Analysis of the expression pattern of the BCL11B gene and its relatives in patients with T-cell acute lymphoblastic leukemia

Abstract

Background: In a human T-cell acute lymphoblastic leukemia (T-ALL) cell line (Molt-4), siRNA-mediated suppression of BCL11B expression was shown to inhibit proliferation and induce apoptosis, functions which may be related to genes involved in apoptosis (such as TNFSF10 and BCL2L1) and TGF-β pathways (such as SPP1and CREBBP).

Methods: The expression levels of the above mentioned genes and their correlation with the BCL11B gene were analyzed in patients with T-ALL using the TaqMan and SYBR Green I real-time polymerase chain reaction technique.

Results: Expression levels of BCL11B, BCL2L1, and CREBBP mRNA in T-ALL patients were significantly higher than those from healthy controls (P<0.05). In T-ALL patients, the BCL11B expression level was negatively correlated with the BCL2L1 expression level (rs=-0.700; P<0.05), and positively correlated with the SPP1 expression level (rs=0.683; P<0.05). In healthy controls, the BCL11B expression level did not correlate with the TNFSF10, BCL2L1, SPP1, or CREBBP expression levels.

Conclusions: Over-expression of BCL11B might play a role in anti-apoptosis in T-ALL cells through up-regulation of its downstream genes BCL2L1 and CREBBP.

Figure 1

Expression levels of the BCL11B gene in PBMCs from T-ALL and healthy controls.

Figure 2

Features of the expression of TNFSF10, BCL2L1, SPP1, and CREBBP genes in T-ALL and healthy groups. A, B: Accurate standard curve graphs of BCL2L1 and the β2M control gene are shown using diluted Molt-4 cDNA as the template. The amplification efficiency of BCL2L1-related genes was more than 95%, and consistent with the high amplification efficiency of the β2M reference gene. C: Melting curves of the BCL2L1 and β2M genes from nine patients. #: Specific peak of the β2M reference gene begins at 81°C. ##: Specific peak of the BCL2L1 gene begins at 84°C. D: PCR products of the β2M gene by 2.5% agarose gel electrophoresis analysis. The size of the PCR products of the β2M gene used for the BCL11B reference is 332 bp (line 1, 2) and that used for the four genes of interest is 145 bp (line 4-11). Line 3: DNA ladder. E: PCR products analyzed by 2.5% agarose gel electrophoresis. Line 1-2: BCL11B (193bp), line 3: DNA ladder, line 4-5: BCL2L1 (202 bp), line 6-7: CREBBP (206 bp), line 8-9: SPP1 (241 bp), line 10-11: TNFSF10 (190 bp). F: Relative expression levels of the four genes of interest in T-ALL and healthy groups.

Figure 3

Linear correlation analyses of the BCL11B and BCL2L1 genes (A) and SPP1 gene (B) in T-ALL samples.

Figure 4

Schematic representation of the regulatory network of apoptosis in BCL11B and its related genes. (a) BCL2L1 is affected by the BCL11B gene in transcriptional regulation. (b, d) BCL11B and BCL2L1 participate in the same protein-protein interactions, along with competitive downstream target proteins. BCL2L1 (Bcl-xL) normally interferes with the mitochondrial programmed cell death pathway by sequestering proapoptotic proteins such as BCL2-associated × protein (BAX) and BCL2-antagonist/killer 1 (BAK1; BAK), suggesting that BAX/BAK may be competitive target proteins downstream of BCL11B. (c) The SPP1 gene may be a target of the BCL11B gene in transcriptional regulation: it plays a consistent role in anti-apoptotic effects with the BCL11B gene by decreasing mitochondrial cytochrome c release.