TRIM59 facilitates the proliferation of colorectal cancer and promotes metastasis via the PI3K/AKT pathway

High PLK4 expression promotes tumor progression and induces epithelial‑mesenchymal transition by regulating the Wnt/β‑catenin signaling pathway in colorectal cancer

Polo-like kinase 4 (PLK4) has been identified as an oncogene, which is overexpressed in various types of human cancer; however, its role in colorectal cancer (CRC) development remains unknown. The present study demonstrated that PLK4 protein expression was upregulated in CRC tissues compared with in normal tissues through western blotting. In addition, immunohistochemical analysis of 39 CRC specimens further demonstrated that PLK4 protein expression was upregulated in 64.1% (25/39) of samples. Increased PLK4 expression was closely associated with enhanced tumor size (P=0.031), lymph node metastasis (P=0.016) and TNM stage (P=0.001). Subsequently, cell viability, wound scratch, migration and invasion assays were conducted in vitro, and nude mice CRC xenograft models were generated. The results demonstrated that knockdown of PLK4 in CRC cells resulted in significant decreases in cell viability and proliferation, and decreased the protein expression levels of N-cadherin and snail, which are biomarkers of epithelial-mesenchymal transition. Furthermore, PLK4 knockdown inactivated the Wnt/β-catenin pathway in CRC cells in vitro and in vivo, and suppressed the growth of xenograft tumors in nude mice. In conclusion, these results suggested that PLK4 may promote the carcinogenesis and metastasis of CRC, thus indicating that PLK4 may be considered a molecular target for CRC treatment.

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.

E2F transcription factor 8 promotes cell proliferation via CCND1/p21 in esophageal squamous cell carcinoma

Purpose

E2F transcription factor 8 (E2F8) is a novel member of the E2F family, but its function in esophageal squamous cell carcinoma (ESCC) remains unclear. This study aimed to research the function of E2F8 in ESCC.

Materials and methods

We used quantitative real-time PCR and Western blot analyses to detect the expression pattern of E2F8 in ESCC. The effects of E2F8 on proliferation were investigated by Cell Counting Kit-8, 5-ethynyl-2′-deoxyuridine, and colony formation assays. We also confirmed the function of E2F8 in vivo.

Results

E2F8 expression was upregulated in ESCC, and promoted cell proliferation and influenced the expression of CCND1/p21. Downregulation of E2F8 expression inhibited cell proliferation in vivo.

Conclusion

E2F8 was identified as a new potential oncogene in ESCC.

TRIM59 overexpression correlates with poor prognosis and contributes to breast cancer progression through AKT signaling pathway

TRIM59 has been recently implicated in the carcinogenesis of several cancers such as lung cancer, gastric cancer, and bladder cancer. However, its expression pattern and clinical significance has not been investigated in human breast cancer. In the present study, we examined TRIM59 protein expression in 95 cases of breast cancer tissues using immunohistochemistry. We found that TRIM59 was upregulated in 42 out of 95 cases and correlated with TNM stage (P = 0.0056), lymph node metastasis (P = 0.0088) and poor prognosis (P = 0.0092). Importantly, TRIM59 level was higher in triple-negative breast cancer (TNBC) (P = 0.0157). Expression of TRIM59 protein was also upregulated in breast cancer cell lines compared to normal MCF-10A cell line. TRIM59 plasmid and shRNA transfection was performed in MCF-7 and SK-BR-3 cells respectively. TRIM59 overexpression promoted cell proliferation, invasion, migration, cell cycle transition, and paclitaxel resistance, whereas TRIM59 depletion showed the opposite results. Further analysis showed that TRIM59 overexpression upregulated expression of cyclinA, cyclinE, Bcl-xl, Bcl-2, p-AKT, and downregulated expression of p21, p27, p53. AKT inhibitor treatment abolished the effect of TRIM59 on Bcl-2 expression. TRIM59 overexpression also upregulated the level of p53 ubiquitination. In conclusion, TRIM59 overexpression correlates with poor prognosis and promotes malignant behavior through regulation of AKT pathway in human breast cancer.

TRIM59 regulates autophagy through modulating both the transcription and the ubiquitination of BECN1

Macroautophagy/autophagy is a multistep cellular process that sequesters cytoplasmic components for lysosomal degradation. BECN1/Beclin1 is a central protein that assembles cofactors for the formation of a BECN1-PIK3C3-PIK3R4 complex to trigger the autophagy protein cascade. Discovering the regulators of BECN1 is important for understanding the mechanism of autophagy induction. Here, we demonstrate that TRIM59, a tripartite motif protein, plays an important role in autophagy regulation in non-small cell lung cancer (NSCLC). On the one hand, TRIM59 regulates the transcription of BECN1 through negatively modulating the NFKB pathway. On the other hand, TRIM59 regulates TRAF6 induced K63-linked ubiquitination of BECN1, thus affecting the formation of the BECN1-PIK3C3 complex. We further demonstrate that TRIM59 can mediate K48-linked ubiquitination of TRAF6 and promote the proteasomal degradation of TRAF6. Taken together, our findings reveal novel dual roles for TRIM59 in autophagy regulation by affecting both the transcription and the ubiquitination of BECN1.

