2005 Fiscal Year Final Research Report Summary
Gene therapy for hormone-refractory prostate cancer targeting androgen receptor
| Project/Area Number |
16591620
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Urology
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| Research Institution | Keio University |
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Principal Investigator |
OHIGASHI Takashi Keio University, School of Medicine, Assistant Professor, 医学部, 講師 (80185371)
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| Co-Investigator(Kenkyū-buntansha) |
MURAI Masaru Keio University, School of Medicine, Professor, 医学部, 教授 (90101956)
NAKASHIMA Jun Keio University, School of Medicine, Associate Professor, 医学部, 助教授 (10167546)
OYA Mototsugu Keio University, School of Medicine, Assistant Professor, 医学部, 講師 (00213885)
MIYAJIMA Akira Keio University, School of Medicine, Instructor, 医学部, 助手 (90245572)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Prostate carcinoma / Androgen receptor / Cell cycle / Vitamin E |
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| Research Abstract |
Androgen (AR) receptor-positive prostate cancer cells LN-Cap and its androgen-independent subclone LN-AI were used for the experiments. Twenty one or Twenty two base pair-double strand siRNAs containing 2base overhang at 3' site were constructed and inoculated into LNCaP. The siRNA resulted in weaken expression of AR. On the other hand, the proliferation ratio of LNCaP did not significantly change. The poor transfection efficacy seemed to contribute to these results. We have used altered transfection reagents or conditions, however, no satisfying results ware obtained. We also made antisense oligonucleotide for the transcriptional initiation site of each exon. The antisense of exon 5 had a significant effect for inhibiting the cell proliferation of LNCaP. This effect was not observed in AR-negative prostate cancer cells.
To elucidate the AR downstream pathway, we investigated the effects of vitamin E succinate (VES) on AR activity. Vitamin E is an expected chemopreventative agent for prostate cancer. Gene expression profiling using microarray analysis revealed VES caused a down-regulation in AR target genes. On the other hand, the expression of AR was not changed with VES. VES also down-regulated the cell cycle associated protein, microchromosome maintenance families, Cdc-45 and Cdc-6. Twenty μM VES showed growth inhibition in LNCaP and LN-AI cells by 40 % and 42 %, respectively. Cell cycle analysis showed that VES increased G1 cells from 44 % to 60 % in LN-AI cells after 48 h, causing G1/S arrest. However, VES alone showed only weak inhibition of cell growth in AR-negative prostate cancer cells. AS for AR gene also induced similar results in LNCaP cells, suggesting the VES arrested cell cycle via modulating AR activity. The pre-incubation with VES enhanced the cytotoxic effects of paclitaxel on LNCaP and LN-AI cells. We are now confirming the effects of VES plus paclitaxel in tumor bearing nude mice.
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