Brandimarte L, Pierini V, Di Giacomo D, et al.
New MLLT10 gene recombinations in pediatric T-acute lymphoblastic leukemia.
Blood. 2013; 121(25):5064-7 [PubMed] Related Publications

The MLLT10 gene, located at 10p13, is a known partner of MLL and PICALM in specific leukemic fusions generated from recurrent 11q23 and 11q14 chromosome translocations. Deep sequencing recently identified NAP1L1/12q21 as another MLLT10 partner in T-cell acute lymphoblastic leukemia (T-ALL). In pediatric T-ALL, we have identified 2 RNA processing genes, that is, HNRNPH1/5q35 and DDX3X/Xp11.3 as new MLLT10 fusion partners. Gene expression profile signatures of the HNRNPH1- and DDX3X-MLLT10 fusions placed them in the HOXA subgroup. Remarkably, they were highly similar only to PICALM-MLLT10-positive cases. The present study showed MLLT10 promiscuity in pediatric T-ALL and identified a specific MLLT10 signature within the HOXA subgroup.

Related: FISH Acute Lymphocytic Leukemia (ALL) Childhood Acute lymphoblastic leukaemia (ALL) ALL - Molecular Biology MLLT10 gene

Watanabe-Okochi N, Yoshimi A, Sato T, et al.
The shortest isoform of C/EBPβ, liver inhibitory protein (LIP), collaborates with Evi1 to induce AML in a mouse BMT model.
Blood. 2013; 121(20):4142-55 [PubMed] Related Publications

Ecotropic viral integration site 1 (Evi1) is one of the master regulators in the development of acute myeloid leukemia (AML) and myelodysplastic syndrome. High expression of Evi1 is found in 10% of patients with AML and indicates a poor outcome. Several recent studies have indicated that Evi1 requires collaborative factors to induce AML. Therefore, the search for candidate factors that collaborate with Evi1 in leukemogenesis is one of the key issues in uncovering the mechanism of Evi1-related leukemia. Previously, we succeeded in making a mouse model of Evi1-related leukemia using a bone marrow transplantation (BMT) system. In the Evi1-induced leukemic cells, we identified frequent retroviral integrations near the CCAAT/enhancer-binding protein β (C/EBPβ) gene and overexpression of its protein. These findings imply that C/EBPβ is a candidate gene that collaborates with Evi1 in leukemogenesis. Cotransduction of Evi1 and the shortest isoform of C/EBPβ, liver inhibitory protein (LIP), induced AML with short latencies in a mouse BMT model. Overexpression of LIP alone also induced AML with longer latencies. However, excision of all 3 isoforms of C/EBPβ (LAP*/LAP/LIP) did not inhibit the development of Evi1-induced leukemia. Therefore, isoform-specific intervention that targets LIP is required when we consider C/EBPβ as a therapeutic target.

Related: Acute Myeloid Leukemia (AML)

Conway AE, Scotland PB, Lavau CP, Wechsler DS
A CALM-derived nuclear export signal is essential for CALM-AF10-mediated leukemogenesis.
Blood. 2013; 121(23):4758-68 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

The t(10;11) chromosomal translocation gives rise to the CALM-AF10 fusion gene and is found in patients with aggressive and difficult-to-treat hematopoietic malignancies. CALM-AF10-driven leukemias are characterized by HOXA gene up-regulation and a global reduction in H3K79 methylation. DOT1L, the H3K79 methyltransferase, interacts with the octapeptide/leucine zipper domain of AF10, and this region has been shown to be necessary and sufficient for CALM-AF10-mediated transformation. However, the precise role of CALM in leukemogenesis remains unclear. Here, we show that CALM contains a nuclear export signal (NES) that mediates cytoplasmic localization of CALM-AF10 and is necessary for CALM-AF10-dependent transformation. Fusions of the CALM NES (NES(CALM)-AF10) or NES motifs from heterologous proteins (ABL1, Rev, PKIA, APC) in-frame with AF10 are sufficient to immortalize murine hematopoietic progenitors in vitro. The CALM NES is essential for CALM-AF10-dependent Hoxa gene up-regulation and aberrant H3K79 methylation, possibly by mislocalization of DOT1L. Finally, we observed that CALM-AF10 leukemia cells are selectively sensitive to inhibition of nuclear export by Leptomycin B. These findings uncover a novel mechanism of leukemogenesis mediated by the nuclear export pathway and support further investigation of the utility of nuclear export inhibitors as therapeutic agents for patients with CALM-AF10 leukemias.

Chamorro-Garcia R, Cervera M, Arredondo JJ
AF10 plays a key role in the survival of uncommitted hematopoietic cells.
PLoS One. 2012; 7(12):e51626 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

Hematopoiesis is a complex process regulated by both cell intrinsic and cell extrinsic factors. Alterations in the expression of critical genes during hematopoiesis can modify the balance between stem cell differentiation and proliferation, and may ultimately give rise to leukemia and other diseases. AF10 is a transcription factor that has been implicated in the development of leukemia following chromosomal rearrangements between the AF10 gene and one of at least two other genes, MLL and CALM. The link between AF10 and leukemia, together with the known interactions between AF10 and hematopoietic regulators, suggests that AF10 may be important in hematopoiesis and in leukemic transformation. Here we show that AF10 is important for proper hematopoietic differentiation. The induction of hematopoietic differentiation in both human hematopoietic cell lines and murine total bone marrow cells triggers a decrease of AF10 mRNA and protein levels, particularly in stem cells and multipotent progenitors. Gain- and loss-of-function studies demonstrate that over- or under-expression of AF10 leads to apoptotic cell death in stem cells and multipotent progenitors. We conclude that AF10 plays a key role in the maintenance of multipotent hematopoietic cells.

