Open Access

Gene expression profiles in BCL11B-siRNA treated malignant T cells

  • Xin Huang1, 2,
  • Qi Shen1,
  • Si Chen1,
  • Shaohua Chen1,
  • Lijian Yang1,
  • Jianyu Weng2,
  • Xin Du2,
  • Piotr Grabarczyk3,
  • Grzegorz K Przybylski3, 4,
  • Christian A Schmidt3 and
  • Yangqiu Li1, 5Email author
Contributed equally
Journal of Hematology & Oncology20114:23

DOI: 10.1186/1756-8722-4-23

Received: 21 March 2011

Accepted: 15 May 2011

Published: 15 May 2011

Abstract

Background

Downregulation of the B-cell chronic lymphocytic leukemia (CLL)/lymphoma11B (BCL11B) gene by small interfering RNA (siRNA) leads to growth inhibition and apoptosis of the human T-cell acute lymphoblastic leukemia (T-ALL) cell line Molt-4. To further characterize the molecular mechanism, a global gene expression profile of BCL11B-siRNA -treated Molt-4 cells was established. The expression profiles of several genes were further validated in the BCL11B-siRNA -treated Molt-4 cells and primary T-ALL cells.

Results

142 genes were found to be upregulated and 109 genes downregulated in the BCL11B-siRNA -treated Molt-4 cells by microarray analysis. Among apoptosis-related genes, three pro-apoptotic genes, TNFSF 10, BIK, BNIP 3, were upregulated and one anti-apoptotic gene, BCL2L 1 was downregulated. Moreover, the expression of SPP 1 and CREBBP genes involved in the transforming growth factor (TGF-β) pathway was down 16-fold. Expression levels of TNFSF 10, BCL2L 1, SPP 1, and CREBBP were also examined by real-time PCR. A similar expression pattern of TNFSF 10, BCL2L 1, and SPP 1 was identified. However, CREBBP was not downregulated in the BLC11B-siRNA -treated Molt-4 cells.

Conclusion

BCL11B-siRNA treatment altered expression profiles of TNFSF 10, BCL2L 1, and SPP 1 in both Molt-4 T cell line and primary T-ALL cells.

Background

Although treatment outcome in patients with T-cell acute lymphoblastic leukemia (T-ALL) has improved in recent years, relapsed T-ALL remains a challenge [1]. Monoclonal antibodies, gene inhibitors, and upregulation of microRNAs [2, 3] are promising tools for cancer targeted therapy. However, few targeted therapies are available for T-cell malignancies. For example, transforming Mer signals may contribute to T-cell leukemogenesis, and regulation of Mer expression could be a novel therapeutic target for pediatric ALL therapy [4]. The recent identification of activating Notch1 mutations in the majority of patients with T-ALL has brought interests on targeting the Notch signaling pathway for this disease [5].

The B-cell chronic lymphocytic leukemia (CLL)/lymphoma 11B (BCL11B) gene was first identified on human chromosome 14q32.2 [6] and encodes a Krüppel-like C2H2 zinc finger protein initially identified as a transcriptional repressor [7]. BCL11B plays an important role in T-cell differentiation and proliferation [811]. Altered expression, mutation, disruption, or rearrangement of BCL11B has been associated with T-cell malignancies [1214]. In humans, BCL11B overexpression is found primarily in lymphoproliferative disorders, such as T-ALL and adult T-cell leukemia/lymphoma [12, 1517]. BCL11B mediates transcriptional activation by interacting with the p300 co-activator at the upstream site 1 (US1) of the interleukin (IL)-2 promoter, leading to transcriptional activation of IL-2 expression in activated T cells [18]. Although the interaction partners and binding sequence have been revealed, only a few BCL11B direct target genes have been identified to date. Our previous study in the human T-ALL cell lines Molt-4, Jurkat, and hut78 has shown increased apoptosis upon BCL11B suppression by RNA interference [19].

In the present study, we further analyzed the global gene expression profiles in Molt-4 and primary T -ALL cells after BCL11B-935-siRNA treatment.

