Tripartite motif 16 suppresses breast cancer stem cell properties through regulation of Gli-1 degradation via the ubiquitin-proteasome pathway

Emerging roles of tripartite motif family proteins (TRIMs) in breast cancer

Breast cancer (BC) is the most common malignant tumor worldwide. Despite enormous progress made in the past decades, the underlying mechanisms of BC remain further illustrated. Recently, TRIM family proteins proved to be engaged in BC progression through regulating various aspects. Here we reviewed the structures and basic functions of TRIM family members and first classified them into three groups according to canonical polyubiquitination forms that they could mediate: K48- only, K63- only, and both K48- and K63-linked ubiquitination. Afterwards, we focused on the specific biological functions and mechanisms of TRIMs in BCs, including tumorigenesis and invasiveness, drug sensitivity, tumor immune microenvironment (TIME), cell cycle, and metabolic reprogramming. We also explored the potential of TRIMs as novel biomarkers for predicting prognosis and future therapeutic targets in BC.

Phosphorylation of human glioma-associated oncogene 1 on Ser937 regulates Sonic Hedgehog signaling in medulloblastoma

Aberrant activation of sonic hedgehog (SHH) signaling and its effector transcriptional factor GLI1 are essential for oncogenesis of SHH-dependent medulloblastoma (MBSHH) and basal cell carcinoma (BCC). Here, we show that SHH inactivates p38α (MAPK14) in a smoothened-dependent manner, conversely, p38α directly phosphorylates GLI1 on Ser937/Ser941 (human/mouse) to induce GLI1's proteasomal degradation and negates the transcription of SHH signaling. As a result, Gli1S941E loss-of-function knock-in significantly reduces the incidence and severity of smoothened-M2 transgene-induced spontaneous MBSHH, whereas Gli1S941A gain-of-function knock-in phenocopies Gli1 transgene in causing BCC-like proliferation in skin. Correspondingly, phospho-Ser937-GLI1, a destabilized form of GLI1, positively correlates to the overall survival rate of children with MBSHH. Together, these findings indicate that SHH-induced p38α inactivation and subsequent GLI1 dephosphorylation and stabilization in controlling SHH signaling and may provide avenues for future interventions of MBSHH and BCC.

Intricate confrontation: Research progress and application potential of TRIM family proteins in tumor immune escape

BACKGROUND

Tripartite motif (TRIM) family proteins have more than 80 members and are widely found in various eukaryotic cells. Most TRIM family proteins participate in the ubiquitin-proteasome degradation system as E3-ubiquitin ligases; therefore, they play pivotal regulatory roles in the occurrence and development of tumors, including tumor immune escape. Due to the diversity of functional domains of TRIM family proteins, they can extensively participate in multiple signaling pathways of tumor immune escape through different substrates. In current research and clinical contexts, immune escape has become an urgent problem. The extensive participation of TRIM family proteins in curing tumors or preventing postoperative recurrence and metastasis makes them promising targets.

AIM OF REVIEW

The aim of the review is to make up for the gap in the current research on TRIM family proteins and tumor immune escape and propose future development directions according to the current progress and problems.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This up-to-date review summarizes the characteristics and biological functions of TRIM family proteins, discusses the mechanisms of TRIM family proteins involved in tumor immune escape, and highlights the specific mechanism from the level of structure-function-molecule-pathway-phenotype, including mechanisms at the level of protein domains and functions, at the level of molecules and signaling pathways, and at the level of cells and microenvironments. We also discuss the application potential of TRIM family proteins in tumor immunotherapy, such as possible treatment strategies for combination targeting TRIM family protein drugs and checkpoint inhibitors for improving cancer treatment.

TRIM16 E121D variant affects the risk and prognosis of hepatocellular carcinoma by modulating the Wnt/β-catenin pathway