Related: Apoptosis Leukemia MLLT10 gene

Novak RL, Harper DP, Caudell D, et al.
Gene expression profiling and candidate gene resequencing identifies pathways and mutations important for malignant transformation caused by leukemogenic fusion genes.
Exp Hematol. 2012; 40(12):1016-27 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

NUP98-HOXD13 (NHD13) and CALM-AF10 (CA10) are oncogenic fusion proteins produced by recurrent chromosomal translocations in patients with acute myeloid leukemia (AML). Transgenic mice that express these fusions develop AML with a long latency and incomplete penetrance, suggesting that collaborating genetic events are required for leukemic transformation. We employed genetic techniques to identify both preleukemic abnormalities in healthy transgenic mice as well as collaborating events leading to leukemic transformation. Candidate gene resequencing revealed that 6 of 27 (22%) CA10 AMLs spontaneously acquired a Ras pathway mutation and 8 of 27 (30%) acquired an Flt3 mutation. Two CA10 AMLs acquired an Flt3 internal-tandem duplication, demonstrating that these mutations can be acquired in murine as well as human AML. Gene expression profiles revealed a marked upregulation of Hox genes, particularly Hoxa5, Hoxa9, and Hoxa10 in both NHD13 and CA10 mice. Furthermore, mir196b, which is embedded within the Hoxa locus, was overexpressed in both CA10 and NHD13 samples. In contrast, the Hox cofactors Meis1 and Pbx3 were differentially expressed; Meis1 was increased in CA10 AMLs but not NHD13 AMLs, whereas Pbx3 was consistently increased in NHD13 but not CA10 AMLs. Silencing of Pbx3 in NHD13 cells led to decreased proliferation, increased apoptosis, and decreased colony formation in vitro, suggesting a previously unexpected role for Pbx3 in leukemic transformation.

Related: Apoptosis Leukemia Acute Myeloid Leukemia (AML) HOXA9 gene

Borel C, Dastugue N, Cances-Lauwers V, et al.
PICALM-MLLT10 acute myeloid leukemia: a French cohort of 18 patients.
Leuk Res. 2012; 36(11):1365-9 [PubMed] Related Publications

The PICALM-MLLT10 fusion gene, generated by the t(10;11)(p12-13;q14-21) translocation, is a rare but recurrent event in acute leukemias. In this study, we assessed the characteristics and outcome of 18 PICALM-MLLT10 AML patients. As compared with non PICALM-MLLT10 patients (n=72), PICALM-MLLT10 AML were characterized by more frequent extramedullary diseases, CD7 expression and higher platelet counts. Three out of four therapy-related PICALM-MLLT10 AMLs had been previously treated for diffuse large B-cell lymphoma. The complete response rate was 71% after intensive chemotherapy. PICALM-MLLT10 patients had a shorter median overall survival than patients with favorable cytogenetics (12 months vs. not reached, p=0.07) but not significantly different from those of intermediate (26 months, p=0.32) or unfavorable cytogenetic groups (8 months, p=0.13). Long term responses were achieved in a subset of patients after allogeneic stem-cell transplantation but also after high-dose cytarabine.

Related: France FISH Acute Myeloid Leukemia (AML) Childhood Acute Myeloid Leukaemia AML - Molecular Biology

Madson JG
Multiple or familial café-au-lait spots is neurofibromatosis type 6: clarification of a diagnosis.
Dermatol Online J. 2012; 18(5):4 [PubMed] Related Publications

A café-au-lait macule (CALM) is an evenly pigmented macule or patch of variable size. Solitary CALMs are common birthmarks in up to 2.5 percent of normal neonates and their incidence rises to up to 25 percent in preschool-aged children. Two or more CALMs occur much less frequently. Multiple lesions may warrant investigation to identify an underlying disease including neurofibromatosis types 1 (NF1), neurofibromatosis type 2, McCune-Albright syndrome, and neurofibromatosis type 1-like syndrome. Considered a hallmark and diagnostic criteria for NF1 is the presence of 6 or more CALMs greater than 0.5 cm in prepubertal individuals. Rare reports describe families which demonstrate the phenomenon of multiple CALMs without other stigmata of NF1 or evidence of other systemic disease. Herein is a description of the condition and justification for this entity to be named Neurofibromatosis type 6.

Related: Neurofibromatosis

Stevens CA, Chiang PW, Messiaen LM
Café-au-lait macules and intertriginous freckling in piebaldism: clinical overlap with neurofibromatosis type 1 and Legius syndrome.
Am J Med Genet A. 2012; 158A(5):1195-9 [PubMed] Related Publications

Piebaldism is an autosomal dominant disorder characterized by congenital hypopigmented patches of skin and hair and has been found to be associated with mutations in the KIT or SLUG genes. Café-au-lait macules (CALM) may occasionally be seen in piebaldism. There are four reports describing six patients who were said to have both piebaldism and neurofibromatosis type 1 (NF1) due to the presence of multiple CALM and intertriginous freckling, but none of these patients had undergone comprehensive NF1 mutation analysis. We describe a large family with piebaldism in which two members meet diagnostic criteria for NF1 based on the presence of >5 CALM and intertriginous freckling. Interestingly, only these two family members are of mixed race, which could be of importance. A novel complex mutation in the KIT gene was identified in several family members affected with piebaldism; the proband meeting diagnostic criteria for NF1 also underwent comprehensive NF1 and SPRED1 testing with no mutations detected. These findings suggest that piebaldism may occasionally include CALM and intertriginous freckling, which may create diagnostic confusion especially in the absence of a family history of piebaldism. However, careful clinical evaluation and molecular testing if necessary should distinguish these two disorders.

Mulaw MA, Krause A, Krause AJ, et al.
CALM/AF10-positive leukemias show upregulation of genes involved in chromatin assembly and DNA repair processes and of genes adjacent to the breakpoint at 10p12.
Leukemia. 2012; 26(5):1012-9 [PubMed] Related Publications

The t(10;11)(p12;q14) is a recurring chromosomal translocation that gives rise to the CALM/AF10 fusion gene, which is found in acute myeloid leukemia, acute lymphoblastic leukemia and malignant lymphoma. We analyzed the fusion transcripts in 20 new cases of CALM/AF10-positive leukemias, and compared the gene expression profile of 10 of these to 125 patients with other types of leukemia and 10 normal bone marrow samples. Based on gene set enrichment analyses, the CALM/AF10-positive samples showed significant upregulation of genes involved in chromatin assembly and maintenance and DNA repair process, and downregulation of angiogenesis and cell communication genes. Interestingly, we observed a striking upregulation of four genes located immediately centromeric to the break point of the t(10;11)(p12;q14) on 10p12 (COMMD3 (COMM domain containing 3), BMI1 (B lymphoma Mo-MLV insertion region 1 homolog), DNAJC1 (DnaJ (Hsp40) homolog subfamily C member 1) and SPAG6 (sperm associated antigen 6)). We also conducted semiquantitative reverse transcriptase-PCR analysis on leukemic blasts from a murine CALM/AF10 transplantation model that does not have the translocation. Commd3, Bmi1 and Dnajc1, but not Spag6 were upregulated in these samples. These results strongly indicate that the differential regulation of these three genes is not due to the break point effect but as a consequence of the CALM/AF10 fusion gene expression, though the mechanism of regulation is not well understood.

Related: Chromosome 10 Leukemia MLLT10 gene

Solly F, Angelot F, Garand R, et al.
CD304 is preferentially expressed on a subset of B-lineage acute lymphoblastic leukemia and represents a novel marker for minimal residual disease detection by flow cytometry.
Cytometry A. 2012; 81(1):17-24 [PubMed] Related Publications

Minimal residual disease (MRD) has emerged as a major prognostic factor for monitoring patients with B-lineage acute lymphoblastic leukemia (B-ALL). The quantification of MRD by flow cytometry (FC) is based on the identification of a leukemia-associated phenotype (LAP). Because phenotypic switch is common during treatment, multiple LAPs must be available and used for MRD detection over time. We evaluated the potential usefulness of CD304 as a new marker for monitoring MRD. CD304 was expressed in 48% of B-ALL (24/50) with discriminative fluorescence intensity compared with CD304-negative normal B-cell precursors (n = 15). The sensitivity of CD304-based MRD detection reached 10(-4), as with some of established LAPs. The stability of CD304 expression evaluated during therapy and at relapse confirms the usefulness of this marker for MRD quantification. Finally, CD304 was repeatedly expressed in patients with TEL-AML1 gene rearrangement, which warrants further investigation on its potential relevance as a prognosis marker or therapeutic target.

Lundemo AG, Pettersen CH, Berge K, et al.
Tetradecylthioacetic acid inhibits proliferation of human SW620 colon cancer cells--gene expression profiling implies endoplasmic reticulum stress.
Lipids Health Dis. 2011; 10:190 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

BACKGROUND: Previous reports have shown an antiproliferative effect of the synthetic, 3-thia fatty acid tetradecylthioacetic acid (TTA) on different cancer cells in vitro and in vivo. The mechanisms behind the observed effects are poorly understood. We therefore wanted to explore the molecular mechanisms involved in TTA-induced growth inhibition of the human colon cancer cell line SW620 by gene expression profiling.
METHODS: An antiproliferative effect of TTA on SW620 cells in vitro was displayed in real time using the xCELLigence System (Roche). Affymetrix gene expression profiling was performed to elucidate the molecular mechanisms behind the antiproliferative effect of TTA. Changes in gene expression were verified at protein level by western blotting.
RESULTS: TTA reduced SW620 cell growth, measured as baseline cell index, by 35% and 55% after 48 h and 72 h, respectively. We show for the first time that TTA induces an endoplasmic reticulum (ER) stress response in cancer cells. Gene expression analysis revealed changes related to ER stress and unfolded protein response (UPR). This was verified at protein level by phosphorylation of eukaryote translation initiation factor 2 alpha (eIF2α) and downstream up-regulation of activating transcription factor 4 (ATF4). Transcripts for positive and negative cell cycle regulators were down- and up-regulated, respectively. This, together with a down-regulation of Cyclin D1 at protein level, indicates inhibition of cell cycle progression. TTA also affected transcripts involved in calcium homeostasis. Moreover, mRNA and protein level of the ER stress inducible C/EBP-homologous protein (CHOP), Tribbles homolog 3 (Drosophila) (TRIB3) and CCAAT/enhancer binding protein beta (C/EBPβ) were enhanced, and the C/EBPβ LIP/LAP ratio was significantly increased. These results indicate prolonged ER stress and a possible link to induction of cell death.
CONCLUSION: We find that TTA-induced growth inhibition of SW620 cells seems to be mediated through induction of ER stress and activation of the UPR pathway.

Wang Q, Qiu H, Jiang H, et al.
Mutations of PHF6 are associated with mutations of NOTCH1, JAK1 and rearrangement of SET-NUP214 in T-cell acute lymphoblastic leukemia.
Haematologica. 2011; 96(12):1808-14 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

BACKGROUND: Mutations in the PHF6 gene were recently described in patients with T-cell acute lymphoblastic leukemia and in those with acute myeloid leukemia. The present study was designed to determine the prevalence of PHF6 gene alterations in T-cell acute lymphoblastic leukemia.
DESIGN AND METHODS: We analyzed the incidence and prognostic value of PHF6 mutations in 96 Chinese patients with T-cell acute lymphoblastic leukemia. PHF6 deletions were screened by real-time quantitative polymerase chain reaction and array-based comparative genomic hybridization. Patients were also investigated for NOTCH1, FBXW7, WT1, and JAK1 mutations together with CALM-AF10, SET-NUP214, and SIL-TAL1 gene rearrangements.
RESULTS: PHF6 mutations were identified in 11/59 (18.6%) adult and 2/37 (5.4%) pediatric cases of T-cell acute lymphoblastic leukemia, these incidences being significantly lower than those recently reported. Although PHF6 is X-linked and mutations have been reported to occur almost exclusively in male patients, we found no sex difference in the incidences of PHF6 mutations in Chinese patients with T-cell acute lymphoblastic leukemia. PHF6 deletions were detected in 2/79 (2.5%) patients analyzed. NOTCH1 mutations, FBXW7 mutations, WT1 mutations, JAK1 mutations, SIL-TAL1 fusions, SET-NUP214 fusions and CALM-AF10 fusions were present in 44/96 (45.8%), 9/96 (9.4%), 4/96 (4.1%), 3/49 (6.1%), 9/48 (18.8%), 3/48 (6.3%) and 0/48 (0%) of patients, respectively. The molecular genetic markers most frequently associated with PHF6 mutations were NOTCH1 mutations (P=0.003), SET-NUP214 rearrangements (P=0.002), and JAK1 mutations (P=0.005). No differences in disease-free survival and overall survival between T-cell acute lymphoblastic leukemia patients with and without PHF6 mutations were observed in a short-term follow-up.
CONCLUSIONS: Overall, these results indicate that, in T-cell acute lymphoblastic leukemia, PHF6 mutations are a recurrent genetic abnormality associated with mutations of NOTCH1, JAK1 and rearrangement of SET-NUP214.

Related: NOTCH1 gene

Li H, Baldwin BR, Zahnow CA
LIP expression is regulated by IGF-1R signaling and participates in suppression of anoikis.
Mol Cancer. 2011; 10:100 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

BACKGROUND: The transcription factor, CCAAT enhancer binding protein-β (C/EBPβ), is expressed as several distinct protein isoforms (LAP1, LAP2 and LIP) that have opposing actions in cellular proliferation and differentiation. Increases in the ratio of LIP/LAP are associated with aggressive, metastatic breast cancer; however, little is known regarding the molecular mechanisms that regulate LIP expression or the biological actions of an increase in the LIP/LAP ratio. Metastasis is highly dependent upon the suppression of anoikis and the role of C/EBPβ and LIP in this anchorage-independent, survival process is currently not known in mammary epithelial cells. IGF-1R signaling is important for the survival of breast cancer cells and crosstalk between IGF-1R and EGFR signaling pathways have been implicated in the development of more aggressive disease. We therefore evaluated in mammary epithelial cells whether IGF-1R signaling regulates the LIP/LAP ratio, analyzed the potential interplay between EGFR and IGF-1R signaling and addressed the biological significance of increased LIP expression in cellular survival and suppression of anoikis.
RESULTS: Our data provide the first evidence that IGF-1R signaling regulates LIP expression in an EGFR independent manner to increase the LIP/LAP ratio in mammary epithelial cells. Although crosstalk between IGF-1R signaling and EGFR signaling is detectable in MCF10A cells, this crosstalk is not required for the IGF-1 mediated regulation of LIP expression. Rather, the critical regulator of IGF-1 induced LIP expression appears to be EGFR-independent, Akt activity. Our data also demonstrate that increases in LIP expression promote cell survival via suppression of anoikis. Likewise, knockdown of total C/EBPβ leads to increased cell death and suggest that C/EBPβ expression is important for survival and resistance to anoikis. IGF-1 treatment can partially rescue vector control cells from anoikis; however, cells with reduced C/EBPβ expression do not survive anoikis.
CONCLUSIONS: Taken together, our data demonstrate that IGF-1R signaling regulates LIP expression in an EGFR independent manner to increase the LIP/LAP ratio in mammary epithelial cells. C/EBPβ expression and elevations in LIP play an important role in regulating cellular survival via suppression of anoikis, in an IGF-1R mediated context or in a manner independent of IGF-1R signaling.

Related: Breast Cancer AKT1 Signal Transduction

Stoddart A, Tennant TR, Fernald AA, et al.
The clathrin-binding domain of CALM-AF10 alters the phenotype of myeloid neoplasms in mice.
Oncogene. 2012; 31(4):494-506 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

The PICALM (CALM) gene, whose product is involved in clathrin-mediated endocytosis, has been identified in two recurring chromosomal translocations, involving either MLL or MLLT10 (AF10). We developed a mouse model of CALM-AF10(+) leukemia to examine the hypothesis that disruption of endocytosis contributes to leukemogenesis. Exclusion of the C-terminal portion of CALM from the fusion protein, which is required for optimal binding to clathrin, resulted in the development of a myeloproliferative disease, whereas inclusion of this domain led to the development of acute myeloid leukemia and changes in gene expression of several cancer-related genes, notably Pim1 and Crebbp. Nonetheless, the development of leukemia could not be attributed directly to interference with endocytosis or consequential changes in proliferation and signaling. In leukemia cells, full-length CALM-AF10 localized to the nucleus with no consistent effect on growth factor endocyctosis, and suppressed histone H3 lysine 79 methylation regardless of the presence of clathrin. Using fluorescence resonance energy transfer analysis, we show that CALM-AF10 has a propensity to homo-oligomerize, raising the possibility that the function of endocytic proteins involved in chimeric fusions may be to provide dimerization properties, a recognized mechanism for unleashing oncogenic properties of chimeric transcription factors, rather than disrupting the internalization of growth factor receptors.

Related: Acute Myeloid Leukemia (AML)

Deshpande AJ, Rouhi A, Lin Y, et al.
The clathrin-binding domain of CALM and the OM-LZ domain of AF10 are sufficient to induce acute myeloid leukemia in mice.
Leukemia. 2011; 25(11):1718-27 [PubMed] Related Publications

The t(10;11)(p13-14;q14-21) translocation, giving rise to the CALM-AF10 fusion gene, is a recurrent chromosomal rearrangement observed in patients with poor prognosis acute myeloid leukemia (AML). Although splicing of the CALM-AF10 fusion transcripts has been described in AML patients, the contribution of different CALM and AF10 domains to in vivo leukemogenesis remains to be defined. We therefore performed detailed structure-function studies of the CALM-AF10 fusion protein. We demonstrate that fusion of the C-terminal 248 amino acids of CALM, which include the clathrin-binding domain, to the octapeptide motif-leucine-zipper (OM-LZ) domain of AF10 generated a fusion protein (termed CALM-AF10 minimal fusion (MF)), with strikingly enhanced transformation capabilities in colony assays, providing an efficient system for the expeditious assessment of CALM-AF10-mediated transformation. Leukemias induced by the CALM-AF10 (MF) mutant recapitulated multiple aspects of full-length CALM-AF10-induced leukemia, including aberrant Hoxa cluster upregulation, a characteristic molecular lesion of CALM-AF10 leukemias. In summary, this study indicates that collaboration of the clathrin-binding and the OM-LZ domains of CALM-AF10 is sufficient to induce AML. These findings further suggest that future approaches to antagonize CALM-AF10-induced transformation should incorporate strategies, which aim at blocking these key domains.

Related: Acute Myeloid Leukemia (AML)

Li LS, Bey EA, Dong Y, et al.
Modulating endogenous NQO1 levels identifies key regulatory mechanisms of action of β-lapachone for pancreatic cancer therapy.
Clin Cancer Res. 2011; 17(2):275-85 [PubMed] Related Publications

PURPOSE: Pancreatic cancer is the fourth leading cause of cancer-related deaths, in which the 5-year survival rate is less than 5%. Current standard of care therapies offer little selectivity and high toxicity. Novel, tumor-selective approaches are desperately needed. Although prior work suggested that β-lapachone (β-lap) could be used for the treatment of pancreatic cancers, the lack of knowledge of the compound's mechanism of action prevented optimal use of this agent.
EXPERIMENTAL DESIGN: We examined the role of NAD(P)H:quinone oxidoreductase-1 (NQO1) in β-lap-mediated antitumor activity, using a series of MIA PaCa-2 pancreatic cancer clones varying in NQO1 levels by stable shRNA knockdown. The antitumor efficacy of β-lap was determined using an optimal hydroxypropyl-β-cyclodextran (HPβ-CD) vehicle formulation in metastatic pancreatic cancer models.
RESULTS: β-Lap-mediated cell death required ∼90 enzymatic units of NQO1. Essential downstream mediators of lethality were as follows: (i) reactive oxygen species (ROS); (ii) single-strand DNA breaks induced by ROS; (iii) poly(ADP-ribose)polymerase-1 (PARP1) hyperactivation; (iv) dramatic NAD(+)/ATP depletion; and (v) programmed necrosis. We showed that 1 regimen of β-lap therapy (5 treatments every other day) efficaciously regressed and reduced human pancreatic tumor burden and dramatically extended the survival of athymic mice, using metastatic pancreatic cancer models.
CONCLUSIONS: Because NQO1 enzyme activities are easily measured and commonly overexpressed (i.e., >70%) in pancreatic cancers 5- to 10-fold above normal tissue, strategies using β-lap to efficaciously treat pancreatic cancers are indicated. On the basis of optimal drug formulation and efficacious antitumor efficacy, such a therapy should be extremely safe and not accompanied with normal tissue toxicity or hemolytic anemia.

Related: Cancer of the Pancreas Pancreatic Cancer

Saint-Auret G, Danan JL, Hiron M, et al.
Characterization of the transcriptional signature of C/EBPbeta isoforms (LAP/LIP) in Hep3B cells: implication of LIP in pro-survival functions.
J Hepatol. 2011; 54(6):1185-94 [PubMed] Related Publications

BACKGROUND & AIMS: C/EBPbeta is an important mediator of several cellular processes, such as differentiation, proliferation, and survival of hepatic cells. However, a complete catalog of the targets of C/EBPbeta or the mechanism by which this transcription factor regulates certain liver-dependent pathways has not been clearly determined. Two major natural isoforms of this transcription factor exist: the liver-enriched activating protein (LAP) and the liver-enriched inhibitory protein (LIP), a functional LAP antagonist. In this study, we used the opposing transcriptional effects driven by LAP and LIP to determine the genuine C/EBPbeta molecular signature in the Hep3B human hepatoma cell line. We subsequently investigated the role of each of the LAP and LIP isoforms in drug-induced Hep3B cell death.
METHODS: We engineered Hep3B cells with regulated LAP or LIP expression using the Tet-off expression system. The genes that showed inverse regulation by LAP and LIP were identified by cDNA array analysis. The cohort of direct-C/EBPbeta-targets was distinguished from indirect-targets by ChIP-on-chip analysis.
RESULTS: We characterized 676 genes by this approach. Among these genes, 39 are novel direct targets of C/EBPbeta. Eleven of these new direct targets are involved in cell survival, suggesting critical roles for LAP/LIP isoforms in this cellular process. Therefore, we examined the effects of LAP and LIP over-expression on cell survival. We show that LIP promotes survival in staurosporine- or taxol-induced Hep3B cell death.
CONCLUSIONS: Our study provides new molecular and cellular insights into the role of C/EBPbeta in cells of hepatic origin.

Related: Liver Cancer Paclitaxel

Arnal-Estapé A, Tarragona M, Morales M, et al.
HER2 silences tumor suppression in breast cancer cells by switching expression of C/EBPß isoforms.
Cancer Res. 2010; 70(23):9927-36 [PubMed] Related Publications

Tumor progression requires ablation of suppressor functions mediated by transforming growth factor β (TGFβ) signaling and by oncogene-induced senescence (OIS), but how these functions are canceled in specific subtypes of breast cancer remains unknown. In this study, we show that HER2-overexpressing breast cancer cells avert TGFβ- and OIS-mediated tumor suppression by switching expression of 2 functionally distinct isoforms of the transcription factor C/EBPβ, which has been implicated previously in breast cancer development. HER2 signaling activates the translational regulatory factor CUGBP1, which favors the production of the transcriptionally inhibitory isoform LIP over that of the active isoform LAP. LIP overexpression prevents the assembly of LAP/Smad transcriptional repressor complexes on the MYC promoter in response to TGFβ, and interferes with activation of OIS responses. Treatment of HER2-transformed mammary epithelial cells with the HER2 antibody trastuzumab reduces LIP levels, restoring these suppressor responses. Our findings reveal a novel mechanism through which HER2 silences tumor suppression in a concerted manner, contributing to the potency of this oncogene in breast cancer.

Related: Monoclonal Antibodies Breast Cancer FISH AKT1 Trastuzumab (Herceptin)

Savage NM, Kota V, Manaloor EJ, et al.
Acute leukemia with PICALM-MLLT10 fusion gene: diagnostic and treatment struggle.
Cancer Genet Cytogenet. 2010; 202(2):129-32 [PubMed] Related Publications

Patients with various hematologic malignancies, including acute lymphoblastic leukemia (ALL), acute myeloblastic leukemia (AML), diffuse histiocytic lymphoma, and granulocytic sarcoma, have sometimes been shown to carry the PICALM-MLLT10 fusion gene (alias CALM-AF10) by various cytogenetic methodologies. Cases with the PICALM-MLLT10 fusion gene can involve a diagnostic dilemma for the following reasons: (1) the fusion gene occurs very rarely, (2) the cases do not have a distinct myeloid or lymphoid morphology and cells often appear immature, (3) cases usually have a mixed T-cell and myeloid phenotype, and (4) cases often have a mixed clinical presentation (e.g., mediastinal mass in a patient with AML). A 27-year-old woman was diagnosed with AML with the PICALM-MLLT10 fusion gene. The patient was treated on an AML regimen and achieved a complete remission. Although the reported treatment of these patients varies greatly, outcome remains very poor in the vast majority. Furthermore, central nervous system involvement at diagnosis and relapse are reported in pediatric populations. Routine acute leukemia fluorescence in situ hybridization panels do not include a probe for the PICALM-MLLT10 fusion gene, and therefore diagnosis can be made only when karyotyping is available; that delay can result in initial misdiagnosis and mistreatment. The case report and literature review here (including discussion of the poor prognosis and of management, including CNS prophylaxis) are intended to raise awareness and to inform about PICALM-MLLT10 in acute leukemia.

Related: FISH Acute Myeloid Leukemia (AML)

Schotte D, Lange-Turenhout EA, Stumpel DJ, et al.
Expression of miR-196b is not exclusively MLL-driven but is especially linked to activation of HOXA genes in pediatric acute lymphoblastic leukemia.
Haematologica. 2010; 95(10):1675-82 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

BACKGROUND: Deregulation of microRNA may contribute to hematopoietic malignancies. MicroRNA-196b (miR-196b) is highly expressed in MLL-rearranged leukemia and has been shown to be activated by MLL and MLL-fusion genes.
DESIGN AND METHODS: In order to determine whether high expression of miR-196b is restricted to MLL-rearranged leukemia, we used quantitative stem-loop reverse transcriptase polymerase chain reaction to measure the expression of this microRNA in 72 selected cases of pediatric acute lymphoblastic leukemia i.e. MLL-rearranged and non-MLL-rearranged precursor B-cell and T-cell acute lymphoblastic leukemias. We also determined the expression of HOXA-genes flanking miR-196 by microarray and real-time quantitative polymerase chain reaction. Furthermore, we used CpG island-arrays to explore the DNA methylation status of miR-196b and HOXA.
RESULTS: We demonstrated that high expression of miR-196b is not unique to MLL-rearranged acute lymphoblastic leukemia but also occurs in patients with T-cell acute lymphoblastic leukemia patients carrying CALM-AF10, SET-NUP214 and inversion of chromosome 7. Like MLL-rearrangements, these abnormalities have been functionally linked with up-regulation of HOXA. In correspondence, miR-196b expression in these patients correlated strongly with the levels of HOXA family genes (Spearman's correlation coefficient ≥ 0.7; P≤0.005). Since miR-196b is encoded on the HOXA cluster, these data suggest co-activation of miR-196b and HOXA genes in acute lymphoblastic leukemia. Up-regulation of miR-196b coincides with reduced DNA methylation at CpG islands in the promoter regions of miR-196b and the entire HOXA cluster in MLL-rearranged cases compared to in cases of non-MLL precursor B-cell acute lymphoblastic leukemia and normal bone marrow (P<0.05), suggesting an epigenetic origin for miR-196b over-expression. Although patients with MLL-rearranged acute lymphoblastic leukemia are highly resistant to prednisolone and L-asparaginase, this resistance was not attributed to miR-196b expression.
CONCLUSIONS: High expression of miR-196b is not exclusively MLL-driven but can also be found in other types of leukemia with aberrant activation of HOXA genes. Since miR-196b has been shown by others to exert oncogenic activity in bone marrow progenitor cells, the findings of the present study imply a potential role for miR-196b in the underlying biology of all HOXA-activated leukemias.

Related: Acute Lymphocytic Leukemia (ALL) Childhood Acute lymphoblastic leukaemia (ALL) ALL - Molecular Biology

Huh JY, Chung S, Oh D, et al.
Clathrin assembly lymphoid myeloid leukemia-AF10-positive acute leukemias: a report of 2 cases with a review of the literature.
Korean J Lab Med. 2010; 30(2):117-21 [PubMed] Related Publications

The translocation t(10;11)(p13;q14q21) has been found to be recurrent in acute lymphoblastic and myeloid leukemias, and results in the fusion of the clathrin assembly lymphoid myeloid leukemia (CALM) gene with the AF10 gene; these genes are present on chromosomes 11 and 10, respectively. Because the CALM-AF10 rearrangement is a rare chromosomal abnormality, it is not included in routine molecular tests for acute leukemia. Here, we describe the cases of 2 patients with the CALM-AF10 fusion gene. The first patient (case 1) was diagnosed with T-cell ALL, and the second patient (case 2) was diagnosed with AML. Both patient samples showed expression of the homeobox A gene cluster and the histone methyltransferase hDOT1L, which suggests that they mediate leukemic transformation in CALM-AF10-positive and mixed-lineage leukemia-AF10-positive leukemias. Both patients achieved complete remission after induction chemotherapy. The first patient (case 1) relapsed after double-unit cord blood transplantation; there was no evidence of relapse in the second patient (case 2) after allogenic peripheral blood stem cell transplantation. Since CALM-AF10- positive leukemias have been shown to have poor prognosis with conventional therapy, molecular tests for CALM-AF10 rearrangement would be necessary to detect minimal residual disease during follow-up.

Related: Chromosome 10 Chromosome 11 Acute Myeloid Leukemia (AML) MLLT10 gene

Dong GZ, Oh ET, Lee H, et al.
Beta-lapachone suppresses radiation-induced activation of nuclear factor-kappaB.
Exp Mol Med. 2010; 42(5):327-34 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

Anticancer effects of beta-lapachone (beta-lap) are due to generation of ROS and metabolic catastrophes as a result of NAD(P)H:quinone oxidoreductase (NQO1)-mediated futile cycling between the oxidized and reduced forms of beta-lap. It has been shown that NQO1 is also essential for the TNF-induced activation of NF-kappaB and that beta-lap suppresses the TNF-induced NF-kappaB activation. We investigated whether or not NQO1 is involved and beta-lap suppresses the radiation-induced NF-kappaB activation using A549 human lung cancer cells and NQO1-knock down A549 cells (shNQO1 A549 cells). Irradiation with 4 Gy markedly increased the DNA binding activity of NF-kappaB in A549 cells, but not in the shNQO1 A549 cells, thus demonstrating that NQO1 plays a pivotal role in irradiation-induced NF-kappaB activation. Treatment with 10 micronM beta-lap for 4 h almost completely abrogated the radiation-induced increase in NF-kappaB activation and the transcription of NF-kappaB target genes such as bcl2, gadd45beta and cyclinD1. Moreover, beta-lap markedly suppressed the activation of IkappaB kinase gamma (IKKgamma) and the subsequent phosphorylation of IkappaBalpha, thereby inhibiting NF-kappaB activation. It is concluded that beta-lap suppresses the radiation-induced activation of NF-kappaB by interrupting the involvement of NQO1 in the activation of NF-kappaB, thereby inhibiting the transcription of survival signals. The radiosensitization caused by beta-lap may, in part, be attributed to beta-lap-induced suppression of NF-kappaB activation.

