Endogenous Bcl-xL is essential for Myc-driven lymphomagenesis in mice

Abstract Impaired apoptosis is a cancer hallmark, and some types of lymphomas and other cancers harbor mutations that directly affect key cell death regulators, such as Bcl-2 family members. However, because the majority of tumors seem to lack such mutations, we are examining the hypothesis that tumorigenesis can be sustained at least initially by the normal expression of specific endogenous pro-survival Bcl-2 family members. We previously demonstrated that the lymphomagenesis in Εμ-myc transgenic mice, which constitutively overexpress the c-Myc oncoprotein in B-lymphoid cells and develop pre-B and B-cell lymphomas, does not require endogenous Bcl-2. In striking contrast, we report here that loss in these mice of its close relative Bcl-xL attenuated the pre-neoplastic expansion of pro-B and pre-B cells otherwise driven by c-Myc overexpression, sensitized these cells to apoptosis and ablated lymphoma formation. Remarkably, even loss of a single bcl-x allele delayed the lymphomagenesis. These findings identify Bcl-xL as a prerequisite for the emergence of c-Myc–driven pre-B/B lymphoma and suggest that BH3 mimetic drugs may provide a prophylactic strategy for c-Myc–driven tumors.

Download Full-text

Expression of the c-myc oncogene under control of an immunoglobulin enhancer in E mu-myc transgenic mice.

Molecular and Cellular Biology ◽

10.1128/mcb.7.4.1436 ◽

1987 ◽

Vol 7 (4) ◽

pp. 1436-1444 ◽

Cited By ~ 42

Author(s):

W S Alexander ◽

J W Schrader ◽

J M Adams

Keyword(s):

Bone Marrow ◽

Transgenic Mice ◽

B Lymphocyte ◽

Lymphoid Cells ◽

Lymphoid Tissues ◽

Myc Oncogene ◽

Feedback Model ◽

B Lymphocyte Development ◽

B Lymphoid ◽

Spleen And Lymph Nodes

Transgenic mice bearing a cellular myc oncogene coupled to the immunoglobulin heavy-chain enhancer (E mu) exhibit perturbed B-lymphocyte development and succumb to B lymphoid tumors. To investigate how the enhancer has affected myc expression, we analyzed the structure and abundance of myc transcripts in tissues of prelymphomatous mice and in the lymphomas. Expression of the E mu-myc transgene appeared to be confined largely to B lymphoid cells, being dominant in bone marrow, spleen, and lymph nodes, with no detectable expression in T cells or other hematopoietic lineages examined. The myc transcripts initiated very predominantly at the normal myc promoters, although use of the more upstream myc promoter was accentuated and an enhancer-associated promoter may be used infrequently. The level of E mu-myc transcripts in the preneoplastic lymphoid tissues and in the E mu-myc tumors was not markedly higher than myc RNA levels in proliferating normal lymphocytes. Thus, enforced expression of structurally normal myc transcripts at only a modestly elevated level has profound biological consequences. The absence of detectable endogenous c-myc RNA in any tumor, or in preneoplastic bone marrow, supports a negative feedback model for normal c-myc regulation.

Download Full-text

JunB inhibits proliferation and transformation in B-lymphoid cells

Blood ◽

10.1182/blood-2003-03-0915 ◽

2003 ◽

Vol 102 (12) ◽

pp. 4159-4165 ◽

Cited By ~ 55

Author(s):

Agnieszka P. Szremska ◽

Lukas Kenner ◽

Eva Weisz ◽

Rene G. Ott ◽

Emmanuelle Passegué ◽

...

Keyword(s):

Transgenic Mice ◽

B Cell ◽

Transgenic Animals ◽

Inhibitory Effect ◽

Lymphoid Cells ◽

Negative Regulator ◽

Transgenic Cells ◽

B Lymphoid

Abstract The activator protein 1 (AP-1) member JunB has recently been implicated in leukemogenesis. Here we surveyed human lymphoma samples for expression of JunB and other AP-1 members (c-Jun, c-Fos, Fra1, JunD). JunB was strongly expressed in T-cell lymphomas, but non-Hodgkin B-cell lymphomas do not or only weakly express JunB. We therefore asked whether JunB acted as a negative regulator of B-cell development, proliferation, and transformation. We used transgenic mice that expressed JunB under the control of the ubiquitin C promoter; these displayed increased JunB levels in both B- and T-lymphoid cells. JunB transgenic cells of B-lymphoid, but not of T-lymphoid, origin responded poorly to mitogenic stimuli. Furthermore, JunB transgenic cells were found to be less susceptible to the transforming potential of the Abelson oncogene in vitro. In addition, overexpression of JunB partially protected transgenic mice against the oncogenic challenge in vivo. However, transformed B cells eventually escaped from the inhibitory effect of JunB: the proliferative response was similar in explanted tumor-derived cells from transgenic animals and those from wild-type controls. Our results identify JunB as a novel regulator of B-cell proliferation and transformation. (Blood. 2003;102:4159-4165)

