TIF1γ Suppresses Tumor Progression by Regulating Mitotic Checkpoints and Chromosomal Stability

TRIM33 loss in multiple myeloma is associated with genomic instability and sensitivity to PARP inhibitors

Deletions of chromosome 1p (del(1p)) are a recurrent genomic aberration associated with poor outcome in Multiple myeloma (MM.) TRIM33, an E3 ligase and transcriptional co-repressor, is located within a commonly deleted region at 1p13.2. TRIM33 is reported to play a role in the regulation of mitosis and PARP-dependent DNA damage response (DDR), both of which are important for maintenance of genome stability. Here, we demonstrate that MM patients with loss of TRIM33 exhibit increased chromosomal instability and poor outcome. Through knockdown studies, we show that TRIM33 loss induces a DDR defect, leading to accumulation of DNA double strand breaks (DSBs) and slower DNA repair kinetics, along with reduced efficiency of non-homologous end joining (NHEJ). Furthermore, TRIM33 loss results in dysregulated ubiquitination of ALC1, an important regulator of response to PARP inhibition. We show that TRIM33 knockdown sensitizes MM cells to the PARP inhibitor Olaparib, and this is synergistic with the standard of care therapy bortezomib, even in co-culture with bone marrow stromal cells (BMSCs). These findings suggest that TRIM33 loss contributes to the pathogenesis of high-risk MM and that this may be therapeutically exploited through the use of PARP inhibitors.

TRIM33 Is a Co-Regulator of Estrogen Receptor Alpha

Estrogen receptor alpha (ER)-positive breast cancer is responsible for over 60% of breast cancer cases in the U.S. Among patients diagnosed with early-stage ER+ disease, 1/3 will experience recurrence despite treatment with adjuvant endocrine therapy. ER is a nuclear hormone receptor responsible for estrogen-driven tumor growth. ER transcriptional activity is modulated by interactions with coregulators. Dysregulation of the levels of these coregulators is involved in the development of endocrine resistance. To identify ER interactors that modulate transcriptional activity in breast cancer, we utilized biotin ligase proximity profiling of ER interactomes. Mass spectrometry analysis revealed tripartite motif containing 33 (TRIM33) as an estrogen-dependent interactor of ER. shRNA knockdown showed that TRIM33 promoted ER transcriptional activity and estrogen-induced cell growth. Despite its known role as an E3 ubiquitin ligase, TRIM33 increased the stability of endogenous ER in breast cancer cells. TRIM33 offers a novel target for inhibiting estrogen-induced cancer cell growth, particularly in cases of endocrine resistance driven by ER (ESR1) gene amplification or overexpression.

Tubular cell transcriptional intermediary factor 1γ deficiency exacerbates kidney injury-induced tubular cell polyploidy and fibrosis

Tubulointerstitial fibrosis is considered the final convergent pathway of progressive chronic kidney diseases (CKD) regardless of etiology. However, mechanisms underlying kidney injury-induced fibrosis largely remain unknown. Recent studies have indicated that transcriptional intermediary factor 1γ (TIF1γ) inhibits the progression of fibrosis in other organs. Here, we found that TIF1γ was highly expressed in the cytoplasm and nucleus of the kidney proximal tubule. Interestingly, we found tubular TIF1γ expression was decreased in patients with CKD, including those with diabetes, hypertension, and IgA nephropathy, and in mouse models with experimental kidney fibrosis (unilateral ureteral obstruction [UUO], folic acid nephropathy [FAN], and aristolochic acid-induced nephrotoxicity). Tubule-specific knock out of TIF1γ in mice exacerbated UUO- and FAN-induced tubular cell polyploidy and subsequent fibrosis, whereas overexpression of kidney TIF1γ protected mice against kidney fibrosis. Mechanistically, in tubular epithelial cells, TIF1γ exerted an antifibrotic role via transforming growth factor-β (TGF-β)-dependent and -independent signaling. TIF1γ hindered TGF-β signaling directly by inhibiting the formation and activity of the transcription factor Smad complex in tubular cells, and we discovered that TIF1γ suppressed epidermal growth factor receptor (EGFR) signaling upstream of TGF-β signaling in tubular cells by ubiquitylating EGFR at its lysine 851/905 sites thereby promoting EGFR internalization and lysosomal degradation. Pharmacological inhibition of EGFR signaling attenuated exacerbated polyploidization and the fibrotic phenotype in mice with tubule deletion of TIF1γ. Thus, tubular TIF1γ plays an important role in kidney fibrosis by suppressing profibrotic EGFR and TGF-β signaling. Hence, our findings suggest that maintaining homeostasis of tubular TIF1γ may be a new therapeutic option for treating tubulointerstitial fibrosis and subsequent CKD.