TRIM16 has been identified as a tumor suppressor in hepatocellular carcinoma (HCC). This study aimed to investigate whether there are genetic variants in TRIM16 influencing HCC risk and/or prognosis and explore the mechanisms. We performed a gene-wide single-nucleotide polymorphism (SNP) mining in TRIM16. The associations of SNPs with both HCC risk and prognosis were assessed through two independent cohorts respectively. Functional experiments were performed to investigate the underlying mechanisms. A missense variant rs2074890 (G > T, resulting in an amino acid substitution from glutamate to aspartate at code 121, E121D) of TRIM16 was found to be associated with both HCC risk (odds ratio = 0.806, p = 0.023) and prognosis (hazard ratio = 0.44, p = 0.034). Compared to the rs2074890 G allele (corresponding to TRIM16121E ) homozygote carriers, the rs2074890 T allele (corresponding to TRIM16121D ) carriers showed lower HCC risk and better overall survival. Mechanistically, TRIM16121D has stronger ability to inhibit proliferation, migration, and invasion of HCC cells. Furthermore, TRIM16121D could bind to β-catenin better and mediate K48-linked ubiquitination to degrade β-catenin, which leads to inhibition of Wnt/β-catenin pathway. In conclusion, TRIM16 E121D variant impacts both risk and prognosis of HCC via regulation of Wnt/β-catenin pathway, which may lead to better understanding the pathogenesis of HCC.

LncRNA OTUD6B-AS1 overexpression promoted GPX4-mediated ferroptosis to suppress radioresistance in colorectal cancer

BACKGROUND

Radiotherapy is widely employed in colorectal cancer (CRC) treatment but is often compromised by developed radioresistance. This study explored the mechanism of long non-coding RNA ovarian tumor domain containing 6B-antisense RNA1 (lncRNA OTUD6B-AS1) in CRC radioresistance through tripartite motif 16 (TRIM16).

METHODS

CRC and non-cancerous tissues were collected and radioresistant CRC cells were established, with real-time quantitative polymerase chain reaction to determine gene expression in tissues and cells. Radioresistance was evaluated by cell counting kit-8 assay and immunofluorescence (γ-H2AX) and ferroptosis was tested by Western blot assay (ACSL4/GPX4) and assay kits (Fe2+/ROS/MDA/GSH). The association between ferroptosis and lncRNA OTUD6B-AS1-inhibited radioresistance was testified using ferroptosis inhibitor. The subcellular localization of lncRNA OTUD6B-AS1 was tested by the nuclear/cytoplasmic fractionation assay, with RNA immunoprecipitation assay to validate gene interactions. Rescue experiments were conducted to analyze the role of TRIM16 in CRC radioresistance.

RESULTS

LncRNA OTUD6B-AS1 and TRIM16 were poorly expressed (P < 0.01) in CRC tissues and cells and further decreased (P < 0.01) in radioresistant CRC cells. OTUD6B-AS1 overexpression decreased cell survival (P < 0.01), increased γ-H2AX levels (P < 0.01), and elevated ferroptosis and oxidative stress (P < 0.01) after X-ray radiation. Ferroptosis inhibitor attenuated radioresistance (P < 0.01) caused by lncRNA OTUD6B-AS1 overexpression. LncRNA OTUD6B-AS1 stabilized TRIM16 mRNA via binding to HuR. TRIM16 knockdown reduced ferroptosis and increased radioresistance (P < 0.05).

CONCLUSION

OTUD6B-AS1 overexpression stabilized TRIM16 via binding to HuR and increased GPX4-mediated ferroptosis, thus attenuating CRC radioresistance. Our study provided a new rationale for the treatment of CRC.

E3 ubiquitin ligases in cancer stem cells: key regulators of cancer hallmarks and novel therapeutic opportunities

BACKGROUND

Human malignancies are composed of heterogeneous subpopulations of cancer cells with phenotypic and functional diversity. Among them, a unique subset of cancer stem cells (CSCs) has both the capacity for self-renewal and the potential to differentiate and contribute to multiple tumor properties. As such, CSCs are promising cellular targets for effective cancer therapy. At the molecular level, hyper-activation of multiple stemness regulatory signaling pathways and downstream transcription factors play critical roles in controlling CSCs establishment and maintenance. To regulate CSC properties, these stemness pathways are controlled by post-translational modifications including, but not limited to phosphorylation, acetylation, methylation, and ubiquitination.