Download Full-text

Role of Bcl-2 Family in Lymphoid Malignancies

Blood ◽

10.1182/blood.v122.21.sci-41.sci-41 ◽

2013 ◽

Vol 122 (21) ◽

pp. SCI-41-SCI-41

Author(s):

Andreas Strasser ◽

G. Kelly ◽

S. Glaser ◽

S. Grabow ◽

A. Delbridge ◽

...

Keyword(s):

Transgenic Mice ◽

Hematological Malignancies ◽

Cell Cycle Control ◽

Family Members ◽

B Lymphoma ◽

Over Expression ◽

Death Studies ◽

Lymphoid Malignancies ◽

Single Allele

Abstract Impaired apoptosis is considered one of the prerequisites for the development of most, if not all, cancers, but the mechanisms that guarantee the sustained survival of most cancer cells remain unknown. Members of the Bcl-2 family are key regulators of apoptosis and include proteins essential for cell survival and those required to initiate cell death. Studies with transgenic mice have shown that over-expression of Bcl-2 or related pro-survival family proteins, such as Bcl-xL or Mcl-1, can promote tumorigenesis, particularly in conjunction with mutations that deregulate cell cycle control, such as deregulated c-myc expression. It is, however, not known whether expression of pro-survival Bcl-2 family members under endogenous control is required to maintain the survival of cells undergoing neoplastic transformation. Using Eµ-myc transgenic mice, a well-characterized model of human Burkitt’s lymphoma, we investigated the role of endogenous Bcl-2 in lymphoma development. Bcl-2 was found to be dispensable for the development of Eµ-myc pre-B/B lymphoma. In contrast, loss of Bcl-xL and even, more remarkable, loss of a single allele of Mcl1 greatly impaired lymphoma development. Experiments with inducible knockout mice demonstrated that Mcl-1 but not Bcl-xL is essential for the sustained survival and expansion of Myc-driven malignant pore-B/B lymphoma. Remarkably, even loss of one Mcl1allele greatly impaired lymphoma growth. These findings were translated into using lymphoid malignancies by using inducible expression of selective antagonists of distinct pro-survival Bcl-2 family members. Such studies showed that Mcl-1 is also critical for the sustained survival and expansion of Burkitt Lymphoma, a Myc-driven malignancy. These observations indicate that (even relatively weak) targeting of Mcl-1 may be an attractive strategy for the treatment of Myc-driven hematological malignancies. Disclosures: Strasser: Genentech Inc: Consultancy.

Download Full-text

SHOC2 scaffold protein modulates daunorubicin-induced cell death through p53 modulation in lymphoid leukemia cells

Scientific Reports ◽

10.1038/s41598-020-72124-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Vanessa Silva Silveira ◽

Kleiton Silva Borges ◽

Verena Silva Santos ◽

Mariana Tannús Ruckert ◽

Gabriela Maciel Vieira ◽

...

Keyword(s):

Dna Damage ◽

Cell Death ◽

Scaffold Protein ◽

Lymphoid Cells ◽

Leukemic Cells ◽

Lymphoid Leukemia ◽

P53 Expression ◽

Free Survival ◽

Significant Impairment ◽

B Lymphoid

Abstract SHOC2 scaffold protein has been mainly related to oncogenic ERK signaling through the RAS-SHOC2-PP1 phosphatase complex. In leukemic cells however, SHOC2 upregulation has been previously related to an increased 5-year event-free survival of pediatric pre-B acute lymphoid leukemia, suggesting that SHOC2 could be a potential prognostic marker. To address such paradoxical function, our study investigated how SHOC2 impact leukemic cells drug response. Our transcriptome analysis has shown that SHOC2 can modulate the DNA-damage mediated by p53. Notably, upon genetic inhibition of SHOC2 we observed a significant impairment of p53 expression, which in turn, leads to the blockage of key apoptotic molecules. To confirm the specificity of DNA-damage related modulation, several anti-leukemic drugs has been tested and we did confirm that the proposed mechanism impairs cell death upon daunorubicin-induced DNA damage of human lymphoid cells. In conclusion, our study uncovers new insights into SHOC2 function and reveals that this scaffold protein may be essential to activate a novel mechanism of p53-induced cell death in pre-B lymphoid cells.

