KAP-1 is overexpressed and correlates with increased metastatic ability and tumorigenicity in pancreatic cancer

TRIM28 in cancer and cancer therapy

TRIM28 (tripartite motif protein 28) was initially believed to be a transcription inhibitor that plays an important role in DNA damage repair (DDR) and in maintaining cancer cellular stemness. As research has continued to deepen, several studies have found that TRIM28 not only has ubiquitin E3 ligase activity to promote degradation of substrates, but also can promote SUMOylation of substrates. Although TRIM28 is highly expressed in various cancer tissues and has oncogenic effects, there are still a few studies indicating that TRIM28 has certain anticancer effects. Additionally, TRIM28 is subject to complex upstream regulation. In this review, we have elaborated on the structure and regulation of TRIM28. At the same time, highlighting the functional role of TRIM28 in tumor development and emphasizing its impact on cancer treatment provides a new direction for future clinical antitumor treatment.

The TRIM28/miR133a/CD47 axis acts as a potential therapeutic target in pancreatic necrosis by impairing efferocytosis

Efferocytosis, the clearance of apoptotic cells by macrophages, plays a crucial role in inflammatory responses and effectively prevents secondary necrosis. However, the mechanisms underlying efferocytosis in acute pancreatitis (AP) remain unclear. In this study, we demonstrated the presence of efferocytosis in injured human and mouse pancreatic tissues. We also observed significant upregulation of CD47, an efferocytosis-related the "do not eat me" molecule in injured acinar cells. Subsequently, we used CRISPR-Cas9 gene editing, anti-adeno-associated virus (AAV) gene modification, and anti-CD47 antibody to investigate the potential therapeutic role of AP. CD47 expression was negatively regulated by upstream miR133a, which is controlled by the transcription factor TRIM28. To further investigate the regulation of efferocytosis and reduction of pancreatic necrosis in AP, we used miR-133a-agomir and pancreas-specific AAV-shTRIM28 to modulate CD47 expression. Our findings confirmed that CD47-mediated efferocytosis is critical for preventing pancreatic necrosis and suggest that targeting the TRIM28-miR133a-CD47 axis is clinically relevant for the treatment of AP.

KAP1 stabilizes MYCN mRNA and promotes neuroblastoma tumorigenicity by protecting the RNA m6A reader YTHDC1 protein degradation

BACKGROUND

Neuroblastoma (NB) patients with amplified MYCN often face a grim prognosis and are resistant to existing therapies, yet MYCN protein is considered undruggable. KAP1 (also named TRIM28) plays a crucial role in multiple biological activities. This study aimed to investigate the relationship between KAP1 and MYCN in NB.

METHODS

Transcriptome analyses and luciferase reporter assay identified that KAP1 was a downstream target of MYCN. The effects of KAP1 on cancer cell proliferation and colony formation were explored using the loss-of-function assays in vitro and in vivo. RNA stability detection was used to examine the influence of KAP1 on MYCN expression. The mechanisms of KAP1 to maintain MYCN mRNA stabilization were mainly investigated by mass spectrum, immunoprecipitation, RIP-qPCR, and western blotting. In addition, a xenograft mouse model was used to reveal the antitumor effect of STM2457 on NB.

RESULTS

Here we identified KAP1 as a critical regulator of MYCN mRNA stability by protecting the RNA N6-methyladenosine (m6A) reader YTHDC1 protein degradation. KAP1 was highly expressed in clinical MYCN-amplified NB and was upregulated by MYCN. Reciprocally, KAP1 knockdown reduced MYCN mRNA stability and inhibited MYCN-amplified NB progression. Mechanistically, KAP1 regulated the stability of MYCN mRNA in an m6A-dependent manner. KAP1 formed a complex with YTHDC1 and RNA m6A writer METTL3 to regulate m6A-modified MYCN mRNA stability. KAP1 depletion decreased YTHDC1 protein stability and promoted MYCN mRNA degradation. Inhibiting MYCN mRNA m6A modification synergized with chemotherapy to restrain tumor progression in MYCN-amplified NB.