CONCLUSION

In this review, we focus on E3 ubiquitin ligases and their roles and mechanisms in regulating essential hallmarks of CSCs, such as self-renewal, invasion and metastasis, metabolic reprogramming, immune evasion, and therapeutic resistance. Moreover, we discuss emerging therapeutic approaches to eliminate CSCs through targeting E3 ubiquitin ligases by chemical inhibitors and proteolysis-targeting chimera (PROTACs) which are currently under development at the discovery, preclinical, and clinical stages. Several outstanding issues such as roles for E3 ubiquitin ligases in heterogeneity and phenotypical/functional evolution of CSCs remain to be studied under pathologically and clinically relevant conditions. With the rapid application of functional genomic and proteomic approaches at single cell, spatiotemporal, and even single molecule levels, we anticipate that more specific and precise functions of E3 ubiquitin ligases will be delineated in dictating CSC properties. Rational design and proper translation of these mechanistic understandings may lead to novel therapeutic modalities for cancer procession medicine.

TRIM proteins in breast cancer: Function and mechanism

Breast cancer is the most prevalent malignancy in the world, and despite tremendous progress in current treatment strategies, recurrence, metastasis and drug resistance of breast cancer remain the major causes of death in patients. Tripartite motif (TRIM) family proteins play a critical role in the tumor progression such as cell proliferation, migration, invasion, and metastasis. Accumulating evidence suggests that the TRIM protein family serve as cancer suppressor proteins or oncoproteins in breast cancer. This review focused on the roles and molecular mechanisms of TRIM protein in breast cancer. Importantly, it provides new insights that TRIM proteins may be ideal targets to treat breast cancer.

Altered Expression of TRIM Proteins - Inimical Outcome and Inimitable Oncogenic Function in Breast Cancer with Diverse Carcinogenic Hallmarks

Deregulation of ubiquitin-mediated degradation of oncogene products or tumor suppressors appears to be implicated in the genesis of carcinomas, according to new clinical findings. Conferring to recent research, some members of the tripartite motif (TRIM) proteins (a subfamily of the RING type E3 ubiquitin ligases) act as significant carcinogenesis regulators. Intracellular signaling, development, apoptosis, protein quality control, innate immunity, autophagy, and carcinogenesis are all regulated by TRIM family proteins, the majority of which have E3 ubiquitin ligase activity. The expression of TRIMs in tumors is likely to be related to the formation and/or progression of the disease, and TRIM expression could be used to predict cancer prognosis. Breast cancer is the most common malignancy in women and also the leading cause of death. TRIM family proteins have unique, vital activities, and their dysregulation, such as TRIM 21, promotes breast cancer, according to growing evidence. Many TRIM proteins have been identified as important cancer biomarkers, with decreased or elevated levels of expression. TRIM29 functions as a hypoxia-induced tumor suppressor gene, revealing a new molecular mechanism for ATM-dependent breast cancer suppression. In breast cancer cells, the TRIM28-TWIST1-EMT axis exists, and TRIM28 enhances breast cancer metastasis by stabilizing TWIST1, and thereby increasing epithelial-tomesenchymal transition. Interestingly, many TRIM proteins are involved in the control of p53, and many TRIM proteins are likewise regulated by p53, according to current research. Furthermore, TRIMs linked to specific tumors may aid in the creation of innovative TRIM-targeted cancer treatments. This review focuses on TRIM proteins that are involved in tumor development, progression, and are of clinical significance in breast cancer.

TRIM3 and TRIM16 as potential tumor suppressors in breast cancer patients

Objective

Breast cancer is the leading cause of death among women in many countries. Numerous factors serve as oncogenes or tumor suppressors in breast cancer. The large family of Tripartite-motif (TRIM) proteins with ~ 80 members has drawn attention for their role in cancer. TRIM3 and TRIM16 have shown suppressive activity in different cancers. This study aimed to evaluate the expression of TRIM3 and TRIM16 in cancerous and normal breast samples and to investigate their association with different clinical and pathological parameters.

Results

qRT-PCR was utilized to determine the gene expression of TRIM3 and TRIM16. The expression of TRIM3 and TRIM16 genes in tumor samples were significantly reduced to 0.45 and 0.29 fold, respectively. TRIM3 and TRIM16 genes expression were both positively correlated with the invasion of breast cancer. TRIM3 gene expression was associated with tumors’ histological grade. However, no significant association was found between the expression of the genes and tumor size, stage and necrosis. The expression of TRIM3 and TRIM16 are significantly reduced in breast cancer tissues. Besides, the expression of both TRIM3 and TRIM16 genes significantly plummet in lymphatic/vascular and perineural invasive samples. Hence, we suggest a potential tumor suppressor role for TRIM3 and TRIM16 in breast cancer.

