8817 IGF-II Regulates Magmas A Mitochondrial Protein Required For Cell Viability And ROS Protection

Abstract Disclosure: K. Granados: None. A. Durán: None. F. Almaguel: None. D. De Leon: None. Our laboratory previously showed that Insulin-like growth factor II (IGF-II) promotes cell proliferation, inhibits apoptosis and induces chemoresistance of Breast Cancer (BC) cells. We demonstrated that IGF-II achieves this by inhibiting pro-apoptotic proteins and stimulating anti-apoptotic proteins. Those studies also demonstrated that IGF-II prevented mitochondrial induced apoptosis by inhibiting depolarization of the mitochondrial membrane. Thus, IGF-II regulates the mitochondria to prevent cell death and to promote tumor growth and chemoresistance. Since IGF-II regulates mitochondrial proteins, we decided to assess how IGF-II regulates MAGMAS, a protein located in the inner mitochondrial membrane that is a critical component of a complex that controls mitochondrial protein import and ROS. Of note, MAGMAS was recently identified as being highly expressed in breast cancer, prostate cancer and during early fetal development which parallels IGF-II expression. Immunostaining of TNBC showed high levels of IGF-II and MAGMAS. Thus, our hypothesis is that IGF-II regulates MAGMAS and IGF-II secreting breast cancer cells will express higher levels of MAGMAS. Our preliminary results of rtPCR and Western blotting experiments validated our hypothesis demonstrating that IGF-II regulated the transcription of MAGMAS. To characterize the mechanisms by which IGF-II regulates MAGMAS, we chose the triple negative breast cancer (TNBC) cell line CRL-2335 which we demonstrated produces high levels of IGF-II and MAGMAS. CRL2335 cells were established from an AA TNBC patient and they express high levels of IGF-II and MAGMAS. Confocal microscopy and Western blotting and cellular fractionation were used to assess IGF-II regulation of MAGMAS in TNBC cells. The expression of MAGMAS was analyzed in wild CRL-2335, and IGF-II antisense transfected CRL-2335 cells and compared to cells treated with IGF-II. Results showed that CRL-2335 express high levels of MAGMAS in the mitochondria and blocking the expression of IGF-II by antisense technology significantly decreased MAGMAS. Exogenous IGF-II treatment to the antisense cells increased MAGMAS as demonstrated by Immunofluorescence and WB. Since IGF-II increases the localization of MAGMAS to the mitochondria we propose that IGF-II regulates MAGMAS to protect cancer cells from ROS induced cell death and chemoresistance. Completion of this study will validate IGF-II as a regulator of MAGMAS. Validation of IGF-II regulation of MAGMAS represents an important new tool for the treatment of TNBC. Presentation: 6/2/2024