Bromodomain (BrD) Family Members as Regulators of Cancer Stemness-A Comprehensive Review

Epigenetic mechanisms involving DNA methylation and chromatin modifications have emerged as critical facilitators of cancer heterogeneity, substantially affecting cancer development and progression, modulating cell phenotypes, and enhancing or inhibiting cancer cell malignant properties. Not surprisingly, considering the importance of epigenetic regulators in normal stem cell maintenance, many chromatin-related proteins are essential to maintaining the cancer stem cell (CSC)-like state. With increased tumor-initiating capacities and self-renewal potential, CSCs promote tumor growth, provide therapy resistance, spread tumors, and facilitate tumor relapse after treatment. In this review, we characterized the epigenetic mechanisms that regulate the acquisition and maintenance of cancer stemness concerning selected epigenetic factors belonging to the Bromodomain (BrD) family of proteins. An increasing number of BrD proteins reinforce cancer stemness, supporting the maintenance of the cancer stem cell population in vitro and in vivo via the utilization of distinct mechanisms. As bromodomain possesses high druggable potential, specific BrD proteins might become novel therapeutic targets in cancers exhibiting de-differentiated tumor characteristics.

The cell cycle, cancer development and therapy

The process of cell division plays a vital role in cancer progression. Cell proliferation and error-free chromosomes segregation during mitosis are central events in life cycle. Mistakes during cell division generate changes in chromosome content and alter the balances of chromosomes number. Any defects in expression of TIF1 family proteins, SAC proteins network, mitotic checkpoint proteins involved in chromosome mis-segregation and cancer development. Here we discuss the function of organelles deal with the chromosome segregation machinery, proteins and correction mechanisms involved in the accurate chromosome segregation during mitosis.

Downregulation of TRIM33 Promotes Survival and Epithelial-Mesenchymal Transition in Gastric Cancer

Among all malignancies worldwide, gastric cancer is the fifth most common cancer with the third highest mortality rate. One of the main reasons for the low survival rate is the recurrence and metastasis that occurs in many patients after surgery. Numerous studies have shown that abnormal TRIM33 expression is associated with the progression of malignant tumors. TRIM33 can function either as a tumor suppressor or tumor promoter in different cancers. Our data showed that TRIM33 was highly expressed in stomach cancer, and in human gastric cancer tissues, low expression of TRIM33 was associated with poor prognosis in patients with gastric cancer. To clarify the function of TRIM33 in survival and epithelial–mesenchymal transition in gastric cancer cells, we investigated the effect of TRIM33 knockdown in several gastric cancer cell lines. Downregulation of TRIM33 in BGC-823 and SGC-7901 cells enhanced the proliferation, colony formation, and migratory ability of these gastric cancer cells. It also promoted epithelial–mesenchymal transition; transfection of cells with siRNA targeting TRIM33 led to the upregulation of vimentin and N-Cadherin expression, and downregulation of E-Cadherin expression. Meanwhile, the transforming growth factor beta pathway was activated: levels of transforming growth factor beta were elevated and the expressions of p-Smad2, Smad2, Smad3, and Smad4 were activated. To confirm the role of TRIM33 in vivo, a xenograft model was established in nude mice. Immunohistochemical analysis identified that the protein levels of TRIM33, p-Smad2, Smad2, Smad3, Smad4, vimentin, and N-Cadherin were increased, and E-Cadherin levels were decreased, in xenograft tumors from the si-TRIM33 group. Taken together, these results suggest that TRIM33 may be a potential marker for the diagnosis and prognosis of gastric cancer. Furthermore, it may also serve as a novel target for gastric cancer treatment.

An Immune-Related Long Noncoding RNA Signature as a Prognostic Biomarker for Human Endometrial Cancer

Background

Endometrial cancer is among the most common malignant tumors threatening the health of women. Recently, immunity and long noncoding RNA (lncRNA) have been widely examined in oncology and shown to play important roles in oncology. Here, we searched for immune-related lncRNAs as prognostic biomarkers to predict the outcome of patients with endometrial cancer.

Methods

RNA sequencing data for 575 endometrial cancer samples and immune-related genes were downloaded from The Cancer Genome Atlas (TCGA) database and gene set enrichment analysis (GSEA) gene sets, respectively. Immune-related lncRNAs showing a coexpression relationship with immune-related genes were obtained, and Cox regression analysis was performed to construct the prognostic model. Survival, independent prognostic, and clinical correlation analyses were performed to evaluate the prognostic model. Immune infiltration of endometrial cancer samples was also evaluated. Functional annotation of 12 immune-related lncRNAs was performed using GSEA software. Prognostic nomogram and survival analysis for independent prognostic risk factors were performed to evaluate the prognostic model and calculate the survival time based on the prognostic model.

