Determining the effect of retinoic acid on PI3K/AKT and RAS/MAPK pathways on childhood solid tumors by using western blot

Neuroblastoma is an embryonic tumor originating from the neural crest. It is the most common extracranial solid tumor in children under 5 years of age. Despite intensive protocols andalternative treatment approaches in advanced-stage disease, the two-year survival rate is only30-40%. Differentiation ofcancer cells by stimulation with agents has become a promising strategy in anti-neoplastictherapy. Retinoic acid (RA) has been clinically used to induce cellular differentiation inneuroblastoma. RA is an agent that continues to be investigated in terms of therapeutic potentialin in-vitro and in- vivo studies. The biological effects of retinoids in the cells are mediatedthrough ligands that bind to retinoic acid receptor (RAR) and retinoid X receptor (RXR). PI3K/AKT and RAS/MAPK are pathways that associated with survival and cell proliferationin cancer. Up to date, PI3K/AKT pathway has been studied more intensively in neuroblastomacells. In contrast, the relationship between RAS/MAPK and associated ERK1/2 pathway, RA and cisplatin in NB cells has not been investigated. The aim of this study is to determine the effect of RA, cisplatin and combinations on the proteinexpressions of AKT, Bcl-2, MAPK (Erk1/2), and Ras related to PI3K/AKT and RAS/MAPK-related ERK1/2 pathways in two childhood solid tumor types of NB cells. For this purpose, LD50 was detected in KELLY and LAN5 cells produced in cell culture and these doses were applied. For the effect on PI3K / AKT and RAS / MAPK-associated ERK1 / 2 pathway, Akt, p44 (Erk1 / 2), Ras and EGFR protein expressions were evaluated by immunocytochemical and Western Blot method. Differentiation was morphologically evaluated in Toludin Blue staining. Non-parametric Mann-Whitney U and Chi-square tests were used statistically. RA showed no significant effect on PI3K / AKT and RAS / MAPK-associated ERK1 / 2 pathway, but differentiation and proliferation inhibiting effect were at the forefront. Tac appears to be not a good candidate for treatment because it increases Akt expression. The fact that RA is not effective on RA, PI3K / AKT and RAS / MAPK-related ERK1 / 2 pathway supports the importance of being a candidate metronomic differentiation agent. It is not expected that a differentiating agent will affect this pathway in an anti-cancer direction. Keywords: Neuroblastoma, Retinoic Acid, Cisplatin, Signal Pathways