Forced cytochrome B gene mutation expression induces mitochondrial proliferation and prevents apoptosis in human uroepithelial SV-HUC-1 cells.
Mitochondria encoded Cytochrome B (CYTB) gene mutations were reported in tumors of different anatomic origin but the functional significance of these mutations are not well studied. Earlier, we found a 7-amino acid deletion mutation in the CYTB gene in a primary bladder cancer patient. In the present study, we overexpressed this 7-amino acid deletion mutation of CYTB gene in SV-40 transformed human uroepithelial HUC-1 cells. The nuclear transcribed mitochondrial CYTB (mtCYTB) was targeted into the mitochondria and generated increased copies of mitochondria and mitochondrial COX-I protein in the transfected HUC-1 cells. The proapoptotic protein Bax largely remained confined to the cytoplasm of the mtCYTB transfected HUC-1 cells without release of Cytochrome C. The downstream apoptotic proteins PARP also remained uncleaved along with increased Lamin B1 in the mtCYTB transfected cells. Our results demonstrate that forced overexpression of mtCYTB in transformed human uroepithelial HUC-1 cells triggered mitochondrial proliferation and induction of an antiapoptotic signaling cascade favoring sustained cellular growth. Coding mitochondrial DNA mutations appear to have significant functional contribution in tumor progression.
Dasgupta
Santanu
S
Department of Otolaryngology-Head and Neck Surgery, Division of Head and Neck Cancer Research, Johns Hopkins University, North Baltimore, MD 21231, USA.
Hoque
Mohammad Obaidul
MO
Upadhyay
Sunil
S
Sidransky
David
D
D017209:Apoptosis; D015153:Blotting, Western; D002461:Cell Line, Transformed; D049109:Cell Proliferation; D002478:Cells, Cultured; D045303:Cytochromes b / Q000235:genetics* / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D009154:Mutation / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013539:Simian virus 40; D019311:Staurosporine / Q000494:pharmacology; D014162:Transfection; D019459:Urothelium / Q000378:metabolism* / Q000473:pathology; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
D004272:DNA, Mitochondrial; D004791:Enzyme Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein; D045303:Cytochromes b; D006861:Hydrogen Peroxide; D019311:Staurosporine