Methods

Samples

Samples from three newly diagnosed patients with T-ALL and one patient with T-cell lymphoma/leukemia were obtained after informed consent. The diagnosis of T-ALL was based on cytomorphology, immunohistochemistry, and flowcytometry analyses. The samples were named P1 (55-year-old male with T-ALL), P2 (6-year-old male with T-ALL), P3 (55-year-old female with T-cell lymphoma/leukemia), and P4 (19-year-old male with T-ALL). Peripheral blood was collected with heparin and peripheral mononuclear cells (PBMCs; contained more than 70% leukemic T cells) were separated using the Ficoll-Hypaque gradient centrifugation method. All procedures were conducted in strict accordance with the guidelines of the Medical Ethics committees of the Health Bureau of Guangdong province, China.

Cell culture

Molt-4 cells (Institutes for Biological Sciences Cell Resource Center, Chinese Academy of Sciences, Shanghai, China) and PBMCs collected from the four patients were cultured in complete RPMI 1640 medium with 15% fetal calf serum and were maintained in a sterile incubator at 37°C, 95% humidity, and 5% CO2.

Nucleofection

BCL11B-siRNA935 (Chinese patent application number: 200910193248.3) and the scrambled non-silencing siRNA control (BCL11B-sc) were designed with online software http://www.invitrogen.com and synthesized by Invitrogen (Carlsbad, CA, USA).

Malignant T cells were resuspended at 2.5 × 106 (Molt-4 cells) or 1 × 107 (PBMCs) per 100 μL of the appropriate Nucleofector kit solution (Amaxa Biosystems, Cologne, Germany), and were nucleofected with 3 μg of BCL11B-siRNA or control non-silencing scrambled (sc) RNA using the C-005 (Molt-4 cells) or U-014 (PBMCs) program in the Nucleofection Device II (Amaxa Biosystems). Mock-transfected cells (nucleofected without siRNA) were used as a negative control. After nucleofection, the cells were immediately mixed with 500 μL of pre-warmed culture medium and transferred to culture plates for incubation. Samples were collected for RNA isolation.

RNA isolation, expression profiling, reverse transcription, and real-time PCR

Total RNA was isolated using Trizol (Invitrogen), and cDNA was synthesized with a Superscript II RNaseH Reverse Transcriptase kit (Invitrogen).

Total RNA (> 3 μg) was sent for global gene expression profile analysis using an Affymetrix HG U133 Plus 2.0 gene chip (Shanghai Biochip Co., Ltd., Shanghai, China). The Affymetrix microarray analysis was performed using Gene Spring GX10.0 software (Agilent Technologies, Santa Clara, CA, USA).

The primer and probe information for BCL11B and the reference gene β-2-microglobulin (β2-MG), as well as the details of the real-time PCR for BCL11B were described in our previous studies [12, 15]. Expression levels of tumor necrosis factor (ligand) superfamily, member 10 (TNFSF 10; TRAIL), BCL 2-like 1 (BCL2L 1; Bcl-xL), secreted phosphoprotein 1 (SPP 1), cAMP-response element binding protein (CREBBP), and β2-MG were determined by real-time PCR using a SYBR Green I qPCR Master Mix kit [15].

Flow cytometry assay

Cells from different groups were prepared according to the protocols, and the BCL2 expression level was measured by flow cytometry (Beckman Coulter, Fullerton, CA, USA). Mouse anti-human BCL2-PE and mouse IgG1-PE (eBioscience, San Diego, CA, USA) were used. Results were analyzed using the Win MDI 2.9 software.

Results and discussion

Global gene expression profile in BCL11B-siRNA935 treated Molt-4 cells

To determine the molecular mechanisms of BCL11B siRNA-mediated cell apoptosis, global gene expression profiling was performed at 24 h post-transfection, when BCL11B mRNA was most effectively suppressed (data not shown). Results were clustered, based on the differential expression level (2-fold up or down), and visualized using a color scale (Figure 1A). Principal component analysis indicated that the changes in the Molt-4 cell gene expression profile could be accounted for primarily by the BCL11B siRNA935 treatment (Figure 1B). A GCOS1.4 software analysis showed that upregulated genes were identified by 142 probe sets, whereas 109 genes were downregulated at least 2-fold, compared with the sc control (Figure 1C). Changes in genes of the same signaling pathways closely related to tumor cell proliferation and apoptosis were analyzed further (Figure 1D).
Figure 1

