The protease inhibitor, elafin, induces p53-dependent apoptosis in human melanoma cells.
Expression of the protease inhibitor elafin is deregulated in several human cancers. However, functions of the protein in cancer are yet to be established. Here, we show that elafin elicits pro-apoptotic effects in melanoma cells but not in normal melanocytes. Elafin triggered the intrinsic apoptotic pathway as evidenced by the increased caspase 9 activity and unaltered caspase 8 activity. Caspase 9-specific siRNA, but not caspase 8-specific siRNA, dramatically abrogated elafin-induced apoptosis. Elevated level of p53 was observed, resulting in increased transcriptional activation and consequent expression of downstream effector molecules (Bax, Puma, Noxa, p21). Moreover, the apoptotic effect of elafin was inhibited by p53-specific siRNA and the p53 inhibitor pifithrin-alpha. Elafin treatment of xenograft mice of melanoma cells led to significantly smaller tumor sizes compared with those of untreated control mice. Immunohistochemical analysis revealed decreased elafin expression in melanoma tissue specimens. Western blot and reverse transcription analyses indicated transcriptional repression of the elafin gene in melanoma cells. Our results collectively indicate that elafin induces apoptosis in melanoma cells through a p53-dependent intrinsic apoptotic pathway, and that repression of elafin expression in melanoma may contribute to disease progression.
Yu
Kyung Sook
KS
Therapeutic Antibody Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea.
Lee
Yangsoon
Y
Kim
Chung Mi
CM
Park
Eui-Chul
EC
Choi
Juhyun
J
Lim
Dae-Sik
DS
Chung
Young-Hwa
YH
Koh
Sang Seok
SS
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation; D053492:Elafin / Q000494:pharmacology*; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011480:Protease Inhibitors / Q000494:pharmacology*; D034741:RNA, Small Interfering; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
D053492:Elafin; D011480:Protease Inhibitors; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53