Application for PTEN Gene Therapy in Prostate Cancer

我们已经证明PTEN的腺病毒基因疗法可以有效地治疗膀胱癌和前列腺癌，并且可以有效地治疗与磷酸化Akt表达相关的药物或放射耐药肿瘤联合化疗或放疗。PTEN是一种肿瘤抑制基因，在磷脂酰肌醇3'-激酶介导的信号转导途径中具有磷酸酶活性，并抑制Akt的激活，Akt是一种参与增殖和抗凋亡途径的丝氨酸-苏氨酸激酶。目前，利用病毒载体进行肿瘤基因治疗存在争议，非病毒基因转移是一种很有前途的方法，但还需要澄清一些问题，如转导效果。我们研制了一种以阳离子明胶微球与质粒DNA偶联的非病毒化合物，是一种新型的基因转移药物，旨在释放质粒DNA，使基因在体内长时间持续表达。在这项研究中，我们首先制备了GelaTen，该GelaTen是阳离子明胶微球（2mg）和PTEN表达载体（100 μg）的缀合物，并检测了GelaTen作为放射联合治疗前列腺癌的疗效。将GelaTen单次直接注射到已建立的裸鼠皮下过表达Bcl-2的PC3前列腺癌肿瘤（PTEN缺失，磷酸化Akt和Bcl-2上调）中，其直径约为5-7mm，与与ss-gal质粒结合（对照）或PBS处理的肿瘤相比，其生长明显降低。免疫组织化学分析显示，GelaTen诱导的肿瘤表达PTEN，磷酸化Akt的量减少，而CTL或PBS处理的肿瘤PTEN呈阴性，磷酸化Akt呈弥漫性阳性。由于PTEN下调磷酸化的Akt和Bcl-2并增加对放射的敏感性，我们在体内探索GelaTen和放射联合治疗。与GelaTen单独治疗相比，GelaTen联合治疗和5gy照射（注射GelaTen后5天）在这些肿瘤中提高了肿瘤生长的体内疗效。这些数据表明，使用基因药物GelaTen进行PTEN基因治疗可以有效治疗PTEN基因改变的前列腺癌。此外，与磷酸化Akt和Bcl-2表达相关的放射耐药肿瘤可以通过GelaTen和放疗有效治疗。少

We have demonstrated that an adenoviral gene therapy of PTEN can effectively treat bladder and prostate cancers, and can be effectively treated tumors which exhibit drug or radiation resistance associated with expression of phosphorylated Akt in combination with chemotherapy or radiotherapy. PTEN is well known as a tumor suppressor gene and has a phosphatase activity in the phosphatidylinositol 3'-kinase mediated signal transduction pathway and inhibits the activation of Akt, a serine-threonine kinase involved in proliferative and anti-apoptotic pathways. These days, using virus vector for cancer gene therapy is controversial, and non-viral gene transfer is a future promising procedure but several problems need to be cleared, such as transduction efficacy. We have developed non-viral compound conjugated with cationized gelatin microsphere and plasmid DNA, which is a new type of gene transfer drug and designed to release plasmid DNA and last the gene expression continuously for a long p … More eriod in vivo. In this study, we originally generated the GelaTen, which is a conjugate with cationized gelatin microsphere (2 mg) and PTEN expression vector (100 μg), and examined the efficacy of GelaTen as a combination therapy with radiation in prostate cancer. Single direct injection of GelaTen into established subcutaneous bcl-2-overexpressing PC3 prostate cancer tumors (PTEN deleted, up-regulation of phosphorylated Akt and Bcl-2) in nude mice, which reached approximately 5-7mm in diameter, resulted in significantly decreased growth compared to the conjugate with ss-gal plasmid (control) or PBS treated tumors. Immunohistochemical analysis showed that tumors inducted with GelaTen expressed PTEN and exhibited decreased amounts of phosphorylated Akt, whereas tumors treated with CTL or PBS were negative for PTEN and diffusely positive for phosphorylated Akt. Since PTEN downregulates phosphorylated Akt and Bcl-2 and increases sensitivity to radiation, we explored combination therapy with GelaTen and radiation in vivo. Combination therapy with GelaTen and 5 Gy irradiation (5 days after GelaTen injection) improved the in vivo efficacy of tumor growth compared to the GelaTen monotherapy alone in these tumors. These data demonstrate that PTEN gene therapy with gene drug GelaTen can effectively treat prostate cancers that have genomic alterations in PTEN. Furthermore, tumors that exhibit radiation resistance associated with expression of phosphorylated Akt and Bcl-2 can be effectively treated with GelaTen and radiotherapy. Less