Lymphokine-activated killer T-cell-originated protein kinase phosphorylation of histone H2AX prevents arsenite-induced apoptosis in RPMI7951 melanoma cells.
OBJECTIVE
Arsenic is a valuable therapeutic tool in cancer treatment. Lymphokine-activated killer T-cell-originated protein kinase (TOPK) is highly expressed in cancer cells, but its specific function is still unknown. We investigated the role of TOPK in arsenic-induced apoptosis in RPMI7951 human melanoma cells.


METHODS
Expression of TOPK was evaluated in different melanoma cell lines, and liquid chromatography-tandem mass spectrometry analysis was used to identify proteins binding with TOPK. Immunofluorescence, Western blot, and flow cytometry were used to assess the effect of arsenic on TOPK, histone H2AX, and apoptosis in RPMI7951 cells.


RESULTS
Melanoma cell lines expressing high levels of TOPK were more resistant to arsenite (As(3+))-induced apoptosis. As(3+) treatment induced phosphorylation of TOPK and histone H2AX in RPMI7951 human melanoma cells. Liquid chromatography-tandem mass spectrometry results indicated that TOPK could bind with histone H2AX, and in vitro and in vivo assays confirmed that TOPK binds with and phosphorylates histone H2AX. As(3+) treatment caused phosphorylation of TOPK, which colocalized with phosphorylated histone H2AX in the nucleus. TOPK small interfering RNA cells exhibited a decreased phosphorylation of histone H2AX with As(3+) treatment. As(3+)-induced apoptosis was decreased in H2AX(-/-) cells but increased in TOPK small interfering RNA cells.


CONCLUSIONS
TOPK binds with histone H2AX and inhibits As(3+)-induced apoptosis through phosphorylation of histone H2AX. Melanoma cell lines with high levels of TOPK are more resistant to As(3+)-induced apoptosis. Therefore, inhibition of TOPK activity combined with As(3+) treatment may be helpful in the treatment of melanomas.
Zykova
Tatyana A
TA
Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA.
Zhu
Feng
F
Lu
Chengrong
C
Higgins
LeeAnn
L
Tatsumi
Yasuaki
Y
Abe
Yasuhito
Y
Bode
Ann M
AM
Dong
Zigang
Z
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D018053:Arsenites / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006657:Histones / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D015979:Killer Cells, Lymphokine-Activated / Q000201:enzymology*; D013058:Mass Spectrometry / Q000379:methods; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism*; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism / Q000494:pharmacology; D013329:Structure-Activity Relationship
D018053:Arsenites; C468783:H2AX protein, human; D006657:Histones; D034741:RNA, Small Interfering; D017346:Protein Serine-Threonine Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C409022:PDZ-binding kinase; C015001:arsenite