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

Abstract

Background/Aim: Diffuse-type tenosynovial giant cell tumor (TGCT) is a rare benign proliferative synovial neoplasm of uncertain etiology, and the efficacy of surgical resection is not satisfactory. Therefore, there is an urgent need to explore the pathogenesis and identify novel therapeutic targets for TGCT. Materials and Methods: Synovial tissues were collected from patients with TGCT and osteoarthritis (OA). Differences of mRNA expression between TGCT and OA were explored using mRNA-seq. In addition, fibroblast-like synoviocytes (FLS) were treated with small interfering RNA (siRNA) or adenovirus in order to knockdown or overexpress β-arrestin2 (Arrb2), respectively. FLS proliferation and apoptosis were evaluated using the MTT assay and the caspase 3 activity assay, respectively. Results: The expression of Arrb2 in TGCT was significantly higher than that in OA. The overexpression of Arrb2 promoted the proliferation of FLS and inhibited its apoptosis, while knocking down Arrb2 had the opposite effect. Further studies showed that Arrb2 can activate the PI3K-Akt signaling pathway, leading to increased proliferation of TGCT. Conclusion: Arrb2 facilitates the proliferation and inhibits the apoptosis of TGCT FLS through activating the PI3K-Akt cell survival pathway, providing new insight into the molecular mechanism of TGCT.Diffuse-type tenosynovial giant cell tumor (TGCT) is a rare benign proliferative synovial neoplasm characterized by villous and nodular lesions of an uncertain etiology (1). The main clinical features of TGCT are synovial hyperplasia and recurrence. The hyperplastic synovial tissue will produce a large amount of bloody synovial fluid and cause excessive swelling of the joints, further causing joint pain and dysfunction (2). Uncontrollable excessive synovial proliferation can even cause malignant transformation of TGCT and result in amputation (3). Fibroblast-like synoviocytes (FLS), as the main constituent cell type of TGCT, play an important role in its proliferation, recurrence, and malignant transformation (4). Because its pathogenesis is currently unclear, the therapeutic mainstay of TGCT is limited to removing the entire pathological synovial tissue (5). However, surgical resection alone often cannot completely remove the diseased synovium; the residual synovium will rapidly proliferate and cause postoperative recurrence, at a rate of approximately 21-50% (6). Postoperative radiotherapy is often needed to reduce recurrence, but radiotherapy can lead to a series of complications such as joint adhesion (7). Therefore, there is an urgent need to explore the pathogenesis of TGCT and identify novel therapeutic targets, especially focusing on the inhibition of its proliferation and recurrence.β-Arrestin 2 (Arrb2) is widely expressed in various tissues and involved in mediating G protein coupled receptor (GPCR) desensitization, internalization, degradation and 461 This article is freely accessible online.

Multimodal management of tenosynovial giant cell tumors (TGCT) in the landscape of new druggable targets

“…In addition, the effect of intra‐articular injections with CSF1R inhibitors is being studied, hoping to cause fewer systemic AEs but having at least comparable local efficacy (AMB‐05X, NCT04731675). Finally, modulation of other targets than CSF1 or overlapping pathways may provide new solutions in the future 29,41,49,50,75 …”

“…Beta‐arrestin2 (ARRB2) is highly expressed in TGCT and is associated with cell survival, apoptosis, migration, and proliferation in several tumor types 50 . Knockdown of ARRB2 has been shown to inhibit cell proliferation and increase apoptosis of fibroblast‐like synovitis (FLS), suggesting that ARRB2 could be a potential molecular target in TGCT treatment 50 …”

“…Finally, modulation of other targets than CSF1 or overlapping pathways may provide new solutions in the future. 29,41,49,50,75 7. Although systemic therapies are primarily used as a standalone treatment in patients with advanced TGCT, their role as neoadjuvant therapy and in an earlier stage of the disease is yet to be explored.…”

“…50 Knockdown of ARRB2 has been shown to inhibit cell proliferation and increase apoptosis of fibroblast-like synovitis (FLS), suggesting that ARRB2 could be a potential molecular target in TGCT treatment. 50 Proliferator-activated receptor gamma (PPARγ), a member of the nuclear receptor superfamily of transcription factors, is expressed at high levels in adipose tissue and monocyte-derived macrophages and stimulates adipocyte and macrophage differentiation. 51 Ligand activation of PPARγ in monocytes/macrophages inhibits inflammatory mediator and cytokine production.…”

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

“…It also enhances kisspeptin-10-induced transactivation of epidermal growth factor receptor and breast cancer cell invasion by regulating matrix metalloprotease (MMP)-9 secretion and activity [ 56 ]. Moreover, β-arrestin 2 promotes intestinal tumor initiation and growth by activating the Wnt pathway [ 57 ] and promotes cell proliferation in diffuse-type tenosynovial giant cell tumor by activating the PI3K-Akt signaling pathway to inhibit apoptosis [ 58 ]. β-arrestin 2 can also promote colorectal cancer growth and migration [ 59 ], and proliferation and anti-apoptosis of ovarian cancer cells [ 60 ] by triggering Wilms tumor 1-associated protein (WTAP).…”