CONCLUSIONS

Our research demonstrates that KAP1, transcriptionally activated by MYCN, forms a complex with YTHDC1 and METTL3, which in turn maintain the stabilization of MYCN mRNA in an m6A-dependent manner. Targeting m6A modification by STM2457, a small-molecule inhibitor of METTL3, could downregulate MYCN expression and attenuate tumor proliferation. This finding provides a new alternative putative therapeutic strategy for MYCN-amplified NB.

Clinical features of dermatomyositis patients with anti-TIF1 antibodies: A case based comprehensive review

BACKGROUND AND OBJECTIVES

Dermatomyositis is chronic autoimmune disease primarily affecting skin and muscles. Antibodies are key players of pathogenesis and are in strong correlation with distinct clinical phenotypes. We present a case and a comprehensive review of the literature on dermatomyositis patients with Anti TIF1 antibodies.

METHODS

PubMed and Web of Science databases were reviewed. 166 articles were identified; 95 of them were evaluated; 79 of them included to the study. 45 of the included articles were case reports 9 were case series and 25 were research articles. In total 1065 patients were identified but number of patients with available information for different clinical features varied.

RESULTS

69.6% of the patients with Anti TIF1-γ were female. Prevalence of malignancy was 42.6% among patients with Anti TIF1-γ. Muscle weakness (83%), Gottron sign (82.2%), heliotrope rash (73.7%), nailfold capillary changes (67.7%), dysphagia (38.4%), and joint involvement (31.1%) were the most common clinical features seen in patients with Anti TIF1-γ. Interstitial lung disease (ILD) was reported among 8.7% of patients with Anti TIF1-γ. Advanced age, male gender, dysphagia, and V-neck rash were significant risk factors for malignancy, whereas juvenile age, ILD, TIF1-β antibodies and joint involvement were associated with a decreased risk for malignancy. Advanced age, malignancy, dysphagia, and muscle involvement were associated with an increased risk for mortality.

CONCLUSIONS

Patients with advanced age, male gender, dysphagia, and V-neck rash require strict cancer screening. Patients with advanced age, malignancy, dysphagia, and muscle involvement have poor prognosis and should receive aggressive treatment.

ZNF133 is a potent suppressor in breast carcinogenesis through dampening L1CAM, a driver for tumor progression

Due to the complexity and heterogeneity of breast cancer, the therapeutic effects of breast cancer treatment vary between subtypes. Breast cancer subtypes are classified based on the presence of molecular markers for estrogen or progesterone receptors and human epidermal growth factor 2. Thus, novel, comprehensive, and precise molecular indicators in breast carcinogenesis are urgently needed. Here, we report that ZNF133, a zinc-finger protein, is negatively associated with poor survival and advanced pathological staging of breast carcinomas. Moreover, ZNF133 is a transcription repressor physically associated with the KAP1 complex. It transcriptionally represses a cohort of genes, including L1CAM, that are critically involved in cell proliferation and motility. We also demonstrate that the ZNF133/KAP1 complex inhibits the proliferation and invasion of breast cancer cells in vitro and suppresses breast cancer growth and metastasis in vivo by dampening the transcription of L1CAM. Taken together, the findings of our study confirm the value of ZNF133 and L1CAM levels in the diagnosis and prognosis of breast cancer, contribute to a deeper understanding of the regulation mechanism of ZNF133 for the first time, and provide a new therapeutic strategy and precise intervention target for breast cancer.

The role of tripartite motif-containing 28 in cancer progression and its therapeutic potentials

Tripartite motif-containing 28 (TRIM28) belongs to tripartite motif (TRIM) family. TRIM28 not only binds and degrades its downstream target, but also acts as a transcription co-factor to inhibit gene expression. More and more studies have shown that TRIM28 plays a vital role in tumor genesis and progression. Here, we reviewed the role of TRIM28 in tumor proliferation, migration, invasion and cell death. Moreover, we also summarized the important role of TRIM28 in tumor stemness sustainability and immune regulation. Because of the importance of TRIM28 in tumors, TIRM28 may be a candidate target for anti-tumor therapy and play an important role in tumor diagnosis and treatment in the future.

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.