Results

Twelve immune-related lncRNAs (ELN-AS1, AC103563.7, PCAT19, AF131215.5, LINC01871, AC084117.1, NRAV, SCARNA9, AL049539.1, POC1B-AS1, AC108134.4, and AC019080.5) were obtained, and a prognostic model was constructed. The survival rate in the high-risk group was significantly lower than that in the low-risk group. Patient age, pathological grade, the International Federation of Gynecology and Obstetrics (FIGO) stage, and risk status were the risk factors. The 12 immune-related lncRNAs correlated with patient age, pathological grade, and FIGO stage. Principal component analysis and functional annotation showed that the high-risk and low-risk groups separated better, and the immune status of the high-risk and low-risk groups differed. Nomogram and receiver operating characteristic (ROC) curves effectively predicted the prognosis of endometrial cancer. Additionally, age, pathological grade, FIGO stage, and risk status were all related to patient survival.

Conclusion

We identified 12 immune-related lncRNAs affecting the prognosis of endometrial cancer, which may be useful as therapeutic targets and molecular biomarkers.

The Association between TIF1 Family Members and Cancer Stemness in Solid Tumors

Simple Summary

Stem cell-associated molecular features of solid tumors, collectively known as cancer stemness, are of great importance in the development, progression, and reoccurrence of cancer. Transcriptional and epigenetic dysregulation is significantly associated with cancer stemness. Here, we investigated the association between the Transcriptional Intermediary Factor 1 (TIF1) family members and cancer stemness in solid tumors. We aimed to evaluate the potential value of TIF1 members in predicting a stem-like cancer phenotype. Our results indicate that only TIF1β (also known as Tripartite Motif protein 28, TRIM28) high expression is consequently associated with a “stemness high” phenotype, regardless of the tumor type, resulting in a worse prognosis for cancer patients. The oncogenic signature of TRIM28^HIGH tumors significantly reflects the enrichment of “stemness high” cancers with targets for c-Myc (MYC Proto-Oncogene). TRIM28-associated gene expression profiles are also robustly enriched with stemness markers. Our results demonstrate that the association between high TRIM28 expression and an enriched cancer stem cell-like phenotype is a common phenomenon across solid tumors.

Abstract

Cancer progression entails a gradual loss of a differentiated phenotype in parallel with the acquisition of stem cell-like features. Cancer de-differentiation and the acquisition of stemness features are mediated by the transcriptional and epigenetic dysregulation of cancer cells. Here, using publicly available data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and harnessing several bioinformatic tools, we characterized the association between Transcriptional Intermediary Factor 1 (TIF1) family members and cancer stemness in 27 distinct types of solid tumors. We aimed to define the prognostic value for TIF1 members in predicting a stem cell-like cancer phenotype and patient outcome. Our results demonstrate that high expression of only one member of the TIF1 family, namely TIF1β (also known as Tripartite Motif protein 28, TRIM28) is consequently associated with enriched cancer stemness across the tested solid tumor types, resulting in a worse prognosis for cancer patients. TRIM28 is highly expressed in higher grade tumors that exhibit stem cell-like traits. In contrast to other TIF1 members, only TIF1β/TRIM28-associated gene expression profiles were robustly enriched with stemness markers regardless of the tumor type. Our work demonstrates that TIF1 family members exhibit distinct expression patterns in stem cell-like tumors, despite their structural and functional similarity. Among other TIF1 members, only TRIM28 might serve as a marker of cancer stemness features.

TRIM33 Overexpression Inhibits the Progression of Clear Cell Renal Cell Carcinoma In Vivo and In Vitro

Purpose

To evaluate the expression of tripartite motif-containing 33 (TRIM33) in ccRCC tissues and explore the biological effect of TRIM33 on the progress of ccRCC.

Method

The Cancer Genome Atlas (TCGA) database was used to examine the mRNA expression levels of TRIM33 in ccRCC tissues and its clinical relevance. Immunohistochemistry (IHC) was performed to evaluate its expression in ccRCC tissues obtained from our hospital. The correlation between TRIM33 expression and clinicopathological features of the patients was also investigated. The effects of TRIM33 on the proliferation of ccRCC cells were examined using the CCK-8 and colony formation assays. The effects of TRIM33 on the migration and invasion of ccRCC cells were explored through wound healing and transwell assays, along with the use of Wnt signaling pathway agonists in rescue experiments. Western blotting was used to explore the potential mechanism of TRIM33 in renal cancer cells. A xenograft model was used to explore the effect of TRIM33 on tumor growth.

