 of 20 MM patients. ELISA found VEGF secretion in all 6 different MM cell lines tested. RT-PCR for VEGF mRNA was positive in all 5 patient marrow samples and all 7 MM cell lines tested. All MM cell lines expressed VEGFR1 and 3 cell lines expressed VEGFR2. VEGFR1 expression was detected in all and VEGFR2 in all but one of marrow samples.

 

WNT

Bone marrow stromal cells secrete several Wnt ligands, which activate Wnt signaling in MM cells.
The canonical Wnt pathway is mediated through beta-catenin. Nonphosphorylated beta-catenin translocates to the nucleus and binds to T cell factor (TCF) transcriptional factors. The resulting transcriptional complex activates the expression of downstream target genes, such as Myc and Cyclin D1. Activation of the canonical Wnt signaling (active beta-catenin-TCF) are protected from apoptosis, while inhibition of the canonical Wnt signaling induces apoptosis.
Beta-catenin is not expressed in normal plasma cells, and it is expressed in MM cell lines and primary MM cells. The constituvely active beta-catenin in MM cells activates the canonical Wnt signal pathway and promotes growth, survival, and migration of MM cells.

Wnts induce migration and invasion of myeloma plasma cells.
Blood. 2005 Sep 1;106(5):1786-93.
Qiang YW, Walsh K, Yao L, Kedei N, Blumberg PM, Rubin JS, Shaughnessy J Jr, Rudikoff S.
This study identified multiple members of the wingless/int (Wnt) family as promoters of myeloma cell migration and invasion. Wnt-mediated migration was associated with the Wnt/RhoA pathway and did not require the beta-catenin signal. Wnt responsiveness of plasma cells may be involved in disease progression of MM.

Targeting the beta-catenin/TCF transcriptional complex in the treatment of multiple myeloma.
Proc Natl Acad Sci U S A. 2007 May 1;104(18):7516-21.
Sukhdeo K, Mani M, Zhang Y, Dutta J, Yasui H, Rooney MD, Carrasco DE, Zheng M, He H, Tai YT, Mitsiades C, Anderson KC, Carrasco DR.
In this study, the use of PKF115-584, a small molecular compound that disrupt the interaction of the beta-catenin/TCF complex, resulted in inhibition of tumor growth and prolonged survival in xenograft models of human MM.

 

OTHER

Occurrence of dysregulated oncogenes in primary plasma cells representing consecutive stages of myeloma pathogenesis: indications for different disease entities.
Br J Haematol. 2003 Oct;123(2):253-62.
Rasmussen T, Theilgaard-Mönch K, Hudlebusch HR, Lodahl M, Johnsen HE, Dahl IM.
These authors studied the expression pattern in plasma cells of putative oncogenes in cDNA archives from 96 subjects, including healthy individuals, patients with MGUS, MM, and MM with extramedullary disease. Their data support a stepwise transformation model with the progressive accumulation of genetic alterations and proliferative capacity during the tumor progression of plasma cell dyscrasias.

Characterization of clonogenic multiple myeloma cells.
Blood. 2004 Mar 15;103(6):2332-6.
Matsui W, Huff CA, Wang Q, Malehorn MT, Barber J, Tanhehco Y, Smith BD, Civin CI, Jones RJ.
Human MM cell lines contain a small population (< 5%) of CD138-negative cells with a good clonogenic potential in vitro. The phenotype of these cells resembled that one of post-germinal center B cells, and their clonogenic growth was inhibited by the anti-CD20 monoclonal antibody rituximab. These authors suggested that MM stem cells are CD138-negative B cells with the ability to replicate and differentiate into malignant CD138+ plasma cells.

MicroRNAs regulate critical genes associated with multiple myeloma pathogenesis.
Proc Natl Acad Sci U S A. 2008 Sep 2;105(35):12885-90.
Pichiorri F, Suh SS, Ladetto M, Kuehl M, Palumbo T, Drandi D, Taccioli C, Zanesi N, Alder H, Hagan JP, Munker R, Volinia S, Boccadoro M, Garzon R, Palumbo A, Aqeilan RI, Croce CM.
MicroRNAs (miRNAs) are small noncoding RNAs which target mRNAs and regulate gene expression. To assess the possible role of miRNAs in the malignant transformation of plasma cells, these authors studied miRNA expression in 49 MM-derived cell lines, 16 MM patients, 6 patients with MGUS, and 6 normal donors. They identified and described a MM miRNA signature, with miRNAs that modulate the expression of proteins critical to the pathogenesis of MM.

 

 


Giampaolo Talamo, M.D.