ESTROGENS PROMOTE GH3 SOMATOLACTOTROPE CELL SURVIVAL THROUGH NUCLEAR FACTOR KAPPA B (NF-κB) PATHWAY

EIJO G; MORENO AYALA M A; JAITA G; ZARATE S; MAGRI ML; GOTTARDO MF; FERRARIS J; PISERA D; SEILICOVICH A

San Francisco

Congreso; 95th annual meeting of The Endocrine Society; 2013

ESTROGENS PROMOTE GH3 SOMATOLACTOTROPE CELL SURVIVAL THROUGH NUCLEAR FACTOR KAPPA B (NF-¦ÊB) PATHWAY G Eijo, M Moreno Ayala, G Jaita, S Z¨¢rate, M L Magri, M Candolfi, M F Gottardo, J Ferraris, D Pisera, A Seilicovich. Activation of Nuclear Factor kappa B (NF-¦ÊB) promotes cell proliferation and inhibits apoptosis. In several cell lines, including GH3 pituitary cells, NF-¦ÊB activity is constitutive and sustained. We have previously shown that estrogens inhibit TNF-¦Á- induced NF-¦ÊB nuclear translocation in anterior pituitary cells from primary cultures, suggesting that this mechanism participates in the sensitizing action of estrogens in the pro-apoptotic effect of TNF-¦Á on these cells. Now, we report the effect of estrogens on TNF-¦Á-induced NF-¦ÊB nuclear translocation and apoptosis in GH3 cells. As determined by Western blot, estradiol increased nuclear concentration of NF-¦ÊB/p105, p65 and p50 in GH3 cells (p<0.05, ANOVA). TNF-¦Á increased nuclear concentration of NF-¦ÊB/p65 in GH3 cells incubated with or without estradiol whereas it increased NF-¦ÊB/p50 nuclear concentration only in the absence of estradiol (p<0.05, ANOVA). As determined by flow cytometry, TNF-¦Á increased the percentage of hypodiploid GH3 cells incubated either in the presence or absence of estrogens (C: 5.2 ¡À 1.2%, TNF-¦Á: 11.3 ¡À 0.5 %, E2: 6.7 ¡À 0.1 %, E2+TNF-¦Á: 13.3 ¡À 3.8 %, p<0.01, ANOVA). Since NF-¦ÊB activation does not rescue GH3 cells from TNF-¦Á-induced apoptosis, we investigated whether this pathway is involved in the survival of these cells using BAY 11-7082 (BAY), an inhibitor of NF-¦ÊB nuclear translocation. BAY, at the concentration of 5 mM, decreased GH3 cell viability (C: 0.18 ¡À 0.02, BAY: 0.14 ¡À 0.01, p<0.01, t test) and increased the percentage of TUNEL-positive GH3 cells (C: 0.7 %, BAY: 9.3 %, p<0.01, ¦Ö2). BAY 2.5 mM, a concentration that does not induce apoptosis per se, increased the effect of TNF-¦Á on the percentage of hypodiploid GH3 cells (C: 4.0 ¡À 1.1 %, TNF-¦Á: 11.8 ¡À 2.1 %, BAY: 6.1 ¡À 0.4 %, BAY+TNF-¦Á: 18.2 ¡À 0.1 %, p<0.05, ANOVA). Our results show that NF-¦ÊB activation is required for GH3 cell survival but does not rescue them from TNF-¦Á-induced apoptosis. Also, these data suggest that estrogens may activate NF-¦ÊB pathway to promote the survival of these pituitary tumor cells. st1:*{behavior:url(#ieooui) }