Results of the gene chip microarray analysis and validation. (A) Visual display of the cluster analysis for the BCL11B siRNA935-transfected and control cells. (B) Principal component analysis. The closer the dots, the more similar the gene expression profiles are; the farther apart the dots, the greater the differences are. (C) Two-dimensional scatterplot analysis of gene expression values for all genes on the BCL11B siRNA935-transfected cells and control cells from the microarray. Yellow dots represent genes absent from both samples; blue dots represent genes present in one sample but absent from the other sample; and red dots represent genes present in both samples. Dots outside the 2 × difference lines, indicated by black arrows, represent differentially expressed genes. The farther from the line, the greater the difference in gene expression are. (D) Analysis of pathways closely related to tumor cell proliferation and apoptosis. Results are shown as fold-change in mRNA transcripts. Genes indicated with a red star are in the apoptosis pathway; genes indicated with a blue star are in the transforming growth factor-β pathway. (E) Gene validation by real-time PCR. Changes in TNFSF 10, BCL2L 1, and SPP 1 expression levels agreed with the microarray results, while those of CREBBP did not. (F) Reduced BCL-2 protein expression was confirmed by flow cytometry. BCL-2 expression in BCL11B siRNA3-transfected cells was significantly lower, at 46% of that in SC (99.1%), MOCK (99.2%), and NC cells (99.7%).

Among apoptosis-related genes, changes in expression levels occurred mainly in three pro-apoptotic genes; TNFSF 10, BCL-2 interacting killer (BIK), and BCL-2/E1B 19 kDa interacting protein 3 (BNIP 3), which were upregulated 2-4 fold, and one anti-apoptotic gene (BCL2L 1) was downregulated by 3-4 fold. The expression levels of SPP 1 and CREBBP genes involved in the transforming growth factor (TGF-β) pathway were down by 16 fold. The changes in the expression levels of the TNFSF10, BCL2L 1, SPP 1, and CREBBP genes were further detected by real-time PCR (Figure 1E). The BH3-only domain proteins BIK and BNIP3, which were located upstream of BCL-2 (Figure 2), may enhance their binding to BCL-2, thereby inhibiting the anti-apoptotic function. Thus, we analyzed the BCL-2 protein expression level by flow cytometry in Molt-4 cells at 72 h after BCL11B-siRNA treatment (Figure 1F). A similar altered expression pattern of these genes, as well as expression of the BCL-2 protein, was confirmed. However, CREBBP did not show downregulation in BCL11B-siRNA treated Molt-4 cells.
Figure 2

Schematic model of the molecular mechanism of BCL11B -siRNA-mediated apoptosis in Molt-4 cell [modified from reference 20].

The global gene expression profile results suggest that the molecular mechanisms of BCL11B siRNA-mediated cell death may involve BCL-2 family genes in the intrinsic mitochondrial pathway as well as the TNFSF 10 gene in the death receptor signaling pathway (Figure 2) [20]. Upregulation of the TNFSF 10 gene activated the death receptor signaling pathway, whereas upregulation of the two mitochondrial BCL-2 family genes (the BH3-only domain proteins BIK and BNIP 3) enhanced their binding to BCL-2, with a reduction in the anti-apoptotic gene BCL2L 1, thereby inhibiting the anti-apoptotic function and promoting Bax and Bak activation. This in turn activates the downstream caspases 3, 6, and 7, leading to increased apoptosis. Reduced expression of SPP 1 correlated with increased apoptosis in Molt-4 cells, suggesting that the SPP 1 gene may be a BCL11B gene target.

