BRAF inhibitors (BRAFi) that target BRAF V600E kinase, a driver mutation found in 50% of melanomas, show a significant antitumor response, but the common emergence of acquired resistance remains a challenge. Abnormal expression of RAF isoforms CRAF and ARAF reactivates pERK1/2, which plays crucial roles in the acquisition of resistance of melanoma cells. However, the mechanisms of dysregulation of RAF isoforms in resistant melanoma cells remain unknown. Here, we identified NONO interacted with and stabilized both CRAF and ARAF in melanoma cells, and that NONO was acetylated at 198K by p300 acetyltransferase, which stabilized NONO via antagonizing its ubiquitination/degradation mediated by RNF8. The upregulation of both p300 and NONO promoted the rebound of pERK1/2 and the subsequent resistance of melanoma cells to BRAFi, and the activation of ERK1/2 in turn induced p300 to form a positive feedback loop in resistant melanoma cells. There was a positive correlation between p300 and NONO in resistant melanoma cells and clinical samples, and p300 inhibitor C646 overcame the resistance of resistant melanoma cells to BRAF inhibitors in vitro and in vivo. Our findings reveal that targeting the positive feedback loop of p300-NONO-CRAF/ARAF-pERK1/2 may be excellent strategies to overcome the resistance of BRAF inhibitors for melanoma patients.

BACKGROUND:WT161, as a selective HDAC6 inhibitor, has been shown to play anti-tumor effects on several kinds of cancers. The aim of the present study is to explore the roles of WT161 in osteosarcoma and its underlying mechanisms.METHODS:The anti-proliferative effect of WT161 on osteosarcoma cells was examined using MTT assay and colony formation assay. Cell apoptosis was analyzed using flow cytometer. The synergistic effect was evaluated by isobologram analysis using CompuSyn software. The osteosarcoma xenograft models were established to evaluate the anti-proliferative effect of WT161 in vivo.RESULTS:WT161 suppressed the cell growth and induced apoptosis of osteosarcoma cells in a dose- and time-dependent manner. Mechanistically, we found that WT161 treatment obviously increased the protein level of PTEN and decreased the phosphorylation level of protein kinase-B (AKT). More importantly, WT161 showed synergistic inhibition with 5-FU on osteosarcoma cells in vitro and in vivo.CONCLUSIONS:These results indicate that WT161 inhibits the growth of osteosarcoma through PTEN and has a synergistic efficiency with 5-FU.

Background: Long noncoding RNAs (LncRNAs) show dysregulation in a variety of cancers. However, the function and specific mechanism of LncRNA GSEC in the progression of osteosarcoma remain mostly unknown. In this study, we sought to elucidate the role and mechanism of LncRNA GSEC in the occurrence and progression of osteosarcoma. Methods: we examined the expression of LncRNA GSEC in osteosarcoma cell lines by quantitative real time PCR. In vitro experiments, including transwell assays, cck8 assays, and flow cytometry analysis have biologically demonstrated the effect of LncRNA GSEC on the proliferation and migration of osteosarcoma cell lines. Furthermore, the regulation of miR-588 by LncRNA GSEC was determined by luciferase reporter assay and quantitative real time PCR. What's more, subcutaneous tumor formation was performed in nude mice to monitor the growth of the tumor in vivo. Results: We found that the expression of LncRNA GSEC was up-regulated in osteosarcoma cell lines. Overexpression of LncRNA GSEC promoted the proliferating and migratory capacity, and inhibited the apoptosis of osteosarcoma cells. Conversely, knockdown of LncRNA GSEC resulted in the opposite effect. Mechanistically, we identified LncRNA GSEC functioned as the sponge of miR-588, thus inhibiting the miR-588/EIF5A2 signal pathway. In addition, the expression of miR-588 was negatively correlated with LncRNA GSEC, and the effect by silencing or overexpressing LncRNA GSEC could be rescued by the introduction of miR-588 mimics or inhibitors, respectively. Conclusions: In summary, this study shows that LncRNA GSEC promotes the proliferation and invasion of OS through the regulation of miR-588/EIF5A2 pathway, which might provide a new strategy for the treatment of osteosarcoma in the future. (C) 2020 Elsevier Inc. All rights reserved.

