KLF6-SV1 is a novel antiapoptotic protein that targets the BH3-only protein NOXA for degradation and whose inhibition extends survival in an ovarian cancer model.
Defects in apoptosis are not only a hallmark of cancer initiation and progression but can also underlie the development of chemoresistance. How the tightly regulated cascade of protein-protein interactions between members of three competing protein families regulating the apoptotic cascade is subverted in tumor cells is incompletely understood. Here, we show that KLF6-SV1, whose overexpression is associated with poor survival in several different cancers and is an alternatively spliced isoform of the Krüppel-like tumor suppressor KLF6, is a critical prosurvival/antiapoptotic protein. KLF6-SV1 binds the proapoptotic BH3-only protein NOXA, which results in their mutual HDM2-dependent degradation. In turn, this increases the intracellular concentration of the prosurvival binding partner of NOXA, Mcl-1, and effectively blocks apoptosis. In an ovarian cancer model, systemically delivered small interfering RNA against KLF6-SV1 induces spontaneous apoptosis of tumor cells, decreases tumor burden, and restores cisplatin sensitivity in vivo. Moreover, i.p. delivery of siKLF6-SV1 RNA halts ovarian tumor progression and improves median and overall survival (progression-free for >15 months; P < 0.0002) in mice in a dose-dependent manner. Thus, KLF6-SV1 represents a novel regulator of protein interactions in the apoptotic cascade and a therapeutically targetable control point.
Difeo
Analisa
A
Departments of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York, USA.
Huang
Fei
F
Sangodkar
Jaya
J
Terzo
Esteban A
EA
Leake
Devin
D
Narla
Goutham
G
Martignetti
John A
JA
D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D005260:Female; D006801:Humans; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000401:mortality; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000627:therapeutic use*; D016019:Survival Analysis; D013997:Time Factors; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C105465:KLF6 protein, human; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors; C498702:PMAIP1 protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering