The antiproliferative effect of Okinawa Habu Apoxin Protein-1 (OHAP-1) on human glioma cells

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 16591449
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Cerebral neurosurgery
• Research Institution: University of the Ryukyus
• Principal Investigator: YOSHII Yoshihiko University of the Ryukyus, Faculty of Medicine, Professor., 医学部, 教授 (50110507)
• Co-Investigator(Kenkyū-buntansha): TSUCHIDA Yukihiro University of the Ryukyus, University Hospital, lecturer, 医学部附属病院, 講師 (90363663)
• Project Period (FY): 2004 – 2006
• Keywords: malignant glioma / Okinawa Habu / snake venom / cytotoxity / cell cycle / Caffeine

Research Abstract

The antiproliferative effect of Okinawa Habu Apoxin Protein-1 (OHAP-1) was examined. OHAP-1 was the protein extracted from the venom of Okinawa Habu (Trimeresurus flavoviridis) and its molecular weight was 55kD. Our recent study has revealed that OHAP-1 induces apoptosis of human glioma cells.
It is well known that p53 protein has an very important role on apoptosis. So we studied the antiproliferative effect of OHAP-1 on some glioma cell lines that had different p53 status, i.e. wild-type p53 or mutant-type p53. We used A172 and U87 for wild-type p53 and U251 and T98G for mutant-type p53. OHAP-1 showed the antiproliferative effect on all cell lines in a dose dependent manner. This effect was seen in U251 and T98G having mutant-type p53.
Caffeine is known to enhance a cytotoxic effect of X-or gamma-rays on various types of cells including gliomas. We tried to see if caffeine has the same effect of OHAP-1 on human glioma cell lines. Glioma cells were cultured with low dose OHAP-1 and then caffeine was added at final concentration of 5mM. Cell cycle with or without caffeine was analyzed using flow cytometer. The antiproliferative effect was enhanced when the cells were co-cultured with caffeine and this enhancement was independent of p53 status. OHAP-1 induced cell cycle arrest on G2/M in T98G. This cell cycle arrest was released after addition of caffeine. These results suggest that DNA damage induced by OHAP-1 could not be repaired and cell death might be induced.
We conclude that OHAP-1 has the antiproliferative effect on human glioma cell lines in dose-dependent but p53-independent manner. This antiproliferative effect is enhanced by caffeine, suggesting adisturbance of DNA repair.