Abstract
BackgroundTreatment of blast phase chronic myeloid leukemia (BP-CML) remains a challenge, and the median survival is less than 6 months. Because effective treatments are lacking, we studied tight targeting of blast crisis CML cells using adenoviral (Ad) vectors expressing a HSV-TK system under dual control of a specific SUZ12 promoter and an antioxidant response element (ARE).MethodsA potential SUZ12 promoter fragment was designed with bioinformatics databases and identified with a luciferase assay. Next, we cloned the ARE element of the NQO1 gene and developed Ad vectors expressing TK kinase or luciferase under the dual control of a specific SUZ12 promoter and an ARE element. An in vitro transfection assay with Ad-ARE/SUZ12-Luc was used to determine promoter activity of ARE/SUZ12 regulatory element in blast crisis CML cells. After incubating human BP-CML-derived cells with Ad-ARE/SUZ12-TK and ganciclovir, Western blot, CCK8, Immunofluorescent assays and Annexin V assays were conducted to assess the efficacy of an ARE/SUZ12 dual-specific TK/GCV system for BP-CML cell lines.ResultsHere, luciferase data confirmed significantly higher and specificer promoter activity of the ARE/SUZ12 composite component in CML blast crisis-derived cell lines (K562, KCL22, and K562/G01) compared to HepG2 cells, and Ad-AS-TK/GCV system could exhibit enhanced apoptotic effects and decreased cell viability for BP-CML cell lines. Additionally, Ad-AS-TK/GCV system altered expression of cycle-related and apoptosis-related proteins in BP-CML cell lines.ConclusionsThus, ARE/SUZ12 dual targeting TK/GCV system was effective in killing BP-CML cells. Moreover, efficacy and specificity of CML cell eradication were enhanced by synergistic effects of ARE/SUZ12 dual-specific regulation. We conclude that suicide gene-targeted therapy might hold promise for BP-CML treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-015-0139-4) contains supplementary material, which is available to authorized users.
Highlights
Treatment of blast phase chronic myeloid leukemia (BP-Chronic myeloid leukemia (CML)) remains a challenge, and the median survival is less than 6 months
Status of SUZ12 and nuclear factor E2-related factor 2 (Nrf2) in blast crisis phase (BP)-CML mRNA of both SUZ12 and Nrf2 was measured in three blast phase chronic myeloid leukemia (BP-CML)-derived cell types (K562, KCL22, and K562/ G01), and a HepG2 hepatoma cell line
To measure SUZ12 and Nrf2 mRNA in bone marrow mononuclear cells from five healthy donors and six blast phase patients, we used quantitative real-time PCR analysis (qRT-PCR) and observed significant increases in SUZ12 and Nrf2 in blast crisis samples compared to normal donor samples (P
Summary
Treatment of blast phase chronic myeloid leukemia (BP-CML) remains a challenge, and the median survival is less than 6 months. Because effective treatments are lacking, we studied tight targeting of blast crisis CML cells using adenoviral (Ad) vectors expressing a HSV-TK system under dual control of a specific SUZ12 promoter and an antioxidant response element (ARE). The introduction of tyrosine kinase inhibitors (TKIs) has dramatically altered CP-CML outcomes [2], improving 8-year overall survival (OS) from 20 to 85%; BPCML remains a challenge, with a 75% mortality within six Suicide gene therapy has been proved non-invasive and effective for ovarian cancer, central nervous system tumors, and graft-versus-host disease (GVHD) syndrome treatment [4,5,6]. Among suicide gene therapy strategies, the herpes simplex virus thymidine kinase gene (HSVTk)/ganciclovir (GCV) system is the most commonly used for tumor treatment research. The TK/GCV suicide gene system is a powerful strategy for cancer gene therapy
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