The CBM signalosome: Potential therapeutic target for aggressive lymphoma?

The CBM signalosome plays a pivotal role in mediating antigen-receptor induced NF-κB signaling to regulate lymphocyte functions. The CBM complex forms filamentous structure and recruits downstream signaling components to activate NF-κB. MALT1, the protease component in the CBM complex, cleaves key proteins in the feedback loop of the NF-κB signaling pathway and enhances NF-κB activation. The aberrant activity of the CBM complex has been linked to aggressive lymphoma. Recent years have witnessed dramatic progresses in understanding the assembly mechanism of the CBM complex, and advances in the development of targeted therapy for aggressive lymphoma. Here, we will highlight these progresses and give an outlook on the potential translation of this knowledge from bench to bedside for aggressive lymphoma patients.     

Non-homologous end joining often uses microhomology: Implications for alternative end joining

Artemis and PALF (also called APLF) appear to be among the primary nucleases involved in non-homologous end joining (NHEJ) and responsible for most nucleolytic end processing in NHEJ. About 60% of NHEJ events show an alignment of the DNA ends that use 1 or 2 bp of microhomology (MH) between the two DNA termini. Thus, MH is a common feature of NHEJ. For most naturally occurring human chromosomal deletions (e.g., after oxidative damage or radiation) and translocations, such as those seen in human neoplasms and as well as inherited chromosomal structural variations, MH usage occurs at a frequency that is typical of NHEJ, and does not suggest major involvement of alternative pathways that require more extensive MH. Though we mainly focus on human NHEJ at double-strand breaks, comparison on these points to other eukaryotes, primarily S. cerevisiae, is informative.     

Epstein-Barr病毒相关T/NK细胞淋巴瘤与B细胞淋巴瘤的临床分析

Epstein-Barr病毒(Epstein-Barr virus,EBV)是可导致人类感染的淋巴滤泡病毒,感染非常普遍。本研究通过对2013年1月-2016年12月于复旦大学附属华东医院就诊并确诊为淋巴瘤且伴有EBV感染的49例患者的临床资料进行回顾性分析,探讨EBV相关淋巴瘤患者的临床特点及生存情况。结果显示,49例EBV相关淋巴瘤患者中,18例为B细胞淋巴瘤,31例为T/NK细胞淋巴瘤。EBV相关B细胞淋巴瘤与T/NK细胞淋巴瘤患者之间白细胞、血小板、丙氨酸氨基转移酶、天冬氨酸氨基转移酶、乳酸脱氢酶、铁蛋白、纤维蛋白原、红细胞沉降率、C反应蛋白的差异有统计学意义(P<0.05)。中位随访5.0个月,49例患者的1个月、6个月、1年、3年生存率分别为 84.4%、59.8%、53.2%、40.3%。结果表明,与EBV相关B细胞淋巴瘤患者相比,EBV相关T/NK细胞淋巴瘤患者的肝功能损伤严重,更易合并噬血细胞综合征,生存期更短,但生存期差异无统计学意义。     

Epstein-Barr病毒相关淋巴瘤的研究进展

Epstein-Barr病毒（Epstein-Barr virus,EBV）是第1个被发现与人类肿瘤发生相关的病毒,且越来越多的数据表明其感染与某些淋巴瘤的发生发展、治疗及预后密切相关。近年来免疫治疗手段发展迅速,但EBV阳性淋巴瘤的治疗目前主要仍以放化疗为基础,结合抗病毒药物。因此,加强EBV及其相关淋巴瘤的研究,寻找有效预防或治疗EBV感染的方法,将有望改善EBV阳性淋巴瘤患者的预后。     

Monocyte activation by an oral immunomodulator (bestatin) in lymphoma patients following autologous bone marrow transplantation

 Bestatin (ubenimex), an inhibitor of aminopeptidase, is an oral immunomodulator that binds to CD13 (aminopeptidase N) on macrophages/monocytes. To examine its immunomodulatory effect after high-dose therapy and autologous bone marrow transplantation (BMT), a dose-finding phase Ib trial was conducted with 30 Hodgkin’s disease and non-Hodgkin’s lymphoma patients who received no drug (control), 10 and 30 mg (low dose), or 90 and 180 mg (high dose) of bestatin daily for 60 days following autologous BMT. Bestatin administration was initiated when the absolute neutrophil count was greater than 250/mm3 on 2 consecutive days. The serum neopterin levels, an indicator of monocyte/macrophage activation, increased in the high-dose group compared to the control group (not significantly) and the low-dose group (significantly). Similarly, the colony-stimulating activity in the sera was significantly increased in the high-dose group compared to the control and low-dose groups. We also examined the expression of cell-surface markers on monocytes in these patients by fluorescent cytometry analysis. There was no significant difference either in the frequency or absolute number of monocytes (CD14⁺) among the three groups at any time. However, a significant increase in the frequency of CD16(FcgRIII)-positive monocytes (a marker of activation) was observed in the high-dose group compared to controls from day 14 to day 60 after the start of bestatin administration. Further, the frequency of HLA-DR⁺ monocytes (another marker of activation) was significantly increased in the high-dose group. These results indicate that bestatin at higher doses (90 and 180 mg daily), but not lower doses, activates macrophages/monocytes, as demonstrated by phenotypic marker (HLA-DR and CD16) up-regulation, and this provides augmentation of neopterin and colony-stimulating activity in the serum of patients following autologous BMT. Received: 24 June 1996 / Accepted 13 September 1996     