Download Full-text

Expression of the c-myc oncogene under control of an immunoglobulin enhancer in E mu-myc transgenic mice

Molecular and Cellular Biology ◽

10.1128/mcb.7.4.1436-1444.1987 ◽

1987 ◽

Vol 7 (4) ◽

pp. 1436-1444

Author(s):

W S Alexander ◽

J W Schrader ◽

J M Adams

Keyword(s):

Bone Marrow ◽

Transgenic Mice ◽

B Lymphocyte ◽

Lymphoid Cells ◽

Lymphoid Tissues ◽

Myc Oncogene ◽

Feedback Model ◽

B Lymphocyte Development ◽

B Lymphoid ◽

Spleen And Lymph Nodes

Download Full-text

Development of a Blastoid Variant, Mantle Cell Lymphoma Model in Transgenic Mice.

Blood ◽

10.1182/blood.v106.11.419.419 ◽

2005 ◽

Vol 106 (11) ◽

pp. 419-419

Author(s):

Richard J. Ford ◽

Yen-Chiu Lin-Lee ◽

Long Shen ◽

Connie Xu ◽

Chongjie Zhang ◽

...

Keyword(s):

Transgenic Mice ◽

B Cell ◽

Mantle Cell Lymphoma ◽

B Lymphocytes ◽

Cell Lymphoma ◽

Lymphoid Cells ◽

Mantle Cell ◽

B Lymphoid ◽

Hodgkin's Lymphomas

Abstract Mantle Cell Lymphoma (MCL) is a poorly understood, aggressive histotype of B-cell non-Hodgkin’s Lymphomas (NHL-B) that remains the most therapeutically resistant of the NHL-B. Little is known regarding why MCL is so clinically aggressive and therapeutically refractory. Blastoid variant MCL (MCL-BV) is an even more aggressive form of MCL that appears to be increasing in incidence in the US. It may represent progression from classic MCL, often with leukemic involvement and complex lymphoma karyotypes. Interleukin 14 (IL-14) is cytokine that was identified and cloned from a Burkitt lymphoma (BL) cell line that acts as a growth factor for normal B-lymphocytes. The expression of IL-14a protein and mRNA levels are elevated at lease fifty-fold in B-cell non-Hodgkin’s Lymphomas (NHL-B), including mantle cell lymphoma (MCL), in contrast to very low levels of IL-14a in quiescent (Go) B cells by both western and northern blot analysis. To evaluate the role of IL-14 in vivo, we have generated transgenic mice expressing IL-14 with pEuSR. The IL-14 TG mice generally live a normal life span, however when autopsies are performed at 18 months of age, splenomegaly is noted, and 50% have evidence of B cell lymphoma. This lymphoma is CD5+, CD19+, sIgM+, CD21− and contains a monoclonal population of B-lymphocytes with rearranged immunoglobulin genes. Morphologically the lymphoma arising in IL-14 transgenic mice resembles the centroblastic/Immunoblastic histotype of DLBCL. Because of the frequent involvement of c-myc in various B cell malignancies, we crossed Eμ-myc (c-myc TG) mice with the IL-14 TG mice. By 3 months of age, 100% of the double transgenic (DTG) mice develop an aggressive B cell malignancy that is characterized by extensive lymphadenopathy and splenomegaly with intermediate to large atypical lymphoid cells, strongly resembling MCL-BV morphologically. This tumor, like that derived from the IL-14 TG mice, is CD5+, CD19+, sIgM+, CD21−. It is also CD23− and over-expresses Cyclin D1 in monoclonal B lymphoid cells with re-arranged IgH immunoglobulin genes, mimicking the MCL phenotype. At the time of autopsy, tumor infiltration of DTG mice is generally found in all organs evaluated, including peripheral blood, lymph nodes, spleen, liver, bone marrow, thymus and kidneys, consistent with the usual findings in MCL-BV. No tumors are observed in IL-14α TG or c-myc TG mice autopsied at this age. This MCL-BV model allows for the molecular and genotypic characterization of the murine B lymphoid cell compartment from birth to lymphoma development (3 mos.), including histogenesis and functional determination of the growth and survival characteristics of these tumors in DTG bone marrow and peripheral B cell populations. Preliminary comparative in vitro and in vivo (SCID Xeno-transplants) studies in DTG/MCL-BV lymphomas have shown additional molecular similarities to the pathophysiology (e.g constitutive NF-kB activation) of MCL-BV cell lines and patient samples, that should provide insights for future potential therapeutic approaches to MCL.