Result

Bioinformatics analysis showed that TRIM33 mRNA expression in ccRCC tissues was downregulated, and low TRIM33 expression was related to poor prognosis in ccRCC patients. In agreement with this, low TRIM33 expression was detected in human ccRCC tissues. TRIM33 expression levels were correlated with clinical characteristics, including tumor size and Furman's grade. Furthermore, TRIM33 overexpression inhibited proliferation, migration, and invasion of 786-O and ACHN cell lines. The rescue experiment showed that the originally inhibited migration and invasion capabilities were restored. TRIM33 overexpression reduced the expression levels of β-catenin, cyclin D1, and c-myc, and inhibited tumor growth in ccRCC cells in vivo.

Conclusion

TRIM33 exhibits an abnormally low expression in human ccRCC tissues. TRIM33 may serve as a potential therapeutic target and prognostic marker for ccRCC.

Clinical features of anti-transcription intermediary factor 1γ (TIF1γ)-positive dermatomyositis with internal malignancy and investigation of the involvement of TIF1γ expression in tumors in the pathogenesis of cancer-associated dermatomyositis

Anti-transcription intermediary factor 1γ (anti-TIF1γ) antibody (Ab) is significantly associated with internal malignancies in adult patients with dermatomyositis (DM). Although pathogenesis of cancer-associated DM is unknown, TIF1γ overexpression in tumors has been considered to be critical for the development of DM. The objective of this study was to investigate clinical characteristics of patients with anti-TIF1γ Ab-positive DM and elucidate risk factors that are potentially associated with internal malignancy. In addition, we compared the expression of TIF1γ in tumor tissues of patients with anti-TIF1γ Ab-positive DM, anti-TIF1γ Ab-negative DM and without DM in order to investigate the pathogenesis of cancer-associated DM. We analyzed 77 Japanese patients with DM, and found 19 patients to be positive for anti-TIF1γ Ab. Patients with anti-TIF1γ Ab-positive DM were older and presented heliotrope rash and flagellate erythema more frequently than patients without anti-TIF1γ Ab (P < 0.05). Interstitial lung disease (ILD) and rapidly progressive ILD, as well as palmar violaceous erythema, were less frequent in patients with anti-TIF1γ Ab than in patients without. Furthermore, internal malignancy and dysphagia were significantly more frequent in the anti-TIF1γ Ab-positive group (P < 0.01). Male sex and dysphagia were significantly associated with internal malignancy in patients with anti-TIF1γ Ab-positive DM (P < 0.01 and <0.05, respectively). Using immunohistochemistry, we examined the TIF1γ expression in tumors of 11 patients with cancer-associated DM (anti-TIF1γ Ab-positive, nine; anti-TIF1γ Ab-negative, two) and 25 patients without DM. TIF1γ was highly expressed in all tumors, and there was no significant difference in TIF1γ expression between patients with and without DM. Furthermore, TIF1γ expressions in tumors were similar irrespective of the presence of anti-TIF1γ Ab. These results suggest that anti-TIF1γ antibody may not be simply induced by overexpression of TIF1γ in tumors in patients with DM, but that other mechanisms may exist.

TIF1 Proteins in Genome Stability and Cancer

Genomic instability is a hallmark of cancer cells which results in excessive DNA damage. To counteract this, cells have evolved a tightly regulated DNA damage response (DDR) to rapidly sense DNA damage and promote its repair whilst halting cell cycle progression. The DDR functions predominantly within the context of chromatin and requires the action of chromatin-binding proteins to coordinate the appropriate response. TRIM24, TRIM28, TRIM33 and TRIM66 make up the transcriptional intermediary factor 1 (TIF1) family of chromatin-binding proteins, a subfamily of the large tripartite motif (TRIM) family of E3 ligases. All four TIF1 proteins are aberrantly expressed across numerous cancer types, and increasing evidence suggests that TIF1 family members can function to maintain genome stability by mediating chromatin-based responses to DNA damage. This review provides an overview of the TIF1 family in cancer, focusing on their roles in DNA repair, chromatin regulation and cell cycle regulation.