Knockdown of KRAB domain-associated protein 1 suppresses the proliferation, migration and invasion of thyroid cancer cells by regulating P68/DEAD box protein 5

KRAB domain-associated protein 1 (KAP-1) has been reported to be an oncogene in diverse tumors. KAP-1 was found to have abundant existence in malignant thyroid tissues, but its role in thyroid cancer hasn’t been elucidated clearly. This study was carried out to explore the role of KAP-1 in thyroid cancer, and to clarify its molecular mechanism. The expressions of KAP-1 and P68/DEAD box protein 5 (DDX5) were assessed under the help of qRT-PCR and western blot. Then, we downregulated KAP-1 or upregulated DDX5 by cell transfection in TPC-1 cells. A series of cellular experiments on proliferation, apoptosis, migration and invasion were conducted with CCK-8, EdU, TUNEL, wound-healing and Transwell assays. Besides, the relationship between KAP-1 and DDX5 was verified by co-immunoprecipitation (Co-IP). The results showed that both of KAP-1 and DDX5 were upregulated in thyroid cancer cells. Loss-of-function experiments revealed that KAP-1 knockdown imparted suppressive effects on cell proliferation, migration and invasion, but promoted cell apoptosis. Additionally, KAP-1 was demonstrated to interact with DDX5 and positively regulate DDX5 expression. The following rescued experiments exhibited that the inhibitory effects of KAP-1 knockdown on cellular activities of thyroid cancer and Wnt/β-catenin signaling were also partly reversed by DDX5 overexpression. Moreover, activation of Wnt/β-catenin signaling retarded the anti-tumor activity of KAP-1 knockdown. In conclusion, the data in this study disclosed that KAP-1 silence helped to repress the cell proliferation, migration and invasion by degrading DDK5, so as to hinder the development of thyroid cancer.

TRIM50 Suppresses Pancreatic Cancer Progression and Reverses the Epithelial-Mesenchymal Transition via Facilitating the Ubiquitous Degradation of Snail1

Emerging evidence suggests that the tripartite motif (TRIM) family play important roles in tumor development and progression. Tripartite motif-containing 50 (TRIM50) is a member of the TRIM family, but little is known regarding its expression and potential functional roles in cancer. In this study, we first analyzed the expression pattern and clinical significance of TRIM50 in pancreatic cancer and found that TRIM50 expression is significantly reduced in pancreatic cancer tissues and its downregulation is associated with poor survival for pancreatic cancer patients. Functionally, TRIM50 overexpression in pancreatic cancer cells decreases their proliferation and motility capabilities and reverses the epithelial-mesenchymal transition (EMT) process, whereas TRIM50 depletion had the opposite effects. Mechanically, TRIM50 directly interacts with Snail1, a key regulator of EMT, and acts as an E3 ubiquitin ligase to target Snail1 for ubiquitous degradation. The function of TRIM50 in suppressing cell migration and EMT depends on TRIM50-promoted Snail1 degradation. In conclusion, our findings identify TRIM50 as a tumor suppressor that inhibits pancreatic cancer progression and reverses EMT via degrading Snail1 and provide new insights into the progression of pancreatic cancer.

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.

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.

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.

Aberrantly enhanced melanoma-associated antigen (MAGE)-A3 expression facilitates cervical cancer cell proliferation and metastasis via actuating Wnt signaling pathway

BACKGROUND

The over-expression of melanoma-associated antigen (MAGE)-A3 in cervical cancer (CC) has been observed in our previous study, suggesting that it possibly take a vital role during the development and metastasis of CC. The present study aimed to investigate the biological function of MAGE-A3 in the progression of CC and explore how it executes its roles.

METHODS

The mRNA expression of MAGE-A3 in End1/E6E7 and CC cell lines (HeLa, SiHa and C33A) was measured by real-time quantitative reverse transcription PCR (qRT-PCR). Loss- and gain-of-function methods were used to assess the effect of MAGE-A3 on the proliferative, migratory and invasive abilities of HeLa and SiHa cells. Western blot was performed to measure the expression levels of proteins related to epithelial-mesenchymal transition (EMT) and proteins in the Wnt signaling pathway. In vivo tumorigenesis assay was conducted to evaluate the effect of MAGE-A3 on tumor growth.

