Cancer stem cells (CSCs) are defined as a small population of cancer cells with the properties of high self-renewal, differentiation, and tumor-initiating functions. Recent studies have demonstrated that aldehyde dehydrogenase 1 (ALDH1) is a marker for CSCs in adult cancers. Although CSCs have been identified in some different types of pediatric solid tumors, there have been no studies regarding the efficacy of ALDH1 as a marker for CSCs. Therefore, in order to elucidate whether ALDH1 can be used as a marker for CSCs of pediatric sarcoma, we examined the characteristics of a population of cells with a high ALDH1 activity (ALDH1high cells) in rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children. We used the human embryonal RMS (eRMS) cell lines RD and KYM-1, and sorted the cells into two subpopulations of ALDH1high cells and cells with a low ALDH1 activity (ALDH1low cells). Consequently, we found that the ALDH1high cells comprised 3.9% and 8.2% of the total cell population, respectively, and showed a higher capacity for self-renewal and tumor formation than the ALDH1low cells. With regard to chemoresistance, the survival rate of the ALDH1high cells was found to be higher than that of the ALDH1low cells following treatment with chemotherapeutic agents for RMS. Furthermore, the ALDH1high cells exhibited a higher degree of pluripotency and gene expression of Sox2, which is one of the stem cell markers. Taken together, the ALDH1high cells possessed characteristics of CSCs, including colony formation, chemoresistance, differentiation and tumor initiation abilities. These results suggest that ALDH1 is a potentially useful marker of CSCs in eRMS.
Rhabdomyosarcoma (RMS) is a malignant mesenchymal tumor and the most common soft tissue sarcoma in children. Because of several complications associated with intensive multimodal therapies, including growth disturbance and secondary cancer, novel therapies with less toxicity are urgently needed. C‐type natriuretic peptide (CNP), an endogenous peptide secreted by endothelial cells, exerts antiproliferative effects in multiple types of mesenchymal cells. Therefore, we investigated whether CNP attenuates proliferation of RMS cells. We examined RMS patient samples and RMS cell lines. All RMS clinical samples expressed higher levels of guanylyl cyclase B (GC‐B), the specific receptor for CNP, than RMS cell lines. GC‐B expression in RMS cells decreased with the number of passages in vitro. Therefore, GC‐B stable expression lines were established to mimic clinical samples. CNP increased cyclic guanosine monophosphate (cGMP) levels in RMS cells in a dose‐dependent manner, demonstrating the biological activity of CNP. However, because cGMP is quickly degraded by phosphodiesterases (PDEs), the selective PDE5 inhibitor sildenafil was added to inhibit its degradation. In vitro, CNP, and sildenafil synergistically inhibited proliferation of RMS cells stably expressing GC‐B and decreased Raf‐1, Mitogen‐activated protein kinase kinase (MEK), and extracellular signal‐regulated kinase (ERK) phosphorylation. These results suggested that CNP in combination with sildenafil exerts antiproliferative effects on RMS cells by inhibiting the Raf/MEK/ERK pathway. This regimen exerted synergistic effects on tumor growth inhibition without severe adverse effects in vivo such as body weight loss. Thus, CNP in combination with sildenafil represents a promising new therapeutic approach against RMS.
Abstract. Survivin, a member of the inhibitor of apoptosis protein family, functions as a key regulator of programmed cell death. YM155 is a small molecule that selectively inhibits survivin. We investigated the effect of YM155 on survivin suppression in the human rhabdomyosarcoma (RMS) cell line RD. The efficacy of YM155 in combination with cisplatin was also determined in a xenograft model. The effect of YM155 on survivin expression in the RD cell line was examined at both mRNA and protein levels using real-time PCR and western blot analysis. RD cells were cultured with various concentrations of YM155, then cisplatin was added to the medium and the anti-proliferation response was determined. Cell growth was evaluated by WST-8 assay. Finally, the efficacy of YM155 combined with cisplatin was examined in an established xenograft model. Survivin mRNA levels in the RD cell line were decreased to 72 and 24% at 24 and 48 h, respectively, after 10 nM of YM155 was added. YM155 also decreased the levels of survivin protein. YM155 treatment (10 nM) inhibited cell proliferation of RD in a dose-dependent manner in vitro, with 58% of cells viable at 48 h. When cultured with 10 nM of YM155 and 10 µM cisplatin, RD cells demonstrated only 25% of the growth observed when cultured with cisplatin alone. YM155 in combination with cisplatin significantly inhibited tumor growth by 13% compared with control (P<0.0001) in RD xenograft tumors. YM155 increased the sensitivity of cisplatin by suppressing survivin in the embryonal RMS cell line RD. Further studies should investigate the use of YM155 as an apoptosis inducer, either alone or in combination with cisplatin, for the treatment of malignant RMS.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.