Transcriptional intermediary factor 1 (TIF1) and anti-TIF1γ antibody-positive dermatomyositis

Recently, great advancements have been made towards understanding the mechanisms underlying dermatomyositis (DM). Many novel autoantibodies, such as anti-MDA5, anti-TIF1γ, anti-NXP2, and anti-SAE, have been reported to be involved in DM. DM is now classified based on these myositis-specific autoantibodies. Anti-TIF1γ antibodies are closely associated with juvenile DM and adult cancer-associated DM. Anti-TIF1γ antibody-positive DM tends to present severe cutaneous manifestations, mild myositis, and dysphagia. TIF1γ (also known as TRIM33) plays a role in transcriptional elongation, DNA repair, differentiation of cells, embryonic development, and mitosis. Moreover, TIF1γ has been shown to suppress various tumors via the TGF-β/Smad and the Wnt/β-Catenin signaling pathways. In this review, we explore the relationship between TIF1γ, cancer, and DM. We also discuss the pathogenesis of anti-TIF1γ antibody-positive DM.

Anti-TIF1-γ autoantibodies: warning lights of a tumour autoantigen

Anti-transcription intermediary factor 1 (TIF1)-γ autoantibodies are robustly linked with cancer-associated DM in adults. This review aims to give an overview of the physiological context of TIF1-γ and to determine whether there is a pathophysiological link between anti-TIF1-γ autoantibodies and the occurrence of cancer. Detection of anti-TIF1-γ autoantibodies has a high sensitivity and specificity for cancer-associated DM in adults and is therefore useful for both diagnosis and cancer risk stratification. The function of the autoantigen, TIF1-γ, may provide insight into the mechanism behind this association. TIF1-γ is a ubiquitously present protein involved in various biological pathways, including TGF-β signalling. In cancer, it can act either as a tumour suppressor or promoter, depending on the cellular context and cancer stage. Evolving data provide pathophysiological insights, linking anti-TIF1-γ autoantibodies to both the anti-tumour response and to muscle and skin damage. TIF1-γ expression is increased in muscle and skin tissue of patients with DM. Mutations or loss-of-heterozygosity in TIF1-γ alleles in malignant tissue may result in the expression of tumour-specific neo-antigens stimulating autoantibody production. The newly formed autoantibodies are hypothesized to cross-react with antigens in muscle and skin, driving the development of DM. Based on the current evidence, anti-TIF1-γ autoantibodies should be considered warning lights of a potential tumour autoantigen and should alert the physician to the possibility of an underlying cancer.

A Case of Dermatomyositis Along with Esophageal Cancer and Screening of Serum Transcriptional Intermediary Factor 1 Gamma Antibodies in Various Cancer Patients

Patient: Male, 70-year-old

Final Diagnosis: Esophageal cancer

Symptoms: Muscle pain • weaknes of lower limbs

Medication: —

Clinical Procedure: Biopsy of the skin

Specialty: Rheumatology

Emerging RNA-binding roles in the TRIM family of ubiquitin ligases

TRIM proteins constitute a large, diverse and ancient protein family which play a key role in processes including cellular differentiation, autophagy, apoptosis, DNA repair, and tumour suppression. Mostly known and studied through the lens of their ubiquitination activity as E3 ligases, it has recently emerged that many of these proteins are involved in direct RNA binding through their NHL or PRY/SPRY domains. We summarise the current knowledge concerning the mechanism of RNA binding by TRIM proteins and its biological role. We discuss how RNA-binding relates to their previously described functions such as E3 ubiquitin ligase activity, and we will consider the potential role of enrichment in membrane-less organelles.

The Roles of TIF1γ in Cancer

Transcriptional intermediary factor 1 γ (TIF1γ), also known as TRIM33, RFG7, PTC7, or Ectodermin, is an E3 ubiquitin-ligase family member with a ring-box-coiled-coil region. It can regulate TGF-β/Smad signaling in two different ways in different cellular contexts. On one hand, TIF1γ can monoubiquitinate Smad4 to inhibit the formation of Smad2/3/4 nuclear complexes. On the other hand, TIF1γ can function as a cofactor of phosphorylated (p)-Smad2/3, competing with Smad4 to inhibit the formation of the Smad2/3/4 complex. In addition, TIF1γ has been reported to play a role in transcription elongation, cellular differentiation, embryonic development, and mitosis. As transforming growth factor-β (TGF-β) superfamily signaling plays an important role in the occurrence and development of cancer, and TIF1γ was reported to be involved in the regulation of TGF-β superfamily signaling, studies on TIF1γ during the last decade have focused on its role in the development of cancer. However, TIF1γ can function either as a tumor suppressor or promoter in different cellular contexts, yet there are few reviews focusing on the roles of TIF1γ in cancer. Hence, in this paper we systematically review and discuss the roles of TIF1γ in cancer. Firstly, we review the biological features, the regulatory mechanisms and the related signaling pathways of TIF1γ. Next, we illustrate the roles of TIF1γ in different tumors. We then provide a tentative hypothesis that explains the dual roles of TIF1 γ in cancer. Finally, we provide our viewpoint regarding the future developments of cancer research focusing on TIF1γ, especially in relation to the effects of TIF1γ on tumoral immunity.

