β-Arrestin2 Inhibits the Apoptosis and Facilitates the Proliferation of Fibroblast-like Synoviocytes in Diffuse-type Tenosynovial Giant Cell Tumor

Increased methylation of ZNF671 suppresses tumor progression by promoting MAPK6 transcription in laryngeal carcinoma

Background: Laryngeal squamous cell carcinoma (LSCC) is a malignant tumor of the head and neck, the exact mechanism of which has not been explored. Methods: By analyzing the GEO data, we found the highly methylated and low expression gene ZNF671. The expression level of ZNF671 in clinical samples was verified by RT-PCR, western blotting and methylation-specific PCR. The function of ZNF671 in LSCC was detected by cell culture and transfection, MTT, Edu, TUNEL assays and flow cytometry analysis. The binding sites of ZNF671 to MAPK6 promoter region were detected and verified by luciferase reporter gene and chromatin immunoprecipitation. Finally, the effect of ZNF671 on LSCC tumors was tested in vivo. Results: In this study, by analyzing GEO data GSE178218 and GSE59102, we found that zinc finger protein (ZNF671) expression was decreased, and DNA methylation level was increased in laryngeal cancer. Moreover, the abnormal expression of ZNF671 was associated with poor survival prognosis of patients. In addition, we found that overexpression of ZNF671 could inhibit the viability, proliferation, migration and invasion of LSCC cells, while promoting cell apoptosis. In contrast, the opposite effects were observed after knockdown of ZNF671. Through the prediction website and chromatin immunoprecipitation and luciferase reporter experiments, it was found that ZNF671 could bind to the promoter region of MAPK6, thereby inhibiting the expression of MPAK6. In vivo experiments confirmed that overexpression of ZNF671 could inhibit tumor growth. Conclusion: Our study found that ZNF671 expression was down-regulated in LSCC. ZNF671 up-regulates the expression of MAPK6 by binding to its promoter region, thus participating in cell proliferation, migration and invasion in LSCC. Our study may provide new ideas for early prediction and treatment of LSCC.

A Novel Splice Variant of BCAS1 Inhibits β-Arrestin 2 to Promote the Proliferation and Migration of Glioblastoma Cells, and This Effect Was Blocked by Maackiain

Brain-enriched myelin-associated protein 1 (BCAS1) is frequently highly expressed in human cancer, but its detailed function is unclear. Here, we identified a novel splice variant of the BCAS1 gene in glioblastoma multiforme (GBM) named BCAS1-SV1. The expression of BCAS1-SV1 was weak in heathy brain cells but high in GBM cell lines. The overexpression of BCAS1-SV1 significantly increased the proliferation and migration of GBM cells, whereas the RNA-interference-mediated knockdown of BCAS1-SV1 reduced proliferation and migration. Moreover, using a yeast-two hybrid assay, immunoprecipitation, and immunofluorescence staining, we confirmed that β-arrestin 2 is an interaction partner of BCAS1-SV1 but not BCAS1. The downregulation of β-arrestin 2 directly enhanced the malignancy of GBM and abrogated the effects of BCAS1-SV1 on GBM cells. Finally, we used a yeast two-hybrid-based growth assay to identify that maackiain (MK) is a potential inhibitor of the interaction between BCAS1-SV1 and β-arrestin 2. MK treatment lessened the proliferation and migration of GBM cells and prolonged the lifespan of tumor-bearing mice in subcutaneous xenograft and intracranial U87-luc xenograft models. This study provides the first evidence that the gain-of-function BCAS1-SV1 splice variant promotes the development of GBM by suppressing the β-arrestin 2 pathway and opens up a new therapeutic perspective in GBM.

Tenosynovial giant cell tumors (TGCT): molecular biology, drug targets and non-surgical pharmacological approaches

INTRODUCTION

Tenosynovial giant cell tumor (TGCT) is a mono-articular, benign or locally aggressive and often debilitating neoplasm. Systemic therapies are becoming part of the multimodal armamentarium when surgery alone will not confer improvements. Since TGCT is characterized by colony-stimulating factor-1 (CSF1) rearrangements, the most studied molecular pathway is the CSF1 and CSF1 receptor (CSF1R) axis. Inhibiting CSF1-CSF1R interaction often yields considerable radiological and clinical responses; however, adverse events may cause treatment discontinuation because of an unfavorable risk-benefit ratio in benign disease. Only Pexidartinib is approved by the US FDA; however, the European Medicines Agency has not approved it due to uncertainties on the risk-benefit ratio. Thus, there is a need for safer and effective therapies.

AREAS COVERED

Light is shed on disease mechanisms and potential drug targets. The safety and efficacy of different systemic therapies are evaluated.

EXPERT OPINION

The CSF1-CSF1R axis is the principal drug target; however, the effect of CSF1R inhibition on angiogenesis and the role of macrophages, which are essential in the postoperative course, needs further elucidation. Systemic therapies have a promising role in treating mainly diffuse-type, TGCT patients who are not expected to clinically improve from surgery. Future drug development should focus on targeting neoplastic TGCT cells.