Advances in Biomarkers and Endogenous Regulation of Breast Cancer Stem Cells

Breast cancer is one of the most common cancers. Even if breast cancer patients initially respond to treatment, developed resistance can lead to a poor prognosis. Cancer stem cells (CSCs) are a group of undifferentiated cells with self-renewal and multipotent differentiation characteristics. Existing evidence has shown that CSCs are one of the determinants that contribute to the heterogeneity of primary tumors. The emergence of CSCs causes tumor recurrence, metastasis, and therapeutic resistance. Previous studies indicated that different stemness-associated surface markers can identify other breast cancer stem cell (BCSC) subpopulations. Deciphering the critical signaling networks that are involved in the induction and maintenance of stemness is essential to develop novel BCSC-targeting strategies. In this review, we reviewed the biomarkers of BCSCs, critical regulators of BCSCs, and the signaling networks that regulate the stemness of BCSCs.

CircPTK2 inhibits cell cisplatin (CDDP) resistance by targeting miR-942/TRIM16 axis in non-small cell lung cancer (NSCLC)

In recent years, the problem of cancer resistance has become more and more prominent, seriously affecting treatment efficiency. Circular RNAs (circRNAs) play an important role in cell progression and cancer mechanisms. However, there is a lack of systematic studies on its function in non-small cell lung cancer (NSCLC) resistance. CircPTK2, microRNA-942 (miR-942), and Tripartite motif 16 (TRIM16) levels were detected by Real-time quantitative reverse transcriptase PCR (qRT-PCR). Extracellular acidification rate (ECAR), glucose consumption, and lactate production were assessed using the Seahorse XF96 Glycolysis Analyzer, glucose, and lactate assay kits, respectively. The protein expression was measured with the western bolt Transwell assay was used to determine migration and invasion of transfected cells. (4-5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry were applied to carry out cell proliferation and apoptosis, respectively. The relationship among circPTK2, miR-942, and TRIM16 were determined by using the dual-luciferase reporter assay and RIP assay. circPTK2 (hsa_circ_0008305) and TRIM16 were low expressed, while miR-942 was significantly highly expressed in NSCLC tissues and cell lines. Moreover, overexpression of circPTK2 remarkably inhibited cell growth, metastasis, and glycolysis in A549/CDDP and H1299/CDDP cells. Promotion of miR-942 or inhibition of TRIM16 could reverse the effects of high circPTK2 expression on cell growth, metastasis, and glycolysis in A549/CDDP and H1299/CDDP cells. CircPTK2 overexpression inhibited the growth of A549/CDDP cells in vivo. Furthermore, circPTK2 weakened CDDP resistance of NSCLC through modulating miR-942/TRIM16 axis, providing a novel sight for the treatment of NSCLC and improving the understanding of the CDDP resistance mechanism of NSCLC.

Tripartite motif-containing protein 16 protects against myocardial ischemia/reperfusion injury by affecting the Keap1/Nrf2 axis

Tripartite motif-containing protein (TRIM16) is a newly identified oxidative-stress-responsive protein. Oxidative stress is a hallmark of myocardial ischemia/reperfusion (I/R) injury and contributes to the cardiac injury. To date, whether TRIM16 plays a role in mediating oxidative stress during myocardial I/R injury is undetermined. The work is devoted to evaluate the possible relevance of TRIM16 in myocardial I/R injury. TRIM16 induction by myocardial hypoxia/reoxygenation (H/R) injury in vitro or myocardial I/R injury in vivo was observed. TRIM16 overexpression alleviated H/R-induced injury of rat cardiomyocytes. TRIM16 overexpression markedly attenuated cardiac injury, infarct size, and myocardial apoptosis induced by myocardial I/R injury. Further research revealed that TRIM16 was capable of enhancing Nrf2 activation via the regulation of Keap1. The inhibition of Nrf2 diminished TRIM16-overexpression-mediated cardioprotective effects. Overall, this work demonstrates that TRIM16 protects against myocardial I/R injury via affecting the Keap1/Nrf2 axis. This work offers new insights into the molecular mechanism underlying myocardial I/R injury and proposes TRIM16 as an attractive candidate target for cardioprotection.

TRIM16 overexpression inhibits the metastasis of colorectal cancer through mediating Snail degradation

Tripartite motif containing 16 (TRIM16) is a member of the tripartite motif protein family and functions as a potential tumor suppressor in several cancers. However, the specific function and clinical significance of TRIM16 in colorectal cancer (CRC) remains unclear. In this study, we observed that low TRIM16 expression was detected frequently in primary colorectal cancer (CRC) tissues and was closely associated with a better prognosis. Functional studies demonstrate that TRIM16 overexpression notably inhibits the metastasis abilities of CRC in vivo and in vitro. Mechanistically, our results demonstrated that TRIM16 directly bound and ubiquitinated Snail family transcriptional repressor 1 (Snail), an important transcriptional factor of the epithelial-mesenchymal transition (EMT) process suppressing the EMT in CRC. Additionally, our data revealed that the inhibition effect of TRIM16 on cancer metastasis was dependent on Snail degradation. Collectively, our study is the first to report that TRIM16 plays a crucial anti-tumor role in CRC tumorigenesis. We also provided novel evidence that TRIM16 might act as a prognostic and therapeutic target to assess and inhibit CRC progression.

TRIMming Down Hormone-Driven Cancers: The Biological Impact of TRIM Proteins on Tumor Development, Progression and Prognostication

The tripartite motif (TRIM) protein family is attracting increasing interest in oncology. As a protein family based on structure rather than function, a plethora of biological activities are described for TRIM proteins, which are implicated in multiple diseases including cancer. With hormone-driven cancers being among the leading causes of cancer-related death, TRIM proteins have been described to portrait tumor suppressive or oncogenic activities in these tumor types. This review describes the biological impact of TRIM proteins in relation to hormone receptor biology, as well as hormone-independent mechanisms that contribute to tumor cell biology in prostate, breast, ovarian and endometrial cancer. Furthermore, we point out common functions of TRIM proteins throughout the group of hormone-driven cancers. An improved understanding of the biological impact of TRIM proteins in cancer may pave the way for improved prognostication and novel therapeutics, ultimately improving cancer care for patients with hormone-driven cancers.

The translational values of TRIM family in pan-cancers: From functions and mechanisms to clinics

Cancer is the second leading cause of human death across the world. Tripartite motif (TRIM) family, with E3 ubiquitin ligase activities in majority of its members, is reported to be involved in multiple cellular processes and signaling pathways. TRIM proteins have critical effects in the regulation of biological behaviors of cancer cells. Here, we discussed the current understanding of the molecular mechanism of TRIM proteins regulation of cancer cells. We also comprehensively reviewed published studies on TRIM family members as oncogenes or tumor suppressors in the oncogenesis, development, and progression of a variety of types of human cancers. Finally, we highlighted that certain TRIM family members are potential molecular biomarkers for cancer diagnosis and prognosis, and potential therapeutic targets.

TRIM Proteins in Colorectal Cancer: TRIM8 as a Promising Therapeutic Target in Chemo Resistance

Colorectal cancer (CRC) represents one of the most widespread forms of cancer in the population and, as all malignant tumors, often develops resistance to chemotherapies with consequent tumor growth and spreading leading to the patient’s premature death. For this reason, a great challenge is to identify new therapeutic targets, able to restore the drugs sensitivity of cancer cells. In this review, we discuss the role of TRIpartite Motifs (TRIM) proteins in cancers and in CRC chemoresistance, focusing on the tumor-suppressor role of TRIM8 protein in the reactivation of the CRC cells sensitivity to drugs currently used in the clinical practice. Since the restoration of TRIM8 protein levels in CRC cells recovers chemotherapy response, it may represent a new promising therapeutic target in the treatment of CRC.

The Tripartite Nexus: Autophagy, Cancer, and Tripartite Motif-Containing Protein Family Members

Autophagy is a cellular degradative process that has multiple important actions in cancer. Autophagy modulation is under consideration as a promising new approach to cancer therapy. However, complete autophagy dysregulation is likely to have substantial undesirable side effects. Thus, more targeted approaches to autophagy modulation may prove clinically beneficial. One potential avenue to achieving this goal is to focus on the actions of tripartite motif-containing protein family members (TRIMs). TRIMs have key roles in an array of cellular processes, and their dysregulation has been extensively linked to cancer risk and prognosis. As detailed here, emerging data shows that TRIMs can play important yet context-dependent roles in controlling autophagy and in the selective targeting of autophagic substrates. This review covers how the autophagy-related actions of TRIM proteins contribute to cancer and the possibility of targeting TRIM-directed autophagy in cancer therapy.

The role of TRIM family proteins in the regulation of cancer stem cell self-renewal

The tripartite-motif (TRIM) family of proteins represents one of the largest classes of putative single protein RING-finger E3 ubiquitin ligases. The members of this family are characterized by an N-terminal TRIM motif containing one RING-finger domain, one or two zinc-finger domains called B boxes (B1 box and B2 box), and a coiled-coil region. The TRIM motif can be found in isolation or in combination with a variety of C-terminal domains, and based on C-terminus, TRIM proteins are classified into 11 distinct groups. Because of the complex nature of TRIM proteins, they are implicated in a variety of cellular functions and biological processes, including regulation of cell proliferation, cell division and developmental processes, cancer transformation, regulation of cell metabolism, autophagocytosis, modification of chromatin status, regulation of gene transcription, post-translational modifications, and interactions with pathogens. Here, we demonstrate the specific activities of TRIM family proteins that contribute to the cancer stem cell phenotype. A growing body of evidence demonstrates that several TRIM members guarantee the acquisition of stem cell properties and the ability to sustain stem-like phenotype by cancer cells using distinct mechanisms. For other members, further work is needed to understand their full contribution to stem cell self-renewal. Identification of TRIM proteins that possess the potential to serve as therapeutic targets may result in the development of new therapeutic strategies. Finally, these strategies may result in the disruption of the machinery of stemness acquisition, which may prevent tumor growth, progression, and overcome the resistance to anticancer therapies.

Transcription factors Brn-3α and TRIM16 in cancers, association with hormone reception

Sex hormones, regulating normal physiological processes of most tissues and organs, are considered to be one of the key factors in the development of hormone-dependent cancer and formation of the hormone-resistant tumor phenotype. Recently, the importance of the system for control of hormone receptors expression mediated by nuclear peptides became evident. This system is involved in the regulation of normal physiological processes, in the pathogenesis of many diseases as well as oncogenesis. In the review, we discuss the relationships of the two regulatory peptides – Brn-3α, TRIM16 with hormone receptors. The transcription factor Brn-3α is able to affect the transcription activity of androgen and estrogen receptors. It is observed the participation of TRIM16 protein in the pathogenesis of hormone-dependent tumors due to its "anti-estrogenic effect". Additionally, they are involved in the key intracellular processes, such as proliferation, cell differentiation, and programmed death - apoptosis. Thus, Brn-3α and TRIM16 are associated with cancer development and progression. By understanding these alterations, we can identify potential markers and novel biochemical therapeutic targets. It makes clear the association between classical hormone-dependent tumors and less sensitive ones with the modification in the level of hormone receptors.

Ubiquitin-protein ligase E3C maintains non-small-cell lung cancer stemness by targeting AHNAK-p53 complex

Cancer stem-like cells (CSCs) are regarded as sources of tumorigenesis, metastasis, and drug resistance, which limits current cancer therapies. Elucidating the molecular modes governing CSC properties is necessary to optimize therapeutic approaches. In this study, we discovered that ubiquitin-protein ligase E3C (UBE3C)-mediated ubiquitination is a key posttranslational mechanism involved in maintaining CSC properties of non-small-cell lung cancer (NSCLC). UBE3C was overexpressed in stem-like NSCLC cells and acted as a stemness enhancer. Knockdown of UBE3C reduced NSCLC stemness and tumorigenesis both in vivo and in vitro. We further identified AHNAK as a novel UBE3C substrate, finding that UBE3C maintained stemness by ubiquitinating and promoting AHNAK degradation. AHNAK functioned as a cofactor assisting p53 binding to stemness-related gene promoters to inhibit transcription. Subsequent downregulation of AHNAK by UBE3C overexpression removed p53-mediated inhibition of gene expression, resulting in enhanced stemness. Clinical significance was investigated in 208 NSCLC patients and confirmed that attenuated UBE3C activity and elevated AHNAK protein levels correlated with extended survival time. Collectively, findings reveal the first global characterization of UBE3C-mediated ubiquitination as a key regulator of CSCs, with results suggesting involvement of the AHNAK-p53 complex.