Circular RNA circTRIM33-12 acts as the sponge of MicroRNA-191 to suppress hepatocellular carcinoma progression

Background

Recently, the dysregulation of circular RNA (circRNA) have been shown to have important regulatory roles in cancer development and progression, including hepatocellular carcinoma (HCC). However, the roles of most circRNAs in HCC are still unknown.

Methods

The expression of circular tripartite motif containing 33–12 (circTRIM33–12) in HCC tissues and cell lines was detected by qRT-PCR. The role of circTRIM33–12 in HCC progression was assessed by western blotting, CCK-8, flow cytometry, transwell and a subcutaneous tumor mouse assays both in vitro and in vivo. In vivo circRNA precipitation, RNA immunoprecipitation, luciferase reporter assays were performed to evaluate the interaction between circTRIM33–12 and miR-191.

Results

Here, we found that circTRIM33–12, is downregulated in HCC tissues and cell lines. The downregulation of circTRIM33–12 in HCC was significantly correlated with malignant characteristics and served as an independent risk factor for the overall survival (OS) and recurrence-free survival (RFS) of patients with HCC after surgery. The reduced expression of circTRIM33–12 in HCC cells increases tumor proliferation, migration, invasion and immune evasion. Mechanistically, we demonstrated that circTRIM33–12 upregulated TET1 expression by sponging miR-191, resulting in significantly reduced 5-hydroxymethylcytosine (5hmC) levels in HCC cells.

Conclusions

These results reveal the important role of circTRIM33–12 in the proliferation, migration, invasion and immune evasion abilities of HCC cells and provide a new perspective on circRNAs in HCC progression.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1031-1) contains supplementary material, which is available to authorized users.

Trim33 is required for appropriate development of pre-cardiogenic mesoderm

Congenital cardiac malformations are among the most common birth defects in humans. Here we show that Trim33, a member of the Tif1 subfamily of tripartite domain containing transcriptional cofactors, is required for appropriate differentiation of the pre-cardiogenic mesoderm during a narrow time window in late gastrulation. While mesoderm-specific Trim33 mutants did not display noticeable phenotypes, epiblast-specific Trim33 mutant embryos developed ventricular septal defects, showed sparse trabeculation and abnormally thin compact myocardium, and died as a result of cardiac failure during late gestation. Differentiating embryoid bodies deficient in Trim33 showed an enrichment of gene sets associated with cardiac differentiation and contractility, while the total number of cardiac precursor cells was reduced. Concordantly, cardiac progenitor cell proliferation was reduced in Trim33-deficient embryos. ChIP-Seq performed using antibodies against Trim33 in differentiating embryoid bodies revealed more than 4000 peaks, which were significantly enriched close to genes implicated in stem cell maintenance and mesoderm development. Nearly half of the Trim33 peaks overlapped with binding sites of the Ctcf insulator protein. Our results suggest that Trim33 is required for appropriate differentiation of precardiogenic mesoderm during late gastrulation and that it will likely mediate some of its functions via multi-protein complexes, many of which include the chromatin architectural and insulator protein Ctcf.

Cellular TRIM33 restrains HIV-1 infection by targeting viral integrase for proteasomal degradation

Productive HIV-1 replication requires viral integrase (IN), which catalyzes integration of the viral genome into the host cell DNA. IN, however, is short lived and is rapidly degraded by the host ubiquitin-proteasome system. To identify the cellular factors responsible for HIV-1 IN degradation, we performed a targeted RNAi screen using a library of siRNAs against all components of the ubiquitin-conjugation machinery using high-content microscopy. Here we report that the E3 RING ligase TRIM33 is a major determinant of HIV-1 IN stability. CD4-positive cells with TRIM33 knock down show increased HIV-1 replication and proviral DNA formation, while those overexpressing the factor display opposite effects. Knock down of TRIM33 reverts the phenotype of an HIV-1 molecular clone carrying substitution of IN serine 57 to alanine, a mutation known to impair viral DNA integration. Thus, TRIM33 acts as a cellular factor restricting HIV-1 infection by preventing provirus formation.