Pretargeted radioimmunotherapy using 131I-labelled bivalent hapten-bearing peptides

The advantages of bivalent hapten-bearing peptides for the detection oftumours pretargeted with bispecific antibodies have been demonstrated. Thistechnology is now considered for radioimmunotherapy and bivalent haptensdesigned to target ¹³¹I are needed. We thus synthesised aseries of tyrosine-containing peptides bearing the histamine-hemisuccinatehapten. These molecules were tested for their ability to bind simultaneouslytwo anti-hapten antibody molecules. One of these bivalent haptens, AG3.0,with a lysyl-d-tyrosyl-lysine connecting chain, was found to have optimalbinding characteristics and was thus selected for further investigations.AG3.0 was shown to efficiently deliver radioactive iodine to humancolorectal tumours grafted in nude mice using an anti-carcinoembryonicantigen×anti-histamine-hemisuccinate bispecific antibody. AG3.0 wasalso targeted to human B lymphoma cells pretargeted with a bispecificantibody specific for membrane IgM. In this system, bivalent ligands such asF(ab)₂ or IgG are rapidly internalised and covalentlylinked radioactive iodine is released from target cells as a result ofintracellular catabolism. With the pretargeted iodine-labelled bivalenthapten, a fivefold increase in the intracellular activity retention time ascompared to ¹²⁵I-labelled F(ab)₂ and IgGwas observed. The radiolabelled hapten did not undergo any degradation afterinternalisation. These results have been confirmed in vivo with ananti-BCL₁ IgM idiotype bispecific antibody and¹³¹I-labelled AG3.0. These reagents injected as a single 300µCi dose, 7 days after inoculation of 10⁴BCL₁ lymphoma cells in BALB/c mice, cured 14/16 of the animalsand the treatment was well tolerated. Comparatively, the same dose oflabelled IgG cured 13/16 of the mice but three mice died of haematologictoxicity. The same dose of labelled F(ab)₂ orFab was completely inefficient. was completely inefficient. ¹³¹I-labelled bivalenthaptens are now used in phase I radioimmunotherapy clinical trials.     

Cytotoxic and Apoptotic Effects of Novel Heterodinucleoside Phosphates Consisting of 5‐Fluorodeoxyuridine and Ara‐C in Human Cancer Cell Lines

In search for possible alternatives in the treatment of human malignancies we investigated several new heterodinucleoside phosphates containing of 5‐Fluorodeoxyuridine (5‐FdUrd) and Arabinofuranosylcytosine (Ara‐C). We show that all dimers tested inhibited the number of colonies of CCL228, CCL227, 5‐FU resistant CCL227 and HT‐29 human colon tumor cells with IC₅₀ values ranging from 0.65 to 1 nM. Dimer # 2 inhibited the number of sensitive and Ara‐C resistant H9 human lymphoma cells with IC₅₀ values ranging from 200 to 230 nM. Since no significant difference in the cytotoxicity of the dimers could be observed between sensitive and resistant cells, these compounds might be used in the treatment of 5‐FU and Ara‐C resistant tumors.     

Gossypol Increases Expression of the Pro-apoptotic BH3-only Protein NOXA through a Novel Mechanism Involving Phospholipase A2, Cytoplasmic Calcium,and Endoplasmic Reticulum Stress

Gossypol is a putative BH3 mimetic proposed to inhibit BCL2 and BCLXL based on cell-free assays. We demonstrated previously that gossypol failed to directly inhibit BCL2 in cells or induce apoptosis in chronic lymphocytic leukemia (CLL) cells or platelets, which require BCL2 or BCLXL, respectively, for survival. Here, we demonstrate that gossypol rapidly increased activity of phospholipase A2 (PLA2), which led to an increase in cytoplasmic calcium, endoplasmic reticulum (ER) stress, and up-regulation of the BH3-only protein NOXA. Pretreatment with the PLA2 inhibitor, aristolochic acid, abrogated the increase in calcium, ER stress, and NOXA. Calcium chelation also abrogated the gossypol-induced increase in calcium, ER stress, and NOXA, but not the increase in PLA2 activity, indicating that PLA2 is upstream of these events. In addition, incubating cells with the two products of PLA2 (lysophosphatidic acid and arachidonic acid) mimicked treatment with gossypol. NOXA is a pro-apoptotic protein that functions by binding the BCL2 family proteins MCL1 and BFL1. The BCL2 inhibitor ABT-199 is currently in clinical trials for CLL. Resistance to ABT-199 can occur from up-regulation of other BCL2 family proteins, and this resistance can be mimicked by culturing CLL cells on CD154⁺ stroma cells. We report here that AT-101, a derivative of gossypol in clinical trials, overcomes stroma-mediated resistance to ABT-199 in primary CLL cells, suggesting that a combination of these drugs may be efficacious in the clinic.