CREBBP overexpression has been detected in Jurkat cells [21]. However, previous studies have not reported a change in CREBBP expression in T cell lines after BCL11B-siRNA treatment. In the present study, downregulation of CREBBP was identified in the microarray analysis, but not confirmed by real-time PCR analysis. The reason may be due to a systemic error on the microarray analysis. Interestingly, unlike the result from Molt-4 cells, the alteration of the CREBBP expression level in primary T-All cells after BCL11B-siRNA treatment was in accordance with the results from the microarray analysis (Figure 3). Thus, the role of CREBBP during BCL11B downregulation in malignant T cells requires further investigation.
Figure 3

Expression of TNFSF 10, BCL2L 1, SPP 1, and CREBBP genes in peripheral mononuclear cells from four patients (P1-P4) with T-cell acute lymphoblastic leukemia at 24 h after BCL11B siRNA transfection.

Expression of TNFSF 10, BCL2L 1, SPP 1, and CREBBP genes in BCL11B-siRNA935-treated primary leukemic T cells

After obtaining interesting data from Molt-4 cells, we analyzed the effect of the BCL11B-siRNA in primary T-ALL cells. We examined the expression levels of TNFSF 10, BCL2L 1, SPP 1, and CREBBP in primary leukemic T cells after BCL11B siRNA935 treatment. BCL11B expression level decreased in primary leukemic T cells treated with BCL11B siRNA935 (282.77 ± 247.57 copies/105 β2-MG) as compared with the sc control group (519.48 ± 303.41 copies/105 β2-MG). The TNFSF 10, BCL2L 1, SPP 1, and CREBBP expression levels in BCL11B-siRNA935- treated primary leukemic T cells were 2.7 ± 2.17%, 9.53 ± 15.34%, 3.5 ± 2.95%, and 4.25 ± 5.82%, respectively, whereas the expression levels in primary leukemic T cells in the sc control group were 1.77 ± 1.93%, 6.96 ± 9.88%, 10.23 ± 13.09%, and 4.98 ± 7.2%, respectively. The T-ALL specimen number was too small to perform statistical analysis. The changes in the mRNA levels of TNFSF 10, SPP 1, and CREBBP in the T cells from the four patients agreed in general with those from the microarray analysis results (Figure 3A, C, D). However, the changes in the BCL2L 1 expression levels in the different samples varied (Figure 3B). The reduced BCL2L 1 expression rates in leukemic T cells from patients 1 and 3 were 31.84% and 13.73%, respectively, compared with the sc controls, whereas BCL2L 1 expression in leukemic T cells from patients 2 and 4 was upregulated. Although BCL11B gene overexpression occurred in all samples, it may have been due to the heterogeneity of T-cell malignancies during apoptosis induced by BCL11B downregulation [22], so it remains to be determined whether apoptosis induced by BCL11B downregulation in some cases with T-ALL involves the BCL-2 family genes in the intrinsic mitochondrial pathway.

A previous analysis revealed that overexpression of the BCL11B, BCL2L 1, and CREBBP genes in primary T-ALL samples blocks apoptosis in malignant T cells [15]. This study suggests that inhibition of BCL11B may trigger apoptosis in leukemic T cells by downregulating the downstream genes SPP 1, CREBBP, and TNFSF 10.

Conclusions

Our findings provide evidence that BCL11 B siRNA-mediated cell apoptosis may be related to the mitochondrial pathway BCL-2 family genes and the TNFSF 10 gene of the death receptor signaling pathway. Moreover, the SPP 1 and CREBBP genes in the TGF-β pathway may also be involved in BCL11B siRNA-mediated cell apoptosis.

Notes

Declarations

Acknowledgements

The authors thank Dr. Xuesong Yang for critical reading of this manuscript, and thank Dr. Xuchao Zhang from the Cancer Center of Guangdong Provincial Hospital for helpful analysis of the gene-chip data. This work was supported by Grants from National Natural Science Foundation of China (no. 30771980) and the Guangdong Science & Technology Project (no. 2007B030703008; and 2009B050700029).

Authors’ Affiliations

(1)
Institute of Hematology, Medical College, Jinan University
(2)
Department of Hematology, Guangdong General Hospital (Guangdong Academy of Medical Sciences)
(3)
Department of Hematology and Oncology, Ernst-Moritz-Arndt University Greifswald
(4)
Institute of Human Genetics, Polish Academy of Sciences
(5)
Key Laboratory for Regenerative Medicine of Ministry of Education, Jinan University

References

  1. Aifantis I, Raetz E, Buonamici S: Molecular pathogenesis of T-cell leukaemia and lymphoma. Nat Rev Immunol. 2008, 8: 380-390. 10.1038/nri2304.View ArticlePubMedGoogle Scholar
  2. Budhu BA, Ji JF, Wang XW: The clinical potential of microRNAs. J Hematol Oncol. 2010, 3: 37-10.1186/1756-8722-3-37.PubMed CentralView ArticlePubMedGoogle Scholar
  3. Wei GQ, Rafiyath S, Liu DL: First-line treatment for chronic myeloid leukemia:dasatinib, nilotinib, or imatinib. J Hematol Oncol. 2010, 3: 47-10.1186/1756-8722-3-47.PubMed CentralView ArticlePubMedGoogle Scholar
  4. Graham DK, Salzberg DB, Kurtzberg J: Ectopic expression of the proto-oncogene Mer in pediatric T-cell acute lymphoblastic leukemia. Clin Cancer Res. 2006, 12: 2662-2669. 10.1158/1078-0432.CCR-05-2208.View ArticlePubMedGoogle Scholar
  5. Palomero T, Ferrando A: Therapeutic targeting of NOTCH1 signaling in T-ALL. Clin Lymphoma Myeloma. 2009, 9 (Suppl 3): S205-PubMed CentralView ArticlePubMedGoogle Scholar
  6. Satterwhite E, Sonoki T, Willis TG, Harder L, Nowak R, Arriola EL, Liu H, Price HP, Gesk S, Steinemann D, Schlegelberger B, Oscier DG, Siebert R, Tucker PW, Dyer MJ: The BCL11 gene family: involvement of BCL11A in lymphoid malignancies. Blood. 2001, 98: 3413-3420. 10.1182/blood.V98.12.3413.View ArticlePubMedGoogle Scholar
  7. Avram D, Fields A, Senawong T, Topark-Ngarm A, Leid M: COUP-TF (chicken ovalbumin upstream promoter transcription factor)-interacting protein 1 (CTIP1) is a sequence-specific DNA binding protein. Biochem J. 2002, 368: 555-563. 10.1042/BJ20020496.PubMed CentralView ArticlePubMedGoogle Scholar
  8. Li L, Leid M, Rothenberg EV: An Early T cell lineage commitment checkpoint dependent on the transcription factor Bcl11b. Science. 2010, 329: 89-93. 10.1126/science.1188989.PubMed CentralView ArticlePubMedGoogle Scholar
  9. Wakabayashi Y, Watanabe H, Inoue J, Takeda N, Sakata J, Takeda N, Sakata J, Mishima Y, Hitomi J, Yamamoto T, Utsuyama M, Niwa O, Aizawa S, Kominami R: Bcl11b is required for differentiation and survival of αβ T lymphocytes. Nat Immunol. 2003, 4: 533-539. 10.1038/ni927.View ArticlePubMedGoogle Scholar
  10. Cismasiu VB, Ghanta S, Duque J, Albu D, Chen HM, Kasturi R: BCL11B participates in the activation of interleukin-2 gene expression in CD4+ T lymphocytes. Blood. 2006, 108: 2695-2702. 10.1182/blood-2006-05-021790.PubMed CentralView ArticlePubMedGoogle Scholar
  11. Liu P, Li P, Burke S: Critical roles of Bcl11b in T-cell development and maintenance of T-cell identity. Immunol Rev. 2010, 238: 138-149. 10.1111/j.1600-065X.2010.00953.x.View ArticlePubMedGoogle Scholar