HIV-1 integration into host DNA is mediated by the viral integrase (IN). Here, using siRNA screen and high-content microscopy, the authors identify the host E3 RING ligase TRIM33 to affect IN stability and show that TRIM33 prevents viral integration by triggering IN proteasome-mediated degradation.

Tumour TIF1 mutations and loss of heterozygosity related to cancer-associated myositis

Objectives

To analyse the influence of genetic alterations and differential expression of transcription intermediary factor 1 (TIF1) genes in the pathophysiology of cancer-associated myositis (CAM).

Methods

Paired blood and tumour DNA samples from patients with anti-TIF1γ-positive CAM and from controls were analysed by whole-exome sequencing for the presence of somatic mutations and loss of heterozygosity (LOH) in their TIF1 genes. The genesis and maintenance of the autoimmune process were investigated immunohistochemically by studying TIF1γ expression in the different tissues involved in CAM (skin, muscle and tumour) based on the immunohistochemical H-score.

Results

From seven patients with anti-TIF1γ-positive CAM, we detected one somatic mutation and five cases of LOH in one or more of the four TIF1 genes compared with just one case of LOH in tumours from TIF1γ-negative myositis patients (86% vs 17%; P = 0.03). Compared with type-matched control tumours from non-myositis patients, TIF1γ staining was more intense in tumours from anti-TIF1γ-positive patients (H-score 255 vs 196; P = 0.01). Also, TIF1γ staining in muscle was slightly more intense in anti-TIF1γ-positive than in anti-TIF1γ-negative myositis (H-score 22 vs 5; P = 0.03). In contrast, intense TIF1γ staining was detected in the skin of both myositis and control patients.

Conclusion

Tumours from paraneoplastic anti-TIF1γ-positive patients showed an increased number of genetic alterations, such as mutations and LOH, in TIF1 genes. These genetic alterations, in the context of a high expression of TIF1γ in the tumour, muscle and skin of these patients may be key to understanding the genesis of paraneoplastic myositis.

Anti-FIRs (PUF60) auto-antibodies are detected in the sera of early-stage colon cancer patients

Anti-PUF60, poly(U)-binding-splicing factor, autoantibodies are reported to be detected in the sera of dermatomyositis and Sjogren's syndrome that occasionally associated with malignancies. PUF60 is identical with far-upstream element-binding protein-interacting repressor (FIR) that is a transcriptional repressor of c-myc gene. In colorectal cancers, a splicing variant of FIR that lacks exon2 (FIRΔexon2) is overexpressed as a dominant negative form of FIR. In this study, to reveal the presence and the significance of anti-FIRs (FIR/FIRΔexon2) antibodies in cancers were explored in the sera of colorectal and other cancer patients. Anti-FIRs antibodies were surely detected in the preoperative sera of 28 colorectal cancer patients (32.2% of positive rates), and the detection rate was significantly higher than that in healthy control sera (Mann-Whitney U test, p < 0.01). The level of anti-FIRs antibodies significantly decreased after the operation (p < 0.01). Anti-FIRs antibodies were detected in the sera of early-stage and/or recurrent colon cancer patients in which anti-p53 antibodies, CEA, and CA19-9 were not detected as well as in the sera of other cancer patients. Furthermore, the area under the curve of receiver operating characteristic for anti-FIRs antibodies was significantly larger (0.85) than that for anti-p53 antibodies or CA19-9. In conclusions, the combination of anti-FIRs antibodies with other clinically available tumor markers further improved the specificity and accuracy of cancer diagnosis.

Biphasic regulation of spindle assembly checkpoint by low and high concentrations of resveratrol leads to the opposite effect on chromosomal instability

Resveratrol (RSV) is a naturally occurring polyphenolic phytoalexin possessing numerous health-promoting effects. Chromosomal instability (CIN), usually results from defective spindle assembly checkpoint (SAC), is a major contributor to many diseases. While it's recently recognized that RSV exhibits a nonlinear dose response for disease prevention, whether it's the case for its role in CIN remains unknown. Here, we investigated the potential of a broad range of RSV concentrations (0.01-100μM) on CIN and the underlying mechanisms in human normal colon epithelial NCM460 cells. CIN was measured by cytokinesis-block micronucleus assay; mitotic fidelity was determined by aberrant mitosis analysis; SAC activity was assessed by nocodazole-challenge assay, and the expression of SAC genes was examined by RT-qPCR. We found that 0.1μM RSV significantly reduced CIN (P<0.01), while 100μM RSV significantly induced it (P<0.05). Mitotic infidelity was significantly prevented by 0.1μM RSV but promoted by 100μM RSV (P<0.05 for both). Moreover, the function of SAC was sustained and impaired by 0.1μM and 100μM RSV, respectively. Several SAC genes, including Aurora-B, Aurora-C, Plk-1 and CENP-E, were significantly up-regulated and down-regulated by 0.1μM and 100μM RSV, respectively (P<0.05). In conclusion, RSV exhibited a biphasic dose-dependent effect on CIN that was exerted via the regulation of mitotic fidelity through the SAC network. The health implications of these findings were summarized.