Related: Lung Cancer

Gorello P, La Starza R, Varasano E, et al.
Combined interphase fluorescence in situ hybridization elucidates the genetic heterogeneity of T-cell acute lymphoblastic leukemia in adults.
Haematologica. 2010; 95(1):79-86 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

BACKGROUND: Molecular lesions in T-cell acute lymphoblastic leukemias affect regulators of cell cycle, proliferation, differentiation, survival and apoptosis in multi-step pathogenic pathways. Full genetic characterization is needed to identify events concurring in the development of these leukemias.
DESIGN AND METHODS: We designed a combined interphase fluorescence in situ hybridization strategy to study 25 oncogenes/tumor suppressor genes in T-cell acute lymphoblastic leukemias and applied it in 23 adult patients for whom immunophenotyping, karyotyping, molecular studies, and gene expression profiling data were available. The results were confirmed and integrated with those of multiplex-polymerase chain reaction analysis and gene expression profiling in another 129 adults with T-cell acute lymphoblastic leukemias.
RESULTS: The combined hybridization was abnormal in 21/23 patients (91%), and revealed multiple genomic changes in 13 (56%). It found abnormalities known to be associated with T-cell acute lymphoblastic leukemias, i.e. CDKN2A-B/9p21 and GRIK2/6q16 deletions, TCR and TLX3 rearrangements, SIL-TAL1, CALM-AF10, MLL-translocations, del(17)(q12)/NF1 and other cryptic genomic imbalances, i.e. 9q34, 11p, 12p, and 17q11 duplication, del(5)(q35), del(7)(q34), del(9)(q34), del(12)(p13), and del(14)(q11). It revealed new cytogenetic mechanisms for TCRB-driven oncogene activation and C-MYB duplication. In two cases with cryptic del(9)(q34), fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction detected the TAF_INUP214 fusion and gene expression profiling identified a signature characterized by HOXA and NUP214 upregulation and TAF_I, FNBP1, C9orf78, and USP20 down-regulation. Multiplex-polymerase chain reaction analysis and gene expression profiling of 129 further cases found five additional cases of TAF_I-NUP214-positive T-cell acute lymphoblastic leukemia.
CONCLUSIONS: Our combined interphase fluorescence in situ hybridization strategy greatly improved the detection of genetic abnormalities in adult T-cell acute lymphoblastic leukemias. It identified new tumor suppressor genes/oncogenes involved in leukemogenesis and highlighted concurrent involvement of genes. The estimated incidence of TAF_I-NUP214, a new recurrent fusion in adult T-cell acute lymphoblastic leukemias, was 4.6% (7/152).

Related: CGH FISH

Caudell D, Harper DP, Novak RL, et al.
Retroviral insertional mutagenesis identifies Zeb2 activation as a novel leukemogenic collaborating event in CALM-AF10 transgenic mice.
Blood. 2010; 115(6):1194-203 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

The t(10;11) translocation results in a CALM-AF10 fusion gene in a subset of leukemia patients. Expression of a CALM-AF10 transgene results in leukemia, with prolonged latency and incomplete penetrance, suggesting that additional events are necessary for leukemic transformation. CALM-AF10 mice infected with the MOL4070LTR retrovirus developed acute leukemia, and ligation-mediated polymerase chain reaction was used to identify retroviral insertions at 19 common insertion sites, including Zeb2, Nf1, Mn1, Evi1, Ift57, Mpl, Plag1, Kras, Erg, Vav1, and Gata1. A total of 26% (11 of 42) of the mice had retroviral integrations near Zeb2, a transcriptional corepressor leading to overexpression of the Zeb2-transcript. A total of 91% (10 of 11) of mice with Zeb2 insertions developed B-lineage acute lymphoblastic leukemia, suggesting that Zeb2 activation promotes the transformation of CALM-AF10 hematopoietic precursors toward B-lineage leukemias. More than half of the mice with Zeb2 integrations also had Nf1 integrations, suggesting cooperativity among CALM-AF10, Zeb2, and Ras pathway mutations. We searched for Nras, Kras, and Ptpn11 point mutations in the CALM-AF10 leukemic mice. Three mutations were identified, all of which occurred in mice with Zeb2 integrations, consistent with the hypothesis that Zeb2 and Ras pathway activation promotes B-lineage leukemic transformation in concert with CALM-AF10.

Related: Acute Lymphocytic Leukemia (ALL) Signal Transduction

Bandyopadhyay A, Raghavan S
Defining the role of integrin alphavbeta6 in cancer.
Curr Drug Targets. 2009; 10(7):645-52 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

Integrins are a large family of heterodimeric transmembrane receptors that mediate cell-substratum adhesion. alphavbeta6 is an epithelial-specific integrin that is a receptor for the extracellular matrix (ECM) proteins fibronectin, vitronectin, tenascin and the latency associated peptide (LAP) of TGF-beta. Integrin alphavbeta6 is not expressed in healthy adult epithelia but is upregulated during wound healing and in cancer. alphavbeta6 has been shown to modulate invasion, inhibit apoptosis, regulate the expression of matrix metalloproteases (MMPs) and activate TGF-beta1. There is increasing evidence, primarily from in vitro studies, that suggest that alphavbeta6 may actually promote carcinoma progression. In this review we summarize what has been learnt in the past few years about the role of alphavbeta6 in cancer progression.

Related: Cancer Prevention and Risk Reduction

Tritschler I, Gramatzki D, Capper D, et al.
Modulation of TGF-beta activity by latent TGF-beta-binding protein 1 in human malignant glioma cells.
Int J Cancer. 2009; 125(3):530-40 [PubMed] Related Publications

High biological activity of the transforming growth factor (TGF)-beta-Smad pathway characterizes the malignant phenotype of malignant gliomas and confers poor prognosis to glioma patients. Accordingly, TGF-beta has become a novel target for the experimental treatment of these tumors. TGF-beta is processed by furin-like proteases (FLP) and secreted from cells in a latent complex with its processed propeptide, the latency-associated peptide (LAP). Latent TGF-beta-binding protein 1 (LTBP-1) covalently binds to this small latent TGF-beta complex (SLC) and regulates its function, presumably via interaction with the extracellular matrix (ECM). We report here that the levels of LTBP-1 protein in vivo increase with the grade of malignancy in gliomas. LTBP-1 is associated with the ECM as well as secreted into the medium in cultured malignant glioma cells. The release of LTBP-1 into the medium is decreased by the inhibition of FLP activity. Gene-transfer mediated overexpression of LTBP-1 in glioma cell lines results in an increase inTGF-beta activity. Accordingly, Smad2 phosphorylation as an intracellular marker of TGF-beta activity is enhanced. Conversely, LTBP-1 gene silencing reduces TGF-beta activity and Smad2 phosphorylation without affecting TGF-beta protein levels. Collectively, we identify LTBP-1 as an important modulator of TGF-beta activation in glioma cells, which may contribute to the malignant phenotype of these tumors.