RESULTS

MAGE-A3 expression was significantly up-regulated in CC cell lines (HeLa, SiHa and C33A) compared with that in End1/E6E7 cell line. Knockdown of MAGE-A3 could significantly suppress migration, invasion and proliferation in HeLa cells; whereas, overexpression of MAGE-A3 in SiHa cells presented the opposite results. Moreover, knockdown of MAGE-A3 presented a suppressive effect on the activation of EMT and Wnt signaling pathway in HeLa cells, whilst up-regulation of MAGE-A3 exhibited the opponent outcomes in SiHa cells. Through in vivo tumorigenesis assay, we further verified that MAGE-A3 acted as a facilitator in tumor growth.

CONCLUSIONS

MAGE-A3 is overexpressed in CC cells and possibly facilitates the viability and motility of CC cells via modulating EMT and Wnt signaling. This study implied that MAGE-A3 might be a potential therapeutic target as well as a prognosis predictor for patients with CC.

Targeting Epithelial Mesenchymal Plasticity in Pancreatic Cancer: A Compendium of Preclinical Discovery in a Heterogeneous Disease

Pancreatic Ductal Adenocarcinoma (PDAC) is a particularly insidious and aggressive disease that causes significant mortality worldwide. The direct correlation between PDAC incidence, disease progression, and mortality highlights the critical need to understand the mechanisms by which PDAC cells rapidly progress to drive metastatic disease in order to identify actionable vulnerabilities. One such proposed vulnerability is epithelial mesenchymal plasticity (EMP), a process whereby neoplastic epithelial cells delaminate from their neighbours, either collectively or individually, allowing for their subsequent invasion into host tissue. This disruption of tissue homeostasis, particularly in PDAC, further promotes cellular transformation by inducing inflammatory interactions with the stromal compartment, which in turn contributes to intratumoural heterogeneity. This review describes the role of EMP in PDAC, and the preclinical target discovery that has been conducted to identify the molecular regulators and effectors of this EMP program. While inhibition of individual targets may provide therapeutic insights, a single 'master-key' remains elusive, making their collective interactions of greater importance in controlling the behaviours' of heterogeneous tumour cell populations. Much work has been undertaken to understand key transcriptional programs that drive EMP in certain contexts, however, a collaborative appreciation for the subtle, context-dependent programs governing EMP regulation is needed in order to design therapeutic strategies to curb PDAC mortality.

TRIM59 predicts poor prognosis and promotes pancreatic cancer progression via the PI3K/AKT/mTOR-glycolysis signaling axis

Aberrant expression of the tripartite motif containing 59 (TRIM59) has been reported to participate in the development and progression of various human cancers. However, its expression pattern and cellular roles in pancreatic cancer (PC) remains unclear. In our study, we found that TRIM59 expression was significantly increased in PC tissues and was positively correlated with several malignant behaviors and poor overall survival of PC patients based on bioinformatics analysis and immunohistochemistry staining. Functionally, small interfering RNA-mediated TRIM59 depletion inhibited cell proliferation and migration in vitro, while TRIM59 overexpression promoted cell proliferation and migration in vitro and drove tumor growth and liver metastasis in vivo. Mechanically, TRIM59 was found to enhance glycolysis through activating the PI3K/AKT/mTOR pathway, ultimately contributing to PC progression. Taken together, our results demonstrate that TRIM59 may be a potential predictor for PC and promotes PC progression via the PI3K/AKT/mTOR-glycolysis signaling pathway, which establishes the rationale for targeting the TRIM59-related pathways to treat PC.