Genipin suppresses colorectal cancer cells by inhibiting the Sonic Hedgehog pathway

Genipin, a major component of Gardenia jasminoides Ellis fruit, has been shown to inhibit the growth of gastric, prostate, and breast cancers. However, the anti-proliferative activity of genipin in colorectal cancer (CRC) has not been characterized. Herein, we demonstrated that genipin inhibits the proliferation of CRC cells and that genipin suppressed the Hedgehog pathway. Further investigation showed that p53 and NOXA protein levels were increased during inhibition of Hedgehog pathway-mediated apoptosis in CRC cells. We also showed that p53 modulated the expression of NOXA during genipin-induced apoptosis, and suppression via SMO also played a role in this process. Subsequently, GLI1 was ubiquitinated by the E3 ligase PCAF. In a xenograft tumor model, genipin suppressed tumor growth, which was also associated with Hedgehog inactivation. Taken together, these results suggest that genipin induces apoptosis through the Hedgehog signaling pathway by suppressing p53. These findings reveal a novel regulatory mechanism involving Hedgehog/p53/NOXA signaling in the modulation of CRC cell apoptosis and tumor-forming defects.

Fish TRIM16L exerts negative regulation on antiviral immune response against grouper iridoviruses

Tripartite motif 16 (TRIM16), has been demonstrated to act as a tumor suppressor through affecting cell proliferation and migration or tumorigenicity in carcigenesis. However, the roles of TRIM16 in immune response were unknown up to now. Here, we cloned a TRIM16-like gene (TRIM16L) from orange spotted grouper (EcTRIM16L) and investigated its roles in response to virus infection. EcTRIM16L encoded a 478 amino acid peptide which showed 72% and 29% identity to large yellow croaker (Larimichthys crocea) and human (Homo sapiens), respectively. Sequence alignments indicated that EcTRIM16L shared the different gene structures with human TRIM16, evidenced by the presence of RING domain, but absence of the B-box domain. In transfected grouper cells, the green fluorescence mainly distributed in cytoplasm, and the deletion of SPRY domain affected the accurate localization of EcTRIM16L. In response to different stimuli, including infection with Singapore grouper iridovirus (SGIV) or red-spotted grouper nervous necrosis (RGNNV), and transfection with b-DNA or poly I:C, the transcript of EcTRIM16L were differently regulated in grouper spleen cells. After incubation with SGIV, the ectopic expression of EcTRIM16L significantly enhanced the viral replication, demonstrated by the increase of cytopathic effect (CPE) severity and viral gene transcriptions. Simultaneously, we also found that overexpression of EcTIRM16L in vitro significantly weakened the expression of interferon related molecules, including interferon regulatory factor 3 (IRF3), IRF7, and melanoma differentiation-associated protein 5 (MDA5). Moreover, the ectopic expression of EcTRIM16L significantly decreased both MDA5-and mediator of IRF3 activation (MITA)-induced interferon immune responses. Further studies showed that the RING domain played more important roles in the molecular action of EcTIRM16L during grouper virus infection. Our data, for the first time, demonstrated that fish TRIM16L exerted negative regulation on the interferon immune response against DNA virus infection.

Tripartite Motif 16 Inhibits the Migration and Invasion in Ovarian Cancer Cells

Tripartite motif 16 (TRIM16), a member of the RING B-box coiled-coil (RBCC)/tripartite motif (TRIM) protein family, has been shown to play a role in tumor development and progression. However, the role of TRIM16 in ovarian cancer has never been revealed. Thus, in this study, we investigated the roles and mechanisms of TRIM16 in ovarian cancer. Our results demonstrated that TRIM16 expression was low in ovarian cancer cell lines. In addition, overexpression of TRIM16 significantly inhibited the migration and invasion in vitro, as well as suppressed the epithelial-mesenchymal transition (EMT) phenotype in ovarian cancer cells. Furthermore, overexpression of TRIM16 greatly inhibited the protein expression levels of Shh, Smo, Ptc, Gli-1, MMP2, and MMP9 in ovarian cancer cells. Taken together, these results strongly suggest that TRIM16 inhibits the migration and invasion via suppressing the Sonic hedgehog signaling pathway in ovarian cancer cells. Thus, TRIM16 may be a novel potential therapeutic target for ovarian cancer.