Evidences of oxidative stress during the development of experimental pituitary tumor cell damage respone and its posible contribution to cell senescence

EZEQUIEL GRONDONA; MONGI BRAGATO BETHANIA; LUCÍA CARREÑO; LILIANA DEL VALLE SOSA; MARIA EUGENIA SABATINO; ALICIA TORRES; ALEXANDRA LATINI; ANA L DE PAUL

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

SAIC

The control of reactive oxygen species (ROS) levels is crucial to guarantee cell survival, since their excessive production is able to promote damages in different cell structures. We have previously demonstrated signs ofcellular senescence as mechanism of proliferative arrest and alterations in mitochondrial metabolism and dynamics in experimental pituitary tumors. Since mitochondrial dysfunction has been associated with senescence and this organelle is the main source of ROS, we aimed to analyze the activation of cellular damage response mechanisms to counteract the lesions promoted by oxidative stress.To promote pituitary tumors, estradiol benzoate was implanted subcutaneously in slow releasing silastic brand capsules(10mg) in adult male Wistar rats for 10, 20, 40 and 60 days. Control group: animals were treated with empty capsules. Subsequently, ROS production was determined by flow cytometry, carbonylated proteins by spectrophotometry; γ-H2AX; 8OHdG, total and phosphorylated Nrf2 and HO-1 was assessed by immunohistochemistry and western blot; OGG1 by PCR; and glutathione levels by colorimetry assays. Statistical analysis: ANOVA-Fischer (p <0.05).From early stages of tumoral development, a progressive increase in ROS levels was detected accompanied by increases in carbonylated proteins and protein expression of DNA damage markers: γ-H2AX and 8OHdG, exposing signs of oxidative stress. Also, significant increases in OGG1, Nrf2, p-Nrf2 and HO-1oxidative stress response markerswere also observed, in addition to fluctuations in glutathione levels,revealingearly antioxidant activation in response to oxidative damage.Our data demonstrate that oxidative stress response activation triggered during pituitary tumoral development was accompanied by detoxifying mechanisms and DNA damage repair, thus favouring the redox balance recovery and cell survival. These results support the emergence cellular senescenceas an intrinsic barrier for the pituitary tumoral growth.