A unique subset of low-risk Wilms tumors is characterized by loss of function of TRIM28 (KAP1), a gene critical in early renal development: A Children's Oncology Group study

This study explores the genomic alterations that contribute to the formation of a unique subset of low-risk, epithelial differentiated, favorable histology Wilms tumors (WT), tumors that have been characterized by their expression of post-induction renal developmental genes (Subset 1 WT). We demonstrate copy neutral loss of heterozygosity involving 19q13.32-q13.43, unaccompanied by evidence for imprinting by DNA methylation. We further identified loss-of-function somatic mutations in TRIM28 (also known as KAP1), located at 19q13, in 8/9 Subset 1 tumors analyzed. An additional germline TRIM28 mutation was identified in one patient. Retrospective evaluation of previously analyzed WT outside of Subset 1 identified an additional tumor with anaplasia and both TRIM28 and TP53 mutations. A major function of TRIM28 is the repression of endogenous retroviruses early in development. We depleted TRIM28 in HEK293 cells, which resulted in increased expression of endogenous retroviruses, a finding also demonstrated in TRIM28-mutant WT. TRIM28 has been shown by others to be active during early renal development, and to interact with WTX, another gene recurrently mutated in WT. Our findings suggest that inactivation of TRIM28 early in renal development contributes to the formation of this unique subset of FHWTs, although the precise manner in which TRIM28 impacts both normal renal development and oncogenesis remains elusive.

TRIM28 is overexpressed in glioma and associated with tumor progression

Background

Tripartite motif containing 28 (TRIM28) is a transcriptional co-factor targeting many genes with pleiotropic biological activities, but the study on the role of TRIM28 in glioma is rare.

Methods

To explore the function of TRIM28 in glioma, we first detected the expression levels of TRIM28 in glioma tissues and analyzed the correlations of TRIM28 expression with clinicopathological variables of patients in 85 cases of glioma. Meanwhile, we used shRNA to knockdown TRIM28 in glioma cell lines to detect the biological functions of TRIM28 in cell and animal experiments.

Results

We found that TRIM28 was expressed at significantly higher level in glioma tissues than in non-tumor brain, and TRIM28 expression correlated significantly with tumor malignancy. Furthermore, TRIM28 higher expression was also correlated with poor survival of glioma patients (P<0.01). Functionally, knockdown of TRIM28 could significantly inhibit cell proliferation and migration in glioma cells. Additionally, we found that TRIM28 could inhibit the expression of E-cadherin significantly by reducing its mRNA stability at the post-transcriptional level.

Conclusion

Our results suggest that TRIM28 overexpression is correlated with glioma malignant progression and patients' poor survival, so targeting TRIM28 could be an efficacious strategy in glioma.

KAP1 inhibits the Raf-MEK-ERK pathway to promote tumorigenesis in A549 lung cancer cells

Aberrant activation of the Raf-MEK-ERK pathway has frequently been associated with various cancers, especially lung cancer. However, the key regulators of this pathway are largely unknown. Using functional proteomics screening, we found that KAP1 interacts with c-Raf. Knocking out KAP1 decreased c-Raf phosphorylation at serine 259 and increased its phosphorylation at serine 338, which activated MEK and ERK. We detected higher KAP1 expression in lung cancer tissues than in normal peri-tumoral tissues. KAP1 knockdown arrested A549 lung cancer cells in the G0/G1 phase of the cell cycle and attenuated cell growth, metastasis, the epithelial-mesenchymal transition, angiogenesis, stemness, and colony formation. Furthermore, knocking out KAP1 remarkably increased the susceptibility of A549 cells to the anti-cancer drug 5-Fluorouracil, which correlated with increasing ERK phosphorylation. In vivo xenograft experiments suggested that KAP1 deficiency significantly decreases the tumorigenicity of A549 cells. Taken together, our findings indicate that KAP1 acts as a key module in the c-Raf-interactome complex and regulates lung cancer development through the Raf-MEK-ERK pathway. Therefore, KAP1 may represent a potential diagnosis biomarker and new treatment target for lung cancer.

Identification of PGAM1 as a putative therapeutic target for pancreatic ductal adenocarcinoma metastasis using quantitative proteomics

Background

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive gastrointestinal cancer characterized by an extremely low survival rate because of early metastasis. Identifying satisfactory therapeutic targets associated with metastasis is crucial to improve the treatment effect of PDAC.

Materials and methods

In this research, we used stable isotope labeling by amino acids in cell culture, 1-dodecyl-3-methylimidazolium chloride-assisted sample preparation method preparing protein sample and nano-reversed-phase liquid chromatography-mass spectrometry/mass spectrometry analysis to perform the comparative proteomics of two homologous hamster pancreatic cancer cell lines that are different in metastatic ability: PC-1.0 (highly metastatic) and PC-1 (weakly metastatic). Verifications are through immunohistochemistry on clinical human PDAC pathologic tissues as well as by Western blot of human pancreatic cancer cell lines. siRNA silencing methods were used to study the effect of molecules on invasion and metastasis of pancreatic cancer cell lines.