INTRODUCTION:Breast cancer metastasis suppressor 1 like (BRMS1-like)was first reported to be a component of the Sin3-HDAC complex, but the role in the progression of cancers was largely unknown. Our previous study reported that BRMS1L promoted the metastasis of breast cancer through facilitating the recruitment of HDAC complex to the promoter FZD10, and hence suppressing the transcription of FZD10. METHODS:In this study, we detected the expression level of BRMS1L in esophageal squamous cell carcinoma (ESCC). The effect of BRMS1L in TE-1D (knockdown) and ECA-109 (overexpression) cell lines was explored by transwell assays, wound healing assays, and cell adhesion assays. Quantitative real‑time PCR, Western blot analysis, and luciferase assays were used to detect the interaction of the CBP/P300-BRMS1L-ITGA7 axis. RESULTS:In the present study, we found that knockdown of BRMS1L promoted the migration, invasion, and epithelial-mesenchymal transition (EMT). Conversely, overexpression of BRMS1L inhibited the migration and invasion of ESCC. Mechanistically, BRMS1L exerted their metastasis-suppressing role via transcriptionally repress ITGA7 expression. Moreover, we revealed that CBP/p 300 regulated the expression of BRMS1L and might be responsible for the down-regulation of BRMS1L in ESCC. CONCLUSION:Collectively, we identified the role of CBP/p300-BRMS1L-ITGA7 axis in the metastasis of ESCC.

BACKGROUND:WT161 is a recently discovered histone deacetylase 6 (HDAC6) inhibitor which shows anti-tumor effects on multiple myelomas and breast cancer. However, the role of WT161 in retinoblastoma remains unclear. The aim of this study is to explore the role of WT161 in retinoblastoma and its underlying mechanisms.METHODS:The anti-proliferation of WT161 on retinoblastoma cells was examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and soft agar colony formation assay. Cell apoptosis was analyzed using flow cytometer. WT161 and DDP synergistic effect was evaluated by isobologram analysis using CompuSyn software.RESULTS:WT161 suppressed the cell growth and induced apoptosis of retinoblastoma cells in a dose- and time-dependent manner. Mechanistically, WT161 increases the transcription of Bad through activating Bad promoter. Chromatin immunoprecipitation (ChIP) assay showed WT161 treatment increased acetylated histone H3 (AcH3) and acetylated histone H4 (AcH4) on the Bad promoter in retinoblastoma cells. In addition, WT161 shows synergistically inhibitory effects on retinoblastoma cell combined with cisplatin.CONCLUSIONS:These results indicate that WT161, as a selective HDAC6 inhibitor, is a promising agent against retinoblastoma.

Osteoarthritis (OA) is a joint degenerative disease, which is prominent in the middle-aged and elderly population, often leading to repeated pain in the joints of patients and seriously affecting the life quality of patients. At present, the treatment of OA mainly depends on the surgery and drug treatment. Nevertheless, these treatments still face many problems, such as surgical safety, complications, and drug side effects. Exosomes can be secreted and released by multiple cell types and have lipid bilayer membranes and contain abundant biological molecules, including proteins, lipids, and nucleic acids. Moreover, exosomes play a critical role in local and distal intercellular and intracellular communication. In recent years, several studies have found that exosomes can regulate the progression of OA and have a potential efficacy for OA treatment. Thus, in this article, we summarize and review the relevant research of exosomes in OA and emphasize the importance of exosomes in the development of OA.

Retinoblastoma (RB) is the most common type of intraocular malignant tumor that occurs in childhood. AR-42, a member of a newly discovered class of phenylbutyrate-derived histone deacetylase inhibitors, exerts antitumor effects on many cancers. In the present study, we initially evaluated the effect of AR-42 towards RB cells and explored the underlying mechanism in this disease. Our results found that AR-42 showed powerful antitumor effects at low micromolar concentrations by inhibiting cell viability, blocking cell cycle, stimulating apoptosis in vitro, and suppressing RB growth in a mouse subcutaneous tumor xenograft model. Furthermore, the AKT/nuclear factor-kappa B signaling pathway was disrupted in Y79 cells treated with AR-42. In conclusion, we propose that AR-42 might be a promising drug treatment for RB.

Mesenchymal stem cells (MSCs) have the ability to differentiate into multiple cell types, including osteogenic, chondrogenic and adipogenic lineages. Osteogenic differentiation of MSCs plays a critical role in bone tissue engineering. Inducing MSC osteogenesis represents a potential treatment that promotes bone formation and bone regeneration. Recently, long non-coding RNA (lncRNA) was shown to participate in the occurrence and development of various diseases. Different lncRNA expression patterns can regulate the cell cycle, proliferation, metastasis, immunobiology and differentiation. With the recent extensive study of lncRNAs, an increasing number of lncRNAs are being studied in the MSC field. Furthermore, some lncRNAs have been confirmed to regulate MSC osteogenesis. Therefore, here, we review research concerning lncRNA in osteogenic differentiation of MSCs and highlight the importance of lncRNA in bone formation and bone regeneration.