Download Full-text

Insights from transgenic mice regarding the role of bcl -2 in normal and neoplastic lymphoid cells

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1994.0108 ◽

1994 ◽

Vol 345 (1313) ◽

pp. 289-295 ◽

Cited By ~ 25

Keyword(s):

Transgenic Mice ◽

Cell Survival ◽

Lupus Erythematosus ◽

Low Frequency ◽

Rapid Onset ◽

Chromosome Translocation ◽

Lymphoid Cells ◽

Cytotoxic Agents ◽

B Lymphoid ◽

The Impact

The bcl -2 gene was first discovered by molecular analysis of the 14; 18 chromosome translocation which is the hallmark of most cases of human follicular lymphoma. To date, it is unique among proto-oncogenes because, rather than promoting cell proliferation, it fosters cell survival. This review summarizes the impact of constitutive bcl -2 expression on the development and function of lymphocytes as well as their malignant transformation. Expression of a bcl -2 transgene in the B lymphoid compartment profoundly perturbed homeostasis and, depending on the genetic background, predisposed to a severe autoimmune disease resembling human systemic lupus erythematosus. T lymphoid cells from transgenic mice were remarkably resistant to diverse cytotoxic agents. Nevertheless, T lymphoid homeostasis was unaffected and tolerance to self was maintained. Expression of high levels of Bcl-2 facilitated the development of B lymphoid tumours but at relatively low frequency and with long latency. Co-expression of myc and bcl -2, on the other hand, promoted the rapid onset of novel tumours which appeared to derive from a lympho-myeloid stem or progenitor cell. Introduction of the bcl -2 transgene into scid mice facilitated the survival and differentiation of pro-B but not pro-T cells, suggesting that a function necessary to supplement or complement the action of Bcl-2 is expressed later in the T than the B lineage. Crosses of the bcl -2 transgenic mice with p53- /- mice have addressed whether loss of p53 function and gain of bcl -2 function are synergistic for lymphoid cell survival.

Download Full-text

Bcl-2, Bcl-xL, and Bcl-w are not equivalent targets of ABT-737 and navitoclax (ABT-263) in lymphoid and leukemic cells

Blood ◽

10.1182/blood-2011-12-400929 ◽

2012 ◽

Vol 119 (24) ◽

pp. 5807-5816 ◽

Cited By ~ 129

Author(s):

Delphine Mérino ◽

Seong L. Khaw ◽

Stefan P. Glaser ◽

Daniel J. Anderson ◽

Lisa D. Belmont ◽

...

Keyword(s):

Clinical Studies ◽

Lymphoid Cells ◽

High Expression ◽

Leukemic Cells ◽

Lymphoid Malignancies ◽

Orally Bioavailable ◽

Bh3 Mimetic ◽

Striking Contrast

Abstract The BH3-mimetic ABT-737 and an orally bioavailable compound of the same class, navitoclax (ABT-263), have shown promising antitumor efficacy in preclinical and early clinical studies. Although both drugs avidly bind Bcl-2, Bcl-xL, and Bcl-w in vitro, we find that Bcl-2 is the critical target in vivo, suggesting that patients with tumors overexpressing Bcl-2 will probably benefit. In human non-Hodgkin lymphomas, high expression of Bcl-2 but not Bcl-xL predicted sensitivity to ABT-263. Moreover, we show that increasing Bcl-2 sensitized normal and transformed lymphoid cells to ABT-737 by elevating proapoptotic Bim. In striking contrast, increasing Bcl-xL or Bcl-w conferred robust resistance to ABT-737, despite also increasing Bim. Cell-based protein redistribution assays unexpectedly revealed that ABT-737 disrupts Bcl-2/Bim complexes more readily than Bcl-xL/Bim or Bcl-w/Bim complexes. These results have profound implications for how BH3-mimetics induce apoptosis and how the use of these compounds can be optimized for treating lymphoid malignancies.

Download Full-text