FAM48A mediates compensatory autophagy induced by proteasome impairment

Maintaining protein homeostasis is central to cell survival. The ubiquitin–proteasome system and autophagy play pivotal roles in protein quality control through protein degradation. Activities of these degradative pathways are carefully orchestrated, and autophagy is up‐regulated during proteasome dysfunction for cellular homeostasis. However, the mechanism by which proteasome impairment induces compensatory autophagy has remained largely elusive. Here, we show that FAM48A mediates autophagy induction during proteasome inhibition. FAM48A is degraded by the proteasome and accumulates in cells by proteasome inhibition. Knockdown of FAM48A led to defective induction of autophagy during proteasome inhibition and accompanied by defective localization of Atg9 on recycling endosomes. Our results indicate that FAM48A is a kind of sensor that is required for compensatory autophagy induction upon proteasome impairment.     

多发性骨髓瘤的过去、现在及未来

多发性骨髓瘤是一种浆细胞系恶性肿瘤，依靠传统的化疗方案不能够治愈。近年来，基于对骨髓瘤生物学、遗传学以及肿瘤发生学的深入研究，开发研制出一些新药，并提出了靶向治疗的新方法，如利用蛋白酶体抑制剂、免疫调节剂等，能够极大的改善病人的预后；另外，新的联合化疗方案的出现，也明显提高了缓解率。这些新的治疗策略为临床工作带来了巨大帮助，本文对治疗多发性骨髓瘤的新看法的最近进展进行了评述。     

Immunoproteasome in the blood plasma of children with acute appendicitis,and its correlation with proteasome and UCHL1 measured by SPR imaging biosensors

The aim of this study was to determinate the immunoproteasome concentration in the blood plasma of children with appendicitis, and its correlation with circulating proteasome and ubiquitin carboxyl‐terminal hydrolase L1 (UCHL1). Twenty‐seven children with acute appendicitis, managed at the Paediatric Surgery Department, were included randomly into the study (age 2 years 9 months up to 14 years, mean age 9·5 ± 1 years). There were 10 girls and 17 boys; 18 healthy, age‐matched subjects, admitted for planned surgeries served as controls. Mean concentrations of immunoproteasome, 20S proteasome and UCHL1 in the blood plasma of children with appendicitis before surgery 24 h and 72 h after the appendectomy were higher than in the control group. The immunoproteasome, 20S proteasome and UCHL1 concentrations in the blood plasma of patients with acute appendicitis were highest before surgery. The immunoproteasome, 20S proteasome and UCHL1 concentration measured 24 and 72 h after the operation decreased slowly over time and still did not reach the normal range (P < 0·05). There was no statistical difference between immunoproteasome, 20S proteasome and UCHL1 concentrations in children operated on laparoscopically and children after classic appendectomy. The immunoproteasome concentration may reflect the metabolic response to acute state inflammation, and the process of gradual ebbing of the inflammation may thus be helpful in the assessment of the efficacy of treatment. The method of operation – classic open appendectomy or laparoscopic appendectomy – does not influence the general trend in immunoproteasome concentration in children with appendicitis.     

Free ISG15 triggers an antitumor immune response against breast cancer: a new perspective

Interferon-Stimulated Gene 15 (ISG15), an antagonist of the canonical ubiquitin pathway, is frequently overexpressed in various cancers. In cancer cells, ISG15 is detected as free (intracellular) and conjugated to cellular proteins (ISGylation). Free ISG15 is also secreted into the extracellular milieu. ISGylation has protumor functions and extracellular free ISG15 has immunomodulatory properties in vitro. Therefore, whether ISG15 is a tumor suppressor or tumor promoter in vivo remains controversial. The current study aimed to clarify the role of free ISG15 in tumorigenesis. Breast cancer cells stably expressing control, ISG15, and UbcH8 (ISG15-specific E2 ligase) shRNAs were used to assess the immunoregulatory and antitumor function of free ISG15 in cell culture (in vitro) and in nude mice (in vivo). We show that extracellular free ISG15 suppresses breast tumor growth and increases NK cell infiltration into xenografted breast tumors in nude mice, and intracellular free ISG15 enhances major histocompatibility complex (MHC) class I surface expression in breast cancer cells. We conclude that free ISG15 may have antitumor and immunoregulatory function in vivo. These findings provides the basis for developing strategies to increase systemic levels of free ISG15 to treat cancer patients overexpressing the ISG15 pathway.     

