Common hTERT Promoter Mutations Represent a Novel Therapeutic Target

 描述(申请人提供)：端粒酶逆转录酶(HTERT)是端粒酶的催化亚单位，在人类肿瘤中经常过表达。最近有研究表明，hTERT启动子在恶性黑色素瘤和胶质母细胞瘤(&gt；75%的肿瘤)中通常发生突变。这些突变发生在富含G的区域的四个特定位置，该区域已被证明形成四链DNA并下调hTERT的表达。我们已经证明，这些突变破坏了四链形成的稳定性，导致hTERT表达增加和细胞增殖。用TMPYP4稳定四链结构可以逆转这些变化。对hTERT启动子突变的细胞用链侵袭的寡核苷酸处理后，hTERT的表达下调，并显著抑制转化细胞的生长。这一应用将检验这样一种假设，即序列特异性寡核苷酸稳定突变的hTERT启动子四链结构将导致具有突变序列的细胞下调hTERT并抑制生长(S)。本应用的具体目的是：1.鉴定针对突变或野生型hTERT启动子序列的寡核苷酸的基因和序列特异性。2.研究靶向hTERT启动子的寡核苷酸与靶向药物和标准化疗药物的潜在协同作用。3.在动物模型中研究hTERT链侵袭寡核苷酸的治疗潜力，包括单独治疗和联合靶向治疗。研究结果将具有重要的临床意义，因为抑制hTERT基因表达与多种肿瘤类型有关。此外，拟议的实验将提供关于四链形成在hTERT基因表达调控中的作用的重要新信息。

 DESCRIPTION (provided by applicant): Telomerase reverse transcriptase (hTERT) is a catalytic subunit of the enzyme telomerase which is frequently overexpressed in human tumors. It has recently been shown that the hTERT promoter is commonly mutated in a malignant melanoma and glioblastoma (>75% of tumors). These mutations occur at four specific sites in a G-rich region which has been shown to form quadruplex DNA and to downregulate hTERT expression. We have shown that these mutations destabilize quadruplex-formation resulting in increased hTERT expression and cellular proliferation. Stabilization of the quadruplex structure with TMPYP4 reverses these changes. Treatment of cells in which the hTERT promoter is mutated with "strand-invading" oligonucleotides downregulates hTERT expression and dramatically inhibits the growth of transformed cells. This application will test the hypothesis tht stabilization of the mutated hTERT promoter quadruplex structure by sequence specific oligonucleotides will result in downregulation of hTERT and inhibition of growth by cells with the mutated sequence(s). The Specific Aims of this application are: 1. To characterize the gene and sequence specificity of oligonucleotides targeted to the mutated or wild type hTERT promoter sequences. 2. To characterize the potential synergy of strand invading hTERT promoter targeted oligonucleotides with targeted agents and standard chemotherapy drugs. 3. To characterize the therapeutic potential of hTERT strand invading oligonucleotides in animal models, alone and in conjunction with targeted therapies. The results of the proposed studies will have important clinical implications as inhibition of hTERT gene expression is relevant to a wide variety of tumor types. In addition, the proposed experiments will provide important new information about the role of quadruplex-formation in the regulation of hTERT gene expression.