Inhibition of BCL11B expression leads to apoptosis of malignant but not normal mature T cells

The B-cell chronic lymphocytic leukemia (CLL)/lymphoma 11B gene (BCL11B) encodes a Krüppel-like zinc-finger protein, which plays a crucial role in thymopoiesis and has been associated with hematopoietic malignancies. It was hypothesized that BCL11B may act as a tumor-suppressor gene, but its precise function has not yet been elucidated. Here, we demonstrate that the survival of human T-cell leukemia and lymphoma cell lines is critically dependent on Bcl11b. Suppression of Bcl11b by RNA interference selectively induced apoptosis in transformed T cells whereas normal mature T cells remained unaffected. The apoptosis was effected by simultaneous activation of death receptor-mediated and intrinsic apoptotic pathways, most likely as a result of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) upregulation and suppression of the Bcl-xL antiapoptotic protein. Our data indicate an antiapoptotic function of Bcl11b. The resistance of normal mature T lymphocytes to Bcl11b suppression-induced apoptosis and restricted expression pattern make it an attractive therapeutic target in T-cell malignancies.     

In vitro functional studies of mononuclear cells in patients with CLL: evidence for functionally normal T lymphocytes and monocytes and abnormal B lymphocytes.

In vitro functional studies of mononuclear cells from 34 patients with B-cell type CLL were investigated and the results of these studies were as follows: 1) The T lymphocytes from patients with CLL were capable of responding normally to PHA or PWM, of inducing allogeneic normal B lymphocytes to respond to these mitogens and of stimulating normally to allogeneic lymphocytes in "one-way" mixed lymphocyte reaction; 2) The monocytes from these patients were capable of enhancing the T lymphocyte response to mitogens and of stimulating normally to allogeneic lymphocytes; and 3) The leukemic B lymphocytes were incapable of responding to mitogens even in the presence of normal T lymphocytes and their enhancer cell activity on T lymphocyte response or their stimulating capacity on allogeneic lymphocytes was depressed. These observations suggest that the T lymphocytes and monocytes from patients with CLL are functionally normal while the leukemic B lymphocytes from these patients are functionally abnormal.     

B lymphocytes repress hepatic tumorigenesis but not development in Hras12V transgenic mice

Increasing reports show noninflammation underlying HCC, challenging our understanding of the roles of the immune system in hepatocarcinogenesis. By exploring a mouse model of hepatic tumor induced by hepatocyte‐specific expression of the Hras12V oncogene without obvious inflammation, we found that the proportion of B cells, but not T cells, progressively and significantly decreased in 3, 5‐month‐old transgenic mice (Tg) compared with non‐transgenic mice. Notably, the proportions of total and activated B and T cells all significantly decreased in 9‐month‐old Tg with multiple massive hepatic tumors. Together with the decreased B cell proportion, serum IgG1/2 also significantly decreased in 5, 9‐month‐old Tg. Interestingly, homozygous Tg showed significantly higher B cell proportion and IgG2 levels, accompanied by significantly lower incidences of liver nodules but not adenomas and carcinomas compared with heterozygous Tg. Treatment of Tg with PCI‐32765, a potent Bruton's tyrosine kinase (BTK) inhibitor for suppressing B cell proliferation and activation, significantly decreased the B cell proportion and IgG2 levels, accompanied by a significantly higher incidence of liver nodules, but had no effects on adenoma and carcinoma. Treatment of Tg with insulin‐like growth factor 1 (IGF‐1) significantly increased the B cell proportion and IgG2 levels, accompanied by a significantly lower incidence of liver nodules and carcinoma, but had no effects on adenoma. Conclusively, B cells and IgG2 may play important roles in suppressing hepatic tumorigenesis, but not development. In addition, hepatocyte‐specific expression of the ras oncogene may play roles in suppressing B cells, while developed hepatic tumors suppress both B and T cells.     

T and B lymphocytes in alpha-chain disease.

The patients studied were diagnosed as suffering from alpha-chain disease by their clinicopathological features, malabsorption findings, X-ray, and presence of abnormal alpha-chain protein in their serum. The objective of the study was to determine any possible defect of the immune system in such patients. The rosette technique and surface immunofluorescence were used to enumerate the circulating T and B lymphocytes in these patients. They were also skin-tested with tuberculin and given sensitizing doses of dinitrochlorobenzene. Their serum immunoglobulins were also quantitated. It was found that the proportion of circulating B lymphocytes was much higher than normal, whereas that of T lymphocytes was lower than normal. Furthermore, they could not be sensitized to DNCB and their skin test to tuberculin was negative. It was concluded that the disease was a B-cell disease of IgA type, associated with low level of cellular immunity.     

