We next examined the effect of CM-FDMSC on the invasive capabilities of A375 melanoma cells using transwell invasion assays (Figure 7A). reductions in viability, migration, and invasion. CM-FDMSC-treated A375 cells showed decreased phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and extracellular signal-regulated kinase (ERK) phosphorylation, and up-regulation of Bcl-2-Associated X (BAX) and down-regulation of B-cell lymphoma-2 (BCL-2) expression. Conclusion: CM-FDMSC can inhibit the tumor-forming behaviors of A375 melanoma cells and inhibit PI3K/AKT and mitogen-activated protein kinase signaling to shift their BCL-2/BAX ratio toward a proapoptotic state. Identification of the bioactive components in CM-FDMSC will be important for translating these findings into HVH-5 novel Sodium succinate therapies for malignant melanoma. Keywords: human fetal dermal mesenchymal stem cells, melanoma, conditioned media, apoptosis, PI3K/AKT signaling pathway, MAPK signaling pathway Introduction Malignant melanoma is one of the most aggressive skin tumors derived from malfunctioning of normal melanocytes. The incidence of melanomas continues to increase at a high rate, particularly in western populations.1,2 Although melanoma represents a small proportion of skin cancers, it accounts for 75% of skin cancer deaths in the United States.3,4 The increasing rate of morbidity of melanoma is attributed mainly to its invasive potential and high resistance to many conventional therapies.5,6 Therefore, it is urgent to develop alternative and innovative therapies to improve clinical outcomes. Mesenchymal stem cells (MSCs) exist in various tissues, including bone marrow, adipose tissue, synovial membrane, periodontal ligament, and skin.7C10 MSCs are pluripotent Sodium succinate progenitor cells and have shown potential in tissue engineering and regenerative medicine.11 Previous studies suggested that MSCs might become a promising treatment strategy for neurological dysfunctions, diabetic, cardiomyopathy, glaucoma, and urological diseases.12C15 Importantly, MSCs can effectively inhibit the development of some types of tumors.16C19 Fetal dermal MSCs (FDMSCs) can be isolated from aborted fetal skin and have the ability to differentiate into multiple cell types, although their full characteristics are still under investigation. Our previous study showed that paracrine factors secreted by FDMSCs could inhibit keloid growth.20 Phosphatidylinositol 3-kinase Sodium succinate (PI3K)/protein kinase B (AKT) signaling pathway regulates most hallmarks of cancer, including cell survival, metabolism, motility, invasion, and genomic instability.21 Activation of the PI3K pathway can promote tumor development by enhancing cell survival. Mitogen-activated protein kinase (MAPK) signal pathway plays an important role in many biological functions such as cell proliferation, adhesion, survival, and differentiation. It also participates in tumorigenesis and regulates the apoptotic process. MAPK pathway is activated in most melanomas because of the oncogenic serine-threonine protein kinase B-RAF (BRAF) mutations. Inhibiting MAPK pathway shows therapeutic benefit in melanoma treatment.22C24 Thus, we hypothesized that the antitumor effects of FDMSCs were mediated by paracrine manner through PI3K/AKT and MAPK signaling pathways. Our studies revealed that CM-FDMSC inhibits A375 cell behaviors associated with tumor formation in vivo and in vitro. Our data supports a model wherein biologically active factors present in CM-FDMSC inhibit PI3K/AKT and MAPK signaling to promote apoptosis of A375 melanoma cells and suggests that FDMSC-derived paracrine factors could lead to novel therapeutic approaches for melanoma. Methods and materials Cell culture and preparation of conditioned media from FDMSCs Our research was conducted in accordance with the Declaration of Helsinki. All of the patients or their guardians provided written informed consent, and we received the ethical approval of the Ethics Committee of the Second Hospital of Sodium succinate Shandong University, Jinan, China, in fetal skin isolation. The ethics certificate was issued on 1st June, 2017 and the certificate number is KYLL-2018(LW)-006. FDMSCs were extracted from the dorsal skin of fetal samples obtained from the Second Hospital of Shandong University and identified as described in our previous study.20 A375 melanoma cells lines were obtained from American Type.