Related: Signal Transduction

Archangelo LF, Greif PA, Hölzel M, et al.
The CALM and CALM/AF10 interactor CATS is a marker for proliferation.
Mol Oncol. 2008; 2(4):356-67 [PubMed] Related Publications

The CATS protein was recently identified as a novel CALM interacting protein. CATS increases the nuclear and specifically the nucleolar localization of the leukemogenic CALM/AF10 fusion protein. We cloned and characterized the murine Cats gene. Detailed analysis of murine Cats expression during mouse embryogenesis showed an association with rapidly proliferating tissues. Interestingly, the Cats transcript is highly expressed in murine hematopoietic cells transformed by CALM/AF10. The CATS protein is highly expressed in leukemia, lymphoma and tumor cell lines but not in non-proliferating T-cells or human peripheral blood lymphocytes. CATS protein levels are cell cycle dependent and it is induced by mitogens, suggesting a role of CATS in the control of cell proliferation and possibly CALM/AF10-mediated leukemogenesis.

Related: Leukemia

Zahnow CA
CCAAT/enhancer-binding protein beta: its role in breast cancer and associations with receptor tyrosine kinases.
Expert Rev Mol Med. 2009; 11:e12 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

The CCAAT/enhancer-binding proteins (C/EBPs) are a family of leucine-zipper transcription factors that regulate gene expression to control cellular proliferation, differentiation, inflammation and metabolism. Encoded by an intronless gene, C/EBPbeta is expressed as several distinct protein isoforms (LAP1, LAP2, LIP) whose expression is regulated by the differential use of several in-frame translation start sites. LAP1 and LAP2 are transcriptional activators and are associated with differentiation, whereas LIP is frequently elevated in proliferative tissue and acts as a dominant-negative inhibitor of transcription. However, emerging evidence suggests that LIP can serve as a transcriptional activator in some cellular contexts, and that LAP1 and LAP2 might also have unique actions. The LIP:LAP ratio is crucial for the maintenance of normal growth and development, and increases in this ratio lead to aggressive forms of breast cancer. This review discusses the regulation of C/EBPbeta activity by post-translational modification, the individual actions of LAP1, LAP2 and LIP, and the functions and downstream targets that are unique to each isoform. The role of the C/EBPbeta isoforms in breast cancer is discussed and emphasis is placed on their interactions with receptor tyrosine kinases.

Related: Breast Cancer

Sebastian T, Johnson PF
RasV12-mediated down-regulation of CCAAT/enhancer binding protein beta in immortalized fibroblasts requires loss of p19Arf and facilitates bypass of oncogene-induced senescence.
Cancer Res. 2009; 69(6):2588-98 [PubMed] Article available free on PMC after 06/06/2014 Related Publications

The transcription factor CCAAT/enhancer binding protein beta (C/EBPbeta) is involved in cellular responses to oncogenic and physiologic Ras signals. C/EBPbeta is required for premature senescence of primary mouse fibroblasts induced by expression of H-Ras(V12), demonstrating its role in oncogene-induced senescence. Here, we have investigated the mechanisms by which Ras inhibits proliferation of normal cells but transforms immortalized cells. We show that oncogenic Ras down-regulates C/EBPbeta expression in NIH 3T3 cells, which are immortalized by a deletion of the CDKN2A locus and, therefore, lack the p16(Ink4a) and p19(Arf) tumor suppressors. Ras(V12)-induced silencing of C/EBPbeta occurred at the mRNA level and involved both the Raf-mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase-ERK and phosphatidylinositol 3-kinase signaling pathways. Oncogenic Ras decreased C/EBPbeta expression in Ink4a/Arf(-/-) mouse embryo fibroblasts (MEF) but increased C/EBPbeta levels in wild-type MEFs. C/EBPbeta down-regulation in NIH 3T3 cells was reversed by expression of p19(Arf), but not of p53 or p16(Ink4a), highlighting a critical role for p19(Arf) in sustaining C/EBPbeta levels. Ectopic expression of p34 C/EBPbeta (LAP) inhibited Ras(V12)-mediated transformation of NIH 3T3 cells, suppressed their tumorigenicity in nude mice, and reactivated expression of the proapoptotic Fas receptor, which is also down-regulated by Ras. Our findings indicate that Cebpb gene silencing eliminates a growth inhibitory transcription factor that would otherwise restrain oncogenesis. We propose that C/EBPbeta is part of a p53-independent, p19(Arf)-mediated network that enforces Ras-induced cell cycle arrest and tumor suppression in primary fibroblasts.

Related: TP53

Ignatova ID, Kostadinova RM, Goldring CE, et al.
Tumor necrosis factor-alpha upregulates 11beta-hydroxysteroid dehydrogenase type 1 expression by CCAAT/enhancer binding protein-beta in HepG2 cells.
Am J Physiol Endocrinol Metab. 2009; 296(2):E367-77 [PubMed] Related Publications

The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) catalyzes the conversion of inactive to active glucocorticoids. 11beta-HSD1 plays a crucial role in the pathogenesis of obesity and controls glucocorticoid actions in inflammation. Several studies have demonstrated that TNF-alpha increases 11beta-HSD1 mRNA and activity in various cell models. Here, we demonstrate that mRNA and activity of 11beta-HSD1 is increased in liver tissue from transgenic mice overexpressing TNF-alpha, indicating that this effect also occurs in vivo. To dissect the molecular mechanism of this increase, we investigated basal and TNF-alpha-induced transcription of the 11beta-HSD1 gene (HSD11B1) in HepG2 cells. We found that TNF-alpha acts via p38 MAPK pathway. Transient transfections with variable lengths of human HSD11B1 promoter revealed highest activity with or without TNF-alpha in the proximal promoter region (-180 to +74). Cotransfection with human CCAAT/enhancer binding protein-alpha (C/EBPalpha) and C/EBPbeta-LAP expression vectors activated the HSD11B1 promoter with the strongest effect within the same region. Gel shift and RNA interference assays revealed the involvement of mainly C/EBPalpha, but also C/EBPbeta, in basal and only of C/EBPbeta in the TNF-alpha-induced HSD11B1 expression. Chromatin immunoprecipitation assay confirmed in vivo the increased abundance of C/EBPbeta on the proximal HSD11B1 promoter upon TNF-alpha treatment. In conclusion, C/EBPalpha and C/EBPbeta control basal transcription, and TNF-alpha upregulates 11beta-HSD1, most likely by p38 MAPK-mediated increased binding of C/EBPbeta to the human HSD11B1 promoter. To our knowledge, this is the first study showing involvement of p38 MAPK in the TNF-alpha-mediated 11beta-HSD1 regulation, and that TNF-alpha stimulates enzyme activity in vivo.

Related: Liver Cancer TNF

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