The biology of Ku and its potential oncogenic role in cancer

Ku is a heterodimeric protein made up of two subunits, Ku70 and Ku80. It was originally identified as an autoantigen recognized by the sera of patients with autoimmune diseases. It is a highly versatile regulatory protein that has been implicated in multiple nuclear processes, e.g., DNA repair, telomere maintenance and apoptosis. Accordingly, Ku is thought to play a crucial role in maintenance of chromosomal integrity and cell survival. Recent reports suggest that there is a positive relationship between Ku and the development of cancer, making Ku an important candidate target for anticancer drug development. Specifically, prior studies suggest that a delicate balance exists in Ku expression, as overexpression of Ku proteins promotes oncogenic phenotypes, including hyperproliferation and resistance to apoptosis; whereas deficient or low expression of Ku leads to genomic instability and tumorigenesis. Such observations through various experimental models indicate that Ku may act as either a tumor suppressor or an oncoprotein. Hence, understanding the link between the various functions of Ku and the development of cancer in different cell systems may help in the development of novel anticancer therapeutic agents that target Ku. These studies may also increase our understanding of how Ku autoantibodies are generated in autoimmune diseases.     

Initial clinical trial of epratuzumab (humanized anti-CD22 antibody) for immunotherapy of systemic lupus erythematosus

B cells play an important role in the pathogenesis of systemic lupus erythematosus (SLE), so the safety and activity of anti-B cell immunotherapy with the humanized anti-CD22 antibody epratuzumab was evaluated in SLE patients. An open-label, single-center study of 14 patients with moderately active SLE (total British Isles Lupus Assessment Group (BILAG) score 6 to 12) was conducted. Patients received 360 mg/m² epratuzumab intravenously every 2 weeks for 4 doses with analgesic/antihistamine premedication (but no steroids) prior to each dose. Evaluations at 6, 10, 18 and 32 weeks (6 months post-treatment) follow-up included safety, SLE activity (BILAG score), blood levels of epratuzumab, B and T cells, immunoglobulins, and human anti-epratuzumab antibody (HAHA) titers. Total BILAG scores decreased by ≥ 50% in all 14 patients at some point during the study (including 77% with a ≥ 50% decrease at 6 weeks), with 92% having decreases of various amounts continuing to at least 18 weeks (where 38% showed a ≥ 50% decrease). Almost all patients (93%) experienced improvements in at least one BILAG B- or C-level disease activity at 6, 10 and 18 weeks. Additionally, 3 patients with multiple BILAG B involvement at baseline had completely resolved all B-level disease activities by 18 weeks. Epratuzumab was well tolerated, with a median infusion time of 32 minutes. Drug serum levels were measurable for at least 4 weeks post-treatment and detectable in most samples at 18 weeks. B cell levels decreased by an average of 35% at 18 weeks and remained depressed at 6 months post-treatment. Changes in routine safety laboratory tests were infrequent and without any consistent pattern, and there was no evidence of immunogenicity or significant changes in T cells, immunoglobulins, or autoantibody levels. In patients with mild to moderate active lupus, 360 mg/m² epratuzumab was well tolerated, with evidence of clinical improvement after the first infusion and durable clinical benefit across most body systems. As such, multicenter controlled studies are being conducted in broader patient populations.     

Epratuzumab (humanised anti-CD22 antibody) in primary Sjögren's syndrome: an open-label phase I/II study