Drug targeting of the c-MYC promoter to repress gene expression via a G-quadruplex silencer element

In this review, we describe the evidence for a parallel-stranded G-quadruplex in the purine-rich strand of the nuclease hypersensitivity element III(1) (NHE III(1)) of the promoter of c-MYC upstream of the P1 and P2 promoters. This biologically relevant G-quadruplex is a mixture of four loop isomers. The folding pattern of a nuclear magnetic resonance (NMR)-derived structure for the predominant loop isomer of this G-quadruplex has been obtained. This G-quadruplex has been demonstrated to be a silencer element, and the cationic porphyrin TMPyP4 has been shown to stabilize this G-quadruplex. Furthermore, TMPyP4 has been shown to repress c-MYC expression, and this effect is mediated through the silencer element. Last, the in vivo activity of TMPyP4 in xenograph models is presented.     

A functional variant in TNXB promoter associates with the risk of esophageal squamous-cell carcinoma

Our previous study identified a tag single-nucleotide polymorphism (SNP) rs204900 in TNXB associated with risk of esophageal squamous-cell carcinoma (ESCC) in the Chinese population. However, the functional role of TNXB and causal variants had not been interrogated in that study. In the present study, we explored the effects of TNXB expression in the development of ESCC and searched for functional variants in this gene. We found TNXB was downregulated in ESCC tumors. Using small interfering RNAs and CRISPR–Cas9 methods, we identified that both knockdown and knockout of TNXB significantly promoted ESCC cell growth in vitro, suggesting a tumor suppressor role of this gene in ESCC. Through further fine-mapping analysis, we identified that a noncoding variant in the promoter of TNXB, rs411337, predisposed to ESCC risk (odds ratio = 1.36, 95% confidence interval: 1.22-1.51, P = 9.10 × 10⁻⁹). These findings revealed the functional mechanism of TNXB in the development of ESCC and may contribute to the prevention and treatment of this disease in the future.     

miR-21-5p promotes cell proliferation by targeting BCL11B in Thp-1 cells

Acute myeloid leukemia (AML) is a highly heterogeneous disease that remains untreatable. MicroRNAs (miRNAs or miRs) play important roles in the pathogenesis of leukemia. miR-21 is highly expressed in multiple types of human cancer and displays oncogenic activities; however, the clinical significance of miR-21 in AML remains unclear. In the present study, it was demonstrated that miR-21 levels were high in patients with AML and in AML cell lines. Further experiments demonstrated that overexpression of miR-21 in Thp-1 human monocytes derived from acute mononuclear leukemia peripheral blood promoted cell proliferation, while downregulation of miR-21-5p, a mature sequence derived from the 5′ end of the miR-21 stem-loop precursor (another mature sequence, miR-21-3p, is derived form 3′ end of miR-21), inhibited cell proliferation. Specifically, it was observed that overexpression of miR-21 could promote the transition of Thp-1 cells into the S and G2/M phases of the cell cycle, as shown by flow cytometry. Furthermore, inhibition of miR-21-5p arrested cells in the S and G2/M phases. Finally, BCL11B was determined to be a functional target of miR-21-5p by luciferase assays. Our study revealed functional and mechanistic associations between miR-21 and BCL11B in Thp-1 cells, which could serve to guide clinical treatment of AML.     

MicroRNA-130a associates with ribosomal protein L11 to suppress c-Myc expression in response to UV irradiation

The oncoprotein c-Myc is essential for cell growth and proliferation while its deregulated overexpression is associated with most human cancers. Thus tightly regulated levels and activity of c-Myc are critical for maintaining normal cell homeostasis. c-Myc is down-regulated in response to several types of stress, including UV-induced DNA damage. Yet, mechanism underlying UV-induced c-Myc reduction is not completely understood. Here we report that L11 promotes miR-130a targeting of c-myc mRNA to repress c-Myc expression in response to UV irradiation. miR-130a targets the 3′-untranslated region (UTR) of c-myc mRNA. Overexpression of miR-130a promotes the Ago2 binding to c-myc mRNA, significantly reduces the levels of both c-Myc protein and mRNA and inhibits cell proliferation. UV treatment markedly promotes the binding of L11 to miR-130a, c-myc mRNA as well as Ago2 in cells. Inhibiting miR-130a significantly suppresses UV-mediated c-Myc reduction. We further show that L11 is relocalized from the nucleolus to the cytoplasm where it associates with c-myc mRNA upon UV treatment. Together, these results reveal a novel mechanism underlying c-Myc down-regulation in response to UV-mediated DNA damage, wherein L11 promotes miR-130a-loaded miRISC to target c-myc mRNA.     

