RH-30

Reduced B7-H3 Expression by PAX3-FOXO1 Knockdown Inhibits Cellular Motility and Promotes Myogenic Differentiation in Alveolar Rhabdomyosarcoma

B7-H3 (also known as CD276) is associated with aggressive characteristics in various cancers. Meanwhile, in alveolar rhabdomyosarcoma (ARMS), PAX3-FOXO1 fusion protein is associated with increased aggressiveness and poor prognosis. In the present study, we explored the relationship between PAX3-FOXO1 and B7-H3 and the biological roles of B7-H3 in ARMS. Quantitative real time PCR and flow cytometry revealed that PAX3-FOXO1 knockdown downregulated B7-H3 expression in all the selected cell lines (Rh-30, Rh-41, and Rh-28), suggesting that PAX3-FOXO1 positively regulates B7-H3 expression (Fig. 1). Wound healing and transwell migration assays revealed that both PAX3-FOXO1 and B7-H3 were associated with cell migration. Furthermore, knockdown of PAX3-FOXO1 or B7-H3 induced myogenin expression in all cell lines (Fig. 2).

Fig. 1. Knockdown of PAX3-FOXO1 downregulates the expression of B7-H3 (Kanayama, Takuyo, et al. 2021).

Fig. 2. Knockdown of PAX3-FOXO1 and B7-H3 induces the expression of myogenin and may induce myoblast differentiation (Kanayama, Takuyo, et al. 2021).

A Rhabdomyosarcoma Spheroid Culture Model for In Vitro Evaluation of Hypericin-Based Photodynamic Therapy

Advanced stages of pediatric alveolar rhabdomyosarcoma (RMA) are associated with an unfavorable outcome at established therapeutic strategies, accentuating the need for novel treatment options. Photodynamic therapy (PDT) with hypericin (HYP) has shown strong cytotoxic effects in two-dimensional (2D) cell culture. In order to more accurately mimic in vivo tissue architecture and better predict pharmaceutical response, the aim of this study was to establish a spheroid culture model by which PDT efficacy could be assessed in a three-dimensional (3D) context. Compared to 2D cell culture, a higher treatment resistance was detected, which can be related to spheroid structure and mechanisms of intercellular communication, signal transduction, and gene expression.

Fig. 3. Evaluation of hypericin (HYP)-based photodynamic therapy (PDT) effects on apoptosis marker expression of RH-30 tumor spheroids (Hempfling, Laura, et al. 2022).