  12. Przybylski GK, Dik WA, Wanzeck J, Grabarczyk P, Majunke S, Martin-Subero JI, Siebert R, Dölken G, Ludwig WD, Verhaaf B, van Dongen JJ, Schmidt CA, Langerak AW: Disruption of the BCL11B gene through inv 14 q11.2q32.31 results in the expression of BCL11B-TRDC fusion transcripts and is associated with the absence of wild-type BCL11B transcripts in T-ALL. Leukemia. 2005, 19: 201-208. 10.1038/sj.leu.2403619.View ArticlePubMedGoogle Scholar
  13. Karlsson A, Nordigården A, Jönsson JI, Söderkvist P: Bcl11b mutations identified in murine lymphomas increase the proliferation rate of hematopoietic progenitor cells. BMC Cancer. 2007, 7: 195-10.1186/1471-2407-7-195.PubMed CentralView ArticlePubMedGoogle Scholar
  14. Su XY, Della-Valle V, Andre-Schmutz I, Lemercier C, Radford-Weiss I, Ballerini P, Lessard M, Lafage-Pochitaloff M, Mugneret F, Berger R, Romana SP, Bernard OA, Penard-Lacronique V: HOX11L2/TLX3 is transcriptionally activated through T-cell regulatory elements downstream of BCL11B as a result of the t(5;14) (q35;q32). Blood. 2006, 108: 4198-4201. 10.1182/blood-2006-07-032953.View ArticlePubMedGoogle Scholar
  15. Huang X, Chen S, Shen Q, Yang LJ, Li B, Zhong LY, Geng SX, Du X, Li YQ: Analysis of the expression pattern of the BCL11B gene and its relatives in patients with T-cell acute lymphoblastic leukemia. J Hematol Oncol. 2010, 3: 44-10.1186/1756-8722-3-44.PubMed CentralView ArticlePubMedGoogle Scholar
  16. Nagel S, Kaufmann M, Drexler HG, MacLeod RA: The cardiac homeobox gene NKX2-5 is deregulated by juxtaposition with BCL11B in pediatric T-ALL cell lines via a novel t(5;14)(q35.1;q32.2). Cancer Res. 2003, 63: 5329-5334.PubMedGoogle Scholar
  17. Oshiro A, Tagawa H, Ohshima K, Karube K, Uike N, Tashiro Y, Utsunomiya A, Masuda M, Takasu N, Nakamura S, Morishima Y, Seto M: Identification of subtype-specific genomic alterations in aggressive adult T-cell leukemia/lymphoma. Blood. 2006, 107: 4500-4507. 10.1182/blood-2005-09-3801.View ArticlePubMedGoogle Scholar
  18. Cismasiu VB, Ghanta S, Duque J, Albu DI, Chen HM: BCL11B participates in the activation of IL2 gene expression in CD4+ T lymphocytes. Blood. 2006, 108: 2695-2702. 10.1182/blood-2006-05-021790.PubMed CentralView ArticlePubMedGoogle Scholar
  19. Huang X, Chen S, Chen SH, Yang LJ, Shen Q, Grabarczyk P, Przybylski GK, Schmidt CA, Li YQ: Inhibition of BCL11B expression leads to apoptosis of malignant T cell lines but not CD34+ cells [abstract]. Blood. 2010, 116: 1539-10.1182/blood-2009-06-230474.View ArticleGoogle Scholar
  20. Adams JM, Cory S: The Bcl-2 apoptotic switch in cancer development and therapy Bcl-2 apoptotic switch in cancer. Oncogene. 2007, 26: 1324-1337. 10.1038/sj.onc.1210220.PubMed CentralView ArticlePubMedGoogle Scholar
  21. Caravatta L, Sancilio S, di Giacomo V, Rana R, Cataldi A, Di Pietro R: PI3-K/Akt-dependent activation of cAMP-response element-binding (CREB) protein in Jurkat T leukemia cells treated with TRAIL. J Cell Physiol. 2008, 214: 192-200. 10.1002/jcp.21186.View ArticlePubMedGoogle Scholar
  22. Onciu M, Lai R, Vega F, Bueso-Ramos C, Medeiros LJ: Precursor T-cell acute lymphoblastic leukemia in adults: age-related immunophenotypic, cytogenetic, and molecular subsets. Am J Clin Pathol. 2002, 117: 252-258. 10.1309/08DJ-GPBH-H0VR-RC6F.View ArticlePubMedGoogle Scholar

Copyright

© Huang et al; licensee BioMed Central Ltd. 2011

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Advertisement