Conserved structural and functional aspects of the tripartite motif gene family point towards therapeutic applications in multiple diseases

TRIM50 acts as a novel Src suppressor and inhibits ovarian cancer progression

Src is a known proto-oncogene and its aberrant activity is involved in a variety of cancers, including ovarian cancer, whereas the regulatory mechanism of Src has not been fully clarified. In this study, we identified tripartite motif-containing (TRIM) 50 as a novel negative regulator of Src protein. Our data showed that TRIM50 directly interacted with SH3 domain of Src via its B-box domain; and TRIM50 reduced Src stability by inducing RING domain-dependent K48-linked poly-ubiquitous modification. We further demonstrated that TRIM50 acted as a tumor suppressor in ovarian cancer cells by its negative regulation of Src protein. In vivo animal model verified that TRIM50 inhibited the xenograft tumor growth of ovarian cancer by suppressing Src protein. Clinical investigation showed that expression of TRIM50 in clinical specimens was inversely correlated with the clinical stages, pathology grades and lymph node metastatic status of the patients, which indicated the involvement of aberrant TRIM50 expression in disease progression. Further analysis verified the negative correlation between TRIM50 and Src expression in clinical specimens. Altogether, we identified TRIM50 as a novel suppressor of Src protein, and demonstrated that TRIM50 inhibited ovarian cancer progression by targeting Src and reducing its activity, which provided a novel therapeutic strategy for Src over-activated cancers by positive regulation of TRIM50.

E3 Ubiquitin Ligase TRIM Proteins, Cell Cycle and Mitosis

The cell cycle is a series of events by which cellular components are accurately segregated into daughter cells, principally controlled by the oscillating activities of cyclin-dependent kinases (CDKs) and their co-activators. In eukaryotes, DNA replication is confined to a discrete synthesis phase while chromosome segregation occurs during mitosis. During mitosis, the chromosomes are pulled into each of the two daughter cells by the coordination of spindle microtubules, kinetochores, centromeres, and chromatin. These four functional units tie chromosomes to the microtubules, send signals to the cells when the attachment is completed and the division can proceed, and withstand the force generated by pulling the chromosomes to either daughter cell. Protein ubiquitination is a post-translational modification that plays a central role in cellular homeostasis. E3 ubiquitin ligases mediate the transfer of ubiquitin to substrate proteins determining their fate. One of the largest subfamilies of E3 ubiquitin ligases is the family of the tripartite motif (TRIM) proteins, whose dysregulation is associated with a variety of cellular processes and directly involved in human diseases and cancer. In this review we summarize the current knowledge and emerging concepts about TRIMs and their contribution to the correct regulation of cell cycle, describing how TRIMs control the cell cycle transition phases and their involvement in the different functional units of the mitotic process, along with implications in cancer progression.

TRIM47 is up-regulated in colorectal cancer, promoting ubiquitination and degradation of SMAD4

Background

Tripartite motif 47 (TRIM47), a member of the TRIM family proteins, plays a key role in many types of cancers including colorectal cancer (CRC). We found that levels of TRIM47 mRNA and protein were increased significantly in colorectal tumors compared with nontumor tissues and the increased levels were associated with advanced tumor stage and poor outcome.

Methods

We used quantitative polymerase chain reaction and western blot to measure levels of TRIM47 mRNA and protein in human colorectal cancer and paired normal tissues. TRIM47 was knocked down and overexpressed in colorectal cancer cells, and the effects on cell proliferation, migration and growth of xenograft tumors in nude mice were assessed. The signaling pathways were examined by western blot and immunoprecipitation assays.

Results

TRIM47 promoted CRC proliferation and metastasis in vitro and in vivo as an oncogene. Mechanistically, TRIM47 interacted physically with SMAD4, increasing its ubiquitination and degradation. Loss of SMAD4 leaded to up-regulation of CCL15 expression and caused growth and invasion in human CRC cells through the CCL15-CCR1 signaling. Moreover, TRIM47 overexpression played a role in CRC chemoresistance in response to 5-FU therapy.

Conclusions

Our study demonstrated a functional role of the TRIM47-SMAD4-CCL15 axis in CRC progression and suggested a potential target for CRC therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1143-x) contains supplementary material, which is available to authorized users.