Results

Bioinformatic analysis indicated that a total of 141 differentially expressed proteins (82 upregulated and 59 downregulated in PC-1.0 cells) were identified showing obviously differential expression (>1.5-fold change). These differentially expressed proteins were involved in a number of different biologic functions, metabolic pathways, and pathophysiologic processes. Phosphoglycerate mutase 1 (PGAM1) and HSPE1 are the top two upregulated proteins, and PDIA3 and CALR are the top two downregulated proteins in PC-1.0 cells compared to PC-1 cells. PGAM1 and HSPE1 showed higher expressions in PDAC tissue with clinical metastasis and highly metastatic pancreatic cancer cell lines PC-1.0 and Aspc-1. PDIA3 and CALR showed higher expressions in weakly metastatic pancreatic cancer cell lines PC-1 and Capan-2. The Western blot results were consistent with the MS quantification data. Silencing PGAM1 was found to decrease the migration and invasion of pancreatic cancer cell lines with statistical significance, especially in highly metastatic PC-1.0 and Aspc-1 cell lines.

Conclusion

These data indicated that PGAM1 may be a potential therapeutic target for PDAC metastasis.

TRIM28 multi-domain protein regulates cancer stem cell population in breast tumor development

The expression of Tripartite motif-containing protein 28 (TRIM28)/Krüppel-associated box (KRAB)-associated protein 1 (KAP1), is elevated in at least 14 tumor types, including solid and hematopoietic tumors. High level of TRIM28 is associated with triple-negative subtype of breast cancer (TNBC), which shows higher aggressiveness and lower survival rates. Interestingly, TRIM28 is essential for maintaining the pluripotent phenotype in embryonic stem cells. Following on that finding, we evaluated the role of TRIM28 protein in the regulation of breast cancer stem cells (CSC) populations and tumorigenesis in vitro and in vivo. Downregulation of TRIM28 expression in xenografts led to deceased expression of pluripotency and mesenchymal markers, as well as inhibition of signaling pathways involved in the complex mechanism of CSC maintenance. Moreover, TRIM28 depletion reduced the ability of cancer cells to induce tumor growth when subcutaneously injected in limiting dilutions. Our data demonstrate that the downregulation of TRIM28 gene expression reduced the ability of CSCs to self-renew that resulted in significant reduction of tumor growth. Loss of function of TRIM28 leads to dysregulation of cell cycle, cellular response to stress, cancer cell metabolism, and inhibition of oxidative phosphorylation. All these mechanisms directly regulate maintenance of CSC population. Our original results revealed the role of the TRIM28 in regulating the CSC population in breast cancer. These findings may pave the way to novel and more effective therapies targeting cancer stem cells in breast tumors.

The lncRNA BORG Drives Breast Cancer Metastasis and Disease Recurrence

Long noncoding RNAs (lncRNAs) have emerged as potent regulators of breast cancer development and progression, including the metastatic spread of disease. Through in silico and biological analyses, we identified a novel lncRNA, BMP/OP-Responsive Gene (BORG), whose expression directly correlates with aggressive breast cancer phenotypes, as well as with metastatic competence and disease recurrence in multiple clinical cohorts. Mechanistically, BORG elicits the metastatic outgrowth of latent breast cancer cells by promoting the localization and transcriptional repressive activity of TRIM28, which binds BORG and induces substantial alterations in carcinoma proliferation and survival. Moreover, inhibiting BORG expression in metastatic breast cancer cells impedes their metastatic colonization of the lungs of mice, implying that BORG acts as a novel driver of the genetic and epigenetic alterations that underlie the acquisition of metastatic and recurrent phenotypes by breast cancer cells.