Objective: To investigate the role of MAGE family member C2 in angiogenesis and epithelial-mesenchymal transition of non-small cell lung carcinoma. Methods: The Cancer Genome Atlas data set was analyzed to filter the highly expressed gene melanoma antigen family C2 in non-small cell lung carcinoma. Quantitative reverse transcription-polymerase chain reaction was performed to verify the overexpression of melanoma antigen family C2 in non-small cell lung carcinoma cell lines. Melanoma antigen family C2 complementary DNA and short hairpin RNA (shRNA) were transfected into SK-MES-1 cells to regulate melanoma antigen family C2 expression. Cell Counting Kit-8 assay, flow cytometry, wound healing assay, and Transwell assay were performed to investigate the effect of melanoma antigen family C2 on proliferation, apoptosis, migration, and invasion of SK-MES-1 cell line. Western blot was used to detect the expression of epithelial-mesenchymal transition markers. Enzyme-linked immunosorbent assay was performed to investigate the secretion of vascular endothelial growth factor, and tube formation assay was conducted to explore the effect of melanoma antigen family C2 on angiogenesis ability of the tumor. Tumor xenograft on nude mice and immunohistochemical/hematoxylin and eosin staining were also performed to detect the influence of melanoma antigen family C2 on growth and metastasis of non-small cell lung carcinoma cells. Results: Melanoma antigen family C2 was highly expressed in non-small cell lung carcinoma cells; melanoma antigen family C2 promoted the expression of epithelial-mesenchymal transition-related proteins as well as enhance the secretion of vascular endothelial growth factor and promote angiogenesis; melanoma antigen family C2 promoted proliferation, migration, and invasion and suppressed apoptosis of non-small cell lung carcinoma cells. It could also facilitate growth and metastasis of non-small cell lung carcinoma in vivo. Conclusion: Melanoma antigen family C2 was a critical factor of angiogenesis and epithelial-mesenchymal transition in non-small cell lung carcinoma.

Background: Long non-coding RNA (lncRNA) SNHG5 has been found to play an important role in tumors. Nevertheless, the function and mechanism of lncRNA SNHG5 in osteosarcoma (OS) remains unclear. The purpose of this study was to investigate whether lncRNA SNHG5 can regulate the occurrence and development of OS cells. Methods: We performed quantitative real time PCR to detect the expression of lncRNA SNHG5 in OS cells. 143B, MG63 (knockdown) and U2OS, U2R (overexpression) cell lines were chosen for the function study of SNHG5. The effect of SNHG5, miR-212-3p, and SGK3 in OS cells was explored by MTT assays, clony formation, flow cytometry, transwell assays, wound healing assays, and cell spreading assays. Quantitative real-time PCR, Western blot analysis and luciferase assays were used to detect the interaction between lncRNA SNHG5 and miR-212-3p. Results: In this study, knockdown of lncRNA SNHG5 suppressed the growth and metastasis of OS cells, whereas the overexpression of SNHG5 produced an opposite result. Mechanistically, lncRNA SNHG5 functions as a sponger against miR-212-3p and suppresses the miR-212-3p/SGK3 signaling pathway. Introduction of miR-212-3p mimics or inhibitors reverses SNHG5 overexpression or silences the exerted tumor promoting or suppressing effect. In addition, our results showed that the function of SNHG5 can be rescued by miR-212-3p and can regulate the growth and metastasis of OS cells via SGK3, the downstream target of miR-212-3p. Conclusions: In summary, our study demonstrated that lncRNA SNHG5 can regulate the proliferation and metastasis of OS cells through the miR-212-3p/SGK3 axis. This axis may provide a new target for future clinical treatment.

AR-42 is a member of a novelly discovered class of phenylbutyrate-derived histone deacetylase inhibitors, and has a number of antitumor effects in a variety of tumor types; however, the role of AR-42 and its possible mechanisms have not been reported in the treatment of breast cancer. The aim of the present study was to investigate the antitumor effects of AR-42 and its associated mechanisms in breast cancer. MTT assays and colony formation assays were conducted to measure the proliferation of MCF-7 cells, and flow cytometry was used to analyze cell apoptosis. The results revealed that AR-42 induced cell apoptosis and suppressed cell growth in a dose- and time-dependent manner. Mechanistically, AR-42 treatment increased the acetylation of the p53 protein and prolonged the half-life of the p53 protein; furthermore, AR-42 treatment upregulated p21 and PUMA expression. Notably, AR-42 had a synergistic effect on MCF-7 cells in combination with fluorouracil, which is one of the most commonly used chemotherapeutic agents. In conclusion, the results indicated that AR-42 inhibits breast cancer cell proliferation and induces apoptosis, indicating that AR-42 is a potential therapeutic agent.