This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Zykova, T. A. Articles by Dong, Z. Search for Related Content PubMed PubMed Citation Articles by Zykova, T. A. Articles by Dong, Z.

Lymphokine-Activated Killer T-Cell-Originated Protein Kinase Phosphorylation of Histone H2AX Prevents Arsenite-Induced Apoptosis in RPMI7951 Melanoma Cells

Authors' Affiliations: ¹ Hormel Institute, University of Minnesota, Austin, Minnesota; ² Department of Biochemistry, Molecular Biology and Biophysics, St. Paul, Minnesota; and ³ Department of Pathology, Division of Molecular Pathology, Ehime University School of Medicine, Toh-on, Ehime, Japan

Requests for reprints: Zigang Dong, Hormel Institute, University of Minnesota, 801 16th Avenue Northeast, Austin, MN 55912. Phone: 507-437-9600; Fax: 507-437-9606; E-mail: zgdong{at}hi.umn.edu.

Purpose: 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.

Experimental Design: 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 (As³⁺)-induced apoptosis. As³⁺ 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. As³⁺ 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 As³⁺ treatment. As³⁺-induced apoptosis was decreased in H2AX^–/– cells but increased in TOPK small interfering RNA cells.

Conclusions: TOPK binds with histone H2AX and inhibits As³⁺-induced apoptosis through phosphorylation of histone H2AX. Melanoma cell lines with high levels of TOPK are more resistant to As³⁺-induced apoptosis. Therefore, inhibition of TOPK activity combined with As³⁺ treatment may be helpful in the treatment of melanomas.