The complexity of TRIM28 contribution to cancer

Since the first discovery in 1996, the engagement of TRIM28 in distinct aspects of cellular biology has been extensively studied resulting in identification of a complex nature of TRIM28 protein. In this review, we summarize core biological functions of TRIM28 that emerge from TRIM28 multi-domain structure and possessed enzymatic activities. Moreover, we will discuss whether the complexity of TRIM28 engagement in cancer biology makes TRIM28 a possible candidate for targeted anti-cancer therapy. Briefly, we will demonstrate the role of TRIM28 in regulation of target gene transcription, response to DNA damage, downregulation of p53 activity, stimulation of epithelial-to-mesenchymal transition, stemness sustainability, induction of autophagy and regulation of retrotransposition, to provide the answer whether TRIM28 functions as a stimulator or inhibitor of tumorigenesis. To date, number of studies demonstrate significant upregulation of TRIM28 expression in cancer tissues which correlates with worse overall patient survival, suggesting that TRIM28 supports cancer progression. Here, we present distinct aspects of TRIM28 involvement in regulation of cancer cell homeostasis which collectively imply pro-tumorigenic character of TRIM28. Thorough analyses are further needed to verify whether TRIM28 possess the potential to become a new anti-cancer target.

Expression of tripartite motif-containing protein 28 in primary breast carcinoma predicts metastasis and is involved in the stemness, chemoresistance, and tumor growth

The prediction of who develops metastasis has been the most difficult aspect in the management of breast cancer patients. The lymph node metastasis has been the most useful predictor of prognosis and patient management. However, a good proportion of patients with lymph node positivity remain disease free for 5 years or more, while about a third of those who were lymph node negative develop distant metastasis within the same period. This warrants a robust biomarker(s), preferably gene expression based. In order to elucidate gene-based biomarkers for prognosis of breast cancers, gene expression profiling of primary tumors and follow-up for over 5 years has been performed. The analysis revealed a network of genes centered around the tripartite motif-containing protein 28 as an important indicator of disease progression. Short hairpin RNA-mediated knockdown of tripartite motif-containing protein 28 in breast cancer cells revealed a decreased expression of epithelial-to-mesenchymal transition markers and increased expression of epithelial markers, decreased migration and invasion, and increased chemosensitivity to doxorubicin, 5-fluorouracil, and methotrexate. Furthermore, knockdown of tripartite motif-containing protein 28 resulted in the decrease of stemness as revealed by sphere formation assay as well as decreased expression of CD44 and Bmi1. Moreover, tripartite motif-containing protein 28 knockdown significantly reduced the tumor size and lung metastasis in orthotopic tumor xenograft assay in immunocompromised mice. The tumor size was further reduced when these mice were treated with doxorubicin. These data provide evidence for tripartite motif-containing protein 28 as a biomarker and a potential therapeutic target for breast cancer.

MAGE-TRIM28 complex promotes the Warburg effect and hepatocellular carcinoma progression by targeting FBP1 for degradation

Hepatocellular carcinoma (HCC) is one of the leading cause of cancer death in the world. Fructose-1,6-biphosphatase (FBP1), a rate-limiting enzyme in gluconeogenesis, has been identified recently as a tumor suppressor in HCC and other cancer types. In this study, we demonstrated that the tripartite motif-containing protein 28 (TRIM28) binds directly to and promotes FBP1 for ubiquitination and degradation. MAGE-A3 and MAGE-C2, which are known to be overexpressed in HCC, can enhance TRIM28-dependent degradation of FBP1 by forming ubiquitin ligase complexes with TRIM28. We further showed that expression of TRIM28 increased glucose consumption and lactate production by promoting FBP1 degradation in HCC cells and that FBP1 is a key mediator of TRIM28-induced HCC growth in culture and in mice. Moreover, we demonstrated that FBP1 and TRIM28 protein levels inversely correlated in HCC patient specimens. Finally, we showed that the proteasome inhibitor bortezomib mitigated the Warburg effect by inhibiting FBP1 degradation in HCC. Collectively, our findings not only identify oncogenic MAGE-TRIM28 complex-mediated proteasome degradation of FBP1 as a key mechanism underlying downregulation of FBP1 proteins in HCC, but also reveal that MAGE-TRIM28-regulated reprogramming of cancer cell metabolism and HCC tumorigenesis is mediated, at least in part, through FBP1 degradation.