Abbreviations: ACTB: actin beta; BECN1: beclin 1; CHX: cycloheximide; CQ: chloroquine; GFP: green fluorescent protein; HA: haemagglutinin tag; His: polyhistidine tag; LC3B: microtubule associated protein 1 light chain 3 beta; NFKB: nuclear factor kappa B; NFKBIA: NFKB inhibitor alpha; NSCLC: non-small cell lung cancer; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; RELA: RELA proto-oncogene, NF-kB subunit; SQSTM1: sequestosome 1; tGFP: Turbo green fluorescent protein; TRAF6: TNF receptor associated factor 6; TRIM59: tripartite motif containing 59; B: ubiquitin

GPR56 promotes proliferation of colorectal cancer cells and enhances metastasis via epithelial‑mesenchymal transition through PI3K/AKT signaling activation

G protein-coupled receptor 56 (GPR56), a member of the orphan GPCR family, has been reported to be an oncogene in various malignancies. However, little is known regarding the detailed molecular mechanism of GPR56 in colorectal cancer (CRC). The present study aimed to detect the expression level and biological function of GPR56 in CRC. We examined the expression of GPR56 in CRC tissues and cell lines by quantitative real time (qRT)-PCR, immunohistochemistry, and western blot analysis. The prognostic significance of GPR56 in CRC patients was evaluated by Kaplan-Meier survival analysis. The influence of GPR56 on tumor cell proliferation (via Cell Counting Kit-8, and a tumor formation assay in mice), apoptosis (flow cytometry), cell cycle distribution (flow cytometry) and migration (Transwell assay) was explored. We also investigated the underlying mechanism of GPR56 by western blot analysis. We found GPR56 expression was significantly upregulated in CRC tissues and cell lines compared to corresponding normal controls. Higher GPR56 expression in patients predicted poorer prognosis. Depletion of GPR56 markedly suppressed cell proliferation, migration, and invasion. GPR56 overexpression promoted CRC cell metastasis by expediting epithelial-mesenchymal transition by activating PI3K/AKT signaling. In conclusion, GPR56 played an important role in CRC progression and may represent a new therapeutic target to reduce CRC metastasis.

A systematic view on E3 ligase Ring TRIMmers with a focus on cardiac function and disease

Ubiquitination, a post-translational modification via ubiquitin-proteasome-system, is one of the vital cellular processes involved in intracellular signaling, cell death, transcriptional control, etc. Importantly, it prevents the aggregation of non-functional, misfolded or unfolded, potentially toxic proteins to maintain cellular protein homeostasis. Ubiquitination is accomplished by the concerted action of three enzymatic steps involving E1 activating enzymes, E2 conjugating enzymes, and E3 ligases. Tripartite motif-containing (TRIM) proteins are one of the integral members of E3 ubiquitin ligases in metazoans modulating essential cellular pathways. For long, MuRFs (Muscle ring finger proteins) were the most extensively studied TRIMs for their cardiac function. Recent research advances in the field and our analysis presented here, however, demonstrated broader and ever increasing involvement of additional TRIM E3 ligases in the pathophysiology of heart. In this review, we summarize the known cardiac E3 ligases and their targets, and discuss their role and importance in cardiac proteostasis, pathophysiology and potential therapeutic implications with specific focus on TRIM E3 ligases.

TRIM27 functions as an oncogene by activating epithelial-mesenchymal transition and p-AKT in colorectal cancer

Tripartite motif-containing 27 (TRIM27) belongs to the tripartite motif (TRIM) protein family and is involved in various malignant tumor processes. However, the function and mechanism of TRIM27 in colorectal cancer (CRC) remains to be elucidated. In the present study, the expression of TRIM27 was analyzed in CRC tissues and adjacent normal tissues by reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. LoVo and HCT116 cell lines were then selected to further investigate the function of TRIM27 in the proliferation, invasion and metastasis of CRC in vitro and in vivo. Finally, the potential mechanism underlying the effects of TRIM27 in CRC was examined by western blotting. The results showed that TRIM27 was upregulated in CRC tissues, and the expression level of TRIM27 was significantly associated with tumor invasion, metastasis and prognosis. Following TRIM27 inhibition and overexpression in CRC cells, it was found that TRIM27 promoted cell proliferation, possibly via the inhibition of apoptosis and cell cycle regulation. TRIM27 also facilitated invasion and metastasis. Finally, it was observed that TRIM27 promoted epithelial-mesenchymal transition and activated phosphorylated AKT serine/threonine kinase in CRC cells. These results suggested that TRIM27 is an oncogenic protein in the progression of CRC, and may represent a novel target for CRC detection and therapy.