This open-label, phase I/II study investigated the safety and efficacy of epratuzumab, a humanised anti-CD22 monoclonal antibody, in the treatment of patients with active primary Sj?gren's syndrome (pSS). Sixteen Caucasian patients (14 females/2 males, 33-72 years) were to receive 4 infusions of 360 mg/m2 epratuzumab once every 2 weeks, with 6 months of follow-up. A composite endpoint involving the Schirmer-I test, unstimulated whole salivary flow, fatigue, erythrocyte sedimentation rate (ESR), and immunoglobulin G (IgG) was devised to provide a clinically meaningful assessment of response, defined as a > or = 20% improvement in at least two of the aforementioned parameters, with > or = 20% reduction in ESR and/or IgG considered as a single combined criterion. Fourteen patients received all infusions without significant reactions, 1 patient received 3, and another was discontinued due to a mild acute reaction after receiving a partial infusion. Three patients showed moderately elevated levels of Human anti-human (epratuzumab) antibody not associated with clinical manifestations. B-cell levels had mean reductions of 54% and 39% at 6 and 18 weeks, respectively, but T-cell levels, immunoglobulins, and routine safety laboratory tests did not change significantly. Fifty-three percent achieved a clinical response (at > or = 20% improvement level) at 6 weeks, with 53%, 47%, and 67% responding at 10, 18, and 32 weeks, respectively. Approximately 40%-50% responded at the > or = 30% level, while 10%-45% responded at the > or = 50% level for 10-32 weeks. Additionally, statistically significant improvements were observed in fatigue, and patient and physician global assessments. Further, we determined that pSS patients have a CD22 over-expression in their peripheral B cells, which was downregulated by epratuzumab for at least 12 weeks after the therapy. Thus, epratuzumab appears to be a promising therapy in active pSS, suggesting that further studies be conducted.     

Paenibacillus hemolyticus, the first hemolytic Paenibacillus with growth-promoting activities discovered

Paenibacillus spp. are Gram-positive, facultatively aerobic, bacilli-shaped endospore-forming bacteria. They have been detected in a variety of environments, such as soil, water, forage, insect larvae, and even clinical samples. The strain 139SI (GenBank accession No.: JF825470.1) from three strains of Paenibacillus isolates investigated here was chosen as the type strain of the proposed novel species. The other two similar strain isolates investigated were 140SI (JF825471.1) and 141SI (JQ734548.1). These strains were identified as members of the genus Paenibacillus on the basis of phenotypic characteristics, phylogenetic analysis and 16S rRNA G+C content. Surprisingly, these strains exhibited a strong hemolytic activity on 5% sheep blood agar. Their crude extracts also showed positive growth-promoting activities in colon cancer and Vero cell lines. To our knowledge, this is the first Paenibacillus with hemolytic and growth-promoting activities reported, and the name Paenibacillus hemolyticus for this novel species is proposed. The capability of this novel species in hemolytic and cell growth activities suggests its potential in both clinical and pharmacological implications.     

The M, E, and N structural proteins of the severe acute respiratory syndrome coronavirus are required for efficient assembly, trafficking, and release of virus-like particles

The production of virus-like particles (VLPs) constitutes a relevant and safe model to study molecular determinants of virion egress. The minimal requirement for the assembly of VLPs for the coronavirus responsible for severe acute respiratory syndrome in humans (SARS-CoV) is still controversial. Recent studies have shown that SARS-CoV VLP formation depends on either M and E proteins or M and N proteins. Here we show that both E and N proteins must be coexpressed with M protein for the efficient production and release of VLPs by transfected Vero E6 cells. This suggests that the mechanism of SARS-CoV assembly differs from that of other studied coronaviruses, which only require M and E proteins for VLP formation. When coexpressed, the native envelope trimeric S glycoprotein is incorporated onto VLPs. Interestingly, when a fluorescent protein tag is added to the C-terminal end of N or S protein, but not M protein, the chimeric viral proteins can be assembled within VLPs and allow visualization of VLP production and trafficking in living cells by state-of-the-art imaging technologies. Fluorescent VLPs will be used further to investigate the role of cellular machineries during SARS-CoV egress.     

In Vivo Evidence for Serine Biosynthesis-Defined Sensitivity of Lung Metastasis,but Not of Primary Breast Tumors,to mTORC1 Inhibition

1. Download : Download high-res image (198KB)
2. Download : Download full-size image