Endogenous melatonin concentration along with the expression of mitochondrial regulator genes is elevated by the serum shock process in the U87-MG cell line
Authors: Balkhi Shayan , Jazi Marie Saghaeian , Samaei Nader Mansour , Farahmandrad Mahtab 
Published: March 2022

Abstract
According to the World Health Organization, glioblastoma, also known as the fourth grade in the development of astrocytoma, is a glial tumor limited to the central nervous system with a strong ability to invade the brain parenchyma. Melatonin can be generated outside of the pineal gland tissue, according to new research. Melatonin is produced by mitochondria independently but in concert with cell demands, and it plays an important function in cell cycle and metabolism regulation. As a result, we set out to investigate the association between cell metabolism and the serum shock-induced increase in endogenous melatonin, as well as the percentage of cell proliferation.Background: Melatonin can be produced in the mitochondria organelle of glioblastoma cells without the involvement of the pineal gland, according to new research. Regarding the physiological function of melatonin secreted by the pineal gland in the regulation of rhythmicity, the goal of this study was to see if the glioblastoma cell's melatonin production ability could be influenced using a typical serum shock technique established for cellular rhythm regulator.Material and methods: First, U87-MG glioblastoma cells were cultured in a DMEM medium containing 10% FBS and then cells were treated with a standard serum shock process (no FBS, 8h). The concentration of melatonin was measured using ELISA method in supernatant and cell extracts of Shock and control groups. The cell proliferation was measured by using BrdU staining and flow cytometry assessment. The gene expression levels of some mitochondria or circadian related genes including TFAM, BMAL1, PPARGC1A(PGC1-α), and DNM1L(DRP1) were measured, using qRT-PCR method.Results: In comparison to the control group, serum shock treated U87-MG glioblastoma cells had higher concentrations of cellular and released endogenous melatonin (two times). At the mRNA level, we discovered considerable upregulation of mitochondrial or circadian regulator genes (TFAM, BMAL1, PPARGC1A, and DNM1L); in the shock group compared to the control group (P <0.0002). Furthermore, although the percentage of proliferative cells (Brdu positive) was higher in the shock group, it was not statistically significant.Conclusion: The serum shock procedure has a significant impact on the U87-MG cell line's cellular activity. In terms of the study's findings, it's worth noting that an increase in endogenous melatonin concentration influences several signaling pathways within the U87-MG cell line, as seen by the increased expression of candidate genes.In light of the findings of this study, it's worth noting that further research into the role of endogenous melatonin and its effects on cancer cells is critical, and that comparing the results of normal and cancer cells can reveal the hotspots of the signaling pathways involved, which could facilitate in better understanding the biology of glioblastoma.