Electrophoretic mobility of T and B lymphocytes in bone tumor patients

Electrophoretic mobility of peripheral blood T and B lymphocytes in bone tumor patients (malignant 24 and benign 16) was studied. Its variations associated with cellular immunity were evaluated in this paper. The electrophoretic mobility of cells was measured at 25 +/- 0.5 degrees C with a cytopherometer. The results showed that electrophoretic mobility of T lymphocytes and E-rosettes in malignant tumor patients were significantly low (P less than 0.05) as compared with that in the normal subjects, while those in the benign tumor patients were not significantly different (P greater than 0.05).     

Aberrant CBFA2T3B gene promoter methylation in breast tumors

Background  

The CBFA2T3 locus located on the human chromosome region 16q24.3 is frequently deleted in breast tumors. CBFA2T3 gene expression levels are aberrant in breast tumor cell lines and the CBFA2T3B isoform is a potential tumor suppressor gene. In the absence of identified mutations to further support a role for this gene in tumorigenesis, we explored whether the CBFA2T3B promoter region is aberrantly methylated and whether this correlates with expression.     

In Situ PLA技术原位分析MTA1与NuRD复合体其他组分的相互作用

目的原位检测肿瘤转移相关蛋白MTA1与NuRD复合体其他组分-Mi2、HDAC2及MBD3的相互作用并分析MTA1/NuRD复合体在HCT116细胞中的分布情况。方法首先利用co-IP技术体外验证MTA1与NuRD复合体其他组分Mi2、HDAC2及MBD3在HCT116细胞裂解液中的相互作用。然后利用In Situ PLA技术,体内原位检测MTA1与三者的相互作用,并根据镜下阳性荧光信号数目,比较MTA1与Mi2、HDAC2及MBD3之间的作用强弱;根据相互作用位点的亚细胞分布情况,分析间期及M期MTA1/NuRD复合体的核质分布情况。结果首次从体内原位水平证实MTA1与NuRD复合体其他组分-Mi2、HDAC2及MBD3的相互作用;其作用强度HDAC2最高,Mi2次之,MBD3最弱;首次发现MTA1/NuRD复合体存在很明显的胞质分布（约占总量的1/4）;另外,我们还首次发现在M期MTA1/NuRD复合体不再位于核区,而是位于染色体外周。结论In Situ PLA技术是一项有效的原位检测蛋白相互作用的新技术;MTA1/NuRD复合体可能参与MTA1胞质中功能的发挥;并且其胞质分布可能参与M期进程调控。     

Erythropoietin-producing hepatocyte B6 variant-derived peptides with the ability to induce glioma-reactive cytotoxic T lymphocytes in human leukocyte antigen-A2+ glioma patients

We recently cloned a variant form of erythropoietin-producing hepatocyte (Eph)B6, a member of the Eph receptor tyrosine kinase family. In the present study, we examined the expression of the EphB6 variant (EphB6v) in a panel of brain tumor cell lines and glioblastoma tissues and we found that EphB6v was preferentially expressed in malignant brain tumors, such as glioblastomas and anaplastic astrocytomas. The EphB6v has a unique 54 amino acid sequence at the C-terminal that is not found in normal EphB6. Therefore, we attempted to identify antigenic peptides unique to EphB6v for immunotherapy. The two EphB6v-derived peptides exhibited the ability to bind to human leukocyte antigen (HLA)-A0201 molecules, and each of them was able to induce cytotoxic T lymphocytes in vitro in the peripheral blood mononuclear cells of HLA-A2⁺ glioma patients. The cytotoxicity was mediated by peptide-specific CD8⁺ T cells in an HLA-A2-restricted manner. The expression of EphB6v was also observed in different types of cancer (e.g. lung, colon, stomach, liver and pancreatic) cells. Taken together, the two peptides derived from EphB6v might be appropriate targets for peptide-based specific immunotherapy for HLA-A2⁺ patients with various cancers. ( Cancer Sci 2008; 99: 1656–1662)