The Proteasome Inhibitor Bortezomib Inhibits Inflammatory Response of Periodontal Ligament Cells and Ameliorates Experimental Periodontitis in Rats

Background: Periodontitis is a chronic inflammatory disease initiated by bacteria and their virulence factors. Bortezomib (BTZ) is the first proteasome inhibitor for clinical treatment of malignancies. Its anticancer activity is accompanied by an anti‐inflammatory effect. However, there are few reports about its anti‐inflammatory effect and underlying mechanism in periodontal disease, especially on human periodontal ligament cells (hPDLCs), which are considered a promising cell‐based therapy for treating periodontitis. Methods: hPDLCs were treated with lipopolysaccharide (LPS) and pretreated with BTZ. mRNA and protein levels of tumor necrosis factor (TNF)‐alpha, interleukin (IL)‐1β, IL‐6, and IL‐8 were determined. The anti‐inflammatory mechanism of BTZ was studied. Further, experimental rat periodontitis was induced with ligature and LPS injection, and simultaneously and locally treated with BTZ (three injections/week). Four weeks after treatment, microcomputed tomography, immunohistochemical, and histopathologic analyses were performed. Results: Bortezomib administration at safe concentrations (≤1 nM) inhibited production of proinflammatory cytokines in LPS‐stimulated hPDLCs via nuclear factor (NF)‐kappa B, p38/extracellular signal‐regulated kinase, and mitogen‐activated protein kinase/activator protein‐1 pathways. Moreover, in the LPS and ligature‐induced periodontitis rat model, BTZ suppressed expression of TNF‐α, IL‐1β, IL‐6, and IL‐8, reduced the ratio of receptor activator of NF‐κB ligand/osteoprotegerin, and prevented alveolar bone absorption. Conclusion: These findings demonstrate the anti‐inflammatory activity of BTZ against periodontal inflammatory response and present BTZ as a promising therapy for periodontal disease.     

FFPE tissue as a feasible source for gene expression analysis – A comparison of three reference genes and one tumor marker

Background

Formalin-fixation, paraffin-embedding is the standard processing technique for tumor tissue in modern pathology. New techniques such as cryo-conservation allow rapid fixation and long-time storage but come along with increased costs and enlarged storage complexity. However, formalin-fixed, paraffin-embedded (FFPE) tissue is available in a large quantity, making it the ideal material for retrospective studies.The following study was designed to investigate the influence of formalin-fixation on the quality of mRNA and applicability of FFPE-derived mRNA for gene expression analysis. Three potential reference genes for pulmonary tumors with neuroendocrine differentiation were included and tested for their robust expression.

Materials and methods

Eighty specimens collected from 2005 to 2012 at the Institute of Pathology and Neuropathology at the University Hospital Essen were analyzed for their gene expression by using TaqMan^® gene expression assays on demand (AoD). Three distinct potential reference genes (ACTB, GAPDH, HPRT1) were evaluated for their expression, and a proteasome subunit (PSMA1) was included in the analysis as tumor marker and functioned as an internal technical control.

Conclusion

For GAPDH and ACTB, a highly significant correlation and consistent expression between the investigated entities was found, making them reliable reference genes for further research. Additionally, the feasibility for a FFPE tissue-based gene expression analysis was verified by showing that the mRNA quality is sufficient. When standardized FFPE preparation is performed carefully, sufficient mRNA can be isolated for reliable and successful gene expression analysis. That provides the basis the door for large, retrospective studies that correlate molecular and clinical follow-up data.