Tripartite motif containing 28 (TRIM28) promotes breast cancer metastasis by stabilizing TWIST1 protein

TRIM28 regulates its target genes at both transcriptional and posttranscriptional levels. Here we report that a TRIM28-TWIST1-EMT axis exists in breast cancer cells and TRIM28 promotes breast cancer metastasis by stabilizing TWIST1 and subsequently enhancing EMT. We find that TRIM28 is highly expressed in both cancer cell lines and advanced breast cancer tissues, and the levels of TRIM28 and TWIST1 are positively correlated with the aggressiveness of breast carcinomas. Overexpression and depletion of TRIM28 up- and down-regulates the protein, but not the mRNA levels of TWIST1, respectively, suggesting that TRIM28 upregulates TWIST1 post-transcriptionally. Overexpression of TRIM28 in breast cancer cell line promotes cell migration and invasion. Knockdown of TRIM28 reduces the protein level of TWIST1 with concurrent upregulation of E-cadherin and downregulation of N-cadherin and consequently inhibits cell migration and invasion. Furthermore, Immunoprecipitation and GST pull-down assays demonstrated that TRIM28 interacts with TWIST1 directly and this interaction is presumed to protect TWIST1 from degradation. Our study revealed a novel mechanism in breast cancer cells that TRIM28 enhances metastasis by stabilizing TWIST1, suggesting that targeting TRIM28 could be an efficacious strategy in breast cancer treatment.

High ROR2 expression in tumor cells and stroma is correlated with poor prognosis in pancreatic ductal adenocarcinoma

RTK-like orphan receptor 2 (ROR2) is overexpressed in several cancers and has tumorigenic activity. However, the expression of ROR2 and its functional and prognostic significance have yet to be evaluated in pancreatic ductal adenocarcinoma (PDAC). Quantitative real-time polymerase chain reaction was used to characterize the expression of ROR2 mRNA in PDAC, corresponding peritumoral tissues, and PDAC cell lines. Immunohistochemical analysis with tissue microarrays was used to evaluate ROR2 expression in PDAC and to investigate the relationship of this expression to clinicopathological factors and prognosis. The expression of ROR2 mRNA and protein was significantly higher in PDAC than in normal pancreatic tissues. High cytoplasmic ROR2 expression in cancer cells was significantly associated with a primary tumor, distant metastasis, and TNM stage, and high stromal ROR2 expression was significantly associated with regional lymph node metastasis and TNM stage. The Kaplan–Meier method and Cox regression analyses showed that high ROR2 expression in tumor cytoplasm or stromal cells was significantly associated with malignant attributes and reduced survival in PDAC. We present strong evidence that ROR2 could be used as an indicator of poor prognosis and could represent a novel therapeutic target for PDAC.

The indolent nature of pulmonary metastases from ductal adenocarcinoma of the pancreas

BACKGROUND AND OBJECTIVES

The natural history of pulmonary metastases from pancreatic ductal adenocarcinoma (PDAC) is not well studied. Limited evidence suggests patients with isolated pulmonary metastases from PDAC follow a more benign clinical course than those with other sites of metastases.

METHODS

We performed a retrospective review of all patients with pulmonary metastases from PDAC from 2000 to 2010 and analyzed survival utilizing the Kaplan-Meier method based upon location of first metastasis (lung first, intra-abdominal first, or synchronous intra-abdominal and lung metastases).

RESULTS

Median survival among subjects with lung as the only site of metastases was significantly longer than those with other metastatic patterns. In subjects that had undergone resection of their PDAC, survival in those with lung as a first site of recurrence remained significantly longer than those with abdominal first or synchronous intra-abdominal and lung recurrence. Among resected patients that developed lung only recurrence, survival was significantly prolonged (67.5 months) in those who underwent surgical resection/stereotactic radiosurgery compared to chemotherapy (33.8 months) or observation (29.9 months) for treatment of lung recurrence.

CONCLUSION

Patients with isolated pulmonary recurrence from PDAC may realize a survival benefit from surgical intervention or stereotactic radiosurgery compared to chemotherapy or observation for treatment of lung recurrence.