USP18 enhances the resistance of BRAF-mutated melanoma cells to vemurafenib by stabilizing cGAS expression to induce cell autophagy.

This study aims to discern the possible molecular mechanism of the effect of ubiquitin-specific peptidase 18 (USP18) on the resistance to BRAF inhibitor vemurafenib in BRAF V600E mutant melanoma by regulating cyclic GMP-AMP synthase (cGAS). The cancer tissues of BRAF V600E mutant melanoma patients before and after vemurafenib treatment were collected, in which the protein expression of USP18 and cGAS was determined. A BRAF V600E mutant human melanoma cell line (A2058R) resistant to vemurafenib was constructed with its viability, apoptosis, and autophagy detected following overexpression and depletion assays of USP18 and cGAS. Xenografted tumors were transplanted into nude mice for in vivo validation. Bioinformatics analysis showed that the expression of cGAS was positively correlated with USP18 in melanoma, and USP18 was highly expressed in melanoma. The expression of cGAS and USP18 was up-regulated in cancer tissues of vemurafenib-resistant patients with BRAF V600E mutant melanoma. Knockdown of cGAS inhibited the resistance to vemurafenib in A2058R cells and the protective autophagy induced by vemurafenib in vitro. USP18 could deubiquitinate cGAS to promote its protein stability. In vivo experimentations confirmed that USP18 promoted vemurafenib-induced protective autophagy by stabilizing cGAS protein, which promoted resistance to vemurafenib in BRAF V600E mutant melanoma cells. Collectively, USP18 stabilizes cGAS protein expression through deubiquitination and induces autophagy of melanoma cells, thereby promoting the resistance to vemurafenib in BRAF V600E mutant melanoma.

Long Non-Coding RNA CRNDE Functions as a Tumor Promoter by Modulating the ERK/MAPK Signaling Pathway in Neuroblastoma Cells.

OBJECTIVE: The long non-coding RNA (lncRNA) colorectal neoplasia differentially expressed (CRNDE) is considered a carcinogenic promoter in various human malignancies. However, the role and underlying mechanism of action of CRNDE during carcinogenesis in neuroblastoma remain unknown. METHODS: CRNDE transcript levels were detected in neuroblastoma tissues and adjacent normal tissues. The effects of CRNDE overexpression and knockdown on the viability of SH-SY5Y and SK-N-AS cells were determined using the Cell Counting Kit-8 (CCK-8) assay. Flow cytometry was performed to measure the role of CRNDE in apoptosis and the cell cycle in neuroblastoma cells. Moreover, the transwell assay was used to evaluate the role of CRNDE in the migration and invasion of tumor cells. The levels of ERK/MAPK pathway-related proteins were evaluated using western blotting. The in vivo role of CRNDE in tumor growth and apoptosis was evaluated in a xenograft mouse model of human neuroblastoma. RESULTS: The relative expression of CRNDE was significantly higher in neuroblastoma tissues than in the adjacent normal tissues. Moreover, knockdown of CRNDE inhibited tumor cell proliferation and induced apoptosis and cell cycle arrest, whereas elevation of CRNDE promoted cell growth and inhibited apoptosis in neuroblastoma cells. In addition, depletion of CRNDE suppressed migration and invasion, whereas overexpression of CRNDE enhanced the migratory and invasive potential of SH-SY5Y and SK-N-AS cells. At the mechanistic level, western blotting showed that CRNDE exerted its oncogenic role by affecting the ERK/MAPK signaling pathway. Furthermore, animal experiments confirmed that CRNDE promotes tumor growth and inhibits apoptosis in neuroblastoma in vivo. CONCLUSION: The present study revealed that CRNDE plays a critical role in the proliferation, apoptosis, migration, and invasion of neuroblastoma by altering the ERK/MAPK signaling pathway, representing a novel molecular target for the treatment of neuroblastoma.

Nuclear paraspeckle assembly transcript 1 promotes the metastasis and epithelial-mesenchymal transition of hepatoblastoma cells by inhibiting miR-129-5p.

The abnormal expression of nuclear paraspeckle assembly transcript 1 (NEAT1) may serve critical functions for the development and progression of various types of human tumor. However, the expression and biological function of NEAT1 in hepatoblastoma (HB) and the underlying mechanisms for the function of NEAT1 in HB remain largely uncharacterized. In the present study, the results of reverse transcription-quantitative polymerase chain reaction revealed that the expression of NEAT1 was significantly elevated in HB tissues. HB tissues with metastasis also exhibited significantly increased levels of NEAT1 compared with tissues without metastasis. The biological functions of NEAT1 were then assessed using gain-/loss-of-function studies. The results of in vitro assays revealed that inhibiting NEAT1 expression reduced the migration and invasion of HepG2 cells. By contrast, the induced expression of NEAT1 exhibited the opposite effect. The present study also demonstrated that the inhibition of NEAT1 expression prevented the epithelial-mesenchymal transition of HepG2 cells, whereas forced expression of NEAT1 exhibited the opposite effect. In addition, it was confirmed that NEAT1 could modulate the expression of microRNA (miR)-129-5p in HepG2 cells, and that NEAT1 may exert its effect on the metastatic behaviors and epithelial-mesenchymal transition of HepG2 cells by inhibiting miR-129-5p. In conclusion, the present study indicated that NEAT1 expression was aberrantly increased in HB and that it may promote the metastasis of HB cells by inhibiting miR-129-5p. Targeting NEAT1 may potentially be a novel therapeutic option for treating patients with HB.

MiR-513c suppresses neuroblastoma cell migration, invasion, and proliferation through direct targeting glutaminase (GLS).

Neuroblastoma is a malignancy [corrected] of childhood and accounts for 7-10% of childhood cancers, leading to approximately 15% of pediatric cancer deaths. MicroRNAs (miRNAs) are a family of short (about 18-25 nucleotides), noncoding and single stranded endogenous RNAs, which complementarily bind to the 3' untranslated regions of their target genes. Recently, glutamine metabolism has been recognized as an important nutrition source for tumor cells, and hence targeting glutamine metabolism could benefit to development of anti-cancer agents. In this study, we investigate the roles of miR-513c in human neuroblastoma. We report miR-513c is significantly downregulated in human neuroblastoma tissues compared with their adjacent normal tissues. Moreover, miR-513c is significantly downregulated in neuroblastoma cell lines compared with normal neuroblast cells. Overexpression of miR-513c suppresses neuroblastoma cells' migration, invasion, and proliferation. We demonstrate the glutaminase (GLS) is a direct target of miR-513c in human neuroblastoma cells. In addition, we found restoration of GLS expression recovered the neuroblastoma cells' migration, invasion, and proliferation. In summary, this study illustrates a miR-513c mediated neuroblastoma cells suppression, providing a new aspect on the miRNA-based therapeutic approach for the treatments of neuroblastoma.