Research Article

Gene Therapy (2003) 10, 375–385. doi:10.1038/sj.gt.3301897

Enhancement of thymidine kinase-mediated killing of malignant glioma by BimS, a BH3-only cell death activator

T Yamaguchi1, T Okada2, K Takeuchi3, T Tonda4, M Ohtaki4, S Shinoda1, T Masuzawa1, K Ozawa2 and T Inaba5

  1. 1Department of Surgical Neurology, Center of Molecular Medicine, Jichi Medical School, Tochigi, Japan
  2. 2Division of Genetic Therapeutics, Center of Molecular Medicine, Jichi Medical School, Tochigi, Japan
  3. 3Department of Anatomy, Center of Molecular Medicine, Jichi Medical School, Tochigi, Japan
  4. 4Department of Environmetrics and Biometrics, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan
  5. 5Department of Molecular Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan

Correspondence: Dr T Inaba, Department of Molecular Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan

Received 14 April 2002; Accepted 6 August 2002.

Top

Abstract

Herpes simplex virus thymidine kinase (HSV-tk)/gancyclovir (GCV) therapy has the ability to inhibit tumor formation in animal models but the results of clinical trials have been disappointing. To improve the performance of tk/GCV therapy, we tried combination therapy designed to enhance its cytotoxic effects by introducing genes that induce apoptosis of the tumor cells through different pathways. We concentrated our efforts on the use of Bim, a BH3-only member of death activators in the Bcl-2 superfamily, because Bim is not involved in the pathways through which HSV-tk/GCV therapy induces apoptosis in malignant glioma cells. Among three alternative splicing variants, BimEL, BimL, and BimS, BimS lacks the binding domain for the dynein light chain LC8, which negatively regulates the proapoptotic function of BimEL and BimL. All four malignant glioma cell lines, U251, A172, T-430, and U373 underwent cell death after transfer of BimS using an adenovirus vector (AVC2). Intriguingly, combination of AVC2-BimS with AVC2-tk markedly increased the sensitivity of U251 cells to GCV both in vitro and in vivo. In contrast, AVC2-BimL did not induce significant cell death. These results indicated that BimS had the ability to improve the efficiency of HSV-tk/GCV therapy in the treatment of malignant glioma and suggested that the targeting of different proapoptotic pathways may be a useful strategy for the development of an effective gene therapy approach to treatment.

Keywords:

tk/GCV therapy, malignant glioma, Bim, apoptosis, adenovirus