Insulin-like Growth Factor-1 (IGF-1) Regulates Pheochromocytoma cellular proliferation in vitro and in vivo.

FERNANDEZ MC; VENARA MC; NOWICKI S; ALVAREZ SEDO C; CHEMES H.E.; BARONTINI M B.; PENNISI PA,

Boston, MA

Congreso; 93rd Annual Meeting, Endocrine Society,; 2011

The Endocrine Society

Endocr Rev, Vol. 32 (03_MeetingAbstracts): OR13-6 Copyright © 2011 by The Endocrine Society Insulin-Like Growth Factor-I (IGF-I) Regulates Pheochromocytoma Cellular Proliferation In Vitro and In Vivo Maria Celia Fernandez, MS, Marcela Cristina Venara, MD, PhD, Susana Nowicki, PhD, Cristian Alvarez Sedo, MS, Hector Edgardo Chemes, MD, PhD, Marta Beatriz Barontini, MD, PhD and Patricia Alejandra Pennisi, PhD CEDIE-CONICET, Division Endocrinología (MCF,MCV,SN,CAS,HEC,MBB,PAP), Hospital de Niños Ricardo Gutierrez, Buenos Aires Argentina We have previously shown that IGF-1R expression is increased in malignant compared to benign human pheochromocytoma, and that the mouse pheochromocytoma cell line MPC4/30 expresses a functional IGF-1R. Herein, we demonstrate that MPC4/30 cellular proliferation and BrdU incorporation after 5 days in culture increased significantly with rhIGF-1 stimulation (15±4.5 vs 30.3±2.6 x104cells p<0.05 tTest; 25.7±5.8% vs 34.7±6.0% positive nuclei p<0.01 M.Whitney Test, respectively) while the percentage of apoptotic cells was significantly lower (35.8±2.7% vs 10.8±1.3% cleaved caspase 3 positive cells; 21.3±2.7 vs 6.8±1.3 % of positive cells for TUNEL assay, p<0.01 M.Whitney Test). MPC4/30 cells migration was also stimulated by rhIGF-1 (12±1 vs 18±1 p<0.01, M.Whitney Test). Additionally, MPC4/30 cells formed colonies in soft agar and stimulation with rhIGF-1 increased the number and size of colonies (11±3 vs 26± 3 p<0.01; 217±13μm vs 288±69μm p<0.01 tTest). To evaluate the impact of IGF-1 on pheochromocytoma cellular proliferation in vivo, we generated a mouse model of pheochromocytoma by subcutaneous injection of MPC4/30 cells to control and liver IGF-1 deficient (LID) mice that exhibit 75% reduction in serum IGF-1 levels. We found that six weeks after MPC4/30 cells injection all control mice developed subcutaneous tumors, while only 40% of LID mice showed noticeable tumors. LID mice harboring MPC4/30 and treated daily with 2 mg/kg rhIGF-1 developed tumors as controls. The latency period for tumor growth increased in LID mice as compared to both control and LID mice treated with rhIGF-1 [Median Survival Ratio 2.2 95%CI 1.59-2.81, Chi2 136.5; 1.83 95%CI 1.35-2.32, Chi2 53.17 respectively, p<0.0001 Logrank Test]. LID mice had 10 times lower probability for developing tumors as compared to controls (Hazard Ratio 0.1 95%CI 0.02-0.27), and rhIGF-1 treatment increased this risk 8 times (Hazard Ratio 7.98 95%CI 1.60-67.06). Our data clearly show that cellular proliferation of pheochromocytoma is regulated by IGF-1 both in vitro and in vivo. IGF-1 enhanced proliferation, migration and cell´s ability to grow unattached.