E2F1 modulates RCCD1 expression to participate in the initiation and progression of EMT in colorectal cancer.

OBJECTIVE: Metastases in the advanced stages of colorectal cancer (CRC) present a major challenge to its treatment. Epithelial-Mesenchymal Transition (EMT) plays a crucial role in enhancing the metastasis and invasion ability of cancer cells. However, the progress of E2F transcription factor 1 (E2F1) and Regulator of chromatin condensation 1 (RCCD1) in CRC on EMT has not been studied. METHODS: The CRC differential expression data from The Cancer Genome Atlas database were analyzed by Gene Set Enrichment Analysis to verify the difference in expression of E2F1 and RCCD1 in cancerous and para-cancerous tissues.DNA-pull down and dual luciferase experiments confirmed that E2F1 regulates RCCD1. Western-blot and q-PCR experiments confirmed that E2F1 regulates RCCD1 and participates in the EMT-related progress of CRC.EDU, Wound healing and Transwell experiments verified the effects of regulation of E2F1 and RCCD1 on the proliferation, migration and invasion of CRC cells. RESULTS: E2F1 and RCCD1 are highly expressed in cancer tissues and cancer cells. E2F1 binds to the upstream promoter of RCCD1 to regulate RCCD1 and affect the expression of EMT-related targets in CRC cells. It also affects the proliferation, migration and invasion of CRC cells. CONCLUSIONS: E2F1 regulates the involvement of RCCD1 in CRC EMT and affects the proliferation, migration and invasion ability of CRC cells.

TRIM55 inhibits colorectal cancer development via enhancing protein degradation of c-Myc.

BACKGROUND: Colorectal cancer (CRC) is one of the most common and lethal malignancies which including colon and rectum cancer. Tripartite motif containing 55 (TRIM55) is an E3 ubiquitin ligase belonging to the TRIM family. Although the aberrant TRIM55 expression has been implicated in several tumors, its functional role, and molecular mechanisms in CRC remain unknown. METHODS: Immunohistochemical studies, qRT-PCR, and Western blot were performed to analyze the expression of TRIM55 in CRC patients and cell lines. TRIM55 expression and its relevance to clinical traits and prognosis were further explored in the TCGA database, and in our 87 clinical samples. Subsequently, we performed a series of functional assays to explore the effect of TRIM55 on CRC progression. Finally, the molecular mechanism of TRIM55 was investigated by immunoprecipitation and ubiquitination analyses. RESULTS: Here, we demonstrated that TRIM55 was markedly downregulated in CRC cell lines and tumors from CRC patients. Moreover, overexpression of TRIM55 could suppress CRC cell growth in vitro and inhibit CRC xenograft tumor development in vivo. Additionally, TRIM55 overexpression dampened CRC cell migration and invasion. Further bioinformatics analysis indicated that TRIM55 suppressed cyclin D1 and c-Myc expression. Mechanistically, co-immunoprecipitation assay revealed that TRIM55 directly interacted with c-Myc and down-regulated its protein expression level via protein ubiquitination. Intriguingly, c-Myc overexpression partially antagonized the function of TRIM55 overexpression. CONCLUSIONS: Taken together, our findings suggest that TRIM55 inhibits CRC tumor development via, at least in part, enhancing protein degradation of c-Myc. Targeting TRIM55 could provide a new therapeutic approach for CRC patients.

Rapid and Quantitative Analysis of Exosomes by a Chemiluminescence Immunoassay Using Superparamagnetic Iron Oxide Particles.

Since the discovery of exosomes, their potential diagnostic value has been the focus of considerable research. However, the lack of a rapid and simple technique for the quantitative analysis of exosomes greatly limits the application of exosomes in clinical research. In this study, we describe a newly developed one-step chemiluminescence immunoassay for the rapid quantitative analysis of exosomes from biofluids. Our new technique, named ExoNANO, adopts a double-antibody sandwich strategy using anti-CD63 antibody-conjugated superparamagnetic iron oxide particles (SIOPs) and acridinium ester (ACE)-labeled anti-CD9 antibodies. SIOPs have narrow size distribution and high magnetic susceptibility, and ACE has excellent chemiluminescent properties such as low background signal and no need for a catalyst. We demonstrated that ExoNANO allows the quantitative analysis of exosomes in the range of 2.92 ×105 to 2.80×108 particles/µL, with a limit of detection of 2.63×105 particles/µL. Using ExoNANO, we quantified exosomes in cell culture medium and clinical biofluids such as serum, saliva, ascitic fluid, and cerebrospinal fluid. We believe that ExoNANO might pave the way for the rapid isolation and quantitative analysis of exosomes for routine clinical applications.