High expression of TRIM36 is associated with radiosensitivity in gastric cancer

Radiotherapy is one of the main adjuvant treatments for gastric cancer (GC) that can effectively reduce local recurrence and improve survival rates. However, radiotherapy may result in cytotoxicity and not benefit all patients. This highlights the requirement for identifying potential radiosensitivity genes in GC. The current study investigated the association between tripartite motif containing 36 (TRIM36) status and the prognosis of patients with GC receiving radiotherapy. A total of 371 patients with GC were selected from The Cancer Genome Atlas and randomly divided into test and the validation groups. The results revealed that TRIM36 expression was not associated with the overall survival (OS) rate. Patients who received radiotherapy with high TRIM36 expression had an improved OS rate compared with patients who did not receive radiotherapy in the test group, as demonstrated by univariate analysis [hazard ratio (HR), 0.062; 95% confidence interval (CI), 0.008–0.462; P=0.007] and multivariate analysis (HR, 0.095; 95% CI, 0.012–0.748; P=0.025). In the validation group, patients with high TRIM36 expression had decreased mortality risk when they received radiotherapy compared with patients who did not receive radiotherapy, as determined by univariate analysis (HR, 0.190; 95% CI, 0.067–0.540; P=0.002) and multivariate analysis (HR, 0.075; 95% CI, 0.020–0.276; P<0.001). However, for patients with low expression, no significant difference was identified in the overall survival rates between the radiotherapy and non-radiotherapy groups. Chi-squared analysis revealed that the expression status of TRIM36 was an independent factor and was not associated with clinicopathological factors. The results indicated that patients with high TRIM36 expression receiving radiotherapy exhibited an improved OS rate. TRIM36 may therefore be an important factor affecting the clinical prognosis of patients with GC receiving radiotherapy and may be considered as a potential radiosensitivity gene signature.

The two TRIM25 isoforms were differentially induced in Larimichthys crocea post poly (I:C) stimulation

In this study, we identified and characterized a tripartite motif containing 25 (TRIM25) gene homologue, LcTRIM25, from large yellow croaker (Larimichthys crocea). Two isoforms of LcTRIM25, which were generated via alternative splicing, were identified via a molecular analysis of cDNA clones. The long isoform of LcTRIM25 (termed as LcTRIM25-L) contained the full open reading frame of the gene, encoded a protein of 698 amino acid residues, and possessed 11 exons. The short isoform of LcTRIM25 (termed as LcTRIM25-S) contained 9 exons and encoded a protein of 665 amino acid residues. The two LcTRIM25 isoforms contained a conserved Really Interesting New Gene (RING) domain, a B-box2 domain, a Coiled-coil domain (CCD), and variable C-terminal PRY/SPRY domains. Phylogenetic analysis showed that the two LcTRIM25 isoforms of the large yellow croaker was clustered together with their counterparts from other teleost fish. The Real-time PCR analysis showed that the LcTRIM25-L and LcTRIM25-S isoforms were both ubiquitously expressed in nine examined tissues in the large yellow croaker, with predominant expressions in the liver. The expression levels of the two isoforms of LcTRIM25 were rapidly and significantly upregulated in vivo after poly (I:C) stimulation in peripheral blood, head kidney, spleen and liver. Moreover, LcTRIM25-L and LcTRIM25-S showed differential expression post poly(I:C) stimulation. LcTRIM25 may have a dual role in innate immunity via alternative gene splicing. These results indicated that LcTRIM25 is likely to be involved in antiviral immune responses.

Expression and Significance of TRIM 28 in Squamous Carcinoma of Esophagus

Tripartite motif-containing protein 28 (TRIM28) has been proved to accelerate cell proliferation and metastasis in a variety of human cancers. However, the role of TRIM28 in esophageal squamous cell carcinoma (ESCC) remains unclear. In this study, to compare the biological effect and significance of TRIM28 expression in ESCC, immunohistochemistry (streptavidin-perosidase, S-P) method was used firstly to examine the expression of TRIM28 in 136 cases of ESCC, 35 cases of high grade intraepithelial neoplasia (HGIN), 29 cases of low grade intraepithelial neoplasia (LGIN) and 37 cases of normal esophageal epithelium (NEE). Then the associations of TRIM28 expression with clinicopathological data and overall survival (OS) were also analyzed. Western blot was performed to evaluate TRIM28 protein in a total of 20 matched human ESCC and NEE tissues. Moreover, the localization of TRIM28 protein in ESCC and NEE tissues was also detected by immunofluorescence. TRIM28 protein was mainly distributed in the nucleus of ESCC. The expression of TRIM28 increased progressively from NEE to LGIN, to HGIN, and to ESCC, and it was also related to invasive depth, pTNM stage and lymph node metastasis in ESCC (P < 0.05). The results of western blot and immunofluorescence all showed that the relative expression of TRIM28 protein was markedly upregulated in ESCC compared with the NEE tissues (P < 0.01). However, prognostic analysis showed that TRIM28 may not be a prognostic factor of patients with ESCC. In conclusion, the overexpression of TRIM28 may play an important role for development and metastasis in ESCC.