Dermatomyositis and Immune-Mediated Necrotizing Myopathies: A Window on Autoimmunity and Cancer

Autoimmune myopathies (myositides) are strongly associated with malignancy. The link between myositis and cancer, originally noticed by Bohan and Peter in their classification in 1975 (1), has been evidenced by large population-based cohort studies and a recent meta-analysis. The numerous reports of cases in which the clinical course of myositis reflects that of cancer and the short delay between myositis and cancer onset support the notion that myositis may be an authentic paraneoplastic disorder. Thus, cancer-associated myositis raises the question of cancer as a cause rather than a consequence of autoimmunity. Among myositides, dermatomyositis and more recently, although to a lesser extent, immune-mediated necrotizing myopathies are the most documented forms associated with cancer. Interestingly, the current diagnostic approach for myositis is based on the identification of specific antibodies where each antibody determines specific clinical features and outcomes. Recent findings have shown that the autoantibodies anti-TIF1γ, anti-NXP2 and anti-HMGCR are associated with cancers in the course of myositis. Herein, we highlight the fact that the targets of these three autoantibodies involve cellular pathways that intervene in tumor promotion and we discuss the role of cancer mutations as autoimmunity triggers in adult myositis.

TRIM33 is essential for osteoblast proliferation and differentiation via BMP pathway

Tripartite motif containing 33 (TRIM33) functions both as a positive and negative regulator of the TGF-β/BMP pathway in tumors; however, its effect and mechanism during osteoblast proliferation and differentiation, which involves the TGF-β/BMP pathway is not defined. In this study, we used mouse C3H10T1/2 mesenchymal stem cell line and MC3T3-E1 preosteoblasts to investigate the role of TRIM33 during this process. The results demonstrated that the expression of TRIM33 increased during the differentiation. Moreover, the overexpression or knockdown of TRIM33 resulted in both an augmentation or decrease in osteoblast differentiation, which were measured by the expression of alkaline phosphatase (ALP) at the mRNA level, both Runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) at the protein level, and the formation of mineral modules. To further demonstrate the mechanism of TRIM33 in this process, we found that TRIM33 could positively mediate the BMP pathway by forming TRIM33-Smad1/5 complex. This interaction between TRIM33 and Smad1/5 triggered the phosphorylation of Smad1/5. In addition, the essential role of TRIM33 in osteoblast proliferation was determined in this study by CellCounting Kit (CCK) -8 and cell cycle assays. In summary, we establish the function of TRIM33 as a positive regulator of osteoblast differentiation in BMP pathway, which mediates its effect through its interaction with and activation of Smad1/5. In addition, the results clearly demonstrate that TRIM33 is necessary for osteoblast proliferation by regulating cell cycle. These results suggest that TRIM33 can be a positive target of osteoblast proliferation and differentiation through BMP pathway.

SNX9 promotes metastasis by enhancing cancer cell invasion via differential regulation of RhoGTPases

Despite current advances in cancer research, metastasis remains the leading factor in cancer-related deaths. Here, we identify sorting nexin 9 (SNX9) as a new regulator of breast cancer metastasis. We detected an increase in SNX9 expression in human breast cancer metastases compared with primary tumors and demonstrated that SNX9 expression in MDA-MB-231 breast cancer cells is necessary to maintain their ability to metastasize in a chick embryo model. Reciprocally, SNX9 knockdown impairs the process. In vitro studies using several cancer cell lines derived from a variety of human tumors revealed a role for SNX9 in cell invasion and identified mechanisms responsible for this novel function. We showed that SNX9 controls the activation of RhoA and Cdc42 GTPases and also regulates cell motility via the modulation of well-known molecules involved in metastasis, namely RhoA-ROCK and N-WASP. In addition, we have discovered that SNX9 is required for RhoGTPase-dependent, clathrin-independent endocytosis, and in this capacity, can functionally substitute to the bona fide Rho GAP, GRAF1 (GTPase Regulator Associated with Focal Adhesion Kinase). Together, our data establish novel roles for SNX9 as a multifunctional protein scaffold that regulates, and potentially coordinates, several cellular processes that together can enhance cancer cell metastasis.