Suppressing STAT5 signaling affects osteosarcoma growth and stemness

Abstract

Osteosarcoma (OS) is the most common primary bone tumor that primarily affects children and adolescents. Studies suggested that dysregulation JAK/STAT signaling promotes the development of OS. Cells treated with pimozide, a STAT5 inhibitor suppressed proliferation and colony formation and induced sub G0/G1 cell cycle arrest and apoptosis. There was a reduction in cyclin D1 and CDK2 expression and Rb phosphorylation, and activation of Caspase-3 and PARP cleavage. In addition, pimozide suppressed the formation of 3-dimensional osteospheres and growth of the cells in the Tumor in a Dish lung organoid system. Furthermore, there was a reduction in expression of cancer stem cell marker proteins DCLK1, CD44, CD133, Oct-4, and ABCG2. More importantly, it was the short form of DCLK1 that was upregulated in osteospheres, which was suppressed in response to pimozide. We further confirmed by flow cytometry a reduction in DCLK1+ cells. Moreover, pimozide inhibits the phosphorylation of STAT5, STAT3, and ERK in OS cells. Molecular docking studies suggest that pimozide interacts with STAT5A and STAT5B with binding energies of −8.4 and −6.4 Kcal/mol, respectively. Binding was confirmed by cellular thermal shift assay. To further understand the role of STAT5, we knocked down the two isoforms using specific siRNAs. While knockdown of the proteins did not affect the cells, knockdown of STAT5B reduced pimozide-induced necrosis and further enhanced late apoptosis. To determine the effect of pimozide on tumor growth in vivo, we administered pimozide intraperitoneally at a dose of 10 mg/kg BW every day for 21 days in mice carrying KHOS/NP tumor xenografts. Pimozide treatment significantly suppressed xenograft growth. Western blot and immunohistochemistry analyses also demonstrated significant inhibition of stem cell marker proteins. Together, these data suggest that pimozide treatment suppresses OS growth by targeting both proliferating cells and stem cells at least in part by inhibiting the STAT5 signaling pathway.

lncRNA SNHG10 Promotes the Proliferation and Invasion of Osteosarcoma via Wnt/β-Catenin Signaling

“…The Wnt/b-catenin signaling pathway has been reported to be involved in controlling OS development. 21 Because FZD3 is a direct target of miR-182-5p, we investigated whether miR-182-5p affected Wnt by regulating FDZ3. Overexpression of miR-182-5p significantly decreased b-catenin nuclear accumulation, whereas b-catenin was increased in the cytoplasm (Figures S3A and S3B).…”

Pimozide augments bromocriptine lethality in prolactinoma cells and in a xenograft model via the STAT5/cyclin D1 and STAT5/Bcl‑xL signaling pathways

“…Bromocriptine regulates several signaling pathways in tumorigenesis and progression, including the PI3K/AKT and the MAPK/JNK/ERK signaling pathways (4,40). Previous studies have also revealed that STAT proteins are important downstream targets of MAPK and JAK signaling (19,(41)(42)(43). Although the exact mechanism is not completely understood, it has been hypothesized that there may be crosstalk between the STAT5 and JNK/MAPK pathways.…”

“…The aim of the present study was to evaluate the activation status of the JAK2/STAT5 signaling pathway in bromocriptine-resistant prolactinoma tissues and to assess the potential chemotherapeutic sensitizing effect of pimozide on the bromocriptine-resistant prolactinoma cells. As tumor stem cells serve a vital role in tumor recurrence, metastasis and drug resistance ( 16 , 18 , 19 ), the effect of pimozide on prolactinoma cell stemness was also assessed. Collectively, these experiments provide a rationale for further clinical studies on the use of pimozide as a chemosensitizer in bromocriptine-resistant prolactinomas.…”

Systems Medicine Design based on Systems Biology Approaches and Deep Neural Network for Gastric Cancer

“…However, more and more studies have indicated that it also held the ability to suppress cancer cells [73][74][75]. Furthermore, pimozide has been demonstrated that its treatment resulted in the decreased level of BCL2 [76]. In addition to the treatment of chronic immune thrombocytopenia [77], there is a study showing that repurposing of fostamatinib is an effective treatment to inhibit metastatic tumor outgrowth in breast cancer [78].…”